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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
90config CC_CAN_LINK_STATIC
91 bool
92 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag) -static) if 64BIT
93 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag) -static)
94
95# Fixed in GCC 14, 13.3, 12.4 and 11.5
96# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921
97config GCC_ASM_GOTO_OUTPUT_BROKEN
98 bool
99 depends on CC_IS_GCC
100 default y if GCC_VERSION < 110500
101 default y if GCC_VERSION >= 120000 && GCC_VERSION < 120400
102 default y if GCC_VERSION >= 130000 && GCC_VERSION < 130300
103
104config CC_HAS_ASM_GOTO_OUTPUT
105 def_bool y
106 depends on !GCC_ASM_GOTO_OUTPUT_BROKEN
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
109config CC_HAS_ASM_GOTO_TIED_OUTPUT
110 depends on CC_HAS_ASM_GOTO_OUTPUT
111 # Detect buggy gcc and clang, fixed in gcc-11 clang-14.
112 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)
113
114config TOOLS_SUPPORT_RELR
115 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
116
117config CC_HAS_ASM_INLINE
118 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
119
120config CC_HAS_NO_PROFILE_FN_ATTR
121 def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
122
123config CC_HAS_COUNTED_BY
124 # TODO: when gcc 15 is released remove the build test and add
125 # a gcc version check
126 def_bool $(success,echo 'struct flex { int count; int array[] __attribute__((__counted_by__(count))); };' | $(CC) $(CLANG_FLAGS) -x c - -c -o /dev/null -Werror)
127 # clang needs to be at least 19.1.3 to avoid __bdos miscalculations
128 # https://github.com/llvm/llvm-project/pull/110497
129 # https://github.com/llvm/llvm-project/pull/112636
130 depends on !(CC_IS_CLANG && CLANG_VERSION < 190103)
131
132config PAHOLE_VERSION
133 int
134 default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE))
135
136config CONSTRUCTORS
137 bool
138
139config IRQ_WORK
140 def_bool y if SMP
141
142config BUILDTIME_TABLE_SORT
143 bool
144
145config THREAD_INFO_IN_TASK
146 bool
147 help
148 Select this to move thread_info off the stack into task_struct. To
149 make this work, an arch will need to remove all thread_info fields
150 except flags and fix any runtime bugs.
151
152 One subtle change that will be needed is to use try_get_task_stack()
153 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
154
155menu "General setup"
156
157config BROKEN
158 bool
159
160config BROKEN_ON_SMP
161 bool
162 depends on BROKEN || !SMP
163 default y
164
165config INIT_ENV_ARG_LIMIT
166 int
167 default 32 if !UML
168 default 128 if UML
169 help
170 Maximum of each of the number of arguments and environment
171 variables passed to init from the kernel command line.
172
173config COMPILE_TEST
174 bool "Compile also drivers which will not load"
175 depends on HAS_IOMEM
176 help
177 Some drivers can be compiled on a different platform than they are
178 intended to be run on. Despite they cannot be loaded there (or even
179 when they load they cannot be used due to missing HW support),
180 developers still, opposing to distributors, might want to build such
181 drivers to compile-test them.
182
183 If you are a developer and want to build everything available, say Y
184 here. If you are a user/distributor, say N here to exclude useless
185 drivers to be distributed.
186
187config WERROR
188 bool "Compile the kernel with warnings as errors"
189 default COMPILE_TEST
190 help
191 A kernel build should not cause any compiler warnings, and this
192 enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags
193 to enforce that rule by default. Certain warnings from other tools
194 such as the linker may be upgraded to errors with this option as
195 well.
196
197 However, if you have a new (or very old) compiler or linker with odd
198 and unusual warnings, or you have some architecture with problems,
199 you may need to disable this config option in order to
200 successfully build the kernel.
201
202 If in doubt, say Y.
203
204config UAPI_HEADER_TEST
205 bool "Compile test UAPI headers"
206 depends on HEADERS_INSTALL && CC_CAN_LINK
207 help
208 Compile test headers exported to user-space to ensure they are
209 self-contained, i.e. compilable as standalone units.
210
211 If you are a developer or tester and want to ensure the exported
212 headers are self-contained, say Y here. Otherwise, choose N.
213
214config LOCALVERSION
215 string "Local version - append to kernel release"
216 help
217 Append an extra string to the end of your kernel version.
218 This will show up when you type uname, for example.
219 The string you set here will be appended after the contents of
220 any files with a filename matching localversion* in your
221 object and source tree, in that order. Your total string can
222 be a maximum of 64 characters.
223
224config LOCALVERSION_AUTO
225 bool "Automatically append version information to the version string"
226 default y
227 depends on !COMPILE_TEST
228 help
229 This will try to automatically determine if the current tree is a
230 release tree by looking for git tags that belong to the current
231 top of tree revision.
232
233 A string of the format -gxxxxxxxx will be added to the localversion
234 if a git-based tree is found. The string generated by this will be
235 appended after any matching localversion* files, and after the value
236 set in CONFIG_LOCALVERSION.
237
238 (The actual string used here is the first 12 characters produced
239 by running the command:
240
241 $ git rev-parse --verify HEAD
242
243 which is done within the script "scripts/setlocalversion".)
244
245config BUILD_SALT
246 string "Build ID Salt"
247 default ""
248 help
249 The build ID is used to link binaries and their debug info. Setting
250 this option will use the value in the calculation of the build id.
251 This is mostly useful for distributions which want to ensure the
252 build is unique between builds. It's safe to leave the default.
253
254config HAVE_KERNEL_GZIP
255 bool
256
257config HAVE_KERNEL_BZIP2
258 bool
259
260config HAVE_KERNEL_LZMA
261 bool
262
263config HAVE_KERNEL_XZ
264 bool
265
266config HAVE_KERNEL_LZO
267 bool
268
269config HAVE_KERNEL_LZ4
270 bool
271
272config HAVE_KERNEL_ZSTD
273 bool
274
275config HAVE_KERNEL_UNCOMPRESSED
276 bool
277
278choice
279 prompt "Kernel compression mode"
280 default KERNEL_GZIP
281 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
282 help
283 The linux kernel is a kind of self-extracting executable.
284 Several compression algorithms are available, which differ
285 in efficiency, compression and decompression speed.
286 Compression speed is only relevant when building a kernel.
287 Decompression speed is relevant at each boot.
288
289 If you have any problems with bzip2 or lzma compressed
290 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
291 version of this functionality (bzip2 only), for 2.4, was
292 supplied by Christian Ludwig)
293
294 High compression options are mostly useful for users, who
295 are low on disk space (embedded systems), but for whom ram
296 size matters less.
297
298 If in doubt, select 'gzip'
299
300config KERNEL_GZIP
301 bool "Gzip"
302 depends on HAVE_KERNEL_GZIP
303 help
304 The old and tried gzip compression. It provides a good balance
305 between compression ratio and decompression speed.
306
307config KERNEL_BZIP2
308 bool "Bzip2"
309 depends on HAVE_KERNEL_BZIP2
310 help
311 Its compression ratio and speed is intermediate.
312 Decompression speed is slowest among the choices. The kernel
313 size is about 10% smaller with bzip2, in comparison to gzip.
314 Bzip2 uses a large amount of memory. For modern kernels you
315 will need at least 8MB RAM or more for booting.
316
317config KERNEL_LZMA
318 bool "LZMA"
319 depends on HAVE_KERNEL_LZMA
320 help
321 This compression algorithm's ratio is best. Decompression speed
322 is between gzip and bzip2. Compression is slowest.
323 The kernel size is about 33% smaller with LZMA in comparison to gzip.
324
325config KERNEL_XZ
326 bool "XZ"
327 depends on HAVE_KERNEL_XZ
328 help
329 XZ uses the LZMA2 algorithm and instruction set specific
330 BCJ filters which can improve compression ratio of executable
331 code. The size of the kernel is about 30% smaller with XZ in
332 comparison to gzip. On architectures for which there is a BCJ
333 filter (i386, x86_64, ARM, ARM64, RISC-V, big endian PowerPC,
334 and SPARC), XZ will create a few percent smaller kernel than
335 plain LZMA.
336
337 The speed is about the same as with LZMA: The decompression
338 speed of XZ is better than that of bzip2 but worse than gzip
339 and LZO. Compression is slow.
340
341config KERNEL_LZO
342 bool "LZO"
343 depends on HAVE_KERNEL_LZO
344 help
345 Its compression ratio is the poorest among the choices. The kernel
346 size is about 10% bigger than gzip; however its speed
347 (both compression and decompression) is the fastest.
348
349config KERNEL_LZ4
350 bool "LZ4"
351 depends on HAVE_KERNEL_LZ4
352 help
353 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
354 A preliminary version of LZ4 de/compression tool is available at
355 <https://code.google.com/p/lz4/>.
356
357 Its compression ratio is worse than LZO. The size of the kernel
358 is about 8% bigger than LZO. But the decompression speed is
359 faster than LZO.
360
361config KERNEL_ZSTD
362 bool "ZSTD"
363 depends on HAVE_KERNEL_ZSTD
364 help
365 ZSTD is a compression algorithm targeting intermediate compression
366 with fast decompression speed. It will compress better than GZIP and
367 decompress around the same speed as LZO, but slower than LZ4. You
368 will need at least 192 KB RAM or more for booting. The zstd command
369 line tool is required for compression.
370
371config KERNEL_UNCOMPRESSED
372 bool "None"
373 depends on HAVE_KERNEL_UNCOMPRESSED
374 help
375 Produce uncompressed kernel image. This option is usually not what
376 you want. It is useful for debugging the kernel in slow simulation
377 environments, where decompressing and moving the kernel is awfully
378 slow. This option allows early boot code to skip the decompressor
379 and jump right at uncompressed kernel image.
380
381endchoice
382
383config DEFAULT_INIT
384 string "Default init path"
385 default ""
386 help
387 This option determines the default init for the system if no init=
388 option is passed on the kernel command line. If the requested path is
389 not present, we will still then move on to attempting further
390 locations (e.g. /sbin/init, etc). If this is empty, we will just use
391 the fallback list when init= is not passed.
392
393config DEFAULT_HOSTNAME
394 string "Default hostname"
395 default "(none)"
396 help
397 This option determines the default system hostname before userspace
398 calls sethostname(2). The kernel traditionally uses "(none)" here,
399 but you may wish to use a different default here to make a minimal
400 system more usable with less configuration.
401
402config SYSVIPC
403 bool "System V IPC"
404 help
405 Inter Process Communication is a suite of library functions and
406 system calls which let processes (running programs) synchronize and
407 exchange information. It is generally considered to be a good thing,
408 and some programs won't run unless you say Y here. In particular, if
409 you want to run the DOS emulator dosemu under Linux (read the
410 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
411 you'll need to say Y here.
412
413 You can find documentation about IPC with "info ipc" and also in
414 section 6.4 of the Linux Programmer's Guide, available from
415 <http://www.tldp.org/guides.html>.
416
417config SYSVIPC_SYSCTL
418 bool
419 depends on SYSVIPC
420 depends on SYSCTL
421 default y
422
423config SYSVIPC_COMPAT
424 def_bool y
425 depends on COMPAT && SYSVIPC
426
427config POSIX_MQUEUE
428 bool "POSIX Message Queues"
429 depends on NET
430 help
431 POSIX variant of message queues is a part of IPC. In POSIX message
432 queues every message has a priority which decides about succession
433 of receiving it by a process. If you want to compile and run
434 programs written e.g. for Solaris with use of its POSIX message
435 queues (functions mq_*) say Y here.
436
437 POSIX message queues are visible as a filesystem called 'mqueue'
438 and can be mounted somewhere if you want to do filesystem
439 operations on message queues.
440
441 If unsure, say Y.
442
443config POSIX_MQUEUE_SYSCTL
444 bool
445 depends on POSIX_MQUEUE
446 depends on SYSCTL
447 default y
448
449config WATCH_QUEUE
450 bool "General notification queue"
451 default n
452 help
453
454 This is a general notification queue for the kernel to pass events to
455 userspace by splicing them into pipes. It can be used in conjunction
456 with watches for key/keyring change notifications and device
457 notifications.
458
459 See Documentation/core-api/watch_queue.rst
460
461config CROSS_MEMORY_ATTACH
462 bool "Enable process_vm_readv/writev syscalls"
463 depends on MMU
464 default y
465 help
466 Enabling this option adds the system calls process_vm_readv and
467 process_vm_writev which allow a process with the correct privileges
468 to directly read from or write to another process' address space.
469 See the man page for more details.
470
471config USELIB
472 bool "uselib syscall (for libc5 and earlier)"
473 default ALPHA || M68K || SPARC
474 help
475 This option enables the uselib syscall, a system call used in the
476 dynamic linker from libc5 and earlier. glibc does not use this
477 system call. If you intend to run programs built on libc5 or
478 earlier, you may need to enable this syscall. Current systems
479 running glibc can safely disable this.
480
481config AUDIT
482 bool "Auditing support"
483 depends on NET
484 help
485 Enable auditing infrastructure that can be used with another
486 kernel subsystem, such as SELinux (which requires this for
487 logging of avc messages output). System call auditing is included
488 on architectures which support it.
489
490config HAVE_ARCH_AUDITSYSCALL
491 bool
492
493config AUDITSYSCALL
494 def_bool y
495 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
496 select FSNOTIFY
497
498source "kernel/irq/Kconfig"
499source "kernel/time/Kconfig"
500source "kernel/bpf/Kconfig"
501source "kernel/Kconfig.preempt"
502
503menu "CPU/Task time and stats accounting"
504
505config VIRT_CPU_ACCOUNTING
506 bool
507
508choice
509 prompt "Cputime accounting"
510 default TICK_CPU_ACCOUNTING
511
512# Kind of a stub config for the pure tick based cputime accounting
513config TICK_CPU_ACCOUNTING
514 bool "Simple tick based cputime accounting"
515 depends on !S390 && !NO_HZ_FULL
516 help
517 This is the basic tick based cputime accounting that maintains
518 statistics about user, system and idle time spent on per jiffies
519 granularity.
520
521 If unsure, say Y.
522
523config VIRT_CPU_ACCOUNTING_NATIVE
524 bool "Deterministic task and CPU time accounting"
525 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
526 select VIRT_CPU_ACCOUNTING
527 help
528 Select this option to enable more accurate task and CPU time
529 accounting. This is done by reading a CPU counter on each
530 kernel entry and exit and on transitions within the kernel
531 between system, softirq and hardirq state, so there is a
532 small performance impact. In the case of s390 or IBM POWER > 5,
533 this also enables accounting of stolen time on logically-partitioned
534 systems.
535
536config VIRT_CPU_ACCOUNTING_GEN
537 bool "Full dynticks CPU time accounting"
538 depends on HAVE_CONTEXT_TRACKING_USER
539 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
540 depends on GENERIC_CLOCKEVENTS
541 select VIRT_CPU_ACCOUNTING
542 select CONTEXT_TRACKING_USER
543 help
544 Select this option to enable task and CPU time accounting on full
545 dynticks systems. This accounting is implemented by watching every
546 kernel-user boundaries using the context tracking subsystem.
547 The accounting is thus performed at the expense of some significant
548 overhead.
549
550 For now this is only useful if you are working on the full
551 dynticks subsystem development.
552
553 If unsure, say N.
554
555endchoice
556
557config IRQ_TIME_ACCOUNTING
558 bool "Fine granularity task level IRQ time accounting"
559 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
560 help
561 Select this option to enable fine granularity task irq time
562 accounting. This is done by reading a timestamp on each
563 transitions between softirq and hardirq state, so there can be a
564 small performance impact.
565
566 If in doubt, say N here.
567
568config HAVE_SCHED_AVG_IRQ
569 def_bool y
570 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
571 depends on SMP
572
573config SCHED_HW_PRESSURE
574 bool
575 default y if ARM && ARM_CPU_TOPOLOGY
576 default y if ARM64
577 depends on SMP
578 depends on CPU_FREQ_THERMAL
579 help
580 Select this option to enable HW pressure accounting in the
581 scheduler. HW pressure is the value conveyed to the scheduler
582 that reflects the reduction in CPU compute capacity resulted from
583 HW throttling. HW throttling occurs when the performance of
584 a CPU is capped due to high operating temperatures as an example.
585
586 If selected, the scheduler will be able to balance tasks accordingly,
587 i.e. put less load on throttled CPUs than on non/less throttled ones.
588
589 This requires the architecture to implement
590 arch_update_hw_pressure() and arch_scale_thermal_pressure().
591
592config BSD_PROCESS_ACCT
593 bool "BSD Process Accounting"
594 depends on MULTIUSER
595 help
596 If you say Y here, a user level program will be able to instruct the
597 kernel (via a special system call) to write process accounting
598 information to a file: whenever a process exits, information about
599 that process will be appended to the file by the kernel. The
600 information includes things such as creation time, owning user,
601 command name, memory usage, controlling terminal etc. (the complete
602 list is in the struct acct in <file:include/linux/acct.h>). It is
603 up to the user level program to do useful things with this
604 information. This is generally a good idea, so say Y.
605
606config BSD_PROCESS_ACCT_V3
607 bool "BSD Process Accounting version 3 file format"
608 depends on BSD_PROCESS_ACCT
609 default n
610 help
611 If you say Y here, the process accounting information is written
612 in a new file format that also logs the process IDs of each
613 process and its parent. Note that this file format is incompatible
614 with previous v0/v1/v2 file formats, so you will need updated tools
615 for processing it. A preliminary version of these tools is available
616 at <http://www.gnu.org/software/acct/>.
617
618config TASKSTATS
619 bool "Export task/process statistics through netlink"
620 depends on NET
621 depends on MULTIUSER
622 default n
623 help
624 Export selected statistics for tasks/processes through the
625 generic netlink interface. Unlike BSD process accounting, the
626 statistics are available during the lifetime of tasks/processes as
627 responses to commands. Like BSD accounting, they are sent to user
628 space on task exit.
629
630 Say N if unsure.
631
632config TASK_DELAY_ACCT
633 bool "Enable per-task delay accounting"
634 depends on TASKSTATS
635 select SCHED_INFO
636 help
637 Collect information on time spent by a task waiting for system
638 resources like cpu, synchronous block I/O completion and swapping
639 in pages. Such statistics can help in setting a task's priorities
640 relative to other tasks for cpu, io, rss limits etc.
641
642 Say N if unsure.
643
644config TASK_XACCT
645 bool "Enable extended accounting over taskstats"
646 depends on TASKSTATS
647 help
648 Collect extended task accounting data and send the data
649 to userland for processing over the taskstats interface.
650
651 Say N if unsure.
652
653config TASK_IO_ACCOUNTING
654 bool "Enable per-task storage I/O accounting"
655 depends on TASK_XACCT
656 help
657 Collect information on the number of bytes of storage I/O which this
658 task has caused.
659
660 Say N if unsure.
661
662config PSI
663 bool "Pressure stall information tracking"
664 select KERNFS
665 help
666 Collect metrics that indicate how overcommitted the CPU, memory,
667 and IO capacity are in the system.
668
669 If you say Y here, the kernel will create /proc/pressure/ with the
670 pressure statistics files cpu, memory, and io. These will indicate
671 the share of walltime in which some or all tasks in the system are
672 delayed due to contention of the respective resource.
673
674 In kernels with cgroup support, cgroups (cgroup2 only) will
675 have cpu.pressure, memory.pressure, and io.pressure files,
676 which aggregate pressure stalls for the grouped tasks only.
677
678 For more details see Documentation/accounting/psi.rst.
679
680 Say N if unsure.
681
682config PSI_DEFAULT_DISABLED
683 bool "Require boot parameter to enable pressure stall information tracking"
684 default n
685 depends on PSI
686 help
687 If set, pressure stall information tracking will be disabled
688 per default but can be enabled through passing psi=1 on the
689 kernel commandline during boot.
690
691 This feature adds some code to the task wakeup and sleep
692 paths of the scheduler. The overhead is too low to affect
693 common scheduling-intense workloads in practice (such as
694 webservers, memcache), but it does show up in artificial
695 scheduler stress tests, such as hackbench.
696
697 If you are paranoid and not sure what the kernel will be
698 used for, say Y.
699
700 Say N if unsure.
701
702endmenu # "CPU/Task time and stats accounting"
703
704config CPU_ISOLATION
705 bool "CPU isolation"
706 depends on SMP || COMPILE_TEST
707 default y
708 help
709 Make sure that CPUs running critical tasks are not disturbed by
710 any source of "noise" such as unbound workqueues, timers, kthreads...
711 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
712 the "isolcpus=" boot parameter.
713
714 Say Y if unsure.
715
716source "kernel/rcu/Kconfig"
717
718config IKCONFIG
719 tristate "Kernel .config support"
720 help
721 This option enables the complete Linux kernel ".config" file
722 contents to be saved in the kernel. It provides documentation
723 of which kernel options are used in a running kernel or in an
724 on-disk kernel. This information can be extracted from the kernel
725 image file with the script scripts/extract-ikconfig and used as
726 input to rebuild the current kernel or to build another kernel.
727 It can also be extracted from a running kernel by reading
728 /proc/config.gz if enabled (below).
729
730config IKCONFIG_PROC
731 bool "Enable access to .config through /proc/config.gz"
732 depends on IKCONFIG && PROC_FS
733 help
734 This option enables access to the kernel configuration file
735 through /proc/config.gz.
736
737config IKHEADERS
738 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
739 depends on SYSFS
740 help
741 This option enables access to the in-kernel headers that are generated during
742 the build process. These can be used to build eBPF tracing programs,
743 or similar programs. If you build the headers as a module, a module called
744 kheaders.ko is built which can be loaded on-demand to get access to headers.
745
746config LOG_BUF_SHIFT
747 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
748 range 12 25
749 default 17
750 depends on PRINTK
751 help
752 Select the minimal kernel log buffer size as a power of 2.
753 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
754 parameter, see below. Any higher size also might be forced
755 by "log_buf_len" boot parameter.
756
757 Examples:
758 17 => 128 KB
759 16 => 64 KB
760 15 => 32 KB
761 14 => 16 KB
762 13 => 8 KB
763 12 => 4 KB
764
765config LOG_CPU_MAX_BUF_SHIFT
766 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
767 depends on SMP
768 range 0 21
769 default 0 if BASE_SMALL
770 default 12
771 depends on PRINTK
772 help
773 This option allows to increase the default ring buffer size
774 according to the number of CPUs. The value defines the contribution
775 of each CPU as a power of 2. The used space is typically only few
776 lines however it might be much more when problems are reported,
777 e.g. backtraces.
778
779 The increased size means that a new buffer has to be allocated and
780 the original static one is unused. It makes sense only on systems
781 with more CPUs. Therefore this value is used only when the sum of
782 contributions is greater than the half of the default kernel ring
783 buffer as defined by LOG_BUF_SHIFT. The default values are set
784 so that more than 16 CPUs are needed to trigger the allocation.
785
786 Also this option is ignored when "log_buf_len" kernel parameter is
787 used as it forces an exact (power of two) size of the ring buffer.
788
789 The number of possible CPUs is used for this computation ignoring
790 hotplugging making the computation optimal for the worst case
791 scenario while allowing a simple algorithm to be used from bootup.
792
793 Examples shift values and their meaning:
794 17 => 128 KB for each CPU
795 16 => 64 KB for each CPU
796 15 => 32 KB for each CPU
797 14 => 16 KB for each CPU
798 13 => 8 KB for each CPU
799 12 => 4 KB for each CPU
800
801config PRINTK_INDEX
802 bool "Printk indexing debugfs interface"
803 depends on PRINTK && DEBUG_FS
804 help
805 Add support for indexing of all printk formats known at compile time
806 at <debugfs>/printk/index/<module>.
807
808 This can be used as part of maintaining daemons which monitor
809 /dev/kmsg, as it permits auditing the printk formats present in a
810 kernel, allowing detection of cases where monitored printks are
811 changed or no longer present.
812
813 There is no additional runtime cost to printk with this enabled.
814
815#
816# Architectures with an unreliable sched_clock() should select this:
817#
818config HAVE_UNSTABLE_SCHED_CLOCK
819 bool
820
821config GENERIC_SCHED_CLOCK
822 bool
823
824menu "Scheduler features"
825
826config UCLAMP_TASK
827 bool "Enable utilization clamping for RT/FAIR tasks"
828 depends on CPU_FREQ_GOV_SCHEDUTIL
829 help
830 This feature enables the scheduler to track the clamped utilization
831 of each CPU based on RUNNABLE tasks scheduled on that CPU.
832
833 With this option, the user can specify the min and max CPU
834 utilization allowed for RUNNABLE tasks. The max utilization defines
835 the maximum frequency a task should use while the min utilization
836 defines the minimum frequency it should use.
837
838 Both min and max utilization clamp values are hints to the scheduler,
839 aiming at improving its frequency selection policy, but they do not
840 enforce or grant any specific bandwidth for tasks.
841
842 If in doubt, say N.
843
844config UCLAMP_BUCKETS_COUNT
845 int "Number of supported utilization clamp buckets"
846 range 5 20
847 default 5
848 depends on UCLAMP_TASK
849 help
850 Defines the number of clamp buckets to use. The range of each bucket
851 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
852 number of clamp buckets the finer their granularity and the higher
853 the precision of clamping aggregation and tracking at run-time.
854
855 For example, with the minimum configuration value we will have 5
856 clamp buckets tracking 20% utilization each. A 25% boosted tasks will
857 be refcounted in the [20..39]% bucket and will set the bucket clamp
858 effective value to 25%.
859 If a second 30% boosted task should be co-scheduled on the same CPU,
860 that task will be refcounted in the same bucket of the first task and
861 it will boost the bucket clamp effective value to 30%.
862 The clamp effective value of a bucket is reset to its nominal value
863 (20% in the example above) when there are no more tasks refcounted in
864 that bucket.
865
866 An additional boost/capping margin can be added to some tasks. In the
867 example above the 25% task will be boosted to 30% until it exits the
868 CPU. If that should be considered not acceptable on certain systems,
869 it's always possible to reduce the margin by increasing the number of
870 clamp buckets to trade off used memory for run-time tracking
871 precision.
872
873 If in doubt, use the default value.
874
875endmenu
876
877#
878# For architectures that want to enable the support for NUMA-affine scheduler
879# balancing logic:
880#
881config ARCH_SUPPORTS_NUMA_BALANCING
882 bool
883
884#
885# For architectures that prefer to flush all TLBs after a number of pages
886# are unmapped instead of sending one IPI per page to flush. The architecture
887# must provide guarantees on what happens if a clean TLB cache entry is
888# written after the unmap. Details are in mm/rmap.c near the check for
889# should_defer_flush. The architecture should also consider if the full flush
890# and the refill costs are offset by the savings of sending fewer IPIs.
891config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
892 bool
893
894config CC_HAS_INT128
895 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
896
897config CC_IMPLICIT_FALLTHROUGH
898 string
899 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5)
900 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough)
901
902# Currently, disable gcc-10+ array-bounds globally.
903# It's still broken in gcc-13, so no upper bound yet.
904config GCC10_NO_ARRAY_BOUNDS
905 def_bool y
906
907config CC_NO_ARRAY_BOUNDS
908 bool
909 default y if CC_IS_GCC && GCC_VERSION >= 90000 && GCC10_NO_ARRAY_BOUNDS
910
911# Currently, disable -Wstringop-overflow for GCC globally.
912config GCC_NO_STRINGOP_OVERFLOW
913 def_bool y
914
915config CC_NO_STRINGOP_OVERFLOW
916 bool
917 default y if CC_IS_GCC && GCC_NO_STRINGOP_OVERFLOW
918
919config CC_STRINGOP_OVERFLOW
920 bool
921 default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW
922
923#
924# For architectures that know their GCC __int128 support is sound
925#
926config ARCH_SUPPORTS_INT128
927 bool
928
929# For architectures that (ab)use NUMA to represent different memory regions
930# all cpu-local but of different latencies, such as SuperH.
931#
932config ARCH_WANT_NUMA_VARIABLE_LOCALITY
933 bool
934
935config NUMA_BALANCING
936 bool "Memory placement aware NUMA scheduler"
937 depends on ARCH_SUPPORTS_NUMA_BALANCING
938 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
939 depends on SMP && NUMA && MIGRATION && !PREEMPT_RT
940 help
941 This option adds support for automatic NUMA aware memory/task placement.
942 The mechanism is quite primitive and is based on migrating memory when
943 it has references to the node the task is running on.
944
945 This system will be inactive on UMA systems.
946
947config NUMA_BALANCING_DEFAULT_ENABLED
948 bool "Automatically enable NUMA aware memory/task placement"
949 default y
950 depends on NUMA_BALANCING
951 help
952 If set, automatic NUMA balancing will be enabled if running on a NUMA
953 machine.
954
955config SLAB_OBJ_EXT
956 bool
957
958menuconfig CGROUPS
959 bool "Control Group support"
960 select KERNFS
961 help
962 This option adds support for grouping sets of processes together, for
963 use with process control subsystems such as Cpusets, CFS, memory
964 controls or device isolation.
965 See
966 - Documentation/scheduler/sched-design-CFS.rst (CFS)
967 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
968 and resource control)
969
970 Say N if unsure.
971
972if CGROUPS
973
974config PAGE_COUNTER
975 bool
976
977config CGROUP_FAVOR_DYNMODS
978 bool "Favor dynamic modification latency reduction by default"
979 help
980 This option enables the "favordynmods" mount option by default
981 which reduces the latencies of dynamic cgroup modifications such
982 as task migrations and controller on/offs at the cost of making
983 hot path operations such as forks and exits more expensive.
984
985 Say N if unsure.
986
987config MEMCG
988 bool "Memory controller"
989 select PAGE_COUNTER
990 select EVENTFD
991 select SLAB_OBJ_EXT
992 help
993 Provides control over the memory footprint of tasks in a cgroup.
994
995config MEMCG_V1
996 bool "Legacy cgroup v1 memory controller"
997 depends on MEMCG
998 default n
999 help
1000 Legacy cgroup v1 memory controller which has been deprecated by
1001 cgroup v2 implementation. The v1 is there for legacy applications
1002 which haven't migrated to the new cgroup v2 interface yet. If you
1003 do not have any such application then you are completely fine leaving
1004 this option disabled.
1005
1006 Please note that feature set of the legacy memory controller is likely
1007 going to shrink due to deprecation process. New deployments with v1
1008 controller are highly discouraged.
1009
1010 Say N if unsure.
1011
1012config BLK_CGROUP
1013 bool "IO controller"
1014 depends on BLOCK
1015 default n
1016 help
1017 Generic block IO controller cgroup interface. This is the common
1018 cgroup interface which should be used by various IO controlling
1019 policies.
1020
1021 Currently, CFQ IO scheduler uses it to recognize task groups and
1022 control disk bandwidth allocation (proportional time slice allocation)
1023 to such task groups. It is also used by bio throttling logic in
1024 block layer to implement upper limit in IO rates on a device.
1025
1026 This option only enables generic Block IO controller infrastructure.
1027 One needs to also enable actual IO controlling logic/policy. For
1028 enabling proportional weight division of disk bandwidth in CFQ, set
1029 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1030 CONFIG_BLK_DEV_THROTTLING=y.
1031
1032 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
1033
1034config CGROUP_WRITEBACK
1035 bool
1036 depends on MEMCG && BLK_CGROUP
1037 default y
1038
1039menuconfig CGROUP_SCHED
1040 bool "CPU controller"
1041 default n
1042 help
1043 This feature lets CPU scheduler recognize task groups and control CPU
1044 bandwidth allocation to such task groups. It uses cgroups to group
1045 tasks.
1046
1047if CGROUP_SCHED
1048config GROUP_SCHED_WEIGHT
1049 def_bool n
1050
1051config FAIR_GROUP_SCHED
1052 bool "Group scheduling for SCHED_OTHER"
1053 depends on CGROUP_SCHED
1054 select GROUP_SCHED_WEIGHT
1055 default CGROUP_SCHED
1056
1057config CFS_BANDWIDTH
1058 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
1059 depends on FAIR_GROUP_SCHED
1060 default n
1061 help
1062 This option allows users to define CPU bandwidth rates (limits) for
1063 tasks running within the fair group scheduler. Groups with no limit
1064 set are considered to be unconstrained and will run with no
1065 restriction.
1066 See Documentation/scheduler/sched-bwc.rst for more information.
1067
1068config RT_GROUP_SCHED
1069 bool "Group scheduling for SCHED_RR/FIFO"
1070 depends on CGROUP_SCHED
1071 default n
1072 help
1073 This feature lets you explicitly allocate real CPU bandwidth
1074 to task groups. If enabled, it will also make it impossible to
1075 schedule realtime tasks for non-root users until you allocate
1076 realtime bandwidth for them.
1077 See Documentation/scheduler/sched-rt-group.rst for more information.
1078
1079config EXT_GROUP_SCHED
1080 bool
1081 depends on SCHED_CLASS_EXT && CGROUP_SCHED
1082 select GROUP_SCHED_WEIGHT
1083 default y
1084
1085endif #CGROUP_SCHED
1086
1087config SCHED_MM_CID
1088 def_bool y
1089 depends on SMP && RSEQ
1090
1091config UCLAMP_TASK_GROUP
1092 bool "Utilization clamping per group of tasks"
1093 depends on CGROUP_SCHED
1094 depends on UCLAMP_TASK
1095 default n
1096 help
1097 This feature enables the scheduler to track the clamped utilization
1098 of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
1099
1100 When this option is enabled, the user can specify a min and max
1101 CPU bandwidth which is allowed for each single task in a group.
1102 The max bandwidth allows to clamp the maximum frequency a task
1103 can use, while the min bandwidth allows to define a minimum
1104 frequency a task will always use.
1105
1106 When task group based utilization clamping is enabled, an eventually
1107 specified task-specific clamp value is constrained by the cgroup
1108 specified clamp value. Both minimum and maximum task clamping cannot
1109 be bigger than the corresponding clamping defined at task group level.
1110
1111 If in doubt, say N.
1112
1113config CGROUP_PIDS
1114 bool "PIDs controller"
1115 help
1116 Provides enforcement of process number limits in the scope of a
1117 cgroup. Any attempt to fork more processes than is allowed in the
1118 cgroup will fail. PIDs are fundamentally a global resource because it
1119 is fairly trivial to reach PID exhaustion before you reach even a
1120 conservative kmemcg limit. As a result, it is possible to grind a
1121 system to halt without being limited by other cgroup policies. The
1122 PIDs controller is designed to stop this from happening.
1123
1124 It should be noted that organisational operations (such as attaching
1125 to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
1126 since the PIDs limit only affects a process's ability to fork, not to
1127 attach to a cgroup.
1128
1129config CGROUP_RDMA
1130 bool "RDMA controller"
1131 help
1132 Provides enforcement of RDMA resources defined by IB stack.
1133 It is fairly easy for consumers to exhaust RDMA resources, which
1134 can result into resource unavailability to other consumers.
1135 RDMA controller is designed to stop this from happening.
1136 Attaching processes with active RDMA resources to the cgroup
1137 hierarchy is allowed even if can cross the hierarchy's limit.
1138
1139config CGROUP_FREEZER
1140 bool "Freezer controller"
1141 help
1142 Provides a way to freeze and unfreeze all tasks in a
1143 cgroup.
1144
1145 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1146 controller includes important in-kernel memory consumers per default.
1147
1148 If you're using cgroup2, say N.
1149
1150config CGROUP_HUGETLB
1151 bool "HugeTLB controller"
1152 depends on HUGETLB_PAGE
1153 select PAGE_COUNTER
1154 default n
1155 help
1156 Provides a cgroup controller for HugeTLB pages.
1157 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1158 The limit is enforced during page fault. Since HugeTLB doesn't
1159 support page reclaim, enforcing the limit at page fault time implies
1160 that, the application will get SIGBUS signal if it tries to access
1161 HugeTLB pages beyond its limit. This requires the application to know
1162 beforehand how much HugeTLB pages it would require for its use. The
1163 control group is tracked in the third page lru pointer. This means
1164 that we cannot use the controller with huge page less than 3 pages.
1165
1166config CPUSETS
1167 bool "Cpuset controller"
1168 depends on SMP
1169 select UNION_FIND
1170 help
1171 This option will let you create and manage CPUSETs which
1172 allow dynamically partitioning a system into sets of CPUs and
1173 Memory Nodes and assigning tasks to run only within those sets.
1174 This is primarily useful on large SMP or NUMA systems.
1175
1176 Say N if unsure.
1177
1178config CPUSETS_V1
1179 bool "Legacy cgroup v1 cpusets controller"
1180 depends on CPUSETS
1181 default n
1182 help
1183 Legacy cgroup v1 cpusets controller which has been deprecated by
1184 cgroup v2 implementation. The v1 is there for legacy applications
1185 which haven't migrated to the new cgroup v2 interface yet. If you
1186 do not have any such application then you are completely fine leaving
1187 this option disabled.
1188
1189 Say N if unsure.
1190
1191config PROC_PID_CPUSET
1192 bool "Include legacy /proc/<pid>/cpuset file"
1193 depends on CPUSETS
1194 default y
1195
1196config CGROUP_DEVICE
1197 bool "Device controller"
1198 help
1199 Provides a cgroup controller implementing whitelists for
1200 devices which a process in the cgroup can mknod or open.
1201
1202config CGROUP_CPUACCT
1203 bool "Simple CPU accounting controller"
1204 help
1205 Provides a simple controller for monitoring the
1206 total CPU consumed by the tasks in a cgroup.
1207
1208config CGROUP_PERF
1209 bool "Perf controller"
1210 depends on PERF_EVENTS
1211 help
1212 This option extends the perf per-cpu mode to restrict monitoring
1213 to threads which belong to the cgroup specified and run on the
1214 designated cpu. Or this can be used to have cgroup ID in samples
1215 so that it can monitor performance events among cgroups.
1216
1217 Say N if unsure.
1218
1219config CGROUP_BPF
1220 bool "Support for eBPF programs attached to cgroups"
1221 depends on BPF_SYSCALL
1222 select SOCK_CGROUP_DATA
1223 help
1224 Allow attaching eBPF programs to a cgroup using the bpf(2)
1225 syscall command BPF_PROG_ATTACH.
1226
1227 In which context these programs are accessed depends on the type
1228 of attachment. For instance, programs that are attached using
1229 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1230 inet sockets.
1231
1232config CGROUP_MISC
1233 bool "Misc resource controller"
1234 default n
1235 help
1236 Provides a controller for miscellaneous resources on a host.
1237
1238 Miscellaneous scalar resources are the resources on the host system
1239 which cannot be abstracted like the other cgroups. This controller
1240 tracks and limits the miscellaneous resources used by a process
1241 attached to a cgroup hierarchy.
1242
1243 For more information, please check misc cgroup section in
1244 /Documentation/admin-guide/cgroup-v2.rst.
1245
1246config CGROUP_DEBUG
1247 bool "Debug controller"
1248 default n
1249 depends on DEBUG_KERNEL
1250 help
1251 This option enables a simple controller that exports
1252 debugging information about the cgroups framework. This
1253 controller is for control cgroup debugging only. Its
1254 interfaces are not stable.
1255
1256 Say N.
1257
1258config SOCK_CGROUP_DATA
1259 bool
1260 default n
1261
1262endif # CGROUPS
1263
1264menuconfig NAMESPACES
1265 bool "Namespaces support" if EXPERT
1266 depends on MULTIUSER
1267 default !EXPERT
1268 help
1269 Provides the way to make tasks work with different objects using
1270 the same id. For example same IPC id may refer to different objects
1271 or same user id or pid may refer to different tasks when used in
1272 different namespaces.
1273
1274if NAMESPACES
1275
1276config UTS_NS
1277 bool "UTS namespace"
1278 default y
1279 help
1280 In this namespace tasks see different info provided with the
1281 uname() system call
1282
1283config TIME_NS
1284 bool "TIME namespace"
1285 depends on GENERIC_VDSO_TIME_NS
1286 default y
1287 help
1288 In this namespace boottime and monotonic clocks can be set.
1289 The time will keep going with the same pace.
1290
1291config IPC_NS
1292 bool "IPC namespace"
1293 depends on (SYSVIPC || POSIX_MQUEUE)
1294 default y
1295 help
1296 In this namespace tasks work with IPC ids which correspond to
1297 different IPC objects in different namespaces.
1298
1299config USER_NS
1300 bool "User namespace"
1301 default n
1302 help
1303 This allows containers, i.e. vservers, to use user namespaces
1304 to provide different user info for different servers.
1305
1306 When user namespaces are enabled in the kernel it is
1307 recommended that the MEMCG option also be enabled and that
1308 user-space use the memory control groups to limit the amount
1309 of memory a memory unprivileged users can use.
1310
1311 If unsure, say N.
1312
1313config PID_NS
1314 bool "PID Namespaces"
1315 default y
1316 help
1317 Support process id namespaces. This allows having multiple
1318 processes with the same pid as long as they are in different
1319 pid namespaces. This is a building block of containers.
1320
1321config NET_NS
1322 bool "Network namespace"
1323 depends on NET
1324 default y
1325 help
1326 Allow user space to create what appear to be multiple instances
1327 of the network stack.
1328
1329endif # NAMESPACES
1330
1331config CHECKPOINT_RESTORE
1332 bool "Checkpoint/restore support"
1333 depends on PROC_FS
1334 select PROC_CHILDREN
1335 select KCMP
1336 default n
1337 help
1338 Enables additional kernel features in a sake of checkpoint/restore.
1339 In particular it adds auxiliary prctl codes to setup process text,
1340 data and heap segment sizes, and a few additional /proc filesystem
1341 entries.
1342
1343 If unsure, say N here.
1344
1345config SCHED_AUTOGROUP
1346 bool "Automatic process group scheduling"
1347 select CGROUPS
1348 select CGROUP_SCHED
1349 select FAIR_GROUP_SCHED
1350 help
1351 This option optimizes the scheduler for common desktop workloads by
1352 automatically creating and populating task groups. This separation
1353 of workloads isolates aggressive CPU burners (like build jobs) from
1354 desktop applications. Task group autogeneration is currently based
1355 upon task session.
1356
1357config RELAY
1358 bool "Kernel->user space relay support (formerly relayfs)"
1359 select IRQ_WORK
1360 help
1361 This option enables support for relay interface support in
1362 certain file systems (such as debugfs).
1363 It is designed to provide an efficient mechanism for tools and
1364 facilities to relay large amounts of data from kernel space to
1365 user space.
1366
1367 If unsure, say N.
1368
1369config BLK_DEV_INITRD
1370 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1371 help
1372 The initial RAM filesystem is a ramfs which is loaded by the
1373 boot loader (loadlin or lilo) and that is mounted as root
1374 before the normal boot procedure. It is typically used to
1375 load modules needed to mount the "real" root file system,
1376 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1377
1378 If RAM disk support (BLK_DEV_RAM) is also included, this
1379 also enables initial RAM disk (initrd) support and adds
1380 15 Kbytes (more on some other architectures) to the kernel size.
1381
1382 If unsure say Y.
1383
1384if BLK_DEV_INITRD
1385
1386source "usr/Kconfig"
1387
1388endif
1389
1390config BOOT_CONFIG
1391 bool "Boot config support"
1392 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED
1393 help
1394 Extra boot config allows system admin to pass a config file as
1395 complemental extension of kernel cmdline when booting.
1396 The boot config file must be attached at the end of initramfs
1397 with checksum, size and magic word.
1398 See <file:Documentation/admin-guide/bootconfig.rst> for details.
1399
1400 If unsure, say Y.
1401
1402config BOOT_CONFIG_FORCE
1403 bool "Force unconditional bootconfig processing"
1404 depends on BOOT_CONFIG
1405 default y if BOOT_CONFIG_EMBED
1406 help
1407 With this Kconfig option set, BOOT_CONFIG processing is carried
1408 out even when the "bootconfig" kernel-boot parameter is omitted.
1409 In fact, with this Kconfig option set, there is no way to
1410 make the kernel ignore the BOOT_CONFIG-supplied kernel-boot
1411 parameters.
1412
1413 If unsure, say N.
1414
1415config BOOT_CONFIG_EMBED
1416 bool "Embed bootconfig file in the kernel"
1417 depends on BOOT_CONFIG
1418 help
1419 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the
1420 kernel. Usually, the bootconfig file is loaded with the initrd
1421 image. But if the system doesn't support initrd, this option will
1422 help you by embedding a bootconfig file while building the kernel.
1423
1424 If unsure, say N.
1425
1426config BOOT_CONFIG_EMBED_FILE
1427 string "Embedded bootconfig file path"
1428 depends on BOOT_CONFIG_EMBED
1429 help
1430 Specify a bootconfig file which will be embedded to the kernel.
1431 This bootconfig will be used if there is no initrd or no other
1432 bootconfig in the initrd.
1433
1434config INITRAMFS_PRESERVE_MTIME
1435 bool "Preserve cpio archive mtimes in initramfs"
1436 default y
1437 help
1438 Each entry in an initramfs cpio archive carries an mtime value. When
1439 enabled, extracted cpio items take this mtime, with directory mtime
1440 setting deferred until after creation of any child entries.
1441
1442 If unsure, say Y.
1443
1444choice
1445 prompt "Compiler optimization level"
1446 default CC_OPTIMIZE_FOR_PERFORMANCE
1447
1448config CC_OPTIMIZE_FOR_PERFORMANCE
1449 bool "Optimize for performance (-O2)"
1450 help
1451 This is the default optimization level for the kernel, building
1452 with the "-O2" compiler flag for best performance and most
1453 helpful compile-time warnings.
1454
1455config CC_OPTIMIZE_FOR_SIZE
1456 bool "Optimize for size (-Os)"
1457 help
1458 Choosing this option will pass "-Os" to your compiler resulting
1459 in a smaller kernel.
1460
1461endchoice
1462
1463config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1464 bool
1465 help
1466 This requires that the arch annotates or otherwise protects
1467 its external entry points from being discarded. Linker scripts
1468 must also merge .text.*, .data.*, and .bss.* correctly into
1469 output sections. Care must be taken not to pull in unrelated
1470 sections (e.g., '.text.init'). Typically '.' in section names
1471 is used to distinguish them from label names / C identifiers.
1472
1473config LD_DEAD_CODE_DATA_ELIMINATION
1474 bool "Dead code and data elimination (EXPERIMENTAL)"
1475 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1476 depends on EXPERT
1477 depends on $(cc-option,-ffunction-sections -fdata-sections)
1478 depends on $(ld-option,--gc-sections)
1479 help
1480 Enable this if you want to do dead code and data elimination with
1481 the linker by compiling with -ffunction-sections -fdata-sections,
1482 and linking with --gc-sections.
1483
1484 This can reduce on disk and in-memory size of the kernel
1485 code and static data, particularly for small configs and
1486 on small systems. This has the possibility of introducing
1487 silently broken kernel if the required annotations are not
1488 present. This option is not well tested yet, so use at your
1489 own risk.
1490
1491config LD_ORPHAN_WARN
1492 def_bool y
1493 depends on ARCH_WANT_LD_ORPHAN_WARN
1494 depends on $(ld-option,--orphan-handling=warn)
1495 depends on $(ld-option,--orphan-handling=error)
1496
1497config LD_ORPHAN_WARN_LEVEL
1498 string
1499 depends on LD_ORPHAN_WARN
1500 default "error" if WERROR
1501 default "warn"
1502
1503config SYSCTL
1504 bool
1505
1506config HAVE_UID16
1507 bool
1508
1509config SYSCTL_EXCEPTION_TRACE
1510 bool
1511 help
1512 Enable support for /proc/sys/debug/exception-trace.
1513
1514config SYSCTL_ARCH_UNALIGN_NO_WARN
1515 bool
1516 help
1517 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1518 Allows arch to define/use @no_unaligned_warning to possibly warn
1519 about unaligned access emulation going on under the hood.
1520
1521config SYSCTL_ARCH_UNALIGN_ALLOW
1522 bool
1523 help
1524 Enable support for /proc/sys/kernel/unaligned-trap
1525 Allows arches to define/use @unaligned_enabled to runtime toggle
1526 the unaligned access emulation.
1527 see arch/parisc/kernel/unaligned.c for reference
1528
1529config HAVE_PCSPKR_PLATFORM
1530 bool
1531
1532menuconfig EXPERT
1533 bool "Configure standard kernel features (expert users)"
1534 # Unhide debug options, to make the on-by-default options visible
1535 select DEBUG_KERNEL
1536 help
1537 This option allows certain base kernel options and settings
1538 to be disabled or tweaked. This is for specialized
1539 environments which can tolerate a "non-standard" kernel.
1540 Only use this if you really know what you are doing.
1541
1542config UID16
1543 bool "Enable 16-bit UID system calls" if EXPERT
1544 depends on HAVE_UID16 && MULTIUSER
1545 default y
1546 help
1547 This enables the legacy 16-bit UID syscall wrappers.
1548
1549config MULTIUSER
1550 bool "Multiple users, groups and capabilities support" if EXPERT
1551 default y
1552 help
1553 This option enables support for non-root users, groups and
1554 capabilities.
1555
1556 If you say N here, all processes will run with UID 0, GID 0, and all
1557 possible capabilities. Saying N here also compiles out support for
1558 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1559 setgid, and capset.
1560
1561 If unsure, say Y here.
1562
1563config SGETMASK_SYSCALL
1564 bool "sgetmask/ssetmask syscalls support" if EXPERT
1565 default PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1566 help
1567 sys_sgetmask and sys_ssetmask are obsolete system calls
1568 no longer supported in libc but still enabled by default in some
1569 architectures.
1570
1571 If unsure, leave the default option here.
1572
1573config SYSFS_SYSCALL
1574 bool "Sysfs syscall support" if EXPERT
1575 default y
1576 help
1577 sys_sysfs is an obsolete system call no longer supported in libc.
1578 Note that disabling this option is more secure but might break
1579 compatibility with some systems.
1580
1581 If unsure say Y here.
1582
1583config FHANDLE
1584 bool "open by fhandle syscalls" if EXPERT
1585 select EXPORTFS
1586 default y
1587 help
1588 If you say Y here, a user level program will be able to map
1589 file names to handle and then later use the handle for
1590 different file system operations. This is useful in implementing
1591 userspace file servers, which now track files using handles instead
1592 of names. The handle would remain the same even if file names
1593 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1594 syscalls.
1595
1596config POSIX_TIMERS
1597 bool "Posix Clocks & timers" if EXPERT
1598 default y
1599 help
1600 This includes native support for POSIX timers to the kernel.
1601 Some embedded systems have no use for them and therefore they
1602 can be configured out to reduce the size of the kernel image.
1603
1604 When this option is disabled, the following syscalls won't be
1605 available: timer_create, timer_gettime: timer_getoverrun,
1606 timer_settime, timer_delete, clock_adjtime, getitimer,
1607 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1608 clock_getres and clock_nanosleep syscalls will be limited to
1609 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1610
1611 If unsure say y.
1612
1613config PRINTK
1614 default y
1615 bool "Enable support for printk" if EXPERT
1616 select IRQ_WORK
1617 help
1618 This option enables normal printk support. Removing it
1619 eliminates most of the message strings from the kernel image
1620 and makes the kernel more or less silent. As this makes it
1621 very difficult to diagnose system problems, saying N here is
1622 strongly discouraged.
1623
1624config BUG
1625 bool "BUG() support" if EXPERT
1626 default y
1627 help
1628 Disabling this option eliminates support for BUG and WARN, reducing
1629 the size of your kernel image and potentially quietly ignoring
1630 numerous fatal conditions. You should only consider disabling this
1631 option for embedded systems with no facilities for reporting errors.
1632 Just say Y.
1633
1634config ELF_CORE
1635 depends on COREDUMP
1636 default y
1637 bool "Enable ELF core dumps" if EXPERT
1638 help
1639 Enable support for generating core dumps. Disabling saves about 4k.
1640
1641
1642config PCSPKR_PLATFORM
1643 bool "Enable PC-Speaker support" if EXPERT
1644 depends on HAVE_PCSPKR_PLATFORM
1645 select I8253_LOCK
1646 default y
1647 help
1648 This option allows to disable the internal PC-Speaker
1649 support, saving some memory.
1650
1651config BASE_SMALL
1652 bool "Enable smaller-sized data structures for core" if EXPERT
1653 help
1654 Enabling this option reduces the size of miscellaneous core
1655 kernel data structures. This saves memory on small machines,
1656 but may reduce performance.
1657
1658config FUTEX
1659 bool "Enable futex support" if EXPERT
1660 depends on !(SPARC32 && SMP)
1661 default y
1662 imply RT_MUTEXES
1663 help
1664 Disabling this option will cause the kernel to be built without
1665 support for "fast userspace mutexes". The resulting kernel may not
1666 run glibc-based applications correctly.
1667
1668config FUTEX_PI
1669 bool
1670 depends on FUTEX && RT_MUTEXES
1671 default y
1672
1673config EPOLL
1674 bool "Enable eventpoll support" if EXPERT
1675 default y
1676 help
1677 Disabling this option will cause the kernel to be built without
1678 support for epoll family of system calls.
1679
1680config SIGNALFD
1681 bool "Enable signalfd() system call" if EXPERT
1682 default y
1683 help
1684 Enable the signalfd() system call that allows to receive signals
1685 on a file descriptor.
1686
1687 If unsure, say Y.
1688
1689config TIMERFD
1690 bool "Enable timerfd() system call" if EXPERT
1691 default y
1692 help
1693 Enable the timerfd() system call that allows to receive timer
1694 events on a file descriptor.
1695
1696 If unsure, say Y.
1697
1698config EVENTFD
1699 bool "Enable eventfd() system call" if EXPERT
1700 default y
1701 help
1702 Enable the eventfd() system call that allows to receive both
1703 kernel notification (ie. KAIO) or userspace notifications.
1704
1705 If unsure, say Y.
1706
1707config SHMEM
1708 bool "Use full shmem filesystem" if EXPERT
1709 default y
1710 depends on MMU
1711 help
1712 The shmem is an internal filesystem used to manage shared memory.
1713 It is backed by swap and manages resource limits. It is also exported
1714 to userspace as tmpfs if TMPFS is enabled. Disabling this
1715 option replaces shmem and tmpfs with the much simpler ramfs code,
1716 which may be appropriate on small systems without swap.
1717
1718config AIO
1719 bool "Enable AIO support" if EXPERT
1720 default y
1721 help
1722 This option enables POSIX asynchronous I/O which may by used
1723 by some high performance threaded applications. Disabling
1724 this option saves about 7k.
1725
1726config IO_URING
1727 bool "Enable IO uring support" if EXPERT
1728 select IO_WQ
1729 default y
1730 help
1731 This option enables support for the io_uring interface, enabling
1732 applications to submit and complete IO through submission and
1733 completion rings that are shared between the kernel and application.
1734
1735config GCOV_PROFILE_URING
1736 bool "Enable GCOV profiling on the io_uring subsystem"
1737 depends on GCOV_KERNEL
1738 help
1739 Enable GCOV profiling on the io_uring subsystem, to facilitate
1740 code coverage testing.
1741
1742 If unsure, say N.
1743
1744 Note that this will have a negative impact on the performance of
1745 the io_uring subsystem, hence this should only be enabled for
1746 specific test purposes.
1747
1748config ADVISE_SYSCALLS
1749 bool "Enable madvise/fadvise syscalls" if EXPERT
1750 default y
1751 help
1752 This option enables the madvise and fadvise syscalls, used by
1753 applications to advise the kernel about their future memory or file
1754 usage, improving performance. If building an embedded system where no
1755 applications use these syscalls, you can disable this option to save
1756 space.
1757
1758config MEMBARRIER
1759 bool "Enable membarrier() system call" if EXPERT
1760 default y
1761 help
1762 Enable the membarrier() system call that allows issuing memory
1763 barriers across all running threads, which can be used to distribute
1764 the cost of user-space memory barriers asymmetrically by transforming
1765 pairs of memory barriers into pairs consisting of membarrier() and a
1766 compiler barrier.
1767
1768 If unsure, say Y.
1769
1770config KCMP
1771 bool "Enable kcmp() system call" if EXPERT
1772 help
1773 Enable the kernel resource comparison system call. It provides
1774 user-space with the ability to compare two processes to see if they
1775 share a common resource, such as a file descriptor or even virtual
1776 memory space.
1777
1778 If unsure, say N.
1779
1780config RSEQ
1781 bool "Enable rseq() system call" if EXPERT
1782 default y
1783 depends on HAVE_RSEQ
1784 select MEMBARRIER
1785 help
1786 Enable the restartable sequences system call. It provides a
1787 user-space cache for the current CPU number value, which
1788 speeds up getting the current CPU number from user-space,
1789 as well as an ABI to speed up user-space operations on
1790 per-CPU data.
1791
1792 If unsure, say Y.
1793
1794config DEBUG_RSEQ
1795 default n
1796 bool "Enable debugging of rseq() system call" if EXPERT
1797 depends on RSEQ && DEBUG_KERNEL
1798 help
1799 Enable extra debugging checks for the rseq system call.
1800
1801 If unsure, say N.
1802
1803config CACHESTAT_SYSCALL
1804 bool "Enable cachestat() system call" if EXPERT
1805 default y
1806 help
1807 Enable the cachestat system call, which queries the page cache
1808 statistics of a file (number of cached pages, dirty pages,
1809 pages marked for writeback, (recently) evicted pages).
1810
1811 If unsure say Y here.
1812
1813config PC104
1814 bool "PC/104 support" if EXPERT
1815 help
1816 Expose PC/104 form factor device drivers and options available for
1817 selection and configuration. Enable this option if your target
1818 machine has a PC/104 bus.
1819
1820config KALLSYMS
1821 bool "Load all symbols for debugging/ksymoops" if EXPERT
1822 default y
1823 help
1824 Say Y here to let the kernel print out symbolic crash information and
1825 symbolic stack backtraces. This increases the size of the kernel
1826 somewhat, as all symbols have to be loaded into the kernel image.
1827
1828config KALLSYMS_SELFTEST
1829 bool "Test the basic functions and performance of kallsyms"
1830 depends on KALLSYMS
1831 default n
1832 help
1833 Test the basic functions and performance of some interfaces, such as
1834 kallsyms_lookup_name. It also calculates the compression rate of the
1835 kallsyms compression algorithm for the current symbol set.
1836
1837 Start self-test automatically after system startup. Suggest executing
1838 "dmesg | grep kallsyms_selftest" to collect test results. "finish" is
1839 displayed in the last line, indicating that the test is complete.
1840
1841config KALLSYMS_ALL
1842 bool "Include all symbols in kallsyms"
1843 depends on DEBUG_KERNEL && KALLSYMS
1844 help
1845 Normally kallsyms only contains the symbols of functions for nicer
1846 OOPS messages and backtraces (i.e., symbols from the text and inittext
1847 sections). This is sufficient for most cases. And only if you want to
1848 enable kernel live patching, or other less common use cases (e.g.,
1849 when a debugger is used) all symbols are required (i.e., names of
1850 variables from the data sections, etc).
1851
1852 This option makes sure that all symbols are loaded into the kernel
1853 image (i.e., symbols from all sections) in cost of increased kernel
1854 size (depending on the kernel configuration, it may be 300KiB or
1855 something like this).
1856
1857 Say N unless you really need all symbols, or kernel live patching.
1858
1859config KALLSYMS_ABSOLUTE_PERCPU
1860 bool
1861 depends on KALLSYMS
1862 default X86_64 && SMP
1863
1864# end of the "standard kernel features (expert users)" menu
1865
1866config ARCH_HAS_MEMBARRIER_CALLBACKS
1867 bool
1868
1869config ARCH_HAS_MEMBARRIER_SYNC_CORE
1870 bool
1871
1872config HAVE_PERF_EVENTS
1873 bool
1874 help
1875 See tools/perf/design.txt for details.
1876
1877config GUEST_PERF_EVENTS
1878 bool
1879 depends on HAVE_PERF_EVENTS
1880
1881config PERF_USE_VMALLOC
1882 bool
1883 help
1884 See tools/perf/design.txt for details
1885
1886menu "Kernel Performance Events And Counters"
1887
1888config PERF_EVENTS
1889 bool "Kernel performance events and counters"
1890 default y if PROFILING
1891 depends on HAVE_PERF_EVENTS
1892 select IRQ_WORK
1893 help
1894 Enable kernel support for various performance events provided
1895 by software and hardware.
1896
1897 Software events are supported either built-in or via the
1898 use of generic tracepoints.
1899
1900 Most modern CPUs support performance events via performance
1901 counter registers. These registers count the number of certain
1902 types of hw events: such as instructions executed, cachemisses
1903 suffered, or branches mis-predicted - without slowing down the
1904 kernel or applications. These registers can also trigger interrupts
1905 when a threshold number of events have passed - and can thus be
1906 used to profile the code that runs on that CPU.
1907
1908 The Linux Performance Event subsystem provides an abstraction of
1909 these software and hardware event capabilities, available via a
1910 system call and used by the "perf" utility in tools/perf/. It
1911 provides per task and per CPU counters, and it provides event
1912 capabilities on top of those.
1913
1914 Say Y if unsure.
1915
1916config DEBUG_PERF_USE_VMALLOC
1917 default n
1918 bool "Debug: use vmalloc to back perf mmap() buffers"
1919 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1920 select PERF_USE_VMALLOC
1921 help
1922 Use vmalloc memory to back perf mmap() buffers.
1923
1924 Mostly useful for debugging the vmalloc code on platforms
1925 that don't require it.
1926
1927 Say N if unsure.
1928
1929endmenu
1930
1931config SYSTEM_DATA_VERIFICATION
1932 def_bool n
1933 select SYSTEM_TRUSTED_KEYRING
1934 select KEYS
1935 select CRYPTO
1936 select CRYPTO_RSA
1937 select ASYMMETRIC_KEY_TYPE
1938 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1939 select ASN1
1940 select OID_REGISTRY
1941 select X509_CERTIFICATE_PARSER
1942 select PKCS7_MESSAGE_PARSER
1943 help
1944 Provide PKCS#7 message verification using the contents of the system
1945 trusted keyring to provide public keys. This then can be used for
1946 module verification, kexec image verification and firmware blob
1947 verification.
1948
1949config PROFILING
1950 bool "Profiling support"
1951 help
1952 Say Y here to enable the extended profiling support mechanisms used
1953 by profilers.
1954
1955config RUST
1956 bool "Rust support"
1957 depends on HAVE_RUST
1958 depends on RUST_IS_AVAILABLE
1959 depends on !MODVERSIONS
1960 depends on !GCC_PLUGIN_RANDSTRUCT
1961 depends on !RANDSTRUCT
1962 depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
1963 depends on !CFI_CLANG || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC
1964 select CFI_ICALL_NORMALIZE_INTEGERS if CFI_CLANG
1965 depends on !CALL_PADDING || RUSTC_VERSION >= 108100
1966 depends on !KASAN_SW_TAGS
1967 depends on !(MITIGATION_RETHUNK && KASAN) || RUSTC_VERSION >= 108300
1968 help
1969 Enables Rust support in the kernel.
1970
1971 This allows other Rust-related options, like drivers written in Rust,
1972 to be selected.
1973
1974 It is also required to be able to load external kernel modules
1975 written in Rust.
1976
1977 See Documentation/rust/ for more information.
1978
1979 If unsure, say N.
1980
1981config RUSTC_VERSION_TEXT
1982 string
1983 depends on RUST
1984 default "$(RUSTC_VERSION_TEXT)"
1985 help
1986 See `CC_VERSION_TEXT`.
1987
1988config BINDGEN_VERSION_TEXT
1989 string
1990 depends on RUST
1991 # The dummy parameter `workaround-for-0.69.0` is required to support 0.69.0
1992 # (https://github.com/rust-lang/rust-bindgen/pull/2678). It can be removed when
1993 # the minimum version is upgraded past that (0.69.1 already fixed the issue).
1994 default "$(shell,$(BINDGEN) --version workaround-for-0.69.0 2>/dev/null)"
1995
1996#
1997# Place an empty function call at each tracepoint site. Can be
1998# dynamically changed for a probe function.
1999#
2000config TRACEPOINTS
2001 bool
2002 select TASKS_TRACE_RCU
2003
2004source "kernel/Kconfig.kexec"
2005
2006endmenu # General setup
2007
2008source "arch/Kconfig"
2009
2010config RT_MUTEXES
2011 bool
2012 default y if PREEMPT_RT
2013
2014config MODULE_SIG_FORMAT
2015 def_bool n
2016 select SYSTEM_DATA_VERIFICATION
2017
2018source "kernel/module/Kconfig"
2019
2020config INIT_ALL_POSSIBLE
2021 bool
2022 help
2023 Back when each arch used to define their own cpu_online_mask and
2024 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2025 with all 1s, and others with all 0s. When they were centralised,
2026 it was better to provide this option than to break all the archs
2027 and have several arch maintainers pursuing me down dark alleys.
2028
2029source "block/Kconfig"
2030
2031config PREEMPT_NOTIFIERS
2032 bool
2033
2034config PADATA
2035 depends on SMP
2036 bool
2037
2038config ASN1
2039 tristate
2040 help
2041 Build a simple ASN.1 grammar compiler that produces a bytecode output
2042 that can be interpreted by the ASN.1 stream decoder and used to
2043 inform it as to what tags are to be expected in a stream and what
2044 functions to call on what tags.
2045
2046source "kernel/Kconfig.locks"
2047
2048config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
2049 bool
2050
2051config ARCH_HAS_PREPARE_SYNC_CORE_CMD
2052 bool
2053
2054config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2055 bool
2056
2057# It may be useful for an architecture to override the definitions of the
2058# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2059# and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2060# different calling convention for syscalls. They can also override the
2061# macros for not-implemented syscalls in kernel/sys_ni.c and
2062# kernel/time/posix-stubs.c. All these overrides need to be available in
2063# <asm/syscall_wrapper.h>.
2064config ARCH_HAS_SYSCALL_WRAPPER
2065 def_bool n