Kconfig 44 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. config HAVE_IRQ_WORK
  21. bool
  22. config IRQ_WORK
  23. bool
  24. depends on HAVE_IRQ_WORK
  25. menu "General setup"
  26. config EXPERIMENTAL
  27. bool "Prompt for development and/or incomplete code/drivers"
  28. ---help---
  29. Some of the various things that Linux supports (such as network
  30. drivers, file systems, network protocols, etc.) can be in a state
  31. of development where the functionality, stability, or the level of
  32. testing is not yet high enough for general use. This is usually
  33. known as the "alpha-test" phase among developers. If a feature is
  34. currently in alpha-test, then the developers usually discourage
  35. uninformed widespread use of this feature by the general public to
  36. avoid "Why doesn't this work?" type mail messages. However, active
  37. testing and use of these systems is welcomed. Just be aware that it
  38. may not meet the normal level of reliability or it may fail to work
  39. in some special cases. Detailed bug reports from people familiar
  40. with the kernel internals are usually welcomed by the developers
  41. (before submitting bug reports, please read the documents
  42. <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
  43. <file:Documentation/BUG-HUNTING>, and
  44. <file:Documentation/oops-tracing.txt> in the kernel source).
  45. This option will also make obsoleted drivers available. These are
  46. drivers that have been replaced by something else, and/or are
  47. scheduled to be removed in a future kernel release.
  48. Unless you intend to help test and develop a feature or driver that
  49. falls into this category, or you have a situation that requires
  50. using these features, you should probably say N here, which will
  51. cause the configurator to present you with fewer choices. If
  52. you say Y here, you will be offered the choice of using features or
  53. drivers that are currently considered to be in the alpha-test phase.
  54. config BROKEN
  55. bool
  56. config BROKEN_ON_SMP
  57. bool
  58. depends on BROKEN || !SMP
  59. default y
  60. config INIT_ENV_ARG_LIMIT
  61. int
  62. default 32 if !UML
  63. default 128 if UML
  64. help
  65. Maximum of each of the number of arguments and environment
  66. variables passed to init from the kernel command line.
  67. config CROSS_COMPILE
  68. string "Cross-compiler tool prefix"
  69. help
  70. Same as running 'make CROSS_COMPILE=prefix-' but stored for
  71. default make runs in this kernel build directory. You don't
  72. need to set this unless you want the configured kernel build
  73. directory to select the cross-compiler automatically.
  74. config LOCALVERSION
  75. string "Local version - append to kernel release"
  76. help
  77. Append an extra string to the end of your kernel version.
  78. This will show up when you type uname, for example.
  79. The string you set here will be appended after the contents of
  80. any files with a filename matching localversion* in your
  81. object and source tree, in that order. Your total string can
  82. be a maximum of 64 characters.
  83. config LOCALVERSION_AUTO
  84. bool "Automatically append version information to the version string"
  85. default y
  86. help
  87. This will try to automatically determine if the current tree is a
  88. release tree by looking for git tags that belong to the current
  89. top of tree revision.
  90. A string of the format -gxxxxxxxx will be added to the localversion
  91. if a git-based tree is found. The string generated by this will be
  92. appended after any matching localversion* files, and after the value
  93. set in CONFIG_LOCALVERSION.
  94. (The actual string used here is the first eight characters produced
  95. by running the command:
  96. $ git rev-parse --verify HEAD
  97. which is done within the script "scripts/setlocalversion".)
  98. config HAVE_KERNEL_GZIP
  99. bool
  100. config HAVE_KERNEL_BZIP2
  101. bool
  102. config HAVE_KERNEL_LZMA
  103. bool
  104. config HAVE_KERNEL_XZ
  105. bool
  106. config HAVE_KERNEL_LZO
  107. bool
  108. choice
  109. prompt "Kernel compression mode"
  110. default KERNEL_GZIP
  111. depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
  112. help
  113. The linux kernel is a kind of self-extracting executable.
  114. Several compression algorithms are available, which differ
  115. in efficiency, compression and decompression speed.
  116. Compression speed is only relevant when building a kernel.
  117. Decompression speed is relevant at each boot.
  118. If you have any problems with bzip2 or lzma compressed
  119. kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
  120. version of this functionality (bzip2 only), for 2.4, was
  121. supplied by Christian Ludwig)
  122. High compression options are mostly useful for users, who
  123. are low on disk space (embedded systems), but for whom ram
  124. size matters less.
  125. If in doubt, select 'gzip'
  126. config KERNEL_GZIP
  127. bool "Gzip"
  128. depends on HAVE_KERNEL_GZIP
  129. help
  130. The old and tried gzip compression. It provides a good balance
  131. between compression ratio and decompression speed.
  132. config KERNEL_BZIP2
  133. bool "Bzip2"
  134. depends on HAVE_KERNEL_BZIP2
  135. help
  136. Its compression ratio and speed is intermediate.
  137. Decompression speed is slowest among the three. The kernel
  138. size is about 10% smaller with bzip2, in comparison to gzip.
  139. Bzip2 uses a large amount of memory. For modern kernels you
  140. will need at least 8MB RAM or more for booting.
  141. config KERNEL_LZMA
  142. bool "LZMA"
  143. depends on HAVE_KERNEL_LZMA
  144. help
  145. The most recent compression algorithm.
  146. Its ratio is best, decompression speed is between the other
  147. two. Compression is slowest. The kernel size is about 33%
  148. smaller with LZMA in comparison to gzip.
  149. config KERNEL_XZ
  150. bool "XZ"
  151. depends on HAVE_KERNEL_XZ
  152. help
  153. XZ uses the LZMA2 algorithm and instruction set specific
  154. BCJ filters which can improve compression ratio of executable
  155. code. The size of the kernel is about 30% smaller with XZ in
  156. comparison to gzip. On architectures for which there is a BCJ
  157. filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
  158. will create a few percent smaller kernel than plain LZMA.
  159. The speed is about the same as with LZMA: The decompression
  160. speed of XZ is better than that of bzip2 but worse than gzip
  161. and LZO. Compression is slow.
  162. config KERNEL_LZO
  163. bool "LZO"
  164. depends on HAVE_KERNEL_LZO
  165. help
  166. Its compression ratio is the poorest among the 4. The kernel
  167. size is about 10% bigger than gzip; however its speed
  168. (both compression and decompression) is the fastest.
  169. endchoice
  170. config DEFAULT_HOSTNAME
  171. string "Default hostname"
  172. default "(none)"
  173. help
  174. This option determines the default system hostname before userspace
  175. calls sethostname(2). The kernel traditionally uses "(none)" here,
  176. but you may wish to use a different default here to make a minimal
  177. system more usable with less configuration.
  178. config SWAP
  179. bool "Support for paging of anonymous memory (swap)"
  180. depends on MMU && BLOCK
  181. default y
  182. help
  183. This option allows you to choose whether you want to have support
  184. for so called swap devices or swap files in your kernel that are
  185. used to provide more virtual memory than the actual RAM present
  186. in your computer. If unsure say Y.
  187. config SYSVIPC
  188. bool "System V IPC"
  189. ---help---
  190. Inter Process Communication is a suite of library functions and
  191. system calls which let processes (running programs) synchronize and
  192. exchange information. It is generally considered to be a good thing,
  193. and some programs won't run unless you say Y here. In particular, if
  194. you want to run the DOS emulator dosemu under Linux (read the
  195. DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
  196. you'll need to say Y here.
  197. You can find documentation about IPC with "info ipc" and also in
  198. section 6.4 of the Linux Programmer's Guide, available from
  199. <http://www.tldp.org/guides.html>.
  200. config SYSVIPC_SYSCTL
  201. bool
  202. depends on SYSVIPC
  203. depends on SYSCTL
  204. default y
  205. config POSIX_MQUEUE
  206. bool "POSIX Message Queues"
  207. depends on NET && EXPERIMENTAL
  208. ---help---
  209. POSIX variant of message queues is a part of IPC. In POSIX message
  210. queues every message has a priority which decides about succession
  211. of receiving it by a process. If you want to compile and run
  212. programs written e.g. for Solaris with use of its POSIX message
  213. queues (functions mq_*) say Y here.
  214. POSIX message queues are visible as a filesystem called 'mqueue'
  215. and can be mounted somewhere if you want to do filesystem
  216. operations on message queues.
  217. If unsure, say Y.
  218. config POSIX_MQUEUE_SYSCTL
  219. bool
  220. depends on POSIX_MQUEUE
  221. depends on SYSCTL
  222. default y
  223. config BSD_PROCESS_ACCT
  224. bool "BSD Process Accounting"
  225. help
  226. If you say Y here, a user level program will be able to instruct the
  227. kernel (via a special system call) to write process accounting
  228. information to a file: whenever a process exits, information about
  229. that process will be appended to the file by the kernel. The
  230. information includes things such as creation time, owning user,
  231. command name, memory usage, controlling terminal etc. (the complete
  232. list is in the struct acct in <file:include/linux/acct.h>). It is
  233. up to the user level program to do useful things with this
  234. information. This is generally a good idea, so say Y.
  235. config BSD_PROCESS_ACCT_V3
  236. bool "BSD Process Accounting version 3 file format"
  237. depends on BSD_PROCESS_ACCT
  238. default n
  239. help
  240. If you say Y here, the process accounting information is written
  241. in a new file format that also logs the process IDs of each
  242. process and it's parent. Note that this file format is incompatible
  243. with previous v0/v1/v2 file formats, so you will need updated tools
  244. for processing it. A preliminary version of these tools is available
  245. at <http://www.gnu.org/software/acct/>.
  246. config FHANDLE
  247. bool "open by fhandle syscalls"
  248. select EXPORTFS
  249. help
  250. If you say Y here, a user level program will be able to map
  251. file names to handle and then later use the handle for
  252. different file system operations. This is useful in implementing
  253. userspace file servers, which now track files using handles instead
  254. of names. The handle would remain the same even if file names
  255. get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
  256. syscalls.
  257. config TASKSTATS
  258. bool "Export task/process statistics through netlink (EXPERIMENTAL)"
  259. depends on NET
  260. default n
  261. help
  262. Export selected statistics for tasks/processes through the
  263. generic netlink interface. Unlike BSD process accounting, the
  264. statistics are available during the lifetime of tasks/processes as
  265. responses to commands. Like BSD accounting, they are sent to user
  266. space on task exit.
  267. Say N if unsure.
  268. config TASK_DELAY_ACCT
  269. bool "Enable per-task delay accounting (EXPERIMENTAL)"
  270. depends on TASKSTATS
  271. help
  272. Collect information on time spent by a task waiting for system
  273. resources like cpu, synchronous block I/O completion and swapping
  274. in pages. Such statistics can help in setting a task's priorities
  275. relative to other tasks for cpu, io, rss limits etc.
  276. Say N if unsure.
  277. config TASK_XACCT
  278. bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
  279. depends on TASKSTATS
  280. help
  281. Collect extended task accounting data and send the data
  282. to userland for processing over the taskstats interface.
  283. Say N if unsure.
  284. config TASK_IO_ACCOUNTING
  285. bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
  286. depends on TASK_XACCT
  287. help
  288. Collect information on the number of bytes of storage I/O which this
  289. task has caused.
  290. Say N if unsure.
  291. config AUDIT
  292. bool "Auditing support"
  293. depends on NET
  294. help
  295. Enable auditing infrastructure that can be used with another
  296. kernel subsystem, such as SELinux (which requires this for
  297. logging of avc messages output). Does not do system-call
  298. auditing without CONFIG_AUDITSYSCALL.
  299. config AUDITSYSCALL
  300. bool "Enable system-call auditing support"
  301. depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
  302. default y if SECURITY_SELINUX
  303. help
  304. Enable low-overhead system-call auditing infrastructure that
  305. can be used independently or with another kernel subsystem,
  306. such as SELinux.
  307. config AUDIT_WATCH
  308. def_bool y
  309. depends on AUDITSYSCALL
  310. select FSNOTIFY
  311. config AUDIT_TREE
  312. def_bool y
  313. depends on AUDITSYSCALL
  314. select FSNOTIFY
  315. source "kernel/irq/Kconfig"
  316. menu "RCU Subsystem"
  317. choice
  318. prompt "RCU Implementation"
  319. default TREE_RCU
  320. config TREE_RCU
  321. bool "Tree-based hierarchical RCU"
  322. depends on !PREEMPT && SMP
  323. help
  324. This option selects the RCU implementation that is
  325. designed for very large SMP system with hundreds or
  326. thousands of CPUs. It also scales down nicely to
  327. smaller systems.
  328. config TREE_PREEMPT_RCU
  329. bool "Preemptible tree-based hierarchical RCU"
  330. depends on PREEMPT
  331. help
  332. This option selects the RCU implementation that is
  333. designed for very large SMP systems with hundreds or
  334. thousands of CPUs, but for which real-time response
  335. is also required. It also scales down nicely to
  336. smaller systems.
  337. config TINY_RCU
  338. bool "UP-only small-memory-footprint RCU"
  339. depends on !SMP
  340. help
  341. This option selects the RCU implementation that is
  342. designed for UP systems from which real-time response
  343. is not required. This option greatly reduces the
  344. memory footprint of RCU.
  345. config TINY_PREEMPT_RCU
  346. bool "Preemptible UP-only small-memory-footprint RCU"
  347. depends on !SMP && PREEMPT
  348. help
  349. This option selects the RCU implementation that is designed
  350. for real-time UP systems. This option greatly reduces the
  351. memory footprint of RCU.
  352. endchoice
  353. config PREEMPT_RCU
  354. def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
  355. help
  356. This option enables preemptible-RCU code that is common between
  357. the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
  358. config RCU_TRACE
  359. bool "Enable tracing for RCU"
  360. help
  361. This option provides tracing in RCU which presents stats
  362. in debugfs for debugging RCU implementation.
  363. Say Y here if you want to enable RCU tracing
  364. Say N if you are unsure.
  365. config RCU_FANOUT
  366. int "Tree-based hierarchical RCU fanout value"
  367. range 2 64 if 64BIT
  368. range 2 32 if !64BIT
  369. depends on TREE_RCU || TREE_PREEMPT_RCU
  370. default 64 if 64BIT
  371. default 32 if !64BIT
  372. help
  373. This option controls the fanout of hierarchical implementations
  374. of RCU, allowing RCU to work efficiently on machines with
  375. large numbers of CPUs. This value must be at least the fourth
  376. root of NR_CPUS, which allows NR_CPUS to be insanely large.
  377. The default value of RCU_FANOUT should be used for production
  378. systems, but if you are stress-testing the RCU implementation
  379. itself, small RCU_FANOUT values allow you to test large-system
  380. code paths on small(er) systems.
  381. Select a specific number if testing RCU itself.
  382. Take the default if unsure.
  383. config RCU_FANOUT_EXACT
  384. bool "Disable tree-based hierarchical RCU auto-balancing"
  385. depends on TREE_RCU || TREE_PREEMPT_RCU
  386. default n
  387. help
  388. This option forces use of the exact RCU_FANOUT value specified,
  389. regardless of imbalances in the hierarchy. This is useful for
  390. testing RCU itself, and might one day be useful on systems with
  391. strong NUMA behavior.
  392. Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
  393. Say N if unsure.
  394. config RCU_FAST_NO_HZ
  395. bool "Accelerate last non-dyntick-idle CPU's grace periods"
  396. depends on TREE_RCU && NO_HZ && SMP
  397. default n
  398. help
  399. This option causes RCU to attempt to accelerate grace periods
  400. in order to allow the final CPU to enter dynticks-idle state
  401. more quickly. On the other hand, this option increases the
  402. overhead of the dynticks-idle checking, particularly on systems
  403. with large numbers of CPUs.
  404. Say Y if energy efficiency is critically important, particularly
  405. if you have relatively few CPUs.
  406. Say N if you are unsure.
  407. config TREE_RCU_TRACE
  408. def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
  409. select DEBUG_FS
  410. help
  411. This option provides tracing for the TREE_RCU and
  412. TREE_PREEMPT_RCU implementations, permitting Makefile to
  413. trivially select kernel/rcutree_trace.c.
  414. config RCU_BOOST
  415. bool "Enable RCU priority boosting"
  416. depends on RT_MUTEXES && PREEMPT_RCU
  417. default n
  418. help
  419. This option boosts the priority of preempted RCU readers that
  420. block the current preemptible RCU grace period for too long.
  421. This option also prevents heavy loads from blocking RCU
  422. callback invocation for all flavors of RCU.
  423. Say Y here if you are working with real-time apps or heavy loads
  424. Say N here if you are unsure.
  425. config RCU_BOOST_PRIO
  426. int "Real-time priority to boost RCU readers to"
  427. range 1 99
  428. depends on RCU_BOOST
  429. default 1
  430. help
  431. This option specifies the real-time priority to which preempted
  432. RCU readers are to be boosted. If you are working with CPU-bound
  433. real-time applications, you should specify a priority higher then
  434. the highest-priority CPU-bound application.
  435. Specify the real-time priority, or take the default if unsure.
  436. config RCU_BOOST_DELAY
  437. int "Milliseconds to delay boosting after RCU grace-period start"
  438. range 0 3000
  439. depends on RCU_BOOST
  440. default 500
  441. help
  442. This option specifies the time to wait after the beginning of
  443. a given grace period before priority-boosting preempted RCU
  444. readers blocking that grace period. Note that any RCU reader
  445. blocking an expedited RCU grace period is boosted immediately.
  446. Accept the default if unsure.
  447. endmenu # "RCU Subsystem"
  448. config IKCONFIG
  449. tristate "Kernel .config support"
  450. ---help---
  451. This option enables the complete Linux kernel ".config" file
  452. contents to be saved in the kernel. It provides documentation
  453. of which kernel options are used in a running kernel or in an
  454. on-disk kernel. This information can be extracted from the kernel
  455. image file with the script scripts/extract-ikconfig and used as
  456. input to rebuild the current kernel or to build another kernel.
  457. It can also be extracted from a running kernel by reading
  458. /proc/config.gz if enabled (below).
  459. config IKCONFIG_PROC
  460. bool "Enable access to .config through /proc/config.gz"
  461. depends on IKCONFIG && PROC_FS
  462. ---help---
  463. This option enables access to the kernel configuration file
  464. through /proc/config.gz.
  465. config LOG_BUF_SHIFT
  466. int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
  467. range 12 21
  468. default 17
  469. help
  470. Select kernel log buffer size as a power of 2.
  471. Examples:
  472. 17 => 128 KB
  473. 16 => 64 KB
  474. 15 => 32 KB
  475. 14 => 16 KB
  476. 13 => 8 KB
  477. 12 => 4 KB
  478. #
  479. # Architectures with an unreliable sched_clock() should select this:
  480. #
  481. config HAVE_UNSTABLE_SCHED_CLOCK
  482. bool
  483. menuconfig CGROUPS
  484. boolean "Control Group support"
  485. depends on EVENTFD
  486. help
  487. This option adds support for grouping sets of processes together, for
  488. use with process control subsystems such as Cpusets, CFS, memory
  489. controls or device isolation.
  490. See
  491. - Documentation/scheduler/sched-design-CFS.txt (CFS)
  492. - Documentation/cgroups/ (features for grouping, isolation
  493. and resource control)
  494. Say N if unsure.
  495. if CGROUPS
  496. config CGROUP_DEBUG
  497. bool "Example debug cgroup subsystem"
  498. default n
  499. help
  500. This option enables a simple cgroup subsystem that
  501. exports useful debugging information about the cgroups
  502. framework.
  503. Say N if unsure.
  504. config CGROUP_FREEZER
  505. bool "Freezer cgroup subsystem"
  506. help
  507. Provides a way to freeze and unfreeze all tasks in a
  508. cgroup.
  509. config CGROUP_DEVICE
  510. bool "Device controller for cgroups"
  511. help
  512. Provides a cgroup implementing whitelists for devices which
  513. a process in the cgroup can mknod or open.
  514. config CPUSETS
  515. bool "Cpuset support"
  516. help
  517. This option will let you create and manage CPUSETs which
  518. allow dynamically partitioning a system into sets of CPUs and
  519. Memory Nodes and assigning tasks to run only within those sets.
  520. This is primarily useful on large SMP or NUMA systems.
  521. Say N if unsure.
  522. config PROC_PID_CPUSET
  523. bool "Include legacy /proc/<pid>/cpuset file"
  524. depends on CPUSETS
  525. default y
  526. config CGROUP_CPUACCT
  527. bool "Simple CPU accounting cgroup subsystem"
  528. help
  529. Provides a simple Resource Controller for monitoring the
  530. total CPU consumed by the tasks in a cgroup.
  531. config RESOURCE_COUNTERS
  532. bool "Resource counters"
  533. help
  534. This option enables controller independent resource accounting
  535. infrastructure that works with cgroups.
  536. config CGROUP_MEM_RES_CTLR
  537. bool "Memory Resource Controller for Control Groups"
  538. depends on RESOURCE_COUNTERS
  539. select MM_OWNER
  540. help
  541. Provides a memory resource controller that manages both anonymous
  542. memory and page cache. (See Documentation/cgroups/memory.txt)
  543. Note that setting this option increases fixed memory overhead
  544. associated with each page of memory in the system. By this,
  545. 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
  546. usage tracking struct at boot. Total amount of this is printed out
  547. at boot.
  548. Only enable when you're ok with these trade offs and really
  549. sure you need the memory resource controller. Even when you enable
  550. this, you can set "cgroup_disable=memory" at your boot option to
  551. disable memory resource controller and you can avoid overheads.
  552. (and lose benefits of memory resource controller)
  553. This config option also selects MM_OWNER config option, which
  554. could in turn add some fork/exit overhead.
  555. config CGROUP_MEM_RES_CTLR_SWAP
  556. bool "Memory Resource Controller Swap Extension"
  557. depends on CGROUP_MEM_RES_CTLR && SWAP
  558. help
  559. Add swap management feature to memory resource controller. When you
  560. enable this, you can limit mem+swap usage per cgroup. In other words,
  561. when you disable this, memory resource controller has no cares to
  562. usage of swap...a process can exhaust all of the swap. This extension
  563. is useful when you want to avoid exhaustion swap but this itself
  564. adds more overheads and consumes memory for remembering information.
  565. Especially if you use 32bit system or small memory system, please
  566. be careful about enabling this. When memory resource controller
  567. is disabled by boot option, this will be automatically disabled and
  568. there will be no overhead from this. Even when you set this config=y,
  569. if boot option "noswapaccount" is set, swap will not be accounted.
  570. Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
  571. size is 4096bytes, 512k per 1Gbytes of swap.
  572. config CGROUP_MEM_RES_CTLR_SWAP_ENABLED
  573. bool "Memory Resource Controller Swap Extension enabled by default"
  574. depends on CGROUP_MEM_RES_CTLR_SWAP
  575. default y
  576. help
  577. Memory Resource Controller Swap Extension comes with its price in
  578. a bigger memory consumption. General purpose distribution kernels
  579. which want to enable the feature but keep it disabled by default
  580. and let the user enable it by swapaccount boot command line
  581. parameter should have this option unselected.
  582. For those who want to have the feature enabled by default should
  583. select this option (if, for some reason, they need to disable it
  584. then noswapaccount does the trick).
  585. config CGROUP_PERF
  586. bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
  587. depends on PERF_EVENTS && CGROUPS
  588. help
  589. This option extends the per-cpu mode to restrict monitoring to
  590. threads which belong to the cgroup specified and run on the
  591. designated cpu.
  592. Say N if unsure.
  593. menuconfig CGROUP_SCHED
  594. bool "Group CPU scheduler"
  595. depends on EXPERIMENTAL
  596. default n
  597. help
  598. This feature lets CPU scheduler recognize task groups and control CPU
  599. bandwidth allocation to such task groups. It uses cgroups to group
  600. tasks.
  601. if CGROUP_SCHED
  602. config FAIR_GROUP_SCHED
  603. bool "Group scheduling for SCHED_OTHER"
  604. depends on CGROUP_SCHED
  605. default CGROUP_SCHED
  606. config RT_GROUP_SCHED
  607. bool "Group scheduling for SCHED_RR/FIFO"
  608. depends on EXPERIMENTAL
  609. depends on CGROUP_SCHED
  610. default n
  611. help
  612. This feature lets you explicitly allocate real CPU bandwidth
  613. to task groups. If enabled, it will also make it impossible to
  614. schedule realtime tasks for non-root users until you allocate
  615. realtime bandwidth for them.
  616. See Documentation/scheduler/sched-rt-group.txt for more information.
  617. endif #CGROUP_SCHED
  618. config BLK_CGROUP
  619. tristate "Block IO controller"
  620. depends on BLOCK
  621. default n
  622. ---help---
  623. Generic block IO controller cgroup interface. This is the common
  624. cgroup interface which should be used by various IO controlling
  625. policies.
  626. Currently, CFQ IO scheduler uses it to recognize task groups and
  627. control disk bandwidth allocation (proportional time slice allocation)
  628. to such task groups. It is also used by bio throttling logic in
  629. block layer to implement upper limit in IO rates on a device.
  630. This option only enables generic Block IO controller infrastructure.
  631. One needs to also enable actual IO controlling logic/policy. For
  632. enabling proportional weight division of disk bandwidth in CFQ, set
  633. CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
  634. CONFIG_BLK_DEV_THROTTLING=y.
  635. See Documentation/cgroups/blkio-controller.txt for more information.
  636. config DEBUG_BLK_CGROUP
  637. bool "Enable Block IO controller debugging"
  638. depends on BLK_CGROUP
  639. default n
  640. ---help---
  641. Enable some debugging help. Currently it exports additional stat
  642. files in a cgroup which can be useful for debugging.
  643. endif # CGROUPS
  644. menuconfig NAMESPACES
  645. bool "Namespaces support" if EXPERT
  646. default !EXPERT
  647. help
  648. Provides the way to make tasks work with different objects using
  649. the same id. For example same IPC id may refer to different objects
  650. or same user id or pid may refer to different tasks when used in
  651. different namespaces.
  652. if NAMESPACES
  653. config UTS_NS
  654. bool "UTS namespace"
  655. default y
  656. help
  657. In this namespace tasks see different info provided with the
  658. uname() system call
  659. config IPC_NS
  660. bool "IPC namespace"
  661. depends on (SYSVIPC || POSIX_MQUEUE)
  662. default y
  663. help
  664. In this namespace tasks work with IPC ids which correspond to
  665. different IPC objects in different namespaces.
  666. config USER_NS
  667. bool "User namespace (EXPERIMENTAL)"
  668. depends on EXPERIMENTAL
  669. default y
  670. help
  671. This allows containers, i.e. vservers, to use user namespaces
  672. to provide different user info for different servers.
  673. If unsure, say N.
  674. config PID_NS
  675. bool "PID Namespaces"
  676. default y
  677. help
  678. Support process id namespaces. This allows having multiple
  679. processes with the same pid as long as they are in different
  680. pid namespaces. This is a building block of containers.
  681. config NET_NS
  682. bool "Network namespace"
  683. depends on NET
  684. default y
  685. help
  686. Allow user space to create what appear to be multiple instances
  687. of the network stack.
  688. endif # NAMESPACES
  689. config SCHED_AUTOGROUP
  690. bool "Automatic process group scheduling"
  691. select EVENTFD
  692. select CGROUPS
  693. select CGROUP_SCHED
  694. select FAIR_GROUP_SCHED
  695. help
  696. This option optimizes the scheduler for common desktop workloads by
  697. automatically creating and populating task groups. This separation
  698. of workloads isolates aggressive CPU burners (like build jobs) from
  699. desktop applications. Task group autogeneration is currently based
  700. upon task session.
  701. config MM_OWNER
  702. bool
  703. config SYSFS_DEPRECATED
  704. bool "Enable deprecated sysfs features to support old userspace tools"
  705. depends on SYSFS
  706. default n
  707. help
  708. This option adds code that switches the layout of the "block" class
  709. devices, to not show up in /sys/class/block/, but only in
  710. /sys/block/.
  711. This switch is only active when the sysfs.deprecated=1 boot option is
  712. passed or the SYSFS_DEPRECATED_V2 option is set.
  713. This option allows new kernels to run on old distributions and tools,
  714. which might get confused by /sys/class/block/. Since 2007/2008 all
  715. major distributions and tools handle this just fine.
  716. Recent distributions and userspace tools after 2009/2010 depend on
  717. the existence of /sys/class/block/, and will not work with this
  718. option enabled.
  719. Only if you are using a new kernel on an old distribution, you might
  720. need to say Y here.
  721. config SYSFS_DEPRECATED_V2
  722. bool "Enable deprecated sysfs features by default"
  723. default n
  724. depends on SYSFS
  725. depends on SYSFS_DEPRECATED
  726. help
  727. Enable deprecated sysfs by default.
  728. See the CONFIG_SYSFS_DEPRECATED option for more details about this
  729. option.
  730. Only if you are using a new kernel on an old distribution, you might
  731. need to say Y here. Even then, odds are you would not need it
  732. enabled, you can always pass the boot option if absolutely necessary.
  733. config RELAY
  734. bool "Kernel->user space relay support (formerly relayfs)"
  735. help
  736. This option enables support for relay interface support in
  737. certain file systems (such as debugfs).
  738. It is designed to provide an efficient mechanism for tools and
  739. facilities to relay large amounts of data from kernel space to
  740. user space.
  741. If unsure, say N.
  742. config BLK_DEV_INITRD
  743. bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
  744. depends on BROKEN || !FRV
  745. help
  746. The initial RAM filesystem is a ramfs which is loaded by the
  747. boot loader (loadlin or lilo) and that is mounted as root
  748. before the normal boot procedure. It is typically used to
  749. load modules needed to mount the "real" root file system,
  750. etc. See <file:Documentation/initrd.txt> for details.
  751. If RAM disk support (BLK_DEV_RAM) is also included, this
  752. also enables initial RAM disk (initrd) support and adds
  753. 15 Kbytes (more on some other architectures) to the kernel size.
  754. If unsure say Y.
  755. if BLK_DEV_INITRD
  756. source "usr/Kconfig"
  757. endif
  758. config CC_OPTIMIZE_FOR_SIZE
  759. bool "Optimize for size"
  760. help
  761. Enabling this option will pass "-Os" instead of "-O2" to gcc
  762. resulting in a smaller kernel.
  763. If unsure, say Y.
  764. config SYSCTL
  765. bool
  766. config ANON_INODES
  767. bool
  768. menuconfig EXPERT
  769. bool "Configure standard kernel features (expert users)"
  770. help
  771. This option allows certain base kernel options and settings
  772. to be disabled or tweaked. This is for specialized
  773. environments which can tolerate a "non-standard" kernel.
  774. Only use this if you really know what you are doing.
  775. config UID16
  776. bool "Enable 16-bit UID system calls" if EXPERT
  777. depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
  778. default y
  779. help
  780. This enables the legacy 16-bit UID syscall wrappers.
  781. config SYSCTL_SYSCALL
  782. bool "Sysctl syscall support" if EXPERT
  783. depends on PROC_SYSCTL
  784. default y
  785. select SYSCTL
  786. ---help---
  787. sys_sysctl uses binary paths that have been found challenging
  788. to properly maintain and use. The interface in /proc/sys
  789. using paths with ascii names is now the primary path to this
  790. information.
  791. Almost nothing using the binary sysctl interface so if you are
  792. trying to save some space it is probably safe to disable this,
  793. making your kernel marginally smaller.
  794. If unsure say Y here.
  795. config KALLSYMS
  796. bool "Load all symbols for debugging/ksymoops" if EXPERT
  797. default y
  798. help
  799. Say Y here to let the kernel print out symbolic crash information and
  800. symbolic stack backtraces. This increases the size of the kernel
  801. somewhat, as all symbols have to be loaded into the kernel image.
  802. config KALLSYMS_ALL
  803. bool "Include all symbols in kallsyms"
  804. depends on DEBUG_KERNEL && KALLSYMS
  805. help
  806. Normally kallsyms only contains the symbols of functions for nicer
  807. OOPS messages and backtraces (i.e., symbols from the text and inittext
  808. sections). This is sufficient for most cases. And only in very rare
  809. cases (e.g., when a debugger is used) all symbols are required (e.g.,
  810. names of variables from the data sections, etc).
  811. This option makes sure that all symbols are loaded into the kernel
  812. image (i.e., symbols from all sections) in cost of increased kernel
  813. size (depending on the kernel configuration, it may be 300KiB or
  814. something like this).
  815. Say N unless you really need all symbols.
  816. config HOTPLUG
  817. bool "Support for hot-pluggable devices" if EXPERT
  818. default y
  819. help
  820. This option is provided for the case where no hotplug or uevent
  821. capabilities is wanted by the kernel. You should only consider
  822. disabling this option for embedded systems that do not use modules, a
  823. dynamic /dev tree, or dynamic device discovery. Just say Y.
  824. config PRINTK
  825. default y
  826. bool "Enable support for printk" if EXPERT
  827. help
  828. This option enables normal printk support. Removing it
  829. eliminates most of the message strings from the kernel image
  830. and makes the kernel more or less silent. As this makes it
  831. very difficult to diagnose system problems, saying N here is
  832. strongly discouraged.
  833. config BUG
  834. bool "BUG() support" if EXPERT
  835. default y
  836. help
  837. Disabling this option eliminates support for BUG and WARN, reducing
  838. the size of your kernel image and potentially quietly ignoring
  839. numerous fatal conditions. You should only consider disabling this
  840. option for embedded systems with no facilities for reporting errors.
  841. Just say Y.
  842. config ELF_CORE
  843. default y
  844. bool "Enable ELF core dumps" if EXPERT
  845. help
  846. Enable support for generating core dumps. Disabling saves about 4k.
  847. config PCSPKR_PLATFORM
  848. bool "Enable PC-Speaker support" if EXPERT
  849. depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
  850. default y
  851. help
  852. This option allows to disable the internal PC-Speaker
  853. support, saving some memory.
  854. config BASE_FULL
  855. default y
  856. bool "Enable full-sized data structures for core" if EXPERT
  857. help
  858. Disabling this option reduces the size of miscellaneous core
  859. kernel data structures. This saves memory on small machines,
  860. but may reduce performance.
  861. config FUTEX
  862. bool "Enable futex support" if EXPERT
  863. default y
  864. select RT_MUTEXES
  865. help
  866. Disabling this option will cause the kernel to be built without
  867. support for "fast userspace mutexes". The resulting kernel may not
  868. run glibc-based applications correctly.
  869. config EPOLL
  870. bool "Enable eventpoll support" if EXPERT
  871. default y
  872. select ANON_INODES
  873. help
  874. Disabling this option will cause the kernel to be built without
  875. support for epoll family of system calls.
  876. config SIGNALFD
  877. bool "Enable signalfd() system call" if EXPERT
  878. select ANON_INODES
  879. default y
  880. help
  881. Enable the signalfd() system call that allows to receive signals
  882. on a file descriptor.
  883. If unsure, say Y.
  884. config TIMERFD
  885. bool "Enable timerfd() system call" if EXPERT
  886. select ANON_INODES
  887. default y
  888. help
  889. Enable the timerfd() system call that allows to receive timer
  890. events on a file descriptor.
  891. If unsure, say Y.
  892. config EVENTFD
  893. bool "Enable eventfd() system call" if EXPERT
  894. select ANON_INODES
  895. default y
  896. help
  897. Enable the eventfd() system call that allows to receive both
  898. kernel notification (ie. KAIO) or userspace notifications.
  899. If unsure, say Y.
  900. config SHMEM
  901. bool "Use full shmem filesystem" if EXPERT
  902. default y
  903. depends on MMU
  904. help
  905. The shmem is an internal filesystem used to manage shared memory.
  906. It is backed by swap and manages resource limits. It is also exported
  907. to userspace as tmpfs if TMPFS is enabled. Disabling this
  908. option replaces shmem and tmpfs with the much simpler ramfs code,
  909. which may be appropriate on small systems without swap.
  910. config AIO
  911. bool "Enable AIO support" if EXPERT
  912. default y
  913. help
  914. This option enables POSIX asynchronous I/O which may by used
  915. by some high performance threaded applications. Disabling
  916. this option saves about 7k.
  917. config EMBEDDED
  918. bool "Embedded system"
  919. select EXPERT
  920. help
  921. This option should be enabled if compiling the kernel for
  922. an embedded system so certain expert options are available
  923. for configuration.
  924. config HAVE_PERF_EVENTS
  925. bool
  926. help
  927. See tools/perf/design.txt for details.
  928. config PERF_USE_VMALLOC
  929. bool
  930. help
  931. See tools/perf/design.txt for details
  932. menu "Kernel Performance Events And Counters"
  933. config PERF_EVENTS
  934. bool "Kernel performance events and counters"
  935. default y if (PROFILING || PERF_COUNTERS)
  936. depends on HAVE_PERF_EVENTS
  937. select ANON_INODES
  938. select IRQ_WORK
  939. help
  940. Enable kernel support for various performance events provided
  941. by software and hardware.
  942. Software events are supported either built-in or via the
  943. use of generic tracepoints.
  944. Most modern CPUs support performance events via performance
  945. counter registers. These registers count the number of certain
  946. types of hw events: such as instructions executed, cachemisses
  947. suffered, or branches mis-predicted - without slowing down the
  948. kernel or applications. These registers can also trigger interrupts
  949. when a threshold number of events have passed - and can thus be
  950. used to profile the code that runs on that CPU.
  951. The Linux Performance Event subsystem provides an abstraction of
  952. these software and hardware event capabilities, available via a
  953. system call and used by the "perf" utility in tools/perf/. It
  954. provides per task and per CPU counters, and it provides event
  955. capabilities on top of those.
  956. Say Y if unsure.
  957. config PERF_COUNTERS
  958. bool "Kernel performance counters (old config option)"
  959. depends on HAVE_PERF_EVENTS
  960. help
  961. This config has been obsoleted by the PERF_EVENTS
  962. config option - please see that one for details.
  963. It has no effect on the kernel whether you enable
  964. it or not, it is a compatibility placeholder.
  965. Say N if unsure.
  966. config DEBUG_PERF_USE_VMALLOC
  967. default n
  968. bool "Debug: use vmalloc to back perf mmap() buffers"
  969. depends on PERF_EVENTS && DEBUG_KERNEL
  970. select PERF_USE_VMALLOC
  971. help
  972. Use vmalloc memory to back perf mmap() buffers.
  973. Mostly useful for debugging the vmalloc code on platforms
  974. that don't require it.
  975. Say N if unsure.
  976. endmenu
  977. config VM_EVENT_COUNTERS
  978. default y
  979. bool "Enable VM event counters for /proc/vmstat" if EXPERT
  980. help
  981. VM event counters are needed for event counts to be shown.
  982. This option allows the disabling of the VM event counters
  983. on EXPERT systems. /proc/vmstat will only show page counts
  984. if VM event counters are disabled.
  985. config PCI_QUIRKS
  986. default y
  987. bool "Enable PCI quirk workarounds" if EXPERT
  988. depends on PCI
  989. help
  990. This enables workarounds for various PCI chipset
  991. bugs/quirks. Disable this only if your target machine is
  992. unaffected by PCI quirks.
  993. config SLUB_DEBUG
  994. default y
  995. bool "Enable SLUB debugging support" if EXPERT
  996. depends on SLUB && SYSFS
  997. help
  998. SLUB has extensive debug support features. Disabling these can
  999. result in significant savings in code size. This also disables
  1000. SLUB sysfs support. /sys/slab will not exist and there will be
  1001. no support for cache validation etc.
  1002. config COMPAT_BRK
  1003. bool "Disable heap randomization"
  1004. default y
  1005. help
  1006. Randomizing heap placement makes heap exploits harder, but it
  1007. also breaks ancient binaries (including anything libc5 based).
  1008. This option changes the bootup default to heap randomization
  1009. disabled, and can be overridden at runtime by setting
  1010. /proc/sys/kernel/randomize_va_space to 2.
  1011. On non-ancient distros (post-2000 ones) N is usually a safe choice.
  1012. choice
  1013. prompt "Choose SLAB allocator"
  1014. default SLUB
  1015. help
  1016. This option allows to select a slab allocator.
  1017. config SLAB
  1018. bool "SLAB"
  1019. help
  1020. The regular slab allocator that is established and known to work
  1021. well in all environments. It organizes cache hot objects in
  1022. per cpu and per node queues.
  1023. config SLUB
  1024. bool "SLUB (Unqueued Allocator)"
  1025. help
  1026. SLUB is a slab allocator that minimizes cache line usage
  1027. instead of managing queues of cached objects (SLAB approach).
  1028. Per cpu caching is realized using slabs of objects instead
  1029. of queues of objects. SLUB can use memory efficiently
  1030. and has enhanced diagnostics. SLUB is the default choice for
  1031. a slab allocator.
  1032. config SLOB
  1033. depends on EXPERT
  1034. bool "SLOB (Simple Allocator)"
  1035. help
  1036. SLOB replaces the stock allocator with a drastically simpler
  1037. allocator. SLOB is generally more space efficient but
  1038. does not perform as well on large systems.
  1039. endchoice
  1040. config MMAP_ALLOW_UNINITIALIZED
  1041. bool "Allow mmapped anonymous memory to be uninitialized"
  1042. depends on EXPERT && !MMU
  1043. default n
  1044. help
  1045. Normally, and according to the Linux spec, anonymous memory obtained
  1046. from mmap() has it's contents cleared before it is passed to
  1047. userspace. Enabling this config option allows you to request that
  1048. mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
  1049. providing a huge performance boost. If this option is not enabled,
  1050. then the flag will be ignored.
  1051. This is taken advantage of by uClibc's malloc(), and also by
  1052. ELF-FDPIC binfmt's brk and stack allocator.
  1053. Because of the obvious security issues, this option should only be
  1054. enabled on embedded devices where you control what is run in
  1055. userspace. Since that isn't generally a problem on no-MMU systems,
  1056. it is normally safe to say Y here.
  1057. See Documentation/nommu-mmap.txt for more information.
  1058. config PROFILING
  1059. bool "Profiling support"
  1060. help
  1061. Say Y here to enable the extended profiling support mechanisms used
  1062. by profilers such as OProfile.
  1063. #
  1064. # Place an empty function call at each tracepoint site. Can be
  1065. # dynamically changed for a probe function.
  1066. #
  1067. config TRACEPOINTS
  1068. bool
  1069. source "arch/Kconfig"
  1070. endmenu # General setup
  1071. config HAVE_GENERIC_DMA_COHERENT
  1072. bool
  1073. default n
  1074. config SLABINFO
  1075. bool
  1076. depends on PROC_FS
  1077. depends on SLAB || SLUB_DEBUG
  1078. default y
  1079. config RT_MUTEXES
  1080. boolean
  1081. config BASE_SMALL
  1082. int
  1083. default 0 if BASE_FULL
  1084. default 1 if !BASE_FULL
  1085. menuconfig MODULES
  1086. bool "Enable loadable module support"
  1087. help
  1088. Kernel modules are small pieces of compiled code which can
  1089. be inserted in the running kernel, rather than being
  1090. permanently built into the kernel. You use the "modprobe"
  1091. tool to add (and sometimes remove) them. If you say Y here,
  1092. many parts of the kernel can be built as modules (by
  1093. answering M instead of Y where indicated): this is most
  1094. useful for infrequently used options which are not required
  1095. for booting. For more information, see the man pages for
  1096. modprobe, lsmod, modinfo, insmod and rmmod.
  1097. If you say Y here, you will need to run "make
  1098. modules_install" to put the modules under /lib/modules/
  1099. where modprobe can find them (you may need to be root to do
  1100. this).
  1101. If unsure, say Y.
  1102. if MODULES
  1103. config MODULE_FORCE_LOAD
  1104. bool "Forced module loading"
  1105. default n
  1106. help
  1107. Allow loading of modules without version information (ie. modprobe
  1108. --force). Forced module loading sets the 'F' (forced) taint flag and
  1109. is usually a really bad idea.
  1110. config MODULE_UNLOAD
  1111. bool "Module unloading"
  1112. help
  1113. Without this option you will not be able to unload any
  1114. modules (note that some modules may not be unloadable
  1115. anyway), which makes your kernel smaller, faster
  1116. and simpler. If unsure, say Y.
  1117. config MODULE_FORCE_UNLOAD
  1118. bool "Forced module unloading"
  1119. depends on MODULE_UNLOAD && EXPERIMENTAL
  1120. help
  1121. This option allows you to force a module to unload, even if the
  1122. kernel believes it is unsafe: the kernel will remove the module
  1123. without waiting for anyone to stop using it (using the -f option to
  1124. rmmod). This is mainly for kernel developers and desperate users.
  1125. If unsure, say N.
  1126. config MODVERSIONS
  1127. bool "Module versioning support"
  1128. help
  1129. Usually, you have to use modules compiled with your kernel.
  1130. Saying Y here makes it sometimes possible to use modules
  1131. compiled for different kernels, by adding enough information
  1132. to the modules to (hopefully) spot any changes which would
  1133. make them incompatible with the kernel you are running. If
  1134. unsure, say N.
  1135. config MODULE_SRCVERSION_ALL
  1136. bool "Source checksum for all modules"
  1137. help
  1138. Modules which contain a MODULE_VERSION get an extra "srcversion"
  1139. field inserted into their modinfo section, which contains a
  1140. sum of the source files which made it. This helps maintainers
  1141. see exactly which source was used to build a module (since
  1142. others sometimes change the module source without updating
  1143. the version). With this option, such a "srcversion" field
  1144. will be created for all modules. If unsure, say N.
  1145. endif # MODULES
  1146. config INIT_ALL_POSSIBLE
  1147. bool
  1148. help
  1149. Back when each arch used to define their own cpu_online_map and
  1150. cpu_possible_map, some of them chose to initialize cpu_possible_map
  1151. with all 1s, and others with all 0s. When they were centralised,
  1152. it was better to provide this option than to break all the archs
  1153. and have several arch maintainers pursuing me down dark alleys.
  1154. config STOP_MACHINE
  1155. bool
  1156. default y
  1157. depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
  1158. help
  1159. Need stop_machine() primitive.
  1160. source "block/Kconfig"
  1161. config PREEMPT_NOTIFIERS
  1162. bool
  1163. config PADATA
  1164. depends on SMP
  1165. bool
  1166. source "kernel/Kconfig.locks"