+menu "printk and dmesg options"
config PRINTK_TIME
bool "Show timing information on printks"
that are auditing their logs closely may want to set it to a lower
priority.
+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 LOCKUP_DETECTOR to detect
+ what it believes to be lockup conditions.
+
+config DYNAMIC_DEBUG
+ bool "Enable dynamic printk() support"
+ default n
+ depends on PRINTK
+ depends on DEBUG_FS
+ help
+
+ Compiles debug level messages into the kernel, which would not
+ otherwise be available at runtime. These messages can then be
+ enabled/disabled based on various levels of scope - per source file,
+ function, module, format string, and line number. This mechanism
+ implicitly compiles in all pr_debug() and dev_dbg() calls, which
+ enlarges the kernel text size by about 2%.
+
+ If a source file is compiled with DEBUG flag set, any
+ pr_debug() calls in it are enabled by default, but can be
+ disabled at runtime as below. Note that DEBUG flag is
+ turned on by many CONFIG_*DEBUG* options.
+
+ Usage:
+
+ Dynamic debugging is controlled via the 'dynamic_debug/control' file,
+ which is contained in the 'debugfs' filesystem. Thus, the debugfs
+ filesystem must first be mounted before making use of this feature.
+ We refer the control file as: <debugfs>/dynamic_debug/control. This
+ file contains a list of the debug statements that can be enabled. The
+ format for each line of the file is:
+
+ filename:lineno [module]function flags format
+
+ filename : source file of the debug statement
+ lineno : line number of the debug statement
+ module : module that contains the debug statement
+ function : function that contains the debug statement
+ flags : '=p' means the line is turned 'on' for printing
+ format : the format used for the debug statement
+
+ From a live system:
+
+ nullarbor:~ # cat <debugfs>/dynamic_debug/control
+ # filename:lineno [module]function flags format
+ fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
+ fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
+ fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
+
+ Example usage:
+
+ // enable the message at line 1603 of file svcsock.c
+ nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
+ <debugfs>/dynamic_debug/control
+
+ // enable all the messages in file svcsock.c
+ nullarbor:~ # echo -n 'file svcsock.c +p' >
+ <debugfs>/dynamic_debug/control
+
+ // enable all the messages in the NFS server module
+ nullarbor:~ # echo -n 'module nfsd +p' >
+ <debugfs>/dynamic_debug/control
+
+ // enable all 12 messages in the function svc_process()
+ nullarbor:~ # echo -n 'func svc_process +p' >
+ <debugfs>/dynamic_debug/control
+
+ // disable all 12 messages in the function svc_process()
+ nullarbor:~ # echo -n 'func svc_process -p' >
+ <debugfs>/dynamic_debug/control
+
+ See Documentation/dynamic-debug-howto.txt for additional information.
+
+endmenu # "printk and dmesg options"
+
+menu "Compile-time checks and compiler options"
+
+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 ENABLE_WARN_DEPRECATED
bool "Enable __deprecated logic"
default y
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
- Enable verbose reporting from modpost in order to help resolve
the section mismatches that are reported.
-config DEBUG_KERNEL
- bool "Kernel debugging"
+#
+# Select this config option from the architecture Kconfig, if 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
- 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
+config FRAME_POINTER
+ bool "Compile the kernel with frame pointers"
+ depends on DEBUG_KERNEL && \
+ (CRIS || M68K || FRV || UML || \
+ AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
+ ARCH_WANT_FRAME_POINTERS
+ default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
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.
+ 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 LOCKUP_DETECTOR
- bool "Detect Hard and Soft Lockups"
- depends on DEBUG_KERNEL && !S390
+config DEBUG_FORCE_WEAK_PER_CPU
+ bool "Force weak per-cpu definitions"
+ depends on DEBUG_KERNEL
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 20 seconds, without giving other tasks a
- chance to run. The current stack trace is displayed upon
- detection and the system will stay locked up.
+ 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.
- Hardlockups are bugs that cause the CPU to loop in kernel mode
- for more than 10 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.
+ 1. percpu symbols must be unique whether static or not
+ 2. percpu variables can't be defined inside a function
- The overhead should be minimal. A periodic hrtimer runs to
- generate interrupts and kick the watchdog task every 4 seconds.
- An NMI is generated every 10 seconds or so to check for hardlockups.
+ To ensure that generic code follows the above rules, this
+ option forces all percpu variables to be defined as weak.
- The frequency of hrtimer and NMI events and the soft and hard lockup
- thresholds can be controlled through the sysctl watchdog_thresh.
+endmenu # "Compiler options"
-config HARDLOCKUP_DETECTOR
- def_bool y
- depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
- depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
+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 BOOTPARAM_HARDLOCKUP_PANIC
- bool "Panic (Reboot) On Hard Lockups"
- depends on HARDLOCKUP_DETECTOR
+config DEBUG_KERNEL
+ bool "Kernel debugging"
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 10 seconds (configurable
- using the watchdog_thresh sysctl).
+ Say Y here if you are developing drivers or trying to debug and
+ identify kernel problems.
- Say N if unsure.
+menu "Memory Debugging"
-config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
- int
- depends on HARDLOCKUP_DETECTOR
- range 0 1
- default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
- default 1 if BOOTPARAM_HARDLOCKUP_PANIC
+source mm/Kconfig.debug
-config BOOTPARAM_SOFTLOCKUP_PANIC
- bool "Panic (Reboot) On Soft Lockups"
- depends on LOCKUP_DETECTOR
+config DEBUG_OBJECTS
+ bool "Debug object operations"
+ depends on DEBUG_KERNEL
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 20 seconds (configurable using the watchdog_thresh
- sysctl), without giving other tasks a chance to run.
+ 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.
- 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.
+config DEBUG_OBJECTS_SELFTEST
+ bool "Debug objects selftest"
+ depends on DEBUG_OBJECTS
+ help
+ This enables the selftest of the object debug code.
- 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 PANIC_ON_OOPS
- bool "Panic on Oops"
- help
- Say Y here to enable the kernel to panic when it oopses. This
- has the same effect as setting oops=panic on the kernel command
- line.
-
- This feature is useful to ensure that the kernel does not do
- anything erroneous after an oops which could result in data
- corruption or other issues.
-
- Say N if unsure.
-
-config PANIC_ON_OOPS_VALUE
- int
- range 0 1
- default 0 if !PANIC_ON_OOPS
- default 1 if PANIC_ON_OOPS
-
-config DETECT_HUNG_TASK
- bool "Detect Hung Tasks"
- depends on DEBUG_KERNEL
- default LOCKUP_DETECTOR
- 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_secs
- sysctl or by writing a value to
- /proc/sys/kernel/hung_task_timeout_secs.
-
- 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_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"
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.
+ 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_STACK_USAGE
+ bool "Stack utilization instrumentation"
+ depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
+ help
+ Enables the display of the minimum amount of free stack which each
+ task has ever had available in the sysrq-T and sysrq-P debug output.
+
+ This option will slow down process creation somewhat.
+
+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_VM_RB
+ bool "Debug VM red-black trees"
+ depends on DEBUG_VM
+ help
+ Enable this to turn on more 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_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 MEMORY_NOTIFIER_ERROR_INJECT
+ tristate "Memory hotplug notifier error injection module"
+ depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
+ help
+ This option provides the ability to inject artificial errors to
+ memory hotplug notifier chain callbacks. It is controlled through
+ debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
+
+ If the notifier call chain should be failed with some events
+ notified, write the error code to "actions/<notifier event>/error".
+
+ Example: Inject memory hotplug offline error (-12 == -ENOMEM)
+
+ # cd /sys/kernel/debug/notifier-error-inject/memory
+ # echo -12 > actions/MEM_GOING_OFFLINE/error
+ # echo offline > /sys/devices/system/memory/memoryXXX/state
+ bash: echo: write error: Cannot allocate memory
+
+ To compile this code as a module, choose M here: the module will
+ be called memory-notifier-error-inject.
+
+ If unsure, say N.
+
+config DEBUG_PER_CPU_MAPS
+ bool "Debug access to per_cpu maps"
+ depends on DEBUG_KERNEL
+ depends on SMP
+ help
+ Say Y to verify that the per_cpu map being accessed has
+ been set up. This adds a fair amount of code to kernel memory
+ and decreases performance.
+
+ Say N if unsure.
+
+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 HAVE_DEBUG_STACKOVERFLOW
+ bool
+
+config DEBUG_STACKOVERFLOW
+ bool "Check for stack overflows"
+ depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
+ ---help---
+ Say Y here if you want to check for overflows of kernel, IRQ
+ and exception stacks (if your archicture uses them). This
+ option will show detailed messages if free stack space drops
+ below a certain limit.
+
+ These kinds of bugs usually occur when call-chains in the
+ kernel get too deep, especially when interrupts are
+ involved.
+
+ Use this in cases where you see apparently random memory
+ corruption, especially if it appears in 'struct thread_info'
+
+ If in doubt, say "N".
+
+source "lib/Kconfig.kmemcheck"
+
+endmenu # "Memory Debugging"
+
+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.
+
+menu "Debug Lockups and Hangs"
+
+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 20 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 10 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 4 seconds.
+ An NMI is generated every 10 seconds or so to check for hardlockups.
+
+ The frequency of hrtimer and NMI events and the soft and hard lockup
+ thresholds can be controlled through the sysctl watchdog_thresh.
+
+config HARDLOCKUP_DETECTOR
+ def_bool y
+ depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
+ depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
+
+config BOOTPARAM_HARDLOCKUP_PANIC
+ bool "Panic (Reboot) On Hard Lockups"
+ depends on HARDLOCKUP_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 10 seconds (configurable
+ using the watchdog_thresh sysctl).
+
+ Say N if unsure.
+
+config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
+ int
+ depends on HARDLOCKUP_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 20 seconds (configurable using the watchdog_thresh
+ sysctl), 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 LOCKUP_DETECTOR
+ 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_secs
+ sysctl or by writing a value to
+ /proc/sys/kernel/hung_task_timeout_secs.
+
+ 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.
- In order to access the kmemleak file, debugfs needs to be
- mounted (usually at /sys/kernel/debug).
+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 DEBUG_KMEMLEAK_EARLY_LOG_SIZE
- int "Maximum kmemleak early log entries"
- depends on DEBUG_KMEMLEAK
- range 200 40000
- default 400
+endmenu # "Debug lockups and hangs"
+
+config PANIC_ON_OOPS
+ bool "Panic on Oops"
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.
+ Say Y here to enable the kernel to panic when it oopses. This
+ has the same effect as setting oops=panic on the kernel command
+ line.
-config DEBUG_KMEMLEAK_TEST
- tristate "Simple test for the kernel memory leak detector"
- depends on DEBUG_KMEMLEAK && m
+ This feature is useful to ensure that the kernel does not do
+ anything erroneous after an oops which could result in data
+ corruption or other issues.
+
+ Say N if unsure.
+
+config PANIC_ON_OOPS_VALUE
+ int
+ range 0 1
+ default 0 if !PANIC_ON_OOPS
+ default 1 if PANIC_ON_OOPS
+
+config SCHED_DEBUG
+ bool "Collect scheduler debugging info"
+ depends on DEBUG_KERNEL && PROC_FS
+ default y
help
- This option enables a module that explicitly leaks memory.
+ 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.
- If unsure, say N.
+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 DEBUG_KMEMLEAK_DEFAULT_OFF
- bool "Default kmemleak to off"
- depends on DEBUG_KMEMLEAK
+config TIMER_STATS
+ bool "Collect kernel timers statistics"
+ depends on DEBUG_KERNEL && PROC_FS
help
- Say Y here to disable kmemleak by default. It can then be enabled
- on the command line via kmemleak=on.
+ 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_PREEMPT
bool "Debug preemptible kernel"
if kernel code uses it in a preemption-unsafe way. Also, the kernel
will detect preemption count underflows.
+menu "Lock Debugging (spinlocks, mutexes, etc...)"
+
config DEBUG_RT_MUTEXES
bool "RT Mutex debugging, deadlock detection"
depends on DEBUG_KERNEL && RT_MUTEXES
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_ATOMIC_SLEEP
bool "Sleep inside atomic section checking"
select PREEMPT_COUNT
The following locking APIs are covered: spinlocks, rwlocks,
mutexes and rwsems.
-config STACKTRACE
- bool
- depends on STACKTRACE_SUPPORT
+endmenu # lock debugging
-config DEBUG_STACK_USAGE
- bool "Stack utilization instrumentation"
- depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
+config TRACE_IRQFLAGS
+ bool
help
- Enables the display of the minimum amount of free stack which each
- task has ever had available in the sysrq-T and sysrq-P debug output.
+ Enables hooks to interrupt enabling and disabling for
+ either tracing or lock debugging.
- This option will slow down process creation somewhat.
+config STACKTRACE
+ bool
+ depends on STACKTRACE_SUPPORT
config DEBUG_KOBJECT
bool "kobject debugging"
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 HAVE_DEBUG_BUGVERBOSE
bool
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_VM_RB
- bool "Debug VM red-black trees"
- depends on DEBUG_VM
- help
- Enable this to turn on more 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
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
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
If unsure, say N.
-#
-# Select this config option from the architecture Kconfig, if 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 || METAG) || \
- 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 LOCKUP_DETECTOR to detect
- what it believes to be lockup conditions.
-
menu "RCU Debugging"
config PROVE_RCU
Say Y if you want to enable such diagnostics.
-config RCU_TRACE
- bool "Enable tracing for RCU"
- depends on DEBUG_KERNEL
- select TRACE_CLOCK
- help
- This option provides tracing in RCU which presents stats
- in debugfs for debugging RCU implementation.
-
- Say Y here if you want to enable RCU tracing
- Say N if you are unsure.
-
-endmenu # "RCU Debugging"
-
-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"
+config RCU_TRACE
+ bool "Enable tracing for RCU"
depends on DEBUG_KERNEL
- default n
+ select TRACE_CLOCK
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.
+ This option provides tracing in RCU which presents stats
+ in debugfs for debugging RCU implementation.
+ Say Y here if you want to enable RCU tracing
Say N if you are unsure.
+endmenu # "RCU Debugging"
+
config DEBUG_BLOCK_EXT_DEVT
bool "Force extended block device numbers and spread them"
depends on DEBUG_KERNEL
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 DEBUG_PER_CPU_MAPS
- bool "Debug access to per_cpu maps"
- depends on DEBUG_KERNEL
- depends on SMP
- help
- Say Y to verify that the per_cpu map being accessed has
- been set up. This adds a fair amount of code to kernel memory
- and decreases performance.
-
- Say N if unsure.
-
-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 NOTIFIER_ERROR_INJECTION
tristate "Notifier error injection"
depends on DEBUG_KERNEL
If unsure, say N.
-config MEMORY_NOTIFIER_ERROR_INJECT
- tristate "Memory hotplug notifier error injection module"
- depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
- help
- This option provides the ability to inject artificial errors to
- memory hotplug notifier chain callbacks. It is controlled through
- debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
-
- If the notifier call chain should be failed with some events
- notified, write the error code to "actions/<notifier event>/error".
-
- Example: Inject memory hotplug offline error (-12 == -ENOMEM)
-
- # cd /sys/kernel/debug/notifier-error-inject/memory
- # echo -12 > actions/MEM_GOING_OFFLINE/error
- # echo offline > /sys/devices/system/memory/memoryXXX/state
- bash: echo: write error: Cannot allocate memory
-
- To compile this code as a module, choose M here: the module will
- be called memory-notifier-error-inject.
-
- If unsure, say N.
-
config OF_RECONFIG_NOTIFIER_ERROR_INJECT
tristate "OF reconfig notifier error injection module"
depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
If unsure, say N.
-source mm/Kconfig.debug
source kernel/trace/Kconfig
+menu "Runtime Testing"
+
+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 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 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 RBTREE_TEST
tristate "Red-Black tree test"
depends on m && DEBUG_KERNEL
help
A benchmark measuring the performance of the interval tree library
+config ATOMIC64_SELFTEST
+ bool "Perform an atomic64_t self-test at boot"
+ help
+ Enable this option to test the atomic64_t functions at boot.
+
+ If unsure, say N.
+
+config ASYNC_RAID6_TEST
+ tristate "Self test for hardware accelerated raid6 recovery"
+ depends on ASYNC_RAID6_RECOV
+ select ASYNC_MEMCPY
+ ---help---
+ This is a one-shot self test that permutes through the
+ recovery of all the possible two disk failure scenarios for a
+ N-disk array. Recovery is performed with the asynchronous
+ raid6 recovery routines, and will optionally use an offload
+ engine if one is available.
+
+ If unsure, say N.
+
+config TEST_STRING_HELPERS
+ tristate "Test functions located in the string_helpers module at runtime"
+
+config TEST_KSTRTOX
+ tristate "Test kstrto*() family of functions at runtime"
+
+endmenu # runtime tests
+
config PROVIDE_OHCI1394_DMA_INIT
bool "Remote debugging over FireWire early on boot"
depends on PCI && X86
Say N if you are unsure.
-config DYNAMIC_DEBUG
- bool "Enable dynamic printk() support"
- default n
- depends on PRINTK
- depends on DEBUG_FS
- help
-
- Compiles debug level messages into the kernel, which would not
- otherwise be available at runtime. These messages can then be
- enabled/disabled based on various levels of scope - per source file,
- function, module, format string, and line number. This mechanism
- implicitly compiles in all pr_debug() and dev_dbg() calls, which
- enlarges the kernel text size by about 2%.
-
- If a source file is compiled with DEBUG flag set, any
- pr_debug() calls in it are enabled by default, but can be
- disabled at runtime as below. Note that DEBUG flag is
- turned on by many CONFIG_*DEBUG* options.
-
- Usage:
-
- Dynamic debugging is controlled via the 'dynamic_debug/control' file,
- which is contained in the 'debugfs' filesystem. Thus, the debugfs
- filesystem must first be mounted before making use of this feature.
- We refer the control file as: <debugfs>/dynamic_debug/control. This
- file contains a list of the debug statements that can be enabled. The
- format for each line of the file is:
-
- filename:lineno [module]function flags format
-
- filename : source file of the debug statement
- lineno : line number of the debug statement
- module : module that contains the debug statement
- function : function that contains the debug statement
- flags : '=p' means the line is turned 'on' for printing
- format : the format used for the debug statement
-
- From a live system:
-
- nullarbor:~ # cat <debugfs>/dynamic_debug/control
- # filename:lineno [module]function flags format
- fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
- fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
- fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
-
- Example usage:
-
- // enable the message at line 1603 of file svcsock.c
- nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
- <debugfs>/dynamic_debug/control
-
- // enable all the messages in file svcsock.c
- nullarbor:~ # echo -n 'file svcsock.c +p' >
- <debugfs>/dynamic_debug/control
-
- // enable all the messages in the NFS server module
- nullarbor:~ # echo -n 'module nfsd +p' >
- <debugfs>/dynamic_debug/control
-
- // enable all 12 messages in the function svc_process()
- nullarbor:~ # echo -n 'func svc_process +p' >
- <debugfs>/dynamic_debug/control
-
- // disable all 12 messages in the function svc_process()
- nullarbor:~ # echo -n 'func svc_process -p' >
- <debugfs>/dynamic_debug/control
-
- See Documentation/dynamic-debug-howto.txt for additional information.
-
config DMA_API_DEBUG
bool "Enable debugging of DMA-API usage"
depends on HAVE_DMA_API_DEBUG
This option causes a performance degredation. Use only if you want
to debug device drivers. If unsure, say N.
-config ATOMIC64_SELFTEST
- bool "Perform an atomic64_t self-test at boot"
- help
- Enable this option to test the atomic64_t functions at boot.
-
- If unsure, say N.
-
-config ASYNC_RAID6_TEST
- tristate "Self test for hardware accelerated raid6 recovery"
- depends on ASYNC_RAID6_RECOV
- select ASYNC_MEMCPY
- ---help---
- This is a one-shot self test that permutes through the
- recovery of all the possible two disk failure scenarios for a
- N-disk array. Recovery is performed with the asynchronous
- raid6 recovery routines, and will optionally use an offload
- engine if one is available.
-
- If unsure, say N.
-
source "samples/Kconfig"
source "lib/Kconfig.kgdb"
-source "lib/Kconfig.kmemcheck"
-
-config TEST_STRING_HELPERS
- tristate "Test functions located in the string_helpers module at runtime"
-
-config TEST_KSTRTOX
- tristate "Test kstrto*() family of functions at runtime"
projects / cascardo / linux.git / blobdiff