xref: /openbmc/linux/init/Kconfig (revision 84b102f5)
1# SPDX-License-Identifier: GPL-2.0-only
2config DEFCONFIG_LIST
3	string
4	depends on !UML
5	option defconfig_list
6	default "/lib/modules/$(shell,uname -r)/.config"
7	default "/etc/kernel-config"
8	default "/boot/config-$(shell,uname -r)"
9	default "arch/$(SRCARCH)/configs/$(KBUILD_DEFCONFIG)"
10
11config CC_VERSION_TEXT
12	string
13	default "$(CC_VERSION_TEXT)"
14	help
15	  This is used in unclear ways:
16
17	  - Re-run Kconfig when the compiler is updated
18	    The 'default' property references the environment variable,
19	    CC_VERSION_TEXT so it is recorded in include/config/auto.conf.cmd.
20	    When the compiler is updated, Kconfig will be invoked.
21
22	  - Ensure full rebuild when the compier is updated
23	    include/linux/kconfig.h contains this option in the comment line so
24	    fixdep adds include/config/cc/version/text.h into the auto-generated
25	    dependency. When the compiler is updated, syncconfig will touch it
26	    and then every file will be rebuilt.
27
28config CC_IS_GCC
29	def_bool $(success,echo "$(CC_VERSION_TEXT)" | grep -q gcc)
30
31config GCC_VERSION
32	int
33	default $(shell,$(srctree)/scripts/gcc-version.sh $(CC)) if CC_IS_GCC
34	default 0
35
36config LD_VERSION
37	int
38	default $(shell,$(LD) --version | $(srctree)/scripts/ld-version.sh)
39
40config CC_IS_CLANG
41	def_bool $(success,echo "$(CC_VERSION_TEXT)" | grep -q clang)
42
43config LD_IS_LLD
44	def_bool $(success,$(LD) -v | head -n 1 | grep -q LLD)
45
46config CLANG_VERSION
47	int
48	default $(shell,$(srctree)/scripts/clang-version.sh $(CC))
49
50config LLD_VERSION
51	int
52	default $(shell,$(srctree)/scripts/lld-version.sh $(LD))
53
54config CC_CAN_LINK
55	bool
56	default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m64-flag)) if 64BIT
57	default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m32-flag))
58
59config CC_CAN_LINK_STATIC
60	bool
61	default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m64-flag) -static) if 64BIT
62	default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m32-flag) -static)
63
64config CC_HAS_ASM_GOTO
65	def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC))
66
67config CC_HAS_ASM_GOTO_OUTPUT
68	depends on CC_HAS_ASM_GOTO
69	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)
70
71config TOOLS_SUPPORT_RELR
72	def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
73
74config CC_HAS_ASM_INLINE
75	def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
76
77config CONSTRUCTORS
78	bool
79
80config IRQ_WORK
81	bool
82
83config BUILDTIME_TABLE_SORT
84	bool
85
86config THREAD_INFO_IN_TASK
87	bool
88	help
89	  Select this to move thread_info off the stack into task_struct.  To
90	  make this work, an arch will need to remove all thread_info fields
91	  except flags and fix any runtime bugs.
92
93	  One subtle change that will be needed is to use try_get_task_stack()
94	  and put_task_stack() in save_thread_stack_tsk() and get_wchan().
95
96menu "General setup"
97
98config BROKEN
99	bool
100
101config BROKEN_ON_SMP
102	bool
103	depends on BROKEN || !SMP
104	default y
105
106config INIT_ENV_ARG_LIMIT
107	int
108	default 32 if !UML
109	default 128 if UML
110	help
111	  Maximum of each of the number of arguments and environment
112	  variables passed to init from the kernel command line.
113
114config COMPILE_TEST
115	bool "Compile also drivers which will not load"
116	depends on !UML && !S390
117	default n
118	help
119	  Some drivers can be compiled on a different platform than they are
120	  intended to be run on. Despite they cannot be loaded there (or even
121	  when they load they cannot be used due to missing HW support),
122	  developers still, opposing to distributors, might want to build such
123	  drivers to compile-test them.
124
125	  If you are a developer and want to build everything available, say Y
126	  here. If you are a user/distributor, say N here to exclude useless
127	  drivers to be distributed.
128
129config UAPI_HEADER_TEST
130	bool "Compile test UAPI headers"
131	depends on HEADERS_INSTALL && CC_CAN_LINK
132	help
133	  Compile test headers exported to user-space to ensure they are
134	  self-contained, i.e. compilable as standalone units.
135
136	  If you are a developer or tester and want to ensure the exported
137	  headers are self-contained, say Y here. Otherwise, choose N.
138
139config LOCALVERSION
140	string "Local version - append to kernel release"
141	help
142	  Append an extra string to the end of your kernel version.
143	  This will show up when you type uname, for example.
144	  The string you set here will be appended after the contents of
145	  any files with a filename matching localversion* in your
146	  object and source tree, in that order.  Your total string can
147	  be a maximum of 64 characters.
148
149config LOCALVERSION_AUTO
150	bool "Automatically append version information to the version string"
151	default y
152	depends on !COMPILE_TEST
153	help
154	  This will try to automatically determine if the current tree is a
155	  release tree by looking for git tags that belong to the current
156	  top of tree revision.
157
158	  A string of the format -gxxxxxxxx will be added to the localversion
159	  if a git-based tree is found.  The string generated by this will be
160	  appended after any matching localversion* files, and after the value
161	  set in CONFIG_LOCALVERSION.
162
163	  (The actual string used here is the first eight characters produced
164	  by running the command:
165
166	    $ git rev-parse --verify HEAD
167
168	  which is done within the script "scripts/setlocalversion".)
169
170config BUILD_SALT
171	string "Build ID Salt"
172	default ""
173	help
174	  The build ID is used to link binaries and their debug info. Setting
175	  this option will use the value in the calculation of the build id.
176	  This is mostly useful for distributions which want to ensure the
177	  build is unique between builds. It's safe to leave the default.
178
179config HAVE_KERNEL_GZIP
180	bool
181
182config HAVE_KERNEL_BZIP2
183	bool
184
185config HAVE_KERNEL_LZMA
186	bool
187
188config HAVE_KERNEL_XZ
189	bool
190
191config HAVE_KERNEL_LZO
192	bool
193
194config HAVE_KERNEL_LZ4
195	bool
196
197config HAVE_KERNEL_ZSTD
198	bool
199
200config HAVE_KERNEL_UNCOMPRESSED
201	bool
202
203choice
204	prompt "Kernel compression mode"
205	default KERNEL_GZIP
206	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
207	help
208	  The linux kernel is a kind of self-extracting executable.
209	  Several compression algorithms are available, which differ
210	  in efficiency, compression and decompression speed.
211	  Compression speed is only relevant when building a kernel.
212	  Decompression speed is relevant at each boot.
213
214	  If you have any problems with bzip2 or lzma compressed
215	  kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
216	  version of this functionality (bzip2 only), for 2.4, was
217	  supplied by Christian Ludwig)
218
219	  High compression options are mostly useful for users, who
220	  are low on disk space (embedded systems), but for whom ram
221	  size matters less.
222
223	  If in doubt, select 'gzip'
224
225config KERNEL_GZIP
226	bool "Gzip"
227	depends on HAVE_KERNEL_GZIP
228	help
229	  The old and tried gzip compression. It provides a good balance
230	  between compression ratio and decompression speed.
231
232config KERNEL_BZIP2
233	bool "Bzip2"
234	depends on HAVE_KERNEL_BZIP2
235	help
236	  Its compression ratio and speed is intermediate.
237	  Decompression speed is slowest among the choices.  The kernel
238	  size is about 10% smaller with bzip2, in comparison to gzip.
239	  Bzip2 uses a large amount of memory. For modern kernels you
240	  will need at least 8MB RAM or more for booting.
241
242config KERNEL_LZMA
243	bool "LZMA"
244	depends on HAVE_KERNEL_LZMA
245	help
246	  This compression algorithm's ratio is best.  Decompression speed
247	  is between gzip and bzip2.  Compression is slowest.
248	  The kernel size is about 33% smaller with LZMA in comparison to gzip.
249
250config KERNEL_XZ
251	bool "XZ"
252	depends on HAVE_KERNEL_XZ
253	help
254	  XZ uses the LZMA2 algorithm and instruction set specific
255	  BCJ filters which can improve compression ratio of executable
256	  code. The size of the kernel is about 30% smaller with XZ in
257	  comparison to gzip. On architectures for which there is a BCJ
258	  filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
259	  will create a few percent smaller kernel than plain LZMA.
260
261	  The speed is about the same as with LZMA: The decompression
262	  speed of XZ is better than that of bzip2 but worse than gzip
263	  and LZO. Compression is slow.
264
265config KERNEL_LZO
266	bool "LZO"
267	depends on HAVE_KERNEL_LZO
268	help
269	  Its compression ratio is the poorest among the choices. The kernel
270	  size is about 10% bigger than gzip; however its speed
271	  (both compression and decompression) is the fastest.
272
273config KERNEL_LZ4
274	bool "LZ4"
275	depends on HAVE_KERNEL_LZ4
276	help
277	  LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
278	  A preliminary version of LZ4 de/compression tool is available at
279	  <https://code.google.com/p/lz4/>.
280
281	  Its compression ratio is worse than LZO. The size of the kernel
282	  is about 8% bigger than LZO. But the decompression speed is
283	  faster than LZO.
284
285config KERNEL_ZSTD
286	bool "ZSTD"
287	depends on HAVE_KERNEL_ZSTD
288	help
289	  ZSTD is a compression algorithm targeting intermediate compression
290	  with fast decompression speed. It will compress better than GZIP and
291	  decompress around the same speed as LZO, but slower than LZ4. You
292	  will need at least 192 KB RAM or more for booting. The zstd command
293	  line tool is required for compression.
294
295config KERNEL_UNCOMPRESSED
296	bool "None"
297	depends on HAVE_KERNEL_UNCOMPRESSED
298	help
299	  Produce uncompressed kernel image. This option is usually not what
300	  you want. It is useful for debugging the kernel in slow simulation
301	  environments, where decompressing and moving the kernel is awfully
302	  slow. This option allows early boot code to skip the decompressor
303	  and jump right at uncompressed kernel image.
304
305endchoice
306
307config DEFAULT_INIT
308	string "Default init path"
309	default ""
310	help
311	  This option determines the default init for the system if no init=
312	  option is passed on the kernel command line. If the requested path is
313	  not present, we will still then move on to attempting further
314	  locations (e.g. /sbin/init, etc). If this is empty, we will just use
315	  the fallback list when init= is not passed.
316
317config DEFAULT_HOSTNAME
318	string "Default hostname"
319	default "(none)"
320	help
321	  This option determines the default system hostname before userspace
322	  calls sethostname(2). The kernel traditionally uses "(none)" here,
323	  but you may wish to use a different default here to make a minimal
324	  system more usable with less configuration.
325
326#
327# For some reason microblaze and nios2 hard code SWAP=n.  Hopefully we can
328# add proper SWAP support to them, in which case this can be remove.
329#
330config ARCH_NO_SWAP
331	bool
332
333config SWAP
334	bool "Support for paging of anonymous memory (swap)"
335	depends on MMU && BLOCK && !ARCH_NO_SWAP
336	default y
337	help
338	  This option allows you to choose whether you want to have support
339	  for so called swap devices or swap files in your kernel that are
340	  used to provide more virtual memory than the actual RAM present
341	  in your computer.  If unsure say Y.
342
343config SYSVIPC
344	bool "System V IPC"
345	help
346	  Inter Process Communication is a suite of library functions and
347	  system calls which let processes (running programs) synchronize and
348	  exchange information. It is generally considered to be a good thing,
349	  and some programs won't run unless you say Y here. In particular, if
350	  you want to run the DOS emulator dosemu under Linux (read the
351	  DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
352	  you'll need to say Y here.
353
354	  You can find documentation about IPC with "info ipc" and also in
355	  section 6.4 of the Linux Programmer's Guide, available from
356	  <http://www.tldp.org/guides.html>.
357
358config SYSVIPC_SYSCTL
359	bool
360	depends on SYSVIPC
361	depends on SYSCTL
362	default y
363
364config POSIX_MQUEUE
365	bool "POSIX Message Queues"
366	depends on NET
367	help
368	  POSIX variant of message queues is a part of IPC. In POSIX message
369	  queues every message has a priority which decides about succession
370	  of receiving it by a process. If you want to compile and run
371	  programs written e.g. for Solaris with use of its POSIX message
372	  queues (functions mq_*) say Y here.
373
374	  POSIX message queues are visible as a filesystem called 'mqueue'
375	  and can be mounted somewhere if you want to do filesystem
376	  operations on message queues.
377
378	  If unsure, say Y.
379
380config POSIX_MQUEUE_SYSCTL
381	bool
382	depends on POSIX_MQUEUE
383	depends on SYSCTL
384	default y
385
386config WATCH_QUEUE
387	bool "General notification queue"
388	default n
389	help
390
391	  This is a general notification queue for the kernel to pass events to
392	  userspace by splicing them into pipes.  It can be used in conjunction
393	  with watches for key/keyring change notifications and device
394	  notifications.
395
396	  See Documentation/watch_queue.rst
397
398config CROSS_MEMORY_ATTACH
399	bool "Enable process_vm_readv/writev syscalls"
400	depends on MMU
401	default y
402	help
403	  Enabling this option adds the system calls process_vm_readv and
404	  process_vm_writev which allow a process with the correct privileges
405	  to directly read from or write to another process' address space.
406	  See the man page for more details.
407
408config USELIB
409	bool "uselib syscall"
410	def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
411	help
412	  This option enables the uselib syscall, a system call used in the
413	  dynamic linker from libc5 and earlier.  glibc does not use this
414	  system call.  If you intend to run programs built on libc5 or
415	  earlier, you may need to enable this syscall.  Current systems
416	  running glibc can safely disable this.
417
418config AUDIT
419	bool "Auditing support"
420	depends on NET
421	help
422	  Enable auditing infrastructure that can be used with another
423	  kernel subsystem, such as SELinux (which requires this for
424	  logging of avc messages output).  System call auditing is included
425	  on architectures which support it.
426
427config HAVE_ARCH_AUDITSYSCALL
428	bool
429
430config AUDITSYSCALL
431	def_bool y
432	depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
433	select FSNOTIFY
434
435source "kernel/irq/Kconfig"
436source "kernel/time/Kconfig"
437source "kernel/Kconfig.preempt"
438
439menu "CPU/Task time and stats accounting"
440
441config VIRT_CPU_ACCOUNTING
442	bool
443
444choice
445	prompt "Cputime accounting"
446	default TICK_CPU_ACCOUNTING if !PPC64
447	default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
448
449# Kind of a stub config for the pure tick based cputime accounting
450config TICK_CPU_ACCOUNTING
451	bool "Simple tick based cputime accounting"
452	depends on !S390 && !NO_HZ_FULL
453	help
454	  This is the basic tick based cputime accounting that maintains
455	  statistics about user, system and idle time spent on per jiffies
456	  granularity.
457
458	  If unsure, say Y.
459
460config VIRT_CPU_ACCOUNTING_NATIVE
461	bool "Deterministic task and CPU time accounting"
462	depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
463	select VIRT_CPU_ACCOUNTING
464	help
465	  Select this option to enable more accurate task and CPU time
466	  accounting.  This is done by reading a CPU counter on each
467	  kernel entry and exit and on transitions within the kernel
468	  between system, softirq and hardirq state, so there is a
469	  small performance impact.  In the case of s390 or IBM POWER > 5,
470	  this also enables accounting of stolen time on logically-partitioned
471	  systems.
472
473config VIRT_CPU_ACCOUNTING_GEN
474	bool "Full dynticks CPU time accounting"
475	depends on HAVE_CONTEXT_TRACKING
476	depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
477	depends on GENERIC_CLOCKEVENTS
478	select VIRT_CPU_ACCOUNTING
479	select CONTEXT_TRACKING
480	help
481	  Select this option to enable task and CPU time accounting on full
482	  dynticks systems. This accounting is implemented by watching every
483	  kernel-user boundaries using the context tracking subsystem.
484	  The accounting is thus performed at the expense of some significant
485	  overhead.
486
487	  For now this is only useful if you are working on the full
488	  dynticks subsystem development.
489
490	  If unsure, say N.
491
492endchoice
493
494config IRQ_TIME_ACCOUNTING
495	bool "Fine granularity task level IRQ time accounting"
496	depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
497	help
498	  Select this option to enable fine granularity task irq time
499	  accounting. This is done by reading a timestamp on each
500	  transitions between softirq and hardirq state, so there can be a
501	  small performance impact.
502
503	  If in doubt, say N here.
504
505config HAVE_SCHED_AVG_IRQ
506	def_bool y
507	depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
508	depends on SMP
509
510config SCHED_THERMAL_PRESSURE
511	bool
512	default y if ARM && ARM_CPU_TOPOLOGY
513	default y if ARM64
514	depends on SMP
515	depends on CPU_FREQ_THERMAL
516	help
517	  Select this option to enable thermal pressure accounting in the
518	  scheduler. Thermal pressure is the value conveyed to the scheduler
519	  that reflects the reduction in CPU compute capacity resulted from
520	  thermal throttling. Thermal throttling occurs when the performance of
521	  a CPU is capped due to high operating temperatures.
522
523	  If selected, the scheduler will be able to balance tasks accordingly,
524	  i.e. put less load on throttled CPUs than on non/less throttled ones.
525
526	  This requires the architecture to implement
527	  arch_set_thermal_pressure() and arch_get_thermal_pressure().
528
529config BSD_PROCESS_ACCT
530	bool "BSD Process Accounting"
531	depends on MULTIUSER
532	help
533	  If you say Y here, a user level program will be able to instruct the
534	  kernel (via a special system call) to write process accounting
535	  information to a file: whenever a process exits, information about
536	  that process will be appended to the file by the kernel.  The
537	  information includes things such as creation time, owning user,
538	  command name, memory usage, controlling terminal etc. (the complete
539	  list is in the struct acct in <file:include/linux/acct.h>).  It is
540	  up to the user level program to do useful things with this
541	  information.  This is generally a good idea, so say Y.
542
543config BSD_PROCESS_ACCT_V3
544	bool "BSD Process Accounting version 3 file format"
545	depends on BSD_PROCESS_ACCT
546	default n
547	help
548	  If you say Y here, the process accounting information is written
549	  in a new file format that also logs the process IDs of each
550	  process and its parent. Note that this file format is incompatible
551	  with previous v0/v1/v2 file formats, so you will need updated tools
552	  for processing it. A preliminary version of these tools is available
553	  at <http://www.gnu.org/software/acct/>.
554
555config TASKSTATS
556	bool "Export task/process statistics through netlink"
557	depends on NET
558	depends on MULTIUSER
559	default n
560	help
561	  Export selected statistics for tasks/processes through the
562	  generic netlink interface. Unlike BSD process accounting, the
563	  statistics are available during the lifetime of tasks/processes as
564	  responses to commands. Like BSD accounting, they are sent to user
565	  space on task exit.
566
567	  Say N if unsure.
568
569config TASK_DELAY_ACCT
570	bool "Enable per-task delay accounting"
571	depends on TASKSTATS
572	select SCHED_INFO
573	help
574	  Collect information on time spent by a task waiting for system
575	  resources like cpu, synchronous block I/O completion and swapping
576	  in pages. Such statistics can help in setting a task's priorities
577	  relative to other tasks for cpu, io, rss limits etc.
578
579	  Say N if unsure.
580
581config TASK_XACCT
582	bool "Enable extended accounting over taskstats"
583	depends on TASKSTATS
584	help
585	  Collect extended task accounting data and send the data
586	  to userland for processing over the taskstats interface.
587
588	  Say N if unsure.
589
590config TASK_IO_ACCOUNTING
591	bool "Enable per-task storage I/O accounting"
592	depends on TASK_XACCT
593	help
594	  Collect information on the number of bytes of storage I/O which this
595	  task has caused.
596
597	  Say N if unsure.
598
599config PSI
600	bool "Pressure stall information tracking"
601	help
602	  Collect metrics that indicate how overcommitted the CPU, memory,
603	  and IO capacity are in the system.
604
605	  If you say Y here, the kernel will create /proc/pressure/ with the
606	  pressure statistics files cpu, memory, and io. These will indicate
607	  the share of walltime in which some or all tasks in the system are
608	  delayed due to contention of the respective resource.
609
610	  In kernels with cgroup support, cgroups (cgroup2 only) will
611	  have cpu.pressure, memory.pressure, and io.pressure files,
612	  which aggregate pressure stalls for the grouped tasks only.
613
614	  For more details see Documentation/accounting/psi.rst.
615
616	  Say N if unsure.
617
618config PSI_DEFAULT_DISABLED
619	bool "Require boot parameter to enable pressure stall information tracking"
620	default n
621	depends on PSI
622	help
623	  If set, pressure stall information tracking will be disabled
624	  per default but can be enabled through passing psi=1 on the
625	  kernel commandline during boot.
626
627	  This feature adds some code to the task wakeup and sleep
628	  paths of the scheduler. The overhead is too low to affect
629	  common scheduling-intense workloads in practice (such as
630	  webservers, memcache), but it does show up in artificial
631	  scheduler stress tests, such as hackbench.
632
633	  If you are paranoid and not sure what the kernel will be
634	  used for, say Y.
635
636	  Say N if unsure.
637
638endmenu # "CPU/Task time and stats accounting"
639
640config CPU_ISOLATION
641	bool "CPU isolation"
642	depends on SMP || COMPILE_TEST
643	default y
644	help
645	  Make sure that CPUs running critical tasks are not disturbed by
646	  any source of "noise" such as unbound workqueues, timers, kthreads...
647	  Unbound jobs get offloaded to housekeeping CPUs. This is driven by
648	  the "isolcpus=" boot parameter.
649
650	  Say Y if unsure.
651
652source "kernel/rcu/Kconfig"
653
654config BUILD_BIN2C
655	bool
656	default n
657
658config IKCONFIG
659	tristate "Kernel .config support"
660	help
661	  This option enables the complete Linux kernel ".config" file
662	  contents to be saved in the kernel. It provides documentation
663	  of which kernel options are used in a running kernel or in an
664	  on-disk kernel.  This information can be extracted from the kernel
665	  image file with the script scripts/extract-ikconfig and used as
666	  input to rebuild the current kernel or to build another kernel.
667	  It can also be extracted from a running kernel by reading
668	  /proc/config.gz if enabled (below).
669
670config IKCONFIG_PROC
671	bool "Enable access to .config through /proc/config.gz"
672	depends on IKCONFIG && PROC_FS
673	help
674	  This option enables access to the kernel configuration file
675	  through /proc/config.gz.
676
677config IKHEADERS
678	tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
679	depends on SYSFS
680	help
681	  This option enables access to the in-kernel headers that are generated during
682	  the build process. These can be used to build eBPF tracing programs,
683	  or similar programs.  If you build the headers as a module, a module called
684	  kheaders.ko is built which can be loaded on-demand to get access to headers.
685
686config LOG_BUF_SHIFT
687	int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
688	range 12 25 if !H8300
689	range 12 19 if H8300
690	default 17
691	depends on PRINTK
692	help
693	  Select the minimal kernel log buffer size as a power of 2.
694	  The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
695	  parameter, see below. Any higher size also might be forced
696	  by "log_buf_len" boot parameter.
697
698	  Examples:
699		     17 => 128 KB
700		     16 => 64 KB
701		     15 => 32 KB
702		     14 => 16 KB
703		     13 =>  8 KB
704		     12 =>  4 KB
705
706config LOG_CPU_MAX_BUF_SHIFT
707	int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
708	depends on SMP
709	range 0 21
710	default 12 if !BASE_SMALL
711	default 0 if BASE_SMALL
712	depends on PRINTK
713	help
714	  This option allows to increase the default ring buffer size
715	  according to the number of CPUs. The value defines the contribution
716	  of each CPU as a power of 2. The used space is typically only few
717	  lines however it might be much more when problems are reported,
718	  e.g. backtraces.
719
720	  The increased size means that a new buffer has to be allocated and
721	  the original static one is unused. It makes sense only on systems
722	  with more CPUs. Therefore this value is used only when the sum of
723	  contributions is greater than the half of the default kernel ring
724	  buffer as defined by LOG_BUF_SHIFT. The default values are set
725	  so that more than 16 CPUs are needed to trigger the allocation.
726
727	  Also this option is ignored when "log_buf_len" kernel parameter is
728	  used as it forces an exact (power of two) size of the ring buffer.
729
730	  The number of possible CPUs is used for this computation ignoring
731	  hotplugging making the computation optimal for the worst case
732	  scenario while allowing a simple algorithm to be used from bootup.
733
734	  Examples shift values and their meaning:
735		     17 => 128 KB for each CPU
736		     16 =>  64 KB for each CPU
737		     15 =>  32 KB for each CPU
738		     14 =>  16 KB for each CPU
739		     13 =>   8 KB for each CPU
740		     12 =>   4 KB for each CPU
741
742config PRINTK_SAFE_LOG_BUF_SHIFT
743	int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
744	range 10 21
745	default 13
746	depends on PRINTK
747	help
748	  Select the size of an alternate printk per-CPU buffer where messages
749	  printed from usafe contexts are temporary stored. One example would
750	  be NMI messages, another one - printk recursion. The messages are
751	  copied to the main log buffer in a safe context to avoid a deadlock.
752	  The value defines the size as a power of 2.
753
754	  Those messages are rare and limited. The largest one is when
755	  a backtrace is printed. It usually fits into 4KB. Select
756	  8KB if you want to be on the safe side.
757
758	  Examples:
759		     17 => 128 KB for each CPU
760		     16 =>  64 KB for each CPU
761		     15 =>  32 KB for each CPU
762		     14 =>  16 KB for each CPU
763		     13 =>   8 KB for each CPU
764		     12 =>   4 KB for each CPU
765
766#
767# Architectures with an unreliable sched_clock() should select this:
768#
769config HAVE_UNSTABLE_SCHED_CLOCK
770	bool
771
772config GENERIC_SCHED_CLOCK
773	bool
774
775menu "Scheduler features"
776
777config UCLAMP_TASK
778	bool "Enable utilization clamping for RT/FAIR tasks"
779	depends on CPU_FREQ_GOV_SCHEDUTIL
780	help
781	  This feature enables the scheduler to track the clamped utilization
782	  of each CPU based on RUNNABLE tasks scheduled on that CPU.
783
784	  With this option, the user can specify the min and max CPU
785	  utilization allowed for RUNNABLE tasks. The max utilization defines
786	  the maximum frequency a task should use while the min utilization
787	  defines the minimum frequency it should use.
788
789	  Both min and max utilization clamp values are hints to the scheduler,
790	  aiming at improving its frequency selection policy, but they do not
791	  enforce or grant any specific bandwidth for tasks.
792
793	  If in doubt, say N.
794
795config UCLAMP_BUCKETS_COUNT
796	int "Number of supported utilization clamp buckets"
797	range 5 20
798	default 5
799	depends on UCLAMP_TASK
800	help
801	  Defines the number of clamp buckets to use. The range of each bucket
802	  will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
803	  number of clamp buckets the finer their granularity and the higher
804	  the precision of clamping aggregation and tracking at run-time.
805
806	  For example, with the minimum configuration value we will have 5
807	  clamp buckets tracking 20% utilization each. A 25% boosted tasks will
808	  be refcounted in the [20..39]% bucket and will set the bucket clamp
809	  effective value to 25%.
810	  If a second 30% boosted task should be co-scheduled on the same CPU,
811	  that task will be refcounted in the same bucket of the first task and
812	  it will boost the bucket clamp effective value to 30%.
813	  The clamp effective value of a bucket is reset to its nominal value
814	  (20% in the example above) when there are no more tasks refcounted in
815	  that bucket.
816
817	  An additional boost/capping margin can be added to some tasks. In the
818	  example above the 25% task will be boosted to 30% until it exits the
819	  CPU. If that should be considered not acceptable on certain systems,
820	  it's always possible to reduce the margin by increasing the number of
821	  clamp buckets to trade off used memory for run-time tracking
822	  precision.
823
824	  If in doubt, use the default value.
825
826endmenu
827
828#
829# For architectures that want to enable the support for NUMA-affine scheduler
830# balancing logic:
831#
832config ARCH_SUPPORTS_NUMA_BALANCING
833	bool
834
835#
836# For architectures that prefer to flush all TLBs after a number of pages
837# are unmapped instead of sending one IPI per page to flush. The architecture
838# must provide guarantees on what happens if a clean TLB cache entry is
839# written after the unmap. Details are in mm/rmap.c near the check for
840# should_defer_flush. The architecture should also consider if the full flush
841# and the refill costs are offset by the savings of sending fewer IPIs.
842config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
843	bool
844
845config CC_HAS_INT128
846	def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
847
848#
849# For architectures that know their GCC __int128 support is sound
850#
851config ARCH_SUPPORTS_INT128
852	bool
853
854# For architectures that (ab)use NUMA to represent different memory regions
855# all cpu-local but of different latencies, such as SuperH.
856#
857config ARCH_WANT_NUMA_VARIABLE_LOCALITY
858	bool
859
860config NUMA_BALANCING
861	bool "Memory placement aware NUMA scheduler"
862	depends on ARCH_SUPPORTS_NUMA_BALANCING
863	depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
864	depends on SMP && NUMA && MIGRATION
865	help
866	  This option adds support for automatic NUMA aware memory/task placement.
867	  The mechanism is quite primitive and is based on migrating memory when
868	  it has references to the node the task is running on.
869
870	  This system will be inactive on UMA systems.
871
872config NUMA_BALANCING_DEFAULT_ENABLED
873	bool "Automatically enable NUMA aware memory/task placement"
874	default y
875	depends on NUMA_BALANCING
876	help
877	  If set, automatic NUMA balancing will be enabled if running on a NUMA
878	  machine.
879
880menuconfig CGROUPS
881	bool "Control Group support"
882	select KERNFS
883	help
884	  This option adds support for grouping sets of processes together, for
885	  use with process control subsystems such as Cpusets, CFS, memory
886	  controls or device isolation.
887	  See
888		- Documentation/scheduler/sched-design-CFS.rst	(CFS)
889		- Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
890					  and resource control)
891
892	  Say N if unsure.
893
894if CGROUPS
895
896config PAGE_COUNTER
897	bool
898
899config MEMCG
900	bool "Memory controller"
901	select PAGE_COUNTER
902	select EVENTFD
903	help
904	  Provides control over the memory footprint of tasks in a cgroup.
905
906config MEMCG_SWAP
907	bool
908	depends on MEMCG && SWAP
909	default y
910
911config MEMCG_KMEM
912	bool
913	depends on MEMCG && !SLOB
914	default y
915
916config BLK_CGROUP
917	bool "IO controller"
918	depends on BLOCK
919	default n
920	help
921	Generic block IO controller cgroup interface. This is the common
922	cgroup interface which should be used by various IO controlling
923	policies.
924
925	Currently, CFQ IO scheduler uses it to recognize task groups and
926	control disk bandwidth allocation (proportional time slice allocation)
927	to such task groups. It is also used by bio throttling logic in
928	block layer to implement upper limit in IO rates on a device.
929
930	This option only enables generic Block IO controller infrastructure.
931	One needs to also enable actual IO controlling logic/policy. For
932	enabling proportional weight division of disk bandwidth in CFQ, set
933	CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
934	CONFIG_BLK_DEV_THROTTLING=y.
935
936	See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
937
938config CGROUP_WRITEBACK
939	bool
940	depends on MEMCG && BLK_CGROUP
941	default y
942
943menuconfig CGROUP_SCHED
944	bool "CPU controller"
945	default n
946	help
947	  This feature lets CPU scheduler recognize task groups and control CPU
948	  bandwidth allocation to such task groups. It uses cgroups to group
949	  tasks.
950
951if CGROUP_SCHED
952config FAIR_GROUP_SCHED
953	bool "Group scheduling for SCHED_OTHER"
954	depends on CGROUP_SCHED
955	default CGROUP_SCHED
956
957config CFS_BANDWIDTH
958	bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
959	depends on FAIR_GROUP_SCHED
960	default n
961	help
962	  This option allows users to define CPU bandwidth rates (limits) for
963	  tasks running within the fair group scheduler.  Groups with no limit
964	  set are considered to be unconstrained and will run with no
965	  restriction.
966	  See Documentation/scheduler/sched-bwc.rst for more information.
967
968config RT_GROUP_SCHED
969	bool "Group scheduling for SCHED_RR/FIFO"
970	depends on CGROUP_SCHED
971	default n
972	help
973	  This feature lets you explicitly allocate real CPU bandwidth
974	  to task groups. If enabled, it will also make it impossible to
975	  schedule realtime tasks for non-root users until you allocate
976	  realtime bandwidth for them.
977	  See Documentation/scheduler/sched-rt-group.rst for more information.
978
979endif #CGROUP_SCHED
980
981config UCLAMP_TASK_GROUP
982	bool "Utilization clamping per group of tasks"
983	depends on CGROUP_SCHED
984	depends on UCLAMP_TASK
985	default n
986	help
987	  This feature enables the scheduler to track the clamped utilization
988	  of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
989
990	  When this option is enabled, the user can specify a min and max
991	  CPU bandwidth which is allowed for each single task in a group.
992	  The max bandwidth allows to clamp the maximum frequency a task
993	  can use, while the min bandwidth allows to define a minimum
994	  frequency a task will always use.
995
996	  When task group based utilization clamping is enabled, an eventually
997	  specified task-specific clamp value is constrained by the cgroup
998	  specified clamp value. Both minimum and maximum task clamping cannot
999	  be bigger than the corresponding clamping defined at task group level.
1000
1001	  If in doubt, say N.
1002
1003config CGROUP_PIDS
1004	bool "PIDs controller"
1005	help
1006	  Provides enforcement of process number limits in the scope of a
1007	  cgroup. Any attempt to fork more processes than is allowed in the
1008	  cgroup will fail. PIDs are fundamentally a global resource because it
1009	  is fairly trivial to reach PID exhaustion before you reach even a
1010	  conservative kmemcg limit. As a result, it is possible to grind a
1011	  system to halt without being limited by other cgroup policies. The
1012	  PIDs controller is designed to stop this from happening.
1013
1014	  It should be noted that organisational operations (such as attaching
1015	  to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
1016	  since the PIDs limit only affects a process's ability to fork, not to
1017	  attach to a cgroup.
1018
1019config CGROUP_RDMA
1020	bool "RDMA controller"
1021	help
1022	  Provides enforcement of RDMA resources defined by IB stack.
1023	  It is fairly easy for consumers to exhaust RDMA resources, which
1024	  can result into resource unavailability to other consumers.
1025	  RDMA controller is designed to stop this from happening.
1026	  Attaching processes with active RDMA resources to the cgroup
1027	  hierarchy is allowed even if can cross the hierarchy's limit.
1028
1029config CGROUP_FREEZER
1030	bool "Freezer controller"
1031	help
1032	  Provides a way to freeze and unfreeze all tasks in a
1033	  cgroup.
1034
1035	  This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1036	  controller includes important in-kernel memory consumers per default.
1037
1038	  If you're using cgroup2, say N.
1039
1040config CGROUP_HUGETLB
1041	bool "HugeTLB controller"
1042	depends on HUGETLB_PAGE
1043	select PAGE_COUNTER
1044	default n
1045	help
1046	  Provides a cgroup controller for HugeTLB pages.
1047	  When you enable this, you can put a per cgroup limit on HugeTLB usage.
1048	  The limit is enforced during page fault. Since HugeTLB doesn't
1049	  support page reclaim, enforcing the limit at page fault time implies
1050	  that, the application will get SIGBUS signal if it tries to access
1051	  HugeTLB pages beyond its limit. This requires the application to know
1052	  beforehand how much HugeTLB pages it would require for its use. The
1053	  control group is tracked in the third page lru pointer. This means
1054	  that we cannot use the controller with huge page less than 3 pages.
1055
1056config CPUSETS
1057	bool "Cpuset controller"
1058	depends on SMP
1059	help
1060	  This option will let you create and manage CPUSETs which
1061	  allow dynamically partitioning a system into sets of CPUs and
1062	  Memory Nodes and assigning tasks to run only within those sets.
1063	  This is primarily useful on large SMP or NUMA systems.
1064
1065	  Say N if unsure.
1066
1067config PROC_PID_CPUSET
1068	bool "Include legacy /proc/<pid>/cpuset file"
1069	depends on CPUSETS
1070	default y
1071
1072config CGROUP_DEVICE
1073	bool "Device controller"
1074	help
1075	  Provides a cgroup controller implementing whitelists for
1076	  devices which a process in the cgroup can mknod or open.
1077
1078config CGROUP_CPUACCT
1079	bool "Simple CPU accounting controller"
1080	help
1081	  Provides a simple controller for monitoring the
1082	  total CPU consumed by the tasks in a cgroup.
1083
1084config CGROUP_PERF
1085	bool "Perf controller"
1086	depends on PERF_EVENTS
1087	help
1088	  This option extends the perf per-cpu mode to restrict monitoring
1089	  to threads which belong to the cgroup specified and run on the
1090	  designated cpu.  Or this can be used to have cgroup ID in samples
1091	  so that it can monitor performance events among cgroups.
1092
1093	  Say N if unsure.
1094
1095config CGROUP_BPF
1096	bool "Support for eBPF programs attached to cgroups"
1097	depends on BPF_SYSCALL
1098	select SOCK_CGROUP_DATA
1099	help
1100	  Allow attaching eBPF programs to a cgroup using the bpf(2)
1101	  syscall command BPF_PROG_ATTACH.
1102
1103	  In which context these programs are accessed depends on the type
1104	  of attachment. For instance, programs that are attached using
1105	  BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1106	  inet sockets.
1107
1108config CGROUP_DEBUG
1109	bool "Debug controller"
1110	default n
1111	depends on DEBUG_KERNEL
1112	help
1113	  This option enables a simple controller that exports
1114	  debugging information about the cgroups framework. This
1115	  controller is for control cgroup debugging only. Its
1116	  interfaces are not stable.
1117
1118	  Say N.
1119
1120config SOCK_CGROUP_DATA
1121	bool
1122	default n
1123
1124endif # CGROUPS
1125
1126menuconfig NAMESPACES
1127	bool "Namespaces support" if EXPERT
1128	depends on MULTIUSER
1129	default !EXPERT
1130	help
1131	  Provides the way to make tasks work with different objects using
1132	  the same id. For example same IPC id may refer to different objects
1133	  or same user id or pid may refer to different tasks when used in
1134	  different namespaces.
1135
1136if NAMESPACES
1137
1138config UTS_NS
1139	bool "UTS namespace"
1140	default y
1141	help
1142	  In this namespace tasks see different info provided with the
1143	  uname() system call
1144
1145config TIME_NS
1146	bool "TIME namespace"
1147	depends on GENERIC_VDSO_TIME_NS
1148	default y
1149	help
1150	  In this namespace boottime and monotonic clocks can be set.
1151	  The time will keep going with the same pace.
1152
1153config IPC_NS
1154	bool "IPC namespace"
1155	depends on (SYSVIPC || POSIX_MQUEUE)
1156	default y
1157	help
1158	  In this namespace tasks work with IPC ids which correspond to
1159	  different IPC objects in different namespaces.
1160
1161config USER_NS
1162	bool "User namespace"
1163	default n
1164	help
1165	  This allows containers, i.e. vservers, to use user namespaces
1166	  to provide different user info for different servers.
1167
1168	  When user namespaces are enabled in the kernel it is
1169	  recommended that the MEMCG option also be enabled and that
1170	  user-space use the memory control groups to limit the amount
1171	  of memory a memory unprivileged users can use.
1172
1173	  If unsure, say N.
1174
1175config PID_NS
1176	bool "PID Namespaces"
1177	default y
1178	help
1179	  Support process id namespaces.  This allows having multiple
1180	  processes with the same pid as long as they are in different
1181	  pid namespaces.  This is a building block of containers.
1182
1183config NET_NS
1184	bool "Network namespace"
1185	depends on NET
1186	default y
1187	help
1188	  Allow user space to create what appear to be multiple instances
1189	  of the network stack.
1190
1191endif # NAMESPACES
1192
1193config CHECKPOINT_RESTORE
1194	bool "Checkpoint/restore support"
1195	select PROC_CHILDREN
1196	default n
1197	help
1198	  Enables additional kernel features in a sake of checkpoint/restore.
1199	  In particular it adds auxiliary prctl codes to setup process text,
1200	  data and heap segment sizes, and a few additional /proc filesystem
1201	  entries.
1202
1203	  If unsure, say N here.
1204
1205config SCHED_AUTOGROUP
1206	bool "Automatic process group scheduling"
1207	select CGROUPS
1208	select CGROUP_SCHED
1209	select FAIR_GROUP_SCHED
1210	help
1211	  This option optimizes the scheduler for common desktop workloads by
1212	  automatically creating and populating task groups.  This separation
1213	  of workloads isolates aggressive CPU burners (like build jobs) from
1214	  desktop applications.  Task group autogeneration is currently based
1215	  upon task session.
1216
1217config SYSFS_DEPRECATED
1218	bool "Enable deprecated sysfs features to support old userspace tools"
1219	depends on SYSFS
1220	default n
1221	help
1222	  This option adds code that switches the layout of the "block" class
1223	  devices, to not show up in /sys/class/block/, but only in
1224	  /sys/block/.
1225
1226	  This switch is only active when the sysfs.deprecated=1 boot option is
1227	  passed or the SYSFS_DEPRECATED_V2 option is set.
1228
1229	  This option allows new kernels to run on old distributions and tools,
1230	  which might get confused by /sys/class/block/. Since 2007/2008 all
1231	  major distributions and tools handle this just fine.
1232
1233	  Recent distributions and userspace tools after 2009/2010 depend on
1234	  the existence of /sys/class/block/, and will not work with this
1235	  option enabled.
1236
1237	  Only if you are using a new kernel on an old distribution, you might
1238	  need to say Y here.
1239
1240config SYSFS_DEPRECATED_V2
1241	bool "Enable deprecated sysfs features by default"
1242	default n
1243	depends on SYSFS
1244	depends on SYSFS_DEPRECATED
1245	help
1246	  Enable deprecated sysfs by default.
1247
1248	  See the CONFIG_SYSFS_DEPRECATED option for more details about this
1249	  option.
1250
1251	  Only if you are using a new kernel on an old distribution, you might
1252	  need to say Y here. Even then, odds are you would not need it
1253	  enabled, you can always pass the boot option if absolutely necessary.
1254
1255config RELAY
1256	bool "Kernel->user space relay support (formerly relayfs)"
1257	select IRQ_WORK
1258	help
1259	  This option enables support for relay interface support in
1260	  certain file systems (such as debugfs).
1261	  It is designed to provide an efficient mechanism for tools and
1262	  facilities to relay large amounts of data from kernel space to
1263	  user space.
1264
1265	  If unsure, say N.
1266
1267config BLK_DEV_INITRD
1268	bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1269	help
1270	  The initial RAM filesystem is a ramfs which is loaded by the
1271	  boot loader (loadlin or lilo) and that is mounted as root
1272	  before the normal boot procedure. It is typically used to
1273	  load modules needed to mount the "real" root file system,
1274	  etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1275
1276	  If RAM disk support (BLK_DEV_RAM) is also included, this
1277	  also enables initial RAM disk (initrd) support and adds
1278	  15 Kbytes (more on some other architectures) to the kernel size.
1279
1280	  If unsure say Y.
1281
1282if BLK_DEV_INITRD
1283
1284source "usr/Kconfig"
1285
1286endif
1287
1288config BOOT_CONFIG
1289	bool "Boot config support"
1290	select BLK_DEV_INITRD
1291	help
1292	  Extra boot config allows system admin to pass a config file as
1293	  complemental extension of kernel cmdline when booting.
1294	  The boot config file must be attached at the end of initramfs
1295	  with checksum, size and magic word.
1296	  See <file:Documentation/admin-guide/bootconfig.rst> for details.
1297
1298	  If unsure, say Y.
1299
1300choice
1301	prompt "Compiler optimization level"
1302	default CC_OPTIMIZE_FOR_PERFORMANCE
1303
1304config CC_OPTIMIZE_FOR_PERFORMANCE
1305	bool "Optimize for performance (-O2)"
1306	help
1307	  This is the default optimization level for the kernel, building
1308	  with the "-O2" compiler flag for best performance and most
1309	  helpful compile-time warnings.
1310
1311config CC_OPTIMIZE_FOR_PERFORMANCE_O3
1312	bool "Optimize more for performance (-O3)"
1313	depends on ARC
1314	help
1315	  Choosing this option will pass "-O3" to your compiler to optimize
1316	  the kernel yet more for performance.
1317
1318config CC_OPTIMIZE_FOR_SIZE
1319	bool "Optimize for size (-Os)"
1320	help
1321	  Choosing this option will pass "-Os" to your compiler resulting
1322	  in a smaller kernel.
1323
1324endchoice
1325
1326config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1327	bool
1328	help
1329	  This requires that the arch annotates or otherwise protects
1330	  its external entry points from being discarded. Linker scripts
1331	  must also merge .text.*, .data.*, and .bss.* correctly into
1332	  output sections. Care must be taken not to pull in unrelated
1333	  sections (e.g., '.text.init'). Typically '.' in section names
1334	  is used to distinguish them from label names / C identifiers.
1335
1336config LD_DEAD_CODE_DATA_ELIMINATION
1337	bool "Dead code and data elimination (EXPERIMENTAL)"
1338	depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1339	depends on EXPERT
1340	depends on $(cc-option,-ffunction-sections -fdata-sections)
1341	depends on $(ld-option,--gc-sections)
1342	help
1343	  Enable this if you want to do dead code and data elimination with
1344	  the linker by compiling with -ffunction-sections -fdata-sections,
1345	  and linking with --gc-sections.
1346
1347	  This can reduce on disk and in-memory size of the kernel
1348	  code and static data, particularly for small configs and
1349	  on small systems. This has the possibility of introducing
1350	  silently broken kernel if the required annotations are not
1351	  present. This option is not well tested yet, so use at your
1352	  own risk.
1353
1354config LD_ORPHAN_WARN
1355	def_bool y
1356	depends on ARCH_WANT_LD_ORPHAN_WARN
1357	depends on !LD_IS_LLD || LLD_VERSION >= 110000
1358	depends on $(ld-option,--orphan-handling=warn)
1359
1360config SYSCTL
1361	bool
1362
1363config HAVE_UID16
1364	bool
1365
1366config SYSCTL_EXCEPTION_TRACE
1367	bool
1368	help
1369	  Enable support for /proc/sys/debug/exception-trace.
1370
1371config SYSCTL_ARCH_UNALIGN_NO_WARN
1372	bool
1373	help
1374	  Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1375	  Allows arch to define/use @no_unaligned_warning to possibly warn
1376	  about unaligned access emulation going on under the hood.
1377
1378config SYSCTL_ARCH_UNALIGN_ALLOW
1379	bool
1380	help
1381	  Enable support for /proc/sys/kernel/unaligned-trap
1382	  Allows arches to define/use @unaligned_enabled to runtime toggle
1383	  the unaligned access emulation.
1384	  see arch/parisc/kernel/unaligned.c for reference
1385
1386config HAVE_PCSPKR_PLATFORM
1387	bool
1388
1389# interpreter that classic socket filters depend on
1390config BPF
1391	bool
1392
1393menuconfig EXPERT
1394	bool "Configure standard kernel features (expert users)"
1395	# Unhide debug options, to make the on-by-default options visible
1396	select DEBUG_KERNEL
1397	help
1398	  This option allows certain base kernel options and settings
1399	  to be disabled or tweaked. This is for specialized
1400	  environments which can tolerate a "non-standard" kernel.
1401	  Only use this if you really know what you are doing.
1402
1403config UID16
1404	bool "Enable 16-bit UID system calls" if EXPERT
1405	depends on HAVE_UID16 && MULTIUSER
1406	default y
1407	help
1408	  This enables the legacy 16-bit UID syscall wrappers.
1409
1410config MULTIUSER
1411	bool "Multiple users, groups and capabilities support" if EXPERT
1412	default y
1413	help
1414	  This option enables support for non-root users, groups and
1415	  capabilities.
1416
1417	  If you say N here, all processes will run with UID 0, GID 0, and all
1418	  possible capabilities.  Saying N here also compiles out support for
1419	  system calls related to UIDs, GIDs, and capabilities, such as setuid,
1420	  setgid, and capset.
1421
1422	  If unsure, say Y here.
1423
1424config SGETMASK_SYSCALL
1425	bool "sgetmask/ssetmask syscalls support" if EXPERT
1426	def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1427	help
1428	  sys_sgetmask and sys_ssetmask are obsolete system calls
1429	  no longer supported in libc but still enabled by default in some
1430	  architectures.
1431
1432	  If unsure, leave the default option here.
1433
1434config SYSFS_SYSCALL
1435	bool "Sysfs syscall support" if EXPERT
1436	default y
1437	help
1438	  sys_sysfs is an obsolete system call no longer supported in libc.
1439	  Note that disabling this option is more secure but might break
1440	  compatibility with some systems.
1441
1442	  If unsure say Y here.
1443
1444config FHANDLE
1445	bool "open by fhandle syscalls" if EXPERT
1446	select EXPORTFS
1447	default y
1448	help
1449	  If you say Y here, a user level program will be able to map
1450	  file names to handle and then later use the handle for
1451	  different file system operations. This is useful in implementing
1452	  userspace file servers, which now track files using handles instead
1453	  of names. The handle would remain the same even if file names
1454	  get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1455	  syscalls.
1456
1457config POSIX_TIMERS
1458	bool "Posix Clocks & timers" if EXPERT
1459	default y
1460	help
1461	  This includes native support for POSIX timers to the kernel.
1462	  Some embedded systems have no use for them and therefore they
1463	  can be configured out to reduce the size of the kernel image.
1464
1465	  When this option is disabled, the following syscalls won't be
1466	  available: timer_create, timer_gettime: timer_getoverrun,
1467	  timer_settime, timer_delete, clock_adjtime, getitimer,
1468	  setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1469	  clock_getres and clock_nanosleep syscalls will be limited to
1470	  CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1471
1472	  If unsure say y.
1473
1474config PRINTK
1475	default y
1476	bool "Enable support for printk" if EXPERT
1477	select IRQ_WORK
1478	help
1479	  This option enables normal printk support. Removing it
1480	  eliminates most of the message strings from the kernel image
1481	  and makes the kernel more or less silent. As this makes it
1482	  very difficult to diagnose system problems, saying N here is
1483	  strongly discouraged.
1484
1485config PRINTK_NMI
1486	def_bool y
1487	depends on PRINTK
1488	depends on HAVE_NMI
1489
1490config BUG
1491	bool "BUG() support" if EXPERT
1492	default y
1493	help
1494	  Disabling this option eliminates support for BUG and WARN, reducing
1495	  the size of your kernel image and potentially quietly ignoring
1496	  numerous fatal conditions. You should only consider disabling this
1497	  option for embedded systems with no facilities for reporting errors.
1498	  Just say Y.
1499
1500config ELF_CORE
1501	depends on COREDUMP
1502	default y
1503	bool "Enable ELF core dumps" if EXPERT
1504	help
1505	  Enable support for generating core dumps. Disabling saves about 4k.
1506
1507
1508config PCSPKR_PLATFORM
1509	bool "Enable PC-Speaker support" if EXPERT
1510	depends on HAVE_PCSPKR_PLATFORM
1511	select I8253_LOCK
1512	default y
1513	help
1514	  This option allows to disable the internal PC-Speaker
1515	  support, saving some memory.
1516
1517config BASE_FULL
1518	default y
1519	bool "Enable full-sized data structures for core" if EXPERT
1520	help
1521	  Disabling this option reduces the size of miscellaneous core
1522	  kernel data structures. This saves memory on small machines,
1523	  but may reduce performance.
1524
1525config FUTEX
1526	bool "Enable futex support" if EXPERT
1527	default y
1528	imply RT_MUTEXES
1529	help
1530	  Disabling this option will cause the kernel to be built without
1531	  support for "fast userspace mutexes".  The resulting kernel may not
1532	  run glibc-based applications correctly.
1533
1534config FUTEX_PI
1535	bool
1536	depends on FUTEX && RT_MUTEXES
1537	default y
1538
1539config HAVE_FUTEX_CMPXCHG
1540	bool
1541	depends on FUTEX
1542	help
1543	  Architectures should select this if futex_atomic_cmpxchg_inatomic()
1544	  is implemented and always working. This removes a couple of runtime
1545	  checks.
1546
1547config EPOLL
1548	bool "Enable eventpoll support" if EXPERT
1549	default y
1550	help
1551	  Disabling this option will cause the kernel to be built without
1552	  support for epoll family of system calls.
1553
1554config SIGNALFD
1555	bool "Enable signalfd() system call" if EXPERT
1556	default y
1557	help
1558	  Enable the signalfd() system call that allows to receive signals
1559	  on a file descriptor.
1560
1561	  If unsure, say Y.
1562
1563config TIMERFD
1564	bool "Enable timerfd() system call" if EXPERT
1565	default y
1566	help
1567	  Enable the timerfd() system call that allows to receive timer
1568	  events on a file descriptor.
1569
1570	  If unsure, say Y.
1571
1572config EVENTFD
1573	bool "Enable eventfd() system call" if EXPERT
1574	default y
1575	help
1576	  Enable the eventfd() system call that allows to receive both
1577	  kernel notification (ie. KAIO) or userspace notifications.
1578
1579	  If unsure, say Y.
1580
1581config SHMEM
1582	bool "Use full shmem filesystem" if EXPERT
1583	default y
1584	depends on MMU
1585	help
1586	  The shmem is an internal filesystem used to manage shared memory.
1587	  It is backed by swap and manages resource limits. It is also exported
1588	  to userspace as tmpfs if TMPFS is enabled. Disabling this
1589	  option replaces shmem and tmpfs with the much simpler ramfs code,
1590	  which may be appropriate on small systems without swap.
1591
1592config AIO
1593	bool "Enable AIO support" if EXPERT
1594	default y
1595	help
1596	  This option enables POSIX asynchronous I/O which may by used
1597	  by some high performance threaded applications. Disabling
1598	  this option saves about 7k.
1599
1600config IO_URING
1601	bool "Enable IO uring support" if EXPERT
1602	select IO_WQ
1603	default y
1604	help
1605	  This option enables support for the io_uring interface, enabling
1606	  applications to submit and complete IO through submission and
1607	  completion rings that are shared between the kernel and application.
1608
1609config ADVISE_SYSCALLS
1610	bool "Enable madvise/fadvise syscalls" if EXPERT
1611	default y
1612	help
1613	  This option enables the madvise and fadvise syscalls, used by
1614	  applications to advise the kernel about their future memory or file
1615	  usage, improving performance. If building an embedded system where no
1616	  applications use these syscalls, you can disable this option to save
1617	  space.
1618
1619config HAVE_ARCH_USERFAULTFD_WP
1620	bool
1621	help
1622	  Arch has userfaultfd write protection support
1623
1624config MEMBARRIER
1625	bool "Enable membarrier() system call" if EXPERT
1626	default y
1627	help
1628	  Enable the membarrier() system call that allows issuing memory
1629	  barriers across all running threads, which can be used to distribute
1630	  the cost of user-space memory barriers asymmetrically by transforming
1631	  pairs of memory barriers into pairs consisting of membarrier() and a
1632	  compiler barrier.
1633
1634	  If unsure, say Y.
1635
1636config KALLSYMS
1637	bool "Load all symbols for debugging/ksymoops" if EXPERT
1638	default y
1639	help
1640	  Say Y here to let the kernel print out symbolic crash information and
1641	  symbolic stack backtraces. This increases the size of the kernel
1642	  somewhat, as all symbols have to be loaded into the kernel image.
1643
1644config KALLSYMS_ALL
1645	bool "Include all symbols in kallsyms"
1646	depends on DEBUG_KERNEL && KALLSYMS
1647	help
1648	  Normally kallsyms only contains the symbols of functions for nicer
1649	  OOPS messages and backtraces (i.e., symbols from the text and inittext
1650	  sections). This is sufficient for most cases. And only in very rare
1651	  cases (e.g., when a debugger is used) all symbols are required (e.g.,
1652	  names of variables from the data sections, etc).
1653
1654	  This option makes sure that all symbols are loaded into the kernel
1655	  image (i.e., symbols from all sections) in cost of increased kernel
1656	  size (depending on the kernel configuration, it may be 300KiB or
1657	  something like this).
1658
1659	  Say N unless you really need all symbols.
1660
1661config KALLSYMS_ABSOLUTE_PERCPU
1662	bool
1663	depends on KALLSYMS
1664	default X86_64 && SMP
1665
1666config KALLSYMS_BASE_RELATIVE
1667	bool
1668	depends on KALLSYMS
1669	default !IA64
1670	help
1671	  Instead of emitting them as absolute values in the native word size,
1672	  emit the symbol references in the kallsyms table as 32-bit entries,
1673	  each containing a relative value in the range [base, base + U32_MAX]
1674	  or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1675	  an absolute value in the range [0, S32_MAX] or a relative value in the
1676	  range [base, base + S32_MAX], where base is the lowest relative symbol
1677	  address encountered in the image.
1678
1679	  On 64-bit builds, this reduces the size of the address table by 50%,
1680	  but more importantly, it results in entries whose values are build
1681	  time constants, and no relocation pass is required at runtime to fix
1682	  up the entries based on the runtime load address of the kernel.
1683
1684# end of the "standard kernel features (expert users)" menu
1685
1686# syscall, maps, verifier
1687
1688config BPF_LSM
1689	bool "LSM Instrumentation with BPF"
1690	depends on BPF_EVENTS
1691	depends on BPF_SYSCALL
1692	depends on SECURITY
1693	depends on BPF_JIT
1694	help
1695	  Enables instrumentation of the security hooks with eBPF programs for
1696	  implementing dynamic MAC and Audit Policies.
1697
1698	  If you are unsure how to answer this question, answer N.
1699
1700config BPF_SYSCALL
1701	bool "Enable bpf() system call"
1702	select BPF
1703	select IRQ_WORK
1704	select TASKS_TRACE_RCU
1705	default n
1706	help
1707	  Enable the bpf() system call that allows to manipulate eBPF
1708	  programs and maps via file descriptors.
1709
1710config ARCH_WANT_DEFAULT_BPF_JIT
1711	bool
1712
1713config BPF_JIT_ALWAYS_ON
1714	bool "Permanently enable BPF JIT and remove BPF interpreter"
1715	depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
1716	help
1717	  Enables BPF JIT and removes BPF interpreter to avoid
1718	  speculative execution of BPF instructions by the interpreter
1719
1720config BPF_JIT_DEFAULT_ON
1721	def_bool ARCH_WANT_DEFAULT_BPF_JIT || BPF_JIT_ALWAYS_ON
1722	depends on HAVE_EBPF_JIT && BPF_JIT
1723
1724source "kernel/bpf/preload/Kconfig"
1725
1726config USERFAULTFD
1727	bool "Enable userfaultfd() system call"
1728	depends on MMU
1729	help
1730	  Enable the userfaultfd() system call that allows to intercept and
1731	  handle page faults in userland.
1732
1733config ARCH_HAS_MEMBARRIER_CALLBACKS
1734	bool
1735
1736config ARCH_HAS_MEMBARRIER_SYNC_CORE
1737	bool
1738
1739config RSEQ
1740	bool "Enable rseq() system call" if EXPERT
1741	default y
1742	depends on HAVE_RSEQ
1743	select MEMBARRIER
1744	help
1745	  Enable the restartable sequences system call. It provides a
1746	  user-space cache for the current CPU number value, which
1747	  speeds up getting the current CPU number from user-space,
1748	  as well as an ABI to speed up user-space operations on
1749	  per-CPU data.
1750
1751	  If unsure, say Y.
1752
1753config DEBUG_RSEQ
1754	default n
1755	bool "Enabled debugging of rseq() system call" if EXPERT
1756	depends on RSEQ && DEBUG_KERNEL
1757	help
1758	  Enable extra debugging checks for the rseq system call.
1759
1760	  If unsure, say N.
1761
1762config EMBEDDED
1763	bool "Embedded system"
1764	option allnoconfig_y
1765	select EXPERT
1766	help
1767	  This option should be enabled if compiling the kernel for
1768	  an embedded system so certain expert options are available
1769	  for configuration.
1770
1771config HAVE_PERF_EVENTS
1772	bool
1773	help
1774	  See tools/perf/design.txt for details.
1775
1776config PERF_USE_VMALLOC
1777	bool
1778	help
1779	  See tools/perf/design.txt for details
1780
1781config PC104
1782	bool "PC/104 support" if EXPERT
1783	help
1784	  Expose PC/104 form factor device drivers and options available for
1785	  selection and configuration. Enable this option if your target
1786	  machine has a PC/104 bus.
1787
1788menu "Kernel Performance Events And Counters"
1789
1790config PERF_EVENTS
1791	bool "Kernel performance events and counters"
1792	default y if PROFILING
1793	depends on HAVE_PERF_EVENTS
1794	select IRQ_WORK
1795	select SRCU
1796	help
1797	  Enable kernel support for various performance events provided
1798	  by software and hardware.
1799
1800	  Software events are supported either built-in or via the
1801	  use of generic tracepoints.
1802
1803	  Most modern CPUs support performance events via performance
1804	  counter registers. These registers count the number of certain
1805	  types of hw events: such as instructions executed, cachemisses
1806	  suffered, or branches mis-predicted - without slowing down the
1807	  kernel or applications. These registers can also trigger interrupts
1808	  when a threshold number of events have passed - and can thus be
1809	  used to profile the code that runs on that CPU.
1810
1811	  The Linux Performance Event subsystem provides an abstraction of
1812	  these software and hardware event capabilities, available via a
1813	  system call and used by the "perf" utility in tools/perf/. It
1814	  provides per task and per CPU counters, and it provides event
1815	  capabilities on top of those.
1816
1817	  Say Y if unsure.
1818
1819config DEBUG_PERF_USE_VMALLOC
1820	default n
1821	bool "Debug: use vmalloc to back perf mmap() buffers"
1822	depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1823	select PERF_USE_VMALLOC
1824	help
1825	  Use vmalloc memory to back perf mmap() buffers.
1826
1827	  Mostly useful for debugging the vmalloc code on platforms
1828	  that don't require it.
1829
1830	  Say N if unsure.
1831
1832endmenu
1833
1834config VM_EVENT_COUNTERS
1835	default y
1836	bool "Enable VM event counters for /proc/vmstat" if EXPERT
1837	help
1838	  VM event counters are needed for event counts to be shown.
1839	  This option allows the disabling of the VM event counters
1840	  on EXPERT systems.  /proc/vmstat will only show page counts
1841	  if VM event counters are disabled.
1842
1843config SLUB_DEBUG
1844	default y
1845	bool "Enable SLUB debugging support" if EXPERT
1846	depends on SLUB && SYSFS
1847	help
1848	  SLUB has extensive debug support features. Disabling these can
1849	  result in significant savings in code size. This also disables
1850	  SLUB sysfs support. /sys/slab will not exist and there will be
1851	  no support for cache validation etc.
1852
1853config SLUB_MEMCG_SYSFS_ON
1854	default n
1855	bool "Enable memcg SLUB sysfs support by default" if EXPERT
1856	depends on SLUB && SYSFS && MEMCG
1857	help
1858	  SLUB creates a directory under /sys/kernel/slab for each
1859	  allocation cache to host info and debug files. If memory
1860	  cgroup is enabled, each cache can have per memory cgroup
1861	  caches. SLUB can create the same sysfs directories for these
1862	  caches under /sys/kernel/slab/CACHE/cgroup but it can lead
1863	  to a very high number of debug files being created. This is
1864	  controlled by slub_memcg_sysfs boot parameter and this
1865	  config option determines the parameter's default value.
1866
1867config COMPAT_BRK
1868	bool "Disable heap randomization"
1869	default y
1870	help
1871	  Randomizing heap placement makes heap exploits harder, but it
1872	  also breaks ancient binaries (including anything libc5 based).
1873	  This option changes the bootup default to heap randomization
1874	  disabled, and can be overridden at runtime by setting
1875	  /proc/sys/kernel/randomize_va_space to 2.
1876
1877	  On non-ancient distros (post-2000 ones) N is usually a safe choice.
1878
1879choice
1880	prompt "Choose SLAB allocator"
1881	default SLUB
1882	help
1883	   This option allows to select a slab allocator.
1884
1885config SLAB
1886	bool "SLAB"
1887	select HAVE_HARDENED_USERCOPY_ALLOCATOR
1888	help
1889	  The regular slab allocator that is established and known to work
1890	  well in all environments. It organizes cache hot objects in
1891	  per cpu and per node queues.
1892
1893config SLUB
1894	bool "SLUB (Unqueued Allocator)"
1895	select HAVE_HARDENED_USERCOPY_ALLOCATOR
1896	help
1897	   SLUB is a slab allocator that minimizes cache line usage
1898	   instead of managing queues of cached objects (SLAB approach).
1899	   Per cpu caching is realized using slabs of objects instead
1900	   of queues of objects. SLUB can use memory efficiently
1901	   and has enhanced diagnostics. SLUB is the default choice for
1902	   a slab allocator.
1903
1904config SLOB
1905	depends on EXPERT
1906	bool "SLOB (Simple Allocator)"
1907	help
1908	   SLOB replaces the stock allocator with a drastically simpler
1909	   allocator. SLOB is generally more space efficient but
1910	   does not perform as well on large systems.
1911
1912endchoice
1913
1914config SLAB_MERGE_DEFAULT
1915	bool "Allow slab caches to be merged"
1916	default y
1917	help
1918	  For reduced kernel memory fragmentation, slab caches can be
1919	  merged when they share the same size and other characteristics.
1920	  This carries a risk of kernel heap overflows being able to
1921	  overwrite objects from merged caches (and more easily control
1922	  cache layout), which makes such heap attacks easier to exploit
1923	  by attackers. By keeping caches unmerged, these kinds of exploits
1924	  can usually only damage objects in the same cache. To disable
1925	  merging at runtime, "slab_nomerge" can be passed on the kernel
1926	  command line.
1927
1928config SLAB_FREELIST_RANDOM
1929	bool "Randomize slab freelist"
1930	depends on SLAB || SLUB
1931	help
1932	  Randomizes the freelist order used on creating new pages. This
1933	  security feature reduces the predictability of the kernel slab
1934	  allocator against heap overflows.
1935
1936config SLAB_FREELIST_HARDENED
1937	bool "Harden slab freelist metadata"
1938	depends on SLAB || SLUB
1939	help
1940	  Many kernel heap attacks try to target slab cache metadata and
1941	  other infrastructure. This options makes minor performance
1942	  sacrifices to harden the kernel slab allocator against common
1943	  freelist exploit methods. Some slab implementations have more
1944	  sanity-checking than others. This option is most effective with
1945	  CONFIG_SLUB.
1946
1947config SHUFFLE_PAGE_ALLOCATOR
1948	bool "Page allocator randomization"
1949	default SLAB_FREELIST_RANDOM && ACPI_NUMA
1950	help
1951	  Randomization of the page allocator improves the average
1952	  utilization of a direct-mapped memory-side-cache. See section
1953	  5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI
1954	  6.2a specification for an example of how a platform advertises
1955	  the presence of a memory-side-cache. There are also incidental
1956	  security benefits as it reduces the predictability of page
1957	  allocations to compliment SLAB_FREELIST_RANDOM, but the
1958	  default granularity of shuffling on the "MAX_ORDER - 1" i.e,
1959	  10th order of pages is selected based on cache utilization
1960	  benefits on x86.
1961
1962	  While the randomization improves cache utilization it may
1963	  negatively impact workloads on platforms without a cache. For
1964	  this reason, by default, the randomization is enabled only
1965	  after runtime detection of a direct-mapped memory-side-cache.
1966	  Otherwise, the randomization may be force enabled with the
1967	  'page_alloc.shuffle' kernel command line parameter.
1968
1969	  Say Y if unsure.
1970
1971config SLUB_CPU_PARTIAL
1972	default y
1973	depends on SLUB && SMP
1974	bool "SLUB per cpu partial cache"
1975	help
1976	  Per cpu partial caches accelerate objects allocation and freeing
1977	  that is local to a processor at the price of more indeterminism
1978	  in the latency of the free. On overflow these caches will be cleared
1979	  which requires the taking of locks that may cause latency spikes.
1980	  Typically one would choose no for a realtime system.
1981
1982config MMAP_ALLOW_UNINITIALIZED
1983	bool "Allow mmapped anonymous memory to be uninitialized"
1984	depends on EXPERT && !MMU
1985	default n
1986	help
1987	  Normally, and according to the Linux spec, anonymous memory obtained
1988	  from mmap() has its contents cleared before it is passed to
1989	  userspace.  Enabling this config option allows you to request that
1990	  mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1991	  providing a huge performance boost.  If this option is not enabled,
1992	  then the flag will be ignored.
1993
1994	  This is taken advantage of by uClibc's malloc(), and also by
1995	  ELF-FDPIC binfmt's brk and stack allocator.
1996
1997	  Because of the obvious security issues, this option should only be
1998	  enabled on embedded devices where you control what is run in
1999	  userspace.  Since that isn't generally a problem on no-MMU systems,
2000	  it is normally safe to say Y here.
2001
2002	  See Documentation/admin-guide/mm/nommu-mmap.rst for more information.
2003
2004config SYSTEM_DATA_VERIFICATION
2005	def_bool n
2006	select SYSTEM_TRUSTED_KEYRING
2007	select KEYS
2008	select CRYPTO
2009	select CRYPTO_RSA
2010	select ASYMMETRIC_KEY_TYPE
2011	select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
2012	select ASN1
2013	select OID_REGISTRY
2014	select X509_CERTIFICATE_PARSER
2015	select PKCS7_MESSAGE_PARSER
2016	help
2017	  Provide PKCS#7 message verification using the contents of the system
2018	  trusted keyring to provide public keys.  This then can be used for
2019	  module verification, kexec image verification and firmware blob
2020	  verification.
2021
2022config PROFILING
2023	bool "Profiling support"
2024	help
2025	  Say Y here to enable the extended profiling support mechanisms used
2026	  by profilers such as OProfile.
2027
2028#
2029# Place an empty function call at each tracepoint site. Can be
2030# dynamically changed for a probe function.
2031#
2032config TRACEPOINTS
2033	bool
2034
2035endmenu		# General setup
2036
2037source "arch/Kconfig"
2038
2039config RT_MUTEXES
2040	bool
2041
2042config BASE_SMALL
2043	int
2044	default 0 if BASE_FULL
2045	default 1 if !BASE_FULL
2046
2047config MODULE_SIG_FORMAT
2048	def_bool n
2049	select SYSTEM_DATA_VERIFICATION
2050
2051menuconfig MODULES
2052	bool "Enable loadable module support"
2053	option modules
2054	help
2055	  Kernel modules are small pieces of compiled code which can
2056	  be inserted in the running kernel, rather than being
2057	  permanently built into the kernel.  You use the "modprobe"
2058	  tool to add (and sometimes remove) them.  If you say Y here,
2059	  many parts of the kernel can be built as modules (by
2060	  answering M instead of Y where indicated): this is most
2061	  useful for infrequently used options which are not required
2062	  for booting.  For more information, see the man pages for
2063	  modprobe, lsmod, modinfo, insmod and rmmod.
2064
2065	  If you say Y here, you will need to run "make
2066	  modules_install" to put the modules under /lib/modules/
2067	  where modprobe can find them (you may need to be root to do
2068	  this).
2069
2070	  If unsure, say Y.
2071
2072if MODULES
2073
2074config MODULE_FORCE_LOAD
2075	bool "Forced module loading"
2076	default n
2077	help
2078	  Allow loading of modules without version information (ie. modprobe
2079	  --force).  Forced module loading sets the 'F' (forced) taint flag and
2080	  is usually a really bad idea.
2081
2082config MODULE_UNLOAD
2083	bool "Module unloading"
2084	help
2085	  Without this option you will not be able to unload any
2086	  modules (note that some modules may not be unloadable
2087	  anyway), which makes your kernel smaller, faster
2088	  and simpler.  If unsure, say Y.
2089
2090config MODULE_FORCE_UNLOAD
2091	bool "Forced module unloading"
2092	depends on MODULE_UNLOAD
2093	help
2094	  This option allows you to force a module to unload, even if the
2095	  kernel believes it is unsafe: the kernel will remove the module
2096	  without waiting for anyone to stop using it (using the -f option to
2097	  rmmod).  This is mainly for kernel developers and desperate users.
2098	  If unsure, say N.
2099
2100config MODVERSIONS
2101	bool "Module versioning support"
2102	help
2103	  Usually, you have to use modules compiled with your kernel.
2104	  Saying Y here makes it sometimes possible to use modules
2105	  compiled for different kernels, by adding enough information
2106	  to the modules to (hopefully) spot any changes which would
2107	  make them incompatible with the kernel you are running.  If
2108	  unsure, say N.
2109
2110config ASM_MODVERSIONS
2111	bool
2112	default HAVE_ASM_MODVERSIONS && MODVERSIONS
2113	help
2114	  This enables module versioning for exported symbols also from
2115	  assembly. This can be enabled only when the target architecture
2116	  supports it.
2117
2118config MODULE_REL_CRCS
2119	bool
2120	depends on MODVERSIONS
2121
2122config MODULE_SRCVERSION_ALL
2123	bool "Source checksum for all modules"
2124	help
2125	  Modules which contain a MODULE_VERSION get an extra "srcversion"
2126	  field inserted into their modinfo section, which contains a
2127    	  sum of the source files which made it.  This helps maintainers
2128	  see exactly which source was used to build a module (since
2129	  others sometimes change the module source without updating
2130	  the version).  With this option, such a "srcversion" field
2131	  will be created for all modules.  If unsure, say N.
2132
2133config MODULE_SIG
2134	bool "Module signature verification"
2135	select MODULE_SIG_FORMAT
2136	help
2137	  Check modules for valid signatures upon load: the signature
2138	  is simply appended to the module. For more information see
2139	  <file:Documentation/admin-guide/module-signing.rst>.
2140
2141	  Note that this option adds the OpenSSL development packages as a
2142	  kernel build dependency so that the signing tool can use its crypto
2143	  library.
2144
2145	  You should enable this option if you wish to use either
2146	  CONFIG_SECURITY_LOCKDOWN_LSM or lockdown functionality imposed via
2147	  another LSM - otherwise unsigned modules will be loadable regardless
2148	  of the lockdown policy.
2149
2150	  !!!WARNING!!!  If you enable this option, you MUST make sure that the
2151	  module DOES NOT get stripped after being signed.  This includes the
2152	  debuginfo strip done by some packagers (such as rpmbuild) and
2153	  inclusion into an initramfs that wants the module size reduced.
2154
2155config MODULE_SIG_FORCE
2156	bool "Require modules to be validly signed"
2157	depends on MODULE_SIG
2158	help
2159	  Reject unsigned modules or signed modules for which we don't have a
2160	  key.  Without this, such modules will simply taint the kernel.
2161
2162config MODULE_SIG_ALL
2163	bool "Automatically sign all modules"
2164	default y
2165	depends on MODULE_SIG
2166	help
2167	  Sign all modules during make modules_install. Without this option,
2168	  modules must be signed manually, using the scripts/sign-file tool.
2169
2170comment "Do not forget to sign required modules with scripts/sign-file"
2171	depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
2172
2173choice
2174	prompt "Which hash algorithm should modules be signed with?"
2175	depends on MODULE_SIG
2176	help
2177	  This determines which sort of hashing algorithm will be used during
2178	  signature generation.  This algorithm _must_ be built into the kernel
2179	  directly so that signature verification can take place.  It is not
2180	  possible to load a signed module containing the algorithm to check
2181	  the signature on that module.
2182
2183config MODULE_SIG_SHA1
2184	bool "Sign modules with SHA-1"
2185	select CRYPTO_SHA1
2186
2187config MODULE_SIG_SHA224
2188	bool "Sign modules with SHA-224"
2189	select CRYPTO_SHA256
2190
2191config MODULE_SIG_SHA256
2192	bool "Sign modules with SHA-256"
2193	select CRYPTO_SHA256
2194
2195config MODULE_SIG_SHA384
2196	bool "Sign modules with SHA-384"
2197	select CRYPTO_SHA512
2198
2199config MODULE_SIG_SHA512
2200	bool "Sign modules with SHA-512"
2201	select CRYPTO_SHA512
2202
2203endchoice
2204
2205config MODULE_SIG_HASH
2206	string
2207	depends on MODULE_SIG
2208	default "sha1" if MODULE_SIG_SHA1
2209	default "sha224" if MODULE_SIG_SHA224
2210	default "sha256" if MODULE_SIG_SHA256
2211	default "sha384" if MODULE_SIG_SHA384
2212	default "sha512" if MODULE_SIG_SHA512
2213
2214config MODULE_COMPRESS
2215	bool "Compress modules on installation"
2216	help
2217
2218	  Compresses kernel modules when 'make modules_install' is run; gzip or
2219	  xz depending on "Compression algorithm" below.
2220
2221	  module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
2222
2223	  Out-of-tree kernel modules installed using Kbuild will also be
2224	  compressed upon installation.
2225
2226	  Note: for modules inside an initrd or initramfs, it's more efficient
2227	  to compress the whole initrd or initramfs instead.
2228
2229	  Note: This is fully compatible with signed modules.
2230
2231	  If in doubt, say N.
2232
2233choice
2234	prompt "Compression algorithm"
2235	depends on MODULE_COMPRESS
2236	default MODULE_COMPRESS_GZIP
2237	help
2238	  This determines which sort of compression will be used during
2239	  'make modules_install'.
2240
2241	  GZIP (default) and XZ are supported.
2242
2243config MODULE_COMPRESS_GZIP
2244	bool "GZIP"
2245
2246config MODULE_COMPRESS_XZ
2247	bool "XZ"
2248
2249endchoice
2250
2251config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
2252	bool "Allow loading of modules with missing namespace imports"
2253	help
2254	  Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in
2255	  a namespace. A module that makes use of a symbol exported with such a
2256	  namespace is required to import the namespace via MODULE_IMPORT_NS().
2257	  There is no technical reason to enforce correct namespace imports,
2258	  but it creates consistency between symbols defining namespaces and
2259	  users importing namespaces they make use of. This option relaxes this
2260	  requirement and lifts the enforcement when loading a module.
2261
2262	  If unsure, say N.
2263
2264config UNUSED_SYMBOLS
2265	bool "Enable unused/obsolete exported symbols"
2266	default y if X86
2267	help
2268	  Unused but exported symbols make the kernel needlessly bigger.  For
2269	  that reason most of these unused exports will soon be removed.  This
2270	  option is provided temporarily to provide a transition period in case
2271	  some external kernel module needs one of these symbols anyway. If you
2272	  encounter such a case in your module, consider if you are actually
2273	  using the right API.  (rationale: since nobody in the kernel is using
2274	  this in a module, there is a pretty good chance it's actually the
2275	  wrong interface to use).  If you really need the symbol, please send a
2276	  mail to the linux kernel mailing list mentioning the symbol and why
2277	  you really need it, and what the merge plan to the mainline kernel for
2278	  your module is.
2279
2280config TRIM_UNUSED_KSYMS
2281	bool "Trim unused exported kernel symbols"
2282	depends on !UNUSED_SYMBOLS
2283	help
2284	  The kernel and some modules make many symbols available for
2285	  other modules to use via EXPORT_SYMBOL() and variants. Depending
2286	  on the set of modules being selected in your kernel configuration,
2287	  many of those exported symbols might never be used.
2288
2289	  This option allows for unused exported symbols to be dropped from
2290	  the build. In turn, this provides the compiler more opportunities
2291	  (especially when using LTO) for optimizing the code and reducing
2292	  binary size.  This might have some security advantages as well.
2293
2294	  If unsure, or if you need to build out-of-tree modules, say N.
2295
2296config UNUSED_KSYMS_WHITELIST
2297	string "Whitelist of symbols to keep in ksymtab"
2298	depends on TRIM_UNUSED_KSYMS
2299	help
2300	  By default, all unused exported symbols will be un-exported from the
2301	  build when TRIM_UNUSED_KSYMS is selected.
2302
2303	  UNUSED_KSYMS_WHITELIST allows to whitelist symbols that must be kept
2304	  exported at all times, even in absence of in-tree users. The value to
2305	  set here is the path to a text file containing the list of symbols,
2306	  one per line. The path can be absolute, or relative to the kernel
2307	  source tree.
2308
2309endif # MODULES
2310
2311config MODULES_TREE_LOOKUP
2312	def_bool y
2313	depends on PERF_EVENTS || TRACING
2314
2315config INIT_ALL_POSSIBLE
2316	bool
2317	help
2318	  Back when each arch used to define their own cpu_online_mask and
2319	  cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2320	  with all 1s, and others with all 0s.  When they were centralised,
2321	  it was better to provide this option than to break all the archs
2322	  and have several arch maintainers pursuing me down dark alleys.
2323
2324source "block/Kconfig"
2325
2326config PREEMPT_NOTIFIERS
2327	bool
2328
2329config PADATA
2330	depends on SMP
2331	bool
2332
2333config ASN1
2334	tristate
2335	help
2336	  Build a simple ASN.1 grammar compiler that produces a bytecode output
2337	  that can be interpreted by the ASN.1 stream decoder and used to
2338	  inform it as to what tags are to be expected in a stream and what
2339	  functions to call on what tags.
2340
2341source "kernel/Kconfig.locks"
2342
2343config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
2344	bool
2345
2346config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2347	bool
2348
2349# It may be useful for an architecture to override the definitions of the
2350# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2351# and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2352# different calling convention for syscalls. They can also override the
2353# macros for not-implemented syscalls in kernel/sys_ni.c and
2354# kernel/time/posix-stubs.c. All these overrides need to be available in
2355# <asm/syscall_wrapper.h>.
2356config ARCH_HAS_SYSCALL_WRAPPER
2357	def_bool n
2358