[linux.git] / lib / Kconfig.debug


config PRINTK_TIME
	bool "Show timing information on printks"
	help
	  Selecting this option causes timing information to be
	  included in printk output.  This allows you to measure
	  the interval between kernel operations, including bootup
	  operations.  This is useful for identifying long delays
	  in kernel startup.


config 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 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_KERNEL
	bool "Kernel debugging"
	help
	  Say Y here if you are developing drivers or trying to debug and
	  identify kernel problems.

config LOG_BUF_SHIFT
	int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" if DEBUG_KERNEL
	range 12 21
	default 17 if S390
	default 16 if X86_NUMAQ || IA64
	default 15 if SMP
	default 14
	help
	  Select kernel log buffer size as a power of 2.
	  Defaults and Examples:
	  	     17 => 128 KB for S/390
		     16 => 64 KB for x86 NUMAQ or IA-64
	             15 => 32 KB for SMP
	             14 => 16 KB for uniprocessor
		     13 =>  8 KB
		     12 =>  4 KB

config DETECT_SOFTLOCKUP
	bool "Detect Soft Lockups"
	depends on DEBUG_KERNEL
	default y
	help
	  Say Y here to enable the kernel to detect "soft lockups",
	  which are bugs that cause the kernel to loop in kernel
	  mode for more than 10 seconds, without giving other tasks a
	  chance to run.

	  When a soft-lockup is detected, the kernel will print the
	  current stack trace (which you should report), but the
	  system will stay locked up. This feature has negligible
	  overhead.

	  (Note that "hard lockups" are separate type of bugs that
	   can be detected via the NMI-watchdog, on platforms that
	   support it.)

config 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 DEBUG_SLAB
	bool "Debug slab memory allocations"
	depends on DEBUG_KERNEL && SLAB
	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 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 debugging"
	depends on DEBUG_KERNEL
	help
	  Say Y here and build SMP to catch missing spinlock initialization
	  and certain other kinds of spinlock errors commonly made.  This is
	  best used in conjunction with the NMI watchdog so that spinlock
	  deadlocks are also debuggable.

config DEBUG_SPINLOCK_SLEEP
	bool "Sleep-inside-spinlock checking"
	depends on DEBUG_KERNEL
	help
	  If you say Y here, various routines which may sleep will become very
	  noisy if they are called with a spinlock held.

config STACKTRACE
	bool
	depends on STACKTRACE_SUPPORT

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 DEBUG_BUGVERBOSE
	bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
	depends on BUG
	depends on ARM || ARM26 || M32R || M68K || SPARC32 || SPARC64 || X86_32 || FRV
	default !EMBEDDED
	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.
	  Say Y here only if you plan to debug the kernel.

	  If unsure, say N.

config DEBUG_FS
	bool "Debug Filesystem"
	depends on SYSFS
	help
	  debugfs is a virtual file system that kernel developers use to put
	  debugging files into.  Enable this option to be able to read and
	  write to these files.

	  If unsure, say N.

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 FRAME_POINTER
	bool "Compile the kernel with frame pointers"
	depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML)
	default y if DEBUG_INFO && UML
	help
	  If you say Y here the resulting kernel image will be slightly larger
	  and slower, but it might give very useful debugging information on
	  some architectures or if you use external debuggers.
	  If you don't debug the kernel, you can say N.

config UNWIND_INFO
	bool "Compile the kernel with frame unwind information"
	depends on !IA64 && !PARISC
	depends on !MODULES || !(MIPS || PPC || SUPERH || V850)
	help
	  If you say Y here the resulting kernel image will be slightly larger
	  but not slower, and it will give very useful debugging information.
	  If you don't debug the kernel, you can say N, but we may not be able
	  to solve problems without frame unwind information or frame pointers.

config STACK_UNWIND
	bool "Stack unwind support"
	depends on UNWIND_INFO
	depends on X86
	help
	  This enables more precise stack traces, omitting all unrelated
	  occurrences of pointers into kernel code from the dump.

config FORCED_INLINING
	bool "Force gcc to inline functions marked 'inline'"
	depends on DEBUG_KERNEL
	default y
	help
	  This option determines if the kernel forces gcc to inline the functions
	  developers have marked 'inline'. Doing so takes away freedom from gcc to
	  do what it thinks is best, which is desirable for the gcc 3.x series of
	  compilers. The gcc 4.x series have a rewritten inlining algorithm and
	  disabling this option will generate a smaller kernel there. Hopefully
	  this algorithm is so good that allowing gcc4 to make the decision can
	  become the default in the future, until then this option is there to
	  test gcc for this.

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 start automatically
	  at boot time (you probably don't).
	  Say M if you want the RCU torture tests to build as a module.
	  Say N if you are unsure.
Commit	Line	Data
1da177e4 LT	1
	2	config PRINTK_TIME
	3	bool "Show timing information on printks"
	4	help
	5	Selecting this option causes timing information to be
	6	included in printk output. This allows you to measure
	7	the interval between kernel operations, including bootup
	8	operations. This is useful for identifying long delays
	9	in kernel startup.
	10
	11
1da177e4 LT	12	config MAGIC_SYSRQ
1da177e4 LT	13	bool "Magic SysRq key"
f346f4b3	14	depends on !UML
1da177e4 LT	15	help
	16	If you say Y here, you will have some control over the system even
	17	if the system crashes for example during kernel debugging (e.g., you
	18	will be able to flush the buffer cache to disk, reboot the system
	19	immediately or dump some status information). This is accomplished
	20	by pressing various keys while holding SysRq (Alt+PrintScreen). It
	21	also works on a serial console (on PC hardware at least), if you
	22	send a BREAK and then within 5 seconds a command keypress. The
	23	keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
	24	unless you really know what this hack does.
	25
f71d20e9 AV	26	config UNUSED_SYMBOLS
	27	bool "Enable unused/obsolete exported symbols"
	28	default y if X86
	29	help
	30	Unused but exported symbols make the kernel needlessly bigger. For
	31	that reason most of these unused exports will soon be removed. This
	32	option is provided temporarily to provide a transition period in case
	33	some external kernel module needs one of these symbols anyway. If you
	34	encounter such a case in your module, consider if you are actually
	35	using the right API. (rationale: since nobody in the kernel is using
	36	this in a module, there is a pretty good chance it's actually the
	37	wrong interface to use). If you really need the symbol, please send a
	38	mail to the linux kernel mailing list mentioning the symbol and why
	39	you really need it, and what the merge plan to the mainline kernel for
	40	your module is.
	41
f346f4b3 AB	42	config DEBUG_KERNEL
	43	bool "Kernel debugging"
	44	help
	45	Say Y here if you are developing drivers or trying to debug and
	46	identify kernel problems.
	47
1da177e4 LT	48	config LOG_BUF_SHIFT
	49	int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" if DEBUG_KERNEL
	50	range 12 21
347a8dc3	51	default 17 if S390
1da177e4 LT	52	default 16 if X86_NUMAQ \|\| IA64
	53	default 15 if SMP
	54	default 14
	55	help
	56	Select kernel log buffer size as a power of 2.
	57	Defaults and Examples:
	58	17 => 128 KB for S/390
	59	16 => 64 KB for x86 NUMAQ or IA-64
	60	15 => 32 KB for SMP
	61	14 => 16 KB for uniprocessor
	62	13 => 8 KB
	63	12 => 4 KB
	64
8446f1d3 IM	65	config DETECT_SOFTLOCKUP
	66	bool "Detect Soft Lockups"
	67	depends on DEBUG_KERNEL
	68	default y
	69	help
	70	Say Y here to enable the kernel to detect "soft lockups",
	71	which are bugs that cause the kernel to loop in kernel
	72	mode for more than 10 seconds, without giving other tasks a
	73	chance to run.
	74
	75	When a soft-lockup is detected, the kernel will print the
	76	current stack trace (which you should report), but the
	77	system will stay locked up. This feature has negligible
	78	overhead.
	79
	80	(Note that "hard lockups" are separate type of bugs that
	81	can be detected via the NMI-watchdog, on platforms that
	82	support it.)
	83
1da177e4 LT	84	config SCHEDSTATS
	85	bool "Collect scheduler statistics"
	86	depends on DEBUG_KERNEL && PROC_FS
	87	help
	88	If you say Y here, additional code will be inserted into the
	89	scheduler and related routines to collect statistics about
	90	scheduler behavior and provide them in /proc/schedstat. These
	91	stats may be useful for both tuning and debugging the scheduler
	92	If you aren't debugging the scheduler or trying to tune a specific
	93	application, you can say N to avoid the very slight overhead
	94	this adds.
	95
	96	config DEBUG_SLAB
4a2f0acf	97	bool "Debug slab memory allocations"
50dd26ba	98	depends on DEBUG_KERNEL && SLAB
1da177e4 LT	99	help
	100	Say Y here to have the kernel do limited verification on memory
	101	allocation as well as poisoning memory on free to catch use of freed
	102	memory. This can make kmalloc/kfree-intensive workloads much slower.
	103
871751e2 AV	104	config DEBUG_SLAB_LEAK
	105	bool "Memory leak debugging"
	106	depends on DEBUG_SLAB
	107
1da177e4 LT	108	config DEBUG_PREEMPT
1da177e4 LT	109	bool "Debug preemptible kernel"
8637c099	110	depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
1da177e4 LT	111	default y
	112	help
	113	If you say Y here then the kernel will use a debug variant of the
	114	commonly used smp_processor_id() function and will print warnings
	115	if kernel code uses it in a preemption-unsafe way. Also, the kernel
	116	will detect preemption count underflows.
	117
e7eebaf6 IM	118	config DEBUG_RT_MUTEXES
e7eebaf6 IM	119	bool "RT Mutex debugging, deadlock detection"
e7eebaf6 IM	120	depends on DEBUG_KERNEL && RT_MUTEXES
	121	help
	122	This allows rt mutex semantics violations and rt mutex related
	123	deadlocks (lockups) to be detected and reported automatically.
	124
	125	config DEBUG_PI_LIST
	126	bool
	127	default y
	128	depends on DEBUG_RT_MUTEXES
	129
61a87122 TG	130	config RT_MUTEX_TESTER
61a87122 TG	131	bool "Built-in scriptable tester for rt-mutexes"
a1583d3e	132	depends on DEBUG_KERNEL && RT_MUTEXES
61a87122 TG	133	help
	134	This option enables a rt-mutex tester.
	135
1da177e4 LT	136	config DEBUG_SPINLOCK
	137	bool "Spinlock debugging"
	138	depends on DEBUG_KERNEL
	139	help
	140	Say Y here and build SMP to catch missing spinlock initialization
	141	and certain other kinds of spinlock errors commonly made. This is
	142	best used in conjunction with the NMI watchdog so that spinlock
	143	deadlocks are also debuggable.
	144
	145	config DEBUG_SPINLOCK_SLEEP
	146	bool "Sleep-inside-spinlock checking"
	147	depends on DEBUG_KERNEL
	148	help
	149	If you say Y here, various routines which may sleep will become very
	150	noisy if they are called with a spinlock held.
	151
8637c099 IM	152	config STACKTRACE
	153	bool
	154	depends on STACKTRACE_SUPPORT
	155
1da177e4 LT	156	config DEBUG_KOBJECT
	157	bool "kobject debugging"
	158	depends on DEBUG_KERNEL
	159	help
	160	If you say Y here, some extra kobject debugging messages will be sent
	161	to the syslog.
	162
	163	config DEBUG_HIGHMEM
	164	bool "Highmem debugging"
	165	depends on DEBUG_KERNEL && HIGHMEM
	166	help
	167	This options enables addition error checking for high memory systems.
	168	Disable for production systems.
	169
	170	config DEBUG_BUGVERBOSE
	171	bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
c8538a7a	172	depends on BUG
0d078f6f	173	depends on ARM \|\| ARM26 \|\| M32R \|\| M68K \|\| SPARC32 \|\| SPARC64 \|\| X86_32 \|\| FRV
1da177e4 LT	174	default !EMBEDDED
	175	help
	176	Say Y here to make BUG() panics output the file name and line number
	177	of the BUG call as well as the EIP and oops trace. This aids
	178	debugging but costs about 70-100K of memory.
	179
	180	config DEBUG_INFO
	181	bool "Compile the kernel with debug info"
	182	depends on DEBUG_KERNEL
	183	help
	184	If you say Y here the resulting kernel image will include
	185	debugging info resulting in a larger kernel image.
	186	Say Y here only if you plan to debug the kernel.
	187
	188	If unsure, say N.
	189
1da177e4 LT	190	config DEBUG_FS
1da177e4 LT	191	bool "Debug Filesystem"
ae36b883	192	depends on SYSFS
1da177e4 LT	193	help
	194	debugfs is a virtual file system that kernel developers use to put
	195	debugging files into. Enable this option to be able to read and
	196	write to these files.
	197
	198	If unsure, say N.
	199
a241ec65 PM	200	config DEBUG_VM
	201	bool "Debug VM"
	202	depends on DEBUG_KERNEL
	203	help
13e7444b NP	204	Enable this to turn on extended checks in the virtual-memory system
13e7444b NP	205	that may impact performance.
a241ec65 PM	206
	207	If unsure, say N.
	208
1da177e4 LT	209	config FRAME_POINTER
1da177e4 LT	210	bool "Compile the kernel with frame pointers"
aeb39986	211	depends on DEBUG_KERNEL && (X86 \|\| CRIS \|\| M68K \|\| M68KNOMMU \|\| FRV \|\| UML)
37fce857	212	default y if DEBUG_INFO && UML
1da177e4 LT	213	help
1da177e4 LT	214	If you say Y here the resulting kernel image will be slightly larger
2a38bccd JJ	215	and slower, but it might give very useful debugging information on
2a38bccd JJ	216	some architectures or if you use external debuggers.
aeb39986	217	If you don't debug the kernel, you can say N.
1da177e4	218
604bf5a2 JB	219	config UNWIND_INFO
604bf5a2 JB	220	bool "Compile the kernel with frame unwind information"
4552d5dc JB	221	depends on !IA64 && !PARISC
4552d5dc JB	222	depends on !MODULES \|\| !(MIPS \|\| PPC \|\| SUPERH \|\| V850)
604bf5a2 JB	223	help
	224	If you say Y here the resulting kernel image will be slightly larger
	225	but not slower, and it will give very useful debugging information.
	226	If you don't debug the kernel, you can say N, but we may not be able
	227	to solve problems without frame unwind information or frame pointers.
	228
4552d5dc JB	229	config STACK_UNWIND
	230	bool "Stack unwind support"
	231	depends on UNWIND_INFO
176a2718	232	depends on X86
4552d5dc JB	233	help
	234	This enables more precise stack traces, omitting all unrelated
	235	occurrences of pointers into kernel code from the dump.
	236
a9df3d0f IM	237	config FORCED_INLINING
	238	bool "Force gcc to inline functions marked 'inline'"
	239	depends on DEBUG_KERNEL
	240	default y
	241	help
	242	This option determines if the kernel forces gcc to inline the functions
	243	developers have marked 'inline'. Doing so takes away freedom from gcc to
	244	do what it thinks is best, which is desirable for the gcc 3.x series of
	245	compilers. The gcc 4.x series have a rewritten inlining algorithm and
	246	disabling this option will generate a smaller kernel there. Hopefully
	247	this algorithm is so good that allowing gcc4 to make the decision can
	248	become the default in the future, until then this option is there to
	249	test gcc for this.
	250
a241ec65 PM	251	config RCU_TORTURE_TEST
	252	tristate "torture tests for RCU"
	253	depends on DEBUG_KERNEL
	254	default n
	255	help
	256	This option provides a kernel module that runs torture tests
	257	on the RCU infrastructure. The kernel module may be built
	258	after the fact on the running kernel to be tested, if desired.
	259
	260	Say Y here if you want RCU torture tests to start automatically
	261	at boot time (you probably don't).
	262	Say M if you want the RCU torture tests to build as a module.
	263	Say N if you are unsure.