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 drivers that have been replaced by something else, and/or are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