Kconfig 42 KB

1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192939495969798991001011021031041051061071081091101111121131141151161171181191201211221231241251261271281291301311321331341351361371381391401411421431441451461471481491501511521531541551561571581591601611621631641651661671681691701711721731741751761771781791801811821831841851861871881891901911921931941951961971981992002012022032042052062072082092102112122132142152162172182192202212222232242252262272282292302312322332342352362372382392402412422432442452462472482492502512522532542552562572582592602612622632642652662672682692702712722732742752762772782792802812822832842852862872882892902912922932942952962972982993003013023033043053063073083093103113123133143153163173183193203213223233243253263273283293303313323333343353363373383393403413423433443453463473483493503513523533543553563573583593603613623633643653663673683693703713723733743753763773783793803813823833843853863873883893903913923933943953963973983994004014024034044054064074084094104114124134144154164174184194204214224234244254264274284294304314324334344354364374384394404414424434444454464474484494504514524534544554564574584594604614624634644654664674684694704714724734744754764774784794804814824834844854864874884894904914924934944954964974984995005015025035045055065075085095105115125135145155165175185195205215225235245255265275285295305315325335345355365375385395405415425435445455465475485495505515525535545555565575585595605615625635645655665675685695705715725735745755765775785795805815825835845855865875885895905915925935945955965975985996006016026036046056066076086096106116126136146156166176186196206216226236246256266276286296306316326336346356366376386396406416426436446456466476486496506516526536546556566576586596606616626636646656666676686696706716726736746756766776786796806816826836846856866876886896906916926936946956966976986997007017027037047057067077087097107117127137147157167177187197207217227237247257267277287297307317327337347357367377387397407417427437447457467477487497507517527537547557567577587597607617627637647657667677687697707717727737747757767777787797807817827837847857867877887897907917927937947957967977987998008018028038048058068078088098108118128138148158168178188198208218228238248258268278288298308318328338348358368378388398408418428438448458468478488498508518528538548558568578588598608618628638648658668678688698708718728738748758768778788798808818828838848858868878888898908918928938948958968978988999009019029039049059069079089099109119129139149159169179189199209219229239249259269279289299309319329339349359369379389399409419429439449459469479489499509519529539549559569579589599609619629639649659669679689699709719729739749759769779789799809819829839849859869879889899909919929939949959969979989991000100110021003100410051006100710081009101010111012101310141015101610171018101910201021102210231024102510261027102810291030103110321033103410351036103710381039104010411042104310441045104610471048104910501051105210531054105510561057105810591060106110621063106410651066106710681069107010711072107310741075107610771078107910801081108210831084108510861087108810891090109110921093109410951096109710981099110011011102110311041105110611071108110911101111111211131114111511161117111811191120112111221123112411251126112711281129113011311132113311341135113611371138113911401141114211431144114511461147114811491150115111521153115411551156115711581159116011611162116311641165116611671168116911701171117211731174117511761177117811791180118111821183118411851186118711881189119011911192119311941195119611971198119912001201120212031204120512061207120812091210121112121213121412151216121712181219122012211222122312241225122612271228122912301231123212331234123512361237123812391240124112421243124412451246124712481249125012511252125312541255125612571258125912601261126212631264126512661267126812691270127112721273127412751276127712781279128012811282128312841285128612871288128912901291129212931294129512961297129812991300130113021303130413051306130713081309131013111312131313141315131613171318131913201321132213231324132513261327132813291330133113321333133413351336133713381339134013411342134313441345
  1. config ARCH
  2. string
  3. option env="ARCH"
  4. config KERNELVERSION
  5. string
  6. option env="KERNELVERSION"
  7. config DEFCONFIG_LIST
  8. string
  9. depends on !UML
  10. option defconfig_list
  11. default "/lib/modules/$UNAME_RELEASE/.config"
  12. default "/etc/kernel-config"
  13. default "/boot/config-$UNAME_RELEASE"
  14. default "$ARCH_DEFCONFIG"
  15. default "arch/$ARCH/defconfig"
  16. config CONSTRUCTORS
  17. bool
  18. depends on !UML
  19. default y
  20. config HAVE_IRQ_WORK
  21. bool
  22. config IRQ_WORK
  23. bool
  24. depends on HAVE_IRQ_WORK
  25. menu "General setup"
  26. config EXPERIMENTAL
  27. bool "Prompt for development and/or incomplete code/drivers"
  28. ---help---
  29. Some of the various things that Linux supports (such as network
  30. drivers, file systems, network protocols, etc.) can be in a state
  31. of development where the functionality, stability, or the level of
  32. testing is not yet high enough for general use. This is usually
  33. known as the "alpha-test" phase among developers. If a feature is
  34. currently in alpha-test, then the developers usually discourage
  35. uninformed widespread use of this feature by the general public to
  36. avoid "Why doesn't this work?" type mail messages. However, active
  37. testing and use of these systems is welcomed. Just be aware that it
  38. may not meet the normal level of reliability or it may fail to work
  39. in some special cases. Detailed bug reports from people familiar
  40. with the kernel internals are usually welcomed by the developers
  41. (before submitting bug reports, please read the documents
  42. <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
  43. <file:Documentation/BUG-HUNTING>, and
  44. <file:Documentation/oops-tracing.txt> in the kernel source).
  45. This option will also make obsoleted drivers available. These are
  46. drivers that have been replaced by something else, and/or are
  47. scheduled to be removed in a future kernel release.
  48. Unless you intend to help test and develop a feature or driver that
  49. falls into this category, or you have a situation that requires
  50. using these features, you should probably say N here, which will
  51. cause the configurator to present you with fewer choices. If
  52. you say Y here, you will be offered the choice of using features or
  53. drivers that are currently considered to be in the alpha-test phase.
  54. config BROKEN
  55. bool
  56. config BROKEN_ON_SMP
  57. bool
  58. depends on BROKEN || !SMP
  59. default y
  60. config LOCK_KERNEL
  61. bool
  62. depends on (SMP || PREEMPT) && BKL
  63. default y
  64. config INIT_ENV_ARG_LIMIT
  65. int
  66. default 32 if !UML
  67. default 128 if UML
  68. help
  69. Maximum of each of the number of arguments and environment
  70. variables passed to init from the kernel command line.
  71. config CROSS_COMPILE
  72. string "Cross-compiler tool prefix"
  73. help
  74. Same as running 'make CROSS_COMPILE=prefix-' but stored for
  75. default make runs in this kernel build directory. You don't
  76. need to set this unless you want the configured kernel build
  77. directory to select the cross-compiler automatically.
  78. config LOCALVERSION
  79. string "Local version - append to kernel release"
  80. help
  81. Append an extra string to the end of your kernel version.
  82. This will show up when you type uname, for example.
  83. The string you set here will be appended after the contents of
  84. any files with a filename matching localversion* in your
  85. object and source tree, in that order. Your total string can
  86. be a maximum of 64 characters.
  87. config LOCALVERSION_AUTO
  88. bool "Automatically append version information to the version string"
  89. default y
  90. help
  91. This will try to automatically determine if the current tree is a
  92. release tree by looking for git tags that belong to the current
  93. top of tree revision.
  94. A string of the format -gxxxxxxxx will be added to the localversion
  95. if a git-based tree is found. The string generated by this will be
  96. appended after any matching localversion* files, and after the value
  97. set in CONFIG_LOCALVERSION.
  98. (The actual string used here is the first eight characters produced
  99. by running the command:
  100. $ git rev-parse --verify HEAD
  101. which is done within the script "scripts/setlocalversion".)
  102. config HAVE_KERNEL_GZIP
  103. bool
  104. config HAVE_KERNEL_BZIP2
  105. bool
  106. config HAVE_KERNEL_LZMA
  107. bool
  108. config HAVE_KERNEL_LZO
  109. bool
  110. choice
  111. prompt "Kernel compression mode"
  112. default KERNEL_GZIP
  113. depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_LZO
  114. help
  115. The linux kernel is a kind of self-extracting executable.
  116. Several compression algorithms are available, which differ
  117. in efficiency, compression and decompression speed.
  118. Compression speed is only relevant when building a kernel.
  119. Decompression speed is relevant at each boot.
  120. If you have any problems with bzip2 or lzma compressed
  121. kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
  122. version of this functionality (bzip2 only), for 2.4, was
  123. supplied by Christian Ludwig)
  124. High compression options are mostly useful for users, who
  125. are low on disk space (embedded systems), but for whom ram
  126. size matters less.
  127. If in doubt, select 'gzip'
  128. config KERNEL_GZIP
  129. bool "Gzip"
  130. depends on HAVE_KERNEL_GZIP
  131. help
  132. The old and tried gzip compression. It provides a good balance
  133. between compression ratio and decompression speed.
  134. config KERNEL_BZIP2
  135. bool "Bzip2"
  136. depends on HAVE_KERNEL_BZIP2
  137. help
  138. Its compression ratio and speed is intermediate.
  139. Decompression speed is slowest among the three. The kernel
  140. size is about 10% smaller with bzip2, in comparison to gzip.
  141. Bzip2 uses a large amount of memory. For modern kernels you
  142. will need at least 8MB RAM or more for booting.
  143. config KERNEL_LZMA
  144. bool "LZMA"
  145. depends on HAVE_KERNEL_LZMA
  146. help
  147. The most recent compression algorithm.
  148. Its ratio is best, decompression speed is between the other
  149. two. Compression is slowest. The kernel size is about 33%
  150. smaller with LZMA in comparison to gzip.
  151. config KERNEL_LZO
  152. bool "LZO"
  153. depends on HAVE_KERNEL_LZO
  154. help
  155. Its compression ratio is the poorest among the 4. The kernel
  156. size is about 10% bigger than gzip; however its speed
  157. (both compression and decompression) is the fastest.
  158. endchoice
  159. config SWAP
  160. bool "Support for paging of anonymous memory (swap)"
  161. depends on MMU && BLOCK
  162. default y
  163. help
  164. This option allows you to choose whether you want to have support
  165. for so called swap devices or swap files in your kernel that are
  166. used to provide more virtual memory than the actual RAM present
  167. in your computer. If unsure say Y.
  168. config SYSVIPC
  169. bool "System V IPC"
  170. ---help---
  171. Inter Process Communication is a suite of library functions and
  172. system calls which let processes (running programs) synchronize and
  173. exchange information. It is generally considered to be a good thing,
  174. and some programs won't run unless you say Y here. In particular, if
  175. you want to run the DOS emulator dosemu under Linux (read the
  176. DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
  177. you'll need to say Y here.
  178. You can find documentation about IPC with "info ipc" and also in
  179. section 6.4 of the Linux Programmer's Guide, available from
  180. <http://www.tldp.org/guides.html>.
  181. config SYSVIPC_SYSCTL
  182. bool
  183. depends on SYSVIPC
  184. depends on SYSCTL
  185. default y
  186. config POSIX_MQUEUE
  187. bool "POSIX Message Queues"
  188. depends on NET && EXPERIMENTAL
  189. ---help---
  190. POSIX variant of message queues is a part of IPC. In POSIX message
  191. queues every message has a priority which decides about succession
  192. of receiving it by a process. If you want to compile and run
  193. programs written e.g. for Solaris with use of its POSIX message
  194. queues (functions mq_*) say Y here.
  195. POSIX message queues are visible as a filesystem called 'mqueue'
  196. and can be mounted somewhere if you want to do filesystem
  197. operations on message queues.
  198. If unsure, say Y.
  199. config POSIX_MQUEUE_SYSCTL
  200. bool
  201. depends on POSIX_MQUEUE
  202. depends on SYSCTL
  203. default y
  204. config BSD_PROCESS_ACCT
  205. bool "BSD Process Accounting"
  206. help
  207. If you say Y here, a user level program will be able to instruct the
  208. kernel (via a special system call) to write process accounting
  209. information to a file: whenever a process exits, information about
  210. that process will be appended to the file by the kernel. The
  211. information includes things such as creation time, owning user,
  212. command name, memory usage, controlling terminal etc. (the complete
  213. list is in the struct acct in <file:include/linux/acct.h>). It is
  214. up to the user level program to do useful things with this
  215. information. This is generally a good idea, so say Y.
  216. config BSD_PROCESS_ACCT_V3
  217. bool "BSD Process Accounting version 3 file format"
  218. depends on BSD_PROCESS_ACCT
  219. default n
  220. help
  221. If you say Y here, the process accounting information is written
  222. in a new file format that also logs the process IDs of each
  223. process and it's parent. Note that this file format is incompatible
  224. with previous v0/v1/v2 file formats, so you will need updated tools
  225. for processing it. A preliminary version of these tools is available
  226. at <http://www.gnu.org/software/acct/>.
  227. config TASKSTATS
  228. bool "Export task/process statistics through netlink (EXPERIMENTAL)"
  229. depends on NET
  230. default n
  231. help
  232. Export selected statistics for tasks/processes through the
  233. generic netlink interface. Unlike BSD process accounting, the
  234. statistics are available during the lifetime of tasks/processes as
  235. responses to commands. Like BSD accounting, they are sent to user
  236. space on task exit.
  237. Say N if unsure.
  238. config TASK_DELAY_ACCT
  239. bool "Enable per-task delay accounting (EXPERIMENTAL)"
  240. depends on TASKSTATS
  241. help
  242. Collect information on time spent by a task waiting for system
  243. resources like cpu, synchronous block I/O completion and swapping
  244. in pages. Such statistics can help in setting a task's priorities
  245. relative to other tasks for cpu, io, rss limits etc.
  246. Say N if unsure.
  247. config TASK_XACCT
  248. bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
  249. depends on TASKSTATS
  250. help
  251. Collect extended task accounting data and send the data
  252. to userland for processing over the taskstats interface.
  253. Say N if unsure.
  254. config TASK_IO_ACCOUNTING
  255. bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
  256. depends on TASK_XACCT
  257. help
  258. Collect information on the number of bytes of storage I/O which this
  259. task has caused.
  260. Say N if unsure.
  261. config AUDIT
  262. bool "Auditing support"
  263. depends on NET
  264. help
  265. Enable auditing infrastructure that can be used with another
  266. kernel subsystem, such as SELinux (which requires this for
  267. logging of avc messages output). Does not do system-call
  268. auditing without CONFIG_AUDITSYSCALL.
  269. config AUDITSYSCALL
  270. bool "Enable system-call auditing support"
  271. depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
  272. default y if SECURITY_SELINUX
  273. help
  274. Enable low-overhead system-call auditing infrastructure that
  275. can be used independently or with another kernel subsystem,
  276. such as SELinux.
  277. config AUDIT_WATCH
  278. def_bool y
  279. depends on AUDITSYSCALL
  280. select FSNOTIFY
  281. config AUDIT_TREE
  282. def_bool y
  283. depends on AUDITSYSCALL
  284. select FSNOTIFY
  285. source "kernel/irq/Kconfig"
  286. menu "RCU Subsystem"
  287. choice
  288. prompt "RCU Implementation"
  289. default TREE_RCU
  290. config TREE_RCU
  291. bool "Tree-based hierarchical RCU"
  292. depends on !PREEMPT && SMP
  293. help
  294. This option selects the RCU implementation that is
  295. designed for very large SMP system with hundreds or
  296. thousands of CPUs. It also scales down nicely to
  297. smaller systems.
  298. config TREE_PREEMPT_RCU
  299. bool "Preemptible tree-based hierarchical RCU"
  300. depends on PREEMPT
  301. help
  302. This option selects the RCU implementation that is
  303. designed for very large SMP systems with hundreds or
  304. thousands of CPUs, but for which real-time response
  305. is also required. It also scales down nicely to
  306. smaller systems.
  307. config TINY_RCU
  308. bool "UP-only small-memory-footprint RCU"
  309. depends on !SMP
  310. help
  311. This option selects the RCU implementation that is
  312. designed for UP systems from which real-time response
  313. is not required. This option greatly reduces the
  314. memory footprint of RCU.
  315. config TINY_PREEMPT_RCU
  316. bool "Preemptible UP-only small-memory-footprint RCU"
  317. depends on !SMP && PREEMPT
  318. help
  319. This option selects the RCU implementation that is designed
  320. for real-time UP systems. This option greatly reduces the
  321. memory footprint of RCU.
  322. endchoice
  323. config PREEMPT_RCU
  324. def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
  325. help
  326. This option enables preemptible-RCU code that is common between
  327. the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
  328. config RCU_TRACE
  329. bool "Enable tracing for RCU"
  330. help
  331. This option provides tracing in RCU which presents stats
  332. in debugfs for debugging RCU implementation.
  333. Say Y here if you want to enable RCU tracing
  334. Say N if you are unsure.
  335. config RCU_FANOUT
  336. int "Tree-based hierarchical RCU fanout value"
  337. range 2 64 if 64BIT
  338. range 2 32 if !64BIT
  339. depends on TREE_RCU || TREE_PREEMPT_RCU
  340. default 64 if 64BIT
  341. default 32 if !64BIT
  342. help
  343. This option controls the fanout of hierarchical implementations
  344. of RCU, allowing RCU to work efficiently on machines with
  345. large numbers of CPUs. This value must be at least the fourth
  346. root of NR_CPUS, which allows NR_CPUS to be insanely large.
  347. The default value of RCU_FANOUT should be used for production
  348. systems, but if you are stress-testing the RCU implementation
  349. itself, small RCU_FANOUT values allow you to test large-system
  350. code paths on small(er) systems.
  351. Select a specific number if testing RCU itself.
  352. Take the default if unsure.
  353. config RCU_FANOUT_EXACT
  354. bool "Disable tree-based hierarchical RCU auto-balancing"
  355. depends on TREE_RCU || TREE_PREEMPT_RCU
  356. default n
  357. help
  358. This option forces use of the exact RCU_FANOUT value specified,
  359. regardless of imbalances in the hierarchy. This is useful for
  360. testing RCU itself, and might one day be useful on systems with
  361. strong NUMA behavior.
  362. Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
  363. Say N if unsure.
  364. config RCU_FAST_NO_HZ
  365. bool "Accelerate last non-dyntick-idle CPU's grace periods"
  366. depends on TREE_RCU && NO_HZ && SMP
  367. default n
  368. help
  369. This option causes RCU to attempt to accelerate grace periods
  370. in order to allow the final CPU to enter dynticks-idle state
  371. more quickly. On the other hand, this option increases the
  372. overhead of the dynticks-idle checking, particularly on systems
  373. with large numbers of CPUs.
  374. Say Y if energy efficiency is critically important, particularly
  375. if you have relatively few CPUs.
  376. Say N if you are unsure.
  377. config TREE_RCU_TRACE
  378. def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
  379. select DEBUG_FS
  380. help
  381. This option provides tracing for the TREE_RCU and
  382. TREE_PREEMPT_RCU implementations, permitting Makefile to
  383. trivially select kernel/rcutree_trace.c.
  384. config RCU_BOOST
  385. bool "Enable RCU priority boosting"
  386. depends on RT_MUTEXES && TINY_PREEMPT_RCU
  387. default n
  388. help
  389. This option boosts the priority of preempted RCU readers that
  390. block the current preemptible RCU grace period for too long.
  391. This option also prevents heavy loads from blocking RCU
  392. callback invocation for all flavors of RCU.
  393. Say Y here if you are working with real-time apps or heavy loads
  394. Say N here if you are unsure.
  395. config RCU_BOOST_PRIO
  396. int "Real-time priority to boost RCU readers to"
  397. range 1 99
  398. depends on RCU_BOOST
  399. default 1
  400. help
  401. This option specifies the real-time priority to which preempted
  402. RCU readers are to be boosted. If you are working with CPU-bound
  403. real-time applications, you should specify a priority higher then
  404. the highest-priority CPU-bound application.
  405. Specify the real-time priority, or take the default if unsure.
  406. config RCU_BOOST_DELAY
  407. int "Milliseconds to delay boosting after RCU grace-period start"
  408. range 0 3000
  409. depends on RCU_BOOST
  410. default 500
  411. help
  412. This option specifies the time to wait after the beginning of
  413. a given grace period before priority-boosting preempted RCU
  414. readers blocking that grace period. Note that any RCU reader
  415. blocking an expedited RCU grace period is boosted immediately.
  416. Accept the default if unsure.
  417. endmenu # "RCU Subsystem"
  418. config IKCONFIG
  419. tristate "Kernel .config support"
  420. ---help---
  421. This option enables the complete Linux kernel ".config" file
  422. contents to be saved in the kernel. It provides documentation
  423. of which kernel options are used in a running kernel or in an
  424. on-disk kernel. This information can be extracted from the kernel
  425. image file with the script scripts/extract-ikconfig and used as
  426. input to rebuild the current kernel or to build another kernel.
  427. It can also be extracted from a running kernel by reading
  428. /proc/config.gz if enabled (below).
  429. config IKCONFIG_PROC
  430. bool "Enable access to .config through /proc/config.gz"
  431. depends on IKCONFIG && PROC_FS
  432. ---help---
  433. This option enables access to the kernel configuration file
  434. through /proc/config.gz.
  435. config LOG_BUF_SHIFT
  436. int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
  437. range 12 21
  438. default 17
  439. help
  440. Select kernel log buffer size as a power of 2.
  441. Examples:
  442. 17 => 128 KB
  443. 16 => 64 KB
  444. 15 => 32 KB
  445. 14 => 16 KB
  446. 13 => 8 KB
  447. 12 => 4 KB
  448. #
  449. # Architectures with an unreliable sched_clock() should select this:
  450. #
  451. config HAVE_UNSTABLE_SCHED_CLOCK
  452. bool
  453. menuconfig CGROUPS
  454. boolean "Control Group support"
  455. depends on EVENTFD
  456. help
  457. This option adds support for grouping sets of processes together, for
  458. use with process control subsystems such as Cpusets, CFS, memory
  459. controls or device isolation.
  460. See
  461. - Documentation/scheduler/sched-design-CFS.txt (CFS)
  462. - Documentation/cgroups/ (features for grouping, isolation
  463. and resource control)
  464. Say N if unsure.
  465. if CGROUPS
  466. config CGROUP_DEBUG
  467. bool "Example debug cgroup subsystem"
  468. default n
  469. help
  470. This option enables a simple cgroup subsystem that
  471. exports useful debugging information about the cgroups
  472. framework.
  473. Say N if unsure.
  474. config CGROUP_NS
  475. bool "Namespace cgroup subsystem"
  476. help
  477. Provides a simple namespace cgroup subsystem to
  478. provide hierarchical naming of sets of namespaces,
  479. for instance virtual servers and checkpoint/restart
  480. jobs.
  481. config CGROUP_FREEZER
  482. bool "Freezer cgroup subsystem"
  483. help
  484. Provides a way to freeze and unfreeze all tasks in a
  485. cgroup.
  486. config CGROUP_DEVICE
  487. bool "Device controller for cgroups"
  488. help
  489. Provides a cgroup implementing whitelists for devices which
  490. a process in the cgroup can mknod or open.
  491. config CPUSETS
  492. bool "Cpuset support"
  493. help
  494. This option will let you create and manage CPUSETs which
  495. allow dynamically partitioning a system into sets of CPUs and
  496. Memory Nodes and assigning tasks to run only within those sets.
  497. This is primarily useful on large SMP or NUMA systems.
  498. Say N if unsure.
  499. config PROC_PID_CPUSET
  500. bool "Include legacy /proc/<pid>/cpuset file"
  501. depends on CPUSETS
  502. default y
  503. config CGROUP_CPUACCT
  504. bool "Simple CPU accounting cgroup subsystem"
  505. help
  506. Provides a simple Resource Controller for monitoring the
  507. total CPU consumed by the tasks in a cgroup.
  508. config RESOURCE_COUNTERS
  509. bool "Resource counters"
  510. help
  511. This option enables controller independent resource accounting
  512. infrastructure that works with cgroups.
  513. config CGROUP_MEM_RES_CTLR
  514. bool "Memory Resource Controller for Control Groups"
  515. depends on RESOURCE_COUNTERS
  516. select MM_OWNER
  517. help
  518. Provides a memory resource controller that manages both anonymous
  519. memory and page cache. (See Documentation/cgroups/memory.txt)
  520. Note that setting this option increases fixed memory overhead
  521. associated with each page of memory in the system. By this,
  522. 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
  523. usage tracking struct at boot. Total amount of this is printed out
  524. at boot.
  525. Only enable when you're ok with these trade offs and really
  526. sure you need the memory resource controller. Even when you enable
  527. this, you can set "cgroup_disable=memory" at your boot option to
  528. disable memory resource controller and you can avoid overheads.
  529. (and lose benefits of memory resource controller)
  530. This config option also selects MM_OWNER config option, which
  531. could in turn add some fork/exit overhead.
  532. config CGROUP_MEM_RES_CTLR_SWAP
  533. bool "Memory Resource Controller Swap Extension"
  534. depends on CGROUP_MEM_RES_CTLR && SWAP
  535. help
  536. Add swap management feature to memory resource controller. When you
  537. enable this, you can limit mem+swap usage per cgroup. In other words,
  538. when you disable this, memory resource controller has no cares to
  539. usage of swap...a process can exhaust all of the swap. This extension
  540. is useful when you want to avoid exhaustion swap but this itself
  541. adds more overheads and consumes memory for remembering information.
  542. Especially if you use 32bit system or small memory system, please
  543. be careful about enabling this. When memory resource controller
  544. is disabled by boot option, this will be automatically disabled and
  545. there will be no overhead from this. Even when you set this config=y,
  546. if boot option "noswapaccount" is set, swap will not be accounted.
  547. Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
  548. size is 4096bytes, 512k per 1Gbytes of swap.
  549. config CGROUP_MEM_RES_CTLR_SWAP_ENABLED
  550. bool "Memory Resource Controller Swap Extension enabled by default"
  551. depends on CGROUP_MEM_RES_CTLR_SWAP
  552. default y
  553. help
  554. Memory Resource Controller Swap Extension comes with its price in
  555. a bigger memory consumption. General purpose distribution kernels
  556. which want to enable the feautre but keep it disabled by default
  557. and let the user enable it by swapaccount boot command line
  558. parameter should have this option unselected.
  559. For those who want to have the feature enabled by default should
  560. select this option (if, for some reason, they need to disable it
  561. then noswapaccount does the trick).
  562. menuconfig CGROUP_SCHED
  563. bool "Group CPU scheduler"
  564. depends on EXPERIMENTAL
  565. default n
  566. help
  567. This feature lets CPU scheduler recognize task groups and control CPU
  568. bandwidth allocation to such task groups. It uses cgroups to group
  569. tasks.
  570. if CGROUP_SCHED
  571. config FAIR_GROUP_SCHED
  572. bool "Group scheduling for SCHED_OTHER"
  573. depends on CGROUP_SCHED
  574. default CGROUP_SCHED
  575. config RT_GROUP_SCHED
  576. bool "Group scheduling for SCHED_RR/FIFO"
  577. depends on EXPERIMENTAL
  578. depends on CGROUP_SCHED
  579. default n
  580. help
  581. This feature lets you explicitly allocate real CPU bandwidth
  582. to task groups. If enabled, it will also make it impossible to
  583. schedule realtime tasks for non-root users until you allocate
  584. realtime bandwidth for them.
  585. See Documentation/scheduler/sched-rt-group.txt for more information.
  586. endif #CGROUP_SCHED
  587. config BLK_CGROUP
  588. tristate "Block IO controller"
  589. depends on BLOCK
  590. default n
  591. ---help---
  592. Generic block IO controller cgroup interface. This is the common
  593. cgroup interface which should be used by various IO controlling
  594. policies.
  595. Currently, CFQ IO scheduler uses it to recognize task groups and
  596. control disk bandwidth allocation (proportional time slice allocation)
  597. to such task groups. It is also used by bio throttling logic in
  598. block layer to implement upper limit in IO rates on a device.
  599. This option only enables generic Block IO controller infrastructure.
  600. One needs to also enable actual IO controlling logic/policy. For
  601. enabling proportional weight division of disk bandwidth in CFQ seti
  602. CONFIG_CFQ_GROUP_IOSCHED=y and for enabling throttling policy set
  603. CONFIG_BLK_THROTTLE=y.
  604. See Documentation/cgroups/blkio-controller.txt for more information.
  605. config DEBUG_BLK_CGROUP
  606. bool "Enable Block IO controller debugging"
  607. depends on BLK_CGROUP
  608. default n
  609. ---help---
  610. Enable some debugging help. Currently it exports additional stat
  611. files in a cgroup which can be useful for debugging.
  612. endif # CGROUPS
  613. menuconfig NAMESPACES
  614. bool "Namespaces support" if EMBEDDED
  615. default !EMBEDDED
  616. help
  617. Provides the way to make tasks work with different objects using
  618. the same id. For example same IPC id may refer to different objects
  619. or same user id or pid may refer to different tasks when used in
  620. different namespaces.
  621. if NAMESPACES
  622. config UTS_NS
  623. bool "UTS namespace"
  624. default y
  625. help
  626. In this namespace tasks see different info provided with the
  627. uname() system call
  628. config IPC_NS
  629. bool "IPC namespace"
  630. depends on (SYSVIPC || POSIX_MQUEUE)
  631. default y
  632. help
  633. In this namespace tasks work with IPC ids which correspond to
  634. different IPC objects in different namespaces.
  635. config USER_NS
  636. bool "User namespace (EXPERIMENTAL)"
  637. depends on EXPERIMENTAL
  638. default y
  639. help
  640. This allows containers, i.e. vservers, to use user namespaces
  641. to provide different user info for different servers.
  642. If unsure, say N.
  643. config PID_NS
  644. bool "PID Namespaces"
  645. default y
  646. help
  647. Support process id namespaces. This allows having multiple
  648. processes with the same pid as long as they are in different
  649. pid namespaces. This is a building block of containers.
  650. config NET_NS
  651. bool "Network namespace"
  652. depends on NET
  653. default y
  654. help
  655. Allow user space to create what appear to be multiple instances
  656. of the network stack.
  657. endif # NAMESPACES
  658. config MM_OWNER
  659. bool
  660. config SYSFS_DEPRECATED
  661. bool "enable deprecated sysfs features to support old userspace tools"
  662. depends on SYSFS
  663. default n
  664. help
  665. This option adds code that switches the layout of the "block" class
  666. devices, to not show up in /sys/class/block/, but only in
  667. /sys/block/.
  668. This switch is only active when the sysfs.deprecated=1 boot option is
  669. passed or the SYSFS_DEPRECATED_V2 option is set.
  670. This option allows new kernels to run on old distributions and tools,
  671. which might get confused by /sys/class/block/. Since 2007/2008 all
  672. major distributions and tools handle this just fine.
  673. Recent distributions and userspace tools after 2009/2010 depend on
  674. the existence of /sys/class/block/, and will not work with this
  675. option enabled.
  676. Only if you are using a new kernel on an old distribution, you might
  677. need to say Y here.
  678. config SYSFS_DEPRECATED_V2
  679. bool "enabled deprecated sysfs features by default"
  680. default n
  681. depends on SYSFS
  682. depends on SYSFS_DEPRECATED
  683. help
  684. Enable deprecated sysfs by default.
  685. See the CONFIG_SYSFS_DEPRECATED option for more details about this
  686. option.
  687. Only if you are using a new kernel on an old distribution, you might
  688. need to say Y here. Even then, odds are you would not need it
  689. enabled, you can always pass the boot option if absolutely necessary.
  690. config RELAY
  691. bool "Kernel->user space relay support (formerly relayfs)"
  692. help
  693. This option enables support for relay interface support in
  694. certain file systems (such as debugfs).
  695. It is designed to provide an efficient mechanism for tools and
  696. facilities to relay large amounts of data from kernel space to
  697. user space.
  698. If unsure, say N.
  699. config BLK_DEV_INITRD
  700. bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
  701. depends on BROKEN || !FRV
  702. help
  703. The initial RAM filesystem is a ramfs which is loaded by the
  704. boot loader (loadlin or lilo) and that is mounted as root
  705. before the normal boot procedure. It is typically used to
  706. load modules needed to mount the "real" root file system,
  707. etc. See <file:Documentation/initrd.txt> for details.
  708. If RAM disk support (BLK_DEV_RAM) is also included, this
  709. also enables initial RAM disk (initrd) support and adds
  710. 15 Kbytes (more on some other architectures) to the kernel size.
  711. If unsure say Y.
  712. if BLK_DEV_INITRD
  713. source "usr/Kconfig"
  714. endif
  715. config CC_OPTIMIZE_FOR_SIZE
  716. bool "Optimize for size"
  717. default y
  718. help
  719. Enabling this option will pass "-Os" instead of "-O2" to gcc
  720. resulting in a smaller kernel.
  721. If unsure, say Y.
  722. config SYSCTL
  723. bool
  724. config ANON_INODES
  725. bool
  726. menuconfig EMBEDDED
  727. bool "Configure standard kernel features (for small systems)"
  728. help
  729. This option allows certain base kernel options and settings
  730. to be disabled or tweaked. This is for specialized
  731. environments which can tolerate a "non-standard" kernel.
  732. Only use this if you really know what you are doing.
  733. config UID16
  734. bool "Enable 16-bit UID system calls" if EMBEDDED
  735. depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
  736. default y
  737. help
  738. This enables the legacy 16-bit UID syscall wrappers.
  739. config SYSCTL_SYSCALL
  740. bool "Sysctl syscall support" if EMBEDDED
  741. depends on PROC_SYSCTL
  742. default y
  743. select SYSCTL
  744. ---help---
  745. sys_sysctl uses binary paths that have been found challenging
  746. to properly maintain and use. The interface in /proc/sys
  747. using paths with ascii names is now the primary path to this
  748. information.
  749. Almost nothing using the binary sysctl interface so if you are
  750. trying to save some space it is probably safe to disable this,
  751. making your kernel marginally smaller.
  752. If unsure say Y here.
  753. config KALLSYMS
  754. bool "Load all symbols for debugging/ksymoops" if EMBEDDED
  755. default y
  756. help
  757. Say Y here to let the kernel print out symbolic crash information and
  758. symbolic stack backtraces. This increases the size of the kernel
  759. somewhat, as all symbols have to be loaded into the kernel image.
  760. config KALLSYMS_ALL
  761. bool "Include all symbols in kallsyms"
  762. depends on DEBUG_KERNEL && KALLSYMS
  763. help
  764. Normally kallsyms only contains the symbols of functions, for nicer
  765. OOPS messages. Some debuggers can use kallsyms for other
  766. symbols too: say Y here to include all symbols, if you need them
  767. and you don't care about adding 300k to the size of your kernel.
  768. Say N.
  769. config KALLSYMS_EXTRA_PASS
  770. bool "Do an extra kallsyms pass"
  771. depends on KALLSYMS
  772. help
  773. If kallsyms is not working correctly, the build will fail with
  774. inconsistent kallsyms data. If that occurs, log a bug report and
  775. turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
  776. Always say N here unless you find a bug in kallsyms, which must be
  777. reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
  778. you wait for kallsyms to be fixed.
  779. config HOTPLUG
  780. bool "Support for hot-pluggable devices" if EMBEDDED
  781. default y
  782. help
  783. This option is provided for the case where no hotplug or uevent
  784. capabilities is wanted by the kernel. You should only consider
  785. disabling this option for embedded systems that do not use modules, a
  786. dynamic /dev tree, or dynamic device discovery. Just say Y.
  787. config PRINTK
  788. default y
  789. bool "Enable support for printk" if EMBEDDED
  790. help
  791. This option enables normal printk support. Removing it
  792. eliminates most of the message strings from the kernel image
  793. and makes the kernel more or less silent. As this makes it
  794. very difficult to diagnose system problems, saying N here is
  795. strongly discouraged.
  796. config BUG
  797. bool "BUG() support" if EMBEDDED
  798. default y
  799. help
  800. Disabling this option eliminates support for BUG and WARN, reducing
  801. the size of your kernel image and potentially quietly ignoring
  802. numerous fatal conditions. You should only consider disabling this
  803. option for embedded systems with no facilities for reporting errors.
  804. Just say Y.
  805. config ELF_CORE
  806. default y
  807. bool "Enable ELF core dumps" if EMBEDDED
  808. help
  809. Enable support for generating core dumps. Disabling saves about 4k.
  810. config PCSPKR_PLATFORM
  811. bool "Enable PC-Speaker support" if EMBEDDED
  812. depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
  813. default y
  814. help
  815. This option allows to disable the internal PC-Speaker
  816. support, saving some memory.
  817. config BASE_FULL
  818. default y
  819. bool "Enable full-sized data structures for core" if EMBEDDED
  820. help
  821. Disabling this option reduces the size of miscellaneous core
  822. kernel data structures. This saves memory on small machines,
  823. but may reduce performance.
  824. config FUTEX
  825. bool "Enable futex support" if EMBEDDED
  826. default y
  827. select RT_MUTEXES
  828. help
  829. Disabling this option will cause the kernel to be built without
  830. support for "fast userspace mutexes". The resulting kernel may not
  831. run glibc-based applications correctly.
  832. config EPOLL
  833. bool "Enable eventpoll support" if EMBEDDED
  834. default y
  835. select ANON_INODES
  836. help
  837. Disabling this option will cause the kernel to be built without
  838. support for epoll family of system calls.
  839. config SIGNALFD
  840. bool "Enable signalfd() system call" if EMBEDDED
  841. select ANON_INODES
  842. default y
  843. help
  844. Enable the signalfd() system call that allows to receive signals
  845. on a file descriptor.
  846. If unsure, say Y.
  847. config TIMERFD
  848. bool "Enable timerfd() system call" if EMBEDDED
  849. select ANON_INODES
  850. default y
  851. help
  852. Enable the timerfd() system call that allows to receive timer
  853. events on a file descriptor.
  854. If unsure, say Y.
  855. config EVENTFD
  856. bool "Enable eventfd() system call" if EMBEDDED
  857. select ANON_INODES
  858. default y
  859. help
  860. Enable the eventfd() system call that allows to receive both
  861. kernel notification (ie. KAIO) or userspace notifications.
  862. If unsure, say Y.
  863. config SHMEM
  864. bool "Use full shmem filesystem" if EMBEDDED
  865. default y
  866. depends on MMU
  867. help
  868. The shmem is an internal filesystem used to manage shared memory.
  869. It is backed by swap and manages resource limits. It is also exported
  870. to userspace as tmpfs if TMPFS is enabled. Disabling this
  871. option replaces shmem and tmpfs with the much simpler ramfs code,
  872. which may be appropriate on small systems without swap.
  873. config AIO
  874. bool "Enable AIO support" if EMBEDDED
  875. default y
  876. help
  877. This option enables POSIX asynchronous I/O which may by used
  878. by some high performance threaded applications. Disabling
  879. this option saves about 7k.
  880. config HAVE_PERF_EVENTS
  881. bool
  882. help
  883. See tools/perf/design.txt for details.
  884. config PERF_USE_VMALLOC
  885. bool
  886. help
  887. See tools/perf/design.txt for details
  888. menu "Kernel Performance Events And Counters"
  889. config PERF_EVENTS
  890. bool "Kernel performance events and counters"
  891. default y if (PROFILING || PERF_COUNTERS)
  892. depends on HAVE_PERF_EVENTS
  893. select ANON_INODES
  894. select IRQ_WORK
  895. help
  896. Enable kernel support for various performance events provided
  897. by software and hardware.
  898. Software events are supported either built-in or via the
  899. use of generic tracepoints.
  900. Most modern CPUs support performance events via performance
  901. counter registers. These registers count the number of certain
  902. types of hw events: such as instructions executed, cachemisses
  903. suffered, or branches mis-predicted - without slowing down the
  904. kernel or applications. These registers can also trigger interrupts
  905. when a threshold number of events have passed - and can thus be
  906. used to profile the code that runs on that CPU.
  907. The Linux Performance Event subsystem provides an abstraction of
  908. these software and hardware event capabilities, available via a
  909. system call and used by the "perf" utility in tools/perf/. It
  910. provides per task and per CPU counters, and it provides event
  911. capabilities on top of those.
  912. Say Y if unsure.
  913. config PERF_COUNTERS
  914. bool "Kernel performance counters (old config option)"
  915. depends on HAVE_PERF_EVENTS
  916. help
  917. This config has been obsoleted by the PERF_EVENTS
  918. config option - please see that one for details.
  919. It has no effect on the kernel whether you enable
  920. it or not, it is a compatibility placeholder.
  921. Say N if unsure.
  922. config DEBUG_PERF_USE_VMALLOC
  923. default n
  924. bool "Debug: use vmalloc to back perf mmap() buffers"
  925. depends on PERF_EVENTS && DEBUG_KERNEL
  926. select PERF_USE_VMALLOC
  927. help
  928. Use vmalloc memory to back perf mmap() buffers.
  929. Mostly useful for debugging the vmalloc code on platforms
  930. that don't require it.
  931. Say N if unsure.
  932. endmenu
  933. config VM_EVENT_COUNTERS
  934. default y
  935. bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
  936. help
  937. VM event counters are needed for event counts to be shown.
  938. This option allows the disabling of the VM event counters
  939. on EMBEDDED systems. /proc/vmstat will only show page counts
  940. if VM event counters are disabled.
  941. config PCI_QUIRKS
  942. default y
  943. bool "Enable PCI quirk workarounds" if EMBEDDED
  944. depends on PCI
  945. help
  946. This enables workarounds for various PCI chipset
  947. bugs/quirks. Disable this only if your target machine is
  948. unaffected by PCI quirks.
  949. config SLUB_DEBUG
  950. default y
  951. bool "Enable SLUB debugging support" if EMBEDDED
  952. depends on SLUB && SYSFS
  953. help
  954. SLUB has extensive debug support features. Disabling these can
  955. result in significant savings in code size. This also disables
  956. SLUB sysfs support. /sys/slab will not exist and there will be
  957. no support for cache validation etc.
  958. config COMPAT_BRK
  959. bool "Disable heap randomization"
  960. default y
  961. help
  962. Randomizing heap placement makes heap exploits harder, but it
  963. also breaks ancient binaries (including anything libc5 based).
  964. This option changes the bootup default to heap randomization
  965. disabled, and can be overridden at runtime by setting
  966. /proc/sys/kernel/randomize_va_space to 2.
  967. On non-ancient distros (post-2000 ones) N is usually a safe choice.
  968. choice
  969. prompt "Choose SLAB allocator"
  970. default SLUB
  971. help
  972. This option allows to select a slab allocator.
  973. config SLAB
  974. bool "SLAB"
  975. help
  976. The regular slab allocator that is established and known to work
  977. well in all environments. It organizes cache hot objects in
  978. per cpu and per node queues.
  979. config SLUB
  980. bool "SLUB (Unqueued Allocator)"
  981. help
  982. SLUB is a slab allocator that minimizes cache line usage
  983. instead of managing queues of cached objects (SLAB approach).
  984. Per cpu caching is realized using slabs of objects instead
  985. of queues of objects. SLUB can use memory efficiently
  986. and has enhanced diagnostics. SLUB is the default choice for
  987. a slab allocator.
  988. config SLOB
  989. depends on EMBEDDED
  990. bool "SLOB (Simple Allocator)"
  991. help
  992. SLOB replaces the stock allocator with a drastically simpler
  993. allocator. SLOB is generally more space efficient but
  994. does not perform as well on large systems.
  995. endchoice
  996. config MMAP_ALLOW_UNINITIALIZED
  997. bool "Allow mmapped anonymous memory to be uninitialized"
  998. depends on EMBEDDED && !MMU
  999. default n
  1000. help
  1001. Normally, and according to the Linux spec, anonymous memory obtained
  1002. from mmap() has it's contents cleared before it is passed to
  1003. userspace. Enabling this config option allows you to request that
  1004. mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
  1005. providing a huge performance boost. If this option is not enabled,
  1006. then the flag will be ignored.
  1007. This is taken advantage of by uClibc's malloc(), and also by
  1008. ELF-FDPIC binfmt's brk and stack allocator.
  1009. Because of the obvious security issues, this option should only be
  1010. enabled on embedded devices where you control what is run in
  1011. userspace. Since that isn't generally a problem on no-MMU systems,
  1012. it is normally safe to say Y here.
  1013. See Documentation/nommu-mmap.txt for more information.
  1014. config PROFILING
  1015. bool "Profiling support"
  1016. help
  1017. Say Y here to enable the extended profiling support mechanisms used
  1018. by profilers such as OProfile.
  1019. #
  1020. # Place an empty function call at each tracepoint site. Can be
  1021. # dynamically changed for a probe function.
  1022. #
  1023. config TRACEPOINTS
  1024. bool
  1025. source "arch/Kconfig"
  1026. endmenu # General setup
  1027. config HAVE_GENERIC_DMA_COHERENT
  1028. bool
  1029. default n
  1030. config SLABINFO
  1031. bool
  1032. depends on PROC_FS
  1033. depends on SLAB || SLUB_DEBUG
  1034. default y
  1035. config RT_MUTEXES
  1036. boolean
  1037. config BASE_SMALL
  1038. int
  1039. default 0 if BASE_FULL
  1040. default 1 if !BASE_FULL
  1041. menuconfig MODULES
  1042. bool "Enable loadable module support"
  1043. help
  1044. Kernel modules are small pieces of compiled code which can
  1045. be inserted in the running kernel, rather than being
  1046. permanently built into the kernel. You use the "modprobe"
  1047. tool to add (and sometimes remove) them. If you say Y here,
  1048. many parts of the kernel can be built as modules (by
  1049. answering M instead of Y where indicated): this is most
  1050. useful for infrequently used options which are not required
  1051. for booting. For more information, see the man pages for
  1052. modprobe, lsmod, modinfo, insmod and rmmod.
  1053. If you say Y here, you will need to run "make
  1054. modules_install" to put the modules under /lib/modules/
  1055. where modprobe can find them (you may need to be root to do
  1056. this).
  1057. If unsure, say Y.
  1058. if MODULES
  1059. config MODULE_FORCE_LOAD
  1060. bool "Forced module loading"
  1061. default n
  1062. help
  1063. Allow loading of modules without version information (ie. modprobe
  1064. --force). Forced module loading sets the 'F' (forced) taint flag and
  1065. is usually a really bad idea.
  1066. config MODULE_UNLOAD
  1067. bool "Module unloading"
  1068. help
  1069. Without this option you will not be able to unload any
  1070. modules (note that some modules may not be unloadable
  1071. anyway), which makes your kernel smaller, faster
  1072. and simpler. If unsure, say Y.
  1073. config MODULE_FORCE_UNLOAD
  1074. bool "Forced module unloading"
  1075. depends on MODULE_UNLOAD && EXPERIMENTAL
  1076. help
  1077. This option allows you to force a module to unload, even if the
  1078. kernel believes it is unsafe: the kernel will remove the module
  1079. without waiting for anyone to stop using it (using the -f option to
  1080. rmmod). This is mainly for kernel developers and desperate users.
  1081. If unsure, say N.
  1082. config MODVERSIONS
  1083. bool "Module versioning support"
  1084. help
  1085. Usually, you have to use modules compiled with your kernel.
  1086. Saying Y here makes it sometimes possible to use modules
  1087. compiled for different kernels, by adding enough information
  1088. to the modules to (hopefully) spot any changes which would
  1089. make them incompatible with the kernel you are running. If
  1090. unsure, say N.
  1091. config MODULE_SRCVERSION_ALL
  1092. bool "Source checksum for all modules"
  1093. help
  1094. Modules which contain a MODULE_VERSION get an extra "srcversion"
  1095. field inserted into their modinfo section, which contains a
  1096. sum of the source files which made it. This helps maintainers
  1097. see exactly which source was used to build a module (since
  1098. others sometimes change the module source without updating
  1099. the version). With this option, such a "srcversion" field
  1100. will be created for all modules. If unsure, say N.
  1101. endif # MODULES
  1102. config INIT_ALL_POSSIBLE
  1103. bool
  1104. help
  1105. Back when each arch used to define their own cpu_online_map and
  1106. cpu_possible_map, some of them chose to initialize cpu_possible_map
  1107. with all 1s, and others with all 0s. When they were centralised,
  1108. it was better to provide this option than to break all the archs
  1109. and have several arch maintainers pursuing me down dark alleys.
  1110. config STOP_MACHINE
  1111. bool
  1112. default y
  1113. depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
  1114. help
  1115. Need stop_machine() primitive.
  1116. source "block/Kconfig"
  1117. config PREEMPT_NOTIFIERS
  1118. bool
  1119. config PADATA
  1120. depends on SMP
  1121. bool
  1122. source "kernel/Kconfig.locks"