Kconfig 28 KB

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  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 drivers that have been replaced by something else, and/or are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 GROUP_SCHED
  267. bool "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. config FAIR_GROUP_SCHED
  273. bool "Group scheduling for SCHED_OTHER"
  274. depends on GROUP_SCHED
  275. default y
  276. config RT_GROUP_SCHED
  277. bool "Group scheduling for SCHED_RR/FIFO"
  278. depends on EXPERIMENTAL
  279. depends on GROUP_SCHED
  280. default n
  281. choice
  282. depends on GROUP_SCHED
  283. prompt "Basis for grouping tasks"
  284. default USER_SCHED
  285. config USER_SCHED
  286. bool "user id"
  287. help
  288. This option will choose userid as the basis for grouping
  289. tasks, thus providing equal CPU bandwidth to each user.
  290. config CGROUP_SCHED
  291. bool "Control groups"
  292. depends on CGROUPS
  293. help
  294. This option allows you to create arbitrary task groups
  295. using the "cgroup" pseudo filesystem and control
  296. the cpu bandwidth allocated to each such task group.
  297. Refer to Documentation/cgroups.txt for more information
  298. on "cgroup" pseudo filesystem.
  299. endchoice
  300. config CGROUP_CPUACCT
  301. bool "Simple CPU accounting cgroup subsystem"
  302. depends on CGROUPS
  303. help
  304. Provides a simple Resource Controller for monitoring the
  305. total CPU consumed by the tasks in a cgroup
  306. config RESOURCE_COUNTERS
  307. bool "Resource counters"
  308. help
  309. This option enables controller independent resource accounting
  310. infrastructure that works with cgroups
  311. depends on CGROUPS
  312. config SYSFS_DEPRECATED
  313. bool "Create deprecated sysfs files"
  314. depends on SYSFS
  315. default y
  316. help
  317. This option creates deprecated symlinks such as the
  318. "device"-link, the <subsystem>:<name>-link, and the
  319. "bus"-link. It may also add deprecated key in the
  320. uevent environment.
  321. None of these features or values should be used today, as
  322. they export driver core implementation details to userspace
  323. or export properties which can't be kept stable across kernel
  324. releases.
  325. If enabled, this option will also move any device structures
  326. that belong to a class, back into the /sys/class hierarchy, in
  327. order to support older versions of udev.
  328. If you are using a distro that was released in 2006 or later,
  329. it should be safe to say N here.
  330. config CGROUP_MEM_CONT
  331. bool "Memory controller for cgroups"
  332. depends on CGROUPS && RESOURCE_COUNTERS
  333. help
  334. Provides a memory controller that manages both page cache and
  335. RSS memory.
  336. Note that setting this option increases fixed memory overhead
  337. associated with each page of memory in the system by 4/8 bytes
  338. and also increases cache misses because struct page on many 64bit
  339. systems will not fit into a single cache line anymore.
  340. Only enable when you're ok with these trade offs and really
  341. sure you need the memory controller.
  342. config PROC_PID_CPUSET
  343. bool "Include legacy /proc/<pid>/cpuset file"
  344. depends on CPUSETS
  345. default y
  346. config RELAY
  347. bool "Kernel->user space relay support (formerly relayfs)"
  348. help
  349. This option enables support for relay interface support in
  350. certain file systems (such as debugfs).
  351. It is designed to provide an efficient mechanism for tools and
  352. facilities to relay large amounts of data from kernel space to
  353. user space.
  354. If unsure, say N.
  355. config NAMESPACES
  356. bool "Namespaces support" if EMBEDDED
  357. default !EMBEDDED
  358. help
  359. Provides the way to make tasks work with different objects using
  360. the same id. For example same IPC id may refer to different objects
  361. or same user id or pid may refer to different tasks when used in
  362. different namespaces.
  363. config UTS_NS
  364. bool "UTS namespace"
  365. depends on NAMESPACES
  366. help
  367. In this namespace tasks see different info provided with the
  368. uname() system call
  369. config IPC_NS
  370. bool "IPC namespace"
  371. depends on NAMESPACES && SYSVIPC
  372. help
  373. In this namespace tasks work with IPC ids which correspond to
  374. different IPC objects in different namespaces
  375. config USER_NS
  376. bool "User namespace (EXPERIMENTAL)"
  377. depends on NAMESPACES && EXPERIMENTAL
  378. help
  379. This allows containers, i.e. vservers, to use user namespaces
  380. to provide different user info for different servers.
  381. If unsure, say N.
  382. config PID_NS
  383. bool "PID Namespaces (EXPERIMENTAL)"
  384. default n
  385. depends on NAMESPACES && EXPERIMENTAL
  386. help
  387. Suport process id namespaces. This allows having multiple
  388. process with the same pid as long as they are in different
  389. pid namespaces. This is a building block of containers.
  390. Unless you want to work with an experimental feature
  391. say N here.
  392. config BLK_DEV_INITRD
  393. bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
  394. depends on BROKEN || !FRV
  395. help
  396. The initial RAM filesystem is a ramfs which is loaded by the
  397. boot loader (loadlin or lilo) and that is mounted as root
  398. before the normal boot procedure. It is typically used to
  399. load modules needed to mount the "real" root file system,
  400. etc. See <file:Documentation/initrd.txt> for details.
  401. If RAM disk support (BLK_DEV_RAM) is also included, this
  402. also enables initial RAM disk (initrd) support and adds
  403. 15 Kbytes (more on some other architectures) to the kernel size.
  404. If unsure say Y.
  405. if BLK_DEV_INITRD
  406. source "usr/Kconfig"
  407. endif
  408. config CC_OPTIMIZE_FOR_SIZE
  409. bool "Optimize for size (Look out for broken compilers!)"
  410. default y
  411. depends on ARM || H8300 || SUPERH || EXPERIMENTAL
  412. help
  413. Enabling this option will pass "-Os" instead of "-O2" to gcc
  414. resulting in a smaller kernel.
  415. WARNING: some versions of gcc may generate incorrect code with this
  416. option. If problems are observed, a gcc upgrade may be needed.
  417. If unsure, say N.
  418. config SYSCTL
  419. bool
  420. menuconfig EMBEDDED
  421. bool "Configure standard kernel features (for small systems)"
  422. help
  423. This option allows certain base kernel options and settings
  424. to be disabled or tweaked. This is for specialized
  425. environments which can tolerate a "non-standard" kernel.
  426. Only use this if you really know what you are doing.
  427. config UID16
  428. bool "Enable 16-bit UID system calls" if EMBEDDED
  429. depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_COMPAT) || UML || (X86_64 && IA32_EMULATION)
  430. default y
  431. help
  432. This enables the legacy 16-bit UID syscall wrappers.
  433. config SYSCTL_SYSCALL
  434. bool "Sysctl syscall support" if EMBEDDED
  435. default y
  436. select SYSCTL
  437. ---help---
  438. sys_sysctl uses binary paths that have been found challenging
  439. to properly maintain and use. The interface in /proc/sys
  440. using paths with ascii names is now the primary path to this
  441. information.
  442. Almost nothing using the binary sysctl interface so if you are
  443. trying to save some space it is probably safe to disable this,
  444. making your kernel marginally smaller.
  445. If unsure say Y here.
  446. config KALLSYMS
  447. bool "Load all symbols for debugging/ksymoops" if EMBEDDED
  448. default y
  449. help
  450. Say Y here to let the kernel print out symbolic crash information and
  451. symbolic stack backtraces. This increases the size of the kernel
  452. somewhat, as all symbols have to be loaded into the kernel image.
  453. config KALLSYMS_ALL
  454. bool "Include all symbols in kallsyms"
  455. depends on DEBUG_KERNEL && KALLSYMS
  456. help
  457. Normally kallsyms only contains the symbols of functions, for nicer
  458. OOPS messages. Some debuggers can use kallsyms for other
  459. symbols too: say Y here to include all symbols, if you need them
  460. and you don't care about adding 300k to the size of your kernel.
  461. Say N.
  462. config KALLSYMS_EXTRA_PASS
  463. bool "Do an extra kallsyms pass"
  464. depends on KALLSYMS
  465. help
  466. If kallsyms is not working correctly, the build will fail with
  467. inconsistent kallsyms data. If that occurs, log a bug report and
  468. turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
  469. Always say N here unless you find a bug in kallsyms, which must be
  470. reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
  471. you wait for kallsyms to be fixed.
  472. config HOTPLUG
  473. bool "Support for hot-pluggable devices" if EMBEDDED
  474. default y
  475. help
  476. This option is provided for the case where no hotplug or uevent
  477. capabilities is wanted by the kernel. You should only consider
  478. disabling this option for embedded systems that do not use modules, a
  479. dynamic /dev tree, or dynamic device discovery. Just say Y.
  480. config PRINTK
  481. default y
  482. bool "Enable support for printk" if EMBEDDED
  483. help
  484. This option enables normal printk support. Removing it
  485. eliminates most of the message strings from the kernel image
  486. and makes the kernel more or less silent. As this makes it
  487. very difficult to diagnose system problems, saying N here is
  488. strongly discouraged.
  489. config BUG
  490. bool "BUG() support" if EMBEDDED
  491. default y
  492. help
  493. Disabling this option eliminates support for BUG and WARN, reducing
  494. the size of your kernel image and potentially quietly ignoring
  495. numerous fatal conditions. You should only consider disabling this
  496. option for embedded systems with no facilities for reporting errors.
  497. Just say Y.
  498. config ELF_CORE
  499. default y
  500. bool "Enable ELF core dumps" if EMBEDDED
  501. help
  502. Enable support for generating core dumps. Disabling saves about 4k.
  503. config COMPAT_BRK
  504. bool "Disable heap randomization"
  505. default y
  506. help
  507. Randomizing heap placement makes heap exploits harder, but it
  508. also breaks ancient binaries (including anything libc5 based).
  509. This option changes the bootup default to heap randomization
  510. disabled, and can be overriden runtime by setting
  511. /proc/sys/kernel/randomize_va_space to 2.
  512. On non-ancient distros (post-2000 ones) N is usually a safe choice.
  513. config BASE_FULL
  514. default y
  515. bool "Enable full-sized data structures for core" if EMBEDDED
  516. help
  517. Disabling this option reduces the size of miscellaneous core
  518. kernel data structures. This saves memory on small machines,
  519. but may reduce performance.
  520. config FUTEX
  521. bool "Enable futex support" if EMBEDDED
  522. default y
  523. select RT_MUTEXES
  524. help
  525. Disabling this option will cause the kernel to be built without
  526. support for "fast userspace mutexes". The resulting kernel may not
  527. run glibc-based applications correctly.
  528. config ANON_INODES
  529. bool
  530. config EPOLL
  531. bool "Enable eventpoll support" if EMBEDDED
  532. default y
  533. select ANON_INODES
  534. help
  535. Disabling this option will cause the kernel to be built without
  536. support for epoll family of system calls.
  537. config SIGNALFD
  538. bool "Enable signalfd() system call" if EMBEDDED
  539. select ANON_INODES
  540. default y
  541. help
  542. Enable the signalfd() system call that allows to receive signals
  543. on a file descriptor.
  544. If unsure, say Y.
  545. config TIMERFD
  546. bool "Enable timerfd() system call" if EMBEDDED
  547. select ANON_INODES
  548. default y
  549. help
  550. Enable the timerfd() system call that allows to receive timer
  551. events on a file descriptor.
  552. If unsure, say Y.
  553. config EVENTFD
  554. bool "Enable eventfd() system call" if EMBEDDED
  555. select ANON_INODES
  556. default y
  557. help
  558. Enable the eventfd() system call that allows to receive both
  559. kernel notification (ie. KAIO) or userspace notifications.
  560. If unsure, say Y.
  561. config SHMEM
  562. bool "Use full shmem filesystem" if EMBEDDED
  563. default y
  564. depends on MMU
  565. help
  566. The shmem is an internal filesystem used to manage shared memory.
  567. It is backed by swap and manages resource limits. It is also exported
  568. to userspace as tmpfs if TMPFS is enabled. Disabling this
  569. option replaces shmem and tmpfs with the much simpler ramfs code,
  570. which may be appropriate on small systems without swap.
  571. config VM_EVENT_COUNTERS
  572. default y
  573. bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
  574. help
  575. VM event counters are needed for event counts to be shown.
  576. This option allows the disabling of the VM event counters
  577. on EMBEDDED systems. /proc/vmstat will only show page counts
  578. if VM event counters are disabled.
  579. config SLUB_DEBUG
  580. default y
  581. bool "Enable SLUB debugging support" if EMBEDDED
  582. depends on SLUB
  583. help
  584. SLUB has extensive debug support features. Disabling these can
  585. result in significant savings in code size. This also disables
  586. SLUB sysfs support. /sys/slab will not exist and there will be
  587. no support for cache validation etc.
  588. choice
  589. prompt "Choose SLAB allocator"
  590. default SLUB
  591. help
  592. This option allows to select a slab allocator.
  593. config SLAB
  594. bool "SLAB"
  595. help
  596. The regular slab allocator that is established and known to work
  597. well in all environments. It organizes cache hot objects in
  598. per cpu and per node queues. SLAB is the default choice for
  599. a slab allocator.
  600. config SLUB
  601. bool "SLUB (Unqueued Allocator)"
  602. help
  603. SLUB is a slab allocator that minimizes cache line usage
  604. instead of managing queues of cached objects (SLAB approach).
  605. Per cpu caching is realized using slabs of objects instead
  606. of queues of objects. SLUB can use memory efficiently
  607. and has enhanced diagnostics.
  608. config SLOB
  609. depends on EMBEDDED
  610. bool "SLOB (Simple Allocator)"
  611. help
  612. SLOB replaces the stock allocator with a drastically simpler
  613. allocator. SLOB is generally more space efficient but
  614. does not perform as well on large systems.
  615. endchoice
  616. config PROFILING
  617. bool "Profiling support (EXPERIMENTAL)"
  618. help
  619. Say Y here to enable the extended profiling support mechanisms used
  620. by profilers such as OProfile.
  621. config MARKERS
  622. bool "Activate markers"
  623. help
  624. Place an empty function call at each marker site. Can be
  625. dynamically changed for a probe function.
  626. source "arch/Kconfig"
  627. config PROC_PAGE_MONITOR
  628. default y
  629. depends on PROC_FS && MMU
  630. bool "Enable /proc page monitoring" if EMBEDDED
  631. help
  632. Various /proc files exist to monitor process memory utilization:
  633. /proc/pid/smaps, /proc/pid/clear_refs, /proc/pid/pagemap,
  634. /proc/kpagecount, and /proc/kpageflags. Disabling these
  635. interfaces will reduce the size of the kernel by approximately 4kb.
  636. endmenu # General setup
  637. config SLABINFO
  638. bool
  639. depends on PROC_FS
  640. depends on SLAB || SLUB
  641. default y
  642. config RT_MUTEXES
  643. boolean
  644. select PLIST
  645. config TINY_SHMEM
  646. default !SHMEM
  647. bool
  648. config BASE_SMALL
  649. int
  650. default 0 if BASE_FULL
  651. default 1 if !BASE_FULL
  652. menuconfig MODULES
  653. bool "Enable loadable module support"
  654. help
  655. Kernel modules are small pieces of compiled code which can
  656. be inserted in the running kernel, rather than being
  657. permanently built into the kernel. You use the "modprobe"
  658. tool to add (and sometimes remove) them. If you say Y here,
  659. many parts of the kernel can be built as modules (by
  660. answering M instead of Y where indicated): this is most
  661. useful for infrequently used options which are not required
  662. for booting. For more information, see the man pages for
  663. modprobe, lsmod, modinfo, insmod and rmmod.
  664. If you say Y here, you will need to run "make
  665. modules_install" to put the modules under /lib/modules/
  666. where modprobe can find them (you may need to be root to do
  667. this).
  668. If unsure, say Y.
  669. config MODULE_UNLOAD
  670. bool "Module unloading"
  671. depends on MODULES
  672. help
  673. Without this option you will not be able to unload any
  674. modules (note that some modules may not be unloadable
  675. anyway), which makes your kernel slightly smaller and
  676. simpler. If unsure, say Y.
  677. config MODULE_FORCE_UNLOAD
  678. bool "Forced module unloading"
  679. depends on MODULE_UNLOAD && EXPERIMENTAL
  680. help
  681. This option allows you to force a module to unload, even if the
  682. kernel believes it is unsafe: the kernel will remove the module
  683. without waiting for anyone to stop using it (using the -f option to
  684. rmmod). This is mainly for kernel developers and desperate users.
  685. If unsure, say N.
  686. config MODVERSIONS
  687. bool "Module versioning support"
  688. depends on MODULES
  689. help
  690. Usually, you have to use modules compiled with your kernel.
  691. Saying Y here makes it sometimes possible to use modules
  692. compiled for different kernels, by adding enough information
  693. to the modules to (hopefully) spot any changes which would
  694. make them incompatible with the kernel you are running. If
  695. unsure, say N.
  696. config MODULE_SRCVERSION_ALL
  697. bool "Source checksum for all modules"
  698. depends on MODULES
  699. help
  700. Modules which contain a MODULE_VERSION get an extra "srcversion"
  701. field inserted into their modinfo section, which contains a
  702. sum of the source files which made it. This helps maintainers
  703. see exactly which source was used to build a module (since
  704. others sometimes change the module source without updating
  705. the version). With this option, such a "srcversion" field
  706. will be created for all modules. If unsure, say N.
  707. config KMOD
  708. bool "Automatic kernel module loading"
  709. depends on MODULES
  710. help
  711. Normally when you have selected some parts of the kernel to
  712. be created as kernel modules, you must load them (using the
  713. "modprobe" command) before you can use them. If you say Y
  714. here, some parts of the kernel will be able to load modules
  715. automatically: when a part of the kernel needs a module, it
  716. runs modprobe with the appropriate arguments, thereby
  717. loading the module if it is available. If unsure, say Y.
  718. config STOP_MACHINE
  719. bool
  720. default y
  721. depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
  722. help
  723. Need stop_machine() primitive.
  724. source "block/Kconfig"
  725. config PREEMPT_NOTIFIERS
  726. bool
  727. choice
  728. prompt "RCU implementation type:"
  729. default CLASSIC_RCU
  730. help
  731. This allows you to choose either the classic RCU implementation
  732. that is designed for best read-side performance on non-realtime
  733. systems, or the preemptible RCU implementation for best latency
  734. on realtime systems. Note that some kernel preemption modes
  735. will restrict your choice.
  736. Select the default if you are unsure.
  737. config CLASSIC_RCU
  738. bool "Classic RCU"
  739. help
  740. This option selects the classic RCU implementation that is
  741. designed for best read-side performance on non-realtime
  742. systems.
  743. Say Y if you are unsure.
  744. config PREEMPT_RCU
  745. bool "Preemptible RCU"
  746. depends on PREEMPT
  747. help
  748. This option reduces the latency of the kernel by making certain
  749. RCU sections preemptible. Normally RCU code is non-preemptible, if
  750. this option is selected then read-only RCU sections become
  751. preemptible. This helps latency, but may expose bugs due to
  752. now-naive assumptions about each RCU read-side critical section
  753. remaining on a given CPU through its execution.
  754. Say N if you are unsure.
  755. endchoice