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
80 bool "Run 'make headers_check' when building vmlinux"
83 This option will extract the user-visible kernel headers whenever
84 building the kernel, and will run basic sanity checks on them to
85 ensure that exported files do not attempt to include files which
86 were not exported, etc.
88 If you're making modifications to header files which are
89 relevant for userspace, say 'Y', and check the headers
90 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
91 your build tree), to make sure they're suitable.
93 config DEBUG_SECTION_MISMATCH
94 bool "Enable full Section mismatch analysis"
96 # This option is on purpose disabled for now.
97 # It will be enabled when we are down to a resonable number
98 # of section mismatch warnings (< 10 for an allyesconfig build)
100 The section mismatch analysis checks if there are illegal
101 references from one section to another section.
102 Linux will during link or during runtime drop some sections
103 and any use of code/data previously in these sections will
104 most likely result in an oops.
105 In the code functions and variables are annotated with
106 __init, __devinit etc. (see full list in include/linux/init.h)
107 which results in the code/data being placed in specific sections.
108 The section mismatch analysis is always done after a full
109 kernel build but enabling this option will in addition
111 - Add the option -fno-inline-functions-called-once to gcc
112 When inlining a function annotated __init in a non-init
113 function we would lose the section information and thus
114 the analysis would not catch the illegal reference.
115 This option tells gcc to inline less but will also
116 result in a larger kernel.
117 - Run the section mismatch analysis for each module/built-in.o
118 When we run the section mismatch analysis on vmlinux.o we
119 lose valueble information about where the mismatch was
121 Running the analysis for each module/built-in.o file
122 will tell where the mismatch happens much closer to the
123 source. The drawback is that we will report the same
124 mismatch at least twice.
125 - Enable verbose reporting from modpost to help solving
126 the section mismatches reported.
129 bool "Kernel debugging"
131 Say Y here if you are developing drivers or trying to debug and
132 identify kernel problems.
135 bool "Debug shared IRQ handlers"
136 depends on DEBUG_KERNEL && GENERIC_HARDIRQS
138 Enable this to generate a spurious interrupt as soon as a shared
139 interrupt handler is registered, and just before one is deregistered.
140 Drivers ought to be able to handle interrupts coming in at those
141 points; some don't and need to be caught.
143 config DETECT_SOFTLOCKUP
144 bool "Detect Soft Lockups"
145 depends on DEBUG_KERNEL && !S390
148 Say Y here to enable the kernel to detect "soft lockups",
149 which are bugs that cause the kernel to loop in kernel
150 mode for more than 60 seconds, without giving other tasks a
153 When a soft-lockup is detected, the kernel will print the
154 current stack trace (which you should report), but the
155 system will stay locked up. This feature has negligible
158 (Note that "hard lockups" are separate type of bugs that
159 can be detected via the NMI-watchdog, on platforms that
162 config BOOTPARAM_SOFTLOCKUP_PANIC
163 bool "Panic (Reboot) On Soft Lockups"
164 depends on DETECT_SOFTLOCKUP
166 Say Y here to enable the kernel to panic on "soft lockups",
167 which are bugs that cause the kernel to loop in kernel
168 mode for more than 60 seconds, without giving other tasks a
171 The panic can be used in combination with panic_timeout,
172 to cause the system to reboot automatically after a
173 lockup has been detected. This feature is useful for
174 high-availability systems that have uptime guarantees and
175 where a lockup must be resolved ASAP.
179 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
181 depends on DETECT_SOFTLOCKUP
183 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
184 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
187 bool "Collect scheduler debugging info"
188 depends on DEBUG_KERNEL && PROC_FS
191 If you say Y here, the /proc/sched_debug file will be provided
192 that can help debug the scheduler. The runtime overhead of this
196 bool "Collect scheduler statistics"
197 depends on DEBUG_KERNEL && PROC_FS
199 If you say Y here, additional code will be inserted into the
200 scheduler and related routines to collect statistics about
201 scheduler behavior and provide them in /proc/schedstat. These
202 stats may be useful for both tuning and debugging the scheduler
203 If you aren't debugging the scheduler or trying to tune a specific
204 application, you can say N to avoid the very slight overhead
208 bool "Collect kernel timers statistics"
209 depends on DEBUG_KERNEL && PROC_FS
211 If you say Y here, additional code will be inserted into the
212 timer routines to collect statistics about kernel timers being
213 reprogrammed. The statistics can be read from /proc/timer_stats.
214 The statistics collection is started by writing 1 to /proc/timer_stats,
215 writing 0 stops it. This feature is useful to collect information
216 about timer usage patterns in kernel and userspace. This feature
217 is lightweight if enabled in the kernel config but not activated
218 (it defaults to deactivated on bootup and will only be activated
219 if some application like powertop activates it explicitly).
222 bool "Debug object operations"
223 depends on DEBUG_KERNEL
225 If you say Y here, additional code will be inserted into the
226 kernel to track the life time of various objects and validate
227 the operations on those objects.
229 config DEBUG_OBJECTS_SELFTEST
230 bool "Debug objects selftest"
231 depends on DEBUG_OBJECTS
233 This enables the selftest of the object debug code.
235 config DEBUG_OBJECTS_FREE
236 bool "Debug objects in freed memory"
237 depends on DEBUG_OBJECTS
239 This enables checks whether a k/v free operation frees an area
240 which contains an object which has not been deactivated
241 properly. This can make kmalloc/kfree-intensive workloads
244 config DEBUG_OBJECTS_TIMERS
245 bool "Debug timer objects"
246 depends on DEBUG_OBJECTS
248 If you say Y here, additional code will be inserted into the
249 timer routines to track the life time of timer objects and
250 validate the timer operations.
253 bool "Debug slab memory allocations"
254 depends on DEBUG_KERNEL && SLAB
256 Say Y here to have the kernel do limited verification on memory
257 allocation as well as poisoning memory on free to catch use of freed
258 memory. This can make kmalloc/kfree-intensive workloads much slower.
260 config DEBUG_SLAB_LEAK
261 bool "Memory leak debugging"
262 depends on DEBUG_SLAB
265 bool "SLUB debugging on by default"
266 depends on SLUB && SLUB_DEBUG
269 Boot with debugging on by default. SLUB boots by default with
270 the runtime debug capabilities switched off. Enabling this is
271 equivalent to specifying the "slub_debug" parameter on boot.
272 There is no support for more fine grained debug control like
273 possible with slub_debug=xxx. SLUB debugging may be switched
274 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
279 bool "Enable SLUB performance statistics"
280 depends on SLUB && SLUB_DEBUG && SYSFS
282 SLUB statistics are useful to debug SLUBs allocation behavior in
283 order find ways to optimize the allocator. This should never be
284 enabled for production use since keeping statistics slows down
285 the allocator by a few percentage points. The slabinfo command
286 supports the determination of the most active slabs to figure
287 out which slabs are relevant to a particular load.
288 Try running: slabinfo -DA
291 bool "Debug preemptible kernel"
292 depends on DEBUG_KERNEL && PREEMPT && (TRACE_IRQFLAGS_SUPPORT || PPC64)
295 If you say Y here then the kernel will use a debug variant of the
296 commonly used smp_processor_id() function and will print warnings
297 if kernel code uses it in a preemption-unsafe way. Also, the kernel
298 will detect preemption count underflows.
300 config DEBUG_RT_MUTEXES
301 bool "RT Mutex debugging, deadlock detection"
302 depends on DEBUG_KERNEL && RT_MUTEXES
304 This allows rt mutex semantics violations and rt mutex related
305 deadlocks (lockups) to be detected and reported automatically.
310 depends on DEBUG_RT_MUTEXES
312 config RT_MUTEX_TESTER
313 bool "Built-in scriptable tester for rt-mutexes"
314 depends on DEBUG_KERNEL && RT_MUTEXES
316 This option enables a rt-mutex tester.
318 config DEBUG_SPINLOCK
319 bool "Spinlock and rw-lock debugging: basic checks"
320 depends on DEBUG_KERNEL
322 Say Y here and build SMP to catch missing spinlock initialization
323 and certain other kinds of spinlock errors commonly made. This is
324 best used in conjunction with the NMI watchdog so that spinlock
325 deadlocks are also debuggable.
328 bool "Mutex debugging: basic checks"
329 depends on DEBUG_KERNEL
331 This feature allows mutex semantics violations to be detected and
334 config DEBUG_LOCK_ALLOC
335 bool "Lock debugging: detect incorrect freeing of live locks"
336 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
337 select DEBUG_SPINLOCK
341 This feature will check whether any held lock (spinlock, rwlock,
342 mutex or rwsem) is incorrectly freed by the kernel, via any of the
343 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
344 vfree(), etc.), whether a live lock is incorrectly reinitialized via
345 spin_lock_init()/mutex_init()/etc., or whether there is any lock
346 held during task exit.
349 bool "Lock debugging: prove locking correctness"
350 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
352 select DEBUG_SPINLOCK
354 select DEBUG_LOCK_ALLOC
357 This feature enables the kernel to prove that all locking
358 that occurs in the kernel runtime is mathematically
359 correct: that under no circumstance could an arbitrary (and
360 not yet triggered) combination of observed locking
361 sequences (on an arbitrary number of CPUs, running an
362 arbitrary number of tasks and interrupt contexts) cause a
365 In short, this feature enables the kernel to report locking
366 related deadlocks before they actually occur.
368 The proof does not depend on how hard and complex a
369 deadlock scenario would be to trigger: how many
370 participant CPUs, tasks and irq-contexts would be needed
371 for it to trigger. The proof also does not depend on
372 timing: if a race and a resulting deadlock is possible
373 theoretically (no matter how unlikely the race scenario
374 is), it will be proven so and will immediately be
375 reported by the kernel (once the event is observed that
376 makes the deadlock theoretically possible).
378 If a deadlock is impossible (i.e. the locking rules, as
379 observed by the kernel, are mathematically correct), the
380 kernel reports nothing.
382 NOTE: this feature can also be enabled for rwlocks, mutexes
383 and rwsems - in which case all dependencies between these
384 different locking variants are observed and mapped too, and
385 the proof of observed correctness is also maintained for an
386 arbitrary combination of these separate locking variants.
388 For more details, see Documentation/lockdep-design.txt.
392 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
394 select FRAME_POINTER if !X86 && !MIPS
399 bool "Lock usage statistics"
400 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
402 select DEBUG_SPINLOCK
404 select DEBUG_LOCK_ALLOC
407 This feature enables tracking lock contention points
409 For more details, see Documentation/lockstat.txt
412 bool "Lock dependency engine debugging"
413 depends on DEBUG_KERNEL && LOCKDEP
415 If you say Y here, the lock dependency engine will do
416 additional runtime checks to debug itself, at the price
417 of more runtime overhead.
419 config TRACE_IRQFLAGS
420 depends on DEBUG_KERNEL
423 depends on TRACE_IRQFLAGS_SUPPORT
424 depends on PROVE_LOCKING
426 config DEBUG_SPINLOCK_SLEEP
427 bool "Spinlock debugging: sleep-inside-spinlock checking"
428 depends on DEBUG_KERNEL
430 If you say Y here, various routines which may sleep will become very
431 noisy if they are called with a spinlock held.
433 config DEBUG_LOCKING_API_SELFTESTS
434 bool "Locking API boot-time self-tests"
435 depends on DEBUG_KERNEL
437 Say Y here if you want the kernel to run a short self-test during
438 bootup. The self-test checks whether common types of locking bugs
439 are detected by debugging mechanisms or not. (if you disable
440 lock debugging then those bugs wont be detected of course.)
441 The following locking APIs are covered: spinlocks, rwlocks,
446 depends on STACKTRACE_SUPPORT
449 bool "kobject debugging"
450 depends on DEBUG_KERNEL
452 If you say Y here, some extra kobject debugging messages will be sent
456 bool "Highmem debugging"
457 depends on DEBUG_KERNEL && HIGHMEM
459 This options enables addition error checking for high memory systems.
460 Disable for production systems.
462 config DEBUG_BUGVERBOSE
463 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
465 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
466 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
469 Say Y here to make BUG() panics output the file name and line number
470 of the BUG call as well as the EIP and oops trace. This aids
471 debugging but costs about 70-100K of memory.
474 bool "Compile the kernel with debug info"
475 depends on DEBUG_KERNEL
477 If you say Y here the resulting kernel image will include
478 debugging info resulting in a larger kernel image.
479 This adds debug symbols to the kernel and modules (gcc -g), and
480 is needed if you intend to use kernel crashdump or binary object
481 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
482 Say Y here only if you plan to debug the kernel.
488 depends on DEBUG_KERNEL
490 Enable this to turn on extended checks in the virtual-memory system
491 that may impact performance.
495 config DEBUG_WRITECOUNT
496 bool "Debug filesystem writers count"
497 depends on DEBUG_KERNEL
499 Enable this to catch wrong use of the writers count in struct
500 vfsmount. This will increase the size of each file struct by
506 bool "Debug linked list manipulation"
507 depends on DEBUG_KERNEL
509 Enable this to turn on extended checks in the linked-list
515 bool "Debug SG table operations"
516 depends on DEBUG_KERNEL
518 Enable this to turn on checks on scatter-gather tables. This can
519 help find problems with drivers that do not properly initialize
525 bool "Compile the kernel with frame pointers"
526 depends on DEBUG_KERNEL && \
527 (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || \
528 AVR32 || SUPERH || BLACKFIN || MN10300)
529 default y if DEBUG_INFO && UML
531 If you say Y here the resulting kernel image will be slightly larger
532 and slower, but it might give very useful debugging information on
533 some architectures or if you use external debuggers.
534 If you don't debug the kernel, you can say N.
536 config BOOT_PRINTK_DELAY
537 bool "Delay each boot printk message by N milliseconds"
538 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
540 This build option allows you to read kernel boot messages
541 by inserting a short delay after each one. The delay is
542 specified in milliseconds on the kernel command line,
543 using "boot_delay=N".
545 It is likely that you would also need to use "lpj=M" to preset
546 the "loops per jiffie" value.
547 See a previous boot log for the "lpj" value to use for your
548 system, and then set "lpj=M" before setting "boot_delay=N".
549 NOTE: Using this option may adversely affect SMP systems.
550 I.e., processors other than the first one may not boot up.
551 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
552 what it believes to be lockup conditions.
554 config RCU_TORTURE_TEST
555 tristate "torture tests for RCU"
556 depends on DEBUG_KERNEL
560 This option provides a kernel module that runs torture tests
561 on the RCU infrastructure. The kernel module may be built
562 after the fact on the running kernel to be tested, if desired.
564 Say M if you want the RCU torture tests to build as a module.
565 Say N if you are unsure.
567 config KPROBES_SANITY_TEST
568 bool "Kprobes sanity tests"
569 depends on DEBUG_KERNEL
573 This option provides for testing basic kprobes functionality on
574 boot. A sample kprobe, jprobe and kretprobe are inserted and
575 verified for functionality.
577 Say N if you are unsure.
579 config BACKTRACE_SELF_TEST
580 tristate "Self test for the backtrace code"
581 depends on DEBUG_KERNEL
584 This option provides a kernel module that can be used to test
585 the kernel stack backtrace code. This option is not useful
586 for distributions or general kernels, but only for kernel
587 developers working on architecture code.
589 Note that if you want to also test saved backtraces, you will
590 have to enable STACKTRACE as well.
592 Say N if you are unsure.
595 tristate "Linux Kernel Dump Test Tool Module"
596 depends on DEBUG_KERNEL
601 This module enables testing of the different dumping mechanisms by
602 inducing system failures at predefined crash points.
603 If you don't need it: say N
604 Choose M here to compile this code as a module. The module will be
607 Documentation on how to use the module can be found in
610 config FAULT_INJECTION
611 bool "Fault-injection framework"
612 depends on DEBUG_KERNEL
614 Provide fault-injection framework.
615 For more details, see Documentation/fault-injection/.
618 bool "Fault-injection capability for kmalloc"
619 depends on FAULT_INJECTION
621 Provide fault-injection capability for kmalloc.
623 config FAIL_PAGE_ALLOC
624 bool "Fault-injection capabilitiy for alloc_pages()"
625 depends on FAULT_INJECTION
627 Provide fault-injection capability for alloc_pages().
629 config FAIL_MAKE_REQUEST
630 bool "Fault-injection capability for disk IO"
631 depends on FAULT_INJECTION
633 Provide fault-injection capability for disk IO.
635 config FAULT_INJECTION_DEBUG_FS
636 bool "Debugfs entries for fault-injection capabilities"
637 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
639 Enable configuration of fault-injection capabilities via debugfs.
641 config FAULT_INJECTION_STACKTRACE_FILTER
642 bool "stacktrace filter for fault-injection capabilities"
643 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
648 Provide stacktrace filter for fault-injection capabilities
651 bool "Latency measuring infrastructure"
652 select FRAME_POINTER if !MIPS
658 depends on HAVE_LATENCYTOP_SUPPORT
660 Enable this option if you want to use the LatencyTOP tool
661 to find out which userspace is blocking on what kernel operations.
663 source kernel/trace/Kconfig
665 config PROVIDE_OHCI1394_DMA_INIT
666 bool "Remote debugging over FireWire early on boot"
667 depends on PCI && X86
669 If you want to debug problems which hang or crash the kernel early
670 on boot and the crashing machine has a FireWire port, you can use
671 this feature to remotely access the memory of the crashed machine
672 over FireWire. This employs remote DMA as part of the OHCI1394
673 specification which is now the standard for FireWire controllers.
675 With remote DMA, you can monitor the printk buffer remotely using
676 firescope and access all memory below 4GB using fireproxy from gdb.
677 Even controlling a kernel debugger is possible using remote DMA.
681 If ohci1394_dma=early is used as boot parameter, it will initialize
682 all OHCI1394 controllers which are found in the PCI config space.
684 As all changes to the FireWire bus such as enabling and disabling
685 devices cause a bus reset and thereby disable remote DMA for all
686 devices, be sure to have the cable plugged and FireWire enabled on
687 the debugging host before booting the debug target for debugging.
689 This code (~1k) is freed after boot. By then, the firewire stack
690 in charge of the OHCI-1394 controllers should be used instead.
692 See Documentation/debugging-via-ohci1394.txt for more information.
694 config FIREWIRE_OHCI_REMOTE_DMA
695 bool "Remote debugging over FireWire with firewire-ohci"
696 depends on FIREWIRE_OHCI
698 This option lets you use the FireWire bus for remote debugging
699 with help of the firewire-ohci driver. It enables unfiltered
700 remote DMA in firewire-ohci.
701 See Documentation/debugging-via-ohci1394.txt for more information.
705 source "samples/Kconfig"
707 source "lib/Kconfig.kgdb"