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 drivers that have been replaced by something else, and/or are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