Kconfig 28 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529530531532533534535536537538539540541542543544545546547548549550551552553554555556557558559560561562563564565566567568569570571572573574575576577578579580581582583584585586587588589590591592593594595596597598599600601602603604605606607608609610611612613614615616617618619620621622623624625626627628629630631632633634635636637638639640641642643644645646647648649650651652653654655656657658659660661662663664665666667668669670671672673674675676677678679680681682683684685686687688689690691692693694695696697698699700701702703704705706707708709710711712713714715716717718719720721722723724725726727728729730731732733734735736737738739740741742743744745746747748749750751752753754755756757758759760761762763764765766767768769770771772773774775776777778779780781782783784785786787788789790791792793794795796797798799800801802803804805806807808809810811812813814815816817818819820821822823824825826827828829830831832833834835836837838839840841842843844845846847848849850851852853854855856857858859860861862863864865866867868869870871872873874875876877878
  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/$ARCH/defconfig"
  15. menu "General setup"
  16. config EXPERIMENTAL
  17. bool "Prompt for development and/or incomplete code/drivers"
  18. ---help---
  19. Some of the various things that Linux supports (such as network
  20. drivers, file systems, network protocols, etc.) can be in a state
  21. of development where the functionality, stability, or the level of
  22. testing is not yet high enough for general use. This is usually
  23. known as the "alpha-test" phase among developers. If a feature is
  24. currently in alpha-test, then the developers usually discourage
  25. uninformed widespread use of this feature by the general public to
  26. avoid "Why doesn't this work?" type mail messages. However, active
  27. testing and use of these systems is welcomed. Just be aware that it
  28. may not meet the normal level of reliability or it may fail to work
  29. in some special cases. Detailed bug reports from people familiar
  30. with the kernel internals are usually welcomed by the developers
  31. (before submitting bug reports, please read the documents
  32. <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
  33. <file:Documentation/BUG-HUNTING>, and
  34. <file:Documentation/oops-tracing.txt> in the kernel source).
  35. This option will also make obsoleted drivers available. These are
  36. drivers that have been replaced by something else, and/or are
  37. scheduled to be removed in a future kernel release.
  38. Unless you intend to help test and develop a feature or driver that
  39. falls into this category, or you have a situation that requires
  40. using these features, you should probably say N here, which will
  41. cause the configurator to present you with fewer choices. If
  42. you say Y here, you will be offered the choice of using features or
  43. drivers that are currently considered to be in the alpha-test phase.
  44. config BROKEN
  45. bool
  46. config BROKEN_ON_SMP
  47. bool
  48. depends on BROKEN || !SMP
  49. default y
  50. config LOCK_KERNEL
  51. bool
  52. depends on SMP || PREEMPT
  53. default y
  54. config INIT_ENV_ARG_LIMIT
  55. int
  56. default 32 if !UML
  57. default 128 if UML
  58. help
  59. Maximum of each of the number of arguments and environment
  60. variables passed to init from the kernel command line.
  61. config LOCALVERSION
  62. string "Local version - append to kernel release"
  63. help
  64. Append an extra string to the end of your kernel version.
  65. This will show up when you type uname, for example.
  66. The string you set here will be appended after the contents of
  67. any files with a filename matching localversion* in your
  68. object and source tree, in that order. Your total string can
  69. be a maximum of 64 characters.
  70. config LOCALVERSION_AUTO
  71. bool "Automatically append version information to the version string"
  72. default y
  73. help
  74. This will try to automatically determine if the current tree is a
  75. release tree by looking for git tags that belong to the current
  76. top of tree revision.
  77. A string of the format -gxxxxxxxx will be added to the localversion
  78. if a git-based tree is found. The string generated by this will be
  79. appended after any matching localversion* files, and after the value
  80. set in CONFIG_LOCALVERSION.
  81. (The actual string used here is the first eight characters produced
  82. by running the command:
  83. $ git rev-parse --verify HEAD
  84. which is done within the script "scripts/setlocalversion".)
  85. config SWAP
  86. bool "Support for paging of anonymous memory (swap)"
  87. depends on MMU && BLOCK
  88. default y
  89. help
  90. This option allows you to choose whether you want to have support
  91. for so called swap devices or swap files in your kernel that are
  92. used to provide more virtual memory than the actual RAM present
  93. in your computer. If unsure say Y.
  94. config SYSVIPC
  95. bool "System V IPC"
  96. ---help---
  97. Inter Process Communication is a suite of library functions and
  98. system calls which let processes (running programs) synchronize and
  99. exchange information. It is generally considered to be a good thing,
  100. and some programs won't run unless you say Y here. In particular, if
  101. you want to run the DOS emulator dosemu under Linux (read the
  102. DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
  103. you'll need to say Y here.
  104. You can find documentation about IPC with "info ipc" and also in
  105. section 6.4 of the Linux Programmer's Guide, available from
  106. <http://www.tldp.org/guides.html>.
  107. config SYSVIPC_SYSCTL
  108. bool
  109. depends on SYSVIPC
  110. depends on SYSCTL
  111. default y
  112. config POSIX_MQUEUE
  113. bool "POSIX Message Queues"
  114. depends on NET && EXPERIMENTAL
  115. ---help---
  116. POSIX variant of message queues is a part of IPC. In POSIX message
  117. queues every message has a priority which decides about succession
  118. of receiving it by a process. If you want to compile and run
  119. programs written e.g. for Solaris with use of its POSIX message
  120. queues (functions mq_*) say Y here.
  121. POSIX message queues are visible as a filesystem called 'mqueue'
  122. and can be mounted somewhere if you want to do filesystem
  123. operations on message queues.
  124. If unsure, say Y.
  125. config BSD_PROCESS_ACCT
  126. bool "BSD Process Accounting"
  127. help
  128. If you say Y here, a user level program will be able to instruct the
  129. kernel (via a special system call) to write process accounting
  130. information to a file: whenever a process exits, information about
  131. that process will be appended to the file by the kernel. The
  132. information includes things such as creation time, owning user,
  133. command name, memory usage, controlling terminal etc. (the complete
  134. list is in the struct acct in <file:include/linux/acct.h>). It is
  135. up to the user level program to do useful things with this
  136. information. This is generally a good idea, so say Y.
  137. config BSD_PROCESS_ACCT_V3
  138. bool "BSD Process Accounting version 3 file format"
  139. depends on BSD_PROCESS_ACCT
  140. default n
  141. help
  142. If you say Y here, the process accounting information is written
  143. in a new file format that also logs the process IDs of each
  144. process and it's parent. Note that this file format is incompatible
  145. with previous v0/v1/v2 file formats, so you will need updated tools
  146. for processing it. A preliminary version of these tools is available
  147. at <http://www.physik3.uni-rostock.de/tim/kernel/utils/acct/>.
  148. config TASKSTATS
  149. bool "Export task/process statistics through netlink (EXPERIMENTAL)"
  150. depends on NET
  151. default n
  152. help
  153. Export selected statistics for tasks/processes through the
  154. generic netlink interface. Unlike BSD process accounting, the
  155. statistics are available during the lifetime of tasks/processes as
  156. responses to commands. Like BSD accounting, they are sent to user
  157. space on task exit.
  158. Say N if unsure.
  159. config TASK_DELAY_ACCT
  160. bool "Enable per-task delay accounting (EXPERIMENTAL)"
  161. depends on TASKSTATS
  162. help
  163. Collect information on time spent by a task waiting for system
  164. resources like cpu, synchronous block I/O completion and swapping
  165. in pages. Such statistics can help in setting a task's priorities
  166. relative to other tasks for cpu, io, rss limits etc.
  167. Say N if unsure.
  168. config TASK_XACCT
  169. bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
  170. depends on TASKSTATS
  171. help
  172. Collect extended task accounting data and send the data
  173. to userland for processing over the taskstats interface.
  174. Say N if unsure.
  175. config TASK_IO_ACCOUNTING
  176. bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
  177. depends on TASK_XACCT
  178. help
  179. Collect information on the number of bytes of storage I/O which this
  180. task has caused.
  181. Say N if unsure.
  182. config AUDIT
  183. bool "Auditing support"
  184. depends on NET
  185. help
  186. Enable auditing infrastructure that can be used with another
  187. kernel subsystem, such as SELinux (which requires this for
  188. logging of avc messages output). Does not do system-call
  189. auditing without CONFIG_AUDITSYSCALL.
  190. config AUDITSYSCALL
  191. bool "Enable system-call auditing support"
  192. depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64|| SUPERH)
  193. default y if SECURITY_SELINUX
  194. help
  195. Enable low-overhead system-call auditing infrastructure that
  196. can be used independently or with another kernel subsystem,
  197. such as SELinux. To use audit's filesystem watch feature, please
  198. ensure that INOTIFY is configured.
  199. config AUDIT_TREE
  200. def_bool y
  201. depends on AUDITSYSCALL && INOTIFY
  202. config IKCONFIG
  203. tristate "Kernel .config support"
  204. ---help---
  205. This option enables the complete Linux kernel ".config" file
  206. contents to be saved in the kernel. It provides documentation
  207. of which kernel options are used in a running kernel or in an
  208. on-disk kernel. This information can be extracted from the kernel
  209. image file with the script scripts/extract-ikconfig and used as
  210. input to rebuild the current kernel or to build another kernel.
  211. It can also be extracted from a running kernel by reading
  212. /proc/config.gz if enabled (below).
  213. config IKCONFIG_PROC
  214. bool "Enable access to .config through /proc/config.gz"
  215. depends on IKCONFIG && PROC_FS
  216. ---help---
  217. This option enables access to the kernel configuration file
  218. through /proc/config.gz.
  219. config LOG_BUF_SHIFT
  220. int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
  221. range 12 21
  222. default 17 if S390 || LOCKDEP
  223. default 16 if X86_NUMAQ || IA64
  224. default 15 if SMP
  225. default 14
  226. help
  227. Select kernel log buffer size as a power of 2.
  228. Defaults and Examples:
  229. 17 => 128 KB for S/390
  230. 16 => 64 KB for x86 NUMAQ or IA-64
  231. 15 => 32 KB for SMP
  232. 14 => 16 KB for uniprocessor
  233. 13 => 8 KB
  234. 12 => 4 KB
  235. config CGROUPS
  236. bool "Control Group support"
  237. help
  238. This option will let you use process cgroup subsystems
  239. such as Cpusets
  240. Say N if unsure.
  241. config CGROUP_DEBUG
  242. bool "Example debug cgroup subsystem"
  243. depends on CGROUPS
  244. help
  245. This option enables a simple cgroup subsystem that
  246. exports useful debugging information about the cgroups
  247. framework
  248. Say N if unsure
  249. config CGROUP_NS
  250. bool "Namespace cgroup subsystem"
  251. depends on CGROUPS
  252. help
  253. Provides a simple namespace cgroup subsystem to
  254. provide hierarchical naming of sets of namespaces,
  255. for instance virtual servers and checkpoint/restart
  256. jobs.
  257. config CPUSETS
  258. bool "Cpuset support"
  259. depends on SMP && CGROUPS
  260. help
  261. This option will let you create and manage CPUSETs which
  262. allow dynamically partitioning a system into sets of CPUs and
  263. Memory Nodes and assigning tasks to run only within those sets.
  264. This is primarily useful on large SMP or NUMA systems.
  265. Say N if unsure.
  266. config FAIR_GROUP_SCHED
  267. bool "Fair group CPU scheduler"
  268. default y
  269. help
  270. This feature lets CPU scheduler recognize task groups and control CPU
  271. bandwidth allocation to such task groups.
  272. choice
  273. depends on FAIR_GROUP_SCHED
  274. prompt "Basis for grouping tasks"
  275. default FAIR_USER_SCHED
  276. config FAIR_USER_SCHED
  277. bool "user id"
  278. help
  279. This option will choose userid as the basis for grouping
  280. tasks, thus providing equal CPU bandwidth to each user.
  281. config FAIR_CGROUP_SCHED
  282. bool "Control groups"
  283. depends on CGROUPS
  284. help
  285. This option allows you to create arbitrary task groups
  286. using the "cgroup" pseudo filesystem and control
  287. the cpu bandwidth allocated to each such task group.
  288. Refer to Documentation/cgroups.txt for more information
  289. on "cgroup" pseudo filesystem.
  290. endchoice
  291. config CGROUP_CPUACCT
  292. bool "Simple CPU accounting cgroup subsystem"
  293. depends on CGROUPS
  294. help
  295. Provides a simple Resource Controller for monitoring the
  296. total CPU consumed by the tasks in a cgroup
  297. config RESOURCE_COUNTERS
  298. bool "Resource counters"
  299. help
  300. This option enables controller independent resource accounting
  301. infrastructure that works with cgroups
  302. depends on CGROUPS
  303. config SYSFS_DEPRECATED
  304. bool "Create deprecated sysfs files"
  305. depends on SYSFS
  306. default y
  307. help
  308. This option creates deprecated symlinks such as the
  309. "device"-link, the <subsystem>:<name>-link, and the
  310. "bus"-link. It may also add deprecated key in the
  311. uevent environment.
  312. None of these features or values should be used today, as
  313. they export driver core implementation details to userspace
  314. or export properties which can't be kept stable across kernel
  315. releases.
  316. If enabled, this option will also move any device structures
  317. that belong to a class, back into the /sys/class hierarchy, in
  318. order to support older versions of udev.
  319. If you are using a distro that was released in 2006 or later,
  320. it should be safe to say N here.
  321. config CGROUP_MEM_CONT
  322. bool "Memory controller for cgroups"
  323. depends on CGROUPS && RESOURCE_COUNTERS
  324. help
  325. Provides a memory controller that manages both page cache and
  326. RSS memory.
  327. config PROC_PID_CPUSET
  328. bool "Include legacy /proc/<pid>/cpuset file"
  329. depends on CPUSETS
  330. default y
  331. config RELAY
  332. bool "Kernel->user space relay support (formerly relayfs)"
  333. help
  334. This option enables support for relay interface support in
  335. certain file systems (such as debugfs).
  336. It is designed to provide an efficient mechanism for tools and
  337. facilities to relay large amounts of data from kernel space to
  338. user space.
  339. If unsure, say N.
  340. config NAMESPACES
  341. bool "Namespaces support" if EMBEDDED
  342. default !EMBEDDED
  343. help
  344. Provides the way to make tasks work with different objects using
  345. the same id. For example same IPC id may refer to different objects
  346. or same user id or pid may refer to different tasks when used in
  347. different namespaces.
  348. config UTS_NS
  349. bool "UTS namespace"
  350. depends on NAMESPACES
  351. help
  352. In this namespace tasks see different info provided with the
  353. uname() system call
  354. config IPC_NS
  355. bool "IPC namespace"
  356. depends on NAMESPACES && SYSVIPC
  357. help
  358. In this namespace tasks work with IPC ids which correspond to
  359. different IPC objects in different namespaces
  360. config USER_NS
  361. bool "User namespace (EXPERIMENTAL)"
  362. depends on NAMESPACES && EXPERIMENTAL
  363. help
  364. This allows containers, i.e. vservers, to use user namespaces
  365. to provide different user info for different servers.
  366. If unsure, say N.
  367. config PID_NS
  368. bool "PID Namespaces (EXPERIMENTAL)"
  369. default n
  370. depends on NAMESPACES && EXPERIMENTAL
  371. help
  372. Suport process id namespaces. This allows having multiple
  373. process with the same pid as long as they are in different
  374. pid namespaces. This is a building block of containers.
  375. Unless you want to work with an experimental feature
  376. say N here.
  377. config BLK_DEV_INITRD
  378. bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
  379. depends on BROKEN || !FRV
  380. help
  381. The initial RAM filesystem is a ramfs which is loaded by the
  382. boot loader (loadlin or lilo) and that is mounted as root
  383. before the normal boot procedure. It is typically used to
  384. load modules needed to mount the "real" root file system,
  385. etc. See <file:Documentation/initrd.txt> for details.
  386. If RAM disk support (BLK_DEV_RAM) is also included, this
  387. also enables initial RAM disk (initrd) support and adds
  388. 15 Kbytes (more on some other architectures) to the kernel size.
  389. If unsure say Y.
  390. if BLK_DEV_INITRD
  391. source "usr/Kconfig"
  392. endif
  393. config CC_OPTIMIZE_FOR_SIZE
  394. bool "Optimize for size (Look out for broken compilers!)"
  395. default y
  396. depends on ARM || H8300 || SUPERH || EXPERIMENTAL
  397. help
  398. Enabling this option will pass "-Os" instead of "-O2" to gcc
  399. resulting in a smaller kernel.
  400. WARNING: some versions of gcc may generate incorrect code with this
  401. option. If problems are observed, a gcc upgrade may be needed.
  402. If unsure, say N.
  403. config SYSCTL
  404. bool
  405. menuconfig EMBEDDED
  406. bool "Configure standard kernel features (for small systems)"
  407. help
  408. This option allows certain base kernel options and settings
  409. to be disabled or tweaked. This is for specialized
  410. environments which can tolerate a "non-standard" kernel.
  411. Only use this if you really know what you are doing.
  412. config UID16
  413. bool "Enable 16-bit UID system calls" if EMBEDDED
  414. depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_COMPAT) || UML || (X86_64 && IA32_EMULATION)
  415. default y
  416. help
  417. This enables the legacy 16-bit UID syscall wrappers.
  418. config SYSCTL_SYSCALL
  419. bool "Sysctl syscall support" if EMBEDDED
  420. default y
  421. select SYSCTL
  422. ---help---
  423. sys_sysctl uses binary paths that have been found challenging
  424. to properly maintain and use. The interface in /proc/sys
  425. using paths with ascii names is now the primary path to this
  426. information.
  427. Almost nothing using the binary sysctl interface so if you are
  428. trying to save some space it is probably safe to disable this,
  429. making your kernel marginally smaller.
  430. If unsure say Y here.
  431. config KALLSYMS
  432. bool "Load all symbols for debugging/ksymoops" if EMBEDDED
  433. default y
  434. help
  435. Say Y here to let the kernel print out symbolic crash information and
  436. symbolic stack backtraces. This increases the size of the kernel
  437. somewhat, as all symbols have to be loaded into the kernel image.
  438. config KALLSYMS_ALL
  439. bool "Include all symbols in kallsyms"
  440. depends on DEBUG_KERNEL && KALLSYMS
  441. help
  442. Normally kallsyms only contains the symbols of functions, for nicer
  443. OOPS messages. Some debuggers can use kallsyms for other
  444. symbols too: say Y here to include all symbols, if you need them
  445. and you don't care about adding 300k to the size of your kernel.
  446. Say N.
  447. config KALLSYMS_EXTRA_PASS
  448. bool "Do an extra kallsyms pass"
  449. depends on KALLSYMS
  450. help
  451. If kallsyms is not working correctly, the build will fail with
  452. inconsistent kallsyms data. If that occurs, log a bug report and
  453. turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
  454. Always say N here unless you find a bug in kallsyms, which must be
  455. reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
  456. you wait for kallsyms to be fixed.
  457. config HOTPLUG
  458. bool "Support for hot-pluggable devices" if EMBEDDED
  459. default y
  460. help
  461. This option is provided for the case where no hotplug or uevent
  462. capabilities is wanted by the kernel. You should only consider
  463. disabling this option for embedded systems that do not use modules, a
  464. dynamic /dev tree, or dynamic device discovery. Just say Y.
  465. config PRINTK
  466. default y
  467. bool "Enable support for printk" if EMBEDDED
  468. help
  469. This option enables normal printk support. Removing it
  470. eliminates most of the message strings from the kernel image
  471. and makes the kernel more or less silent. As this makes it
  472. very difficult to diagnose system problems, saying N here is
  473. strongly discouraged.
  474. config BUG
  475. bool "BUG() support" if EMBEDDED
  476. default y
  477. help
  478. Disabling this option eliminates support for BUG and WARN, reducing
  479. the size of your kernel image and potentially quietly ignoring
  480. numerous fatal conditions. You should only consider disabling this
  481. option for embedded systems with no facilities for reporting errors.
  482. Just say Y.
  483. config ELF_CORE
  484. default y
  485. bool "Enable ELF core dumps" if EMBEDDED
  486. help
  487. Enable support for generating core dumps. Disabling saves about 4k.
  488. config COMPAT_BRK
  489. bool "Disable heap randomization"
  490. default y
  491. help
  492. Randomizing heap placement makes heap exploits harder, but it
  493. also breaks ancient binaries (including anything libc5 based).
  494. This option changes the bootup default to heap randomization
  495. disabled, and can be overriden runtime by setting
  496. /proc/sys/kernel/randomize_va_space to 2.
  497. On non-ancient distros (post-2000 ones) N is usually a safe choice.
  498. config BASE_FULL
  499. default y
  500. bool "Enable full-sized data structures for core" if EMBEDDED
  501. help
  502. Disabling this option reduces the size of miscellaneous core
  503. kernel data structures. This saves memory on small machines,
  504. but may reduce performance.
  505. config FUTEX
  506. bool "Enable futex support" if EMBEDDED
  507. default y
  508. select RT_MUTEXES
  509. help
  510. Disabling this option will cause the kernel to be built without
  511. support for "fast userspace mutexes". The resulting kernel may not
  512. run glibc-based applications correctly.
  513. config ANON_INODES
  514. bool
  515. config EPOLL
  516. bool "Enable eventpoll support" if EMBEDDED
  517. default y
  518. select ANON_INODES
  519. help
  520. Disabling this option will cause the kernel to be built without
  521. support for epoll family of system calls.
  522. config SIGNALFD
  523. bool "Enable signalfd() system call" if EMBEDDED
  524. select ANON_INODES
  525. default y
  526. help
  527. Enable the signalfd() system call that allows to receive signals
  528. on a file descriptor.
  529. If unsure, say Y.
  530. config TIMERFD
  531. bool "Enable timerfd() system call" if EMBEDDED
  532. select ANON_INODES
  533. default y
  534. help
  535. Enable the timerfd() system call that allows to receive timer
  536. events on a file descriptor.
  537. If unsure, say Y.
  538. config EVENTFD
  539. bool "Enable eventfd() system call" if EMBEDDED
  540. select ANON_INODES
  541. default y
  542. help
  543. Enable the eventfd() system call that allows to receive both
  544. kernel notification (ie. KAIO) or userspace notifications.
  545. If unsure, say Y.
  546. config SHMEM
  547. bool "Use full shmem filesystem" if EMBEDDED
  548. default y
  549. depends on MMU
  550. help
  551. The shmem is an internal filesystem used to manage shared memory.
  552. It is backed by swap and manages resource limits. It is also exported
  553. to userspace as tmpfs if TMPFS is enabled. Disabling this
  554. option replaces shmem and tmpfs with the much simpler ramfs code,
  555. which may be appropriate on small systems without swap.
  556. config VM_EVENT_COUNTERS
  557. default y
  558. bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
  559. help
  560. VM event counters are needed for event counts to be shown.
  561. This option allows the disabling of the VM event counters
  562. on EMBEDDED systems. /proc/vmstat will only show page counts
  563. if VM event counters are disabled.
  564. config SLUB_DEBUG
  565. default y
  566. bool "Enable SLUB debugging support" if EMBEDDED
  567. depends on SLUB
  568. help
  569. SLUB has extensive debug support features. Disabling these can
  570. result in significant savings in code size. This also disables
  571. SLUB sysfs support. /sys/slab will not exist and there will be
  572. no support for cache validation etc.
  573. choice
  574. prompt "Choose SLAB allocator"
  575. default SLUB
  576. help
  577. This option allows to select a slab allocator.
  578. config SLAB
  579. bool "SLAB"
  580. help
  581. The regular slab allocator that is established and known to work
  582. well in all environments. It organizes cache hot objects in
  583. per cpu and per node queues. SLAB is the default choice for
  584. a slab allocator.
  585. config SLUB
  586. bool "SLUB (Unqueued Allocator)"
  587. help
  588. SLUB is a slab allocator that minimizes cache line usage
  589. instead of managing queues of cached objects (SLAB approach).
  590. Per cpu caching is realized using slabs of objects instead
  591. of queues of objects. SLUB can use memory efficiently
  592. and has enhanced diagnostics.
  593. config SLOB
  594. depends on EMBEDDED
  595. bool "SLOB (Simple Allocator)"
  596. help
  597. SLOB replaces the stock allocator with a drastically simpler
  598. allocator. SLOB is generally more space efficient but
  599. does not perform as well on large systems.
  600. endchoice
  601. config PROFILING
  602. bool "Profiling support (EXPERIMENTAL)"
  603. help
  604. Say Y here to enable the extended profiling support mechanisms used
  605. by profilers such as OProfile.
  606. config MARKERS
  607. bool "Activate markers"
  608. help
  609. Place an empty function call at each marker site. Can be
  610. dynamically changed for a probe function.
  611. source "arch/Kconfig"
  612. config PROC_PAGE_MONITOR
  613. default y
  614. depends on PROC_FS && MMU
  615. bool "Enable /proc page monitoring" if EMBEDDED
  616. help
  617. Various /proc files exist to monitor process memory utilization:
  618. /proc/pid/smaps, /proc/pid/clear_refs, /proc/pid/pagemap,
  619. /proc/kpagecount, and /proc/kpageflags. Disabling these
  620. interfaces will reduce the size of the kernel by approximately 4kb.
  621. endmenu # General setup
  622. config SLABINFO
  623. bool
  624. depends on PROC_FS
  625. depends on SLAB || SLUB
  626. default y
  627. config RT_MUTEXES
  628. boolean
  629. select PLIST
  630. config TINY_SHMEM
  631. default !SHMEM
  632. bool
  633. config BASE_SMALL
  634. int
  635. default 0 if BASE_FULL
  636. default 1 if !BASE_FULL
  637. menuconfig MODULES
  638. bool "Enable loadable module support"
  639. help
  640. Kernel modules are small pieces of compiled code which can
  641. be inserted in the running kernel, rather than being
  642. permanently built into the kernel. You use the "modprobe"
  643. tool to add (and sometimes remove) them. If you say Y here,
  644. many parts of the kernel can be built as modules (by
  645. answering M instead of Y where indicated): this is most
  646. useful for infrequently used options which are not required
  647. for booting. For more information, see the man pages for
  648. modprobe, lsmod, modinfo, insmod and rmmod.
  649. If you say Y here, you will need to run "make
  650. modules_install" to put the modules under /lib/modules/
  651. where modprobe can find them (you may need to be root to do
  652. this).
  653. If unsure, say Y.
  654. config MODULE_UNLOAD
  655. bool "Module unloading"
  656. depends on MODULES
  657. help
  658. Without this option you will not be able to unload any
  659. modules (note that some modules may not be unloadable
  660. anyway), which makes your kernel slightly smaller and
  661. simpler. If unsure, say Y.
  662. config MODULE_FORCE_UNLOAD
  663. bool "Forced module unloading"
  664. depends on MODULE_UNLOAD && EXPERIMENTAL
  665. help
  666. This option allows you to force a module to unload, even if the
  667. kernel believes it is unsafe: the kernel will remove the module
  668. without waiting for anyone to stop using it (using the -f option to
  669. rmmod). This is mainly for kernel developers and desperate users.
  670. If unsure, say N.
  671. config MODVERSIONS
  672. bool "Module versioning support"
  673. depends on MODULES
  674. help
  675. Usually, you have to use modules compiled with your kernel.
  676. Saying Y here makes it sometimes possible to use modules
  677. compiled for different kernels, by adding enough information
  678. to the modules to (hopefully) spot any changes which would
  679. make them incompatible with the kernel you are running. If
  680. unsure, say N.
  681. config MODULE_SRCVERSION_ALL
  682. bool "Source checksum for all modules"
  683. depends on MODULES
  684. help
  685. Modules which contain a MODULE_VERSION get an extra "srcversion"
  686. field inserted into their modinfo section, which contains a
  687. sum of the source files which made it. This helps maintainers
  688. see exactly which source was used to build a module (since
  689. others sometimes change the module source without updating
  690. the version). With this option, such a "srcversion" field
  691. will be created for all modules. If unsure, say N.
  692. config KMOD
  693. bool "Automatic kernel module loading"
  694. depends on MODULES
  695. help
  696. Normally when you have selected some parts of the kernel to
  697. be created as kernel modules, you must load them (using the
  698. "modprobe" command) before you can use them. If you say Y
  699. here, some parts of the kernel will be able to load modules
  700. automatically: when a part of the kernel needs a module, it
  701. runs modprobe with the appropriate arguments, thereby
  702. loading the module if it is available. If unsure, say Y.
  703. config STOP_MACHINE
  704. bool
  705. default y
  706. depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
  707. help
  708. Need stop_machine() primitive.
  709. source "block/Kconfig"
  710. config PREEMPT_NOTIFIERS
  711. bool
  712. choice
  713. prompt "RCU implementation type:"
  714. default CLASSIC_RCU
  715. help
  716. This allows you to choose either the classic RCU implementation
  717. that is designed for best read-side performance on non-realtime
  718. systems, or the preemptible RCU implementation for best latency
  719. on realtime systems. Note that some kernel preemption modes
  720. will restrict your choice.
  721. Select the default if you are unsure.
  722. config CLASSIC_RCU
  723. bool "Classic RCU"
  724. help
  725. This option selects the classic RCU implementation that is
  726. designed for best read-side performance on non-realtime
  727. systems.
  728. Say Y if you are unsure.
  729. config PREEMPT_RCU
  730. bool "Preemptible RCU"
  731. depends on PREEMPT
  732. help
  733. This option reduces the latency of the kernel by making certain
  734. RCU sections preemptible. Normally RCU code is non-preemptible, if
  735. this option is selected then read-only RCU sections become
  736. preemptible. This helps latency, but may expose bugs due to
  737. now-naive assumptions about each RCU read-side critical section
  738. remaining on a given CPU through its execution.
  739. Say N if you are unsure.
  740. endchoice