xref: /linux/init/Kconfig (revision 4b81e2eb9e4db8f6094c077d0c8b27c264901c1b)
1# SPDX-License-Identifier: GPL-2.0-only
2config CC_VERSION_TEXT
3	string
4	default "$(CC_VERSION_TEXT)"
5	help
6	  This is used in unclear ways:
7
8	  - Re-run Kconfig when the compiler is updated
9	    The 'default' property references the environment variable,
10	    CC_VERSION_TEXT so it is recorded in include/config/auto.conf.cmd.
11	    When the compiler is updated, Kconfig will be invoked.
12
13	  - Ensure full rebuild when the compiler is updated
14	    include/linux/compiler-version.h contains this option in the comment
15	    line so fixdep adds include/config/CC_VERSION_TEXT into the
16	    auto-generated dependency. When the compiler is updated, syncconfig
17	    will touch it and then every file will be rebuilt.
18
19config CC_IS_GCC
20	def_bool $(success,test "$(cc-name)" = GCC)
21
22config GCC_VERSION
23	int
24	default $(cc-version) if CC_IS_GCC
25	default 0
26
27config CC_IS_CLANG
28	def_bool $(success,test "$(cc-name)" = Clang)
29
30config CLANG_VERSION
31	int
32	default $(cc-version) if CC_IS_CLANG
33	default 0
34
35config AS_IS_GNU
36	def_bool $(success,test "$(as-name)" = GNU)
37
38config AS_IS_LLVM
39	def_bool $(success,test "$(as-name)" = LLVM)
40
41config AS_VERSION
42	int
43	# Use clang version if this is the integrated assembler
44	default CLANG_VERSION if AS_IS_LLVM
45	default $(as-version)
46
47config LD_IS_BFD
48	def_bool $(success,test "$(ld-name)" = BFD)
49
50config LD_VERSION
51	int
52	default $(ld-version) if LD_IS_BFD
53	default 0
54
55config LD_IS_LLD
56	def_bool $(success,test "$(ld-name)" = LLD)
57
58config LLD_VERSION
59	int
60	default $(ld-version) if LD_IS_LLD
61	default 0
62
63config RUSTC_VERSION
64	int
65	default $(rustc-version)
66	help
67	  It does not depend on `RUST` since that one may need to use the version
68	  in a `depends on`.
69
70config RUST_IS_AVAILABLE
71	def_bool $(success,$(srctree)/scripts/rust_is_available.sh)
72	help
73	  This shows whether a suitable Rust toolchain is available (found).
74
75	  Please see Documentation/rust/quick-start.rst for instructions on how
76	  to satisfy the build requirements of Rust support.
77
78	  In particular, the Makefile target 'rustavailable' is useful to check
79	  why the Rust toolchain is not being detected.
80
81config RUSTC_LLVM_VERSION
82	int
83	default $(rustc-llvm-version)
84
85config CC_CAN_LINK
86	bool
87	default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag)) if 64BIT
88	default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag))
89
90# Fixed in GCC 14, 13.3, 12.4 and 11.5
91# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921
92config GCC_ASM_GOTO_OUTPUT_BROKEN
93	bool
94	depends on CC_IS_GCC
95	default y if GCC_VERSION < 110500
96	default y if GCC_VERSION >= 120000 && GCC_VERSION < 120400
97	default y if GCC_VERSION >= 130000 && GCC_VERSION < 130300
98
99config CC_HAS_ASM_GOTO_OUTPUT
100	def_bool y
101	depends on !GCC_ASM_GOTO_OUTPUT_BROKEN
102	# Detect basic support
103	depends on $(success,echo 'int foo(int x) { asm goto ("": "=r"(x) ::: bar); return x; bar: return 0; }' | $(CC) -x c - -c -o /dev/null)
104	# Detect clang (< v17) scoped label issues
105	depends on $(success,echo 'void b(void **);void* c(void);int f(void){{asm goto(""::::l0);return 0;l0:return 1;}void *x __attribute__((cleanup(b)))=c();{asm goto(""::::l1);return 2;l1:return 3;}}' | $(CC) -x c - -c -o /dev/null)
106
107config CC_HAS_ASM_GOTO_TIED_OUTPUT
108	depends on CC_HAS_ASM_GOTO_OUTPUT
109	# Detect buggy gcc and clang, fixed in gcc-11 clang-14.
110	def_bool $(success,echo 'int foo(int *x) { asm goto (".long (%l[bar]) - .": "+m"(*x) ::: bar); return *x; bar: return 0; }' | $CC -x c - -c -o /dev/null)
111
112config TOOLS_SUPPORT_RELR
113	def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
114
115config CC_HAS_ASM_INLINE
116	def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
117
118config CC_HAS_ASSUME
119	bool
120	# clang needs to be at least 19.1.0 since the meaning of the assume
121	# attribute changed:
122	# https://github.com/llvm/llvm-project/commit/c44fa3e8a9a44c2e9a575768a3c185354b9f6c17
123	default y if CC_IS_CLANG && CLANG_VERSION >= 190100
124	# supported since gcc 13.1.0
125	# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106654
126	default y if CC_IS_GCC && GCC_VERSION >= 130100
127
128config CC_HAS_NO_PROFILE_FN_ATTR
129	def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
130
131config CC_HAS_COUNTED_BY
132	bool
133	# clang needs to be at least 20.1.0 to avoid potential crashes
134	# when building structures that contain __counted_by
135	# https://github.com/ClangBuiltLinux/linux/issues/2114
136	# https://github.com/llvm/llvm-project/commit/160fb1121cdf703c3ef5e61fb26c5659eb581489
137	default y if CC_IS_CLANG && CLANG_VERSION >= 200100
138	# supported since gcc 15.1.0
139	# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108896
140	default y if CC_IS_GCC && GCC_VERSION >= 150100
141
142config CC_HAS_MULTIDIMENSIONAL_NONSTRING
143	def_bool $(success,echo 'char tag[][4] __attribute__((__nonstring__)) = { };' | $(CC) $(CLANG_FLAGS) -x c - -c -o /dev/null -Werror)
144
145config LD_CAN_USE_KEEP_IN_OVERLAY
146	# ld.lld prior to 21.0.0 did not support KEEP within an overlay description
147	# https://github.com/llvm/llvm-project/pull/130661
148	def_bool LD_IS_BFD || LLD_VERSION >= 210000
149
150config RUSTC_HAS_COERCE_POINTEE
151	def_bool RUSTC_VERSION >= 108400
152
153config RUSTC_HAS_SPAN_FILE
154	def_bool RUSTC_VERSION >= 108800
155
156config RUSTC_HAS_UNNECESSARY_TRANSMUTES
157	def_bool RUSTC_VERSION >= 108800
158
159config RUSTC_HAS_FILE_WITH_NUL
160	def_bool RUSTC_VERSION >= 108900
161
162config RUSTC_HAS_FILE_AS_C_STR
163	def_bool RUSTC_VERSION >= 109100
164
165config PAHOLE_VERSION
166	int
167	default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE))
168
169config CONSTRUCTORS
170	bool
171
172config IRQ_WORK
173	def_bool y if SMP
174
175config BUILDTIME_TABLE_SORT
176	bool
177
178config THREAD_INFO_IN_TASK
179	bool
180	help
181	  Select this to move thread_info off the stack into task_struct.  To
182	  make this work, an arch will need to remove all thread_info fields
183	  except flags and fix any runtime bugs.
184
185	  One subtle change that will be needed is to use try_get_task_stack()
186	  and put_task_stack() in save_thread_stack_tsk() and get_wchan().
187
188menu "General setup"
189
190config BROKEN
191	bool
192	help
193	  This option allows you to choose whether you want to try to
194	  compile (and fix) old drivers that haven't been updated to
195	  new infrastructure.
196
197config BROKEN_ON_SMP
198	bool
199	depends on BROKEN || !SMP
200	default y
201
202config INIT_ENV_ARG_LIMIT
203	int
204	default 32 if !UML
205	default 128 if UML
206	help
207	  Maximum of each of the number of arguments and environment
208	  variables passed to init from the kernel command line.
209
210config COMPILE_TEST
211	bool "Compile also drivers which will not load"
212	depends on HAS_IOMEM
213	help
214	  Some drivers can be compiled on a different platform than they are
215	  intended to be run on. Despite they cannot be loaded there (or even
216	  when they load they cannot be used due to missing HW support),
217	  developers still, opposing to distributors, might want to build such
218	  drivers to compile-test them.
219
220	  If you are a developer and want to build everything available, say Y
221	  here. If you are a user/distributor, say N here to exclude useless
222	  drivers to be distributed.
223
224config WERROR
225	bool "Compile the kernel with warnings as errors"
226	default COMPILE_TEST
227	help
228	  A kernel build should not cause any compiler warnings, and this
229	  enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags
230	  to enforce that rule by default. Certain warnings from other tools
231	  such as the linker may be upgraded to errors with this option as
232	  well.
233
234	  However, if you have a new (or very old) compiler or linker with odd
235	  and unusual warnings, or you have some architecture with problems,
236	  you may need to disable this config option in order to
237	  successfully build the kernel.
238
239	  If in doubt, say Y.
240
241config UAPI_HEADER_TEST
242	bool "Compile test UAPI headers"
243	depends on HEADERS_INSTALL && CC_CAN_LINK
244	help
245	  Compile test headers exported to user-space to ensure they are
246	  self-contained, i.e. compilable as standalone units.
247
248	  If you are a developer or tester and want to ensure the exported
249	  headers are self-contained, say Y here. Otherwise, choose N.
250
251config LOCALVERSION
252	string "Local version - append to kernel release"
253	help
254	  Append an extra string to the end of your kernel version.
255	  This will show up when you type uname, for example.
256	  The string you set here will be appended after the contents of
257	  any files with a filename matching localversion* in your
258	  object and source tree, in that order.  Your total string can
259	  be a maximum of 64 characters.
260
261config LOCALVERSION_AUTO
262	bool "Automatically append version information to the version string"
263	default y
264	depends on !COMPILE_TEST
265	help
266	  This will try to automatically determine if the current tree is a
267	  release tree by looking for git tags that belong to the current
268	  top of tree revision.
269
270	  A string of the format -gxxxxxxxx will be added to the localversion
271	  if a git-based tree is found.  The string generated by this will be
272	  appended after any matching localversion* files, and after the value
273	  set in CONFIG_LOCALVERSION.
274
275	  (The actual string used here is the first 12 characters produced
276	  by running the command:
277
278	    $ git rev-parse --verify HEAD
279
280	  which is done within the script "scripts/setlocalversion".)
281
282config BUILD_SALT
283	string "Build ID Salt"
284	default ""
285	help
286	  The build ID is used to link binaries and their debug info. Setting
287	  this option will use the value in the calculation of the build id.
288	  This is mostly useful for distributions which want to ensure the
289	  build is unique between builds. It's safe to leave the default.
290
291config HAVE_KERNEL_GZIP
292	bool
293
294config HAVE_KERNEL_BZIP2
295	bool
296
297config HAVE_KERNEL_LZMA
298	bool
299
300config HAVE_KERNEL_XZ
301	bool
302
303config HAVE_KERNEL_LZO
304	bool
305
306config HAVE_KERNEL_LZ4
307	bool
308
309config HAVE_KERNEL_ZSTD
310	bool
311
312config HAVE_KERNEL_UNCOMPRESSED
313	bool
314
315choice
316	prompt "Kernel compression mode"
317	default KERNEL_GZIP
318	depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 || HAVE_KERNEL_ZSTD || HAVE_KERNEL_UNCOMPRESSED
319	help
320	  The linux kernel is a kind of self-extracting executable.
321	  Several compression algorithms are available, which differ
322	  in efficiency, compression and decompression speed.
323	  Compression speed is only relevant when building a kernel.
324	  Decompression speed is relevant at each boot.
325
326	  If you have any problems with bzip2 or lzma compressed
327	  kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
328	  version of this functionality (bzip2 only), for 2.4, was
329	  supplied by Christian Ludwig)
330
331	  High compression options are mostly useful for users, who
332	  are low on disk space (embedded systems), but for whom ram
333	  size matters less.
334
335	  If in doubt, select 'gzip'
336
337config KERNEL_GZIP
338	bool "Gzip"
339	depends on HAVE_KERNEL_GZIP
340	help
341	  The old and tried gzip compression. It provides a good balance
342	  between compression ratio and decompression speed.
343
344config KERNEL_BZIP2
345	bool "Bzip2"
346	depends on HAVE_KERNEL_BZIP2
347	help
348	  Its compression ratio and speed is intermediate.
349	  Decompression speed is slowest among the choices.  The kernel
350	  size is about 10% smaller with bzip2, in comparison to gzip.
351	  Bzip2 uses a large amount of memory. For modern kernels you
352	  will need at least 8MB RAM or more for booting.
353
354config KERNEL_LZMA
355	bool "LZMA"
356	depends on HAVE_KERNEL_LZMA
357	help
358	  This compression algorithm's ratio is best.  Decompression speed
359	  is between gzip and bzip2.  Compression is slowest.
360	  The kernel size is about 33% smaller with LZMA in comparison to gzip.
361
362config KERNEL_XZ
363	bool "XZ"
364	depends on HAVE_KERNEL_XZ
365	help
366	  XZ uses the LZMA2 algorithm and instruction set specific
367	  BCJ filters which can improve compression ratio of executable
368	  code. The size of the kernel is about 30% smaller with XZ in
369	  comparison to gzip. On architectures for which there is a BCJ
370	  filter (i386, x86_64, ARM, ARM64, RISC-V, big endian PowerPC,
371	  and SPARC), XZ will create a few percent smaller kernel than
372	  plain LZMA.
373
374	  The speed is about the same as with LZMA: The decompression
375	  speed of XZ is better than that of bzip2 but worse than gzip
376	  and LZO. Compression is slow.
377
378config KERNEL_LZO
379	bool "LZO"
380	depends on HAVE_KERNEL_LZO
381	help
382	  Its compression ratio is the poorest among the choices. The kernel
383	  size is about 10% bigger than gzip; however its speed
384	  (both compression and decompression) is the fastest.
385
386config KERNEL_LZ4
387	bool "LZ4"
388	depends on HAVE_KERNEL_LZ4
389	help
390	  LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
391	  A preliminary version of LZ4 de/compression tool is available at
392	  <https://code.google.com/p/lz4/>.
393
394	  Its compression ratio is worse than LZO. The size of the kernel
395	  is about 8% bigger than LZO. But the decompression speed is
396	  faster than LZO.
397
398config KERNEL_ZSTD
399	bool "ZSTD"
400	depends on HAVE_KERNEL_ZSTD
401	help
402	  ZSTD is a compression algorithm targeting intermediate compression
403	  with fast decompression speed. It will compress better than GZIP and
404	  decompress around the same speed as LZO, but slower than LZ4. You
405	  will need at least 192 KB RAM or more for booting. The zstd command
406	  line tool is required for compression.
407
408config KERNEL_UNCOMPRESSED
409	bool "None"
410	depends on HAVE_KERNEL_UNCOMPRESSED
411	help
412	  Produce uncompressed kernel image. This option is usually not what
413	  you want. It is useful for debugging the kernel in slow simulation
414	  environments, where decompressing and moving the kernel is awfully
415	  slow. This option allows early boot code to skip the decompressor
416	  and jump right at uncompressed kernel image.
417
418endchoice
419
420config DEFAULT_INIT
421	string "Default init path"
422	default ""
423	help
424	  This option determines the default init for the system if no init=
425	  option is passed on the kernel command line. If the requested path is
426	  not present, we will still then move on to attempting further
427	  locations (e.g. /sbin/init, etc). If this is empty, we will just use
428	  the fallback list when init= is not passed.
429
430config DEFAULT_HOSTNAME
431	string "Default hostname"
432	default "(none)"
433	help
434	  This option determines the default system hostname before userspace
435	  calls sethostname(2). The kernel traditionally uses "(none)" here,
436	  but you may wish to use a different default here to make a minimal
437	  system more usable with less configuration.
438
439config SYSVIPC
440	bool "System V IPC"
441	help
442	  Inter Process Communication is a suite of library functions and
443	  system calls which let processes (running programs) synchronize and
444	  exchange information. It is generally considered to be a good thing,
445	  and some programs won't run unless you say Y here. In particular, if
446	  you want to run the DOS emulator dosemu under Linux (read the
447	  DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
448	  you'll need to say Y here.
449
450	  You can find documentation about IPC with "info ipc" and also in
451	  section 6.4 of the Linux Programmer's Guide, available from
452	  <http://www.tldp.org/guides.html>.
453
454config SYSVIPC_SYSCTL
455	bool
456	depends on SYSVIPC
457	depends on SYSCTL
458	default y
459
460config SYSVIPC_COMPAT
461	def_bool y
462	depends on COMPAT && SYSVIPC
463
464config POSIX_MQUEUE
465	bool "POSIX Message Queues"
466	depends on NET
467	help
468	  POSIX variant of message queues is a part of IPC. In POSIX message
469	  queues every message has a priority which decides about succession
470	  of receiving it by a process. If you want to compile and run
471	  programs written e.g. for Solaris with use of its POSIX message
472	  queues (functions mq_*) say Y here.
473
474	  POSIX message queues are visible as a filesystem called 'mqueue'
475	  and can be mounted somewhere if you want to do filesystem
476	  operations on message queues.
477
478	  If unsure, say Y.
479
480config POSIX_MQUEUE_SYSCTL
481	bool
482	depends on POSIX_MQUEUE
483	depends on SYSCTL
484	default y
485
486config WATCH_QUEUE
487	bool "General notification queue"
488	default n
489	help
490
491	  This is a general notification queue for the kernel to pass events to
492	  userspace by splicing them into pipes.  It can be used in conjunction
493	  with watches for key/keyring change notifications and device
494	  notifications.
495
496	  See Documentation/core-api/watch_queue.rst
497
498config CROSS_MEMORY_ATTACH
499	bool "Enable process_vm_readv/writev syscalls"
500	depends on MMU
501	default y
502	help
503	  Enabling this option adds the system calls process_vm_readv and
504	  process_vm_writev which allow a process with the correct privileges
505	  to directly read from or write to another process' address space.
506	  See the man page for more details.
507
508config AUDIT
509	bool "Auditing support"
510	depends on NET
511	help
512	  Enable auditing infrastructure that can be used with another
513	  kernel subsystem, such as SELinux (which requires this for
514	  logging of avc messages output).  System call auditing is included
515	  on architectures which support it.
516
517config HAVE_ARCH_AUDITSYSCALL
518	bool
519
520config AUDITSYSCALL
521	def_bool y
522	depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
523	select FSNOTIFY
524
525source "kernel/irq/Kconfig"
526source "kernel/time/Kconfig"
527source "kernel/bpf/Kconfig"
528source "kernel/Kconfig.preempt"
529
530menu "CPU/Task time and stats accounting"
531
532config VIRT_CPU_ACCOUNTING
533	bool
534
535choice
536	prompt "Cputime accounting"
537	default TICK_CPU_ACCOUNTING
538
539# Kind of a stub config for the pure tick based cputime accounting
540config TICK_CPU_ACCOUNTING
541	bool "Simple tick based cputime accounting"
542	depends on !S390 && !NO_HZ_FULL
543	help
544	  This is the basic tick based cputime accounting that maintains
545	  statistics about user, system and idle time spent on per jiffies
546	  granularity.
547
548	  If unsure, say Y.
549
550config VIRT_CPU_ACCOUNTING_NATIVE
551	bool "Deterministic task and CPU time accounting"
552	depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
553	select VIRT_CPU_ACCOUNTING
554	help
555	  Select this option to enable more accurate task and CPU time
556	  accounting.  This is done by reading a CPU counter on each
557	  kernel entry and exit and on transitions within the kernel
558	  between system, softirq and hardirq state, so there is a
559	  small performance impact.  In the case of s390 or IBM POWER > 5,
560	  this also enables accounting of stolen time on logically-partitioned
561	  systems.
562
563config VIRT_CPU_ACCOUNTING_GEN
564	bool "Full dynticks CPU time accounting"
565	depends on HAVE_CONTEXT_TRACKING_USER
566	depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
567	depends on GENERIC_CLOCKEVENTS
568	select VIRT_CPU_ACCOUNTING
569	select CONTEXT_TRACKING_USER
570	help
571	  Select this option to enable task and CPU time accounting on full
572	  dynticks systems. This accounting is implemented by watching every
573	  kernel-user boundaries using the context tracking subsystem.
574	  The accounting is thus performed at the expense of some significant
575	  overhead.
576
577	  For now this is only useful if you are working on the full
578	  dynticks subsystem development.
579
580	  If unsure, say N.
581
582endchoice
583
584config IRQ_TIME_ACCOUNTING
585	bool "Fine granularity task level IRQ time accounting"
586	depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
587	help
588	  Select this option to enable fine granularity task irq time
589	  accounting. This is done by reading a timestamp on each
590	  transitions between softirq and hardirq state, so there can be a
591	  small performance impact.
592
593	  If in doubt, say N here.
594
595config HAVE_SCHED_AVG_IRQ
596	def_bool y
597	depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
598	depends on SMP
599
600config SCHED_HW_PRESSURE
601	bool
602	default y if ARM && ARM_CPU_TOPOLOGY
603	default y if ARM64
604	depends on SMP
605	depends on CPU_FREQ_THERMAL
606	help
607	  Select this option to enable HW pressure accounting in the
608	  scheduler. HW pressure is the value conveyed to the scheduler
609	  that reflects the reduction in CPU compute capacity resulted from
610	  HW throttling. HW throttling occurs when the performance of
611	  a CPU is capped due to high operating temperatures as an example.
612
613	  If selected, the scheduler will be able to balance tasks accordingly,
614	  i.e. put less load on throttled CPUs than on non/less throttled ones.
615
616	  This requires the architecture to implement
617	  arch_update_hw_pressure() and arch_scale_thermal_pressure().
618
619config BSD_PROCESS_ACCT
620	bool "BSD Process Accounting"
621	depends on MULTIUSER
622	help
623	  If you say Y here, a user level program will be able to instruct the
624	  kernel (via a special system call) to write process accounting
625	  information to a file: whenever a process exits, information about
626	  that process will be appended to the file by the kernel.  The
627	  information includes things such as creation time, owning user,
628	  command name, memory usage, controlling terminal etc. (the complete
629	  list is in the struct acct in <file:include/linux/acct.h>).  It is
630	  up to the user level program to do useful things with this
631	  information.  This is generally a good idea, so say Y.
632
633config BSD_PROCESS_ACCT_V3
634	bool "BSD Process Accounting version 3 file format"
635	depends on BSD_PROCESS_ACCT
636	default n
637	help
638	  If you say Y here, the process accounting information is written
639	  in a new file format that also logs the process IDs of each
640	  process and its parent. Note that this file format is incompatible
641	  with previous v0/v1/v2 file formats, so you will need updated tools
642	  for processing it. A preliminary version of these tools is available
643	  at <http://www.gnu.org/software/acct/>.
644
645config TASKSTATS
646	bool "Export task/process statistics through netlink"
647	depends on NET
648	depends on MULTIUSER
649	default n
650	help
651	  Export selected statistics for tasks/processes through the
652	  generic netlink interface. Unlike BSD process accounting, the
653	  statistics are available during the lifetime of tasks/processes as
654	  responses to commands. Like BSD accounting, they are sent to user
655	  space on task exit.
656
657	  Say N if unsure.
658
659config TASK_DELAY_ACCT
660	bool "Enable per-task delay accounting"
661	depends on TASKSTATS
662	select SCHED_INFO
663	help
664	  Collect information on time spent by a task waiting for system
665	  resources like cpu, synchronous block I/O completion and swapping
666	  in pages. Such statistics can help in setting a task's priorities
667	  relative to other tasks for cpu, io, rss limits etc.
668
669	  Say N if unsure.
670
671config TASK_XACCT
672	bool "Enable extended accounting over taskstats"
673	depends on TASKSTATS
674	help
675	  Collect extended task accounting data and send the data
676	  to userland for processing over the taskstats interface.
677
678	  Say N if unsure.
679
680config TASK_IO_ACCOUNTING
681	bool "Enable per-task storage I/O accounting"
682	depends on TASK_XACCT
683	help
684	  Collect information on the number of bytes of storage I/O which this
685	  task has caused.
686
687	  Say N if unsure.
688
689config PSI
690	bool "Pressure stall information tracking"
691	select KERNFS
692	help
693	  Collect metrics that indicate how overcommitted the CPU, memory,
694	  and IO capacity are in the system.
695
696	  If you say Y here, the kernel will create /proc/pressure/ with the
697	  pressure statistics files cpu, memory, and io. These will indicate
698	  the share of walltime in which some or all tasks in the system are
699	  delayed due to contention of the respective resource.
700
701	  In kernels with cgroup support, cgroups (cgroup2 only) will
702	  have cpu.pressure, memory.pressure, and io.pressure files,
703	  which aggregate pressure stalls for the grouped tasks only.
704
705	  For more details see Documentation/accounting/psi.rst.
706
707	  Say N if unsure.
708
709config PSI_DEFAULT_DISABLED
710	bool "Require boot parameter to enable pressure stall information tracking"
711	default n
712	depends on PSI
713	help
714	  If set, pressure stall information tracking will be disabled
715	  per default but can be enabled through passing psi=1 on the
716	  kernel commandline during boot.
717
718	  This feature adds some code to the task wakeup and sleep
719	  paths of the scheduler. The overhead is too low to affect
720	  common scheduling-intense workloads in practice (such as
721	  webservers, memcache), but it does show up in artificial
722	  scheduler stress tests, such as hackbench.
723
724	  If you are paranoid and not sure what the kernel will be
725	  used for, say Y.
726
727	  Say N if unsure.
728
729endmenu # "CPU/Task time and stats accounting"
730
731config CPU_ISOLATION
732	bool "CPU isolation"
733	depends on SMP
734	default y
735	help
736	  Make sure that CPUs running critical tasks are not disturbed by
737	  any source of "noise" such as unbound workqueues, timers, kthreads...
738	  Unbound jobs get offloaded to housekeeping CPUs. This is driven by
739	  the "isolcpus=" boot parameter.
740
741	  Say Y if unsure.
742
743source "kernel/rcu/Kconfig"
744
745config IKCONFIG
746	tristate "Kernel .config support"
747	help
748	  This option enables the complete Linux kernel ".config" file
749	  contents to be saved in the kernel. It provides documentation
750	  of which kernel options are used in a running kernel or in an
751	  on-disk kernel.  This information can be extracted from the kernel
752	  image file with the script scripts/extract-ikconfig and used as
753	  input to rebuild the current kernel or to build another kernel.
754	  It can also be extracted from a running kernel by reading
755	  /proc/config.gz if enabled (below).
756
757config IKCONFIG_PROC
758	bool "Enable access to .config through /proc/config.gz"
759	depends on IKCONFIG && PROC_FS
760	help
761	  This option enables access to the kernel configuration file
762	  through /proc/config.gz.
763
764config IKHEADERS
765	tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
766	depends on SYSFS
767	help
768	  This option enables access to the in-kernel headers that are generated during
769	  the build process. These can be used to build eBPF tracing programs,
770	  or similar programs.  If you build the headers as a module, a module called
771	  kheaders.ko is built which can be loaded on-demand to get access to headers.
772
773config LOG_BUF_SHIFT
774	int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
775	range 12 25
776	default 17
777	depends on PRINTK
778	help
779	  Select the minimal kernel log buffer size as a power of 2.
780	  The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
781	  parameter, see below. Any higher size also might be forced
782	  by "log_buf_len" boot parameter.
783
784	  Examples:
785		     17 => 128 KB
786		     16 => 64 KB
787		     15 => 32 KB
788		     14 => 16 KB
789		     13 =>  8 KB
790		     12 =>  4 KB
791
792config LOG_CPU_MAX_BUF_SHIFT
793	int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
794	depends on SMP
795	range 0 21
796	default 0 if BASE_SMALL
797	default 12
798	depends on PRINTK
799	help
800	  This option allows to increase the default ring buffer size
801	  according to the number of CPUs. The value defines the contribution
802	  of each CPU as a power of 2. The used space is typically only few
803	  lines however it might be much more when problems are reported,
804	  e.g. backtraces.
805
806	  The increased size means that a new buffer has to be allocated and
807	  the original static one is unused. It makes sense only on systems
808	  with more CPUs. Therefore this value is used only when the sum of
809	  contributions is greater than the half of the default kernel ring
810	  buffer as defined by LOG_BUF_SHIFT. The default values are set
811	  so that more than 16 CPUs are needed to trigger the allocation.
812
813	  Also this option is ignored when "log_buf_len" kernel parameter is
814	  used as it forces an exact (power of two) size of the ring buffer.
815
816	  The number of possible CPUs is used for this computation ignoring
817	  hotplugging making the computation optimal for the worst case
818	  scenario while allowing a simple algorithm to be used from bootup.
819
820	  Examples shift values and their meaning:
821		     17 => 128 KB for each CPU
822		     16 =>  64 KB for each CPU
823		     15 =>  32 KB for each CPU
824		     14 =>  16 KB for each CPU
825		     13 =>   8 KB for each CPU
826		     12 =>   4 KB for each CPU
827
828config PRINTK_INDEX
829	bool "Printk indexing debugfs interface"
830	depends on PRINTK && DEBUG_FS
831	help
832	  Add support for indexing of all printk formats known at compile time
833	  at <debugfs>/printk/index/<module>.
834
835	  This can be used as part of maintaining daemons which monitor
836	  /dev/kmsg, as it permits auditing the printk formats present in a
837	  kernel, allowing detection of cases where monitored printks are
838	  changed or no longer present.
839
840	  There is no additional runtime cost to printk with this enabled.
841
842#
843# Architectures with an unreliable sched_clock() should select this:
844#
845config HAVE_UNSTABLE_SCHED_CLOCK
846	bool
847
848config GENERIC_SCHED_CLOCK
849	bool
850
851menu "Scheduler features"
852
853config UCLAMP_TASK
854	bool "Enable utilization clamping for RT/FAIR tasks"
855	depends on CPU_FREQ_GOV_SCHEDUTIL
856	help
857	  This feature enables the scheduler to track the clamped utilization
858	  of each CPU based on RUNNABLE tasks scheduled on that CPU.
859
860	  With this option, the user can specify the min and max CPU
861	  utilization allowed for RUNNABLE tasks. The max utilization defines
862	  the maximum frequency a task should use while the min utilization
863	  defines the minimum frequency it should use.
864
865	  Both min and max utilization clamp values are hints to the scheduler,
866	  aiming at improving its frequency selection policy, but they do not
867	  enforce or grant any specific bandwidth for tasks.
868
869	  If in doubt, say N.
870
871config UCLAMP_BUCKETS_COUNT
872	int "Number of supported utilization clamp buckets"
873	range 5 20
874	default 5
875	depends on UCLAMP_TASK
876	help
877	  Defines the number of clamp buckets to use. The range of each bucket
878	  will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
879	  number of clamp buckets the finer their granularity and the higher
880	  the precision of clamping aggregation and tracking at run-time.
881
882	  For example, with the minimum configuration value we will have 5
883	  clamp buckets tracking 20% utilization each. A 25% boosted tasks will
884	  be refcounted in the [20..39]% bucket and will set the bucket clamp
885	  effective value to 25%.
886	  If a second 30% boosted task should be co-scheduled on the same CPU,
887	  that task will be refcounted in the same bucket of the first task and
888	  it will boost the bucket clamp effective value to 30%.
889	  The clamp effective value of a bucket is reset to its nominal value
890	  (20% in the example above) when there are no more tasks refcounted in
891	  that bucket.
892
893	  An additional boost/capping margin can be added to some tasks. In the
894	  example above the 25% task will be boosted to 30% until it exits the
895	  CPU. If that should be considered not acceptable on certain systems,
896	  it's always possible to reduce the margin by increasing the number of
897	  clamp buckets to trade off used memory for run-time tracking
898	  precision.
899
900	  If in doubt, use the default value.
901
902config SCHED_PROXY_EXEC
903	bool "Proxy Execution"
904	# Avoid some build failures w/ PREEMPT_RT until it can be fixed
905	depends on !PREEMPT_RT
906	# Need to investigate how to inform sched_ext of split contexts
907	depends on !SCHED_CLASS_EXT
908	# Not particularly useful until we get to multi-rq proxying
909	depends on EXPERT
910	help
911	  This option enables proxy execution, a mechanism for mutex-owning
912	  tasks to inherit the scheduling context of higher priority waiters.
913
914endmenu
915
916#
917# For architectures that want to enable the support for NUMA-affine scheduler
918# balancing logic:
919#
920config ARCH_SUPPORTS_NUMA_BALANCING
921	bool
922
923#
924# For architectures that prefer to flush all TLBs after a number of pages
925# are unmapped instead of sending one IPI per page to flush. The architecture
926# must provide guarantees on what happens if a clean TLB cache entry is
927# written after the unmap. Details are in mm/rmap.c near the check for
928# should_defer_flush. The architecture should also consider if the full flush
929# and the refill costs are offset by the savings of sending fewer IPIs.
930config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
931	bool
932
933config CC_HAS_INT128
934	def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
935
936config CC_IMPLICIT_FALLTHROUGH
937	string
938	default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5)
939	default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough)
940
941# Currently, disable gcc-10+ array-bounds globally.
942# It's still broken in gcc-13, so no upper bound yet.
943config GCC10_NO_ARRAY_BOUNDS
944	def_bool y
945
946config CC_NO_ARRAY_BOUNDS
947	bool
948	default y if CC_IS_GCC && GCC_VERSION >= 90000 && GCC10_NO_ARRAY_BOUNDS
949
950# Currently, disable -Wstringop-overflow for GCC globally.
951config GCC_NO_STRINGOP_OVERFLOW
952	def_bool y
953
954config CC_NO_STRINGOP_OVERFLOW
955	bool
956	default y if CC_IS_GCC && GCC_NO_STRINGOP_OVERFLOW
957
958config CC_STRINGOP_OVERFLOW
959	bool
960	default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW
961
962#
963# For architectures that know their GCC __int128 support is sound
964#
965config ARCH_SUPPORTS_INT128
966	bool
967
968# For architectures that (ab)use NUMA to represent different memory regions
969# all cpu-local but of different latencies, such as SuperH.
970#
971config ARCH_WANT_NUMA_VARIABLE_LOCALITY
972	bool
973
974config NUMA_BALANCING
975	bool "Memory placement aware NUMA scheduler"
976	depends on ARCH_SUPPORTS_NUMA_BALANCING
977	depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
978	depends on SMP && NUMA && MIGRATION && !PREEMPT_RT
979	help
980	  This option adds support for automatic NUMA aware memory/task placement.
981	  The mechanism is quite primitive and is based on migrating memory when
982	  it has references to the node the task is running on.
983
984	  This system will be inactive on UMA systems.
985
986config NUMA_BALANCING_DEFAULT_ENABLED
987	bool "Automatically enable NUMA aware memory/task placement"
988	default y
989	depends on NUMA_BALANCING
990	help
991	  If set, automatic NUMA balancing will be enabled if running on a NUMA
992	  machine.
993
994config SLAB_OBJ_EXT
995	bool
996
997menuconfig CGROUPS
998	bool "Control Group support"
999	select KERNFS
1000	help
1001	  This option adds support for grouping sets of processes together, for
1002	  use with process control subsystems such as Cpusets, CFS, memory
1003	  controls or device isolation.
1004	  See
1005		- Documentation/scheduler/sched-design-CFS.rst	(CFS)
1006		- Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
1007					  and resource control)
1008
1009	  Say N if unsure.
1010
1011if CGROUPS
1012
1013config PAGE_COUNTER
1014	bool
1015
1016config CGROUP_FAVOR_DYNMODS
1017        bool "Favor dynamic modification latency reduction by default"
1018        help
1019          This option enables the "favordynmods" mount option by default
1020          which reduces the latencies of dynamic cgroup modifications such
1021          as task migrations and controller on/offs at the cost of making
1022          hot path operations such as forks and exits more expensive.
1023
1024          Say N if unsure.
1025
1026config MEMCG
1027	bool "Memory controller"
1028	select PAGE_COUNTER
1029	select EVENTFD
1030	select SLAB_OBJ_EXT
1031	select VM_EVENT_COUNTERS
1032	help
1033	  Provides control over the memory footprint of tasks in a cgroup.
1034
1035config MEMCG_NMI_UNSAFE
1036	bool
1037	depends on MEMCG
1038	depends on HAVE_NMI
1039	depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && !ARCH_HAVE_NMI_SAFE_CMPXCHG
1040	default y
1041
1042config MEMCG_NMI_SAFETY_REQUIRES_ATOMIC
1043	bool
1044	depends on MEMCG
1045	depends on HAVE_NMI
1046	depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && ARCH_HAVE_NMI_SAFE_CMPXCHG
1047	default y
1048
1049config MEMCG_V1
1050	bool "Legacy cgroup v1 memory controller"
1051	depends on MEMCG
1052	default n
1053	help
1054	  Legacy cgroup v1 memory controller which has been deprecated by
1055	  cgroup v2 implementation. The v1 is there for legacy applications
1056	  which haven't migrated to the new cgroup v2 interface yet. If you
1057	  do not have any such application then you are completely fine leaving
1058	  this option disabled.
1059
1060	  Please note that feature set of the legacy memory controller is likely
1061	  going to shrink due to deprecation process. New deployments with v1
1062	  controller are highly discouraged.
1063
1064	  Say N if unsure.
1065
1066config BLK_CGROUP
1067	bool "IO controller"
1068	depends on BLOCK
1069	default n
1070	help
1071	Generic block IO controller cgroup interface. This is the common
1072	cgroup interface which should be used by various IO controlling
1073	policies.
1074
1075	Currently, CFQ IO scheduler uses it to recognize task groups and
1076	control disk bandwidth allocation (proportional time slice allocation)
1077	to such task groups. It is also used by bio throttling logic in
1078	block layer to implement upper limit in IO rates on a device.
1079
1080	This option only enables generic Block IO controller infrastructure.
1081	One needs to also enable actual IO controlling logic/policy. For
1082	enabling proportional weight division of disk bandwidth in CFQ, set
1083	CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1084	CONFIG_BLK_DEV_THROTTLING=y.
1085
1086	See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
1087
1088config CGROUP_WRITEBACK
1089	bool
1090	depends on MEMCG && BLK_CGROUP
1091	default y
1092
1093menuconfig CGROUP_SCHED
1094	bool "CPU controller"
1095	default n
1096	help
1097	  This feature lets CPU scheduler recognize task groups and control CPU
1098	  bandwidth allocation to such task groups. It uses cgroups to group
1099	  tasks.
1100
1101if CGROUP_SCHED
1102config GROUP_SCHED_WEIGHT
1103	def_bool n
1104
1105config GROUP_SCHED_BANDWIDTH
1106        def_bool n
1107
1108config FAIR_GROUP_SCHED
1109	bool "Group scheduling for SCHED_OTHER"
1110	depends on CGROUP_SCHED
1111	select GROUP_SCHED_WEIGHT
1112	default CGROUP_SCHED
1113
1114config CFS_BANDWIDTH
1115	bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
1116	depends on FAIR_GROUP_SCHED
1117	select GROUP_SCHED_BANDWIDTH
1118	default n
1119	help
1120	  This option allows users to define CPU bandwidth rates (limits) for
1121	  tasks running within the fair group scheduler.  Groups with no limit
1122	  set are considered to be unconstrained and will run with no
1123	  restriction.
1124	  See Documentation/scheduler/sched-bwc.rst for more information.
1125
1126config RT_GROUP_SCHED
1127	bool "Group scheduling for SCHED_RR/FIFO"
1128	depends on CGROUP_SCHED
1129	default n
1130	help
1131	  This feature lets you explicitly allocate real CPU bandwidth
1132	  to task groups. If enabled, it will also make it impossible to
1133	  schedule realtime tasks for non-root users until you allocate
1134	  realtime bandwidth for them.
1135	  See Documentation/scheduler/sched-rt-group.rst for more information.
1136
1137config RT_GROUP_SCHED_DEFAULT_DISABLED
1138	bool "Require boot parameter to enable group scheduling for SCHED_RR/FIFO"
1139	depends on RT_GROUP_SCHED
1140	default n
1141	help
1142	  When set, the RT group scheduling is disabled by default. The option
1143	  is in inverted form so that mere RT_GROUP_SCHED enables the group
1144	  scheduling.
1145
1146	  Say N if unsure.
1147
1148config EXT_GROUP_SCHED
1149	bool
1150	depends on SCHED_CLASS_EXT && CGROUP_SCHED
1151	select GROUP_SCHED_WEIGHT
1152	select GROUP_SCHED_BANDWIDTH
1153	default y
1154
1155endif #CGROUP_SCHED
1156
1157config SCHED_MM_CID
1158	def_bool y
1159	depends on SMP && RSEQ
1160
1161config UCLAMP_TASK_GROUP
1162	bool "Utilization clamping per group of tasks"
1163	depends on CGROUP_SCHED
1164	depends on UCLAMP_TASK
1165	default n
1166	help
1167	  This feature enables the scheduler to track the clamped utilization
1168	  of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
1169
1170	  When this option is enabled, the user can specify a min and max
1171	  CPU bandwidth which is allowed for each single task in a group.
1172	  The max bandwidth allows to clamp the maximum frequency a task
1173	  can use, while the min bandwidth allows to define a minimum
1174	  frequency a task will always use.
1175
1176	  When task group based utilization clamping is enabled, an eventually
1177	  specified task-specific clamp value is constrained by the cgroup
1178	  specified clamp value. Both minimum and maximum task clamping cannot
1179	  be bigger than the corresponding clamping defined at task group level.
1180
1181	  If in doubt, say N.
1182
1183config CGROUP_PIDS
1184	bool "PIDs controller"
1185	help
1186	  Provides enforcement of process number limits in the scope of a
1187	  cgroup. Any attempt to fork more processes than is allowed in the
1188	  cgroup will fail. PIDs are fundamentally a global resource because it
1189	  is fairly trivial to reach PID exhaustion before you reach even a
1190	  conservative kmemcg limit. As a result, it is possible to grind a
1191	  system to halt without being limited by other cgroup policies. The
1192	  PIDs controller is designed to stop this from happening.
1193
1194	  It should be noted that organisational operations (such as attaching
1195	  to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
1196	  since the PIDs limit only affects a process's ability to fork, not to
1197	  attach to a cgroup.
1198
1199config CGROUP_RDMA
1200	bool "RDMA controller"
1201	help
1202	  Provides enforcement of RDMA resources defined by IB stack.
1203	  It is fairly easy for consumers to exhaust RDMA resources, which
1204	  can result into resource unavailability to other consumers.
1205	  RDMA controller is designed to stop this from happening.
1206	  Attaching processes with active RDMA resources to the cgroup
1207	  hierarchy is allowed even if can cross the hierarchy's limit.
1208
1209config CGROUP_DMEM
1210	bool "Device memory controller (DMEM)"
1211	select PAGE_COUNTER
1212	help
1213	  The DMEM controller allows compatible devices to restrict device
1214	  memory usage based on the cgroup hierarchy.
1215
1216	  As an example, it allows you to restrict VRAM usage for applications
1217	  in the DRM subsystem.
1218
1219config CGROUP_FREEZER
1220	bool "Freezer controller"
1221	help
1222	  Provides a way to freeze and unfreeze all tasks in a
1223	  cgroup.
1224
1225	  This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1226	  controller includes important in-kernel memory consumers per default.
1227
1228	  If you're using cgroup2, say N.
1229
1230config CGROUP_HUGETLB
1231	bool "HugeTLB controller"
1232	depends on HUGETLB_PAGE
1233	select PAGE_COUNTER
1234	default n
1235	help
1236	  Provides a cgroup controller for HugeTLB pages.
1237	  When you enable this, you can put a per cgroup limit on HugeTLB usage.
1238	  The limit is enforced during page fault. Since HugeTLB doesn't
1239	  support page reclaim, enforcing the limit at page fault time implies
1240	  that, the application will get SIGBUS signal if it tries to access
1241	  HugeTLB pages beyond its limit. This requires the application to know
1242	  beforehand how much HugeTLB pages it would require for its use. The
1243	  control group is tracked in the third page lru pointer. This means
1244	  that we cannot use the controller with huge page less than 3 pages.
1245
1246config CPUSETS
1247	bool "Cpuset controller"
1248	depends on SMP
1249	select UNION_FIND
1250	help
1251	  This option will let you create and manage CPUSETs which
1252	  allow dynamically partitioning a system into sets of CPUs and
1253	  Memory Nodes and assigning tasks to run only within those sets.
1254	  This is primarily useful on large SMP or NUMA systems.
1255
1256	  Say N if unsure.
1257
1258config CPUSETS_V1
1259	bool "Legacy cgroup v1 cpusets controller"
1260	depends on CPUSETS
1261	default n
1262	help
1263	  Legacy cgroup v1 cpusets controller which has been deprecated by
1264	  cgroup v2 implementation. The v1 is there for legacy applications
1265	  which haven't migrated to the new cgroup v2 interface yet. Legacy
1266	  interface includes cpuset filesystem and /proc/<pid>/cpuset. If you
1267	  do not have any such application then you are completely fine leaving
1268	  this option disabled.
1269
1270	  Say N if unsure.
1271
1272config PROC_PID_CPUSET
1273	bool "Include legacy /proc/<pid>/cpuset file"
1274	depends on CPUSETS_V1
1275	default y
1276
1277config CGROUP_DEVICE
1278	bool "Device controller"
1279	help
1280	  Provides a cgroup controller implementing whitelists for
1281	  devices which a process in the cgroup can mknod or open.
1282
1283config CGROUP_CPUACCT
1284	bool "Simple CPU accounting controller"
1285	help
1286	  Provides a simple controller for monitoring the
1287	  total CPU consumed by the tasks in a cgroup.
1288
1289config CGROUP_PERF
1290	bool "Perf controller"
1291	depends on PERF_EVENTS
1292	help
1293	  This option extends the perf per-cpu mode to restrict monitoring
1294	  to threads which belong to the cgroup specified and run on the
1295	  designated cpu.  Or this can be used to have cgroup ID in samples
1296	  so that it can monitor performance events among cgroups.
1297
1298	  Say N if unsure.
1299
1300config CGROUP_BPF
1301	bool "Support for eBPF programs attached to cgroups"
1302	depends on BPF_SYSCALL
1303	select SOCK_CGROUP_DATA
1304	help
1305	  Allow attaching eBPF programs to a cgroup using the bpf(2)
1306	  syscall command BPF_PROG_ATTACH.
1307
1308	  In which context these programs are accessed depends on the type
1309	  of attachment. For instance, programs that are attached using
1310	  BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1311	  inet sockets.
1312
1313config CGROUP_MISC
1314	bool "Misc resource controller"
1315	default n
1316	help
1317	  Provides a controller for miscellaneous resources on a host.
1318
1319	  Miscellaneous scalar resources are the resources on the host system
1320	  which cannot be abstracted like the other cgroups. This controller
1321	  tracks and limits the miscellaneous resources used by a process
1322	  attached to a cgroup hierarchy.
1323
1324	  For more information, please check misc cgroup section in
1325	  /Documentation/admin-guide/cgroup-v2.rst.
1326
1327config CGROUP_DEBUG
1328	bool "Debug controller"
1329	default n
1330	depends on DEBUG_KERNEL
1331	help
1332	  This option enables a simple controller that exports
1333	  debugging information about the cgroups framework. This
1334	  controller is for control cgroup debugging only. Its
1335	  interfaces are not stable.
1336
1337	  Say N.
1338
1339config SOCK_CGROUP_DATA
1340	bool
1341	default n
1342
1343endif # CGROUPS
1344
1345menuconfig NAMESPACES
1346	bool "Namespaces support" if EXPERT
1347	depends on MULTIUSER
1348	default !EXPERT
1349	help
1350	  Provides the way to make tasks work with different objects using
1351	  the same id. For example same IPC id may refer to different objects
1352	  or same user id or pid may refer to different tasks when used in
1353	  different namespaces.
1354
1355if NAMESPACES
1356
1357config UTS_NS
1358	bool "UTS namespace"
1359	default y
1360	help
1361	  In this namespace tasks see different info provided with the
1362	  uname() system call
1363
1364config TIME_NS
1365	bool "TIME namespace"
1366	depends on GENERIC_GETTIMEOFDAY
1367	default y
1368	help
1369	  In this namespace boottime and monotonic clocks can be set.
1370	  The time will keep going with the same pace.
1371
1372config IPC_NS
1373	bool "IPC namespace"
1374	depends on (SYSVIPC || POSIX_MQUEUE)
1375	default y
1376	help
1377	  In this namespace tasks work with IPC ids which correspond to
1378	  different IPC objects in different namespaces.
1379
1380config USER_NS
1381	bool "User namespace"
1382	default n
1383	help
1384	  This allows containers, i.e. vservers, to use user namespaces
1385	  to provide different user info for different servers.
1386
1387	  When user namespaces are enabled in the kernel it is
1388	  recommended that the MEMCG option also be enabled and that
1389	  user-space use the memory control groups to limit the amount
1390	  of memory a memory unprivileged users can use.
1391
1392	  If unsure, say N.
1393
1394config PID_NS
1395	bool "PID Namespaces"
1396	default y
1397	help
1398	  Support process id namespaces.  This allows having multiple
1399	  processes with the same pid as long as they are in different
1400	  pid namespaces.  This is a building block of containers.
1401
1402config NET_NS
1403	bool "Network namespace"
1404	depends on NET
1405	default y
1406	help
1407	  Allow user space to create what appear to be multiple instances
1408	  of the network stack.
1409
1410endif # NAMESPACES
1411
1412config CHECKPOINT_RESTORE
1413	bool "Checkpoint/restore support"
1414	depends on PROC_FS
1415	select PROC_CHILDREN
1416	select KCMP
1417	default n
1418	help
1419	  Enables additional kernel features in a sake of checkpoint/restore.
1420	  In particular it adds auxiliary prctl codes to setup process text,
1421	  data and heap segment sizes, and a few additional /proc filesystem
1422	  entries.
1423
1424	  If unsure, say N here.
1425
1426config SCHED_AUTOGROUP
1427	bool "Automatic process group scheduling"
1428	select CGROUPS
1429	select CGROUP_SCHED
1430	select FAIR_GROUP_SCHED
1431	help
1432	  This option optimizes the scheduler for common desktop workloads by
1433	  automatically creating and populating task groups.  This separation
1434	  of workloads isolates aggressive CPU burners (like build jobs) from
1435	  desktop applications.  Task group autogeneration is currently based
1436	  upon task session.
1437
1438config RELAY
1439	bool "Kernel->user space relay support (formerly relayfs)"
1440	select IRQ_WORK
1441	help
1442	  This option enables support for relay interface support in
1443	  certain file systems (such as debugfs).
1444	  It is designed to provide an efficient mechanism for tools and
1445	  facilities to relay large amounts of data from kernel space to
1446	  user space.
1447
1448	  If unsure, say N.
1449
1450config BLK_DEV_INITRD
1451	bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1452	help
1453	  The initial RAM filesystem is a ramfs which is loaded by the
1454	  boot loader (loadlin or lilo) and that is mounted as root
1455	  before the normal boot procedure. It is typically used to
1456	  load modules needed to mount the "real" root file system,
1457	  etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1458
1459	  If RAM disk support (BLK_DEV_RAM) is also included, this
1460	  also enables initial RAM disk (initrd) support and adds
1461	  15 Kbytes (more on some other architectures) to the kernel size.
1462
1463	  If unsure say Y.
1464
1465if BLK_DEV_INITRD
1466
1467source "usr/Kconfig"
1468
1469endif
1470
1471config BOOT_CONFIG
1472	bool "Boot config support"
1473	select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED
1474	help
1475	  Extra boot config allows system admin to pass a config file as
1476	  complemental extension of kernel cmdline when booting.
1477	  The boot config file must be attached at the end of initramfs
1478	  with checksum, size and magic word.
1479	  See <file:Documentation/admin-guide/bootconfig.rst> for details.
1480
1481	  If unsure, say Y.
1482
1483config BOOT_CONFIG_FORCE
1484	bool "Force unconditional bootconfig processing"
1485	depends on BOOT_CONFIG
1486	default y if BOOT_CONFIG_EMBED
1487	help
1488	  With this Kconfig option set, BOOT_CONFIG processing is carried
1489	  out even when the "bootconfig" kernel-boot parameter is omitted.
1490	  In fact, with this Kconfig option set, there is no way to
1491	  make the kernel ignore the BOOT_CONFIG-supplied kernel-boot
1492	  parameters.
1493
1494	  If unsure, say N.
1495
1496config BOOT_CONFIG_EMBED
1497	bool "Embed bootconfig file in the kernel"
1498	depends on BOOT_CONFIG
1499	help
1500	  Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the
1501	  kernel. Usually, the bootconfig file is loaded with the initrd
1502	  image. But if the system doesn't support initrd, this option will
1503	  help you by embedding a bootconfig file while building the kernel.
1504
1505	  If unsure, say N.
1506
1507config BOOT_CONFIG_EMBED_FILE
1508	string "Embedded bootconfig file path"
1509	depends on BOOT_CONFIG_EMBED
1510	help
1511	  Specify a bootconfig file which will be embedded to the kernel.
1512	  This bootconfig will be used if there is no initrd or no other
1513	  bootconfig in the initrd.
1514
1515config INITRAMFS_PRESERVE_MTIME
1516	bool "Preserve cpio archive mtimes in initramfs"
1517	depends on BLK_DEV_INITRD
1518	default y
1519	help
1520	  Each entry in an initramfs cpio archive carries an mtime value. When
1521	  enabled, extracted cpio items take this mtime, with directory mtime
1522	  setting deferred until after creation of any child entries.
1523
1524	  If unsure, say Y.
1525
1526config INITRAMFS_TEST
1527	bool "Test initramfs cpio archive extraction" if !KUNIT_ALL_TESTS
1528	depends on BLK_DEV_INITRD && KUNIT=y
1529	default KUNIT_ALL_TESTS
1530	help
1531	  Build KUnit tests for initramfs. See Documentation/dev-tools/kunit
1532
1533choice
1534	prompt "Compiler optimization level"
1535	default CC_OPTIMIZE_FOR_PERFORMANCE
1536
1537config CC_OPTIMIZE_FOR_PERFORMANCE
1538	bool "Optimize for performance (-O2)"
1539	help
1540	  This is the default optimization level for the kernel, building
1541	  with the "-O2" compiler flag for best performance and most
1542	  helpful compile-time warnings.
1543
1544config CC_OPTIMIZE_FOR_SIZE
1545	bool "Optimize for size (-Os)"
1546	help
1547	  Choosing this option will pass "-Os" to your compiler resulting
1548	  in a smaller kernel.
1549
1550endchoice
1551
1552config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1553	bool
1554	help
1555	  This requires that the arch annotates or otherwise protects
1556	  its external entry points from being discarded. Linker scripts
1557	  must also merge .text.*, .data.*, and .bss.* correctly into
1558	  output sections. Care must be taken not to pull in unrelated
1559	  sections (e.g., '.text.init'). Typically '.' in section names
1560	  is used to distinguish them from label names / C identifiers.
1561
1562config LD_DEAD_CODE_DATA_ELIMINATION
1563	bool "Dead code and data elimination (EXPERIMENTAL)"
1564	depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1565	depends on EXPERT
1566	depends on $(cc-option,-ffunction-sections -fdata-sections)
1567	depends on $(ld-option,--gc-sections)
1568	help
1569	  Enable this if you want to do dead code and data elimination with
1570	  the linker by compiling with -ffunction-sections -fdata-sections,
1571	  and linking with --gc-sections.
1572
1573	  This can reduce on disk and in-memory size of the kernel
1574	  code and static data, particularly for small configs and
1575	  on small systems. This has the possibility of introducing
1576	  silently broken kernel if the required annotations are not
1577	  present. This option is not well tested yet, so use at your
1578	  own risk.
1579
1580config LD_ORPHAN_WARN
1581	def_bool y
1582	depends on ARCH_WANT_LD_ORPHAN_WARN
1583	depends on $(ld-option,--orphan-handling=warn)
1584	depends on $(ld-option,--orphan-handling=error)
1585
1586config LD_ORPHAN_WARN_LEVEL
1587        string
1588        depends on LD_ORPHAN_WARN
1589        default "error" if WERROR
1590        default "warn"
1591
1592config SYSCTL
1593	bool
1594
1595config HAVE_UID16
1596	bool
1597
1598config SYSCTL_EXCEPTION_TRACE
1599	bool
1600	help
1601	  Enable support for /proc/sys/debug/exception-trace.
1602
1603config SYSCTL_ARCH_UNALIGN_NO_WARN
1604	bool
1605	help
1606	  Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1607	  Allows arch to define/use @no_unaligned_warning to possibly warn
1608	  about unaligned access emulation going on under the hood.
1609
1610config SYSCTL_ARCH_UNALIGN_ALLOW
1611	bool
1612	help
1613	  Enable support for /proc/sys/kernel/unaligned-trap
1614	  Allows arches to define/use @unaligned_enabled to runtime toggle
1615	  the unaligned access emulation.
1616	  see arch/parisc/kernel/unaligned.c for reference
1617
1618config SYSFS_SYSCALL
1619	bool "Sysfs syscall support"
1620	default n
1621	help
1622	  sys_sysfs is an obsolete system call no longer supported in libc.
1623	  Note that disabling this option is more secure but might break
1624	  compatibility with some systems.
1625
1626	  If unsure say N here.
1627
1628config HAVE_PCSPKR_PLATFORM
1629	bool
1630
1631menuconfig EXPERT
1632	bool "Configure standard kernel features (expert users)"
1633	# Unhide debug options, to make the on-by-default options visible
1634	select DEBUG_KERNEL
1635	help
1636	  This option allows certain base kernel options and settings
1637	  to be disabled or tweaked. This is for specialized
1638	  environments which can tolerate a "non-standard" kernel.
1639	  Only use this if you really know what you are doing.
1640
1641config UID16
1642	bool "Enable 16-bit UID system calls" if EXPERT
1643	depends on HAVE_UID16 && MULTIUSER
1644	default y
1645	help
1646	  This enables the legacy 16-bit UID syscall wrappers.
1647
1648config MULTIUSER
1649	bool "Multiple users, groups and capabilities support" if EXPERT
1650	default y
1651	help
1652	  This option enables support for non-root users, groups and
1653	  capabilities.
1654
1655	  If you say N here, all processes will run with UID 0, GID 0, and all
1656	  possible capabilities.  Saying N here also compiles out support for
1657	  system calls related to UIDs, GIDs, and capabilities, such as setuid,
1658	  setgid, and capset.
1659
1660	  If unsure, say Y here.
1661
1662config SGETMASK_SYSCALL
1663	bool "sgetmask/ssetmask syscalls support" if EXPERT
1664	default PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1665	help
1666	  sys_sgetmask and sys_ssetmask are obsolete system calls
1667	  no longer supported in libc but still enabled by default in some
1668	  architectures.
1669
1670	  If unsure, leave the default option here.
1671
1672config FHANDLE
1673	bool "open by fhandle syscalls" if EXPERT
1674	select EXPORTFS
1675	default y
1676	help
1677	  If you say Y here, a user level program will be able to map
1678	  file names to handle and then later use the handle for
1679	  different file system operations. This is useful in implementing
1680	  userspace file servers, which now track files using handles instead
1681	  of names. The handle would remain the same even if file names
1682	  get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1683	  syscalls.
1684
1685config POSIX_TIMERS
1686	bool "Posix Clocks & timers" if EXPERT
1687	default y
1688	help
1689	  This includes native support for POSIX timers to the kernel.
1690	  Some embedded systems have no use for them and therefore they
1691	  can be configured out to reduce the size of the kernel image.
1692
1693	  When this option is disabled, the following syscalls won't be
1694	  available: timer_create, timer_gettime: timer_getoverrun,
1695	  timer_settime, timer_delete, clock_adjtime, getitimer,
1696	  setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1697	  clock_getres and clock_nanosleep syscalls will be limited to
1698	  CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1699
1700	  If unsure say y.
1701
1702config PRINTK
1703	default y
1704	bool "Enable support for printk" if EXPERT
1705	select IRQ_WORK
1706	help
1707	  This option enables normal printk support. Removing it
1708	  eliminates most of the message strings from the kernel image
1709	  and makes the kernel more or less silent. As this makes it
1710	  very difficult to diagnose system problems, saying N here is
1711	  strongly discouraged.
1712
1713config BUG
1714	bool "BUG() support" if EXPERT
1715	default y
1716	help
1717	  Disabling this option eliminates support for BUG and WARN, reducing
1718	  the size of your kernel image and potentially quietly ignoring
1719	  numerous fatal conditions. You should only consider disabling this
1720	  option for embedded systems with no facilities for reporting errors.
1721	  Just say Y.
1722
1723config ELF_CORE
1724	depends on COREDUMP
1725	default y
1726	bool "Enable ELF core dumps" if EXPERT
1727	help
1728	  Enable support for generating core dumps. Disabling saves about 4k.
1729
1730
1731config PCSPKR_PLATFORM
1732	bool "Enable PC-Speaker support" if EXPERT
1733	depends on HAVE_PCSPKR_PLATFORM
1734	select I8253_LOCK
1735	default y
1736	help
1737	  This option allows to disable the internal PC-Speaker
1738	  support, saving some memory.
1739
1740config BASE_SMALL
1741	bool "Enable smaller-sized data structures for core" if EXPERT
1742	help
1743	  Enabling this option reduces the size of miscellaneous core
1744	  kernel data structures. This saves memory on small machines,
1745	  but may reduce performance.
1746
1747config FUTEX
1748	bool "Enable futex support" if EXPERT
1749	depends on !(SPARC32 && SMP)
1750	default y
1751	imply RT_MUTEXES
1752	help
1753	  Disabling this option will cause the kernel to be built without
1754	  support for "fast userspace mutexes".  The resulting kernel may not
1755	  run glibc-based applications correctly.
1756
1757config FUTEX_PI
1758	bool
1759	depends on FUTEX && RT_MUTEXES
1760	default y
1761
1762config FUTEX_PRIVATE_HASH
1763	bool
1764	depends on FUTEX && !BASE_SMALL && MMU
1765	default y
1766
1767config FUTEX_MPOL
1768	bool
1769	depends on FUTEX && NUMA
1770	default y
1771
1772config EPOLL
1773	bool "Enable eventpoll support" if EXPERT
1774	default y
1775	help
1776	  Disabling this option will cause the kernel to be built without
1777	  support for epoll family of system calls.
1778
1779config SIGNALFD
1780	bool "Enable signalfd() system call" if EXPERT
1781	default y
1782	help
1783	  Enable the signalfd() system call that allows to receive signals
1784	  on a file descriptor.
1785
1786	  If unsure, say Y.
1787
1788config TIMERFD
1789	bool "Enable timerfd() system call" if EXPERT
1790	default y
1791	help
1792	  Enable the timerfd() system call that allows to receive timer
1793	  events on a file descriptor.
1794
1795	  If unsure, say Y.
1796
1797config EVENTFD
1798	bool "Enable eventfd() system call" if EXPERT
1799	default y
1800	help
1801	  Enable the eventfd() system call that allows to receive both
1802	  kernel notification (ie. KAIO) or userspace notifications.
1803
1804	  If unsure, say Y.
1805
1806config SHMEM
1807	bool "Use full shmem filesystem" if EXPERT
1808	default y
1809	depends on MMU
1810	help
1811	  The shmem is an internal filesystem used to manage shared memory.
1812	  It is backed by swap and manages resource limits. It is also exported
1813	  to userspace as tmpfs if TMPFS is enabled. Disabling this
1814	  option replaces shmem and tmpfs with the much simpler ramfs code,
1815	  which may be appropriate on small systems without swap.
1816
1817config AIO
1818	bool "Enable AIO support" if EXPERT
1819	default y
1820	help
1821	  This option enables POSIX asynchronous I/O which may by used
1822	  by some high performance threaded applications. Disabling
1823	  this option saves about 7k.
1824
1825config IO_URING
1826	bool "Enable IO uring support" if EXPERT
1827	select IO_WQ
1828	default y
1829	help
1830	  This option enables support for the io_uring interface, enabling
1831	  applications to submit and complete IO through submission and
1832	  completion rings that are shared between the kernel and application.
1833
1834config GCOV_PROFILE_URING
1835	bool "Enable GCOV profiling on the io_uring subsystem"
1836	depends on IO_URING && GCOV_KERNEL
1837	help
1838	  Enable GCOV profiling on the io_uring subsystem, to facilitate
1839	  code coverage testing.
1840
1841	  If unsure, say N.
1842
1843	  Note that this will have a negative impact on the performance of
1844	  the io_uring subsystem, hence this should only be enabled for
1845	  specific test purposes.
1846
1847config IO_URING_MOCK_FILE
1848	tristate "Enable io_uring mock files (Experimental)" if EXPERT
1849	default n
1850	depends on IO_URING
1851	help
1852	  Enable mock files for io_uring subststem testing. The ABI might
1853	  still change, so it's still experimental and should only be enabled
1854	  for specific test purposes.
1855
1856	  If unsure, say N.
1857
1858config ADVISE_SYSCALLS
1859	bool "Enable madvise/fadvise syscalls" if EXPERT
1860	default y
1861	help
1862	  This option enables the madvise and fadvise syscalls, used by
1863	  applications to advise the kernel about their future memory or file
1864	  usage, improving performance. If building an embedded system where no
1865	  applications use these syscalls, you can disable this option to save
1866	  space.
1867
1868config MEMBARRIER
1869	bool "Enable membarrier() system call" if EXPERT
1870	default y
1871	help
1872	  Enable the membarrier() system call that allows issuing memory
1873	  barriers across all running threads, which can be used to distribute
1874	  the cost of user-space memory barriers asymmetrically by transforming
1875	  pairs of memory barriers into pairs consisting of membarrier() and a
1876	  compiler barrier.
1877
1878	  If unsure, say Y.
1879
1880config KCMP
1881	bool "Enable kcmp() system call" if EXPERT
1882	help
1883	  Enable the kernel resource comparison system call. It provides
1884	  user-space with the ability to compare two processes to see if they
1885	  share a common resource, such as a file descriptor or even virtual
1886	  memory space.
1887
1888	  If unsure, say N.
1889
1890config RSEQ
1891	bool "Enable rseq() system call" if EXPERT
1892	default y
1893	depends on HAVE_RSEQ
1894	select MEMBARRIER
1895	help
1896	  Enable the restartable sequences system call. It provides a
1897	  user-space cache for the current CPU number value, which
1898	  speeds up getting the current CPU number from user-space,
1899	  as well as an ABI to speed up user-space operations on
1900	  per-CPU data.
1901
1902	  If unsure, say Y.
1903
1904config DEBUG_RSEQ
1905	default n
1906	bool "Enable debugging of rseq() system call" if EXPERT
1907	depends on RSEQ && DEBUG_KERNEL
1908	help
1909	  Enable extra debugging checks for the rseq system call.
1910
1911	  If unsure, say N.
1912
1913config CACHESTAT_SYSCALL
1914	bool "Enable cachestat() system call" if EXPERT
1915	default y
1916	help
1917	  Enable the cachestat system call, which queries the page cache
1918	  statistics of a file (number of cached pages, dirty pages,
1919	  pages marked for writeback, (recently) evicted pages).
1920
1921	  If unsure say Y here.
1922
1923config KALLSYMS
1924	bool "Load all symbols for debugging/ksymoops" if EXPERT
1925	default y
1926	help
1927	  Say Y here to let the kernel print out symbolic crash information and
1928	  symbolic stack backtraces. This increases the size of the kernel
1929	  somewhat, as all symbols have to be loaded into the kernel image.
1930
1931config KALLSYMS_SELFTEST
1932	bool "Test the basic functions and performance of kallsyms"
1933	depends on KALLSYMS
1934	default n
1935	help
1936	  Test the basic functions and performance of some interfaces, such as
1937	  kallsyms_lookup_name. It also calculates the compression rate of the
1938	  kallsyms compression algorithm for the current symbol set.
1939
1940	  Start self-test automatically after system startup. Suggest executing
1941	  "dmesg | grep kallsyms_selftest" to collect test results. "finish" is
1942	  displayed in the last line, indicating that the test is complete.
1943
1944config KALLSYMS_ALL
1945	bool "Include all symbols in kallsyms"
1946	depends on DEBUG_KERNEL && KALLSYMS
1947	help
1948	  Normally kallsyms only contains the symbols of functions for nicer
1949	  OOPS messages and backtraces (i.e., symbols from the text and inittext
1950	  sections). This is sufficient for most cases. And only if you want to
1951	  enable kernel live patching, or other less common use cases (e.g.,
1952	  when a debugger is used) all symbols are required (i.e., names of
1953	  variables from the data sections, etc).
1954
1955	  This option makes sure that all symbols are loaded into the kernel
1956	  image (i.e., symbols from all sections) in cost of increased kernel
1957	  size (depending on the kernel configuration, it may be 300KiB or
1958	  something like this).
1959
1960	  Say N unless you really need all symbols, or kernel live patching.
1961
1962# end of the "standard kernel features (expert users)" menu
1963
1964config ARCH_HAS_MEMBARRIER_CALLBACKS
1965	bool
1966
1967config ARCH_HAS_MEMBARRIER_SYNC_CORE
1968	bool
1969
1970config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS
1971	bool
1972	help
1973	  Control MSEAL_SYSTEM_MAPPINGS access based on architecture.
1974
1975	  A 64-bit kernel is required for the memory sealing feature.
1976	  No specific hardware features from the CPU are needed.
1977
1978	  To enable this feature, the architecture needs to update their
1979	  special mappings calls to include the sealing flag and confirm
1980	  that it doesn't unmap/remap system mappings during the life
1981	  time of the process. The existence of this flag for an architecture
1982	  implies that it does not require the remapping of the system
1983	  mappings during process lifetime, so sealing these mappings is safe
1984	  from a kernel perspective.
1985
1986	  After the architecture enables this, a distribution can set
1987	  CONFIG_MSEAL_SYSTEM_MAPPING to manage access to the feature.
1988
1989	  For complete descriptions of memory sealing, please see
1990	  Documentation/userspace-api/mseal.rst
1991
1992config HAVE_PERF_EVENTS
1993	bool
1994	help
1995	  See tools/perf/design.txt for details.
1996
1997config GUEST_PERF_EVENTS
1998	bool
1999	depends on HAVE_PERF_EVENTS
2000
2001config PERF_USE_VMALLOC
2002	bool
2003	help
2004	  See tools/perf/design.txt for details
2005
2006menu "Kernel Performance Events And Counters"
2007
2008config PERF_EVENTS
2009	bool "Kernel performance events and counters"
2010	default y if PROFILING
2011	depends on HAVE_PERF_EVENTS
2012	select IRQ_WORK
2013	help
2014	  Enable kernel support for various performance events provided
2015	  by software and hardware.
2016
2017	  Software events are supported either built-in or via the
2018	  use of generic tracepoints.
2019
2020	  Most modern CPUs support performance events via performance
2021	  counter registers. These registers count the number of certain
2022	  types of hw events: such as instructions executed, cachemisses
2023	  suffered, or branches mis-predicted - without slowing down the
2024	  kernel or applications. These registers can also trigger interrupts
2025	  when a threshold number of events have passed - and can thus be
2026	  used to profile the code that runs on that CPU.
2027
2028	  The Linux Performance Event subsystem provides an abstraction of
2029	  these software and hardware event capabilities, available via a
2030	  system call and used by the "perf" utility in tools/perf/. It
2031	  provides per task and per CPU counters, and it provides event
2032	  capabilities on top of those.
2033
2034	  Say Y if unsure.
2035
2036config DEBUG_PERF_USE_VMALLOC
2037	default n
2038	bool "Debug: use vmalloc to back perf mmap() buffers"
2039	depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
2040	select PERF_USE_VMALLOC
2041	help
2042	  Use vmalloc memory to back perf mmap() buffers.
2043
2044	  Mostly useful for debugging the vmalloc code on platforms
2045	  that don't require it.
2046
2047	  Say N if unsure.
2048
2049endmenu
2050
2051config SYSTEM_DATA_VERIFICATION
2052	def_bool n
2053	select SYSTEM_TRUSTED_KEYRING
2054	select KEYS
2055	select CRYPTO
2056	select CRYPTO_RSA
2057	select ASYMMETRIC_KEY_TYPE
2058	select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
2059	select ASN1
2060	select OID_REGISTRY
2061	select X509_CERTIFICATE_PARSER
2062	select PKCS7_MESSAGE_PARSER
2063	help
2064	  Provide PKCS#7 message verification using the contents of the system
2065	  trusted keyring to provide public keys.  This then can be used for
2066	  module verification, kexec image verification and firmware blob
2067	  verification.
2068
2069config PROFILING
2070	bool "Profiling support"
2071	help
2072	  Say Y here to enable the extended profiling support mechanisms used
2073	  by profilers.
2074
2075config RUST
2076	bool "Rust support"
2077	depends on HAVE_RUST
2078	depends on RUST_IS_AVAILABLE
2079	select EXTENDED_MODVERSIONS if MODVERSIONS
2080	depends on !MODVERSIONS || GENDWARFKSYMS
2081	depends on !GCC_PLUGIN_RANDSTRUCT
2082	depends on !RANDSTRUCT
2083	depends on !DEBUG_INFO_BTF || (PAHOLE_HAS_LANG_EXCLUDE && !LTO)
2084	depends on !CFI || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC
2085	select CFI_ICALL_NORMALIZE_INTEGERS if CFI
2086	depends on !CALL_PADDING || RUSTC_VERSION >= 108100
2087	depends on !KASAN_SW_TAGS
2088	depends on !(MITIGATION_RETHUNK && KASAN) || RUSTC_VERSION >= 108300
2089	help
2090	  Enables Rust support in the kernel.
2091
2092	  This allows other Rust-related options, like drivers written in Rust,
2093	  to be selected.
2094
2095	  It is also required to be able to load external kernel modules
2096	  written in Rust.
2097
2098	  See Documentation/rust/ for more information.
2099
2100	  If unsure, say N.
2101
2102config RUSTC_VERSION_TEXT
2103	string
2104	depends on RUST
2105	default "$(RUSTC_VERSION_TEXT)"
2106	help
2107	  See `CC_VERSION_TEXT`.
2108
2109config BINDGEN_VERSION_TEXT
2110	string
2111	depends on RUST
2112	# The dummy parameter `workaround-for-0.69.0` is required to support 0.69.0
2113	# (https://github.com/rust-lang/rust-bindgen/pull/2678) and 0.71.0
2114	# (https://github.com/rust-lang/rust-bindgen/pull/3040). It can be removed
2115	# when the minimum version is upgraded past the latter (0.69.1 and 0.71.1
2116	# both fixed the issue).
2117	default "$(shell,$(BINDGEN) --version workaround-for-0.69.0 2>/dev/null)"
2118
2119#
2120# Place an empty function call at each tracepoint site. Can be
2121# dynamically changed for a probe function.
2122#
2123config TRACEPOINTS
2124	bool
2125	select TASKS_TRACE_RCU
2126
2127source "kernel/Kconfig.kexec"
2128
2129endmenu		# General setup
2130
2131source "arch/Kconfig"
2132
2133config RT_MUTEXES
2134	bool
2135	default y if PREEMPT_RT
2136
2137config MODULE_SIG_FORMAT
2138	def_bool n
2139	select SYSTEM_DATA_VERIFICATION
2140
2141source "kernel/module/Kconfig"
2142
2143config INIT_ALL_POSSIBLE
2144	bool
2145	help
2146	  Back when each arch used to define their own cpu_online_mask and
2147	  cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2148	  with all 1s, and others with all 0s.  When they were centralised,
2149	  it was better to provide this option than to break all the archs
2150	  and have several arch maintainers pursuing me down dark alleys.
2151
2152source "block/Kconfig"
2153
2154config PREEMPT_NOTIFIERS
2155	bool
2156
2157config PADATA
2158	depends on SMP
2159	bool
2160
2161config ASN1
2162	tristate
2163	help
2164	  Build a simple ASN.1 grammar compiler that produces a bytecode output
2165	  that can be interpreted by the ASN.1 stream decoder and used to
2166	  inform it as to what tags are to be expected in a stream and what
2167	  functions to call on what tags.
2168
2169source "kernel/Kconfig.locks"
2170
2171config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
2172	bool
2173
2174config ARCH_HAS_PREPARE_SYNC_CORE_CMD
2175	bool
2176
2177config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2178	bool
2179
2180# It may be useful for an architecture to override the definitions of the
2181# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2182# and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2183# different calling convention for syscalls. They can also override the
2184# macros for not-implemented syscalls in kernel/sys_ni.c and
2185# kernel/time/posix-stubs.c. All these overrides need to be available in
2186# <asm/syscall_wrapper.h>.
2187config ARCH_HAS_SYSCALL_WRAPPER
2188	def_bool n
2189