3 bool "Show timing information on printks"
6 Selecting this option causes timing information to be
7 included in printk output. This allows you to measure
8 the interval between kernel operations, including bootup
9 operations. This is useful for identifying long delays
12 config ENABLE_WARN_DEPRECATED
13 bool "Enable __deprecated logic"
16 Enable the __deprecated logic in the kernel build.
17 Disable this to suppress the "warning: 'foo' is deprecated
18 (declared at kernel/power/somefile.c:1234)" messages.
20 config ENABLE_MUST_CHECK
21 bool "Enable __must_check logic"
24 Enable the __must_check logic in the kernel build. Disable this to
25 suppress the "warning: ignoring return value of 'foo', declared with
26 attribute warn_unused_result" messages.
29 int "Warn for stack frames larger than (needs gcc 4.4)"
31 default 1024 if !64BIT
34 Tell gcc to warn at build time for stack frames larger than this.
35 Setting this too low will cause a lot of warnings.
36 Setting it to 0 disables the warning.
40 bool "Magic SysRq key"
43 If you say Y here, you will have some control over the system even
44 if the system crashes for example during kernel debugging (e.g., you
45 will be able to flush the buffer cache to disk, reboot the system
46 immediately or dump some status information). This is accomplished
47 by pressing various keys while holding SysRq (Alt+PrintScreen). It
48 also works on a serial console (on PC hardware at least), if you
49 send a BREAK and then within 5 seconds a command keypress. The
50 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
51 unless you really know what this hack does.
54 bool "Enable unused/obsolete exported symbols"
57 Unused but exported symbols make the kernel needlessly bigger. For
58 that reason most of these unused exports will soon be removed. This
59 option is provided temporarily to provide a transition period in case
60 some external kernel module needs one of these symbols anyway. If you
61 encounter such a case in your module, consider if you are actually
62 using the right API. (rationale: since nobody in the kernel is using
63 this in a module, there is a pretty good chance it's actually the
64 wrong interface to use). If you really need the symbol, please send a
65 mail to the linux kernel mailing list mentioning the symbol and why
66 you really need it, and what the merge plan to the mainline kernel for
70 bool "Debug Filesystem"
73 debugfs is a virtual file system that kernel developers use to put
74 debugging files into. Enable this option to be able to read and
77 For detailed documentation on the debugfs API, see
78 Documentation/DocBook/filesystems.
83 bool "Run 'make headers_check' when building vmlinux"
86 This option will extract the user-visible kernel headers whenever
87 building the kernel, and will run basic sanity checks on them to
88 ensure that exported files do not attempt to include files which
89 were not exported, etc.
91 If you're making modifications to header files which are
92 relevant for userspace, say 'Y', and check the headers
93 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
94 your build tree), to make sure they're suitable.
96 config DEBUG_SECTION_MISMATCH
97 bool "Enable full Section mismatch analysis"
99 # This option is on purpose disabled for now.
100 # It will be enabled when we are down to a resonable number
101 # of section mismatch warnings (< 10 for an allyesconfig build)
103 The section mismatch analysis checks if there are illegal
104 references from one section to another section.
105 Linux will during link or during runtime drop some sections
106 and any use of code/data previously in these sections will
107 most likely result in an oops.
108 In the code functions and variables are annotated with
109 __init, __devinit etc. (see full list in include/linux/init.h)
110 which results in the code/data being placed in specific sections.
111 The section mismatch analysis is always done after a full
112 kernel build but enabling this option will in addition
114 - Add the option -fno-inline-functions-called-once to gcc
115 When inlining a function annotated __init in a non-init
116 function we would lose the section information and thus
117 the analysis would not catch the illegal reference.
118 This option tells gcc to inline less but will also
119 result in a larger kernel.
120 - Run the section mismatch analysis for each module/built-in.o
121 When we run the section mismatch analysis on vmlinux.o we
122 lose valueble information about where the mismatch was
124 Running the analysis for each module/built-in.o file
125 will tell where the mismatch happens much closer to the
126 source. The drawback is that we will report the same
127 mismatch at least twice.
128 - Enable verbose reporting from modpost to help solving
129 the section mismatches reported.
132 bool "Kernel debugging"
134 Say Y here if you are developing drivers or trying to debug and
135 identify kernel problems.
138 bool "Debug shared IRQ handlers"
139 depends on DEBUG_KERNEL && GENERIC_HARDIRQS
141 Enable this to generate a spurious interrupt as soon as a shared
142 interrupt handler is registered, and just before one is deregistered.
143 Drivers ought to be able to handle interrupts coming in at those
144 points; some don't and need to be caught.
146 config DETECT_SOFTLOCKUP
147 bool "Detect Soft Lockups"
148 depends on DEBUG_KERNEL && !S390
151 Say Y here to enable the kernel to detect "soft lockups",
152 which are bugs that cause the kernel to loop in kernel
153 mode for more than 60 seconds, without giving other tasks a
156 When a soft-lockup is detected, the kernel will print the
157 current stack trace (which you should report), but the
158 system will stay locked up. This feature has negligible
161 (Note that "hard lockups" are separate type of bugs that
162 can be detected via the NMI-watchdog, on platforms that
165 config BOOTPARAM_SOFTLOCKUP_PANIC
166 bool "Panic (Reboot) On Soft Lockups"
167 depends on DETECT_SOFTLOCKUP
169 Say Y here to enable the kernel to panic on "soft lockups",
170 which are bugs that cause the kernel to loop in kernel
171 mode for more than 60 seconds, without giving other tasks a
174 The panic can be used in combination with panic_timeout,
175 to cause the system to reboot automatically after a
176 lockup has been detected. This feature is useful for
177 high-availability systems that have uptime guarantees and
178 where a lockup must be resolved ASAP.
182 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
184 depends on DETECT_SOFTLOCKUP
186 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
187 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
189 config DETECT_HUNG_TASK
190 bool "Detect Hung Tasks"
191 depends on DEBUG_KERNEL
192 default DETECT_SOFTLOCKUP
194 Say Y here to enable the kernel to detect "hung tasks",
195 which are bugs that cause the task to be stuck in
196 uninterruptible "D" state indefinitiley.
198 When a hung task is detected, the kernel will print the
199 current stack trace (which you should report), but the
200 task will stay in uninterruptible state. If lockdep is
201 enabled then all held locks will also be reported. This
202 feature has negligible overhead.
204 config BOOTPARAM_HUNG_TASK_PANIC
205 bool "Panic (Reboot) On Hung Tasks"
206 depends on DETECT_HUNG_TASK
208 Say Y here to enable the kernel to panic on "hung tasks",
209 which are bugs that cause the kernel to leave a task stuck
210 in uninterruptible "D" state.
212 The panic can be used in combination with panic_timeout,
213 to cause the system to reboot automatically after a
214 hung task has been detected. This feature is useful for
215 high-availability systems that have uptime guarantees and
216 where a hung tasks must be resolved ASAP.
220 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
222 depends on DETECT_HUNG_TASK
224 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
225 default 1 if BOOTPARAM_HUNG_TASK_PANIC
228 bool "Collect scheduler debugging info"
229 depends on DEBUG_KERNEL && PROC_FS
232 If you say Y here, the /proc/sched_debug file will be provided
233 that can help debug the scheduler. The runtime overhead of this
237 bool "Collect scheduler statistics"
238 depends on DEBUG_KERNEL && PROC_FS
240 If you say Y here, additional code will be inserted into the
241 scheduler and related routines to collect statistics about
242 scheduler behavior and provide them in /proc/schedstat. These
243 stats may be useful for both tuning and debugging the scheduler
244 If you aren't debugging the scheduler or trying to tune a specific
245 application, you can say N to avoid the very slight overhead
249 bool "Collect kernel timers statistics"
250 depends on DEBUG_KERNEL && PROC_FS
252 If you say Y here, additional code will be inserted into the
253 timer routines to collect statistics about kernel timers being
254 reprogrammed. The statistics can be read from /proc/timer_stats.
255 The statistics collection is started by writing 1 to /proc/timer_stats,
256 writing 0 stops it. This feature is useful to collect information
257 about timer usage patterns in kernel and userspace. This feature
258 is lightweight if enabled in the kernel config but not activated
259 (it defaults to deactivated on bootup and will only be activated
260 if some application like powertop activates it explicitly).
263 bool "Debug object operations"
264 depends on DEBUG_KERNEL
266 If you say Y here, additional code will be inserted into the
267 kernel to track the life time of various objects and validate
268 the operations on those objects.
270 config DEBUG_OBJECTS_SELFTEST
271 bool "Debug objects selftest"
272 depends on DEBUG_OBJECTS
274 This enables the selftest of the object debug code.
276 config DEBUG_OBJECTS_FREE
277 bool "Debug objects in freed memory"
278 depends on DEBUG_OBJECTS
280 This enables checks whether a k/v free operation frees an area
281 which contains an object which has not been deactivated
282 properly. This can make kmalloc/kfree-intensive workloads
285 config DEBUG_OBJECTS_TIMERS
286 bool "Debug timer objects"
287 depends on DEBUG_OBJECTS
289 If you say Y here, additional code will be inserted into the
290 timer routines to track the life time of timer objects and
291 validate the timer operations.
293 config DEBUG_OBJECTS_ENABLE_DEFAULT
294 int "debug_objects bootup default value (0-1)"
297 depends on DEBUG_OBJECTS
299 Debug objects boot parameter default value
302 bool "Debug slab memory allocations"
303 depends on DEBUG_KERNEL && SLAB
305 Say Y here to have the kernel do limited verification on memory
306 allocation as well as poisoning memory on free to catch use of freed
307 memory. This can make kmalloc/kfree-intensive workloads much slower.
309 config DEBUG_SLAB_LEAK
310 bool "Memory leak debugging"
311 depends on DEBUG_SLAB
314 bool "SLUB debugging on by default"
315 depends on SLUB && SLUB_DEBUG
318 Boot with debugging on by default. SLUB boots by default with
319 the runtime debug capabilities switched off. Enabling this is
320 equivalent to specifying the "slub_debug" parameter on boot.
321 There is no support for more fine grained debug control like
322 possible with slub_debug=xxx. SLUB debugging may be switched
323 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
328 bool "Enable SLUB performance statistics"
329 depends on SLUB && SLUB_DEBUG && SYSFS
331 SLUB statistics are useful to debug SLUBs allocation behavior in
332 order find ways to optimize the allocator. This should never be
333 enabled for production use since keeping statistics slows down
334 the allocator by a few percentage points. The slabinfo command
335 supports the determination of the most active slabs to figure
336 out which slabs are relevant to a particular load.
337 Try running: slabinfo -DA
339 config DEBUG_KMEMLEAK
340 bool "Kernel memory leak detector"
341 depends on DEBUG_KERNEL && EXPERIMENTAL && (X86 || ARM) && \
343 select DEBUG_SLAB if SLAB
344 select SLUB_DEBUG if SLUB
345 select DEBUG_FS if SYSFS
346 select STACKTRACE if STACKTRACE_SUPPORT
349 Say Y here if you want to enable the memory leak
350 detector. The memory allocation/freeing is traced in a way
351 similar to the Boehm's conservative garbage collector, the
352 difference being that the orphan objects are not freed but
353 only shown in /sys/kernel/debug/kmemleak. Enabling this
354 feature will introduce an overhead to memory
355 allocations. See Documentation/kmemleak.txt for more
358 In order to access the kmemleak file, debugfs needs to be
359 mounted (usually at /sys/kernel/debug).
362 bool "Debug preemptible kernel"
363 depends on DEBUG_KERNEL && PREEMPT && (TRACE_IRQFLAGS_SUPPORT || PPC64)
366 If you say Y here then the kernel will use a debug variant of the
367 commonly used smp_processor_id() function and will print warnings
368 if kernel code uses it in a preemption-unsafe way. Also, the kernel
369 will detect preemption count underflows.
371 config DEBUG_RT_MUTEXES
372 bool "RT Mutex debugging, deadlock detection"
373 depends on DEBUG_KERNEL && RT_MUTEXES
375 This allows rt mutex semantics violations and rt mutex related
376 deadlocks (lockups) to be detected and reported automatically.
381 depends on DEBUG_RT_MUTEXES
383 config RT_MUTEX_TESTER
384 bool "Built-in scriptable tester for rt-mutexes"
385 depends on DEBUG_KERNEL && RT_MUTEXES
387 This option enables a rt-mutex tester.
389 config DEBUG_SPINLOCK
390 bool "Spinlock and rw-lock debugging: basic checks"
391 depends on DEBUG_KERNEL
393 Say Y here and build SMP to catch missing spinlock initialization
394 and certain other kinds of spinlock errors commonly made. This is
395 best used in conjunction with the NMI watchdog so that spinlock
396 deadlocks are also debuggable.
399 bool "Mutex debugging: basic checks"
400 depends on DEBUG_KERNEL
402 This feature allows mutex semantics violations to be detected and
405 config DEBUG_LOCK_ALLOC
406 bool "Lock debugging: detect incorrect freeing of live locks"
407 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
408 select DEBUG_SPINLOCK
412 This feature will check whether any held lock (spinlock, rwlock,
413 mutex or rwsem) is incorrectly freed by the kernel, via any of the
414 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
415 vfree(), etc.), whether a live lock is incorrectly reinitialized via
416 spin_lock_init()/mutex_init()/etc., or whether there is any lock
417 held during task exit.
420 bool "Lock debugging: prove locking correctness"
421 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
423 select DEBUG_SPINLOCK
425 select DEBUG_LOCK_ALLOC
428 This feature enables the kernel to prove that all locking
429 that occurs in the kernel runtime is mathematically
430 correct: that under no circumstance could an arbitrary (and
431 not yet triggered) combination of observed locking
432 sequences (on an arbitrary number of CPUs, running an
433 arbitrary number of tasks and interrupt contexts) cause a
436 In short, this feature enables the kernel to report locking
437 related deadlocks before they actually occur.
439 The proof does not depend on how hard and complex a
440 deadlock scenario would be to trigger: how many
441 participant CPUs, tasks and irq-contexts would be needed
442 for it to trigger. The proof also does not depend on
443 timing: if a race and a resulting deadlock is possible
444 theoretically (no matter how unlikely the race scenario
445 is), it will be proven so and will immediately be
446 reported by the kernel (once the event is observed that
447 makes the deadlock theoretically possible).
449 If a deadlock is impossible (i.e. the locking rules, as
450 observed by the kernel, are mathematically correct), the
451 kernel reports nothing.
453 NOTE: this feature can also be enabled for rwlocks, mutexes
454 and rwsems - in which case all dependencies between these
455 different locking variants are observed and mapped too, and
456 the proof of observed correctness is also maintained for an
457 arbitrary combination of these separate locking variants.
459 For more details, see Documentation/lockdep-design.txt.
463 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
465 select FRAME_POINTER if !X86 && !MIPS && !PPC && !ARM_UNWIND && !S390
470 bool "Lock usage statistics"
471 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
473 select DEBUG_SPINLOCK
475 select DEBUG_LOCK_ALLOC
478 This feature enables tracking lock contention points
480 For more details, see Documentation/lockstat.txt
483 bool "Lock dependency engine debugging"
484 depends on DEBUG_KERNEL && LOCKDEP
486 If you say Y here, the lock dependency engine will do
487 additional runtime checks to debug itself, at the price
488 of more runtime overhead.
490 config TRACE_IRQFLAGS
491 depends on DEBUG_KERNEL
494 depends on TRACE_IRQFLAGS_SUPPORT
495 depends on PROVE_LOCKING
497 config DEBUG_SPINLOCK_SLEEP
498 bool "Spinlock debugging: sleep-inside-spinlock checking"
499 depends on DEBUG_KERNEL
501 If you say Y here, various routines which may sleep will become very
502 noisy if they are called with a spinlock held.
504 config DEBUG_LOCKING_API_SELFTESTS
505 bool "Locking API boot-time self-tests"
506 depends on DEBUG_KERNEL
508 Say Y here if you want the kernel to run a short self-test during
509 bootup. The self-test checks whether common types of locking bugs
510 are detected by debugging mechanisms or not. (if you disable
511 lock debugging then those bugs wont be detected of course.)
512 The following locking APIs are covered: spinlocks, rwlocks,
517 depends on STACKTRACE_SUPPORT
520 bool "kobject debugging"
521 depends on DEBUG_KERNEL
523 If you say Y here, some extra kobject debugging messages will be sent
527 bool "Highmem debugging"
528 depends on DEBUG_KERNEL && HIGHMEM
530 This options enables addition error checking for high memory systems.
531 Disable for production systems.
533 config DEBUG_BUGVERBOSE
534 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
536 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
537 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
540 Say Y here to make BUG() panics output the file name and line number
541 of the BUG call as well as the EIP and oops trace. This aids
542 debugging but costs about 70-100K of memory.
545 bool "Compile the kernel with debug info"
546 depends on DEBUG_KERNEL
548 If you say Y here the resulting kernel image will include
549 debugging info resulting in a larger kernel image.
550 This adds debug symbols to the kernel and modules (gcc -g), and
551 is needed if you intend to use kernel crashdump or binary object
552 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
553 Say Y here only if you plan to debug the kernel.
559 depends on DEBUG_KERNEL
561 Enable this to turn on extended checks in the virtual-memory system
562 that may impact performance.
567 bool "Debug VM translations"
568 depends on DEBUG_KERNEL && X86
570 Enable some costly sanity checks in virtual to page code. This can
571 catch mistakes with virt_to_page() and friends.
575 config DEBUG_NOMMU_REGIONS
576 bool "Debug the global anon/private NOMMU mapping region tree"
577 depends on DEBUG_KERNEL && !MMU
579 This option causes the global tree of anonymous and private mapping
580 regions to be regularly checked for invalid topology.
582 config DEBUG_WRITECOUNT
583 bool "Debug filesystem writers count"
584 depends on DEBUG_KERNEL
586 Enable this to catch wrong use of the writers count in struct
587 vfsmount. This will increase the size of each file struct by
592 config DEBUG_MEMORY_INIT
593 bool "Debug memory initialisation" if EMBEDDED
596 Enable this for additional checks during memory initialisation.
597 The sanity checks verify aspects of the VM such as the memory model
598 and other information provided by the architecture. Verbose
599 information will be printed at KERN_DEBUG loglevel depending
600 on the mminit_loglevel= command-line option.
605 bool "Debug linked list manipulation"
606 depends on DEBUG_KERNEL
608 Enable this to turn on extended checks in the linked-list
614 bool "Debug SG table operations"
615 depends on DEBUG_KERNEL
617 Enable this to turn on checks on scatter-gather tables. This can
618 help find problems with drivers that do not properly initialize
623 config DEBUG_NOTIFIERS
624 bool "Debug notifier call chains"
625 depends on DEBUG_KERNEL
627 Enable this to turn on sanity checking for notifier call chains.
628 This is most useful for kernel developers to make sure that
629 modules properly unregister themselves from notifier chains.
630 This is a relatively cheap check but if you care about maximum
634 # Select this config option from the architecture Kconfig, if it
635 # it is preferred to always offer frame pointers as a config
636 # option on the architecture (regardless of KERNEL_DEBUG):
638 config ARCH_WANT_FRAME_POINTERS
643 bool "Compile the kernel with frame pointers"
644 depends on DEBUG_KERNEL && \
645 (CRIS || M68K || M68KNOMMU || FRV || UML || \
646 AVR32 || SUPERH || BLACKFIN || MN10300) || \
647 ARCH_WANT_FRAME_POINTERS
648 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
650 If you say Y here the resulting kernel image will be slightly
651 larger and slower, but it gives very useful debugging information
652 in case of kernel bugs. (precise oopses/stacktraces/warnings)
654 config BOOT_PRINTK_DELAY
655 bool "Delay each boot printk message by N milliseconds"
656 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
658 This build option allows you to read kernel boot messages
659 by inserting a short delay after each one. The delay is
660 specified in milliseconds on the kernel command line,
661 using "boot_delay=N".
663 It is likely that you would also need to use "lpj=M" to preset
664 the "loops per jiffie" value.
665 See a previous boot log for the "lpj" value to use for your
666 system, and then set "lpj=M" before setting "boot_delay=N".
667 NOTE: Using this option may adversely affect SMP systems.
668 I.e., processors other than the first one may not boot up.
669 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
670 what it believes to be lockup conditions.
672 config RCU_TORTURE_TEST
673 tristate "torture tests for RCU"
674 depends on DEBUG_KERNEL
677 This option provides a kernel module that runs torture tests
678 on the RCU infrastructure. The kernel module may be built
679 after the fact on the running kernel to be tested, if desired.
681 Say Y here if you want RCU torture tests to be built into
683 Say M if you want the RCU torture tests to build as a module.
684 Say N if you are unsure.
686 config RCU_TORTURE_TEST_RUNNABLE
687 bool "torture tests for RCU runnable by default"
688 depends on RCU_TORTURE_TEST = y
691 This option provides a way to build the RCU torture tests
692 directly into the kernel without them starting up at boot
693 time. You can use /proc/sys/kernel/rcutorture_runnable
694 to manually override this setting. This /proc file is
695 available only when the RCU torture tests have been built
698 Say Y here if you want the RCU torture tests to start during
699 boot (you probably don't).
700 Say N here if you want the RCU torture tests to start only
701 after being manually enabled via /proc.
703 config RCU_CPU_STALL_DETECTOR
704 bool "Check for stalled CPUs delaying RCU grace periods"
705 depends on CLASSIC_RCU || TREE_RCU
708 This option causes RCU to printk information on which
709 CPUs are delaying the current grace period, but only when
710 the grace period extends for excessive time periods.
712 Say Y if you want RCU to perform such checks.
714 Say N if you are unsure.
716 config KPROBES_SANITY_TEST
717 bool "Kprobes sanity tests"
718 depends on DEBUG_KERNEL
722 This option provides for testing basic kprobes functionality on
723 boot. A sample kprobe, jprobe and kretprobe are inserted and
724 verified for functionality.
726 Say N if you are unsure.
728 config BACKTRACE_SELF_TEST
729 tristate "Self test for the backtrace code"
730 depends on DEBUG_KERNEL
733 This option provides a kernel module that can be used to test
734 the kernel stack backtrace code. This option is not useful
735 for distributions or general kernels, but only for kernel
736 developers working on architecture code.
738 Note that if you want to also test saved backtraces, you will
739 have to enable STACKTRACE as well.
741 Say N if you are unsure.
743 config DEBUG_BLOCK_EXT_DEVT
744 bool "Force extended block device numbers and spread them"
745 depends on DEBUG_KERNEL
749 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
750 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
751 YOU ARE DOING. Distros, please enable this and fix whatever
754 Conventionally, block device numbers are allocated from
755 predetermined contiguous area. However, extended block area
756 may introduce non-contiguous block device numbers. This
757 option forces most block device numbers to be allocated from
758 the extended space and spreads them to discover kernel or
759 userland code paths which assume predetermined contiguous
760 device number allocation.
762 Note that turning on this debug option shuffles all the
763 device numbers for all IDE and SCSI devices including libata
764 ones, so root partition specified using device number
765 directly (via rdev or root=MAJ:MIN) won't work anymore.
766 Textual device names (root=/dev/sdXn) will continue to work.
768 Say N if you are unsure.
771 tristate "Linux Kernel Dump Test Tool Module"
772 depends on DEBUG_KERNEL
777 This module enables testing of the different dumping mechanisms by
778 inducing system failures at predefined crash points.
779 If you don't need it: say N
780 Choose M here to compile this code as a module. The module will be
783 Documentation on how to use the module can be found in
786 config FAULT_INJECTION
787 bool "Fault-injection framework"
788 depends on DEBUG_KERNEL
790 Provide fault-injection framework.
791 For more details, see Documentation/fault-injection/.
794 bool "Fault-injection capability for kmalloc"
795 depends on FAULT_INJECTION
796 depends on SLAB || SLUB
798 Provide fault-injection capability for kmalloc.
800 config FAIL_PAGE_ALLOC
801 bool "Fault-injection capabilitiy for alloc_pages()"
802 depends on FAULT_INJECTION
804 Provide fault-injection capability for alloc_pages().
806 config FAIL_MAKE_REQUEST
807 bool "Fault-injection capability for disk IO"
808 depends on FAULT_INJECTION && BLOCK
810 Provide fault-injection capability for disk IO.
812 config FAIL_IO_TIMEOUT
813 bool "Faul-injection capability for faking disk interrupts"
814 depends on FAULT_INJECTION && BLOCK
816 Provide fault-injection capability on end IO handling. This
817 will make the block layer "forget" an interrupt as configured,
818 thus exercising the error handling.
820 Only works with drivers that use the generic timeout handling,
821 for others it wont do anything.
823 config FAULT_INJECTION_DEBUG_FS
824 bool "Debugfs entries for fault-injection capabilities"
825 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
827 Enable configuration of fault-injection capabilities via debugfs.
829 config FAULT_INJECTION_STACKTRACE_FILTER
830 bool "stacktrace filter for fault-injection capabilities"
831 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
834 select FRAME_POINTER if !PPC && !S390
836 Provide stacktrace filter for fault-injection capabilities
839 bool "Latency measuring infrastructure"
840 select FRAME_POINTER if !MIPS && !PPC && !S390
846 depends on HAVE_LATENCYTOP_SUPPORT
848 Enable this option if you want to use the LatencyTOP tool
849 to find out which userspace is blocking on what kernel operations.
851 config SYSCTL_SYSCALL_CHECK
853 depends on SYSCTL_SYSCALL
855 sys_sysctl uses binary paths that have been found challenging
856 to properly maintain and use. This enables checks that help
857 you to keep things correct.
859 source mm/Kconfig.debug
860 source kernel/trace/Kconfig
862 config PROVIDE_OHCI1394_DMA_INIT
863 bool "Remote debugging over FireWire early on boot"
864 depends on PCI && X86
866 If you want to debug problems which hang or crash the kernel early
867 on boot and the crashing machine has a FireWire port, you can use
868 this feature to remotely access the memory of the crashed machine
869 over FireWire. This employs remote DMA as part of the OHCI1394
870 specification which is now the standard for FireWire controllers.
872 With remote DMA, you can monitor the printk buffer remotely using
873 firescope and access all memory below 4GB using fireproxy from gdb.
874 Even controlling a kernel debugger is possible using remote DMA.
878 If ohci1394_dma=early is used as boot parameter, it will initialize
879 all OHCI1394 controllers which are found in the PCI config space.
881 As all changes to the FireWire bus such as enabling and disabling
882 devices cause a bus reset and thereby disable remote DMA for all
883 devices, be sure to have the cable plugged and FireWire enabled on
884 the debugging host before booting the debug target for debugging.
886 This code (~1k) is freed after boot. By then, the firewire stack
887 in charge of the OHCI-1394 controllers should be used instead.
889 See Documentation/debugging-via-ohci1394.txt for more information.
891 config FIREWIRE_OHCI_REMOTE_DMA
892 bool "Remote debugging over FireWire with firewire-ohci"
893 depends on FIREWIRE_OHCI
895 This option lets you use the FireWire bus for remote debugging
896 with help of the firewire-ohci driver. It enables unfiltered
897 remote DMA in firewire-ohci.
898 See Documentation/debugging-via-ohci1394.txt for more information.
903 bool "Build targets in Documentation/ tree"
904 depends on HEADERS_CHECK
906 This option attempts to build objects from the source files in the
907 kernel Documentation/ tree.
909 Say N if you are unsure.
912 bool "Enable dynamic printk() support"
918 Compiles debug level messages into the kernel, which would not
919 otherwise be available at runtime. These messages can then be
920 enabled/disabled based on various levels of scope - per source file,
921 function, module, format string, and line number. This mechanism
922 implicitly enables all pr_debug() and dev_dbg() calls. The impact of
923 this compile option is a larger kernel text size of about 2%.
927 Dynamic debugging is controlled via the 'dynamic_debug/ddebug' file,
928 which is contained in the 'debugfs' filesystem. Thus, the debugfs
929 filesystem must first be mounted before making use of this feature.
930 We refer the control file as: <debugfs>/dynamic_debug/ddebug. This
931 file contains a list of the debug statements that can be enabled. The
932 format for each line of the file is:
934 filename:lineno [module]function flags format
936 filename : source file of the debug statement
937 lineno : line number of the debug statement
938 module : module that contains the debug statement
939 function : function that contains the debug statement
940 flags : 'p' means the line is turned 'on' for printing
941 format : the format used for the debug statement
945 nullarbor:~ # cat <debugfs>/dynamic_debug/ddebug
946 # filename:lineno [module]function flags format
947 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
948 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
949 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
953 // enable the message at line 1603 of file svcsock.c
954 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
955 <debugfs>/dynamic_debug/ddebug
957 // enable all the messages in file svcsock.c
958 nullarbor:~ # echo -n 'file svcsock.c +p' >
959 <debugfs>/dynamic_debug/ddebug
961 // enable all the messages in the NFS server module
962 nullarbor:~ # echo -n 'module nfsd +p' >
963 <debugfs>/dynamic_debug/ddebug
965 // enable all 12 messages in the function svc_process()
966 nullarbor:~ # echo -n 'func svc_process +p' >
967 <debugfs>/dynamic_debug/ddebug
969 // disable all 12 messages in the function svc_process()
970 nullarbor:~ # echo -n 'func svc_process -p' >
971 <debugfs>/dynamic_debug/ddebug
973 See Documentation/dynamic-debug-howto.txt for additional information.
976 bool "Enable debugging of DMA-API usage"
977 depends on HAVE_DMA_API_DEBUG
979 Enable this option to debug the use of the DMA API by device drivers.
980 With this option you will be able to detect common bugs in device
981 drivers like double-freeing of DMA mappings or freeing mappings that
982 were never allocated.
983 This option causes a performance degredation. Use only if you want
984 to debug device drivers. If unsure, say N.
986 source "samples/Kconfig"
988 source "lib/Kconfig.kgdb"