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 # 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 DEBUG_LL_UART_NONE bool "No low-level debugging UART" 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_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_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_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. endchoice 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 DEBUG_S3C_UART depends on PLAT_SAMSUNG int "S3C UART to use for low-level debug" default "0" help Choice for UART for kernel low-level using S3C UARTS, should be between zero and two. 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. endmenu