Kconfig 64 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 RUST_IS_AVAILABLE
  50. def_bool $(success,$(srctree)/scripts/rust_is_available.sh)
  51. help
  52. This shows whether a suitable Rust toolchain is available (found).
  53. Please see Documentation/rust/quick-start.rst for instructions on how
  54. to satisfy the build requirements of Rust support.
  55. In particular, the Makefile target 'rustavailable' is useful to check
  56. why the Rust toolchain is not being detected.
  57. config CC_CAN_LINK
  58. bool
  59. default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag)) if 64BIT
  60. default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag))
  61. config CC_CAN_LINK_STATIC
  62. bool
  63. default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag) -static) if 64BIT
  64. default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag) -static)
  65. config CC_HAS_ASM_GOTO_OUTPUT
  66. 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)
  67. config CC_HAS_ASM_GOTO_TIED_OUTPUT
  68. depends on CC_HAS_ASM_GOTO_OUTPUT
  69. # Detect buggy gcc and clang, fixed in gcc-11 clang-14.
  70. 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)
  71. config TOOLS_SUPPORT_RELR
  72. def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
  73. config CC_HAS_ASM_INLINE
  74. def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
  75. config CC_HAS_NO_PROFILE_FN_ATTR
  76. def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
  77. config PAHOLE_VERSION
  78. int
  79. default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE))
  80. config CONSTRUCTORS
  81. bool
  82. config IRQ_WORK
  83. bool
  84. config BUILDTIME_TABLE_SORT
  85. bool
  86. config 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. One subtle change that will be needed is to use try_get_task_stack()
  93. and put_task_stack() in save_thread_stack_tsk() and get_wchan().
  94. menu "General setup"
  95. config BROKEN
  96. bool
  97. config BROKEN_ON_SMP
  98. bool
  99. depends on BROKEN || !SMP
  100. default y
  101. config INIT_ENV_ARG_LIMIT
  102. int
  103. default 32 if !UML
  104. default 128 if UML
  105. help
  106. Maximum of each of the number of arguments and environment
  107. variables passed to init from the kernel command line.
  108. config COMPILE_TEST
  109. bool "Compile also drivers which will not load"
  110. depends on HAS_IOMEM
  111. help
  112. Some drivers can be compiled on a different platform than they are
  113. intended to be run on. Despite they cannot be loaded there (or even
  114. when they load they cannot be used due to missing HW support),
  115. developers still, opposing to distributors, might want to build such
  116. drivers to compile-test them.
  117. If you are a developer and want to build everything available, say Y
  118. here. If you are a user/distributor, say N here to exclude useless
  119. drivers to be distributed.
  120. config WERROR
  121. bool "Compile the kernel with warnings as errors"
  122. default y
  123. help
  124. A kernel build should not cause any compiler warnings, and this
  125. enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags
  126. to enforce that rule by default.
  127. However, if you have a new (or very old) compiler with odd and
  128. unusual warnings, or you have some architecture with problems,
  129. you may need to disable this config option in order to
  130. successfully build the kernel.
  131. If in doubt, say Y.
  132. config UAPI_HEADER_TEST
  133. bool "Compile test UAPI headers"
  134. depends on HEADERS_INSTALL && CC_CAN_LINK
  135. help
  136. Compile test headers exported to user-space to ensure they are
  137. self-contained, i.e. compilable as standalone units.
  138. If you are a developer or tester and want to ensure the exported
  139. headers are self-contained, say Y here. Otherwise, choose N.
  140. config LOCALVERSION
  141. string "Local version - append to kernel release"
  142. help
  143. Append an extra string to the end of your kernel version.
  144. This will show up when you type uname, for example.
  145. The string you set here will be appended after the contents of
  146. any files with a filename matching localversion* in your
  147. object and source tree, in that order. Your total string can
  148. be a maximum of 64 characters.
  149. config 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. A string of the format -gxxxxxxxx will be added to the localversion
  158. if a git-based tree is found. The string generated by this will be
  159. appended after any matching localversion* files, and after the value
  160. set in CONFIG_LOCALVERSION.
  161. (The actual string used here is the first eight characters produced
  162. by running the command:
  163. $ git rev-parse --verify HEAD
  164. which is done within the script "scripts/setlocalversion".)
  165. config BUILD_SALT
  166. string "Build ID Salt"
  167. default ""
  168. help
  169. The build ID is used to link binaries and their debug info. Setting
  170. this option will use the value in the calculation of the build id.
  171. This is mostly useful for distributions which want to ensure the
  172. build is unique between builds. It's safe to leave the default.
  173. config HAVE_KERNEL_GZIP
  174. bool
  175. config HAVE_KERNEL_BZIP2
  176. bool
  177. config HAVE_KERNEL_LZMA
  178. bool
  179. config HAVE_KERNEL_XZ
  180. bool
  181. config HAVE_KERNEL_LZO
  182. bool
  183. config HAVE_KERNEL_LZ4
  184. bool
  185. config HAVE_KERNEL_ZSTD
  186. bool
  187. config HAVE_KERNEL_UNCOMPRESSED
  188. bool
  189. choice
  190. prompt "Kernel compression mode"
  191. default KERNEL_GZIP
  192. 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
  193. help
  194. The linux kernel is a kind of self-extracting executable.
  195. Several compression algorithms are available, which differ
  196. in efficiency, compression and decompression speed.
  197. Compression speed is only relevant when building a kernel.
  198. Decompression speed is relevant at each boot.
  199. If you have any problems with bzip2 or lzma compressed
  200. kernels, mail me (Alain Knaff) <[email protected]>. (An older
  201. version of this functionality (bzip2 only), for 2.4, was
  202. supplied by Christian Ludwig)
  203. High compression options are mostly useful for users, who
  204. are low on disk space (embedded systems), but for whom ram
  205. size matters less.
  206. If in doubt, select 'gzip'
  207. config KERNEL_GZIP
  208. bool "Gzip"
  209. depends on HAVE_KERNEL_GZIP
  210. help
  211. The old and tried gzip compression. It provides a good balance
  212. between compression ratio and decompression speed.
  213. config KERNEL_BZIP2
  214. bool "Bzip2"
  215. depends on HAVE_KERNEL_BZIP2
  216. help
  217. Its compression ratio and speed is intermediate.
  218. Decompression speed is slowest among the choices. The kernel
  219. size is about 10% smaller with bzip2, in comparison to gzip.
  220. Bzip2 uses a large amount of memory. For modern kernels you
  221. will need at least 8MB RAM or more for booting.
  222. config KERNEL_LZMA
  223. bool "LZMA"
  224. depends on HAVE_KERNEL_LZMA
  225. help
  226. This compression algorithm's ratio is best. Decompression speed
  227. is between gzip and bzip2. Compression is slowest.
  228. The kernel size is about 33% smaller with LZMA in comparison to gzip.
  229. config KERNEL_XZ
  230. bool "XZ"
  231. depends on HAVE_KERNEL_XZ
  232. help
  233. XZ uses the LZMA2 algorithm and instruction set specific
  234. BCJ filters which can improve compression ratio of executable
  235. code. The size of the kernel is about 30% smaller with XZ in
  236. comparison to gzip. On architectures for which there is a BCJ
  237. filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
  238. will create a few percent smaller kernel than plain LZMA.
  239. The speed is about the same as with LZMA: The decompression
  240. speed of XZ is better than that of bzip2 but worse than gzip
  241. and LZO. Compression is slow.
  242. config KERNEL_LZO
  243. bool "LZO"
  244. depends on HAVE_KERNEL_LZO
  245. help
  246. Its compression ratio is the poorest among the choices. The kernel
  247. size is about 10% bigger than gzip; however its speed
  248. (both compression and decompression) is the fastest.
  249. config KERNEL_LZ4
  250. bool "LZ4"
  251. depends on HAVE_KERNEL_LZ4
  252. help
  253. LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
  254. A preliminary version of LZ4 de/compression tool is available at
  255. <https://code.google.com/p/lz4/>.
  256. Its compression ratio is worse than LZO. The size of the kernel
  257. is about 8% bigger than LZO. But the decompression speed is
  258. faster than LZO.
  259. config KERNEL_ZSTD
  260. bool "ZSTD"
  261. depends on HAVE_KERNEL_ZSTD
  262. help
  263. ZSTD is a compression algorithm targeting intermediate compression
  264. with fast decompression speed. It will compress better than GZIP and
  265. decompress around the same speed as LZO, but slower than LZ4. You
  266. will need at least 192 KB RAM or more for booting. The zstd command
  267. line tool is required for compression.
  268. config KERNEL_UNCOMPRESSED
  269. bool "None"
  270. depends on HAVE_KERNEL_UNCOMPRESSED
  271. help
  272. Produce uncompressed kernel image. This option is usually not what
  273. you want. It is useful for debugging the kernel in slow simulation
  274. environments, where decompressing and moving the kernel is awfully
  275. slow. This option allows early boot code to skip the decompressor
  276. and jump right at uncompressed kernel image.
  277. endchoice
  278. config DEFAULT_INIT
  279. string "Default init path"
  280. default ""
  281. help
  282. This option determines the default init for the system if no init=
  283. option is passed on the kernel command line. If the requested path is
  284. not present, we will still then move on to attempting further
  285. locations (e.g. /sbin/init, etc). If this is empty, we will just use
  286. the fallback list when init= is not passed.
  287. config DEFAULT_HOSTNAME
  288. string "Default hostname"
  289. default "(none)"
  290. help
  291. This option determines the default system hostname before userspace
  292. calls sethostname(2). The kernel traditionally uses "(none)" here,
  293. but you may wish to use a different default here to make a minimal
  294. system more usable with less configuration.
  295. config SYSVIPC
  296. bool "System V IPC"
  297. help
  298. Inter Process Communication is a suite of library functions and
  299. system calls which let processes (running programs) synchronize and
  300. exchange information. It is generally considered to be a good thing,
  301. and some programs won't run unless you say Y here. In particular, if
  302. you want to run the DOS emulator dosemu under Linux (read the
  303. DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
  304. you'll need to say Y here.
  305. You can find documentation about IPC with "info ipc" and also in
  306. section 6.4 of the Linux Programmer's Guide, available from
  307. <http://www.tldp.org/guides.html>.
  308. config SYSVIPC_SYSCTL
  309. bool
  310. depends on SYSVIPC
  311. depends on SYSCTL
  312. default y
  313. config SYSVIPC_COMPAT
  314. def_bool y
  315. depends on COMPAT && SYSVIPC
  316. config POSIX_MQUEUE
  317. bool "POSIX Message Queues"
  318. depends on NET
  319. help
  320. POSIX variant of message queues is a part of IPC. In POSIX message
  321. queues every message has a priority which decides about succession
  322. of receiving it by a process. If you want to compile and run
  323. programs written e.g. for Solaris with use of its POSIX message
  324. queues (functions mq_*) say Y here.
  325. POSIX message queues are visible as a filesystem called 'mqueue'
  326. and can be mounted somewhere if you want to do filesystem
  327. operations on message queues.
  328. If unsure, say Y.
  329. config POSIX_MQUEUE_SYSCTL
  330. bool
  331. depends on POSIX_MQUEUE
  332. depends on SYSCTL
  333. default y
  334. config WATCH_QUEUE
  335. bool "General notification queue"
  336. default n
  337. help
  338. This is a general notification queue for the kernel to pass events to
  339. userspace by splicing them into pipes. It can be used in conjunction
  340. with watches for key/keyring change notifications and device
  341. notifications.
  342. See Documentation/core-api/watch_queue.rst
  343. config CROSS_MEMORY_ATTACH
  344. bool "Enable process_vm_readv/writev syscalls"
  345. depends on MMU
  346. default y
  347. help
  348. Enabling this option adds the system calls process_vm_readv and
  349. process_vm_writev which allow a process with the correct privileges
  350. to directly read from or write to another process' address space.
  351. See the man page for more details.
  352. config USELIB
  353. bool "uselib syscall (for libc5 and earlier)"
  354. default ALPHA || M68K || SPARC
  355. help
  356. This option enables the uselib syscall, a system call used in the
  357. dynamic linker from libc5 and earlier. glibc does not use this
  358. system call. If you intend to run programs built on libc5 or
  359. earlier, you may need to enable this syscall. Current systems
  360. running glibc can safely disable this.
  361. config AUDIT
  362. bool "Auditing support"
  363. depends on NET
  364. help
  365. Enable auditing infrastructure that can be used with another
  366. kernel subsystem, such as SELinux (which requires this for
  367. logging of avc messages output). System call auditing is included
  368. on architectures which support it.
  369. config HAVE_ARCH_AUDITSYSCALL
  370. bool
  371. config AUDITSYSCALL
  372. def_bool y
  373. depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
  374. select FSNOTIFY
  375. source "kernel/irq/Kconfig"
  376. source "kernel/time/Kconfig"
  377. source "kernel/bpf/Kconfig"
  378. source "kernel/Kconfig.preempt"
  379. menu "CPU/Task time and stats accounting"
  380. config VIRT_CPU_ACCOUNTING
  381. bool
  382. choice
  383. prompt "Cputime accounting"
  384. default TICK_CPU_ACCOUNTING
  385. # Kind of a stub config for the pure tick based cputime accounting
  386. config TICK_CPU_ACCOUNTING
  387. bool "Simple tick based cputime accounting"
  388. depends on !S390 && !NO_HZ_FULL
  389. help
  390. This is the basic tick based cputime accounting that maintains
  391. statistics about user, system and idle time spent on per jiffies
  392. granularity.
  393. If unsure, say Y.
  394. config VIRT_CPU_ACCOUNTING_NATIVE
  395. bool "Deterministic task and CPU time accounting"
  396. depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
  397. select VIRT_CPU_ACCOUNTING
  398. help
  399. Select this option to enable more accurate task and CPU time
  400. accounting. This is done by reading a CPU counter on each
  401. kernel entry and exit and on transitions within the kernel
  402. between system, softirq and hardirq state, so there is a
  403. small performance impact. In the case of s390 or IBM POWER > 5,
  404. this also enables accounting of stolen time on logically-partitioned
  405. systems.
  406. config VIRT_CPU_ACCOUNTING_GEN
  407. bool "Full dynticks CPU time accounting"
  408. depends on HAVE_CONTEXT_TRACKING_USER
  409. depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
  410. depends on GENERIC_CLOCKEVENTS
  411. select VIRT_CPU_ACCOUNTING
  412. select CONTEXT_TRACKING_USER
  413. help
  414. Select this option to enable task and CPU time accounting on full
  415. dynticks systems. This accounting is implemented by watching every
  416. kernel-user boundaries using the context tracking subsystem.
  417. The accounting is thus performed at the expense of some significant
  418. overhead.
  419. For now this is only useful if you are working on the full
  420. dynticks subsystem development.
  421. If unsure, say N.
  422. endchoice
  423. config IRQ_TIME_ACCOUNTING
  424. bool "Fine granularity task level IRQ time accounting"
  425. depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
  426. help
  427. Select this option to enable fine granularity task irq time
  428. accounting. This is done by reading a timestamp on each
  429. transitions between softirq and hardirq state, so there can be a
  430. small performance impact.
  431. If in doubt, say N here.
  432. config HAVE_SCHED_AVG_IRQ
  433. def_bool y
  434. depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
  435. depends on SMP
  436. config SCHED_THERMAL_PRESSURE
  437. bool
  438. default y if ARM && ARM_CPU_TOPOLOGY
  439. default y if ARM64
  440. depends on SMP
  441. depends on CPU_FREQ_THERMAL
  442. help
  443. Select this option to enable thermal pressure accounting in the
  444. scheduler. Thermal pressure is the value conveyed to the scheduler
  445. that reflects the reduction in CPU compute capacity resulted from
  446. thermal throttling. Thermal throttling occurs when the performance of
  447. a CPU is capped due to high operating temperatures.
  448. If selected, the scheduler will be able to balance tasks accordingly,
  449. i.e. put less load on throttled CPUs than on non/less throttled ones.
  450. This requires the architecture to implement
  451. arch_update_thermal_pressure() and arch_scale_thermal_pressure().
  452. config BSD_PROCESS_ACCT
  453. bool "BSD Process Accounting"
  454. depends on MULTIUSER
  455. help
  456. If you say Y here, a user level program will be able to instruct the
  457. kernel (via a special system call) to write process accounting
  458. information to a file: whenever a process exits, information about
  459. that process will be appended to the file by the kernel. The
  460. information includes things such as creation time, owning user,
  461. command name, memory usage, controlling terminal etc. (the complete
  462. list is in the struct acct in <file:include/linux/acct.h>). It is
  463. up to the user level program to do useful things with this
  464. information. This is generally a good idea, so say Y.
  465. config BSD_PROCESS_ACCT_V3
  466. bool "BSD Process Accounting version 3 file format"
  467. depends on BSD_PROCESS_ACCT
  468. default n
  469. help
  470. If you say Y here, the process accounting information is written
  471. in a new file format that also logs the process IDs of each
  472. process and its parent. Note that this file format is incompatible
  473. with previous v0/v1/v2 file formats, so you will need updated tools
  474. for processing it. A preliminary version of these tools is available
  475. at <http://www.gnu.org/software/acct/>.
  476. config TASKSTATS
  477. bool "Export task/process statistics through netlink"
  478. depends on NET
  479. depends on MULTIUSER
  480. default n
  481. help
  482. Export selected statistics for tasks/processes through the
  483. generic netlink interface. Unlike BSD process accounting, the
  484. statistics are available during the lifetime of tasks/processes as
  485. responses to commands. Like BSD accounting, they are sent to user
  486. space on task exit.
  487. Say N if unsure.
  488. config MSM_SYSSTATS
  489. tristate "Export system/task statistics through netlink"
  490. depends on NET
  491. depends on MULTIUSER
  492. help
  493. Export system and task statistics through generic netlink
  494. interface. Userspace can retrieve these statistics via netlink
  495. socket.
  496. If unsure, say N
  497. config MSM_SYSSTATS_STUB_NONEXPORTED_SYMBOLS
  498. bool "Stub out non-exported core-kernel symbols"
  499. depends on MSM_SYSSTATS
  500. help
  501. Stub out is_system_dmabufheap(), vmalloc_nr_pages() and si_swapinfo().
  502. Enabling this option will make the swap_used, swap_total and
  503. vmalloc_total fields of struct sysstats_mem 0, and will make the
  504. unreclaimable field either 0, or make it only include the KGSL memory.
  505. If unsure, say N.
  506. config TASK_DELAY_ACCT
  507. bool "Enable per-task delay accounting"
  508. depends on TASKSTATS
  509. select SCHED_INFO
  510. help
  511. Collect information on time spent by a task waiting for system
  512. resources like cpu, synchronous block I/O completion and swapping
  513. in pages. Such statistics can help in setting a task's priorities
  514. relative to other tasks for cpu, io, rss limits etc.
  515. Say N if unsure.
  516. config TASK_XACCT
  517. bool "Enable extended accounting over taskstats"
  518. depends on TASKSTATS
  519. help
  520. Collect extended task accounting data and send the data
  521. to userland for processing over the taskstats interface.
  522. Say N if unsure.
  523. config TASK_IO_ACCOUNTING
  524. bool "Enable per-task storage I/O accounting"
  525. depends on TASK_XACCT
  526. help
  527. Collect information on the number of bytes of storage I/O which this
  528. task has caused.
  529. Say N if unsure.
  530. config PSI
  531. bool "Pressure stall information tracking"
  532. select KERNFS
  533. help
  534. Collect metrics that indicate how overcommitted the CPU, memory,
  535. and IO capacity are in the system.
  536. If you say Y here, the kernel will create /proc/pressure/ with the
  537. pressure statistics files cpu, memory, and io. These will indicate
  538. the share of walltime in which some or all tasks in the system are
  539. delayed due to contention of the respective resource.
  540. In kernels with cgroup support, cgroups (cgroup2 only) will
  541. have cpu.pressure, memory.pressure, and io.pressure files,
  542. which aggregate pressure stalls for the grouped tasks only.
  543. For more details see Documentation/accounting/psi.rst.
  544. Say N if unsure.
  545. config PSI_DEFAULT_DISABLED
  546. bool "Require boot parameter to enable pressure stall information tracking"
  547. default n
  548. depends on PSI
  549. help
  550. If set, pressure stall information tracking will be disabled
  551. per default but can be enabled through passing psi=1 on the
  552. kernel commandline during boot.
  553. This feature adds some code to the task wakeup and sleep
  554. paths of the scheduler. The overhead is too low to affect
  555. common scheduling-intense workloads in practice (such as
  556. webservers, memcache), but it does show up in artificial
  557. scheduler stress tests, such as hackbench.
  558. If you are paranoid and not sure what the kernel will be
  559. used for, say Y.
  560. Say N if unsure.
  561. endmenu # "CPU/Task time and stats accounting"
  562. config CPU_ISOLATION
  563. bool "CPU isolation"
  564. depends on SMP || COMPILE_TEST
  565. default y
  566. help
  567. Make sure that CPUs running critical tasks are not disturbed by
  568. any source of "noise" such as unbound workqueues, timers, kthreads...
  569. Unbound jobs get offloaded to housekeeping CPUs. This is driven by
  570. the "isolcpus=" boot parameter.
  571. Say Y if unsure.
  572. source "kernel/rcu/Kconfig"
  573. config BUILD_BIN2C
  574. bool
  575. default n
  576. config IKCONFIG
  577. tristate "Kernel .config support"
  578. help
  579. This option enables the complete Linux kernel ".config" file
  580. contents to be saved in the kernel. It provides documentation
  581. of which kernel options are used in a running kernel or in an
  582. on-disk kernel. This information can be extracted from the kernel
  583. image file with the script scripts/extract-ikconfig and used as
  584. input to rebuild the current kernel or to build another kernel.
  585. It can also be extracted from a running kernel by reading
  586. /proc/config.gz if enabled (below).
  587. config IKCONFIG_PROC
  588. bool "Enable access to .config through /proc/config.gz"
  589. depends on IKCONFIG && PROC_FS
  590. help
  591. This option enables access to the kernel configuration file
  592. through /proc/config.gz.
  593. config IKHEADERS
  594. tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
  595. depends on SYSFS
  596. help
  597. This option enables access to the in-kernel headers that are generated during
  598. the build process. These can be used to build eBPF tracing programs,
  599. or similar programs. If you build the headers as a module, a module called
  600. kheaders.ko is built which can be loaded on-demand to get access to headers.
  601. config LOG_BUF_SHIFT
  602. int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
  603. range 12 25
  604. default 17
  605. depends on PRINTK
  606. help
  607. Select the minimal kernel log buffer size as a power of 2.
  608. The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
  609. parameter, see below. Any higher size also might be forced
  610. by "log_buf_len" boot parameter.
  611. Examples:
  612. 17 => 128 KB
  613. 16 => 64 KB
  614. 15 => 32 KB
  615. 14 => 16 KB
  616. 13 => 8 KB
  617. 12 => 4 KB
  618. config LOG_CPU_MAX_BUF_SHIFT
  619. int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
  620. depends on SMP
  621. range 0 21
  622. default 12 if !BASE_SMALL
  623. default 0 if BASE_SMALL
  624. depends on PRINTK
  625. help
  626. This option allows to increase the default ring buffer size
  627. according to the number of CPUs. The value defines the contribution
  628. of each CPU as a power of 2. The used space is typically only few
  629. lines however it might be much more when problems are reported,
  630. e.g. backtraces.
  631. The increased size means that a new buffer has to be allocated and
  632. the original static one is unused. It makes sense only on systems
  633. with more CPUs. Therefore this value is used only when the sum of
  634. contributions is greater than the half of the default kernel ring
  635. buffer as defined by LOG_BUF_SHIFT. The default values are set
  636. so that more than 16 CPUs are needed to trigger the allocation.
  637. Also this option is ignored when "log_buf_len" kernel parameter is
  638. used as it forces an exact (power of two) size of the ring buffer.
  639. The number of possible CPUs is used for this computation ignoring
  640. hotplugging making the computation optimal for the worst case
  641. scenario while allowing a simple algorithm to be used from bootup.
  642. Examples shift values and their meaning:
  643. 17 => 128 KB for each CPU
  644. 16 => 64 KB for each CPU
  645. 15 => 32 KB for each CPU
  646. 14 => 16 KB for each CPU
  647. 13 => 8 KB for each CPU
  648. 12 => 4 KB for each CPU
  649. config PRINTK_SAFE_LOG_BUF_SHIFT
  650. int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
  651. range 10 21
  652. default 13
  653. depends on PRINTK
  654. help
  655. Select the size of an alternate printk per-CPU buffer where messages
  656. printed from usafe contexts are temporary stored. One example would
  657. be NMI messages, another one - printk recursion. The messages are
  658. copied to the main log buffer in a safe context to avoid a deadlock.
  659. The value defines the size as a power of 2.
  660. Those messages are rare and limited. The largest one is when
  661. a backtrace is printed. It usually fits into 4KB. Select
  662. 8KB if you want to be on the safe side.
  663. Examples:
  664. 17 => 128 KB for each CPU
  665. 16 => 64 KB for each CPU
  666. 15 => 32 KB for each CPU
  667. 14 => 16 KB for each CPU
  668. 13 => 8 KB for each CPU
  669. 12 => 4 KB for each CPU
  670. config PRINTK_INDEX
  671. bool "Printk indexing debugfs interface"
  672. depends on PRINTK && DEBUG_FS
  673. help
  674. Add support for indexing of all printk formats known at compile time
  675. at <debugfs>/printk/index/<module>.
  676. This can be used as part of maintaining daemons which monitor
  677. /dev/kmsg, as it permits auditing the printk formats present in a
  678. kernel, allowing detection of cases where monitored printks are
  679. changed or no longer present.
  680. There is no additional runtime cost to printk with this enabled.
  681. #
  682. # Architectures with an unreliable sched_clock() should select this:
  683. #
  684. config HAVE_UNSTABLE_SCHED_CLOCK
  685. bool
  686. config GENERIC_SCHED_CLOCK
  687. bool
  688. menu "Scheduler features"
  689. config UCLAMP_TASK
  690. bool "Enable utilization clamping for RT/FAIR tasks"
  691. depends on CPU_FREQ_GOV_SCHEDUTIL
  692. help
  693. This feature enables the scheduler to track the clamped utilization
  694. of each CPU based on RUNNABLE tasks scheduled on that CPU.
  695. With this option, the user can specify the min and max CPU
  696. utilization allowed for RUNNABLE tasks. The max utilization defines
  697. the maximum frequency a task should use while the min utilization
  698. defines the minimum frequency it should use.
  699. Both min and max utilization clamp values are hints to the scheduler,
  700. aiming at improving its frequency selection policy, but they do not
  701. enforce or grant any specific bandwidth for tasks.
  702. If in doubt, say N.
  703. config UCLAMP_BUCKETS_COUNT
  704. int "Number of supported utilization clamp buckets"
  705. range 5 20
  706. default 5
  707. depends on UCLAMP_TASK
  708. help
  709. Defines the number of clamp buckets to use. The range of each bucket
  710. will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
  711. number of clamp buckets the finer their granularity and the higher
  712. the precision of clamping aggregation and tracking at run-time.
  713. For example, with the minimum configuration value we will have 5
  714. clamp buckets tracking 20% utilization each. A 25% boosted tasks will
  715. be refcounted in the [20..39]% bucket and will set the bucket clamp
  716. effective value to 25%.
  717. If a second 30% boosted task should be co-scheduled on the same CPU,
  718. that task will be refcounted in the same bucket of the first task and
  719. it will boost the bucket clamp effective value to 30%.
  720. The clamp effective value of a bucket is reset to its nominal value
  721. (20% in the example above) when there are no more tasks refcounted in
  722. that bucket.
  723. An additional boost/capping margin can be added to some tasks. In the
  724. example above the 25% task will be boosted to 30% until it exits the
  725. CPU. If that should be considered not acceptable on certain systems,
  726. it's always possible to reduce the margin by increasing the number of
  727. clamp buckets to trade off used memory for run-time tracking
  728. precision.
  729. If in doubt, use the default value.
  730. endmenu
  731. #
  732. # For architectures that want to enable the support for NUMA-affine scheduler
  733. # balancing logic:
  734. #
  735. config ARCH_SUPPORTS_NUMA_BALANCING
  736. bool
  737. #
  738. # For architectures that prefer to flush all TLBs after a number of pages
  739. # are unmapped instead of sending one IPI per page to flush. The architecture
  740. # must provide guarantees on what happens if a clean TLB cache entry is
  741. # written after the unmap. Details are in mm/rmap.c near the check for
  742. # should_defer_flush. The architecture should also consider if the full flush
  743. # and the refill costs are offset by the savings of sending fewer IPIs.
  744. config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
  745. bool
  746. config CC_HAS_INT128
  747. def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
  748. config CC_IMPLICIT_FALLTHROUGH
  749. string
  750. default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5)
  751. default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough)
  752. # Currently, disable gcc-11+ array-bounds globally.
  753. # It's still broken in gcc-13, so no upper bound yet.
  754. config GCC11_NO_ARRAY_BOUNDS
  755. def_bool y
  756. config CC_NO_ARRAY_BOUNDS
  757. bool
  758. default y if CC_IS_GCC && GCC_VERSION >= 110000 && GCC11_NO_ARRAY_BOUNDS
  759. #
  760. # For architectures that know their GCC __int128 support is sound
  761. #
  762. config ARCH_SUPPORTS_INT128
  763. bool
  764. # For architectures that (ab)use NUMA to represent different memory regions
  765. # all cpu-local but of different latencies, such as SuperH.
  766. #
  767. config ARCH_WANT_NUMA_VARIABLE_LOCALITY
  768. bool
  769. config NUMA_BALANCING
  770. bool "Memory placement aware NUMA scheduler"
  771. depends on ARCH_SUPPORTS_NUMA_BALANCING
  772. depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
  773. depends on SMP && NUMA && MIGRATION && !PREEMPT_RT
  774. help
  775. This option adds support for automatic NUMA aware memory/task placement.
  776. The mechanism is quite primitive and is based on migrating memory when
  777. it has references to the node the task is running on.
  778. This system will be inactive on UMA systems.
  779. config NUMA_BALANCING_DEFAULT_ENABLED
  780. bool "Automatically enable NUMA aware memory/task placement"
  781. default y
  782. depends on NUMA_BALANCING
  783. help
  784. If set, automatic NUMA balancing will be enabled if running on a NUMA
  785. machine.
  786. menuconfig CGROUPS
  787. bool "Control Group support"
  788. select KERNFS
  789. help
  790. This option adds support for grouping sets of processes together, for
  791. use with process control subsystems such as Cpusets, CFS, memory
  792. controls or device isolation.
  793. See
  794. - Documentation/scheduler/sched-design-CFS.rst (CFS)
  795. - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
  796. and resource control)
  797. Say N if unsure.
  798. if CGROUPS
  799. config PAGE_COUNTER
  800. bool
  801. config CGROUP_FAVOR_DYNMODS
  802. bool "Favor dynamic modification latency reduction by default"
  803. help
  804. This option enables the "favordynmods" mount option by default
  805. which reduces the latencies of dynamic cgroup modifications such
  806. as task migrations and controller on/offs at the cost of making
  807. hot path operations such as forks and exits more expensive.
  808. Say N if unsure.
  809. config MEMCG
  810. bool "Memory controller"
  811. select PAGE_COUNTER
  812. select EVENTFD
  813. help
  814. Provides control over the memory footprint of tasks in a cgroup.
  815. config MEMCG_KMEM
  816. bool
  817. depends on MEMCG && !SLOB
  818. default y
  819. config BLK_CGROUP
  820. bool "IO controller"
  821. depends on BLOCK
  822. default n
  823. help
  824. Generic block IO controller cgroup interface. This is the common
  825. cgroup interface which should be used by various IO controlling
  826. policies.
  827. Currently, CFQ IO scheduler uses it to recognize task groups and
  828. control disk bandwidth allocation (proportional time slice allocation)
  829. to such task groups. It is also used by bio throttling logic in
  830. block layer to implement upper limit in IO rates on a device.
  831. This option only enables generic Block IO controller infrastructure.
  832. One needs to also enable actual IO controlling logic/policy. For
  833. enabling proportional weight division of disk bandwidth in CFQ, set
  834. CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
  835. CONFIG_BLK_DEV_THROTTLING=y.
  836. See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
  837. config CGROUP_WRITEBACK
  838. bool
  839. depends on MEMCG && BLK_CGROUP
  840. default y
  841. menuconfig CGROUP_SCHED
  842. bool "CPU controller"
  843. default n
  844. help
  845. This feature lets CPU scheduler recognize task groups and control CPU
  846. bandwidth allocation to such task groups. It uses cgroups to group
  847. tasks.
  848. if CGROUP_SCHED
  849. config FAIR_GROUP_SCHED
  850. bool "Group scheduling for SCHED_OTHER"
  851. depends on CGROUP_SCHED
  852. default CGROUP_SCHED
  853. config CFS_BANDWIDTH
  854. bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
  855. depends on FAIR_GROUP_SCHED
  856. default n
  857. help
  858. This option allows users to define CPU bandwidth rates (limits) for
  859. tasks running within the fair group scheduler. Groups with no limit
  860. set are considered to be unconstrained and will run with no
  861. restriction.
  862. See Documentation/scheduler/sched-bwc.rst for more information.
  863. config RT_GROUP_SCHED
  864. bool "Group scheduling for SCHED_RR/FIFO"
  865. depends on CGROUP_SCHED
  866. default n
  867. help
  868. This feature lets you explicitly allocate real CPU bandwidth
  869. to task groups. If enabled, it will also make it impossible to
  870. schedule realtime tasks for non-root users until you allocate
  871. realtime bandwidth for them.
  872. See Documentation/scheduler/sched-rt-group.rst for more information.
  873. endif #CGROUP_SCHED
  874. config UCLAMP_TASK_GROUP
  875. bool "Utilization clamping per group of tasks"
  876. depends on CGROUP_SCHED
  877. depends on UCLAMP_TASK
  878. default n
  879. help
  880. This feature enables the scheduler to track the clamped utilization
  881. of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
  882. When this option is enabled, the user can specify a min and max
  883. CPU bandwidth which is allowed for each single task in a group.
  884. The max bandwidth allows to clamp the maximum frequency a task
  885. can use, while the min bandwidth allows to define a minimum
  886. frequency a task will always use.
  887. When task group based utilization clamping is enabled, an eventually
  888. specified task-specific clamp value is constrained by the cgroup
  889. specified clamp value. Both minimum and maximum task clamping cannot
  890. be bigger than the corresponding clamping defined at task group level.
  891. If in doubt, say N.
  892. config CGROUP_PIDS
  893. bool "PIDs controller"
  894. help
  895. Provides enforcement of process number limits in the scope of a
  896. cgroup. Any attempt to fork more processes than is allowed in the
  897. cgroup will fail. PIDs are fundamentally a global resource because it
  898. is fairly trivial to reach PID exhaustion before you reach even a
  899. conservative kmemcg limit. As a result, it is possible to grind a
  900. system to halt without being limited by other cgroup policies. The
  901. PIDs controller is designed to stop this from happening.
  902. It should be noted that organisational operations (such as attaching
  903. to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
  904. since the PIDs limit only affects a process's ability to fork, not to
  905. attach to a cgroup.
  906. config CGROUP_RDMA
  907. bool "RDMA controller"
  908. help
  909. Provides enforcement of RDMA resources defined by IB stack.
  910. It is fairly easy for consumers to exhaust RDMA resources, which
  911. can result into resource unavailability to other consumers.
  912. RDMA controller is designed to stop this from happening.
  913. Attaching processes with active RDMA resources to the cgroup
  914. hierarchy is allowed even if can cross the hierarchy's limit.
  915. config CGROUP_FREEZER
  916. bool "Freezer controller"
  917. help
  918. Provides a way to freeze and unfreeze all tasks in a
  919. cgroup.
  920. This option affects the ORIGINAL cgroup interface. The cgroup2 memory
  921. controller includes important in-kernel memory consumers per default.
  922. If you're using cgroup2, say N.
  923. config CGROUP_HUGETLB
  924. bool "HugeTLB controller"
  925. depends on HUGETLB_PAGE
  926. select PAGE_COUNTER
  927. default n
  928. help
  929. Provides a cgroup controller for HugeTLB pages.
  930. When you enable this, you can put a per cgroup limit on HugeTLB usage.
  931. The limit is enforced during page fault. Since HugeTLB doesn't
  932. support page reclaim, enforcing the limit at page fault time implies
  933. that, the application will get SIGBUS signal if it tries to access
  934. HugeTLB pages beyond its limit. This requires the application to know
  935. beforehand how much HugeTLB pages it would require for its use. The
  936. control group is tracked in the third page lru pointer. This means
  937. that we cannot use the controller with huge page less than 3 pages.
  938. config CPUSETS
  939. bool "Cpuset controller"
  940. depends on SMP
  941. help
  942. This option will let you create and manage CPUSETs which
  943. allow dynamically partitioning a system into sets of CPUs and
  944. Memory Nodes and assigning tasks to run only within those sets.
  945. This is primarily useful on large SMP or NUMA systems.
  946. Say N if unsure.
  947. config PROC_PID_CPUSET
  948. bool "Include legacy /proc/<pid>/cpuset file"
  949. depends on CPUSETS
  950. default y
  951. config CGROUP_DEVICE
  952. bool "Device controller"
  953. help
  954. Provides a cgroup controller implementing whitelists for
  955. devices which a process in the cgroup can mknod or open.
  956. config CGROUP_CPUACCT
  957. bool "Simple CPU accounting controller"
  958. help
  959. Provides a simple controller for monitoring the
  960. total CPU consumed by the tasks in a cgroup.
  961. config CGROUP_PERF
  962. bool "Perf controller"
  963. depends on PERF_EVENTS
  964. help
  965. This option extends the perf per-cpu mode to restrict monitoring
  966. to threads which belong to the cgroup specified and run on the
  967. designated cpu. Or this can be used to have cgroup ID in samples
  968. so that it can monitor performance events among cgroups.
  969. Say N if unsure.
  970. config CGROUP_BPF
  971. bool "Support for eBPF programs attached to cgroups"
  972. depends on BPF_SYSCALL
  973. select SOCK_CGROUP_DATA
  974. help
  975. Allow attaching eBPF programs to a cgroup using the bpf(2)
  976. syscall command BPF_PROG_ATTACH.
  977. In which context these programs are accessed depends on the type
  978. of attachment. For instance, programs that are attached using
  979. BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
  980. inet sockets.
  981. config CGROUP_MISC
  982. bool "Misc resource controller"
  983. default n
  984. help
  985. Provides a controller for miscellaneous resources on a host.
  986. Miscellaneous scalar resources are the resources on the host system
  987. which cannot be abstracted like the other cgroups. This controller
  988. tracks and limits the miscellaneous resources used by a process
  989. attached to a cgroup hierarchy.
  990. For more information, please check misc cgroup section in
  991. /Documentation/admin-guide/cgroup-v2.rst.
  992. config CGROUP_DEBUG
  993. bool "Debug controller"
  994. default n
  995. depends on DEBUG_KERNEL
  996. help
  997. This option enables a simple controller that exports
  998. debugging information about the cgroups framework. This
  999. controller is for control cgroup debugging only. Its
  1000. interfaces are not stable.
  1001. Say N.
  1002. config SOCK_CGROUP_DATA
  1003. bool
  1004. default n
  1005. endif # CGROUPS
  1006. menuconfig NAMESPACES
  1007. bool "Namespaces support" if EXPERT
  1008. depends on MULTIUSER
  1009. default !EXPERT
  1010. help
  1011. Provides the way to make tasks work with different objects using
  1012. the same id. For example same IPC id may refer to different objects
  1013. or same user id or pid may refer to different tasks when used in
  1014. different namespaces.
  1015. if NAMESPACES
  1016. config UTS_NS
  1017. bool "UTS namespace"
  1018. default y
  1019. help
  1020. In this namespace tasks see different info provided with the
  1021. uname() system call
  1022. config TIME_NS
  1023. bool "TIME namespace"
  1024. depends on GENERIC_VDSO_TIME_NS
  1025. default y
  1026. help
  1027. In this namespace boottime and monotonic clocks can be set.
  1028. The time will keep going with the same pace.
  1029. config IPC_NS
  1030. bool "IPC namespace"
  1031. depends on (SYSVIPC || POSIX_MQUEUE)
  1032. default y
  1033. help
  1034. In this namespace tasks work with IPC ids which correspond to
  1035. different IPC objects in different namespaces.
  1036. config USER_NS
  1037. bool "User namespace"
  1038. default n
  1039. help
  1040. This allows containers, i.e. vservers, to use user namespaces
  1041. to provide different user info for different servers.
  1042. When user namespaces are enabled in the kernel it is
  1043. recommended that the MEMCG option also be enabled and that
  1044. user-space use the memory control groups to limit the amount
  1045. of memory a memory unprivileged users can use.
  1046. If unsure, say N.
  1047. config PID_NS
  1048. bool "PID Namespaces"
  1049. default y
  1050. help
  1051. Support process id namespaces. This allows having multiple
  1052. processes with the same pid as long as they are in different
  1053. pid namespaces. This is a building block of containers.
  1054. config NET_NS
  1055. bool "Network namespace"
  1056. depends on NET
  1057. default y
  1058. help
  1059. Allow user space to create what appear to be multiple instances
  1060. of the network stack.
  1061. endif # NAMESPACES
  1062. config CHECKPOINT_RESTORE
  1063. bool "Checkpoint/restore support"
  1064. depends on PROC_FS
  1065. select PROC_CHILDREN
  1066. select KCMP
  1067. default n
  1068. help
  1069. Enables additional kernel features in a sake of checkpoint/restore.
  1070. In particular it adds auxiliary prctl codes to setup process text,
  1071. data and heap segment sizes, and a few additional /proc filesystem
  1072. entries.
  1073. If unsure, say N here.
  1074. config SCHED_AUTOGROUP
  1075. bool "Automatic process group scheduling"
  1076. select CGROUPS
  1077. select CGROUP_SCHED
  1078. select FAIR_GROUP_SCHED
  1079. help
  1080. This option optimizes the scheduler for common desktop workloads by
  1081. automatically creating and populating task groups. This separation
  1082. of workloads isolates aggressive CPU burners (like build jobs) from
  1083. desktop applications. Task group autogeneration is currently based
  1084. upon task session.
  1085. config RT_SOFTIRQ_AWARE_SCHED
  1086. bool "Improve RT scheduling during long softirq execution"
  1087. depends on SMP && !PREEMPT_RT
  1088. default n
  1089. help
  1090. Enable an optimization which tries to avoid placing RT tasks on CPUs
  1091. occupied by nonpreemptible tasks, such as a long softirq or CPUs
  1092. which may soon block preemptions, such as a CPU running a ksoftirq
  1093. thread which handles slow softirqs.
  1094. config SYSFS_DEPRECATED
  1095. bool "Enable deprecated sysfs features to support old userspace tools"
  1096. depends on SYSFS
  1097. default n
  1098. help
  1099. This option adds code that switches the layout of the "block" class
  1100. devices, to not show up in /sys/class/block/, but only in
  1101. /sys/block/.
  1102. This switch is only active when the sysfs.deprecated=1 boot option is
  1103. passed or the SYSFS_DEPRECATED_V2 option is set.
  1104. This option allows new kernels to run on old distributions and tools,
  1105. which might get confused by /sys/class/block/. Since 2007/2008 all
  1106. major distributions and tools handle this just fine.
  1107. Recent distributions and userspace tools after 2009/2010 depend on
  1108. the existence of /sys/class/block/, and will not work with this
  1109. option enabled.
  1110. Only if you are using a new kernel on an old distribution, you might
  1111. need to say Y here.
  1112. config SYSFS_DEPRECATED_V2
  1113. bool "Enable deprecated sysfs features by default"
  1114. default n
  1115. depends on SYSFS
  1116. depends on SYSFS_DEPRECATED
  1117. help
  1118. Enable deprecated sysfs by default.
  1119. See the CONFIG_SYSFS_DEPRECATED option for more details about this
  1120. option.
  1121. Only if you are using a new kernel on an old distribution, you might
  1122. need to say Y here. Even then, odds are you would not need it
  1123. enabled, you can always pass the boot option if absolutely necessary.
  1124. config RELAY
  1125. bool "Kernel->user space relay support (formerly relayfs)"
  1126. select IRQ_WORK
  1127. help
  1128. This option enables support for relay interface support in
  1129. certain file systems (such as debugfs).
  1130. It is designed to provide an efficient mechanism for tools and
  1131. facilities to relay large amounts of data from kernel space to
  1132. user space.
  1133. If unsure, say N.
  1134. config BLK_DEV_INITRD
  1135. bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
  1136. help
  1137. The initial RAM filesystem is a ramfs which is loaded by the
  1138. boot loader (loadlin or lilo) and that is mounted as root
  1139. before the normal boot procedure. It is typically used to
  1140. load modules needed to mount the "real" root file system,
  1141. etc. See <file:Documentation/admin-guide/initrd.rst> for details.
  1142. If RAM disk support (BLK_DEV_RAM) is also included, this
  1143. also enables initial RAM disk (initrd) support and adds
  1144. 15 Kbytes (more on some other architectures) to the kernel size.
  1145. If unsure say Y.
  1146. if BLK_DEV_INITRD
  1147. source "usr/Kconfig"
  1148. endif
  1149. config BOOT_CONFIG
  1150. bool "Boot config support"
  1151. select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED
  1152. help
  1153. Extra boot config allows system admin to pass a config file as
  1154. complemental extension of kernel cmdline when booting.
  1155. The boot config file must be attached at the end of initramfs
  1156. with checksum, size and magic word.
  1157. See <file:Documentation/admin-guide/bootconfig.rst> for details.
  1158. If unsure, say Y.
  1159. config BOOT_CONFIG_EMBED
  1160. bool "Embed bootconfig file in the kernel"
  1161. depends on BOOT_CONFIG
  1162. help
  1163. Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the
  1164. kernel. Usually, the bootconfig file is loaded with the initrd
  1165. image. But if the system doesn't support initrd, this option will
  1166. help you by embedding a bootconfig file while building the kernel.
  1167. If unsure, say N.
  1168. config BOOT_CONFIG_EMBED_FILE
  1169. string "Embedded bootconfig file path"
  1170. depends on BOOT_CONFIG_EMBED
  1171. help
  1172. Specify a bootconfig file which will be embedded to the kernel.
  1173. This bootconfig will be used if there is no initrd or no other
  1174. bootconfig in the initrd.
  1175. config INITRAMFS_PRESERVE_MTIME
  1176. bool "Preserve cpio archive mtimes in initramfs"
  1177. default y
  1178. help
  1179. Each entry in an initramfs cpio archive carries an mtime value. When
  1180. enabled, extracted cpio items take this mtime, with directory mtime
  1181. setting deferred until after creation of any child entries.
  1182. If unsure, say Y.
  1183. choice
  1184. prompt "Compiler optimization level"
  1185. default CC_OPTIMIZE_FOR_PERFORMANCE
  1186. config CC_OPTIMIZE_FOR_PERFORMANCE
  1187. bool "Optimize for performance (-O2)"
  1188. help
  1189. This is the default optimization level for the kernel, building
  1190. with the "-O2" compiler flag for best performance and most
  1191. helpful compile-time warnings.
  1192. config CC_OPTIMIZE_FOR_SIZE
  1193. bool "Optimize for size (-Os)"
  1194. help
  1195. Choosing this option will pass "-Os" to your compiler resulting
  1196. in a smaller kernel.
  1197. endchoice
  1198. config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
  1199. bool
  1200. help
  1201. This requires that the arch annotates or otherwise protects
  1202. its external entry points from being discarded. Linker scripts
  1203. must also merge .text.*, .data.*, and .bss.* correctly into
  1204. output sections. Care must be taken not to pull in unrelated
  1205. sections (e.g., '.text.init'). Typically '.' in section names
  1206. is used to distinguish them from label names / C identifiers.
  1207. config LD_DEAD_CODE_DATA_ELIMINATION
  1208. bool "Dead code and data elimination (EXPERIMENTAL)"
  1209. depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
  1210. depends on EXPERT
  1211. depends on $(cc-option,-ffunction-sections -fdata-sections)
  1212. depends on $(ld-option,--gc-sections)
  1213. help
  1214. Enable this if you want to do dead code and data elimination with
  1215. the linker by compiling with -ffunction-sections -fdata-sections,
  1216. and linking with --gc-sections.
  1217. This can reduce on disk and in-memory size of the kernel
  1218. code and static data, particularly for small configs and
  1219. on small systems. This has the possibility of introducing
  1220. silently broken kernel if the required annotations are not
  1221. present. This option is not well tested yet, so use at your
  1222. own risk.
  1223. config LD_ORPHAN_WARN
  1224. def_bool y
  1225. depends on ARCH_WANT_LD_ORPHAN_WARN
  1226. depends on $(ld-option,--orphan-handling=warn)
  1227. config SYSCTL
  1228. bool
  1229. config HAVE_UID16
  1230. bool
  1231. config SYSCTL_EXCEPTION_TRACE
  1232. bool
  1233. help
  1234. Enable support for /proc/sys/debug/exception-trace.
  1235. config SYSCTL_ARCH_UNALIGN_NO_WARN
  1236. bool
  1237. help
  1238. Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
  1239. Allows arch to define/use @no_unaligned_warning to possibly warn
  1240. about unaligned access emulation going on under the hood.
  1241. config SYSCTL_ARCH_UNALIGN_ALLOW
  1242. bool
  1243. help
  1244. Enable support for /proc/sys/kernel/unaligned-trap
  1245. Allows arches to define/use @unaligned_enabled to runtime toggle
  1246. the unaligned access emulation.
  1247. see arch/parisc/kernel/unaligned.c for reference
  1248. config HAVE_PCSPKR_PLATFORM
  1249. bool
  1250. # interpreter that classic socket filters depend on
  1251. config BPF
  1252. bool
  1253. select CRYPTO_LIB_SHA1
  1254. menuconfig EXPERT
  1255. bool "Configure standard kernel features (expert users)"
  1256. # Unhide debug options, to make the on-by-default options visible
  1257. select DEBUG_KERNEL
  1258. help
  1259. This option allows certain base kernel options and settings
  1260. to be disabled or tweaked. This is for specialized
  1261. environments which can tolerate a "non-standard" kernel.
  1262. Only use this if you really know what you are doing.
  1263. config UID16
  1264. bool "Enable 16-bit UID system calls" if EXPERT
  1265. depends on HAVE_UID16 && MULTIUSER
  1266. default y
  1267. help
  1268. This enables the legacy 16-bit UID syscall wrappers.
  1269. config MULTIUSER
  1270. bool "Multiple users, groups and capabilities support" if EXPERT
  1271. default y
  1272. help
  1273. This option enables support for non-root users, groups and
  1274. capabilities.
  1275. If you say N here, all processes will run with UID 0, GID 0, and all
  1276. possible capabilities. Saying N here also compiles out support for
  1277. system calls related to UIDs, GIDs, and capabilities, such as setuid,
  1278. setgid, and capset.
  1279. If unsure, say Y here.
  1280. config SGETMASK_SYSCALL
  1281. bool "sgetmask/ssetmask syscalls support" if EXPERT
  1282. def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
  1283. help
  1284. sys_sgetmask and sys_ssetmask are obsolete system calls
  1285. no longer supported in libc but still enabled by default in some
  1286. architectures.
  1287. If unsure, leave the default option here.
  1288. config SYSFS_SYSCALL
  1289. bool "Sysfs syscall support" if EXPERT
  1290. default y
  1291. help
  1292. sys_sysfs is an obsolete system call no longer supported in libc.
  1293. Note that disabling this option is more secure but might break
  1294. compatibility with some systems.
  1295. If unsure say Y here.
  1296. config FHANDLE
  1297. bool "open by fhandle syscalls" if EXPERT
  1298. select EXPORTFS
  1299. default y
  1300. help
  1301. If you say Y here, a user level program will be able to map
  1302. file names to handle and then later use the handle for
  1303. different file system operations. This is useful in implementing
  1304. userspace file servers, which now track files using handles instead
  1305. of names. The handle would remain the same even if file names
  1306. get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
  1307. syscalls.
  1308. config POSIX_TIMERS
  1309. bool "Posix Clocks & timers" if EXPERT
  1310. default y
  1311. help
  1312. This includes native support for POSIX timers to the kernel.
  1313. Some embedded systems have no use for them and therefore they
  1314. can be configured out to reduce the size of the kernel image.
  1315. When this option is disabled, the following syscalls won't be
  1316. available: timer_create, timer_gettime: timer_getoverrun,
  1317. timer_settime, timer_delete, clock_adjtime, getitimer,
  1318. setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
  1319. clock_getres and clock_nanosleep syscalls will be limited to
  1320. CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
  1321. If unsure say y.
  1322. config PRINTK
  1323. default y
  1324. bool "Enable support for printk" if EXPERT
  1325. select IRQ_WORK
  1326. help
  1327. This option enables normal printk support. Removing it
  1328. eliminates most of the message strings from the kernel image
  1329. and makes the kernel more or less silent. As this makes it
  1330. very difficult to diagnose system problems, saying N here is
  1331. strongly discouraged.
  1332. config BUG
  1333. bool "BUG() support" if EXPERT
  1334. default y
  1335. help
  1336. Disabling this option eliminates support for BUG and WARN, reducing
  1337. the size of your kernel image and potentially quietly ignoring
  1338. numerous fatal conditions. You should only consider disabling this
  1339. option for embedded systems with no facilities for reporting errors.
  1340. Just say Y.
  1341. config ELF_CORE
  1342. depends on COREDUMP
  1343. default y
  1344. bool "Enable ELF core dumps" if EXPERT
  1345. help
  1346. Enable support for generating core dumps. Disabling saves about 4k.
  1347. config PCSPKR_PLATFORM
  1348. bool "Enable PC-Speaker support" if EXPERT
  1349. depends on HAVE_PCSPKR_PLATFORM
  1350. select I8253_LOCK
  1351. default y
  1352. help
  1353. This option allows to disable the internal PC-Speaker
  1354. support, saving some memory.
  1355. config BASE_FULL
  1356. default y
  1357. bool "Enable full-sized data structures for core" if EXPERT
  1358. help
  1359. Disabling this option reduces the size of miscellaneous core
  1360. kernel data structures. This saves memory on small machines,
  1361. but may reduce performance.
  1362. config FUTEX
  1363. bool "Enable futex support" if EXPERT
  1364. depends on !(SPARC32 && SMP)
  1365. default y
  1366. imply RT_MUTEXES
  1367. help
  1368. Disabling this option will cause the kernel to be built without
  1369. support for "fast userspace mutexes". The resulting kernel may not
  1370. run glibc-based applications correctly.
  1371. config FUTEX_PI
  1372. bool
  1373. depends on FUTEX && RT_MUTEXES
  1374. default y
  1375. config EPOLL
  1376. bool "Enable eventpoll support" if EXPERT
  1377. default y
  1378. help
  1379. Disabling this option will cause the kernel to be built without
  1380. support for epoll family of system calls.
  1381. config SIGNALFD
  1382. bool "Enable signalfd() system call" if EXPERT
  1383. default y
  1384. help
  1385. Enable the signalfd() system call that allows to receive signals
  1386. on a file descriptor.
  1387. If unsure, say Y.
  1388. config TIMERFD
  1389. bool "Enable timerfd() system call" if EXPERT
  1390. default y
  1391. help
  1392. Enable the timerfd() system call that allows to receive timer
  1393. events on a file descriptor.
  1394. If unsure, say Y.
  1395. config EVENTFD
  1396. bool "Enable eventfd() system call" if EXPERT
  1397. default y
  1398. help
  1399. Enable the eventfd() system call that allows to receive both
  1400. kernel notification (ie. KAIO) or userspace notifications.
  1401. If unsure, say Y.
  1402. config SHMEM
  1403. bool "Use full shmem filesystem" if EXPERT
  1404. default y
  1405. depends on MMU
  1406. help
  1407. The shmem is an internal filesystem used to manage shared memory.
  1408. It is backed by swap and manages resource limits. It is also exported
  1409. to userspace as tmpfs if TMPFS is enabled. Disabling this
  1410. option replaces shmem and tmpfs with the much simpler ramfs code,
  1411. which may be appropriate on small systems without swap.
  1412. config AIO
  1413. bool "Enable AIO support" if EXPERT
  1414. default y
  1415. help
  1416. This option enables POSIX asynchronous I/O which may by used
  1417. by some high performance threaded applications. Disabling
  1418. this option saves about 7k.
  1419. config IO_URING
  1420. bool "Enable IO uring support" if EXPERT
  1421. select IO_WQ
  1422. default y
  1423. help
  1424. This option enables support for the io_uring interface, enabling
  1425. applications to submit and complete IO through submission and
  1426. completion rings that are shared between the kernel and application.
  1427. config ADVISE_SYSCALLS
  1428. bool "Enable madvise/fadvise syscalls" if EXPERT
  1429. default y
  1430. help
  1431. This option enables the madvise and fadvise syscalls, used by
  1432. applications to advise the kernel about their future memory or file
  1433. usage, improving performance. If building an embedded system where no
  1434. applications use these syscalls, you can disable this option to save
  1435. space.
  1436. config MEMBARRIER
  1437. bool "Enable membarrier() system call" if EXPERT
  1438. default y
  1439. help
  1440. Enable the membarrier() system call that allows issuing memory
  1441. barriers across all running threads, which can be used to distribute
  1442. the cost of user-space memory barriers asymmetrically by transforming
  1443. pairs of memory barriers into pairs consisting of membarrier() and a
  1444. compiler barrier.
  1445. If unsure, say Y.
  1446. config KALLSYMS
  1447. bool "Load all symbols for debugging/ksymoops" if EXPERT
  1448. default y
  1449. help
  1450. Say Y here to let the kernel print out symbolic crash information and
  1451. symbolic stack backtraces. This increases the size of the kernel
  1452. somewhat, as all symbols have to be loaded into the kernel image.
  1453. config KALLSYMS_ALL
  1454. bool "Include all symbols in kallsyms"
  1455. depends on DEBUG_KERNEL && KALLSYMS
  1456. help
  1457. Normally kallsyms only contains the symbols of functions for nicer
  1458. OOPS messages and backtraces (i.e., symbols from the text and inittext
  1459. sections). This is sufficient for most cases. And only if you want to
  1460. enable kernel live patching, or other less common use cases (e.g.,
  1461. when a debugger is used) all symbols are required (i.e., names of
  1462. variables from the data sections, etc).
  1463. This option makes sure that all symbols are loaded into the kernel
  1464. image (i.e., symbols from all sections) in cost of increased kernel
  1465. size (depending on the kernel configuration, it may be 300KiB or
  1466. something like this).
  1467. Say N unless you really need all symbols, or kernel live patching.
  1468. config KALLSYMS_ABSOLUTE_PERCPU
  1469. bool
  1470. depends on KALLSYMS
  1471. default X86_64 && SMP
  1472. config KALLSYMS_BASE_RELATIVE
  1473. bool
  1474. depends on KALLSYMS
  1475. default !IA64
  1476. help
  1477. Instead of emitting them as absolute values in the native word size,
  1478. emit the symbol references in the kallsyms table as 32-bit entries,
  1479. each containing a relative value in the range [base, base + U32_MAX]
  1480. or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
  1481. an absolute value in the range [0, S32_MAX] or a relative value in the
  1482. range [base, base + S32_MAX], where base is the lowest relative symbol
  1483. address encountered in the image.
  1484. On 64-bit builds, this reduces the size of the address table by 50%,
  1485. but more importantly, it results in entries whose values are build
  1486. time constants, and no relocation pass is required at runtime to fix
  1487. up the entries based on the runtime load address of the kernel.
  1488. # end of the "standard kernel features (expert users)" menu
  1489. # syscall, maps, verifier
  1490. config ARCH_HAS_MEMBARRIER_CALLBACKS
  1491. bool
  1492. config ARCH_HAS_MEMBARRIER_SYNC_CORE
  1493. bool
  1494. config KCMP
  1495. bool "Enable kcmp() system call" if EXPERT
  1496. help
  1497. Enable the kernel resource comparison system call. It provides
  1498. user-space with the ability to compare two processes to see if they
  1499. share a common resource, such as a file descriptor or even virtual
  1500. memory space.
  1501. If unsure, say N.
  1502. config RSEQ
  1503. bool "Enable rseq() system call" if EXPERT
  1504. default y
  1505. depends on HAVE_RSEQ
  1506. select MEMBARRIER
  1507. help
  1508. Enable the restartable sequences system call. It provides a
  1509. user-space cache for the current CPU number value, which
  1510. speeds up getting the current CPU number from user-space,
  1511. as well as an ABI to speed up user-space operations on
  1512. per-CPU data.
  1513. If unsure, say Y.
  1514. config DEBUG_RSEQ
  1515. default n
  1516. bool "Enabled debugging of rseq() system call" if EXPERT
  1517. depends on RSEQ && DEBUG_KERNEL
  1518. help
  1519. Enable extra debugging checks for the rseq system call.
  1520. If unsure, say N.
  1521. config EMBEDDED
  1522. bool "Embedded system"
  1523. select EXPERT
  1524. help
  1525. This option should be enabled if compiling the kernel for
  1526. an embedded system so certain expert options are available
  1527. for configuration.
  1528. config HAVE_PERF_EVENTS
  1529. bool
  1530. help
  1531. See tools/perf/design.txt for details.
  1532. config GUEST_PERF_EVENTS
  1533. bool
  1534. depends on HAVE_PERF_EVENTS
  1535. config PERF_USE_VMALLOC
  1536. bool
  1537. help
  1538. See tools/perf/design.txt for details
  1539. config PC104
  1540. bool "PC/104 support" if EXPERT
  1541. help
  1542. Expose PC/104 form factor device drivers and options available for
  1543. selection and configuration. Enable this option if your target
  1544. machine has a PC/104 bus.
  1545. menu "Kernel Performance Events And Counters"
  1546. config PERF_EVENTS
  1547. bool "Kernel performance events and counters"
  1548. default y if PROFILING
  1549. depends on HAVE_PERF_EVENTS
  1550. select IRQ_WORK
  1551. select SRCU
  1552. help
  1553. Enable kernel support for various performance events provided
  1554. by software and hardware.
  1555. Software events are supported either built-in or via the
  1556. use of generic tracepoints.
  1557. Most modern CPUs support performance events via performance
  1558. counter registers. These registers count the number of certain
  1559. types of hw events: such as instructions executed, cachemisses
  1560. suffered, or branches mis-predicted - without slowing down the
  1561. kernel or applications. These registers can also trigger interrupts
  1562. when a threshold number of events have passed - and can thus be
  1563. used to profile the code that runs on that CPU.
  1564. The Linux Performance Event subsystem provides an abstraction of
  1565. these software and hardware event capabilities, available via a
  1566. system call and used by the "perf" utility in tools/perf/. It
  1567. provides per task and per CPU counters, and it provides event
  1568. capabilities on top of those.
  1569. Say Y if unsure.
  1570. config DEBUG_PERF_USE_VMALLOC
  1571. default n
  1572. bool "Debug: use vmalloc to back perf mmap() buffers"
  1573. depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
  1574. select PERF_USE_VMALLOC
  1575. help
  1576. Use vmalloc memory to back perf mmap() buffers.
  1577. Mostly useful for debugging the vmalloc code on platforms
  1578. that don't require it.
  1579. Say N if unsure.
  1580. endmenu
  1581. config SYSTEM_DATA_VERIFICATION
  1582. def_bool n
  1583. select SYSTEM_TRUSTED_KEYRING
  1584. select KEYS
  1585. select CRYPTO
  1586. select CRYPTO_RSA
  1587. select ASYMMETRIC_KEY_TYPE
  1588. select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
  1589. select ASN1
  1590. select OID_REGISTRY
  1591. select X509_CERTIFICATE_PARSER
  1592. select PKCS7_MESSAGE_PARSER
  1593. help
  1594. Provide PKCS#7 message verification using the contents of the system
  1595. trusted keyring to provide public keys. This then can be used for
  1596. module verification, kexec image verification and firmware blob
  1597. verification.
  1598. config PROFILING
  1599. bool "Profiling support"
  1600. help
  1601. Say Y here to enable the extended profiling support mechanisms used
  1602. by profilers.
  1603. config RUST
  1604. bool "Rust support"
  1605. depends on HAVE_RUST
  1606. depends on RUST_IS_AVAILABLE
  1607. depends on !MODVERSIONS
  1608. depends on !GCC_PLUGINS
  1609. depends on !RANDSTRUCT
  1610. depends on !DEBUG_INFO_BTF
  1611. select CONSTRUCTORS
  1612. help
  1613. Enables Rust support in the kernel.
  1614. This allows other Rust-related options, like drivers written in Rust,
  1615. to be selected.
  1616. It is also required to be able to load external kernel modules
  1617. written in Rust.
  1618. See Documentation/rust/ for more information.
  1619. If unsure, say N.
  1620. config RUSTC_VERSION_TEXT
  1621. string
  1622. depends on RUST
  1623. default $(shell,command -v $(RUSTC) >/dev/null 2>&1 && $(RUSTC) --version || echo n)
  1624. config BINDGEN_VERSION_TEXT
  1625. string
  1626. depends on RUST
  1627. default $(shell,command -v $(BINDGEN) >/dev/null 2>&1 && $(BINDGEN) --version || echo n)
  1628. #
  1629. # Place an empty function call at each tracepoint site. Can be
  1630. # dynamically changed for a probe function.
  1631. #
  1632. config TRACEPOINTS
  1633. bool
  1634. endmenu # General setup
  1635. source "arch/Kconfig"
  1636. config RT_MUTEXES
  1637. bool
  1638. default y if PREEMPT_RT
  1639. config BASE_SMALL
  1640. int
  1641. default 0 if BASE_FULL
  1642. default 1 if !BASE_FULL
  1643. config MODULE_SIG_FORMAT
  1644. def_bool n
  1645. select SYSTEM_DATA_VERIFICATION
  1646. source "kernel/module/Kconfig"
  1647. config INIT_ALL_POSSIBLE
  1648. bool
  1649. help
  1650. Back when each arch used to define their own cpu_online_mask and
  1651. cpu_possible_mask, some of them chose to initialize cpu_possible_mask
  1652. with all 1s, and others with all 0s. When they were centralised,
  1653. it was better to provide this option than to break all the archs
  1654. and have several arch maintainers pursuing me down dark alleys.
  1655. source "block/Kconfig"
  1656. config PREEMPT_NOTIFIERS
  1657. bool
  1658. config PADATA
  1659. depends on SMP
  1660. bool
  1661. config ASN1
  1662. tristate
  1663. help
  1664. Build a simple ASN.1 grammar compiler that produces a bytecode output
  1665. that can be interpreted by the ASN.1 stream decoder and used to
  1666. inform it as to what tags are to be expected in a stream and what
  1667. functions to call on what tags.
  1668. source "kernel/Kconfig.locks"
  1669. config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
  1670. bool
  1671. config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
  1672. bool
  1673. # It may be useful for an architecture to override the definitions of the
  1674. # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
  1675. # and the COMPAT_ variants in <linux/compat.h>, in particular to use a
  1676. # different calling convention for syscalls. They can also override the
  1677. # macros for not-implemented syscalls in kernel/sys_ni.c and
  1678. # kernel/time/posix-stubs.c. All these overrides need to be available in
  1679. # <asm/syscall_wrapper.h>.
  1680. config ARCH_HAS_SYSCALL_WRAPPER
  1681. def_bool n
  1682. source "init/Kconfig.gki"
  1683. source "init/Kconfig.gki-debug"