menu "Kernel hacking" source "lib/Kconfig.debug" config STRICT_DEVMEM bool "Filter access to /dev/mem" depends on MMU ---help--- If this option is disabled, you allow userspace (root) access to all of memory, including kernel and userspace memory. Accidental access to this is obviously disastrous, but specific access can be used by people debugging the kernel. If this option is switched on, the /dev/mem file only allows userspace access to memory mapped peripherals. If in doubt, say Y. # RMK wants arm kernels compiled with frame pointers or stack unwinding. # If you know what you are doing and are willing to live without stack # traces, you can get a slightly smaller kernel by setting this option to # n, but then RMK will have to kill you ;). config FRAME_POINTER bool depends on !THUMB2_KERNEL default y if !ARM_UNWIND || FUNCTION_GRAPH_TRACER help If you say N here, the resulting kernel will be slightly smaller and faster. However, if neither FRAME_POINTER nor ARM_UNWIND are enabled, when a problem occurs with the kernel, the information that is reported is severely limited. config ARM_UNWIND bool "Enable stack unwinding support (EXPERIMENTAL)" depends on AEABI && EXPERIMENTAL default y help This option enables stack unwinding support in the kernel using the information automatically generated by the compiler. The resulting kernel image is slightly bigger but the performance is not affected. Currently, this feature only works with EABI compilers. If unsure say Y. config OLD_MCOUNT bool depends on FUNCTION_TRACER && FRAME_POINTER default y config DEBUG_USER bool "Verbose user fault messages" help When a user program crashes due to an exception, the kernel can print a brief message explaining what the problem was. This is sometimes helpful for debugging but serves no purpose on a production system. Most people should say N here. In addition, you need to pass user_debug=N on the kernel command line to enable this feature. N consists of the sum of: 1 - undefined instruction events 2 - system calls 4 - invalid data aborts 8 - SIGSEGV faults 16 - SIGBUS faults config DEBUG_RODATA bool "Write protect kernel text section" default n depends on DEBUG_KERNEL && MMU ---help--- Mark the kernel text section as write-protected in the pagetables, in order to catch accidental (and incorrect) writes to such const data. This will cause the size of the kernel, plus up to 4MB, to be mapped as pages instead of sections, which will increase TLB pressure. If in doubt, say "N". config DEBUG_RODATA_TEST bool "Testcase for the DEBUG_RODATA feature" depends on DEBUG_RODATA default n ---help--- This option enables a testcase for the DEBUG_RODATA feature. If in doubt, say "N" # These options are only for real kernel hackers who want to get their hands dirty. config DEBUG_LL bool "Kernel low-level debugging functions (read help!)" depends on DEBUG_KERNEL help Say Y here to include definitions of printascii, printch, printhex in the kernel. This is helpful if you are debugging code that executes before the console is initialized. Note that selecting this option will limit the kernel to a single UART definition, as specified below. Attempting to boot the kernel image on a different platform *will not work*, so this option should not be enabled for kernels that are intended to be portable. choice prompt "Kernel low-level debugging port" depends on DEBUG_LL config AT91_DEBUG_LL_DBGU0 bool "Kernel low-level debugging on rm9200, 9260/9g20, 9261/9g10 and 9rl" depends on HAVE_AT91_DBGU0 config AT91_DEBUG_LL_DBGU1 bool "Kernel low-level debugging on 9263 and 9g45" depends on HAVE_AT91_DBGU1 config DEBUG_CLPS711X_UART1 bool "Kernel low-level debugging messages via UART1" depends on ARCH_CLPS711X help Say Y here if you want the debug print routines to direct their output to the first serial port on these devices. config DEBUG_CLPS711X_UART2 bool "Kernel low-level debugging messages via UART2" depends on ARCH_CLPS711X help Say Y here if you want the debug print routines to direct their output to the second serial port on these devices. config DEBUG_DAVINCI_DA8XX_UART1 bool "Kernel low-level debugging on DaVinci DA8XX using UART1" depends on ARCH_DAVINCI_DA8XX help Say Y here if you want the debug print routines to direct their output to UART1 serial port on DaVinci DA8XX devices. config DEBUG_DAVINCI_DA8XX_UART2 bool "Kernel low-level debugging on DaVinci DA8XX using UART2" depends on ARCH_DAVINCI_DA8XX help Say Y here if you want the debug print routines to direct their output to UART2 serial port on DaVinci DA8XX devices. config DEBUG_DAVINCI_DMx_UART0 bool "Kernel low-level debugging on DaVinci DMx using UART0" depends on ARCH_DAVINCI_DMx help Say Y here if you want the debug print routines to direct their output to UART0 serial port on DaVinci DMx devices. config DEBUG_DAVINCI_TNETV107X_UART1 bool "Kernel low-level debugging on DaVinci TNETV107x using UART1" depends on ARCH_DAVINCI_TNETV107X help Say Y here if you want the debug print routines to direct their output to UART1 serial port on DaVinci TNETV107X devices. config DEBUG_ZYNQ_UART0 bool "Kernel low-level debugging on Xilinx Zynq using UART0" depends on ARCH_ZYNQ help Say Y here if you want the debug print routines to direct their output to UART0 on the Zynq platform. config DEBUG_ZYNQ_UART1 bool "Kernel low-level debugging on Xilinx Zynq using UART1" depends on ARCH_ZYNQ help Say Y here if you want the debug print routines to direct their output to UART1 on the Zynq platform. If you have a ZC702 board and want early boot messages to appear on the USB serial adaptor, select this option. config DEBUG_DC21285_PORT bool "Kernel low-level debugging messages via footbridge serial port" depends on FOOTBRIDGE help Say Y here if you want the debug print routines to direct their output to the serial port in the DC21285 (Footbridge). config DEBUG_FOOTBRIDGE_COM1 bool "Kernel low-level debugging messages via footbridge 8250 at PCI COM1" depends on FOOTBRIDGE help Say Y here if you want the debug print routines to direct their output to the 8250 at PCI COM1. config DEBUG_HIGHBANK_UART bool "Kernel low-level debugging messages via Highbank UART" depends on ARCH_HIGHBANK help Say Y here if you want the debug print routines to direct their output to the UART on Highbank based devices. config DEBUG_IMX1_UART bool "i.MX1 Debug UART" depends on SOC_IMX1 help Say Y here if you want kernel low-level debugging support on i.MX1. config DEBUG_IMX23_UART bool "i.MX23 Debug UART" depends on SOC_IMX23 help Say Y here if you want kernel low-level debugging support on i.MX23. config DEBUG_IMX25_UART bool "i.MX25 Debug UART" depends on SOC_IMX25 help Say Y here if you want kernel low-level debugging support on i.MX25. config DEBUG_IMX21_IMX27_UART bool "i.MX21 and i.MX27 Debug UART" depends on SOC_IMX21 || SOC_IMX27 help Say Y here if you want kernel low-level debugging support on i.MX21 or i.MX27. config DEBUG_IMX28_UART bool "i.MX28 Debug UART" depends on SOC_IMX28 help Say Y here if you want kernel low-level debugging support on i.MX28. config DEBUG_IMX31_IMX35_UART bool "i.MX31 and i.MX35 Debug UART" depends on SOC_IMX31 || SOC_IMX35 help Say Y here if you want kernel low-level debugging support on i.MX31 or i.MX35. config DEBUG_IMX51_UART bool "i.MX51 Debug UART" depends on SOC_IMX51 help Say Y here if you want kernel low-level debugging support on i.MX51. config DEBUG_IMX50_IMX53_UART bool "i.MX50 and i.MX53 Debug UART" depends on SOC_IMX50 || SOC_IMX53 help Say Y here if you want kernel low-level debugging support on i.MX50 or i.MX53. config DEBUG_IMX6Q_UART bool "i.MX6Q Debug UART" depends on SOC_IMX6Q help Say Y here if you want kernel low-level debugging support on i.MX6Q. config DEBUG_MMP_UART2 bool "Kernel low-level debugging message via MMP UART2" depends on ARCH_MMP help Say Y here if you want kernel low-level debugging support on MMP UART2. config DEBUG_MMP_UART3 bool "Kernel low-level debugging message via MMP UART3" depends on ARCH_MMP help Say Y here if you want kernel low-level debugging support on MMP UART3. config DEBUG_MSM_UART1 bool "Kernel low-level debugging messages via MSM UART1" depends on ARCH_MSM7X00A || ARCH_MSM7X30 || ARCH_QSD8X50 help Say Y here if you want the debug print routines to direct their output to the first serial port on MSM devices. config DEBUG_MSM_UART2 bool "Kernel low-level debugging messages via MSM UART2" depends on ARCH_MSM7X00A || ARCH_MSM7X30 || ARCH_QSD8X50 help Say Y here if you want the debug print routines to direct their output to the second serial port on MSM devices. config DEBUG_MSM_UART3 bool "Kernel low-level debugging messages via MSM UART3" depends on ARCH_MSM7X00A || ARCH_MSM7X30 || ARCH_QSD8X50 help Say Y here if you want the debug print routines to direct their output to the third serial port on MSM devices. config DEBUG_MSM8660_UART bool "Kernel low-level debugging messages via MSM 8660 UART" depends on ARCH_MSM8X60 select MSM_HAS_DEBUG_UART_HS help Say Y here if you want the debug print routines to direct their output to the serial port on MSM 8660 devices. config DEBUG_MSM8960_UART bool "Kernel low-level debugging messages via MSM 8960 UART" depends on ARCH_MSM8960 select MSM_HAS_DEBUG_UART_HS help Say Y here if you want the debug print routines to direct their output to the serial port on MSM 8960 devices. config DEBUG_MVEBU_UART bool "Kernel low-level debugging messages via MVEBU UART" depends on ARCH_MVEBU help Say Y here if you want kernel low-level debugging support on MVEBU based platforms. config DEBUG_PICOXCELL_UART depends on ARCH_PICOXCELL bool "Use PicoXcell UART for low-level debug" help Say Y here if you want kernel low-level debugging support on PicoXcell based platforms. config DEBUG_REALVIEW_STD_PORT bool "RealView Default UART" depends on ARCH_REALVIEW help Say Y here if you want the debug print routines to direct their output to the serial port on RealView EB, PB11MP, PBA8 and PBX platforms. config DEBUG_REALVIEW_PB1176_PORT bool "RealView PB1176 UART" depends on MACH_REALVIEW_PB1176 help Say Y here if you want the debug print routines to direct their output to the standard serial port on the RealView PB1176 platform. config DEBUG_S3C_UART0 depends on PLAT_SAMSUNG bool "Use S3C UART 0 for low-level debug" help Say Y here if you want the debug print routines to direct their output to UART 0. The port must have been initialised by the boot-loader before use. The uncompressor code port configuration is now handled by CONFIG_S3C_LOWLEVEL_UART_PORT. config DEBUG_S3C_UART1 depends on PLAT_SAMSUNG bool "Use S3C UART 1 for low-level debug" help Say Y here if you want the debug print routines to direct their output to UART 1. The port must have been initialised by the boot-loader before use. The uncompressor code port configuration is now handled by CONFIG_S3C_LOWLEVEL_UART_PORT. config DEBUG_S3C_UART2 depends on PLAT_SAMSUNG bool "Use S3C UART 2 for low-level debug" help Say Y here if you want the debug print routines to direct their output to UART 2. The port must have been initialised by the boot-loader before use. The uncompressor code port configuration is now handled by CONFIG_S3C_LOWLEVEL_UART_PORT. config DEBUG_S3C_UART3 depends on PLAT_SAMSUNG && ARCH_EXYNOS bool "Use S3C UART 3 for low-level debug" help Say Y here if you want the debug print routines to direct their output to UART 3. The port must have been initialised by the boot-loader before use. The uncompressor code port configuration is now handled by CONFIG_S3C_LOWLEVEL_UART_PORT. config DEBUG_SOCFPGA_UART depends on ARCH_SOCFPGA bool "Use SOCFPGA UART for low-level debug" help Say Y here if you want kernel low-level debugging support on SOCFPGA based platforms. config DEBUG_SUNXI_UART0 bool "Kernel low-level debugging messages via sunXi UART0" depends on ARCH_SUNXI help Say Y here if you want kernel low-level debugging support on Allwinner A1X based platforms on the UART0. config DEBUG_SUNXI_UART1 bool "Kernel low-level debugging messages via sunXi UART1" depends on ARCH_SUNXI help Say Y here if you want kernel low-level debugging support on Allwinner A1X based platforms on the UART1. config DEBUG_TEGRA_UART depends on ARCH_TEGRA bool "Use Tegra UART for low-level debug" help Say Y here if you want kernel low-level debugging support on Tegra based platforms. config DEBUG_VEXPRESS_UART0_DETECT bool "Autodetect UART0 on Versatile Express Cortex-A core tiles" depends on ARCH_VEXPRESS && CPU_CP15_MMU help This option enables a simple heuristic which tries to determine the motherboard's memory map variant (original or RS1) and then choose the relevant UART0 base address. Note that this will only work with standard A-class core tiles, and may fail with non-standard SMM or custom software models. config DEBUG_VEXPRESS_UART0_CA9 bool "Use PL011 UART0 at 0x10009000 (V2P-CA9 core tile)" depends on ARCH_VEXPRESS help This option selects UART0 at 0x10009000. Except for custom models, this applies only to the V2P-CA9 tile. config DEBUG_VEXPRESS_UART0_RS1 bool "Use PL011 UART0 at 0x1c090000 (RS1 complaint tiles)" depends on ARCH_VEXPRESS help This option selects UART0 at 0x1c090000. This applies to most of the tiles using the RS1 memory map, including all new A-class core tiles, FPGA-based SMMs and software models. config DEBUG_LL_UART_NONE bool "No low-level debugging UART" depends on !ARCH_MULTIPLATFORM help Say Y here if your platform doesn't provide a UART option below. This relies on your platform choosing the right UART definition internally in order for low-level debugging to work. config DEBUG_ICEDCC bool "Kernel low-level debugging via EmbeddedICE DCC channel" help Say Y here if you want the debug print routines to direct their output to the EmbeddedICE macrocell's DCC channel using co-processor 14. This is known to work on the ARM9 style ICE channel and on the XScale with the PEEDI. Note that the system will appear to hang during boot if there is nothing connected to read from the DCC. config DEBUG_SEMIHOSTING bool "Kernel low-level debug output via semihosting I/O" help Semihosting enables code running on an ARM target to use the I/O facilities on a host debugger/emulator through a simple SVC call. The host debugger or emulator must have semihosting enabled for the special svc call to be trapped otherwise the kernel will crash. This is known to work with OpenOCD, as well as ARM's Fast Models, or any other controlling environment that implements semihosting. For more details about semihosting, please see chapter 8 of DUI0203I_rvct_developer_guide.pdf from ARM Ltd. endchoice config DEBUG_IMX6Q_UART_PORT int "i.MX6Q Debug UART Port (1-5)" if DEBUG_IMX6Q_UART range 1 5 default 1 depends on SOC_IMX6Q help Choose UART port on which kernel low-level debug messages should be output. choice prompt "Low-level debug console UART" depends on DEBUG_LL && DEBUG_TEGRA_UART config TEGRA_DEBUG_UART_AUTO_ODMDATA bool "Via ODMDATA" help Automatically determines which UART to use for low-level debug based on the ODMDATA value. This value is part of the BCT, and is written to the boot memory device using nvflash, or other flashing tool. When bits 19:18 are 3, then bits 17:15 indicate which UART to use; 0/1/2/3/4 are UART A/B/C/D/E. config TEGRA_DEBUG_UARTA bool "UART A" config TEGRA_DEBUG_UARTB bool "UART B" config TEGRA_DEBUG_UARTC bool "UART C" config TEGRA_DEBUG_UARTD bool "UART D" config TEGRA_DEBUG_UARTE bool "UART E" endchoice config DEBUG_LL_INCLUDE string default "debug/icedcc.S" if DEBUG_ICEDCC default "debug/imx.S" if DEBUG_IMX1_UART || \ DEBUG_IMX25_UART || \ DEBUG_IMX21_IMX27_UART || \ DEBUG_IMX31_IMX35_UART || \ DEBUG_IMX51_UART || \ DEBUG_IMX50_IMX53_UART ||\ DEBUG_IMX6Q_UART default "debug/highbank.S" if DEBUG_HIGHBANK_UART default "debug/mvebu.S" if DEBUG_MVEBU_UART default "debug/picoxcell.S" if DEBUG_PICOXCELL_UART default "debug/socfpga.S" if DEBUG_SOCFPGA_UART default "debug/sunxi.S" if DEBUG_SUNXI_UART0 || DEBUG_SUNXI_UART1 default "debug/vexpress.S" if DEBUG_VEXPRESS_UART0_DETECT || \ DEBUG_VEXPRESS_UART0_CA9 || DEBUG_VEXPRESS_UART0_RS1 default "debug/tegra.S" if DEBUG_TEGRA_UART default "debug/zynq.S" if DEBUG_ZYNQ_UART0 || DEBUG_ZYNQ_UART1 default "mach/debug-macro.S" config EARLY_PRINTK bool "Early printk" depends on DEBUG_LL help Say Y here if you want to have an early console using the kernel low-level debugging functions. Add earlyprintk to your kernel parameters to enable this console. config OC_ETM bool "On-chip ETM and ETB" depends on ARM_AMBA help Enables the on-chip embedded trace macrocell and embedded trace buffer driver that will allow you to collect traces of the kernel code. config ARM_KPROBES_TEST tristate "Kprobes test module" depends on KPROBES && MODULES help Perform tests of kprobes API and instruction set simulation. config PID_IN_CONTEXTIDR bool "Write the current PID to the CONTEXTIDR register" depends on CPU_COPY_V6 help Enabling this option causes the kernel to write the current PID to the PROCID field of the CONTEXTIDR register, at the expense of some additional instructions during context switch. Say Y here only if you are planning to use hardware trace tools with this kernel. endmenu