1 # SPDX-License-Identifier: GPL-2.0+
2 #
3 # (C) Copyright 2000 - 2013
4 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
6 Summary:
7 ========
9 This directory contains the source code for U-Boot, a boot loader for
10 Embedded boards based on PowerPC, ARM, MIPS and several other
11 processors, which can be installed in a boot ROM and used to
12 initialize and test the hardware or to download and run application
13 code.
15 The development of U-Boot is closely related to Linux: some parts of
16 the source code originate in the Linux source tree, we have some
17 header files in common, and special provision has been made to
18 support booting of Linux images.
20 Some attention has been paid to make this software easily
21 configurable and extendable. For instance, all monitor commands are
22 implemented with the same call interface, so that it's very easy to
23 add new commands. Also, instead of permanently adding rarely used
24 code (for instance hardware test utilities) to the monitor, you can
25 load and run it dynamically.
28 Status:
29 =======
31 In general, all boards for which a configuration option exists in the
32 Makefile have been tested to some extent and can be considered
33 "working". In fact, many of them are used in production systems.
35 In case of problems see the CHANGELOG file to find out who contributed
36 the specific port. In addition, there are various MAINTAINERS files
37 scattered throughout the U-Boot source identifying the people or
38 companies responsible for various boards and subsystems.
40 Note: As of August, 2010, there is no longer a CHANGELOG file in the
41 actual U-Boot source tree; however, it can be created dynamically
42 from the Git log using:
44 make CHANGELOG
47 Where to get help:
48 ==================
50 In case you have questions about, problems with or contributions for
51 U-Boot, you should send a message to the U-Boot mailing list at
52 <u-boot@lists.denx.de>. There is also an archive of previous traffic
53 on the mailing list - please search the archive before asking FAQ's.
54 Please see http://lists.denx.de/pipermail/u-boot and
55 http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
58 Where to get source code:
59 =========================
61 The U-Boot source code is maintained in the Git repository at
62 git://www.denx.de/git/u-boot.git ; you can browse it online at
63 http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
65 The "snapshot" links on this page allow you to download tarballs of
66 any version you might be interested in. Official releases are also
67 available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
68 directory.
70 Pre-built (and tested) images are available from
71 ftp://ftp.denx.de/pub/u-boot/images/
74 Where we come from:
75 ===================
77 - start from 8xxrom sources
78 - create PPCBoot project (http://sourceforge.net/projects/ppcboot)
79 - clean up code
80 - make it easier to add custom boards
81 - make it possible to add other [PowerPC] CPUs
82 - extend functions, especially:
83 * Provide extended interface to Linux boot loader
84 * S-Record download
85 * network boot
86 * ATA disk / SCSI ... boot
87 - create ARMBoot project (http://sourceforge.net/projects/armboot)
88 - add other CPU families (starting with ARM)
89 - create U-Boot project (http://sourceforge.net/projects/u-boot)
90 - current project page: see http://www.denx.de/wiki/U-Boot
93 Names and Spelling:
94 ===================
96 The "official" name of this project is "Das U-Boot". The spelling
97 "U-Boot" shall be used in all written text (documentation, comments
98 in source files etc.). Example:
100 This is the README file for the U-Boot project.
102 File names etc. shall be based on the string "u-boot". Examples:
104 include/asm-ppc/u-boot.h
106 #include <asm/u-boot.h>
108 Variable names, preprocessor constants etc. shall be either based on
109 the string "u_boot" or on "U_BOOT". Example:
111 U_BOOT_VERSION u_boot_logo
112 IH_OS_U_BOOT u_boot_hush_start
115 Versioning:
116 ===========
118 Starting with the release in October 2008, the names of the releases
119 were changed from numerical release numbers without deeper meaning
120 into a time stamp based numbering. Regular releases are identified by
121 names consisting of the calendar year and month of the release date.
122 Additional fields (if present) indicate release candidates or bug fix
123 releases in "stable" maintenance trees.
125 Examples:
126 U-Boot v2009.11 - Release November 2009
127 U-Boot v2009.11.1 - Release 1 in version November 2009 stable tree
128 U-Boot v2010.09-rc1 - Release candidate 1 for September 2010 release
131 Directory Hierarchy:
132 ====================
134 /arch Architecture specific files
135 /arc Files generic to ARC architecture
136 /arm Files generic to ARM architecture
137 /m68k Files generic to m68k architecture
138 /microblaze Files generic to microblaze architecture
139 /mips Files generic to MIPS architecture
140 /nds32 Files generic to NDS32 architecture
141 /nios2 Files generic to Altera NIOS2 architecture
142 /openrisc Files generic to OpenRISC architecture
143 /powerpc Files generic to PowerPC architecture
144 /riscv Files generic to RISC-V architecture
145 /sandbox Files generic to HW-independent "sandbox"
146 /sh Files generic to SH architecture
147 /x86 Files generic to x86 architecture
148 /api Machine/arch independent API for external apps
149 /board Board dependent files
150 /cmd U-Boot commands functions
151 /common Misc architecture independent functions
152 /configs Board default configuration files
153 /disk Code for disk drive partition handling
154 /doc Documentation (don't expect too much)
155 /drivers Commonly used device drivers
156 /dts Contains Makefile for building internal U-Boot fdt.
157 /examples Example code for standalone applications, etc.
158 /fs Filesystem code (cramfs, ext2, jffs2, etc.)
159 /include Header Files
160 /lib Library routines generic to all architectures
161 /Licenses Various license files
162 /net Networking code
163 /post Power On Self Test
164 /scripts Various build scripts and Makefiles
165 /test Various unit test files
166 /tools Tools to build S-Record or U-Boot images, etc.
168 Software Configuration:
169 =======================
171 Configuration is usually done using C preprocessor defines; the
172 rationale behind that is to avoid dead code whenever possible.
174 There are two classes of configuration variables:
176 * Configuration _OPTIONS_:
177 These are selectable by the user and have names beginning with
178 "CONFIG_".
180 * Configuration _SETTINGS_:
181 These depend on the hardware etc. and should not be meddled with if
182 you don't know what you're doing; they have names beginning with
183 "CONFIG_SYS_".
185 Previously, all configuration was done by hand, which involved creating
186 symbolic links and editing configuration files manually. More recently,
187 U-Boot has added the Kbuild infrastructure used by the Linux kernel,
188 allowing you to use the "make menuconfig" command to configure your
189 build.
192 Selection of Processor Architecture and Board Type:
193 ---------------------------------------------------
195 For all supported boards there are ready-to-use default
196 configurations available; just type "make <board_name>_defconfig".
198 Example: For a TQM823L module type:
200 cd u-boot
201 make TQM823L_defconfig
203 Note: If you're looking for the default configuration file for a board
204 you're sure used to be there but is now missing, check the file
205 doc/README.scrapyard for a list of no longer supported boards.
207 Sandbox Environment:
208 --------------------
210 U-Boot can be built natively to run on a Linux host using the 'sandbox'
211 board. This allows feature development which is not board- or architecture-
212 specific to be undertaken on a native platform. The sandbox is also used to
213 run some of U-Boot's tests.
215 See doc/arch/index.rst for more details.
218 Board Initialisation Flow:
219 --------------------------
221 This is the intended start-up flow for boards. This should apply for both
222 SPL and U-Boot proper (i.e. they both follow the same rules).
224 Note: "SPL" stands for "Secondary Program Loader," which is explained in
225 more detail later in this file.
227 At present, SPL mostly uses a separate code path, but the function names
228 and roles of each function are the same. Some boards or architectures
229 may not conform to this. At least most ARM boards which use
230 CONFIG_SPL_FRAMEWORK conform to this.
232 Execution typically starts with an architecture-specific (and possibly
233 CPU-specific) start.S file, such as:
235 - arch/arm/cpu/armv7/start.S
236 - arch/powerpc/cpu/mpc83xx/start.S
237 - arch/mips/cpu/start.S
239 and so on. From there, three functions are called; the purpose and
240 limitations of each of these functions are described below.
242 lowlevel_init():
243 - purpose: essential init to permit execution to reach board_init_f()
244 - no global_data or BSS
245 - there is no stack (ARMv7 may have one but it will soon be removed)
246 - must not set up SDRAM or use console
247 - must only do the bare minimum to allow execution to continue to
248 board_init_f()
249 - this is almost never needed
250 - return normally from this function
252 board_init_f():
253 - purpose: set up the machine ready for running board_init_r():
254 i.e. SDRAM and serial UART
255 - global_data is available
256 - stack is in SRAM
257 - BSS is not available, so you cannot use global/static variables,
258 only stack variables and global_data
260 Non-SPL-specific notes:
261 - dram_init() is called to set up DRAM. If already done in SPL this
262 can do nothing
264 SPL-specific notes:
265 - you can override the entire board_init_f() function with your own
266 version as needed.
267 - preloader_console_init() can be called here in extremis
268 - should set up SDRAM, and anything needed to make the UART work
269 - these is no need to clear BSS, it will be done by crt0.S
270 - for specific scenarios on certain architectures an early BSS *can*
271 be made available (via CONFIG_SPL_EARLY_BSS by moving the clearing
272 of BSS prior to entering board_init_f()) but doing so is discouraged.
273 Instead it is strongly recommended to architect any code changes
274 or additions such to not depend on the availability of BSS during
275 board_init_f() as indicated in other sections of this README to
276 maintain compatibility and consistency across the entire code base.
277 - must return normally from this function (don't call board_init_r()
278 directly)
280 Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
281 this point the stack and global_data are relocated to below
282 CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
283 memory.
285 board_init_r():
286 - purpose: main execution, common code
287 - global_data is available
288 - SDRAM is available
289 - BSS is available, all static/global variables can be used
290 - execution eventually continues to main_loop()
292 Non-SPL-specific notes:
293 - U-Boot is relocated to the top of memory and is now running from
294 there.
296 SPL-specific notes:
297 - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
298 CONFIG_SPL_STACK_R_ADDR points into SDRAM
299 - preloader_console_init() can be called here - typically this is
300 done by selecting CONFIG_SPL_BOARD_INIT and then supplying a
301 spl_board_init() function containing this call
302 - loads U-Boot or (in falcon mode) Linux
306 Configuration Options:
307 ----------------------
309 Configuration depends on the combination of board and CPU type; all
310 such information is kept in a configuration file
311 "include/configs/<board_name>.h".
313 Example: For a TQM823L module, all configuration settings are in
314 "include/configs/TQM823L.h".
317 Many of the options are named exactly as the corresponding Linux
318 kernel configuration options. The intention is to make it easier to
319 build a config tool - later.
321 - ARM Platform Bus Type(CCI):
322 CoreLink Cache Coherent Interconnect (CCI) is ARM BUS which
323 provides full cache coherency between two clusters of multi-core
324 CPUs and I/O coherency for devices and I/O masters
326 CONFIG_SYS_FSL_HAS_CCI400
328 Defined For SoC that has cache coherent interconnect
329 CCN-400
331 CONFIG_SYS_FSL_HAS_CCN504
333 Defined for SoC that has cache coherent interconnect CCN-504
335 The following options need to be configured:
337 - CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
339 - Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
341 - 85xx CPU Options:
342 CONFIG_SYS_PPC64
344 Specifies that the core is a 64-bit PowerPC implementation (implements
345 the "64" category of the Power ISA). This is necessary for ePAPR
346 compliance, among other possible reasons.
348 CONFIG_SYS_FSL_TBCLK_DIV
350 Defines the core time base clock divider ratio compared to the
351 system clock. On most PQ3 devices this is 8, on newer QorIQ
352 devices it can be 16 or 32. The ratio varies from SoC to Soc.
354 CONFIG_SYS_FSL_PCIE_COMPAT
356 Defines the string to utilize when trying to match PCIe device
357 tree nodes for the given platform.
359 CONFIG_SYS_FSL_ERRATUM_A004510
361 Enables a workaround for erratum A004510. If set,
362 then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
363 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
365 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
366 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
368 Defines one or two SoC revisions (low 8 bits of SVR)
369 for which the A004510 workaround should be applied.
371 The rest of SVR is either not relevant to the decision
372 of whether the erratum is present (e.g. p2040 versus
373 p2041) or is implied by the build target, which controls
374 whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
376 See Freescale App Note 4493 for more information about
377 this erratum.
379 CONFIG_A003399_NOR_WORKAROUND
380 Enables a workaround for IFC erratum A003399. It is only
381 required during NOR boot.
383 CONFIG_A008044_WORKAROUND
384 Enables a workaround for T1040/T1042 erratum A008044. It is only
385 required during NAND boot and valid for Rev 1.0 SoC revision
387 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
389 This is the value to write into CCSR offset 0x18600
390 according to the A004510 workaround.
392 CONFIG_SYS_FSL_DSP_DDR_ADDR
393 This value denotes start offset of DDR memory which is
394 connected exclusively to the DSP cores.
396 CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
397 This value denotes start offset of M2 memory
398 which is directly connected to the DSP core.
400 CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
401 This value denotes start offset of M3 memory which is directly
402 connected to the DSP core.
404 CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
405 This value denotes start offset of DSP CCSR space.
407 CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
408 Single Source Clock is clocking mode present in some of FSL SoC's.
409 In this mode, a single differential clock is used to supply
410 clocks to the sysclock, ddrclock and usbclock.
412 CONFIG_SYS_CPC_REINIT_F
413 This CONFIG is defined when the CPC is configured as SRAM at the
414 time of U-Boot entry and is required to be re-initialized.
416 CONFIG_DEEP_SLEEP
417 Indicates this SoC supports deep sleep feature. If deep sleep is
418 supported, core will start to execute uboot when wakes up.
420 - Generic CPU options:
421 CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
423 Defines the endianess of the CPU. Implementation of those
424 values is arch specific.
426 CONFIG_SYS_FSL_DDR
427 Freescale DDR driver in use. This type of DDR controller is
428 found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core
429 SoCs.
431 CONFIG_SYS_FSL_DDR_ADDR
432 Freescale DDR memory-mapped register base.
434 CONFIG_SYS_FSL_DDR_EMU
435 Specify emulator support for DDR. Some DDR features such as
436 deskew training are not available.
438 CONFIG_SYS_FSL_DDRC_GEN1
439 Freescale DDR1 controller.
441 CONFIG_SYS_FSL_DDRC_GEN2
442 Freescale DDR2 controller.
444 CONFIG_SYS_FSL_DDRC_GEN3
445 Freescale DDR3 controller.
447 CONFIG_SYS_FSL_DDRC_GEN4
448 Freescale DDR4 controller.
450 CONFIG_SYS_FSL_DDRC_ARM_GEN3
451 Freescale DDR3 controller for ARM-based SoCs.
453 CONFIG_SYS_FSL_DDR1
454 Board config to use DDR1. It can be enabled for SoCs with
455 Freescale DDR1 or DDR2 controllers, depending on the board
456 implemetation.
458 CONFIG_SYS_FSL_DDR2
459 Board config to use DDR2. It can be enabled for SoCs with
460 Freescale DDR2 or DDR3 controllers, depending on the board
461 implementation.
463 CONFIG_SYS_FSL_DDR3
464 Board config to use DDR3. It can be enabled for SoCs with
465 Freescale DDR3 or DDR3L controllers.
467 CONFIG_SYS_FSL_DDR3L
468 Board config to use DDR3L. It can be enabled for SoCs with
469 DDR3L controllers.
471 CONFIG_SYS_FSL_DDR4
472 Board config to use DDR4. It can be enabled for SoCs with
473 DDR4 controllers.
475 CONFIG_SYS_FSL_IFC_BE
476 Defines the IFC controller register space as Big Endian
478 CONFIG_SYS_FSL_IFC_LE
479 Defines the IFC controller register space as Little Endian
481 CONFIG_SYS_FSL_IFC_CLK_DIV
482 Defines divider of platform clock(clock input to IFC controller).
484 CONFIG_SYS_FSL_LBC_CLK_DIV
485 Defines divider of platform clock(clock input to eLBC controller).
487 CONFIG_SYS_FSL_PBL_PBI
488 It enables addition of RCW (Power on reset configuration) in built image.
489 Please refer doc/README.pblimage for more details
491 CONFIG_SYS_FSL_PBL_RCW
492 It adds PBI(pre-boot instructions) commands in u-boot build image.
493 PBI commands can be used to configure SoC before it starts the execution.
494 Please refer doc/README.pblimage for more details
496 CONFIG_SYS_FSL_DDR_BE
497 Defines the DDR controller register space as Big Endian
499 CONFIG_SYS_FSL_DDR_LE
500 Defines the DDR controller register space as Little Endian
502 CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
503 Physical address from the view of DDR controllers. It is the
504 same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
505 it could be different for ARM SoCs.
507 CONFIG_SYS_FSL_DDR_INTLV_256B
508 DDR controller interleaving on 256-byte. This is a special
509 interleaving mode, handled by Dickens for Freescale layerscape
510 SoCs with ARM core.
512 CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
513 Number of controllers used as main memory.
515 CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
516 Number of controllers used for other than main memory.
518 CONFIG_SYS_FSL_HAS_DP_DDR
519 Defines the SoC has DP-DDR used for DPAA.
521 CONFIG_SYS_FSL_SEC_BE
522 Defines the SEC controller register space as Big Endian
524 CONFIG_SYS_FSL_SEC_LE
525 Defines the SEC controller register space as Little Endian
527 - MIPS CPU options:
528 CONFIG_SYS_INIT_SP_OFFSET
530 Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
531 pointer. This is needed for the temporary stack before
532 relocation.
534 CONFIG_XWAY_SWAP_BYTES
536 Enable compilation of tools/xway-swap-bytes needed for Lantiq
537 XWAY SoCs for booting from NOR flash. The U-Boot image needs to
538 be swapped if a flash programmer is used.
540 - ARM options:
541 CONFIG_SYS_EXCEPTION_VECTORS_HIGH
543 Select high exception vectors of the ARM core, e.g., do not
544 clear the V bit of the c1 register of CP15.
546 COUNTER_FREQUENCY
547 Generic timer clock source frequency.
549 COUNTER_FREQUENCY_REAL
550 Generic timer clock source frequency if the real clock is
551 different from COUNTER_FREQUENCY, and can only be determined
552 at run time.
554 - Tegra SoC options:
555 CONFIG_TEGRA_SUPPORT_NON_SECURE
557 Support executing U-Boot in non-secure (NS) mode. Certain
558 impossible actions will be skipped if the CPU is in NS mode,
559 such as ARM architectural timer initialization.
561 - Linux Kernel Interface:
562 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
564 When transferring memsize parameter to Linux, some versions
565 expect it to be in bytes, others in MB.
566 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
568 CONFIG_OF_LIBFDT
570 New kernel versions are expecting firmware settings to be
571 passed using flattened device trees (based on open firmware
572 concepts).
574 CONFIG_OF_LIBFDT
575 * New libfdt-based support
576 * Adds the "fdt" command
577 * The bootm command automatically updates the fdt
579 OF_TBCLK - The timebase frequency.
580 OF_STDOUT_PATH - The path to the console device
582 boards with QUICC Engines require OF_QE to set UCC MAC
583 addresses
585 CONFIG_OF_BOARD_SETUP
587 Board code has addition modification that it wants to make
588 to the flat device tree before handing it off to the kernel
590 CONFIG_OF_SYSTEM_SETUP
592 Other code has addition modification that it wants to make
593 to the flat device tree before handing it off to the kernel.
594 This causes ft_system_setup() to be called before booting
595 the kernel.
597 CONFIG_OF_IDE_FIXUP
599 U-Boot can detect if an IDE device is present or not.
600 If not, and this new config option is activated, U-Boot
601 removes the ATA node from the DTS before booting Linux,
602 so the Linux IDE driver does not probe the device and
603 crash. This is needed for buggy hardware (uc101) where
604 no pull down resistor is connected to the signal IDE5V_DD7.
606 CONFIG_MACH_TYPE [relevant for ARM only][mandatory]
608 This setting is mandatory for all boards that have only one
609 machine type and must be used to specify the machine type
610 number as it appears in the ARM machine registry
611 (see http://www.arm.linux.org.uk/developer/machines/).
612 Only boards that have multiple machine types supported
613 in a single configuration file and the machine type is
614 runtime discoverable, do not have to use this setting.
616 - vxWorks boot parameters:
618 bootvx constructs a valid bootline using the following
619 environments variables: bootdev, bootfile, ipaddr, netmask,
620 serverip, gatewayip, hostname, othbootargs.
621 It loads the vxWorks image pointed bootfile.
623 Note: If a "bootargs" environment is defined, it will overwride
624 the defaults discussed just above.
626 - Cache Configuration:
627 CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
629 - Cache Configuration for ARM:
630 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
631 controller
632 CONFIG_SYS_PL310_BASE - Physical base address of PL310
633 controller register space
635 - Serial Ports:
636 CONFIG_PL010_SERIAL
638 Define this if you want support for Amba PrimeCell PL010 UARTs.
640 CONFIG_PL011_SERIAL
642 Define this if you want support for Amba PrimeCell PL011 UARTs.
644 CONFIG_PL011_CLOCK
646 If you have Amba PrimeCell PL011 UARTs, set this variable to
647 the clock speed of the UARTs.
649 CONFIG_PL01x_PORTS
651 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
652 define this to a list of base addresses for each (supported)
653 port. See e.g. include/configs/versatile.h
655 CONFIG_SERIAL_HW_FLOW_CONTROL
657 Define this variable to enable hw flow control in serial driver.
658 Current user of this option is drivers/serial/nsl16550.c driver
660 - Autoboot Command:
661 CONFIG_BOOTCOMMAND
662 Only needed when CONFIG_BOOTDELAY is enabled;
663 define a command string that is automatically executed
664 when no character is read on the console interface
665 within "Boot Delay" after reset.
667 CONFIG_RAMBOOT and CONFIG_NFSBOOT
668 The value of these goes into the environment as
669 "ramboot" and "nfsboot" respectively, and can be used
670 as a convenience, when switching between booting from
671 RAM and NFS.
673 - Serial Download Echo Mode:
674 CONFIG_LOADS_ECHO
675 If defined to 1, all characters received during a
676 serial download (using the "loads" command) are
677 echoed back. This might be needed by some terminal
678 emulations (like "cu"), but may as well just take
679 time on others. This setting #define's the initial
680 value of the "loads_echo" environment variable.
682 - Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
683 CONFIG_KGDB_BAUDRATE
684 Select one of the baudrates listed in
685 CONFIG_SYS_BAUDRATE_TABLE, see below.
687 - Removal of commands
688 If no commands are needed to boot, you can disable
689 CONFIG_CMDLINE to remove them. In this case, the command line
690 will not be available, and when U-Boot wants to execute the
691 boot command (on start-up) it will call board_run_command()
692 instead. This can reduce image size significantly for very
693 simple boot procedures.
695 - Regular expression support:
696 CONFIG_REGEX
697 If this variable is defined, U-Boot is linked against
698 the SLRE (Super Light Regular Expression) library,
699 which adds regex support to some commands, as for
700 example "env grep" and "setexpr".
702 - Device tree:
703 CONFIG_OF_CONTROL
704 If this variable is defined, U-Boot will use a device tree
705 to configure its devices, instead of relying on statically
706 compiled #defines in the board file. This option is
707 experimental and only available on a few boards. The device
708 tree is available in the global data as gd->fdt_blob.
710 U-Boot needs to get its device tree from somewhere. This can
711 be done using one of the three options below:
713 CONFIG_OF_EMBED
714 If this variable is defined, U-Boot will embed a device tree
715 binary in its image. This device tree file should be in the
716 board directory and called <soc>-<board>.dts. The binary file
717 is then picked up in board_init_f() and made available through
718 the global data structure as gd->fdt_blob.
720 CONFIG_OF_SEPARATE
721 If this variable is defined, U-Boot will build a device tree
722 binary. It will be called u-boot.dtb. Architecture-specific
723 code will locate it at run-time. Generally this works by:
725 cat u-boot.bin u-boot.dtb >image.bin
727 and in fact, U-Boot does this for you, creating a file called
728 u-boot-dtb.bin which is useful in the common case. You can
729 still use the individual files if you need something more
730 exotic.
732 CONFIG_OF_BOARD
733 If this variable is defined, U-Boot will use the device tree
734 provided by the board at runtime instead of embedding one with
735 the image. Only boards defining board_fdt_blob_setup() support
736 this option (see include/fdtdec.h file).
738 - Watchdog:
739 CONFIG_WATCHDOG
740 If this variable is defined, it enables watchdog
741 support for the SoC. There must be support in the SoC
742 specific code for a watchdog. For the 8xx
743 CPUs, the SIU Watchdog feature is enabled in the SYPCR
744 register. When supported for a specific SoC is
745 available, then no further board specific code should
746 be needed to use it.
748 CONFIG_HW_WATCHDOG
749 When using a watchdog circuitry external to the used
750 SoC, then define this variable and provide board
751 specific code for the "hw_watchdog_reset" function.
753 - Real-Time Clock:
755 When CONFIG_CMD_DATE is selected, the type of the RTC
756 has to be selected, too. Define exactly one of the
757 following options:
759 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
760 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
761 CONFIG_RTC_MC146818 - use MC146818 RTC
762 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
763 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
764 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
765 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
766 CONFIG_RTC_DS164x - use Dallas DS164x RTC
767 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
768 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
769 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
770 CONFIG_SYS_RV3029_TCR - enable trickle charger on
771 RV3029 RTC.
773 Note that if the RTC uses I2C, then the I2C interface
774 must also be configured. See I2C Support, below.
776 - GPIO Support:
777 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
779 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
780 chip-ngpio pairs that tell the PCA953X driver the number of
781 pins supported by a particular chip.
783 Note that if the GPIO device uses I2C, then the I2C interface
784 must also be configured. See I2C Support, below.
786 - I/O tracing:
787 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
788 accesses and can checksum them or write a list of them out
789 to memory. See the 'iotrace' command for details. This is
790 useful for testing device drivers since it can confirm that
791 the driver behaves the same way before and after a code
792 change. Currently this is supported on sandbox and arm. To
793 add support for your architecture, add '#include <iotrace.h>'
794 to the bottom of arch/<arch>/include/asm/io.h and test.
796 Example output from the 'iotrace stats' command is below.
797 Note that if the trace buffer is exhausted, the checksum will
798 still continue to operate.
800 iotrace is enabled
801 Start: 10000000 (buffer start address)
802 Size: 00010000 (buffer size)
803 Offset: 00000120 (current buffer offset)
804 Output: 10000120 (start + offset)
805 Count: 00000018 (number of trace records)
806 CRC32: 9526fb66 (CRC32 of all trace records)
808 - Timestamp Support:
810 When CONFIG_TIMESTAMP is selected, the timestamp
811 (date and time) of an image is printed by image
812 commands like bootm or iminfo. This option is
813 automatically enabled when you select CONFIG_CMD_DATE .
815 - Partition Labels (disklabels) Supported:
816 Zero or more of the following:
817 CONFIG_MAC_PARTITION Apple's MacOS partition table.
818 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
819 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
820 bootloader. Note 2TB partition limit; see
821 disk/part_efi.c
822 CONFIG_SCSI) you must configure support for at
823 least one non-MTD partition type as well.
825 - IDE Reset method:
826 CONFIG_IDE_RESET_ROUTINE - this is defined in several
827 board configurations files but used nowhere!
829 CONFIG_IDE_RESET - is this is defined, IDE Reset will
830 be performed by calling the function
831 ide_set_reset(int reset)
832 which has to be defined in a board specific file
834 - ATAPI Support:
835 CONFIG_ATAPI
837 Set this to enable ATAPI support.
839 - LBA48 Support
840 CONFIG_LBA48
842 Set this to enable support for disks larger than 137GB
843 Also look at CONFIG_SYS_64BIT_LBA.
844 Whithout these , LBA48 support uses 32bit variables and will 'only'
845 support disks up to 2.1TB.
847 CONFIG_SYS_64BIT_LBA:
848 When enabled, makes the IDE subsystem use 64bit sector addresses.
849 Default is 32bit.
851 - SCSI Support:
852 CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
853 CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
854 CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
855 maximum numbers of LUNs, SCSI ID's and target
856 devices.
858 The environment variable 'scsidevs' is set to the number of
859 SCSI devices found during the last scan.
861 - NETWORK Support (PCI):
862 CONFIG_E1000
863 Support for Intel 8254x/8257x gigabit chips.
865 CONFIG_E1000_SPI
866 Utility code for direct access to the SPI bus on Intel 8257x.
867 This does not do anything useful unless you set at least one
868 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
870 CONFIG_E1000_SPI_GENERIC
871 Allow generic access to the SPI bus on the Intel 8257x, for
872 example with the "sspi" command.
874 CONFIG_TULIP
875 Support for Digital 2114x chips.
877 CONFIG_NATSEMI
878 Support for National dp83815 chips.
880 CONFIG_NS8382X
881 Support for National dp8382[01] gigabit chips.
883 - NETWORK Support (other):
885 CONFIG_DRIVER_AT91EMAC
886 Support for AT91RM9200 EMAC.
888 CONFIG_RMII
889 Define this to use reduced MII inteface
891 CONFIG_DRIVER_AT91EMAC_QUIET
892 If this defined, the driver is quiet.
893 The driver doen't show link status messages.
895 CONFIG_CALXEDA_XGMAC
896 Support for the Calxeda XGMAC device
898 CONFIG_LAN91C96
899 Support for SMSC's LAN91C96 chips.
901 CONFIG_LAN91C96_USE_32_BIT
902 Define this to enable 32 bit addressing
904 CONFIG_SMC91111
905 Support for SMSC's LAN91C111 chip
907 CONFIG_SMC91111_BASE
908 Define this to hold the physical address
909 of the device (I/O space)
911 CONFIG_SMC_USE_32_BIT
912 Define this if data bus is 32 bits
914 CONFIG_SMC_USE_IOFUNCS
915 Define this to use i/o functions instead of macros
916 (some hardware wont work with macros)
918 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
919 Define this if you have more then 3 PHYs.
921 CONFIG_FTGMAC100
922 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
924 CONFIG_FTGMAC100_EGIGA
925 Define this to use GE link update with gigabit PHY.
926 Define this if FTGMAC100 is connected to gigabit PHY.
927 If your system has 10/100 PHY only, it might not occur
928 wrong behavior. Because PHY usually return timeout or
929 useless data when polling gigabit status and gigabit
930 control registers. This behavior won't affect the
931 correctnessof 10/100 link speed update.
933 CONFIG_SH_ETHER
934 Support for Renesas on-chip Ethernet controller
936 CONFIG_SH_ETHER_USE_PORT
937 Define the number of ports to be used
939 CONFIG_SH_ETHER_PHY_ADDR
940 Define the ETH PHY's address
942 CONFIG_SH_ETHER_CACHE_WRITEBACK
943 If this option is set, the driver enables cache flush.
945 - TPM Support:
946 CONFIG_TPM
947 Support TPM devices.
949 CONFIG_TPM_TIS_INFINEON
950 Support for Infineon i2c bus TPM devices. Only one device
951 per system is supported at this time.
953 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
954 Define the burst count bytes upper limit
956 CONFIG_TPM_ST33ZP24
957 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
959 CONFIG_TPM_ST33ZP24_I2C
960 Support for STMicroelectronics ST33ZP24 I2C devices.
961 Requires TPM_ST33ZP24 and I2C.
963 CONFIG_TPM_ST33ZP24_SPI
964 Support for STMicroelectronics ST33ZP24 SPI devices.
965 Requires TPM_ST33ZP24 and SPI.
967 CONFIG_TPM_ATMEL_TWI
968 Support for Atmel TWI TPM device. Requires I2C support.
970 CONFIG_TPM_TIS_LPC
971 Support for generic parallel port TPM devices. Only one device
972 per system is supported at this time.
974 CONFIG_TPM_TIS_BASE_ADDRESS
975 Base address where the generic TPM device is mapped
976 to. Contemporary x86 systems usually map it at
977 0xfed40000.
979 CONFIG_TPM
980 Define this to enable the TPM support library which provides
981 functional interfaces to some TPM commands.
982 Requires support for a TPM device.
984 CONFIG_TPM_AUTH_SESSIONS
985 Define this to enable authorized functions in the TPM library.
986 Requires CONFIG_TPM and CONFIG_SHA1.
988 - USB Support:
989 At the moment only the UHCI host controller is
990 supported (PIP405, MIP405); define
991 CONFIG_USB_UHCI to enable it.
992 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
993 and define CONFIG_USB_STORAGE to enable the USB
994 storage devices.
995 Note:
996 Supported are USB Keyboards and USB Floppy drives
997 (TEAC FD-05PUB).
999 CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1000 txfilltuning field in the EHCI controller on reset.
1002 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
1003 HW module registers.
1005 - USB Device:
1006 Define the below if you wish to use the USB console.
1007 Once firmware is rebuilt from a serial console issue the
1008 command "setenv stdin usbtty; setenv stdout usbtty" and
1009 attach your USB cable. The Unix command "dmesg" should print
1010 it has found a new device. The environment variable usbtty
1011 can be set to gserial or cdc_acm to enable your device to
1012 appear to a USB host as a Linux gserial device or a
1013 Common Device Class Abstract Control Model serial device.
1014 If you select usbtty = gserial you should be able to enumerate
1015 a Linux host by
1016 # modprobe usbserial vendor=0xVendorID product=0xProductID
1017 else if using cdc_acm, simply setting the environment
1018 variable usbtty to be cdc_acm should suffice. The following
1019 might be defined in YourBoardName.h
1021 CONFIG_USB_DEVICE
1022 Define this to build a UDC device
1024 CONFIG_USB_TTY
1025 Define this to have a tty type of device available to
1026 talk to the UDC device
1028 CONFIG_USBD_HS
1029 Define this to enable the high speed support for usb
1030 device and usbtty. If this feature is enabled, a routine
1031 int is_usbd_high_speed(void)
1032 also needs to be defined by the driver to dynamically poll
1033 whether the enumeration has succeded at high speed or full
1034 speed.
1036 CONFIG_SYS_CONSOLE_IS_IN_ENV
1037 Define this if you want stdin, stdout &/or stderr to
1038 be set to usbtty.
1040 If you have a USB-IF assigned VendorID then you may wish to
1041 define your own vendor specific values either in BoardName.h
1042 or directly in usbd_vendor_info.h. If you don't define
1043 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1044 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1045 should pretend to be a Linux device to it's target host.
1047 CONFIG_USBD_MANUFACTURER
1048 Define this string as the name of your company for
1049 - CONFIG_USBD_MANUFACTURER "my company"
1051 CONFIG_USBD_PRODUCT_NAME
1052 Define this string as the name of your product
1053 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
1055 CONFIG_USBD_VENDORID
1056 Define this as your assigned Vendor ID from the USB
1057 Implementors Forum. This *must* be a genuine Vendor ID
1058 to avoid polluting the USB namespace.
1059 - CONFIG_USBD_VENDORID 0xFFFF
1061 CONFIG_USBD_PRODUCTID
1062 Define this as the unique Product ID
1063 for your device
1064 - CONFIG_USBD_PRODUCTID 0xFFFF
1066 - ULPI Layer Support:
1067 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1068 the generic ULPI layer. The generic layer accesses the ULPI PHY
1069 via the platform viewport, so you need both the genric layer and
1070 the viewport enabled. Currently only Chipidea/ARC based
1071 viewport is supported.
1072 To enable the ULPI layer support, define CONFIG_USB_ULPI and
1073 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1074 If your ULPI phy needs a different reference clock than the
1075 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1076 the appropriate value in Hz.
1078 - MMC Support:
1079 The MMC controller on the Intel PXA is supported. To
1080 enable this define CONFIG_MMC. The MMC can be
1081 accessed from the boot prompt by mapping the device
1082 to physical memory similar to flash. Command line is
1083 enabled with CONFIG_CMD_MMC. The MMC driver also works with
1084 the FAT fs. This is enabled with CONFIG_CMD_FAT.
1086 CONFIG_SH_MMCIF
1087 Support for Renesas on-chip MMCIF controller
1089 CONFIG_SH_MMCIF_ADDR
1090 Define the base address of MMCIF registers
1092 CONFIG_SH_MMCIF_CLK
1093 Define the clock frequency for MMCIF
1095 - USB Device Firmware Update (DFU) class support:
1096 CONFIG_DFU_OVER_USB
1097 This enables the USB portion of the DFU USB class
1099 CONFIG_DFU_NAND
1100 This enables support for exposing NAND devices via DFU.
1102 CONFIG_DFU_RAM
1103 This enables support for exposing RAM via DFU.
1104 Note: DFU spec refer to non-volatile memory usage, but
1105 allow usages beyond the scope of spec - here RAM usage,
1106 one that would help mostly the developer.
1108 CONFIG_SYS_DFU_DATA_BUF_SIZE
1109 Dfu transfer uses a buffer before writing data to the
1110 raw storage device. Make the size (in bytes) of this buffer
1111 configurable. The size of this buffer is also configurable
1112 through the "dfu_bufsiz" environment variable.
1114 CONFIG_SYS_DFU_MAX_FILE_SIZE
1115 When updating files rather than the raw storage device,
1116 we use a static buffer to copy the file into and then write
1117 the buffer once we've been given the whole file. Define
1118 this to the maximum filesize (in bytes) for the buffer.
1119 Default is 4 MiB if undefined.
1121 DFU_DEFAULT_POLL_TIMEOUT
1122 Poll timeout [ms], is the timeout a device can send to the
1123 host. The host must wait for this timeout before sending
1124 a subsequent DFU_GET_STATUS request to the device.
1126 DFU_MANIFEST_POLL_TIMEOUT
1127 Poll timeout [ms], which the device sends to the host when
1128 entering dfuMANIFEST state. Host waits this timeout, before
1129 sending again an USB request to the device.
1131 - Journaling Flash filesystem support:
1132 CONFIG_JFFS2_NAND
1133 Define these for a default partition on a NAND device
1135 CONFIG_SYS_JFFS2_FIRST_SECTOR,
1136 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1137 Define these for a default partition on a NOR device
1139 - Keyboard Support:
1140 See Kconfig help for available keyboard drivers.
1142 CONFIG_KEYBOARD
1144 Define this to enable a custom keyboard support.
1145 This simply calls drv_keyboard_init() which must be
1146 defined in your board-specific files. This option is deprecated
1147 and is only used by novena. For new boards, use driver model
1148 instead.
1150 - Video support:
1151 CONFIG_FSL_DIU_FB
1152 Enable the Freescale DIU video driver. Reference boards for
1153 SOCs that have a DIU should define this macro to enable DIU
1154 support, and should also define these other macros:
1156 CONFIG_SYS_DIU_ADDR
1157 CONFIG_VIDEO
1158 CONFIG_CFB_CONSOLE
1159 CONFIG_VIDEO_SW_CURSOR
1160 CONFIG_VGA_AS_SINGLE_DEVICE
1161 CONFIG_VIDEO_LOGO
1162 CONFIG_VIDEO_BMP_LOGO
1164 The DIU driver will look for the 'video-mode' environment
1165 variable, and if defined, enable the DIU as a console during
1166 boot. See the documentation file doc/README.video for a
1167 description of this variable.
1169 - LCD Support: CONFIG_LCD
1171 Define this to enable LCD support (for output to LCD
1172 display); also select one of the supported displays
1173 by defining one of these:
1175 CONFIG_ATMEL_LCD:
1177 HITACHI TX09D70VM1CCA, 3.5", 240x320.
1179 CONFIG_NEC_NL6448AC33:
1181 NEC NL6448AC33-18. Active, color, single scan.
1183 CONFIG_NEC_NL6448BC20
1185 NEC NL6448BC20-08. 6.5", 640x480.
1186 Active, color, single scan.
1188 CONFIG_NEC_NL6448BC33_54
1190 NEC NL6448BC33-54. 10.4", 640x480.
1191 Active, color, single scan.
1193 CONFIG_SHARP_16x9
1195 Sharp 320x240. Active, color, single scan.
1196 It isn't 16x9, and I am not sure what it is.
1198 CONFIG_SHARP_LQ64D341
1200 Sharp LQ64D341 display, 640x480.
1201 Active, color, single scan.
1203 CONFIG_HLD1045
1205 HLD1045 display, 640x480.
1206 Active, color, single scan.
1208 CONFIG_OPTREX_BW
1210 Optrex CBL50840-2 NF-FW 99 22 M5
1211 or
1212 Hitachi LMG6912RPFC-00T
1213 or
1214 Hitachi SP14Q002
1216 320x240. Black & white.
1218 CONFIG_LCD_ALIGNMENT
1220 Normally the LCD is page-aligned (typically 4KB). If this is
1221 defined then the LCD will be aligned to this value instead.
1222 For ARM it is sometimes useful to use MMU_SECTION_SIZE
1223 here, since it is cheaper to change data cache settings on
1224 a per-section basis.
1227 CONFIG_LCD_ROTATION
1229 Sometimes, for example if the display is mounted in portrait
1230 mode or even if it's mounted landscape but rotated by 180degree,
1231 we need to rotate our content of the display relative to the
1232 framebuffer, so that user can read the messages which are
1233 printed out.
1234 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1235 initialized with a given rotation from "vl_rot" out of
1236 "vidinfo_t" which is provided by the board specific code.
1237 The value for vl_rot is coded as following (matching to
1238 fbcon=rotate:<n> linux-kernel commandline):
1239 0 = no rotation respectively 0 degree
1240 1 = 90 degree rotation
1241 2 = 180 degree rotation
1242 3 = 270 degree rotation
1244 If CONFIG_LCD_ROTATION is not defined, the console will be
1245 initialized with 0degree rotation.
1247 CONFIG_LCD_BMP_RLE8
1249 Support drawing of RLE8-compressed bitmaps on the LCD.
1251 CONFIG_I2C_EDID
1253 Enables an 'i2c edid' command which can read EDID
1254 information over I2C from an attached LCD display.
1256 - Splash Screen Support: CONFIG_SPLASH_SCREEN
1258 If this option is set, the environment is checked for
1259 a variable "splashimage". If found, the usual display
1260 of logo, copyright and system information on the LCD
1261 is suppressed and the BMP image at the address
1262 specified in "splashimage" is loaded instead. The
1263 console is redirected to the "nulldev", too. This
1264 allows for a "silent" boot where a splash screen is
1265 loaded very quickly after power-on.
1267 CONFIG_SPLASHIMAGE_GUARD
1269 If this option is set, then U-Boot will prevent the environment
1270 variable "splashimage" from being set to a problematic address
1271 (see doc/README.displaying-bmps).
1272 This option is useful for targets where, due to alignment
1273 restrictions, an improperly aligned BMP image will cause a data
1274 abort. If you think you will not have problems with unaligned
1275 accesses (for example because your toolchain prevents them)
1276 there is no need to set this option.
1278 CONFIG_SPLASH_SCREEN_ALIGN
1280 If this option is set the splash image can be freely positioned
1281 on the screen. Environment variable "splashpos" specifies the
1282 position as "x,y". If a positive number is given it is used as
1283 number of pixel from left/top. If a negative number is given it
1284 is used as number of pixel from right/bottom. You can also
1285 specify 'm' for centering the image.
1287 Example:
1288 setenv splashpos m,m
1289 => image at center of screen
1291 setenv splashpos 30,20
1292 => image at x = 30 and y = 20
1294 setenv splashpos -10,m
1295 => vertically centered image
1296 at x = dspWidth - bmpWidth - 9
1298 - Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1300 If this option is set, additionally to standard BMP
1301 images, gzipped BMP images can be displayed via the
1302 splashscreen support or the bmp command.
1304 - Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1306 If this option is set, 8-bit RLE compressed BMP images
1307 can be displayed via the splashscreen support or the
1308 bmp command.
1310 - MII/PHY support:
1311 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1313 The clock frequency of the MII bus
1315 CONFIG_PHY_RESET_DELAY
1317 Some PHY like Intel LXT971A need extra delay after
1318 reset before any MII register access is possible.
1319 For such PHY, set this option to the usec delay
1320 required. (minimum 300usec for LXT971A)
1322 CONFIG_PHY_CMD_DELAY (ppc4xx)
1324 Some PHY like Intel LXT971A need extra delay after
1325 command issued before MII status register can be read
1327 - IP address:
1328 CONFIG_IPADDR
1330 Define a default value for the IP address to use for
1331 the default Ethernet interface, in case this is not
1332 determined through e.g. bootp.
1333 (Environment variable "ipaddr")
1335 - Server IP address:
1336 CONFIG_SERVERIP
1338 Defines a default value for the IP address of a TFTP
1339 server to contact when using the "tftboot" command.
1340 (Environment variable "serverip")
1342 CONFIG_KEEP_SERVERADDR
1344 Keeps the server's MAC address, in the env 'serveraddr'
1345 for passing to bootargs (like Linux's netconsole option)
1347 - Gateway IP address:
1348 CONFIG_GATEWAYIP
1350 Defines a default value for the IP address of the
1351 default router where packets to other networks are
1352 sent to.
1353 (Environment variable "gatewayip")
1355 - Subnet mask:
1356 CONFIG_NETMASK
1358 Defines a default value for the subnet mask (or
1359 routing prefix) which is used to determine if an IP
1360 address belongs to the local subnet or needs to be
1361 forwarded through a router.
1362 (Environment variable "netmask")
1364 - BOOTP Recovery Mode:
1365 CONFIG_BOOTP_RANDOM_DELAY
1367 If you have many targets in a network that try to
1368 boot using BOOTP, you may want to avoid that all
1369 systems send out BOOTP requests at precisely the same
1370 moment (which would happen for instance at recovery
1371 from a power failure, when all systems will try to
1372 boot, thus flooding the BOOTP server. Defining
1373 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1374 inserted before sending out BOOTP requests. The
1375 following delays are inserted then:
1377 1st BOOTP request: delay 0 ... 1 sec
1378 2nd BOOTP request: delay 0 ... 2 sec
1379 3rd BOOTP request: delay 0 ... 4 sec
1380 4th and following
1381 BOOTP requests: delay 0 ... 8 sec
1383 CONFIG_BOOTP_ID_CACHE_SIZE
1385 BOOTP packets are uniquely identified using a 32-bit ID. The
1386 server will copy the ID from client requests to responses and
1387 U-Boot will use this to determine if it is the destination of
1388 an incoming response. Some servers will check that addresses
1389 aren't in use before handing them out (usually using an ARP
1390 ping) and therefore take up to a few hundred milliseconds to
1391 respond. Network congestion may also influence the time it
1392 takes for a response to make it back to the client. If that
1393 time is too long, U-Boot will retransmit requests. In order
1394 to allow earlier responses to still be accepted after these
1395 retransmissions, U-Boot's BOOTP client keeps a small cache of
1396 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1397 cache. The default is to keep IDs for up to four outstanding
1398 requests. Increasing this will allow U-Boot to accept offers
1399 from a BOOTP client in networks with unusually high latency.
1401 - DHCP Advanced Options:
1402 You can fine tune the DHCP functionality by defining
1403 CONFIG_BOOTP_* symbols:
1405 CONFIG_BOOTP_NISDOMAIN
1406 CONFIG_BOOTP_BOOTFILESIZE
1407 CONFIG_BOOTP_SEND_HOSTNAME
1408 CONFIG_BOOTP_NTPSERVER
1409 CONFIG_BOOTP_TIMEOFFSET
1410 CONFIG_BOOTP_VENDOREX
1411 CONFIG_BOOTP_MAY_FAIL
1413 CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1414 environment variable, not the BOOTP server.
1416 CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1417 after the configured retry count, the call will fail
1418 instead of starting over. This can be used to fail over
1419 to Link-local IP address configuration if the DHCP server
1420 is not available.
1422 CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1423 to do a dynamic update of a DNS server. To do this, they
1424 need the hostname of the DHCP requester.
1425 If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1426 of the "hostname" environment variable is passed as
1427 option 12 to the DHCP server.
1429 CONFIG_BOOTP_DHCP_REQUEST_DELAY
1431 A 32bit value in microseconds for a delay between
1432 receiving a "DHCP Offer" and sending the "DHCP Request".
1433 This fixes a problem with certain DHCP servers that don't
1434 respond 100% of the time to a "DHCP request". E.g. On an
1435 AT91RM9200 processor running at 180MHz, this delay needed
1436 to be *at least* 15,000 usec before a Windows Server 2003
1437 DHCP server would reply 100% of the time. I recommend at
1438 least 50,000 usec to be safe. The alternative is to hope
1439 that one of the retries will be successful but note that
1440 the DHCP timeout and retry process takes a longer than
1441 this delay.
1443 - Link-local IP address negotiation:
1444 Negotiate with other link-local clients on the local network
1445 for an address that doesn't require explicit configuration.
1446 This is especially useful if a DHCP server cannot be guaranteed
1447 to exist in all environments that the device must operate.
1449 See doc/README.link-local for more information.
1451 - MAC address from environment variables
1453 FDT_SEQ_MACADDR_FROM_ENV
1455 Fix-up device tree with MAC addresses fetched sequentially from
1456 environment variables. This config work on assumption that
1457 non-usable ethernet node of device-tree are either not present
1458 or their status has been marked as "disabled".
1460 - CDP Options:
1461 CONFIG_CDP_DEVICE_ID
1463 The device id used in CDP trigger frames.
1465 CONFIG_CDP_DEVICE_ID_PREFIX
1467 A two character string which is prefixed to the MAC address
1468 of the device.
1470 CONFIG_CDP_PORT_ID
1472 A printf format string which contains the ascii name of
1473 the port. Normally is set to "eth%d" which sets
1474 eth0 for the first Ethernet, eth1 for the second etc.
1476 CONFIG_CDP_CAPABILITIES
1478 A 32bit integer which indicates the device capabilities;
1479 0x00000010 for a normal host which does not forwards.
1481 CONFIG_CDP_VERSION
1483 An ascii string containing the version of the software.
1485 CONFIG_CDP_PLATFORM
1487 An ascii string containing the name of the platform.
1489 CONFIG_CDP_TRIGGER
1491 A 32bit integer sent on the trigger.
1493 CONFIG_CDP_POWER_CONSUMPTION
1495 A 16bit integer containing the power consumption of the
1496 device in .1 of milliwatts.
1498 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1500 A byte containing the id of the VLAN.
1502 - Status LED: CONFIG_LED_STATUS
1504 Several configurations allow to display the current
1505 status using a LED. For instance, the LED will blink
1506 fast while running U-Boot code, stop blinking as
1507 soon as a reply to a BOOTP request was received, and
1508 start blinking slow once the Linux kernel is running
1509 (supported by a status LED driver in the Linux
1510 kernel). Defining CONFIG_LED_STATUS enables this
1511 feature in U-Boot.
1513 Additional options:
1515 CONFIG_LED_STATUS_GPIO
1516 The status LED can be connected to a GPIO pin.
1517 In such cases, the gpio_led driver can be used as a
1518 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1519 to include the gpio_led driver in the U-Boot binary.
1521 CONFIG_GPIO_LED_INVERTED_TABLE
1522 Some GPIO connected LEDs may have inverted polarity in which
1523 case the GPIO high value corresponds to LED off state and
1524 GPIO low value corresponds to LED on state.
1525 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1526 with a list of GPIO LEDs that have inverted polarity.
1528 - I2C Support: CONFIG_SYS_I2C
1530 This enable the NEW i2c subsystem, and will allow you to use
1531 i2c commands at the u-boot command line (as long as you set
1532 CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
1533 for defining speed and slave address
1534 - activate second bus with I2C_SOFT_DECLARATIONS2 define
1535 CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
1536 for defining speed and slave address
1537 - activate third bus with I2C_SOFT_DECLARATIONS3 define
1538 CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
1539 for defining speed and slave address
1540 - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
1541 CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
1542 for defining speed and slave address
1544 - drivers/i2c/fsl_i2c.c:
1545 - activate i2c driver with CONFIG_SYS_I2C_FSL
1546 define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
1547 offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
1548 CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
1549 bus.
1550 - If your board supports a second fsl i2c bus, define
1551 CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
1552 CONFIG_SYS_FSL_I2C2_SPEED for the speed and
1553 CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
1554 second bus.
1556 - drivers/i2c/tegra_i2c.c:
1557 - activate this driver with CONFIG_SYS_I2C_TEGRA
1558 - This driver adds 4 i2c buses with a fix speed from
1559 100000 and the slave addr 0!
1561 - drivers/i2c/ppc4xx_i2c.c
1562 - activate this driver with CONFIG_SYS_I2C_PPC4XX
1563 - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
1564 - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
1566 - drivers/i2c/i2c_mxc.c
1567 - activate this driver with CONFIG_SYS_I2C_MXC
1568 - enable bus 1 with CONFIG_SYS_I2C_MXC_I2C1
1569 - enable bus 2 with CONFIG_SYS_I2C_MXC_I2C2
1570 - enable bus 3 with CONFIG_SYS_I2C_MXC_I2C3
1571 - enable bus 4 with CONFIG_SYS_I2C_MXC_I2C4
1572 - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
1573 - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
1574 - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
1575 - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
1576 - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
1577 - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
1578 - define speed for bus 4 with CONFIG_SYS_MXC_I2C4_SPEED
1579 - define slave for bus 4 with CONFIG_SYS_MXC_I2C4_SLAVE
1580 If those defines are not set, default value is 100000
1581 for speed, and 0 for slave.
1583 - drivers/i2c/rcar_i2c.c:
1584 - activate this driver with CONFIG_SYS_I2C_RCAR
1585 - This driver adds 4 i2c buses
1587 - drivers/i2c/sh_i2c.c:
1588 - activate this driver with CONFIG_SYS_I2C_SH
1589 - This driver adds from 2 to 5 i2c buses
1591 - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
1592 - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
1593 - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
1594 - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
1595 - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
1596 - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
1597 - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
1598 - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
1599 - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
1600 - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
1601 - CONFIG_SYS_I2C_SH_NUM_CONTROLLERS for number of i2c buses
1603 - drivers/i2c/omap24xx_i2c.c
1604 - activate this driver with CONFIG_SYS_I2C_OMAP24XX
1605 - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
1606 - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
1607 - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
1608 - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
1609 - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
1610 - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
1611 - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
1612 - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
1613 - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
1614 - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
1616 - drivers/i2c/s3c24x0_i2c.c:
1617 - activate this driver with CONFIG_SYS_I2C_S3C24X0
1618 - This driver adds i2c buses (11 for Exynos5250, Exynos5420
1619 9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
1620 with a fix speed from 100000 and the slave addr 0!
1622 - drivers/i2c/ihs_i2c.c
1623 - activate this driver with CONFIG_SYS_I2C_IHS
1624 - CONFIG_SYS_I2C_IHS_CH0 activate hardware channel 0
1625 - CONFIG_SYS_I2C_IHS_SPEED_0 speed channel 0
1626 - CONFIG_SYS_I2C_IHS_SLAVE_0 slave addr channel 0
1627 - CONFIG_SYS_I2C_IHS_CH1 activate hardware channel 1
1628 - CONFIG_SYS_I2C_IHS_SPEED_1 speed channel 1
1629 - CONFIG_SYS_I2C_IHS_SLAVE_1 slave addr channel 1
1630 - CONFIG_SYS_I2C_IHS_CH2 activate hardware channel 2
1631 - CONFIG_SYS_I2C_IHS_SPEED_2 speed channel 2
1632 - CONFIG_SYS_I2C_IHS_SLAVE_2 slave addr channel 2
1633 - CONFIG_SYS_I2C_IHS_CH3 activate hardware channel 3
1634 - CONFIG_SYS_I2C_IHS_SPEED_3 speed channel 3
1635 - CONFIG_SYS_I2C_IHS_SLAVE_3 slave addr channel 3
1636 - activate dual channel with CONFIG_SYS_I2C_IHS_DUAL
1637 - CONFIG_SYS_I2C_IHS_SPEED_0_1 speed channel 0_1
1638 - CONFIG_SYS_I2C_IHS_SLAVE_0_1 slave addr channel 0_1
1639 - CONFIG_SYS_I2C_IHS_SPEED_1_1 speed channel 1_1
1640 - CONFIG_SYS_I2C_IHS_SLAVE_1_1 slave addr channel 1_1
1641 - CONFIG_SYS_I2C_IHS_SPEED_2_1 speed channel 2_1
1642 - CONFIG_SYS_I2C_IHS_SLAVE_2_1 slave addr channel 2_1
1643 - CONFIG_SYS_I2C_IHS_SPEED_3_1 speed channel 3_1
1644 - CONFIG_SYS_I2C_IHS_SLAVE_3_1 slave addr channel 3_1
1646 additional defines:
1648 CONFIG_SYS_NUM_I2C_BUSES
1649 Hold the number of i2c buses you want to use.
1651 CONFIG_SYS_I2C_DIRECT_BUS
1652 define this, if you don't use i2c muxes on your hardware.
1653 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1654 omit this define.
1656 CONFIG_SYS_I2C_MAX_HOPS
1657 define how many muxes are maximal consecutively connected
1658 on one i2c bus. If you not use i2c muxes, omit this
1659 define.
1661 CONFIG_SYS_I2C_BUSES
1662 hold a list of buses you want to use, only used if
1663 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1664 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1665 CONFIG_SYS_NUM_I2C_BUSES = 9:
1667 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1668 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1669 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1670 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1671 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1672 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1673 {1, {I2C_NULL_HOP}}, \
1674 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1675 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1676 }
1678 which defines
1679 bus 0 on adapter 0 without a mux
1680 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1681 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1682 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1683 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1684 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1685 bus 6 on adapter 1 without a mux
1686 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1687 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1689 If you do not have i2c muxes on your board, omit this define.
1691 - Legacy I2C Support:
1692 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1693 then the following macros need to be defined (examples are
1694 from include/configs/lwmon.h):
1696 I2C_INIT
1698 (Optional). Any commands necessary to enable the I2C
1699 controller or configure ports.
1701 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1703 I2C_ACTIVE
1705 The code necessary to make the I2C data line active
1706 (driven). If the data line is open collector, this
1707 define can be null.
1709 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1711 I2C_TRISTATE
1713 The code necessary to make the I2C data line tri-stated
1714 (inactive). If the data line is open collector, this
1715 define can be null.
1717 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1719 I2C_READ
1721 Code that returns true if the I2C data line is high,
1722 false if it is low.
1724 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1726 I2C_SDA(bit)
1728 If <bit> is true, sets the I2C data line high. If it
1729 is false, it clears it (low).
1731 eg: #define I2C_SDA(bit) \
1732 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1733 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1735 I2C_SCL(bit)
1737 If <bit> is true, sets the I2C clock line high. If it
1738 is false, it clears it (low).
1740 eg: #define I2C_SCL(bit) \
1741 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1742 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1744 I2C_DELAY
1746 This delay is invoked four times per clock cycle so this
1747 controls the rate of data transfer. The data rate thus
1748 is 1 / (I2C_DELAY * 4). Often defined to be something
1749 like:
1751 #define I2C_DELAY udelay(2)
1753 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1755 If your arch supports the generic GPIO framework (asm/gpio.h),
1756 then you may alternatively define the two GPIOs that are to be
1757 used as SCL / SDA. Any of the previous I2C_xxx macros will
1758 have GPIO-based defaults assigned to them as appropriate.
1760 You should define these to the GPIO value as given directly to
1761 the generic GPIO functions.
1763 CONFIG_SYS_I2C_INIT_BOARD
1765 When a board is reset during an i2c bus transfer
1766 chips might think that the current transfer is still
1767 in progress. On some boards it is possible to access
1768 the i2c SCLK line directly, either by using the
1769 processor pin as a GPIO or by having a second pin
1770 connected to the bus. If this option is defined a
1771 custom i2c_init_board() routine in boards/xxx/board.c
1772 is run early in the boot sequence.
1774 CONFIG_I2C_MULTI_BUS
1776 This option allows the use of multiple I2C buses, each of which
1777 must have a controller. At any point in time, only one bus is
1778 active. To switch to a different bus, use the 'i2c dev' command.
1779 Note that bus numbering is zero-based.
1781 CONFIG_SYS_I2C_NOPROBES
1783 This option specifies a list of I2C devices that will be skipped
1784 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1785 is set, specify a list of bus-device pairs. Otherwise, specify
1786 a 1D array of device addresses
1788 e.g.
1789 #undef CONFIG_I2C_MULTI_BUS
1790 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1792 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1794 #define CONFIG_I2C_MULTI_BUS
1795 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1797 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1799 CONFIG_SYS_SPD_BUS_NUM
1801 If defined, then this indicates the I2C bus number for DDR SPD.
1802 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1804 CONFIG_SYS_RTC_BUS_NUM
1806 If defined, then this indicates the I2C bus number for the RTC.
1807 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1809 CONFIG_SOFT_I2C_READ_REPEATED_START
1811 defining this will force the i2c_read() function in
1812 the soft_i2c driver to perform an I2C repeated start
1813 between writing the address pointer and reading the
1814 data. If this define is omitted the default behaviour
1815 of doing a stop-start sequence will be used. Most I2C
1816 devices can use either method, but some require one or
1817 the other.
1819 - SPI Support: CONFIG_SPI
1821 Enables SPI driver (so far only tested with
1822 SPI EEPROM, also an instance works with Crystal A/D and
1823 D/As on the SACSng board)
1825 CONFIG_SOFT_SPI
1827 Enables a software (bit-bang) SPI driver rather than
1828 using hardware support. This is a general purpose
1829 driver that only requires three general I/O port pins
1830 (two outputs, one input) to function. If this is
1831 defined, the board configuration must define several
1832 SPI configuration items (port pins to use, etc). For
1833 an example, see include/configs/sacsng.h.
1835 CONFIG_SYS_SPI_MXC_WAIT
1836 Timeout for waiting until spi transfer completed.
1837 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1839 - FPGA Support: CONFIG_FPGA
1841 Enables FPGA subsystem.
1843 CONFIG_FPGA_<vendor>
1845 Enables support for specific chip vendors.
1846 (ALTERA, XILINX)
1848 CONFIG_FPGA_<family>
1850 Enables support for FPGA family.
1851 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1853 CONFIG_FPGA_COUNT
1855 Specify the number of FPGA devices to support.
1857 CONFIG_SYS_FPGA_PROG_FEEDBACK
1859 Enable printing of hash marks during FPGA configuration.
1861 CONFIG_SYS_FPGA_CHECK_BUSY
1863 Enable checks on FPGA configuration interface busy
1864 status by the configuration function. This option
1865 will require a board or device specific function to
1866 be written.
1868 CONFIG_FPGA_DELAY
1870 If defined, a function that provides delays in the FPGA
1871 configuration driver.
1873 CONFIG_SYS_FPGA_CHECK_CTRLC
1874 Allow Control-C to interrupt FPGA configuration
1876 CONFIG_SYS_FPGA_CHECK_ERROR
1878 Check for configuration errors during FPGA bitfile
1879 loading. For example, abort during Virtex II
1880 configuration if the INIT_B line goes low (which
1881 indicated a CRC error).
1883 CONFIG_SYS_FPGA_WAIT_INIT
1885 Maximum time to wait for the INIT_B line to de-assert
1886 after PROB_B has been de-asserted during a Virtex II
1887 FPGA configuration sequence. The default time is 500
1888 ms.
1890 CONFIG_SYS_FPGA_WAIT_BUSY
1892 Maximum time to wait for BUSY to de-assert during
1893 Virtex II FPGA configuration. The default is 5 ms.
1895 CONFIG_SYS_FPGA_WAIT_CONFIG
1897 Time to wait after FPGA configuration. The default is
1898 200 ms.
1900 - Configuration Management:
1902 CONFIG_IDENT_STRING
1904 If defined, this string will be added to the U-Boot
1905 version information (U_BOOT_VERSION)
1907 - Vendor Parameter Protection:
1909 U-Boot considers the values of the environment
1910 variables "serial#" (Board Serial Number) and
1911 "ethaddr" (Ethernet Address) to be parameters that
1912 are set once by the board vendor / manufacturer, and
1913 protects these variables from casual modification by
1914 the user. Once set, these variables are read-only,
1915 and write or delete attempts are rejected. You can
1916 change this behaviour:
1918 If CONFIG_ENV_OVERWRITE is #defined in your config
1919 file, the write protection for vendor parameters is
1920 completely disabled. Anybody can change or delete
1921 these parameters.
1923 Alternatively, if you define _both_ an ethaddr in the
1924 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1925 Ethernet address is installed in the environment,
1926 which can be changed exactly ONCE by the user. [The
1927 serial# is unaffected by this, i. e. it remains
1928 read-only.]
1930 The same can be accomplished in a more flexible way
1931 for any variable by configuring the type of access
1932 to allow for those variables in the ".flags" variable
1933 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1935 - Protected RAM:
1936 CONFIG_PRAM
1938 Define this variable to enable the reservation of
1939 "protected RAM", i. e. RAM which is not overwritten
1940 by U-Boot. Define CONFIG_PRAM to hold the number of
1941 kB you want to reserve for pRAM. You can overwrite
1942 this default value by defining an environment
1943 variable "pram" to the number of kB you want to
1944 reserve. Note that the board info structure will
1945 still show the full amount of RAM. If pRAM is
1946 reserved, a new environment variable "mem" will
1947 automatically be defined to hold the amount of
1948 remaining RAM in a form that can be passed as boot
1949 argument to Linux, for instance like that:
1951 setenv bootargs ... mem=\${mem}
1952 saveenv
1954 This way you can tell Linux not to use this memory,
1955 either, which results in a memory region that will
1956 not be affected by reboots.
1958 *WARNING* If your board configuration uses automatic
1959 detection of the RAM size, you must make sure that
1960 this memory test is non-destructive. So far, the
1961 following board configurations are known to be
1962 "pRAM-clean":
1964 IVMS8, IVML24, SPD8xx,
1965 HERMES, IP860, RPXlite, LWMON,
1966 FLAGADM
1968 - Access to physical memory region (> 4GB)
1969 Some basic support is provided for operations on memory not
1970 normally accessible to U-Boot - e.g. some architectures
1971 support access to more than 4GB of memory on 32-bit
1972 machines using physical address extension or similar.
1973 Define CONFIG_PHYSMEM to access this basic support, which
1974 currently only supports clearing the memory.
1976 - Error Recovery:
1977 CONFIG_NET_RETRY_COUNT
1979 This variable defines the number of retries for
1980 network operations like ARP, RARP, TFTP, or BOOTP
1981 before giving up the operation. If not defined, a
1982 default value of 5 is used.
1984 CONFIG_ARP_TIMEOUT
1986 Timeout waiting for an ARP reply in milliseconds.
1988 CONFIG_NFS_TIMEOUT
1990 Timeout in milliseconds used in NFS protocol.
1991 If you encounter "ERROR: Cannot umount" in nfs command,
1992 try longer timeout such as
1993 #define CONFIG_NFS_TIMEOUT 10000UL
1995 - Command Interpreter:
1996 CONFIG_SYS_PROMPT_HUSH_PS2
1998 This defines the secondary prompt string, which is
1999 printed when the command interpreter needs more input
2000 to complete a command. Usually "> ".
2002 Note:
2004 In the current implementation, the local variables
2005 space and global environment variables space are
2006 separated. Local variables are those you define by
2007 simply typing `name=value'. To access a local
2008 variable later on, you have write `$name' or
2009 `${name}'; to execute the contents of a variable
2010 directly type `$name' at the command prompt.
2012 Global environment variables are those you use
2013 setenv/printenv to work with. To run a command stored
2014 in such a variable, you need to use the run command,
2015 and you must not use the '$' sign to access them.
2017 To store commands and special characters in a
2018 variable, please use double quotation marks
2019 surrounding the whole text of the variable, instead
2020 of the backslashes before semicolons and special
2021 symbols.
2023 - Command Line Editing and History:
2024 CONFIG_CMDLINE_PS_SUPPORT
2026 Enable support for changing the command prompt string
2027 at run-time. Only static string is supported so far.
2028 The string is obtained from environment variables PS1
2029 and PS2.
2031 - Default Environment:
2032 CONFIG_EXTRA_ENV_SETTINGS
2034 Define this to contain any number of null terminated
2035 strings (variable = value pairs) that will be part of
2036 the default environment compiled into the boot image.
2038 For example, place something like this in your
2039 board's config file:
2041 #define CONFIG_EXTRA_ENV_SETTINGS \
2042 "myvar1=value1\0" \
2043 "myvar2=value2\0"
2045 Warning: This method is based on knowledge about the
2046 internal format how the environment is stored by the
2047 U-Boot code. This is NOT an official, exported
2048 interface! Although it is unlikely that this format
2049 will change soon, there is no guarantee either.
2050 You better know what you are doing here.
2052 Note: overly (ab)use of the default environment is
2053 discouraged. Make sure to check other ways to preset
2054 the environment like the "source" command or the
2055 boot command first.
2057 CONFIG_DELAY_ENVIRONMENT
2059 Normally the environment is loaded when the board is
2060 initialised so that it is available to U-Boot. This inhibits
2061 that so that the environment is not available until
2062 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2063 this is instead controlled by the value of
2064 /config/load-environment.
2066 - TFTP Fixed UDP Port:
2067 CONFIG_TFTP_PORT
2069 If this is defined, the environment variable tftpsrcp
2070 is used to supply the TFTP UDP source port value.
2071 If tftpsrcp isn't defined, the normal pseudo-random port
2072 number generator is used.
2074 Also, the environment variable tftpdstp is used to supply
2075 the TFTP UDP destination port value. If tftpdstp isn't
2076 defined, the normal port 69 is used.
2078 The purpose for tftpsrcp is to allow a TFTP server to
2079 blindly start the TFTP transfer using the pre-configured
2080 target IP address and UDP port. This has the effect of
2081 "punching through" the (Windows XP) firewall, allowing
2082 the remainder of the TFTP transfer to proceed normally.
2083 A better solution is to properly configure the firewall,
2084 but sometimes that is not allowed.
2086 CONFIG_STANDALONE_LOAD_ADDR
2088 This option defines a board specific value for the
2089 address where standalone program gets loaded, thus
2090 overwriting the architecture dependent default
2091 settings.
2093 - Frame Buffer Address:
2094 CONFIG_FB_ADDR
2096 Define CONFIG_FB_ADDR if you want to use specific
2097 address for frame buffer. This is typically the case
2098 when using a graphics controller has separate video
2099 memory. U-Boot will then place the frame buffer at
2100 the given address instead of dynamically reserving it
2101 in system RAM by calling lcd_setmem(), which grabs
2102 the memory for the frame buffer depending on the
2103 configured panel size.
2105 Please see board_init_f function.
2107 - Automatic software updates via TFTP server
2108 CONFIG_UPDATE_TFTP
2109 CONFIG_UPDATE_TFTP_CNT_MAX
2110 CONFIG_UPDATE_TFTP_MSEC_MAX
2112 These options enable and control the auto-update feature;
2113 for a more detailed description refer to doc/README.update.
2115 - MTD Support (mtdparts command, UBI support)
2116 CONFIG_MTD_UBI_WL_THRESHOLD
2117 This parameter defines the maximum difference between the highest
2118 erase counter value and the lowest erase counter value of eraseblocks
2119 of UBI devices. When this threshold is exceeded, UBI starts performing
2120 wear leveling by means of moving data from eraseblock with low erase
2121 counter to eraseblocks with high erase counter.
2123 The default value should be OK for SLC NAND flashes, NOR flashes and
2124 other flashes which have eraseblock life-cycle 100000 or more.
2125 However, in case of MLC NAND flashes which typically have eraseblock
2126 life-cycle less than 10000, the threshold should be lessened (e.g.,
2127 to 128 or 256, although it does not have to be power of 2).
2129 default: 4096
2131 CONFIG_MTD_UBI_BEB_LIMIT
2132 This option specifies the maximum bad physical eraseblocks UBI
2133 expects on the MTD device (per 1024 eraseblocks). If the
2134 underlying flash does not admit of bad eraseblocks (e.g. NOR
2135 flash), this value is ignored.
2137 NAND datasheets often specify the minimum and maximum NVM
2138 (Number of Valid Blocks) for the flashes' endurance lifetime.
2139 The maximum expected bad eraseblocks per 1024 eraseblocks
2140 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
2141 which gives 20 for most NANDs (MaxNVB is basically the total
2142 count of eraseblocks on the chip).
2144 To put it differently, if this value is 20, UBI will try to
2145 reserve about 1.9% of physical eraseblocks for bad blocks
2146 handling. And that will be 1.9% of eraseblocks on the entire
2147 NAND chip, not just the MTD partition UBI attaches. This means
2148 that if you have, say, a NAND flash chip admits maximum 40 bad
2149 eraseblocks, and it is split on two MTD partitions of the same
2150 size, UBI will reserve 40 eraseblocks when attaching a
2151 partition.
2153 default: 20
2155 CONFIG_MTD_UBI_FASTMAP
2156 Fastmap is a mechanism which allows attaching an UBI device
2157 in nearly constant time. Instead of scanning the whole MTD device it
2158 only has to locate a checkpoint (called fastmap) on the device.
2159 The on-flash fastmap contains all information needed to attach
2160 the device. Using fastmap makes only sense on large devices where
2161 attaching by scanning takes long. UBI will not automatically install
2162 a fastmap on old images, but you can set the UBI parameter
2163 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
2164 that fastmap-enabled images are still usable with UBI implementations
2165 without fastmap support. On typical flash devices the whole fastmap
2166 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
2168 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
2169 Set this parameter to enable fastmap automatically on images
2170 without a fastmap.
2171 default: 0
2173 CONFIG_MTD_UBI_FM_DEBUG
2174 Enable UBI fastmap debug
2175 default: 0
2177 - SPL framework
2178 CONFIG_SPL
2179 Enable building of SPL globally.
2181 CONFIG_SPL_LDSCRIPT
2182 LDSCRIPT for linking the SPL binary.
2184 CONFIG_SPL_MAX_FOOTPRINT
2185 Maximum size in memory allocated to the SPL, BSS included.
2186 When defined, the linker checks that the actual memory
2187 used by SPL from _start to __bss_end does not exceed it.
2188 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
2189 must not be both defined at the same time.
2191 CONFIG_SPL_MAX_SIZE
2192 Maximum size of the SPL image (text, data, rodata, and
2193 linker lists sections), BSS excluded.
2194 When defined, the linker checks that the actual size does
2195 not exceed it.
2197 CONFIG_SPL_RELOC_TEXT_BASE
2198 Address to relocate to. If unspecified, this is equal to
2199 CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
2201 CONFIG_SPL_BSS_START_ADDR
2202 Link address for the BSS within the SPL binary.
2204 CONFIG_SPL_BSS_MAX_SIZE
2205 Maximum size in memory allocated to the SPL BSS.
2206 When defined, the linker checks that the actual memory used
2207 by SPL from __bss_start to __bss_end does not exceed it.
2208 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
2209 must not be both defined at the same time.
2211 CONFIG_SPL_STACK
2212 Adress of the start of the stack SPL will use
2214 CONFIG_SPL_PANIC_ON_RAW_IMAGE
2215 When defined, SPL will panic() if the image it has
2216 loaded does not have a signature.
2217 Defining this is useful when code which loads images
2218 in SPL cannot guarantee that absolutely all read errors
2219 will be caught.
2220 An example is the LPC32XX MLC NAND driver, which will
2221 consider that a completely unreadable NAND block is bad,
2222 and thus should be skipped silently.
2224 CONFIG_SPL_RELOC_STACK
2225 Adress of the start of the stack SPL will use after
2226 relocation. If unspecified, this is equal to
2227 CONFIG_SPL_STACK.
2229 CONFIG_SYS_SPL_MALLOC_START
2230 Starting address of the malloc pool used in SPL.
2231 When this option is set the full malloc is used in SPL and
2232 it is set up by spl_init() and before that, the simple malloc()
2233 can be used if CONFIG_SYS_MALLOC_F is defined.
2235 CONFIG_SYS_SPL_MALLOC_SIZE
2236 The size of the malloc pool used in SPL.
2238 CONFIG_SPL_OS_BOOT
2239 Enable booting directly to an OS from SPL.
2240 See also: doc/README.falcon
2242 CONFIG_SPL_DISPLAY_PRINT
2243 For ARM, enable an optional function to print more information
2244 about the running system.
2246 CONFIG_SPL_INIT_MINIMAL
2247 Arch init code should be built for a very small image
2249 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
2250 Partition on the MMC to load U-Boot from when the MMC is being
2251 used in raw mode
2253 CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
2254 Sector to load kernel uImage from when MMC is being
2255 used in raw mode (for Falcon mode)
2257 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
2258 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
2259 Sector and number of sectors to load kernel argument
2260 parameters from when MMC is being used in raw mode
2261 (for falcon mode)
2263 CONFIG_SYS_MMCSD_FS_BOOT_PARTITION
2264 Partition on the MMC to load U-Boot from when the MMC is being
2265 used in fs mode
2267 CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
2268 Filename to read to load U-Boot when reading from filesystem
2270 CONFIG_SPL_FS_LOAD_KERNEL_NAME
2271 Filename to read to load kernel uImage when reading
2272 from filesystem (for Falcon mode)
2274 CONFIG_SPL_FS_LOAD_ARGS_NAME
2275 Filename to read to load kernel argument parameters
2276 when reading from filesystem (for Falcon mode)
2278 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
2279 Set this for NAND SPL on PPC mpc83xx targets, so that
2280 start.S waits for the rest of the SPL to load before
2281 continuing (the hardware starts execution after just
2282 loading the first page rather than the full 4K).
2284 CONFIG_SPL_SKIP_RELOCATE
2285 Avoid SPL relocation
2287 CONFIG_SPL_NAND_BASE
2288 Include nand_base.c in the SPL. Requires
2289 CONFIG_SPL_NAND_DRIVERS.
2291 CONFIG_SPL_NAND_DRIVERS
2292 SPL uses normal NAND drivers, not minimal drivers.
2294 CONFIG_SPL_NAND_IDENT
2295 SPL uses the chip ID list to identify the NAND flash.
2296 Requires CONFIG_SPL_NAND_BASE.
2298 CONFIG_SPL_NAND_ECC
2299 Include standard software ECC in the SPL
2301 CONFIG_SPL_NAND_SIMPLE
2302 Support for NAND boot using simple NAND drivers that
2303 expose the cmd_ctrl() interface.
2305 CONFIG_SPL_UBI
2306 Support for a lightweight UBI (fastmap) scanner and
2307 loader
2309 CONFIG_SPL_NAND_RAW_ONLY
2310 Support to boot only raw u-boot.bin images. Use this only
2311 if you need to save space.
2313 CONFIG_SPL_COMMON_INIT_DDR
2314 Set for common ddr init with serial presence detect in
2315 SPL binary.
2317 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
2318 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
2319 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
2320 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
2321 CONFIG_SYS_NAND_ECCBYTES
2322 Defines the size and behavior of the NAND that SPL uses
2323 to read U-Boot
2325 CONFIG_SYS_NAND_U_BOOT_OFFS
2326 Location in NAND to read U-Boot from
2328 CONFIG_SYS_NAND_U_BOOT_DST
2329 Location in memory to load U-Boot to
2331 CONFIG_SYS_NAND_U_BOOT_SIZE
2332 Size of image to load
2334 CONFIG_SYS_NAND_U_BOOT_START
2335 Entry point in loaded image to jump to
2337 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
2338 Define this if you need to first read the OOB and then the
2339 data. This is used, for example, on davinci platforms.
2341 CONFIG_SPL_RAM_DEVICE
2342 Support for running image already present in ram, in SPL binary
2344 CONFIG_SPL_PAD_TO
2345 Image offset to which the SPL should be padded before appending
2346 the SPL payload. By default, this is defined as
2347 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2348 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2349 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2351 CONFIG_SPL_TARGET
2352 Final target image containing SPL and payload. Some SPLs
2353 use an arch-specific makefile fragment instead, for
2354 example if more than one image needs to be produced.
2356 CONFIG_SPL_FIT_PRINT
2357 Printing information about a FIT image adds quite a bit of
2358 code to SPL. So this is normally disabled in SPL. Use this
2359 option to re-enable it. This will affect the output of the
2360 bootm command when booting a FIT image.
2362 - TPL framework
2363 CONFIG_TPL
2364 Enable building of TPL globally.
2366 CONFIG_TPL_PAD_TO
2367 Image offset to which the TPL should be padded before appending
2368 the TPL payload. By default, this is defined as
2369 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2370 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2371 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2373 - Interrupt support (PPC):
2375 There are common interrupt_init() and timer_interrupt()
2376 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
2377 for CPU specific initialization. interrupt_init_cpu()
2378 should set decrementer_count to appropriate value. If
2379 CPU resets decrementer automatically after interrupt
2380 (ppc4xx) it should set decrementer_count to zero.
2381 timer_interrupt() calls timer_interrupt_cpu() for CPU
2382 specific handling. If board has watchdog / status_led
2383 / other_activity_monitor it works automatically from
2384 general timer_interrupt().
2387 Board initialization settings:
2388 ------------------------------
2390 During Initialization u-boot calls a number of board specific functions
2391 to allow the preparation of board specific prerequisites, e.g. pin setup
2392 before drivers are initialized. To enable these callbacks the
2393 following configuration macros have to be defined. Currently this is
2394 architecture specific, so please check arch/your_architecture/lib/board.c
2395 typically in board_init_f() and board_init_r().
2397 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
2398 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
2399 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
2400 - CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
2402 Configuration Settings:
2403 -----------------------
2405 - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
2406 Optionally it can be defined to support 64-bit memory commands.
2408 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2409 undefine this when you're short of memory.
2411 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
2412 width of the commands listed in the 'help' command output.
2414 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
2415 prompt for user input.
2417 - CONFIG_SYS_CBSIZE: Buffer size for input from the Console
2419 - CONFIG_SYS_PBSIZE: Buffer size for Console output
2421 - CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands
2423 - CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2424 the application (usually a Linux kernel) when it is
2425 booted
2427 - CONFIG_SYS_BAUDRATE_TABLE:
2428 List of legal baudrate settings for this board.
2430 - CONFIG_SYS_MEM_RESERVE_SECURE
2431 Only implemented for ARMv8 for now.
2432 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
2433 is substracted from total RAM and won't be reported to OS.
2434 This memory can be used as secure memory. A variable
2435 gd->arch.secure_ram is used to track the location. In systems
2436 the RAM base is not zero, or RAM is divided into banks,
2437 this variable needs to be recalcuated to get the address.
2439 - CONFIG_SYS_MEM_TOP_HIDE:
2440 If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2441 this specified memory area will get subtracted from the top
2442 (end) of RAM and won't get "touched" at all by U-Boot. By
2443 fixing up gd->ram_size the Linux kernel should gets passed
2444 the now "corrected" memory size and won't touch it either.
2445 This should work for arch/ppc and arch/powerpc. Only Linux
2446 board ports in arch/powerpc with bootwrapper support that
2447 recalculate the memory size from the SDRAM controller setup
2448 will have to get fixed in Linux additionally.
2450 This option can be used as a workaround for the 440EPx/GRx
2451 CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2452 be touched.
2454 WARNING: Please make sure that this value is a multiple of
2455 the Linux page size (normally 4k). If this is not the case,
2456 then the end address of the Linux memory will be located at a
2457 non page size aligned address and this could cause major
2458 problems.
2460 - CONFIG_SYS_LOADS_BAUD_CHANGE:
2461 Enable temporary baudrate change while serial download
2463 - CONFIG_SYS_SDRAM_BASE:
2464 Physical start address of SDRAM. _Must_ be 0 here.
2466 - CONFIG_SYS_FLASH_BASE:
2467 Physical start address of Flash memory.
2469 - CONFIG_SYS_MONITOR_BASE:
2470 Physical start address of boot monitor code (set by
2471 make config files to be same as the text base address
2472 (CONFIG_SYS_TEXT_BASE) used when linking) - same as
2473 CONFIG_SYS_FLASH_BASE when booting from flash.
2475 - CONFIG_SYS_MONITOR_LEN:
2476 Size of memory reserved for monitor code, used to
2477 determine _at_compile_time_ (!) if the environment is
2478 embedded within the U-Boot image, or in a separate
2479 flash sector.
2481 - CONFIG_SYS_MALLOC_LEN:
2482 Size of DRAM reserved for malloc() use.
2484 - CONFIG_SYS_MALLOC_F_LEN
2485 Size of the malloc() pool for use before relocation. If
2486 this is defined, then a very simple malloc() implementation
2487 will become available before relocation. The address is just
2488 below the global data, and the stack is moved down to make
2489 space.
2491 This feature allocates regions with increasing addresses
2492 within the region. calloc() is supported, but realloc()
2493 is not available. free() is supported but does nothing.
2494 The memory will be freed (or in fact just forgotten) when
2495 U-Boot relocates itself.
2497 - CONFIG_SYS_MALLOC_SIMPLE
2498 Provides a simple and small malloc() and calloc() for those
2499 boards which do not use the full malloc in SPL (which is
2500 enabled with CONFIG_SYS_SPL_MALLOC_START).
2502 - CONFIG_SYS_NONCACHED_MEMORY:
2503 Size of non-cached memory area. This area of memory will be
2504 typically located right below the malloc() area and mapped
2505 uncached in the MMU. This is useful for drivers that would
2506 otherwise require a lot of explicit cache maintenance. For
2507 some drivers it's also impossible to properly maintain the
2508 cache. For example if the regions that need to be flushed
2509 are not a multiple of the cache-line size, *and* padding
2510 cannot be allocated between the regions to align them (i.e.
2511 if the HW requires a contiguous array of regions, and the
2512 size of each region is not cache-aligned), then a flush of
2513 one region may result in overwriting data that hardware has
2514 written to another region in the same cache-line. This can
2515 happen for example in network drivers where descriptors for
2516 buffers are typically smaller than the CPU cache-line (e.g.
2517 16 bytes vs. 32 or 64 bytes).
2519 Non-cached memory is only supported on 32-bit ARM at present.
2521 - CONFIG_SYS_BOOTM_LEN:
2522 Normally compressed uImages are limited to an
2523 uncompressed size of 8 MBytes. If this is not enough,
2524 you can define CONFIG_SYS_BOOTM_LEN in your board config file
2525 to adjust this setting to your needs.
2527 - CONFIG_SYS_BOOTMAPSZ:
2528 Maximum size of memory mapped by the startup code of
2529 the Linux kernel; all data that must be processed by
2530 the Linux kernel (bd_info, boot arguments, FDT blob if
2531 used) must be put below this limit, unless "bootm_low"
2532 environment variable is defined and non-zero. In such case
2533 all data for the Linux kernel must be between "bootm_low"
2534 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
2535 variable "bootm_mapsize" will override the value of
2536 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
2537 then the value in "bootm_size" will be used instead.
2539 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
2540 Enable initrd_high functionality. If defined then the
2541 initrd_high feature is enabled and the bootm ramdisk subcommand
2542 is enabled.
2544 - CONFIG_SYS_BOOT_GET_CMDLINE:
2545 Enables allocating and saving kernel cmdline in space between
2546 "bootm_low" and "bootm_low" + BOOTMAPSZ.
2548 - CONFIG_SYS_BOOT_GET_KBD:
2549 Enables allocating and saving a kernel copy of the bd_info in
2550 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2552 - CONFIG_SYS_MAX_FLASH_BANKS:
2553 Max number of Flash memory banks
2555 - CONFIG_SYS_MAX_FLASH_SECT:
2556 Max number of sectors on a Flash chip
2558 - CONFIG_SYS_FLASH_ERASE_TOUT:
2559 Timeout for Flash erase operations (in ms)
2561 - CONFIG_SYS_FLASH_WRITE_TOUT:
2562 Timeout for Flash write operations (in ms)
2564 - CONFIG_SYS_FLASH_LOCK_TOUT
2565 Timeout for Flash set sector lock bit operation (in ms)
2567 - CONFIG_SYS_FLASH_UNLOCK_TOUT
2568 Timeout for Flash clear lock bits operation (in ms)
2570 - CONFIG_SYS_FLASH_PROTECTION
2571 If defined, hardware flash sectors protection is used
2572 instead of U-Boot software protection.
2574 - CONFIG_SYS_DIRECT_FLASH_TFTP:
2576 Enable TFTP transfers directly to flash memory;
2577 without this option such a download has to be
2578 performed in two steps: (1) download to RAM, and (2)
2579 copy from RAM to flash.
2581 The two-step approach is usually more reliable, since
2582 you can check if the download worked before you erase
2583 the flash, but in some situations (when system RAM is
2584 too limited to allow for a temporary copy of the
2585 downloaded image) this option may be very useful.
2587 - CONFIG_SYS_FLASH_CFI:
2588 Define if the flash driver uses extra elements in the
2589 common flash structure for storing flash geometry.
2591 - CONFIG_FLASH_CFI_DRIVER
2592 This option also enables the building of the cfi_flash driver
2593 in the drivers directory
2595 - CONFIG_FLASH_CFI_MTD
2596 This option enables the building of the cfi_mtd driver
2597 in the drivers directory. The driver exports CFI flash
2598 to the MTD layer.
2600 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2601 Use buffered writes to flash.
2603 - CONFIG_FLASH_SPANSION_S29WS_N
2604 s29ws-n MirrorBit flash has non-standard addresses for buffered
2605 write commands.
2607 - CONFIG_SYS_FLASH_QUIET_TEST
2608 If this option is defined, the common CFI flash doesn't
2609 print it's warning upon not recognized FLASH banks. This
2610 is useful, if some of the configured banks are only
2611 optionally available.
2613 - CONFIG_FLASH_SHOW_PROGRESS
2614 If defined (must be an integer), print out countdown
2615 digits and dots. Recommended value: 45 (9..1) for 80
2616 column displays, 15 (3..1) for 40 column displays.
2618 - CONFIG_FLASH_VERIFY
2619 If defined, the content of the flash (destination) is compared
2620 against the source after the write operation. An error message
2621 will be printed when the contents are not identical.
2622 Please note that this option is useless in nearly all cases,
2623 since such flash programming errors usually are detected earlier
2624 while unprotecting/erasing/programming. Please only enable
2625 this option if you really know what you are doing.
2627 - CONFIG_SYS_RX_ETH_BUFFER:
2628 Defines the number of Ethernet receive buffers. On some
2629 Ethernet controllers it is recommended to set this value
2630 to 8 or even higher (EEPRO100 or 405 EMAC), since all
2631 buffers can be full shortly after enabling the interface
2632 on high Ethernet traffic.
2633 Defaults to 4 if not defined.
2635 - CONFIG_ENV_MAX_ENTRIES
2637 Maximum number of entries in the hash table that is used
2638 internally to store the environment settings. The default
2639 setting is supposed to be generous and should work in most
2640 cases. This setting can be used to tune behaviour; see
2641 lib/hashtable.c for details.
2643 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2644 - CONFIG_ENV_FLAGS_LIST_STATIC
2645 Enable validation of the values given to environment variables when
2646 calling env set. Variables can be restricted to only decimal,
2647 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
2648 the variables can also be restricted to IP address or MAC address.
2650 The format of the list is:
2651 type_attribute = [s|d|x|b|i|m]
2652 access_attribute = [a|r|o|c]
2653 attributes = type_attribute[access_attribute]
2654 entry = variable_name[:attributes]
2655 list = entry[,list]
2657 The type attributes are:
2658 s - String (default)
2659 d - Decimal
2660 x - Hexadecimal
2661 b - Boolean ([1yYtT|0nNfF])
2662 i - IP address
2663 m - MAC address
2665 The access attributes are:
2666 a - Any (default)
2667 r - Read-only
2668 o - Write-once
2669 c - Change-default
2671 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2672 Define this to a list (string) to define the ".flags"
2673 environment variable in the default or embedded environment.
2675 - CONFIG_ENV_FLAGS_LIST_STATIC
2676 Define this to a list (string) to define validation that
2677 should be done if an entry is not found in the ".flags"
2678 environment variable. To override a setting in the static
2679 list, simply add an entry for the same variable name to the
2680 ".flags" variable.
2682 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
2683 regular expression. This allows multiple variables to define the same
2684 flags without explicitly listing them for each variable.
2686 The following definitions that deal with the placement and management
2687 of environment data (variable area); in general, we support the
2688 following configurations:
2690 - CONFIG_BUILD_ENVCRC:
2692 Builds up envcrc with the target environment so that external utils
2693 may easily extract it and embed it in final U-Boot images.
2695 BE CAREFUL! The first access to the environment happens quite early
2696 in U-Boot initialization (when we try to get the setting of for the
2697 console baudrate). You *MUST* have mapped your NVRAM area then, or
2698 U-Boot will hang.
2700 Please note that even with NVRAM we still use a copy of the
2701 environment in RAM: we could work on NVRAM directly, but we want to
2702 keep settings there always unmodified except somebody uses "saveenv"
2703 to save the current settings.
2705 BE CAREFUL! For some special cases, the local device can not use
2706 "saveenv" command. For example, the local device will get the
2707 environment stored in a remote NOR flash by SRIO or PCIE link,
2708 but it can not erase, write this NOR flash by SRIO or PCIE interface.
2710 - CONFIG_NAND_ENV_DST
2712 Defines address in RAM to which the nand_spl code should copy the
2713 environment. If redundant environment is used, it will be copied to
2714 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
2716 Please note that the environment is read-only until the monitor
2717 has been relocated to RAM and a RAM copy of the environment has been
2718 created; also, when using EEPROM you will have to use env_get_f()
2719 until then to read environment variables.
2721 The environment is protected by a CRC32 checksum. Before the monitor
2722 is relocated into RAM, as a result of a bad CRC you will be working
2723 with the compiled-in default environment - *silently*!!! [This is
2724 necessary, because the first environment variable we need is the
2725 "baudrate" setting for the console - if we have a bad CRC, we don't
2726 have any device yet where we could complain.]
2728 Note: once the monitor has been relocated, then it will complain if
2729 the default environment is used; a new CRC is computed as soon as you
2730 use the "saveenv" command to store a valid environment.
2732 - CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
2733 Echo the inverted Ethernet link state to the fault LED.
2735 Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
2736 also needs to be defined.
2738 - CONFIG_SYS_FAULT_MII_ADDR:
2739 MII address of the PHY to check for the Ethernet link state.
2741 - CONFIG_NS16550_MIN_FUNCTIONS:
2742 Define this if you desire to only have use of the NS16550_init
2743 and NS16550_putc functions for the serial driver located at
2744 drivers/serial/ns16550.c. This option is useful for saving
2745 space for already greatly restricted images, including but not
2746 limited to NAND_SPL configurations.
2748 - CONFIG_DISPLAY_BOARDINFO
2749 Display information about the board that U-Boot is running on
2750 when U-Boot starts up. The board function checkboard() is called
2751 to do this.
2753 - CONFIG_DISPLAY_BOARDINFO_LATE
2754 Similar to the previous option, but display this information
2755 later, once stdio is running and output goes to the LCD, if
2756 present.
2758 - CONFIG_BOARD_SIZE_LIMIT:
2759 Maximum size of the U-Boot image. When defined, the
2760 build system checks that the actual size does not
2761 exceed it.
2763 Low Level (hardware related) configuration options:
2764 ---------------------------------------------------
2766 - CONFIG_SYS_CACHELINE_SIZE:
2767 Cache Line Size of the CPU.
2769 - CONFIG_SYS_CCSRBAR_DEFAULT:
2770 Default (power-on reset) physical address of CCSR on Freescale
2771 PowerPC SOCs.
2773 - CONFIG_SYS_CCSRBAR:
2774 Virtual address of CCSR. On a 32-bit build, this is typically
2775 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
2777 - CONFIG_SYS_CCSRBAR_PHYS:
2778 Physical address of CCSR. CCSR can be relocated to a new
2779 physical address, if desired. In this case, this macro should
2780 be set to that address. Otherwise, it should be set to the
2781 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
2782 is typically relocated on 36-bit builds. It is recommended
2783 that this macro be defined via the _HIGH and _LOW macros:
2785 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
2786 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
2788 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
2789 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
2790 either 0 (32-bit build) or 0xF (36-bit build). This macro is
2791 used in assembly code, so it must not contain typecasts or
2792 integer size suffixes (e.g. "ULL").
2794 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
2795 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
2796 used in assembly code, so it must not contain typecasts or
2797 integer size suffixes (e.g. "ULL").
2799 - CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
2800 If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
2801 forced to a value that ensures that CCSR is not relocated.
2803 - CONFIG_IDE_AHB:
2804 Most IDE controllers were designed to be connected with PCI
2805 interface. Only few of them were designed for AHB interface.
2806 When software is doing ATA command and data transfer to
2807 IDE devices through IDE-AHB controller, some additional
2808 registers accessing to these kind of IDE-AHB controller
2809 is required.
2811 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
2812 DO NOT CHANGE unless you know exactly what you're
2813 doing! (11-4) [MPC8xx systems only]
2815 - CONFIG_SYS_INIT_RAM_ADDR:
2817 Start address of memory area that can be used for
2818 initial data and stack; please note that this must be
2819 writable memory that is working WITHOUT special
2820 initialization, i. e. you CANNOT use normal RAM which
2821 will become available only after programming the
2822 memory controller and running certain initialization
2823 sequences.
2825 U-Boot uses the following memory types:
2826 - MPC8xx: IMMR (internal memory of the CPU)
2828 - CONFIG_SYS_GBL_DATA_OFFSET:
2830 Offset of the initial data structure in the memory
2831 area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
2832 CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
2833 data is located at the end of the available space
2834 (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
2835 GENERATED_GBL_DATA_SIZE), and the initial stack is just
2836 below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
2837 CONFIG_SYS_GBL_DATA_OFFSET) downward.
2839 Note:
2840 On the MPC824X (or other systems that use the data
2841 cache for initial memory) the address chosen for
2842 CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
2843 point to an otherwise UNUSED address space between
2844 the top of RAM and the start of the PCI space.
2846 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
2848 - CONFIG_SYS_OR_TIMING_SDRAM:
2849 SDRAM timing
2851 - CONFIG_SYS_MAMR_PTA:
2852 periodic timer for refresh
2854 - FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
2855 CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
2856 CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
2857 CONFIG_SYS_BR1_PRELIM:
2858 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
2860 - SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
2861 CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
2862 CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
2863 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
2865 - CONFIG_PCI_ENUM_ONLY
2866 Only scan through and get the devices on the buses.
2867 Don't do any setup work, presumably because someone or
2868 something has already done it, and we don't need to do it
2869 a second time. Useful for platforms that are pre-booted
2870 by coreboot or similar.
2872 - CONFIG_PCI_INDIRECT_BRIDGE:
2873 Enable support for indirect PCI bridges.
2875 - CONFIG_SYS_SRIO:
2876 Chip has SRIO or not
2878 - CONFIG_SRIO1:
2879 Board has SRIO 1 port available
2881 - CONFIG_SRIO2:
2882 Board has SRIO 2 port available
2884 - CONFIG_SRIO_PCIE_BOOT_MASTER
2885 Board can support master function for Boot from SRIO and PCIE
2887 - CONFIG_SYS_SRIOn_MEM_VIRT:
2888 Virtual Address of SRIO port 'n' memory region
2890 - CONFIG_SYS_SRIOn_MEM_PHYxS:
2891 Physical Address of SRIO port 'n' memory region
2893 - CONFIG_SYS_SRIOn_MEM_SIZE:
2894 Size of SRIO port 'n' memory region
2896 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
2897 Defined to tell the NAND controller that the NAND chip is using
2898 a 16 bit bus.
2899 Not all NAND drivers use this symbol.
2900 Example of drivers that use it:
2901 - drivers/mtd/nand/raw/ndfc.c
2902 - drivers/mtd/nand/raw/mxc_nand.c
2904 - CONFIG_SYS_NDFC_EBC0_CFG
2905 Sets the EBC0_CFG register for the NDFC. If not defined
2906 a default value will be used.
2908 - CONFIG_SPD_EEPROM
2909 Get DDR timing information from an I2C EEPROM. Common
2910 with pluggable memory modules such as SODIMMs
2912 SPD_EEPROM_ADDRESS
2913 I2C address of the SPD EEPROM
2915 - CONFIG_SYS_SPD_BUS_NUM
2916 If SPD EEPROM is on an I2C bus other than the first
2917 one, specify here. Note that the value must resolve
2918 to something your driver can deal with.
2920 - CONFIG_SYS_DDR_RAW_TIMING
2921 Get DDR timing information from other than SPD. Common with
2922 soldered DDR chips onboard without SPD. DDR raw timing
2923 parameters are extracted from datasheet and hard-coded into
2924 header files or board specific files.
2926 - CONFIG_FSL_DDR_INTERACTIVE
2927 Enable interactive DDR debugging. See doc/README.fsl-ddr.
2929 - CONFIG_FSL_DDR_SYNC_REFRESH
2930 Enable sync of refresh for multiple controllers.
2932 - CONFIG_FSL_DDR_BIST
2933 Enable built-in memory test for Freescale DDR controllers.
2935 - CONFIG_SYS_83XX_DDR_USES_CS0
2936 Only for 83xx systems. If specified, then DDR should
2937 be configured using CS0 and CS1 instead of CS2 and CS3.
2939 - CONFIG_RMII
2940 Enable RMII mode for all FECs.
2941 Note that this is a global option, we can't
2942 have one FEC in standard MII mode and another in RMII mode.
2944 - CONFIG_CRC32_VERIFY
2945 Add a verify option to the crc32 command.
2946 The syntax is:
2948 => crc32 -v <address> <count> <crc32>
2950 Where address/count indicate a memory area
2951 and crc32 is the correct crc32 which the
2952 area should have.
2954 - CONFIG_LOOPW
2955 Add the "loopw" memory command. This only takes effect if
2956 the memory commands are activated globally (CONFIG_CMD_MEMORY).
2958 - CONFIG_CMD_MX_CYCLIC
2959 Add the "mdc" and "mwc" memory commands. These are cyclic
2960 "md/mw" commands.
2961 Examples:
2963 => mdc.b 10 4 500
2964 This command will print 4 bytes (10,11,12,13) each 500 ms.
2966 => mwc.l 100 12345678 10
2967 This command will write 12345678 to address 100 all 10 ms.
2969 This only takes effect if the memory commands are activated
2970 globally (CONFIG_CMD_MEMORY).
2972 - CONFIG_SKIP_LOWLEVEL_INIT
2973 [ARM, NDS32, MIPS, RISC-V only] If this variable is defined, then certain
2974 low level initializations (like setting up the memory
2975 controller) are omitted and/or U-Boot does not
2976 relocate itself into RAM.
2978 Normally this variable MUST NOT be defined. The only
2979 exception is when U-Boot is loaded (to RAM) by some
2980 other boot loader or by a debugger which performs
2981 these initializations itself.
2983 - CONFIG_SKIP_LOWLEVEL_INIT_ONLY
2984 [ARM926EJ-S only] This allows just the call to lowlevel_init()
2985 to be skipped. The normal CP15 init (such as enabling the
2986 instruction cache) is still performed.
2988 - CONFIG_SPL_BUILD
2989 Set when the currently-running compilation is for an artifact
2990 that will end up in the SPL (as opposed to the TPL or U-Boot
2991 proper). Code that needs stage-specific behavior should check
2992 this.
2994 - CONFIG_TPL_BUILD
2995 Set when the currently-running compilation is for an artifact
2996 that will end up in the TPL (as opposed to the SPL or U-Boot
2997 proper). Code that needs stage-specific behavior should check
2998 this.
3000 - CONFIG_SYS_MPC85XX_NO_RESETVEC
3001 Only for 85xx systems. If this variable is specified, the section
3002 .resetvec is not kept and the section .bootpg is placed in the
3003 previous 4k of the .text section.
3005 - CONFIG_ARCH_MAP_SYSMEM
3006 Generally U-Boot (and in particular the md command) uses
3007 effective address. It is therefore not necessary to regard
3008 U-Boot address as virtual addresses that need to be translated
3009 to physical addresses. However, sandbox requires this, since
3010 it maintains its own little RAM buffer which contains all
3011 addressable memory. This option causes some memory accesses
3012 to be mapped through map_sysmem() / unmap_sysmem().
3014 - CONFIG_X86_RESET_VECTOR
3015 If defined, the x86 reset vector code is included. This is not
3016 needed when U-Boot is running from Coreboot.
3018 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
3019 Option to disable subpage write in NAND driver
3020 driver that uses this:
3021 drivers/mtd/nand/raw/davinci_nand.c
3023 Freescale QE/FMAN Firmware Support:
3024 -----------------------------------
3026 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
3027 loading of "firmware", which is encoded in the QE firmware binary format.
3028 This firmware often needs to be loaded during U-Boot booting, so macros
3029 are used to identify the storage device (NOR flash, SPI, etc) and the address
3030 within that device.
3032 - CONFIG_SYS_FMAN_FW_ADDR
3033 The address in the storage device where the FMAN microcode is located. The
3034 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
3035 is also specified.
3037 - CONFIG_SYS_QE_FW_ADDR
3038 The address in the storage device where the QE microcode is located. The
3039 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
3040 is also specified.
3042 - CONFIG_SYS_QE_FMAN_FW_LENGTH
3043 The maximum possible size of the firmware. The firmware binary format
3044 has a field that specifies the actual size of the firmware, but it
3045 might not be possible to read any part of the firmware unless some
3046 local storage is allocated to hold the entire firmware first.
3048 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
3049 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
3050 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
3051 virtual address in NOR flash.
3053 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
3054 Specifies that QE/FMAN firmware is located in NAND flash.
3055 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
3057 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
3058 Specifies that QE/FMAN firmware is located on the primary SD/MMC
3059 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
3061 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
3062 Specifies that QE/FMAN firmware is located in the remote (master)
3063 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
3064 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
3065 window->master inbound window->master LAW->the ucode address in
3066 master's memory space.
3068 Freescale Layerscape Management Complex Firmware Support:
3069 ---------------------------------------------------------
3070 The Freescale Layerscape Management Complex (MC) supports the loading of
3071 "firmware".
3072 This firmware often needs to be loaded during U-Boot booting, so macros
3073 are used to identify the storage device (NOR flash, SPI, etc) and the address
3074 within that device.
3076 - CONFIG_FSL_MC_ENET
3077 Enable the MC driver for Layerscape SoCs.
3079 Freescale Layerscape Debug Server Support:
3080 -------------------------------------------
3081 The Freescale Layerscape Debug Server Support supports the loading of
3082 "Debug Server firmware" and triggering SP boot-rom.
3083 This firmware often needs to be loaded during U-Boot booting.
3085 - CONFIG_SYS_MC_RSV_MEM_ALIGN
3086 Define alignment of reserved memory MC requires
3088 Reproducible builds
3089 -------------------
3091 In order to achieve reproducible builds, timestamps used in the U-Boot build
3092 process have to be set to a fixed value.
3094 This is done using the SOURCE_DATE_EPOCH environment variable.
3095 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
3096 option for U-Boot or an environment variable in U-Boot.
3098 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
3100 Building the Software:
3101 ======================
3103 Building U-Boot has been tested in several native build environments
3104 and in many different cross environments. Of course we cannot support
3105 all possibly existing versions of cross development tools in all
3106 (potentially obsolete) versions. In case of tool chain problems we
3107 recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
3108 which is extensively used to build and test U-Boot.
3110 If you are not using a native environment, it is assumed that you
3111 have GNU cross compiling tools available in your path. In this case,
3112 you must set the environment variable CROSS_COMPILE in your shell.
3113 Note that no changes to the Makefile or any other source files are
3114 necessary. For example using the ELDK on a 4xx CPU, please enter:
3116 $ CROSS_COMPILE=ppc_4xx-
3117 $ export CROSS_COMPILE
3119 U-Boot is intended to be simple to build. After installing the
3120 sources you must configure U-Boot for one specific board type. This
3121 is done by typing:
3123 make NAME_defconfig
3125 where "NAME_defconfig" is the name of one of the existing configu-
3126 rations; see configs/*_defconfig for supported names.
3128 Note: for some boards special configuration names may exist; check if
3129 additional information is available from the board vendor; for
3130 instance, the TQM823L systems are available without (standard)
3131 or with LCD support. You can select such additional "features"
3132 when choosing the configuration, i. e.
3134 make TQM823L_defconfig
3135 - will configure for a plain TQM823L, i. e. no LCD support
3137 make TQM823L_LCD_defconfig
3138 - will configure for a TQM823L with U-Boot console on LCD
3140 etc.
3143 Finally, type "make all", and you should get some working U-Boot
3144 images ready for download to / installation on your system:
3146 - "u-boot.bin" is a raw binary image
3147 - "u-boot" is an image in ELF binary format
3148 - "u-boot.srec" is in Motorola S-Record format
3150 By default the build is performed locally and the objects are saved
3151 in the source directory. One of the two methods can be used to change
3152 this behavior and build U-Boot to some external directory:
3154 1. Add O= to the make command line invocations:
3156 make O=/tmp/build distclean
3157 make O=/tmp/build NAME_defconfig
3158 make O=/tmp/build all
3160 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
3162 export KBUILD_OUTPUT=/tmp/build
3163 make distclean
3164 make NAME_defconfig
3165 make all
3167 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
3168 variable.
3170 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
3171 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
3172 For example to treat all compiler warnings as errors:
3174 make KCFLAGS=-Werror
3176 Please be aware that the Makefiles assume you are using GNU make, so
3177 for instance on NetBSD you might need to use "gmake" instead of
3178 native "make".
3181 If the system board that you have is not listed, then you will need
3182 to port U-Boot to your hardware platform. To do this, follow these
3183 steps:
3185 1. Create a new directory to hold your board specific code. Add any
3186 files you need. In your board directory, you will need at least
3187 the "Makefile" and a "<board>.c".
3188 2. Create a new configuration file "include/configs/<board>.h" for
3189 your board.
3190 3. If you're porting U-Boot to a new CPU, then also create a new
3191 directory to hold your CPU specific code. Add any files you need.
3192 4. Run "make <board>_defconfig" with your new name.
3193 5. Type "make", and you should get a working "u-boot.srec" file
3194 to be installed on your target system.
3195 6. Debug and solve any problems that might arise.
3196 [Of course, this last step is much harder than it sounds.]
3199 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
3200 ==============================================================
3202 If you have modified U-Boot sources (for instance added a new board
3203 or support for new devices, a new CPU, etc.) you are expected to
3204 provide feedback to the other developers. The feedback normally takes
3205 the form of a "patch", i.e. a context diff against a certain (latest
3206 official or latest in the git repository) version of U-Boot sources.
3208 But before you submit such a patch, please verify that your modifi-
3209 cation did not break existing code. At least make sure that *ALL* of
3210 the supported boards compile WITHOUT ANY compiler warnings. To do so,
3211 just run the buildman script (tools/buildman/buildman), which will
3212 configure and build U-Boot for ALL supported system. Be warned, this
3213 will take a while. Please see the buildman README, or run 'buildman -H'
3214 for documentation.
3217 See also "U-Boot Porting Guide" below.
3220 Monitor Commands - Overview:
3221 ============================
3223 go - start application at address 'addr'
3224 run - run commands in an environment variable
3225 bootm - boot application image from memory
3226 bootp - boot image via network using BootP/TFTP protocol
3227 bootz - boot zImage from memory
3228 tftpboot- boot image via network using TFTP protocol
3229 and env variables "ipaddr" and "serverip"
3230 (and eventually "gatewayip")
3231 tftpput - upload a file via network using TFTP protocol
3232 rarpboot- boot image via network using RARP/TFTP protocol
3233 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
3234 loads - load S-Record file over serial line
3235 loadb - load binary file over serial line (kermit mode)
3236 md - memory display
3237 mm - memory modify (auto-incrementing)
3238 nm - memory modify (constant address)
3239 mw - memory write (fill)
3240 cp - memory copy
3241 cmp - memory compare
3242 crc32 - checksum calculation
3243 i2c - I2C sub-system
3244 sspi - SPI utility commands
3245 base - print or set address offset
3246 printenv- print environment variables
3247 setenv - set environment variables
3248 saveenv - save environment variables to persistent storage
3249 protect - enable or disable FLASH write protection
3250 erase - erase FLASH memory
3251 flinfo - print FLASH memory information
3252 nand - NAND memory operations (see doc/README.nand)
3253 bdinfo - print Board Info structure
3254 iminfo - print header information for application image
3255 coninfo - print console devices and informations
3256 ide - IDE sub-system
3257 loop - infinite loop on address range
3258 loopw - infinite write loop on address range
3259 mtest - simple RAM test
3260 icache - enable or disable instruction cache
3261 dcache - enable or disable data cache
3262 reset - Perform RESET of the CPU
3263 echo - echo args to console
3264 version - print monitor version
3265 help - print online help
3266 ? - alias for 'help'
3269 Monitor Commands - Detailed Description:
3270 ========================================
3272 TODO.
3274 For now: just type "help <command>".
3277 Environment Variables:
3278 ======================
3280 U-Boot supports user configuration using Environment Variables which
3281 can be made persistent by saving to Flash memory.
3283 Environment Variables are set using "setenv", printed using
3284 "printenv", and saved to Flash using "saveenv". Using "setenv"
3285 without a value can be used to delete a variable from the
3286 environment. As long as you don't save the environment you are
3287 working with an in-memory copy. In case the Flash area containing the
3288 environment is erased by accident, a default environment is provided.
3290 Some configuration options can be set using Environment Variables.
3292 List of environment variables (most likely not complete):
3294 baudrate - see CONFIG_BAUDRATE
3296 bootdelay - see CONFIG_BOOTDELAY
3298 bootcmd - see CONFIG_BOOTCOMMAND
3300 bootargs - Boot arguments when booting an RTOS image
3302 bootfile - Name of the image to load with TFTP
3304 bootm_low - Memory range available for image processing in the bootm
3305 command can be restricted. This variable is given as
3306 a hexadecimal number and defines lowest address allowed
3307 for use by the bootm command. See also "bootm_size"
3308 environment variable. Address defined by "bootm_low" is
3309 also the base of the initial memory mapping for the Linux
3310 kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
3311 bootm_mapsize.
3313 bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
3314 This variable is given as a hexadecimal number and it
3315 defines the size of the memory region starting at base
3316 address bootm_low that is accessible by the Linux kernel
3317 during early boot. If unset, CONFIG_SYS_BOOTMAPSZ is used
3318 as the default value if it is defined, and bootm_size is
3319 used otherwise.
3321 bootm_size - Memory range available for image processing in the bootm
3322 command can be restricted. This variable is given as
3323 a hexadecimal number and defines the size of the region
3324 allowed for use by the bootm command. See also "bootm_low"
3325 environment variable.
3327 bootstopkeysha256, bootdelaykey, bootstopkey - See README.autoboot
3329 updatefile - Location of the software update file on a TFTP server, used
3330 by the automatic software update feature. Please refer to
3331 documentation in doc/README.update for more details.
3333 autoload - if set to "no" (any string beginning with 'n'),
3334 "bootp" will just load perform a lookup of the
3335 configuration from the BOOTP server, but not try to
3336 load any image using TFTP
3338 autostart - if set to "yes", an image loaded using the "bootp",
3339 "rarpboot", "tftpboot" or "diskboot" commands will
3340 be automatically started (by internally calling
3341 "bootm")
3343 If set to "no", a standalone image passed to the
3344 "bootm" command will be copied to the load address
3345 (and eventually uncompressed), but NOT be started.
3346 This can be used to load and uncompress arbitrary
3347 data.
3349 fdt_high - if set this restricts the maximum address that the
3350 flattened device tree will be copied into upon boot.
3351 For example, if you have a system with 1 GB memory
3352 at physical address 0x10000000, while Linux kernel
3353 only recognizes the first 704 MB as low memory, you
3354 may need to set fdt_high as 0x3C000000 to have the
3355 device tree blob be copied to the maximum address
3356 of the 704 MB low memory, so that Linux kernel can
3357 access it during the boot procedure.
3359 If this is set to the special value 0xFFFFFFFF then
3360 the fdt will not be copied at all on boot. For this
3361 to work it must reside in writable memory, have
3362 sufficient padding on the end of it for u-boot to
3363 add the information it needs into it, and the memory
3364 must be accessible by the kernel.
3366 fdtcontroladdr- if set this is the address of the control flattened
3367 device tree used by U-Boot when CONFIG_OF_CONTROL is
3368 defined.
3370 i2cfast - (PPC405GP|PPC405EP only)
3371 if set to 'y' configures Linux I2C driver for fast
3372 mode (400kHZ). This environment variable is used in
3373 initialization code. So, for changes to be effective
3374 it must be saved and board must be reset.
3376 initrd_high - restrict positioning of initrd images:
3377 If this variable is not set, initrd images will be
3378 copied to the highest possible address in RAM; this
3379 is usually what you want since it allows for
3380 maximum initrd size. If for some reason you want to
3381 make sure that the initrd image is loaded below the
3382 CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
3383 variable to a value of "no" or "off" or "0".
3384 Alternatively, you can set it to a maximum upper
3385 address to use (U-Boot will still check that it
3386 does not overwrite the U-Boot stack and data).
3388 For instance, when you have a system with 16 MB
3389 RAM, and want to reserve 4 MB from use by Linux,
3390 you can do this by adding "mem=12M" to the value of
3391 the "bootargs" variable. However, now you must make
3392 sure that the initrd image is placed in the first
3393 12 MB as well - this can be done with
3395 setenv initrd_high 00c00000
3397 If you set initrd_high to 0xFFFFFFFF, this is an
3398 indication to U-Boot that all addresses are legal
3399 for the Linux kernel, including addresses in flash
3400 memory. In this case U-Boot will NOT COPY the
3401 ramdisk at all. This may be useful to reduce the
3402 boot time on your system, but requires that this
3403 feature is supported by your Linux kernel.
3405 ipaddr - IP address; needed for tftpboot command
3407 loadaddr - Default load address for commands like "bootp",
3408 "rarpboot", "tftpboot", "loadb" or "diskboot"
3410 loads_echo - see CONFIG_LOADS_ECHO
3412 serverip - TFTP server IP address; needed for tftpboot command
3414 bootretry - see CONFIG_BOOT_RETRY_TIME
3416 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
3418 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
3420 ethprime - controls which interface is used first.
3422 ethact - controls which interface is currently active.
3423 For example you can do the following
3425 => setenv ethact FEC
3426 => ping 192.168.0.1 # traffic sent on FEC
3427 => setenv ethact SCC
3428 => ping 10.0.0.1 # traffic sent on SCC
3430 ethrotate - When set to "no" U-Boot does not go through all
3431 available network interfaces.
3432 It just stays at the currently selected interface.
3434 netretry - When set to "no" each network operation will
3435 either succeed or fail without retrying.
3436 When set to "once" the network operation will
3437 fail when all the available network interfaces
3438 are tried once without success.
3439 Useful on scripts which control the retry operation
3440 themselves.
3442 npe_ucode - set load address for the NPE microcode
3444 silent_linux - If set then Linux will be told to boot silently, by
3445 changing the console to be empty. If "yes" it will be
3446 made silent. If "no" it will not be made silent. If
3447 unset, then it will be made silent if the U-Boot console
3448 is silent.
3450 tftpsrcp - If this is set, the value is used for TFTP's
3451 UDP source port.
3453 tftpdstp - If this is set, the value is used for TFTP's UDP
3454 destination port instead of the Well Know Port 69.
3456 tftpblocksize - Block size to use for TFTP transfers; if not set,
3457 we use the TFTP server's default block size
3459 tftptimeout - Retransmission timeout for TFTP packets (in milli-
3460 seconds, minimum value is 1000 = 1 second). Defines
3461 when a packet is considered to be lost so it has to
3462 be retransmitted. The default is 5000 = 5 seconds.
3463 Lowering this value may make downloads succeed
3464 faster in networks with high packet loss rates or
3465 with unreliable TFTP servers.
3467 tftptimeoutcountmax - maximum count of TFTP timeouts (no
3468 unit, minimum value = 0). Defines how many timeouts
3469 can happen during a single file transfer before that
3470 transfer is aborted. The default is 10, and 0 means
3471 'no timeouts allowed'. Increasing this value may help
3472 downloads succeed with high packet loss rates, or with
3473 unreliable TFTP servers or client hardware.
3475 vlan - When set to a value < 4095 the traffic over
3476 Ethernet is encapsulated/received over 802.1q
3477 VLAN tagged frames.
3479 bootpretryperiod - Period during which BOOTP/DHCP sends retries.
3480 Unsigned value, in milliseconds. If not set, the period will
3481 be either the default (28000), or a value based on
3482 CONFIG_NET_RETRY_COUNT, if defined. This value has
3483 precedence over the valu based on CONFIG_NET_RETRY_COUNT.
3485 The following image location variables contain the location of images
3486 used in booting. The "Image" column gives the role of the image and is
3487 not an environment variable name. The other columns are environment
3488 variable names. "File Name" gives the name of the file on a TFTP
3489 server, "RAM Address" gives the location in RAM the image will be
3490 loaded to, and "Flash Location" gives the image's address in NOR
3491 flash or offset in NAND flash.
3493 *Note* - these variables don't have to be defined for all boards, some
3494 boards currently use other variables for these purposes, and some
3495 boards use these variables for other purposes.
3497 Image File Name RAM Address Flash Location
3498 ----- --------- ----------- --------------
3499 u-boot u-boot u-boot_addr_r u-boot_addr
3500 Linux kernel bootfile kernel_addr_r kernel_addr
3501 device tree blob fdtfile fdt_addr_r fdt_addr
3502 ramdisk ramdiskfile ramdisk_addr_r ramdisk_addr
3504 The following environment variables may be used and automatically
3505 updated by the network boot commands ("bootp" and "rarpboot"),
3506 depending the information provided by your boot server:
3508 bootfile - see above
3509 dnsip - IP address of your Domain Name Server
3510 dnsip2 - IP address of your secondary Domain Name Server
3511 gatewayip - IP address of the Gateway (Router) to use
3512 hostname - Target hostname
3513 ipaddr - see above
3514 netmask - Subnet Mask
3515 rootpath - Pathname of the root filesystem on the NFS server
3516 serverip - see above
3519 There are two special Environment Variables:
3521 serial# - contains hardware identification information such
3522 as type string and/or serial number
3523 ethaddr - Ethernet address
3525 These variables can be set only once (usually during manufacturing of
3526 the board). U-Boot refuses to delete or overwrite these variables
3527 once they have been set once.
3530 Further special Environment Variables:
3532 ver - Contains the U-Boot version string as printed
3533 with the "version" command. This variable is
3534 readonly (see CONFIG_VERSION_VARIABLE).
3537 Please note that changes to some configuration parameters may take
3538 only effect after the next boot (yes, that's just like Windoze :-).
3541 Callback functions for environment variables:
3542 ---------------------------------------------
3544 For some environment variables, the behavior of u-boot needs to change
3545 when their values are changed. This functionality allows functions to
3546 be associated with arbitrary variables. On creation, overwrite, or
3547 deletion, the callback will provide the opportunity for some side
3548 effect to happen or for the change to be rejected.
3550 The callbacks are named and associated with a function using the
3551 U_BOOT_ENV_CALLBACK macro in your board or driver code.
3553 These callbacks are associated with variables in one of two ways. The
3554 static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
3555 in the board configuration to a string that defines a list of
3556 associations. The list must be in the following format:
3558 entry = variable_name[:callback_name]
3559 list = entry[,list]
3561 If the callback name is not specified, then the callback is deleted.
3562 Spaces are also allowed anywhere in the list.
3564 Callbacks can also be associated by defining the ".callbacks" variable
3565 with the same list format above. Any association in ".callbacks" will
3566 override any association in the static list. You can define
3567 CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
3568 ".callbacks" environment variable in the default or embedded environment.
3570 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
3571 regular expression. This allows multiple variables to be connected to
3572 the same callback without explicitly listing them all out.
3574 The signature of the callback functions is:
3576 int callback(const char *name, const char *value, enum env_op op, int flags)
3578 * name - changed environment variable
3579 * value - new value of the environment variable
3580 * op - operation (create, overwrite, or delete)
3581 * flags - attributes of the environment variable change, see flags H_* in
3582 include/search.h
3584 The return value is 0 if the variable change is accepted and 1 otherwise.
3586 Command Line Parsing:
3587 =====================
3589 There are two different command line parsers available with U-Boot:
3590 the old "simple" one, and the much more powerful "hush" shell:
3592 Old, simple command line parser:
3593 --------------------------------
3595 - supports environment variables (through setenv / saveenv commands)
3596 - several commands on one line, separated by ';'
3597 - variable substitution using "... ${name} ..." syntax
3598 - special characters ('$', ';') can be escaped by prefixing with '\',
3599 for example:
3600 setenv bootcmd bootm \${address}
3601 - You can also escape text by enclosing in single apostrophes, for example:
3602 setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
3604 Hush shell:
3605 -----------
3607 - similar to Bourne shell, with control structures like
3608 if...then...else...fi, for...do...done; while...do...done,
3609 until...do...done, ...
3610 - supports environment ("global") variables (through setenv / saveenv
3611 commands) and local shell variables (through standard shell syntax
3612 "name=value"); only environment variables can be used with "run"
3613 command
3615 General rules:
3616 --------------
3618 (1) If a command line (or an environment variable executed by a "run"
3619 command) contains several commands separated by semicolon, and
3620 one of these commands fails, then the remaining commands will be
3621 executed anyway.
3623 (2) If you execute several variables with one call to run (i. e.
3624 calling run with a list of variables as arguments), any failing
3625 command will cause "run" to terminate, i. e. the remaining
3626 variables are not executed.
3628 Note for Redundant Ethernet Interfaces:
3629 =======================================
3631 Some boards come with redundant Ethernet interfaces; U-Boot supports
3632 such configurations and is capable of automatic selection of a
3633 "working" interface when needed. MAC assignment works as follows:
3635 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
3636 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
3637 "eth1addr" (=>eth1), "eth2addr", ...
3639 If the network interface stores some valid MAC address (for instance
3640 in SROM), this is used as default address if there is NO correspon-
3641 ding setting in the environment; if the corresponding environment
3642 variable is set, this overrides the settings in the card; that means:
3644 o If the SROM has a valid MAC address, and there is no address in the
3645 environment, the SROM's address is used.
3647 o If there is no valid address in the SROM, and a definition in the
3648 environment exists, then the value from the environment variable is
3649 used.
3651 o If both the SROM and the environment contain a MAC address, and
3652 both addresses are the same, this MAC address is used.
3654 o If both the SROM and the environment contain a MAC address, and the
3655 addresses differ, the value from the environment is used and a
3656 warning is printed.
3658 o If neither SROM nor the environment contain a MAC address, an error
3659 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
3660 a random, locally-assigned MAC is used.
3662 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
3663 will be programmed into hardware as part of the initialization process. This
3664 may be skipped by setting the appropriate 'ethmacskip' environment variable.
3665 The naming convention is as follows:
3666 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
3668 Image Formats:
3669 ==============
3671 U-Boot is capable of booting (and performing other auxiliary operations on)
3672 images in two formats:
3674 New uImage format (FIT)
3675 -----------------------
3677 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
3678 to Flattened Device Tree). It allows the use of images with multiple
3679 components (several kernels, ramdisks, etc.), with contents protected by
3680 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
3683 Old uImage format
3684 -----------------
3686 Old image format is based on binary files which can be basically anything,
3687 preceded by a special header; see the definitions in include/image.h for
3688 details; basically, the header defines the following image properties:
3690 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
3691 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
3692 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
3693 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
3694 INTEGRITY).
3695 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
3696 IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
3697 Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC).
3698 * Compression Type (uncompressed, gzip, bzip2)
3699 * Load Address
3700 * Entry Point
3701 * Image Name
3702 * Image Timestamp
3704 The header is marked by a special Magic Number, and both the header
3705 and the data portions of the image are secured against corruption by
3706 CRC32 checksums.
3709 Linux Support:
3710 ==============
3712 Although U-Boot should support any OS or standalone application
3713 easily, the main focus has always been on Linux during the design of
3714 U-Boot.
3716 U-Boot includes many features that so far have been part of some
3717 special "boot loader" code within the Linux kernel. Also, any
3718 "initrd" images to be used are no longer part of one big Linux image;
3719 instead, kernel and "initrd" are separate images. This implementation
3720 serves several purposes:
3722 - the same features can be used for other OS or standalone
3723 applications (for instance: using compressed images to reduce the
3724 Flash memory footprint)
3726 - it becomes much easier to port new Linux kernel versions because
3727 lots of low-level, hardware dependent stuff are done by U-Boot
3729 - the same Linux kernel image can now be used with different "initrd"
3730 images; of course this also means that different kernel images can
3731 be run with the same "initrd". This makes testing easier (you don't
3732 have to build a new "zImage.initrd" Linux image when you just
3733 change a file in your "initrd"). Also, a field-upgrade of the
3734 software is easier now.
3737 Linux HOWTO:
3738 ============
3740 Porting Linux to U-Boot based systems:
3741 ---------------------------------------
3743 U-Boot cannot save you from doing all the necessary modifications to
3744 configure the Linux device drivers for use with your target hardware
3745 (no, we don't intend to provide a full virtual machine interface to
3746 Linux :-).
3748 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
3750 Just make sure your machine specific header file (for instance
3751 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
3752 Information structure as we define in include/asm-<arch>/u-boot.h,
3753 and make sure that your definition of IMAP_ADDR uses the same value
3754 as your U-Boot configuration in CONFIG_SYS_IMMR.
3756 Note that U-Boot now has a driver model, a unified model for drivers.
3757 If you are adding a new driver, plumb it into driver model. If there
3758 is no uclass available, you are encouraged to create one. See
3759 doc/driver-model.
3762 Configuring the Linux kernel:
3763 -----------------------------
3765 No specific requirements for U-Boot. Make sure you have some root
3766 device (initial ramdisk, NFS) for your target system.
3769 Building a Linux Image:
3770 -----------------------
3772 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
3773 not used. If you use recent kernel source, a new build target
3774 "uImage" will exist which automatically builds an image usable by
3775 U-Boot. Most older kernels also have support for a "pImage" target,
3776 which was introduced for our predecessor project PPCBoot and uses a
3777 100% compatible format.
3779 Example:
3781 make TQM850L_defconfig
3782 make oldconfig
3783 make dep
3784 make uImage
3786 The "uImage" build target uses a special tool (in 'tools/mkimage') to
3787 encapsulate a compressed Linux kernel image with header information,
3788 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
3790 * build a standard "vmlinux" kernel image (in ELF binary format):
3792 * convert the kernel into a raw binary image:
3794 ${CROSS_COMPILE}-objcopy -O binary \
3795 -R .note -R .comment \
3796 -S vmlinux linux.bin
3798 * compress the binary image:
3800 gzip -9 linux.bin
3802 * package compressed binary image for U-Boot:
3804 mkimage -A ppc -O linux -T kernel -C gzip \
3805 -a 0 -e 0 -n "Linux Kernel Image" \
3806 -d linux.bin.gz uImage
3809 The "mkimage" tool can also be used to create ramdisk images for use
3810 with U-Boot, either separated from the Linux kernel image, or
3811 combined into one file. "mkimage" encapsulates the images with a 64
3812 byte header containing information about target architecture,
3813 operating system, image type, compression method, entry points, time
3814 stamp, CRC32 checksums, etc.
3816 "mkimage" can be called in two ways: to verify existing images and
3817 print the header information, or to build new images.
3819 In the first form (with "-l" option) mkimage lists the information
3820 contained in the header of an existing U-Boot image; this includes
3821 checksum verification:
3823 tools/mkimage -l image
3824 -l ==> list image header information
3826 The second form (with "-d" option) is used to build a U-Boot image
3827 from a "data file" which is used as image payload:
3829 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
3830 -n name -d data_file image
3831 -A ==> set architecture to 'arch'
3832 -O ==> set operating system to 'os'
3833 -T ==> set image type to 'type'
3834 -C ==> set compression type 'comp'
3835 -a ==> set load address to 'addr' (hex)
3836 -e ==> set entry point to 'ep' (hex)
3837 -n ==> set image name to 'name'
3838 -d ==> use image data from 'datafile'
3840 Right now, all Linux kernels for PowerPC systems use the same load
3841 address (0x00000000), but the entry point address depends on the
3842 kernel version:
3844 - 2.2.x kernels have the entry point at 0x0000000C,
3845 - 2.3.x and later kernels have the entry point at 0x00000000.
3847 So a typical call to build a U-Boot image would read:
3849 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3850 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
3851 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
3852 > examples/uImage.TQM850L
3853 Image Name: 2.4.4 kernel for TQM850L
3854 Created: Wed Jul 19 02:34:59 2000
3855 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3856 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3857 Load Address: 0x00000000
3858 Entry Point: 0x00000000
3860 To verify the contents of the image (or check for corruption):
3862 -> tools/mkimage -l examples/uImage.TQM850L
3863 Image Name: 2.4.4 kernel for TQM850L
3864 Created: Wed Jul 19 02:34:59 2000
3865 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3866 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3867 Load Address: 0x00000000
3868 Entry Point: 0x00000000
3870 NOTE: for embedded systems where boot time is critical you can trade
3871 speed for memory and install an UNCOMPRESSED image instead: this
3872 needs more space in Flash, but boots much faster since it does not
3873 need to be uncompressed:
3875 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
3876 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3877 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3878 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
3879 > examples/uImage.TQM850L-uncompressed
3880 Image Name: 2.4.4 kernel for TQM850L
3881 Created: Wed Jul 19 02:34:59 2000
3882 Image Type: PowerPC Linux Kernel Image (uncompressed)
3883 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
3884 Load Address: 0x00000000
3885 Entry Point: 0x00000000
3888 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3889 when your kernel is intended to use an initial ramdisk:
3891 -> tools/mkimage -n 'Simple Ramdisk Image' \
3892 > -A ppc -O linux -T ramdisk -C gzip \
3893 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3894 Image Name: Simple Ramdisk Image
3895 Created: Wed Jan 12 14:01:50 2000
3896 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3897 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
3898 Load Address: 0x00000000
3899 Entry Point: 0x00000000
3901 The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
3902 option performs the converse operation of the mkimage's second form (the "-d"
3903 option). Given an image built by mkimage, the dumpimage extracts a "data file"
3904 from the image:
3906 tools/dumpimage -i image -T type -p position data_file
3907 -i ==> extract from the 'image' a specific 'data_file'
3908 -T ==> set image type to 'type'
3909 -p ==> 'position' (starting at 0) of the 'data_file' inside the 'image'
3912 Installing a Linux Image:
3913 -------------------------
3915 To downloading a U-Boot image over the serial (console) interface,
3916 you must convert the image to S-Record format:
3918 objcopy -I binary -O srec examples/image examples/image.srec
3920 The 'objcopy' does not understand the information in the U-Boot
3921 image header, so the resulting S-Record file will be relative to
3922 address 0x00000000. To load it to a given address, you need to
3923 specify the target address as 'offset' parameter with the 'loads'
3924 command.
3926 Example: install the image to address 0x40100000 (which on the
3927 TQM8xxL is in the first Flash bank):
3929 => erase 40100000 401FFFFF
3931 .......... done
3932 Erased 8 sectors
3934 => loads 40100000
3935 ## Ready for S-Record download ...
3936 ~>examples/image.srec
3937 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3938 ...
3939 15989 15990 15991 15992
3940 [file transfer complete]
3941 [connected]
3942 ## Start Addr = 0x00000000
3945 You can check the success of the download using the 'iminfo' command;
3946 this includes a checksum verification so you can be sure no data
3947 corruption happened:
3949 => imi 40100000
3951 ## Checking Image at 40100000 ...
3952 Image Name: 2.2.13 for initrd on TQM850L
3953 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3954 Data Size: 335725 Bytes = 327 kB = 0 MB
3955 Load Address: 00000000
3956 Entry Point: 0000000c
3957 Verifying Checksum ... OK
3960 Boot Linux:
3961 -----------
3963 The "bootm" command is used to boot an application that is stored in
3964 memory (RAM or Flash). In case of a Linux kernel image, the contents
3965 of the "bootargs" environment variable is passed to the kernel as
3966 parameters. You can check and modify this variable using the
3967 "printenv" and "setenv" commands:
3970 => printenv bootargs
3971 bootargs=root=/dev/ram
3973 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3975 => printenv bootargs
3976 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3978 => bootm 40020000
3979 ## Booting Linux kernel at 40020000 ...
3980 Image Name: 2.2.13 for NFS on TQM850L
3981 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3982 Data Size: 381681 Bytes = 372 kB = 0 MB
3983 Load Address: 00000000
3984 Entry Point: 0000000c
3985 Verifying Checksum ... OK
3986 Uncompressing Kernel Image ... OK
3987 Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:35:17 MEST 2000
3988 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3989 time_init: decrementer frequency = 187500000/60
3990 Calibrating delay loop... 49.77 BogoMIPS
3991 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3992 ...
3994 If you want to boot a Linux kernel with initial RAM disk, you pass
3995 the memory addresses of both the kernel and the initrd image (PPBCOOT
3996 format!) to the "bootm" command:
3998 => imi 40100000 40200000
4000 ## Checking Image at 40100000 ...
4001 Image Name: 2.2.13 for initrd on TQM850L
4002 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4003 Data Size: 335725 Bytes = 327 kB = 0 MB
4004 Load Address: 00000000
4005 Entry Point: 0000000c
4006 Verifying Checksum ... OK
4008 ## Checking Image at 40200000 ...
4009 Image Name: Simple Ramdisk Image
4010 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
4011 Data Size: 566530 Bytes = 553 kB = 0 MB
4012 Load Address: 00000000
4013 Entry Point: 00000000
4014 Verifying Checksum ... OK
4016 => bootm 40100000 40200000
4017 ## Booting Linux kernel at 40100000 ...
4018 Image Name: 2.2.13 for initrd on TQM850L
4019 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4020 Data Size: 335725 Bytes = 327 kB = 0 MB
4021 Load Address: 00000000
4022 Entry Point: 0000000c
4023 Verifying Checksum ... OK
4024 Uncompressing Kernel Image ... OK
4025 ## Loading RAMDisk Image at 40200000 ...
4026 Image Name: Simple Ramdisk Image
4027 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
4028 Data Size: 566530 Bytes = 553 kB = 0 MB
4029 Load Address: 00000000
4030 Entry Point: 00000000
4031 Verifying Checksum ... OK
4032 Loading Ramdisk ... OK
4033 Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:32:08 MEST 2000
4034 Boot arguments: root=/dev/ram
4035 time_init: decrementer frequency = 187500000/60
4036 Calibrating delay loop... 49.77 BogoMIPS
4037 ...
4038 RAMDISK: Compressed image found at block 0
4039 VFS: Mounted root (ext2 filesystem).
4041 bash#
4043 Boot Linux and pass a flat device tree:
4044 -----------
4046 First, U-Boot must be compiled with the appropriate defines. See the section
4047 titled "Linux Kernel Interface" above for a more in depth explanation. The
4048 following is an example of how to start a kernel and pass an updated
4049 flat device tree:
4051 => print oftaddr
4052 oftaddr=0x300000
4053 => print oft
4054 oft=oftrees/mpc8540ads.dtb
4055 => tftp $oftaddr $oft
4056 Speed: 1000, full duplex
4057 Using TSEC0 device
4058 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
4059 Filename 'oftrees/mpc8540ads.dtb'.
4060 Load address: 0x300000
4061 Loading: #
4062 done
4063 Bytes transferred = 4106 (100a hex)
4064 => tftp $loadaddr $bootfile
4065 Speed: 1000, full duplex
4066 Using TSEC0 device
4067 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
4068 Filename 'uImage'.
4069 Load address: 0x200000
4070 Loading:############
4071 done
4072 Bytes transferred = 1029407 (fb51f hex)
4073 => print loadaddr
4074 loadaddr=200000
4075 => print oftaddr
4076 oftaddr=0x300000
4077 => bootm $loadaddr - $oftaddr
4078 ## Booting image at 00200000 ...
4079 Image Name: Linux-2.6.17-dirty
4080 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4081 Data Size: 1029343 Bytes = 1005.2 kB
4082 Load Address: 00000000
4083 Entry Point: 00000000
4084 Verifying Checksum ... OK
4085 Uncompressing Kernel Image ... OK
4086 Booting using flat device tree at 0x300000
4087 Using MPC85xx ADS machine description
4088 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
4089 [snip]
4092 More About U-Boot Image Types:
4093 ------------------------------
4095 U-Boot supports the following image types:
4097 "Standalone Programs" are directly runnable in the environment
4098 provided by U-Boot; it is expected that (if they behave
4099 well) you can continue to work in U-Boot after return from
4100 the Standalone Program.
4101 "OS Kernel Images" are usually images of some Embedded OS which
4102 will take over control completely. Usually these programs
4103 will install their own set of exception handlers, device
4104 drivers, set up the MMU, etc. - this means, that you cannot
4105 expect to re-enter U-Boot except by resetting the CPU.
4106 "RAMDisk Images" are more or less just data blocks, and their
4107 parameters (address, size) are passed to an OS kernel that is
4108 being started.
4109 "Multi-File Images" contain several images, typically an OS
4110 (Linux) kernel image and one or more data images like
4111 RAMDisks. This construct is useful for instance when you want
4112 to boot over the network using BOOTP etc., where the boot
4113 server provides just a single image file, but you want to get
4114 for instance an OS kernel and a RAMDisk image.
4116 "Multi-File Images" start with a list of image sizes, each
4117 image size (in bytes) specified by an "uint32_t" in network
4118 byte order. This list is terminated by an "(uint32_t)0".
4119 Immediately after the terminating 0 follow the images, one by
4120 one, all aligned on "uint32_t" boundaries (size rounded up to
4121 a multiple of 4 bytes).
4123 "Firmware Images" are binary images containing firmware (like
4124 U-Boot or FPGA images) which usually will be programmed to
4125 flash memory.
4127 "Script files" are command sequences that will be executed by
4128 U-Boot's command interpreter; this feature is especially
4129 useful when you configure U-Boot to use a real shell (hush)
4130 as command interpreter.
4132 Booting the Linux zImage:
4133 -------------------------
4135 On some platforms, it's possible to boot Linux zImage. This is done
4136 using the "bootz" command. The syntax of "bootz" command is the same
4137 as the syntax of "bootm" command.
4139 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
4140 kernel with raw initrd images. The syntax is slightly different, the
4141 address of the initrd must be augmented by it's size, in the following
4142 format: "<initrd addres>:<initrd size>".
4145 Standalone HOWTO:
4146 =================
4148 One of the features of U-Boot is that you can dynamically load and
4149 run "standalone" applications, which can use some resources of
4150 U-Boot like console I/O functions or interrupt services.
4152 Two simple examples are included with the sources:
4154 "Hello World" Demo:
4155 -------------------
4157 'examples/hello_world.c' contains a small "Hello World" Demo
4158 application; it is automatically compiled when you build U-Boot.
4159 It's configured to run at address 0x00040004, so you can play with it
4160 like that:
4162 => loads
4163 ## Ready for S-Record download ...
4164 ~>examples/hello_world.srec
4165 1 2 3 4 5 6 7 8 9 10 11 ...
4166 [file transfer complete]
4167 [connected]
4168 ## Start Addr = 0x00040004
4170 => go 40004 Hello World! This is a test.
4171 ## Starting application at 0x00040004 ...
4172 Hello World
4173 argc = 7
4174 argv[0] = "40004"
4175 argv[1] = "Hello"
4176 argv[2] = "World!"
4177 argv[3] = "This"
4178 argv[4] = "is"
4179 argv[5] = "a"
4180 argv[6] = "test."
4181 argv[7] = "<NULL>"
4182 Hit any key to exit ...
4184 ## Application terminated, rc = 0x0
4186 Another example, which demonstrates how to register a CPM interrupt
4187 handler with the U-Boot code, can be found in 'examples/timer.c'.
4188 Here, a CPM timer is set up to generate an interrupt every second.
4189 The interrupt service routine is trivial, just printing a '.'
4190 character, but this is just a demo program. The application can be
4191 controlled by the following keys:
4193 ? - print current values og the CPM Timer registers
4194 b - enable interrupts and start timer
4195 e - stop timer and disable interrupts
4196 q - quit application
4198 => loads
4199 ## Ready for S-Record download ...
4200 ~>examples/timer.srec
4201 1 2 3 4 5 6 7 8 9 10 11 ...
4202 [file transfer complete]
4203 [connected]
4204 ## Start Addr = 0x00040004
4206 => go 40004
4207 ## Starting application at 0x00040004 ...
4208 TIMERS=0xfff00980
4209 Using timer 1
4210 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
4212 Hit 'b':
4213 [q, b, e, ?] Set interval 1000000 us
4214 Enabling timer
4215 Hit '?':
4216 [q, b, e, ?] ........
4217 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
4218 Hit '?':
4219 [q, b, e, ?] .
4220 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
4221 Hit '?':
4222 [q, b, e, ?] .
4223 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
4224 Hit '?':
4225 [q, b, e, ?] .
4226 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
4227 Hit 'e':
4228 [q, b, e, ?] ...Stopping timer
4229 Hit 'q':
4230 [q, b, e, ?] ## Application terminated, rc = 0x0
4233 Minicom warning:
4234 ================
4236 Over time, many people have reported problems when trying to use the
4237 "minicom" terminal emulation program for serial download. I (wd)
4238 consider minicom to be broken, and recommend not to use it. Under
4239 Unix, I recommend to use C-Kermit for general purpose use (and
4240 especially for kermit binary protocol download ("loadb" command), and
4241 use "cu" for S-Record download ("loads" command). See
4242 http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
4243 for help with kermit.
4246 Nevertheless, if you absolutely want to use it try adding this
4247 configuration to your "File transfer protocols" section:
4249 Name Program Name U/D FullScr IO-Red. Multi
4250 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
4251 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
4254 NetBSD Notes:
4255 =============
4257 Starting at version 0.9.2, U-Boot supports NetBSD both as host
4258 (build U-Boot) and target system (boots NetBSD/mpc8xx).
4260 Building requires a cross environment; it is known to work on
4261 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
4262 need gmake since the Makefiles are not compatible with BSD make).
4263 Note that the cross-powerpc package does not install include files;
4264 attempting to build U-Boot will fail because <machine/ansi.h> is
4265 missing. This file has to be installed and patched manually:
4267 # cd /usr/pkg/cross/powerpc-netbsd/include
4268 # mkdir powerpc
4269 # ln -s powerpc machine
4270 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
4271 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
4273 Native builds *don't* work due to incompatibilities between native
4274 and U-Boot include files.
4276 Booting assumes that (the first part of) the image booted is a
4277 stage-2 loader which in turn loads and then invokes the kernel
4278 proper. Loader sources will eventually appear in the NetBSD source
4279 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
4280 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
4283 Implementation Internals:
4284 =========================
4286 The following is not intended to be a complete description of every
4287 implementation detail. However, it should help to understand the
4288 inner workings of U-Boot and make it easier to port it to custom
4289 hardware.
4292 Initial Stack, Global Data:
4293 ---------------------------
4295 The implementation of U-Boot is complicated by the fact that U-Boot
4296 starts running out of ROM (flash memory), usually without access to
4297 system RAM (because the memory controller is not initialized yet).
4298 This means that we don't have writable Data or BSS segments, and BSS
4299 is not initialized as zero. To be able to get a C environment working
4300 at all, we have to allocate at least a minimal stack. Implementation
4301 options for this are defined and restricted by the CPU used: Some CPU
4302 models provide on-chip memory (like the IMMR area on MPC8xx and
4303 MPC826x processors), on others (parts of) the data cache can be
4304 locked as (mis-) used as memory, etc.
4306 Chris Hallinan posted a good summary of these issues to the
4307 U-Boot mailing list:
4309 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
4310 From: "Chris Hallinan" <clh@net1plus.com>
4311 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
4312 ...
4314 Correct me if I'm wrong, folks, but the way I understand it
4315 is this: Using DCACHE as initial RAM for Stack, etc, does not
4316 require any physical RAM backing up the cache. The cleverness
4317 is that the cache is being used as a temporary supply of
4318 necessary storage before the SDRAM controller is setup. It's
4319 beyond the scope of this list to explain the details, but you
4320 can see how this works by studying the cache architecture and
4321 operation in the architecture and processor-specific manuals.
4323 OCM is On Chip Memory, which I believe the 405GP has 4K. It
4324 is another option for the system designer to use as an
4325 initial stack/RAM area prior to SDRAM being available. Either
4326 option should work for you. Using CS 4 should be fine if your
4327 board designers haven't used it for something that would
4328 cause you grief during the initial boot! It is frequently not
4329 used.
4331 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
4332 with your processor/board/system design. The default value
4333 you will find in any recent u-boot distribution in
4334 walnut.h should work for you. I'd set it to a value larger
4335 than your SDRAM module. If you have a 64MB SDRAM module, set
4336 it above 400_0000. Just make sure your board has no resources
4337 that are supposed to respond to that address! That code in
4338 start.S has been around a while and should work as is when
4339 you get the config right.
4341 -Chris Hallinan
4342 DS4.COM, Inc.
4344 It is essential to remember this, since it has some impact on the C
4345 code for the initialization procedures:
4347 * Initialized global data (data segment) is read-only. Do not attempt
4348 to write it.
4350 * Do not use any uninitialized global data (or implicitly initialized
4351 as zero data - BSS segment) at all - this is undefined, initiali-
4352 zation is performed later (when relocating to RAM).
4354 * Stack space is very limited. Avoid big data buffers or things like
4355 that.
4357 Having only the stack as writable memory limits means we cannot use
4358 normal global data to share information between the code. But it
4359 turned out that the implementation of U-Boot can be greatly
4360 simplified by making a global data structure (gd_t) available to all
4361 functions. We could pass a pointer to this data as argument to _all_
4362 functions, but this would bloat the code. Instead we use a feature of
4363 the GCC compiler (Global Register Variables) to share the data: we
4364 place a pointer (gd) to the global data into a register which we
4365 reserve for this purpose.
4367 When choosing a register for such a purpose we are restricted by the
4368 relevant (E)ABI specifications for the current architecture, and by
4369 GCC's implementation.
4371 For PowerPC, the following registers have specific use:
4372 R1: stack pointer
4373 R2: reserved for system use
4374 R3-R4: parameter passing and return values
4375 R5-R10: parameter passing
4376 R13: small data area pointer
4377 R30: GOT pointer
4378 R31: frame pointer
4380 (U-Boot also uses R12 as internal GOT pointer. r12
4381 is a volatile register so r12 needs to be reset when
4382 going back and forth between asm and C)
4384 ==> U-Boot will use R2 to hold a pointer to the global data
4386 Note: on PPC, we could use a static initializer (since the
4387 address of the global data structure is known at compile time),
4388 but it turned out that reserving a register results in somewhat
4389 smaller code - although the code savings are not that big (on
4390 average for all boards 752 bytes for the whole U-Boot image,
4391 624 text + 127 data).
4393 On ARM, the following registers are used:
4395 R0: function argument word/integer result
4396 R1-R3: function argument word
4397 R9: platform specific
4398 R10: stack limit (used only if stack checking is enabled)
4399 R11: argument (frame) pointer
4400 R12: temporary workspace
4401 R13: stack pointer
4402 R14: link register
4403 R15: program counter
4405 ==> U-Boot will use R9 to hold a pointer to the global data
4407 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
4409 On Nios II, the ABI is documented here:
4410 http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
4412 ==> U-Boot will use gp to hold a pointer to the global data
4414 Note: on Nios II, we give "-G0" option to gcc and don't use gp
4415 to access small data sections, so gp is free.
4417 On NDS32, the following registers are used:
4419 R0-R1: argument/return
4420 R2-R5: argument
4421 R15: temporary register for assembler
4422 R16: trampoline register
4423 R28: frame pointer (FP)
4424 R29: global pointer (GP)
4425 R30: link register (LP)
4426 R31: stack pointer (SP)
4427 PC: program counter (PC)
4429 ==> U-Boot will use R10 to hold a pointer to the global data
4431 NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
4432 or current versions of GCC may "optimize" the code too much.
4434 On RISC-V, the following registers are used:
4436 x0: hard-wired zero (zero)
4437 x1: return address (ra)
4438 x2: stack pointer (sp)
4439 x3: global pointer (gp)
4440 x4: thread pointer (tp)
4441 x5: link register (t0)
4442 x8: frame pointer (fp)
4443 x10-x11: arguments/return values (a0-1)
4444 x12-x17: arguments (a2-7)
4445 x28-31: temporaries (t3-6)
4446 pc: program counter (pc)
4448 ==> U-Boot will use gp to hold a pointer to the global data
4450 Memory Management:
4451 ------------------
4453 U-Boot runs in system state and uses physical addresses, i.e. the
4454 MMU is not used either for address mapping nor for memory protection.
4456 The available memory is mapped to fixed addresses using the memory
4457 controller. In this process, a contiguous block is formed for each
4458 memory type (Flash, SDRAM, SRAM), even when it consists of several
4459 physical memory banks.
4461 U-Boot is installed in the first 128 kB of the first Flash bank (on
4462 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
4463 booting and sizing and initializing DRAM, the code relocates itself
4464 to the upper end of DRAM. Immediately below the U-Boot code some
4465 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
4466 configuration setting]. Below that, a structure with global Board
4467 Info data is placed, followed by the stack (growing downward).
4469 Additionally, some exception handler code is copied to the low 8 kB
4470 of DRAM (0x00000000 ... 0x00001FFF).
4472 So a typical memory configuration with 16 MB of DRAM could look like
4473 this:
4475 0x0000 0000 Exception Vector code
4476 :
4477 0x0000 1FFF
4478 0x0000 2000 Free for Application Use
4479 :
4480 :
4482 :
4483 :
4484 0x00FB FF20 Monitor Stack (Growing downward)
4485 0x00FB FFAC Board Info Data and permanent copy of global data
4486 0x00FC 0000 Malloc Arena
4487 :
4488 0x00FD FFFF
4489 0x00FE 0000 RAM Copy of Monitor Code
4490 ... eventually: LCD or video framebuffer
4491 ... eventually: pRAM (Protected RAM - unchanged by reset)
4492 0x00FF FFFF [End of RAM]
4495 System Initialization:
4496 ----------------------
4498 In the reset configuration, U-Boot starts at the reset entry point
4499 (on most PowerPC systems at address 0x00000100). Because of the reset
4500 configuration for CS0# this is a mirror of the on board Flash memory.
4501 To be able to re-map memory U-Boot then jumps to its link address.
4502 To be able to implement the initialization code in C, a (small!)
4503 initial stack is set up in the internal Dual Ported RAM (in case CPUs
4504 which provide such a feature like), or in a locked part of the data
4505 cache. After that, U-Boot initializes the CPU core, the caches and
4506 the SIU.
4508 Next, all (potentially) available memory banks are mapped using a
4509 preliminary mapping. For example, we put them on 512 MB boundaries
4510 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
4511 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
4512 programmed for SDRAM access. Using the temporary configuration, a
4513 simple memory test is run that determines the size of the SDRAM
4514 banks.
4516 When there is more than one SDRAM bank, and the banks are of
4517 different size, the largest is mapped first. For equal size, the first
4518 bank (CS2#) is mapped first. The first mapping is always for address
4519 0x00000000, with any additional banks following immediately to create
4520 contiguous memory starting from 0.
4522 Then, the monitor installs itself at the upper end of the SDRAM area
4523 and allocates memory for use by malloc() and for the global Board
4524 Info data; also, the exception vector code is copied to the low RAM
4525 pages, and the final stack is set up.
4527 Only after this relocation will you have a "normal" C environment;
4528 until that you are restricted in several ways, mostly because you are
4529 running from ROM, and because the code will have to be relocated to a
4530 new address in RAM.
4533 U-Boot Porting Guide:
4534 ----------------------
4536 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
4537 list, October 2002]
4540 int main(int argc, char *argv[])
4541 {
4542 sighandler_t no_more_time;
4544 signal(SIGALRM, no_more_time);
4545 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
4547 if (available_money > available_manpower) {
4548 Pay consultant to port U-Boot;
4549 return 0;
4550 }
4552 Download latest U-Boot source;
4554 Subscribe to u-boot mailing list;
4556 if (clueless)
4557 email("Hi, I am new to U-Boot, how do I get started?");
4559 while (learning) {
4560 Read the README file in the top level directory;
4561 Read http://www.denx.de/twiki/bin/view/DULG/Manual;
4562 Read applicable doc/README.*;
4563 Read the source, Luke;
4564 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
4565 }
4567 if (available_money > toLocalCurrency ($2500))
4568 Buy a BDI3000;
4569 else
4570 Add a lot of aggravation and time;
4572 if (a similar board exists) { /* hopefully... */
4573 cp -a board/<similar> board/<myboard>
4574 cp include/configs/<similar>.h include/configs/<myboard>.h
4575 } else {
4576 Create your own board support subdirectory;
4577 Create your own board include/configs/<myboard>.h file;
4578 }
4579 Edit new board/<myboard> files
4580 Edit new include/configs/<myboard>.h
4582 while (!accepted) {
4583 while (!running) {
4584 do {
4585 Add / modify source code;
4586 } until (compiles);
4587 Debug;
4588 if (clueless)
4589 email("Hi, I am having problems...");
4590 }
4591 Send patch file to the U-Boot email list;
4592 if (reasonable critiques)
4593 Incorporate improvements from email list code review;
4594 else
4595 Defend code as written;
4596 }
4598 return 0;
4599 }
4601 void no_more_time (int sig)
4602 {
4603 hire_a_guru();
4604 }
4607 Coding Standards:
4608 -----------------
4610 All contributions to U-Boot should conform to the Linux kernel
4611 coding style; see the kernel coding style guide at
4612 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
4613 script "scripts/Lindent" in your Linux kernel source directory.
4615 Source files originating from a different project (for example the
4616 MTD subsystem) are generally exempt from these guidelines and are not
4617 reformatted to ease subsequent migration to newer versions of those
4618 sources.
4620 Please note that U-Boot is implemented in C (and to some small parts in
4621 Assembler); no C++ is used, so please do not use C++ style comments (//)
4622 in your code.
4624 Please also stick to the following formatting rules:
4625 - remove any trailing white space
4626 - use TAB characters for indentation and vertical alignment, not spaces
4627 - make sure NOT to use DOS '\r\n' line feeds
4628 - do not add more than 2 consecutive empty lines to source files
4629 - do not add trailing empty lines to source files
4631 Submissions which do not conform to the standards may be returned
4632 with a request to reformat the changes.
4635 Submitting Patches:
4636 -------------------
4638 Since the number of patches for U-Boot is growing, we need to
4639 establish some rules. Submissions which do not conform to these rules
4640 may be rejected, even when they contain important and valuable stuff.
4642 Please see http://www.denx.de/wiki/U-Boot/Patches for details.
4644 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
4645 see https://lists.denx.de/listinfo/u-boot
4647 When you send a patch, please include the following information with
4648 it:
4650 * For bug fixes: a description of the bug and how your patch fixes
4651 this bug. Please try to include a way of demonstrating that the
4652 patch actually fixes something.
4654 * For new features: a description of the feature and your
4655 implementation.
4657 * For major contributions, add a MAINTAINERS file with your
4658 information and associated file and directory references.
4660 * When you add support for a new board, don't forget to add a
4661 maintainer e-mail address to the boards.cfg file, too.
4663 * If your patch adds new configuration options, don't forget to
4664 document these in the README file.
4666 * The patch itself. If you are using git (which is *strongly*
4667 recommended) you can easily generate the patch using the
4668 "git format-patch". If you then use "git send-email" to send it to
4669 the U-Boot mailing list, you will avoid most of the common problems
4670 with some other mail clients.
4672 If you cannot use git, use "diff -purN OLD NEW". If your version of
4673 diff does not support these options, then get the latest version of
4674 GNU diff.
4676 The current directory when running this command shall be the parent
4677 directory of the U-Boot source tree (i. e. please make sure that
4678 your patch includes sufficient directory information for the
4679 affected files).
4681 We prefer patches as plain text. MIME attachments are discouraged,
4682 and compressed attachments must not be used.
4684 * If one logical set of modifications affects or creates several
4685 files, all these changes shall be submitted in a SINGLE patch file.
4687 * Changesets that contain different, unrelated modifications shall be
4688 submitted as SEPARATE patches, one patch per changeset.
4691 Notes:
4693 * Before sending the patch, run the buildman script on your patched
4694 source tree and make sure that no errors or warnings are reported
4695 for any of the boards.
4697 * Keep your modifications to the necessary minimum: A patch
4698 containing several unrelated changes or arbitrary reformats will be
4699 returned with a request to re-formatting / split it.
4701 * If you modify existing code, make sure that your new code does not
4702 add to the memory footprint of the code ;-) Small is beautiful!
4703 When adding new features, these should compile conditionally only
4704 (using #ifdef), and the resulting code with the new feature
4705 disabled must not need more memory than the old code without your
4706 modification.
4708 * Remember that there is a size limit of 100 kB per message on the
4709 u-boot mailing list. Bigger patches will be moderated. If they are
4710 reasonable and not too big, they will be acknowledged. But patches
4711 bigger than the size limit should be avoided.