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_NATSEMI
875 Support for National dp83815 chips.
877 CONFIG_NS8382X
878 Support for National dp8382[01] gigabit chips.
880 - NETWORK Support (other):
882 CONFIG_DRIVER_AT91EMAC
883 Support for AT91RM9200 EMAC.
885 CONFIG_RMII
886 Define this to use reduced MII inteface
888 CONFIG_DRIVER_AT91EMAC_QUIET
889 If this defined, the driver is quiet.
890 The driver doen't show link status messages.
892 CONFIG_CALXEDA_XGMAC
893 Support for the Calxeda XGMAC device
895 CONFIG_LAN91C96
896 Support for SMSC's LAN91C96 chips.
898 CONFIG_LAN91C96_USE_32_BIT
899 Define this to enable 32 bit addressing
901 CONFIG_SMC91111
902 Support for SMSC's LAN91C111 chip
904 CONFIG_SMC91111_BASE
905 Define this to hold the physical address
906 of the device (I/O space)
908 CONFIG_SMC_USE_32_BIT
909 Define this if data bus is 32 bits
911 CONFIG_SMC_USE_IOFUNCS
912 Define this to use i/o functions instead of macros
913 (some hardware wont work with macros)
915 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
916 Define this if you have more then 3 PHYs.
918 CONFIG_FTGMAC100
919 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
921 CONFIG_FTGMAC100_EGIGA
922 Define this to use GE link update with gigabit PHY.
923 Define this if FTGMAC100 is connected to gigabit PHY.
924 If your system has 10/100 PHY only, it might not occur
925 wrong behavior. Because PHY usually return timeout or
926 useless data when polling gigabit status and gigabit
927 control registers. This behavior won't affect the
928 correctnessof 10/100 link speed update.
930 CONFIG_SH_ETHER
931 Support for Renesas on-chip Ethernet controller
933 CONFIG_SH_ETHER_USE_PORT
934 Define the number of ports to be used
936 CONFIG_SH_ETHER_PHY_ADDR
937 Define the ETH PHY's address
939 CONFIG_SH_ETHER_CACHE_WRITEBACK
940 If this option is set, the driver enables cache flush.
942 - TPM Support:
943 CONFIG_TPM
944 Support TPM devices.
946 CONFIG_TPM_TIS_INFINEON
947 Support for Infineon i2c bus TPM devices. Only one device
948 per system is supported at this time.
950 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
951 Define the burst count bytes upper limit
953 CONFIG_TPM_ST33ZP24
954 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
956 CONFIG_TPM_ST33ZP24_I2C
957 Support for STMicroelectronics ST33ZP24 I2C devices.
958 Requires TPM_ST33ZP24 and I2C.
960 CONFIG_TPM_ST33ZP24_SPI
961 Support for STMicroelectronics ST33ZP24 SPI devices.
962 Requires TPM_ST33ZP24 and SPI.
964 CONFIG_TPM_ATMEL_TWI
965 Support for Atmel TWI TPM device. Requires I2C support.
967 CONFIG_TPM_TIS_LPC
968 Support for generic parallel port TPM devices. Only one device
969 per system is supported at this time.
971 CONFIG_TPM_TIS_BASE_ADDRESS
972 Base address where the generic TPM device is mapped
973 to. Contemporary x86 systems usually map it at
974 0xfed40000.
976 CONFIG_TPM
977 Define this to enable the TPM support library which provides
978 functional interfaces to some TPM commands.
979 Requires support for a TPM device.
981 CONFIG_TPM_AUTH_SESSIONS
982 Define this to enable authorized functions in the TPM library.
983 Requires CONFIG_TPM and CONFIG_SHA1.
985 - USB Support:
986 At the moment only the UHCI host controller is
987 supported (PIP405, MIP405); define
988 CONFIG_USB_UHCI to enable it.
989 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
990 and define CONFIG_USB_STORAGE to enable the USB
991 storage devices.
992 Note:
993 Supported are USB Keyboards and USB Floppy drives
994 (TEAC FD-05PUB).
996 CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
997 txfilltuning field in the EHCI controller on reset.
999 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
1000 HW module registers.
1002 - USB Device:
1003 Define the below if you wish to use the USB console.
1004 Once firmware is rebuilt from a serial console issue the
1005 command "setenv stdin usbtty; setenv stdout usbtty" and
1006 attach your USB cable. The Unix command "dmesg" should print
1007 it has found a new device. The environment variable usbtty
1008 can be set to gserial or cdc_acm to enable your device to
1009 appear to a USB host as a Linux gserial device or a
1010 Common Device Class Abstract Control Model serial device.
1011 If you select usbtty = gserial you should be able to enumerate
1012 a Linux host by
1013 # modprobe usbserial vendor=0xVendorID product=0xProductID
1014 else if using cdc_acm, simply setting the environment
1015 variable usbtty to be cdc_acm should suffice. The following
1016 might be defined in YourBoardName.h
1018 CONFIG_USB_DEVICE
1019 Define this to build a UDC device
1021 CONFIG_USB_TTY
1022 Define this to have a tty type of device available to
1023 talk to the UDC device
1025 CONFIG_USBD_HS
1026 Define this to enable the high speed support for usb
1027 device and usbtty. If this feature is enabled, a routine
1028 int is_usbd_high_speed(void)
1029 also needs to be defined by the driver to dynamically poll
1030 whether the enumeration has succeded at high speed or full
1031 speed.
1033 CONFIG_SYS_CONSOLE_IS_IN_ENV
1034 Define this if you want stdin, stdout &/or stderr to
1035 be set to usbtty.
1037 If you have a USB-IF assigned VendorID then you may wish to
1038 define your own vendor specific values either in BoardName.h
1039 or directly in usbd_vendor_info.h. If you don't define
1040 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1041 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1042 should pretend to be a Linux device to it's target host.
1044 CONFIG_USBD_MANUFACTURER
1045 Define this string as the name of your company for
1046 - CONFIG_USBD_MANUFACTURER "my company"
1048 CONFIG_USBD_PRODUCT_NAME
1049 Define this string as the name of your product
1050 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
1052 CONFIG_USBD_VENDORID
1053 Define this as your assigned Vendor ID from the USB
1054 Implementors Forum. This *must* be a genuine Vendor ID
1055 to avoid polluting the USB namespace.
1056 - CONFIG_USBD_VENDORID 0xFFFF
1058 CONFIG_USBD_PRODUCTID
1059 Define this as the unique Product ID
1060 for your device
1061 - CONFIG_USBD_PRODUCTID 0xFFFF
1063 - ULPI Layer Support:
1064 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1065 the generic ULPI layer. The generic layer accesses the ULPI PHY
1066 via the platform viewport, so you need both the genric layer and
1067 the viewport enabled. Currently only Chipidea/ARC based
1068 viewport is supported.
1069 To enable the ULPI layer support, define CONFIG_USB_ULPI and
1070 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1071 If your ULPI phy needs a different reference clock than the
1072 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1073 the appropriate value in Hz.
1075 - MMC Support:
1076 The MMC controller on the Intel PXA is supported. To
1077 enable this define CONFIG_MMC. The MMC can be
1078 accessed from the boot prompt by mapping the device
1079 to physical memory similar to flash. Command line is
1080 enabled with CONFIG_CMD_MMC. The MMC driver also works with
1081 the FAT fs. This is enabled with CONFIG_CMD_FAT.
1083 CONFIG_SH_MMCIF
1084 Support for Renesas on-chip MMCIF controller
1086 CONFIG_SH_MMCIF_ADDR
1087 Define the base address of MMCIF registers
1089 CONFIG_SH_MMCIF_CLK
1090 Define the clock frequency for MMCIF
1092 - USB Device Firmware Update (DFU) class support:
1093 CONFIG_DFU_OVER_USB
1094 This enables the USB portion of the DFU USB class
1096 CONFIG_DFU_NAND
1097 This enables support for exposing NAND devices via DFU.
1099 CONFIG_DFU_RAM
1100 This enables support for exposing RAM via DFU.
1101 Note: DFU spec refer to non-volatile memory usage, but
1102 allow usages beyond the scope of spec - here RAM usage,
1103 one that would help mostly the developer.
1105 CONFIG_SYS_DFU_DATA_BUF_SIZE
1106 Dfu transfer uses a buffer before writing data to the
1107 raw storage device. Make the size (in bytes) of this buffer
1108 configurable. The size of this buffer is also configurable
1109 through the "dfu_bufsiz" environment variable.
1111 CONFIG_SYS_DFU_MAX_FILE_SIZE
1112 When updating files rather than the raw storage device,
1113 we use a static buffer to copy the file into and then write
1114 the buffer once we've been given the whole file. Define
1115 this to the maximum filesize (in bytes) for the buffer.
1116 Default is 4 MiB if undefined.
1118 DFU_DEFAULT_POLL_TIMEOUT
1119 Poll timeout [ms], is the timeout a device can send to the
1120 host. The host must wait for this timeout before sending
1121 a subsequent DFU_GET_STATUS request to the device.
1123 DFU_MANIFEST_POLL_TIMEOUT
1124 Poll timeout [ms], which the device sends to the host when
1125 entering dfuMANIFEST state. Host waits this timeout, before
1126 sending again an USB request to the device.
1128 - Journaling Flash filesystem support:
1129 CONFIG_JFFS2_NAND
1130 Define these for a default partition on a NAND device
1132 CONFIG_SYS_JFFS2_FIRST_SECTOR,
1133 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1134 Define these for a default partition on a NOR device
1136 - Keyboard Support:
1137 See Kconfig help for available keyboard drivers.
1139 CONFIG_KEYBOARD
1141 Define this to enable a custom keyboard support.
1142 This simply calls drv_keyboard_init() which must be
1143 defined in your board-specific files. This option is deprecated
1144 and is only used by novena. For new boards, use driver model
1145 instead.
1147 - Video support:
1148 CONFIG_FSL_DIU_FB
1149 Enable the Freescale DIU video driver. Reference boards for
1150 SOCs that have a DIU should define this macro to enable DIU
1151 support, and should also define these other macros:
1153 CONFIG_SYS_DIU_ADDR
1154 CONFIG_VIDEO
1155 CONFIG_CFB_CONSOLE
1156 CONFIG_VIDEO_SW_CURSOR
1157 CONFIG_VGA_AS_SINGLE_DEVICE
1158 CONFIG_VIDEO_LOGO
1159 CONFIG_VIDEO_BMP_LOGO
1161 The DIU driver will look for the 'video-mode' environment
1162 variable, and if defined, enable the DIU as a console during
1163 boot. See the documentation file doc/README.video for a
1164 description of this variable.
1166 - LCD Support: CONFIG_LCD
1168 Define this to enable LCD support (for output to LCD
1169 display); also select one of the supported displays
1170 by defining one of these:
1172 CONFIG_ATMEL_LCD:
1174 HITACHI TX09D70VM1CCA, 3.5", 240x320.
1176 CONFIG_NEC_NL6448AC33:
1178 NEC NL6448AC33-18. Active, color, single scan.
1180 CONFIG_NEC_NL6448BC20
1182 NEC NL6448BC20-08. 6.5", 640x480.
1183 Active, color, single scan.
1185 CONFIG_NEC_NL6448BC33_54
1187 NEC NL6448BC33-54. 10.4", 640x480.
1188 Active, color, single scan.
1190 CONFIG_SHARP_16x9
1192 Sharp 320x240. Active, color, single scan.
1193 It isn't 16x9, and I am not sure what it is.
1195 CONFIG_SHARP_LQ64D341
1197 Sharp LQ64D341 display, 640x480.
1198 Active, color, single scan.
1200 CONFIG_HLD1045
1202 HLD1045 display, 640x480.
1203 Active, color, single scan.
1205 CONFIG_OPTREX_BW
1207 Optrex CBL50840-2 NF-FW 99 22 M5
1208 or
1209 Hitachi LMG6912RPFC-00T
1210 or
1211 Hitachi SP14Q002
1213 320x240. Black & white.
1215 CONFIG_LCD_ALIGNMENT
1217 Normally the LCD is page-aligned (typically 4KB). If this is
1218 defined then the LCD will be aligned to this value instead.
1219 For ARM it is sometimes useful to use MMU_SECTION_SIZE
1220 here, since it is cheaper to change data cache settings on
1221 a per-section basis.
1224 CONFIG_LCD_ROTATION
1226 Sometimes, for example if the display is mounted in portrait
1227 mode or even if it's mounted landscape but rotated by 180degree,
1228 we need to rotate our content of the display relative to the
1229 framebuffer, so that user can read the messages which are
1230 printed out.
1231 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1232 initialized with a given rotation from "vl_rot" out of
1233 "vidinfo_t" which is provided by the board specific code.
1234 The value for vl_rot is coded as following (matching to
1235 fbcon=rotate:<n> linux-kernel commandline):
1236 0 = no rotation respectively 0 degree
1237 1 = 90 degree rotation
1238 2 = 180 degree rotation
1239 3 = 270 degree rotation
1241 If CONFIG_LCD_ROTATION is not defined, the console will be
1242 initialized with 0degree rotation.
1244 CONFIG_LCD_BMP_RLE8
1246 Support drawing of RLE8-compressed bitmaps on the LCD.
1248 CONFIG_I2C_EDID
1250 Enables an 'i2c edid' command which can read EDID
1251 information over I2C from an attached LCD display.
1253 - Splash Screen Support: CONFIG_SPLASH_SCREEN
1255 If this option is set, the environment is checked for
1256 a variable "splashimage". If found, the usual display
1257 of logo, copyright and system information on the LCD
1258 is suppressed and the BMP image at the address
1259 specified in "splashimage" is loaded instead. The
1260 console is redirected to the "nulldev", too. This
1261 allows for a "silent" boot where a splash screen is
1262 loaded very quickly after power-on.
1264 CONFIG_SPLASHIMAGE_GUARD
1266 If this option is set, then U-Boot will prevent the environment
1267 variable "splashimage" from being set to a problematic address
1268 (see doc/README.displaying-bmps).
1269 This option is useful for targets where, due to alignment
1270 restrictions, an improperly aligned BMP image will cause a data
1271 abort. If you think you will not have problems with unaligned
1272 accesses (for example because your toolchain prevents them)
1273 there is no need to set this option.
1275 CONFIG_SPLASH_SCREEN_ALIGN
1277 If this option is set the splash image can be freely positioned
1278 on the screen. Environment variable "splashpos" specifies the
1279 position as "x,y". If a positive number is given it is used as
1280 number of pixel from left/top. If a negative number is given it
1281 is used as number of pixel from right/bottom. You can also
1282 specify 'm' for centering the image.
1284 Example:
1285 setenv splashpos m,m
1286 => image at center of screen
1288 setenv splashpos 30,20
1289 => image at x = 30 and y = 20
1291 setenv splashpos -10,m
1292 => vertically centered image
1293 at x = dspWidth - bmpWidth - 9
1295 - Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1297 If this option is set, additionally to standard BMP
1298 images, gzipped BMP images can be displayed via the
1299 splashscreen support or the bmp command.
1301 - Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1303 If this option is set, 8-bit RLE compressed BMP images
1304 can be displayed via the splashscreen support or the
1305 bmp command.
1307 - MII/PHY support:
1308 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1310 The clock frequency of the MII bus
1312 CONFIG_PHY_RESET_DELAY
1314 Some PHY like Intel LXT971A need extra delay after
1315 reset before any MII register access is possible.
1316 For such PHY, set this option to the usec delay
1317 required. (minimum 300usec for LXT971A)
1319 CONFIG_PHY_CMD_DELAY (ppc4xx)
1321 Some PHY like Intel LXT971A need extra delay after
1322 command issued before MII status register can be read
1324 - IP address:
1325 CONFIG_IPADDR
1327 Define a default value for the IP address to use for
1328 the default Ethernet interface, in case this is not
1329 determined through e.g. bootp.
1330 (Environment variable "ipaddr")
1332 - Server IP address:
1333 CONFIG_SERVERIP
1335 Defines a default value for the IP address of a TFTP
1336 server to contact when using the "tftboot" command.
1337 (Environment variable "serverip")
1339 CONFIG_KEEP_SERVERADDR
1341 Keeps the server's MAC address, in the env 'serveraddr'
1342 for passing to bootargs (like Linux's netconsole option)
1344 - Gateway IP address:
1345 CONFIG_GATEWAYIP
1347 Defines a default value for the IP address of the
1348 default router where packets to other networks are
1349 sent to.
1350 (Environment variable "gatewayip")
1352 - Subnet mask:
1353 CONFIG_NETMASK
1355 Defines a default value for the subnet mask (or
1356 routing prefix) which is used to determine if an IP
1357 address belongs to the local subnet or needs to be
1358 forwarded through a router.
1359 (Environment variable "netmask")
1361 - BOOTP Recovery Mode:
1362 CONFIG_BOOTP_RANDOM_DELAY
1364 If you have many targets in a network that try to
1365 boot using BOOTP, you may want to avoid that all
1366 systems send out BOOTP requests at precisely the same
1367 moment (which would happen for instance at recovery
1368 from a power failure, when all systems will try to
1369 boot, thus flooding the BOOTP server. Defining
1370 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1371 inserted before sending out BOOTP requests. The
1372 following delays are inserted then:
1374 1st BOOTP request: delay 0 ... 1 sec
1375 2nd BOOTP request: delay 0 ... 2 sec
1376 3rd BOOTP request: delay 0 ... 4 sec
1377 4th and following
1378 BOOTP requests: delay 0 ... 8 sec
1380 CONFIG_BOOTP_ID_CACHE_SIZE
1382 BOOTP packets are uniquely identified using a 32-bit ID. The
1383 server will copy the ID from client requests to responses and
1384 U-Boot will use this to determine if it is the destination of
1385 an incoming response. Some servers will check that addresses
1386 aren't in use before handing them out (usually using an ARP
1387 ping) and therefore take up to a few hundred milliseconds to
1388 respond. Network congestion may also influence the time it
1389 takes for a response to make it back to the client. If that
1390 time is too long, U-Boot will retransmit requests. In order
1391 to allow earlier responses to still be accepted after these
1392 retransmissions, U-Boot's BOOTP client keeps a small cache of
1393 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1394 cache. The default is to keep IDs for up to four outstanding
1395 requests. Increasing this will allow U-Boot to accept offers
1396 from a BOOTP client in networks with unusually high latency.
1398 - DHCP Advanced Options:
1399 You can fine tune the DHCP functionality by defining
1400 CONFIG_BOOTP_* symbols:
1402 CONFIG_BOOTP_NISDOMAIN
1403 CONFIG_BOOTP_BOOTFILESIZE
1404 CONFIG_BOOTP_NTPSERVER
1405 CONFIG_BOOTP_TIMEOFFSET
1406 CONFIG_BOOTP_VENDOREX
1407 CONFIG_BOOTP_MAY_FAIL
1409 CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1410 environment variable, not the BOOTP server.
1412 CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1413 after the configured retry count, the call will fail
1414 instead of starting over. This can be used to fail over
1415 to Link-local IP address configuration if the DHCP server
1416 is not available.
1418 CONFIG_BOOTP_DHCP_REQUEST_DELAY
1420 A 32bit value in microseconds for a delay between
1421 receiving a "DHCP Offer" and sending the "DHCP Request".
1422 This fixes a problem with certain DHCP servers that don't
1423 respond 100% of the time to a "DHCP request". E.g. On an
1424 AT91RM9200 processor running at 180MHz, this delay needed
1425 to be *at least* 15,000 usec before a Windows Server 2003
1426 DHCP server would reply 100% of the time. I recommend at
1427 least 50,000 usec to be safe. The alternative is to hope
1428 that one of the retries will be successful but note that
1429 the DHCP timeout and retry process takes a longer than
1430 this delay.
1432 - Link-local IP address negotiation:
1433 Negotiate with other link-local clients on the local network
1434 for an address that doesn't require explicit configuration.
1435 This is especially useful if a DHCP server cannot be guaranteed
1436 to exist in all environments that the device must operate.
1438 See doc/README.link-local for more information.
1440 - MAC address from environment variables
1442 FDT_SEQ_MACADDR_FROM_ENV
1444 Fix-up device tree with MAC addresses fetched sequentially from
1445 environment variables. This config work on assumption that
1446 non-usable ethernet node of device-tree are either not present
1447 or their status has been marked as "disabled".
1449 - CDP Options:
1450 CONFIG_CDP_DEVICE_ID
1452 The device id used in CDP trigger frames.
1454 CONFIG_CDP_DEVICE_ID_PREFIX
1456 A two character string which is prefixed to the MAC address
1457 of the device.
1459 CONFIG_CDP_PORT_ID
1461 A printf format string which contains the ascii name of
1462 the port. Normally is set to "eth%d" which sets
1463 eth0 for the first Ethernet, eth1 for the second etc.
1465 CONFIG_CDP_CAPABILITIES
1467 A 32bit integer which indicates the device capabilities;
1468 0x00000010 for a normal host which does not forwards.
1470 CONFIG_CDP_VERSION
1472 An ascii string containing the version of the software.
1474 CONFIG_CDP_PLATFORM
1476 An ascii string containing the name of the platform.
1478 CONFIG_CDP_TRIGGER
1480 A 32bit integer sent on the trigger.
1482 CONFIG_CDP_POWER_CONSUMPTION
1484 A 16bit integer containing the power consumption of the
1485 device in .1 of milliwatts.
1487 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1489 A byte containing the id of the VLAN.
1491 - Status LED: CONFIG_LED_STATUS
1493 Several configurations allow to display the current
1494 status using a LED. For instance, the LED will blink
1495 fast while running U-Boot code, stop blinking as
1496 soon as a reply to a BOOTP request was received, and
1497 start blinking slow once the Linux kernel is running
1498 (supported by a status LED driver in the Linux
1499 kernel). Defining CONFIG_LED_STATUS enables this
1500 feature in U-Boot.
1502 Additional options:
1504 CONFIG_LED_STATUS_GPIO
1505 The status LED can be connected to a GPIO pin.
1506 In such cases, the gpio_led driver can be used as a
1507 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1508 to include the gpio_led driver in the U-Boot binary.
1510 CONFIG_GPIO_LED_INVERTED_TABLE
1511 Some GPIO connected LEDs may have inverted polarity in which
1512 case the GPIO high value corresponds to LED off state and
1513 GPIO low value corresponds to LED on state.
1514 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1515 with a list of GPIO LEDs that have inverted polarity.
1517 - I2C Support: CONFIG_SYS_I2C
1519 This enable the NEW i2c subsystem, and will allow you to use
1520 i2c commands at the u-boot command line (as long as you set
1521 CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
1522 for defining speed and slave address
1523 - activate second bus with I2C_SOFT_DECLARATIONS2 define
1524 CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
1525 for defining speed and slave address
1526 - activate third bus with I2C_SOFT_DECLARATIONS3 define
1527 CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
1528 for defining speed and slave address
1529 - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
1530 CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
1531 for defining speed and slave address
1533 - drivers/i2c/fsl_i2c.c:
1534 - activate i2c driver with CONFIG_SYS_I2C_FSL
1535 define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
1536 offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
1537 CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
1538 bus.
1539 - If your board supports a second fsl i2c bus, define
1540 CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
1541 CONFIG_SYS_FSL_I2C2_SPEED for the speed and
1542 CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
1543 second bus.
1545 - drivers/i2c/tegra_i2c.c:
1546 - activate this driver with CONFIG_SYS_I2C_TEGRA
1547 - This driver adds 4 i2c buses with a fix speed from
1548 100000 and the slave addr 0!
1550 - drivers/i2c/ppc4xx_i2c.c
1551 - activate this driver with CONFIG_SYS_I2C_PPC4XX
1552 - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
1553 - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
1555 - drivers/i2c/i2c_mxc.c
1556 - activate this driver with CONFIG_SYS_I2C_MXC
1557 - enable bus 1 with CONFIG_SYS_I2C_MXC_I2C1
1558 - enable bus 2 with CONFIG_SYS_I2C_MXC_I2C2
1559 - enable bus 3 with CONFIG_SYS_I2C_MXC_I2C3
1560 - enable bus 4 with CONFIG_SYS_I2C_MXC_I2C4
1561 - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
1562 - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
1563 - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
1564 - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
1565 - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
1566 - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
1567 - define speed for bus 4 with CONFIG_SYS_MXC_I2C4_SPEED
1568 - define slave for bus 4 with CONFIG_SYS_MXC_I2C4_SLAVE
1569 If those defines are not set, default value is 100000
1570 for speed, and 0 for slave.
1572 - drivers/i2c/rcar_i2c.c:
1573 - activate this driver with CONFIG_SYS_I2C_RCAR
1574 - This driver adds 4 i2c buses
1576 - drivers/i2c/sh_i2c.c:
1577 - activate this driver with CONFIG_SYS_I2C_SH
1578 - This driver adds from 2 to 5 i2c buses
1580 - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
1581 - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
1582 - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
1583 - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
1584 - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
1585 - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
1586 - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
1587 - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
1588 - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
1589 - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
1590 - CONFIG_SYS_I2C_SH_NUM_CONTROLLERS for number of i2c buses
1592 - drivers/i2c/omap24xx_i2c.c
1593 - activate this driver with CONFIG_SYS_I2C_OMAP24XX
1594 - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
1595 - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
1596 - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
1597 - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
1598 - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
1599 - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
1600 - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
1601 - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
1602 - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
1603 - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
1605 - drivers/i2c/s3c24x0_i2c.c:
1606 - activate this driver with CONFIG_SYS_I2C_S3C24X0
1607 - This driver adds i2c buses (11 for Exynos5250, Exynos5420
1608 9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
1609 with a fix speed from 100000 and the slave addr 0!
1611 - drivers/i2c/ihs_i2c.c
1612 - activate this driver with CONFIG_SYS_I2C_IHS
1613 - CONFIG_SYS_I2C_IHS_CH0 activate hardware channel 0
1614 - CONFIG_SYS_I2C_IHS_SPEED_0 speed channel 0
1615 - CONFIG_SYS_I2C_IHS_SLAVE_0 slave addr channel 0
1616 - CONFIG_SYS_I2C_IHS_CH1 activate hardware channel 1
1617 - CONFIG_SYS_I2C_IHS_SPEED_1 speed channel 1
1618 - CONFIG_SYS_I2C_IHS_SLAVE_1 slave addr channel 1
1619 - CONFIG_SYS_I2C_IHS_CH2 activate hardware channel 2
1620 - CONFIG_SYS_I2C_IHS_SPEED_2 speed channel 2
1621 - CONFIG_SYS_I2C_IHS_SLAVE_2 slave addr channel 2
1622 - CONFIG_SYS_I2C_IHS_CH3 activate hardware channel 3
1623 - CONFIG_SYS_I2C_IHS_SPEED_3 speed channel 3
1624 - CONFIG_SYS_I2C_IHS_SLAVE_3 slave addr channel 3
1625 - activate dual channel with CONFIG_SYS_I2C_IHS_DUAL
1626 - CONFIG_SYS_I2C_IHS_SPEED_0_1 speed channel 0_1
1627 - CONFIG_SYS_I2C_IHS_SLAVE_0_1 slave addr channel 0_1
1628 - CONFIG_SYS_I2C_IHS_SPEED_1_1 speed channel 1_1
1629 - CONFIG_SYS_I2C_IHS_SLAVE_1_1 slave addr channel 1_1
1630 - CONFIG_SYS_I2C_IHS_SPEED_2_1 speed channel 2_1
1631 - CONFIG_SYS_I2C_IHS_SLAVE_2_1 slave addr channel 2_1
1632 - CONFIG_SYS_I2C_IHS_SPEED_3_1 speed channel 3_1
1633 - CONFIG_SYS_I2C_IHS_SLAVE_3_1 slave addr channel 3_1
1635 additional defines:
1637 CONFIG_SYS_NUM_I2C_BUSES
1638 Hold the number of i2c buses you want to use.
1640 CONFIG_SYS_I2C_DIRECT_BUS
1641 define this, if you don't use i2c muxes on your hardware.
1642 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1643 omit this define.
1645 CONFIG_SYS_I2C_MAX_HOPS
1646 define how many muxes are maximal consecutively connected
1647 on one i2c bus. If you not use i2c muxes, omit this
1648 define.
1650 CONFIG_SYS_I2C_BUSES
1651 hold a list of buses you want to use, only used if
1652 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1653 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1654 CONFIG_SYS_NUM_I2C_BUSES = 9:
1656 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1657 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1658 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1659 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1660 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1661 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1662 {1, {I2C_NULL_HOP}}, \
1663 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1664 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1665 }
1667 which defines
1668 bus 0 on adapter 0 without a mux
1669 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1670 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1671 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1672 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1673 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1674 bus 6 on adapter 1 without a mux
1675 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1676 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1678 If you do not have i2c muxes on your board, omit this define.
1680 - Legacy I2C Support:
1681 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1682 then the following macros need to be defined (examples are
1683 from include/configs/lwmon.h):
1685 I2C_INIT
1687 (Optional). Any commands necessary to enable the I2C
1688 controller or configure ports.
1690 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1692 I2C_ACTIVE
1694 The code necessary to make the I2C data line active
1695 (driven). If the data line is open collector, this
1696 define can be null.
1698 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1700 I2C_TRISTATE
1702 The code necessary to make the I2C data line tri-stated
1703 (inactive). If the data line is open collector, this
1704 define can be null.
1706 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1708 I2C_READ
1710 Code that returns true if the I2C data line is high,
1711 false if it is low.
1713 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1715 I2C_SDA(bit)
1717 If <bit> is true, sets the I2C data line high. If it
1718 is false, it clears it (low).
1720 eg: #define I2C_SDA(bit) \
1721 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1722 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1724 I2C_SCL(bit)
1726 If <bit> is true, sets the I2C clock line high. If it
1727 is false, it clears it (low).
1729 eg: #define I2C_SCL(bit) \
1730 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1731 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1733 I2C_DELAY
1735 This delay is invoked four times per clock cycle so this
1736 controls the rate of data transfer. The data rate thus
1737 is 1 / (I2C_DELAY * 4). Often defined to be something
1738 like:
1740 #define I2C_DELAY udelay(2)
1742 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1744 If your arch supports the generic GPIO framework (asm/gpio.h),
1745 then you may alternatively define the two GPIOs that are to be
1746 used as SCL / SDA. Any of the previous I2C_xxx macros will
1747 have GPIO-based defaults assigned to them as appropriate.
1749 You should define these to the GPIO value as given directly to
1750 the generic GPIO functions.
1752 CONFIG_SYS_I2C_INIT_BOARD
1754 When a board is reset during an i2c bus transfer
1755 chips might think that the current transfer is still
1756 in progress. On some boards it is possible to access
1757 the i2c SCLK line directly, either by using the
1758 processor pin as a GPIO or by having a second pin
1759 connected to the bus. If this option is defined a
1760 custom i2c_init_board() routine in boards/xxx/board.c
1761 is run early in the boot sequence.
1763 CONFIG_I2C_MULTI_BUS
1765 This option allows the use of multiple I2C buses, each of which
1766 must have a controller. At any point in time, only one bus is
1767 active. To switch to a different bus, use the 'i2c dev' command.
1768 Note that bus numbering is zero-based.
1770 CONFIG_SYS_I2C_NOPROBES
1772 This option specifies a list of I2C devices that will be skipped
1773 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1774 is set, specify a list of bus-device pairs. Otherwise, specify
1775 a 1D array of device addresses
1777 e.g.
1778 #undef CONFIG_I2C_MULTI_BUS
1779 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1781 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1783 #define CONFIG_I2C_MULTI_BUS
1784 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1786 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1788 CONFIG_SYS_SPD_BUS_NUM
1790 If defined, then this indicates the I2C bus number for DDR SPD.
1791 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1793 CONFIG_SYS_RTC_BUS_NUM
1795 If defined, then this indicates the I2C bus number for the RTC.
1796 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1798 CONFIG_SOFT_I2C_READ_REPEATED_START
1800 defining this will force the i2c_read() function in
1801 the soft_i2c driver to perform an I2C repeated start
1802 between writing the address pointer and reading the
1803 data. If this define is omitted the default behaviour
1804 of doing a stop-start sequence will be used. Most I2C
1805 devices can use either method, but some require one or
1806 the other.
1808 - SPI Support: CONFIG_SPI
1810 Enables SPI driver (so far only tested with
1811 SPI EEPROM, also an instance works with Crystal A/D and
1812 D/As on the SACSng board)
1814 CONFIG_SOFT_SPI
1816 Enables a software (bit-bang) SPI driver rather than
1817 using hardware support. This is a general purpose
1818 driver that only requires three general I/O port pins
1819 (two outputs, one input) to function. If this is
1820 defined, the board configuration must define several
1821 SPI configuration items (port pins to use, etc). For
1822 an example, see include/configs/sacsng.h.
1824 CONFIG_SYS_SPI_MXC_WAIT
1825 Timeout for waiting until spi transfer completed.
1826 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1828 - FPGA Support: CONFIG_FPGA
1830 Enables FPGA subsystem.
1832 CONFIG_FPGA_<vendor>
1834 Enables support for specific chip vendors.
1835 (ALTERA, XILINX)
1837 CONFIG_FPGA_<family>
1839 Enables support for FPGA family.
1840 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1842 CONFIG_FPGA_COUNT
1844 Specify the number of FPGA devices to support.
1846 CONFIG_SYS_FPGA_PROG_FEEDBACK
1848 Enable printing of hash marks during FPGA configuration.
1850 CONFIG_SYS_FPGA_CHECK_BUSY
1852 Enable checks on FPGA configuration interface busy
1853 status by the configuration function. This option
1854 will require a board or device specific function to
1855 be written.
1857 CONFIG_FPGA_DELAY
1859 If defined, a function that provides delays in the FPGA
1860 configuration driver.
1862 CONFIG_SYS_FPGA_CHECK_CTRLC
1863 Allow Control-C to interrupt FPGA configuration
1865 CONFIG_SYS_FPGA_CHECK_ERROR
1867 Check for configuration errors during FPGA bitfile
1868 loading. For example, abort during Virtex II
1869 configuration if the INIT_B line goes low (which
1870 indicated a CRC error).
1872 CONFIG_SYS_FPGA_WAIT_INIT
1874 Maximum time to wait for the INIT_B line to de-assert
1875 after PROB_B has been de-asserted during a Virtex II
1876 FPGA configuration sequence. The default time is 500
1877 ms.
1879 CONFIG_SYS_FPGA_WAIT_BUSY
1881 Maximum time to wait for BUSY to de-assert during
1882 Virtex II FPGA configuration. The default is 5 ms.
1884 CONFIG_SYS_FPGA_WAIT_CONFIG
1886 Time to wait after FPGA configuration. The default is
1887 200 ms.
1889 - Configuration Management:
1891 CONFIG_IDENT_STRING
1893 If defined, this string will be added to the U-Boot
1894 version information (U_BOOT_VERSION)
1896 - Vendor Parameter Protection:
1898 U-Boot considers the values of the environment
1899 variables "serial#" (Board Serial Number) and
1900 "ethaddr" (Ethernet Address) to be parameters that
1901 are set once by the board vendor / manufacturer, and
1902 protects these variables from casual modification by
1903 the user. Once set, these variables are read-only,
1904 and write or delete attempts are rejected. You can
1905 change this behaviour:
1907 If CONFIG_ENV_OVERWRITE is #defined in your config
1908 file, the write protection for vendor parameters is
1909 completely disabled. Anybody can change or delete
1910 these parameters.
1912 Alternatively, if you define _both_ an ethaddr in the
1913 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1914 Ethernet address is installed in the environment,
1915 which can be changed exactly ONCE by the user. [The
1916 serial# is unaffected by this, i. e. it remains
1917 read-only.]
1919 The same can be accomplished in a more flexible way
1920 for any variable by configuring the type of access
1921 to allow for those variables in the ".flags" variable
1922 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1924 - Protected RAM:
1925 CONFIG_PRAM
1927 Define this variable to enable the reservation of
1928 "protected RAM", i. e. RAM which is not overwritten
1929 by U-Boot. Define CONFIG_PRAM to hold the number of
1930 kB you want to reserve for pRAM. You can overwrite
1931 this default value by defining an environment
1932 variable "pram" to the number of kB you want to
1933 reserve. Note that the board info structure will
1934 still show the full amount of RAM. If pRAM is
1935 reserved, a new environment variable "mem" will
1936 automatically be defined to hold the amount of
1937 remaining RAM in a form that can be passed as boot
1938 argument to Linux, for instance like that:
1940 setenv bootargs ... mem=\${mem}
1941 saveenv
1943 This way you can tell Linux not to use this memory,
1944 either, which results in a memory region that will
1945 not be affected by reboots.
1947 *WARNING* If your board configuration uses automatic
1948 detection of the RAM size, you must make sure that
1949 this memory test is non-destructive. So far, the
1950 following board configurations are known to be
1951 "pRAM-clean":
1953 IVMS8, IVML24, SPD8xx,
1954 HERMES, IP860, RPXlite, LWMON,
1955 FLAGADM
1957 - Access to physical memory region (> 4GB)
1958 Some basic support is provided for operations on memory not
1959 normally accessible to U-Boot - e.g. some architectures
1960 support access to more than 4GB of memory on 32-bit
1961 machines using physical address extension or similar.
1962 Define CONFIG_PHYSMEM to access this basic support, which
1963 currently only supports clearing the memory.
1965 - Error Recovery:
1966 CONFIG_NET_RETRY_COUNT
1968 This variable defines the number of retries for
1969 network operations like ARP, RARP, TFTP, or BOOTP
1970 before giving up the operation. If not defined, a
1971 default value of 5 is used.
1973 CONFIG_ARP_TIMEOUT
1975 Timeout waiting for an ARP reply in milliseconds.
1977 CONFIG_NFS_TIMEOUT
1979 Timeout in milliseconds used in NFS protocol.
1980 If you encounter "ERROR: Cannot umount" in nfs command,
1981 try longer timeout such as
1982 #define CONFIG_NFS_TIMEOUT 10000UL
1984 - Command Interpreter:
1985 CONFIG_SYS_PROMPT_HUSH_PS2
1987 This defines the secondary prompt string, which is
1988 printed when the command interpreter needs more input
1989 to complete a command. Usually "> ".
1991 Note:
1993 In the current implementation, the local variables
1994 space and global environment variables space are
1995 separated. Local variables are those you define by
1996 simply typing `name=value'. To access a local
1997 variable later on, you have write `$name' or
1998 `${name}'; to execute the contents of a variable
1999 directly type `$name' at the command prompt.
2001 Global environment variables are those you use
2002 setenv/printenv to work with. To run a command stored
2003 in such a variable, you need to use the run command,
2004 and you must not use the '$' sign to access them.
2006 To store commands and special characters in a
2007 variable, please use double quotation marks
2008 surrounding the whole text of the variable, instead
2009 of the backslashes before semicolons and special
2010 symbols.
2012 - Command Line Editing and History:
2013 CONFIG_CMDLINE_PS_SUPPORT
2015 Enable support for changing the command prompt string
2016 at run-time. Only static string is supported so far.
2017 The string is obtained from environment variables PS1
2018 and PS2.
2020 - Default Environment:
2021 CONFIG_EXTRA_ENV_SETTINGS
2023 Define this to contain any number of null terminated
2024 strings (variable = value pairs) that will be part of
2025 the default environment compiled into the boot image.
2027 For example, place something like this in your
2028 board's config file:
2030 #define CONFIG_EXTRA_ENV_SETTINGS \
2031 "myvar1=value1\0" \
2032 "myvar2=value2\0"
2034 Warning: This method is based on knowledge about the
2035 internal format how the environment is stored by the
2036 U-Boot code. This is NOT an official, exported
2037 interface! Although it is unlikely that this format
2038 will change soon, there is no guarantee either.
2039 You better know what you are doing here.
2041 Note: overly (ab)use of the default environment is
2042 discouraged. Make sure to check other ways to preset
2043 the environment like the "source" command or the
2044 boot command first.
2046 CONFIG_DELAY_ENVIRONMENT
2048 Normally the environment is loaded when the board is
2049 initialised so that it is available to U-Boot. This inhibits
2050 that so that the environment is not available until
2051 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2052 this is instead controlled by the value of
2053 /config/load-environment.
2055 - TFTP Fixed UDP Port:
2056 CONFIG_TFTP_PORT
2058 If this is defined, the environment variable tftpsrcp
2059 is used to supply the TFTP UDP source port value.
2060 If tftpsrcp isn't defined, the normal pseudo-random port
2061 number generator is used.
2063 Also, the environment variable tftpdstp is used to supply
2064 the TFTP UDP destination port value. If tftpdstp isn't
2065 defined, the normal port 69 is used.
2067 The purpose for tftpsrcp is to allow a TFTP server to
2068 blindly start the TFTP transfer using the pre-configured
2069 target IP address and UDP port. This has the effect of
2070 "punching through" the (Windows XP) firewall, allowing
2071 the remainder of the TFTP transfer to proceed normally.
2072 A better solution is to properly configure the firewall,
2073 but sometimes that is not allowed.
2075 CONFIG_STANDALONE_LOAD_ADDR
2077 This option defines a board specific value for the
2078 address where standalone program gets loaded, thus
2079 overwriting the architecture dependent default
2080 settings.
2082 - Frame Buffer Address:
2083 CONFIG_FB_ADDR
2085 Define CONFIG_FB_ADDR if you want to use specific
2086 address for frame buffer. This is typically the case
2087 when using a graphics controller has separate video
2088 memory. U-Boot will then place the frame buffer at
2089 the given address instead of dynamically reserving it
2090 in system RAM by calling lcd_setmem(), which grabs
2091 the memory for the frame buffer depending on the
2092 configured panel size.
2094 Please see board_init_f function.
2096 - Automatic software updates via TFTP server
2097 CONFIG_UPDATE_TFTP
2098 CONFIG_UPDATE_TFTP_CNT_MAX
2099 CONFIG_UPDATE_TFTP_MSEC_MAX
2101 These options enable and control the auto-update feature;
2102 for a more detailed description refer to doc/README.update.
2104 - MTD Support (mtdparts command, UBI support)
2105 CONFIG_MTD_UBI_WL_THRESHOLD
2106 This parameter defines the maximum difference between the highest
2107 erase counter value and the lowest erase counter value of eraseblocks
2108 of UBI devices. When this threshold is exceeded, UBI starts performing
2109 wear leveling by means of moving data from eraseblock with low erase
2110 counter to eraseblocks with high erase counter.
2112 The default value should be OK for SLC NAND flashes, NOR flashes and
2113 other flashes which have eraseblock life-cycle 100000 or more.
2114 However, in case of MLC NAND flashes which typically have eraseblock
2115 life-cycle less than 10000, the threshold should be lessened (e.g.,
2116 to 128 or 256, although it does not have to be power of 2).
2118 default: 4096
2120 CONFIG_MTD_UBI_BEB_LIMIT
2121 This option specifies the maximum bad physical eraseblocks UBI
2122 expects on the MTD device (per 1024 eraseblocks). If the
2123 underlying flash does not admit of bad eraseblocks (e.g. NOR
2124 flash), this value is ignored.
2126 NAND datasheets often specify the minimum and maximum NVM
2127 (Number of Valid Blocks) for the flashes' endurance lifetime.
2128 The maximum expected bad eraseblocks per 1024 eraseblocks
2129 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
2130 which gives 20 for most NANDs (MaxNVB is basically the total
2131 count of eraseblocks on the chip).
2133 To put it differently, if this value is 20, UBI will try to
2134 reserve about 1.9% of physical eraseblocks for bad blocks
2135 handling. And that will be 1.9% of eraseblocks on the entire
2136 NAND chip, not just the MTD partition UBI attaches. This means
2137 that if you have, say, a NAND flash chip admits maximum 40 bad
2138 eraseblocks, and it is split on two MTD partitions of the same
2139 size, UBI will reserve 40 eraseblocks when attaching a
2140 partition.
2142 default: 20
2144 CONFIG_MTD_UBI_FASTMAP
2145 Fastmap is a mechanism which allows attaching an UBI device
2146 in nearly constant time. Instead of scanning the whole MTD device it
2147 only has to locate a checkpoint (called fastmap) on the device.
2148 The on-flash fastmap contains all information needed to attach
2149 the device. Using fastmap makes only sense on large devices where
2150 attaching by scanning takes long. UBI will not automatically install
2151 a fastmap on old images, but you can set the UBI parameter
2152 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
2153 that fastmap-enabled images are still usable with UBI implementations
2154 without fastmap support. On typical flash devices the whole fastmap
2155 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
2157 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
2158 Set this parameter to enable fastmap automatically on images
2159 without a fastmap.
2160 default: 0
2162 CONFIG_MTD_UBI_FM_DEBUG
2163 Enable UBI fastmap debug
2164 default: 0
2166 - SPL framework
2167 CONFIG_SPL
2168 Enable building of SPL globally.
2170 CONFIG_SPL_LDSCRIPT
2171 LDSCRIPT for linking the SPL binary.
2173 CONFIG_SPL_MAX_FOOTPRINT
2174 Maximum size in memory allocated to the SPL, BSS included.
2175 When defined, the linker checks that the actual memory
2176 used by SPL from _start to __bss_end does not exceed it.
2177 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
2178 must not be both defined at the same time.
2180 CONFIG_SPL_MAX_SIZE
2181 Maximum size of the SPL image (text, data, rodata, and
2182 linker lists sections), BSS excluded.
2183 When defined, the linker checks that the actual size does
2184 not exceed it.
2186 CONFIG_SPL_RELOC_TEXT_BASE
2187 Address to relocate to. If unspecified, this is equal to
2188 CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
2190 CONFIG_SPL_BSS_START_ADDR
2191 Link address for the BSS within the SPL binary.
2193 CONFIG_SPL_BSS_MAX_SIZE
2194 Maximum size in memory allocated to the SPL BSS.
2195 When defined, the linker checks that the actual memory used
2196 by SPL from __bss_start to __bss_end does not exceed it.
2197 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
2198 must not be both defined at the same time.
2200 CONFIG_SPL_STACK
2201 Adress of the start of the stack SPL will use
2203 CONFIG_SPL_PANIC_ON_RAW_IMAGE
2204 When defined, SPL will panic() if the image it has
2205 loaded does not have a signature.
2206 Defining this is useful when code which loads images
2207 in SPL cannot guarantee that absolutely all read errors
2208 will be caught.
2209 An example is the LPC32XX MLC NAND driver, which will
2210 consider that a completely unreadable NAND block is bad,
2211 and thus should be skipped silently.
2213 CONFIG_SPL_RELOC_STACK
2214 Adress of the start of the stack SPL will use after
2215 relocation. If unspecified, this is equal to
2216 CONFIG_SPL_STACK.
2218 CONFIG_SYS_SPL_MALLOC_START
2219 Starting address of the malloc pool used in SPL.
2220 When this option is set the full malloc is used in SPL and
2221 it is set up by spl_init() and before that, the simple malloc()
2222 can be used if CONFIG_SYS_MALLOC_F is defined.
2224 CONFIG_SYS_SPL_MALLOC_SIZE
2225 The size of the malloc pool used in SPL.
2227 CONFIG_SPL_OS_BOOT
2228 Enable booting directly to an OS from SPL.
2229 See also: doc/README.falcon
2231 CONFIG_SPL_DISPLAY_PRINT
2232 For ARM, enable an optional function to print more information
2233 about the running system.
2235 CONFIG_SPL_INIT_MINIMAL
2236 Arch init code should be built for a very small image
2238 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
2239 Partition on the MMC to load U-Boot from when the MMC is being
2240 used in raw mode
2242 CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
2243 Sector to load kernel uImage from when MMC is being
2244 used in raw mode (for Falcon mode)
2246 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
2247 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
2248 Sector and number of sectors to load kernel argument
2249 parameters from when MMC is being used in raw mode
2250 (for falcon mode)
2252 CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
2253 Filename to read to load U-Boot when reading from filesystem
2255 CONFIG_SPL_FS_LOAD_KERNEL_NAME
2256 Filename to read to load kernel uImage when reading
2257 from filesystem (for Falcon mode)
2259 CONFIG_SPL_FS_LOAD_ARGS_NAME
2260 Filename to read to load kernel argument parameters
2261 when reading from filesystem (for Falcon mode)
2263 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
2264 Set this for NAND SPL on PPC mpc83xx targets, so that
2265 start.S waits for the rest of the SPL to load before
2266 continuing (the hardware starts execution after just
2267 loading the first page rather than the full 4K).
2269 CONFIG_SPL_SKIP_RELOCATE
2270 Avoid SPL relocation
2272 CONFIG_SPL_NAND_IDENT
2273 SPL uses the chip ID list to identify the NAND flash.
2274 Requires CONFIG_SPL_NAND_BASE.
2276 CONFIG_SPL_UBI
2277 Support for a lightweight UBI (fastmap) scanner and
2278 loader
2280 CONFIG_SPL_NAND_RAW_ONLY
2281 Support to boot only raw u-boot.bin images. Use this only
2282 if you need to save space.
2284 CONFIG_SPL_COMMON_INIT_DDR
2285 Set for common ddr init with serial presence detect in
2286 SPL binary.
2288 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
2289 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
2290 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
2291 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
2292 CONFIG_SYS_NAND_ECCBYTES
2293 Defines the size and behavior of the NAND that SPL uses
2294 to read U-Boot
2296 CONFIG_SYS_NAND_U_BOOT_OFFS
2297 Location in NAND to read U-Boot from
2299 CONFIG_SYS_NAND_U_BOOT_DST
2300 Location in memory to load U-Boot to
2302 CONFIG_SYS_NAND_U_BOOT_SIZE
2303 Size of image to load
2305 CONFIG_SYS_NAND_U_BOOT_START
2306 Entry point in loaded image to jump to
2308 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
2309 Define this if you need to first read the OOB and then the
2310 data. This is used, for example, on davinci platforms.
2312 CONFIG_SPL_RAM_DEVICE
2313 Support for running image already present in ram, in SPL binary
2315 CONFIG_SPL_PAD_TO
2316 Image offset to which the SPL should be padded before appending
2317 the SPL payload. By default, this is defined as
2318 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2319 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2320 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2322 CONFIG_SPL_TARGET
2323 Final target image containing SPL and payload. Some SPLs
2324 use an arch-specific makefile fragment instead, for
2325 example if more than one image needs to be produced.
2327 CONFIG_SPL_FIT_PRINT
2328 Printing information about a FIT image adds quite a bit of
2329 code to SPL. So this is normally disabled in SPL. Use this
2330 option to re-enable it. This will affect the output of the
2331 bootm command when booting a FIT image.
2333 - TPL framework
2334 CONFIG_TPL
2335 Enable building of TPL globally.
2337 CONFIG_TPL_PAD_TO
2338 Image offset to which the TPL should be padded before appending
2339 the TPL payload. By default, this is defined as
2340 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2341 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2342 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2344 - Interrupt support (PPC):
2346 There are common interrupt_init() and timer_interrupt()
2347 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
2348 for CPU specific initialization. interrupt_init_cpu()
2349 should set decrementer_count to appropriate value. If
2350 CPU resets decrementer automatically after interrupt
2351 (ppc4xx) it should set decrementer_count to zero.
2352 timer_interrupt() calls timer_interrupt_cpu() for CPU
2353 specific handling. If board has watchdog / status_led
2354 / other_activity_monitor it works automatically from
2355 general timer_interrupt().
2358 Board initialization settings:
2359 ------------------------------
2361 During Initialization u-boot calls a number of board specific functions
2362 to allow the preparation of board specific prerequisites, e.g. pin setup
2363 before drivers are initialized. To enable these callbacks the
2364 following configuration macros have to be defined. Currently this is
2365 architecture specific, so please check arch/your_architecture/lib/board.c
2366 typically in board_init_f() and board_init_r().
2368 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
2369 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
2370 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
2371 - CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
2373 Configuration Settings:
2374 -----------------------
2376 - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
2377 Optionally it can be defined to support 64-bit memory commands.
2379 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2380 undefine this when you're short of memory.
2382 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
2383 width of the commands listed in the 'help' command output.
2385 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
2386 prompt for user input.
2388 - CONFIG_SYS_CBSIZE: Buffer size for input from the Console
2390 - CONFIG_SYS_PBSIZE: Buffer size for Console output
2392 - CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands
2394 - CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2395 the application (usually a Linux kernel) when it is
2396 booted
2398 - CONFIG_SYS_BAUDRATE_TABLE:
2399 List of legal baudrate settings for this board.
2401 - CONFIG_SYS_MEM_RESERVE_SECURE
2402 Only implemented for ARMv8 for now.
2403 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
2404 is substracted from total RAM and won't be reported to OS.
2405 This memory can be used as secure memory. A variable
2406 gd->arch.secure_ram is used to track the location. In systems
2407 the RAM base is not zero, or RAM is divided into banks,
2408 this variable needs to be recalcuated to get the address.
2410 - CONFIG_SYS_MEM_TOP_HIDE:
2411 If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2412 this specified memory area will get subtracted from the top
2413 (end) of RAM and won't get "touched" at all by U-Boot. By
2414 fixing up gd->ram_size the Linux kernel should gets passed
2415 the now "corrected" memory size and won't touch it either.
2416 This should work for arch/ppc and arch/powerpc. Only Linux
2417 board ports in arch/powerpc with bootwrapper support that
2418 recalculate the memory size from the SDRAM controller setup
2419 will have to get fixed in Linux additionally.
2421 This option can be used as a workaround for the 440EPx/GRx
2422 CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2423 be touched.
2425 WARNING: Please make sure that this value is a multiple of
2426 the Linux page size (normally 4k). If this is not the case,
2427 then the end address of the Linux memory will be located at a
2428 non page size aligned address and this could cause major
2429 problems.
2431 - CONFIG_SYS_LOADS_BAUD_CHANGE:
2432 Enable temporary baudrate change while serial download
2434 - CONFIG_SYS_SDRAM_BASE:
2435 Physical start address of SDRAM. _Must_ be 0 here.
2437 - CONFIG_SYS_FLASH_BASE:
2438 Physical start address of Flash memory.
2440 - CONFIG_SYS_MONITOR_BASE:
2441 Physical start address of boot monitor code (set by
2442 make config files to be same as the text base address
2443 (CONFIG_SYS_TEXT_BASE) used when linking) - same as
2444 CONFIG_SYS_FLASH_BASE when booting from flash.
2446 - CONFIG_SYS_MONITOR_LEN:
2447 Size of memory reserved for monitor code, used to
2448 determine _at_compile_time_ (!) if the environment is
2449 embedded within the U-Boot image, or in a separate
2450 flash sector.
2452 - CONFIG_SYS_MALLOC_LEN:
2453 Size of DRAM reserved for malloc() use.
2455 - CONFIG_SYS_MALLOC_F_LEN
2456 Size of the malloc() pool for use before relocation. If
2457 this is defined, then a very simple malloc() implementation
2458 will become available before relocation. The address is just
2459 below the global data, and the stack is moved down to make
2460 space.
2462 This feature allocates regions with increasing addresses
2463 within the region. calloc() is supported, but realloc()
2464 is not available. free() is supported but does nothing.
2465 The memory will be freed (or in fact just forgotten) when
2466 U-Boot relocates itself.
2468 - CONFIG_SYS_MALLOC_SIMPLE
2469 Provides a simple and small malloc() and calloc() for those
2470 boards which do not use the full malloc in SPL (which is
2471 enabled with CONFIG_SYS_SPL_MALLOC_START).
2473 - CONFIG_SYS_NONCACHED_MEMORY:
2474 Size of non-cached memory area. This area of memory will be
2475 typically located right below the malloc() area and mapped
2476 uncached in the MMU. This is useful for drivers that would
2477 otherwise require a lot of explicit cache maintenance. For
2478 some drivers it's also impossible to properly maintain the
2479 cache. For example if the regions that need to be flushed
2480 are not a multiple of the cache-line size, *and* padding
2481 cannot be allocated between the regions to align them (i.e.
2482 if the HW requires a contiguous array of regions, and the
2483 size of each region is not cache-aligned), then a flush of
2484 one region may result in overwriting data that hardware has
2485 written to another region in the same cache-line. This can
2486 happen for example in network drivers where descriptors for
2487 buffers are typically smaller than the CPU cache-line (e.g.
2488 16 bytes vs. 32 or 64 bytes).
2490 Non-cached memory is only supported on 32-bit ARM at present.
2492 - CONFIG_SYS_BOOTM_LEN:
2493 Normally compressed uImages are limited to an
2494 uncompressed size of 8 MBytes. If this is not enough,
2495 you can define CONFIG_SYS_BOOTM_LEN in your board config file
2496 to adjust this setting to your needs.
2498 - CONFIG_SYS_BOOTMAPSZ:
2499 Maximum size of memory mapped by the startup code of
2500 the Linux kernel; all data that must be processed by
2501 the Linux kernel (bd_info, boot arguments, FDT blob if
2502 used) must be put below this limit, unless "bootm_low"
2503 environment variable is defined and non-zero. In such case
2504 all data for the Linux kernel must be between "bootm_low"
2505 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
2506 variable "bootm_mapsize" will override the value of
2507 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
2508 then the value in "bootm_size" will be used instead.
2510 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
2511 Enable initrd_high functionality. If defined then the
2512 initrd_high feature is enabled and the bootm ramdisk subcommand
2513 is enabled.
2515 - CONFIG_SYS_BOOT_GET_CMDLINE:
2516 Enables allocating and saving kernel cmdline in space between
2517 "bootm_low" and "bootm_low" + BOOTMAPSZ.
2519 - CONFIG_SYS_BOOT_GET_KBD:
2520 Enables allocating and saving a kernel copy of the bd_info in
2521 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2523 - CONFIG_SYS_MAX_FLASH_BANKS:
2524 Max number of Flash memory banks
2526 - CONFIG_SYS_MAX_FLASH_SECT:
2527 Max number of sectors on a Flash chip
2529 - CONFIG_SYS_FLASH_ERASE_TOUT:
2530 Timeout for Flash erase operations (in ms)
2532 - CONFIG_SYS_FLASH_WRITE_TOUT:
2533 Timeout for Flash write operations (in ms)
2535 - CONFIG_SYS_FLASH_LOCK_TOUT
2536 Timeout for Flash set sector lock bit operation (in ms)
2538 - CONFIG_SYS_FLASH_UNLOCK_TOUT
2539 Timeout for Flash clear lock bits operation (in ms)
2541 - CONFIG_SYS_FLASH_PROTECTION
2542 If defined, hardware flash sectors protection is used
2543 instead of U-Boot software protection.
2545 - CONFIG_SYS_DIRECT_FLASH_TFTP:
2547 Enable TFTP transfers directly to flash memory;
2548 without this option such a download has to be
2549 performed in two steps: (1) download to RAM, and (2)
2550 copy from RAM to flash.
2552 The two-step approach is usually more reliable, since
2553 you can check if the download worked before you erase
2554 the flash, but in some situations (when system RAM is
2555 too limited to allow for a temporary copy of the
2556 downloaded image) this option may be very useful.
2558 - CONFIG_SYS_FLASH_CFI:
2559 Define if the flash driver uses extra elements in the
2560 common flash structure for storing flash geometry.
2562 - CONFIG_FLASH_CFI_DRIVER
2563 This option also enables the building of the cfi_flash driver
2564 in the drivers directory
2566 - CONFIG_FLASH_CFI_MTD
2567 This option enables the building of the cfi_mtd driver
2568 in the drivers directory. The driver exports CFI flash
2569 to the MTD layer.
2571 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2572 Use buffered writes to flash.
2574 - CONFIG_FLASH_SPANSION_S29WS_N
2575 s29ws-n MirrorBit flash has non-standard addresses for buffered
2576 write commands.
2578 - CONFIG_SYS_FLASH_QUIET_TEST
2579 If this option is defined, the common CFI flash doesn't
2580 print it's warning upon not recognized FLASH banks. This
2581 is useful, if some of the configured banks are only
2582 optionally available.
2584 - CONFIG_FLASH_SHOW_PROGRESS
2585 If defined (must be an integer), print out countdown
2586 digits and dots. Recommended value: 45 (9..1) for 80
2587 column displays, 15 (3..1) for 40 column displays.
2589 - CONFIG_FLASH_VERIFY
2590 If defined, the content of the flash (destination) is compared
2591 against the source after the write operation. An error message
2592 will be printed when the contents are not identical.
2593 Please note that this option is useless in nearly all cases,
2594 since such flash programming errors usually are detected earlier
2595 while unprotecting/erasing/programming. Please only enable
2596 this option if you really know what you are doing.
2598 - CONFIG_SYS_RX_ETH_BUFFER:
2599 Defines the number of Ethernet receive buffers. On some
2600 Ethernet controllers it is recommended to set this value
2601 to 8 or even higher (EEPRO100 or 405 EMAC), since all
2602 buffers can be full shortly after enabling the interface
2603 on high Ethernet traffic.
2604 Defaults to 4 if not defined.
2606 - CONFIG_ENV_MAX_ENTRIES
2608 Maximum number of entries in the hash table that is used
2609 internally to store the environment settings. The default
2610 setting is supposed to be generous and should work in most
2611 cases. This setting can be used to tune behaviour; see
2612 lib/hashtable.c for details.
2614 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2615 - CONFIG_ENV_FLAGS_LIST_STATIC
2616 Enable validation of the values given to environment variables when
2617 calling env set. Variables can be restricted to only decimal,
2618 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
2619 the variables can also be restricted to IP address or MAC address.
2621 The format of the list is:
2622 type_attribute = [s|d|x|b|i|m]
2623 access_attribute = [a|r|o|c]
2624 attributes = type_attribute[access_attribute]
2625 entry = variable_name[:attributes]
2626 list = entry[,list]
2628 The type attributes are:
2629 s - String (default)
2630 d - Decimal
2631 x - Hexadecimal
2632 b - Boolean ([1yYtT|0nNfF])
2633 i - IP address
2634 m - MAC address
2636 The access attributes are:
2637 a - Any (default)
2638 r - Read-only
2639 o - Write-once
2640 c - Change-default
2642 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2643 Define this to a list (string) to define the ".flags"
2644 environment variable in the default or embedded environment.
2646 - CONFIG_ENV_FLAGS_LIST_STATIC
2647 Define this to a list (string) to define validation that
2648 should be done if an entry is not found in the ".flags"
2649 environment variable. To override a setting in the static
2650 list, simply add an entry for the same variable name to the
2651 ".flags" variable.
2653 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
2654 regular expression. This allows multiple variables to define the same
2655 flags without explicitly listing them for each variable.
2657 The following definitions that deal with the placement and management
2658 of environment data (variable area); in general, we support the
2659 following configurations:
2661 - CONFIG_BUILD_ENVCRC:
2663 Builds up envcrc with the target environment so that external utils
2664 may easily extract it and embed it in final U-Boot images.
2666 BE CAREFUL! The first access to the environment happens quite early
2667 in U-Boot initialization (when we try to get the setting of for the
2668 console baudrate). You *MUST* have mapped your NVRAM area then, or
2669 U-Boot will hang.
2671 Please note that even with NVRAM we still use a copy of the
2672 environment in RAM: we could work on NVRAM directly, but we want to
2673 keep settings there always unmodified except somebody uses "saveenv"
2674 to save the current settings.
2676 BE CAREFUL! For some special cases, the local device can not use
2677 "saveenv" command. For example, the local device will get the
2678 environment stored in a remote NOR flash by SRIO or PCIE link,
2679 but it can not erase, write this NOR flash by SRIO or PCIE interface.
2681 - CONFIG_NAND_ENV_DST
2683 Defines address in RAM to which the nand_spl code should copy the
2684 environment. If redundant environment is used, it will be copied to
2685 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
2687 Please note that the environment is read-only until the monitor
2688 has been relocated to RAM and a RAM copy of the environment has been
2689 created; also, when using EEPROM you will have to use env_get_f()
2690 until then to read environment variables.
2692 The environment is protected by a CRC32 checksum. Before the monitor
2693 is relocated into RAM, as a result of a bad CRC you will be working
2694 with the compiled-in default environment - *silently*!!! [This is
2695 necessary, because the first environment variable we need is the
2696 "baudrate" setting for the console - if we have a bad CRC, we don't
2697 have any device yet where we could complain.]
2699 Note: once the monitor has been relocated, then it will complain if
2700 the default environment is used; a new CRC is computed as soon as you
2701 use the "saveenv" command to store a valid environment.
2703 - CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
2704 Echo the inverted Ethernet link state to the fault LED.
2706 Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
2707 also needs to be defined.
2709 - CONFIG_SYS_FAULT_MII_ADDR:
2710 MII address of the PHY to check for the Ethernet link state.
2712 - CONFIG_NS16550_MIN_FUNCTIONS:
2713 Define this if you desire to only have use of the NS16550_init
2714 and NS16550_putc functions for the serial driver located at
2715 drivers/serial/ns16550.c. This option is useful for saving
2716 space for already greatly restricted images, including but not
2717 limited to NAND_SPL configurations.
2719 - CONFIG_DISPLAY_BOARDINFO
2720 Display information about the board that U-Boot is running on
2721 when U-Boot starts up. The board function checkboard() is called
2722 to do this.
2724 - CONFIG_DISPLAY_BOARDINFO_LATE
2725 Similar to the previous option, but display this information
2726 later, once stdio is running and output goes to the LCD, if
2727 present.
2729 - CONFIG_BOARD_SIZE_LIMIT:
2730 Maximum size of the U-Boot image. When defined, the
2731 build system checks that the actual size does not
2732 exceed it.
2734 Low Level (hardware related) configuration options:
2735 ---------------------------------------------------
2737 - CONFIG_SYS_CACHELINE_SIZE:
2738 Cache Line Size of the CPU.
2740 - CONFIG_SYS_CCSRBAR_DEFAULT:
2741 Default (power-on reset) physical address of CCSR on Freescale
2742 PowerPC SOCs.
2744 - CONFIG_SYS_CCSRBAR:
2745 Virtual address of CCSR. On a 32-bit build, this is typically
2746 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
2748 - CONFIG_SYS_CCSRBAR_PHYS:
2749 Physical address of CCSR. CCSR can be relocated to a new
2750 physical address, if desired. In this case, this macro should
2751 be set to that address. Otherwise, it should be set to the
2752 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
2753 is typically relocated on 36-bit builds. It is recommended
2754 that this macro be defined via the _HIGH and _LOW macros:
2756 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
2757 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
2759 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
2760 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
2761 either 0 (32-bit build) or 0xF (36-bit build). This macro is
2762 used in assembly code, so it must not contain typecasts or
2763 integer size suffixes (e.g. "ULL").
2765 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
2766 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
2767 used in assembly code, so it must not contain typecasts or
2768 integer size suffixes (e.g. "ULL").
2770 - CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
2771 If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
2772 forced to a value that ensures that CCSR is not relocated.
2774 - CONFIG_IDE_AHB:
2775 Most IDE controllers were designed to be connected with PCI
2776 interface. Only few of them were designed for AHB interface.
2777 When software is doing ATA command and data transfer to
2778 IDE devices through IDE-AHB controller, some additional
2779 registers accessing to these kind of IDE-AHB controller
2780 is required.
2782 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
2783 DO NOT CHANGE unless you know exactly what you're
2784 doing! (11-4) [MPC8xx systems only]
2786 - CONFIG_SYS_INIT_RAM_ADDR:
2788 Start address of memory area that can be used for
2789 initial data and stack; please note that this must be
2790 writable memory that is working WITHOUT special
2791 initialization, i. e. you CANNOT use normal RAM which
2792 will become available only after programming the
2793 memory controller and running certain initialization
2794 sequences.
2796 U-Boot uses the following memory types:
2797 - MPC8xx: IMMR (internal memory of the CPU)
2799 - CONFIG_SYS_GBL_DATA_OFFSET:
2801 Offset of the initial data structure in the memory
2802 area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
2803 CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
2804 data is located at the end of the available space
2805 (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
2806 GENERATED_GBL_DATA_SIZE), and the initial stack is just
2807 below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
2808 CONFIG_SYS_GBL_DATA_OFFSET) downward.
2810 Note:
2811 On the MPC824X (or other systems that use the data
2812 cache for initial memory) the address chosen for
2813 CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
2814 point to an otherwise UNUSED address space between
2815 the top of RAM and the start of the PCI space.
2817 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
2819 - CONFIG_SYS_OR_TIMING_SDRAM:
2820 SDRAM timing
2822 - CONFIG_SYS_MAMR_PTA:
2823 periodic timer for refresh
2825 - FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
2826 CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
2827 CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
2828 CONFIG_SYS_BR1_PRELIM:
2829 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
2831 - SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
2832 CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
2833 CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
2834 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
2836 - CONFIG_PCI_ENUM_ONLY
2837 Only scan through and get the devices on the buses.
2838 Don't do any setup work, presumably because someone or
2839 something has already done it, and we don't need to do it
2840 a second time. Useful for platforms that are pre-booted
2841 by coreboot or similar.
2843 - CONFIG_PCI_INDIRECT_BRIDGE:
2844 Enable support for indirect PCI bridges.
2846 - CONFIG_SYS_SRIO:
2847 Chip has SRIO or not
2849 - CONFIG_SRIO1:
2850 Board has SRIO 1 port available
2852 - CONFIG_SRIO2:
2853 Board has SRIO 2 port available
2855 - CONFIG_SRIO_PCIE_BOOT_MASTER
2856 Board can support master function for Boot from SRIO and PCIE
2858 - CONFIG_SYS_SRIOn_MEM_VIRT:
2859 Virtual Address of SRIO port 'n' memory region
2861 - CONFIG_SYS_SRIOn_MEM_PHYxS:
2862 Physical Address of SRIO port 'n' memory region
2864 - CONFIG_SYS_SRIOn_MEM_SIZE:
2865 Size of SRIO port 'n' memory region
2867 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
2868 Defined to tell the NAND controller that the NAND chip is using
2869 a 16 bit bus.
2870 Not all NAND drivers use this symbol.
2871 Example of drivers that use it:
2872 - drivers/mtd/nand/raw/ndfc.c
2873 - drivers/mtd/nand/raw/mxc_nand.c
2875 - CONFIG_SYS_NDFC_EBC0_CFG
2876 Sets the EBC0_CFG register for the NDFC. If not defined
2877 a default value will be used.
2879 - CONFIG_SPD_EEPROM
2880 Get DDR timing information from an I2C EEPROM. Common
2881 with pluggable memory modules such as SODIMMs
2883 SPD_EEPROM_ADDRESS
2884 I2C address of the SPD EEPROM
2886 - CONFIG_SYS_SPD_BUS_NUM
2887 If SPD EEPROM is on an I2C bus other than the first
2888 one, specify here. Note that the value must resolve
2889 to something your driver can deal with.
2891 - CONFIG_SYS_DDR_RAW_TIMING
2892 Get DDR timing information from other than SPD. Common with
2893 soldered DDR chips onboard without SPD. DDR raw timing
2894 parameters are extracted from datasheet and hard-coded into
2895 header files or board specific files.
2897 - CONFIG_FSL_DDR_INTERACTIVE
2898 Enable interactive DDR debugging. See doc/README.fsl-ddr.
2900 - CONFIG_FSL_DDR_SYNC_REFRESH
2901 Enable sync of refresh for multiple controllers.
2903 - CONFIG_FSL_DDR_BIST
2904 Enable built-in memory test for Freescale DDR controllers.
2906 - CONFIG_SYS_83XX_DDR_USES_CS0
2907 Only for 83xx systems. If specified, then DDR should
2908 be configured using CS0 and CS1 instead of CS2 and CS3.
2910 - CONFIG_RMII
2911 Enable RMII mode for all FECs.
2912 Note that this is a global option, we can't
2913 have one FEC in standard MII mode and another in RMII mode.
2915 - CONFIG_CRC32_VERIFY
2916 Add a verify option to the crc32 command.
2917 The syntax is:
2919 => crc32 -v <address> <count> <crc32>
2921 Where address/count indicate a memory area
2922 and crc32 is the correct crc32 which the
2923 area should have.
2925 - CONFIG_LOOPW
2926 Add the "loopw" memory command. This only takes effect if
2927 the memory commands are activated globally (CONFIG_CMD_MEMORY).
2929 - CONFIG_CMD_MX_CYCLIC
2930 Add the "mdc" and "mwc" memory commands. These are cyclic
2931 "md/mw" commands.
2932 Examples:
2934 => mdc.b 10 4 500
2935 This command will print 4 bytes (10,11,12,13) each 500 ms.
2937 => mwc.l 100 12345678 10
2938 This command will write 12345678 to address 100 all 10 ms.
2940 This only takes effect if the memory commands are activated
2941 globally (CONFIG_CMD_MEMORY).
2943 - CONFIG_SKIP_LOWLEVEL_INIT
2944 [ARM, NDS32, MIPS, RISC-V only] If this variable is defined, then certain
2945 low level initializations (like setting up the memory
2946 controller) are omitted and/or U-Boot does not
2947 relocate itself into RAM.
2949 Normally this variable MUST NOT be defined. The only
2950 exception is when U-Boot is loaded (to RAM) by some
2951 other boot loader or by a debugger which performs
2952 these initializations itself.
2954 - CONFIG_SKIP_LOWLEVEL_INIT_ONLY
2955 [ARM926EJ-S only] This allows just the call to lowlevel_init()
2956 to be skipped. The normal CP15 init (such as enabling the
2957 instruction cache) is still performed.
2959 - CONFIG_SPL_BUILD
2960 Set when the currently-running compilation is for an artifact
2961 that will end up in the SPL (as opposed to the TPL or U-Boot
2962 proper). Code that needs stage-specific behavior should check
2963 this.
2965 - CONFIG_TPL_BUILD
2966 Set when the currently-running compilation is for an artifact
2967 that will end up in the TPL (as opposed to the SPL or U-Boot
2968 proper). Code that needs stage-specific behavior should check
2969 this.
2971 - CONFIG_SYS_MPC85XX_NO_RESETVEC
2972 Only for 85xx systems. If this variable is specified, the section
2973 .resetvec is not kept and the section .bootpg is placed in the
2974 previous 4k of the .text section.
2976 - CONFIG_ARCH_MAP_SYSMEM
2977 Generally U-Boot (and in particular the md command) uses
2978 effective address. It is therefore not necessary to regard
2979 U-Boot address as virtual addresses that need to be translated
2980 to physical addresses. However, sandbox requires this, since
2981 it maintains its own little RAM buffer which contains all
2982 addressable memory. This option causes some memory accesses
2983 to be mapped through map_sysmem() / unmap_sysmem().
2985 - CONFIG_X86_RESET_VECTOR
2986 If defined, the x86 reset vector code is included. This is not
2987 needed when U-Boot is running from Coreboot.
2989 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
2990 Option to disable subpage write in NAND driver
2991 driver that uses this:
2992 drivers/mtd/nand/raw/davinci_nand.c
2994 Freescale QE/FMAN Firmware Support:
2995 -----------------------------------
2997 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
2998 loading of "firmware", which is encoded in the QE firmware binary format.
2999 This firmware often needs to be loaded during U-Boot booting, so macros
3000 are used to identify the storage device (NOR flash, SPI, etc) and the address
3001 within that device.
3003 - CONFIG_SYS_FMAN_FW_ADDR
3004 The address in the storage device where the FMAN microcode is located. The
3005 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
3006 is also specified.
3008 - CONFIG_SYS_QE_FW_ADDR
3009 The address in the storage device where the QE microcode is located. The
3010 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
3011 is also specified.
3013 - CONFIG_SYS_QE_FMAN_FW_LENGTH
3014 The maximum possible size of the firmware. The firmware binary format
3015 has a field that specifies the actual size of the firmware, but it
3016 might not be possible to read any part of the firmware unless some
3017 local storage is allocated to hold the entire firmware first.
3019 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
3020 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
3021 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
3022 virtual address in NOR flash.
3024 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
3025 Specifies that QE/FMAN firmware is located in NAND flash.
3026 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
3028 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
3029 Specifies that QE/FMAN firmware is located on the primary SD/MMC
3030 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
3032 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
3033 Specifies that QE/FMAN firmware is located in the remote (master)
3034 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
3035 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
3036 window->master inbound window->master LAW->the ucode address in
3037 master's memory space.
3039 Freescale Layerscape Management Complex Firmware Support:
3040 ---------------------------------------------------------
3041 The Freescale Layerscape Management Complex (MC) supports the loading of
3042 "firmware".
3043 This firmware often needs to be loaded during U-Boot booting, so macros
3044 are used to identify the storage device (NOR flash, SPI, etc) and the address
3045 within that device.
3047 - CONFIG_FSL_MC_ENET
3048 Enable the MC driver for Layerscape SoCs.
3050 Freescale Layerscape Debug Server Support:
3051 -------------------------------------------
3052 The Freescale Layerscape Debug Server Support supports the loading of
3053 "Debug Server firmware" and triggering SP boot-rom.
3054 This firmware often needs to be loaded during U-Boot booting.
3056 - CONFIG_SYS_MC_RSV_MEM_ALIGN
3057 Define alignment of reserved memory MC requires
3059 Reproducible builds
3060 -------------------
3062 In order to achieve reproducible builds, timestamps used in the U-Boot build
3063 process have to be set to a fixed value.
3065 This is done using the SOURCE_DATE_EPOCH environment variable.
3066 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
3067 option for U-Boot or an environment variable in U-Boot.
3069 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
3071 Building the Software:
3072 ======================
3074 Building U-Boot has been tested in several native build environments
3075 and in many different cross environments. Of course we cannot support
3076 all possibly existing versions of cross development tools in all
3077 (potentially obsolete) versions. In case of tool chain problems we
3078 recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
3079 which is extensively used to build and test U-Boot.
3081 If you are not using a native environment, it is assumed that you
3082 have GNU cross compiling tools available in your path. In this case,
3083 you must set the environment variable CROSS_COMPILE in your shell.
3084 Note that no changes to the Makefile or any other source files are
3085 necessary. For example using the ELDK on a 4xx CPU, please enter:
3087 $ CROSS_COMPILE=ppc_4xx-
3088 $ export CROSS_COMPILE
3090 U-Boot is intended to be simple to build. After installing the
3091 sources you must configure U-Boot for one specific board type. This
3092 is done by typing:
3094 make NAME_defconfig
3096 where "NAME_defconfig" is the name of one of the existing configu-
3097 rations; see configs/*_defconfig for supported names.
3099 Note: for some boards special configuration names may exist; check if
3100 additional information is available from the board vendor; for
3101 instance, the TQM823L systems are available without (standard)
3102 or with LCD support. You can select such additional "features"
3103 when choosing the configuration, i. e.
3105 make TQM823L_defconfig
3106 - will configure for a plain TQM823L, i. e. no LCD support
3108 make TQM823L_LCD_defconfig
3109 - will configure for a TQM823L with U-Boot console on LCD
3111 etc.
3114 Finally, type "make all", and you should get some working U-Boot
3115 images ready for download to / installation on your system:
3117 - "u-boot.bin" is a raw binary image
3118 - "u-boot" is an image in ELF binary format
3119 - "u-boot.srec" is in Motorola S-Record format
3121 By default the build is performed locally and the objects are saved
3122 in the source directory. One of the two methods can be used to change
3123 this behavior and build U-Boot to some external directory:
3125 1. Add O= to the make command line invocations:
3127 make O=/tmp/build distclean
3128 make O=/tmp/build NAME_defconfig
3129 make O=/tmp/build all
3131 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
3133 export KBUILD_OUTPUT=/tmp/build
3134 make distclean
3135 make NAME_defconfig
3136 make all
3138 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
3139 variable.
3141 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
3142 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
3143 For example to treat all compiler warnings as errors:
3145 make KCFLAGS=-Werror
3147 Please be aware that the Makefiles assume you are using GNU make, so
3148 for instance on NetBSD you might need to use "gmake" instead of
3149 native "make".
3152 If the system board that you have is not listed, then you will need
3153 to port U-Boot to your hardware platform. To do this, follow these
3154 steps:
3156 1. Create a new directory to hold your board specific code. Add any
3157 files you need. In your board directory, you will need at least
3158 the "Makefile" and a "<board>.c".
3159 2. Create a new configuration file "include/configs/<board>.h" for
3160 your board.
3161 3. If you're porting U-Boot to a new CPU, then also create a new
3162 directory to hold your CPU specific code. Add any files you need.
3163 4. Run "make <board>_defconfig" with your new name.
3164 5. Type "make", and you should get a working "u-boot.srec" file
3165 to be installed on your target system.
3166 6. Debug and solve any problems that might arise.
3167 [Of course, this last step is much harder than it sounds.]
3170 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
3171 ==============================================================
3173 If you have modified U-Boot sources (for instance added a new board
3174 or support for new devices, a new CPU, etc.) you are expected to
3175 provide feedback to the other developers. The feedback normally takes
3176 the form of a "patch", i.e. a context diff against a certain (latest
3177 official or latest in the git repository) version of U-Boot sources.
3179 But before you submit such a patch, please verify that your modifi-
3180 cation did not break existing code. At least make sure that *ALL* of
3181 the supported boards compile WITHOUT ANY compiler warnings. To do so,
3182 just run the buildman script (tools/buildman/buildman), which will
3183 configure and build U-Boot for ALL supported system. Be warned, this
3184 will take a while. Please see the buildman README, or run 'buildman -H'
3185 for documentation.
3188 See also "U-Boot Porting Guide" below.
3191 Monitor Commands - Overview:
3192 ============================
3194 go - start application at address 'addr'
3195 run - run commands in an environment variable
3196 bootm - boot application image from memory
3197 bootp - boot image via network using BootP/TFTP protocol
3198 bootz - boot zImage from memory
3199 tftpboot- boot image via network using TFTP protocol
3200 and env variables "ipaddr" and "serverip"
3201 (and eventually "gatewayip")
3202 tftpput - upload a file via network using TFTP protocol
3203 rarpboot- boot image via network using RARP/TFTP protocol
3204 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
3205 loads - load S-Record file over serial line
3206 loadb - load binary file over serial line (kermit mode)
3207 md - memory display
3208 mm - memory modify (auto-incrementing)
3209 nm - memory modify (constant address)
3210 mw - memory write (fill)
3211 ms - memory search
3212 cp - memory copy
3213 cmp - memory compare
3214 crc32 - checksum calculation
3215 i2c - I2C sub-system
3216 sspi - SPI utility commands
3217 base - print or set address offset
3218 printenv- print environment variables
3219 setenv - set environment variables
3220 saveenv - save environment variables to persistent storage
3221 protect - enable or disable FLASH write protection
3222 erase - erase FLASH memory
3223 flinfo - print FLASH memory information
3224 nand - NAND memory operations (see doc/README.nand)
3225 bdinfo - print Board Info structure
3226 iminfo - print header information for application image
3227 coninfo - print console devices and informations
3228 ide - IDE sub-system
3229 loop - infinite loop on address range
3230 loopw - infinite write loop on address range
3231 mtest - simple RAM test
3232 icache - enable or disable instruction cache
3233 dcache - enable or disable data cache
3234 reset - Perform RESET of the CPU
3235 echo - echo args to console
3236 version - print monitor version
3237 help - print online help
3238 ? - alias for 'help'
3241 Monitor Commands - Detailed Description:
3242 ========================================
3244 TODO.
3246 For now: just type "help <command>".
3249 Environment Variables:
3250 ======================
3252 U-Boot supports user configuration using Environment Variables which
3253 can be made persistent by saving to Flash memory.
3255 Environment Variables are set using "setenv", printed using
3256 "printenv", and saved to Flash using "saveenv". Using "setenv"
3257 without a value can be used to delete a variable from the
3258 environment. As long as you don't save the environment you are
3259 working with an in-memory copy. In case the Flash area containing the
3260 environment is erased by accident, a default environment is provided.
3262 Some configuration options can be set using Environment Variables.
3264 List of environment variables (most likely not complete):
3266 baudrate - see CONFIG_BAUDRATE
3268 bootdelay - see CONFIG_BOOTDELAY
3270 bootcmd - see CONFIG_BOOTCOMMAND
3272 bootargs - Boot arguments when booting an RTOS image
3274 bootfile - Name of the image to load with TFTP
3276 bootm_low - Memory range available for image processing in the bootm
3277 command can be restricted. This variable is given as
3278 a hexadecimal number and defines lowest address allowed
3279 for use by the bootm command. See also "bootm_size"
3280 environment variable. Address defined by "bootm_low" is
3281 also the base of the initial memory mapping for the Linux
3282 kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
3283 bootm_mapsize.
3285 bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
3286 This variable is given as a hexadecimal number and it
3287 defines the size of the memory region starting at base
3288 address bootm_low that is accessible by the Linux kernel
3289 during early boot. If unset, CONFIG_SYS_BOOTMAPSZ is used
3290 as the default value if it is defined, and bootm_size is
3291 used otherwise.
3293 bootm_size - Memory range available for image processing in the bootm
3294 command can be restricted. This variable is given as
3295 a hexadecimal number and defines the size of the region
3296 allowed for use by the bootm command. See also "bootm_low"
3297 environment variable.
3299 bootstopkeysha256, bootdelaykey, bootstopkey - See README.autoboot
3301 updatefile - Location of the software update file on a TFTP server, used
3302 by the automatic software update feature. Please refer to
3303 documentation in doc/README.update for more details.
3305 autoload - if set to "no" (any string beginning with 'n'),
3306 "bootp" will just load perform a lookup of the
3307 configuration from the BOOTP server, but not try to
3308 load any image using TFTP
3310 autostart - if set to "yes", an image loaded using the "bootp",
3311 "rarpboot", "tftpboot" or "diskboot" commands will
3312 be automatically started (by internally calling
3313 "bootm")
3315 If set to "no", a standalone image passed to the
3316 "bootm" command will be copied to the load address
3317 (and eventually uncompressed), but NOT be started.
3318 This can be used to load and uncompress arbitrary
3319 data.
3321 fdt_high - if set this restricts the maximum address that the
3322 flattened device tree will be copied into upon boot.
3323 For example, if you have a system with 1 GB memory
3324 at physical address 0x10000000, while Linux kernel
3325 only recognizes the first 704 MB as low memory, you
3326 may need to set fdt_high as 0x3C000000 to have the
3327 device tree blob be copied to the maximum address
3328 of the 704 MB low memory, so that Linux kernel can
3329 access it during the boot procedure.
3331 If this is set to the special value 0xFFFFFFFF then
3332 the fdt will not be copied at all on boot. For this
3333 to work it must reside in writable memory, have
3334 sufficient padding on the end of it for u-boot to
3335 add the information it needs into it, and the memory
3336 must be accessible by the kernel.
3338 fdtcontroladdr- if set this is the address of the control flattened
3339 device tree used by U-Boot when CONFIG_OF_CONTROL is
3340 defined.
3342 i2cfast - (PPC405GP|PPC405EP only)
3343 if set to 'y' configures Linux I2C driver for fast
3344 mode (400kHZ). This environment variable is used in
3345 initialization code. So, for changes to be effective
3346 it must be saved and board must be reset.
3348 initrd_high - restrict positioning of initrd images:
3349 If this variable is not set, initrd images will be
3350 copied to the highest possible address in RAM; this
3351 is usually what you want since it allows for
3352 maximum initrd size. If for some reason you want to
3353 make sure that the initrd image is loaded below the
3354 CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
3355 variable to a value of "no" or "off" or "0".
3356 Alternatively, you can set it to a maximum upper
3357 address to use (U-Boot will still check that it
3358 does not overwrite the U-Boot stack and data).
3360 For instance, when you have a system with 16 MB
3361 RAM, and want to reserve 4 MB from use by Linux,
3362 you can do this by adding "mem=12M" to the value of
3363 the "bootargs" variable. However, now you must make
3364 sure that the initrd image is placed in the first
3365 12 MB as well - this can be done with
3367 setenv initrd_high 00c00000
3369 If you set initrd_high to 0xFFFFFFFF, this is an
3370 indication to U-Boot that all addresses are legal
3371 for the Linux kernel, including addresses in flash
3372 memory. In this case U-Boot will NOT COPY the
3373 ramdisk at all. This may be useful to reduce the
3374 boot time on your system, but requires that this
3375 feature is supported by your Linux kernel.
3377 ipaddr - IP address; needed for tftpboot command
3379 loadaddr - Default load address for commands like "bootp",
3380 "rarpboot", "tftpboot", "loadb" or "diskboot"
3382 loads_echo - see CONFIG_LOADS_ECHO
3384 serverip - TFTP server IP address; needed for tftpboot command
3386 bootretry - see CONFIG_BOOT_RETRY_TIME
3388 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
3390 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
3392 ethprime - controls which interface is used first.
3394 ethact - controls which interface is currently active.
3395 For example you can do the following
3397 => setenv ethact FEC
3398 => ping 192.168.0.1 # traffic sent on FEC
3399 => setenv ethact SCC
3400 => ping 10.0.0.1 # traffic sent on SCC
3402 ethrotate - When set to "no" U-Boot does not go through all
3403 available network interfaces.
3404 It just stays at the currently selected interface.
3406 netretry - When set to "no" each network operation will
3407 either succeed or fail without retrying.
3408 When set to "once" the network operation will
3409 fail when all the available network interfaces
3410 are tried once without success.
3411 Useful on scripts which control the retry operation
3412 themselves.
3414 npe_ucode - set load address for the NPE microcode
3416 silent_linux - If set then Linux will be told to boot silently, by
3417 changing the console to be empty. If "yes" it will be
3418 made silent. If "no" it will not be made silent. If
3419 unset, then it will be made silent if the U-Boot console
3420 is silent.
3422 tftpsrcp - If this is set, the value is used for TFTP's
3423 UDP source port.
3425 tftpdstp - If this is set, the value is used for TFTP's UDP
3426 destination port instead of the Well Know Port 69.
3428 tftpblocksize - Block size to use for TFTP transfers; if not set,
3429 we use the TFTP server's default block size
3431 tftptimeout - Retransmission timeout for TFTP packets (in milli-
3432 seconds, minimum value is 1000 = 1 second). Defines
3433 when a packet is considered to be lost so it has to
3434 be retransmitted. The default is 5000 = 5 seconds.
3435 Lowering this value may make downloads succeed
3436 faster in networks with high packet loss rates or
3437 with unreliable TFTP servers.
3439 tftptimeoutcountmax - maximum count of TFTP timeouts (no
3440 unit, minimum value = 0). Defines how many timeouts
3441 can happen during a single file transfer before that
3442 transfer is aborted. The default is 10, and 0 means
3443 'no timeouts allowed'. Increasing this value may help
3444 downloads succeed with high packet loss rates, or with
3445 unreliable TFTP servers or client hardware.
3447 tftpwindowsize - if this is set, the value is used for TFTP's
3448 window size as described by RFC 7440.
3449 This means the count of blocks we can receive before
3450 sending ack to server.
3452 vlan - When set to a value < 4095 the traffic over
3453 Ethernet is encapsulated/received over 802.1q
3454 VLAN tagged frames.
3456 bootpretryperiod - Period during which BOOTP/DHCP sends retries.
3457 Unsigned value, in milliseconds. If not set, the period will
3458 be either the default (28000), or a value based on
3459 CONFIG_NET_RETRY_COUNT, if defined. This value has
3460 precedence over the valu based on CONFIG_NET_RETRY_COUNT.
3462 memmatches - Number of matches found by the last 'ms' command, in hex
3464 memaddr - Address of the last match found by the 'ms' command, in hex,
3465 or 0 if none
3467 mempos - Index position of the last match found by the 'ms' command,
3468 in units of the size (.b, .w, .l) of the search
3471 The following image location variables contain the location of images
3472 used in booting. The "Image" column gives the role of the image and is
3473 not an environment variable name. The other columns are environment
3474 variable names. "File Name" gives the name of the file on a TFTP
3475 server, "RAM Address" gives the location in RAM the image will be
3476 loaded to, and "Flash Location" gives the image's address in NOR
3477 flash or offset in NAND flash.
3479 *Note* - these variables don't have to be defined for all boards, some
3480 boards currently use other variables for these purposes, and some
3481 boards use these variables for other purposes.
3483 Image File Name RAM Address Flash Location
3484 ----- --------- ----------- --------------
3485 u-boot u-boot u-boot_addr_r u-boot_addr
3486 Linux kernel bootfile kernel_addr_r kernel_addr
3487 device tree blob fdtfile fdt_addr_r fdt_addr
3488 ramdisk ramdiskfile ramdisk_addr_r ramdisk_addr
3490 The following environment variables may be used and automatically
3491 updated by the network boot commands ("bootp" and "rarpboot"),
3492 depending the information provided by your boot server:
3494 bootfile - see above
3495 dnsip - IP address of your Domain Name Server
3496 dnsip2 - IP address of your secondary Domain Name Server
3497 gatewayip - IP address of the Gateway (Router) to use
3498 hostname - Target hostname
3499 ipaddr - see above
3500 netmask - Subnet Mask
3501 rootpath - Pathname of the root filesystem on the NFS server
3502 serverip - see above
3505 There are two special Environment Variables:
3507 serial# - contains hardware identification information such
3508 as type string and/or serial number
3509 ethaddr - Ethernet address
3511 These variables can be set only once (usually during manufacturing of
3512 the board). U-Boot refuses to delete or overwrite these variables
3513 once they have been set once.
3516 Further special Environment Variables:
3518 ver - Contains the U-Boot version string as printed
3519 with the "version" command. This variable is
3520 readonly (see CONFIG_VERSION_VARIABLE).
3523 Please note that changes to some configuration parameters may take
3524 only effect after the next boot (yes, that's just like Windoze :-).
3527 Callback functions for environment variables:
3528 ---------------------------------------------
3530 For some environment variables, the behavior of u-boot needs to change
3531 when their values are changed. This functionality allows functions to
3532 be associated with arbitrary variables. On creation, overwrite, or
3533 deletion, the callback will provide the opportunity for some side
3534 effect to happen or for the change to be rejected.
3536 The callbacks are named and associated with a function using the
3537 U_BOOT_ENV_CALLBACK macro in your board or driver code.
3539 These callbacks are associated with variables in one of two ways. The
3540 static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
3541 in the board configuration to a string that defines a list of
3542 associations. The list must be in the following format:
3544 entry = variable_name[:callback_name]
3545 list = entry[,list]
3547 If the callback name is not specified, then the callback is deleted.
3548 Spaces are also allowed anywhere in the list.
3550 Callbacks can also be associated by defining the ".callbacks" variable
3551 with the same list format above. Any association in ".callbacks" will
3552 override any association in the static list. You can define
3553 CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
3554 ".callbacks" environment variable in the default or embedded environment.
3556 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
3557 regular expression. This allows multiple variables to be connected to
3558 the same callback without explicitly listing them all out.
3560 The signature of the callback functions is:
3562 int callback(const char *name, const char *value, enum env_op op, int flags)
3564 * name - changed environment variable
3565 * value - new value of the environment variable
3566 * op - operation (create, overwrite, or delete)
3567 * flags - attributes of the environment variable change, see flags H_* in
3568 include/search.h
3570 The return value is 0 if the variable change is accepted and 1 otherwise.
3572 Command Line Parsing:
3573 =====================
3575 There are two different command line parsers available with U-Boot:
3576 the old "simple" one, and the much more powerful "hush" shell:
3578 Old, simple command line parser:
3579 --------------------------------
3581 - supports environment variables (through setenv / saveenv commands)
3582 - several commands on one line, separated by ';'
3583 - variable substitution using "... ${name} ..." syntax
3584 - special characters ('$', ';') can be escaped by prefixing with '\',
3585 for example:
3586 setenv bootcmd bootm \${address}
3587 - You can also escape text by enclosing in single apostrophes, for example:
3588 setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
3590 Hush shell:
3591 -----------
3593 - similar to Bourne shell, with control structures like
3594 if...then...else...fi, for...do...done; while...do...done,
3595 until...do...done, ...
3596 - supports environment ("global") variables (through setenv / saveenv
3597 commands) and local shell variables (through standard shell syntax
3598 "name=value"); only environment variables can be used with "run"
3599 command
3601 General rules:
3602 --------------
3604 (1) If a command line (or an environment variable executed by a "run"
3605 command) contains several commands separated by semicolon, and
3606 one of these commands fails, then the remaining commands will be
3607 executed anyway.
3609 (2) If you execute several variables with one call to run (i. e.
3610 calling run with a list of variables as arguments), any failing
3611 command will cause "run" to terminate, i. e. the remaining
3612 variables are not executed.
3614 Note for Redundant Ethernet Interfaces:
3615 =======================================
3617 Some boards come with redundant Ethernet interfaces; U-Boot supports
3618 such configurations and is capable of automatic selection of a
3619 "working" interface when needed. MAC assignment works as follows:
3621 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
3622 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
3623 "eth1addr" (=>eth1), "eth2addr", ...
3625 If the network interface stores some valid MAC address (for instance
3626 in SROM), this is used as default address if there is NO correspon-
3627 ding setting in the environment; if the corresponding environment
3628 variable is set, this overrides the settings in the card; that means:
3630 o If the SROM has a valid MAC address, and there is no address in the
3631 environment, the SROM's address is used.
3633 o If there is no valid address in the SROM, and a definition in the
3634 environment exists, then the value from the environment variable is
3635 used.
3637 o If both the SROM and the environment contain a MAC address, and
3638 both addresses are the same, this MAC address is used.
3640 o If both the SROM and the environment contain a MAC address, and the
3641 addresses differ, the value from the environment is used and a
3642 warning is printed.
3644 o If neither SROM nor the environment contain a MAC address, an error
3645 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
3646 a random, locally-assigned MAC is used.
3648 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
3649 will be programmed into hardware as part of the initialization process. This
3650 may be skipped by setting the appropriate 'ethmacskip' environment variable.
3651 The naming convention is as follows:
3652 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
3654 Image Formats:
3655 ==============
3657 U-Boot is capable of booting (and performing other auxiliary operations on)
3658 images in two formats:
3660 New uImage format (FIT)
3661 -----------------------
3663 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
3664 to Flattened Device Tree). It allows the use of images with multiple
3665 components (several kernels, ramdisks, etc.), with contents protected by
3666 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
3669 Old uImage format
3670 -----------------
3672 Old image format is based on binary files which can be basically anything,
3673 preceded by a special header; see the definitions in include/image.h for
3674 details; basically, the header defines the following image properties:
3676 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
3677 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
3678 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
3679 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
3680 INTEGRITY).
3681 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
3682 IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
3683 Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC).
3684 * Compression Type (uncompressed, gzip, bzip2)
3685 * Load Address
3686 * Entry Point
3687 * Image Name
3688 * Image Timestamp
3690 The header is marked by a special Magic Number, and both the header
3691 and the data portions of the image are secured against corruption by
3692 CRC32 checksums.
3695 Linux Support:
3696 ==============
3698 Although U-Boot should support any OS or standalone application
3699 easily, the main focus has always been on Linux during the design of
3700 U-Boot.
3702 U-Boot includes many features that so far have been part of some
3703 special "boot loader" code within the Linux kernel. Also, any
3704 "initrd" images to be used are no longer part of one big Linux image;
3705 instead, kernel and "initrd" are separate images. This implementation
3706 serves several purposes:
3708 - the same features can be used for other OS or standalone
3709 applications (for instance: using compressed images to reduce the
3710 Flash memory footprint)
3712 - it becomes much easier to port new Linux kernel versions because
3713 lots of low-level, hardware dependent stuff are done by U-Boot
3715 - the same Linux kernel image can now be used with different "initrd"
3716 images; of course this also means that different kernel images can
3717 be run with the same "initrd". This makes testing easier (you don't
3718 have to build a new "zImage.initrd" Linux image when you just
3719 change a file in your "initrd"). Also, a field-upgrade of the
3720 software is easier now.
3723 Linux HOWTO:
3724 ============
3726 Porting Linux to U-Boot based systems:
3727 ---------------------------------------
3729 U-Boot cannot save you from doing all the necessary modifications to
3730 configure the Linux device drivers for use with your target hardware
3731 (no, we don't intend to provide a full virtual machine interface to
3732 Linux :-).
3734 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
3736 Just make sure your machine specific header file (for instance
3737 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
3738 Information structure as we define in include/asm-<arch>/u-boot.h,
3739 and make sure that your definition of IMAP_ADDR uses the same value
3740 as your U-Boot configuration in CONFIG_SYS_IMMR.
3742 Note that U-Boot now has a driver model, a unified model for drivers.
3743 If you are adding a new driver, plumb it into driver model. If there
3744 is no uclass available, you are encouraged to create one. See
3745 doc/driver-model.
3748 Configuring the Linux kernel:
3749 -----------------------------
3751 No specific requirements for U-Boot. Make sure you have some root
3752 device (initial ramdisk, NFS) for your target system.
3755 Building a Linux Image:
3756 -----------------------
3758 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
3759 not used. If you use recent kernel source, a new build target
3760 "uImage" will exist which automatically builds an image usable by
3761 U-Boot. Most older kernels also have support for a "pImage" target,
3762 which was introduced for our predecessor project PPCBoot and uses a
3763 100% compatible format.
3765 Example:
3767 make TQM850L_defconfig
3768 make oldconfig
3769 make dep
3770 make uImage
3772 The "uImage" build target uses a special tool (in 'tools/mkimage') to
3773 encapsulate a compressed Linux kernel image with header information,
3774 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
3776 * build a standard "vmlinux" kernel image (in ELF binary format):
3778 * convert the kernel into a raw binary image:
3780 ${CROSS_COMPILE}-objcopy -O binary \
3781 -R .note -R .comment \
3782 -S vmlinux linux.bin
3784 * compress the binary image:
3786 gzip -9 linux.bin
3788 * package compressed binary image for U-Boot:
3790 mkimage -A ppc -O linux -T kernel -C gzip \
3791 -a 0 -e 0 -n "Linux Kernel Image" \
3792 -d linux.bin.gz uImage
3795 The "mkimage" tool can also be used to create ramdisk images for use
3796 with U-Boot, either separated from the Linux kernel image, or
3797 combined into one file. "mkimage" encapsulates the images with a 64
3798 byte header containing information about target architecture,
3799 operating system, image type, compression method, entry points, time
3800 stamp, CRC32 checksums, etc.
3802 "mkimage" can be called in two ways: to verify existing images and
3803 print the header information, or to build new images.
3805 In the first form (with "-l" option) mkimage lists the information
3806 contained in the header of an existing U-Boot image; this includes
3807 checksum verification:
3809 tools/mkimage -l image
3810 -l ==> list image header information
3812 The second form (with "-d" option) is used to build a U-Boot image
3813 from a "data file" which is used as image payload:
3815 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
3816 -n name -d data_file image
3817 -A ==> set architecture to 'arch'
3818 -O ==> set operating system to 'os'
3819 -T ==> set image type to 'type'
3820 -C ==> set compression type 'comp'
3821 -a ==> set load address to 'addr' (hex)
3822 -e ==> set entry point to 'ep' (hex)
3823 -n ==> set image name to 'name'
3824 -d ==> use image data from 'datafile'
3826 Right now, all Linux kernels for PowerPC systems use the same load
3827 address (0x00000000), but the entry point address depends on the
3828 kernel version:
3830 - 2.2.x kernels have the entry point at 0x0000000C,
3831 - 2.3.x and later kernels have the entry point at 0x00000000.
3833 So a typical call to build a U-Boot image would read:
3835 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3836 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
3837 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
3838 > examples/uImage.TQM850L
3839 Image Name: 2.4.4 kernel for TQM850L
3840 Created: Wed Jul 19 02:34:59 2000
3841 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3842 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3843 Load Address: 0x00000000
3844 Entry Point: 0x00000000
3846 To verify the contents of the image (or check for corruption):
3848 -> tools/mkimage -l examples/uImage.TQM850L
3849 Image Name: 2.4.4 kernel for TQM850L
3850 Created: Wed Jul 19 02:34:59 2000
3851 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3852 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3853 Load Address: 0x00000000
3854 Entry Point: 0x00000000
3856 NOTE: for embedded systems where boot time is critical you can trade
3857 speed for memory and install an UNCOMPRESSED image instead: this
3858 needs more space in Flash, but boots much faster since it does not
3859 need to be uncompressed:
3861 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
3862 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3863 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3864 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
3865 > examples/uImage.TQM850L-uncompressed
3866 Image Name: 2.4.4 kernel for TQM850L
3867 Created: Wed Jul 19 02:34:59 2000
3868 Image Type: PowerPC Linux Kernel Image (uncompressed)
3869 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
3870 Load Address: 0x00000000
3871 Entry Point: 0x00000000
3874 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3875 when your kernel is intended to use an initial ramdisk:
3877 -> tools/mkimage -n 'Simple Ramdisk Image' \
3878 > -A ppc -O linux -T ramdisk -C gzip \
3879 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3880 Image Name: Simple Ramdisk Image
3881 Created: Wed Jan 12 14:01:50 2000
3882 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3883 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
3884 Load Address: 0x00000000
3885 Entry Point: 0x00000000
3887 The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
3888 option performs the converse operation of the mkimage's second form (the "-d"
3889 option). Given an image built by mkimage, the dumpimage extracts a "data file"
3890 from the image:
3892 tools/dumpimage -i image -T type -p position data_file
3893 -i ==> extract from the 'image' a specific 'data_file'
3894 -T ==> set image type to 'type'
3895 -p ==> 'position' (starting at 0) of the 'data_file' inside the 'image'
3898 Installing a Linux Image:
3899 -------------------------
3901 To downloading a U-Boot image over the serial (console) interface,
3902 you must convert the image to S-Record format:
3904 objcopy -I binary -O srec examples/image examples/image.srec
3906 The 'objcopy' does not understand the information in the U-Boot
3907 image header, so the resulting S-Record file will be relative to
3908 address 0x00000000. To load it to a given address, you need to
3909 specify the target address as 'offset' parameter with the 'loads'
3910 command.
3912 Example: install the image to address 0x40100000 (which on the
3913 TQM8xxL is in the first Flash bank):
3915 => erase 40100000 401FFFFF
3917 .......... done
3918 Erased 8 sectors
3920 => loads 40100000
3921 ## Ready for S-Record download ...
3922 ~>examples/image.srec
3923 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3924 ...
3925 15989 15990 15991 15992
3926 [file transfer complete]
3927 [connected]
3928 ## Start Addr = 0x00000000
3931 You can check the success of the download using the 'iminfo' command;
3932 this includes a checksum verification so you can be sure no data
3933 corruption happened:
3935 => imi 40100000
3937 ## Checking Image at 40100000 ...
3938 Image Name: 2.2.13 for initrd on TQM850L
3939 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3940 Data Size: 335725 Bytes = 327 kB = 0 MB
3941 Load Address: 00000000
3942 Entry Point: 0000000c
3943 Verifying Checksum ... OK
3946 Boot Linux:
3947 -----------
3949 The "bootm" command is used to boot an application that is stored in
3950 memory (RAM or Flash). In case of a Linux kernel image, the contents
3951 of the "bootargs" environment variable is passed to the kernel as
3952 parameters. You can check and modify this variable using the
3953 "printenv" and "setenv" commands:
3956 => printenv bootargs
3957 bootargs=root=/dev/ram
3959 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3961 => printenv bootargs
3962 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3964 => bootm 40020000
3965 ## Booting Linux kernel at 40020000 ...
3966 Image Name: 2.2.13 for NFS on TQM850L
3967 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3968 Data Size: 381681 Bytes = 372 kB = 0 MB
3969 Load Address: 00000000
3970 Entry Point: 0000000c
3971 Verifying Checksum ... OK
3972 Uncompressing Kernel Image ... OK
3973 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
3974 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3975 time_init: decrementer frequency = 187500000/60
3976 Calibrating delay loop... 49.77 BogoMIPS
3977 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3978 ...
3980 If you want to boot a Linux kernel with initial RAM disk, you pass
3981 the memory addresses of both the kernel and the initrd image (PPBCOOT
3982 format!) to the "bootm" command:
3984 => imi 40100000 40200000
3986 ## Checking Image at 40100000 ...
3987 Image Name: 2.2.13 for initrd on TQM850L
3988 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3989 Data Size: 335725 Bytes = 327 kB = 0 MB
3990 Load Address: 00000000
3991 Entry Point: 0000000c
3992 Verifying Checksum ... OK
3994 ## Checking Image at 40200000 ...
3995 Image Name: Simple Ramdisk Image
3996 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3997 Data Size: 566530 Bytes = 553 kB = 0 MB
3998 Load Address: 00000000
3999 Entry Point: 00000000
4000 Verifying Checksum ... OK
4002 => bootm 40100000 40200000
4003 ## Booting Linux kernel at 40100000 ...
4004 Image Name: 2.2.13 for initrd on TQM850L
4005 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4006 Data Size: 335725 Bytes = 327 kB = 0 MB
4007 Load Address: 00000000
4008 Entry Point: 0000000c
4009 Verifying Checksum ... OK
4010 Uncompressing Kernel Image ... OK
4011 ## Loading RAMDisk Image at 40200000 ...
4012 Image Name: Simple Ramdisk Image
4013 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
4014 Data Size: 566530 Bytes = 553 kB = 0 MB
4015 Load Address: 00000000
4016 Entry Point: 00000000
4017 Verifying Checksum ... OK
4018 Loading Ramdisk ... OK
4019 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
4020 Boot arguments: root=/dev/ram
4021 time_init: decrementer frequency = 187500000/60
4022 Calibrating delay loop... 49.77 BogoMIPS
4023 ...
4024 RAMDISK: Compressed image found at block 0
4025 VFS: Mounted root (ext2 filesystem).
4027 bash#
4029 Boot Linux and pass a flat device tree:
4030 -----------
4032 First, U-Boot must be compiled with the appropriate defines. See the section
4033 titled "Linux Kernel Interface" above for a more in depth explanation. The
4034 following is an example of how to start a kernel and pass an updated
4035 flat device tree:
4037 => print oftaddr
4038 oftaddr=0x300000
4039 => print oft
4040 oft=oftrees/mpc8540ads.dtb
4041 => tftp $oftaddr $oft
4042 Speed: 1000, full duplex
4043 Using TSEC0 device
4044 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
4045 Filename 'oftrees/mpc8540ads.dtb'.
4046 Load address: 0x300000
4047 Loading: #
4048 done
4049 Bytes transferred = 4106 (100a hex)
4050 => tftp $loadaddr $bootfile
4051 Speed: 1000, full duplex
4052 Using TSEC0 device
4053 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
4054 Filename 'uImage'.
4055 Load address: 0x200000
4056 Loading:############
4057 done
4058 Bytes transferred = 1029407 (fb51f hex)
4059 => print loadaddr
4060 loadaddr=200000
4061 => print oftaddr
4062 oftaddr=0x300000
4063 => bootm $loadaddr - $oftaddr
4064 ## Booting image at 00200000 ...
4065 Image Name: Linux-2.6.17-dirty
4066 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4067 Data Size: 1029343 Bytes = 1005.2 kB
4068 Load Address: 00000000
4069 Entry Point: 00000000
4070 Verifying Checksum ... OK
4071 Uncompressing Kernel Image ... OK
4072 Booting using flat device tree at 0x300000
4073 Using MPC85xx ADS machine description
4074 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
4075 [snip]
4078 More About U-Boot Image Types:
4079 ------------------------------
4081 U-Boot supports the following image types:
4083 "Standalone Programs" are directly runnable in the environment
4084 provided by U-Boot; it is expected that (if they behave
4085 well) you can continue to work in U-Boot after return from
4086 the Standalone Program.
4087 "OS Kernel Images" are usually images of some Embedded OS which
4088 will take over control completely. Usually these programs
4089 will install their own set of exception handlers, device
4090 drivers, set up the MMU, etc. - this means, that you cannot
4091 expect to re-enter U-Boot except by resetting the CPU.
4092 "RAMDisk Images" are more or less just data blocks, and their
4093 parameters (address, size) are passed to an OS kernel that is
4094 being started.
4095 "Multi-File Images" contain several images, typically an OS
4096 (Linux) kernel image and one or more data images like
4097 RAMDisks. This construct is useful for instance when you want
4098 to boot over the network using BOOTP etc., where the boot
4099 server provides just a single image file, but you want to get
4100 for instance an OS kernel and a RAMDisk image.
4102 "Multi-File Images" start with a list of image sizes, each
4103 image size (in bytes) specified by an "uint32_t" in network
4104 byte order. This list is terminated by an "(uint32_t)0".
4105 Immediately after the terminating 0 follow the images, one by
4106 one, all aligned on "uint32_t" boundaries (size rounded up to
4107 a multiple of 4 bytes).
4109 "Firmware Images" are binary images containing firmware (like
4110 U-Boot or FPGA images) which usually will be programmed to
4111 flash memory.
4113 "Script files" are command sequences that will be executed by
4114 U-Boot's command interpreter; this feature is especially
4115 useful when you configure U-Boot to use a real shell (hush)
4116 as command interpreter.
4118 Booting the Linux zImage:
4119 -------------------------
4121 On some platforms, it's possible to boot Linux zImage. This is done
4122 using the "bootz" command. The syntax of "bootz" command is the same
4123 as the syntax of "bootm" command.
4125 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
4126 kernel with raw initrd images. The syntax is slightly different, the
4127 address of the initrd must be augmented by it's size, in the following
4128 format: "<initrd addres>:<initrd size>".
4131 Standalone HOWTO:
4132 =================
4134 One of the features of U-Boot is that you can dynamically load and
4135 run "standalone" applications, which can use some resources of
4136 U-Boot like console I/O functions or interrupt services.
4138 Two simple examples are included with the sources:
4140 "Hello World" Demo:
4141 -------------------
4143 'examples/hello_world.c' contains a small "Hello World" Demo
4144 application; it is automatically compiled when you build U-Boot.
4145 It's configured to run at address 0x00040004, so you can play with it
4146 like that:
4148 => loads
4149 ## Ready for S-Record download ...
4150 ~>examples/hello_world.srec
4151 1 2 3 4 5 6 7 8 9 10 11 ...
4152 [file transfer complete]
4153 [connected]
4154 ## Start Addr = 0x00040004
4156 => go 40004 Hello World! This is a test.
4157 ## Starting application at 0x00040004 ...
4158 Hello World
4159 argc = 7
4160 argv[0] = "40004"
4161 argv[1] = "Hello"
4162 argv[2] = "World!"
4163 argv[3] = "This"
4164 argv[4] = "is"
4165 argv[5] = "a"
4166 argv[6] = "test."
4167 argv[7] = "<NULL>"
4168 Hit any key to exit ...
4170 ## Application terminated, rc = 0x0
4172 Another example, which demonstrates how to register a CPM interrupt
4173 handler with the U-Boot code, can be found in 'examples/timer.c'.
4174 Here, a CPM timer is set up to generate an interrupt every second.
4175 The interrupt service routine is trivial, just printing a '.'
4176 character, but this is just a demo program. The application can be
4177 controlled by the following keys:
4179 ? - print current values og the CPM Timer registers
4180 b - enable interrupts and start timer
4181 e - stop timer and disable interrupts
4182 q - quit application
4184 => loads
4185 ## Ready for S-Record download ...
4186 ~>examples/timer.srec
4187 1 2 3 4 5 6 7 8 9 10 11 ...
4188 [file transfer complete]
4189 [connected]
4190 ## Start Addr = 0x00040004
4192 => go 40004
4193 ## Starting application at 0x00040004 ...
4194 TIMERS=0xfff00980
4195 Using timer 1
4196 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
4198 Hit 'b':
4199 [q, b, e, ?] Set interval 1000000 us
4200 Enabling timer
4201 Hit '?':
4202 [q, b, e, ?] ........
4203 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
4204 Hit '?':
4205 [q, b, e, ?] .
4206 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
4207 Hit '?':
4208 [q, b, e, ?] .
4209 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
4210 Hit '?':
4211 [q, b, e, ?] .
4212 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
4213 Hit 'e':
4214 [q, b, e, ?] ...Stopping timer
4215 Hit 'q':
4216 [q, b, e, ?] ## Application terminated, rc = 0x0
4219 Minicom warning:
4220 ================
4222 Over time, many people have reported problems when trying to use the
4223 "minicom" terminal emulation program for serial download. I (wd)
4224 consider minicom to be broken, and recommend not to use it. Under
4225 Unix, I recommend to use C-Kermit for general purpose use (and
4226 especially for kermit binary protocol download ("loadb" command), and
4227 use "cu" for S-Record download ("loads" command). See
4228 http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
4229 for help with kermit.
4232 Nevertheless, if you absolutely want to use it try adding this
4233 configuration to your "File transfer protocols" section:
4235 Name Program Name U/D FullScr IO-Red. Multi
4236 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
4237 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
4240 NetBSD Notes:
4241 =============
4243 Starting at version 0.9.2, U-Boot supports NetBSD both as host
4244 (build U-Boot) and target system (boots NetBSD/mpc8xx).
4246 Building requires a cross environment; it is known to work on
4247 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
4248 need gmake since the Makefiles are not compatible with BSD make).
4249 Note that the cross-powerpc package does not install include files;
4250 attempting to build U-Boot will fail because <machine/ansi.h> is
4251 missing. This file has to be installed and patched manually:
4253 # cd /usr/pkg/cross/powerpc-netbsd/include
4254 # mkdir powerpc
4255 # ln -s powerpc machine
4256 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
4257 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
4259 Native builds *don't* work due to incompatibilities between native
4260 and U-Boot include files.
4262 Booting assumes that (the first part of) the image booted is a
4263 stage-2 loader which in turn loads and then invokes the kernel
4264 proper. Loader sources will eventually appear in the NetBSD source
4265 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
4266 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
4269 Implementation Internals:
4270 =========================
4272 The following is not intended to be a complete description of every
4273 implementation detail. However, it should help to understand the
4274 inner workings of U-Boot and make it easier to port it to custom
4275 hardware.
4278 Initial Stack, Global Data:
4279 ---------------------------
4281 The implementation of U-Boot is complicated by the fact that U-Boot
4282 starts running out of ROM (flash memory), usually without access to
4283 system RAM (because the memory controller is not initialized yet).
4284 This means that we don't have writable Data or BSS segments, and BSS
4285 is not initialized as zero. To be able to get a C environment working
4286 at all, we have to allocate at least a minimal stack. Implementation
4287 options for this are defined and restricted by the CPU used: Some CPU
4288 models provide on-chip memory (like the IMMR area on MPC8xx and
4289 MPC826x processors), on others (parts of) the data cache can be
4290 locked as (mis-) used as memory, etc.
4292 Chris Hallinan posted a good summary of these issues to the
4293 U-Boot mailing list:
4295 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
4296 From: "Chris Hallinan" <clh@net1plus.com>
4297 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
4298 ...
4300 Correct me if I'm wrong, folks, but the way I understand it
4301 is this: Using DCACHE as initial RAM for Stack, etc, does not
4302 require any physical RAM backing up the cache. The cleverness
4303 is that the cache is being used as a temporary supply of
4304 necessary storage before the SDRAM controller is setup. It's
4305 beyond the scope of this list to explain the details, but you
4306 can see how this works by studying the cache architecture and
4307 operation in the architecture and processor-specific manuals.
4309 OCM is On Chip Memory, which I believe the 405GP has 4K. It
4310 is another option for the system designer to use as an
4311 initial stack/RAM area prior to SDRAM being available. Either
4312 option should work for you. Using CS 4 should be fine if your
4313 board designers haven't used it for something that would
4314 cause you grief during the initial boot! It is frequently not
4315 used.
4317 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
4318 with your processor/board/system design. The default value
4319 you will find in any recent u-boot distribution in
4320 walnut.h should work for you. I'd set it to a value larger
4321 than your SDRAM module. If you have a 64MB SDRAM module, set
4322 it above 400_0000. Just make sure your board has no resources
4323 that are supposed to respond to that address! That code in
4324 start.S has been around a while and should work as is when
4325 you get the config right.
4327 -Chris Hallinan
4328 DS4.COM, Inc.
4330 It is essential to remember this, since it has some impact on the C
4331 code for the initialization procedures:
4333 * Initialized global data (data segment) is read-only. Do not attempt
4334 to write it.
4336 * Do not use any uninitialized global data (or implicitly initialized
4337 as zero data - BSS segment) at all - this is undefined, initiali-
4338 zation is performed later (when relocating to RAM).
4340 * Stack space is very limited. Avoid big data buffers or things like
4341 that.
4343 Having only the stack as writable memory limits means we cannot use
4344 normal global data to share information between the code. But it
4345 turned out that the implementation of U-Boot can be greatly
4346 simplified by making a global data structure (gd_t) available to all
4347 functions. We could pass a pointer to this data as argument to _all_
4348 functions, but this would bloat the code. Instead we use a feature of
4349 the GCC compiler (Global Register Variables) to share the data: we
4350 place a pointer (gd) to the global data into a register which we
4351 reserve for this purpose.
4353 When choosing a register for such a purpose we are restricted by the
4354 relevant (E)ABI specifications for the current architecture, and by
4355 GCC's implementation.
4357 For PowerPC, the following registers have specific use:
4358 R1: stack pointer
4359 R2: reserved for system use
4360 R3-R4: parameter passing and return values
4361 R5-R10: parameter passing
4362 R13: small data area pointer
4363 R30: GOT pointer
4364 R31: frame pointer
4366 (U-Boot also uses R12 as internal GOT pointer. r12
4367 is a volatile register so r12 needs to be reset when
4368 going back and forth between asm and C)
4370 ==> U-Boot will use R2 to hold a pointer to the global data
4372 Note: on PPC, we could use a static initializer (since the
4373 address of the global data structure is known at compile time),
4374 but it turned out that reserving a register results in somewhat
4375 smaller code - although the code savings are not that big (on
4376 average for all boards 752 bytes for the whole U-Boot image,
4377 624 text + 127 data).
4379 On ARM, the following registers are used:
4381 R0: function argument word/integer result
4382 R1-R3: function argument word
4383 R9: platform specific
4384 R10: stack limit (used only if stack checking is enabled)
4385 R11: argument (frame) pointer
4386 R12: temporary workspace
4387 R13: stack pointer
4388 R14: link register
4389 R15: program counter
4391 ==> U-Boot will use R9 to hold a pointer to the global data
4393 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
4395 On Nios II, the ABI is documented here:
4396 http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
4398 ==> U-Boot will use gp to hold a pointer to the global data
4400 Note: on Nios II, we give "-G0" option to gcc and don't use gp
4401 to access small data sections, so gp is free.
4403 On NDS32, the following registers are used:
4405 R0-R1: argument/return
4406 R2-R5: argument
4407 R15: temporary register for assembler
4408 R16: trampoline register
4409 R28: frame pointer (FP)
4410 R29: global pointer (GP)
4411 R30: link register (LP)
4412 R31: stack pointer (SP)
4413 PC: program counter (PC)
4415 ==> U-Boot will use R10 to hold a pointer to the global data
4417 NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
4418 or current versions of GCC may "optimize" the code too much.
4420 On RISC-V, the following registers are used:
4422 x0: hard-wired zero (zero)
4423 x1: return address (ra)
4424 x2: stack pointer (sp)
4425 x3: global pointer (gp)
4426 x4: thread pointer (tp)
4427 x5: link register (t0)
4428 x8: frame pointer (fp)
4429 x10-x11: arguments/return values (a0-1)
4430 x12-x17: arguments (a2-7)
4431 x28-31: temporaries (t3-6)
4432 pc: program counter (pc)
4434 ==> U-Boot will use gp to hold a pointer to the global data
4436 Memory Management:
4437 ------------------
4439 U-Boot runs in system state and uses physical addresses, i.e. the
4440 MMU is not used either for address mapping nor for memory protection.
4442 The available memory is mapped to fixed addresses using the memory
4443 controller. In this process, a contiguous block is formed for each
4444 memory type (Flash, SDRAM, SRAM), even when it consists of several
4445 physical memory banks.
4447 U-Boot is installed in the first 128 kB of the first Flash bank (on
4448 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
4449 booting and sizing and initializing DRAM, the code relocates itself
4450 to the upper end of DRAM. Immediately below the U-Boot code some
4451 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
4452 configuration setting]. Below that, a structure with global Board
4453 Info data is placed, followed by the stack (growing downward).
4455 Additionally, some exception handler code is copied to the low 8 kB
4456 of DRAM (0x00000000 ... 0x00001FFF).
4458 So a typical memory configuration with 16 MB of DRAM could look like
4459 this:
4461 0x0000 0000 Exception Vector code
4462 :
4463 0x0000 1FFF
4464 0x0000 2000 Free for Application Use
4465 :
4466 :
4468 :
4469 :
4470 0x00FB FF20 Monitor Stack (Growing downward)
4471 0x00FB FFAC Board Info Data and permanent copy of global data
4472 0x00FC 0000 Malloc Arena
4473 :
4474 0x00FD FFFF
4475 0x00FE 0000 RAM Copy of Monitor Code
4476 ... eventually: LCD or video framebuffer
4477 ... eventually: pRAM (Protected RAM - unchanged by reset)
4478 0x00FF FFFF [End of RAM]
4481 System Initialization:
4482 ----------------------
4484 In the reset configuration, U-Boot starts at the reset entry point
4485 (on most PowerPC systems at address 0x00000100). Because of the reset
4486 configuration for CS0# this is a mirror of the on board Flash memory.
4487 To be able to re-map memory U-Boot then jumps to its link address.
4488 To be able to implement the initialization code in C, a (small!)
4489 initial stack is set up in the internal Dual Ported RAM (in case CPUs
4490 which provide such a feature like), or in a locked part of the data
4491 cache. After that, U-Boot initializes the CPU core, the caches and
4492 the SIU.
4494 Next, all (potentially) available memory banks are mapped using a
4495 preliminary mapping. For example, we put them on 512 MB boundaries
4496 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
4497 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
4498 programmed for SDRAM access. Using the temporary configuration, a
4499 simple memory test is run that determines the size of the SDRAM
4500 banks.
4502 When there is more than one SDRAM bank, and the banks are of
4503 different size, the largest is mapped first. For equal size, the first
4504 bank (CS2#) is mapped first. The first mapping is always for address
4505 0x00000000, with any additional banks following immediately to create
4506 contiguous memory starting from 0.
4508 Then, the monitor installs itself at the upper end of the SDRAM area
4509 and allocates memory for use by malloc() and for the global Board
4510 Info data; also, the exception vector code is copied to the low RAM
4511 pages, and the final stack is set up.
4513 Only after this relocation will you have a "normal" C environment;
4514 until that you are restricted in several ways, mostly because you are
4515 running from ROM, and because the code will have to be relocated to a
4516 new address in RAM.
4519 U-Boot Porting Guide:
4520 ----------------------
4522 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
4523 list, October 2002]
4526 int main(int argc, char *argv[])
4527 {
4528 sighandler_t no_more_time;
4530 signal(SIGALRM, no_more_time);
4531 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
4533 if (available_money > available_manpower) {
4534 Pay consultant to port U-Boot;
4535 return 0;
4536 }
4538 Download latest U-Boot source;
4540 Subscribe to u-boot mailing list;
4542 if (clueless)
4543 email("Hi, I am new to U-Boot, how do I get started?");
4545 while (learning) {
4546 Read the README file in the top level directory;
4547 Read http://www.denx.de/twiki/bin/view/DULG/Manual;
4548 Read applicable doc/README.*;
4549 Read the source, Luke;
4550 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
4551 }
4553 if (available_money > toLocalCurrency ($2500))
4554 Buy a BDI3000;
4555 else
4556 Add a lot of aggravation and time;
4558 if (a similar board exists) { /* hopefully... */
4559 cp -a board/<similar> board/<myboard>
4560 cp include/configs/<similar>.h include/configs/<myboard>.h
4561 } else {
4562 Create your own board support subdirectory;
4563 Create your own board include/configs/<myboard>.h file;
4564 }
4565 Edit new board/<myboard> files
4566 Edit new include/configs/<myboard>.h
4568 while (!accepted) {
4569 while (!running) {
4570 do {
4571 Add / modify source code;
4572 } until (compiles);
4573 Debug;
4574 if (clueless)
4575 email("Hi, I am having problems...");
4576 }
4577 Send patch file to the U-Boot email list;
4578 if (reasonable critiques)
4579 Incorporate improvements from email list code review;
4580 else
4581 Defend code as written;
4582 }
4584 return 0;
4585 }
4587 void no_more_time (int sig)
4588 {
4589 hire_a_guru();
4590 }
4593 Coding Standards:
4594 -----------------
4596 All contributions to U-Boot should conform to the Linux kernel
4597 coding style; see the kernel coding style guide at
4598 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
4599 script "scripts/Lindent" in your Linux kernel source directory.
4601 Source files originating from a different project (for example the
4602 MTD subsystem) are generally exempt from these guidelines and are not
4603 reformatted to ease subsequent migration to newer versions of those
4604 sources.
4606 Please note that U-Boot is implemented in C (and to some small parts in
4607 Assembler); no C++ is used, so please do not use C++ style comments (//)
4608 in your code.
4610 Please also stick to the following formatting rules:
4611 - remove any trailing white space
4612 - use TAB characters for indentation and vertical alignment, not spaces
4613 - make sure NOT to use DOS '\r\n' line feeds
4614 - do not add more than 2 consecutive empty lines to source files
4615 - do not add trailing empty lines to source files
4617 Submissions which do not conform to the standards may be returned
4618 with a request to reformat the changes.
4621 Submitting Patches:
4622 -------------------
4624 Since the number of patches for U-Boot is growing, we need to
4625 establish some rules. Submissions which do not conform to these rules
4626 may be rejected, even when they contain important and valuable stuff.
4628 Please see http://www.denx.de/wiki/U-Boot/Patches for details.
4630 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
4631 see https://lists.denx.de/listinfo/u-boot
4633 When you send a patch, please include the following information with
4634 it:
4636 * For bug fixes: a description of the bug and how your patch fixes
4637 this bug. Please try to include a way of demonstrating that the
4638 patch actually fixes something.
4640 * For new features: a description of the feature and your
4641 implementation.
4643 * For major contributions, add a MAINTAINERS file with your
4644 information and associated file and directory references.
4646 * When you add support for a new board, don't forget to add a
4647 maintainer e-mail address to the boards.cfg file, too.
4649 * If your patch adds new configuration options, don't forget to
4650 document these in the README file.
4652 * The patch itself. If you are using git (which is *strongly*
4653 recommended) you can easily generate the patch using the
4654 "git format-patch". If you then use "git send-email" to send it to
4655 the U-Boot mailing list, you will avoid most of the common problems
4656 with some other mail clients.
4658 If you cannot use git, use "diff -purN OLD NEW". If your version of
4659 diff does not support these options, then get the latest version of
4660 GNU diff.
4662 The current directory when running this command shall be the parent
4663 directory of the U-Boot source tree (i. e. please make sure that
4664 your patch includes sufficient directory information for the
4665 affected files).
4667 We prefer patches as plain text. MIME attachments are discouraged,
4668 and compressed attachments must not be used.
4670 * If one logical set of modifications affects or creates several
4671 files, all these changes shall be submitted in a SINGLE patch file.
4673 * Changesets that contain different, unrelated modifications shall be
4674 submitted as SEPARATE patches, one patch per changeset.
4677 Notes:
4679 * Before sending the patch, run the buildman script on your patched
4680 source tree and make sure that no errors or warnings are reported
4681 for any of the boards.
4683 * Keep your modifications to the necessary minimum: A patch
4684 containing several unrelated changes or arbitrary reformats will be
4685 returned with a request to re-formatting / split it.
4687 * If you modify existing code, make sure that your new code does not
4688 add to the memory footprint of the code ;-) Small is beautiful!
4689 When adding new features, these should compile conditionally only
4690 (using #ifdef), and the resulting code with the new feature
4691 disabled must not need more memory than the old code without your
4692 modification.
4694 * Remember that there is a size limit of 100 kB per message on the
4695 u-boot mailing list. Bigger patches will be moderated. If they are
4696 reasonable and not too big, they will be acknowledged. But patches
4697 bigger than the size limit should be avoided.