Kconfig 36 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529530531532533534535536537538539540541542543544545546547548549550551552553554555556557558559560561562563564565566567568569570571572573574575576577578579580581582583584585586587588589590591592593594595596597598599600601602603604605606607608609610611612613614615616617618619620621622623624625626627628629630631632633634635636637638639640641642643644645646647648649650651652653654655656657658659660661662663664665666667668669670671672673674675676677678679680681682683684685686687688689690691692693694695696697698699700701702703704705706707708709710711712713714715716717718719720721722723724725726727728729730731732733734735736737738739740741742743744745746747748749750751752753754755756757758759760761762763764765766767768769770771772773774775776777778779780781782783784785786787788789790791792793794795796797798799800801802803804805806807808809810811812813814815816817818819820821822823824825826827828829830831832833834835836837838839840841842843844845846847848849850851852853854855856857858859860861862863864865866867868869870871872873874875876877878879880881882883884885886887888889890891892893894895896897898899900901902903904905906907908909910911912913914915916917918919920921922923924925926927928929930931932933934935936937938939940941942943944945946947948949950951952953954955956957958959960961962963964965966967968969970971972973974975976977978979980981982983984985986987988989990991992993994995996997998999100010011002100310041005100610071008100910101011101210131014101510161017101810191020102110221023102410251026102710281029103010311032103310341035103610371038103910401041104210431044104510461047104810491050105110521053105410551056105710581059106010611062106310641065106610671068106910701071107210731074107510761077107810791080108110821083108410851086108710881089109010911092109310941095109610971098109911001101110211031104110511061107110811091110111111121113111411151116111711181119112011211122112311241125112611271128112911301131113211331134113511361137113811391140
  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. menu "General setup"
  17. config EXPERIMENTAL
  18. bool "Prompt for development and/or incomplete code/drivers"
  19. ---help---
  20. Some of the various things that Linux supports (such as network
  21. drivers, file systems, network protocols, etc.) can be in a state
  22. of development where the functionality, stability, or the level of
  23. testing is not yet high enough for general use. This is usually
  24. known as the "alpha-test" phase among developers. If a feature is
  25. currently in alpha-test, then the developers usually discourage
  26. uninformed widespread use of this feature by the general public to
  27. avoid "Why doesn't this work?" type mail messages. However, active
  28. testing and use of these systems is welcomed. Just be aware that it
  29. may not meet the normal level of reliability or it may fail to work
  30. in some special cases. Detailed bug reports from people familiar
  31. with the kernel internals are usually welcomed by the developers
  32. (before submitting bug reports, please read the documents
  33. <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
  34. <file:Documentation/BUG-HUNTING>, and
  35. <file:Documentation/oops-tracing.txt> in the kernel source).
  36. This option will also make obsoleted drivers available. These are
  37. drivers that have been replaced by something else, and/or are
  38. scheduled to be removed in a future kernel release.
  39. Unless you intend to help test and develop a feature or driver that
  40. falls into this category, or you have a situation that requires
  41. using these features, you should probably say N here, which will
  42. cause the configurator to present you with fewer choices. If
  43. you say Y here, you will be offered the choice of using features or
  44. drivers that are currently considered to be in the alpha-test phase.
  45. config BROKEN
  46. bool
  47. config BROKEN_ON_SMP
  48. bool
  49. depends on BROKEN || !SMP
  50. default y
  51. config LOCK_KERNEL
  52. bool
  53. depends on SMP || PREEMPT
  54. default y
  55. config INIT_ENV_ARG_LIMIT
  56. int
  57. default 32 if !UML
  58. default 128 if UML
  59. help
  60. Maximum of each of the number of arguments and environment
  61. variables passed to init from the kernel command line.
  62. config LOCALVERSION
  63. string "Local version - append to kernel release"
  64. help
  65. Append an extra string to the end of your kernel version.
  66. This will show up when you type uname, for example.
  67. The string you set here will be appended after the contents of
  68. any files with a filename matching localversion* in your
  69. object and source tree, in that order. Your total string can
  70. be a maximum of 64 characters.
  71. config LOCALVERSION_AUTO
  72. bool "Automatically append version information to the version string"
  73. default y
  74. help
  75. This will try to automatically determine if the current tree is a
  76. release tree by looking for git tags that belong to the current
  77. top of tree revision.
  78. A string of the format -gxxxxxxxx will be added to the localversion
  79. if a git-based tree is found. The string generated by this will be
  80. appended after any matching localversion* files, and after the value
  81. set in CONFIG_LOCALVERSION.
  82. (The actual string used here is the first eight characters produced
  83. by running the command:
  84. $ git rev-parse --verify HEAD
  85. which is done within the script "scripts/setlocalversion".)
  86. config HAVE_KERNEL_GZIP
  87. bool
  88. config HAVE_KERNEL_BZIP2
  89. bool
  90. config HAVE_KERNEL_LZMA
  91. bool
  92. choice
  93. prompt "Kernel compression mode"
  94. default KERNEL_GZIP
  95. depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA
  96. help
  97. The linux kernel is a kind of self-extracting executable.
  98. Several compression algorithms are available, which differ
  99. in efficiency, compression and decompression speed.
  100. Compression speed is only relevant when building a kernel.
  101. Decompression speed is relevant at each boot.
  102. If you have any problems with bzip2 or lzma compressed
  103. kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
  104. version of this functionality (bzip2 only), for 2.4, was
  105. supplied by Christian Ludwig)
  106. High compression options are mostly useful for users, who
  107. are low on disk space (embedded systems), but for whom ram
  108. size matters less.
  109. If in doubt, select 'gzip'
  110. config KERNEL_GZIP
  111. bool "Gzip"
  112. depends on HAVE_KERNEL_GZIP
  113. help
  114. The old and tried gzip compression. Its compression ratio is
  115. the poorest among the 3 choices; however its speed (both
  116. compression and decompression) is the fastest.
  117. config KERNEL_BZIP2
  118. bool "Bzip2"
  119. depends on HAVE_KERNEL_BZIP2
  120. help
  121. Its compression ratio and speed is intermediate.
  122. Decompression speed is slowest among the three. The kernel
  123. size is about 10% smaller with bzip2, in comparison to gzip.
  124. Bzip2 uses a large amount of memory. For modern kernels you
  125. will need at least 8MB RAM or more for booting.
  126. config KERNEL_LZMA
  127. bool "LZMA"
  128. depends on HAVE_KERNEL_LZMA
  129. help
  130. The most recent compression algorithm.
  131. Its ratio is best, decompression speed is between the other
  132. two. Compression is slowest. The kernel size is about 33%
  133. smaller with LZMA in comparison to gzip.
  134. endchoice
  135. config SWAP
  136. bool "Support for paging of anonymous memory (swap)"
  137. depends on MMU && BLOCK
  138. default y
  139. help
  140. This option allows you to choose whether you want to have support
  141. for so called swap devices or swap files in your kernel that are
  142. used to provide more virtual memory than the actual RAM present
  143. in your computer. If unsure say Y.
  144. config SYSVIPC
  145. bool "System V IPC"
  146. ---help---
  147. Inter Process Communication is a suite of library functions and
  148. system calls which let processes (running programs) synchronize and
  149. exchange information. It is generally considered to be a good thing,
  150. and some programs won't run unless you say Y here. In particular, if
  151. you want to run the DOS emulator dosemu under Linux (read the
  152. DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
  153. you'll need to say Y here.
  154. You can find documentation about IPC with "info ipc" and also in
  155. section 6.4 of the Linux Programmer's Guide, available from
  156. <http://www.tldp.org/guides.html>.
  157. config SYSVIPC_SYSCTL
  158. bool
  159. depends on SYSVIPC
  160. depends on SYSCTL
  161. default y
  162. config POSIX_MQUEUE
  163. bool "POSIX Message Queues"
  164. depends on NET && EXPERIMENTAL
  165. ---help---
  166. POSIX variant of message queues is a part of IPC. In POSIX message
  167. queues every message has a priority which decides about succession
  168. of receiving it by a process. If you want to compile and run
  169. programs written e.g. for Solaris with use of its POSIX message
  170. queues (functions mq_*) say Y here.
  171. POSIX message queues are visible as a filesystem called 'mqueue'
  172. and can be mounted somewhere if you want to do filesystem
  173. operations on message queues.
  174. If unsure, say Y.
  175. config BSD_PROCESS_ACCT
  176. bool "BSD Process Accounting"
  177. help
  178. If you say Y here, a user level program will be able to instruct the
  179. kernel (via a special system call) to write process accounting
  180. information to a file: whenever a process exits, information about
  181. that process will be appended to the file by the kernel. The
  182. information includes things such as creation time, owning user,
  183. command name, memory usage, controlling terminal etc. (the complete
  184. list is in the struct acct in <file:include/linux/acct.h>). It is
  185. up to the user level program to do useful things with this
  186. information. This is generally a good idea, so say Y.
  187. config BSD_PROCESS_ACCT_V3
  188. bool "BSD Process Accounting version 3 file format"
  189. depends on BSD_PROCESS_ACCT
  190. default n
  191. help
  192. If you say Y here, the process accounting information is written
  193. in a new file format that also logs the process IDs of each
  194. process and it's parent. Note that this file format is incompatible
  195. with previous v0/v1/v2 file formats, so you will need updated tools
  196. for processing it. A preliminary version of these tools is available
  197. at <http://www.gnu.org/software/acct/>.
  198. config TASKSTATS
  199. bool "Export task/process statistics through netlink (EXPERIMENTAL)"
  200. depends on NET
  201. default n
  202. help
  203. Export selected statistics for tasks/processes through the
  204. generic netlink interface. Unlike BSD process accounting, the
  205. statistics are available during the lifetime of tasks/processes as
  206. responses to commands. Like BSD accounting, they are sent to user
  207. space on task exit.
  208. Say N if unsure.
  209. config TASK_DELAY_ACCT
  210. bool "Enable per-task delay accounting (EXPERIMENTAL)"
  211. depends on TASKSTATS
  212. help
  213. Collect information on time spent by a task waiting for system
  214. resources like cpu, synchronous block I/O completion and swapping
  215. in pages. Such statistics can help in setting a task's priorities
  216. relative to other tasks for cpu, io, rss limits etc.
  217. Say N if unsure.
  218. config TASK_XACCT
  219. bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
  220. depends on TASKSTATS
  221. help
  222. Collect extended task accounting data and send the data
  223. to userland for processing over the taskstats interface.
  224. Say N if unsure.
  225. config TASK_IO_ACCOUNTING
  226. bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
  227. depends on TASK_XACCT
  228. help
  229. Collect information on the number of bytes of storage I/O which this
  230. task has caused.
  231. Say N if unsure.
  232. config AUDIT
  233. bool "Auditing support"
  234. depends on NET
  235. help
  236. Enable auditing infrastructure that can be used with another
  237. kernel subsystem, such as SELinux (which requires this for
  238. logging of avc messages output). Does not do system-call
  239. auditing without CONFIG_AUDITSYSCALL.
  240. config AUDITSYSCALL
  241. bool "Enable system-call auditing support"
  242. depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64|| SUPERH)
  243. default y if SECURITY_SELINUX
  244. help
  245. Enable low-overhead system-call auditing infrastructure that
  246. can be used independently or with another kernel subsystem,
  247. such as SELinux. To use audit's filesystem watch feature, please
  248. ensure that INOTIFY is configured.
  249. config AUDIT_TREE
  250. def_bool y
  251. depends on AUDITSYSCALL && INOTIFY
  252. menu "RCU Subsystem"
  253. choice
  254. prompt "RCU Implementation"
  255. default CLASSIC_RCU
  256. config CLASSIC_RCU
  257. bool "Classic RCU"
  258. help
  259. This option selects the classic RCU implementation that is
  260. designed for best read-side performance on non-realtime
  261. systems.
  262. Select this option if you are unsure.
  263. config TREE_RCU
  264. bool "Tree-based hierarchical RCU"
  265. help
  266. This option selects the RCU implementation that is
  267. designed for very large SMP system with hundreds or
  268. thousands of CPUs.
  269. config PREEMPT_RCU
  270. bool "Preemptible RCU"
  271. depends on PREEMPT
  272. help
  273. This option reduces the latency of the kernel by making certain
  274. RCU sections preemptible. Normally RCU code is non-preemptible, if
  275. this option is selected then read-only RCU sections become
  276. preemptible. This helps latency, but may expose bugs due to
  277. now-naive assumptions about each RCU read-side critical section
  278. remaining on a given CPU through its execution.
  279. endchoice
  280. config RCU_TRACE
  281. bool "Enable tracing for RCU"
  282. depends on TREE_RCU || PREEMPT_RCU
  283. help
  284. This option provides tracing in RCU which presents stats
  285. in debugfs for debugging RCU implementation.
  286. Say Y here if you want to enable RCU tracing
  287. Say N if you are unsure.
  288. config RCU_FANOUT
  289. int "Tree-based hierarchical RCU fanout value"
  290. range 2 64 if 64BIT
  291. range 2 32 if !64BIT
  292. depends on TREE_RCU
  293. default 64 if 64BIT
  294. default 32 if !64BIT
  295. help
  296. This option controls the fanout of hierarchical implementations
  297. of RCU, allowing RCU to work efficiently on machines with
  298. large numbers of CPUs. This value must be at least the cube
  299. root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
  300. systems and up to 262,144 for 64-bit systems.
  301. Select a specific number if testing RCU itself.
  302. Take the default if unsure.
  303. config RCU_FANOUT_EXACT
  304. bool "Disable tree-based hierarchical RCU auto-balancing"
  305. depends on TREE_RCU
  306. default n
  307. help
  308. This option forces use of the exact RCU_FANOUT value specified,
  309. regardless of imbalances in the hierarchy. This is useful for
  310. testing RCU itself, and might one day be useful on systems with
  311. strong NUMA behavior.
  312. Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
  313. Say N if unsure.
  314. config TREE_RCU_TRACE
  315. def_bool RCU_TRACE && TREE_RCU
  316. select DEBUG_FS
  317. help
  318. This option provides tracing for the TREE_RCU implementation,
  319. permitting Makefile to trivially select kernel/rcutree_trace.c.
  320. config PREEMPT_RCU_TRACE
  321. def_bool RCU_TRACE && PREEMPT_RCU
  322. select DEBUG_FS
  323. help
  324. This option provides tracing for the PREEMPT_RCU implementation,
  325. permitting Makefile to trivially select kernel/rcupreempt_trace.c.
  326. endmenu # "RCU Subsystem"
  327. config IKCONFIG
  328. tristate "Kernel .config support"
  329. ---help---
  330. This option enables the complete Linux kernel ".config" file
  331. contents to be saved in the kernel. It provides documentation
  332. of which kernel options are used in a running kernel or in an
  333. on-disk kernel. This information can be extracted from the kernel
  334. image file with the script scripts/extract-ikconfig and used as
  335. input to rebuild the current kernel or to build another kernel.
  336. It can also be extracted from a running kernel by reading
  337. /proc/config.gz if enabled (below).
  338. config IKCONFIG_PROC
  339. bool "Enable access to .config through /proc/config.gz"
  340. depends on IKCONFIG && PROC_FS
  341. ---help---
  342. This option enables access to the kernel configuration file
  343. through /proc/config.gz.
  344. config LOG_BUF_SHIFT
  345. int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
  346. range 12 21
  347. default 17
  348. help
  349. Select kernel log buffer size as a power of 2.
  350. Examples:
  351. 17 => 128 KB
  352. 16 => 64 KB
  353. 15 => 32 KB
  354. 14 => 16 KB
  355. 13 => 8 KB
  356. 12 => 4 KB
  357. #
  358. # Architectures with an unreliable sched_clock() should select this:
  359. #
  360. config HAVE_UNSTABLE_SCHED_CLOCK
  361. bool
  362. config GROUP_SCHED
  363. bool "Group CPU scheduler"
  364. depends on EXPERIMENTAL
  365. default n
  366. help
  367. This feature lets CPU scheduler recognize task groups and control CPU
  368. bandwidth allocation to such task groups.
  369. In order to create a group from arbitrary set of processes, use
  370. CONFIG_CGROUPS. (See Control Group support.)
  371. config FAIR_GROUP_SCHED
  372. bool "Group scheduling for SCHED_OTHER"
  373. depends on GROUP_SCHED
  374. default GROUP_SCHED
  375. config RT_GROUP_SCHED
  376. bool "Group scheduling for SCHED_RR/FIFO"
  377. depends on EXPERIMENTAL
  378. depends on GROUP_SCHED
  379. default n
  380. help
  381. This feature lets you explicitly allocate real CPU bandwidth
  382. to users or control groups (depending on the "Basis for grouping tasks"
  383. setting below. If enabled, it will also make it impossible to
  384. schedule realtime tasks for non-root users until you allocate
  385. realtime bandwidth for them.
  386. See Documentation/scheduler/sched-rt-group.txt for more information.
  387. choice
  388. depends on GROUP_SCHED
  389. prompt "Basis for grouping tasks"
  390. default USER_SCHED
  391. config USER_SCHED
  392. bool "user id"
  393. help
  394. This option will choose userid as the basis for grouping
  395. tasks, thus providing equal CPU bandwidth to each user.
  396. config CGROUP_SCHED
  397. bool "Control groups"
  398. depends on CGROUPS
  399. help
  400. This option allows you to create arbitrary task groups
  401. using the "cgroup" pseudo filesystem and control
  402. the cpu bandwidth allocated to each such task group.
  403. Refer to Documentation/cgroups/cgroups.txt for more
  404. information on "cgroup" pseudo filesystem.
  405. endchoice
  406. menuconfig CGROUPS
  407. boolean "Control Group support"
  408. help
  409. This option adds support for grouping sets of processes together, for
  410. use with process control subsystems such as Cpusets, CFS, memory
  411. controls or device isolation.
  412. See
  413. - Documentation/scheduler/sched-design-CFS.txt (CFS)
  414. - Documentation/cgroups/ (features for grouping, isolation
  415. and resource control)
  416. Say N if unsure.
  417. if CGROUPS
  418. config CGROUP_DEBUG
  419. bool "Example debug cgroup subsystem"
  420. depends on CGROUPS
  421. default n
  422. help
  423. This option enables a simple cgroup subsystem that
  424. exports useful debugging information about the cgroups
  425. framework.
  426. Say N if unsure.
  427. config CGROUP_NS
  428. bool "Namespace cgroup subsystem"
  429. depends on CGROUPS
  430. help
  431. Provides a simple namespace cgroup subsystem to
  432. provide hierarchical naming of sets of namespaces,
  433. for instance virtual servers and checkpoint/restart
  434. jobs.
  435. config CGROUP_FREEZER
  436. bool "Freezer cgroup subsystem"
  437. depends on CGROUPS
  438. help
  439. Provides a way to freeze and unfreeze all tasks in a
  440. cgroup.
  441. config CGROUP_DEVICE
  442. bool "Device controller for cgroups"
  443. depends on CGROUPS && EXPERIMENTAL
  444. help
  445. Provides a cgroup implementing whitelists for devices which
  446. a process in the cgroup can mknod or open.
  447. config CPUSETS
  448. bool "Cpuset support"
  449. depends on CGROUPS
  450. help
  451. This option will let you create and manage CPUSETs which
  452. allow dynamically partitioning a system into sets of CPUs and
  453. Memory Nodes and assigning tasks to run only within those sets.
  454. This is primarily useful on large SMP or NUMA systems.
  455. Say N if unsure.
  456. config PROC_PID_CPUSET
  457. bool "Include legacy /proc/<pid>/cpuset file"
  458. depends on CPUSETS
  459. default y
  460. config CGROUP_CPUACCT
  461. bool "Simple CPU accounting cgroup subsystem"
  462. depends on CGROUPS
  463. help
  464. Provides a simple Resource Controller for monitoring the
  465. total CPU consumed by the tasks in a cgroup.
  466. config RESOURCE_COUNTERS
  467. bool "Resource counters"
  468. help
  469. This option enables controller independent resource accounting
  470. infrastructure that works with cgroups.
  471. depends on CGROUPS
  472. config CGROUP_MEM_RES_CTLR
  473. bool "Memory Resource Controller for Control Groups"
  474. depends on CGROUPS && RESOURCE_COUNTERS
  475. select MM_OWNER
  476. help
  477. Provides a memory resource controller that manages both anonymous
  478. memory and page cache. (See Documentation/controllers/memory.txt)
  479. Note that setting this option increases fixed memory overhead
  480. associated with each page of memory in the system. By this,
  481. 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
  482. usage tracking struct at boot. Total amount of this is printed out
  483. at boot.
  484. Only enable when you're ok with these trade offs and really
  485. sure you need the memory resource controller. Even when you enable
  486. this, you can set "cgroup_disable=memory" at your boot option to
  487. disable memory resource controller and you can avoid overheads.
  488. (and lose benefits of memory resource controller)
  489. This config option also selects MM_OWNER config option, which
  490. could in turn add some fork/exit overhead.
  491. config CGROUP_MEM_RES_CTLR_SWAP
  492. bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)"
  493. depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL
  494. help
  495. Add swap management feature to memory resource controller. When you
  496. enable this, you can limit mem+swap usage per cgroup. In other words,
  497. when you disable this, memory resource controller has no cares to
  498. usage of swap...a process can exhaust all of the swap. This extension
  499. is useful when you want to avoid exhaustion swap but this itself
  500. adds more overheads and consumes memory for remembering information.
  501. Especially if you use 32bit system or small memory system, please
  502. be careful about enabling this. When memory resource controller
  503. is disabled by boot option, this will be automatically disabled and
  504. there will be no overhead from this. Even when you set this config=y,
  505. if boot option "noswapaccount" is set, swap will not be accounted.
  506. Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
  507. size is 4096bytes, 512k per 1Gbytes of swap.
  508. endif # CGROUPS
  509. config MM_OWNER
  510. bool
  511. config SYSFS_DEPRECATED
  512. bool
  513. config SYSFS_DEPRECATED_V2
  514. bool "Create deprecated sysfs layout for older userspace tools"
  515. depends on SYSFS
  516. default y
  517. select SYSFS_DEPRECATED
  518. help
  519. This option switches the layout of sysfs to the deprecated
  520. version.
  521. The current sysfs layout features a unified device tree at
  522. /sys/devices/, which is able to express a hierarchy between
  523. class devices. If the deprecated option is set to Y, the
  524. unified device tree is split into a bus device tree at
  525. /sys/devices/ and several individual class device trees at
  526. /sys/class/. The class and bus devices will be connected by
  527. "<subsystem>:<name>" and the "device" links. The "block"
  528. class devices, will not show up in /sys/class/block/. Some
  529. subsystems will suppress the creation of some devices which
  530. depend on the unified device tree.
  531. This option is not a pure compatibility option that can
  532. be safely enabled on newer distributions. It will change the
  533. layout of sysfs to the non-extensible deprecated version,
  534. and disable some features, which can not be exported without
  535. confusing older userspace tools. Since 2007/2008 all major
  536. distributions do not enable this option, and ship no tools which
  537. depend on the deprecated layout or this option.
  538. If you are using a new kernel on an older distribution, or use
  539. older userspace tools, you might need to say Y here. Do not say Y,
  540. if the original kernel, that came with your distribution, has
  541. this option set to N.
  542. config RELAY
  543. bool "Kernel->user space relay support (formerly relayfs)"
  544. help
  545. This option enables support for relay interface support in
  546. certain file systems (such as debugfs).
  547. It is designed to provide an efficient mechanism for tools and
  548. facilities to relay large amounts of data from kernel space to
  549. user space.
  550. If unsure, say N.
  551. config NAMESPACES
  552. bool "Namespaces support" if EMBEDDED
  553. default !EMBEDDED
  554. help
  555. Provides the way to make tasks work with different objects using
  556. the same id. For example same IPC id may refer to different objects
  557. or same user id or pid may refer to different tasks when used in
  558. different namespaces.
  559. config UTS_NS
  560. bool "UTS namespace"
  561. depends on NAMESPACES
  562. help
  563. In this namespace tasks see different info provided with the
  564. uname() system call
  565. config IPC_NS
  566. bool "IPC namespace"
  567. depends on NAMESPACES && SYSVIPC
  568. help
  569. In this namespace tasks work with IPC ids which correspond to
  570. different IPC objects in different namespaces
  571. config USER_NS
  572. bool "User namespace (EXPERIMENTAL)"
  573. depends on NAMESPACES && EXPERIMENTAL
  574. help
  575. This allows containers, i.e. vservers, to use user namespaces
  576. to provide different user info for different servers.
  577. If unsure, say N.
  578. config PID_NS
  579. bool "PID Namespaces (EXPERIMENTAL)"
  580. default n
  581. depends on NAMESPACES && EXPERIMENTAL
  582. help
  583. Support process id namespaces. This allows having multiple
  584. process with the same pid as long as they are in different
  585. pid namespaces. This is a building block of containers.
  586. Unless you want to work with an experimental feature
  587. say N here.
  588. config NET_NS
  589. bool "Network namespace"
  590. default n
  591. depends on NAMESPACES && EXPERIMENTAL && NET
  592. help
  593. Allow user space to create what appear to be multiple instances
  594. of the network stack.
  595. config BLK_DEV_INITRD
  596. bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
  597. depends on BROKEN || !FRV
  598. help
  599. The initial RAM filesystem is a ramfs which is loaded by the
  600. boot loader (loadlin or lilo) and that is mounted as root
  601. before the normal boot procedure. It is typically used to
  602. load modules needed to mount the "real" root file system,
  603. etc. See <file:Documentation/initrd.txt> for details.
  604. If RAM disk support (BLK_DEV_RAM) is also included, this
  605. also enables initial RAM disk (initrd) support and adds
  606. 15 Kbytes (more on some other architectures) to the kernel size.
  607. If unsure say Y.
  608. if BLK_DEV_INITRD
  609. source "usr/Kconfig"
  610. endif
  611. config CC_OPTIMIZE_FOR_SIZE
  612. bool "Optimize for size"
  613. default y
  614. help
  615. Enabling this option will pass "-Os" instead of "-O2" to gcc
  616. resulting in a smaller kernel.
  617. If unsure, say Y.
  618. config SYSCTL
  619. bool
  620. config ANON_INODES
  621. bool
  622. menuconfig EMBEDDED
  623. bool "Configure standard kernel features (for small systems)"
  624. help
  625. This option allows certain base kernel options and settings
  626. to be disabled or tweaked. This is for specialized
  627. environments which can tolerate a "non-standard" kernel.
  628. Only use this if you really know what you are doing.
  629. config UID16
  630. bool "Enable 16-bit UID system calls" if EMBEDDED
  631. depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
  632. default y
  633. help
  634. This enables the legacy 16-bit UID syscall wrappers.
  635. config SYSCTL_SYSCALL
  636. bool "Sysctl syscall support" if EMBEDDED
  637. default y
  638. select SYSCTL
  639. ---help---
  640. sys_sysctl uses binary paths that have been found challenging
  641. to properly maintain and use. The interface in /proc/sys
  642. using paths with ascii names is now the primary path to this
  643. information.
  644. Almost nothing using the binary sysctl interface so if you are
  645. trying to save some space it is probably safe to disable this,
  646. making your kernel marginally smaller.
  647. If unsure say Y here.
  648. config KALLSYMS
  649. bool "Load all symbols for debugging/ksymoops" if EMBEDDED
  650. default y
  651. help
  652. Say Y here to let the kernel print out symbolic crash information and
  653. symbolic stack backtraces. This increases the size of the kernel
  654. somewhat, as all symbols have to be loaded into the kernel image.
  655. config KALLSYMS_ALL
  656. bool "Include all symbols in kallsyms"
  657. depends on DEBUG_KERNEL && KALLSYMS
  658. help
  659. Normally kallsyms only contains the symbols of functions, for nicer
  660. OOPS messages. Some debuggers can use kallsyms for other
  661. symbols too: say Y here to include all symbols, if you need them
  662. and you don't care about adding 300k to the size of your kernel.
  663. Say N.
  664. config KALLSYMS_EXTRA_PASS
  665. bool "Do an extra kallsyms pass"
  666. depends on KALLSYMS
  667. help
  668. If kallsyms is not working correctly, the build will fail with
  669. inconsistent kallsyms data. If that occurs, log a bug report and
  670. turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
  671. Always say N here unless you find a bug in kallsyms, which must be
  672. reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
  673. you wait for kallsyms to be fixed.
  674. config HOTPLUG
  675. bool "Support for hot-pluggable devices" if EMBEDDED
  676. default y
  677. help
  678. This option is provided for the case where no hotplug or uevent
  679. capabilities is wanted by the kernel. You should only consider
  680. disabling this option for embedded systems that do not use modules, a
  681. dynamic /dev tree, or dynamic device discovery. Just say Y.
  682. config PRINTK
  683. default y
  684. bool "Enable support for printk" if EMBEDDED
  685. help
  686. This option enables normal printk support. Removing it
  687. eliminates most of the message strings from the kernel image
  688. and makes the kernel more or less silent. As this makes it
  689. very difficult to diagnose system problems, saying N here is
  690. strongly discouraged.
  691. config BUG
  692. bool "BUG() support" if EMBEDDED
  693. default y
  694. help
  695. Disabling this option eliminates support for BUG and WARN, reducing
  696. the size of your kernel image and potentially quietly ignoring
  697. numerous fatal conditions. You should only consider disabling this
  698. option for embedded systems with no facilities for reporting errors.
  699. Just say Y.
  700. config ELF_CORE
  701. default y
  702. bool "Enable ELF core dumps" if EMBEDDED
  703. help
  704. Enable support for generating core dumps. Disabling saves about 4k.
  705. config PCSPKR_PLATFORM
  706. bool "Enable PC-Speaker support" if EMBEDDED
  707. depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
  708. default y
  709. help
  710. This option allows to disable the internal PC-Speaker
  711. support, saving some memory.
  712. config BASE_FULL
  713. default y
  714. bool "Enable full-sized data structures for core" if EMBEDDED
  715. help
  716. Disabling this option reduces the size of miscellaneous core
  717. kernel data structures. This saves memory on small machines,
  718. but may reduce performance.
  719. config FUTEX
  720. bool "Enable futex support" if EMBEDDED
  721. default y
  722. select RT_MUTEXES
  723. help
  724. Disabling this option will cause the kernel to be built without
  725. support for "fast userspace mutexes". The resulting kernel may not
  726. run glibc-based applications correctly.
  727. config EPOLL
  728. bool "Enable eventpoll support" if EMBEDDED
  729. default y
  730. select ANON_INODES
  731. help
  732. Disabling this option will cause the kernel to be built without
  733. support for epoll family of system calls.
  734. config SIGNALFD
  735. bool "Enable signalfd() system call" if EMBEDDED
  736. select ANON_INODES
  737. default y
  738. help
  739. Enable the signalfd() system call that allows to receive signals
  740. on a file descriptor.
  741. If unsure, say Y.
  742. config TIMERFD
  743. bool "Enable timerfd() system call" if EMBEDDED
  744. select ANON_INODES
  745. default y
  746. help
  747. Enable the timerfd() system call that allows to receive timer
  748. events on a file descriptor.
  749. If unsure, say Y.
  750. config EVENTFD
  751. bool "Enable eventfd() system call" if EMBEDDED
  752. select ANON_INODES
  753. default y
  754. help
  755. Enable the eventfd() system call that allows to receive both
  756. kernel notification (ie. KAIO) or userspace notifications.
  757. If unsure, say Y.
  758. config SHMEM
  759. bool "Use full shmem filesystem" if EMBEDDED
  760. default y
  761. depends on MMU
  762. help
  763. The shmem is an internal filesystem used to manage shared memory.
  764. It is backed by swap and manages resource limits. It is also exported
  765. to userspace as tmpfs if TMPFS is enabled. Disabling this
  766. option replaces shmem and tmpfs with the much simpler ramfs code,
  767. which may be appropriate on small systems without swap.
  768. config AIO
  769. bool "Enable AIO support" if EMBEDDED
  770. default y
  771. help
  772. This option enables POSIX asynchronous I/O which may by used
  773. by some high performance threaded applications. Disabling
  774. this option saves about 7k.
  775. config VM_EVENT_COUNTERS
  776. default y
  777. bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
  778. help
  779. VM event counters are needed for event counts to be shown.
  780. This option allows the disabling of the VM event counters
  781. on EMBEDDED systems. /proc/vmstat will only show page counts
  782. if VM event counters are disabled.
  783. config PCI_QUIRKS
  784. default y
  785. bool "Enable PCI quirk workarounds" if EMBEDDED
  786. depends on PCI
  787. help
  788. This enables workarounds for various PCI chipset
  789. bugs/quirks. Disable this only if your target machine is
  790. unaffected by PCI quirks.
  791. config SLUB_DEBUG
  792. default y
  793. bool "Enable SLUB debugging support" if EMBEDDED
  794. depends on SLUB && SYSFS
  795. help
  796. SLUB has extensive debug support features. Disabling these can
  797. result in significant savings in code size. This also disables
  798. SLUB sysfs support. /sys/slab will not exist and there will be
  799. no support for cache validation etc.
  800. config COMPAT_BRK
  801. bool "Disable heap randomization"
  802. default y
  803. help
  804. Randomizing heap placement makes heap exploits harder, but it
  805. also breaks ancient binaries (including anything libc5 based).
  806. This option changes the bootup default to heap randomization
  807. disabled, and can be overriden runtime by setting
  808. /proc/sys/kernel/randomize_va_space to 2.
  809. On non-ancient distros (post-2000 ones) N is usually a safe choice.
  810. choice
  811. prompt "Choose SLAB allocator"
  812. default SLUB
  813. help
  814. This option allows to select a slab allocator.
  815. config SLAB
  816. bool "SLAB"
  817. help
  818. The regular slab allocator that is established and known to work
  819. well in all environments. It organizes cache hot objects in
  820. per cpu and per node queues.
  821. config SLUB
  822. bool "SLUB (Unqueued Allocator)"
  823. help
  824. SLUB is a slab allocator that minimizes cache line usage
  825. instead of managing queues of cached objects (SLAB approach).
  826. Per cpu caching is realized using slabs of objects instead
  827. of queues of objects. SLUB can use memory efficiently
  828. and has enhanced diagnostics. SLUB is the default choice for
  829. a slab allocator.
  830. config SLOB
  831. depends on EMBEDDED
  832. bool "SLOB (Simple Allocator)"
  833. help
  834. SLOB replaces the stock allocator with a drastically simpler
  835. allocator. SLOB is generally more space efficient but
  836. does not perform as well on large systems.
  837. endchoice
  838. config PROFILING
  839. bool "Profiling support (EXPERIMENTAL)"
  840. help
  841. Say Y here to enable the extended profiling support mechanisms used
  842. by profilers such as OProfile.
  843. #
  844. # Place an empty function call at each tracepoint site. Can be
  845. # dynamically changed for a probe function.
  846. #
  847. config TRACEPOINTS
  848. bool
  849. config MARKERS
  850. bool "Activate markers"
  851. depends on TRACEPOINTS
  852. help
  853. Place an empty function call at each marker site. Can be
  854. dynamically changed for a probe function.
  855. source "arch/Kconfig"
  856. config SLOW_WORK
  857. default n
  858. bool "Enable slow work thread pool"
  859. help
  860. The slow work thread pool provides a number of dynamically allocated
  861. threads that can be used by the kernel to perform operations that
  862. take a relatively long time.
  863. An example of this would be CacheFiles doing a path lookup followed
  864. by a series of mkdirs and a create call, all of which have to touch
  865. disk.
  866. endmenu # General setup
  867. config HAVE_GENERIC_DMA_COHERENT
  868. bool
  869. default n
  870. config SLABINFO
  871. bool
  872. depends on PROC_FS
  873. depends on SLAB || SLUB_DEBUG
  874. default y
  875. config RT_MUTEXES
  876. boolean
  877. config BASE_SMALL
  878. int
  879. default 0 if BASE_FULL
  880. default 1 if !BASE_FULL
  881. menuconfig MODULES
  882. bool "Enable loadable module support"
  883. help
  884. Kernel modules are small pieces of compiled code which can
  885. be inserted in the running kernel, rather than being
  886. permanently built into the kernel. You use the "modprobe"
  887. tool to add (and sometimes remove) them. If you say Y here,
  888. many parts of the kernel can be built as modules (by
  889. answering M instead of Y where indicated): this is most
  890. useful for infrequently used options which are not required
  891. for booting. For more information, see the man pages for
  892. modprobe, lsmod, modinfo, insmod and rmmod.
  893. If you say Y here, you will need to run "make
  894. modules_install" to put the modules under /lib/modules/
  895. where modprobe can find them (you may need to be root to do
  896. this).
  897. If unsure, say Y.
  898. if MODULES
  899. config MODULE_FORCE_LOAD
  900. bool "Forced module loading"
  901. default n
  902. help
  903. Allow loading of modules without version information (ie. modprobe
  904. --force). Forced module loading sets the 'F' (forced) taint flag and
  905. is usually a really bad idea.
  906. config MODULE_UNLOAD
  907. bool "Module unloading"
  908. help
  909. Without this option you will not be able to unload any
  910. modules (note that some modules may not be unloadable
  911. anyway), which makes your kernel smaller, faster
  912. and simpler. If unsure, say Y.
  913. config MODULE_FORCE_UNLOAD
  914. bool "Forced module unloading"
  915. depends on MODULE_UNLOAD && EXPERIMENTAL
  916. help
  917. This option allows you to force a module to unload, even if the
  918. kernel believes it is unsafe: the kernel will remove the module
  919. without waiting for anyone to stop using it (using the -f option to
  920. rmmod). This is mainly for kernel developers and desperate users.
  921. If unsure, say N.
  922. config MODVERSIONS
  923. bool "Module versioning support"
  924. help
  925. Usually, you have to use modules compiled with your kernel.
  926. Saying Y here makes it sometimes possible to use modules
  927. compiled for different kernels, by adding enough information
  928. to the modules to (hopefully) spot any changes which would
  929. make them incompatible with the kernel you are running. If
  930. unsure, say N.
  931. config MODULE_SRCVERSION_ALL
  932. bool "Source checksum for all modules"
  933. help
  934. Modules which contain a MODULE_VERSION get an extra "srcversion"
  935. field inserted into their modinfo section, which contains a
  936. sum of the source files which made it. This helps maintainers
  937. see exactly which source was used to build a module (since
  938. others sometimes change the module source without updating
  939. the version). With this option, such a "srcversion" field
  940. will be created for all modules. If unsure, say N.
  941. endif # MODULES
  942. config INIT_ALL_POSSIBLE
  943. bool
  944. help
  945. Back when each arch used to define their own cpu_online_map and
  946. cpu_possible_map, some of them chose to initialize cpu_possible_map
  947. with all 1s, and others with all 0s. When they were centralised,
  948. it was better to provide this option than to break all the archs
  949. and have several arch maintainers persuing me down dark alleys.
  950. config STOP_MACHINE
  951. bool
  952. default y
  953. depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
  954. help
  955. Need stop_machine() primitive.
  956. source "block/Kconfig"
  957. config PREEMPT_NOTIFIERS
  958. bool