3 bool "Show timing information on printks"
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
13 bool "Magic SysRq key"
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.
27 bool "Enable unused/obsolete exported symbols"
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
43 bool "Kernel debugging"
45 Say Y here if you are developing drivers or trying to debug and
46 identify kernel problems.
49 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" if DEBUG_KERNEL
51 default 17 if S390 || LOCKDEP
52 default 16 if X86_NUMAQ || IA64
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
61 14 => 16 KB for uniprocessor
65 config DETECT_SOFTLOCKUP
66 bool "Detect Soft Lockups"
67 depends on DEBUG_KERNEL
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
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
80 (Note that "hard lockups" are separate type of bugs that
81 can be detected via the NMI-watchdog, on platforms that
85 bool "Collect scheduler statistics"
86 depends on DEBUG_KERNEL && PROC_FS
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
97 bool "Debug slab memory allocations"
98 depends on DEBUG_KERNEL && SLAB
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.
104 config DEBUG_SLAB_LEAK
105 bool "Memory leak debugging"
106 depends on DEBUG_SLAB
109 bool "Debug preemptible kernel"
110 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
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.
118 config DEBUG_RT_MUTEXES
119 bool "RT Mutex debugging, deadlock detection"
120 depends on DEBUG_KERNEL && RT_MUTEXES
122 This allows rt mutex semantics violations and rt mutex related
123 deadlocks (lockups) to be detected and reported automatically.
128 depends on DEBUG_RT_MUTEXES
130 config RT_MUTEX_TESTER
131 bool "Built-in scriptable tester for rt-mutexes"
132 depends on DEBUG_KERNEL && RT_MUTEXES
134 This option enables a rt-mutex tester.
136 config DEBUG_SPINLOCK
137 bool "Spinlock debugging"
138 depends on DEBUG_KERNEL
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.
145 config DEBUG_SPINLOCK_SLEEP
146 bool "Sleep-inside-spinlock checking"
147 depends on DEBUG_KERNEL
149 If you say Y here, various routines which may sleep will become very
150 noisy if they are called with a spinlock held.
152 config DEBUG_LOCKING_API_SELFTESTS
153 bool "Locking API boot-time self-tests"
154 depends on DEBUG_KERNEL
156 Say Y here if you want the kernel to run a short self-test during
157 bootup. The self-test checks whether common types of locking bugs
158 are detected by debugging mechanisms or not. (if you disable
159 lock debugging then those bugs wont be detected of course.)
160 The following locking APIs are covered: spinlocks, rwlocks,
165 depends on STACKTRACE_SUPPORT
168 bool "kobject debugging"
169 depends on DEBUG_KERNEL
171 If you say Y here, some extra kobject debugging messages will be sent
175 bool "Highmem debugging"
176 depends on DEBUG_KERNEL && HIGHMEM
178 This options enables addition error checking for high memory systems.
179 Disable for production systems.
181 config DEBUG_BUGVERBOSE
182 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
184 depends on ARM || ARM26 || M32R || M68K || SPARC32 || SPARC64 || X86_32 || FRV
187 Say Y here to make BUG() panics output the file name and line number
188 of the BUG call as well as the EIP and oops trace. This aids
189 debugging but costs about 70-100K of memory.
192 bool "Compile the kernel with debug info"
193 depends on DEBUG_KERNEL
195 If you say Y here the resulting kernel image will include
196 debugging info resulting in a larger kernel image.
197 Say Y here only if you plan to debug the kernel.
202 bool "Debug Filesystem"
205 debugfs is a virtual file system that kernel developers use to put
206 debugging files into. Enable this option to be able to read and
207 write to these files.
213 depends on DEBUG_KERNEL
215 Enable this to turn on extended checks in the virtual-memory system
216 that may impact performance.
221 bool "Compile the kernel with frame pointers"
222 depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390)
223 default y if DEBUG_INFO && UML
225 If you say Y here the resulting kernel image will be slightly larger
226 and slower, but it might give very useful debugging information on
227 some architectures or if you use external debuggers.
228 If you don't debug the kernel, you can say N.
231 bool "Compile the kernel with frame unwind information"
232 depends on !IA64 && !PARISC
233 depends on !MODULES || !(MIPS || PPC || SUPERH || V850)
235 If you say Y here the resulting kernel image will be slightly larger
236 but not slower, and it will give very useful debugging information.
237 If you don't debug the kernel, you can say N, but we may not be able
238 to solve problems without frame unwind information or frame pointers.
241 bool "Stack unwind support"
242 depends on UNWIND_INFO
245 This enables more precise stack traces, omitting all unrelated
246 occurrences of pointers into kernel code from the dump.
248 config FORCED_INLINING
249 bool "Force gcc to inline functions marked 'inline'"
250 depends on DEBUG_KERNEL
253 This option determines if the kernel forces gcc to inline the functions
254 developers have marked 'inline'. Doing so takes away freedom from gcc to
255 do what it thinks is best, which is desirable for the gcc 3.x series of
256 compilers. The gcc 4.x series have a rewritten inlining algorithm and
257 disabling this option will generate a smaller kernel there. Hopefully
258 this algorithm is so good that allowing gcc4 to make the decision can
259 become the default in the future, until then this option is there to
262 config RCU_TORTURE_TEST
263 tristate "torture tests for RCU"
264 depends on DEBUG_KERNEL
267 This option provides a kernel module that runs torture tests
268 on the RCU infrastructure. The kernel module may be built
269 after the fact on the running kernel to be tested, if desired.
271 Say Y here if you want RCU torture tests to start automatically
272 at boot time (you probably don't).
273 Say M if you want the RCU torture tests to build as a module.
274 Say N if you are unsure.