Kconfig 17 KB

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  1. menu "Code maturity level options"
  2. config EXPERIMENTAL
  3. bool "Prompt for development and/or incomplete code/drivers"
  4. ---help---
  5. Some of the various things that Linux supports (such as network
  6. drivers, file systems, network protocols, etc.) can be in a state
  7. of development where the functionality, stability, or the level of
  8. testing is not yet high enough for general use. This is usually
  9. known as the "alpha-test" phase among developers. If a feature is
  10. currently in alpha-test, then the developers usually discourage
  11. uninformed widespread use of this feature by the general public to
  12. avoid "Why doesn't this work?" type mail messages. However, active
  13. testing and use of these systems is welcomed. Just be aware that it
  14. may not meet the normal level of reliability or it may fail to work
  15. in some special cases. Detailed bug reports from people familiar
  16. with the kernel internals are usually welcomed by the developers
  17. (before submitting bug reports, please read the documents
  18. <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
  19. <file:Documentation/BUG-HUNTING>, and
  20. <file:Documentation/oops-tracing.txt> in the kernel source).
  21. This option will also make obsoleted drivers available. These are
  22. drivers that have been replaced by something else, and/or are
  23. scheduled to be removed in a future kernel release.
  24. Unless you intend to help test and develop a feature or driver that
  25. falls into this category, or you have a situation that requires
  26. using these features, you should probably say N here, which will
  27. cause the configurator to present you with fewer choices. If
  28. you say Y here, you will be offered the choice of using features or
  29. drivers that are currently considered to be in the alpha-test phase.
  30. config CLEAN_COMPILE
  31. bool "Select only drivers expected to compile cleanly" if EXPERIMENTAL
  32. default y
  33. help
  34. Select this option if you don't even want to see the option
  35. to configure known-broken drivers.
  36. If unsure, say Y
  37. config BROKEN
  38. bool
  39. depends on !CLEAN_COMPILE
  40. default y
  41. config BROKEN_ON_SMP
  42. bool
  43. depends on BROKEN || !SMP
  44. default y
  45. config LOCK_KERNEL
  46. bool
  47. depends on SMP || PREEMPT
  48. default y
  49. config INIT_ENV_ARG_LIMIT
  50. int
  51. default 32 if !USERMODE
  52. default 128 if USERMODE
  53. help
  54. This is the value of the two limits on the number of argument and of
  55. env.var passed to init from the kernel command line.
  56. endmenu
  57. menu "General setup"
  58. config LOCALVERSION
  59. string "Local version - append to kernel release"
  60. help
  61. Append an extra string to the end of your kernel version.
  62. This will show up when you type uname, for example.
  63. The string you set here will be appended after the contents of
  64. any files with a filename matching localversion* in your
  65. object and source tree, in that order. Your total string can
  66. be a maximum of 64 characters.
  67. config SWAP
  68. bool "Support for paging of anonymous memory (swap)"
  69. depends on MMU
  70. default y
  71. help
  72. This option allows you to choose whether you want to have support
  73. for socalled swap devices or swap files in your kernel that are
  74. used to provide more virtual memory than the actual RAM present
  75. in your computer. If unsure say Y.
  76. config SYSVIPC
  77. bool "System V IPC"
  78. depends on MMU
  79. ---help---
  80. Inter Process Communication is a suite of library functions and
  81. system calls which let processes (running programs) synchronize and
  82. exchange information. It is generally considered to be a good thing,
  83. and some programs won't run unless you say Y here. In particular, if
  84. you want to run the DOS emulator dosemu under Linux (read the
  85. DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
  86. you'll need to say Y here.
  87. You can find documentation about IPC with "info ipc" and also in
  88. section 6.4 of the Linux Programmer's Guide, available from
  89. <http://www.tldp.org/guides.html>.
  90. config POSIX_MQUEUE
  91. bool "POSIX Message Queues"
  92. depends on NET && EXPERIMENTAL
  93. ---help---
  94. POSIX variant of message queues is a part of IPC. In POSIX message
  95. queues every message has a priority which decides about succession
  96. of receiving it by a process. If you want to compile and run
  97. programs written e.g. for Solaris with use of its POSIX message
  98. queues (functions mq_*) say Y here. To use this feature you will
  99. also need mqueue library, available from
  100. <http://www.mat.uni.torun.pl/~wrona/posix_ipc/>
  101. POSIX message queues are visible as a filesystem called 'mqueue'
  102. and can be mounted somewhere if you want to do filesystem
  103. operations on message queues.
  104. If unsure, say Y.
  105. config BSD_PROCESS_ACCT
  106. bool "BSD Process Accounting"
  107. help
  108. If you say Y here, a user level program will be able to instruct the
  109. kernel (via a special system call) to write process accounting
  110. information to a file: whenever a process exits, information about
  111. that process will be appended to the file by the kernel. The
  112. information includes things such as creation time, owning user,
  113. command name, memory usage, controlling terminal etc. (the complete
  114. list is in the struct acct in <file:include/linux/acct.h>). It is
  115. up to the user level program to do useful things with this
  116. information. This is generally a good idea, so say Y.
  117. config BSD_PROCESS_ACCT_V3
  118. bool "BSD Process Accounting version 3 file format"
  119. depends on BSD_PROCESS_ACCT
  120. default n
  121. help
  122. If you say Y here, the process accounting information is written
  123. in a new file format that also logs the process IDs of each
  124. process and it's parent. Note that this file format is incompatible
  125. with previous v0/v1/v2 file formats, so you will need updated tools
  126. for processing it. A preliminary version of these tools is available
  127. at <http://www.physik3.uni-rostock.de/tim/kernel/utils/acct/>.
  128. config SYSCTL
  129. bool "Sysctl support"
  130. ---help---
  131. The sysctl interface provides a means of dynamically changing
  132. certain kernel parameters and variables on the fly without requiring
  133. a recompile of the kernel or reboot of the system. The primary
  134. interface consists of a system call, but if you say Y to "/proc
  135. file system support", a tree of modifiable sysctl entries will be
  136. generated beneath the /proc/sys directory. They are explained in the
  137. files in <file:Documentation/sysctl/>. Note that enabling this
  138. option will enlarge the kernel by at least 8 KB.
  139. As it is generally a good thing, you should say Y here unless
  140. building a kernel for install/rescue disks or your system is very
  141. limited in memory.
  142. config AUDIT
  143. bool "Auditing support"
  144. depends on NET
  145. default y if SECURITY_SELINUX
  146. help
  147. Enable auditing infrastructure that can be used with another
  148. kernel subsystem, such as SELinux (which requires this for
  149. logging of avc messages output). Does not do system-call
  150. auditing without CONFIG_AUDITSYSCALL.
  151. config AUDITSYSCALL
  152. bool "Enable system-call auditing support"
  153. depends on AUDIT && (X86 || PPC || PPC64 || ARCH_S390 || IA64 || UML)
  154. default y if SECURITY_SELINUX
  155. help
  156. Enable low-overhead system-call auditing infrastructure that
  157. can be used independently or with another kernel subsystem,
  158. such as SELinux.
  159. config HOTPLUG
  160. bool "Support for hot-pluggable devices" if !ARCH_S390
  161. default ARCH_S390
  162. help
  163. This option is provided for the case where no in-kernel-tree
  164. modules require HOTPLUG functionality, but a module built
  165. outside the kernel tree does. Such modules require Y here.
  166. config KOBJECT_UEVENT
  167. bool "Kernel Userspace Events"
  168. depends on NET
  169. default y
  170. help
  171. This option enables the kernel userspace event layer, which is a
  172. simple mechanism for kernel-to-user communication over a netlink
  173. socket.
  174. The goal of the kernel userspace events layer is to provide a simple
  175. and efficient events system, that notifies userspace about kobject
  176. state changes. This will enable applications to just listen for
  177. events instead of polling system devices and files.
  178. Hotplug events (kobject addition and removal) are also available on
  179. the netlink socket in addition to the execution of /sbin/hotplug if
  180. CONFIG_HOTPLUG is enabled.
  181. Say Y, unless you are building a system requiring minimal memory
  182. consumption.
  183. config IKCONFIG
  184. bool "Kernel .config support"
  185. ---help---
  186. This option enables the complete Linux kernel ".config" file
  187. contents to be saved in the kernel. It provides documentation
  188. of which kernel options are used in a running kernel or in an
  189. on-disk kernel. This information can be extracted from the kernel
  190. image file with the script scripts/extract-ikconfig and used as
  191. input to rebuild the current kernel or to build another kernel.
  192. It can also be extracted from a running kernel by reading
  193. /proc/config.gz if enabled (below).
  194. config IKCONFIG_PROC
  195. bool "Enable access to .config through /proc/config.gz"
  196. depends on IKCONFIG && PROC_FS
  197. ---help---
  198. This option enables access to the kernel configuration file
  199. through /proc/config.gz.
  200. config CPUSETS
  201. bool "Cpuset support"
  202. depends on SMP
  203. help
  204. This options will let you create and manage CPUSET's which
  205. allow dynamically partitioning a system into sets of CPUs and
  206. Memory Nodes and assigning tasks to run only within those sets.
  207. This is primarily useful on large SMP or NUMA systems.
  208. Say N if unsure.
  209. menuconfig EMBEDDED
  210. bool "Configure standard kernel features (for small systems)"
  211. help
  212. This option allows certain base kernel options and settings
  213. to be disabled or tweaked. This is for specialized
  214. environments which can tolerate a "non-standard" kernel.
  215. Only use this if you really know what you are doing.
  216. config KALLSYMS
  217. bool "Load all symbols for debugging/kksymoops" if EMBEDDED
  218. default y
  219. help
  220. Say Y here to let the kernel print out symbolic crash information and
  221. symbolic stack backtraces. This increases the size of the kernel
  222. somewhat, as all symbols have to be loaded into the kernel image.
  223. config KALLSYMS_ALL
  224. bool "Include all symbols in kallsyms"
  225. depends on DEBUG_KERNEL && KALLSYMS
  226. help
  227. Normally kallsyms only contains the symbols of functions, for nicer
  228. OOPS messages. Some debuggers can use kallsyms for other
  229. symbols too: say Y here to include all symbols, and you
  230. don't care about adding 300k to the size of your kernel.
  231. Say N.
  232. config KALLSYMS_EXTRA_PASS
  233. bool "Do an extra kallsyms pass"
  234. depends on KALLSYMS
  235. help
  236. If kallsyms is not working correctly, the build will fail with
  237. inconsistent kallsyms data. If that occurs, log a bug report and
  238. turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
  239. Always say N here unless you find a bug in kallsyms, which must be
  240. reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
  241. you wait for kallsyms to be fixed.
  242. config PRINTK
  243. default y
  244. bool "Enable support for printk" if EMBEDDED
  245. help
  246. This option enables normal printk support. Removing it
  247. eliminates most of the message strings from the kernel image
  248. and makes the kernel more or less silent. As this makes it
  249. very difficult to diagnose system problems, saying N here is
  250. strongly discouraged.
  251. config BUG
  252. bool "BUG() support" if EMBEDDED
  253. default y
  254. help
  255. Disabling this option eliminates support for BUG and WARN, reducing
  256. the size of your kernel image and potentially quietly ignoring
  257. numerous fatal conditions. You should only consider disabling this
  258. option for embedded systems with no facilities for reporting errors.
  259. Just say Y.
  260. config BASE_FULL
  261. default y
  262. bool "Enable full-sized data structures for core" if EMBEDDED
  263. help
  264. Disabling this option reduces the size of miscellaneous core
  265. kernel data structures. This saves memory on small machines,
  266. but may reduce performance.
  267. config FUTEX
  268. bool "Enable futex support" if EMBEDDED
  269. default y
  270. help
  271. Disabling this option will cause the kernel to be built without
  272. support for "fast userspace mutexes". The resulting kernel may not
  273. run glibc-based applications correctly.
  274. config EPOLL
  275. bool "Enable eventpoll support" if EMBEDDED
  276. default y
  277. help
  278. Disabling this option will cause the kernel to be built without
  279. support for epoll family of system calls.
  280. config CC_OPTIMIZE_FOR_SIZE
  281. bool "Optimize for size" if EMBEDDED
  282. default y if ARM || H8300
  283. help
  284. Enabling this option will pass "-Os" instead of "-O2" to gcc
  285. resulting in a smaller kernel.
  286. WARNING: some versions of gcc may generate incorrect code with this
  287. option. If problems are observed, a gcc upgrade may be needed.
  288. If unsure, say N.
  289. config SHMEM
  290. bool "Use full shmem filesystem" if EMBEDDED
  291. default y
  292. depends on MMU
  293. help
  294. The shmem is an internal filesystem used to manage shared memory.
  295. It is backed by swap and manages resource limits. It is also exported
  296. to userspace as tmpfs if TMPFS is enabled. Disabling this
  297. option replaces shmem and tmpfs with the much simpler ramfs code,
  298. which may be appropriate on small systems without swap.
  299. config CC_ALIGN_FUNCTIONS
  300. int "Function alignment" if EMBEDDED
  301. default 0
  302. help
  303. Align the start of functions to the next power-of-two greater than n,
  304. skipping up to n bytes. For instance, 32 aligns functions
  305. to the next 32-byte boundary, but 24 would align to the next
  306. 32-byte boundary only if this can be done by skipping 23 bytes or less.
  307. Zero means use compiler's default.
  308. config CC_ALIGN_LABELS
  309. int "Label alignment" if EMBEDDED
  310. default 0
  311. help
  312. Align all branch targets to a power-of-two boundary, skipping
  313. up to n bytes like ALIGN_FUNCTIONS. This option can easily
  314. make code slower, because it must insert dummy operations for
  315. when the branch target is reached in the usual flow of the code.
  316. Zero means use compiler's default.
  317. config CC_ALIGN_LOOPS
  318. int "Loop alignment" if EMBEDDED
  319. default 0
  320. help
  321. Align loops to a power-of-two boundary, skipping up to n bytes.
  322. Zero means use compiler's default.
  323. config CC_ALIGN_JUMPS
  324. int "Jump alignment" if EMBEDDED
  325. default 0
  326. help
  327. Align branch targets to a power-of-two boundary, for branch
  328. targets where the targets can only be reached by jumping,
  329. skipping up to n bytes like ALIGN_FUNCTIONS. In this case,
  330. no dummy operations need be executed.
  331. Zero means use compiler's default.
  332. endmenu # General setup
  333. config TINY_SHMEM
  334. default !SHMEM
  335. bool
  336. config BASE_SMALL
  337. int
  338. default 0 if BASE_FULL
  339. default 1 if !BASE_FULL
  340. menu "Loadable module support"
  341. config MODULES
  342. bool "Enable loadable module support"
  343. help
  344. Kernel modules are small pieces of compiled code which can
  345. be inserted in the running kernel, rather than being
  346. permanently built into the kernel. You use the "modprobe"
  347. tool to add (and sometimes remove) them. If you say Y here,
  348. many parts of the kernel can be built as modules (by
  349. answering M instead of Y where indicated): this is most
  350. useful for infrequently used options which are not required
  351. for booting. For more information, see the man pages for
  352. modprobe, lsmod, modinfo, insmod and rmmod.
  353. If you say Y here, you will need to run "make
  354. modules_install" to put the modules under /lib/modules/
  355. where modprobe can find them (you may need to be root to do
  356. this).
  357. If unsure, say Y.
  358. config MODULE_UNLOAD
  359. bool "Module unloading"
  360. depends on MODULES
  361. help
  362. Without this option you will not be able to unload any
  363. modules (note that some modules may not be unloadable
  364. anyway), which makes your kernel slightly smaller and
  365. simpler. If unsure, say Y.
  366. config MODULE_FORCE_UNLOAD
  367. bool "Forced module unloading"
  368. depends on MODULE_UNLOAD && EXPERIMENTAL
  369. help
  370. This option allows you to force a module to unload, even if the
  371. kernel believes it is unsafe: the kernel will remove the module
  372. without waiting for anyone to stop using it (using the -f option to
  373. rmmod). This is mainly for kernel developers and desperate users.
  374. If unsure, say N.
  375. config OBSOLETE_MODPARM
  376. bool
  377. default y
  378. depends on MODULES
  379. help
  380. You need this option to use module parameters on modules which
  381. have not been converted to the new module parameter system yet.
  382. If unsure, say Y.
  383. config MODVERSIONS
  384. bool "Module versioning support (EXPERIMENTAL)"
  385. depends on MODULES && EXPERIMENTAL
  386. help
  387. Usually, you have to use modules compiled with your kernel.
  388. Saying Y here makes it sometimes possible to use modules
  389. compiled for different kernels, by adding enough information
  390. to the modules to (hopefully) spot any changes which would
  391. make them incompatible with the kernel you are running. If
  392. unsure, say N.
  393. config MODULE_SRCVERSION_ALL
  394. bool "Source checksum for all modules"
  395. depends on MODULES
  396. help
  397. Modules which contain a MODULE_VERSION get an extra "srcversion"
  398. field inserted into their modinfo section, which contains a
  399. sum of the source files which made it. This helps maintainers
  400. see exactly which source was used to build a module (since
  401. others sometimes change the module source without updating
  402. the version). With this option, such a "srcversion" field
  403. will be created for all modules. If unsure, say N.
  404. config KMOD
  405. bool "Automatic kernel module loading"
  406. depends on MODULES
  407. help
  408. Normally when you have selected some parts of the kernel to
  409. be created as kernel modules, you must load them (using the
  410. "modprobe" command) before you can use them. If you say Y
  411. here, some parts of the kernel will be able to load modules
  412. automatically: when a part of the kernel needs a module, it
  413. runs modprobe with the appropriate arguments, thereby
  414. loading the module if it is available. If unsure, say Y.
  415. config STOP_MACHINE
  416. bool
  417. default y
  418. depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
  419. help
  420. Need stop_machine() primitive.
  421. endmenu