xref: /linux/kernel/trace/Kconfig (revision fd639726bf15fca8ee1a00dce8e0096d0ad9bd18)
1#
2# Architectures that offer an FUNCTION_TRACER implementation should
3#  select HAVE_FUNCTION_TRACER:
4#
5
6config USER_STACKTRACE_SUPPORT
7	bool
8
9config NOP_TRACER
10	bool
11
12config HAVE_FTRACE_NMI_ENTER
13	bool
14	help
15	  See Documentation/trace/ftrace-design.txt
16
17config HAVE_FUNCTION_TRACER
18	bool
19	help
20	  See Documentation/trace/ftrace-design.txt
21
22config HAVE_FUNCTION_GRAPH_TRACER
23	bool
24	help
25	  See Documentation/trace/ftrace-design.txt
26
27config HAVE_DYNAMIC_FTRACE
28	bool
29	help
30	  See Documentation/trace/ftrace-design.txt
31
32config HAVE_DYNAMIC_FTRACE_WITH_REGS
33	bool
34
35config HAVE_FTRACE_MCOUNT_RECORD
36	bool
37	help
38	  See Documentation/trace/ftrace-design.txt
39
40config HAVE_SYSCALL_TRACEPOINTS
41	bool
42	help
43	  See Documentation/trace/ftrace-design.txt
44
45config HAVE_FENTRY
46	bool
47	help
48	  Arch supports the gcc options -pg with -mfentry
49
50config HAVE_C_RECORDMCOUNT
51	bool
52	help
53	  C version of recordmcount available?
54
55config TRACER_MAX_TRACE
56	bool
57
58config TRACE_CLOCK
59	bool
60
61config RING_BUFFER
62	bool
63	select TRACE_CLOCK
64	select IRQ_WORK
65
66config FTRACE_NMI_ENTER
67       bool
68       depends on HAVE_FTRACE_NMI_ENTER
69       default y
70
71config EVENT_TRACING
72	select CONTEXT_SWITCH_TRACER
73        select GLOB
74	bool
75
76config CONTEXT_SWITCH_TRACER
77	bool
78
79config RING_BUFFER_ALLOW_SWAP
80	bool
81	help
82	 Allow the use of ring_buffer_swap_cpu.
83	 Adds a very slight overhead to tracing when enabled.
84
85# All tracer options should select GENERIC_TRACER. For those options that are
86# enabled by all tracers (context switch and event tracer) they select TRACING.
87# This allows those options to appear when no other tracer is selected. But the
88# options do not appear when something else selects it. We need the two options
89# GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the
90# hiding of the automatic options.
91
92config TRACING
93	bool
94	select DEBUG_FS
95	select RING_BUFFER
96	select STACKTRACE if STACKTRACE_SUPPORT
97	select TRACEPOINTS
98	select NOP_TRACER
99	select BINARY_PRINTF
100	select EVENT_TRACING
101	select TRACE_CLOCK
102
103config GENERIC_TRACER
104	bool
105	select TRACING
106
107#
108# Minimum requirements an architecture has to meet for us to
109# be able to offer generic tracing facilities:
110#
111config TRACING_SUPPORT
112	bool
113	# PPC32 has no irqflags tracing support, but it can use most of the
114	# tracers anyway, they were tested to build and work. Note that new
115	# exceptions to this list aren't welcomed, better implement the
116	# irqflags tracing for your architecture.
117	depends on TRACE_IRQFLAGS_SUPPORT || PPC32
118	depends on STACKTRACE_SUPPORT
119	default y
120
121if TRACING_SUPPORT
122
123menuconfig FTRACE
124	bool "Tracers"
125	default y if DEBUG_KERNEL
126	help
127	  Enable the kernel tracing infrastructure.
128
129if FTRACE
130
131config FUNCTION_TRACER
132	bool "Kernel Function Tracer"
133	depends on HAVE_FUNCTION_TRACER
134	select KALLSYMS
135	select GENERIC_TRACER
136	select CONTEXT_SWITCH_TRACER
137	select GLOB
138	select TASKS_RCU if PREEMPT
139	help
140	  Enable the kernel to trace every kernel function. This is done
141	  by using a compiler feature to insert a small, 5-byte No-Operation
142	  instruction at the beginning of every kernel function, which NOP
143	  sequence is then dynamically patched into a tracer call when
144	  tracing is enabled by the administrator. If it's runtime disabled
145	  (the bootup default), then the overhead of the instructions is very
146	  small and not measurable even in micro-benchmarks.
147
148config FUNCTION_GRAPH_TRACER
149	bool "Kernel Function Graph Tracer"
150	depends on HAVE_FUNCTION_GRAPH_TRACER
151	depends on FUNCTION_TRACER
152	depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE
153	default y
154	help
155	  Enable the kernel to trace a function at both its return
156	  and its entry.
157	  Its first purpose is to trace the duration of functions and
158	  draw a call graph for each thread with some information like
159	  the return value. This is done by setting the current return
160	  address on the current task structure into a stack of calls.
161
162
163config PREEMPTIRQ_EVENTS
164	bool "Enable trace events for preempt and irq disable/enable"
165	select TRACE_IRQFLAGS
166	depends on DEBUG_PREEMPT || !PROVE_LOCKING
167	default n
168	help
169	  Enable tracing of disable and enable events for preemption and irqs.
170	  For tracing preempt disable/enable events, DEBUG_PREEMPT must be
171	  enabled. For tracing irq disable/enable events, PROVE_LOCKING must
172	  be disabled.
173
174config IRQSOFF_TRACER
175	bool "Interrupts-off Latency Tracer"
176	default n
177	depends on TRACE_IRQFLAGS_SUPPORT
178	depends on !ARCH_USES_GETTIMEOFFSET
179	select TRACE_IRQFLAGS
180	select GENERIC_TRACER
181	select TRACER_MAX_TRACE
182	select RING_BUFFER_ALLOW_SWAP
183	select TRACER_SNAPSHOT
184	select TRACER_SNAPSHOT_PER_CPU_SWAP
185	help
186	  This option measures the time spent in irqs-off critical
187	  sections, with microsecond accuracy.
188
189	  The default measurement method is a maximum search, which is
190	  disabled by default and can be runtime (re-)started
191	  via:
192
193	      echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
194
195	  (Note that kernel size and overhead increase with this option
196	  enabled. This option and the preempt-off timing option can be
197	  used together or separately.)
198
199config PREEMPT_TRACER
200	bool "Preemption-off Latency Tracer"
201	default n
202	depends on !ARCH_USES_GETTIMEOFFSET
203	depends on PREEMPT
204	select GENERIC_TRACER
205	select TRACER_MAX_TRACE
206	select RING_BUFFER_ALLOW_SWAP
207	select TRACER_SNAPSHOT
208	select TRACER_SNAPSHOT_PER_CPU_SWAP
209	help
210	  This option measures the time spent in preemption-off critical
211	  sections, with microsecond accuracy.
212
213	  The default measurement method is a maximum search, which is
214	  disabled by default and can be runtime (re-)started
215	  via:
216
217	      echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
218
219	  (Note that kernel size and overhead increase with this option
220	  enabled. This option and the irqs-off timing option can be
221	  used together or separately.)
222
223config SCHED_TRACER
224	bool "Scheduling Latency Tracer"
225	select GENERIC_TRACER
226	select CONTEXT_SWITCH_TRACER
227	select TRACER_MAX_TRACE
228	select TRACER_SNAPSHOT
229	help
230	  This tracer tracks the latency of the highest priority task
231	  to be scheduled in, starting from the point it has woken up.
232
233config HWLAT_TRACER
234	bool "Tracer to detect hardware latencies (like SMIs)"
235	select GENERIC_TRACER
236	help
237	 This tracer, when enabled will create one or more kernel threads,
238	 depending on what the cpumask file is set to, which each thread
239	 spinning in a loop looking for interruptions caused by
240	 something other than the kernel. For example, if a
241	 System Management Interrupt (SMI) takes a noticeable amount of
242	 time, this tracer will detect it. This is useful for testing
243	 if a system is reliable for Real Time tasks.
244
245	 Some files are created in the tracing directory when this
246	 is enabled:
247
248	   hwlat_detector/width   - time in usecs for how long to spin for
249	   hwlat_detector/window  - time in usecs between the start of each
250				     iteration
251
252	 A kernel thread is created that will spin with interrupts disabled
253	 for "width" microseconds in every "window" cycle. It will not spin
254	 for "window - width" microseconds, where the system can
255	 continue to operate.
256
257	 The output will appear in the trace and trace_pipe files.
258
259	 When the tracer is not running, it has no affect on the system,
260	 but when it is running, it can cause the system to be
261	 periodically non responsive. Do not run this tracer on a
262	 production system.
263
264	 To enable this tracer, echo in "hwlat" into the current_tracer
265	 file. Every time a latency is greater than tracing_thresh, it will
266	 be recorded into the ring buffer.
267
268config ENABLE_DEFAULT_TRACERS
269	bool "Trace process context switches and events"
270	depends on !GENERIC_TRACER
271	select TRACING
272	help
273	  This tracer hooks to various trace points in the kernel,
274	  allowing the user to pick and choose which trace point they
275	  want to trace. It also includes the sched_switch tracer plugin.
276
277config FTRACE_SYSCALLS
278	bool "Trace syscalls"
279	depends on HAVE_SYSCALL_TRACEPOINTS
280	select GENERIC_TRACER
281	select KALLSYMS
282	help
283	  Basic tracer to catch the syscall entry and exit events.
284
285config TRACER_SNAPSHOT
286	bool "Create a snapshot trace buffer"
287	select TRACER_MAX_TRACE
288	help
289	  Allow tracing users to take snapshot of the current buffer using the
290	  ftrace interface, e.g.:
291
292	      echo 1 > /sys/kernel/debug/tracing/snapshot
293	      cat snapshot
294
295config TRACER_SNAPSHOT_PER_CPU_SWAP
296        bool "Allow snapshot to swap per CPU"
297	depends on TRACER_SNAPSHOT
298	select RING_BUFFER_ALLOW_SWAP
299	help
300	  Allow doing a snapshot of a single CPU buffer instead of a
301	  full swap (all buffers). If this is set, then the following is
302	  allowed:
303
304	      echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot
305
306	  After which, only the tracing buffer for CPU 2 was swapped with
307	  the main tracing buffer, and the other CPU buffers remain the same.
308
309	  When this is enabled, this adds a little more overhead to the
310	  trace recording, as it needs to add some checks to synchronize
311	  recording with swaps. But this does not affect the performance
312	  of the overall system. This is enabled by default when the preempt
313	  or irq latency tracers are enabled, as those need to swap as well
314	  and already adds the overhead (plus a lot more).
315
316config TRACE_BRANCH_PROFILING
317	bool
318	select GENERIC_TRACER
319
320choice
321	prompt "Branch Profiling"
322	default BRANCH_PROFILE_NONE
323	help
324	 The branch profiling is a software profiler. It will add hooks
325	 into the C conditionals to test which path a branch takes.
326
327	 The likely/unlikely profiler only looks at the conditions that
328	 are annotated with a likely or unlikely macro.
329
330	 The "all branch" profiler will profile every if-statement in the
331	 kernel. This profiler will also enable the likely/unlikely
332	 profiler.
333
334	 Either of the above profilers adds a bit of overhead to the system.
335	 If unsure, choose "No branch profiling".
336
337config BRANCH_PROFILE_NONE
338	bool "No branch profiling"
339	help
340	  No branch profiling. Branch profiling adds a bit of overhead.
341	  Only enable it if you want to analyse the branching behavior.
342	  Otherwise keep it disabled.
343
344config PROFILE_ANNOTATED_BRANCHES
345	bool "Trace likely/unlikely profiler"
346	select TRACE_BRANCH_PROFILING
347	help
348	  This tracer profiles all likely and unlikely macros
349	  in the kernel. It will display the results in:
350
351	  /sys/kernel/debug/tracing/trace_stat/branch_annotated
352
353	  Note: this will add a significant overhead; only turn this
354	  on if you need to profile the system's use of these macros.
355
356config PROFILE_ALL_BRANCHES
357	bool "Profile all if conditionals"
358	select TRACE_BRANCH_PROFILING
359	help
360	  This tracer profiles all branch conditions. Every if ()
361	  taken in the kernel is recorded whether it hit or miss.
362	  The results will be displayed in:
363
364	  /sys/kernel/debug/tracing/trace_stat/branch_all
365
366	  This option also enables the likely/unlikely profiler.
367
368	  This configuration, when enabled, will impose a great overhead
369	  on the system. This should only be enabled when the system
370	  is to be analyzed in much detail.
371endchoice
372
373config TRACING_BRANCHES
374	bool
375	help
376	  Selected by tracers that will trace the likely and unlikely
377	  conditions. This prevents the tracers themselves from being
378	  profiled. Profiling the tracing infrastructure can only happen
379	  when the likelys and unlikelys are not being traced.
380
381config BRANCH_TRACER
382	bool "Trace likely/unlikely instances"
383	depends on TRACE_BRANCH_PROFILING
384	select TRACING_BRANCHES
385	help
386	  This traces the events of likely and unlikely condition
387	  calls in the kernel.  The difference between this and the
388	  "Trace likely/unlikely profiler" is that this is not a
389	  histogram of the callers, but actually places the calling
390	  events into a running trace buffer to see when and where the
391	  events happened, as well as their results.
392
393	  Say N if unsure.
394
395config STACK_TRACER
396	bool "Trace max stack"
397	depends on HAVE_FUNCTION_TRACER
398	select FUNCTION_TRACER
399	select STACKTRACE
400	select KALLSYMS
401	help
402	  This special tracer records the maximum stack footprint of the
403	  kernel and displays it in /sys/kernel/debug/tracing/stack_trace.
404
405	  This tracer works by hooking into every function call that the
406	  kernel executes, and keeping a maximum stack depth value and
407	  stack-trace saved.  If this is configured with DYNAMIC_FTRACE
408	  then it will not have any overhead while the stack tracer
409	  is disabled.
410
411	  To enable the stack tracer on bootup, pass in 'stacktrace'
412	  on the kernel command line.
413
414	  The stack tracer can also be enabled or disabled via the
415	  sysctl kernel.stack_tracer_enabled
416
417	  Say N if unsure.
418
419config BLK_DEV_IO_TRACE
420	bool "Support for tracing block IO actions"
421	depends on SYSFS
422	depends on BLOCK
423	select RELAY
424	select DEBUG_FS
425	select TRACEPOINTS
426	select GENERIC_TRACER
427	select STACKTRACE
428	help
429	  Say Y here if you want to be able to trace the block layer actions
430	  on a given queue. Tracing allows you to see any traffic happening
431	  on a block device queue. For more information (and the userspace
432	  support tools needed), fetch the blktrace tools from:
433
434	  git://git.kernel.dk/blktrace.git
435
436	  Tracing also is possible using the ftrace interface, e.g.:
437
438	    echo 1 > /sys/block/sda/sda1/trace/enable
439	    echo blk > /sys/kernel/debug/tracing/current_tracer
440	    cat /sys/kernel/debug/tracing/trace_pipe
441
442	  If unsure, say N.
443
444config KPROBE_EVENTS
445	depends on KPROBES
446	depends on HAVE_REGS_AND_STACK_ACCESS_API
447	bool "Enable kprobes-based dynamic events"
448	select TRACING
449	select PROBE_EVENTS
450	default y
451	help
452	  This allows the user to add tracing events (similar to tracepoints)
453	  on the fly via the ftrace interface. See
454	  Documentation/trace/kprobetrace.txt for more details.
455
456	  Those events can be inserted wherever kprobes can probe, and record
457	  various register and memory values.
458
459	  This option is also required by perf-probe subcommand of perf tools.
460	  If you want to use perf tools, this option is strongly recommended.
461
462config UPROBE_EVENTS
463	bool "Enable uprobes-based dynamic events"
464	depends on ARCH_SUPPORTS_UPROBES
465	depends on MMU
466	depends on PERF_EVENTS
467	select UPROBES
468	select PROBE_EVENTS
469	select TRACING
470	default y
471	help
472	  This allows the user to add tracing events on top of userspace
473	  dynamic events (similar to tracepoints) on the fly via the trace
474	  events interface. Those events can be inserted wherever uprobes
475	  can probe, and record various registers.
476	  This option is required if you plan to use perf-probe subcommand
477	  of perf tools on user space applications.
478
479config BPF_EVENTS
480	depends on BPF_SYSCALL
481	depends on (KPROBE_EVENTS || UPROBE_EVENTS) && PERF_EVENTS
482	bool
483	default y
484	help
485	  This allows the user to attach BPF programs to kprobe events.
486
487config PROBE_EVENTS
488	def_bool n
489
490config DYNAMIC_FTRACE
491	bool "enable/disable function tracing dynamically"
492	depends on FUNCTION_TRACER
493	depends on HAVE_DYNAMIC_FTRACE
494	default y
495	help
496	  This option will modify all the calls to function tracing
497	  dynamically (will patch them out of the binary image and
498	  replace them with a No-Op instruction) on boot up. During
499	  compile time, a table is made of all the locations that ftrace
500	  can function trace, and this table is linked into the kernel
501	  image. When this is enabled, functions can be individually
502	  enabled, and the functions not enabled will not affect
503	  performance of the system.
504
505	  See the files in /sys/kernel/debug/tracing:
506	    available_filter_functions
507	    set_ftrace_filter
508	    set_ftrace_notrace
509
510	  This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but
511	  otherwise has native performance as long as no tracing is active.
512
513config DYNAMIC_FTRACE_WITH_REGS
514	def_bool y
515	depends on DYNAMIC_FTRACE
516	depends on HAVE_DYNAMIC_FTRACE_WITH_REGS
517
518config FUNCTION_PROFILER
519	bool "Kernel function profiler"
520	depends on FUNCTION_TRACER
521	default n
522	help
523	  This option enables the kernel function profiler. A file is created
524	  in debugfs called function_profile_enabled which defaults to zero.
525	  When a 1 is echoed into this file profiling begins, and when a
526	  zero is entered, profiling stops. A "functions" file is created in
527	  the trace_stats directory; this file shows the list of functions that
528	  have been hit and their counters.
529
530	  If in doubt, say N.
531
532config FTRACE_MCOUNT_RECORD
533	def_bool y
534	depends on DYNAMIC_FTRACE
535	depends on HAVE_FTRACE_MCOUNT_RECORD
536
537config FTRACE_SELFTEST
538	bool
539
540config FTRACE_STARTUP_TEST
541	bool "Perform a startup test on ftrace"
542	depends on GENERIC_TRACER
543	select FTRACE_SELFTEST
544	help
545	  This option performs a series of startup tests on ftrace. On bootup
546	  a series of tests are made to verify that the tracer is
547	  functioning properly. It will do tests on all the configured
548	  tracers of ftrace.
549
550config EVENT_TRACE_TEST_SYSCALLS
551	bool "Run selftest on syscall events"
552	depends on FTRACE_STARTUP_TEST
553	help
554	 This option will also enable testing every syscall event.
555	 It only enables the event and disables it and runs various loads
556	 with the event enabled. This adds a bit more time for kernel boot
557	 up since it runs this on every system call defined.
558
559	 TBD - enable a way to actually call the syscalls as we test their
560	       events
561
562config MMIOTRACE
563	bool "Memory mapped IO tracing"
564	depends on HAVE_MMIOTRACE_SUPPORT && PCI
565	select GENERIC_TRACER
566	help
567	  Mmiotrace traces Memory Mapped I/O access and is meant for
568	  debugging and reverse engineering. It is called from the ioremap
569	  implementation and works via page faults. Tracing is disabled by
570	  default and can be enabled at run-time.
571
572	  See Documentation/trace/mmiotrace.txt.
573	  If you are not helping to develop drivers, say N.
574
575config TRACING_MAP
576	bool
577	depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
578	help
579	  tracing_map is a special-purpose lock-free map for tracing,
580	  separated out as a stand-alone facility in order to allow it
581	  to be shared between multiple tracers.  It isn't meant to be
582	  generally used outside of that context, and is normally
583	  selected by tracers that use it.
584
585config HIST_TRIGGERS
586	bool "Histogram triggers"
587	depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
588	select TRACING_MAP
589	select TRACING
590	default n
591	help
592	  Hist triggers allow one or more arbitrary trace event fields
593	  to be aggregated into hash tables and dumped to stdout by
594	  reading a debugfs/tracefs file.  They're useful for
595	  gathering quick and dirty (though precise) summaries of
596	  event activity as an initial guide for further investigation
597	  using more advanced tools.
598
599	  See Documentation/trace/events.txt.
600	  If in doubt, say N.
601
602config MMIOTRACE_TEST
603	tristate "Test module for mmiotrace"
604	depends on MMIOTRACE && m
605	help
606	  This is a dumb module for testing mmiotrace. It is very dangerous
607	  as it will write garbage to IO memory starting at a given address.
608	  However, it should be safe to use on e.g. unused portion of VRAM.
609
610	  Say N, unless you absolutely know what you are doing.
611
612config TRACEPOINT_BENCHMARK
613        bool "Add tracepoint that benchmarks tracepoints"
614	help
615	 This option creates the tracepoint "benchmark:benchmark_event".
616	 When the tracepoint is enabled, it kicks off a kernel thread that
617	 goes into an infinite loop (calling cond_sched() to let other tasks
618	 run), and calls the tracepoint. Each iteration will record the time
619	 it took to write to the tracepoint and the next iteration that
620	 data will be passed to the tracepoint itself. That is, the tracepoint
621	 will report the time it took to do the previous tracepoint.
622	 The string written to the tracepoint is a static string of 128 bytes
623	 to keep the time the same. The initial string is simply a write of
624	 "START". The second string records the cold cache time of the first
625	 write which is not added to the rest of the calculations.
626
627	 As it is a tight loop, it benchmarks as hot cache. That's fine because
628	 we care most about hot paths that are probably in cache already.
629
630	 An example of the output:
631
632	      START
633	      first=3672 [COLD CACHED]
634	      last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712
635	      last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337
636	      last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064
637	      last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411
638	      last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389
639	      last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666
640
641
642config RING_BUFFER_BENCHMARK
643	tristate "Ring buffer benchmark stress tester"
644	depends on RING_BUFFER
645	help
646	  This option creates a test to stress the ring buffer and benchmark it.
647	  It creates its own ring buffer such that it will not interfere with
648	  any other users of the ring buffer (such as ftrace). It then creates
649	  a producer and consumer that will run for 10 seconds and sleep for
650	  10 seconds. Each interval it will print out the number of events
651	  it recorded and give a rough estimate of how long each iteration took.
652
653	  It does not disable interrupts or raise its priority, so it may be
654	  affected by processes that are running.
655
656	  If unsure, say N.
657
658config RING_BUFFER_STARTUP_TEST
659       bool "Ring buffer startup self test"
660       depends on RING_BUFFER
661       help
662         Run a simple self test on the ring buffer on boot up. Late in the
663	 kernel boot sequence, the test will start that kicks off
664	 a thread per cpu. Each thread will write various size events
665	 into the ring buffer. Another thread is created to send IPIs
666	 to each of the threads, where the IPI handler will also write
667	 to the ring buffer, to test/stress the nesting ability.
668	 If any anomalies are discovered, a warning will be displayed
669	 and all ring buffers will be disabled.
670
671	 The test runs for 10 seconds. This will slow your boot time
672	 by at least 10 more seconds.
673
674	 At the end of the test, statics and more checks are done.
675	 It will output the stats of each per cpu buffer. What
676	 was written, the sizes, what was read, what was lost, and
677	 other similar details.
678
679	 If unsure, say N
680
681config TRACE_EVAL_MAP_FILE
682       bool "Show eval mappings for trace events"
683       depends on TRACING
684       help
685	The "print fmt" of the trace events will show the enum/sizeof names
686	instead	of their values. This can cause problems for user space tools
687	that use this string to parse the raw data as user space does not know
688	how to convert the string to its value.
689
690	To fix this, there's a special macro in the kernel that can be used
691	to convert an enum/sizeof into its value. If this macro is used, then
692	the print fmt strings will be converted to their values.
693
694	If something does not get converted properly, this option can be
695	used to show what enums/sizeof the kernel tried to convert.
696
697	This option is for debugging the conversions. A file is created
698	in the tracing directory called "eval_map" that will show the
699	names matched with their values and what trace event system they
700	belong too.
701
702	Normally, the mapping of the strings to values will be freed after
703	boot up or module load. With this option, they will not be freed, as
704	they are needed for the "eval_map" file. Enabling this option will
705	increase the memory footprint of the running kernel.
706
707	If unsure, say N
708
709config TRACING_EVENTS_GPIO
710	bool "Trace gpio events"
711	depends on GPIOLIB
712	default y
713	help
714	  Enable tracing events for gpio subsystem
715
716endif # FTRACE
717
718endif # TRACING_SUPPORT
719
720