Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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 ARCH_HAS_CC_CAN_LINK
86 bool
87
88config CC_CAN_LINK
89 bool
90 default ARCH_CC_CAN_LINK if ARCH_HAS_CC_CAN_LINK
91 default $(cc_can_link_user,$(m64-flag)) if 64BIT
92 default $(cc_can_link_user,$(m32-flag))
93
94# Fixed in GCC 14, 13.3, 12.4 and 11.5
95# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921
96config GCC_ASM_GOTO_OUTPUT_BROKEN
97 bool
98 depends on CC_IS_GCC
99 default y if GCC_VERSION < 110500
100 default y if GCC_VERSION >= 120000 && GCC_VERSION < 120400
101 default y if GCC_VERSION >= 130000 && GCC_VERSION < 130300
102
103config CC_HAS_ASM_GOTO_OUTPUT
104 def_bool y
105 depends on !GCC_ASM_GOTO_OUTPUT_BROKEN
106 # Detect basic support
107 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)
108 # Detect clang (< v17) scoped label issues
109 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)
110
111config CC_HAS_ASM_GOTO_TIED_OUTPUT
112 depends on CC_HAS_ASM_GOTO_OUTPUT
113 # Detect buggy gcc and clang, fixed in gcc-11 clang-14.
114 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)
115
116config TOOLS_SUPPORT_RELR
117 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
118
119config CC_HAS_ASM_INLINE
120 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
121
122config CC_HAS_ASSUME
123 bool
124 # clang needs to be at least 19.1.0 since the meaning of the assume
125 # attribute changed:
126 # https://github.com/llvm/llvm-project/commit/c44fa3e8a9a44c2e9a575768a3c185354b9f6c17
127 default y if CC_IS_CLANG && CLANG_VERSION >= 190100
128 # supported since gcc 13.1.0
129 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106654
130 default y if CC_IS_GCC && GCC_VERSION >= 130100
131
132config CC_HAS_NO_PROFILE_FN_ATTR
133 def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
134
135config CC_HAS_COUNTED_BY
136 bool
137 # clang needs to be at least 20.1.0 to avoid potential crashes
138 # when building structures that contain __counted_by
139 # https://github.com/ClangBuiltLinux/linux/issues/2114
140 # https://github.com/llvm/llvm-project/commit/160fb1121cdf703c3ef5e61fb26c5659eb581489
141 default y if CC_IS_CLANG && CLANG_VERSION >= 200100
142 # supported since gcc 15.1.0
143 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108896
144 default y if CC_IS_GCC && GCC_VERSION >= 150100
145
146config CC_HAS_COUNTED_BY_PTR
147 bool
148 # supported since clang 22
149 default y if CC_IS_CLANG && CLANG_VERSION >= 220000
150 # supported since gcc 16.0.0
151 default y if CC_IS_GCC && GCC_VERSION >= 160000
152
153config CC_HAS_BROKEN_COUNTED_BY_REF
154 bool
155 # https://github.com/llvm/llvm-project/issues/182575
156 default y if CC_IS_CLANG && CLANG_VERSION < 220100
157
158config CC_HAS_MULTIDIMENSIONAL_NONSTRING
159 def_bool $(success,echo 'char tag[][4] __attribute__((__nonstring__)) = { };' | $(CC) $(CLANG_FLAGS) -x c - -c -o /dev/null -Werror)
160
161config LD_CAN_USE_KEEP_IN_OVERLAY
162 # ld.lld prior to 21.0.0 did not support KEEP within an overlay description
163 # https://github.com/llvm/llvm-project/pull/130661
164 def_bool LD_IS_BFD || LLD_VERSION >= 210000
165
166config RUSTC_HAS_SLICE_AS_FLATTENED
167 def_bool RUSTC_VERSION >= 108000
168
169config RUSTC_HAS_COERCE_POINTEE
170 def_bool RUSTC_VERSION >= 108400
171
172config RUSTC_HAS_SPAN_FILE
173 def_bool RUSTC_VERSION >= 108800
174
175config RUSTC_HAS_UNNECESSARY_TRANSMUTES
176 def_bool RUSTC_VERSION >= 108800
177
178config RUSTC_HAS_FILE_WITH_NUL
179 def_bool RUSTC_VERSION >= 108900
180
181config RUSTC_HAS_FILE_AS_C_STR
182 def_bool RUSTC_VERSION >= 109100
183
184config PAHOLE_VERSION
185 int
186 default "$(PAHOLE_VERSION)"
187
188config CONSTRUCTORS
189 bool
190
191config IRQ_WORK
192 def_bool y if SMP
193
194config BUILDTIME_TABLE_SORT
195 bool
196
197config THREAD_INFO_IN_TASK
198 bool
199 help
200 Select this to move thread_info off the stack into task_struct. To
201 make this work, an arch will need to remove all thread_info fields
202 except flags and fix any runtime bugs.
203
204 One subtle change that will be needed is to use try_get_task_stack()
205 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
206
207menu "General setup"
208
209config BROKEN
210 bool
211 help
212 This option allows you to choose whether you want to try to
213 compile (and fix) old drivers that haven't been updated to
214 new infrastructure.
215
216config BROKEN_ON_SMP
217 bool
218 depends on BROKEN || !SMP
219 default y
220
221config INIT_ENV_ARG_LIMIT
222 int
223 default 32 if !UML
224 default 128 if UML
225 help
226 Maximum of each of the number of arguments and environment
227 variables passed to init from the kernel command line.
228
229config COMPILE_TEST
230 bool "Compile also drivers which will not load"
231 depends on HAS_IOMEM
232 help
233 Some drivers can be compiled on a different platform than they are
234 intended to be run on. Despite they cannot be loaded there (or even
235 when they load they cannot be used due to missing HW support),
236 developers still, opposing to distributors, might want to build such
237 drivers to compile-test them.
238
239 If you are a developer and want to build everything available, say Y
240 here. If you are a user/distributor, say N here to exclude useless
241 drivers to be distributed.
242
243config WERROR
244 bool "Compile the kernel with warnings as errors"
245 default COMPILE_TEST
246 help
247 A kernel build should not cause any compiler warnings, and this
248 enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags
249 to enforce that rule by default. Certain warnings from other tools
250 such as the linker may be upgraded to errors with this option as
251 well.
252
253 However, if you have a new (or very old) compiler or linker with odd
254 and unusual warnings, or you have some architecture with problems,
255 you may need to disable this config option in order to
256 successfully build the kernel.
257
258 If in doubt, say Y.
259
260config UAPI_HEADER_TEST
261 bool "Compile test UAPI headers"
262 depends on HEADERS_INSTALL
263 help
264 Compile test headers exported to user-space to ensure they are
265 self-contained, i.e. compilable as standalone units.
266
267 If you are a developer or tester and want to ensure the exported
268 headers are self-contained, say Y here. Otherwise, choose N.
269
270config LOCALVERSION
271 string "Local version - append to kernel release"
272 help
273 Append an extra string to the end of your kernel version.
274 This will show up when you type uname, for example.
275 The string you set here will be appended after the contents of
276 any files with a filename matching localversion* in your
277 object and source tree, in that order. Your total string can
278 be a maximum of 64 characters.
279
280config LOCALVERSION_AUTO
281 bool "Automatically append version information to the version string"
282 default y
283 depends on !COMPILE_TEST
284 help
285 This will try to automatically determine if the current tree is a
286 release tree by looking for git tags that belong to the current
287 top of tree revision.
288
289 A string of the format -gxxxxxxxx will be added to the localversion
290 if a git-based tree is found. The string generated by this will be
291 appended after any matching localversion* files, and after the value
292 set in CONFIG_LOCALVERSION.
293
294 (The actual string used here is the first 12 characters produced
295 by running the command:
296
297 $ git rev-parse --verify HEAD
298
299 which is done within the script "scripts/setlocalversion".)
300
301config BUILD_SALT
302 string "Build ID Salt"
303 default ""
304 help
305 The build ID is used to link binaries and their debug info. Setting
306 this option will use the value in the calculation of the build id.
307 This is mostly useful for distributions which want to ensure the
308 build is unique between builds. It's safe to leave the default.
309
310config HAVE_KERNEL_GZIP
311 bool
312
313config HAVE_KERNEL_BZIP2
314 bool
315
316config HAVE_KERNEL_LZMA
317 bool
318
319config HAVE_KERNEL_XZ
320 bool
321
322config HAVE_KERNEL_LZO
323 bool
324
325config HAVE_KERNEL_LZ4
326 bool
327
328config HAVE_KERNEL_ZSTD
329 bool
330
331config HAVE_KERNEL_UNCOMPRESSED
332 bool
333
334choice
335 prompt "Kernel compression mode"
336 default KERNEL_GZIP
337 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
338 help
339 The linux kernel is a kind of self-extracting executable.
340 Several compression algorithms are available, which differ
341 in efficiency, compression and decompression speed.
342 Compression speed is only relevant when building a kernel.
343 Decompression speed is relevant at each boot.
344
345 If you have any problems with bzip2 or lzma compressed
346 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
347 version of this functionality (bzip2 only), for 2.4, was
348 supplied by Christian Ludwig)
349
350 High compression options are mostly useful for users, who
351 are low on disk space (embedded systems), but for whom ram
352 size matters less.
353
354 If in doubt, select 'gzip'
355
356config KERNEL_GZIP
357 bool "Gzip"
358 depends on HAVE_KERNEL_GZIP
359 help
360 The old and tried gzip compression. It provides a good balance
361 between compression ratio and decompression speed.
362
363config KERNEL_BZIP2
364 bool "Bzip2"
365 depends on HAVE_KERNEL_BZIP2
366 help
367 Its compression ratio and speed is intermediate.
368 Decompression speed is slowest among the choices. The kernel
369 size is about 10% smaller with bzip2, in comparison to gzip.
370 Bzip2 uses a large amount of memory. For modern kernels you
371 will need at least 8MB RAM or more for booting.
372
373config KERNEL_LZMA
374 bool "LZMA"
375 depends on HAVE_KERNEL_LZMA
376 help
377 This compression algorithm's ratio is best. Decompression speed
378 is between gzip and bzip2. Compression is slowest.
379 The kernel size is about 33% smaller with LZMA in comparison to gzip.
380
381config KERNEL_XZ
382 bool "XZ"
383 depends on HAVE_KERNEL_XZ
384 help
385 XZ uses the LZMA2 algorithm and instruction set specific
386 BCJ filters which can improve compression ratio of executable
387 code. The size of the kernel is about 30% smaller with XZ in
388 comparison to gzip. On architectures for which there is a BCJ
389 filter (i386, x86_64, ARM, ARM64, RISC-V, big endian PowerPC,
390 and SPARC), XZ will create a few percent smaller kernel than
391 plain LZMA.
392
393 The speed is about the same as with LZMA: The decompression
394 speed of XZ is better than that of bzip2 but worse than gzip
395 and LZO. Compression is slow.
396
397config KERNEL_LZO
398 bool "LZO"
399 depends on HAVE_KERNEL_LZO
400 help
401 Its compression ratio is the poorest among the choices. The kernel
402 size is about 10% bigger than gzip; however its speed
403 (both compression and decompression) is the fastest.
404
405config KERNEL_LZ4
406 bool "LZ4"
407 depends on HAVE_KERNEL_LZ4
408 help
409 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
410 A preliminary version of LZ4 de/compression tool is available at
411 <https://code.google.com/p/lz4/>.
412
413 Its compression ratio is worse than LZO. The size of the kernel
414 is about 8% bigger than LZO. But the decompression speed is
415 faster than LZO.
416
417config KERNEL_ZSTD
418 bool "ZSTD"
419 depends on HAVE_KERNEL_ZSTD
420 help
421 ZSTD is a compression algorithm targeting intermediate compression
422 with fast decompression speed. It will compress better than GZIP and
423 decompress around the same speed as LZO, but slower than LZ4. You
424 will need at least 192 KB RAM or more for booting. The zstd command
425 line tool is required for compression.
426
427config KERNEL_UNCOMPRESSED
428 bool "None"
429 depends on HAVE_KERNEL_UNCOMPRESSED
430 help
431 Produce uncompressed kernel image. This option is usually not what
432 you want. It is useful for debugging the kernel in slow simulation
433 environments, where decompressing and moving the kernel is awfully
434 slow. This option allows early boot code to skip the decompressor
435 and jump right at uncompressed kernel image.
436
437endchoice
438
439config DEFAULT_INIT
440 string "Default init path"
441 default ""
442 help
443 This option determines the default init for the system if no init=
444 option is passed on the kernel command line. If the requested path is
445 not present, we will still then move on to attempting further
446 locations (e.g. /sbin/init, etc). If this is empty, we will just use
447 the fallback list when init= is not passed.
448
449config DEFAULT_HOSTNAME
450 string "Default hostname"
451 default "(none)"
452 help
453 This option determines the default system hostname before userspace
454 calls sethostname(2). The kernel traditionally uses "(none)" here,
455 but you may wish to use a different default here to make a minimal
456 system more usable with less configuration.
457
458config SYSVIPC
459 bool "System V IPC"
460 help
461 Inter Process Communication is a suite of library functions and
462 system calls which let processes (running programs) synchronize and
463 exchange information. It is generally considered to be a good thing,
464 and some programs won't run unless you say Y here. In particular, if
465 you want to run the DOS emulator dosemu under Linux (read the
466 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
467 you'll need to say Y here.
468
469 You can find documentation about IPC with "info ipc" and also in
470 section 6.4 of the Linux Programmer's Guide, available from
471 <http://www.tldp.org/guides.html>.
472
473config SYSVIPC_SYSCTL
474 bool
475 depends on SYSVIPC
476 depends on SYSCTL
477 default y
478
479config SYSVIPC_COMPAT
480 def_bool y
481 depends on COMPAT && SYSVIPC
482
483config POSIX_MQUEUE
484 bool "POSIX Message Queues"
485 depends on NET
486 help
487 POSIX variant of message queues is a part of IPC. In POSIX message
488 queues every message has a priority which decides about succession
489 of receiving it by a process. If you want to compile and run
490 programs written e.g. for Solaris with use of its POSIX message
491 queues (functions mq_*) say Y here.
492
493 POSIX message queues are visible as a filesystem called 'mqueue'
494 and can be mounted somewhere if you want to do filesystem
495 operations on message queues.
496
497 If unsure, say Y.
498
499config POSIX_MQUEUE_SYSCTL
500 bool
501 depends on POSIX_MQUEUE
502 depends on SYSCTL
503 default y
504
505config WATCH_QUEUE
506 bool "General notification queue"
507 default n
508 help
509
510 This is a general notification queue for the kernel to pass events to
511 userspace by splicing them into pipes. It can be used in conjunction
512 with watches for key/keyring change notifications and device
513 notifications.
514
515 See Documentation/core-api/watch_queue.rst
516
517config CROSS_MEMORY_ATTACH
518 bool "Enable process_vm_readv/writev syscalls"
519 depends on MMU
520 default y
521 help
522 Enabling this option adds the system calls process_vm_readv and
523 process_vm_writev which allow a process with the correct privileges
524 to directly read from or write to another process' address space.
525 See the man page for more details.
526
527config AUDIT
528 bool "Auditing support"
529 depends on NET
530 help
531 Enable auditing infrastructure that can be used with another
532 kernel subsystem, such as SELinux (which requires this for
533 logging of avc messages output). System call auditing is included
534 on architectures which support it.
535
536config HAVE_ARCH_AUDITSYSCALL
537 bool
538
539config AUDITSYSCALL
540 def_bool y
541 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
542 select FSNOTIFY
543
544source "kernel/irq/Kconfig"
545source "kernel/time/Kconfig"
546source "kernel/bpf/Kconfig"
547source "kernel/Kconfig.preempt"
548
549menu "CPU/Task time and stats accounting"
550
551config VIRT_CPU_ACCOUNTING
552 bool
553
554choice
555 prompt "Cputime accounting"
556 default TICK_CPU_ACCOUNTING
557
558# Kind of a stub config for the pure tick based cputime accounting
559config TICK_CPU_ACCOUNTING
560 bool "Simple tick based cputime accounting"
561 depends on !S390 && !NO_HZ_FULL
562 help
563 This is the basic tick based cputime accounting that maintains
564 statistics about user, system and idle time spent on per jiffies
565 granularity.
566
567 If unsure, say Y.
568
569config VIRT_CPU_ACCOUNTING_NATIVE
570 bool "Deterministic task and CPU time accounting"
571 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
572 select VIRT_CPU_ACCOUNTING
573 help
574 Select this option to enable more accurate task and CPU time
575 accounting. This is done by reading a CPU counter on each
576 kernel entry and exit and on transitions within the kernel
577 between system, softirq and hardirq state, so there is a
578 small performance impact. In the case of s390 or IBM POWER > 5,
579 this also enables accounting of stolen time on logically-partitioned
580 systems.
581
582config VIRT_CPU_ACCOUNTING_GEN
583 bool "Full dynticks CPU time accounting"
584 depends on HAVE_CONTEXT_TRACKING_USER
585 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
586 depends on GENERIC_CLOCKEVENTS
587 select VIRT_CPU_ACCOUNTING
588 select CONTEXT_TRACKING_USER
589 help
590 Select this option to enable task and CPU time accounting on full
591 dynticks systems. This accounting is implemented by watching every
592 kernel-user boundaries using the context tracking subsystem.
593 The accounting is thus performed at the expense of some significant
594 overhead.
595
596 For now this is only useful if you are working on the full
597 dynticks subsystem development.
598
599 If unsure, say N.
600
601endchoice
602
603config IRQ_TIME_ACCOUNTING
604 bool "Fine granularity task level IRQ time accounting"
605 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
606 help
607 Select this option to enable fine granularity task irq time
608 accounting. This is done by reading a timestamp on each
609 transitions between softirq and hardirq state, so there can be a
610 small performance impact.
611
612 If in doubt, say N here.
613
614config HAVE_SCHED_AVG_IRQ
615 def_bool y
616 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
617 depends on SMP
618
619config SCHED_HW_PRESSURE
620 bool
621 default y if ARM && ARM_CPU_TOPOLOGY
622 default y if ARM64
623 depends on SMP
624 depends on CPU_FREQ_THERMAL
625 help
626 Select this option to enable HW pressure accounting in the
627 scheduler. HW pressure is the value conveyed to the scheduler
628 that reflects the reduction in CPU compute capacity resulted from
629 HW throttling. HW throttling occurs when the performance of
630 a CPU is capped due to high operating temperatures as an example.
631
632 If selected, the scheduler will be able to balance tasks accordingly,
633 i.e. put less load on throttled CPUs than on non/less throttled ones.
634
635 This requires the architecture to implement
636 arch_update_hw_pressure() and arch_scale_thermal_pressure().
637
638config BSD_PROCESS_ACCT
639 bool "BSD Process Accounting (DEPRECATED)"
640 depends on MULTIUSER
641 default n
642 help
643 If you say Y here, a user level program will be able to instruct the
644 kernel (via a special system call) to write process accounting
645 information to a file: whenever a process exits, information about
646 that process will be appended to the file by the kernel. The
647 information includes things such as creation time, owning user,
648 command name, memory usage, controlling terminal etc. (the complete
649 list is in the struct acct in <file:include/linux/acct.h>). It is
650 up to the user level program to do useful things with this
651 information. This mechanism is antiquated and has significant
652 scalability issues. You probably want to use eBPF instead. Say
653 N unless you really need this.
654
655config BSD_PROCESS_ACCT_V3
656 bool "BSD Process Accounting version 3 file format"
657 depends on BSD_PROCESS_ACCT
658 default n
659 help
660 If you say Y here, the process accounting information is written
661 in a new file format that also logs the process IDs of each
662 process and its parent. Note that this file format is incompatible
663 with previous v0/v1/v2 file formats, so you will need updated tools
664 for processing it. A preliminary version of these tools is available
665 at <http://www.gnu.org/software/acct/>.
666
667config TASKSTATS
668 bool "Export task/process statistics through netlink"
669 depends on NET
670 depends on MULTIUSER
671 default n
672 help
673 Export selected statistics for tasks/processes through the
674 generic netlink interface. Unlike BSD process accounting, the
675 statistics are available during the lifetime of tasks/processes as
676 responses to commands. Like BSD accounting, they are sent to user
677 space on task exit.
678
679 Say N if unsure.
680
681config TASK_DELAY_ACCT
682 bool "Enable per-task delay accounting"
683 depends on TASKSTATS
684 select SCHED_INFO
685 help
686 Collect information on time spent by a task waiting for system
687 resources like cpu, synchronous block I/O completion and swapping
688 in pages. Such statistics can help in setting a task's priorities
689 relative to other tasks for cpu, io, rss limits etc.
690
691 Say N if unsure.
692
693config TASK_XACCT
694 bool "Enable extended accounting over taskstats"
695 depends on TASKSTATS
696 help
697 Collect extended task accounting data and send the data
698 to userland for processing over the taskstats interface.
699
700 Say N if unsure.
701
702config TASK_IO_ACCOUNTING
703 bool "Enable per-task storage I/O accounting"
704 depends on TASK_XACCT
705 help
706 Collect information on the number of bytes of storage I/O which this
707 task has caused.
708
709 Say N if unsure.
710
711config PSI
712 bool "Pressure stall information tracking"
713 select KERNFS
714 help
715 Collect metrics that indicate how overcommitted the CPU, memory,
716 and IO capacity are in the system.
717
718 If you say Y here, the kernel will create /proc/pressure/ with the
719 pressure statistics files cpu, memory, and io. These will indicate
720 the share of walltime in which some or all tasks in the system are
721 delayed due to contention of the respective resource.
722
723 In kernels with cgroup support, cgroups (cgroup2 only) will
724 have cpu.pressure, memory.pressure, and io.pressure files,
725 which aggregate pressure stalls for the grouped tasks only.
726
727 For more details see Documentation/accounting/psi.rst.
728
729 Say N if unsure.
730
731config PSI_DEFAULT_DISABLED
732 bool "Require boot parameter to enable pressure stall information tracking"
733 default n
734 depends on PSI
735 help
736 If set, pressure stall information tracking will be disabled
737 per default but can be enabled through passing psi=1 on the
738 kernel commandline during boot.
739
740 This feature adds some code to the task wakeup and sleep
741 paths of the scheduler. The overhead is too low to affect
742 common scheduling-intense workloads in practice (such as
743 webservers, memcache), but it does show up in artificial
744 scheduler stress tests, such as hackbench.
745
746 If you are paranoid and not sure what the kernel will be
747 used for, say Y.
748
749 Say N if unsure.
750
751endmenu # "CPU/Task time and stats accounting"
752
753config CPU_ISOLATION
754 bool "CPU isolation"
755 depends on SMP
756 default y
757 help
758 Make sure that CPUs running critical tasks are not disturbed by
759 any source of "noise" such as unbound workqueues, timers, kthreads...
760 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
761 the "isolcpus=" boot parameter.
762
763 Say Y if unsure.
764
765source "kernel/rcu/Kconfig"
766
767config IKCONFIG
768 tristate "Kernel .config support"
769 help
770 This option enables the complete Linux kernel ".config" file
771 contents to be saved in the kernel. It provides documentation
772 of which kernel options are used in a running kernel or in an
773 on-disk kernel. This information can be extracted from the kernel
774 image file with the script scripts/extract-ikconfig and used as
775 input to rebuild the current kernel or to build another kernel.
776 It can also be extracted from a running kernel by reading
777 /proc/config.gz if enabled (below).
778
779config IKCONFIG_PROC
780 bool "Enable access to .config through /proc/config.gz"
781 depends on IKCONFIG && PROC_FS
782 help
783 This option enables access to the kernel configuration file
784 through /proc/config.gz.
785
786config IKHEADERS
787 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
788 depends on SYSFS
789 help
790 This option enables access to the in-kernel headers that are generated during
791 the build process. These can be used to build eBPF tracing programs,
792 or similar programs. If you build the headers as a module, a module called
793 kheaders.ko is built which can be loaded on-demand to get access to headers.
794
795config LOG_BUF_SHIFT
796 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
797 range 12 25
798 default 17
799 depends on PRINTK
800 help
801 Select the minimal kernel log buffer size as a power of 2.
802 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
803 parameter, see below. Any higher size also might be forced
804 by "log_buf_len" boot parameter.
805
806 Examples:
807 17 => 128 KB
808 16 => 64 KB
809 15 => 32 KB
810 14 => 16 KB
811 13 => 8 KB
812 12 => 4 KB
813
814config LOG_CPU_MAX_BUF_SHIFT
815 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
816 depends on SMP
817 range 0 21
818 default 0 if BASE_SMALL
819 default 12
820 depends on PRINTK
821 help
822 This option allows to increase the default ring buffer size
823 according to the number of CPUs. The value defines the contribution
824 of each CPU as a power of 2. The used space is typically only few
825 lines however it might be much more when problems are reported,
826 e.g. backtraces.
827
828 The increased size means that a new buffer has to be allocated and
829 the original static one is unused. It makes sense only on systems
830 with more CPUs. Therefore this value is used only when the sum of
831 contributions is greater than the half of the default kernel ring
832 buffer as defined by LOG_BUF_SHIFT. The default values are set
833 so that more than 16 CPUs are needed to trigger the allocation.
834
835 Also this option is ignored when "log_buf_len" kernel parameter is
836 used as it forces an exact (power of two) size of the ring buffer.
837
838 The number of possible CPUs is used for this computation ignoring
839 hotplugging making the computation optimal for the worst case
840 scenario while allowing a simple algorithm to be used from bootup.
841
842 Examples shift values and their meaning:
843 17 => 128 KB for each CPU
844 16 => 64 KB for each CPU
845 15 => 32 KB for each CPU
846 14 => 16 KB for each CPU
847 13 => 8 KB for each CPU
848 12 => 4 KB for each CPU
849
850config PRINTK_INDEX
851 bool "Printk indexing debugfs interface"
852 depends on PRINTK && DEBUG_FS
853 help
854 Add support for indexing of all printk formats known at compile time
855 at <debugfs>/printk/index/<module>.
856
857 This can be used as part of maintaining daemons which monitor
858 /dev/kmsg, as it permits auditing the printk formats present in a
859 kernel, allowing detection of cases where monitored printks are
860 changed or no longer present.
861
862 There is no additional runtime cost to printk with this enabled.
863
864#
865# Architectures with an unreliable sched_clock() should select this:
866#
867config HAVE_UNSTABLE_SCHED_CLOCK
868 bool
869
870config GENERIC_SCHED_CLOCK
871 bool
872
873menu "Scheduler features"
874
875config UCLAMP_TASK
876 bool "Enable utilization clamping for RT/FAIR tasks"
877 depends on CPU_FREQ_GOV_SCHEDUTIL
878 help
879 This feature enables the scheduler to track the clamped utilization
880 of each CPU based on RUNNABLE tasks scheduled on that CPU.
881
882 With this option, the user can specify the min and max CPU
883 utilization allowed for RUNNABLE tasks. The max utilization defines
884 the maximum frequency a task should use while the min utilization
885 defines the minimum frequency it should use.
886
887 Both min and max utilization clamp values are hints to the scheduler,
888 aiming at improving its frequency selection policy, but they do not
889 enforce or grant any specific bandwidth for tasks.
890
891 If in doubt, say N.
892
893config UCLAMP_BUCKETS_COUNT
894 int "Number of supported utilization clamp buckets"
895 range 5 20
896 default 5
897 depends on UCLAMP_TASK
898 help
899 Defines the number of clamp buckets to use. The range of each bucket
900 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
901 number of clamp buckets the finer their granularity and the higher
902 the precision of clamping aggregation and tracking at run-time.
903
904 For example, with the minimum configuration value we will have 5
905 clamp buckets tracking 20% utilization each. A 25% boosted tasks will
906 be refcounted in the [20..39]% bucket and will set the bucket clamp
907 effective value to 25%.
908 If a second 30% boosted task should be co-scheduled on the same CPU,
909 that task will be refcounted in the same bucket of the first task and
910 it will boost the bucket clamp effective value to 30%.
911 The clamp effective value of a bucket is reset to its nominal value
912 (20% in the example above) when there are no more tasks refcounted in
913 that bucket.
914
915 An additional boost/capping margin can be added to some tasks. In the
916 example above the 25% task will be boosted to 30% until it exits the
917 CPU. If that should be considered not acceptable on certain systems,
918 it's always possible to reduce the margin by increasing the number of
919 clamp buckets to trade off used memory for run-time tracking
920 precision.
921
922 If in doubt, use the default value.
923
924config SCHED_PROXY_EXEC
925 bool "Proxy Execution"
926 # Avoid some build failures w/ PREEMPT_RT until it can be fixed
927 depends on !PREEMPT_RT
928 # Need to investigate how to inform sched_ext of split contexts
929 depends on !SCHED_CLASS_EXT
930 # Not particularly useful until we get to multi-rq proxying
931 depends on EXPERT
932 help
933 This option enables proxy execution, a mechanism for mutex-owning
934 tasks to inherit the scheduling context of higher priority waiters.
935
936endmenu
937
938#
939# For architectures that want to enable the support for NUMA-affine scheduler
940# balancing logic:
941#
942config ARCH_SUPPORTS_NUMA_BALANCING
943 bool
944
945#
946# For architectures that prefer to flush all TLBs after a number of pages
947# are unmapped instead of sending one IPI per page to flush. The architecture
948# must provide guarantees on what happens if a clean TLB cache entry is
949# written after the unmap. Details are in mm/rmap.c near the check for
950# should_defer_flush. The architecture should also consider if the full flush
951# and the refill costs are offset by the savings of sending fewer IPIs.
952config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
953 bool
954
955config CC_HAS_INT128
956 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
957
958config CC_IMPLICIT_FALLTHROUGH
959 string
960 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5)
961 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough)
962
963# Currently, disable gcc-10+ array-bounds globally.
964# It's still broken in gcc-13, so no upper bound yet.
965config GCC10_NO_ARRAY_BOUNDS
966 def_bool y
967
968config CC_NO_ARRAY_BOUNDS
969 bool
970 default y if CC_IS_GCC && GCC_VERSION >= 90000 && GCC10_NO_ARRAY_BOUNDS
971
972# Currently, disable -Wstringop-overflow for GCC globally.
973config GCC_NO_STRINGOP_OVERFLOW
974 def_bool y
975
976config CC_NO_STRINGOP_OVERFLOW
977 bool
978 default y if CC_IS_GCC && GCC_NO_STRINGOP_OVERFLOW
979
980config CC_STRINGOP_OVERFLOW
981 bool
982 default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW
983
984#
985# For architectures that know their GCC __int128 support is sound
986#
987config ARCH_SUPPORTS_INT128
988 bool
989
990# For architectures that (ab)use NUMA to represent different memory regions
991# all cpu-local but of different latencies, such as SuperH.
992#
993config ARCH_WANT_NUMA_VARIABLE_LOCALITY
994 bool
995
996config NUMA_BALANCING
997 bool "Memory placement aware NUMA scheduler"
998 depends on ARCH_SUPPORTS_NUMA_BALANCING
999 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
1000 depends on SMP && NUMA && MIGRATION && !PREEMPT_RT
1001 help
1002 This option adds support for automatic NUMA aware memory/task placement.
1003 The mechanism is quite primitive and is based on migrating memory when
1004 it has references to the node the task is running on.
1005
1006 This system will be inactive on UMA systems.
1007
1008config NUMA_BALANCING_DEFAULT_ENABLED
1009 bool "Automatically enable NUMA aware memory/task placement"
1010 default y
1011 depends on NUMA_BALANCING
1012 help
1013 If set, automatic NUMA balancing will be enabled if running on a NUMA
1014 machine.
1015
1016config SLAB_OBJ_EXT
1017 bool
1018
1019menuconfig CGROUPS
1020 bool "Control Group support"
1021 select KERNFS
1022 help
1023 This option adds support for grouping sets of processes together, for
1024 use with process control subsystems such as Cpusets, CFS, memory
1025 controls or device isolation.
1026 See
1027 - Documentation/scheduler/sched-design-CFS.rst (CFS)
1028 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
1029 and resource control)
1030
1031 Say N if unsure.
1032
1033if CGROUPS
1034
1035config PAGE_COUNTER
1036 bool
1037
1038config CGROUP_FAVOR_DYNMODS
1039 bool "Favor dynamic modification latency reduction by default"
1040 help
1041 This option enables the "favordynmods" mount option by default
1042 which reduces the latencies of dynamic cgroup modifications such
1043 as task migrations and controller on/offs at the cost of making
1044 hot path operations such as forks and exits more expensive.
1045
1046 Say N if unsure.
1047
1048config MEMCG
1049 bool "Memory controller"
1050 select PAGE_COUNTER
1051 select EVENTFD
1052 select SLAB_OBJ_EXT
1053 select VM_EVENT_COUNTERS
1054 help
1055 Provides control over the memory footprint of tasks in a cgroup.
1056
1057config MEMCG_NMI_UNSAFE
1058 bool
1059 depends on MEMCG
1060 depends on HAVE_NMI
1061 depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && !ARCH_HAVE_NMI_SAFE_CMPXCHG
1062 default y
1063
1064config MEMCG_NMI_SAFETY_REQUIRES_ATOMIC
1065 bool
1066 depends on MEMCG
1067 depends on HAVE_NMI
1068 depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && ARCH_HAVE_NMI_SAFE_CMPXCHG
1069 default y
1070
1071config MEMCG_V1
1072 bool "Legacy cgroup v1 memory controller"
1073 depends on MEMCG
1074 default n
1075 help
1076 Legacy cgroup v1 memory controller which has been deprecated by
1077 cgroup v2 implementation. The v1 is there for legacy applications
1078 which haven't migrated to the new cgroup v2 interface yet. If you
1079 do not have any such application then you are completely fine leaving
1080 this option disabled.
1081
1082 Please note that feature set of the legacy memory controller is likely
1083 going to shrink due to deprecation process. New deployments with v1
1084 controller are highly discouraged.
1085
1086 Say N if unsure.
1087
1088config BLK_CGROUP
1089 bool "IO controller"
1090 depends on BLOCK
1091 default n
1092 help
1093 Generic block IO controller cgroup interface. This is the common
1094 cgroup interface which should be used by various IO controlling
1095 policies.
1096
1097 Currently, CFQ IO scheduler uses it to recognize task groups and
1098 control disk bandwidth allocation (proportional time slice allocation)
1099 to such task groups. It is also used by bio throttling logic in
1100 block layer to implement upper limit in IO rates on a device.
1101
1102 This option only enables generic Block IO controller infrastructure.
1103 One needs to also enable actual IO controlling logic/policy. For
1104 enabling proportional weight division of disk bandwidth in CFQ, set
1105 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1106 CONFIG_BLK_DEV_THROTTLING=y.
1107
1108 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
1109
1110config CGROUP_WRITEBACK
1111 bool
1112 depends on MEMCG && BLK_CGROUP
1113 default y
1114
1115menuconfig CGROUP_SCHED
1116 bool "CPU controller"
1117 default n
1118 help
1119 This feature lets CPU scheduler recognize task groups and control CPU
1120 bandwidth allocation to such task groups. It uses cgroups to group
1121 tasks.
1122
1123if CGROUP_SCHED
1124config GROUP_SCHED_WEIGHT
1125 def_bool n
1126
1127config GROUP_SCHED_BANDWIDTH
1128 def_bool n
1129
1130config FAIR_GROUP_SCHED
1131 bool "Group scheduling for SCHED_OTHER"
1132 depends on CGROUP_SCHED
1133 select GROUP_SCHED_WEIGHT
1134 default CGROUP_SCHED
1135
1136config CFS_BANDWIDTH
1137 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
1138 depends on FAIR_GROUP_SCHED
1139 select GROUP_SCHED_BANDWIDTH
1140 default n
1141 help
1142 This option allows users to define CPU bandwidth rates (limits) for
1143 tasks running within the fair group scheduler. Groups with no limit
1144 set are considered to be unconstrained and will run with no
1145 restriction.
1146 See Documentation/scheduler/sched-bwc.rst for more information.
1147
1148config RT_GROUP_SCHED
1149 bool "Group scheduling for SCHED_RR/FIFO"
1150 depends on CGROUP_SCHED
1151 default n
1152 help
1153 This feature lets you explicitly allocate real CPU bandwidth
1154 to task groups. If enabled, it will also make it impossible to
1155 schedule realtime tasks for non-root users until you allocate
1156 realtime bandwidth for them.
1157 See Documentation/scheduler/sched-rt-group.rst for more information.
1158
1159config RT_GROUP_SCHED_DEFAULT_DISABLED
1160 bool "Require boot parameter to enable group scheduling for SCHED_RR/FIFO"
1161 depends on RT_GROUP_SCHED
1162 default n
1163 help
1164 When set, the RT group scheduling is disabled by default. The option
1165 is in inverted form so that mere RT_GROUP_SCHED enables the group
1166 scheduling.
1167
1168 Say N if unsure.
1169
1170config EXT_GROUP_SCHED
1171 bool
1172 depends on SCHED_CLASS_EXT && CGROUP_SCHED
1173 select GROUP_SCHED_WEIGHT
1174 select GROUP_SCHED_BANDWIDTH
1175 default y
1176
1177endif #CGROUP_SCHED
1178
1179config SCHED_MM_CID
1180 def_bool y
1181 depends on SMP && RSEQ
1182
1183config UCLAMP_TASK_GROUP
1184 bool "Utilization clamping per group of tasks"
1185 depends on CGROUP_SCHED
1186 depends on UCLAMP_TASK
1187 default n
1188 help
1189 This feature enables the scheduler to track the clamped utilization
1190 of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
1191
1192 When this option is enabled, the user can specify a min and max
1193 CPU bandwidth which is allowed for each single task in a group.
1194 The max bandwidth allows to clamp the maximum frequency a task
1195 can use, while the min bandwidth allows to define a minimum
1196 frequency a task will always use.
1197
1198 When task group based utilization clamping is enabled, an eventually
1199 specified task-specific clamp value is constrained by the cgroup
1200 specified clamp value. Both minimum and maximum task clamping cannot
1201 be bigger than the corresponding clamping defined at task group level.
1202
1203 If in doubt, say N.
1204
1205config CGROUP_PIDS
1206 bool "PIDs controller"
1207 help
1208 Provides enforcement of process number limits in the scope of a
1209 cgroup. Any attempt to fork more processes than is allowed in the
1210 cgroup will fail. PIDs are fundamentally a global resource because it
1211 is fairly trivial to reach PID exhaustion before you reach even a
1212 conservative kmemcg limit. As a result, it is possible to grind a
1213 system to halt without being limited by other cgroup policies. The
1214 PIDs controller is designed to stop this from happening.
1215
1216 It should be noted that organisational operations (such as attaching
1217 to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
1218 since the PIDs limit only affects a process's ability to fork, not to
1219 attach to a cgroup.
1220
1221config CGROUP_RDMA
1222 bool "RDMA controller"
1223 help
1224 Provides enforcement of RDMA resources defined by IB stack.
1225 It is fairly easy for consumers to exhaust RDMA resources, which
1226 can result into resource unavailability to other consumers.
1227 RDMA controller is designed to stop this from happening.
1228 Attaching processes with active RDMA resources to the cgroup
1229 hierarchy is allowed even if can cross the hierarchy's limit.
1230
1231config CGROUP_DMEM
1232 bool "Device memory controller (DMEM)"
1233 select PAGE_COUNTER
1234 help
1235 The DMEM controller allows compatible devices to restrict device
1236 memory usage based on the cgroup hierarchy.
1237
1238 As an example, it allows you to restrict VRAM usage for applications
1239 in the DRM subsystem.
1240
1241config CGROUP_FREEZER
1242 bool "Freezer controller"
1243 help
1244 Provides a way to freeze and unfreeze all tasks in a
1245 cgroup.
1246
1247 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1248 controller includes important in-kernel memory consumers per default.
1249
1250 If you're using cgroup2, say N.
1251
1252config CGROUP_HUGETLB
1253 bool "HugeTLB controller"
1254 depends on HUGETLB_PAGE
1255 select PAGE_COUNTER
1256 default n
1257 help
1258 Provides a cgroup controller for HugeTLB pages.
1259 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1260 The limit is enforced during page fault. Since HugeTLB doesn't
1261 support page reclaim, enforcing the limit at page fault time implies
1262 that, the application will get SIGBUS signal if it tries to access
1263 HugeTLB pages beyond its limit. This requires the application to know
1264 beforehand how much HugeTLB pages it would require for its use. The
1265 control group is tracked in the third page lru pointer. This means
1266 that we cannot use the controller with huge page less than 3 pages.
1267
1268config CPUSETS
1269 bool "Cpuset controller"
1270 depends on SMP
1271 select UNION_FIND
1272 select CPU_ISOLATION
1273 help
1274 This option will let you create and manage CPUSETs which
1275 allow dynamically partitioning a system into sets of CPUs and
1276 Memory Nodes and assigning tasks to run only within those sets.
1277 This is primarily useful on large SMP or NUMA systems.
1278
1279 Say N if unsure.
1280
1281config CPUSETS_V1
1282 bool "Legacy cgroup v1 cpusets controller"
1283 depends on CPUSETS
1284 default n
1285 help
1286 Legacy cgroup v1 cpusets controller which has been deprecated by
1287 cgroup v2 implementation. The v1 is there for legacy applications
1288 which haven't migrated to the new cgroup v2 interface yet. Legacy
1289 interface includes cpuset filesystem and /proc/<pid>/cpuset. If you
1290 do not have any such application then you are completely fine leaving
1291 this option disabled.
1292
1293 Say N if unsure.
1294
1295config PROC_PID_CPUSET
1296 bool "Include legacy /proc/<pid>/cpuset file"
1297 depends on CPUSETS_V1
1298 default y
1299
1300config CGROUP_DEVICE
1301 bool "Device controller"
1302 help
1303 Provides a cgroup controller implementing whitelists for
1304 devices which a process in the cgroup can mknod or open.
1305
1306config CGROUP_CPUACCT
1307 bool "Simple CPU accounting controller"
1308 help
1309 Provides a simple controller for monitoring the
1310 total CPU consumed by the tasks in a cgroup.
1311
1312config CGROUP_PERF
1313 bool "Perf controller"
1314 depends on PERF_EVENTS
1315 help
1316 This option extends the perf per-cpu mode to restrict monitoring
1317 to threads which belong to the cgroup specified and run on the
1318 designated cpu. Or this can be used to have cgroup ID in samples
1319 so that it can monitor performance events among cgroups.
1320
1321 Say N if unsure.
1322
1323config CGROUP_BPF
1324 bool "Support for eBPF programs attached to cgroups"
1325 depends on BPF_SYSCALL
1326 select SOCK_CGROUP_DATA
1327 help
1328 Allow attaching eBPF programs to a cgroup using the bpf(2)
1329 syscall command BPF_PROG_ATTACH.
1330
1331 In which context these programs are accessed depends on the type
1332 of attachment. For instance, programs that are attached using
1333 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1334 inet sockets.
1335
1336config CGROUP_MISC
1337 bool "Misc resource controller"
1338 default n
1339 help
1340 Provides a controller for miscellaneous resources on a host.
1341
1342 Miscellaneous scalar resources are the resources on the host system
1343 which cannot be abstracted like the other cgroups. This controller
1344 tracks and limits the miscellaneous resources used by a process
1345 attached to a cgroup hierarchy.
1346
1347 For more information, please check misc cgroup section in
1348 /Documentation/admin-guide/cgroup-v2.rst.
1349
1350config CGROUP_DEBUG
1351 bool "Debug controller"
1352 default n
1353 depends on DEBUG_KERNEL
1354 help
1355 This option enables a simple controller that exports
1356 debugging information about the cgroups framework. This
1357 controller is for control cgroup debugging only. Its
1358 interfaces are not stable.
1359
1360 Say N.
1361
1362config SOCK_CGROUP_DATA
1363 bool
1364 default n
1365
1366endif # CGROUPS
1367
1368menuconfig NAMESPACES
1369 bool "Namespaces support" if EXPERT
1370 depends on MULTIUSER
1371 default !EXPERT
1372 help
1373 Provides the way to make tasks work with different objects using
1374 the same id. For example same IPC id may refer to different objects
1375 or same user id or pid may refer to different tasks when used in
1376 different namespaces.
1377
1378if NAMESPACES
1379
1380config UTS_NS
1381 bool "UTS namespace"
1382 default y
1383 help
1384 In this namespace tasks see different info provided with the
1385 uname() system call
1386
1387config TIME_NS
1388 bool "TIME namespace"
1389 depends on GENERIC_GETTIMEOFDAY
1390 default y
1391 help
1392 In this namespace boottime and monotonic clocks can be set.
1393 The time will keep going with the same pace.
1394
1395config IPC_NS
1396 bool "IPC namespace"
1397 depends on (SYSVIPC || POSIX_MQUEUE)
1398 default y
1399 help
1400 In this namespace tasks work with IPC ids which correspond to
1401 different IPC objects in different namespaces.
1402
1403config USER_NS
1404 bool "User namespace"
1405 default n
1406 help
1407 This allows containers, i.e. vservers, to use user namespaces
1408 to provide different user info for different servers.
1409
1410 When user namespaces are enabled in the kernel it is
1411 recommended that the MEMCG option also be enabled and that
1412 user-space use the memory control groups to limit the amount
1413 of memory a memory unprivileged users can use.
1414
1415 If unsure, say N.
1416
1417config PID_NS
1418 bool "PID Namespaces"
1419 default y
1420 help
1421 Support process id namespaces. This allows having multiple
1422 processes with the same pid as long as they are in different
1423 pid namespaces. This is a building block of containers.
1424
1425config NET_NS
1426 bool "Network namespace"
1427 depends on NET
1428 default y
1429 help
1430 Allow user space to create what appear to be multiple instances
1431 of the network stack.
1432
1433endif # NAMESPACES
1434
1435config CHECKPOINT_RESTORE
1436 bool "Checkpoint/restore support"
1437 depends on PROC_FS
1438 select PROC_CHILDREN
1439 select KCMP
1440 default n
1441 help
1442 Enables additional kernel features in a sake of checkpoint/restore.
1443 In particular it adds auxiliary prctl codes to setup process text,
1444 data and heap segment sizes, and a few additional /proc filesystem
1445 entries.
1446
1447 If unsure, say N here.
1448
1449config SCHED_AUTOGROUP
1450 bool "Automatic process group scheduling"
1451 select CGROUPS
1452 select CGROUP_SCHED
1453 select FAIR_GROUP_SCHED
1454 help
1455 This option optimizes the scheduler for common desktop workloads by
1456 automatically creating and populating task groups. This separation
1457 of workloads isolates aggressive CPU burners (like build jobs) from
1458 desktop applications. Task group autogeneration is currently based
1459 upon task session.
1460
1461config RELAY
1462 bool "Kernel->user space relay support (formerly relayfs)"
1463 select IRQ_WORK
1464 help
1465 This option enables support for relay interface support in
1466 certain file systems (such as debugfs).
1467 It is designed to provide an efficient mechanism for tools and
1468 facilities to relay large amounts of data from kernel space to
1469 user space.
1470
1471 If unsure, say N.
1472
1473config BLK_DEV_INITRD
1474 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1475 help
1476 The initial RAM filesystem is a ramfs which is loaded by the
1477 boot loader (loadlin or lilo) and that is mounted as root
1478 before the normal boot procedure. It is typically used to
1479 load modules needed to mount the "real" root file system,
1480 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1481
1482 If RAM disk support (BLK_DEV_RAM) is also included, this
1483 also enables initial RAM disk (initrd) support and adds
1484 15 Kbytes (more on some other architectures) to the kernel size.
1485
1486 If unsure say Y.
1487
1488if BLK_DEV_INITRD
1489
1490source "usr/Kconfig"
1491
1492endif
1493
1494config BOOT_CONFIG
1495 bool "Boot config support"
1496 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED
1497 help
1498 Extra boot config allows system admin to pass a config file as
1499 complemental extension of kernel cmdline when booting.
1500 The boot config file must be attached at the end of initramfs
1501 with checksum, size and magic word.
1502 See <file:Documentation/admin-guide/bootconfig.rst> for details.
1503
1504 If unsure, say Y.
1505
1506config BOOT_CONFIG_FORCE
1507 bool "Force unconditional bootconfig processing"
1508 depends on BOOT_CONFIG
1509 default y if BOOT_CONFIG_EMBED
1510 help
1511 With this Kconfig option set, BOOT_CONFIG processing is carried
1512 out even when the "bootconfig" kernel-boot parameter is omitted.
1513 In fact, with this Kconfig option set, there is no way to
1514 make the kernel ignore the BOOT_CONFIG-supplied kernel-boot
1515 parameters.
1516
1517 If unsure, say N.
1518
1519config BOOT_CONFIG_EMBED
1520 bool "Embed bootconfig file in the kernel"
1521 depends on BOOT_CONFIG
1522 help
1523 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the
1524 kernel. Usually, the bootconfig file is loaded with the initrd
1525 image. But if the system doesn't support initrd, this option will
1526 help you by embedding a bootconfig file while building the kernel.
1527
1528 If unsure, say N.
1529
1530config BOOT_CONFIG_EMBED_FILE
1531 string "Embedded bootconfig file path"
1532 depends on BOOT_CONFIG_EMBED
1533 help
1534 Specify a bootconfig file which will be embedded to the kernel.
1535 This bootconfig will be used if there is no initrd or no other
1536 bootconfig in the initrd.
1537
1538config CMDLINE_LOG_WRAP_IDEAL_LEN
1539 int "Length to try to wrap the cmdline when logged at boot"
1540 default 1021
1541 range 0 1021
1542 help
1543 At boot time, the kernel command line is logged to the console.
1544 The log message will start with the prefix "Kernel command line: ".
1545 The log message will attempt to be wrapped (split into multiple log
1546 messages) at spaces based on CMDLINE_LOG_WRAP_IDEAL_LEN characters.
1547 If wrapping happens, each log message will start with the prefix and
1548 all but the last message will end with " \". Messages may exceed the
1549 ideal length if a place to wrap isn't found before the specified
1550 number of characters.
1551
1552 A value of 0 disables wrapping, though be warned that the maximum
1553 length of a log message (1021 characters) may cause the cmdline to
1554 be truncated.
1555
1556config INITRAMFS_PRESERVE_MTIME
1557 bool "Preserve cpio archive mtimes in initramfs"
1558 depends on BLK_DEV_INITRD
1559 default y
1560 help
1561 Each entry in an initramfs cpio archive carries an mtime value. When
1562 enabled, extracted cpio items take this mtime, with directory mtime
1563 setting deferred until after creation of any child entries.
1564
1565 If unsure, say Y.
1566
1567config INITRAMFS_TEST
1568 bool "Test initramfs cpio archive extraction" if !KUNIT_ALL_TESTS
1569 depends on BLK_DEV_INITRD && KUNIT=y
1570 default KUNIT_ALL_TESTS
1571 help
1572 Build KUnit tests for initramfs. See Documentation/dev-tools/kunit
1573
1574choice
1575 prompt "Compiler optimization level"
1576 default CC_OPTIMIZE_FOR_PERFORMANCE
1577
1578config CC_OPTIMIZE_FOR_PERFORMANCE
1579 bool "Optimize for performance (-O2)"
1580 help
1581 This is the default optimization level for the kernel, building
1582 with the "-O2" compiler flag for best performance and most
1583 helpful compile-time warnings.
1584
1585config CC_OPTIMIZE_FOR_SIZE
1586 bool "Optimize for size (-Os)"
1587 help
1588 Choosing this option will pass "-Os" to your compiler resulting
1589 in a smaller kernel.
1590
1591endchoice
1592
1593config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1594 bool
1595 help
1596 This requires that the arch annotates or otherwise protects
1597 its external entry points from being discarded. Linker scripts
1598 must also merge .text.*, .data.*, and .bss.* correctly into
1599 output sections. Care must be taken not to pull in unrelated
1600 sections (e.g., '.text.init'). Typically '.' in section names
1601 is used to distinguish them from label names / C identifiers.
1602
1603config LD_DEAD_CODE_DATA_ELIMINATION
1604 bool "Dead code and data elimination (EXPERIMENTAL)"
1605 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1606 depends on EXPERT
1607 depends on $(cc-option,-ffunction-sections -fdata-sections)
1608 depends on $(ld-option,--gc-sections)
1609 help
1610 Enable this if you want to do dead code and data elimination with
1611 the linker by compiling with -ffunction-sections -fdata-sections,
1612 and linking with --gc-sections.
1613
1614 This can reduce on disk and in-memory size of the kernel
1615 code and static data, particularly for small configs and
1616 on small systems. This has the possibility of introducing
1617 silently broken kernel if the required annotations are not
1618 present. This option is not well tested yet, so use at your
1619 own risk.
1620
1621config LD_ORPHAN_WARN
1622 def_bool y
1623 depends on ARCH_WANT_LD_ORPHAN_WARN
1624 depends on $(ld-option,--orphan-handling=warn)
1625 depends on $(ld-option,--orphan-handling=error)
1626
1627config LD_ORPHAN_WARN_LEVEL
1628 string
1629 depends on LD_ORPHAN_WARN
1630 default "error" if WERROR
1631 default "warn"
1632
1633config SYSCTL
1634 bool
1635
1636config HAVE_UID16
1637 bool
1638
1639config SYSCTL_EXCEPTION_TRACE
1640 bool
1641 help
1642 Enable support for /proc/sys/debug/exception-trace.
1643
1644config SYSCTL_ARCH_UNALIGN_NO_WARN
1645 bool
1646 help
1647 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1648 Allows arch to define/use @no_unaligned_warning to possibly warn
1649 about unaligned access emulation going on under the hood.
1650
1651config SYSCTL_ARCH_UNALIGN_ALLOW
1652 bool
1653 help
1654 Enable support for /proc/sys/kernel/unaligned-trap
1655 Allows arches to define/use @unaligned_enabled to runtime toggle
1656 the unaligned access emulation.
1657 see arch/parisc/kernel/unaligned.c for reference
1658
1659config SYSFS_SYSCALL
1660 bool "Sysfs syscall support"
1661 default n
1662 help
1663 sys_sysfs is an obsolete system call no longer supported in libc.
1664 Note that disabling this option is more secure but might break
1665 compatibility with some systems.
1666
1667 If unsure say N here.
1668
1669config HAVE_PCSPKR_PLATFORM
1670 bool
1671
1672menuconfig EXPERT
1673 bool "Configure standard kernel features (expert users)"
1674 # Unhide debug options, to make the on-by-default options visible
1675 select DEBUG_KERNEL
1676 help
1677 This option allows certain base kernel options and settings
1678 to be disabled or tweaked. This is for specialized
1679 environments which can tolerate a "non-standard" kernel.
1680 Only use this if you really know what you are doing.
1681
1682config UID16
1683 bool "Enable 16-bit UID system calls" if EXPERT
1684 depends on HAVE_UID16 && MULTIUSER
1685 default y
1686 help
1687 This enables the legacy 16-bit UID syscall wrappers.
1688
1689config MULTIUSER
1690 bool "Multiple users, groups and capabilities support" if EXPERT
1691 default y
1692 help
1693 This option enables support for non-root users, groups and
1694 capabilities.
1695
1696 If you say N here, all processes will run with UID 0, GID 0, and all
1697 possible capabilities. Saying N here also compiles out support for
1698 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1699 setgid, and capset.
1700
1701 If unsure, say Y here.
1702
1703config SGETMASK_SYSCALL
1704 bool "sgetmask/ssetmask syscalls support" if EXPERT
1705 default PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1706 help
1707 sys_sgetmask and sys_ssetmask are obsolete system calls
1708 no longer supported in libc but still enabled by default in some
1709 architectures.
1710
1711 If unsure, leave the default option here.
1712
1713config FHANDLE
1714 bool "open by fhandle syscalls" if EXPERT
1715 select EXPORTFS
1716 default y
1717 help
1718 If you say Y here, a user level program will be able to map
1719 file names to handle and then later use the handle for
1720 different file system operations. This is useful in implementing
1721 userspace file servers, which now track files using handles instead
1722 of names. The handle would remain the same even if file names
1723 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1724 syscalls.
1725
1726config POSIX_TIMERS
1727 bool "Posix Clocks & timers" if EXPERT
1728 default y
1729 help
1730 This includes native support for POSIX timers to the kernel.
1731 Some embedded systems have no use for them and therefore they
1732 can be configured out to reduce the size of the kernel image.
1733
1734 When this option is disabled, the following syscalls won't be
1735 available: timer_create, timer_gettime: timer_getoverrun,
1736 timer_settime, timer_delete, clock_adjtime, getitimer,
1737 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1738 clock_getres and clock_nanosleep syscalls will be limited to
1739 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1740
1741 If unsure say y.
1742
1743config PRINTK
1744 default y
1745 bool "Enable support for printk" if EXPERT
1746 select IRQ_WORK
1747 help
1748 This option enables normal printk support. Removing it
1749 eliminates most of the message strings from the kernel image
1750 and makes the kernel more or less silent. As this makes it
1751 very difficult to diagnose system problems, saying N here is
1752 strongly discouraged.
1753
1754config PRINTK_RINGBUFFER_KUNIT_TEST
1755 tristate "KUnit Test for the printk ringbuffer" if !KUNIT_ALL_TESTS
1756 depends on PRINTK && KUNIT
1757 default KUNIT_ALL_TESTS
1758 help
1759 This builds the printk ringbuffer KUnit test suite.
1760
1761 For more information on KUnit and unit tests in general, please refer
1762 to the KUnit documentation.
1763
1764 If unsure, say N.
1765
1766config BUG
1767 bool "BUG() support" if EXPERT
1768 default y
1769 help
1770 Disabling this option eliminates support for BUG and WARN, reducing
1771 the size of your kernel image and potentially quietly ignoring
1772 numerous fatal conditions. You should only consider disabling this
1773 option for embedded systems with no facilities for reporting errors.
1774 Just say Y.
1775
1776config ELF_CORE
1777 depends on COREDUMP
1778 default y
1779 bool "Enable ELF core dumps" if EXPERT
1780 help
1781 Enable support for generating core dumps. Disabling saves about 4k.
1782
1783
1784config PCSPKR_PLATFORM
1785 bool "Enable PC-Speaker support" if EXPERT
1786 depends on HAVE_PCSPKR_PLATFORM
1787 select I8253_LOCK
1788 default y
1789 help
1790 This option allows to disable the internal PC-Speaker
1791 support, saving some memory.
1792
1793config BASE_SMALL
1794 bool "Enable smaller-sized data structures for core" if EXPERT
1795 help
1796 Enabling this option reduces the size of miscellaneous core
1797 kernel data structures. This saves memory on small machines,
1798 but may reduce performance.
1799
1800config FUTEX
1801 bool "Enable futex support" if EXPERT
1802 depends on !(SPARC32 && SMP)
1803 default y
1804 imply RT_MUTEXES
1805 help
1806 Disabling this option will cause the kernel to be built without
1807 support for "fast userspace mutexes". The resulting kernel may not
1808 run glibc-based applications correctly.
1809
1810config FUTEX_PI
1811 bool
1812 depends on FUTEX && RT_MUTEXES
1813 default y
1814
1815config FUTEX_PRIVATE_HASH
1816 bool
1817 depends on FUTEX && !BASE_SMALL && MMU
1818 default y
1819
1820config FUTEX_MPOL
1821 bool
1822 depends on FUTEX && NUMA
1823 default y
1824
1825config EPOLL
1826 bool "Enable eventpoll support" if EXPERT
1827 default y
1828 help
1829 Disabling this option will cause the kernel to be built without
1830 support for epoll family of system calls.
1831
1832config SIGNALFD
1833 bool "Enable signalfd() system call" if EXPERT
1834 default y
1835 help
1836 Enable the signalfd() system call that allows to receive signals
1837 on a file descriptor.
1838
1839 If unsure, say Y.
1840
1841config TIMERFD
1842 bool "Enable timerfd() system call" if EXPERT
1843 default y
1844 help
1845 Enable the timerfd() system call that allows to receive timer
1846 events on a file descriptor.
1847
1848 If unsure, say Y.
1849
1850config EVENTFD
1851 bool "Enable eventfd() system call" if EXPERT
1852 default y
1853 help
1854 Enable the eventfd() system call that allows to receive both
1855 kernel notification (ie. KAIO) or userspace notifications.
1856
1857 If unsure, say Y.
1858
1859config SHMEM
1860 bool "Use full shmem filesystem" if EXPERT
1861 default y
1862 depends on MMU
1863 help
1864 The shmem is an internal filesystem used to manage shared memory.
1865 It is backed by swap and manages resource limits. It is also exported
1866 to userspace as tmpfs if TMPFS is enabled. Disabling this
1867 option replaces shmem and tmpfs with the much simpler ramfs code,
1868 which may be appropriate on small systems without swap.
1869
1870config AIO
1871 bool "Enable AIO support" if EXPERT
1872 default y
1873 help
1874 This option enables POSIX asynchronous I/O which may by used
1875 by some high performance threaded applications. Disabling
1876 this option saves about 7k.
1877
1878config IO_URING
1879 bool "Enable IO uring support" if EXPERT
1880 select IO_WQ
1881 default y
1882 help
1883 This option enables support for the io_uring interface, enabling
1884 applications to submit and complete IO through submission and
1885 completion rings that are shared between the kernel and application.
1886
1887config GCOV_PROFILE_URING
1888 bool "Enable GCOV profiling on the io_uring subsystem"
1889 depends on IO_URING && GCOV_KERNEL
1890 help
1891 Enable GCOV profiling on the io_uring subsystem, to facilitate
1892 code coverage testing.
1893
1894 If unsure, say N.
1895
1896 Note that this will have a negative impact on the performance of
1897 the io_uring subsystem, hence this should only be enabled for
1898 specific test purposes.
1899
1900config IO_URING_MOCK_FILE
1901 tristate "Enable io_uring mock files (Experimental)" if EXPERT
1902 default n
1903 depends on IO_URING
1904 help
1905 Enable mock files for io_uring subsystem testing. The ABI might
1906 still change, so it's still experimental and should only be enabled
1907 for specific test purposes.
1908
1909 If unsure, say N.
1910
1911config ADVISE_SYSCALLS
1912 bool "Enable madvise/fadvise syscalls" if EXPERT
1913 default y
1914 help
1915 This option enables the madvise and fadvise syscalls, used by
1916 applications to advise the kernel about their future memory or file
1917 usage, improving performance. If building an embedded system where no
1918 applications use these syscalls, you can disable this option to save
1919 space.
1920
1921config MEMBARRIER
1922 bool "Enable membarrier() system call" if EXPERT
1923 default y
1924 help
1925 Enable the membarrier() system call that allows issuing memory
1926 barriers across all running threads, which can be used to distribute
1927 the cost of user-space memory barriers asymmetrically by transforming
1928 pairs of memory barriers into pairs consisting of membarrier() and a
1929 compiler barrier.
1930
1931 If unsure, say Y.
1932
1933config KCMP
1934 bool "Enable kcmp() system call" if EXPERT
1935 help
1936 Enable the kernel resource comparison system call. It provides
1937 user-space with the ability to compare two processes to see if they
1938 share a common resource, such as a file descriptor or even virtual
1939 memory space.
1940
1941 If unsure, say N.
1942
1943config RSEQ
1944 bool "Enable rseq() system call" if EXPERT
1945 default y
1946 depends on HAVE_RSEQ
1947 select MEMBARRIER
1948 help
1949 Enable the restartable sequences system call. It provides a
1950 user-space cache for the current CPU number value, which
1951 speeds up getting the current CPU number from user-space,
1952 as well as an ABI to speed up user-space operations on
1953 per-CPU data.
1954
1955 If unsure, say Y.
1956
1957config RSEQ_SLICE_EXTENSION
1958 bool "Enable rseq-based time slice extension mechanism"
1959 depends on RSEQ && HIGH_RES_TIMERS && GENERIC_ENTRY && HAVE_GENERIC_TIF_BITS
1960 help
1961 Allows userspace to request a limited time slice extension when
1962 returning from an interrupt to user space via the RSEQ shared
1963 data ABI. If granted, that allows to complete a critical section,
1964 so that other threads are not stuck on a conflicted resource,
1965 while the task is scheduled out.
1966
1967 If unsure, say N.
1968
1969config RSEQ_STATS
1970 default n
1971 bool "Enable lightweight statistics of restartable sequences" if EXPERT
1972 depends on RSEQ && DEBUG_FS
1973 help
1974 Enable lightweight counters which expose information about the
1975 frequency of RSEQ operations via debugfs. Mostly interesting for
1976 kernel debugging or performance analysis. While lightweight it's
1977 still adding code into the user/kernel mode transitions.
1978
1979 If unsure, say N.
1980
1981config RSEQ_DEBUG_DEFAULT_ENABLE
1982 default n
1983 bool "Enable restartable sequences debug mode by default" if EXPERT
1984 depends on RSEQ
1985 help
1986 This enables the static branch for debug mode of restartable
1987 sequences.
1988
1989 This also can be controlled on the kernel command line via the
1990 command line parameter "rseq_debug=0/1" and through debugfs.
1991
1992 If unsure, say N.
1993
1994config DEBUG_RSEQ
1995 default n
1996 bool "Enable debugging of rseq() system call" if EXPERT
1997 depends on RSEQ && DEBUG_KERNEL && !GENERIC_ENTRY
1998 select RSEQ_DEBUG_DEFAULT_ENABLE
1999 help
2000 Enable extra debugging checks for the rseq system call.
2001
2002 If unsure, say N.
2003
2004config CACHESTAT_SYSCALL
2005 bool "Enable cachestat() system call" if EXPERT
2006 default y
2007 help
2008 Enable the cachestat system call, which queries the page cache
2009 statistics of a file (number of cached pages, dirty pages,
2010 pages marked for writeback, (recently) evicted pages).
2011
2012 If unsure say Y here.
2013
2014config KALLSYMS
2015 bool "Load all symbols for debugging/ksymoops" if EXPERT
2016 default y
2017 help
2018 Say Y here to let the kernel print out symbolic crash information and
2019 symbolic stack backtraces. This increases the size of the kernel
2020 somewhat, as all symbols have to be loaded into the kernel image.
2021
2022config KALLSYMS_SELFTEST
2023 bool "Test the basic functions and performance of kallsyms"
2024 depends on KALLSYMS
2025 default n
2026 help
2027 Test the basic functions and performance of some interfaces, such as
2028 kallsyms_lookup_name. It also calculates the compression rate of the
2029 kallsyms compression algorithm for the current symbol set.
2030
2031 Start self-test automatically after system startup. Suggest executing
2032 "dmesg | grep kallsyms_selftest" to collect test results. "finish" is
2033 displayed in the last line, indicating that the test is complete.
2034
2035config KALLSYMS_ALL
2036 bool "Include all symbols in kallsyms"
2037 depends on DEBUG_KERNEL && KALLSYMS
2038 help
2039 Normally kallsyms only contains the symbols of functions for nicer
2040 OOPS messages and backtraces (i.e., symbols from the text and inittext
2041 sections). This is sufficient for most cases. And only if you want to
2042 enable kernel live patching, or other less common use cases (e.g.,
2043 when a debugger is used) all symbols are required (i.e., names of
2044 variables from the data sections, etc).
2045
2046 This option makes sure that all symbols are loaded into the kernel
2047 image (i.e., symbols from all sections) in cost of increased kernel
2048 size (depending on the kernel configuration, it may be 300KiB or
2049 something like this).
2050
2051 Say N unless you really need all symbols, or kernel live patching.
2052
2053# end of the "standard kernel features (expert users)" menu
2054
2055config ARCH_HAS_MEMBARRIER_CALLBACKS
2056 bool
2057
2058config ARCH_HAS_MEMBARRIER_SYNC_CORE
2059 bool
2060
2061config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS
2062 bool
2063 help
2064 Control MSEAL_SYSTEM_MAPPINGS access based on architecture.
2065
2066 A 64-bit kernel is required for the memory sealing feature.
2067 No specific hardware features from the CPU are needed.
2068
2069 To enable this feature, the architecture needs to update their
2070 special mappings calls to include the sealing flag and confirm
2071 that it doesn't unmap/remap system mappings during the life
2072 time of the process. The existence of this flag for an architecture
2073 implies that it does not require the remapping of the system
2074 mappings during process lifetime, so sealing these mappings is safe
2075 from a kernel perspective.
2076
2077 After the architecture enables this, a distribution can set
2078 CONFIG_MSEAL_SYSTEM_MAPPING to manage access to the feature.
2079
2080 For complete descriptions of memory sealing, please see
2081 Documentation/userspace-api/mseal.rst
2082
2083config HAVE_PERF_EVENTS
2084 bool
2085 help
2086 See tools/perf/design.txt for details.
2087
2088config GUEST_PERF_EVENTS
2089 bool
2090 depends on HAVE_PERF_EVENTS
2091
2092config PERF_GUEST_MEDIATED_PMU
2093 bool
2094 depends on GUEST_PERF_EVENTS
2095
2096config PERF_USE_VMALLOC
2097 bool
2098 help
2099 See tools/perf/design.txt for details
2100
2101menu "Kernel Performance Events And Counters"
2102
2103config PERF_EVENTS
2104 bool "Kernel performance events and counters"
2105 default y if PROFILING
2106 depends on HAVE_PERF_EVENTS
2107 select IRQ_WORK
2108 help
2109 Enable kernel support for various performance events provided
2110 by software and hardware.
2111
2112 Software events are supported either built-in or via the
2113 use of generic tracepoints.
2114
2115 Most modern CPUs support performance events via performance
2116 counter registers. These registers count the number of certain
2117 types of hw events: such as instructions executed, cachemisses
2118 suffered, or branches mis-predicted - without slowing down the
2119 kernel or applications. These registers can also trigger interrupts
2120 when a threshold number of events have passed - and can thus be
2121 used to profile the code that runs on that CPU.
2122
2123 The Linux Performance Event subsystem provides an abstraction of
2124 these software and hardware event capabilities, available via a
2125 system call and used by the "perf" utility in tools/perf/. It
2126 provides per task and per CPU counters, and it provides event
2127 capabilities on top of those.
2128
2129 Say Y if unsure.
2130
2131config DEBUG_PERF_USE_VMALLOC
2132 default n
2133 bool "Debug: use vmalloc to back perf mmap() buffers"
2134 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
2135 select PERF_USE_VMALLOC
2136 help
2137 Use vmalloc memory to back perf mmap() buffers.
2138
2139 Mostly useful for debugging the vmalloc code on platforms
2140 that don't require it.
2141
2142 Say N if unsure.
2143
2144endmenu
2145
2146config SYSTEM_DATA_VERIFICATION
2147 def_bool n
2148 select SYSTEM_TRUSTED_KEYRING
2149 select KEYS
2150 select CRYPTO
2151 select CRYPTO_RSA
2152 select ASYMMETRIC_KEY_TYPE
2153 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
2154 select ASN1
2155 select OID_REGISTRY
2156 select X509_CERTIFICATE_PARSER
2157 select PKCS7_MESSAGE_PARSER
2158 help
2159 Provide PKCS#7 message verification using the contents of the system
2160 trusted keyring to provide public keys. This then can be used for
2161 module verification, kexec image verification and firmware blob
2162 verification.
2163
2164config PROFILING
2165 bool "Profiling support"
2166 help
2167 Say Y here to enable the extended profiling support mechanisms used
2168 by profilers.
2169
2170config RUST
2171 bool "Rust support"
2172 depends on HAVE_RUST
2173 depends on RUST_IS_AVAILABLE
2174 select EXTENDED_MODVERSIONS if MODVERSIONS
2175 depends on !MODVERSIONS || GENDWARFKSYMS
2176 depends on !GCC_PLUGIN_RANDSTRUCT
2177 depends on !RANDSTRUCT
2178 depends on !DEBUG_INFO_BTF || (PAHOLE_HAS_LANG_EXCLUDE && !LTO)
2179 depends on !CFI || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC
2180 select CFI_ICALL_NORMALIZE_INTEGERS if CFI
2181 depends on !CALL_PADDING || RUSTC_VERSION >= 108100
2182 depends on !KASAN_SW_TAGS
2183 depends on !(MITIGATION_RETHUNK && KASAN) || RUSTC_VERSION >= 108300
2184 help
2185 Enables Rust support in the kernel.
2186
2187 This allows other Rust-related options, like drivers written in Rust,
2188 to be selected.
2189
2190 It is also required to be able to load external kernel modules
2191 written in Rust.
2192
2193 See Documentation/rust/ for more information.
2194
2195 If unsure, say N.
2196
2197config RUSTC_VERSION_TEXT
2198 string
2199 depends on RUST
2200 default "$(RUSTC_VERSION_TEXT)"
2201 help
2202 See `CC_VERSION_TEXT`.
2203
2204config BINDGEN_VERSION_TEXT
2205 string
2206 depends on RUST
2207 # The dummy parameter `workaround-for-0.69.0` is required to support 0.69.0
2208 # (https://github.com/rust-lang/rust-bindgen/pull/2678) and 0.71.0
2209 # (https://github.com/rust-lang/rust-bindgen/pull/3040). It can be removed
2210 # when the minimum version is upgraded past the latter (0.69.1 and 0.71.1
2211 # both fixed the issue).
2212 default "$(shell,$(BINDGEN) --version workaround-for-0.69.0 2>/dev/null)"
2213
2214#
2215# Place an empty function call at each tracepoint site. Can be
2216# dynamically changed for a probe function.
2217#
2218config TRACEPOINTS
2219 bool
2220 select TASKS_TRACE_RCU
2221
2222source "kernel/Kconfig.kexec"
2223
2224source "kernel/liveupdate/Kconfig"
2225
2226endmenu # General setup
2227
2228source "arch/Kconfig"
2229
2230config RT_MUTEXES
2231 bool
2232 default y if PREEMPT_RT
2233
2234config MODULE_SIG_FORMAT
2235 def_bool n
2236 select SYSTEM_DATA_VERIFICATION
2237
2238source "kernel/module/Kconfig"
2239
2240config INIT_ALL_POSSIBLE
2241 bool
2242 help
2243 Back when each arch used to define their own cpu_online_mask and
2244 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2245 with all 1s, and others with all 0s. When they were centralised,
2246 it was better to provide this option than to break all the archs
2247 and have several arch maintainers pursuing me down dark alleys.
2248
2249source "block/Kconfig"
2250
2251config PREEMPT_NOTIFIERS
2252 bool
2253
2254config PADATA
2255 depends on SMP
2256 bool
2257
2258config ASN1
2259 tristate
2260 help
2261 Build a simple ASN.1 grammar compiler that produces a bytecode output
2262 that can be interpreted by the ASN.1 stream decoder and used to
2263 inform it as to what tags are to be expected in a stream and what
2264 functions to call on what tags.
2265
2266source "kernel/Kconfig.locks"
2267
2268config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
2269 bool
2270
2271config ARCH_HAS_PREPARE_SYNC_CORE_CMD
2272 bool
2273
2274config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2275 bool
2276
2277# It may be useful for an architecture to override the definitions of the
2278# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2279# and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2280# different calling convention for syscalls. They can also override the
2281# macros for not-implemented syscalls in kernel/sys_ni.c and
2282# kernel/time/posix-stubs.c. All these overrides need to be available in
2283# <asm/syscall_wrapper.h>.
2284config ARCH_HAS_SYSCALL_WRAPPER
2285 def_bool n