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 10 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
163 bool "Collect scheduler debugging info"
164 depends on DEBUG_KERNEL && PROC_FS
167 If you say Y here, the /proc/sched_debug file will be provided
168 that can help debug the scheduler. The runtime overhead of this
172 bool "Collect scheduler statistics"
173 depends on DEBUG_KERNEL && PROC_FS
175 If you say Y here, additional code will be inserted into the
176 scheduler and related routines to collect statistics about
177 scheduler behavior and provide them in /proc/schedstat. These
178 stats may be useful for both tuning and debugging the scheduler
179 If you aren't debugging the scheduler or trying to tune a specific
180 application, you can say N to avoid the very slight overhead
184 bool "Collect kernel timers statistics"
185 depends on DEBUG_KERNEL && PROC_FS
187 If you say Y here, additional code will be inserted into the
188 timer routines to collect statistics about kernel timers being
189 reprogrammed. The statistics can be read from /proc/timer_stats.
190 The statistics collection is started by writing 1 to /proc/timer_stats,
191 writing 0 stops it. This feature is useful to collect information
192 about timer usage patterns in kernel and userspace. This feature
193 is lightweight if enabled in the kernel config but not activated
194 (it defaults to deactivated on bootup and will only be activated
195 if some application like powertop activates it explicitly).
198 bool "Debug object operations"
199 depends on DEBUG_KERNEL
201 If you say Y here, additional code will be inserted into the
202 kernel to track the life time of various objects and validate
203 the operations on those objects.
205 config DEBUG_OBJECTS_SELFTEST
206 bool "Debug objects selftest"
207 depends on DEBUG_OBJECTS
209 This enables the selftest of the object debug code.
211 config DEBUG_OBJECTS_FREE
212 bool "Debug objects in freed memory"
213 depends on DEBUG_OBJECTS
215 This enables checks whether a k/v free operation frees an area
216 which contains an object which has not been deactivated
217 properly. This can make kmalloc/kfree-intensive workloads
221 bool "Debug slab memory allocations"
222 depends on DEBUG_KERNEL && SLAB
224 Say Y here to have the kernel do limited verification on memory
225 allocation as well as poisoning memory on free to catch use of freed
226 memory. This can make kmalloc/kfree-intensive workloads much slower.
228 config DEBUG_SLAB_LEAK
229 bool "Memory leak debugging"
230 depends on DEBUG_SLAB
233 bool "SLUB debugging on by default"
234 depends on SLUB && SLUB_DEBUG
237 Boot with debugging on by default. SLUB boots by default with
238 the runtime debug capabilities switched off. Enabling this is
239 equivalent to specifying the "slub_debug" parameter on boot.
240 There is no support for more fine grained debug control like
241 possible with slub_debug=xxx. SLUB debugging may be switched
242 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
247 bool "Enable SLUB performance statistics"
248 depends on SLUB && SLUB_DEBUG && SYSFS
250 SLUB statistics are useful to debug SLUBs allocation behavior in
251 order find ways to optimize the allocator. This should never be
252 enabled for production use since keeping statistics slows down
253 the allocator by a few percentage points. The slabinfo command
254 supports the determination of the most active slabs to figure
255 out which slabs are relevant to a particular load.
256 Try running: slabinfo -DA
259 bool "Debug preemptible kernel"
260 depends on DEBUG_KERNEL && PREEMPT && (TRACE_IRQFLAGS_SUPPORT || PPC64)
263 If you say Y here then the kernel will use a debug variant of the
264 commonly used smp_processor_id() function and will print warnings
265 if kernel code uses it in a preemption-unsafe way. Also, the kernel
266 will detect preemption count underflows.
268 config DEBUG_RT_MUTEXES
269 bool "RT Mutex debugging, deadlock detection"
270 depends on DEBUG_KERNEL && RT_MUTEXES
272 This allows rt mutex semantics violations and rt mutex related
273 deadlocks (lockups) to be detected and reported automatically.
278 depends on DEBUG_RT_MUTEXES
280 config RT_MUTEX_TESTER
281 bool "Built-in scriptable tester for rt-mutexes"
282 depends on DEBUG_KERNEL && RT_MUTEXES
284 This option enables a rt-mutex tester.
286 config DEBUG_SPINLOCK
287 bool "Spinlock and rw-lock debugging: basic checks"
288 depends on DEBUG_KERNEL
290 Say Y here and build SMP to catch missing spinlock initialization
291 and certain other kinds of spinlock errors commonly made. This is
292 best used in conjunction with the NMI watchdog so that spinlock
293 deadlocks are also debuggable.
296 bool "Mutex debugging: basic checks"
297 depends on DEBUG_KERNEL
299 This feature allows mutex semantics violations to be detected and
302 config DEBUG_LOCK_ALLOC
303 bool "Lock debugging: detect incorrect freeing of live locks"
304 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
305 select DEBUG_SPINLOCK
309 This feature will check whether any held lock (spinlock, rwlock,
310 mutex or rwsem) is incorrectly freed by the kernel, via any of the
311 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
312 vfree(), etc.), whether a live lock is incorrectly reinitialized via
313 spin_lock_init()/mutex_init()/etc., or whether there is any lock
314 held during task exit.
317 bool "Lock debugging: prove locking correctness"
318 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
320 select DEBUG_SPINLOCK
322 select DEBUG_LOCK_ALLOC
325 This feature enables the kernel to prove that all locking
326 that occurs in the kernel runtime is mathematically
327 correct: that under no circumstance could an arbitrary (and
328 not yet triggered) combination of observed locking
329 sequences (on an arbitrary number of CPUs, running an
330 arbitrary number of tasks and interrupt contexts) cause a
333 In short, this feature enables the kernel to report locking
334 related deadlocks before they actually occur.
336 The proof does not depend on how hard and complex a
337 deadlock scenario would be to trigger: how many
338 participant CPUs, tasks and irq-contexts would be needed
339 for it to trigger. The proof also does not depend on
340 timing: if a race and a resulting deadlock is possible
341 theoretically (no matter how unlikely the race scenario
342 is), it will be proven so and will immediately be
343 reported by the kernel (once the event is observed that
344 makes the deadlock theoretically possible).
346 If a deadlock is impossible (i.e. the locking rules, as
347 observed by the kernel, are mathematically correct), the
348 kernel reports nothing.
350 NOTE: this feature can also be enabled for rwlocks, mutexes
351 and rwsems - in which case all dependencies between these
352 different locking variants are observed and mapped too, and
353 the proof of observed correctness is also maintained for an
354 arbitrary combination of these separate locking variants.
356 For more details, see Documentation/lockdep-design.txt.
360 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
362 select FRAME_POINTER if !X86 && !MIPS
367 bool "Lock usage statistics"
368 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
370 select DEBUG_SPINLOCK
372 select DEBUG_LOCK_ALLOC
375 This feature enables tracking lock contention points
377 For more details, see Documentation/lockstat.txt
380 bool "Lock dependency engine debugging"
381 depends on DEBUG_KERNEL && LOCKDEP
383 If you say Y here, the lock dependency engine will do
384 additional runtime checks to debug itself, at the price
385 of more runtime overhead.
387 config TRACE_IRQFLAGS
388 depends on DEBUG_KERNEL
391 depends on TRACE_IRQFLAGS_SUPPORT
392 depends on PROVE_LOCKING
394 config DEBUG_SPINLOCK_SLEEP
395 bool "Spinlock debugging: sleep-inside-spinlock checking"
396 depends on DEBUG_KERNEL
398 If you say Y here, various routines which may sleep will become very
399 noisy if they are called with a spinlock held.
401 config DEBUG_LOCKING_API_SELFTESTS
402 bool "Locking API boot-time self-tests"
403 depends on DEBUG_KERNEL
405 Say Y here if you want the kernel to run a short self-test during
406 bootup. The self-test checks whether common types of locking bugs
407 are detected by debugging mechanisms or not. (if you disable
408 lock debugging then those bugs wont be detected of course.)
409 The following locking APIs are covered: spinlocks, rwlocks,
414 depends on DEBUG_KERNEL
415 depends on STACKTRACE_SUPPORT
418 bool "kobject debugging"
419 depends on DEBUG_KERNEL
421 If you say Y here, some extra kobject debugging messages will be sent
425 bool "Highmem debugging"
426 depends on DEBUG_KERNEL && HIGHMEM
428 This options enables addition error checking for high memory systems.
429 Disable for production systems.
431 config DEBUG_BUGVERBOSE
432 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
434 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
435 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
438 Say Y here to make BUG() panics output the file name and line number
439 of the BUG call as well as the EIP and oops trace. This aids
440 debugging but costs about 70-100K of memory.
443 bool "Compile the kernel with debug info"
444 depends on DEBUG_KERNEL
446 If you say Y here the resulting kernel image will include
447 debugging info resulting in a larger kernel image.
448 This adds debug symbols to the kernel and modules (gcc -g), and
449 is needed if you intend to use kernel crashdump or binary object
450 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
451 Say Y here only if you plan to debug the kernel.
457 depends on DEBUG_KERNEL
459 Enable this to turn on extended checks in the virtual-memory system
460 that may impact performance.
464 config DEBUG_WRITECOUNT
465 bool "Debug filesystem writers count"
466 depends on DEBUG_KERNEL
468 Enable this to catch wrong use of the writers count in struct
469 vfsmount. This will increase the size of each file struct by
475 bool "Debug linked list manipulation"
476 depends on DEBUG_KERNEL
478 Enable this to turn on extended checks in the linked-list
484 bool "Debug SG table operations"
485 depends on DEBUG_KERNEL
487 Enable this to turn on checks on scatter-gather tables. This can
488 help find problems with drivers that do not properly initialize
494 bool "Compile the kernel with frame pointers"
495 depends on DEBUG_KERNEL && \
496 (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || \
497 AVR32 || SUPERH || BLACKFIN || MN10300)
498 default y if DEBUG_INFO && UML
500 If you say Y here the resulting kernel image will be slightly larger
501 and slower, but it might give very useful debugging information on
502 some architectures or if you use external debuggers.
503 If you don't debug the kernel, you can say N.
505 config BOOT_PRINTK_DELAY
506 bool "Delay each boot printk message by N milliseconds"
507 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
509 This build option allows you to read kernel boot messages
510 by inserting a short delay after each one. The delay is
511 specified in milliseconds on the kernel command line,
512 using "boot_delay=N".
514 It is likely that you would also need to use "lpj=M" to preset
515 the "loops per jiffie" value.
516 See a previous boot log for the "lpj" value to use for your
517 system, and then set "lpj=M" before setting "boot_delay=N".
518 NOTE: Using this option may adversely affect SMP systems.
519 I.e., processors other than the first one may not boot up.
520 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
521 what it believes to be lockup conditions.
523 config RCU_TORTURE_TEST
524 tristate "torture tests for RCU"
525 depends on DEBUG_KERNEL
529 This option provides a kernel module that runs torture tests
530 on the RCU infrastructure. The kernel module may be built
531 after the fact on the running kernel to be tested, if desired.
533 Say M if you want the RCU torture tests to build as a module.
534 Say N if you are unsure.
536 config KPROBES_SANITY_TEST
537 bool "Kprobes sanity tests"
538 depends on DEBUG_KERNEL
542 This option provides for testing basic kprobes functionality on
543 boot. A sample kprobe, jprobe and kretprobe are inserted and
544 verified for functionality.
546 Say N if you are unsure.
548 config BACKTRACE_SELF_TEST
549 tristate "Self test for the backtrace code"
550 depends on DEBUG_KERNEL
553 This option provides a kernel module that can be used to test
554 the kernel stack backtrace code. This option is not useful
555 for distributions or general kernels, but only for kernel
556 developers working on architecture code.
558 Say N if you are unsure.
561 tristate "Linux Kernel Dump Test Tool Module"
562 depends on DEBUG_KERNEL
567 This module enables testing of the different dumping mechanisms by
568 inducing system failures at predefined crash points.
569 If you don't need it: say N
570 Choose M here to compile this code as a module. The module will be
573 Documentation on how to use the module can be found in
576 config FAULT_INJECTION
577 bool "Fault-injection framework"
578 depends on DEBUG_KERNEL
580 Provide fault-injection framework.
581 For more details, see Documentation/fault-injection/.
584 bool "Fault-injection capability for kmalloc"
585 depends on FAULT_INJECTION
587 Provide fault-injection capability for kmalloc.
589 config FAIL_PAGE_ALLOC
590 bool "Fault-injection capabilitiy for alloc_pages()"
591 depends on FAULT_INJECTION
593 Provide fault-injection capability for alloc_pages().
595 config FAIL_MAKE_REQUEST
596 bool "Fault-injection capability for disk IO"
597 depends on FAULT_INJECTION
599 Provide fault-injection capability for disk IO.
601 config FAULT_INJECTION_DEBUG_FS
602 bool "Debugfs entries for fault-injection capabilities"
603 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
605 Enable configuration of fault-injection capabilities via debugfs.
607 config FAULT_INJECTION_STACKTRACE_FILTER
608 bool "stacktrace filter for fault-injection capabilities"
609 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
614 Provide stacktrace filter for fault-injection capabilities
617 bool "Latency measuring infrastructure"
618 select FRAME_POINTER if !MIPS
624 depends on HAVE_LATENCYTOP_SUPPORT
626 Enable this option if you want to use the LatencyTOP tool
627 to find out which userspace is blocking on what kernel operations.
629 config PROVIDE_OHCI1394_DMA_INIT
630 bool "Remote debugging over FireWire early on boot"
631 depends on PCI && X86
633 If you want to debug problems which hang or crash the kernel early
634 on boot and the crashing machine has a FireWire port, you can use
635 this feature to remotely access the memory of the crashed machine
636 over FireWire. This employs remote DMA as part of the OHCI1394
637 specification which is now the standard for FireWire controllers.
639 With remote DMA, you can monitor the printk buffer remotely using
640 firescope and access all memory below 4GB using fireproxy from gdb.
641 Even controlling a kernel debugger is possible using remote DMA.
645 If ohci1394_dma=early is used as boot parameter, it will initialize
646 all OHCI1394 controllers which are found in the PCI config space.
648 As all changes to the FireWire bus such as enabling and disabling
649 devices cause a bus reset and thereby disable remote DMA for all
650 devices, be sure to have the cable plugged and FireWire enabled on
651 the debugging host before booting the debug target for debugging.
653 This code (~1k) is freed after boot. By then, the firewire stack
654 in charge of the OHCI-1394 controllers should be used instead.
656 See Documentation/debugging-via-ohci1394.txt for more information.
658 config FIREWIRE_OHCI_REMOTE_DMA
659 bool "Remote debugging over FireWire with firewire-ohci"
660 depends on FIREWIRE_OHCI
662 This option lets you use the FireWire bus for remote debugging
663 with help of the firewire-ohci driver. It enables unfiltered
664 remote DMA in firewire-ohci.
665 See Documentation/debugging-via-ohci1394.txt for more information.
669 source "samples/Kconfig"
671 source "lib/Kconfig.kgdb"