Kconfig 52 KB

1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192939495969798991001011021031041051061071081091101111121131141151161171181191201211221231241251261271281291301311321331341351361371381391401411421431441451461471481491501511521531541551561571581591601611621631641651661671681691701711721731741751761771781791801811821831841851861871881891901911921931941951961971981992002012022032042052062072082092102112122132142152162172182192202212222232242252262272282292302312322332342352362372382392402412422432442452462472482492502512522532542552562572582592602612622632642652662672682692702712722732742752762772782792802812822832842852862872882892902912922932942952962972982993003013023033043053063073083093103113123133143153163173183193203213223233243253263273283293303313323333343353363373383393403413423433443453463473483493503513523533543553563573583593603613623633643653663673683693703713723733743753763773783793803813823833843853863873883893903913923933943953963973983994004014024034044054064074084094104114124134144154164174184194204214224234244254264274284294304314324334344354364374384394404414424434444454464474484494504514524534544554564574584594604614624634644654664674684694704714724734744754764774784794804814824834844854864874884894904914924934944954964974984995005015025035045055065075085095105115125135145155165175185195205215225235245255265275285295305315325335345355365375385395405415425435445455465475485495505515525535545555565575585595605615625635645655665675685695705715725735745755765775785795805815825835845855865875885895905915925935945955965975985996006016026036046056066076086096106116126136146156166176186196206216226236246256266276286296306316326336346356366376386396406416426436446456466476486496506516526536546556566576586596606616626636646656666676686696706716726736746756766776786796806816826836846856866876886896906916926936946956966976986997007017027037047057067077087097107117127137147157167177187197207217227237247257267277287297307317327337347357367377387397407417427437447457467477487497507517527537547557567577587597607617627637647657667677687697707717727737747757767777787797807817827837847857867877887897907917927937947957967977987998008018028038048058068078088098108118128138148158168178188198208218228238248258268278288298308318328338348358368378388398408418428438448458468478488498508518528538548558568578588598608618628638648658668678688698708718728738748758768778788798808818828838848858868878888898908918928938948958968978988999009019029039049059069079089099109119129139149159169179189199209219229239249259269279289299309319329339349359369379389399409419429439449459469479489499509519529539549559569579589599609619629639649659669679689699709719729739749759769779789799809819829839849859869879889899909919929939949959969979989991000100110021003100410051006100710081009101010111012101310141015101610171018101910201021102210231024102510261027102810291030103110321033103410351036103710381039104010411042104310441045104610471048104910501051105210531054105510561057105810591060106110621063106410651066106710681069107010711072107310741075107610771078107910801081108210831084108510861087108810891090109110921093109410951096109710981099110011011102110311041105110611071108110911101111111211131114111511161117111811191120112111221123112411251126112711281129113011311132113311341135113611371138113911401141114211431144114511461147114811491150115111521153115411551156115711581159116011611162116311641165116611671168116911701171117211731174117511761177117811791180118111821183118411851186118711881189119011911192119311941195119611971198119912001201120212031204120512061207120812091210121112121213121412151216121712181219122012211222122312241225122612271228122912301231123212331234123512361237123812391240124112421243124412451246124712481249125012511252125312541255125612571258125912601261126212631264126512661267126812691270127112721273127412751276127712781279128012811282128312841285128612871288128912901291129212931294129512961297129812991300130113021303130413051306130713081309131013111312131313141315131613171318131913201321132213231324132513261327132813291330133113321333133413351336133713381339134013411342134313441345134613471348134913501351135213531354135513561357135813591360136113621363136413651366136713681369137013711372137313741375137613771378137913801381138213831384138513861387138813891390139113921393139413951396139713981399140014011402140314041405140614071408140914101411141214131414141514161417141814191420142114221423142414251426142714281429143014311432143314341435143614371438143914401441144214431444144514461447144814491450145114521453145414551456145714581459146014611462146314641465146614671468146914701471147214731474147514761477147814791480148114821483148414851486148714881489149014911492149314941495149614971498149915001501150215031504150515061507150815091510151115121513151415151516151715181519152015211522152315241525152615271528152915301531153215331534153515361537153815391540154115421543154415451546154715481549155015511552155315541555155615571558155915601561156215631564156515661567156815691570157115721573157415751576157715781579158015811582158315841585158615871588158915901591159215931594159515961597159815991600160116021603160416051606160716081609161016111612161316141615161616171618161916201621162216231624162516261627162816291630163116321633163416351636163716381639164016411642164316441645164616471648164916501651165216531654165516561657165816591660
  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. config HAVE_IRQ_WORK
  20. bool
  21. config IRQ_WORK
  22. bool
  23. depends on HAVE_IRQ_WORK
  24. menu "General setup"
  25. config EXPERIMENTAL
  26. bool "Prompt for development and/or incomplete code/drivers"
  27. ---help---
  28. Some of the various things that Linux supports (such as network
  29. drivers, file systems, network protocols, etc.) can be in a state
  30. of development where the functionality, stability, or the level of
  31. testing is not yet high enough for general use. This is usually
  32. known as the "alpha-test" phase among developers. If a feature is
  33. currently in alpha-test, then the developers usually discourage
  34. uninformed widespread use of this feature by the general public to
  35. avoid "Why doesn't this work?" type mail messages. However, active
  36. testing and use of these systems is welcomed. Just be aware that it
  37. may not meet the normal level of reliability or it may fail to work
  38. in some special cases. Detailed bug reports from people familiar
  39. with the kernel internals are usually welcomed by the developers
  40. (before submitting bug reports, please read the documents
  41. <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
  42. <file:Documentation/BUG-HUNTING>, and
  43. <file:Documentation/oops-tracing.txt> in the kernel source).
  44. This option will also make obsoleted drivers available. These are
  45. drivers that have been replaced by something else, and/or are
  46. scheduled to be removed in a future kernel release.
  47. Unless you intend to help test and develop a feature or driver that
  48. falls into this category, or you have a situation that requires
  49. using these features, you should probably say N here, which will
  50. cause the configurator to present you with fewer choices. If
  51. you say Y here, you will be offered the choice of using features or
  52. drivers that are currently considered to be in the alpha-test phase.
  53. config BROKEN
  54. bool
  55. config BROKEN_ON_SMP
  56. bool
  57. depends on BROKEN || !SMP
  58. default y
  59. config INIT_ENV_ARG_LIMIT
  60. int
  61. default 32 if !UML
  62. default 128 if UML
  63. help
  64. Maximum of each of the number of arguments and environment
  65. variables passed to init from the kernel command line.
  66. config CROSS_COMPILE
  67. string "Cross-compiler tool prefix"
  68. help
  69. Same as running 'make CROSS_COMPILE=prefix-' but stored for
  70. default make runs in this kernel build directory. You don't
  71. need to set this unless you want the configured kernel build
  72. directory to select the cross-compiler automatically.
  73. config LOCALVERSION
  74. string "Local version - append to kernel release"
  75. help
  76. Append an extra string to the end of your kernel version.
  77. This will show up when you type uname, for example.
  78. The string you set here will be appended after the contents of
  79. any files with a filename matching localversion* in your
  80. object and source tree, in that order. Your total string can
  81. be a maximum of 64 characters.
  82. config LOCALVERSION_AUTO
  83. bool "Automatically append version information to the version string"
  84. default y
  85. help
  86. This will try to automatically determine if the current tree is a
  87. release tree by looking for git tags that belong to the current
  88. top of tree revision.
  89. A string of the format -gxxxxxxxx will be added to the localversion
  90. if a git-based tree is found. The string generated by this will be
  91. appended after any matching localversion* files, and after the value
  92. set in CONFIG_LOCALVERSION.
  93. (The actual string used here is the first eight characters produced
  94. by running the command:
  95. $ git rev-parse --verify HEAD
  96. which is done within the script "scripts/setlocalversion".)
  97. config HAVE_KERNEL_GZIP
  98. bool
  99. config HAVE_KERNEL_BZIP2
  100. bool
  101. config HAVE_KERNEL_LZMA
  102. bool
  103. config HAVE_KERNEL_XZ
  104. bool
  105. config HAVE_KERNEL_LZO
  106. bool
  107. config HAVE_KERNEL_LZ4
  108. bool
  109. choice
  110. prompt "Kernel compression mode"
  111. default KERNEL_GZIP
  112. depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4
  113. help
  114. The linux kernel is a kind of self-extracting executable.
  115. Several compression algorithms are available, which differ
  116. in efficiency, compression and decompression speed.
  117. Compression speed is only relevant when building a kernel.
  118. Decompression speed is relevant at each boot.
  119. If you have any problems with bzip2 or lzma compressed
  120. kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
  121. version of this functionality (bzip2 only), for 2.4, was
  122. supplied by Christian Ludwig)
  123. High compression options are mostly useful for users, who
  124. are low on disk space (embedded systems), but for whom ram
  125. size matters less.
  126. If in doubt, select 'gzip'
  127. config KERNEL_GZIP
  128. bool "Gzip"
  129. depends on HAVE_KERNEL_GZIP
  130. help
  131. The old and tried gzip compression. It provides a good balance
  132. between compression ratio and decompression speed.
  133. config KERNEL_BZIP2
  134. bool "Bzip2"
  135. depends on HAVE_KERNEL_BZIP2
  136. help
  137. Its compression ratio and speed is intermediate.
  138. Decompression speed is slowest among the three. The kernel
  139. size is about 10% smaller with bzip2, in comparison to gzip.
  140. Bzip2 uses a large amount of memory. For modern kernels you
  141. will need at least 8MB RAM or more for booting.
  142. config KERNEL_LZMA
  143. bool "LZMA"
  144. depends on HAVE_KERNEL_LZMA
  145. help
  146. The most recent compression algorithm.
  147. Its ratio is best, decompression speed is between the other
  148. two. Compression is slowest. The kernel size is about 33%
  149. smaller with LZMA in comparison to gzip.
  150. config KERNEL_XZ
  151. bool "XZ"
  152. depends on HAVE_KERNEL_XZ
  153. help
  154. XZ uses the LZMA2 algorithm and instruction set specific
  155. BCJ filters which can improve compression ratio of executable
  156. code. The size of the kernel is about 30% smaller with XZ in
  157. comparison to gzip. On architectures for which there is a BCJ
  158. filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
  159. will create a few percent smaller kernel than plain LZMA.
  160. The speed is about the same as with LZMA: The decompression
  161. speed of XZ is better than that of bzip2 but worse than gzip
  162. and LZO. Compression is slow.
  163. config KERNEL_LZO
  164. bool "LZO"
  165. depends on HAVE_KERNEL_LZO
  166. help
  167. Its compression ratio is the poorest among the 4. The kernel
  168. size is about 10% bigger than gzip; however its speed
  169. (both compression and decompression) is the fastest.
  170. config KERNEL_LZ4
  171. bool "LZ4"
  172. depends on HAVE_KERNEL_LZ4
  173. help
  174. LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
  175. A preliminary version of LZ4 de/compression tool is available at
  176. <https://code.google.com/p/lz4/>.
  177. Its compression ratio is worse than LZO. The size of the kernel
  178. is about 8% bigger than LZO. But the decompression speed is
  179. faster than LZO.
  180. endchoice
  181. config DEFAULT_HOSTNAME
  182. string "Default hostname"
  183. default "(none)"
  184. help
  185. This option determines the default system hostname before userspace
  186. calls sethostname(2). The kernel traditionally uses "(none)" here,
  187. but you may wish to use a different default here to make a minimal
  188. system more usable with less configuration.
  189. config SWAP
  190. bool "Support for paging of anonymous memory (swap)"
  191. depends on MMU && BLOCK
  192. default y
  193. help
  194. This option allows you to choose whether you want to have support
  195. for so called swap devices or swap files in your kernel that are
  196. used to provide more virtual memory than the actual RAM present
  197. in your computer. If unsure say Y.
  198. config SYSVIPC
  199. bool "System V IPC"
  200. ---help---
  201. Inter Process Communication is a suite of library functions and
  202. system calls which let processes (running programs) synchronize and
  203. exchange information. It is generally considered to be a good thing,
  204. and some programs won't run unless you say Y here. In particular, if
  205. you want to run the DOS emulator dosemu under Linux (read the
  206. DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
  207. you'll need to say Y here.
  208. You can find documentation about IPC with "info ipc" and also in
  209. section 6.4 of the Linux Programmer's Guide, available from
  210. <http://www.tldp.org/guides.html>.
  211. config SYSVIPC_SYSCTL
  212. bool
  213. depends on SYSVIPC
  214. depends on SYSCTL
  215. default y
  216. config POSIX_MQUEUE
  217. bool "POSIX Message Queues"
  218. depends on NET && EXPERIMENTAL
  219. ---help---
  220. POSIX variant of message queues is a part of IPC. In POSIX message
  221. queues every message has a priority which decides about succession
  222. of receiving it by a process. If you want to compile and run
  223. programs written e.g. for Solaris with use of its POSIX message
  224. queues (functions mq_*) say Y here.
  225. POSIX message queues are visible as a filesystem called 'mqueue'
  226. and can be mounted somewhere if you want to do filesystem
  227. operations on message queues.
  228. If unsure, say Y.
  229. config POSIX_MQUEUE_SYSCTL
  230. bool
  231. depends on POSIX_MQUEUE
  232. depends on SYSCTL
  233. default y
  234. config BSD_PROCESS_ACCT
  235. bool "BSD Process Accounting"
  236. help
  237. If you say Y here, a user level program will be able to instruct the
  238. kernel (via a special system call) to write process accounting
  239. information to a file: whenever a process exits, information about
  240. that process will be appended to the file by the kernel. The
  241. information includes things such as creation time, owning user,
  242. command name, memory usage, controlling terminal etc. (the complete
  243. list is in the struct acct in <file:include/linux/acct.h>). It is
  244. up to the user level program to do useful things with this
  245. information. This is generally a good idea, so say Y.
  246. config BSD_PROCESS_ACCT_V3
  247. bool "BSD Process Accounting version 3 file format"
  248. depends on BSD_PROCESS_ACCT
  249. default n
  250. help
  251. If you say Y here, the process accounting information is written
  252. in a new file format that also logs the process IDs of each
  253. process and it's parent. Note that this file format is incompatible
  254. with previous v0/v1/v2 file formats, so you will need updated tools
  255. for processing it. A preliminary version of these tools is available
  256. at <http://www.gnu.org/software/acct/>.
  257. config FHANDLE
  258. bool "open by fhandle syscalls"
  259. select EXPORTFS
  260. help
  261. If you say Y here, a user level program will be able to map
  262. file names to handle and then later use the handle for
  263. different file system operations. This is useful in implementing
  264. userspace file servers, which now track files using handles instead
  265. of names. The handle would remain the same even if file names
  266. get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
  267. syscalls.
  268. config TASKSTATS
  269. bool "Export task/process statistics through netlink (EXPERIMENTAL)"
  270. depends on NET
  271. default n
  272. help
  273. Export selected statistics for tasks/processes through the
  274. generic netlink interface. Unlike BSD process accounting, the
  275. statistics are available during the lifetime of tasks/processes as
  276. responses to commands. Like BSD accounting, they are sent to user
  277. space on task exit.
  278. Say N if unsure.
  279. config TASK_DELAY_ACCT
  280. bool "Enable per-task delay accounting (EXPERIMENTAL)"
  281. depends on TASKSTATS
  282. help
  283. Collect information on time spent by a task waiting for system
  284. resources like cpu, synchronous block I/O completion and swapping
  285. in pages. Such statistics can help in setting a task's priorities
  286. relative to other tasks for cpu, io, rss limits etc.
  287. Say N if unsure.
  288. config TASK_XACCT
  289. bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
  290. depends on TASKSTATS
  291. help
  292. Collect extended task accounting data and send the data
  293. to userland for processing over the taskstats interface.
  294. Say N if unsure.
  295. config TASK_IO_ACCOUNTING
  296. bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
  297. depends on TASK_XACCT
  298. help
  299. Collect information on the number of bytes of storage I/O which this
  300. task has caused.
  301. Say N if unsure.
  302. config AUDIT
  303. bool "Auditing support"
  304. depends on NET
  305. help
  306. Enable auditing infrastructure that can be used with another
  307. kernel subsystem, such as SELinux (which requires this for
  308. logging of avc messages output). Does not do system-call
  309. auditing without CONFIG_AUDITSYSCALL.
  310. config AUDITSYSCALL
  311. bool "Enable system-call auditing support"
  312. depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || ARM)
  313. default y if SECURITY_SELINUX
  314. help
  315. Enable low-overhead system-call auditing infrastructure that
  316. can be used independently or with another kernel subsystem,
  317. such as SELinux.
  318. config AUDIT_WATCH
  319. def_bool y
  320. depends on AUDITSYSCALL
  321. select FSNOTIFY
  322. config AUDIT_TREE
  323. def_bool y
  324. depends on AUDITSYSCALL
  325. select FSNOTIFY
  326. config AUDIT_LOGINUID_IMMUTABLE
  327. bool "Make audit loginuid immutable"
  328. depends on AUDIT
  329. help
  330. The config option toggles if a task setting its loginuid requires
  331. CAP_SYS_AUDITCONTROL or if that task should require no special permissions
  332. but should instead only allow setting its loginuid if it was never
  333. previously set. On systems which use systemd or a similar central
  334. process to restart login services this should be set to true. On older
  335. systems in which an admin would typically have to directly stop and
  336. start processes this should be set to false. Setting this to true allows
  337. one to drop potentially dangerous capabilites from the login tasks,
  338. but may not be backwards compatible with older init systems.
  339. source "kernel/irq/Kconfig"
  340. source "kernel/time/Kconfig"
  341. menu "RCU Subsystem"
  342. choice
  343. prompt "RCU Implementation"
  344. default TREE_RCU
  345. config TREE_RCU
  346. bool "Tree-based hierarchical RCU"
  347. depends on !PREEMPT && SMP
  348. help
  349. This option selects the RCU implementation that is
  350. designed for very large SMP system with hundreds or
  351. thousands of CPUs. It also scales down nicely to
  352. smaller systems.
  353. config TREE_PREEMPT_RCU
  354. bool "Preemptible tree-based hierarchical RCU"
  355. depends on PREEMPT && SMP
  356. help
  357. This option selects the RCU implementation that is
  358. designed for very large SMP systems with hundreds or
  359. thousands of CPUs, but for which real-time response
  360. is also required. It also scales down nicely to
  361. smaller systems.
  362. config TINY_RCU
  363. bool "UP-only small-memory-footprint RCU"
  364. depends on !PREEMPT && !SMP
  365. help
  366. This option selects the RCU implementation that is
  367. designed for UP systems from which real-time response
  368. is not required. This option greatly reduces the
  369. memory footprint of RCU.
  370. config TINY_PREEMPT_RCU
  371. bool "Preemptible UP-only small-memory-footprint RCU"
  372. depends on PREEMPT && !SMP
  373. help
  374. This option selects the RCU implementation that is designed
  375. for real-time UP systems. This option greatly reduces the
  376. memory footprint of RCU.
  377. endchoice
  378. config PREEMPT_RCU
  379. def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
  380. help
  381. This option enables preemptible-RCU code that is common between
  382. the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
  383. config RCU_FANOUT
  384. int "Tree-based hierarchical RCU fanout value"
  385. range 2 64 if 64BIT
  386. range 2 32 if !64BIT
  387. depends on TREE_RCU || TREE_PREEMPT_RCU
  388. default 64 if 64BIT
  389. default 32 if !64BIT
  390. help
  391. This option controls the fanout of hierarchical implementations
  392. of RCU, allowing RCU to work efficiently on machines with
  393. large numbers of CPUs. This value must be at least the fourth
  394. root of NR_CPUS, which allows NR_CPUS to be insanely large.
  395. The default value of RCU_FANOUT should be used for production
  396. systems, but if you are stress-testing the RCU implementation
  397. itself, small RCU_FANOUT values allow you to test large-system
  398. code paths on small(er) systems.
  399. Select a specific number if testing RCU itself.
  400. Take the default if unsure.
  401. config RCU_FANOUT_EXACT
  402. bool "Disable tree-based hierarchical RCU auto-balancing"
  403. depends on TREE_RCU || TREE_PREEMPT_RCU
  404. default n
  405. help
  406. This option forces use of the exact RCU_FANOUT value specified,
  407. regardless of imbalances in the hierarchy. This is useful for
  408. testing RCU itself, and might one day be useful on systems with
  409. strong NUMA behavior.
  410. Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
  411. Say N if unsure.
  412. config RCU_FAST_NO_HZ
  413. bool "Accelerate last non-dyntick-idle CPU's grace periods"
  414. depends on NO_HZ && SMP && !SEC_FACTORY
  415. default n
  416. help
  417. This option causes RCU to attempt to accelerate grace periods
  418. in order to allow CPUs to enter dynticks-idle state more
  419. quickly. On the other hand, this option increases the overhead
  420. of the dynticks-idle checking, particularly on systems with
  421. large numbers of CPUs.
  422. Say Y if energy efficiency is critically important, particularly
  423. if you have relatively few CPUs.
  424. Say N if you are unsure.
  425. config RCU_FAST_NO_HZ_OFF_AT_BOOT
  426. bool "turn off rcu_fast_no_hz concept at boot time"
  427. depends on RCU_FAST_NO_HZ
  428. default n
  429. config TREE_RCU_TRACE
  430. def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
  431. select DEBUG_FS
  432. help
  433. This option provides tracing for the TREE_RCU and
  434. TREE_PREEMPT_RCU implementations, permitting Makefile to
  435. trivially select kernel/rcutree_trace.c.
  436. config RCU_BOOST
  437. bool "Enable RCU priority boosting"
  438. depends on RT_MUTEXES && PREEMPT_RCU
  439. default n
  440. help
  441. This option boosts the priority of preempted RCU readers that
  442. block the current preemptible RCU grace period for too long.
  443. This option also prevents heavy loads from blocking RCU
  444. callback invocation for all flavors of RCU.
  445. Say Y here if you are working with real-time apps or heavy loads
  446. Say N here if you are unsure.
  447. config RCU_BOOST_PRIO
  448. int "Real-time priority to boost RCU readers to"
  449. range 1 99
  450. depends on RCU_BOOST
  451. default 1
  452. help
  453. This option specifies the real-time priority to which long-term
  454. preempted RCU readers are to be boosted. If you are working
  455. with a real-time application that has one or more CPU-bound
  456. threads running at a real-time priority level, you should set
  457. RCU_BOOST_PRIO to a priority higher then the highest-priority
  458. real-time CPU-bound thread. The default RCU_BOOST_PRIO value
  459. of 1 is appropriate in the common case, which is real-time
  460. applications that do not have any CPU-bound threads.
  461. Some real-time applications might not have a single real-time
  462. thread that saturates a given CPU, but instead might have
  463. multiple real-time threads that, taken together, fully utilize
  464. that CPU. In this case, you should set RCU_BOOST_PRIO to
  465. a priority higher than the lowest-priority thread that is
  466. conspiring to prevent the CPU from running any non-real-time
  467. tasks. For example, if one thread at priority 10 and another
  468. thread at priority 5 are between themselves fully consuming
  469. the CPU time on a given CPU, then RCU_BOOST_PRIO should be
  470. set to priority 6 or higher.
  471. Specify the real-time priority, or take the default if unsure.
  472. config RCU_BOOST_DELAY
  473. int "Milliseconds to delay boosting after RCU grace-period start"
  474. range 0 3000
  475. depends on RCU_BOOST
  476. default 500
  477. help
  478. This option specifies the time to wait after the beginning of
  479. a given grace period before priority-boosting preempted RCU
  480. readers blocking that grace period. Note that any RCU reader
  481. blocking an expedited RCU grace period is boosted immediately.
  482. Accept the default if unsure.
  483. endmenu # "RCU Subsystem"
  484. config BUILD_BIN2C
  485. bool
  486. default n
  487. config IKCONFIG
  488. tristate "Kernel .config support"
  489. select BUILD_BIN2C
  490. ---help---
  491. This option enables the complete Linux kernel ".config" file
  492. contents to be saved in the kernel. It provides documentation
  493. of which kernel options are used in a running kernel or in an
  494. on-disk kernel. This information can be extracted from the kernel
  495. image file with the script scripts/extract-ikconfig and used as
  496. input to rebuild the current kernel or to build another kernel.
  497. It can also be extracted from a running kernel by reading
  498. /proc/config.gz if enabled (below).
  499. config IKCONFIG_PROC
  500. bool "Enable access to .config through /proc/config.gz"
  501. depends on IKCONFIG && PROC_FS
  502. ---help---
  503. This option enables access to the kernel configuration file
  504. through /proc/config.gz.
  505. config LOG_BUF_SHIFT
  506. int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
  507. range 12 21
  508. default 17
  509. depends on PRINTK
  510. help
  511. Select kernel log buffer size as a power of 2.
  512. Examples:
  513. 17 => 128 KB
  514. 16 => 64 KB
  515. 15 => 32 KB
  516. 14 => 16 KB
  517. 13 => 8 KB
  518. 12 => 4 KB
  519. #
  520. # Architectures with an unreliable sched_clock() should select this:
  521. #
  522. config HAVE_UNSTABLE_SCHED_CLOCK
  523. bool
  524. config GENERIC_SCHED_CLOCK
  525. bool
  526. menuconfig CGROUPS
  527. boolean "Control Group support"
  528. depends on EVENTFD
  529. help
  530. This option adds support for grouping sets of processes together, for
  531. use with process control subsystems such as Cpusets, CFS, memory
  532. controls or device isolation.
  533. See
  534. - Documentation/scheduler/sched-design-CFS.txt (CFS)
  535. - Documentation/cgroups/ (features for grouping, isolation
  536. and resource control)
  537. Say N if unsure.
  538. if CGROUPS
  539. config CGROUP_DEBUG
  540. bool "Example debug cgroup subsystem"
  541. default n
  542. help
  543. This option enables a simple cgroup subsystem that
  544. exports useful debugging information about the cgroups
  545. framework.
  546. Say N if unsure.
  547. config CGROUP_FREEZER
  548. bool "Freezer cgroup subsystem"
  549. help
  550. Provides a way to freeze and unfreeze all tasks in a
  551. cgroup.
  552. config CGROUP_DEVICE
  553. bool "Device controller for cgroups"
  554. help
  555. Provides a cgroup implementing whitelists for devices which
  556. a process in the cgroup can mknod or open.
  557. config CPUSETS
  558. bool "Cpuset support"
  559. help
  560. This option will let you create and manage CPUSETs which
  561. allow dynamically partitioning a system into sets of CPUs and
  562. Memory Nodes and assigning tasks to run only within those sets.
  563. This is primarily useful on large SMP or NUMA systems.
  564. Say N if unsure.
  565. config PROC_PID_CPUSET
  566. bool "Include legacy /proc/<pid>/cpuset file"
  567. depends on CPUSETS
  568. default y
  569. config CGROUP_CPUACCT
  570. bool "Simple CPU accounting cgroup subsystem"
  571. help
  572. Provides a simple Resource Controller for monitoring the
  573. total CPU consumed by the tasks in a cgroup.
  574. config RESOURCE_COUNTERS
  575. bool "Resource counters"
  576. help
  577. This option enables controller independent resource accounting
  578. infrastructure that works with cgroups.
  579. config MEMCG
  580. bool "Memory Resource Controller for Control Groups"
  581. depends on RESOURCE_COUNTERS
  582. select MM_OWNER
  583. help
  584. Provides a memory resource controller that manages both anonymous
  585. memory and page cache. (See Documentation/cgroups/memory.txt)
  586. Note that setting this option increases fixed memory overhead
  587. associated with each page of memory in the system. By this,
  588. 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
  589. usage tracking struct at boot. Total amount of this is printed out
  590. at boot.
  591. Only enable when you're ok with these trade offs and really
  592. sure you need the memory resource controller. Even when you enable
  593. this, you can set "cgroup_disable=memory" at your boot option to
  594. disable memory resource controller and you can avoid overheads.
  595. (and lose benefits of memory resource controller)
  596. This config option also selects MM_OWNER config option, which
  597. could in turn add some fork/exit overhead.
  598. config MEMCG_SWAP
  599. bool "Memory Resource Controller Swap Extension"
  600. depends on MEMCG && SWAP
  601. help
  602. Add swap management feature to memory resource controller. When you
  603. enable this, you can limit mem+swap usage per cgroup. In other words,
  604. when you disable this, memory resource controller has no cares to
  605. usage of swap...a process can exhaust all of the swap. This extension
  606. is useful when you want to avoid exhaustion swap but this itself
  607. adds more overheads and consumes memory for remembering information.
  608. Especially if you use 32bit system or small memory system, please
  609. be careful about enabling this. When memory resource controller
  610. is disabled by boot option, this will be automatically disabled and
  611. there will be no overhead from this. Even when you set this config=y,
  612. if boot option "swapaccount=0" is set, swap will not be accounted.
  613. Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
  614. size is 4096bytes, 512k per 1Gbytes of swap.
  615. config MEMCG_SWAP_ENABLED
  616. bool "Memory Resource Controller Swap Extension enabled by default"
  617. depends on MEMCG_SWAP
  618. default y
  619. help
  620. Memory Resource Controller Swap Extension comes with its price in
  621. a bigger memory consumption. General purpose distribution kernels
  622. which want to enable the feature but keep it disabled by default
  623. and let the user enable it by swapaccount boot command line
  624. parameter should have this option unselected.
  625. For those who want to have the feature enabled by default should
  626. select this option (if, for some reason, they need to disable it
  627. then swapaccount=0 does the trick).
  628. config MEMCG_KMEM
  629. bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
  630. depends on MEMCG && EXPERIMENTAL
  631. default n
  632. help
  633. The Kernel Memory extension for Memory Resource Controller can limit
  634. the amount of memory used by kernel objects in the system. Those are
  635. fundamentally different from the entities handled by the standard
  636. Memory Controller, which are page-based, and can be swapped. Users of
  637. the kmem extension can use it to guarantee that no group of processes
  638. will ever exhaust kernel resources alone.
  639. config CGROUP_PERF
  640. bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
  641. depends on PERF_EVENTS && CGROUPS
  642. help
  643. This option extends the per-cpu mode to restrict monitoring to
  644. threads which belong to the cgroup specified and run on the
  645. designated cpu.
  646. Say N if unsure.
  647. menuconfig CGROUP_SCHED
  648. bool "Group CPU scheduler"
  649. default n
  650. help
  651. This feature lets CPU scheduler recognize task groups and control CPU
  652. bandwidth allocation to such task groups. It uses cgroups to group
  653. tasks.
  654. if CGROUP_SCHED
  655. config FAIR_GROUP_SCHED
  656. bool "Group scheduling for SCHED_OTHER"
  657. depends on CGROUP_SCHED
  658. default CGROUP_SCHED
  659. config CFS_BANDWIDTH
  660. bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
  661. depends on EXPERIMENTAL
  662. depends on FAIR_GROUP_SCHED
  663. default n
  664. help
  665. This option allows users to define CPU bandwidth rates (limits) for
  666. tasks running within the fair group scheduler. Groups with no limit
  667. set are considered to be unconstrained and will run with no
  668. restriction.
  669. See tip/Documentation/scheduler/sched-bwc.txt for more information.
  670. config RT_GROUP_SCHED
  671. bool "Group scheduling for SCHED_RR/FIFO"
  672. depends on EXPERIMENTAL
  673. depends on CGROUP_SCHED
  674. default n
  675. help
  676. This feature lets you explicitly allocate real CPU bandwidth
  677. to task groups. If enabled, it will also make it impossible to
  678. schedule realtime tasks for non-root users until you allocate
  679. realtime bandwidth for them.
  680. See Documentation/scheduler/sched-rt-group.txt for more information.
  681. endif #CGROUP_SCHED
  682. config BLK_CGROUP
  683. tristate "Block IO controller"
  684. depends on BLOCK
  685. default n
  686. ---help---
  687. Generic block IO controller cgroup interface. This is the common
  688. cgroup interface which should be used by various IO controlling
  689. policies.
  690. Currently, CFQ IO scheduler uses it to recognize task groups and
  691. control disk bandwidth allocation (proportional time slice allocation)
  692. to such task groups. It is also used by bio throttling logic in
  693. block layer to implement upper limit in IO rates on a device.
  694. This option only enables generic Block IO controller infrastructure.
  695. One needs to also enable actual IO controlling logic/policy. For
  696. enabling proportional weight division of disk bandwidth in CFQ, set
  697. CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
  698. CONFIG_BLK_DEV_THROTTLING=y.
  699. See Documentation/cgroups/blkio-controller.txt for more information.
  700. config DEBUG_BLK_CGROUP
  701. bool "Enable Block IO controller debugging"
  702. depends on BLK_CGROUP
  703. default n
  704. ---help---
  705. Enable some debugging help. Currently it exports additional stat
  706. files in a cgroup which can be useful for debugging.
  707. endif # CGROUPS
  708. config CHECKPOINT_RESTORE
  709. bool "Checkpoint/restore support" if EXPERT
  710. default n
  711. help
  712. Enables additional kernel features in a sake of checkpoint/restore.
  713. In particular it adds auxiliary prctl codes to setup process text,
  714. data and heap segment sizes, and a few additional /proc filesystem
  715. entries.
  716. If unsure, say N here.
  717. menuconfig NAMESPACES
  718. bool "Namespaces support" if EXPERT
  719. default !EXPERT
  720. help
  721. Provides the way to make tasks work with different objects using
  722. the same id. For example same IPC id may refer to different objects
  723. or same user id or pid may refer to different tasks when used in
  724. different namespaces.
  725. if NAMESPACES
  726. config UTS_NS
  727. bool "UTS namespace"
  728. default y
  729. help
  730. In this namespace tasks see different info provided with the
  731. uname() system call
  732. config IPC_NS
  733. bool "IPC namespace"
  734. depends on (SYSVIPC || POSIX_MQUEUE)
  735. default y
  736. help
  737. In this namespace tasks work with IPC ids which correspond to
  738. different IPC objects in different namespaces.
  739. config USER_NS
  740. bool "User namespace (EXPERIMENTAL)"
  741. depends on EXPERIMENTAL
  742. depends on UIDGID_CONVERTED
  743. select UIDGID_STRICT_TYPE_CHECKS
  744. default n
  745. help
  746. This allows containers, i.e. vservers, to use user namespaces
  747. to provide different user info for different servers.
  748. When user namespaces are enabled in the kernel it is
  749. recommended that the MEMCG and MEMCG_KMEM options also be
  750. enabled and that user-space use the memory control groups to
  751. limit the amount of memory a memory unprivileged users can
  752. use.
  753. If unsure, say N.
  754. config PID_NS
  755. bool "PID Namespaces"
  756. default y
  757. help
  758. Support process id namespaces. This allows having multiple
  759. processes with the same pid as long as they are in different
  760. pid namespaces. This is a building block of containers.
  761. config NET_NS
  762. bool "Network namespace"
  763. depends on NET
  764. default y
  765. help
  766. Allow user space to create what appear to be multiple instances
  767. of the network stack.
  768. endif # NAMESPACES
  769. config UIDGID_CONVERTED
  770. # True if all of the selected software conmponents are known
  771. # to have uid_t and gid_t converted to kuid_t and kgid_t
  772. # where appropriate and are otherwise safe to use with
  773. # the user namespace.
  774. bool
  775. default y
  776. # List of kernel pieces that need user namespace work
  777. # Features
  778. depends on BINFMT_ELF = n
  779. depends on BINFMT_ELF_FDPIC = n
  780. depends on UNIX98_PTYS = n
  781. depends on CGROUPS = n
  782. depends on MIGRATION = n
  783. depends on NUMA = n
  784. depends on IMA = n
  785. depends on EVM = n
  786. depends on KEYS = n
  787. depends on AUDIT = n
  788. depends on AUDITSYSCALL = n
  789. depends on TASKSTATS = n
  790. depends on TRACING = n
  791. depends on FS_POSIX_ACL = n
  792. depends on QUOTA = n
  793. depends on QUOTACTL = n
  794. depends on DEBUG_CREDENTIALS = n
  795. depends on BSD_PROCESS_ACCT = n
  796. depends on DRM = n
  797. depends on PROC_EVENTS = n
  798. # Networking
  799. depends on NET = n
  800. depends on NET_9P = n
  801. depends on IPX = n
  802. depends on PHONET = n
  803. depends on NET_CLS_FLOW = n
  804. depends on NETFILTER_XT_MATCH_OWNER = n
  805. depends on NETFILTER_XT_MATCH_RECENT = n
  806. depends on NETFILTER_XT_TARGET_LOG = n
  807. depends on NETFILTER_NETLINK_LOG = n
  808. depends on INET = n
  809. depends on IPV6 = n
  810. depends on IP_SCTP = n
  811. depends on AF_RXRPC = n
  812. depends on LLC2 = n
  813. depends on NET_KEY = n
  814. depends on INET_DIAG = n
  815. depends on DNS_RESOLVER = n
  816. depends on AX25 = n
  817. depends on ATALK = n
  818. # Filesystems
  819. depends on USB_DEVICEFS = n
  820. depends on USB_GADGETFS = n
  821. depends on USB_FUNCTIONFS = n
  822. depends on DEVTMPFS = n
  823. depends on XENFS = n
  824. depends on 9P_FS = n
  825. depends on ADFS_FS = n
  826. depends on AFFS_FS = n
  827. depends on AFS_FS = n
  828. depends on AUTOFS4_FS = n
  829. depends on BEFS_FS = n
  830. depends on BFS_FS = n
  831. depends on BTRFS_FS = n
  832. depends on CEPH_FS = n
  833. depends on CIFS = n
  834. depends on CODA_FS = n
  835. depends on CONFIGFS_FS = n
  836. depends on CRAMFS = n
  837. depends on DEBUG_FS = n
  838. depends on ECRYPT_FS = n
  839. depends on EFS_FS = n
  840. depends on EXOFS_FS = n
  841. depends on EXT2_FS = n
  842. depends on EXT3_FS = n
  843. depends on EXT4_FS = n
  844. depends on FAT_FS = n
  845. depends on FUSE_FS = n
  846. depends on GFS2_FS = n
  847. depends on HFS_FS = n
  848. depends on HFSPLUS_FS = n
  849. depends on HPFS_FS = n
  850. depends on HUGETLBFS = n
  851. depends on ISO9660_FS = n
  852. depends on JFFS2_FS = n
  853. depends on JFS_FS = n
  854. depends on LOGFS = n
  855. depends on MINIX_FS = n
  856. depends on NCP_FS = n
  857. depends on NFSD = n
  858. depends on NFS_FS = n
  859. depends on NILFS2_FS = n
  860. depends on NTFS_FS = n
  861. depends on OCFS2_FS = n
  862. depends on OMFS_FS = n
  863. depends on PROC_SYSCTL = n
  864. depends on QNX4FS_FS = n
  865. depends on QNX6FS_FS = n
  866. depends on REISERFS_FS = n
  867. depends on SQUASHFS = n
  868. depends on SYSFS = n
  869. depends on SYSV_FS = n
  870. depends on TMPFS = n
  871. depends on UBIFS_FS = n
  872. depends on UDF_FS = n
  873. depends on UFS_FS = n
  874. depends on VXFS_FS = n
  875. depends on XFS_FS = n
  876. depends on !UML || HOSTFS = n
  877. # The rare drivers that won't build
  878. depends on AIRO = n
  879. depends on AIRO_CS = n
  880. depends on TUN = n
  881. depends on INFINIBAND_QIB = n
  882. depends on BLK_DEV_LOOP = n
  883. depends on ANDROID_BINDER_IPC = n
  884. # Security modules
  885. depends on SECURITY_TOMOYO = n
  886. depends on SECURITY_APPARMOR = n
  887. config UIDGID_STRICT_TYPE_CHECKS
  888. bool "Require conversions between uid/gids and their internal representation"
  889. depends on UIDGID_CONVERTED
  890. default n
  891. help
  892. While the nececessary conversions are being added to all subsystems this option allows
  893. the code to continue to build for unconverted subsystems.
  894. Say Y here if you want the strict type checking enabled
  895. config SCHED_AUTOGROUP
  896. bool "Automatic process group scheduling"
  897. select EVENTFD
  898. select CGROUPS
  899. select CGROUP_SCHED
  900. select FAIR_GROUP_SCHED
  901. help
  902. This option optimizes the scheduler for common desktop workloads by
  903. automatically creating and populating task groups. This separation
  904. of workloads isolates aggressive CPU burners (like build jobs) from
  905. desktop applications. Task group autogeneration is currently based
  906. upon task session.
  907. config MM_OWNER
  908. bool
  909. config SYSFS_DEPRECATED
  910. bool "Enable deprecated sysfs features to support old userspace tools"
  911. depends on SYSFS
  912. default n
  913. help
  914. This option adds code that switches the layout of the "block" class
  915. devices, to not show up in /sys/class/block/, but only in
  916. /sys/block/.
  917. This switch is only active when the sysfs.deprecated=1 boot option is
  918. passed or the SYSFS_DEPRECATED_V2 option is set.
  919. This option allows new kernels to run on old distributions and tools,
  920. which might get confused by /sys/class/block/. Since 2007/2008 all
  921. major distributions and tools handle this just fine.
  922. Recent distributions and userspace tools after 2009/2010 depend on
  923. the existence of /sys/class/block/, and will not work with this
  924. option enabled.
  925. Only if you are using a new kernel on an old distribution, you might
  926. need to say Y here.
  927. config SYSFS_DEPRECATED_V2
  928. bool "Enable deprecated sysfs features by default"
  929. default n
  930. depends on SYSFS
  931. depends on SYSFS_DEPRECATED
  932. help
  933. Enable deprecated sysfs by default.
  934. See the CONFIG_SYSFS_DEPRECATED option for more details about this
  935. option.
  936. Only if you are using a new kernel on an old distribution, you might
  937. need to say Y here. Even then, odds are you would not need it
  938. enabled, you can always pass the boot option if absolutely necessary.
  939. config RELAY
  940. bool "Kernel->user space relay support (formerly relayfs)"
  941. help
  942. This option enables support for relay interface support in
  943. certain file systems (such as debugfs).
  944. It is designed to provide an efficient mechanism for tools and
  945. facilities to relay large amounts of data from kernel space to
  946. user space.
  947. If unsure, say N.
  948. config BLK_DEV_INITRD
  949. bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
  950. depends on BROKEN || !FRV
  951. help
  952. The initial RAM filesystem is a ramfs which is loaded by the
  953. boot loader (loadlin or lilo) and that is mounted as root
  954. before the normal boot procedure. It is typically used to
  955. load modules needed to mount the "real" root file system,
  956. etc. See <file:Documentation/initrd.txt> for details.
  957. If RAM disk support (BLK_DEV_RAM) is also included, this
  958. also enables initial RAM disk (initrd) support and adds
  959. 15 Kbytes (more on some other architectures) to the kernel size.
  960. If unsure say Y.
  961. if BLK_DEV_INITRD
  962. source "usr/Kconfig"
  963. endif
  964. config CC_OPTIMIZE_FOR_SIZE
  965. bool "Optimize for size"
  966. help
  967. Enabling this option will pass "-Os" instead of "-O2" to gcc
  968. resulting in a smaller kernel.
  969. If unsure, say Y.
  970. config SYSCTL
  971. bool
  972. config ANON_INODES
  973. bool
  974. config PANIC_TIMEOUT
  975. int "Default panic timeout"
  976. default 0
  977. help
  978. Set default panic timeout.
  979. menuconfig EXPERT
  980. bool "Configure standard kernel features (expert users)"
  981. # Unhide debug options, to make the on-by-default options visible
  982. select DEBUG_KERNEL
  983. help
  984. This option allows certain base kernel options and settings
  985. to be disabled or tweaked. This is for specialized
  986. environments which can tolerate a "non-standard" kernel.
  987. Only use this if you really know what you are doing.
  988. config UID16
  989. bool "Enable 16-bit UID system calls" if EXPERT
  990. depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
  991. default y
  992. help
  993. This enables the legacy 16-bit UID syscall wrappers.
  994. config SYSCTL_SYSCALL
  995. bool "Sysctl syscall support" if EXPERT
  996. depends on PROC_SYSCTL
  997. default n
  998. select SYSCTL
  999. ---help---
  1000. sys_sysctl uses binary paths that have been found challenging
  1001. to properly maintain and use. The interface in /proc/sys
  1002. using paths with ascii names is now the primary path to this
  1003. information.
  1004. Almost nothing using the binary sysctl interface so if you are
  1005. trying to save some space it is probably safe to disable this,
  1006. making your kernel marginally smaller.
  1007. If unsure say N here.
  1008. config KALLSYMS
  1009. bool "Load all symbols for debugging/ksymoops" if EXPERT
  1010. default y
  1011. help
  1012. Say Y here to let the kernel print out symbolic crash information and
  1013. symbolic stack backtraces. This increases the size of the kernel
  1014. somewhat, as all symbols have to be loaded into the kernel image.
  1015. config KALLSYMS_ALL
  1016. bool "Include all symbols in kallsyms"
  1017. depends on DEBUG_KERNEL && KALLSYMS
  1018. help
  1019. Normally kallsyms only contains the symbols of functions for nicer
  1020. OOPS messages and backtraces (i.e., symbols from the text and inittext
  1021. sections). This is sufficient for most cases. And only in very rare
  1022. cases (e.g., when a debugger is used) all symbols are required (e.g.,
  1023. names of variables from the data sections, etc).
  1024. This option makes sure that all symbols are loaded into the kernel
  1025. image (i.e., symbols from all sections) in cost of increased kernel
  1026. size (depending on the kernel configuration, it may be 300KiB or
  1027. something like this).
  1028. Say N unless you really need all symbols.
  1029. config HOTPLUG
  1030. bool "Support for hot-pluggable devices" if EXPERT
  1031. default y
  1032. help
  1033. This option is provided for the case where no hotplug or uevent
  1034. capabilities is wanted by the kernel. You should only consider
  1035. disabling this option for embedded systems that do not use modules, a
  1036. dynamic /dev tree, or dynamic device discovery. Just say Y.
  1037. config PRINTK
  1038. default y
  1039. bool "Enable support for printk" if EXPERT
  1040. help
  1041. This option enables normal printk support. Removing it
  1042. eliminates most of the message strings from the kernel image
  1043. and makes the kernel more or less silent. As this makes it
  1044. very difficult to diagnose system problems, saying N here is
  1045. strongly discouraged.
  1046. config BUG
  1047. bool "BUG() support" if EXPERT
  1048. default y
  1049. help
  1050. Disabling this option eliminates support for BUG and WARN, reducing
  1051. the size of your kernel image and potentially quietly ignoring
  1052. numerous fatal conditions. You should only consider disabling this
  1053. option for embedded systems with no facilities for reporting errors.
  1054. Just say Y.
  1055. config ELF_CORE
  1056. default y
  1057. bool "Enable ELF core dumps" if EXPERT
  1058. help
  1059. Enable support for generating core dumps. Disabling saves about 4k.
  1060. config PCSPKR_PLATFORM
  1061. bool "Enable PC-Speaker support" if EXPERT
  1062. depends on HAVE_PCSPKR_PLATFORM
  1063. select I8253_LOCK
  1064. default y
  1065. help
  1066. This option allows to disable the internal PC-Speaker
  1067. support, saving some memory.
  1068. config HAVE_PCSPKR_PLATFORM
  1069. bool
  1070. config BASE_FULL
  1071. default y
  1072. bool "Enable full-sized data structures for core" if EXPERT
  1073. help
  1074. Disabling this option reduces the size of miscellaneous core
  1075. kernel data structures. This saves memory on small machines,
  1076. but may reduce performance.
  1077. config FUTEX
  1078. bool "Enable futex support" if EXPERT
  1079. default y
  1080. select RT_MUTEXES
  1081. help
  1082. Disabling this option will cause the kernel to be built without
  1083. support for "fast userspace mutexes". The resulting kernel may not
  1084. run glibc-based applications correctly.
  1085. config EPOLL
  1086. bool "Enable eventpoll support" if EXPERT
  1087. default y
  1088. select ANON_INODES
  1089. help
  1090. Disabling this option will cause the kernel to be built without
  1091. support for epoll family of system calls.
  1092. config SIGNALFD
  1093. bool "Enable signalfd() system call" if EXPERT
  1094. select ANON_INODES
  1095. default y
  1096. help
  1097. Enable the signalfd() system call that allows to receive signals
  1098. on a file descriptor.
  1099. If unsure, say Y.
  1100. config TIMERFD
  1101. bool "Enable timerfd() system call" if EXPERT
  1102. select ANON_INODES
  1103. default y
  1104. help
  1105. Enable the timerfd() system call that allows to receive timer
  1106. events on a file descriptor.
  1107. If unsure, say Y.
  1108. config EVENTFD
  1109. bool "Enable eventfd() system call" if EXPERT
  1110. select ANON_INODES
  1111. default y
  1112. help
  1113. Enable the eventfd() system call that allows to receive both
  1114. kernel notification (ie. KAIO) or userspace notifications.
  1115. If unsure, say Y.
  1116. config SHMEM
  1117. bool "Use full shmem filesystem" if EXPERT
  1118. default y
  1119. depends on MMU
  1120. help
  1121. The shmem is an internal filesystem used to manage shared memory.
  1122. It is backed by swap and manages resource limits. It is also exported
  1123. to userspace as tmpfs if TMPFS is enabled. Disabling this
  1124. option replaces shmem and tmpfs with the much simpler ramfs code,
  1125. which may be appropriate on small systems without swap.
  1126. config AIO
  1127. bool "Enable AIO support" if EXPERT
  1128. default y
  1129. help
  1130. This option enables POSIX asynchronous I/O which may by used
  1131. by some high performance threaded applications. Disabling
  1132. this option saves about 7k.
  1133. config EMBEDDED
  1134. bool "Embedded system"
  1135. select EXPERT
  1136. help
  1137. This option should be enabled if compiling the kernel for
  1138. an embedded system so certain expert options are available
  1139. for configuration.
  1140. config HAVE_PERF_EVENTS
  1141. bool
  1142. help
  1143. See tools/perf/design.txt for details.
  1144. config PERF_USE_VMALLOC
  1145. bool
  1146. help
  1147. See tools/perf/design.txt for details
  1148. menu "Kernel Performance Events And Counters"
  1149. config PERF_EVENTS
  1150. bool "Kernel performance events and counters"
  1151. default y if (PROFILING || PERF_COUNTERS)
  1152. depends on HAVE_PERF_EVENTS
  1153. select ANON_INODES
  1154. select IRQ_WORK
  1155. help
  1156. Enable kernel support for various performance events provided
  1157. by software and hardware.
  1158. Software events are supported either built-in or via the
  1159. use of generic tracepoints.
  1160. Most modern CPUs support performance events via performance
  1161. counter registers. These registers count the number of certain
  1162. types of hw events: such as instructions executed, cachemisses
  1163. suffered, or branches mis-predicted - without slowing down the
  1164. kernel or applications. These registers can also trigger interrupts
  1165. when a threshold number of events have passed - and can thus be
  1166. used to profile the code that runs on that CPU.
  1167. The Linux Performance Event subsystem provides an abstraction of
  1168. these software and hardware event capabilities, available via a
  1169. system call and used by the "perf" utility in tools/perf/. It
  1170. provides per task and per CPU counters, and it provides event
  1171. capabilities on top of those.
  1172. Say Y if unsure.
  1173. config PERF_COUNTERS
  1174. bool "Kernel performance counters (old config option)"
  1175. depends on HAVE_PERF_EVENTS
  1176. help
  1177. This config has been obsoleted by the PERF_EVENTS
  1178. config option - please see that one for details.
  1179. It has no effect on the kernel whether you enable
  1180. it or not, it is a compatibility placeholder.
  1181. Say N if unsure.
  1182. config DEBUG_PERF_USE_VMALLOC
  1183. default n
  1184. bool "Debug: use vmalloc to back perf mmap() buffers"
  1185. depends on PERF_EVENTS && DEBUG_KERNEL
  1186. select PERF_USE_VMALLOC
  1187. help
  1188. Use vmalloc memory to back perf mmap() buffers.
  1189. Mostly useful for debugging the vmalloc code on platforms
  1190. that don't require it.
  1191. Say N if unsure.
  1192. endmenu
  1193. config VM_EVENT_COUNTERS
  1194. default y
  1195. bool "Enable VM event counters for /proc/vmstat" if EXPERT
  1196. help
  1197. VM event counters are needed for event counts to be shown.
  1198. This option allows the disabling of the VM event counters
  1199. on EXPERT systems. /proc/vmstat will only show page counts
  1200. if VM event counters are disabled.
  1201. config PCI_QUIRKS
  1202. default y
  1203. bool "Enable PCI quirk workarounds" if EXPERT
  1204. depends on PCI
  1205. help
  1206. This enables workarounds for various PCI chipset
  1207. bugs/quirks. Disable this only if your target machine is
  1208. unaffected by PCI quirks.
  1209. config SLUB_DEBUG
  1210. default y
  1211. bool "Enable SLUB debugging support" if EXPERT
  1212. depends on SLUB && SYSFS
  1213. help
  1214. SLUB has extensive debug support features. Disabling these can
  1215. result in significant savings in code size. This also disables
  1216. SLUB sysfs support. /sys/slab will not exist and there will be
  1217. no support for cache validation etc.
  1218. config COMPAT_BRK
  1219. bool "Disable heap randomization"
  1220. default y
  1221. help
  1222. Randomizing heap placement makes heap exploits harder, but it
  1223. also breaks ancient binaries (including anything libc5 based).
  1224. This option changes the bootup default to heap randomization
  1225. disabled, and can be overridden at runtime by setting
  1226. /proc/sys/kernel/randomize_va_space to 2.
  1227. On non-ancient distros (post-2000 ones) N is usually a safe choice.
  1228. choice
  1229. prompt "Choose SLAB allocator"
  1230. default SLUB
  1231. help
  1232. This option allows to select a slab allocator.
  1233. config SLAB
  1234. bool "SLAB"
  1235. help
  1236. The regular slab allocator that is established and known to work
  1237. well in all environments. It organizes cache hot objects in
  1238. per cpu and per node queues.
  1239. config SLUB
  1240. depends on BROKEN || NUMA || !DISCONTIGMEM
  1241. bool "SLUB (Unqueued Allocator)"
  1242. help
  1243. SLUB is a slab allocator that minimizes cache line usage
  1244. instead of managing queues of cached objects (SLAB approach).
  1245. Per cpu caching is realized using slabs of objects instead
  1246. of queues of objects. SLUB can use memory efficiently
  1247. and has enhanced diagnostics. SLUB is the default choice for
  1248. a slab allocator.
  1249. config SLOB
  1250. depends on EXPERT
  1251. bool "SLOB (Simple Allocator)"
  1252. help
  1253. SLOB replaces the stock allocator with a drastically simpler
  1254. allocator. SLOB is generally more space efficient but
  1255. does not perform as well on large systems.
  1256. endchoice
  1257. config MMAP_ALLOW_UNINITIALIZED
  1258. bool "Allow mmapped anonymous memory to be uninitialized"
  1259. depends on EXPERT && !MMU
  1260. default n
  1261. help
  1262. Normally, and according to the Linux spec, anonymous memory obtained
  1263. from mmap() has it's contents cleared before it is passed to
  1264. userspace. Enabling this config option allows you to request that
  1265. mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
  1266. providing a huge performance boost. If this option is not enabled,
  1267. then the flag will be ignored.
  1268. This is taken advantage of by uClibc's malloc(), and also by
  1269. ELF-FDPIC binfmt's brk and stack allocator.
  1270. Because of the obvious security issues, this option should only be
  1271. enabled on embedded devices where you control what is run in
  1272. userspace. Since that isn't generally a problem on no-MMU systems,
  1273. it is normally safe to say Y here.
  1274. See Documentation/nommu-mmap.txt for more information.
  1275. config DEFERRED_INITCALLS
  1276. bool "Deferred initcalls support"
  1277. default n
  1278. help
  1279. Say 'y' here to include support for deferred initcalls
  1280. config PROFILING
  1281. bool "Profiling support"
  1282. help
  1283. Say Y here to enable the extended profiling support mechanisms used
  1284. by profilers such as OProfile.
  1285. #
  1286. # Place an empty function call at each tracepoint site. Can be
  1287. # dynamically changed for a probe function.
  1288. #
  1289. config TRACEPOINTS
  1290. bool
  1291. source "arch/Kconfig"
  1292. endmenu # General setup
  1293. config HAVE_GENERIC_DMA_COHERENT
  1294. bool
  1295. default n
  1296. config SLABINFO
  1297. bool
  1298. depends on PROC_FS
  1299. depends on SLAB || SLUB_DEBUG
  1300. default y
  1301. config RT_MUTEXES
  1302. boolean
  1303. config BASE_SMALL
  1304. int
  1305. default 0 if BASE_FULL
  1306. default 1 if !BASE_FULL
  1307. menuconfig MODULES
  1308. bool "Enable loadable module support"
  1309. help
  1310. Kernel modules are small pieces of compiled code which can
  1311. be inserted in the running kernel, rather than being
  1312. permanently built into the kernel. You use the "modprobe"
  1313. tool to add (and sometimes remove) them. If you say Y here,
  1314. many parts of the kernel can be built as modules (by
  1315. answering M instead of Y where indicated): this is most
  1316. useful for infrequently used options which are not required
  1317. for booting. For more information, see the man pages for
  1318. modprobe, lsmod, modinfo, insmod and rmmod.
  1319. If you say Y here, you will need to run "make
  1320. modules_install" to put the modules under /lib/modules/
  1321. where modprobe can find them (you may need to be root to do
  1322. this).
  1323. If unsure, say Y.
  1324. if MODULES
  1325. config MODULE_FORCE_LOAD
  1326. bool "Forced module loading"
  1327. default n
  1328. help
  1329. Allow loading of modules without version information (ie. modprobe
  1330. --force). Forced module loading sets the 'F' (forced) taint flag and
  1331. is usually a really bad idea.
  1332. config MODULE_UNLOAD
  1333. bool "Module unloading"
  1334. help
  1335. Without this option you will not be able to unload any
  1336. modules (note that some modules may not be unloadable
  1337. anyway), which makes your kernel smaller, faster
  1338. and simpler. If unsure, say Y.
  1339. config MODULE_FORCE_UNLOAD
  1340. bool "Forced module unloading"
  1341. depends on MODULE_UNLOAD && EXPERIMENTAL
  1342. help
  1343. This option allows you to force a module to unload, even if the
  1344. kernel believes it is unsafe: the kernel will remove the module
  1345. without waiting for anyone to stop using it (using the -f option to
  1346. rmmod). This is mainly for kernel developers and desperate users.
  1347. If unsure, say N.
  1348. config MODVERSIONS
  1349. bool "Module versioning support"
  1350. help
  1351. Usually, you have to use modules compiled with your kernel.
  1352. Saying Y here makes it sometimes possible to use modules
  1353. compiled for different kernels, by adding enough information
  1354. to the modules to (hopefully) spot any changes which would
  1355. make them incompatible with the kernel you are running. If
  1356. unsure, say N.
  1357. config MODULE_SRCVERSION_ALL
  1358. bool "Source checksum for all modules"
  1359. help
  1360. Modules which contain a MODULE_VERSION get an extra "srcversion"
  1361. field inserted into their modinfo section, which contains a
  1362. sum of the source files which made it. This helps maintainers
  1363. see exactly which source was used to build a module (since
  1364. others sometimes change the module source without updating
  1365. the version). With this option, such a "srcversion" field
  1366. will be created for all modules. If unsure, say N.
  1367. config TRIM_UNUSED_KSYMS
  1368. bool "Trim unused exported kernel symbols"
  1369. depends on MODULES && !UNUSED_SYMBOLS
  1370. help
  1371. The kernel and some modules make many symbols available for
  1372. other modules to use via EXPORT_SYMBOL() and variants. Depending
  1373. on the set of modules being selected in your kernel configuration,
  1374. many of those exported symbols might never be used.
  1375. This option allows for unused exported symbols to be dropped from
  1376. the build. In turn, this provides the compiler more opportunities
  1377. (especially when using LTO) for optimizing the code and reducing
  1378. binary size. This might have some security advantages as well.
  1379. If unsure say N.
  1380. endif # MODULES
  1381. config INIT_ALL_POSSIBLE
  1382. bool
  1383. help
  1384. Back when each arch used to define their own cpu_online_mask and
  1385. cpu_possible_mask, some of them chose to initialize cpu_possible_mask
  1386. with all 1s, and others with all 0s. When they were centralised,
  1387. it was better to provide this option than to break all the archs
  1388. and have several arch maintainers pursuing me down dark alleys.
  1389. config STOP_MACHINE
  1390. bool
  1391. default y
  1392. depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
  1393. help
  1394. Need stop_machine() primitive.
  1395. source "block/Kconfig"
  1396. config PREEMPT_NOTIFIERS
  1397. bool
  1398. config PADATA
  1399. depends on SMP
  1400. bool
  1401. source "kernel/Kconfig.locks"