| |
| config PRINTK_TIME |
| bool "Show timing information on printks" |
| depends on PRINTK |
| help |
| Selecting this option causes time stamps of the printk() |
| messages to be added to the output of the syslog() system |
| call and at the console. |
| |
| The timestamp is always recorded internally, and exported |
| to /dev/kmsg. This flag just specifies if the timestamp should |
| be included, not that the timestamp is recorded. |
| |
| The behavior is also controlled by the kernel command line |
| parameter printk.time=1. See Documentation/kernel-parameters.txt |
| |
| 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 READABLE_ASM |
| bool "Generate readable assembler code" |
| depends on DEBUG_KERNEL |
| help |
| Disable some compiler optimizations that tend to generate human unreadable |
| assembler output. This may make the kernel slightly slower, but it helps |
| to keep kernel developers who have to stare a lot at assembler listings |
| sane. |
| |
| 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. |
| During linktime or runtime, some sections are dropped; |
| any use of code/data previously in these sections would |
| most likely result in an oops. |
| In the code, functions and variables are annotated with |
| __init, __devinit, etc. (see the full list in include/linux/init.h), |
| which results in the code/data being placed in specific sections. |
| The section mismatch analysis is always performed after a full |
| kernel build, and enabling this option causes the following |
| additional steps to occur: |
| - Add the option -fno-inline-functions-called-once to gcc commands. |
| When inlining a function annotated with __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 it does result in |
| a larger kernel). |
| - Run the section mismatch analysis for each module/built-in.o file. |
| 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 |
| tells where the mismatch happens much closer to the |
| source. The drawback is that the same mismatch is |
| reported at least twice. |
| - Enable verbose reporting from modpost in order to help resolve |
| the section mismatches that are 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 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 PANIC_ON_OOPS |
| bool "Panic on Oops" if EXPERT |
| default n |
| 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_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 HAVE_DEBUG_KMEMLEAK |
| bool |
| |
| config DEBUG_KMEMLEAK |
| bool "Kernel memory leak detector" |
| depends on DEBUG_KERNEL && EXPERIMENTAL && HAVE_DEBUG_KMEMLEAK |
| 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 |
| select UNINLINE_SPIN_UNLOCK |
| 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 PROVE_RCU_DELAY |
| bool "RCU debugging: preemptible RCU race provocation" |
| depends on DEBUG_KERNEL && PREEMPT_RCU |
| default n |
| help |
| There is a class of races that involve an unlikely preemption |
| of __rcu_read_unlock() just after ->rcu_read_lock_nesting has |
| been set to INT_MIN. This feature inserts a delay at that |
| point to increase the probability of these races. |
| |
| Say Y to increase probability of preemption of __rcu_read_unlock(). |
| |
| 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_ATOMIC_SLEEP |
| bool "Sleep inside atomic section checking" |
| select PREEMPT_COUNT |
| depends on DEBUG_KERNEL |
| help |
| If you say Y here, various routines which may sleep will become very |
| noisy if they are called inside atomic sections: when a spinlock is |
| held, inside an rcu read side critical section, inside preempt disabled |
| sections, inside an interrupt, etc... |
| |
| 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_STACK_USAGE |
| bool "Stack utilization instrumentation" |
| depends on DEBUG_KERNEL && !IA64 && !PARISC |
| 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_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 HAVE_DEBUG_BUGVERBOSE |
| bool |
| |
| config DEBUG_BUGVERBOSE |
| bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT |
| depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) |
| 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_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 |
| 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 |
| # 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 LOCKUP_DETECTOR 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 RCU_CPU_STALL_INFO |
| bool "Print additional diagnostics on RCU CPU stall" |
| depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL |
| default n |
| help |
| For each stalled CPU that is aware of the current RCU grace |
| period, print out additional per-CPU diagnostic information |
| regarding scheduling-clock ticks, idle state, and, |
| for RCU_FAST_NO_HZ kernels, idle-entry state. |
| |
| Say N if you are unsure. |
| |
| Say Y if you want to enable such diagnostics. |
| |
| config RCU_TRACE |
| bool "Enable tracing for RCU" |
| depends on DEBUG_KERNEL |
| 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. |
| |
| 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 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 |
| select DEBUG_FS |
| help |
| This option provides the ability to inject artificial errors to |
| specified notifier chain callbacks. It is useful to test the error |
| handling of notifier call chain failures. |
| |
| Say N if unsure. |
| |
| config CPU_NOTIFIER_ERROR_INJECT |
| tristate "CPU notifier error injection module" |
| depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION |
| help |
| This option provides a kernel module that can be used to test |
| the error handling of the cpu notifiers by injecting artificial |
| errors to CPU notifier chain callbacks. It is controlled through |
| debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu |
| |
| If the notifier call chain should be failed with some events |
| notified, write the error code to "actions/<notifier event>/error". |
| |
| Example: Inject CPU offline error (-1 == -EPERM) |
| |
| # cd /sys/kernel/debug/notifier-error-inject/cpu |
| # echo -1 > actions/CPU_DOWN_PREPARE/error |
| # echo 0 > /sys/devices/system/cpu/cpu1/online |
| bash: echo: write error: Operation not permitted |
| |
| To compile this code as a module, choose M here: the module will |
| be called cpu-notifier-error-inject. |
| |
| If unsure, say N. |
| |
| config PM_NOTIFIER_ERROR_INJECT |
| tristate "PM notifier error injection module" |
| depends on PM && NOTIFIER_ERROR_INJECTION |
| default m if PM_DEBUG |
| help |
| This option provides the ability to inject artificial errors to |
| PM notifier chain callbacks. It is controlled through debugfs |
| interface /sys/kernel/debug/notifier-error-inject/pm |
| |
| If the notifier call chain should be failed with some events |
| notified, write the error code to "actions/<notifier event>/error". |
| |
| Example: Inject PM suspend error (-12 = -ENOMEM) |
| |
| # cd /sys/kernel/debug/notifier-error-inject/pm/ |
| # echo -12 > actions/PM_SUSPEND_PREPARE/error |
| # echo mem > /sys/power/state |
| bash: echo: write error: Cannot allocate memory |
| |
| To compile this code as a module, choose M here: the module will |
| be called pm-notifier-error-inject. |
| |
| 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 pSeries-reconfig-notifier-error-inject. |
| |
| If unsure, say N. |
| |
| config PSERIES_RECONFIG_NOTIFIER_ERROR_INJECT |
| tristate "pSeries reconfig notifier error injection module" |
| depends on PPC_PSERIES && NOTIFIER_ERROR_INJECTION |
| help |
| This option provides the ability to inject artificial errors to |
| pSeries reconfig notifier chain callbacks. It is controlled |
| through debugfs interface under |
| /sys/kernel/debug/notifier-error-inject/pSeries-reconfig/ |
| |
| If the notifier call chain should be failed with some events |
| notified, write the error code to "actions/<notifier event>/error". |
| |
| To compile this code as a module, choose M here: the module will |
| be called memory-notifier-error-inject. |
| |
| If unsure, say N. |
| |
| config FAULT_INJECTION |
| bool "Fault-injection framework" |
| depends on DEBUG_KERNEL |
| help |
| Provide fault-injection framework. |
| For more details, see Documentation/fault-injection/. |
| |
| config FAILSLAB |
| bool "Fault-injection capability for kmalloc" |
| depends on FAULT_INJECTION |
| depends on SLAB || SLUB |
| help |
| Provide fault-injection capability for kmalloc. |
| |
| config FAIL_PAGE_ALLOC |
| bool "Fault-injection capabilitiy for alloc_pages()" |
| depends on FAULT_INJECTION |
| help |
| Provide fault-injection capability for alloc_pages(). |
| |
| config FAIL_MAKE_REQUEST |
| bool "Fault-injection capability for disk IO" |
| depends on FAULT_INJECTION && BLOCK |
| help |
| Provide fault-injection capability for disk IO. |
| |
| config FAIL_IO_TIMEOUT |
| bool "Fault-injection capability for faking disk interrupts" |
| depends on FAULT_INJECTION && BLOCK |
| help |
| Provide fault-injection capability on end IO handling. This |
| will make the block layer "forget" an interrupt as configured, |
| thus exercising the error handling. |
| |
| Only works with drivers that use the generic timeout handling, |
| for others it wont do anything. |
| |
| config FAIL_MMC_REQUEST |
| bool "Fault-injection capability for MMC IO" |
| select DEBUG_FS |
| depends on FAULT_INJECTION && MMC |
| help |
| Provide fault-injection capability for MMC IO. |
| This will make the mmc core return data errors. This is |
| useful to test the error handling in the mmc block device |
| and to test how the mmc host driver handles retries from |
| the block device. |
| |
| config FAULT_INJECTION_DEBUG_FS |
| bool "Debugfs entries for fault-injection capabilities" |
| depends on FAULT_INJECTION && SYSFS && DEBUG_FS |
| help |
| Enable configuration of fault-injection capabilities via debugfs. |
| |
| config FAULT_INJECTION_STACKTRACE_FILTER |
| bool "stacktrace filter for fault-injection capabilities" |
| depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT |
| depends on !X86_64 |
| select STACKTRACE |
| select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND |
| help |
| Provide stacktrace filter for fault-injection capabilities |
| |
| config LATENCYTOP |
| bool "Latency measuring infrastructure" |
| depends on HAVE_LATENCYTOP_SUPPORT |
| depends on DEBUG_KERNEL |
| depends on STACKTRACE_SUPPORT |
| depends on PROC_FS |
| select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND |
| select KALLSYMS |
| select KALLSYMS_ALL |
| select STACKTRACE |
| select SCHEDSTATS |
| select SCHED_DEBUG |
| help |
| Enable this option if you want to use the LatencyTOP tool |
| to find out which userspace is blocking on what kernel operations. |
| |
| source mm/Kconfig.debug |
| source kernel/trace/Kconfig |
| |
| config RBTREE_TEST |
| tristate "Red-Black tree test" |
| depends on m && DEBUG_KERNEL |
| help |
| A benchmark measuring the performance of the rbtree library. |
| Also includes rbtree invariant checks. |
| |
| config INTERVAL_TREE_TEST |
| tristate "Interval tree test" |
| depends on m && DEBUG_KERNEL |
| help |
| A benchmark measuring the performance of the interval tree library |
| |
| config PROVIDE_OHCI1394_DMA_INIT |
| bool "Remote debugging over FireWire early on boot" |
| depends on PCI && X86 |
| help |
| If you want to debug problems which hang or crash the kernel early |
| on boot and the crashing machine has a FireWire port, you can use |
| this feature to remotely access the memory of the crashed machine |
| over FireWire. This employs remote DMA as part of the OHCI1394 |
| specification which is now the standard for FireWire controllers. |
| |
| With remote DMA, you can monitor the printk buffer remotely using |
| firescope and access all memory below 4GB using fireproxy from gdb. |
| Even controlling a kernel debugger is possible using remote DMA. |
| |
| Usage: |
| |
| If ohci1394_dma=early is used as boot parameter, it will initialize |
| all OHCI1394 controllers which are found in the PCI config space. |
| |
| As all changes to the FireWire bus such as enabling and disabling |
| devices cause a bus reset and thereby disable remote DMA for all |
| devices, be sure to have the cable plugged and FireWire enabled on |
| the debugging host before booting the debug target for debugging. |
| |
| This code (~1k) is freed after boot. By then, the firewire stack |
| in charge of the OHCI-1394 controllers should be used instead. |
| |
| See Documentation/debugging-via-ohci1394.txt for more information. |
| |
| config FIREWIRE_OHCI_REMOTE_DMA |
| bool "Remote debugging over FireWire with firewire-ohci" |
| depends on FIREWIRE_OHCI |
| help |
| This option lets you use the FireWire bus for remote debugging |
| with help of the firewire-ohci driver. It enables unfiltered |
| remote DMA in firewire-ohci. |
| See Documentation/debugging-via-ohci1394.txt for more information. |
| |
| If unsure, say N. |
| |
| config BUILD_DOCSRC |
| bool "Build targets in Documentation/ tree" |
| depends on HEADERS_CHECK |
| help |
| This option attempts to build objects from the source files in the |
| kernel Documentation/ tree. |
| |
| 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 |
| help |
| Enable this option to debug the use of the DMA API by device drivers. |
| With this option you will be able to detect common bugs in device |
| drivers like double-freeing of DMA mappings or freeing mappings that |
| were never allocated. |
| 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_KSTRTOX |
| tristate "Test kstrto*() family of functions at runtime" |