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 CC_CAN_LINK
64	bool
65	default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag)) if 64BIT
66	default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag))
67
68config CC_CAN_LINK_STATIC
69	bool
70	default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag) -static) if 64BIT
71	default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag) -static)
72
73config CC_HAS_ASM_GOTO
74	def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC))
75
76config CC_HAS_ASM_GOTO_OUTPUT
77	depends on CC_HAS_ASM_GOTO
78	def_bool $(success,echo 'int foo(int x) { asm goto ("": "=r"(x) ::: bar); return x; bar: return 0; }' | $(CC) -x c - -c -o /dev/null)
79
80config CC_HAS_ASM_GOTO_TIED_OUTPUT
81	depends on CC_HAS_ASM_GOTO_OUTPUT
82	# Detect buggy gcc and clang, fixed in gcc-11 clang-14.
83	def_bool $(success,echo 'int foo(int *x) { asm goto (".long (%l[bar]) - .\n": "+m"(*x) ::: bar); return *x; bar: return 0; }' | $CC -x c - -c -o /dev/null)
84
85config TOOLS_SUPPORT_RELR
86	def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
87
88config CC_HAS_ASM_INLINE
89	def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
90
91config CC_HAS_NO_PROFILE_FN_ATTR
92	def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
93
94config PAHOLE_VERSION
95	int
96	default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE))
97
98config CONSTRUCTORS
99	bool
100
101config IRQ_WORK
102	bool
103
104config BUILDTIME_TABLE_SORT
105	bool
106
107config THREAD_INFO_IN_TASK
108	bool
109	help
110	  Select this to move thread_info off the stack into task_struct.  To
111	  make this work, an arch will need to remove all thread_info fields
112	  except flags and fix any runtime bugs.
113
114	  One subtle change that will be needed is to use try_get_task_stack()
115	  and put_task_stack() in save_thread_stack_tsk() and get_wchan().
116
117menu "General setup"
118
119config BROKEN
120	bool
121
122config BROKEN_ON_SMP
123	bool
124	depends on BROKEN || !SMP
125	default y
126
127config INIT_ENV_ARG_LIMIT
128	int
129	default 32 if !UML
130	default 128 if UML
131	help
132	  Maximum of each of the number of arguments and environment
133	  variables passed to init from the kernel command line.
134
135config COMPILE_TEST
136	bool "Compile also drivers which will not load"
137	depends on HAS_IOMEM
138	help
139	  Some drivers can be compiled on a different platform than they are
140	  intended to be run on. Despite they cannot be loaded there (or even
141	  when they load they cannot be used due to missing HW support),
142	  developers still, opposing to distributors, might want to build such
143	  drivers to compile-test them.
144
145	  If you are a developer and want to build everything available, say Y
146	  here. If you are a user/distributor, say N here to exclude useless
147	  drivers to be distributed.
148
149config WERROR
150	bool "Compile the kernel with warnings as errors"
151	default COMPILE_TEST
152	help
153	  A kernel build should not cause any compiler warnings, and this
154	  enables the '-Werror' flag to enforce that rule by default.
155
156	  However, if you have a new (or very old) compiler with odd and
157	  unusual warnings, or you have some architecture with problems,
158	  you may need to disable this config option in order to
159	  successfully build the kernel.
160
161	  If in doubt, say Y.
162
163config UAPI_HEADER_TEST
164	bool "Compile test UAPI headers"
165	depends on HEADERS_INSTALL && CC_CAN_LINK
166	help
167	  Compile test headers exported to user-space to ensure they are
168	  self-contained, i.e. compilable as standalone units.
169
170	  If you are a developer or tester and want to ensure the exported
171	  headers are self-contained, say Y here. Otherwise, choose N.
172
173config LOCALVERSION
174	string "Local version - append to kernel release"
175	help
176	  Append an extra string to the end of your kernel version.
177	  This will show up when you type uname, for example.
178	  The string you set here will be appended after the contents of
179	  any files with a filename matching localversion* in your
180	  object and source tree, in that order.  Your total string can
181	  be a maximum of 64 characters.
182
183config LOCALVERSION_AUTO
184	bool "Automatically append version information to the version string"
185	default y
186	depends on !COMPILE_TEST
187	help
188	  This will try to automatically determine if the current tree is a
189	  release tree by looking for git tags that belong to the current
190	  top of tree revision.
191
192	  A string of the format -gxxxxxxxx will be added to the localversion
193	  if a git-based tree is found.  The string generated by this will be
194	  appended after any matching localversion* files, and after the value
195	  set in CONFIG_LOCALVERSION.
196
197	  (The actual string used here is the first eight characters produced
198	  by running the command:
199
200	    $ git rev-parse --verify HEAD
201
202	  which is done within the script "scripts/setlocalversion".)
203
204config BUILD_SALT
205	string "Build ID Salt"
206	default ""
207	help
208	  The build ID is used to link binaries and their debug info. Setting
209	  this option will use the value in the calculation of the build id.
210	  This is mostly useful for distributions which want to ensure the
211	  build is unique between builds. It's safe to leave the default.
212
213config HAVE_KERNEL_GZIP
214	bool
215
216config HAVE_KERNEL_BZIP2
217	bool
218
219config HAVE_KERNEL_LZMA
220	bool
221
222config HAVE_KERNEL_XZ
223	bool
224
225config HAVE_KERNEL_LZO
226	bool
227
228config HAVE_KERNEL_LZ4
229	bool
230
231config HAVE_KERNEL_ZSTD
232	bool
233
234config HAVE_KERNEL_UNCOMPRESSED
235	bool
236
237choice
238	prompt "Kernel compression mode"
239	default KERNEL_GZIP
240	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
241	help
242	  The linux kernel is a kind of self-extracting executable.
243	  Several compression algorithms are available, which differ
244	  in efficiency, compression and decompression speed.
245	  Compression speed is only relevant when building a kernel.
246	  Decompression speed is relevant at each boot.
247
248	  If you have any problems with bzip2 or lzma compressed
249	  kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
250	  version of this functionality (bzip2 only), for 2.4, was
251	  supplied by Christian Ludwig)
252
253	  High compression options are mostly useful for users, who
254	  are low on disk space (embedded systems), but for whom ram
255	  size matters less.
256
257	  If in doubt, select 'gzip'
258
259config KERNEL_GZIP
260	bool "Gzip"
261	depends on HAVE_KERNEL_GZIP
262	help
263	  The old and tried gzip compression. It provides a good balance
264	  between compression ratio and decompression speed.
265
266config KERNEL_BZIP2
267	bool "Bzip2"
268	depends on HAVE_KERNEL_BZIP2
269	help
270	  Its compression ratio and speed is intermediate.
271	  Decompression speed is slowest among the choices.  The kernel
272	  size is about 10% smaller with bzip2, in comparison to gzip.
273	  Bzip2 uses a large amount of memory. For modern kernels you
274	  will need at least 8MB RAM or more for booting.
275
276config KERNEL_LZMA
277	bool "LZMA"
278	depends on HAVE_KERNEL_LZMA
279	help
280	  This compression algorithm's ratio is best.  Decompression speed
281	  is between gzip and bzip2.  Compression is slowest.
282	  The kernel size is about 33% smaller with LZMA in comparison to gzip.
283
284config KERNEL_XZ
285	bool "XZ"
286	depends on HAVE_KERNEL_XZ
287	help
288	  XZ uses the LZMA2 algorithm and instruction set specific
289	  BCJ filters which can improve compression ratio of executable
290	  code. The size of the kernel is about 30% smaller with XZ in
291	  comparison to gzip. On architectures for which there is a BCJ
292	  filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
293	  will create a few percent smaller kernel than plain LZMA.
294
295	  The speed is about the same as with LZMA: The decompression
296	  speed of XZ is better than that of bzip2 but worse than gzip
297	  and LZO. Compression is slow.
298
299config KERNEL_LZO
300	bool "LZO"
301	depends on HAVE_KERNEL_LZO
302	help
303	  Its compression ratio is the poorest among the choices. The kernel
304	  size is about 10% bigger than gzip; however its speed
305	  (both compression and decompression) is the fastest.
306
307config KERNEL_LZ4
308	bool "LZ4"
309	depends on HAVE_KERNEL_LZ4
310	help
311	  LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
312	  A preliminary version of LZ4 de/compression tool is available at
313	  <https://code.google.com/p/lz4/>.
314
315	  Its compression ratio is worse than LZO. The size of the kernel
316	  is about 8% bigger than LZO. But the decompression speed is
317	  faster than LZO.
318
319config KERNEL_ZSTD
320	bool "ZSTD"
321	depends on HAVE_KERNEL_ZSTD
322	help
323	  ZSTD is a compression algorithm targeting intermediate compression
324	  with fast decompression speed. It will compress better than GZIP and
325	  decompress around the same speed as LZO, but slower than LZ4. You
326	  will need at least 192 KB RAM or more for booting. The zstd command
327	  line tool is required for compression.
328
329config KERNEL_UNCOMPRESSED
330	bool "None"
331	depends on HAVE_KERNEL_UNCOMPRESSED
332	help
333	  Produce uncompressed kernel image. This option is usually not what
334	  you want. It is useful for debugging the kernel in slow simulation
335	  environments, where decompressing and moving the kernel is awfully
336	  slow. This option allows early boot code to skip the decompressor
337	  and jump right at uncompressed kernel image.
338
339endchoice
340
341config DEFAULT_INIT
342	string "Default init path"
343	default ""
344	help
345	  This option determines the default init for the system if no init=
346	  option is passed on the kernel command line. If the requested path is
347	  not present, we will still then move on to attempting further
348	  locations (e.g. /sbin/init, etc). If this is empty, we will just use
349	  the fallback list when init= is not passed.
350
351config DEFAULT_HOSTNAME
352	string "Default hostname"
353	default "(none)"
354	help
355	  This option determines the default system hostname before userspace
356	  calls sethostname(2). The kernel traditionally uses "(none)" here,
357	  but you may wish to use a different default here to make a minimal
358	  system more usable with less configuration.
359
360config SYSVIPC
361	bool "System V IPC"
362	help
363	  Inter Process Communication is a suite of library functions and
364	  system calls which let processes (running programs) synchronize and
365	  exchange information. It is generally considered to be a good thing,
366	  and some programs won't run unless you say Y here. In particular, if
367	  you want to run the DOS emulator dosemu under Linux (read the
368	  DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
369	  you'll need to say Y here.
370
371	  You can find documentation about IPC with "info ipc" and also in
372	  section 6.4 of the Linux Programmer's Guide, available from
373	  <http://www.tldp.org/guides.html>.
374
375config SYSVIPC_SYSCTL
376	bool
377	depends on SYSVIPC
378	depends on SYSCTL
379	default y
380
381config SYSVIPC_COMPAT
382	def_bool y
383	depends on COMPAT && SYSVIPC
384
385config POSIX_MQUEUE
386	bool "POSIX Message Queues"
387	depends on NET
388	help
389	  POSIX variant of message queues is a part of IPC. In POSIX message
390	  queues every message has a priority which decides about succession
391	  of receiving it by a process. If you want to compile and run
392	  programs written e.g. for Solaris with use of its POSIX message
393	  queues (functions mq_*) say Y here.
394
395	  POSIX message queues are visible as a filesystem called 'mqueue'
396	  and can be mounted somewhere if you want to do filesystem
397	  operations on message queues.
398
399	  If unsure, say Y.
400
401config POSIX_MQUEUE_SYSCTL
402	bool
403	depends on POSIX_MQUEUE
404	depends on SYSCTL
405	default y
406
407config WATCH_QUEUE
408	bool "General notification queue"
409	default n
410	help
411
412	  This is a general notification queue for the kernel to pass events to
413	  userspace by splicing them into pipes.  It can be used in conjunction
414	  with watches for key/keyring change notifications and device
415	  notifications.
416
417	  See Documentation/watch_queue.rst
418
419config CROSS_MEMORY_ATTACH
420	bool "Enable process_vm_readv/writev syscalls"
421	depends on MMU
422	default y
423	help
424	  Enabling this option adds the system calls process_vm_readv and
425	  process_vm_writev which allow a process with the correct privileges
426	  to directly read from or write to another process' address space.
427	  See the man page for more details.
428
429config USELIB
430	bool "uselib syscall (for libc5 and earlier)"
431	default ALPHA || M68K || SPARC
432	help
433	  This option enables the uselib syscall, a system call used in the
434	  dynamic linker from libc5 and earlier.  glibc does not use this
435	  system call.  If you intend to run programs built on libc5 or
436	  earlier, you may need to enable this syscall.  Current systems
437	  running glibc can safely disable this.
438
439config AUDIT
440	bool "Auditing support"
441	depends on NET
442	help
443	  Enable auditing infrastructure that can be used with another
444	  kernel subsystem, such as SELinux (which requires this for
445	  logging of avc messages output).  System call auditing is included
446	  on architectures which support it.
447
448config HAVE_ARCH_AUDITSYSCALL
449	bool
450
451config AUDITSYSCALL
452	def_bool y
453	depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
454	select FSNOTIFY
455
456source "kernel/irq/Kconfig"
457source "kernel/time/Kconfig"
458source "kernel/bpf/Kconfig"
459source "kernel/Kconfig.preempt"
460
461menu "CPU/Task time and stats accounting"
462
463config VIRT_CPU_ACCOUNTING
464	bool
465
466choice
467	prompt "Cputime accounting"
468	default TICK_CPU_ACCOUNTING if !PPC64
469	default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
470
471# Kind of a stub config for the pure tick based cputime accounting
472config TICK_CPU_ACCOUNTING
473	bool "Simple tick based cputime accounting"
474	depends on !S390 && !NO_HZ_FULL
475	help
476	  This is the basic tick based cputime accounting that maintains
477	  statistics about user, system and idle time spent on per jiffies
478	  granularity.
479
480	  If unsure, say Y.
481
482config VIRT_CPU_ACCOUNTING_NATIVE
483	bool "Deterministic task and CPU time accounting"
484	depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
485	select VIRT_CPU_ACCOUNTING
486	help
487	  Select this option to enable more accurate task and CPU time
488	  accounting.  This is done by reading a CPU counter on each
489	  kernel entry and exit and on transitions within the kernel
490	  between system, softirq and hardirq state, so there is a
491	  small performance impact.  In the case of s390 or IBM POWER > 5,
492	  this also enables accounting of stolen time on logically-partitioned
493	  systems.
494
495config VIRT_CPU_ACCOUNTING_GEN
496	bool "Full dynticks CPU time accounting"
497	depends on HAVE_CONTEXT_TRACKING
498	depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
499	depends on GENERIC_CLOCKEVENTS
500	select VIRT_CPU_ACCOUNTING
501	select CONTEXT_TRACKING
502	help
503	  Select this option to enable task and CPU time accounting on full
504	  dynticks systems. This accounting is implemented by watching every
505	  kernel-user boundaries using the context tracking subsystem.
506	  The accounting is thus performed at the expense of some significant
507	  overhead.
508
509	  For now this is only useful if you are working on the full
510	  dynticks subsystem development.
511
512	  If unsure, say N.
513
514endchoice
515
516config IRQ_TIME_ACCOUNTING
517	bool "Fine granularity task level IRQ time accounting"
518	depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
519	help
520	  Select this option to enable fine granularity task irq time
521	  accounting. This is done by reading a timestamp on each
522	  transitions between softirq and hardirq state, so there can be a
523	  small performance impact.
524
525	  If in doubt, say N here.
526
527config HAVE_SCHED_AVG_IRQ
528	def_bool y
529	depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
530	depends on SMP
531
532config SCHED_THERMAL_PRESSURE
533	bool
534	default y if ARM && ARM_CPU_TOPOLOGY
535	default y if ARM64
536	depends on SMP
537	depends on CPU_FREQ_THERMAL
538	help
539	  Select this option to enable thermal pressure accounting in the
540	  scheduler. Thermal pressure is the value conveyed to the scheduler
541	  that reflects the reduction in CPU compute capacity resulted from
542	  thermal throttling. Thermal throttling occurs when the performance of
543	  a CPU is capped due to high operating temperatures.
544
545	  If selected, the scheduler will be able to balance tasks accordingly,
546	  i.e. put less load on throttled CPUs than on non/less throttled ones.
547
548	  This requires the architecture to implement
549	  arch_update_thermal_pressure() and arch_scale_thermal_pressure().
550
551config BSD_PROCESS_ACCT
552	bool "BSD Process Accounting"
553	depends on MULTIUSER
554	help
555	  If you say Y here, a user level program will be able to instruct the
556	  kernel (via a special system call) to write process accounting
557	  information to a file: whenever a process exits, information about
558	  that process will be appended to the file by the kernel.  The
559	  information includes things such as creation time, owning user,
560	  command name, memory usage, controlling terminal etc. (the complete
561	  list is in the struct acct in <file:include/linux/acct.h>).  It is
562	  up to the user level program to do useful things with this
563	  information.  This is generally a good idea, so say Y.
564
565config BSD_PROCESS_ACCT_V3
566	bool "BSD Process Accounting version 3 file format"
567	depends on BSD_PROCESS_ACCT
568	default n
569	help
570	  If you say Y here, the process accounting information is written
571	  in a new file format that also logs the process IDs of each
572	  process and its parent. Note that this file format is incompatible
573	  with previous v0/v1/v2 file formats, so you will need updated tools
574	  for processing it. A preliminary version of these tools is available
575	  at <http://www.gnu.org/software/acct/>.
576
577config TASKSTATS
578	bool "Export task/process statistics through netlink"
579	depends on NET
580	depends on MULTIUSER
581	default n
582	help
583	  Export selected statistics for tasks/processes through the
584	  generic netlink interface. Unlike BSD process accounting, the
585	  statistics are available during the lifetime of tasks/processes as
586	  responses to commands. Like BSD accounting, they are sent to user
587	  space on task exit.
588
589	  Say N if unsure.
590
591config TASK_DELAY_ACCT
592	bool "Enable per-task delay accounting"
593	depends on TASKSTATS
594	select SCHED_INFO
595	help
596	  Collect information on time spent by a task waiting for system
597	  resources like cpu, synchronous block I/O completion and swapping
598	  in pages. Such statistics can help in setting a task's priorities
599	  relative to other tasks for cpu, io, rss limits etc.
600
601	  Say N if unsure.
602
603config TASK_XACCT
604	bool "Enable extended accounting over taskstats"
605	depends on TASKSTATS
606	help
607	  Collect extended task accounting data and send the data
608	  to userland for processing over the taskstats interface.
609
610	  Say N if unsure.
611
612config TASK_IO_ACCOUNTING
613	bool "Enable per-task storage I/O accounting"
614	depends on TASK_XACCT
615	help
616	  Collect information on the number of bytes of storage I/O which this
617	  task has caused.
618
619	  Say N if unsure.
620
621config PSI
622	bool "Pressure stall information tracking"
623	help
624	  Collect metrics that indicate how overcommitted the CPU, memory,
625	  and IO capacity are in the system.
626
627	  If you say Y here, the kernel will create /proc/pressure/ with the
628	  pressure statistics files cpu, memory, and io. These will indicate
629	  the share of walltime in which some or all tasks in the system are
630	  delayed due to contention of the respective resource.
631
632	  In kernels with cgroup support, cgroups (cgroup2 only) will
633	  have cpu.pressure, memory.pressure, and io.pressure files,
634	  which aggregate pressure stalls for the grouped tasks only.
635
636	  For more details see Documentation/accounting/psi.rst.
637
638	  Say N if unsure.
639
640config PSI_DEFAULT_DISABLED
641	bool "Require boot parameter to enable pressure stall information tracking"
642	default n
643	depends on PSI
644	help
645	  If set, pressure stall information tracking will be disabled
646	  per default but can be enabled through passing psi=1 on the
647	  kernel commandline during boot.
648
649	  This feature adds some code to the task wakeup and sleep
650	  paths of the scheduler. The overhead is too low to affect
651	  common scheduling-intense workloads in practice (such as
652	  webservers, memcache), but it does show up in artificial
653	  scheduler stress tests, such as hackbench.
654
655	  If you are paranoid and not sure what the kernel will be
656	  used for, say Y.
657
658	  Say N if unsure.
659
660endmenu # "CPU/Task time and stats accounting"
661
662config CPU_ISOLATION
663	bool "CPU isolation"
664	depends on SMP || COMPILE_TEST
665	default y
666	help
667	  Make sure that CPUs running critical tasks are not disturbed by
668	  any source of "noise" such as unbound workqueues, timers, kthreads...
669	  Unbound jobs get offloaded to housekeeping CPUs. This is driven by
670	  the "isolcpus=" boot parameter.
671
672	  Say Y if unsure.
673
674source "kernel/rcu/Kconfig"
675
676config BUILD_BIN2C
677	bool
678	default n
679
680config IKCONFIG
681	tristate "Kernel .config support"
682	help
683	  This option enables the complete Linux kernel ".config" file
684	  contents to be saved in the kernel. It provides documentation
685	  of which kernel options are used in a running kernel or in an
686	  on-disk kernel.  This information can be extracted from the kernel
687	  image file with the script scripts/extract-ikconfig and used as
688	  input to rebuild the current kernel or to build another kernel.
689	  It can also be extracted from a running kernel by reading
690	  /proc/config.gz if enabled (below).
691
692config IKCONFIG_PROC
693	bool "Enable access to .config through /proc/config.gz"
694	depends on IKCONFIG && PROC_FS
695	help
696	  This option enables access to the kernel configuration file
697	  through /proc/config.gz.
698
699config IKHEADERS
700	tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
701	depends on SYSFS
702	help
703	  This option enables access to the in-kernel headers that are generated during
704	  the build process. These can be used to build eBPF tracing programs,
705	  or similar programs.  If you build the headers as a module, a module called
706	  kheaders.ko is built which can be loaded on-demand to get access to headers.
707
708config LOG_BUF_SHIFT
709	int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
710	range 12 25
711	default 17
712	depends on PRINTK
713	help
714	  Select the minimal kernel log buffer size as a power of 2.
715	  The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
716	  parameter, see below. Any higher size also might be forced
717	  by "log_buf_len" boot parameter.
718
719	  Examples:
720		     17 => 128 KB
721		     16 => 64 KB
722		     15 => 32 KB
723		     14 => 16 KB
724		     13 =>  8 KB
725		     12 =>  4 KB
726
727config LOG_CPU_MAX_BUF_SHIFT
728	int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
729	depends on SMP
730	range 0 21
731	default 12 if !BASE_SMALL
732	default 0 if BASE_SMALL
733	depends on PRINTK
734	help
735	  This option allows to increase the default ring buffer size
736	  according to the number of CPUs. The value defines the contribution
737	  of each CPU as a power of 2. The used space is typically only few
738	  lines however it might be much more when problems are reported,
739	  e.g. backtraces.
740
741	  The increased size means that a new buffer has to be allocated and
742	  the original static one is unused. It makes sense only on systems
743	  with more CPUs. Therefore this value is used only when the sum of
744	  contributions is greater than the half of the default kernel ring
745	  buffer as defined by LOG_BUF_SHIFT. The default values are set
746	  so that more than 16 CPUs are needed to trigger the allocation.
747
748	  Also this option is ignored when "log_buf_len" kernel parameter is
749	  used as it forces an exact (power of two) size of the ring buffer.
750
751	  The number of possible CPUs is used for this computation ignoring
752	  hotplugging making the computation optimal for the worst case
753	  scenario while allowing a simple algorithm to be used from bootup.
754
755	  Examples shift values and their meaning:
756		     17 => 128 KB for each CPU
757		     16 =>  64 KB for each CPU
758		     15 =>  32 KB for each CPU
759		     14 =>  16 KB for each CPU
760		     13 =>   8 KB for each CPU
761		     12 =>   4 KB for each CPU
762
763config PRINTK_SAFE_LOG_BUF_SHIFT
764	int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
765	range 10 21
766	default 13
767	depends on PRINTK
768	help
769	  Select the size of an alternate printk per-CPU buffer where messages
770	  printed from usafe contexts are temporary stored. One example would
771	  be NMI messages, another one - printk recursion. The messages are
772	  copied to the main log buffer in a safe context to avoid a deadlock.
773	  The value defines the size as a power of 2.
774
775	  Those messages are rare and limited. The largest one is when
776	  a backtrace is printed. It usually fits into 4KB. Select
777	  8KB if you want to be on the safe side.
778
779	  Examples:
780		     17 => 128 KB for each CPU
781		     16 =>  64 KB for each CPU
782		     15 =>  32 KB for each CPU
783		     14 =>  16 KB for each CPU
784		     13 =>   8 KB for each CPU
785		     12 =>   4 KB for each CPU
786
787config PRINTK_INDEX
788	bool "Printk indexing debugfs interface"
789	depends on PRINTK && DEBUG_FS
790	help
791	  Add support for indexing of all printk formats known at compile time
792	  at <debugfs>/printk/index/<module>.
793
794	  This can be used as part of maintaining daemons which monitor
795	  /dev/kmsg, as it permits auditing the printk formats present in a
796	  kernel, allowing detection of cases where monitored printks are
797	  changed or no longer present.
798
799	  There is no additional runtime cost to printk with this enabled.
800
801#
802# Architectures with an unreliable sched_clock() should select this:
803#
804config HAVE_UNSTABLE_SCHED_CLOCK
805	bool
806
807config GENERIC_SCHED_CLOCK
808	bool
809
810menu "Scheduler features"
811
812config UCLAMP_TASK
813	bool "Enable utilization clamping for RT/FAIR tasks"
814	depends on CPU_FREQ_GOV_SCHEDUTIL
815	help
816	  This feature enables the scheduler to track the clamped utilization
817	  of each CPU based on RUNNABLE tasks scheduled on that CPU.
818
819	  With this option, the user can specify the min and max CPU
820	  utilization allowed for RUNNABLE tasks. The max utilization defines
821	  the maximum frequency a task should use while the min utilization
822	  defines the minimum frequency it should use.
823
824	  Both min and max utilization clamp values are hints to the scheduler,
825	  aiming at improving its frequency selection policy, but they do not
826	  enforce or grant any specific bandwidth for tasks.
827
828	  If in doubt, say N.
829
830config UCLAMP_BUCKETS_COUNT
831	int "Number of supported utilization clamp buckets"
832	range 5 20
833	default 5
834	depends on UCLAMP_TASK
835	help
836	  Defines the number of clamp buckets to use. The range of each bucket
837	  will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
838	  number of clamp buckets the finer their granularity and the higher
839	  the precision of clamping aggregation and tracking at run-time.
840
841	  For example, with the minimum configuration value we will have 5
842	  clamp buckets tracking 20% utilization each. A 25% boosted tasks will
843	  be refcounted in the [20..39]% bucket and will set the bucket clamp
844	  effective value to 25%.
845	  If a second 30% boosted task should be co-scheduled on the same CPU,
846	  that task will be refcounted in the same bucket of the first task and
847	  it will boost the bucket clamp effective value to 30%.
848	  The clamp effective value of a bucket is reset to its nominal value
849	  (20% in the example above) when there are no more tasks refcounted in
850	  that bucket.
851
852	  An additional boost/capping margin can be added to some tasks. In the
853	  example above the 25% task will be boosted to 30% until it exits the
854	  CPU. If that should be considered not acceptable on certain systems,
855	  it's always possible to reduce the margin by increasing the number of
856	  clamp buckets to trade off used memory for run-time tracking
857	  precision.
858
859	  If in doubt, use the default value.
860
861endmenu
862
863#
864# For architectures that want to enable the support for NUMA-affine scheduler
865# balancing logic:
866#
867config ARCH_SUPPORTS_NUMA_BALANCING
868	bool
869
870#
871# For architectures that prefer to flush all TLBs after a number of pages
872# are unmapped instead of sending one IPI per page to flush. The architecture
873# must provide guarantees on what happens if a clean TLB cache entry is
874# written after the unmap. Details are in mm/rmap.c near the check for
875# should_defer_flush. The architecture should also consider if the full flush
876# and the refill costs are offset by the savings of sending fewer IPIs.
877config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
878	bool
879
880config CC_HAS_INT128
881	def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
882
883config CC_IMPLICIT_FALLTHROUGH
884	string
885	default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5)
886	default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough)
887
888# Currently, disable gcc-12 array-bounds globally.
889# We may want to target only particular configurations some day.
890config GCC12_NO_ARRAY_BOUNDS
891	def_bool y
892
893config CC_NO_ARRAY_BOUNDS
894	bool
895	default y if CC_IS_GCC && GCC_VERSION >= 120000 && GCC_VERSION < 130000 && GCC12_NO_ARRAY_BOUNDS
896
897#
898# For architectures that know their GCC __int128 support is sound
899#
900config ARCH_SUPPORTS_INT128
901	bool
902
903# For architectures that (ab)use NUMA to represent different memory regions
904# all cpu-local but of different latencies, such as SuperH.
905#
906config ARCH_WANT_NUMA_VARIABLE_LOCALITY
907	bool
908
909config NUMA_BALANCING
910	bool "Memory placement aware NUMA scheduler"
911	depends on ARCH_SUPPORTS_NUMA_BALANCING
912	depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
913	depends on SMP && NUMA && MIGRATION && !PREEMPT_RT
914	help
915	  This option adds support for automatic NUMA aware memory/task placement.
916	  The mechanism is quite primitive and is based on migrating memory when
917	  it has references to the node the task is running on.
918
919	  This system will be inactive on UMA systems.
920
921config NUMA_BALANCING_DEFAULT_ENABLED
922	bool "Automatically enable NUMA aware memory/task placement"
923	default y
924	depends on NUMA_BALANCING
925	help
926	  If set, automatic NUMA balancing will be enabled if running on a NUMA
927	  machine.
928
929menuconfig CGROUPS
930	bool "Control Group support"
931	select KERNFS
932	help
933	  This option adds support for grouping sets of processes together, for
934	  use with process control subsystems such as Cpusets, CFS, memory
935	  controls or device isolation.
936	  See
937		- Documentation/scheduler/sched-design-CFS.rst	(CFS)
938		- Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
939					  and resource control)
940
941	  Say N if unsure.
942
943if CGROUPS
944
945config PAGE_COUNTER
946	bool
947
948config MEMCG
949	bool "Memory controller"
950	select PAGE_COUNTER
951	select EVENTFD
952	help
953	  Provides control over the memory footprint of tasks in a cgroup.
954
955config MEMCG_SWAP
956	bool
957	depends on MEMCG && SWAP
958	default y
959
960config MEMCG_KMEM
961	bool
962	depends on MEMCG && !SLOB
963	default y
964
965config BLK_CGROUP
966	bool "IO controller"
967	depends on BLOCK
968	default n
969	help
970	Generic block IO controller cgroup interface. This is the common
971	cgroup interface which should be used by various IO controlling
972	policies.
973
974	Currently, CFQ IO scheduler uses it to recognize task groups and
975	control disk bandwidth allocation (proportional time slice allocation)
976	to such task groups. It is also used by bio throttling logic in
977	block layer to implement upper limit in IO rates on a device.
978
979	This option only enables generic Block IO controller infrastructure.
980	One needs to also enable actual IO controlling logic/policy. For
981	enabling proportional weight division of disk bandwidth in CFQ, set
982	CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
983	CONFIG_BLK_DEV_THROTTLING=y.
984
985	See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
986
987config CGROUP_WRITEBACK
988	bool
989	depends on MEMCG && BLK_CGROUP
990	default y
991
992menuconfig CGROUP_SCHED
993	bool "CPU controller"
994	default n
995	help
996	  This feature lets CPU scheduler recognize task groups and control CPU
997	  bandwidth allocation to such task groups. It uses cgroups to group
998	  tasks.
999
1000if CGROUP_SCHED
1001config FAIR_GROUP_SCHED
1002	bool "Group scheduling for SCHED_OTHER"
1003	depends on CGROUP_SCHED
1004	default CGROUP_SCHED
1005
1006config CFS_BANDWIDTH
1007	bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
1008	depends on FAIR_GROUP_SCHED
1009	default n
1010	help
1011	  This option allows users to define CPU bandwidth rates (limits) for
1012	  tasks running within the fair group scheduler.  Groups with no limit
1013	  set are considered to be unconstrained and will run with no
1014	  restriction.
1015	  See Documentation/scheduler/sched-bwc.rst for more information.
1016
1017config RT_GROUP_SCHED
1018	bool "Group scheduling for SCHED_RR/FIFO"
1019	depends on CGROUP_SCHED
1020	default n
1021	help
1022	  This feature lets you explicitly allocate real CPU bandwidth
1023	  to task groups. If enabled, it will also make it impossible to
1024	  schedule realtime tasks for non-root users until you allocate
1025	  realtime bandwidth for them.
1026	  See Documentation/scheduler/sched-rt-group.rst for more information.
1027
1028endif #CGROUP_SCHED
1029
1030config UCLAMP_TASK_GROUP
1031	bool "Utilization clamping per group of tasks"
1032	depends on CGROUP_SCHED
1033	depends on UCLAMP_TASK
1034	default n
1035	help
1036	  This feature enables the scheduler to track the clamped utilization
1037	  of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
1038
1039	  When this option is enabled, the user can specify a min and max
1040	  CPU bandwidth which is allowed for each single task in a group.
1041	  The max bandwidth allows to clamp the maximum frequency a task
1042	  can use, while the min bandwidth allows to define a minimum
1043	  frequency a task will always use.
1044
1045	  When task group based utilization clamping is enabled, an eventually
1046	  specified task-specific clamp value is constrained by the cgroup
1047	  specified clamp value. Both minimum and maximum task clamping cannot
1048	  be bigger than the corresponding clamping defined at task group level.
1049
1050	  If in doubt, say N.
1051
1052config CGROUP_PIDS
1053	bool "PIDs controller"
1054	help
1055	  Provides enforcement of process number limits in the scope of a
1056	  cgroup. Any attempt to fork more processes than is allowed in the
1057	  cgroup will fail. PIDs are fundamentally a global resource because it
1058	  is fairly trivial to reach PID exhaustion before you reach even a
1059	  conservative kmemcg limit. As a result, it is possible to grind a
1060	  system to halt without being limited by other cgroup policies. The
1061	  PIDs controller is designed to stop this from happening.
1062
1063	  It should be noted that organisational operations (such as attaching
1064	  to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
1065	  since the PIDs limit only affects a process's ability to fork, not to
1066	  attach to a cgroup.
1067
1068config CGROUP_RDMA
1069	bool "RDMA controller"
1070	help
1071	  Provides enforcement of RDMA resources defined by IB stack.
1072	  It is fairly easy for consumers to exhaust RDMA resources, which
1073	  can result into resource unavailability to other consumers.
1074	  RDMA controller is designed to stop this from happening.
1075	  Attaching processes with active RDMA resources to the cgroup
1076	  hierarchy is allowed even if can cross the hierarchy's limit.
1077
1078config CGROUP_FREEZER
1079	bool "Freezer controller"
1080	help
1081	  Provides a way to freeze and unfreeze all tasks in a
1082	  cgroup.
1083
1084	  This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1085	  controller includes important in-kernel memory consumers per default.
1086
1087	  If you're using cgroup2, say N.
1088
1089config CGROUP_HUGETLB
1090	bool "HugeTLB controller"
1091	depends on HUGETLB_PAGE
1092	select PAGE_COUNTER
1093	default n
1094	help
1095	  Provides a cgroup controller for HugeTLB pages.
1096	  When you enable this, you can put a per cgroup limit on HugeTLB usage.
1097	  The limit is enforced during page fault. Since HugeTLB doesn't
1098	  support page reclaim, enforcing the limit at page fault time implies
1099	  that, the application will get SIGBUS signal if it tries to access
1100	  HugeTLB pages beyond its limit. This requires the application to know
1101	  beforehand how much HugeTLB pages it would require for its use. The
1102	  control group is tracked in the third page lru pointer. This means
1103	  that we cannot use the controller with huge page less than 3 pages.
1104
1105config CPUSETS
1106	bool "Cpuset controller"
1107	depends on SMP
1108	help
1109	  This option will let you create and manage CPUSETs which
1110	  allow dynamically partitioning a system into sets of CPUs and
1111	  Memory Nodes and assigning tasks to run only within those sets.
1112	  This is primarily useful on large SMP or NUMA systems.
1113
1114	  Say N if unsure.
1115
1116config PROC_PID_CPUSET
1117	bool "Include legacy /proc/<pid>/cpuset file"
1118	depends on CPUSETS
1119	default y
1120
1121config CGROUP_DEVICE
1122	bool "Device controller"
1123	help
1124	  Provides a cgroup controller implementing whitelists for
1125	  devices which a process in the cgroup can mknod or open.
1126
1127config CGROUP_CPUACCT
1128	bool "Simple CPU accounting controller"
1129	help
1130	  Provides a simple controller for monitoring the
1131	  total CPU consumed by the tasks in a cgroup.
1132
1133config CGROUP_PERF
1134	bool "Perf controller"
1135	depends on PERF_EVENTS
1136	help
1137	  This option extends the perf per-cpu mode to restrict monitoring
1138	  to threads which belong to the cgroup specified and run on the
1139	  designated cpu.  Or this can be used to have cgroup ID in samples
1140	  so that it can monitor performance events among cgroups.
1141
1142	  Say N if unsure.
1143
1144config CGROUP_BPF
1145	bool "Support for eBPF programs attached to cgroups"
1146	depends on BPF_SYSCALL
1147	select SOCK_CGROUP_DATA
1148	help
1149	  Allow attaching eBPF programs to a cgroup using the bpf(2)
1150	  syscall command BPF_PROG_ATTACH.
1151
1152	  In which context these programs are accessed depends on the type
1153	  of attachment. For instance, programs that are attached using
1154	  BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1155	  inet sockets.
1156
1157config CGROUP_MISC
1158	bool "Misc resource controller"
1159	default n
1160	help
1161	  Provides a controller for miscellaneous resources on a host.
1162
1163	  Miscellaneous scalar resources are the resources on the host system
1164	  which cannot be abstracted like the other cgroups. This controller
1165	  tracks and limits the miscellaneous resources used by a process
1166	  attached to a cgroup hierarchy.
1167
1168	  For more information, please check misc cgroup section in
1169	  /Documentation/admin-guide/cgroup-v2.rst.
1170
1171config CGROUP_DEBUG
1172	bool "Debug controller"
1173	default n
1174	depends on DEBUG_KERNEL
1175	help
1176	  This option enables a simple controller that exports
1177	  debugging information about the cgroups framework. This
1178	  controller is for control cgroup debugging only. Its
1179	  interfaces are not stable.
1180
1181	  Say N.
1182
1183config SOCK_CGROUP_DATA
1184	bool
1185	default n
1186
1187endif # CGROUPS
1188
1189menuconfig NAMESPACES
1190	bool "Namespaces support" if EXPERT
1191	depends on MULTIUSER
1192	default !EXPERT
1193	help
1194	  Provides the way to make tasks work with different objects using
1195	  the same id. For example same IPC id may refer to different objects
1196	  or same user id or pid may refer to different tasks when used in
1197	  different namespaces.
1198
1199if NAMESPACES
1200
1201config UTS_NS
1202	bool "UTS namespace"
1203	default y
1204	help
1205	  In this namespace tasks see different info provided with the
1206	  uname() system call
1207
1208config TIME_NS
1209	bool "TIME namespace"
1210	depends on GENERIC_VDSO_TIME_NS
1211	default y
1212	help
1213	  In this namespace boottime and monotonic clocks can be set.
1214	  The time will keep going with the same pace.
1215
1216config IPC_NS
1217	bool "IPC namespace"
1218	depends on (SYSVIPC || POSIX_MQUEUE)
1219	default y
1220	help
1221	  In this namespace tasks work with IPC ids which correspond to
1222	  different IPC objects in different namespaces.
1223
1224config USER_NS
1225	bool "User namespace"
1226	default n
1227	help
1228	  This allows containers, i.e. vservers, to use user namespaces
1229	  to provide different user info for different servers.
1230
1231	  When user namespaces are enabled in the kernel it is
1232	  recommended that the MEMCG option also be enabled and that
1233	  user-space use the memory control groups to limit the amount
1234	  of memory a memory unprivileged users can use.
1235
1236	  If unsure, say N.
1237
1238config PID_NS
1239	bool "PID Namespaces"
1240	default y
1241	help
1242	  Support process id namespaces.  This allows having multiple
1243	  processes with the same pid as long as they are in different
1244	  pid namespaces.  This is a building block of containers.
1245
1246config NET_NS
1247	bool "Network namespace"
1248	depends on NET
1249	default y
1250	help
1251	  Allow user space to create what appear to be multiple instances
1252	  of the network stack.
1253
1254endif # NAMESPACES
1255
1256config CHECKPOINT_RESTORE
1257	bool "Checkpoint/restore support"
1258	select PROC_CHILDREN
1259	select KCMP
1260	default n
1261	help
1262	  Enables additional kernel features in a sake of checkpoint/restore.
1263	  In particular it adds auxiliary prctl codes to setup process text,
1264	  data and heap segment sizes, and a few additional /proc filesystem
1265	  entries.
1266
1267	  If unsure, say N here.
1268
1269config SCHED_AUTOGROUP
1270	bool "Automatic process group scheduling"
1271	select CGROUPS
1272	select CGROUP_SCHED
1273	select FAIR_GROUP_SCHED
1274	help
1275	  This option optimizes the scheduler for common desktop workloads by
1276	  automatically creating and populating task groups.  This separation
1277	  of workloads isolates aggressive CPU burners (like build jobs) from
1278	  desktop applications.  Task group autogeneration is currently based
1279	  upon task session.
1280
1281config SYSFS_DEPRECATED
1282	bool "Enable deprecated sysfs features to support old userspace tools"
1283	depends on SYSFS
1284	default n
1285	help
1286	  This option adds code that switches the layout of the "block" class
1287	  devices, to not show up in /sys/class/block/, but only in
1288	  /sys/block/.
1289
1290	  This switch is only active when the sysfs.deprecated=1 boot option is
1291	  passed or the SYSFS_DEPRECATED_V2 option is set.
1292
1293	  This option allows new kernels to run on old distributions and tools,
1294	  which might get confused by /sys/class/block/. Since 2007/2008 all
1295	  major distributions and tools handle this just fine.
1296
1297	  Recent distributions and userspace tools after 2009/2010 depend on
1298	  the existence of /sys/class/block/, and will not work with this
1299	  option enabled.
1300
1301	  Only if you are using a new kernel on an old distribution, you might
1302	  need to say Y here.
1303
1304config SYSFS_DEPRECATED_V2
1305	bool "Enable deprecated sysfs features by default"
1306	default n
1307	depends on SYSFS
1308	depends on SYSFS_DEPRECATED
1309	help
1310	  Enable deprecated sysfs by default.
1311
1312	  See the CONFIG_SYSFS_DEPRECATED option for more details about this
1313	  option.
1314
1315	  Only if you are using a new kernel on an old distribution, you might
1316	  need to say Y here. Even then, odds are you would not need it
1317	  enabled, you can always pass the boot option if absolutely necessary.
1318
1319config RELAY
1320	bool "Kernel->user space relay support (formerly relayfs)"
1321	select IRQ_WORK
1322	help
1323	  This option enables support for relay interface support in
1324	  certain file systems (such as debugfs).
1325	  It is designed to provide an efficient mechanism for tools and
1326	  facilities to relay large amounts of data from kernel space to
1327	  user space.
1328
1329	  If unsure, say N.
1330
1331config BLK_DEV_INITRD
1332	bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1333	help
1334	  The initial RAM filesystem is a ramfs which is loaded by the
1335	  boot loader (loadlin or lilo) and that is mounted as root
1336	  before the normal boot procedure. It is typically used to
1337	  load modules needed to mount the "real" root file system,
1338	  etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1339
1340	  If RAM disk support (BLK_DEV_RAM) is also included, this
1341	  also enables initial RAM disk (initrd) support and adds
1342	  15 Kbytes (more on some other architectures) to the kernel size.
1343
1344	  If unsure say Y.
1345
1346if BLK_DEV_INITRD
1347
1348source "usr/Kconfig"
1349
1350endif
1351
1352config BOOT_CONFIG
1353	bool "Boot config support"
1354	select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED
1355	help
1356	  Extra boot config allows system admin to pass a config file as
1357	  complemental extension of kernel cmdline when booting.
1358	  The boot config file must be attached at the end of initramfs
1359	  with checksum, size and magic word.
1360	  See <file:Documentation/admin-guide/bootconfig.rst> for details.
1361
1362	  If unsure, say Y.
1363
1364config BOOT_CONFIG_EMBED
1365	bool "Embed bootconfig file in the kernel"
1366	depends on BOOT_CONFIG
1367	help
1368	  Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the
1369	  kernel. Usually, the bootconfig file is loaded with the initrd
1370	  image. But if the system doesn't support initrd, this option will
1371	  help you by embedding a bootconfig file while building the kernel.
1372
1373	  If unsure, say N.
1374
1375config BOOT_CONFIG_EMBED_FILE
1376	string "Embedded bootconfig file path"
1377	depends on BOOT_CONFIG_EMBED
1378	help
1379	  Specify a bootconfig file which will be embedded to the kernel.
1380	  This bootconfig will be used if there is no initrd or no other
1381	  bootconfig in the initrd.
1382
1383config INITRAMFS_PRESERVE_MTIME
1384	bool "Preserve cpio archive mtimes in initramfs"
1385	default y
1386	help
1387	  Each entry in an initramfs cpio archive carries an mtime value. When
1388	  enabled, extracted cpio items take this mtime, with directory mtime
1389	  setting deferred until after creation of any child entries.
1390
1391	  If unsure, say Y.
1392
1393choice
1394	prompt "Compiler optimization level"
1395	default CC_OPTIMIZE_FOR_PERFORMANCE
1396
1397config CC_OPTIMIZE_FOR_PERFORMANCE
1398	bool "Optimize for performance (-O2)"
1399	help
1400	  This is the default optimization level for the kernel, building
1401	  with the "-O2" compiler flag for best performance and most
1402	  helpful compile-time warnings.
1403
1404config CC_OPTIMIZE_FOR_PERFORMANCE_O3
1405	bool "Optimize more for performance (-O3)"
1406	depends on ARC
1407	help
1408	  Choosing this option will pass "-O3" to your compiler to optimize
1409	  the kernel yet more for performance.
1410
1411config CC_OPTIMIZE_FOR_SIZE
1412	bool "Optimize for size (-Os)"
1413	help
1414	  Choosing this option will pass "-Os" to your compiler resulting
1415	  in a smaller kernel.
1416
1417endchoice
1418
1419config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1420	bool
1421	help
1422	  This requires that the arch annotates or otherwise protects
1423	  its external entry points from being discarded. Linker scripts
1424	  must also merge .text.*, .data.*, and .bss.* correctly into
1425	  output sections. Care must be taken not to pull in unrelated
1426	  sections (e.g., '.text.init'). Typically '.' in section names
1427	  is used to distinguish them from label names / C identifiers.
1428
1429config LD_DEAD_CODE_DATA_ELIMINATION
1430	bool "Dead code and data elimination (EXPERIMENTAL)"
1431	depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1432	depends on EXPERT
1433	depends on $(cc-option,-ffunction-sections -fdata-sections)
1434	depends on $(ld-option,--gc-sections)
1435	help
1436	  Enable this if you want to do dead code and data elimination with
1437	  the linker by compiling with -ffunction-sections -fdata-sections,
1438	  and linking with --gc-sections.
1439
1440	  This can reduce on disk and in-memory size of the kernel
1441	  code and static data, particularly for small configs and
1442	  on small systems. This has the possibility of introducing
1443	  silently broken kernel if the required annotations are not
1444	  present. This option is not well tested yet, so use at your
1445	  own risk.
1446
1447config LD_ORPHAN_WARN
1448	def_bool y
1449	depends on ARCH_WANT_LD_ORPHAN_WARN
1450	depends on $(ld-option,--orphan-handling=warn)
1451
1452config SYSCTL
1453	bool
1454
1455config HAVE_UID16
1456	bool
1457
1458config SYSCTL_EXCEPTION_TRACE
1459	bool
1460	help
1461	  Enable support for /proc/sys/debug/exception-trace.
1462
1463config SYSCTL_ARCH_UNALIGN_NO_WARN
1464	bool
1465	help
1466	  Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1467	  Allows arch to define/use @no_unaligned_warning to possibly warn
1468	  about unaligned access emulation going on under the hood.
1469
1470config SYSCTL_ARCH_UNALIGN_ALLOW
1471	bool
1472	help
1473	  Enable support for /proc/sys/kernel/unaligned-trap
1474	  Allows arches to define/use @unaligned_enabled to runtime toggle
1475	  the unaligned access emulation.
1476	  see arch/parisc/kernel/unaligned.c for reference
1477
1478config HAVE_PCSPKR_PLATFORM
1479	bool
1480
1481# interpreter that classic socket filters depend on
1482config BPF
1483	bool
1484
1485menuconfig EXPERT
1486	bool "Configure standard kernel features (expert users)"
1487	# Unhide debug options, to make the on-by-default options visible
1488	select DEBUG_KERNEL
1489	help
1490	  This option allows certain base kernel options and settings
1491	  to be disabled or tweaked. This is for specialized
1492	  environments which can tolerate a "non-standard" kernel.
1493	  Only use this if you really know what you are doing.
1494
1495config UID16
1496	bool "Enable 16-bit UID system calls" if EXPERT
1497	depends on HAVE_UID16 && MULTIUSER
1498	default y
1499	help
1500	  This enables the legacy 16-bit UID syscall wrappers.
1501
1502config MULTIUSER
1503	bool "Multiple users, groups and capabilities support" if EXPERT
1504	default y
1505	help
1506	  This option enables support for non-root users, groups and
1507	  capabilities.
1508
1509	  If you say N here, all processes will run with UID 0, GID 0, and all
1510	  possible capabilities.  Saying N here also compiles out support for
1511	  system calls related to UIDs, GIDs, and capabilities, such as setuid,
1512	  setgid, and capset.
1513
1514	  If unsure, say Y here.
1515
1516config SGETMASK_SYSCALL
1517	bool "sgetmask/ssetmask syscalls support" if EXPERT
1518	def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1519	help
1520	  sys_sgetmask and sys_ssetmask are obsolete system calls
1521	  no longer supported in libc but still enabled by default in some
1522	  architectures.
1523
1524	  If unsure, leave the default option here.
1525
1526config SYSFS_SYSCALL
1527	bool "Sysfs syscall support" if EXPERT
1528	default y
1529	help
1530	  sys_sysfs is an obsolete system call no longer supported in libc.
1531	  Note that disabling this option is more secure but might break
1532	  compatibility with some systems.
1533
1534	  If unsure say Y here.
1535
1536config FHANDLE
1537	bool "open by fhandle syscalls" if EXPERT
1538	select EXPORTFS
1539	default y
1540	help
1541	  If you say Y here, a user level program will be able to map
1542	  file names to handle and then later use the handle for
1543	  different file system operations. This is useful in implementing
1544	  userspace file servers, which now track files using handles instead
1545	  of names. The handle would remain the same even if file names
1546	  get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1547	  syscalls.
1548
1549config POSIX_TIMERS
1550	bool "Posix Clocks & timers" if EXPERT
1551	default y
1552	help
1553	  This includes native support for POSIX timers to the kernel.
1554	  Some embedded systems have no use for them and therefore they
1555	  can be configured out to reduce the size of the kernel image.
1556
1557	  When this option is disabled, the following syscalls won't be
1558	  available: timer_create, timer_gettime: timer_getoverrun,
1559	  timer_settime, timer_delete, clock_adjtime, getitimer,
1560	  setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1561	  clock_getres and clock_nanosleep syscalls will be limited to
1562	  CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1563
1564	  If unsure say y.
1565
1566config PRINTK
1567	default y
1568	bool "Enable support for printk" if EXPERT
1569	select IRQ_WORK
1570	help
1571	  This option enables normal printk support. Removing it
1572	  eliminates most of the message strings from the kernel image
1573	  and makes the kernel more or less silent. As this makes it
1574	  very difficult to diagnose system problems, saying N here is
1575	  strongly discouraged.
1576
1577config BUG
1578	bool "BUG() support" if EXPERT
1579	default y
1580	help
1581	  Disabling this option eliminates support for BUG and WARN, reducing
1582	  the size of your kernel image and potentially quietly ignoring
1583	  numerous fatal conditions. You should only consider disabling this
1584	  option for embedded systems with no facilities for reporting errors.
1585	  Just say Y.
1586
1587config ELF_CORE
1588	depends on COREDUMP
1589	default y
1590	bool "Enable ELF core dumps" if EXPERT
1591	help
1592	  Enable support for generating core dumps. Disabling saves about 4k.
1593
1594
1595config PCSPKR_PLATFORM
1596	bool "Enable PC-Speaker support" if EXPERT
1597	depends on HAVE_PCSPKR_PLATFORM
1598	select I8253_LOCK
1599	default y
1600	help
1601	  This option allows to disable the internal PC-Speaker
1602	  support, saving some memory.
1603
1604config BASE_FULL
1605	default y
1606	bool "Enable full-sized data structures for core" if EXPERT
1607	help
1608	  Disabling this option reduces the size of miscellaneous core
1609	  kernel data structures. This saves memory on small machines,
1610	  but may reduce performance.
1611
1612config FUTEX
1613	bool "Enable futex support" if EXPERT
1614	depends on !(SPARC32 && SMP)
1615	default y
1616	imply RT_MUTEXES
1617	help
1618	  Disabling this option will cause the kernel to be built without
1619	  support for "fast userspace mutexes".  The resulting kernel may not
1620	  run glibc-based applications correctly.
1621
1622config FUTEX_PI
1623	bool
1624	depends on FUTEX && RT_MUTEXES
1625	default y
1626
1627config EPOLL
1628	bool "Enable eventpoll support" if EXPERT
1629	default y
1630	help
1631	  Disabling this option will cause the kernel to be built without
1632	  support for epoll family of system calls.
1633
1634config SIGNALFD
1635	bool "Enable signalfd() system call" if EXPERT
1636	default y
1637	help
1638	  Enable the signalfd() system call that allows to receive signals
1639	  on a file descriptor.
1640
1641	  If unsure, say Y.
1642
1643config TIMERFD
1644	bool "Enable timerfd() system call" if EXPERT
1645	default y
1646	help
1647	  Enable the timerfd() system call that allows to receive timer
1648	  events on a file descriptor.
1649
1650	  If unsure, say Y.
1651
1652config EVENTFD
1653	bool "Enable eventfd() system call" if EXPERT
1654	default y
1655	help
1656	  Enable the eventfd() system call that allows to receive both
1657	  kernel notification (ie. KAIO) or userspace notifications.
1658
1659	  If unsure, say Y.
1660
1661config SHMEM
1662	bool "Use full shmem filesystem" if EXPERT
1663	default y
1664	depends on MMU
1665	help
1666	  The shmem is an internal filesystem used to manage shared memory.
1667	  It is backed by swap and manages resource limits. It is also exported
1668	  to userspace as tmpfs if TMPFS is enabled. Disabling this
1669	  option replaces shmem and tmpfs with the much simpler ramfs code,
1670	  which may be appropriate on small systems without swap.
1671
1672config AIO
1673	bool "Enable AIO support" if EXPERT
1674	default y
1675	help
1676	  This option enables POSIX asynchronous I/O which may by used
1677	  by some high performance threaded applications. Disabling
1678	  this option saves about 7k.
1679
1680config IO_URING
1681	bool "Enable IO uring support" if EXPERT
1682	select IO_WQ
1683	default y
1684	help
1685	  This option enables support for the io_uring interface, enabling
1686	  applications to submit and complete IO through submission and
1687	  completion rings that are shared between the kernel and application.
1688
1689config ADVISE_SYSCALLS
1690	bool "Enable madvise/fadvise syscalls" if EXPERT
1691	default y
1692	help
1693	  This option enables the madvise and fadvise syscalls, used by
1694	  applications to advise the kernel about their future memory or file
1695	  usage, improving performance. If building an embedded system where no
1696	  applications use these syscalls, you can disable this option to save
1697	  space.
1698
1699config MEMBARRIER
1700	bool "Enable membarrier() system call" if EXPERT
1701	default y
1702	help
1703	  Enable the membarrier() system call that allows issuing memory
1704	  barriers across all running threads, which can be used to distribute
1705	  the cost of user-space memory barriers asymmetrically by transforming
1706	  pairs of memory barriers into pairs consisting of membarrier() and a
1707	  compiler barrier.
1708
1709	  If unsure, say Y.
1710
1711config KALLSYMS
1712	bool "Load all symbols for debugging/ksymoops" if EXPERT
1713	default y
1714	help
1715	  Say Y here to let the kernel print out symbolic crash information and
1716	  symbolic stack backtraces. This increases the size of the kernel
1717	  somewhat, as all symbols have to be loaded into the kernel image.
1718
1719config KALLSYMS_ALL
1720	bool "Include all symbols in kallsyms"
1721	depends on DEBUG_KERNEL && KALLSYMS
1722	help
1723	  Normally kallsyms only contains the symbols of functions for nicer
1724	  OOPS messages and backtraces (i.e., symbols from the text and inittext
1725	  sections). This is sufficient for most cases. And only in very rare
1726	  cases (e.g., when a debugger is used) all symbols are required (e.g.,
1727	  names of variables from the data sections, etc).
1728
1729	  This option makes sure that all symbols are loaded into the kernel
1730	  image (i.e., symbols from all sections) in cost of increased kernel
1731	  size (depending on the kernel configuration, it may be 300KiB or
1732	  something like this).
1733
1734	  Say N unless you really need all symbols.
1735
1736config KALLSYMS_ABSOLUTE_PERCPU
1737	bool
1738	depends on KALLSYMS
1739	default X86_64 && SMP
1740
1741config KALLSYMS_BASE_RELATIVE
1742	bool
1743	depends on KALLSYMS
1744	default !IA64
1745	help
1746	  Instead of emitting them as absolute values in the native word size,
1747	  emit the symbol references in the kallsyms table as 32-bit entries,
1748	  each containing a relative value in the range [base, base + U32_MAX]
1749	  or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1750	  an absolute value in the range [0, S32_MAX] or a relative value in the
1751	  range [base, base + S32_MAX], where base is the lowest relative symbol
1752	  address encountered in the image.
1753
1754	  On 64-bit builds, this reduces the size of the address table by 50%,
1755	  but more importantly, it results in entries whose values are build
1756	  time constants, and no relocation pass is required at runtime to fix
1757	  up the entries based on the runtime load address of the kernel.
1758
1759# end of the "standard kernel features (expert users)" menu
1760
1761# syscall, maps, verifier
1762
1763config ARCH_HAS_MEMBARRIER_CALLBACKS
1764	bool
1765
1766config ARCH_HAS_MEMBARRIER_SYNC_CORE
1767	bool
1768
1769config KCMP
1770	bool "Enable kcmp() system call" if EXPERT
1771	help
1772	  Enable the kernel resource comparison system call. It provides
1773	  user-space with the ability to compare two processes to see if they
1774	  share a common resource, such as a file descriptor or even virtual
1775	  memory space.
1776
1777	  If unsure, say N.
1778
1779config RSEQ
1780	bool "Enable rseq() system call" if EXPERT
1781	default y
1782	depends on HAVE_RSEQ
1783	select MEMBARRIER
1784	help
1785	  Enable the restartable sequences system call. It provides a
1786	  user-space cache for the current CPU number value, which
1787	  speeds up getting the current CPU number from user-space,
1788	  as well as an ABI to speed up user-space operations on
1789	  per-CPU data.
1790
1791	  If unsure, say Y.
1792
1793config DEBUG_RSEQ
1794	default n
1795	bool "Enabled debugging of rseq() system call" if EXPERT
1796	depends on RSEQ && DEBUG_KERNEL
1797	help
1798	  Enable extra debugging checks for the rseq system call.
1799
1800	  If unsure, say N.
1801
1802config EMBEDDED
1803	bool "Embedded system"
1804	select EXPERT
1805	help
1806	  This option should be enabled if compiling the kernel for
1807	  an embedded system so certain expert options are available
1808	  for configuration.
1809
1810config HAVE_PERF_EVENTS
1811	bool
1812	help
1813	  See tools/perf/design.txt for details.
1814
1815config GUEST_PERF_EVENTS
1816	bool
1817	depends on HAVE_PERF_EVENTS
1818
1819config PERF_USE_VMALLOC
1820	bool
1821	help
1822	  See tools/perf/design.txt for details
1823
1824config PC104
1825	bool "PC/104 support" if EXPERT
1826	help
1827	  Expose PC/104 form factor device drivers and options available for
1828	  selection and configuration. Enable this option if your target
1829	  machine has a PC/104 bus.
1830
1831menu "Kernel Performance Events And Counters"
1832
1833config PERF_EVENTS
1834	bool "Kernel performance events and counters"
1835	default y if PROFILING
1836	depends on HAVE_PERF_EVENTS
1837	select IRQ_WORK
1838	select SRCU
1839	help
1840	  Enable kernel support for various performance events provided
1841	  by software and hardware.
1842
1843	  Software events are supported either built-in or via the
1844	  use of generic tracepoints.
1845
1846	  Most modern CPUs support performance events via performance
1847	  counter registers. These registers count the number of certain
1848	  types of hw events: such as instructions executed, cachemisses
1849	  suffered, or branches mis-predicted - without slowing down the
1850	  kernel or applications. These registers can also trigger interrupts
1851	  when a threshold number of events have passed - and can thus be
1852	  used to profile the code that runs on that CPU.
1853
1854	  The Linux Performance Event subsystem provides an abstraction of
1855	  these software and hardware event capabilities, available via a
1856	  system call and used by the "perf" utility in tools/perf/. It
1857	  provides per task and per CPU counters, and it provides event
1858	  capabilities on top of those.
1859
1860	  Say Y if unsure.
1861
1862config DEBUG_PERF_USE_VMALLOC
1863	default n
1864	bool "Debug: use vmalloc to back perf mmap() buffers"
1865	depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1866	select PERF_USE_VMALLOC
1867	help
1868	  Use vmalloc memory to back perf mmap() buffers.
1869
1870	  Mostly useful for debugging the vmalloc code on platforms
1871	  that don't require it.
1872
1873	  Say N if unsure.
1874
1875endmenu
1876
1877config SYSTEM_DATA_VERIFICATION
1878	def_bool n
1879	select SYSTEM_TRUSTED_KEYRING
1880	select KEYS
1881	select CRYPTO
1882	select CRYPTO_RSA
1883	select ASYMMETRIC_KEY_TYPE
1884	select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1885	select ASN1
1886	select OID_REGISTRY
1887	select X509_CERTIFICATE_PARSER
1888	select PKCS7_MESSAGE_PARSER
1889	help
1890	  Provide PKCS#7 message verification using the contents of the system
1891	  trusted keyring to provide public keys.  This then can be used for
1892	  module verification, kexec image verification and firmware blob
1893	  verification.
1894
1895config PROFILING
1896	bool "Profiling support"
1897	help
1898	  Say Y here to enable the extended profiling support mechanisms used
1899	  by profilers.
1900
1901#
1902# Place an empty function call at each tracepoint site. Can be
1903# dynamically changed for a probe function.
1904#
1905config TRACEPOINTS
1906	bool
1907
1908endmenu		# General setup
1909
1910source "arch/Kconfig"
1911
1912config RT_MUTEXES
1913	bool
1914	default y if PREEMPT_RT
1915
1916config BASE_SMALL
1917	int
1918	default 0 if BASE_FULL
1919	default 1 if !BASE_FULL
1920
1921config MODULE_SIG_FORMAT
1922	def_bool n
1923	select SYSTEM_DATA_VERIFICATION
1924
1925menuconfig MODULES
1926	bool "Enable loadable module support"
1927	modules
1928	help
1929	  Kernel modules are small pieces of compiled code which can
1930	  be inserted in the running kernel, rather than being
1931	  permanently built into the kernel.  You use the "modprobe"
1932	  tool to add (and sometimes remove) them.  If you say Y here,
1933	  many parts of the kernel can be built as modules (by
1934	  answering M instead of Y where indicated): this is most
1935	  useful for infrequently used options which are not required
1936	  for booting.  For more information, see the man pages for
1937	  modprobe, lsmod, modinfo, insmod and rmmod.
1938
1939	  If you say Y here, you will need to run "make
1940	  modules_install" to put the modules under /lib/modules/
1941	  where modprobe can find them (you may need to be root to do
1942	  this).
1943
1944	  If unsure, say Y.
1945
1946if MODULES
1947
1948config MODULE_FORCE_LOAD
1949	bool "Forced module loading"
1950	default n
1951	help
1952	  Allow loading of modules without version information (ie. modprobe
1953	  --force).  Forced module loading sets the 'F' (forced) taint flag and
1954	  is usually a really bad idea.
1955
1956config MODULE_UNLOAD
1957	bool "Module unloading"
1958	help
1959	  Without this option you will not be able to unload any
1960	  modules (note that some modules may not be unloadable
1961	  anyway), which makes your kernel smaller, faster
1962	  and simpler.  If unsure, say Y.
1963
1964config MODULE_FORCE_UNLOAD
1965	bool "Forced module unloading"
1966	depends on MODULE_UNLOAD
1967	help
1968	  This option allows you to force a module to unload, even if the
1969	  kernel believes it is unsafe: the kernel will remove the module
1970	  without waiting for anyone to stop using it (using the -f option to
1971	  rmmod).  This is mainly for kernel developers and desperate users.
1972	  If unsure, say N.
1973
1974config MODULE_UNLOAD_TAINT_TRACKING
1975	bool "Tainted module unload tracking"
1976	depends on MODULE_UNLOAD
1977	default n
1978	help
1979	  This option allows you to maintain a record of each unloaded
1980	  module that tainted the kernel. In addition to displaying a
1981	  list of linked (or loaded) modules e.g. on detection of a bad
1982	  page (see bad_page()), the aforementioned details are also
1983	  shown. If unsure, say N.
1984
1985config MODVERSIONS
1986	bool "Module versioning support"
1987	help
1988	  Usually, you have to use modules compiled with your kernel.
1989	  Saying Y here makes it sometimes possible to use modules
1990	  compiled for different kernels, by adding enough information
1991	  to the modules to (hopefully) spot any changes which would
1992	  make them incompatible with the kernel you are running.  If
1993	  unsure, say N.
1994
1995config ASM_MODVERSIONS
1996	bool
1997	default HAVE_ASM_MODVERSIONS && MODVERSIONS
1998	help
1999	  This enables module versioning for exported symbols also from
2000	  assembly. This can be enabled only when the target architecture
2001	  supports it.
2002
2003config MODULE_SRCVERSION_ALL
2004	bool "Source checksum for all modules"
2005	help
2006	  Modules which contain a MODULE_VERSION get an extra "srcversion"
2007	  field inserted into their modinfo section, which contains a
2008    	  sum of the source files which made it.  This helps maintainers
2009	  see exactly which source was used to build a module (since
2010	  others sometimes change the module source without updating
2011	  the version).  With this option, such a "srcversion" field
2012	  will be created for all modules.  If unsure, say N.
2013
2014config MODULE_SIG
2015	bool "Module signature verification"
2016	select MODULE_SIG_FORMAT
2017	help
2018	  Check modules for valid signatures upon load: the signature
2019	  is simply appended to the module. For more information see
2020	  <file:Documentation/admin-guide/module-signing.rst>.
2021
2022	  Note that this option adds the OpenSSL development packages as a
2023	  kernel build dependency so that the signing tool can use its crypto
2024	  library.
2025
2026	  You should enable this option if you wish to use either
2027	  CONFIG_SECURITY_LOCKDOWN_LSM or lockdown functionality imposed via
2028	  another LSM - otherwise unsigned modules will be loadable regardless
2029	  of the lockdown policy.
2030
2031	  !!!WARNING!!!  If you enable this option, you MUST make sure that the
2032	  module DOES NOT get stripped after being signed.  This includes the
2033	  debuginfo strip done by some packagers (such as rpmbuild) and
2034	  inclusion into an initramfs that wants the module size reduced.
2035
2036config MODULE_SIG_FORCE
2037	bool "Require modules to be validly signed"
2038	depends on MODULE_SIG
2039	help
2040	  Reject unsigned modules or signed modules for which we don't have a
2041	  key.  Without this, such modules will simply taint the kernel.
2042
2043config MODULE_SIG_ALL
2044	bool "Automatically sign all modules"
2045	default y
2046	depends on MODULE_SIG || IMA_APPRAISE_MODSIG
2047	help
2048	  Sign all modules during make modules_install. Without this option,
2049	  modules must be signed manually, using the scripts/sign-file tool.
2050
2051comment "Do not forget to sign required modules with scripts/sign-file"
2052	depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
2053
2054choice
2055	prompt "Which hash algorithm should modules be signed with?"
2056	depends on MODULE_SIG || IMA_APPRAISE_MODSIG
2057	help
2058	  This determines which sort of hashing algorithm will be used during
2059	  signature generation.  This algorithm _must_ be built into the kernel
2060	  directly so that signature verification can take place.  It is not
2061	  possible to load a signed module containing the algorithm to check
2062	  the signature on that module.
2063
2064config MODULE_SIG_SHA1
2065	bool "Sign modules with SHA-1"
2066	select CRYPTO_SHA1
2067
2068config MODULE_SIG_SHA224
2069	bool "Sign modules with SHA-224"
2070	select CRYPTO_SHA256
2071
2072config MODULE_SIG_SHA256
2073	bool "Sign modules with SHA-256"
2074	select CRYPTO_SHA256
2075
2076config MODULE_SIG_SHA384
2077	bool "Sign modules with SHA-384"
2078	select CRYPTO_SHA512
2079
2080config MODULE_SIG_SHA512
2081	bool "Sign modules with SHA-512"
2082	select CRYPTO_SHA512
2083
2084endchoice
2085
2086config MODULE_SIG_HASH
2087	string
2088	depends on MODULE_SIG || IMA_APPRAISE_MODSIG
2089	default "sha1" if MODULE_SIG_SHA1
2090	default "sha224" if MODULE_SIG_SHA224
2091	default "sha256" if MODULE_SIG_SHA256
2092	default "sha384" if MODULE_SIG_SHA384
2093	default "sha512" if MODULE_SIG_SHA512
2094
2095choice
2096	prompt "Module compression mode"
2097	help
2098	  This option allows you to choose the algorithm which will be used to
2099	  compress modules when 'make modules_install' is run. (or, you can
2100	  choose to not compress modules at all.)
2101
2102	  External modules will also be compressed in the same way during the
2103	  installation.
2104
2105	  For modules inside an initrd or initramfs, it's more efficient to
2106	  compress the whole initrd or initramfs instead.
2107
2108	  This is fully compatible with signed modules.
2109
2110	  Please note that the tool used to load modules needs to support the
2111	  corresponding algorithm. module-init-tools MAY support gzip, and kmod
2112	  MAY support gzip, xz and zstd.
2113
2114	  Your build system needs to provide the appropriate compression tool
2115	  to compress the modules.
2116
2117	  If in doubt, select 'None'.
2118
2119config MODULE_COMPRESS_NONE
2120	bool "None"
2121	help
2122	  Do not compress modules. The installed modules are suffixed
2123	  with .ko.
2124
2125config MODULE_COMPRESS_GZIP
2126	bool "GZIP"
2127	help
2128	  Compress modules with GZIP. The installed modules are suffixed
2129	  with .ko.gz.
2130
2131config MODULE_COMPRESS_XZ
2132	bool "XZ"
2133	help
2134	  Compress modules with XZ. The installed modules are suffixed
2135	  with .ko.xz.
2136
2137config MODULE_COMPRESS_ZSTD
2138	bool "ZSTD"
2139	help
2140	  Compress modules with ZSTD. The installed modules are suffixed
2141	  with .ko.zst.
2142
2143endchoice
2144
2145config MODULE_DECOMPRESS
2146	bool "Support in-kernel module decompression"
2147	depends on MODULE_COMPRESS_GZIP || MODULE_COMPRESS_XZ
2148	select ZLIB_INFLATE if MODULE_COMPRESS_GZIP
2149	select XZ_DEC if MODULE_COMPRESS_XZ
2150	help
2151
2152	  Support for decompressing kernel modules by the kernel itself
2153	  instead of relying on userspace to perform this task. Useful when
2154	  load pinning security policy is enabled.
2155
2156	  If unsure, say N.
2157
2158config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
2159	bool "Allow loading of modules with missing namespace imports"
2160	help
2161	  Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in
2162	  a namespace. A module that makes use of a symbol exported with such a
2163	  namespace is required to import the namespace via MODULE_IMPORT_NS().
2164	  There is no technical reason to enforce correct namespace imports,
2165	  but it creates consistency between symbols defining namespaces and
2166	  users importing namespaces they make use of. This option relaxes this
2167	  requirement and lifts the enforcement when loading a module.
2168
2169	  If unsure, say N.
2170
2171config MODPROBE_PATH
2172	string "Path to modprobe binary"
2173	default "/sbin/modprobe"
2174	help
2175	  When kernel code requests a module, it does so by calling
2176	  the "modprobe" userspace utility. This option allows you to
2177	  set the path where that binary is found. This can be changed
2178	  at runtime via the sysctl file
2179	  /proc/sys/kernel/modprobe. Setting this to the empty string
2180	  removes the kernel's ability to request modules (but
2181	  userspace can still load modules explicitly).
2182
2183config TRIM_UNUSED_KSYMS
2184	bool "Trim unused exported kernel symbols" if EXPERT
2185	depends on !COMPILE_TEST
2186	help
2187	  The kernel and some modules make many symbols available for
2188	  other modules to use via EXPORT_SYMBOL() and variants. Depending
2189	  on the set of modules being selected in your kernel configuration,
2190	  many of those exported symbols might never be used.
2191
2192	  This option allows for unused exported symbols to be dropped from
2193	  the build. In turn, this provides the compiler more opportunities
2194	  (especially when using LTO) for optimizing the code and reducing
2195	  binary size.  This might have some security advantages as well.
2196
2197	  If unsure, or if you need to build out-of-tree modules, say N.
2198
2199config UNUSED_KSYMS_WHITELIST
2200	string "Whitelist of symbols to keep in ksymtab"
2201	depends on TRIM_UNUSED_KSYMS
2202	help
2203	  By default, all unused exported symbols will be un-exported from the
2204	  build when TRIM_UNUSED_KSYMS is selected.
2205
2206	  UNUSED_KSYMS_WHITELIST allows to whitelist symbols that must be kept
2207	  exported at all times, even in absence of in-tree users. The value to
2208	  set here is the path to a text file containing the list of symbols,
2209	  one per line. The path can be absolute, or relative to the kernel
2210	  source tree.
2211
2212endif # MODULES
2213
2214config MODULES_TREE_LOOKUP
2215	def_bool y
2216	depends on PERF_EVENTS || TRACING || CFI_CLANG
2217
2218config INIT_ALL_POSSIBLE
2219	bool
2220	help
2221	  Back when each arch used to define their own cpu_online_mask and
2222	  cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2223	  with all 1s, and others with all 0s.  When they were centralised,
2224	  it was better to provide this option than to break all the archs
2225	  and have several arch maintainers pursuing me down dark alleys.
2226
2227source "block/Kconfig"
2228
2229config PREEMPT_NOTIFIERS
2230	bool
2231
2232config PADATA
2233	depends on SMP
2234	bool
2235
2236config ASN1
2237	tristate
2238	help
2239	  Build a simple ASN.1 grammar compiler that produces a bytecode output
2240	  that can be interpreted by the ASN.1 stream decoder and used to
2241	  inform it as to what tags are to be expected in a stream and what
2242	  functions to call on what tags.
2243
2244source "kernel/Kconfig.locks"
2245
2246config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
2247	bool
2248
2249config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2250	bool
2251
2252# It may be useful for an architecture to override the definitions of the
2253# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2254# and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2255# different calling convention for syscalls. They can also override the
2256# macros for not-implemented syscalls in kernel/sys_ni.c and
2257# kernel/time/posix-stubs.c. All these overrides need to be available in
2258# <asm/syscall_wrapper.h>.
2259config ARCH_HAS_SYSCALL_WRAPPER
2260	def_bool n
2261