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 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" depends on SYSFS 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" depends on UNDEFINED || (BLACKFIN) default y # This option is on purpose disabled for now. # It will be enabled when we are down to a reasonable number # of section mismatch warnings (< 10 for an allyesconfig build) 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 DETECT_SOFTLOCKUP bool "Detect Soft Lockups" depends on DEBUG_KERNEL && !S390 default y help Say Y here to enable the kernel to detect "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. When a soft-lockup is detected, the kernel will print the current stack trace (which you should report), but the system will stay locked up. This feature has negligible overhead. (Note that "hard lockups" are separate type of bugs that can be detected via the NMI-watchdog, on platforms that support it.) config BOOTPARAM_SOFTLOCKUP_PANIC bool "Panic (Reboot) On Soft Lockups" depends on DETECT_SOFTLOCKUP 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 DETECT_SOFTLOCKUP 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 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_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 && SLUB_DEBUG && 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 || S390 || SPARC64 || SUPERH || MICROBLAZE) select DEBUG_FS if SYSFS 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 help Say Y or M here to build a test for the kernel memory leak detector. This option enables a module that explicitly leaks memory. If unsure, say N. 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 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. Lines 1–500 of 1093. Load more
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 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" depends on SYSFS 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" depends on UNDEFINED || (BLACKFIN) default y # This option is on purpose disabled for now. # It will be enabled when we are down to a reasonable number # of section mismatch warnings (< 10 for an allyesconfig build) 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 DETECT_SOFTLOCKUP bool "Detect Soft Lockups" depends on DEBUG_KERNEL && !S390 default y help Say Y here to enable the kernel to detect "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. When a soft-lockup is detected, the kernel will print the current stack trace (which you should report), but the system will stay locked up. This feature has negligible overhead. (Note that "hard lockups" are separate type of bugs that can be detected via the NMI-watchdog, on platforms that support it.) config BOOTPARAM_SOFTLOCKUP_PANIC bool "Panic (Reboot) On Soft Lockups" depends on DETECT_SOFTLOCKUP 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 DETECT_SOFTLOCKUP 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 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_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 && SLUB_DEBUG && 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 || S390 || SPARC64 || SUPERH || MICROBLAZE) select DEBUG_FS if SYSFS 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 help Say Y or M here to build a test for the kernel memory leak detector. This option enables a module that explicitly leaks memory. If unsure, say N. 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 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.