Kconfig 40 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. config CONSTRUCTORS
  17. bool
  18. depends on !UML
  19. default y
  20. menu "General setup"
  21. config EXPERIMENTAL
  22. bool "Prompt for development and/or incomplete code/drivers"
  23. ---help---
  24. Some of the various things that Linux supports (such as network
  25. drivers, file systems, network protocols, etc.) can be in a state
  26. of development where the functionality, stability, or the level of
  27. testing is not yet high enough for general use. This is usually
  28. known as the "alpha-test" phase among developers. If a feature is
  29. currently in alpha-test, then the developers usually discourage
  30. uninformed widespread use of this feature by the general public to
  31. avoid "Why doesn't this work?" type mail messages. However, active
  32. testing and use of these systems is welcomed. Just be aware that it
  33. may not meet the normal level of reliability or it may fail to work
  34. in some special cases. Detailed bug reports from people familiar
  35. with the kernel internals are usually welcomed by the developers
  36. (before submitting bug reports, please read the documents
  37. <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
  38. <file:Documentation/BUG-HUNTING>, and
  39. <file:Documentation/oops-tracing.txt> in the kernel source).
  40. This option will also make obsoleted drivers available. These are
  41. drivers that have been replaced by something else, and/or are
  42. scheduled to be removed in a future kernel release.
  43. Unless you intend to help test and develop a feature or driver that
  44. falls into this category, or you have a situation that requires
  45. using these features, you should probably say N here, which will
  46. cause the configurator to present you with fewer choices. If
  47. you say Y here, you will be offered the choice of using features or
  48. drivers that are currently considered to be in the alpha-test phase.
  49. config BROKEN
  50. bool
  51. config BROKEN_ON_SMP
  52. bool
  53. depends on BROKEN || !SMP
  54. default y
  55. config LOCK_KERNEL
  56. bool
  57. depends on SMP || PREEMPT
  58. default y
  59. config INIT_ENV_ARG_LIMIT
  60. int
  61. default 32 if !UML
  62. default 128 if UML
  63. help
  64. Maximum of each of the number of arguments and environment
  65. variables passed to init from the kernel command line.
  66. config CROSS_COMPILE
  67. string "Cross-compiler tool prefix"
  68. help
  69. Same as running 'make CROSS_COMPILE=prefix-' but stored for
  70. default make runs in this kernel build directory. You don't
  71. need to set this unless you want the configured kernel build
  72. directory to select the cross-compiler automatically.
  73. config LOCALVERSION
  74. string "Local version - append to kernel release"
  75. help
  76. Append an extra string to the end of your kernel version.
  77. This will show up when you type uname, for example.
  78. The string you set here will be appended after the contents of
  79. any files with a filename matching localversion* in your
  80. object and source tree, in that order. Your total string can
  81. be a maximum of 64 characters.
  82. config LOCALVERSION_AUTO
  83. bool "Automatically append version information to the version string"
  84. default y
  85. help
  86. This will try to automatically determine if the current tree is a
  87. release tree by looking for git tags that belong to the current
  88. top of tree revision.
  89. A string of the format -gxxxxxxxx will be added to the localversion
  90. if a git-based tree is found. The string generated by this will be
  91. appended after any matching localversion* files, and after the value
  92. set in CONFIG_LOCALVERSION.
  93. (The actual string used here is the first eight characters produced
  94. by running the command:
  95. $ git rev-parse --verify HEAD
  96. which is done within the script "scripts/setlocalversion".)
  97. config HAVE_KERNEL_GZIP
  98. bool
  99. config HAVE_KERNEL_BZIP2
  100. bool
  101. config HAVE_KERNEL_LZMA
  102. bool
  103. config HAVE_KERNEL_LZO
  104. bool
  105. choice
  106. prompt "Kernel compression mode"
  107. default KERNEL_GZIP
  108. depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_LZO
  109. help
  110. The linux kernel is a kind of self-extracting executable.
  111. Several compression algorithms are available, which differ
  112. in efficiency, compression and decompression speed.
  113. Compression speed is only relevant when building a kernel.
  114. Decompression speed is relevant at each boot.
  115. If you have any problems with bzip2 or lzma compressed
  116. kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
  117. version of this functionality (bzip2 only), for 2.4, was
  118. supplied by Christian Ludwig)
  119. High compression options are mostly useful for users, who
  120. are low on disk space (embedded systems), but for whom ram
  121. size matters less.
  122. If in doubt, select 'gzip'
  123. config KERNEL_GZIP
  124. bool "Gzip"
  125. depends on HAVE_KERNEL_GZIP
  126. help
  127. The old and tried gzip compression. It provides a good balance
  128. between compression ratio and decompression speed.
  129. config KERNEL_BZIP2
  130. bool "Bzip2"
  131. depends on HAVE_KERNEL_BZIP2
  132. help
  133. Its compression ratio and speed is intermediate.
  134. Decompression speed is slowest among the three. The kernel
  135. size is about 10% smaller with bzip2, in comparison to gzip.
  136. Bzip2 uses a large amount of memory. For modern kernels you
  137. will need at least 8MB RAM or more for booting.
  138. config KERNEL_LZMA
  139. bool "LZMA"
  140. depends on HAVE_KERNEL_LZMA
  141. help
  142. The most recent compression algorithm.
  143. Its ratio is best, decompression speed is between the other
  144. two. Compression is slowest. The kernel size is about 33%
  145. smaller with LZMA in comparison to gzip.
  146. config KERNEL_LZO
  147. bool "LZO"
  148. depends on HAVE_KERNEL_LZO
  149. help
  150. Its compression ratio is the poorest among the 4. The kernel
  151. size is about about 10% bigger than gzip; however its speed
  152. (both compression and decompression) is the fastest.
  153. endchoice
  154. config SWAP
  155. bool "Support for paging of anonymous memory (swap)"
  156. depends on MMU && BLOCK
  157. default y
  158. help
  159. This option allows you to choose whether you want to have support
  160. for so called swap devices or swap files in your kernel that are
  161. used to provide more virtual memory than the actual RAM present
  162. in your computer. If unsure say Y.
  163. config SYSVIPC
  164. bool "System V IPC"
  165. ---help---
  166. Inter Process Communication is a suite of library functions and
  167. system calls which let processes (running programs) synchronize and
  168. exchange information. It is generally considered to be a good thing,
  169. and some programs won't run unless you say Y here. In particular, if
  170. you want to run the DOS emulator dosemu under Linux (read the
  171. DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
  172. you'll need to say Y here.
  173. You can find documentation about IPC with "info ipc" and also in
  174. section 6.4 of the Linux Programmer's Guide, available from
  175. <http://www.tldp.org/guides.html>.
  176. config SYSVIPC_SYSCTL
  177. bool
  178. depends on SYSVIPC
  179. depends on SYSCTL
  180. default y
  181. config POSIX_MQUEUE
  182. bool "POSIX Message Queues"
  183. depends on NET && EXPERIMENTAL
  184. ---help---
  185. POSIX variant of message queues is a part of IPC. In POSIX message
  186. queues every message has a priority which decides about succession
  187. of receiving it by a process. If you want to compile and run
  188. programs written e.g. for Solaris with use of its POSIX message
  189. queues (functions mq_*) say Y here.
  190. POSIX message queues are visible as a filesystem called 'mqueue'
  191. and can be mounted somewhere if you want to do filesystem
  192. operations on message queues.
  193. If unsure, say Y.
  194. config POSIX_MQUEUE_SYSCTL
  195. bool
  196. depends on POSIX_MQUEUE
  197. depends on SYSCTL
  198. default y
  199. config BSD_PROCESS_ACCT
  200. bool "BSD Process Accounting"
  201. help
  202. If you say Y here, a user level program will be able to instruct the
  203. kernel (via a special system call) to write process accounting
  204. information to a file: whenever a process exits, information about
  205. that process will be appended to the file by the kernel. The
  206. information includes things such as creation time, owning user,
  207. command name, memory usage, controlling terminal etc. (the complete
  208. list is in the struct acct in <file:include/linux/acct.h>). It is
  209. up to the user level program to do useful things with this
  210. information. This is generally a good idea, so say Y.
  211. config BSD_PROCESS_ACCT_V3
  212. bool "BSD Process Accounting version 3 file format"
  213. depends on BSD_PROCESS_ACCT
  214. default n
  215. help
  216. If you say Y here, the process accounting information is written
  217. in a new file format that also logs the process IDs of each
  218. process and it's parent. Note that this file format is incompatible
  219. with previous v0/v1/v2 file formats, so you will need updated tools
  220. for processing it. A preliminary version of these tools is available
  221. at <http://www.gnu.org/software/acct/>.
  222. config TASKSTATS
  223. bool "Export task/process statistics through netlink (EXPERIMENTAL)"
  224. depends on NET
  225. default n
  226. help
  227. Export selected statistics for tasks/processes through the
  228. generic netlink interface. Unlike BSD process accounting, the
  229. statistics are available during the lifetime of tasks/processes as
  230. responses to commands. Like BSD accounting, they are sent to user
  231. space on task exit.
  232. Say N if unsure.
  233. config TASK_DELAY_ACCT
  234. bool "Enable per-task delay accounting (EXPERIMENTAL)"
  235. depends on TASKSTATS
  236. help
  237. Collect information on time spent by a task waiting for system
  238. resources like cpu, synchronous block I/O completion and swapping
  239. in pages. Such statistics can help in setting a task's priorities
  240. relative to other tasks for cpu, io, rss limits etc.
  241. Say N if unsure.
  242. config TASK_XACCT
  243. bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
  244. depends on TASKSTATS
  245. help
  246. Collect extended task accounting data and send the data
  247. to userland for processing over the taskstats interface.
  248. Say N if unsure.
  249. config TASK_IO_ACCOUNTING
  250. bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
  251. depends on TASK_XACCT
  252. help
  253. Collect information on the number of bytes of storage I/O which this
  254. task has caused.
  255. Say N if unsure.
  256. config AUDIT
  257. bool "Auditing support"
  258. depends on NET
  259. help
  260. Enable auditing infrastructure that can be used with another
  261. kernel subsystem, such as SELinux (which requires this for
  262. logging of avc messages output). Does not do system-call
  263. auditing without CONFIG_AUDITSYSCALL.
  264. config AUDITSYSCALL
  265. bool "Enable system-call auditing support"
  266. depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
  267. default y if SECURITY_SELINUX
  268. help
  269. Enable low-overhead system-call auditing infrastructure that
  270. can be used independently or with another kernel subsystem,
  271. such as SELinux. To use audit's filesystem watch feature, please
  272. ensure that INOTIFY is configured.
  273. config AUDIT_TREE
  274. def_bool y
  275. depends on AUDITSYSCALL
  276. select INOTIFY
  277. menu "RCU Subsystem"
  278. choice
  279. prompt "RCU Implementation"
  280. default TREE_RCU
  281. config TREE_RCU
  282. bool "Tree-based hierarchical RCU"
  283. help
  284. This option selects the RCU implementation that is
  285. designed for very large SMP system with hundreds or
  286. thousands of CPUs. It also scales down nicely to
  287. smaller systems.
  288. config TREE_PREEMPT_RCU
  289. bool "Preemptable tree-based hierarchical RCU"
  290. depends on PREEMPT
  291. help
  292. This option selects the RCU implementation that is
  293. designed for very large SMP systems with hundreds or
  294. thousands of CPUs, but for which real-time response
  295. is also required. It also scales down nicely to
  296. smaller systems.
  297. config TINY_RCU
  298. bool "UP-only small-memory-footprint RCU"
  299. depends on !SMP
  300. help
  301. This option selects the RCU implementation that is
  302. designed for UP systems from which real-time response
  303. is not required. This option greatly reduces the
  304. memory footprint of RCU.
  305. endchoice
  306. config RCU_TRACE
  307. bool "Enable tracing for RCU"
  308. depends on TREE_RCU || TREE_PREEMPT_RCU
  309. help
  310. This option provides tracing in RCU which presents stats
  311. in debugfs for debugging RCU implementation.
  312. Say Y here if you want to enable RCU tracing
  313. Say N if you are unsure.
  314. config RCU_FANOUT
  315. int "Tree-based hierarchical RCU fanout value"
  316. range 2 64 if 64BIT
  317. range 2 32 if !64BIT
  318. depends on TREE_RCU || TREE_PREEMPT_RCU
  319. default 64 if 64BIT
  320. default 32 if !64BIT
  321. help
  322. This option controls the fanout of hierarchical implementations
  323. of RCU, allowing RCU to work efficiently on machines with
  324. large numbers of CPUs. This value must be at least the cube
  325. root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
  326. systems and up to 262,144 for 64-bit systems.
  327. Select a specific number if testing RCU itself.
  328. Take the default if unsure.
  329. config RCU_FANOUT_EXACT
  330. bool "Disable tree-based hierarchical RCU auto-balancing"
  331. depends on TREE_RCU || TREE_PREEMPT_RCU
  332. default n
  333. help
  334. This option forces use of the exact RCU_FANOUT value specified,
  335. regardless of imbalances in the hierarchy. This is useful for
  336. testing RCU itself, and might one day be useful on systems with
  337. strong NUMA behavior.
  338. Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
  339. Say N if unsure.
  340. config TREE_RCU_TRACE
  341. def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
  342. select DEBUG_FS
  343. help
  344. This option provides tracing for the TREE_RCU and
  345. TREE_PREEMPT_RCU implementations, permitting Makefile to
  346. trivially select kernel/rcutree_trace.c.
  347. endmenu # "RCU Subsystem"
  348. config IKCONFIG
  349. tristate "Kernel .config support"
  350. ---help---
  351. This option enables the complete Linux kernel ".config" file
  352. contents to be saved in the kernel. It provides documentation
  353. of which kernel options are used in a running kernel or in an
  354. on-disk kernel. This information can be extracted from the kernel
  355. image file with the script scripts/extract-ikconfig and used as
  356. input to rebuild the current kernel or to build another kernel.
  357. It can also be extracted from a running kernel by reading
  358. /proc/config.gz if enabled (below).
  359. config IKCONFIG_PROC
  360. bool "Enable access to .config through /proc/config.gz"
  361. depends on IKCONFIG && PROC_FS
  362. ---help---
  363. This option enables access to the kernel configuration file
  364. through /proc/config.gz.
  365. config LOG_BUF_SHIFT
  366. int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
  367. range 12 21
  368. default 17
  369. help
  370. Select kernel log buffer size as a power of 2.
  371. Examples:
  372. 17 => 128 KB
  373. 16 => 64 KB
  374. 15 => 32 KB
  375. 14 => 16 KB
  376. 13 => 8 KB
  377. 12 => 4 KB
  378. #
  379. # Architectures with an unreliable sched_clock() should select this:
  380. #
  381. config HAVE_UNSTABLE_SCHED_CLOCK
  382. bool
  383. config GROUP_SCHED
  384. bool "Group CPU scheduler"
  385. depends on EXPERIMENTAL
  386. default n
  387. help
  388. This feature lets CPU scheduler recognize task groups and control CPU
  389. bandwidth allocation to such task groups.
  390. In order to create a group from arbitrary set of processes, use
  391. CONFIG_CGROUPS. (See Control Group support.)
  392. config FAIR_GROUP_SCHED
  393. bool "Group scheduling for SCHED_OTHER"
  394. depends on GROUP_SCHED
  395. default GROUP_SCHED
  396. config RT_GROUP_SCHED
  397. bool "Group scheduling for SCHED_RR/FIFO"
  398. depends on EXPERIMENTAL
  399. depends on GROUP_SCHED
  400. default n
  401. help
  402. This feature lets you explicitly allocate real CPU bandwidth
  403. to users or control groups (depending on the "Basis for grouping tasks"
  404. setting below. If enabled, it will also make it impossible to
  405. schedule realtime tasks for non-root users until you allocate
  406. realtime bandwidth for them.
  407. See Documentation/scheduler/sched-rt-group.txt for more information.
  408. choice
  409. depends on GROUP_SCHED
  410. prompt "Basis for grouping tasks"
  411. default USER_SCHED
  412. config USER_SCHED
  413. bool "user id"
  414. help
  415. This option will choose userid as the basis for grouping
  416. tasks, thus providing equal CPU bandwidth to each user.
  417. config CGROUP_SCHED
  418. bool "Control groups"
  419. depends on CGROUPS
  420. help
  421. This option allows you to create arbitrary task groups
  422. using the "cgroup" pseudo filesystem and control
  423. the cpu bandwidth allocated to each such task group.
  424. Refer to Documentation/cgroups/cgroups.txt for more
  425. information on "cgroup" pseudo filesystem.
  426. endchoice
  427. menuconfig CGROUPS
  428. boolean "Control Group support"
  429. help
  430. This option adds support for grouping sets of processes together, for
  431. use with process control subsystems such as Cpusets, CFS, memory
  432. controls or device isolation.
  433. See
  434. - Documentation/scheduler/sched-design-CFS.txt (CFS)
  435. - Documentation/cgroups/ (features for grouping, isolation
  436. and resource control)
  437. Say N if unsure.
  438. if CGROUPS
  439. config CGROUP_DEBUG
  440. bool "Example debug cgroup subsystem"
  441. depends on CGROUPS
  442. default n
  443. help
  444. This option enables a simple cgroup subsystem that
  445. exports useful debugging information about the cgroups
  446. framework.
  447. Say N if unsure.
  448. config CGROUP_NS
  449. bool "Namespace cgroup subsystem"
  450. depends on CGROUPS
  451. help
  452. Provides a simple namespace cgroup subsystem to
  453. provide hierarchical naming of sets of namespaces,
  454. for instance virtual servers and checkpoint/restart
  455. jobs.
  456. config CGROUP_FREEZER
  457. bool "Freezer cgroup subsystem"
  458. depends on CGROUPS
  459. help
  460. Provides a way to freeze and unfreeze all tasks in a
  461. cgroup.
  462. config CGROUP_DEVICE
  463. bool "Device controller for cgroups"
  464. depends on CGROUPS && EXPERIMENTAL
  465. help
  466. Provides a cgroup implementing whitelists for devices which
  467. a process in the cgroup can mknod or open.
  468. config CPUSETS
  469. bool "Cpuset support"
  470. depends on CGROUPS
  471. help
  472. This option will let you create and manage CPUSETs which
  473. allow dynamically partitioning a system into sets of CPUs and
  474. Memory Nodes and assigning tasks to run only within those sets.
  475. This is primarily useful on large SMP or NUMA systems.
  476. Say N if unsure.
  477. config PROC_PID_CPUSET
  478. bool "Include legacy /proc/<pid>/cpuset file"
  479. depends on CPUSETS
  480. default y
  481. config CGROUP_CPUACCT
  482. bool "Simple CPU accounting cgroup subsystem"
  483. depends on CGROUPS
  484. help
  485. Provides a simple Resource Controller for monitoring the
  486. total CPU consumed by the tasks in a cgroup.
  487. config RESOURCE_COUNTERS
  488. bool "Resource counters"
  489. help
  490. This option enables controller independent resource accounting
  491. infrastructure that works with cgroups.
  492. depends on CGROUPS
  493. config CGROUP_MEM_RES_CTLR
  494. bool "Memory Resource Controller for Control Groups"
  495. depends on CGROUPS && RESOURCE_COUNTERS
  496. select MM_OWNER
  497. help
  498. Provides a memory resource controller that manages both anonymous
  499. memory and page cache. (See Documentation/cgroups/memory.txt)
  500. Note that setting this option increases fixed memory overhead
  501. associated with each page of memory in the system. By this,
  502. 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
  503. usage tracking struct at boot. Total amount of this is printed out
  504. at boot.
  505. Only enable when you're ok with these trade offs and really
  506. sure you need the memory resource controller. Even when you enable
  507. this, you can set "cgroup_disable=memory" at your boot option to
  508. disable memory resource controller and you can avoid overheads.
  509. (and lose benefits of memory resource controller)
  510. This config option also selects MM_OWNER config option, which
  511. could in turn add some fork/exit overhead.
  512. config CGROUP_MEM_RES_CTLR_SWAP
  513. bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)"
  514. depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL
  515. help
  516. Add swap management feature to memory resource controller. When you
  517. enable this, you can limit mem+swap usage per cgroup. In other words,
  518. when you disable this, memory resource controller has no cares to
  519. usage of swap...a process can exhaust all of the swap. This extension
  520. is useful when you want to avoid exhaustion swap but this itself
  521. adds more overheads and consumes memory for remembering information.
  522. Especially if you use 32bit system or small memory system, please
  523. be careful about enabling this. When memory resource controller
  524. is disabled by boot option, this will be automatically disabled and
  525. there will be no overhead from this. Even when you set this config=y,
  526. if boot option "noswapaccount" is set, swap will not be accounted.
  527. Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
  528. size is 4096bytes, 512k per 1Gbytes of swap.
  529. endif # CGROUPS
  530. config MM_OWNER
  531. bool
  532. config SYSFS_DEPRECATED
  533. bool
  534. config SYSFS_DEPRECATED_V2
  535. bool "enable deprecated sysfs features to support old userspace tools"
  536. depends on SYSFS
  537. default n
  538. select SYSFS_DEPRECATED
  539. help
  540. This option switches the layout of sysfs to the deprecated
  541. version. Do not use it on recent distributions.
  542. The current sysfs layout features a unified device tree at
  543. /sys/devices/, which is able to express a hierarchy between
  544. class devices. If the deprecated option is set to Y, the
  545. unified device tree is split into a bus device tree at
  546. /sys/devices/ and several individual class device trees at
  547. /sys/class/. The class and bus devices will be connected by
  548. "<subsystem>:<name>" and the "device" links. The "block"
  549. class devices, will not show up in /sys/class/block/. Some
  550. subsystems will suppress the creation of some devices which
  551. depend on the unified device tree.
  552. This option is not a pure compatibility option that can
  553. be safely enabled on newer distributions. It will change the
  554. layout of sysfs to the non-extensible deprecated version,
  555. and disable some features, which can not be exported without
  556. confusing older userspace tools. Since 2007/2008 all major
  557. distributions do not enable this option, and ship no tools which
  558. depend on the deprecated layout or this option.
  559. If you are using a new kernel on an older distribution, or use
  560. older userspace tools, you might need to say Y here. Do not say Y,
  561. if the original kernel, that came with your distribution, has
  562. this option set to N.
  563. config RELAY
  564. bool "Kernel->user space relay support (formerly relayfs)"
  565. help
  566. This option enables support for relay interface support in
  567. certain file systems (such as debugfs).
  568. It is designed to provide an efficient mechanism for tools and
  569. facilities to relay large amounts of data from kernel space to
  570. user space.
  571. If unsure, say N.
  572. config NAMESPACES
  573. bool "Namespaces support" if EMBEDDED
  574. default !EMBEDDED
  575. help
  576. Provides the way to make tasks work with different objects using
  577. the same id. For example same IPC id may refer to different objects
  578. or same user id or pid may refer to different tasks when used in
  579. different namespaces.
  580. config UTS_NS
  581. bool "UTS namespace"
  582. depends on NAMESPACES
  583. help
  584. In this namespace tasks see different info provided with the
  585. uname() system call
  586. config IPC_NS
  587. bool "IPC namespace"
  588. depends on NAMESPACES && (SYSVIPC || POSIX_MQUEUE)
  589. help
  590. In this namespace tasks work with IPC ids which correspond to
  591. different IPC objects in different namespaces.
  592. config USER_NS
  593. bool "User namespace (EXPERIMENTAL)"
  594. depends on NAMESPACES && EXPERIMENTAL
  595. help
  596. This allows containers, i.e. vservers, to use user namespaces
  597. to provide different user info for different servers.
  598. If unsure, say N.
  599. config PID_NS
  600. bool "PID Namespaces (EXPERIMENTAL)"
  601. default n
  602. depends on NAMESPACES && EXPERIMENTAL
  603. help
  604. Support process id namespaces. This allows having multiple
  605. processes with the same pid as long as they are in different
  606. pid namespaces. This is a building block of containers.
  607. Unless you want to work with an experimental feature
  608. say N here.
  609. config NET_NS
  610. bool "Network namespace"
  611. default n
  612. depends on NAMESPACES && EXPERIMENTAL && NET
  613. help
  614. Allow user space to create what appear to be multiple instances
  615. of the network stack.
  616. config BLK_DEV_INITRD
  617. bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
  618. depends on BROKEN || !FRV
  619. help
  620. The initial RAM filesystem is a ramfs which is loaded by the
  621. boot loader (loadlin or lilo) and that is mounted as root
  622. before the normal boot procedure. It is typically used to
  623. load modules needed to mount the "real" root file system,
  624. etc. See <file:Documentation/initrd.txt> for details.
  625. If RAM disk support (BLK_DEV_RAM) is also included, this
  626. also enables initial RAM disk (initrd) support and adds
  627. 15 Kbytes (more on some other architectures) to the kernel size.
  628. If unsure say Y.
  629. if BLK_DEV_INITRD
  630. source "usr/Kconfig"
  631. endif
  632. config CC_OPTIMIZE_FOR_SIZE
  633. bool "Optimize for size"
  634. default y
  635. help
  636. Enabling this option will pass "-Os" instead of "-O2" to gcc
  637. resulting in a smaller kernel.
  638. If unsure, say Y.
  639. config SYSCTL
  640. bool
  641. config ANON_INODES
  642. bool
  643. menuconfig EMBEDDED
  644. bool "Configure standard kernel features (for small systems)"
  645. help
  646. This option allows certain base kernel options and settings
  647. to be disabled or tweaked. This is for specialized
  648. environments which can tolerate a "non-standard" kernel.
  649. Only use this if you really know what you are doing.
  650. config UID16
  651. bool "Enable 16-bit UID system calls" if EMBEDDED
  652. depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
  653. default y
  654. help
  655. This enables the legacy 16-bit UID syscall wrappers.
  656. config SYSCTL_SYSCALL
  657. bool "Sysctl syscall support" if EMBEDDED
  658. depends on PROC_SYSCTL
  659. default y
  660. select SYSCTL
  661. ---help---
  662. sys_sysctl uses binary paths that have been found challenging
  663. to properly maintain and use. The interface in /proc/sys
  664. using paths with ascii names is now the primary path to this
  665. information.
  666. Almost nothing using the binary sysctl interface so if you are
  667. trying to save some space it is probably safe to disable this,
  668. making your kernel marginally smaller.
  669. If unsure say Y here.
  670. config KALLSYMS
  671. bool "Load all symbols for debugging/ksymoops" if EMBEDDED
  672. default y
  673. help
  674. Say Y here to let the kernel print out symbolic crash information and
  675. symbolic stack backtraces. This increases the size of the kernel
  676. somewhat, as all symbols have to be loaded into the kernel image.
  677. config KALLSYMS_ALL
  678. bool "Include all symbols in kallsyms"
  679. depends on DEBUG_KERNEL && KALLSYMS
  680. help
  681. Normally kallsyms only contains the symbols of functions, for nicer
  682. OOPS messages. Some debuggers can use kallsyms for other
  683. symbols too: say Y here to include all symbols, if you need them
  684. and you don't care about adding 300k to the size of your kernel.
  685. Say N.
  686. config KALLSYMS_EXTRA_PASS
  687. bool "Do an extra kallsyms pass"
  688. depends on KALLSYMS
  689. help
  690. If kallsyms is not working correctly, the build will fail with
  691. inconsistent kallsyms data. If that occurs, log a bug report and
  692. turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
  693. Always say N here unless you find a bug in kallsyms, which must be
  694. reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
  695. you wait for kallsyms to be fixed.
  696. config HOTPLUG
  697. bool "Support for hot-pluggable devices" if EMBEDDED
  698. default y
  699. help
  700. This option is provided for the case where no hotplug or uevent
  701. capabilities is wanted by the kernel. You should only consider
  702. disabling this option for embedded systems that do not use modules, a
  703. dynamic /dev tree, or dynamic device discovery. Just say Y.
  704. config PRINTK
  705. default y
  706. bool "Enable support for printk" if EMBEDDED
  707. help
  708. This option enables normal printk support. Removing it
  709. eliminates most of the message strings from the kernel image
  710. and makes the kernel more or less silent. As this makes it
  711. very difficult to diagnose system problems, saying N here is
  712. strongly discouraged.
  713. config BUG
  714. bool "BUG() support" if EMBEDDED
  715. default y
  716. help
  717. Disabling this option eliminates support for BUG and WARN, reducing
  718. the size of your kernel image and potentially quietly ignoring
  719. numerous fatal conditions. You should only consider disabling this
  720. option for embedded systems with no facilities for reporting errors.
  721. Just say Y.
  722. config ELF_CORE
  723. default y
  724. bool "Enable ELF core dumps" if EMBEDDED
  725. help
  726. Enable support for generating core dumps. Disabling saves about 4k.
  727. config PCSPKR_PLATFORM
  728. bool "Enable PC-Speaker support" if EMBEDDED
  729. depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
  730. default y
  731. help
  732. This option allows to disable the internal PC-Speaker
  733. support, saving some memory.
  734. config BASE_FULL
  735. default y
  736. bool "Enable full-sized data structures for core" if EMBEDDED
  737. help
  738. Disabling this option reduces the size of miscellaneous core
  739. kernel data structures. This saves memory on small machines,
  740. but may reduce performance.
  741. config FUTEX
  742. bool "Enable futex support" if EMBEDDED
  743. default y
  744. select RT_MUTEXES
  745. help
  746. Disabling this option will cause the kernel to be built without
  747. support for "fast userspace mutexes". The resulting kernel may not
  748. run glibc-based applications correctly.
  749. config EPOLL
  750. bool "Enable eventpoll support" if EMBEDDED
  751. default y
  752. select ANON_INODES
  753. help
  754. Disabling this option will cause the kernel to be built without
  755. support for epoll family of system calls.
  756. config SIGNALFD
  757. bool "Enable signalfd() system call" if EMBEDDED
  758. select ANON_INODES
  759. default y
  760. help
  761. Enable the signalfd() system call that allows to receive signals
  762. on a file descriptor.
  763. If unsure, say Y.
  764. config TIMERFD
  765. bool "Enable timerfd() system call" if EMBEDDED
  766. select ANON_INODES
  767. default y
  768. help
  769. Enable the timerfd() system call that allows to receive timer
  770. events on a file descriptor.
  771. If unsure, say Y.
  772. config EVENTFD
  773. bool "Enable eventfd() system call" if EMBEDDED
  774. select ANON_INODES
  775. default y
  776. help
  777. Enable the eventfd() system call that allows to receive both
  778. kernel notification (ie. KAIO) or userspace notifications.
  779. If unsure, say Y.
  780. config SHMEM
  781. bool "Use full shmem filesystem" if EMBEDDED
  782. default y
  783. depends on MMU
  784. help
  785. The shmem is an internal filesystem used to manage shared memory.
  786. It is backed by swap and manages resource limits. It is also exported
  787. to userspace as tmpfs if TMPFS is enabled. Disabling this
  788. option replaces shmem and tmpfs with the much simpler ramfs code,
  789. which may be appropriate on small systems without swap.
  790. config AIO
  791. bool "Enable AIO support" if EMBEDDED
  792. default y
  793. help
  794. This option enables POSIX asynchronous I/O which may by used
  795. by some high performance threaded applications. Disabling
  796. this option saves about 7k.
  797. config HAVE_PERF_EVENTS
  798. bool
  799. help
  800. See tools/perf/design.txt for details.
  801. config PERF_USE_VMALLOC
  802. bool
  803. help
  804. See tools/perf/design.txt for details
  805. menu "Kernel Performance Events And Counters"
  806. config PERF_EVENTS
  807. bool "Kernel performance events and counters"
  808. default y if (PROFILING || PERF_COUNTERS)
  809. depends on HAVE_PERF_EVENTS
  810. select ANON_INODES
  811. help
  812. Enable kernel support for various performance events provided
  813. by software and hardware.
  814. Software events are supported either built-in or via the
  815. use of generic tracepoints.
  816. Most modern CPUs support performance events via performance
  817. counter registers. These registers count the number of certain
  818. types of hw events: such as instructions executed, cachemisses
  819. suffered, or branches mis-predicted - without slowing down the
  820. kernel or applications. These registers can also trigger interrupts
  821. when a threshold number of events have passed - and can thus be
  822. used to profile the code that runs on that CPU.
  823. The Linux Performance Event subsystem provides an abstraction of
  824. these software and hardware event capabilities, available via a
  825. system call and used by the "perf" utility in tools/perf/. It
  826. provides per task and per CPU counters, and it provides event
  827. capabilities on top of those.
  828. Say Y if unsure.
  829. config EVENT_PROFILE
  830. bool "Tracepoint profiling sources"
  831. depends on PERF_EVENTS && EVENT_TRACING
  832. default y
  833. help
  834. Allow the use of tracepoints as software performance events.
  835. When this is enabled, you can create perf events based on
  836. tracepoints using PERF_TYPE_TRACEPOINT and the tracepoint ID
  837. found in debugfs://tracing/events/*/*/id. (The -e/--events
  838. option to the perf tool can parse and interpret symbolic
  839. tracepoints, in the subsystem:tracepoint_name format.)
  840. config PERF_COUNTERS
  841. bool "Kernel performance counters (old config option)"
  842. depends on HAVE_PERF_EVENTS
  843. help
  844. This config has been obsoleted by the PERF_EVENTS
  845. config option - please see that one for details.
  846. It has no effect on the kernel whether you enable
  847. it or not, it is a compatibility placeholder.
  848. Say N if unsure.
  849. config DEBUG_PERF_USE_VMALLOC
  850. default n
  851. bool "Debug: use vmalloc to back perf mmap() buffers"
  852. depends on PERF_EVENTS && DEBUG_KERNEL
  853. select PERF_USE_VMALLOC
  854. help
  855. Use vmalloc memory to back perf mmap() buffers.
  856. Mostly useful for debugging the vmalloc code on platforms
  857. that don't require it.
  858. Say N if unsure.
  859. endmenu
  860. config VM_EVENT_COUNTERS
  861. default y
  862. bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
  863. help
  864. VM event counters are needed for event counts to be shown.
  865. This option allows the disabling of the VM event counters
  866. on EMBEDDED systems. /proc/vmstat will only show page counts
  867. if VM event counters are disabled.
  868. config PCI_QUIRKS
  869. default y
  870. bool "Enable PCI quirk workarounds" if EMBEDDED
  871. depends on PCI
  872. help
  873. This enables workarounds for various PCI chipset
  874. bugs/quirks. Disable this only if your target machine is
  875. unaffected by PCI quirks.
  876. config SLUB_DEBUG
  877. default y
  878. bool "Enable SLUB debugging support" if EMBEDDED
  879. depends on SLUB && SYSFS
  880. help
  881. SLUB has extensive debug support features. Disabling these can
  882. result in significant savings in code size. This also disables
  883. SLUB sysfs support. /sys/slab will not exist and there will be
  884. no support for cache validation etc.
  885. config COMPAT_BRK
  886. bool "Disable heap randomization"
  887. default y
  888. help
  889. Randomizing heap placement makes heap exploits harder, but it
  890. also breaks ancient binaries (including anything libc5 based).
  891. This option changes the bootup default to heap randomization
  892. disabled, and can be overridden at runtime by setting
  893. /proc/sys/kernel/randomize_va_space to 2.
  894. On non-ancient distros (post-2000 ones) N is usually a safe choice.
  895. choice
  896. prompt "Choose SLAB allocator"
  897. default SLUB
  898. help
  899. This option allows to select a slab allocator.
  900. config SLAB
  901. bool "SLAB"
  902. help
  903. The regular slab allocator that is established and known to work
  904. well in all environments. It organizes cache hot objects in
  905. per cpu and per node queues.
  906. config SLUB
  907. bool "SLUB (Unqueued Allocator)"
  908. help
  909. SLUB is a slab allocator that minimizes cache line usage
  910. instead of managing queues of cached objects (SLAB approach).
  911. Per cpu caching is realized using slabs of objects instead
  912. of queues of objects. SLUB can use memory efficiently
  913. and has enhanced diagnostics. SLUB is the default choice for
  914. a slab allocator.
  915. config SLOB
  916. depends on EMBEDDED
  917. bool "SLOB (Simple Allocator)"
  918. help
  919. SLOB replaces the stock allocator with a drastically simpler
  920. allocator. SLOB is generally more space efficient but
  921. does not perform as well on large systems.
  922. endchoice
  923. config MMAP_ALLOW_UNINITIALIZED
  924. bool "Allow mmapped anonymous memory to be uninitialized"
  925. depends on EMBEDDED && !MMU
  926. default n
  927. help
  928. Normally, and according to the Linux spec, anonymous memory obtained
  929. from mmap() has it's contents cleared before it is passed to
  930. userspace. Enabling this config option allows you to request that
  931. mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
  932. providing a huge performance boost. If this option is not enabled,
  933. then the flag will be ignored.
  934. This is taken advantage of by uClibc's malloc(), and also by
  935. ELF-FDPIC binfmt's brk and stack allocator.
  936. Because of the obvious security issues, this option should only be
  937. enabled on embedded devices where you control what is run in
  938. userspace. Since that isn't generally a problem on no-MMU systems,
  939. it is normally safe to say Y here.
  940. See Documentation/nommu-mmap.txt for more information.
  941. config PROFILING
  942. bool "Profiling support (EXPERIMENTAL)"
  943. help
  944. Say Y here to enable the extended profiling support mechanisms used
  945. by profilers such as OProfile.
  946. #
  947. # Place an empty function call at each tracepoint site. Can be
  948. # dynamically changed for a probe function.
  949. #
  950. config TRACEPOINTS
  951. bool
  952. source "arch/Kconfig"
  953. config SLOW_WORK
  954. default n
  955. bool
  956. help
  957. The slow work thread pool provides a number of dynamically allocated
  958. threads that can be used by the kernel to perform operations that
  959. take a relatively long time.
  960. An example of this would be CacheFiles doing a path lookup followed
  961. by a series of mkdirs and a create call, all of which have to touch
  962. disk.
  963. See Documentation/slow-work.txt.
  964. config SLOW_WORK_DEBUG
  965. bool "Slow work debugging through debugfs"
  966. default n
  967. depends on SLOW_WORK && DEBUG_FS
  968. help
  969. Display the contents of the slow work run queue through debugfs,
  970. including items currently executing.
  971. See Documentation/slow-work.txt.
  972. endmenu # General setup
  973. config HAVE_GENERIC_DMA_COHERENT
  974. bool
  975. default n
  976. config SLABINFO
  977. bool
  978. depends on PROC_FS
  979. depends on SLAB || SLUB_DEBUG
  980. default y
  981. config RT_MUTEXES
  982. boolean
  983. config BASE_SMALL
  984. int
  985. default 0 if BASE_FULL
  986. default 1 if !BASE_FULL
  987. menuconfig MODULES
  988. bool "Enable loadable module support"
  989. help
  990. Kernel modules are small pieces of compiled code which can
  991. be inserted in the running kernel, rather than being
  992. permanently built into the kernel. You use the "modprobe"
  993. tool to add (and sometimes remove) them. If you say Y here,
  994. many parts of the kernel can be built as modules (by
  995. answering M instead of Y where indicated): this is most
  996. useful for infrequently used options which are not required
  997. for booting. For more information, see the man pages for
  998. modprobe, lsmod, modinfo, insmod and rmmod.
  999. If you say Y here, you will need to run "make
  1000. modules_install" to put the modules under /lib/modules/
  1001. where modprobe can find them (you may need to be root to do
  1002. this).
  1003. If unsure, say Y.
  1004. if MODULES
  1005. config MODULE_FORCE_LOAD
  1006. bool "Forced module loading"
  1007. default n
  1008. help
  1009. Allow loading of modules without version information (ie. modprobe
  1010. --force). Forced module loading sets the 'F' (forced) taint flag and
  1011. is usually a really bad idea.
  1012. config MODULE_UNLOAD
  1013. bool "Module unloading"
  1014. help
  1015. Without this option you will not be able to unload any
  1016. modules (note that some modules may not be unloadable
  1017. anyway), which makes your kernel smaller, faster
  1018. and simpler. If unsure, say Y.
  1019. config MODULE_FORCE_UNLOAD
  1020. bool "Forced module unloading"
  1021. depends on MODULE_UNLOAD && EXPERIMENTAL
  1022. help
  1023. This option allows you to force a module to unload, even if the
  1024. kernel believes it is unsafe: the kernel will remove the module
  1025. without waiting for anyone to stop using it (using the -f option to
  1026. rmmod). This is mainly for kernel developers and desperate users.
  1027. If unsure, say N.
  1028. config MODVERSIONS
  1029. bool "Module versioning support"
  1030. help
  1031. Usually, you have to use modules compiled with your kernel.
  1032. Saying Y here makes it sometimes possible to use modules
  1033. compiled for different kernels, by adding enough information
  1034. to the modules to (hopefully) spot any changes which would
  1035. make them incompatible with the kernel you are running. If
  1036. unsure, say N.
  1037. config MODULE_SRCVERSION_ALL
  1038. bool "Source checksum for all modules"
  1039. help
  1040. Modules which contain a MODULE_VERSION get an extra "srcversion"
  1041. field inserted into their modinfo section, which contains a
  1042. sum of the source files which made it. This helps maintainers
  1043. see exactly which source was used to build a module (since
  1044. others sometimes change the module source without updating
  1045. the version). With this option, such a "srcversion" field
  1046. will be created for all modules. If unsure, say N.
  1047. endif # MODULES
  1048. config INIT_ALL_POSSIBLE
  1049. bool
  1050. help
  1051. Back when each arch used to define their own cpu_online_map and
  1052. cpu_possible_map, some of them chose to initialize cpu_possible_map
  1053. with all 1s, and others with all 0s. When they were centralised,
  1054. it was better to provide this option than to break all the archs
  1055. and have several arch maintainers pursuing me down dark alleys.
  1056. config STOP_MACHINE
  1057. bool
  1058. default y
  1059. depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
  1060. help
  1061. Need stop_machine() primitive.
  1062. source "block/Kconfig"
  1063. config PREEMPT_NOTIFIERS
  1064. bool
  1065. source "kernel/Kconfig.locks"