menu "Kernel hacking" source "lib/Kconfig.debug" # 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 default y if !ARM_UNWIND && !THUMB2_KERNEL 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" 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 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_ERRORS bool "Verbose kernel error messages" depends on DEBUG_KERNEL help This option controls verbose debugging information which can be printed when the kernel detects an internal error. This debugging information is useful to kernel hackers when tracking down problems, but mostly meaningless to other people. It's safe to say Y unless you are concerned with the code size or don't want to see these messages. config DEBUG_STACK_USAGE bool "Enable stack utilization instrumentation" depends on DEBUG_KERNEL help Enables the display of the minimum amount of free stack which each task has ever had available in the sysrq-T output. config DEBUG_RVIDCC bool "Include the RealView ICE DCC channel device driver" depends on !DEBUG_ICEDCC help Say Y here if you want a serial channel connected through ARM's RealView ICE emulator through to your debugging host. IMPORTANT: if you are not using one of the pre-configured platforms (notably ARM's Integrator or Versatile Platform) then you will need to configure interrupts for DCC and pass the IRQ numbers in the module parameters 'txirq' and 'rxirq', assuming they have been wired into your interrupt controller. If interrupts are not used then a timed polling scheme is used. This introduces poorer performance, using more CPU bandwidth and reducing communication throughput on DCC. This feature requires at least the RealView ICE 1.5 firmware version. config DEBUG_DCC_KGDB bool "Use the RealView ICE DCC serial channel for KGDB debugging" depends on DEBUG_RVIDCC && KGDB help Say Y here if you want to remotely debug the kernel using gdb and the KGDB kernel debugging patches. Refer to the KGDB documentation for more details. Note that only one device can be enabled as the KGDB communications device, so if this is selected, then KGDB on serial devices or Ethernet must be deselected, or the kernel won't link. config DEBUG_DCC_RAW bool "Disable virtual Ethernet on the RealView ICE DCC channel" depends on DEBUG_RVIDCC help Say Y here if you want to disable the virtual Ethernet facility of the RealView ICE. The virtual Ethernet facility provides both a serial channel and an Ethernet channel, and can be used for its serial channel even if Ethernet is not required. Using this has the advantage over raw DCC communications in that serial channel writes that do not have an integral multiple of 4 bytes are not stuffed with nulls to make the packet size. DCC communicates in 32-bit words and, in raw mode, data is packed in 4 bytes per word. Individual write calls pack the data provided, padding any remainder with nulls. Any protocol using this channel must tolerate the embedded nulls. GDB is such a protocol, provided the driver is fed with complete packets, and not one byte at a time. # These options are only for real kernel hackers who want to get their hands dirty. config DEBUG_LL bool "Kernel low-level debugging functions" 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. config DEBUG_LL_CONSOLE bool "Kernel early console" 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 DEBUG_ICEDCC bool "Kernel low-level debugging via EmbeddedICE DCC channel" depends on DEBUG_LL 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. It does include a timeout to ensure that the system does not totally freeze when there is nothing connected to read. config DEBUG_DC21285_PORT bool "Kernel low-level debugging messages via footbridge serial port" depends on DEBUG_LL && FOOTBRIDGE help Say Y here if you want the debug print routines to direct their output to the serial port in the DC21285 (Footbridge). Saying N will cause the debug messages to appear on the first 16550 serial port. config DEBUG_CLPS711X_UART2 bool "Kernel low-level debugging messages via UART2" depends on DEBUG_LL && 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. Saying N will cause the debug messages to appear on the first serial port. config DEBUG_S3C_PORT depends on DEBUG_LL && PLAT_S3C bool "Kernel low-level debugging messages via S3C UART" help Say Y here if you want debug print routines to go to one of the S3C internal UARTs. The chosen UART must have been configured before it is used. config DEBUG_S3C_UART depends on PLAT_S3C 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