config PRINTK_TIME

bool "Show timing information on printks"

depends on PRINTK

help

Selecting this option causes timing information to be

included in printk output. This allows you to measure

the interval between kernel operations, including bootup

operations. This is useful for identifying long delays

in kernel startup.

config DEFAULT_MESSAGE_LOGLEVEL

int "Default message log level (1-7)"

range 1 7

default "4"

help

Default log level for printk statements with no specified priority.

This was hard-coded to KERN_WARNING since at least 2.6.10 but folks

that are auditing their logs closely may want to set it to a lower

priority.

config ENABLE_WARN_DEPRECATED

bool "Enable __deprecated logic"

default y

help

Enable the __deprecated logic in the kernel build.

Disable this to suppress the "warning: 'foo' is deprecated

(declared at kernel/power/somefile.c:1234)" messages.

config ENABLE_MUST_CHECK

bool "Enable __must_check logic"

default y

help

Enable the __must_check logic in the kernel build. Disable this to

suppress the "warning: ignoring return value of 'foo', declared with

attribute warn_unused_result" messages.

config FRAME_WARN

int "Warn for stack frames larger than (needs gcc 4.4)"

range 0 8192

default 1024 if !64BIT

default 2048 if 64BIT

help

Tell gcc to warn at build time for stack frames larger than this.

Setting this too low will cause a lot of warnings.

Setting it to 0 disables the warning.

Requires gcc 4.4

config MAGIC_SYSRQ

bool "Magic SysRq key"

depends on !UML

help

If you say Y here, you will have some control over the system even

if the system crashes for example during kernel debugging (e.g., you

will be able to flush the buffer cache to disk, reboot the system

immediately or dump some status information). This is accomplished

by pressing various keys while holding SysRq (Alt+PrintScreen). It

also works on a serial console (on PC hardware at least), if you

send a BREAK and then within 5 seconds a command keypress. The

keys are documented in <file:Documentation/sysrq.txt>. Don't say Y

unless you really know what this hack does.

config STRIP_ASM_SYMS

bool "Strip assembler-generated symbols during link"

default n

help

Strip internal assembler-generated symbols during a link (symbols

that look like '.Lxxx') so they don't pollute the output of

get_wchan() and suchlike.

config UNUSED_SYMBOLS

bool "Enable unused/obsolete exported symbols"

default y if X86

help

Unused but exported symbols make the kernel needlessly bigger. For

that reason most of these unused exports will soon be removed. This

option is provided temporarily to provide a transition period in case

some external kernel module needs one of these symbols anyway. If you

encounter such a case in your module, consider if you are actually

using the right API. (rationale: since nobody in the kernel is using

this in a module, there is a pretty good chance it's actually the

wrong interface to use). If you really need the symbol, please send a

mail to the linux kernel mailing list mentioning the symbol and why

you really need it, and what the merge plan to the mainline kernel for

your module is.

config DEBUG_FS

bool "Debug Filesystem"

help

debugfs is a virtual file system that kernel developers use to put

debugging files into. Enable this option to be able to read and

write to these files.

For detailed documentation on the debugfs API, see

Documentation/DocBook/filesystems.

If unsure, say N.

config HEADERS_CHECK

bool "Run 'make headers_check' when building vmlinux"

depends on !UML

help

This option will extract the user-visible kernel headers whenever

building the kernel, and will run basic sanity checks on them to

ensure that exported files do not attempt to include files which

were not exported, etc.

If you're making modifications to header files which are

relevant for userspace, say 'Y', and check the headers

exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in

your build tree), to make sure they're suitable.

config DEBUG_SECTION_MISMATCH

bool "Enable full Section mismatch analysis"

help

The section mismatch analysis checks if there are illegal

references from one section to another section.

Linux will during link or during runtime drop some sections

and any use of code/data previously in these sections will

most likely result in an oops.

In the code functions and variables are annotated with

__init, __devinit etc. (see full list in include/linux/init.h)

which results in the code/data being placed in specific sections.

The section mismatch analysis is always done after a full

kernel build but enabling this option will in addition

do the following:

- Add the option -fno-inline-functions-called-once to gcc

When inlining a function annotated __init in a non-init

function we would lose the section information and thus

the analysis would not catch the illegal reference.

This option tells gcc to inline less but will also

result in a larger kernel.

- Run the section mismatch analysis for each module/built-in.o

When we run the section mismatch analysis on vmlinux.o we

lose valueble information about where the mismatch was

introduced.

Running the analysis for each module/built-in.o file

will tell where the mismatch happens much closer to the

source. The drawback is that we will report the same

mismatch at least twice.

- Enable verbose reporting from modpost to help solving

the section mismatches reported.

config DEBUG_KERNEL

bool "Kernel debugging"

help

Say Y here if you are developing drivers or trying to debug and

identify kernel problems.

config DEBUG_SHIRQ

bool "Debug shared IRQ handlers"

depends on DEBUG_KERNEL && GENERIC_HARDIRQS

help

Enable this to generate a spurious interrupt as soon as a shared

interrupt handler is registered, and just before one is deregistered.

Drivers ought to be able to handle interrupts coming in at those

points; some don't and need to be caught.

config LOCKUP_DETECTOR

bool "Detect Hard and Soft Lockups"

depends on DEBUG_KERNEL && !S390

help

Say Y here to enable the kernel to act as a watchdog to detect

hard and soft lockups.

Softlockups are bugs that cause the kernel to loop in kernel

mode for more than 60 seconds, without giving other tasks a

chance to run. The current stack trace is displayed upon

detection and the system will stay locked up.

Hardlockups are bugs that cause the CPU to loop in kernel mode

for more than 60 seconds, without letting other interrupts have a

chance to run. The current stack trace is displayed upon detection

and the system will stay locked up.

The overhead should be minimal. A periodic hrtimer runs to

generate interrupts and kick the watchdog task every 10-12 seconds.

An NMI is generated every 60 seconds or so to check for hardlockups.

config HARDLOCKUP_DETECTOR

def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI && \

!ARCH_HAS_NMI_WATCHDOG

config BOOTPARAM_HARDLOCKUP_PANIC

bool "Panic (Reboot) On Hard Lockups"

depends on LOCKUP_DETECTOR

help

Say Y here to enable the kernel to panic on "hard lockups",

which are bugs that cause the kernel to loop in kernel

mode with interrupts disabled for more than 60 seconds.

Say N if unsure.

config BOOTPARAM_HARDLOCKUP_PANIC_VALUE

int

depends on LOCKUP_DETECTOR

range 0 1

default 0 if !BOOTPARAM_HARDLOCKUP_PANIC

default 1 if BOOTPARAM_HARDLOCKUP_PANIC

config BOOTPARAM_SOFTLOCKUP_PANIC

bool "Panic (Reboot) On Soft Lockups"

depends on LOCKUP_DETECTOR

help

Say Y here to enable the kernel to panic on "soft lockups",

which are bugs that cause the kernel to loop in kernel

mode for more than 60 seconds, without giving other tasks a

chance to run.

The panic can be used in combination with panic_timeout,

to cause the system to reboot automatically after a

lockup has been detected. This feature is useful for

high-availability systems that have uptime guarantees and

where a lockup must be resolved ASAP.

Say N if unsure.

config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE

int

depends on LOCKUP_DETECTOR

range 0 1

default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC

default 1 if BOOTPARAM_SOFTLOCKUP_PANIC

config DETECT_HUNG_TASK

bool "Detect Hung Tasks"

depends on DEBUG_KERNEL

default DETECT_SOFTLOCKUP

help

Say Y here to enable the kernel to detect "hung tasks",

which are bugs that cause the task to be stuck in

uninterruptible "D" state indefinitiley.

When a hung task is detected, the kernel will print the

current stack trace (which you should report), but the

task will stay in uninterruptible state. If lockdep is

enabled then all held locks will also be reported. This

feature has negligible overhead.

config DEFAULT_HUNG_TASK_TIMEOUT

int "Default timeout for hung task detection (in seconds)"

depends on DETECT_HUNG_TASK

default 120

help

This option controls the default timeout (in seconds) used

to determine when a task has become non-responsive and should

be considered hung.

It can be adjusted at runtime via the kernel.hung_task_timeout

sysctl or by writing a value to /proc/sys/kernel/hung_task_timeout.

A timeout of 0 disables the check. The default is two minutes.

Keeping the default should be fine in most cases.

config BOOTPARAM_HUNG_TASK_PANIC

bool "Panic (Reboot) On Hung Tasks"

depends on DETECT_HUNG_TASK

help

Say Y here to enable the kernel to panic on "hung tasks",

which are bugs that cause the kernel to leave a task stuck

in uninterruptible "D" state.

The panic can be used in combination with panic_timeout,

to cause the system to reboot automatically after a

hung task has been detected. This feature is useful for

high-availability systems that have uptime guarantees and

where a hung tasks must be resolved ASAP.

Say N if unsure.

config BOOTPARAM_HUNG_TASK_PANIC_VALUE

int

depends on DETECT_HUNG_TASK

range 0 1

default 0 if !BOOTPARAM_HUNG_TASK_PANIC

default 1 if BOOTPARAM_HUNG_TASK_PANIC

config SCHED_DEBUG

bool "Collect scheduler debugging info"

depends on DEBUG_KERNEL && PROC_FS

default y

help

If you say Y here, the /proc/sched_debug file will be provided

that can help debug the scheduler. The runtime overhead of this

option is minimal.

config SCHEDSTATS

bool "Collect scheduler statistics"

depends on DEBUG_KERNEL && PROC_FS

help

If you say Y here, additional code will be inserted into the

scheduler and related routines to collect statistics about

scheduler behavior and provide them in /proc/schedstat. These

stats may be useful for both tuning and debugging the scheduler

If you aren't debugging the scheduler or trying to tune a specific

application, you can say N to avoid the very slight overhead

this adds.

config TIMER_STATS

bool "Collect kernel timers statistics"

depends on DEBUG_KERNEL && PROC_FS

help

If you say Y here, additional code will be inserted into the

timer routines to collect statistics about kernel timers being

reprogrammed. The statistics can be read from /proc/timer_stats.

The statistics collection is started by writing 1 to /proc/timer_stats,

writing 0 stops it. This feature is useful to collect information

about timer usage patterns in kernel and userspace. This feature

is lightweight if enabled in the kernel config but not activated

(it defaults to deactivated on bootup and will only be activated

if some application like powertop activates it explicitly).

config DEBUG_OBJECTS

bool "Debug object operations"

depends on DEBUG_KERNEL

help

If you say Y here, additional code will be inserted into the

kernel to track the life time of various objects and validate

the operations on those objects.

config DEBUG_OBJECTS_SELFTEST

bool "Debug objects selftest"

depends on DEBUG_OBJECTS

help

This enables the selftest of the object debug code.

config DEBUG_OBJECTS_FREE

bool "Debug objects in freed memory"

depends on DEBUG_OBJECTS

help

This enables checks whether a k/v free operation frees an area

which contains an object which has not been deactivated

properly. This can make kmalloc/kfree-intensive workloads

much slower.

config DEBUG_OBJECTS_TIMERS

bool "Debug timer objects"

depends on DEBUG_OBJECTS

help

If you say Y here, additional code will be inserted into the

timer routines to track the life time of timer objects and

validate the timer operations.

config DEBUG_OBJECTS_WORK

bool "Debug work objects"

depends on DEBUG_OBJECTS

help

If you say Y here, additional code will be inserted into the

work queue routines to track the life time of work objects and

validate the work operations.

config DEBUG_OBJECTS_RCU_HEAD

bool "Debug RCU callbacks objects"

depends on DEBUG_OBJECTS

help

Enable this to turn on debugging of RCU list heads (call_rcu() usage).

config DEBUG_OBJECTS_PERCPU_COUNTER

bool "Debug percpu counter objects"

depends on DEBUG_OBJECTS

help

If you say Y here, additional code will be inserted into the

percpu counter routines to track the life time of percpu counter

objects and validate the percpu counter operations.

config DEBUG_OBJECTS_ENABLE_DEFAULT

int "debug_objects bootup default value (0-1)"

range 0 1

default "1"

depends on DEBUG_OBJECTS

help

Debug objects boot parameter default value

config DEBUG_SLAB

bool "Debug slab memory allocations"

depends on DEBUG_KERNEL && SLAB && !KMEMCHECK

help

Say Y here to have the kernel do limited verification on memory

allocation as well as poisoning memory on free to catch use of freed

memory. This can make kmalloc/kfree-intensive workloads much slower.

config DEBUG_SLAB_LEAK

bool "Memory leak debugging"

depends on DEBUG_SLAB

config SLUB_DEBUG_ON

bool "SLUB debugging on by default"

depends on SLUB && SLUB_DEBUG && !KMEMCHECK

default n

help

Boot with debugging on by default. SLUB boots by default with

the runtime debug capabilities switched off. Enabling this is

equivalent to specifying the "slub_debug" parameter on boot.

There is no support for more fine grained debug control like

possible with slub_debug=xxx. SLUB debugging may be switched

off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying

"slub_debug=-".

config SLUB_STATS

default n

bool "Enable SLUB performance statistics"

depends on SLUB && SYSFS

help

SLUB statistics are useful to debug SLUBs allocation behavior in

order find ways to optimize the allocator. This should never be

enabled for production use since keeping statistics slows down

the allocator by a few percentage points. The slabinfo command

supports the determination of the most active slabs to figure

out which slabs are relevant to a particular load.

Try running: slabinfo -DA

config DEBUG_KMEMLEAK

bool "Kernel memory leak detector"

depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \

(X86 || ARM || PPC || MIPS || S390 || SPARC64 || SUPERH || MICROBLAZE || TILE)

select DEBUG_FS

select STACKTRACE if STACKTRACE_SUPPORT

select KALLSYMS

select CRC32

help

Say Y here if you want to enable the memory leak

detector. The memory allocation/freeing is traced in a way

similar to the Boehm's conservative garbage collector, the

difference being that the orphan objects are not freed but

only shown in /sys/kernel/debug/kmemleak. Enabling this

feature will introduce an overhead to memory

allocations. See Documentation/kmemleak.txt for more

details.

Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances

of finding leaks due to the slab objects poisoning.

In order to access the kmemleak file, debugfs needs to be

mounted (usually at /sys/kernel/debug).

config DEBUG_KMEMLEAK_EARLY_LOG_SIZE

int "Maximum kmemleak early log entries"

depends on DEBUG_KMEMLEAK

range 200 40000

default 400

help

Kmemleak must track all the memory allocations to avoid

reporting false positives. Since memory may be allocated or

freed before kmemleak is initialised, an early log buffer is

used to store these actions. If kmemleak reports "early log

buffer exceeded", please increase this value.

config DEBUG_KMEMLEAK_TEST

tristate "Simple test for the kernel memory leak detector"

depends on DEBUG_KMEMLEAK && m

help

This option enables a module that explicitly leaks memory.

If unsure, say N.

config DEBUG_KMEMLEAK_DEFAULT_OFF

bool "Default kmemleak to off"

depends on DEBUG_KMEMLEAK

help

Say Y here to disable kmemleak by default. It can then be enabled

on the command line via kmemleak=on.

config DEBUG_PREEMPT

bool "Debug preemptible kernel"

depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT

default y

help

If you say Y here then the kernel will use a debug variant of the

commonly used smp_processor_id() function and will print warnings

if kernel code uses it in a preemption-unsafe way. Also, the kernel

will detect preemption count underflows.

config DEBUG_RT_MUTEXES

bool "RT Mutex debugging, deadlock detection"

depends on DEBUG_KERNEL && RT_MUTEXES

help

This allows rt mutex semantics violations and rt mutex related

deadlocks (lockups) to be detected and reported automatically.

config DEBUG_PI_LIST

bool

default y

depends on DEBUG_RT_MUTEXES

config RT_MUTEX_TESTER

bool "Built-in scriptable tester for rt-mutexes"

depends on DEBUG_KERNEL && RT_MUTEXES

help

This option enables a rt-mutex tester.

config DEBUG_SPINLOCK

bool "Spinlock and rw-lock debugging: basic checks"

depends on DEBUG_KERNEL

help

Say Y here and build SMP to catch missing spinlock initialization

and certain other kinds of spinlock errors commonly made. This is

best used in conjunction with the NMI watchdog so that spinlock

deadlocks are also debuggable.

config DEBUG_MUTEXES

bool "Mutex debugging: basic checks"

depends on DEBUG_KERNEL

help

This feature allows mutex semantics violations to be detected and

reported.

config DEBUG_LOCK_ALLOC

bool "Lock debugging: detect incorrect freeing of live locks"

depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT

select DEBUG_SPINLOCK

select DEBUG_MUTEXES

select LOCKDEP

help

This feature will check whether any held lock (spinlock, rwlock,

mutex or rwsem) is incorrectly freed by the kernel, via any of the

memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),

vfree(), etc.), whether a live lock is incorrectly reinitialized via

spin_lock_init()/mutex_init()/etc., or whether there is any lock

held during task exit.

config PROVE_LOCKING

bool "Lock debugging: prove locking correctness"

depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT

select LOCKDEP

select DEBUG_SPINLOCK

select DEBUG_MUTEXES

select DEBUG_LOCK_ALLOC

select TRACE_IRQFLAGS

default n

help

This feature enables the kernel to prove that all locking

that occurs in the kernel runtime is mathematically

correct: that under no circumstance could an arbitrary (and

not yet triggered) combination of observed locking

sequences (on an arbitrary number of CPUs, running an

arbitrary number of tasks and interrupt contexts) cause a

deadlock.

In short, this feature enables the kernel to report locking

related deadlocks before they actually occur.

The proof does not depend on how hard and complex a

deadlock scenario would be to trigger: how many

participant CPUs, tasks and irq-contexts would be needed

for it to trigger. The proof also does not depend on

timing: if a race and a resulting deadlock is possible

theoretically (no matter how unlikely the race scenario

is), it will be proven so and will immediately be

reported by the kernel (once the event is observed that

makes the deadlock theoretically possible).

If a deadlock is impossible (i.e. the locking rules, as

observed by the kernel, are mathematically correct), the

kernel reports nothing.

NOTE: this feature can also be enabled for rwlocks, mutexes

and rwsems - in which case all dependencies between these

different locking variants are observed and mapped too, and

the proof of observed correctness is also maintained for an

arbitrary combination of these separate locking variants.

For more details, see Documentation/lockdep-design.txt.

config PROVE_RCU

bool "RCU debugging: prove RCU correctness"

depends on PROVE_LOCKING

default n

help

This feature enables lockdep extensions that check for correct

use of RCU APIs. This is currently under development. Say Y

if you want to debug RCU usage or help work on the PROVE_RCU

feature.

Say N if you are unsure.

config PROVE_RCU_REPEATEDLY

bool "RCU debugging: don't disable PROVE_RCU on first splat"

depends on PROVE_RCU

default n

help

By itself, PROVE_RCU will disable checking upon issuing the

first warning (or "splat"). This feature prevents such

disabling, allowing multiple RCU-lockdep warnings to be printed

on a single reboot.

Say Y to allow multiple RCU-lockdep warnings per boot.

Say N if you are unsure.

config SPARSE_RCU_POINTER

bool "RCU debugging: sparse-based checks for pointer usage"

default n

help

This feature enables the __rcu sparse annotation for

RCU-protected pointers. This annotation will cause sparse

to flag any non-RCU used of annotated pointers. This can be

helpful when debugging RCU usage. Please note that this feature

is not intended to enforce code cleanliness; it is instead merely

a debugging aid.

Say Y to make sparse flag questionable use of RCU-protected pointers

Say N if you are unsure.

config LOCKDEP

bool

depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT

select STACKTRACE

select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE

select KALLSYMS

select KALLSYMS_ALL

config LOCK_STAT

bool "Lock usage statistics"

depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT

select LOCKDEP

select DEBUG_SPINLOCK

select DEBUG_MUTEXES

select DEBUG_LOCK_ALLOC

default n

help

This feature enables tracking lock contention points

For more details, see Documentation/lockstat.txt

This also enables lock events required by "perf lock",

subcommand of perf.

If you want to use "perf lock", you also need to turn on

CONFIG_EVENT_TRACING.

CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.

(CONFIG_LOCKDEP defines "acquire" and "release" events.)

config DEBUG_LOCKDEP

bool "Lock dependency engine debugging"

depends on DEBUG_KERNEL && LOCKDEP

help

If you say Y here, the lock dependency engine will do

additional runtime checks to debug itself, at the price

of more runtime overhead.

config TRACE_IRQFLAGS

bool

help

Enables hooks to interrupt enabling and disabling for

either tracing or lock debugging.

config DEBUG_SPINLOCK_SLEEP

bool "Spinlock debugging: sleep-inside-spinlock checking"

depends on DEBUG_KERNEL

help

If you say Y here, various routines which may sleep will become very

noisy if they are called with a spinlock held.

config DEBUG_LOCKING_API_SELFTESTS

bool "Locking API boot-time self-tests"

depends on DEBUG_KERNEL

help

Say Y here if you want the kernel to run a short self-test during

bootup. The self-test checks whether common types of locking bugs

are detected by debugging mechanisms or not. (if you disable

lock debugging then those bugs wont be detected of course.)

The following locking APIs are covered: spinlocks, rwlocks,

mutexes and rwsems.

config STACKTRACE

bool

depends on STACKTRACE_SUPPORT

config DEBUG_KOBJECT

bool "kobject debugging"

depends on DEBUG_KERNEL

help

If you say Y here, some extra kobject debugging messages will be sent

to the syslog.

config DEBUG_HIGHMEM

bool "Highmem debugging"

depends on DEBUG_KERNEL && HIGHMEM

help

This options enables addition error checking for high memory systems.

Disable for production systems.

config DEBUG_BUGVERBOSE

bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT

depends on BUG

depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \

FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300

default y

help

Say Y here to make BUG() panics output the file name and line number

of the BUG call as well as the EIP and oops trace. This aids

debugging but costs about 70-100K of memory.

config DEBUG_INFO

bool "Compile the kernel with debug info"

depends on DEBUG_KERNEL

help

If you say Y here the resulting kernel image will include

debugging info resulting in a larger kernel image.

This adds debug symbols to the kernel and modules (gcc -g), and

is needed if you intend to use kernel crashdump or binary object

tools like crash, kgdb, LKCD, gdb, etc on the kernel.

Say Y here only if you plan to debug the kernel.

If unsure, say N.

config DEBUG_INFO_REDUCED

bool "Reduce debugging information"

depends on DEBUG_INFO

help

If you say Y here gcc is instructed to generate less debugging

information for structure types. This means that tools that

need full debugging information (like kgdb or systemtap) won't

be happy. But if you merely need debugging information to

resolve line numbers there is no loss. Advantage is that

build directory object sizes shrink dramatically over a full

DEBUG_INFO build and compile times are reduced too.

Only works with newer gcc versions.

config DEBUG_VM

bool "Debug VM"

depends on DEBUG_KERNEL

help

Enable this to turn on extended checks in the virtual-memory system

that may impact performance.

If unsure, say N.

config DEBUG_VIRTUAL

bool "Debug VM translations"

depends on DEBUG_KERNEL && X86

help

Enable some costly sanity checks in virtual to page code. This can

catch mistakes with virt_to_page() and friends.

If unsure, say N.

config DEBUG_NOMMU_REGIONS

bool "Debug the global anon/private NOMMU mapping region tree"

depends on DEBUG_KERNEL && !MMU

help

This option causes the global tree of anonymous and private mapping

regions to be regularly checked for invalid topology.

config DEBUG_WRITECOUNT

bool "Debug filesystem writers count"

depends on DEBUG_KERNEL

help

Enable this to catch wrong use of the writers count in struct

vfsmount. This will increase the size of each file struct by

32 bits.

If unsure, say N.

config DEBUG_MEMORY_INIT

bool "Debug memory initialisation" if EXPERT

default !EXPERT

help

Enable this for additional checks during memory initialisation.

The sanity checks verify aspects of the VM such as the memory model

and other information provided by the architecture. Verbose

information will be printed at KERN_DEBUG loglevel depending

on the mminit_loglevel= command-line option.

If unsure, say Y

config DEBUG_LIST

bool "Debug linked list manipulation"

depends on DEBUG_KERNEL

help

Enable this to turn on extended checks in the linked-list

walking routines.

If unsure, say N.

config TEST_LIST_SORT

bool "Linked list sorting test"

depends on DEBUG_KERNEL

help

Enable this to turn on 'list_sort()' function test. This test is

executed only once during system boot, so affects only boot time.

If unsure, say N.

config DEBUG_SG

bool "Debug SG table operations"

depends on DEBUG_KERNEL

help

Enable this to turn on checks on scatter-gather tables. This can

help find problems with drivers that do not properly initialize

their sg tables.

If unsure, say N.

config DEBUG_NOTIFIERS

bool "Debug notifier call chains"

depends on DEBUG_KERNEL

help

Enable this to turn on sanity checking for notifier call chains.

This is most useful for kernel developers to make sure that

modules properly unregister themselves from notifier chains.

This is a relatively cheap check but if you care about maximum

performance, say N.

config DEBUG_CREDENTIALS

bool "Debug credential management"

depends on DEBUG_KERNEL

help

Enable this to turn on some debug checking for credential

management. The additional code keeps track of the number of

pointers from task_structs to any given cred struct, and checks to

see that this number never exceeds the usage count of the cred

struct.

Furthermore, if SELinux is enabled, this also checks that the

security pointer in the cred struct is never seen to be invalid.

If unsure, say N.

#

# Select this config option from the architecture Kconfig, if it

# it is preferred to always offer frame pointers as a config

# option on the architecture (regardless of KERNEL_DEBUG):

#

config ARCH_WANT_FRAME_POINTERS

bool

help

config FRAME_POINTER

bool "Compile the kernel with frame pointers"

depends on DEBUG_KERNEL && \

(CRIS || M68K || FRV || UML || \

AVR32 || SUPERH || BLACKFIN || MN10300) || \

ARCH_WANT_FRAME_POINTERS

default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS

help

If you say Y here the resulting kernel image will be slightly

larger and slower, but it gives very useful debugging information

in case of kernel bugs. (precise oopses/stacktraces/warnings)

config BOOT_PRINTK_DELAY

bool "Delay each boot printk message by N milliseconds"

depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY

help

This build option allows you to read kernel boot messages

by inserting a short delay after each one. The delay is

specified in milliseconds on the kernel command line,

using "boot_delay=N".

It is likely that you would also need to use "lpj=M" to preset

the "loops per jiffie" value.

See a previous boot log for the "lpj" value to use for your

system, and then set "lpj=M" before setting "boot_delay=N".

NOTE: Using this option may adversely affect SMP systems.

I.e., processors other than the first one may not boot up.

BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect

what it believes to be lockup conditions.

config RCU_TORTURE_TEST

tristate "torture tests for RCU"

depends on DEBUG_KERNEL

default n

help

This option provides a kernel module that runs torture tests

on the RCU infrastructure. The kernel module may be built

after the fact on the running kernel to be tested, if desired.

Say Y here if you want RCU torture tests to be built into

the kernel.

Say M if you want the RCU torture tests to build as a module.

Say N if you are unsure.

config RCU_TORTURE_TEST_RUNNABLE

bool "torture tests for RCU runnable by default"

depends on RCU_TORTURE_TEST = y

default n

help

This option provides a way to build the RCU torture tests

directly into the kernel without them starting up at boot

time. You can use /proc/sys/kernel/rcutorture_runnable

to manually override this setting. This /proc file is

available only when the RCU torture tests have been built

into the kernel.

Say Y here if you want the RCU torture tests to start during

boot (you probably don't).

Say N here if you want the RCU torture tests to start only

after being manually enabled via /proc.

config RCU_CPU_STALL_TIMEOUT

int "RCU CPU stall timeout in seconds"

depends on TREE_RCU || TREE_PREEMPT_RCU

range 3 300

default 60

help

If a given RCU grace period extends more than the specified

number of seconds, a CPU stall warning is printed. If the

RCU grace period persists, additional CPU stall warnings are

printed at more widely spaced intervals.

config RCU_CPU_STALL_VERBOSE

bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"

depends on TREE_PREEMPT_RCU

default y

help

This option causes RCU to printk detailed per-task information

for any tasks that are stalling the current RCU grace period.

Say N if you are unsure.

Say Y if you want to enable such checks.

config KPROBES_SANITY_TEST

bool "Kprobes sanity tests"

depends on DEBUG_KERNEL

depends on KPROBES

default n

help

This option provides for testing basic kprobes functionality on

boot. A sample kprobe, jprobe and kretprobe are inserted and

verified for functionality.

Say N if you are unsure.

config BACKTRACE_SELF_TEST

tristate "Self test for the backtrace code"

depends on DEBUG_KERNEL

default n

help

This option provides a kernel module that can be used to test

the kernel stack backtrace code. This option is not useful

for distributions or general kernels, but only for kernel

developers working on architecture code.

Note that if you want to also test saved backtraces, you will

have to enable STACKTRACE as well.

Say N if you are unsure.

config DEBUG_BLOCK_EXT_DEVT

bool "Force extended block device numbers and spread them"

depends on DEBUG_KERNEL

depends on BLOCK

default n

help

BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON

SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT

YOU ARE DOING. Distros, please enable this and fix whatever

is broken.

Conventionally, block device numbers are allocated from

predetermined contiguous area. However, extended block area

may introduce non-contiguous block device numbers. This

option forces most block device numbers to be allocated from

the extended space and spreads them to discover kernel or

userland code paths which assume predetermined contiguous

device number allocation.

Note that turning on this debug option shuffles all the

device numbers for all IDE and SCSI devices including libata

ones, so root partition specified using device number

directly (via rdev or root=MAJ:MIN) won't work anymore.

Textual device names (root=/dev/sdXn) will continue to work.

Say N if you are unsure.

config DEBUG_FORCE_WEAK_PER_CPU

bool "Force weak per-cpu definitions"

depends on DEBUG_KERNEL

help

s390 and alpha require percpu variables in modules to be

defined weak to work around addressing range issue which

puts the following two restrictions on percpu variable

definitions.

1. percpu symbols must be unique whether static or not

2. percpu variables can't be defined inside a function

To ensure that generic code follows the above rules, this

option forces all percpu variables to be defined as weak.

config LKDTM

tristate "Linux Kernel Dump Test Tool Module"

depends on DEBUG_FS

depends on BLOCK

default n

help

This module enables testing of the different dumping mechanisms by

inducing system failures at predefined crash points.

If you don't need it: say N

Choose M here to compile this code as a module. The module will be

called lkdtm.

Documentation on how to use the module can be found in

Documentation/fault-injection/provoke-crashes.txt

config CPU_NOTIFIER_ERROR_INJECT