Kconfig 72 KB

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  1. # SPDX-License-Identifier: GPL-2.0-only
  2. config CC_VERSION_TEXT
  3. string
  4. default "$(CC_VERSION_TEXT)"
  5. help
  6. This is used in unclear ways:
  7. - Re-run Kconfig when the compiler is updated
  8. The 'default' property references the environment variable,
  9. CC_VERSION_TEXT so it is recorded in include/config/auto.conf.cmd.
  10. When the compiler is updated, Kconfig will be invoked.
  11. - Ensure full rebuild when the compiler is updated
  12. include/linux/compiler-version.h contains this option in the comment
  13. line so fixdep adds include/config/CC_VERSION_TEXT into the
  14. auto-generated dependency. When the compiler is updated, syncconfig
  15. will touch it and then every file will be rebuilt.
  16. config CC_IS_GCC
  17. def_bool $(success,test "$(cc-name)" = GCC)
  18. config GCC_VERSION
  19. int
  20. default $(cc-version) if CC_IS_GCC
  21. default 0
  22. config CC_IS_CLANG
  23. def_bool $(success,test "$(cc-name)" = Clang)
  24. config CLANG_VERSION
  25. int
  26. default $(cc-version) if CC_IS_CLANG
  27. default 0
  28. config AS_IS_GNU
  29. def_bool $(success,test "$(as-name)" = GNU)
  30. config AS_IS_LLVM
  31. def_bool $(success,test "$(as-name)" = LLVM)
  32. config AS_VERSION
  33. int
  34. # Use clang version if this is the integrated assembler
  35. default CLANG_VERSION if AS_IS_LLVM
  36. default $(as-version)
  37. config LD_IS_BFD
  38. def_bool $(success,test "$(ld-name)" = BFD)
  39. config LD_VERSION
  40. int
  41. default $(ld-version) if LD_IS_BFD
  42. default 0
  43. config LD_IS_LLD
  44. def_bool $(success,test "$(ld-name)" = LLD)
  45. config LLD_VERSION
  46. int
  47. default $(ld-version) if LD_IS_LLD
  48. default 0
  49. config RUSTC_VERSION
  50. int
  51. default $(rustc-version)
  52. help
  53. It does not depend on `RUST` since that one may need to use the version
  54. in a `depends on`.
  55. config RUST_IS_AVAILABLE
  56. def_bool $(success,$(srctree)/scripts/rust_is_available.sh)
  57. help
  58. This shows whether a suitable Rust toolchain is available (found).
  59. Please see Documentation/rust/quick-start.rst for instructions on how
  60. to satisfy the build requirements of Rust support.
  61. In particular, the Makefile target 'rustavailable' is useful to check
  62. why the Rust toolchain is not being detected.
  63. config RUSTC_LLVM_VERSION
  64. int
  65. default $(rustc-llvm-version)
  66. config ARCH_HAS_CC_CAN_LINK
  67. bool
  68. config CC_CAN_LINK
  69. bool
  70. default ARCH_CC_CAN_LINK if ARCH_HAS_CC_CAN_LINK
  71. default $(cc_can_link_user,$(m64-flag)) if 64BIT
  72. default $(cc_can_link_user,$(m32-flag))
  73. # Fixed in GCC 14, 13.3, 12.4 and 11.5
  74. # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921
  75. config GCC_ASM_GOTO_OUTPUT_BROKEN
  76. bool
  77. depends on CC_IS_GCC
  78. default y if GCC_VERSION < 110500
  79. default y if GCC_VERSION >= 120000 && GCC_VERSION < 120400
  80. default y if GCC_VERSION >= 130000 && GCC_VERSION < 130300
  81. config CC_HAS_ASM_GOTO_OUTPUT
  82. def_bool y
  83. depends on !GCC_ASM_GOTO_OUTPUT_BROKEN
  84. # Detect basic support
  85. depends on $(success,echo 'int foo(int x) { asm goto ("": "=r"(x) ::: bar); return x; bar: return 0; }' | $(CC) -x c - -c -o /dev/null)
  86. # Detect clang (< v17) scoped label issues
  87. depends on $(success,echo 'void b(void **);void* c(void);int f(void){{asm goto(""::::l0);return 0;l0:return 1;}void *x __attribute__((cleanup(b)))=c();{asm goto(""::::l1);return 2;l1:return 3;}}' | $(CC) -x c - -c -o /dev/null)
  88. config CC_HAS_ASM_GOTO_TIED_OUTPUT
  89. depends on CC_HAS_ASM_GOTO_OUTPUT
  90. # Detect buggy gcc and clang, fixed in gcc-11 clang-14.
  91. def_bool $(success,echo 'int foo(int *x) { asm goto (".long (%l[bar]) - .": "+m"(*x) ::: bar); return *x; bar: return 0; }' | $CC -x c - -c -o /dev/null)
  92. config TOOLS_SUPPORT_RELR
  93. def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
  94. config CC_HAS_ASM_INLINE
  95. def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
  96. config CC_HAS_ASSUME
  97. bool
  98. # clang needs to be at least 19.1.0 since the meaning of the assume
  99. # attribute changed:
  100. # https://github.com/llvm/llvm-project/commit/c44fa3e8a9a44c2e9a575768a3c185354b9f6c17
  101. default y if CC_IS_CLANG && CLANG_VERSION >= 190100
  102. # supported since gcc 13.1.0
  103. # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106654
  104. default y if CC_IS_GCC && GCC_VERSION >= 130100
  105. config CC_HAS_NO_PROFILE_FN_ATTR
  106. def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
  107. config CC_HAS_COUNTED_BY
  108. bool
  109. # clang needs to be at least 20.1.0 to avoid potential crashes
  110. # when building structures that contain __counted_by
  111. # https://github.com/ClangBuiltLinux/linux/issues/2114
  112. # https://github.com/llvm/llvm-project/commit/160fb1121cdf703c3ef5e61fb26c5659eb581489
  113. default y if CC_IS_CLANG && CLANG_VERSION >= 200100
  114. # supported since gcc 15.1.0
  115. # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108896
  116. default y if CC_IS_GCC && GCC_VERSION >= 150100
  117. config CC_HAS_COUNTED_BY_PTR
  118. bool
  119. # supported since clang 22
  120. default y if CC_IS_CLANG && CLANG_VERSION >= 220100
  121. # supported since gcc 16.0.0
  122. default y if CC_IS_GCC && GCC_VERSION >= 160000
  123. config CC_HAS_BROKEN_COUNTED_BY_REF
  124. bool
  125. # https://github.com/llvm/llvm-project/issues/182575
  126. default y if CC_IS_CLANG && CLANG_VERSION < 220100
  127. config CC_HAS_MULTIDIMENSIONAL_NONSTRING
  128. def_bool $(success,echo 'char tag[][4] __attribute__((__nonstring__)) = { };' | $(CC) $(CLANG_FLAGS) -x c - -c -o /dev/null -Werror)
  129. config LD_CAN_USE_KEEP_IN_OVERLAY
  130. # ld.lld prior to 21.0.0 did not support KEEP within an overlay description
  131. # https://github.com/llvm/llvm-project/pull/130661
  132. def_bool LD_IS_BFD || LLD_VERSION >= 210000
  133. config RUSTC_HAS_SLICE_AS_FLATTENED
  134. def_bool RUSTC_VERSION >= 108000
  135. config RUSTC_HAS_COERCE_POINTEE
  136. def_bool RUSTC_VERSION >= 108400
  137. config RUSTC_HAS_SPAN_FILE
  138. def_bool RUSTC_VERSION >= 108800
  139. config RUSTC_HAS_UNNECESSARY_TRANSMUTES
  140. def_bool RUSTC_VERSION >= 108800
  141. config RUSTC_HAS_FILE_WITH_NUL
  142. def_bool RUSTC_VERSION >= 108900
  143. config RUSTC_HAS_FILE_AS_C_STR
  144. def_bool RUSTC_VERSION >= 109100
  145. config PAHOLE_VERSION
  146. int
  147. default "$(PAHOLE_VERSION)"
  148. config CONSTRUCTORS
  149. bool
  150. config IRQ_WORK
  151. def_bool y if SMP
  152. config BUILDTIME_TABLE_SORT
  153. bool
  154. config THREAD_INFO_IN_TASK
  155. bool
  156. help
  157. Select this to move thread_info off the stack into task_struct. To
  158. make this work, an arch will need to remove all thread_info fields
  159. except flags and fix any runtime bugs.
  160. One subtle change that will be needed is to use try_get_task_stack()
  161. and put_task_stack() in save_thread_stack_tsk() and get_wchan().
  162. menu "General setup"
  163. config BROKEN
  164. bool
  165. help
  166. This option allows you to choose whether you want to try to
  167. compile (and fix) old drivers that haven't been updated to
  168. new infrastructure.
  169. config BROKEN_ON_SMP
  170. bool
  171. depends on BROKEN || !SMP
  172. default y
  173. config INIT_ENV_ARG_LIMIT
  174. int
  175. default 32 if !UML
  176. default 128 if UML
  177. help
  178. Maximum of each of the number of arguments and environment
  179. variables passed to init from the kernel command line.
  180. config COMPILE_TEST
  181. bool "Compile also drivers which will not load"
  182. depends on HAS_IOMEM
  183. help
  184. Some drivers can be compiled on a different platform than they are
  185. intended to be run on. Despite they cannot be loaded there (or even
  186. when they load they cannot be used due to missing HW support),
  187. developers still, opposing to distributors, might want to build such
  188. drivers to compile-test them.
  189. If you are a developer and want to build everything available, say Y
  190. here. If you are a user/distributor, say N here to exclude useless
  191. drivers to be distributed.
  192. config WERROR
  193. bool "Compile the kernel with warnings as errors"
  194. default COMPILE_TEST
  195. help
  196. A kernel build should not cause any compiler warnings, and this
  197. enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags
  198. to enforce that rule by default. Certain warnings from other tools
  199. such as the linker may be upgraded to errors with this option as
  200. well.
  201. However, if you have a new (or very old) compiler or linker with odd
  202. and unusual warnings, or you have some architecture with problems,
  203. you may need to disable this config option in order to
  204. successfully build the kernel.
  205. If in doubt, say Y.
  206. config UAPI_HEADER_TEST
  207. bool "Compile test UAPI headers"
  208. depends on HEADERS_INSTALL
  209. help
  210. Compile test headers exported to user-space to ensure they are
  211. self-contained, i.e. compilable as standalone units.
  212. If you are a developer or tester and want to ensure the exported
  213. headers are self-contained, say Y here. Otherwise, choose N.
  214. config LOCALVERSION
  215. string "Local version - append to kernel release"
  216. help
  217. Append an extra string to the end of your kernel version.
  218. This will show up when you type uname, for example.
  219. The string you set here will be appended after the contents of
  220. any files with a filename matching localversion* in your
  221. object and source tree, in that order. Your total string can
  222. be a maximum of 64 characters.
  223. config LOCALVERSION_AUTO
  224. bool "Automatically append version information to the version string"
  225. default y
  226. depends on !COMPILE_TEST
  227. help
  228. This will try to automatically determine if the current tree is a
  229. release tree by looking for git tags that belong to the current
  230. top of tree revision.
  231. A string of the format -gxxxxxxxx will be added to the localversion
  232. if a git-based tree is found. The string generated by this will be
  233. appended after any matching localversion* files, and after the value
  234. set in CONFIG_LOCALVERSION.
  235. (The actual string used here is the first 12 characters produced
  236. by running the command:
  237. $ git rev-parse --verify HEAD
  238. which is done within the script "scripts/setlocalversion".)
  239. config BUILD_SALT
  240. string "Build ID Salt"
  241. default ""
  242. help
  243. The build ID is used to link binaries and their debug info. Setting
  244. this option will use the value in the calculation of the build id.
  245. This is mostly useful for distributions which want to ensure the
  246. build is unique between builds. It's safe to leave the default.
  247. config HAVE_KERNEL_GZIP
  248. bool
  249. config HAVE_KERNEL_BZIP2
  250. bool
  251. config HAVE_KERNEL_LZMA
  252. bool
  253. config HAVE_KERNEL_XZ
  254. bool
  255. config HAVE_KERNEL_LZO
  256. bool
  257. config HAVE_KERNEL_LZ4
  258. bool
  259. config HAVE_KERNEL_ZSTD
  260. bool
  261. config HAVE_KERNEL_UNCOMPRESSED
  262. bool
  263. choice
  264. prompt "Kernel compression mode"
  265. default KERNEL_GZIP
  266. 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
  267. help
  268. The linux kernel is a kind of self-extracting executable.
  269. Several compression algorithms are available, which differ
  270. in efficiency, compression and decompression speed.
  271. Compression speed is only relevant when building a kernel.
  272. Decompression speed is relevant at each boot.
  273. If you have any problems with bzip2 or lzma compressed
  274. kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
  275. version of this functionality (bzip2 only), for 2.4, was
  276. supplied by Christian Ludwig)
  277. High compression options are mostly useful for users, who
  278. are low on disk space (embedded systems), but for whom ram
  279. size matters less.
  280. If in doubt, select 'gzip'
  281. config KERNEL_GZIP
  282. bool "Gzip"
  283. depends on HAVE_KERNEL_GZIP
  284. help
  285. The old and tried gzip compression. It provides a good balance
  286. between compression ratio and decompression speed.
  287. config KERNEL_BZIP2
  288. bool "Bzip2"
  289. depends on HAVE_KERNEL_BZIP2
  290. help
  291. Its compression ratio and speed is intermediate.
  292. Decompression speed is slowest among the choices. The kernel
  293. size is about 10% smaller with bzip2, in comparison to gzip.
  294. Bzip2 uses a large amount of memory. For modern kernels you
  295. will need at least 8MB RAM or more for booting.
  296. config KERNEL_LZMA
  297. bool "LZMA"
  298. depends on HAVE_KERNEL_LZMA
  299. help
  300. This compression algorithm's ratio is best. Decompression speed
  301. is between gzip and bzip2. Compression is slowest.
  302. The kernel size is about 33% smaller with LZMA in comparison to gzip.
  303. config KERNEL_XZ
  304. bool "XZ"
  305. depends on HAVE_KERNEL_XZ
  306. help
  307. XZ uses the LZMA2 algorithm and instruction set specific
  308. BCJ filters which can improve compression ratio of executable
  309. code. The size of the kernel is about 30% smaller with XZ in
  310. comparison to gzip. On architectures for which there is a BCJ
  311. filter (i386, x86_64, ARM, ARM64, RISC-V, big endian PowerPC,
  312. and SPARC), XZ will create a few percent smaller kernel than
  313. plain LZMA.
  314. The speed is about the same as with LZMA: The decompression
  315. speed of XZ is better than that of bzip2 but worse than gzip
  316. and LZO. Compression is slow.
  317. config KERNEL_LZO
  318. bool "LZO"
  319. depends on HAVE_KERNEL_LZO
  320. help
  321. Its compression ratio is the poorest among the choices. The kernel
  322. size is about 10% bigger than gzip; however its speed
  323. (both compression and decompression) is the fastest.
  324. config KERNEL_LZ4
  325. bool "LZ4"
  326. depends on HAVE_KERNEL_LZ4
  327. help
  328. LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
  329. A preliminary version of LZ4 de/compression tool is available at
  330. <https://code.google.com/p/lz4/>.
  331. Its compression ratio is worse than LZO. The size of the kernel
  332. is about 8% bigger than LZO. But the decompression speed is
  333. faster than LZO.
  334. config KERNEL_ZSTD
  335. bool "ZSTD"
  336. depends on HAVE_KERNEL_ZSTD
  337. help
  338. ZSTD is a compression algorithm targeting intermediate compression
  339. with fast decompression speed. It will compress better than GZIP and
  340. decompress around the same speed as LZO, but slower than LZ4. You
  341. will need at least 192 KB RAM or more for booting. The zstd command
  342. line tool is required for compression.
  343. config KERNEL_UNCOMPRESSED
  344. bool "None"
  345. depends on HAVE_KERNEL_UNCOMPRESSED
  346. help
  347. Produce uncompressed kernel image. This option is usually not what
  348. you want. It is useful for debugging the kernel in slow simulation
  349. environments, where decompressing and moving the kernel is awfully
  350. slow. This option allows early boot code to skip the decompressor
  351. and jump right at uncompressed kernel image.
  352. endchoice
  353. config DEFAULT_INIT
  354. string "Default init path"
  355. default ""
  356. help
  357. This option determines the default init for the system if no init=
  358. option is passed on the kernel command line. If the requested path is
  359. not present, we will still then move on to attempting further
  360. locations (e.g. /sbin/init, etc). If this is empty, we will just use
  361. the fallback list when init= is not passed.
  362. config DEFAULT_HOSTNAME
  363. string "Default hostname"
  364. default "(none)"
  365. help
  366. This option determines the default system hostname before userspace
  367. calls sethostname(2). The kernel traditionally uses "(none)" here,
  368. but you may wish to use a different default here to make a minimal
  369. system more usable with less configuration.
  370. config SYSVIPC
  371. bool "System V IPC"
  372. help
  373. Inter Process Communication is a suite of library functions and
  374. system calls which let processes (running programs) synchronize and
  375. exchange information. It is generally considered to be a good thing,
  376. and some programs won't run unless you say Y here. In particular, if
  377. you want to run the DOS emulator dosemu under Linux (read the
  378. DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
  379. you'll need to say Y here.
  380. You can find documentation about IPC with "info ipc" and also in
  381. section 6.4 of the Linux Programmer's Guide, available from
  382. <http://www.tldp.org/guides.html>.
  383. config SYSVIPC_SYSCTL
  384. bool
  385. depends on SYSVIPC
  386. depends on SYSCTL
  387. default y
  388. config SYSVIPC_COMPAT
  389. def_bool y
  390. depends on COMPAT && SYSVIPC
  391. config POSIX_MQUEUE
  392. bool "POSIX Message Queues"
  393. depends on NET
  394. help
  395. POSIX variant of message queues is a part of IPC. In POSIX message
  396. queues every message has a priority which decides about succession
  397. of receiving it by a process. If you want to compile and run
  398. programs written e.g. for Solaris with use of its POSIX message
  399. queues (functions mq_*) say Y here.
  400. POSIX message queues are visible as a filesystem called 'mqueue'
  401. and can be mounted somewhere if you want to do filesystem
  402. operations on message queues.
  403. If unsure, say Y.
  404. config POSIX_MQUEUE_SYSCTL
  405. bool
  406. depends on POSIX_MQUEUE
  407. depends on SYSCTL
  408. default y
  409. config WATCH_QUEUE
  410. bool "General notification queue"
  411. default n
  412. help
  413. This is a general notification queue for the kernel to pass events to
  414. userspace by splicing them into pipes. It can be used in conjunction
  415. with watches for key/keyring change notifications and device
  416. notifications.
  417. See Documentation/core-api/watch_queue.rst
  418. config CROSS_MEMORY_ATTACH
  419. bool "Enable process_vm_readv/writev syscalls"
  420. depends on MMU
  421. default y
  422. help
  423. Enabling this option adds the system calls process_vm_readv and
  424. process_vm_writev which allow a process with the correct privileges
  425. to directly read from or write to another process' address space.
  426. See the man page for more details.
  427. config AUDIT
  428. bool "Auditing support"
  429. depends on NET
  430. help
  431. Enable auditing infrastructure that can be used with another
  432. kernel subsystem, such as SELinux (which requires this for
  433. logging of avc messages output). System call auditing is included
  434. on architectures which support it.
  435. config HAVE_ARCH_AUDITSYSCALL
  436. bool
  437. config AUDITSYSCALL
  438. def_bool y
  439. depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
  440. select FSNOTIFY
  441. source "kernel/irq/Kconfig"
  442. source "kernel/time/Kconfig"
  443. source "kernel/bpf/Kconfig"
  444. source "kernel/Kconfig.preempt"
  445. menu "CPU/Task time and stats accounting"
  446. config VIRT_CPU_ACCOUNTING
  447. bool
  448. choice
  449. prompt "Cputime accounting"
  450. default TICK_CPU_ACCOUNTING
  451. # Kind of a stub config for the pure tick based cputime accounting
  452. config TICK_CPU_ACCOUNTING
  453. bool "Simple tick based cputime accounting"
  454. depends on !S390 && !NO_HZ_FULL
  455. help
  456. This is the basic tick based cputime accounting that maintains
  457. statistics about user, system and idle time spent on per jiffies
  458. granularity.
  459. If unsure, say Y.
  460. config 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. config VIRT_CPU_ACCOUNTING_GEN
  473. bool "Full dynticks CPU time accounting"
  474. depends on HAVE_CONTEXT_TRACKING_USER
  475. depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
  476. depends on GENERIC_CLOCKEVENTS
  477. select VIRT_CPU_ACCOUNTING
  478. select CONTEXT_TRACKING_USER
  479. help
  480. Select this option to enable task and CPU time accounting on full
  481. dynticks systems. This accounting is implemented by watching every
  482. kernel-user boundaries using the context tracking subsystem.
  483. The accounting is thus performed at the expense of some significant
  484. overhead.
  485. For now this is only useful if you are working on the full
  486. dynticks subsystem development.
  487. If unsure, say N.
  488. endchoice
  489. config IRQ_TIME_ACCOUNTING
  490. bool "Fine granularity task level IRQ time accounting"
  491. depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
  492. help
  493. Select this option to enable fine granularity task irq time
  494. accounting. This is done by reading a timestamp on each
  495. transitions between softirq and hardirq state, so there can be a
  496. small performance impact.
  497. If in doubt, say N here.
  498. config HAVE_SCHED_AVG_IRQ
  499. def_bool y
  500. depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
  501. depends on SMP
  502. config SCHED_HW_PRESSURE
  503. bool
  504. default y if ARM && ARM_CPU_TOPOLOGY
  505. default y if ARM64
  506. depends on SMP
  507. depends on CPU_FREQ_THERMAL
  508. help
  509. Select this option to enable HW pressure accounting in the
  510. scheduler. HW pressure is the value conveyed to the scheduler
  511. that reflects the reduction in CPU compute capacity resulted from
  512. HW throttling. HW throttling occurs when the performance of
  513. a CPU is capped due to high operating temperatures as an example.
  514. If selected, the scheduler will be able to balance tasks accordingly,
  515. i.e. put less load on throttled CPUs than on non/less throttled ones.
  516. This requires the architecture to implement
  517. arch_update_hw_pressure() and arch_scale_thermal_pressure().
  518. config BSD_PROCESS_ACCT
  519. bool "BSD Process Accounting (DEPRECATED)"
  520. depends on MULTIUSER
  521. default n
  522. help
  523. If you say Y here, a user level program will be able to instruct the
  524. kernel (via a special system call) to write process accounting
  525. information to a file: whenever a process exits, information about
  526. that process will be appended to the file by the kernel. The
  527. information includes things such as creation time, owning user,
  528. command name, memory usage, controlling terminal etc. (the complete
  529. list is in the struct acct in <file:include/linux/acct.h>). It is
  530. up to the user level program to do useful things with this
  531. information. This mechanism is antiquated and has significant
  532. scalability issues. You probably want to use eBPF instead. Say
  533. N unless you really need this.
  534. config BSD_PROCESS_ACCT_V3
  535. bool "BSD Process Accounting version 3 file format"
  536. depends on BSD_PROCESS_ACCT
  537. default n
  538. help
  539. If you say Y here, the process accounting information is written
  540. in a new file format that also logs the process IDs of each
  541. process and its parent. Note that this file format is incompatible
  542. with previous v0/v1/v2 file formats, so you will need updated tools
  543. for processing it. A preliminary version of these tools is available
  544. at <http://www.gnu.org/software/acct/>.
  545. config TASKSTATS
  546. bool "Export task/process statistics through netlink"
  547. depends on NET
  548. depends on MULTIUSER
  549. default n
  550. help
  551. Export selected statistics for tasks/processes through the
  552. generic netlink interface. Unlike BSD process accounting, the
  553. statistics are available during the lifetime of tasks/processes as
  554. responses to commands. Like BSD accounting, they are sent to user
  555. space on task exit.
  556. Say N if unsure.
  557. config TASK_DELAY_ACCT
  558. bool "Enable per-task delay accounting"
  559. depends on TASKSTATS
  560. select SCHED_INFO
  561. help
  562. Collect information on time spent by a task waiting for system
  563. resources like cpu, synchronous block I/O completion and swapping
  564. in pages. Such statistics can help in setting a task's priorities
  565. relative to other tasks for cpu, io, rss limits etc.
  566. Say N if unsure.
  567. config TASK_XACCT
  568. bool "Enable extended accounting over taskstats"
  569. depends on TASKSTATS
  570. help
  571. Collect extended task accounting data and send the data
  572. to userland for processing over the taskstats interface.
  573. Say N if unsure.
  574. config TASK_IO_ACCOUNTING
  575. bool "Enable per-task storage I/O accounting"
  576. depends on TASK_XACCT
  577. help
  578. Collect information on the number of bytes of storage I/O which this
  579. task has caused.
  580. Say N if unsure.
  581. config PSI
  582. bool "Pressure stall information tracking"
  583. select KERNFS
  584. help
  585. Collect metrics that indicate how overcommitted the CPU, memory,
  586. and IO capacity are in the system.
  587. If you say Y here, the kernel will create /proc/pressure/ with the
  588. pressure statistics files cpu, memory, and io. These will indicate
  589. the share of walltime in which some or all tasks in the system are
  590. delayed due to contention of the respective resource.
  591. In kernels with cgroup support, cgroups (cgroup2 only) will
  592. have cpu.pressure, memory.pressure, and io.pressure files,
  593. which aggregate pressure stalls for the grouped tasks only.
  594. For more details see Documentation/accounting/psi.rst.
  595. Say N if unsure.
  596. config PSI_DEFAULT_DISABLED
  597. bool "Require boot parameter to enable pressure stall information tracking"
  598. default n
  599. depends on PSI
  600. help
  601. If set, pressure stall information tracking will be disabled
  602. per default but can be enabled through passing psi=1 on the
  603. kernel commandline during boot.
  604. This feature adds some code to the task wakeup and sleep
  605. paths of the scheduler. The overhead is too low to affect
  606. common scheduling-intense workloads in practice (such as
  607. webservers, memcache), but it does show up in artificial
  608. scheduler stress tests, such as hackbench.
  609. If you are paranoid and not sure what the kernel will be
  610. used for, say Y.
  611. Say N if unsure.
  612. endmenu # "CPU/Task time and stats accounting"
  613. config CPU_ISOLATION
  614. bool "CPU isolation"
  615. depends on SMP
  616. default y
  617. help
  618. Make sure that CPUs running critical tasks are not disturbed by
  619. any source of "noise" such as unbound workqueues, timers, kthreads...
  620. Unbound jobs get offloaded to housekeeping CPUs. This is driven by
  621. the "isolcpus=" boot parameter.
  622. Say Y if unsure.
  623. source "kernel/rcu/Kconfig"
  624. config IKCONFIG
  625. tristate "Kernel .config support"
  626. help
  627. This option enables the complete Linux kernel ".config" file
  628. contents to be saved in the kernel. It provides documentation
  629. of which kernel options are used in a running kernel or in an
  630. on-disk kernel. This information can be extracted from the kernel
  631. image file with the script scripts/extract-ikconfig and used as
  632. input to rebuild the current kernel or to build another kernel.
  633. It can also be extracted from a running kernel by reading
  634. /proc/config.gz if enabled (below).
  635. config IKCONFIG_PROC
  636. bool "Enable access to .config through /proc/config.gz"
  637. depends on IKCONFIG && PROC_FS
  638. help
  639. This option enables access to the kernel configuration file
  640. through /proc/config.gz.
  641. config IKHEADERS
  642. tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
  643. depends on SYSFS
  644. help
  645. This option enables access to the in-kernel headers that are generated during
  646. the build process. These can be used to build eBPF tracing programs,
  647. or similar programs. If you build the headers as a module, a module called
  648. kheaders.ko is built which can be loaded on-demand to get access to headers.
  649. config LOG_BUF_SHIFT
  650. int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
  651. range 12 25
  652. default 17
  653. depends on PRINTK
  654. help
  655. Select the minimal kernel log buffer size as a power of 2.
  656. The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
  657. parameter, see below. Any higher size also might be forced
  658. by "log_buf_len" boot parameter.
  659. Examples:
  660. 17 => 128 KB
  661. 16 => 64 KB
  662. 15 => 32 KB
  663. 14 => 16 KB
  664. 13 => 8 KB
  665. 12 => 4 KB
  666. config LOG_CPU_MAX_BUF_SHIFT
  667. int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
  668. depends on SMP
  669. range 0 21
  670. default 0 if BASE_SMALL
  671. default 12
  672. depends on PRINTK
  673. help
  674. This option allows to increase the default ring buffer size
  675. according to the number of CPUs. The value defines the contribution
  676. of each CPU as a power of 2. The used space is typically only few
  677. lines however it might be much more when problems are reported,
  678. e.g. backtraces.
  679. The increased size means that a new buffer has to be allocated and
  680. the original static one is unused. It makes sense only on systems
  681. with more CPUs. Therefore this value is used only when the sum of
  682. contributions is greater than the half of the default kernel ring
  683. buffer as defined by LOG_BUF_SHIFT. The default values are set
  684. so that more than 16 CPUs are needed to trigger the allocation.
  685. Also this option is ignored when "log_buf_len" kernel parameter is
  686. used as it forces an exact (power of two) size of the ring buffer.
  687. The number of possible CPUs is used for this computation ignoring
  688. hotplugging making the computation optimal for the worst case
  689. scenario while allowing a simple algorithm to be used from bootup.
  690. Examples shift values and their meaning:
  691. 17 => 128 KB for each CPU
  692. 16 => 64 KB for each CPU
  693. 15 => 32 KB for each CPU
  694. 14 => 16 KB for each CPU
  695. 13 => 8 KB for each CPU
  696. 12 => 4 KB for each CPU
  697. config PRINTK_INDEX
  698. bool "Printk indexing debugfs interface"
  699. depends on PRINTK && DEBUG_FS
  700. help
  701. Add support for indexing of all printk formats known at compile time
  702. at <debugfs>/printk/index/<module>.
  703. This can be used as part of maintaining daemons which monitor
  704. /dev/kmsg, as it permits auditing the printk formats present in a
  705. kernel, allowing detection of cases where monitored printks are
  706. changed or no longer present.
  707. There is no additional runtime cost to printk with this enabled.
  708. #
  709. # Architectures with an unreliable sched_clock() should select this:
  710. #
  711. config HAVE_UNSTABLE_SCHED_CLOCK
  712. bool
  713. config GENERIC_SCHED_CLOCK
  714. bool
  715. menu "Scheduler features"
  716. config UCLAMP_TASK
  717. bool "Enable utilization clamping for RT/FAIR tasks"
  718. depends on CPU_FREQ_GOV_SCHEDUTIL
  719. help
  720. This feature enables the scheduler to track the clamped utilization
  721. of each CPU based on RUNNABLE tasks scheduled on that CPU.
  722. With this option, the user can specify the min and max CPU
  723. utilization allowed for RUNNABLE tasks. The max utilization defines
  724. the maximum frequency a task should use while the min utilization
  725. defines the minimum frequency it should use.
  726. Both min and max utilization clamp values are hints to the scheduler,
  727. aiming at improving its frequency selection policy, but they do not
  728. enforce or grant any specific bandwidth for tasks.
  729. If in doubt, say N.
  730. config UCLAMP_BUCKETS_COUNT
  731. int "Number of supported utilization clamp buckets"
  732. range 5 20
  733. default 5
  734. depends on UCLAMP_TASK
  735. help
  736. Defines the number of clamp buckets to use. The range of each bucket
  737. will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
  738. number of clamp buckets the finer their granularity and the higher
  739. the precision of clamping aggregation and tracking at run-time.
  740. For example, with the minimum configuration value we will have 5
  741. clamp buckets tracking 20% utilization each. A 25% boosted tasks will
  742. be refcounted in the [20..39]% bucket and will set the bucket clamp
  743. effective value to 25%.
  744. If a second 30% boosted task should be co-scheduled on the same CPU,
  745. that task will be refcounted in the same bucket of the first task and
  746. it will boost the bucket clamp effective value to 30%.
  747. The clamp effective value of a bucket is reset to its nominal value
  748. (20% in the example above) when there are no more tasks refcounted in
  749. that bucket.
  750. An additional boost/capping margin can be added to some tasks. In the
  751. example above the 25% task will be boosted to 30% until it exits the
  752. CPU. If that should be considered not acceptable on certain systems,
  753. it's always possible to reduce the margin by increasing the number of
  754. clamp buckets to trade off used memory for run-time tracking
  755. precision.
  756. If in doubt, use the default value.
  757. config SCHED_PROXY_EXEC
  758. bool "Proxy Execution"
  759. # Avoid some build failures w/ PREEMPT_RT until it can be fixed
  760. depends on !PREEMPT_RT
  761. # Need to investigate how to inform sched_ext of split contexts
  762. depends on !SCHED_CLASS_EXT
  763. # Not particularly useful until we get to multi-rq proxying
  764. depends on EXPERT
  765. help
  766. This option enables proxy execution, a mechanism for mutex-owning
  767. tasks to inherit the scheduling context of higher priority waiters.
  768. endmenu
  769. #
  770. # For architectures that want to enable the support for NUMA-affine scheduler
  771. # balancing logic:
  772. #
  773. config ARCH_SUPPORTS_NUMA_BALANCING
  774. bool
  775. #
  776. # For architectures that prefer to flush all TLBs after a number of pages
  777. # are unmapped instead of sending one IPI per page to flush. The architecture
  778. # must provide guarantees on what happens if a clean TLB cache entry is
  779. # written after the unmap. Details are in mm/rmap.c near the check for
  780. # should_defer_flush. The architecture should also consider if the full flush
  781. # and the refill costs are offset by the savings of sending fewer IPIs.
  782. config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
  783. bool
  784. config CC_HAS_INT128
  785. def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
  786. config CC_IMPLICIT_FALLTHROUGH
  787. string
  788. default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5)
  789. default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough)
  790. # Currently, disable gcc-10+ array-bounds globally.
  791. # It's still broken in gcc-13, so no upper bound yet.
  792. config GCC10_NO_ARRAY_BOUNDS
  793. def_bool y
  794. config CC_NO_ARRAY_BOUNDS
  795. bool
  796. default y if CC_IS_GCC && GCC_VERSION >= 90000 && GCC10_NO_ARRAY_BOUNDS
  797. # Currently, disable -Wstringop-overflow for GCC globally.
  798. config GCC_NO_STRINGOP_OVERFLOW
  799. def_bool y
  800. config CC_NO_STRINGOP_OVERFLOW
  801. bool
  802. default y if CC_IS_GCC && GCC_NO_STRINGOP_OVERFLOW
  803. config CC_STRINGOP_OVERFLOW
  804. bool
  805. default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW
  806. #
  807. # For architectures that know their GCC __int128 support is sound
  808. #
  809. config ARCH_SUPPORTS_INT128
  810. bool
  811. # For architectures that (ab)use NUMA to represent different memory regions
  812. # all cpu-local but of different latencies, such as SuperH.
  813. #
  814. config ARCH_WANT_NUMA_VARIABLE_LOCALITY
  815. bool
  816. config NUMA_BALANCING
  817. bool "Memory placement aware NUMA scheduler"
  818. depends on ARCH_SUPPORTS_NUMA_BALANCING
  819. depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
  820. depends on SMP && NUMA && MIGRATION && !PREEMPT_RT
  821. help
  822. This option adds support for automatic NUMA aware memory/task placement.
  823. The mechanism is quite primitive and is based on migrating memory when
  824. it has references to the node the task is running on.
  825. This system will be inactive on UMA systems.
  826. config NUMA_BALANCING_DEFAULT_ENABLED
  827. bool "Automatically enable NUMA aware memory/task placement"
  828. default y
  829. depends on NUMA_BALANCING
  830. help
  831. If set, automatic NUMA balancing will be enabled if running on a NUMA
  832. machine.
  833. config SLAB_OBJ_EXT
  834. bool
  835. menuconfig CGROUPS
  836. bool "Control Group support"
  837. select KERNFS
  838. help
  839. This option adds support for grouping sets of processes together, for
  840. use with process control subsystems such as Cpusets, CFS, memory
  841. controls or device isolation.
  842. See
  843. - Documentation/scheduler/sched-design-CFS.rst (CFS)
  844. - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
  845. and resource control)
  846. Say N if unsure.
  847. if CGROUPS
  848. config PAGE_COUNTER
  849. bool
  850. config CGROUP_FAVOR_DYNMODS
  851. bool "Favor dynamic modification latency reduction by default"
  852. help
  853. This option enables the "favordynmods" mount option by default
  854. which reduces the latencies of dynamic cgroup modifications such
  855. as task migrations and controller on/offs at the cost of making
  856. hot path operations such as forks and exits more expensive.
  857. Say N if unsure.
  858. config MEMCG
  859. bool "Memory controller"
  860. select PAGE_COUNTER
  861. select EVENTFD
  862. select SLAB_OBJ_EXT
  863. select VM_EVENT_COUNTERS
  864. help
  865. Provides control over the memory footprint of tasks in a cgroup.
  866. config MEMCG_NMI_UNSAFE
  867. bool
  868. depends on MEMCG
  869. depends on HAVE_NMI
  870. depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && !ARCH_HAVE_NMI_SAFE_CMPXCHG
  871. default y
  872. config MEMCG_NMI_SAFETY_REQUIRES_ATOMIC
  873. bool
  874. depends on MEMCG
  875. depends on HAVE_NMI
  876. depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && ARCH_HAVE_NMI_SAFE_CMPXCHG
  877. default y
  878. config MEMCG_V1
  879. bool "Legacy cgroup v1 memory controller"
  880. depends on MEMCG
  881. default n
  882. help
  883. Legacy cgroup v1 memory controller which has been deprecated by
  884. cgroup v2 implementation. The v1 is there for legacy applications
  885. which haven't migrated to the new cgroup v2 interface yet. If you
  886. do not have any such application then you are completely fine leaving
  887. this option disabled.
  888. Please note that feature set of the legacy memory controller is likely
  889. going to shrink due to deprecation process. New deployments with v1
  890. controller are highly discouraged.
  891. Say N if unsure.
  892. config BLK_CGROUP
  893. bool "IO controller"
  894. depends on BLOCK
  895. default n
  896. help
  897. Generic block IO controller cgroup interface. This is the common
  898. cgroup interface which should be used by various IO controlling
  899. policies.
  900. Currently, CFQ IO scheduler uses it to recognize task groups and
  901. control disk bandwidth allocation (proportional time slice allocation)
  902. to such task groups. It is also used by bio throttling logic in
  903. block layer to implement upper limit in IO rates on a device.
  904. This option only enables generic Block IO controller infrastructure.
  905. One needs to also enable actual IO controlling logic/policy. For
  906. enabling proportional weight division of disk bandwidth in CFQ, set
  907. CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
  908. CONFIG_BLK_DEV_THROTTLING=y.
  909. See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
  910. config CGROUP_WRITEBACK
  911. bool
  912. depends on MEMCG && BLK_CGROUP
  913. default y
  914. menuconfig CGROUP_SCHED
  915. bool "CPU controller"
  916. default n
  917. help
  918. This feature lets CPU scheduler recognize task groups and control CPU
  919. bandwidth allocation to such task groups. It uses cgroups to group
  920. tasks.
  921. if CGROUP_SCHED
  922. config GROUP_SCHED_WEIGHT
  923. def_bool n
  924. config GROUP_SCHED_BANDWIDTH
  925. def_bool n
  926. config FAIR_GROUP_SCHED
  927. bool "Group scheduling for SCHED_OTHER"
  928. depends on CGROUP_SCHED
  929. select GROUP_SCHED_WEIGHT
  930. default CGROUP_SCHED
  931. config CFS_BANDWIDTH
  932. bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
  933. depends on FAIR_GROUP_SCHED
  934. select GROUP_SCHED_BANDWIDTH
  935. default n
  936. help
  937. This option allows users to define CPU bandwidth rates (limits) for
  938. tasks running within the fair group scheduler. Groups with no limit
  939. set are considered to be unconstrained and will run with no
  940. restriction.
  941. See Documentation/scheduler/sched-bwc.rst for more information.
  942. config RT_GROUP_SCHED
  943. bool "Group scheduling for SCHED_RR/FIFO"
  944. depends on CGROUP_SCHED
  945. default n
  946. help
  947. This feature lets you explicitly allocate real CPU bandwidth
  948. to task groups. If enabled, it will also make it impossible to
  949. schedule realtime tasks for non-root users until you allocate
  950. realtime bandwidth for them.
  951. See Documentation/scheduler/sched-rt-group.rst for more information.
  952. config RT_GROUP_SCHED_DEFAULT_DISABLED
  953. bool "Require boot parameter to enable group scheduling for SCHED_RR/FIFO"
  954. depends on RT_GROUP_SCHED
  955. default n
  956. help
  957. When set, the RT group scheduling is disabled by default. The option
  958. is in inverted form so that mere RT_GROUP_SCHED enables the group
  959. scheduling.
  960. Say N if unsure.
  961. config EXT_GROUP_SCHED
  962. bool
  963. depends on SCHED_CLASS_EXT && CGROUP_SCHED
  964. select GROUP_SCHED_WEIGHT
  965. select GROUP_SCHED_BANDWIDTH
  966. default y
  967. endif #CGROUP_SCHED
  968. config SCHED_MM_CID
  969. def_bool y
  970. depends on SMP && RSEQ
  971. config UCLAMP_TASK_GROUP
  972. bool "Utilization clamping per group of tasks"
  973. depends on CGROUP_SCHED
  974. depends on UCLAMP_TASK
  975. default n
  976. help
  977. This feature enables the scheduler to track the clamped utilization
  978. of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
  979. When this option is enabled, the user can specify a min and max
  980. CPU bandwidth which is allowed for each single task in a group.
  981. The max bandwidth allows to clamp the maximum frequency a task
  982. can use, while the min bandwidth allows to define a minimum
  983. frequency a task will always use.
  984. When task group based utilization clamping is enabled, an eventually
  985. specified task-specific clamp value is constrained by the cgroup
  986. specified clamp value. Both minimum and maximum task clamping cannot
  987. be bigger than the corresponding clamping defined at task group level.
  988. If in doubt, say N.
  989. config CGROUP_PIDS
  990. bool "PIDs controller"
  991. help
  992. Provides enforcement of process number limits in the scope of a
  993. cgroup. Any attempt to fork more processes than is allowed in the
  994. cgroup will fail. PIDs are fundamentally a global resource because it
  995. is fairly trivial to reach PID exhaustion before you reach even a
  996. conservative kmemcg limit. As a result, it is possible to grind a
  997. system to halt without being limited by other cgroup policies. The
  998. PIDs controller is designed to stop this from happening.
  999. It should be noted that organisational operations (such as attaching
  1000. to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
  1001. since the PIDs limit only affects a process's ability to fork, not to
  1002. attach to a cgroup.
  1003. config CGROUP_RDMA
  1004. bool "RDMA controller"
  1005. help
  1006. Provides enforcement of RDMA resources defined by IB stack.
  1007. It is fairly easy for consumers to exhaust RDMA resources, which
  1008. can result into resource unavailability to other consumers.
  1009. RDMA controller is designed to stop this from happening.
  1010. Attaching processes with active RDMA resources to the cgroup
  1011. hierarchy is allowed even if can cross the hierarchy's limit.
  1012. config CGROUP_DMEM
  1013. bool "Device memory controller (DMEM)"
  1014. select PAGE_COUNTER
  1015. help
  1016. The DMEM controller allows compatible devices to restrict device
  1017. memory usage based on the cgroup hierarchy.
  1018. As an example, it allows you to restrict VRAM usage for applications
  1019. in the DRM subsystem.
  1020. config CGROUP_FREEZER
  1021. bool "Freezer controller"
  1022. help
  1023. Provides a way to freeze and unfreeze all tasks in a
  1024. cgroup.
  1025. This option affects the ORIGINAL cgroup interface. The cgroup2 memory
  1026. controller includes important in-kernel memory consumers per default.
  1027. If you're using cgroup2, say N.
  1028. config CGROUP_HUGETLB
  1029. bool "HugeTLB controller"
  1030. depends on HUGETLB_PAGE
  1031. select PAGE_COUNTER
  1032. default n
  1033. help
  1034. Provides a cgroup controller for HugeTLB pages.
  1035. When you enable this, you can put a per cgroup limit on HugeTLB usage.
  1036. The limit is enforced during page fault. Since HugeTLB doesn't
  1037. support page reclaim, enforcing the limit at page fault time implies
  1038. that, the application will get SIGBUS signal if it tries to access
  1039. HugeTLB pages beyond its limit. This requires the application to know
  1040. beforehand how much HugeTLB pages it would require for its use. The
  1041. control group is tracked in the third page lru pointer. This means
  1042. that we cannot use the controller with huge page less than 3 pages.
  1043. config CPUSETS
  1044. bool "Cpuset controller"
  1045. depends on SMP
  1046. select UNION_FIND
  1047. select CPU_ISOLATION
  1048. help
  1049. This option will let you create and manage CPUSETs which
  1050. allow dynamically partitioning a system into sets of CPUs and
  1051. Memory Nodes and assigning tasks to run only within those sets.
  1052. This is primarily useful on large SMP or NUMA systems.
  1053. Say N if unsure.
  1054. config CPUSETS_V1
  1055. bool "Legacy cgroup v1 cpusets controller"
  1056. depends on CPUSETS
  1057. default n
  1058. help
  1059. Legacy cgroup v1 cpusets controller which has been deprecated by
  1060. cgroup v2 implementation. The v1 is there for legacy applications
  1061. which haven't migrated to the new cgroup v2 interface yet. Legacy
  1062. interface includes cpuset filesystem and /proc/<pid>/cpuset. If you
  1063. do not have any such application then you are completely fine leaving
  1064. this option disabled.
  1065. Say N if unsure.
  1066. config PROC_PID_CPUSET
  1067. bool "Include legacy /proc/<pid>/cpuset file"
  1068. depends on CPUSETS_V1
  1069. default y
  1070. config CGROUP_DEVICE
  1071. bool "Device controller"
  1072. help
  1073. Provides a cgroup controller implementing whitelists for
  1074. devices which a process in the cgroup can mknod or open.
  1075. config CGROUP_CPUACCT
  1076. bool "Simple CPU accounting controller"
  1077. help
  1078. Provides a simple controller for monitoring the
  1079. total CPU consumed by the tasks in a cgroup.
  1080. config CGROUP_PERF
  1081. bool "Perf controller"
  1082. depends on PERF_EVENTS
  1083. help
  1084. This option extends the perf per-cpu mode to restrict monitoring
  1085. to threads which belong to the cgroup specified and run on the
  1086. designated cpu. Or this can be used to have cgroup ID in samples
  1087. so that it can monitor performance events among cgroups.
  1088. Say N if unsure.
  1089. config CGROUP_BPF
  1090. bool "Support for eBPF programs attached to cgroups"
  1091. depends on BPF_SYSCALL
  1092. select SOCK_CGROUP_DATA
  1093. help
  1094. Allow attaching eBPF programs to a cgroup using the bpf(2)
  1095. syscall command BPF_PROG_ATTACH.
  1096. In which context these programs are accessed depends on the type
  1097. of attachment. For instance, programs that are attached using
  1098. BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
  1099. inet sockets.
  1100. config CGROUP_MISC
  1101. bool "Misc resource controller"
  1102. default n
  1103. help
  1104. Provides a controller for miscellaneous resources on a host.
  1105. Miscellaneous scalar resources are the resources on the host system
  1106. which cannot be abstracted like the other cgroups. This controller
  1107. tracks and limits the miscellaneous resources used by a process
  1108. attached to a cgroup hierarchy.
  1109. For more information, please check misc cgroup section in
  1110. /Documentation/admin-guide/cgroup-v2.rst.
  1111. config CGROUP_DEBUG
  1112. bool "Debug controller"
  1113. default n
  1114. depends on DEBUG_KERNEL
  1115. help
  1116. This option enables a simple controller that exports
  1117. debugging information about the cgroups framework. This
  1118. controller is for control cgroup debugging only. Its
  1119. interfaces are not stable.
  1120. Say N.
  1121. config SOCK_CGROUP_DATA
  1122. bool
  1123. default n
  1124. endif # CGROUPS
  1125. menuconfig NAMESPACES
  1126. bool "Namespaces support" if EXPERT
  1127. depends on MULTIUSER
  1128. default !EXPERT
  1129. help
  1130. Provides the way to make tasks work with different objects using
  1131. the same id. For example same IPC id may refer to different objects
  1132. or same user id or pid may refer to different tasks when used in
  1133. different namespaces.
  1134. if NAMESPACES
  1135. config UTS_NS
  1136. bool "UTS namespace"
  1137. default y
  1138. help
  1139. In this namespace tasks see different info provided with the
  1140. uname() system call
  1141. config TIME_NS
  1142. bool "TIME namespace"
  1143. depends on GENERIC_GETTIMEOFDAY
  1144. default y
  1145. help
  1146. In this namespace boottime and monotonic clocks can be set.
  1147. The time will keep going with the same pace.
  1148. config IPC_NS
  1149. bool "IPC namespace"
  1150. depends on (SYSVIPC || POSIX_MQUEUE)
  1151. default y
  1152. help
  1153. In this namespace tasks work with IPC ids which correspond to
  1154. different IPC objects in different namespaces.
  1155. config USER_NS
  1156. bool "User namespace"
  1157. default n
  1158. help
  1159. This allows containers, i.e. vservers, to use user namespaces
  1160. to provide different user info for different servers.
  1161. When user namespaces are enabled in the kernel it is
  1162. recommended that the MEMCG option also be enabled and that
  1163. user-space use the memory control groups to limit the amount
  1164. of memory a memory unprivileged users can use.
  1165. If unsure, say N.
  1166. config PID_NS
  1167. bool "PID Namespaces"
  1168. default y
  1169. help
  1170. Support process id namespaces. This allows having multiple
  1171. processes with the same pid as long as they are in different
  1172. pid namespaces. This is a building block of containers.
  1173. config NET_NS
  1174. bool "Network namespace"
  1175. depends on NET
  1176. default y
  1177. help
  1178. Allow user space to create what appear to be multiple instances
  1179. of the network stack.
  1180. endif # NAMESPACES
  1181. config CHECKPOINT_RESTORE
  1182. bool "Checkpoint/restore support"
  1183. depends on PROC_FS
  1184. select PROC_CHILDREN
  1185. select KCMP
  1186. default n
  1187. help
  1188. Enables additional kernel features in a sake of checkpoint/restore.
  1189. In particular it adds auxiliary prctl codes to setup process text,
  1190. data and heap segment sizes, and a few additional /proc filesystem
  1191. entries.
  1192. If unsure, say N here.
  1193. config SCHED_AUTOGROUP
  1194. bool "Automatic process group scheduling"
  1195. select CGROUPS
  1196. select CGROUP_SCHED
  1197. select FAIR_GROUP_SCHED
  1198. help
  1199. This option optimizes the scheduler for common desktop workloads by
  1200. automatically creating and populating task groups. This separation
  1201. of workloads isolates aggressive CPU burners (like build jobs) from
  1202. desktop applications. Task group autogeneration is currently based
  1203. upon task session.
  1204. config RELAY
  1205. bool "Kernel->user space relay support (formerly relayfs)"
  1206. select IRQ_WORK
  1207. help
  1208. This option enables support for relay interface support in
  1209. certain file systems (such as debugfs).
  1210. It is designed to provide an efficient mechanism for tools and
  1211. facilities to relay large amounts of data from kernel space to
  1212. user space.
  1213. If unsure, say N.
  1214. config BLK_DEV_INITRD
  1215. bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
  1216. help
  1217. The initial RAM filesystem is a ramfs which is loaded by the
  1218. boot loader (loadlin or lilo) and that is mounted as root
  1219. before the normal boot procedure. It is typically used to
  1220. load modules needed to mount the "real" root file system,
  1221. etc. See <file:Documentation/admin-guide/initrd.rst> for details.
  1222. If RAM disk support (BLK_DEV_RAM) is also included, this
  1223. also enables initial RAM disk (initrd) support and adds
  1224. 15 Kbytes (more on some other architectures) to the kernel size.
  1225. If unsure say Y.
  1226. if BLK_DEV_INITRD
  1227. source "usr/Kconfig"
  1228. endif
  1229. config BOOT_CONFIG
  1230. bool "Boot config support"
  1231. select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED
  1232. help
  1233. Extra boot config allows system admin to pass a config file as
  1234. complemental extension of kernel cmdline when booting.
  1235. The boot config file must be attached at the end of initramfs
  1236. with checksum, size and magic word.
  1237. See <file:Documentation/admin-guide/bootconfig.rst> for details.
  1238. If unsure, say Y.
  1239. config BOOT_CONFIG_FORCE
  1240. bool "Force unconditional bootconfig processing"
  1241. depends on BOOT_CONFIG
  1242. default y if BOOT_CONFIG_EMBED
  1243. help
  1244. With this Kconfig option set, BOOT_CONFIG processing is carried
  1245. out even when the "bootconfig" kernel-boot parameter is omitted.
  1246. In fact, with this Kconfig option set, there is no way to
  1247. make the kernel ignore the BOOT_CONFIG-supplied kernel-boot
  1248. parameters.
  1249. If unsure, say N.
  1250. config BOOT_CONFIG_EMBED
  1251. bool "Embed bootconfig file in the kernel"
  1252. depends on BOOT_CONFIG
  1253. help
  1254. Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the
  1255. kernel. Usually, the bootconfig file is loaded with the initrd
  1256. image. But if the system doesn't support initrd, this option will
  1257. help you by embedding a bootconfig file while building the kernel.
  1258. If unsure, say N.
  1259. config BOOT_CONFIG_EMBED_FILE
  1260. string "Embedded bootconfig file path"
  1261. depends on BOOT_CONFIG_EMBED
  1262. help
  1263. Specify a bootconfig file which will be embedded to the kernel.
  1264. This bootconfig will be used if there is no initrd or no other
  1265. bootconfig in the initrd.
  1266. config CMDLINE_LOG_WRAP_IDEAL_LEN
  1267. int "Length to try to wrap the cmdline when logged at boot"
  1268. default 1021
  1269. range 0 1021
  1270. help
  1271. At boot time, the kernel command line is logged to the console.
  1272. The log message will start with the prefix "Kernel command line: ".
  1273. The log message will attempt to be wrapped (split into multiple log
  1274. messages) at spaces based on CMDLINE_LOG_WRAP_IDEAL_LEN characters.
  1275. If wrapping happens, each log message will start with the prefix and
  1276. all but the last message will end with " \". Messages may exceed the
  1277. ideal length if a place to wrap isn't found before the specified
  1278. number of characters.
  1279. A value of 0 disables wrapping, though be warned that the maximum
  1280. length of a log message (1021 characters) may cause the cmdline to
  1281. be truncated.
  1282. config INITRAMFS_PRESERVE_MTIME
  1283. bool "Preserve cpio archive mtimes in initramfs"
  1284. depends on BLK_DEV_INITRD
  1285. default y
  1286. help
  1287. Each entry in an initramfs cpio archive carries an mtime value. When
  1288. enabled, extracted cpio items take this mtime, with directory mtime
  1289. setting deferred until after creation of any child entries.
  1290. If unsure, say Y.
  1291. config INITRAMFS_TEST
  1292. bool "Test initramfs cpio archive extraction" if !KUNIT_ALL_TESTS
  1293. depends on BLK_DEV_INITRD && KUNIT=y
  1294. default KUNIT_ALL_TESTS
  1295. help
  1296. Build KUnit tests for initramfs. See Documentation/dev-tools/kunit
  1297. choice
  1298. prompt "Compiler optimization level"
  1299. default CC_OPTIMIZE_FOR_PERFORMANCE
  1300. config CC_OPTIMIZE_FOR_PERFORMANCE
  1301. bool "Optimize for performance (-O2)"
  1302. help
  1303. This is the default optimization level for the kernel, building
  1304. with the "-O2" compiler flag for best performance and most
  1305. helpful compile-time warnings.
  1306. config CC_OPTIMIZE_FOR_SIZE
  1307. bool "Optimize for size (-Os)"
  1308. help
  1309. Choosing this option will pass "-Os" to your compiler resulting
  1310. in a smaller kernel.
  1311. endchoice
  1312. config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
  1313. bool
  1314. help
  1315. This requires that the arch annotates or otherwise protects
  1316. its external entry points from being discarded. Linker scripts
  1317. must also merge .text.*, .data.*, and .bss.* correctly into
  1318. output sections. Care must be taken not to pull in unrelated
  1319. sections (e.g., '.text.init'). Typically '.' in section names
  1320. is used to distinguish them from label names / C identifiers.
  1321. config LD_DEAD_CODE_DATA_ELIMINATION
  1322. bool "Dead code and data elimination (EXPERIMENTAL)"
  1323. depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
  1324. depends on EXPERT
  1325. depends on $(cc-option,-ffunction-sections -fdata-sections)
  1326. depends on $(ld-option,--gc-sections)
  1327. help
  1328. Enable this if you want to do dead code and data elimination with
  1329. the linker by compiling with -ffunction-sections -fdata-sections,
  1330. and linking with --gc-sections.
  1331. This can reduce on disk and in-memory size of the kernel
  1332. code and static data, particularly for small configs and
  1333. on small systems. This has the possibility of introducing
  1334. silently broken kernel if the required annotations are not
  1335. present. This option is not well tested yet, so use at your
  1336. own risk.
  1337. config LD_ORPHAN_WARN
  1338. def_bool y
  1339. depends on ARCH_WANT_LD_ORPHAN_WARN
  1340. depends on $(ld-option,--orphan-handling=warn)
  1341. depends on $(ld-option,--orphan-handling=error)
  1342. config LD_ORPHAN_WARN_LEVEL
  1343. string
  1344. depends on LD_ORPHAN_WARN
  1345. default "error" if WERROR
  1346. default "warn"
  1347. config SYSCTL
  1348. bool
  1349. config HAVE_UID16
  1350. bool
  1351. config SYSCTL_EXCEPTION_TRACE
  1352. bool
  1353. help
  1354. Enable support for /proc/sys/debug/exception-trace.
  1355. config SYSCTL_ARCH_UNALIGN_NO_WARN
  1356. bool
  1357. help
  1358. Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
  1359. Allows arch to define/use @no_unaligned_warning to possibly warn
  1360. about unaligned access emulation going on under the hood.
  1361. config SYSCTL_ARCH_UNALIGN_ALLOW
  1362. bool
  1363. help
  1364. Enable support for /proc/sys/kernel/unaligned-trap
  1365. Allows arches to define/use @unaligned_enabled to runtime toggle
  1366. the unaligned access emulation.
  1367. see arch/parisc/kernel/unaligned.c for reference
  1368. config SYSFS_SYSCALL
  1369. bool "Sysfs syscall support"
  1370. default n
  1371. help
  1372. sys_sysfs is an obsolete system call no longer supported in libc.
  1373. Note that disabling this option is more secure but might break
  1374. compatibility with some systems.
  1375. If unsure say N here.
  1376. config HAVE_PCSPKR_PLATFORM
  1377. bool
  1378. menuconfig EXPERT
  1379. bool "Configure standard kernel features (expert users)"
  1380. # Unhide debug options, to make the on-by-default options visible
  1381. select DEBUG_KERNEL
  1382. help
  1383. This option allows certain base kernel options and settings
  1384. to be disabled or tweaked. This is for specialized
  1385. environments which can tolerate a "non-standard" kernel.
  1386. Only use this if you really know what you are doing.
  1387. config UID16
  1388. bool "Enable 16-bit UID system calls" if EXPERT
  1389. depends on HAVE_UID16 && MULTIUSER
  1390. default y
  1391. help
  1392. This enables the legacy 16-bit UID syscall wrappers.
  1393. config MULTIUSER
  1394. bool "Multiple users, groups and capabilities support" if EXPERT
  1395. default y
  1396. help
  1397. This option enables support for non-root users, groups and
  1398. capabilities.
  1399. If you say N here, all processes will run with UID 0, GID 0, and all
  1400. possible capabilities. Saying N here also compiles out support for
  1401. system calls related to UIDs, GIDs, and capabilities, such as setuid,
  1402. setgid, and capset.
  1403. If unsure, say Y here.
  1404. config SGETMASK_SYSCALL
  1405. bool "sgetmask/ssetmask syscalls support" if EXPERT
  1406. default PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
  1407. help
  1408. sys_sgetmask and sys_ssetmask are obsolete system calls
  1409. no longer supported in libc but still enabled by default in some
  1410. architectures.
  1411. If unsure, leave the default option here.
  1412. config FHANDLE
  1413. bool "open by fhandle syscalls" if EXPERT
  1414. select EXPORTFS
  1415. default y
  1416. help
  1417. If you say Y here, a user level program will be able to map
  1418. file names to handle and then later use the handle for
  1419. different file system operations. This is useful in implementing
  1420. userspace file servers, which now track files using handles instead
  1421. of names. The handle would remain the same even if file names
  1422. get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
  1423. syscalls.
  1424. config POSIX_TIMERS
  1425. bool "Posix Clocks & timers" if EXPERT
  1426. default y
  1427. help
  1428. This includes native support for POSIX timers to the kernel.
  1429. Some embedded systems have no use for them and therefore they
  1430. can be configured out to reduce the size of the kernel image.
  1431. When this option is disabled, the following syscalls won't be
  1432. available: timer_create, timer_gettime: timer_getoverrun,
  1433. timer_settime, timer_delete, clock_adjtime, getitimer,
  1434. setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
  1435. clock_getres and clock_nanosleep syscalls will be limited to
  1436. CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
  1437. If unsure say y.
  1438. config PRINTK
  1439. default y
  1440. bool "Enable support for printk" if EXPERT
  1441. select IRQ_WORK
  1442. help
  1443. This option enables normal printk support. Removing it
  1444. eliminates most of the message strings from the kernel image
  1445. and makes the kernel more or less silent. As this makes it
  1446. very difficult to diagnose system problems, saying N here is
  1447. strongly discouraged.
  1448. config PRINTK_RINGBUFFER_KUNIT_TEST
  1449. tristate "KUnit Test for the printk ringbuffer" if !KUNIT_ALL_TESTS
  1450. depends on PRINTK && KUNIT
  1451. default KUNIT_ALL_TESTS
  1452. help
  1453. This builds the printk ringbuffer KUnit test suite.
  1454. For more information on KUnit and unit tests in general, please refer
  1455. to the KUnit documentation.
  1456. If unsure, say N.
  1457. config BUG
  1458. bool "BUG() support" if EXPERT
  1459. default y
  1460. help
  1461. Disabling this option eliminates support for BUG and WARN, reducing
  1462. the size of your kernel image and potentially quietly ignoring
  1463. numerous fatal conditions. You should only consider disabling this
  1464. option for embedded systems with no facilities for reporting errors.
  1465. Just say Y.
  1466. config ELF_CORE
  1467. depends on COREDUMP
  1468. default y
  1469. bool "Enable ELF core dumps" if EXPERT
  1470. help
  1471. Enable support for generating core dumps. Disabling saves about 4k.
  1472. config PCSPKR_PLATFORM
  1473. bool "Enable PC-Speaker support" if EXPERT
  1474. depends on HAVE_PCSPKR_PLATFORM
  1475. select I8253_LOCK
  1476. default y
  1477. help
  1478. This option allows to disable the internal PC-Speaker
  1479. support, saving some memory.
  1480. config BASE_SMALL
  1481. bool "Enable smaller-sized data structures for core" if EXPERT
  1482. help
  1483. Enabling this option reduces the size of miscellaneous core
  1484. kernel data structures. This saves memory on small machines,
  1485. but may reduce performance.
  1486. config FUTEX
  1487. bool "Enable futex support" if EXPERT
  1488. depends on !(SPARC32 && SMP)
  1489. default y
  1490. imply RT_MUTEXES
  1491. help
  1492. Disabling this option will cause the kernel to be built without
  1493. support for "fast userspace mutexes". The resulting kernel may not
  1494. run glibc-based applications correctly.
  1495. config FUTEX_PI
  1496. bool
  1497. depends on FUTEX && RT_MUTEXES
  1498. default y
  1499. config FUTEX_PRIVATE_HASH
  1500. bool
  1501. depends on FUTEX && !BASE_SMALL && MMU
  1502. default y
  1503. config FUTEX_MPOL
  1504. bool
  1505. depends on FUTEX && NUMA
  1506. default y
  1507. config EPOLL
  1508. bool "Enable eventpoll support" if EXPERT
  1509. default y
  1510. help
  1511. Disabling this option will cause the kernel to be built without
  1512. support for epoll family of system calls.
  1513. config SIGNALFD
  1514. bool "Enable signalfd() system call" if EXPERT
  1515. default y
  1516. help
  1517. Enable the signalfd() system call that allows to receive signals
  1518. on a file descriptor.
  1519. If unsure, say Y.
  1520. config TIMERFD
  1521. bool "Enable timerfd() system call" if EXPERT
  1522. default y
  1523. help
  1524. Enable the timerfd() system call that allows to receive timer
  1525. events on a file descriptor.
  1526. If unsure, say Y.
  1527. config EVENTFD
  1528. bool "Enable eventfd() system call" if EXPERT
  1529. default y
  1530. help
  1531. Enable the eventfd() system call that allows to receive both
  1532. kernel notification (ie. KAIO) or userspace notifications.
  1533. If unsure, say Y.
  1534. config SHMEM
  1535. bool "Use full shmem filesystem" if EXPERT
  1536. default y
  1537. depends on MMU
  1538. help
  1539. The shmem is an internal filesystem used to manage shared memory.
  1540. It is backed by swap and manages resource limits. It is also exported
  1541. to userspace as tmpfs if TMPFS is enabled. Disabling this
  1542. option replaces shmem and tmpfs with the much simpler ramfs code,
  1543. which may be appropriate on small systems without swap.
  1544. config AIO
  1545. bool "Enable AIO support" if EXPERT
  1546. default y
  1547. help
  1548. This option enables POSIX asynchronous I/O which may by used
  1549. by some high performance threaded applications. Disabling
  1550. this option saves about 7k.
  1551. config IO_URING
  1552. bool "Enable IO uring support" if EXPERT
  1553. select IO_WQ
  1554. default y
  1555. help
  1556. This option enables support for the io_uring interface, enabling
  1557. applications to submit and complete IO through submission and
  1558. completion rings that are shared between the kernel and application.
  1559. config GCOV_PROFILE_URING
  1560. bool "Enable GCOV profiling on the io_uring subsystem"
  1561. depends on IO_URING && GCOV_KERNEL
  1562. help
  1563. Enable GCOV profiling on the io_uring subsystem, to facilitate
  1564. code coverage testing.
  1565. If unsure, say N.
  1566. Note that this will have a negative impact on the performance of
  1567. the io_uring subsystem, hence this should only be enabled for
  1568. specific test purposes.
  1569. config IO_URING_MOCK_FILE
  1570. tristate "Enable io_uring mock files (Experimental)" if EXPERT
  1571. default n
  1572. depends on IO_URING
  1573. help
  1574. Enable mock files for io_uring subsystem testing. The ABI might
  1575. still change, so it's still experimental and should only be enabled
  1576. for specific test purposes.
  1577. If unsure, say N.
  1578. config ADVISE_SYSCALLS
  1579. bool "Enable madvise/fadvise syscalls" if EXPERT
  1580. default y
  1581. help
  1582. This option enables the madvise and fadvise syscalls, used by
  1583. applications to advise the kernel about their future memory or file
  1584. usage, improving performance. If building an embedded system where no
  1585. applications use these syscalls, you can disable this option to save
  1586. space.
  1587. config MEMBARRIER
  1588. bool "Enable membarrier() system call" if EXPERT
  1589. default y
  1590. help
  1591. Enable the membarrier() system call that allows issuing memory
  1592. barriers across all running threads, which can be used to distribute
  1593. the cost of user-space memory barriers asymmetrically by transforming
  1594. pairs of memory barriers into pairs consisting of membarrier() and a
  1595. compiler barrier.
  1596. If unsure, say Y.
  1597. config KCMP
  1598. bool "Enable kcmp() system call" if EXPERT
  1599. help
  1600. Enable the kernel resource comparison system call. It provides
  1601. user-space with the ability to compare two processes to see if they
  1602. share a common resource, such as a file descriptor or even virtual
  1603. memory space.
  1604. If unsure, say N.
  1605. config RSEQ
  1606. bool "Enable rseq() system call" if EXPERT
  1607. default y
  1608. depends on HAVE_RSEQ
  1609. select MEMBARRIER
  1610. help
  1611. Enable the restartable sequences system call. It provides a
  1612. user-space cache for the current CPU number value, which
  1613. speeds up getting the current CPU number from user-space,
  1614. as well as an ABI to speed up user-space operations on
  1615. per-CPU data.
  1616. If unsure, say Y.
  1617. config RSEQ_SLICE_EXTENSION
  1618. bool "Enable rseq-based time slice extension mechanism"
  1619. depends on RSEQ && HIGH_RES_TIMERS && GENERIC_ENTRY && HAVE_GENERIC_TIF_BITS
  1620. help
  1621. Allows userspace to request a limited time slice extension when
  1622. returning from an interrupt to user space via the RSEQ shared
  1623. data ABI. If granted, that allows to complete a critical section,
  1624. so that other threads are not stuck on a conflicted resource,
  1625. while the task is scheduled out.
  1626. If unsure, say N.
  1627. config RSEQ_STATS
  1628. default n
  1629. bool "Enable lightweight statistics of restartable sequences" if EXPERT
  1630. depends on RSEQ && DEBUG_FS
  1631. help
  1632. Enable lightweight counters which expose information about the
  1633. frequency of RSEQ operations via debugfs. Mostly interesting for
  1634. kernel debugging or performance analysis. While lightweight it's
  1635. still adding code into the user/kernel mode transitions.
  1636. If unsure, say N.
  1637. config RSEQ_DEBUG_DEFAULT_ENABLE
  1638. default n
  1639. bool "Enable restartable sequences debug mode by default" if EXPERT
  1640. depends on RSEQ
  1641. help
  1642. This enables the static branch for debug mode of restartable
  1643. sequences.
  1644. This also can be controlled on the kernel command line via the
  1645. command line parameter "rseq_debug=0/1" and through debugfs.
  1646. If unsure, say N.
  1647. config DEBUG_RSEQ
  1648. default n
  1649. bool "Enable debugging of rseq() system call" if EXPERT
  1650. depends on RSEQ && DEBUG_KERNEL && !GENERIC_ENTRY
  1651. select RSEQ_DEBUG_DEFAULT_ENABLE
  1652. help
  1653. Enable extra debugging checks for the rseq system call.
  1654. If unsure, say N.
  1655. config CACHESTAT_SYSCALL
  1656. bool "Enable cachestat() system call" if EXPERT
  1657. default y
  1658. help
  1659. Enable the cachestat system call, which queries the page cache
  1660. statistics of a file (number of cached pages, dirty pages,
  1661. pages marked for writeback, (recently) evicted pages).
  1662. If unsure say Y here.
  1663. config KALLSYMS
  1664. bool "Load all symbols for debugging/ksymoops" if EXPERT
  1665. default y
  1666. help
  1667. Say Y here to let the kernel print out symbolic crash information and
  1668. symbolic stack backtraces. This increases the size of the kernel
  1669. somewhat, as all symbols have to be loaded into the kernel image.
  1670. config KALLSYMS_SELFTEST
  1671. bool "Test the basic functions and performance of kallsyms"
  1672. depends on KALLSYMS
  1673. default n
  1674. help
  1675. Test the basic functions and performance of some interfaces, such as
  1676. kallsyms_lookup_name. It also calculates the compression rate of the
  1677. kallsyms compression algorithm for the current symbol set.
  1678. Start self-test automatically after system startup. Suggest executing
  1679. "dmesg | grep kallsyms_selftest" to collect test results. "finish" is
  1680. displayed in the last line, indicating that the test is complete.
  1681. config KALLSYMS_ALL
  1682. bool "Include all symbols in kallsyms"
  1683. depends on DEBUG_KERNEL && KALLSYMS
  1684. help
  1685. Normally kallsyms only contains the symbols of functions for nicer
  1686. OOPS messages and backtraces (i.e., symbols from the text and inittext
  1687. sections). This is sufficient for most cases. And only if you want to
  1688. enable kernel live patching, or other less common use cases (e.g.,
  1689. when a debugger is used) all symbols are required (i.e., names of
  1690. variables from the data sections, etc).
  1691. This option makes sure that all symbols are loaded into the kernel
  1692. image (i.e., symbols from all sections) in cost of increased kernel
  1693. size (depending on the kernel configuration, it may be 300KiB or
  1694. something like this).
  1695. Say N unless you really need all symbols, or kernel live patching.
  1696. # end of the "standard kernel features (expert users)" menu
  1697. config ARCH_HAS_MEMBARRIER_CALLBACKS
  1698. bool
  1699. config ARCH_HAS_MEMBARRIER_SYNC_CORE
  1700. bool
  1701. config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS
  1702. bool
  1703. help
  1704. Control MSEAL_SYSTEM_MAPPINGS access based on architecture.
  1705. A 64-bit kernel is required for the memory sealing feature.
  1706. No specific hardware features from the CPU are needed.
  1707. To enable this feature, the architecture needs to update their
  1708. special mappings calls to include the sealing flag and confirm
  1709. that it doesn't unmap/remap system mappings during the life
  1710. time of the process. The existence of this flag for an architecture
  1711. implies that it does not require the remapping of the system
  1712. mappings during process lifetime, so sealing these mappings is safe
  1713. from a kernel perspective.
  1714. After the architecture enables this, a distribution can set
  1715. CONFIG_MSEAL_SYSTEM_MAPPING to manage access to the feature.
  1716. For complete descriptions of memory sealing, please see
  1717. Documentation/userspace-api/mseal.rst
  1718. config HAVE_PERF_EVENTS
  1719. bool
  1720. help
  1721. See tools/perf/design.txt for details.
  1722. config GUEST_PERF_EVENTS
  1723. bool
  1724. depends on HAVE_PERF_EVENTS
  1725. config PERF_GUEST_MEDIATED_PMU
  1726. bool
  1727. depends on GUEST_PERF_EVENTS
  1728. config PERF_USE_VMALLOC
  1729. bool
  1730. help
  1731. See tools/perf/design.txt for details
  1732. menu "Kernel Performance Events And Counters"
  1733. config PERF_EVENTS
  1734. bool "Kernel performance events and counters"
  1735. default y if PROFILING
  1736. depends on HAVE_PERF_EVENTS
  1737. select IRQ_WORK
  1738. help
  1739. Enable kernel support for various performance events provided
  1740. by software and hardware.
  1741. Software events are supported either built-in or via the
  1742. use of generic tracepoints.
  1743. Most modern CPUs support performance events via performance
  1744. counter registers. These registers count the number of certain
  1745. types of hw events: such as instructions executed, cachemisses
  1746. suffered, or branches mis-predicted - without slowing down the
  1747. kernel or applications. These registers can also trigger interrupts
  1748. when a threshold number of events have passed - and can thus be
  1749. used to profile the code that runs on that CPU.
  1750. The Linux Performance Event subsystem provides an abstraction of
  1751. these software and hardware event capabilities, available via a
  1752. system call and used by the "perf" utility in tools/perf/. It
  1753. provides per task and per CPU counters, and it provides event
  1754. capabilities on top of those.
  1755. Say Y if unsure.
  1756. config DEBUG_PERF_USE_VMALLOC
  1757. default n
  1758. bool "Debug: use vmalloc to back perf mmap() buffers"
  1759. depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
  1760. select PERF_USE_VMALLOC
  1761. help
  1762. Use vmalloc memory to back perf mmap() buffers.
  1763. Mostly useful for debugging the vmalloc code on platforms
  1764. that don't require it.
  1765. Say N if unsure.
  1766. endmenu
  1767. config SYSTEM_DATA_VERIFICATION
  1768. def_bool n
  1769. select SYSTEM_TRUSTED_KEYRING
  1770. select KEYS
  1771. select CRYPTO
  1772. select CRYPTO_RSA
  1773. select ASYMMETRIC_KEY_TYPE
  1774. select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
  1775. select ASN1
  1776. select OID_REGISTRY
  1777. select X509_CERTIFICATE_PARSER
  1778. select PKCS7_MESSAGE_PARSER
  1779. help
  1780. Provide PKCS#7 message verification using the contents of the system
  1781. trusted keyring to provide public keys. This then can be used for
  1782. module verification, kexec image verification and firmware blob
  1783. verification.
  1784. config PROFILING
  1785. bool "Profiling support"
  1786. help
  1787. Say Y here to enable the extended profiling support mechanisms used
  1788. by profilers.
  1789. config RUST
  1790. bool "Rust support"
  1791. depends on HAVE_RUST
  1792. depends on RUST_IS_AVAILABLE
  1793. select EXTENDED_MODVERSIONS if MODVERSIONS
  1794. depends on !MODVERSIONS || GENDWARFKSYMS
  1795. depends on !GCC_PLUGIN_RANDSTRUCT
  1796. depends on !RANDSTRUCT
  1797. depends on !DEBUG_INFO_BTF || (PAHOLE_HAS_LANG_EXCLUDE && !LTO)
  1798. depends on !CFI || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC
  1799. select CFI_ICALL_NORMALIZE_INTEGERS if CFI
  1800. depends on !CALL_PADDING || RUSTC_VERSION >= 108100
  1801. depends on !KASAN_SW_TAGS
  1802. depends on !(MITIGATION_RETHUNK && KASAN) || RUSTC_VERSION >= 108300
  1803. help
  1804. Enables Rust support in the kernel.
  1805. This allows other Rust-related options, like drivers written in Rust,
  1806. to be selected.
  1807. It is also required to be able to load external kernel modules
  1808. written in Rust.
  1809. See Documentation/rust/ for more information.
  1810. If unsure, say N.
  1811. config RUSTC_VERSION_TEXT
  1812. string
  1813. depends on RUST
  1814. default "$(RUSTC_VERSION_TEXT)"
  1815. help
  1816. See `CC_VERSION_TEXT`.
  1817. config BINDGEN_VERSION_TEXT
  1818. string
  1819. depends on RUST
  1820. # The dummy parameter `workaround-for-0.69.0` is required to support 0.69.0
  1821. # (https://github.com/rust-lang/rust-bindgen/pull/2678) and 0.71.0
  1822. # (https://github.com/rust-lang/rust-bindgen/pull/3040). It can be removed
  1823. # when the minimum version is upgraded past the latter (0.69.1 and 0.71.1
  1824. # both fixed the issue).
  1825. default "$(shell,$(BINDGEN) --version workaround-for-0.69.0 2>/dev/null)"
  1826. #
  1827. # Place an empty function call at each tracepoint site. Can be
  1828. # dynamically changed for a probe function.
  1829. #
  1830. config TRACEPOINTS
  1831. bool
  1832. select TASKS_TRACE_RCU
  1833. source "kernel/Kconfig.kexec"
  1834. source "kernel/liveupdate/Kconfig"
  1835. endmenu # General setup
  1836. source "arch/Kconfig"
  1837. config RT_MUTEXES
  1838. bool
  1839. default y if PREEMPT_RT
  1840. config MODULE_SIG_FORMAT
  1841. def_bool n
  1842. select SYSTEM_DATA_VERIFICATION
  1843. source "kernel/module/Kconfig"
  1844. config INIT_ALL_POSSIBLE
  1845. bool
  1846. help
  1847. Back when each arch used to define their own cpu_online_mask and
  1848. cpu_possible_mask, some of them chose to initialize cpu_possible_mask
  1849. with all 1s, and others with all 0s. When they were centralised,
  1850. it was better to provide this option than to break all the archs
  1851. and have several arch maintainers pursuing me down dark alleys.
  1852. source "block/Kconfig"
  1853. config PREEMPT_NOTIFIERS
  1854. bool
  1855. config PADATA
  1856. depends on SMP
  1857. bool
  1858. config ASN1
  1859. tristate
  1860. help
  1861. Build a simple ASN.1 grammar compiler that produces a bytecode output
  1862. that can be interpreted by the ASN.1 stream decoder and used to
  1863. inform it as to what tags are to be expected in a stream and what
  1864. functions to call on what tags.
  1865. source "kernel/Kconfig.locks"
  1866. config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
  1867. bool
  1868. config ARCH_HAS_PREPARE_SYNC_CORE_CMD
  1869. bool
  1870. config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
  1871. bool
  1872. # It may be useful for an architecture to override the definitions of the
  1873. # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
  1874. # and the COMPAT_ variants in <linux/compat.h>, in particular to use a
  1875. # different calling convention for syscalls. They can also override the
  1876. # macros for not-implemented syscalls in kernel/sys_ni.c and
  1877. # kernel/time/posix-stubs.c. All these overrides need to be available in
  1878. # <asm/syscall_wrapper.h>.
  1879. config ARCH_HAS_SYSCALL_WRAPPER
  1880. def_bool n