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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"
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_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.
# 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 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 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 and on the XScale with the PEEDI.
It does include a timeout to ensure that the system does not
totally freeze when there is nothing connected to read.
config OC_ETM
bool "On-chip ETM and ETB"
select 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_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_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
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