Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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 PRINTK_RINGBUFFER_KUNIT_TEST
1714 tristate "KUnit Test for the printk ringbuffer" if !KUNIT_ALL_TESTS
1715 depends on PRINTK && KUNIT
1716 default KUNIT_ALL_TESTS
1717 help
1718 This builds the printk ringbuffer KUnit test suite.
1719
1720 For more information on KUnit and unit tests in general, please refer
1721 to the KUnit documentation.
1722
1723 If unsure, say N.
1724
1725config BUG
1726 bool "BUG() support" if EXPERT
1727 default y
1728 help
1729 Disabling this option eliminates support for BUG and WARN, reducing
1730 the size of your kernel image and potentially quietly ignoring
1731 numerous fatal conditions. You should only consider disabling this
1732 option for embedded systems with no facilities for reporting errors.
1733 Just say Y.
1734
1735config ELF_CORE
1736 depends on COREDUMP
1737 default y
1738 bool "Enable ELF core dumps" if EXPERT
1739 help
1740 Enable support for generating core dumps. Disabling saves about 4k.
1741
1742
1743config PCSPKR_PLATFORM
1744 bool "Enable PC-Speaker support" if EXPERT
1745 depends on HAVE_PCSPKR_PLATFORM
1746 select I8253_LOCK
1747 default y
1748 help
1749 This option allows to disable the internal PC-Speaker
1750 support, saving some memory.
1751
1752config BASE_SMALL
1753 bool "Enable smaller-sized data structures for core" if EXPERT
1754 help
1755 Enabling this option reduces the size of miscellaneous core
1756 kernel data structures. This saves memory on small machines,
1757 but may reduce performance.
1758
1759config FUTEX
1760 bool "Enable futex support" if EXPERT
1761 depends on !(SPARC32 && SMP)
1762 default y
1763 imply RT_MUTEXES
1764 help
1765 Disabling this option will cause the kernel to be built without
1766 support for "fast userspace mutexes". The resulting kernel may not
1767 run glibc-based applications correctly.
1768
1769config FUTEX_PI
1770 bool
1771 depends on FUTEX && RT_MUTEXES
1772 default y
1773
1774config FUTEX_PRIVATE_HASH
1775 bool
1776 depends on FUTEX && !BASE_SMALL && MMU
1777 default y
1778
1779config FUTEX_MPOL
1780 bool
1781 depends on FUTEX && NUMA
1782 default y
1783
1784config EPOLL
1785 bool "Enable eventpoll support" if EXPERT
1786 default y
1787 help
1788 Disabling this option will cause the kernel to be built without
1789 support for epoll family of system calls.
1790
1791config SIGNALFD
1792 bool "Enable signalfd() system call" if EXPERT
1793 default y
1794 help
1795 Enable the signalfd() system call that allows to receive signals
1796 on a file descriptor.
1797
1798 If unsure, say Y.
1799
1800config TIMERFD
1801 bool "Enable timerfd() system call" if EXPERT
1802 default y
1803 help
1804 Enable the timerfd() system call that allows to receive timer
1805 events on a file descriptor.
1806
1807 If unsure, say Y.
1808
1809config EVENTFD
1810 bool "Enable eventfd() system call" if EXPERT
1811 default y
1812 help
1813 Enable the eventfd() system call that allows to receive both
1814 kernel notification (ie. KAIO) or userspace notifications.
1815
1816 If unsure, say Y.
1817
1818config SHMEM
1819 bool "Use full shmem filesystem" if EXPERT
1820 default y
1821 depends on MMU
1822 help
1823 The shmem is an internal filesystem used to manage shared memory.
1824 It is backed by swap and manages resource limits. It is also exported
1825 to userspace as tmpfs if TMPFS is enabled. Disabling this
1826 option replaces shmem and tmpfs with the much simpler ramfs code,
1827 which may be appropriate on small systems without swap.
1828
1829config AIO
1830 bool "Enable AIO support" if EXPERT
1831 default y
1832 help
1833 This option enables POSIX asynchronous I/O which may by used
1834 by some high performance threaded applications. Disabling
1835 this option saves about 7k.
1836
1837config IO_URING
1838 bool "Enable IO uring support" if EXPERT
1839 select IO_WQ
1840 default y
1841 help
1842 This option enables support for the io_uring interface, enabling
1843 applications to submit and complete IO through submission and
1844 completion rings that are shared between the kernel and application.
1845
1846config GCOV_PROFILE_URING
1847 bool "Enable GCOV profiling on the io_uring subsystem"
1848 depends on IO_URING && GCOV_KERNEL
1849 help
1850 Enable GCOV profiling on the io_uring subsystem, to facilitate
1851 code coverage testing.
1852
1853 If unsure, say N.
1854
1855 Note that this will have a negative impact on the performance of
1856 the io_uring subsystem, hence this should only be enabled for
1857 specific test purposes.
1858
1859config IO_URING_MOCK_FILE
1860 tristate "Enable io_uring mock files (Experimental)" if EXPERT
1861 default n
1862 depends on IO_URING
1863 help
1864 Enable mock files for io_uring subststem testing. The ABI might
1865 still change, so it's still experimental and should only be enabled
1866 for specific test purposes.
1867
1868 If unsure, say N.
1869
1870config ADVISE_SYSCALLS
1871 bool "Enable madvise/fadvise syscalls" if EXPERT
1872 default y
1873 help
1874 This option enables the madvise and fadvise syscalls, used by
1875 applications to advise the kernel about their future memory or file
1876 usage, improving performance. If building an embedded system where no
1877 applications use these syscalls, you can disable this option to save
1878 space.
1879
1880config MEMBARRIER
1881 bool "Enable membarrier() system call" if EXPERT
1882 default y
1883 help
1884 Enable the membarrier() system call that allows issuing memory
1885 barriers across all running threads, which can be used to distribute
1886 the cost of user-space memory barriers asymmetrically by transforming
1887 pairs of memory barriers into pairs consisting of membarrier() and a
1888 compiler barrier.
1889
1890 If unsure, say Y.
1891
1892config KCMP
1893 bool "Enable kcmp() system call" if EXPERT
1894 help
1895 Enable the kernel resource comparison system call. It provides
1896 user-space with the ability to compare two processes to see if they
1897 share a common resource, such as a file descriptor or even virtual
1898 memory space.
1899
1900 If unsure, say N.
1901
1902config RSEQ
1903 bool "Enable rseq() system call" if EXPERT
1904 default y
1905 depends on HAVE_RSEQ
1906 select MEMBARRIER
1907 help
1908 Enable the restartable sequences system call. It provides a
1909 user-space cache for the current CPU number value, which
1910 speeds up getting the current CPU number from user-space,
1911 as well as an ABI to speed up user-space operations on
1912 per-CPU data.
1913
1914 If unsure, say Y.
1915
1916config DEBUG_RSEQ
1917 default n
1918 bool "Enable debugging of rseq() system call" if EXPERT
1919 depends on RSEQ && DEBUG_KERNEL
1920 help
1921 Enable extra debugging checks for the rseq system call.
1922
1923 If unsure, say N.
1924
1925config CACHESTAT_SYSCALL
1926 bool "Enable cachestat() system call" if EXPERT
1927 default y
1928 help
1929 Enable the cachestat system call, which queries the page cache
1930 statistics of a file (number of cached pages, dirty pages,
1931 pages marked for writeback, (recently) evicted pages).
1932
1933 If unsure say Y here.
1934
1935config KALLSYMS
1936 bool "Load all symbols for debugging/ksymoops" if EXPERT
1937 default y
1938 help
1939 Say Y here to let the kernel print out symbolic crash information and
1940 symbolic stack backtraces. This increases the size of the kernel
1941 somewhat, as all symbols have to be loaded into the kernel image.
1942
1943config KALLSYMS_SELFTEST
1944 bool "Test the basic functions and performance of kallsyms"
1945 depends on KALLSYMS
1946 default n
1947 help
1948 Test the basic functions and performance of some interfaces, such as
1949 kallsyms_lookup_name. It also calculates the compression rate of the
1950 kallsyms compression algorithm for the current symbol set.
1951
1952 Start self-test automatically after system startup. Suggest executing
1953 "dmesg | grep kallsyms_selftest" to collect test results. "finish" is
1954 displayed in the last line, indicating that the test is complete.
1955
1956config KALLSYMS_ALL
1957 bool "Include all symbols in kallsyms"
1958 depends on DEBUG_KERNEL && KALLSYMS
1959 help
1960 Normally kallsyms only contains the symbols of functions for nicer
1961 OOPS messages and backtraces (i.e., symbols from the text and inittext
1962 sections). This is sufficient for most cases. And only if you want to
1963 enable kernel live patching, or other less common use cases (e.g.,
1964 when a debugger is used) all symbols are required (i.e., names of
1965 variables from the data sections, etc).
1966
1967 This option makes sure that all symbols are loaded into the kernel
1968 image (i.e., symbols from all sections) in cost of increased kernel
1969 size (depending on the kernel configuration, it may be 300KiB or
1970 something like this).
1971
1972 Say N unless you really need all symbols, or kernel live patching.
1973
1974# end of the "standard kernel features (expert users)" menu
1975
1976config ARCH_HAS_MEMBARRIER_CALLBACKS
1977 bool
1978
1979config ARCH_HAS_MEMBARRIER_SYNC_CORE
1980 bool
1981
1982config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS
1983 bool
1984 help
1985 Control MSEAL_SYSTEM_MAPPINGS access based on architecture.
1986
1987 A 64-bit kernel is required for the memory sealing feature.
1988 No specific hardware features from the CPU are needed.
1989
1990 To enable this feature, the architecture needs to update their
1991 special mappings calls to include the sealing flag and confirm
1992 that it doesn't unmap/remap system mappings during the life
1993 time of the process. The existence of this flag for an architecture
1994 implies that it does not require the remapping of the system
1995 mappings during process lifetime, so sealing these mappings is safe
1996 from a kernel perspective.
1997
1998 After the architecture enables this, a distribution can set
1999 CONFIG_MSEAL_SYSTEM_MAPPING to manage access to the feature.
2000
2001 For complete descriptions of memory sealing, please see
2002 Documentation/userspace-api/mseal.rst
2003
2004config HAVE_PERF_EVENTS
2005 bool
2006 help
2007 See tools/perf/design.txt for details.
2008
2009config GUEST_PERF_EVENTS
2010 bool
2011 depends on HAVE_PERF_EVENTS
2012
2013config PERF_USE_VMALLOC
2014 bool
2015 help
2016 See tools/perf/design.txt for details
2017
2018menu "Kernel Performance Events And Counters"
2019
2020config PERF_EVENTS
2021 bool "Kernel performance events and counters"
2022 default y if PROFILING
2023 depends on HAVE_PERF_EVENTS
2024 select IRQ_WORK
2025 help
2026 Enable kernel support for various performance events provided
2027 by software and hardware.
2028
2029 Software events are supported either built-in or via the
2030 use of generic tracepoints.
2031
2032 Most modern CPUs support performance events via performance
2033 counter registers. These registers count the number of certain
2034 types of hw events: such as instructions executed, cachemisses
2035 suffered, or branches mis-predicted - without slowing down the
2036 kernel or applications. These registers can also trigger interrupts
2037 when a threshold number of events have passed - and can thus be
2038 used to profile the code that runs on that CPU.
2039
2040 The Linux Performance Event subsystem provides an abstraction of
2041 these software and hardware event capabilities, available via a
2042 system call and used by the "perf" utility in tools/perf/. It
2043 provides per task and per CPU counters, and it provides event
2044 capabilities on top of those.
2045
2046 Say Y if unsure.
2047
2048config DEBUG_PERF_USE_VMALLOC
2049 default n
2050 bool "Debug: use vmalloc to back perf mmap() buffers"
2051 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
2052 select PERF_USE_VMALLOC
2053 help
2054 Use vmalloc memory to back perf mmap() buffers.
2055
2056 Mostly useful for debugging the vmalloc code on platforms
2057 that don't require it.
2058
2059 Say N if unsure.
2060
2061endmenu
2062
2063config SYSTEM_DATA_VERIFICATION
2064 def_bool n
2065 select SYSTEM_TRUSTED_KEYRING
2066 select KEYS
2067 select CRYPTO
2068 select CRYPTO_RSA
2069 select ASYMMETRIC_KEY_TYPE
2070 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
2071 select ASN1
2072 select OID_REGISTRY
2073 select X509_CERTIFICATE_PARSER
2074 select PKCS7_MESSAGE_PARSER
2075 help
2076 Provide PKCS#7 message verification using the contents of the system
2077 trusted keyring to provide public keys. This then can be used for
2078 module verification, kexec image verification and firmware blob
2079 verification.
2080
2081config PROFILING
2082 bool "Profiling support"
2083 help
2084 Say Y here to enable the extended profiling support mechanisms used
2085 by profilers.
2086
2087config RUST
2088 bool "Rust support"
2089 depends on HAVE_RUST
2090 depends on RUST_IS_AVAILABLE
2091 select EXTENDED_MODVERSIONS if MODVERSIONS
2092 depends on !MODVERSIONS || GENDWARFKSYMS
2093 depends on !GCC_PLUGIN_RANDSTRUCT
2094 depends on !RANDSTRUCT
2095 depends on !DEBUG_INFO_BTF || (PAHOLE_HAS_LANG_EXCLUDE && !LTO)
2096 depends on !CFI || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC
2097 select CFI_ICALL_NORMALIZE_INTEGERS if CFI
2098 depends on !CALL_PADDING || RUSTC_VERSION >= 108100
2099 depends on !KASAN_SW_TAGS
2100 depends on !(MITIGATION_RETHUNK && KASAN) || RUSTC_VERSION >= 108300
2101 help
2102 Enables Rust support in the kernel.
2103
2104 This allows other Rust-related options, like drivers written in Rust,
2105 to be selected.
2106
2107 It is also required to be able to load external kernel modules
2108 written in Rust.
2109
2110 See Documentation/rust/ for more information.
2111
2112 If unsure, say N.
2113
2114config RUSTC_VERSION_TEXT
2115 string
2116 depends on RUST
2117 default "$(RUSTC_VERSION_TEXT)"
2118 help
2119 See `CC_VERSION_TEXT`.
2120
2121config BINDGEN_VERSION_TEXT
2122 string
2123 depends on RUST
2124 # The dummy parameter `workaround-for-0.69.0` is required to support 0.69.0
2125 # (https://github.com/rust-lang/rust-bindgen/pull/2678) and 0.71.0
2126 # (https://github.com/rust-lang/rust-bindgen/pull/3040). It can be removed
2127 # when the minimum version is upgraded past the latter (0.69.1 and 0.71.1
2128 # both fixed the issue).
2129 default "$(shell,$(BINDGEN) --version workaround-for-0.69.0 2>/dev/null)"
2130
2131#
2132# Place an empty function call at each tracepoint site. Can be
2133# dynamically changed for a probe function.
2134#
2135config TRACEPOINTS
2136 bool
2137 select TASKS_TRACE_RCU
2138
2139source "kernel/Kconfig.kexec"
2140
2141endmenu # General setup
2142
2143source "arch/Kconfig"
2144
2145config RT_MUTEXES
2146 bool
2147 default y if PREEMPT_RT
2148
2149config MODULE_SIG_FORMAT
2150 def_bool n
2151 select SYSTEM_DATA_VERIFICATION
2152
2153source "kernel/module/Kconfig"
2154
2155config INIT_ALL_POSSIBLE
2156 bool
2157 help
2158 Back when each arch used to define their own cpu_online_mask and
2159 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2160 with all 1s, and others with all 0s. When they were centralised,
2161 it was better to provide this option than to break all the archs
2162 and have several arch maintainers pursuing me down dark alleys.
2163
2164source "block/Kconfig"
2165
2166config PREEMPT_NOTIFIERS
2167 bool
2168
2169config PADATA
2170 depends on SMP
2171 bool
2172
2173config ASN1
2174 tristate
2175 help
2176 Build a simple ASN.1 grammar compiler that produces a bytecode output
2177 that can be interpreted by the ASN.1 stream decoder and used to
2178 inform it as to what tags are to be expected in a stream and what
2179 functions to call on what tags.
2180
2181source "kernel/Kconfig.locks"
2182
2183config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
2184 bool
2185
2186config ARCH_HAS_PREPARE_SYNC_CORE_CMD
2187 bool
2188
2189config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2190 bool
2191
2192# It may be useful for an architecture to override the definitions of the
2193# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2194# and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2195# different calling convention for syscalls. They can also override the
2196# macros for not-implemented syscalls in kernel/sys_ni.c and
2197# kernel/time/posix-stubs.c. All these overrides need to be available in
2198# <asm/syscall_wrapper.h>.
2199config ARCH_HAS_SYSCALL_WRAPPER
2200 def_bool n