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 drivers that have been replaced by something else, and/or are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 LOCK_KERNEL
  61. bool
  62. depends on (SMP || PREEMPT) && BKL
  63. default y
  64. config INIT_ENV_ARG_LIMIT
  65. int
  66. default 32 if !UML
  67. default 128 if UML
  68. help
  69. Maximum of each of the number of arguments and environment
  70. variables passed to init from the kernel command line.
  71. config CROSS_COMPILE
  72. string "Cross-compiler tool prefix"
  73. help
  74. Same as running 'make CROSS_COMPILE=prefix-' but stored for
  75. default make runs in this kernel build directory. You don't
  76. need to set this unless you want the configured kernel build
  77. directory to select the cross-compiler automatically.
  78. config LOCALVERSION
  79. string "Local version - append to kernel release"
  80. help
  81. Append an extra string to the end of your kernel version.
  82. This will show up when you type uname, for example.
  83. The string you set here will be appended after the contents of
  84. any files with a filename matching localversion* in your
  85. object and source tree, in that order. Your total string can
  86. be a maximum of 64 characters.
  87. config LOCALVERSION_AUTO
  88. bool "Automatically append version information to the version string"
  89. default y
  90. help
  91. This will try to automatically determine if the current tree is a
  92. release tree by looking for git tags that belong to the current
  93. top of tree revision.
  94. A string of the format -gxxxxxxxx will be added to the localversion
  95. if a git-based tree is found. The string generated by this will be
  96. appended after any matching localversion* files, and after the value
  97. set in CONFIG_LOCALVERSION.
  98. (The actual string used here is the first eight characters produced
  99. by running the command:
  100. $ git rev-parse --verify HEAD
  101. which is done within the script "scripts/setlocalversion".)
  102. config HAVE_KERNEL_GZIP
  103. bool
  104. config HAVE_KERNEL_BZIP2
  105. bool
  106. config HAVE_KERNEL_LZMA
  107. bool
  108. config HAVE_KERNEL_XZ
  109. bool
  110. config HAVE_KERNEL_LZO
  111. bool
  112. choice
  113. prompt "Kernel compression mode"
  114. default KERNEL_GZIP
  115. depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
  116. help
  117. The linux kernel is a kind of self-extracting executable.
  118. Several compression algorithms are available, which differ
  119. in efficiency, compression and decompression speed.
  120. Compression speed is only relevant when building a kernel.
  121. Decompression speed is relevant at each boot.
  122. If you have any problems with bzip2 or lzma compressed
  123. kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
  124. version of this functionality (bzip2 only), for 2.4, was
  125. supplied by Christian Ludwig)
  126. High compression options are mostly useful for users, who
  127. are low on disk space (embedded systems), but for whom ram
  128. size matters less.
  129. If in doubt, select 'gzip'
  130. config KERNEL_GZIP
  131. bool "Gzip"
  132. depends on HAVE_KERNEL_GZIP
  133. help
  134. The old and tried gzip compression. It provides a good balance
  135. between compression ratio and decompression speed.
  136. config KERNEL_BZIP2
  137. bool "Bzip2"
  138. depends on HAVE_KERNEL_BZIP2
  139. help
  140. Its compression ratio and speed is intermediate.
  141. Decompression speed is slowest among the three. The kernel
  142. size is about 10% smaller with bzip2, in comparison to gzip.
  143. Bzip2 uses a large amount of memory. For modern kernels you
  144. will need at least 8MB RAM or more for booting.
  145. config KERNEL_LZMA
  146. bool "LZMA"
  147. depends on HAVE_KERNEL_LZMA
  148. help
  149. The most recent compression algorithm.
  150. Its ratio is best, decompression speed is between the other
  151. two. Compression is slowest. The kernel size is about 33%
  152. smaller with LZMA in comparison to gzip.
  153. config KERNEL_XZ
  154. bool "XZ"
  155. depends on HAVE_KERNEL_XZ
  156. help
  157. XZ uses the LZMA2 algorithm and instruction set specific
  158. BCJ filters which can improve compression ratio of executable
  159. code. The size of the kernel is about 30% smaller with XZ in
  160. comparison to gzip. On architectures for which there is a BCJ
  161. filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
  162. will create a few percent smaller kernel than plain LZMA.
  163. The speed is about the same as with LZMA: The decompression
  164. speed of XZ is better than that of bzip2 but worse than gzip
  165. and LZO. Compression is slow.
  166. config KERNEL_LZO
  167. bool "LZO"
  168. depends on HAVE_KERNEL_LZO
  169. help
  170. Its compression ratio is the poorest among the 4. The kernel
  171. size is about 10% bigger than gzip; however its speed
  172. (both compression and decompression) is the fastest.
  173. endchoice
  174. config SWAP
  175. bool "Support for paging of anonymous memory (swap)"
  176. depends on MMU && BLOCK
  177. default y
  178. help
  179. This option allows you to choose whether you want to have support
  180. for so called swap devices or swap files in your kernel that are
  181. used to provide more virtual memory than the actual RAM present
  182. in your computer. If unsure say Y.
  183. config SYSVIPC
  184. bool "System V IPC"
  185. ---help---
  186. Inter Process Communication is a suite of library functions and
  187. system calls which let processes (running programs) synchronize and
  188. exchange information. It is generally considered to be a good thing,
  189. and some programs won't run unless you say Y here. In particular, if
  190. you want to run the DOS emulator dosemu under Linux (read the
  191. DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
  192. you'll need to say Y here.
  193. You can find documentation about IPC with "info ipc" and also in
  194. section 6.4 of the Linux Programmer's Guide, available from
  195. <http://www.tldp.org/guides.html>.
  196. config SYSVIPC_SYSCTL
  197. bool
  198. depends on SYSVIPC
  199. depends on SYSCTL
  200. default y
  201. config POSIX_MQUEUE
  202. bool "POSIX Message Queues"
  203. depends on NET && EXPERIMENTAL
  204. ---help---
  205. POSIX variant of message queues is a part of IPC. In POSIX message
  206. queues every message has a priority which decides about succession
  207. of receiving it by a process. If you want to compile and run
  208. programs written e.g. for Solaris with use of its POSIX message
  209. queues (functions mq_*) say Y here.
  210. POSIX message queues are visible as a filesystem called 'mqueue'
  211. and can be mounted somewhere if you want to do filesystem
  212. operations on message queues.
  213. If unsure, say Y.
  214. config POSIX_MQUEUE_SYSCTL
  215. bool
  216. depends on POSIX_MQUEUE
  217. depends on SYSCTL
  218. default y
  219. config BSD_PROCESS_ACCT
  220. bool "BSD Process Accounting"
  221. help
  222. If you say Y here, a user level program will be able to instruct the
  223. kernel (via a special system call) to write process accounting
  224. information to a file: whenever a process exits, information about
  225. that process will be appended to the file by the kernel. The
  226. information includes things such as creation time, owning user,
  227. command name, memory usage, controlling terminal etc. (the complete
  228. list is in the struct acct in <file:include/linux/acct.h>). It is
  229. up to the user level program to do useful things with this
  230. information. This is generally a good idea, so say Y.
  231. config BSD_PROCESS_ACCT_V3
  232. bool "BSD Process Accounting version 3 file format"
  233. depends on BSD_PROCESS_ACCT
  234. default n
  235. help
  236. If you say Y here, the process accounting information is written
  237. in a new file format that also logs the process IDs of each
  238. process and it's parent. Note that this file format is incompatible
  239. with previous v0/v1/v2 file formats, so you will need updated tools
  240. for processing it. A preliminary version of these tools is available
  241. at <http://www.gnu.org/software/acct/>.
  242. config FHANDLE
  243. bool "open by fhandle syscalls"
  244. select EXPORTFS
  245. help
  246. If you say Y here, a user level program will be able to map
  247. file names to handle and then later use the handle for
  248. different file system operations. This is useful in implementing
  249. userspace file servers, which now track files using handles instead
  250. of names. The handle would remain the same even if file names
  251. get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
  252. syscalls.
  253. config TASKSTATS
  254. bool "Export task/process statistics through netlink (EXPERIMENTAL)"
  255. depends on NET
  256. default n
  257. help
  258. Export selected statistics for tasks/processes through the
  259. generic netlink interface. Unlike BSD process accounting, the
  260. statistics are available during the lifetime of tasks/processes as
  261. responses to commands. Like BSD accounting, they are sent to user
  262. space on task exit.
  263. Say N if unsure.
  264. config TASK_DELAY_ACCT
  265. bool "Enable per-task delay accounting (EXPERIMENTAL)"
  266. depends on TASKSTATS
  267. help
  268. Collect information on time spent by a task waiting for system
  269. resources like cpu, synchronous block I/O completion and swapping
  270. in pages. Such statistics can help in setting a task's priorities
  271. relative to other tasks for cpu, io, rss limits etc.
  272. Say N if unsure.
  273. config TASK_XACCT
  274. bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
  275. depends on TASKSTATS
  276. help
  277. Collect extended task accounting data and send the data
  278. to userland for processing over the taskstats interface.
  279. Say N if unsure.
  280. config TASK_IO_ACCOUNTING
  281. bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
  282. depends on TASK_XACCT
  283. help
  284. Collect information on the number of bytes of storage I/O which this
  285. task has caused.
  286. Say N if unsure.
  287. config AUDIT
  288. bool "Auditing support"
  289. depends on NET
  290. help
  291. Enable auditing infrastructure that can be used with another
  292. kernel subsystem, such as SELinux (which requires this for
  293. logging of avc messages output). Does not do system-call
  294. auditing without CONFIG_AUDITSYSCALL.
  295. config AUDITSYSCALL
  296. bool "Enable system-call auditing support"
  297. depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
  298. default y if SECURITY_SELINUX
  299. help
  300. Enable low-overhead system-call auditing infrastructure that
  301. can be used independently or with another kernel subsystem,
  302. such as SELinux.
  303. config AUDIT_WATCH
  304. def_bool y
  305. depends on AUDITSYSCALL
  306. select FSNOTIFY
  307. config AUDIT_TREE
  308. def_bool y
  309. depends on AUDITSYSCALL
  310. select FSNOTIFY
  311. source "kernel/irq/Kconfig"
  312. menu "RCU Subsystem"
  313. choice
  314. prompt "RCU Implementation"
  315. default TREE_RCU
  316. config TREE_RCU
  317. bool "Tree-based hierarchical RCU"
  318. depends on !PREEMPT && SMP
  319. help
  320. This option selects the RCU implementation that is
  321. designed for very large SMP system with hundreds or
  322. thousands of CPUs. It also scales down nicely to
  323. smaller systems.
  324. config TREE_PREEMPT_RCU
  325. bool "Preemptible tree-based hierarchical RCU"
  326. depends on PREEMPT
  327. help
  328. This option selects the RCU implementation that is
  329. designed for very large SMP systems with hundreds or
  330. thousands of CPUs, but for which real-time response
  331. is also required. It also scales down nicely to
  332. smaller systems.
  333. config TINY_RCU
  334. bool "UP-only small-memory-footprint RCU"
  335. depends on !SMP
  336. help
  337. This option selects the RCU implementation that is
  338. designed for UP systems from which real-time response
  339. is not required. This option greatly reduces the
  340. memory footprint of RCU.
  341. config TINY_PREEMPT_RCU
  342. bool "Preemptible UP-only small-memory-footprint RCU"
  343. depends on !SMP && PREEMPT
  344. help
  345. This option selects the RCU implementation that is designed
  346. for real-time UP systems. This option greatly reduces the
  347. memory footprint of RCU.
  348. endchoice
  349. config PREEMPT_RCU
  350. def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
  351. help
  352. This option enables preemptible-RCU code that is common between
  353. the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
  354. config RCU_TRACE
  355. bool "Enable tracing for RCU"
  356. help
  357. This option provides tracing in RCU which presents stats
  358. in debugfs for debugging RCU implementation.
  359. Say Y here if you want to enable RCU tracing
  360. Say N if you are unsure.
  361. config RCU_FANOUT
  362. int "Tree-based hierarchical RCU fanout value"
  363. range 2 64 if 64BIT
  364. range 2 32 if !64BIT
  365. depends on TREE_RCU || TREE_PREEMPT_RCU
  366. default 64 if 64BIT
  367. default 32 if !64BIT
  368. help
  369. This option controls the fanout of hierarchical implementations
  370. of RCU, allowing RCU to work efficiently on machines with
  371. large numbers of CPUs. This value must be at least the fourth
  372. root of NR_CPUS, which allows NR_CPUS to be insanely large.
  373. The default value of RCU_FANOUT should be used for production
  374. systems, but if you are stress-testing the RCU implementation
  375. itself, small RCU_FANOUT values allow you to test large-system
  376. code paths on small(er) systems.
  377. Select a specific number if testing RCU itself.
  378. Take the default if unsure.
  379. config RCU_FANOUT_EXACT
  380. bool "Disable tree-based hierarchical RCU auto-balancing"
  381. depends on TREE_RCU || TREE_PREEMPT_RCU
  382. default n
  383. help
  384. This option forces use of the exact RCU_FANOUT value specified,
  385. regardless of imbalances in the hierarchy. This is useful for
  386. testing RCU itself, and might one day be useful on systems with
  387. strong NUMA behavior.
  388. Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
  389. Say N if unsure.
  390. config RCU_FAST_NO_HZ
  391. bool "Accelerate last non-dyntick-idle CPU's grace periods"
  392. depends on TREE_RCU && NO_HZ && SMP
  393. default n
  394. help
  395. This option causes RCU to attempt to accelerate grace periods
  396. in order to allow the final CPU to enter dynticks-idle state
  397. more quickly. On the other hand, this option increases the
  398. overhead of the dynticks-idle checking, particularly on systems
  399. with large numbers of CPUs.
  400. Say Y if energy efficiency is critically important, particularly
  401. if you have relatively few CPUs.
  402. Say N if you are unsure.
  403. config TREE_RCU_TRACE
  404. def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
  405. select DEBUG_FS
  406. help
  407. This option provides tracing for the TREE_RCU and
  408. TREE_PREEMPT_RCU implementations, permitting Makefile to
  409. trivially select kernel/rcutree_trace.c.
  410. config RCU_BOOST
  411. bool "Enable RCU priority boosting"
  412. depends on RT_MUTEXES && TINY_PREEMPT_RCU
  413. default n
  414. help
  415. This option boosts the priority of preempted RCU readers that
  416. block the current preemptible RCU grace period for too long.
  417. This option also prevents heavy loads from blocking RCU
  418. callback invocation for all flavors of RCU.
  419. Say Y here if you are working with real-time apps or heavy loads
  420. Say N here if you are unsure.
  421. config RCU_BOOST_PRIO
  422. int "Real-time priority to boost RCU readers to"
  423. range 1 99
  424. depends on RCU_BOOST
  425. default 1
  426. help
  427. This option specifies the real-time priority to which preempted
  428. RCU readers are to be boosted. If you are working with CPU-bound
  429. real-time applications, you should specify a priority higher then
  430. the highest-priority CPU-bound application.
  431. Specify the real-time priority, or take the default if unsure.
  432. config RCU_BOOST_DELAY
  433. int "Milliseconds to delay boosting after RCU grace-period start"
  434. range 0 3000
  435. depends on RCU_BOOST
  436. default 500
  437. help
  438. This option specifies the time to wait after the beginning of
  439. a given grace period before priority-boosting preempted RCU
  440. readers blocking that grace period. Note that any RCU reader
  441. blocking an expedited RCU grace period is boosted immediately.
  442. Accept the default if unsure.
  443. endmenu # "RCU Subsystem"
  444. config IKCONFIG
  445. tristate "Kernel .config support"
  446. ---help---
  447. This option enables the complete Linux kernel ".config" file
  448. contents to be saved in the kernel. It provides documentation
  449. of which kernel options are used in a running kernel or in an
  450. on-disk kernel. This information can be extracted from the kernel
  451. image file with the script scripts/extract-ikconfig and used as
  452. input to rebuild the current kernel or to build another kernel.
  453. It can also be extracted from a running kernel by reading
  454. /proc/config.gz if enabled (below).
  455. config IKCONFIG_PROC
  456. bool "Enable access to .config through /proc/config.gz"
  457. depends on IKCONFIG && PROC_FS
  458. ---help---
  459. This option enables access to the kernel configuration file
  460. through /proc/config.gz.
  461. config LOG_BUF_SHIFT
  462. int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
  463. range 12 21
  464. default 17
  465. help
  466. Select kernel log buffer size as a power of 2.
  467. Examples:
  468. 17 => 128 KB
  469. 16 => 64 KB
  470. 15 => 32 KB
  471. 14 => 16 KB
  472. 13 => 8 KB
  473. 12 => 4 KB
  474. #
  475. # Architectures with an unreliable sched_clock() should select this:
  476. #
  477. config HAVE_UNSTABLE_SCHED_CLOCK
  478. bool
  479. menuconfig CGROUPS
  480. boolean "Control Group support"
  481. depends on EVENTFD
  482. help
  483. This option adds support for grouping sets of processes together, for
  484. use with process control subsystems such as Cpusets, CFS, memory
  485. controls or device isolation.
  486. See
  487. - Documentation/scheduler/sched-design-CFS.txt (CFS)
  488. - Documentation/cgroups/ (features for grouping, isolation
  489. and resource control)
  490. Say N if unsure.
  491. if CGROUPS
  492. config CGROUP_DEBUG
  493. bool "Example debug cgroup subsystem"
  494. default n
  495. help
  496. This option enables a simple cgroup subsystem that
  497. exports useful debugging information about the cgroups
  498. framework.
  499. Say N if unsure.
  500. config CGROUP_NS
  501. bool "Namespace cgroup subsystem"
  502. help
  503. Provides a simple namespace cgroup subsystem to
  504. provide hierarchical naming of sets of namespaces,
  505. for instance virtual servers and checkpoint/restart
  506. jobs.
  507. config CGROUP_FREEZER
  508. bool "Freezer cgroup subsystem"
  509. help
  510. Provides a way to freeze and unfreeze all tasks in a
  511. cgroup.
  512. config CGROUP_DEVICE
  513. bool "Device controller for cgroups"
  514. help
  515. Provides a cgroup implementing whitelists for devices which
  516. a process in the cgroup can mknod or open.
  517. config CPUSETS
  518. bool "Cpuset support"
  519. help
  520. This option will let you create and manage CPUSETs which
  521. allow dynamically partitioning a system into sets of CPUs and
  522. Memory Nodes and assigning tasks to run only within those sets.
  523. This is primarily useful on large SMP or NUMA systems.
  524. Say N if unsure.
  525. config PROC_PID_CPUSET
  526. bool "Include legacy /proc/<pid>/cpuset file"
  527. depends on CPUSETS
  528. default y
  529. config CGROUP_CPUACCT
  530. bool "Simple CPU accounting cgroup subsystem"
  531. help
  532. Provides a simple Resource Controller for monitoring the
  533. total CPU consumed by the tasks in a cgroup.
  534. config RESOURCE_COUNTERS
  535. bool "Resource counters"
  536. help
  537. This option enables controller independent resource accounting
  538. infrastructure that works with cgroups.
  539. config CGROUP_MEM_RES_CTLR
  540. bool "Memory Resource Controller for Control Groups"
  541. depends on RESOURCE_COUNTERS
  542. select MM_OWNER
  543. help
  544. Provides a memory resource controller that manages both anonymous
  545. memory and page cache. (See Documentation/cgroups/memory.txt)
  546. Note that setting this option increases fixed memory overhead
  547. associated with each page of memory in the system. By this,
  548. 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
  549. usage tracking struct at boot. Total amount of this is printed out
  550. at boot.
  551. Only enable when you're ok with these trade offs and really
  552. sure you need the memory resource controller. Even when you enable
  553. this, you can set "cgroup_disable=memory" at your boot option to
  554. disable memory resource controller and you can avoid overheads.
  555. (and lose benefits of memory resource controller)
  556. This config option also selects MM_OWNER config option, which
  557. could in turn add some fork/exit overhead.
  558. config CGROUP_MEM_RES_CTLR_SWAP
  559. bool "Memory Resource Controller Swap Extension"
  560. depends on CGROUP_MEM_RES_CTLR && SWAP
  561. help
  562. Add swap management feature to memory resource controller. When you
  563. enable this, you can limit mem+swap usage per cgroup. In other words,
  564. when you disable this, memory resource controller has no cares to
  565. usage of swap...a process can exhaust all of the swap. This extension
  566. is useful when you want to avoid exhaustion swap but this itself
  567. adds more overheads and consumes memory for remembering information.
  568. Especially if you use 32bit system or small memory system, please
  569. be careful about enabling this. When memory resource controller
  570. is disabled by boot option, this will be automatically disabled and
  571. there will be no overhead from this. Even when you set this config=y,
  572. if boot option "noswapaccount" is set, swap will not be accounted.
  573. Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
  574. size is 4096bytes, 512k per 1Gbytes of swap.
  575. config CGROUP_MEM_RES_CTLR_SWAP_ENABLED
  576. bool "Memory Resource Controller Swap Extension enabled by default"
  577. depends on CGROUP_MEM_RES_CTLR_SWAP
  578. default y
  579. help
  580. Memory Resource Controller Swap Extension comes with its price in
  581. a bigger memory consumption. General purpose distribution kernels
  582. which want to enable the feature but keep it disabled by default
  583. and let the user enable it by swapaccount boot command line
  584. parameter should have this option unselected.
  585. For those who want to have the feature enabled by default should
  586. select this option (if, for some reason, they need to disable it
  587. then noswapaccount does the trick).
  588. config CGROUP_PERF
  589. bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
  590. depends on PERF_EVENTS && CGROUPS
  591. help
  592. This option extends the per-cpu mode to restrict monitoring to
  593. threads which belong to the cgroup specified and run on the
  594. designated cpu.
  595. Say N if unsure.
  596. menuconfig CGROUP_SCHED
  597. bool "Group CPU scheduler"
  598. depends on EXPERIMENTAL
  599. default n
  600. help
  601. This feature lets CPU scheduler recognize task groups and control CPU
  602. bandwidth allocation to such task groups. It uses cgroups to group
  603. tasks.
  604. if CGROUP_SCHED
  605. config FAIR_GROUP_SCHED
  606. bool "Group scheduling for SCHED_OTHER"
  607. depends on CGROUP_SCHED
  608. default CGROUP_SCHED
  609. config RT_GROUP_SCHED
  610. bool "Group scheduling for SCHED_RR/FIFO"
  611. depends on EXPERIMENTAL
  612. depends on CGROUP_SCHED
  613. default n
  614. help
  615. This feature lets you explicitly allocate real CPU bandwidth
  616. to task groups. If enabled, it will also make it impossible to
  617. schedule realtime tasks for non-root users until you allocate
  618. realtime bandwidth for them.
  619. See Documentation/scheduler/sched-rt-group.txt for more information.
  620. endif #CGROUP_SCHED
  621. config BLK_CGROUP
  622. tristate "Block IO controller"
  623. depends on BLOCK
  624. default n
  625. ---help---
  626. Generic block IO controller cgroup interface. This is the common
  627. cgroup interface which should be used by various IO controlling
  628. policies.
  629. Currently, CFQ IO scheduler uses it to recognize task groups and
  630. control disk bandwidth allocation (proportional time slice allocation)
  631. to such task groups. It is also used by bio throttling logic in
  632. block layer to implement upper limit in IO rates on a device.
  633. This option only enables generic Block IO controller infrastructure.
  634. One needs to also enable actual IO controlling logic/policy. For
  635. enabling proportional weight division of disk bandwidth in CFQ seti
  636. CONFIG_CFQ_GROUP_IOSCHED=y and for enabling throttling policy set
  637. CONFIG_BLK_THROTTLE=y.
  638. See Documentation/cgroups/blkio-controller.txt for more information.
  639. config DEBUG_BLK_CGROUP
  640. bool "Enable Block IO controller debugging"
  641. depends on BLK_CGROUP
  642. default n
  643. ---help---
  644. Enable some debugging help. Currently it exports additional stat
  645. files in a cgroup which can be useful for debugging.
  646. endif # CGROUPS
  647. menuconfig NAMESPACES
  648. bool "Namespaces support" if EXPERT
  649. default !EXPERT
  650. help
  651. Provides the way to make tasks work with different objects using
  652. the same id. For example same IPC id may refer to different objects
  653. or same user id or pid may refer to different tasks when used in
  654. different namespaces.
  655. if NAMESPACES
  656. config UTS_NS
  657. bool "UTS namespace"
  658. default y
  659. help
  660. In this namespace tasks see different info provided with the
  661. uname() system call
  662. config IPC_NS
  663. bool "IPC namespace"
  664. depends on (SYSVIPC || POSIX_MQUEUE)
  665. default y
  666. help
  667. In this namespace tasks work with IPC ids which correspond to
  668. different IPC objects in different namespaces.
  669. config USER_NS
  670. bool "User namespace (EXPERIMENTAL)"
  671. depends on EXPERIMENTAL
  672. default y
  673. help
  674. This allows containers, i.e. vservers, to use user namespaces
  675. to provide different user info for different servers.
  676. If unsure, say N.
  677. config PID_NS
  678. bool "PID Namespaces"
  679. default y
  680. help
  681. Support process id namespaces. This allows having multiple
  682. processes with the same pid as long as they are in different
  683. pid namespaces. This is a building block of containers.
  684. config NET_NS
  685. bool "Network namespace"
  686. depends on NET
  687. default y
  688. help
  689. Allow user space to create what appear to be multiple instances
  690. of the network stack.
  691. endif # NAMESPACES
  692. config SCHED_AUTOGROUP
  693. bool "Automatic process group scheduling"
  694. select EVENTFD
  695. select CGROUPS
  696. select CGROUP_SCHED
  697. select FAIR_GROUP_SCHED
  698. help
  699. This option optimizes the scheduler for common desktop workloads by
  700. automatically creating and populating task groups. This separation
  701. of workloads isolates aggressive CPU burners (like build jobs) from
  702. desktop applications. Task group autogeneration is currently based
  703. upon task session.
  704. config MM_OWNER
  705. bool
  706. config SYSFS_DEPRECATED
  707. bool "Enable deprecated sysfs features to support old userspace tools"
  708. depends on SYSFS
  709. default n
  710. help
  711. This option adds code that switches the layout of the "block" class
  712. devices, to not show up in /sys/class/block/, but only in
  713. /sys/block/.
  714. This switch is only active when the sysfs.deprecated=1 boot option is
  715. passed or the SYSFS_DEPRECATED_V2 option is set.
  716. This option allows new kernels to run on old distributions and tools,
  717. which might get confused by /sys/class/block/. Since 2007/2008 all
  718. major distributions and tools handle this just fine.
  719. Recent distributions and userspace tools after 2009/2010 depend on
  720. the existence of /sys/class/block/, and will not work with this
  721. option enabled.
  722. Only if you are using a new kernel on an old distribution, you might
  723. need to say Y here.
  724. config SYSFS_DEPRECATED_V2
  725. bool "Enable deprecated sysfs features by default"
  726. default n
  727. depends on SYSFS
  728. depends on SYSFS_DEPRECATED
  729. help
  730. Enable deprecated sysfs by default.
  731. See the CONFIG_SYSFS_DEPRECATED option for more details about this
  732. option.
  733. Only if you are using a new kernel on an old distribution, you might
  734. need to say Y here. Even then, odds are you would not need it
  735. enabled, you can always pass the boot option if absolutely necessary.
  736. config RELAY
  737. bool "Kernel->user space relay support (formerly relayfs)"
  738. help
  739. This option enables support for relay interface support in
  740. certain file systems (such as debugfs).
  741. It is designed to provide an efficient mechanism for tools and
  742. facilities to relay large amounts of data from kernel space to
  743. user space.
  744. If unsure, say N.
  745. config BLK_DEV_INITRD
  746. bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
  747. depends on BROKEN || !FRV
  748. help
  749. The initial RAM filesystem is a ramfs which is loaded by the
  750. boot loader (loadlin or lilo) and that is mounted as root
  751. before the normal boot procedure. It is typically used to
  752. load modules needed to mount the "real" root file system,
  753. etc. See <file:Documentation/initrd.txt> for details.
  754. If RAM disk support (BLK_DEV_RAM) is also included, this
  755. also enables initial RAM disk (initrd) support and adds
  756. 15 Kbytes (more on some other architectures) to the kernel size.
  757. If unsure say Y.
  758. if BLK_DEV_INITRD
  759. source "usr/Kconfig"
  760. endif
  761. config CC_OPTIMIZE_FOR_SIZE
  762. bool "Optimize for size"
  763. default y
  764. help
  765. Enabling this option will pass "-Os" instead of "-O2" to gcc
  766. resulting in a smaller kernel.
  767. If unsure, say Y.
  768. config SYSCTL
  769. bool
  770. config ANON_INODES
  771. bool
  772. menuconfig EXPERT
  773. bool "Configure standard kernel features (expert users)"
  774. help
  775. This option allows certain base kernel options and settings
  776. to be disabled or tweaked. This is for specialized
  777. environments which can tolerate a "non-standard" kernel.
  778. Only use this if you really know what you are doing.
  779. config EMBEDDED
  780. bool "Embedded system"
  781. select EXPERT
  782. help
  783. This option should be enabled if compiling the kernel for
  784. an embedded system so certain expert options are available
  785. for configuration.
  786. config UID16
  787. bool "Enable 16-bit UID system calls" if EXPERT
  788. depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
  789. default y
  790. help
  791. This enables the legacy 16-bit UID syscall wrappers.
  792. config SYSCTL_SYSCALL
  793. bool "Sysctl syscall support" if EXPERT
  794. depends on PROC_SYSCTL
  795. default y
  796. select SYSCTL
  797. ---help---
  798. sys_sysctl uses binary paths that have been found challenging
  799. to properly maintain and use. The interface in /proc/sys
  800. using paths with ascii names is now the primary path to this
  801. information.
  802. Almost nothing using the binary sysctl interface so if you are
  803. trying to save some space it is probably safe to disable this,
  804. making your kernel marginally smaller.
  805. If unsure say Y here.
  806. config KALLSYMS
  807. bool "Load all symbols for debugging/ksymoops" if EXPERT
  808. default y
  809. help
  810. Say Y here to let the kernel print out symbolic crash information and
  811. symbolic stack backtraces. This increases the size of the kernel
  812. somewhat, as all symbols have to be loaded into the kernel image.
  813. config KALLSYMS_ALL
  814. bool "Include all symbols in kallsyms"
  815. depends on DEBUG_KERNEL && KALLSYMS
  816. help
  817. Normally kallsyms only contains the symbols of functions, for nicer
  818. OOPS messages. Some debuggers can use kallsyms for other
  819. symbols too: say Y here to include all symbols, if you need them
  820. and you don't care about adding 300k to the size of your kernel.
  821. Say N.
  822. config KALLSYMS_EXTRA_PASS
  823. bool "Do an extra kallsyms pass"
  824. depends on KALLSYMS
  825. help
  826. If kallsyms is not working correctly, the build will fail with
  827. inconsistent kallsyms data. If that occurs, log a bug report and
  828. turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
  829. Always say N here unless you find a bug in kallsyms, which must be
  830. reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
  831. you wait for kallsyms to be fixed.
  832. config HOTPLUG
  833. bool "Support for hot-pluggable devices" if EXPERT
  834. default y
  835. help
  836. This option is provided for the case where no hotplug or uevent
  837. capabilities is wanted by the kernel. You should only consider
  838. disabling this option for embedded systems that do not use modules, a
  839. dynamic /dev tree, or dynamic device discovery. Just say Y.
  840. config PRINTK
  841. default y
  842. bool "Enable support for printk" if EXPERT
  843. help
  844. This option enables normal printk support. Removing it
  845. eliminates most of the message strings from the kernel image
  846. and makes the kernel more or less silent. As this makes it
  847. very difficult to diagnose system problems, saying N here is
  848. strongly discouraged.
  849. config BUG
  850. bool "BUG() support" if EXPERT
  851. default y
  852. help
  853. Disabling this option eliminates support for BUG and WARN, reducing
  854. the size of your kernel image and potentially quietly ignoring
  855. numerous fatal conditions. You should only consider disabling this
  856. option for embedded systems with no facilities for reporting errors.
  857. Just say Y.
  858. config ELF_CORE
  859. default y
  860. bool "Enable ELF core dumps" if EXPERT
  861. help
  862. Enable support for generating core dumps. Disabling saves about 4k.
  863. config PCSPKR_PLATFORM
  864. bool "Enable PC-Speaker support" if EXPERT
  865. depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
  866. default y
  867. help
  868. This option allows to disable the internal PC-Speaker
  869. support, saving some memory.
  870. config BASE_FULL
  871. default y
  872. bool "Enable full-sized data structures for core" if EXPERT
  873. help
  874. Disabling this option reduces the size of miscellaneous core
  875. kernel data structures. This saves memory on small machines,
  876. but may reduce performance.
  877. config FUTEX
  878. bool "Enable futex support" if EXPERT
  879. default y
  880. select RT_MUTEXES
  881. help
  882. Disabling this option will cause the kernel to be built without
  883. support for "fast userspace mutexes". The resulting kernel may not
  884. run glibc-based applications correctly.
  885. config EPOLL
  886. bool "Enable eventpoll support" if EXPERT
  887. default y
  888. select ANON_INODES
  889. help
  890. Disabling this option will cause the kernel to be built without
  891. support for epoll family of system calls.
  892. config SIGNALFD
  893. bool "Enable signalfd() system call" if EXPERT
  894. select ANON_INODES
  895. default y
  896. help
  897. Enable the signalfd() system call that allows to receive signals
  898. on a file descriptor.
  899. If unsure, say Y.
  900. config TIMERFD
  901. bool "Enable timerfd() system call" if EXPERT
  902. select ANON_INODES
  903. default y
  904. help
  905. Enable the timerfd() system call that allows to receive timer
  906. events on a file descriptor.
  907. If unsure, say Y.
  908. config EVENTFD
  909. bool "Enable eventfd() system call" if EXPERT
  910. select ANON_INODES
  911. default y
  912. help
  913. Enable the eventfd() system call that allows to receive both
  914. kernel notification (ie. KAIO) or userspace notifications.
  915. If unsure, say Y.
  916. config SHMEM
  917. bool "Use full shmem filesystem" if EXPERT
  918. default y
  919. depends on MMU
  920. help
  921. The shmem is an internal filesystem used to manage shared memory.
  922. It is backed by swap and manages resource limits. It is also exported
  923. to userspace as tmpfs if TMPFS is enabled. Disabling this
  924. option replaces shmem and tmpfs with the much simpler ramfs code,
  925. which may be appropriate on small systems without swap.
  926. config AIO
  927. bool "Enable AIO support" if EXPERT
  928. default y
  929. help
  930. This option enables POSIX asynchronous I/O which may by used
  931. by some high performance threaded applications. Disabling
  932. this option saves about 7k.
  933. config HAVE_PERF_EVENTS
  934. bool
  935. help
  936. See tools/perf/design.txt for details.
  937. config PERF_USE_VMALLOC
  938. bool
  939. help
  940. See tools/perf/design.txt for details
  941. menu "Kernel Performance Events And Counters"
  942. config PERF_EVENTS
  943. bool "Kernel performance events and counters"
  944. default y if (PROFILING || PERF_COUNTERS)
  945. depends on HAVE_PERF_EVENTS
  946. select ANON_INODES
  947. select IRQ_WORK
  948. help
  949. Enable kernel support for various performance events provided
  950. by software and hardware.
  951. Software events are supported either built-in or via the
  952. use of generic tracepoints.
  953. Most modern CPUs support performance events via performance
  954. counter registers. These registers count the number of certain
  955. types of hw events: such as instructions executed, cachemisses
  956. suffered, or branches mis-predicted - without slowing down the
  957. kernel or applications. These registers can also trigger interrupts
  958. when a threshold number of events have passed - and can thus be
  959. used to profile the code that runs on that CPU.
  960. The Linux Performance Event subsystem provides an abstraction of
  961. these software and hardware event capabilities, available via a
  962. system call and used by the "perf" utility in tools/perf/. It
  963. provides per task and per CPU counters, and it provides event
  964. capabilities on top of those.
  965. Say Y if unsure.
  966. config PERF_COUNTERS
  967. bool "Kernel performance counters (old config option)"
  968. depends on HAVE_PERF_EVENTS
  969. help
  970. This config has been obsoleted by the PERF_EVENTS
  971. config option - please see that one for details.
  972. It has no effect on the kernel whether you enable
  973. it or not, it is a compatibility placeholder.
  974. Say N if unsure.
  975. config DEBUG_PERF_USE_VMALLOC
  976. default n
  977. bool "Debug: use vmalloc to back perf mmap() buffers"
  978. depends on PERF_EVENTS && DEBUG_KERNEL
  979. select PERF_USE_VMALLOC
  980. help
  981. Use vmalloc memory to back perf mmap() buffers.
  982. Mostly useful for debugging the vmalloc code on platforms
  983. that don't require it.
  984. Say N if unsure.
  985. endmenu
  986. config VM_EVENT_COUNTERS
  987. default y
  988. bool "Enable VM event counters for /proc/vmstat" if EXPERT
  989. help
  990. VM event counters are needed for event counts to be shown.
  991. This option allows the disabling of the VM event counters
  992. on EXPERT systems. /proc/vmstat will only show page counts
  993. if VM event counters are disabled.
  994. config PCI_QUIRKS
  995. default y
  996. bool "Enable PCI quirk workarounds" if EXPERT
  997. depends on PCI
  998. help
  999. This enables workarounds for various PCI chipset
  1000. bugs/quirks. Disable this only if your target machine is
  1001. unaffected by PCI quirks.
  1002. config SLUB_DEBUG
  1003. default y
  1004. bool "Enable SLUB debugging support" if EXPERT
  1005. depends on SLUB && SYSFS
  1006. help
  1007. SLUB has extensive debug support features. Disabling these can
  1008. result in significant savings in code size. This also disables
  1009. SLUB sysfs support. /sys/slab will not exist and there will be
  1010. no support for cache validation etc.
  1011. config COMPAT_BRK
  1012. bool "Disable heap randomization"
  1013. default y
  1014. help
  1015. Randomizing heap placement makes heap exploits harder, but it
  1016. also breaks ancient binaries (including anything libc5 based).
  1017. This option changes the bootup default to heap randomization
  1018. disabled, and can be overridden at runtime by setting
  1019. /proc/sys/kernel/randomize_va_space to 2.
  1020. On non-ancient distros (post-2000 ones) N is usually a safe choice.
  1021. choice
  1022. prompt "Choose SLAB allocator"
  1023. default SLUB
  1024. help
  1025. This option allows to select a slab allocator.
  1026. config SLAB
  1027. bool "SLAB"
  1028. help
  1029. The regular slab allocator that is established and known to work
  1030. well in all environments. It organizes cache hot objects in
  1031. per cpu and per node queues.
  1032. config SLUB
  1033. bool "SLUB (Unqueued Allocator)"
  1034. help
  1035. SLUB is a slab allocator that minimizes cache line usage
  1036. instead of managing queues of cached objects (SLAB approach).
  1037. Per cpu caching is realized using slabs of objects instead
  1038. of queues of objects. SLUB can use memory efficiently
  1039. and has enhanced diagnostics. SLUB is the default choice for
  1040. a slab allocator.
  1041. config SLOB
  1042. depends on EXPERT
  1043. bool "SLOB (Simple Allocator)"
  1044. help
  1045. SLOB replaces the stock allocator with a drastically simpler
  1046. allocator. SLOB is generally more space efficient but
  1047. does not perform as well on large systems.
  1048. endchoice
  1049. config MMAP_ALLOW_UNINITIALIZED
  1050. bool "Allow mmapped anonymous memory to be uninitialized"
  1051. depends on EXPERT && !MMU
  1052. default n
  1053. help
  1054. Normally, and according to the Linux spec, anonymous memory obtained
  1055. from mmap() has it's contents cleared before it is passed to
  1056. userspace. Enabling this config option allows you to request that
  1057. mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
  1058. providing a huge performance boost. If this option is not enabled,
  1059. then the flag will be ignored.
  1060. This is taken advantage of by uClibc's malloc(), and also by
  1061. ELF-FDPIC binfmt's brk and stack allocator.
  1062. Because of the obvious security issues, this option should only be
  1063. enabled on embedded devices where you control what is run in
  1064. userspace. Since that isn't generally a problem on no-MMU systems,
  1065. it is normally safe to say Y here.
  1066. See Documentation/nommu-mmap.txt for more information.
  1067. config PROFILING
  1068. bool "Profiling support"
  1069. help
  1070. Say Y here to enable the extended profiling support mechanisms used
  1071. by profilers such as OProfile.
  1072. #
  1073. # Place an empty function call at each tracepoint site. Can be
  1074. # dynamically changed for a probe function.
  1075. #
  1076. config TRACEPOINTS
  1077. bool
  1078. source "arch/Kconfig"
  1079. endmenu # General setup
  1080. config HAVE_GENERIC_DMA_COHERENT
  1081. bool
  1082. default n
  1083. config SLABINFO
  1084. bool
  1085. depends on PROC_FS
  1086. depends on SLAB || SLUB_DEBUG
  1087. default y
  1088. config RT_MUTEXES
  1089. boolean
  1090. config BASE_SMALL
  1091. int
  1092. default 0 if BASE_FULL
  1093. default 1 if !BASE_FULL
  1094. menuconfig MODULES
  1095. bool "Enable loadable module support"
  1096. help
  1097. Kernel modules are small pieces of compiled code which can
  1098. be inserted in the running kernel, rather than being
  1099. permanently built into the kernel. You use the "modprobe"
  1100. tool to add (and sometimes remove) them. If you say Y here,
  1101. many parts of the kernel can be built as modules (by
  1102. answering M instead of Y where indicated): this is most
  1103. useful for infrequently used options which are not required
  1104. for booting. For more information, see the man pages for
  1105. modprobe, lsmod, modinfo, insmod and rmmod.
  1106. If you say Y here, you will need to run "make
  1107. modules_install" to put the modules under /lib/modules/
  1108. where modprobe can find them (you may need to be root to do
  1109. this).
  1110. If unsure, say Y.
  1111. if MODULES
  1112. config MODULE_FORCE_LOAD
  1113. bool "Forced module loading"
  1114. default n
  1115. help
  1116. Allow loading of modules without version information (ie. modprobe
  1117. --force). Forced module loading sets the 'F' (forced) taint flag and
  1118. is usually a really bad idea.
  1119. config MODULE_UNLOAD
  1120. bool "Module unloading"
  1121. help
  1122. Without this option you will not be able to unload any
  1123. modules (note that some modules may not be unloadable
  1124. anyway), which makes your kernel smaller, faster
  1125. and simpler. If unsure, say Y.
  1126. config MODULE_FORCE_UNLOAD
  1127. bool "Forced module unloading"
  1128. depends on MODULE_UNLOAD && EXPERIMENTAL
  1129. help
  1130. This option allows you to force a module to unload, even if the
  1131. kernel believes it is unsafe: the kernel will remove the module
  1132. without waiting for anyone to stop using it (using the -f option to
  1133. rmmod). This is mainly for kernel developers and desperate users.
  1134. If unsure, say N.
  1135. config MODVERSIONS
  1136. bool "Module versioning support"
  1137. help
  1138. Usually, you have to use modules compiled with your kernel.
  1139. Saying Y here makes it sometimes possible to use modules
  1140. compiled for different kernels, by adding enough information
  1141. to the modules to (hopefully) spot any changes which would
  1142. make them incompatible with the kernel you are running. If
  1143. unsure, say N.
  1144. config MODULE_SRCVERSION_ALL
  1145. bool "Source checksum for all modules"
  1146. help
  1147. Modules which contain a MODULE_VERSION get an extra "srcversion"
  1148. field inserted into their modinfo section, which contains a
  1149. sum of the source files which made it. This helps maintainers
  1150. see exactly which source was used to build a module (since
  1151. others sometimes change the module source without updating
  1152. the version). With this option, such a "srcversion" field
  1153. will be created for all modules. If unsure, say N.
  1154. endif # MODULES
  1155. config INIT_ALL_POSSIBLE
  1156. bool
  1157. help
  1158. Back when each arch used to define their own cpu_online_map and
  1159. cpu_possible_map, some of them chose to initialize cpu_possible_map
  1160. with all 1s, and others with all 0s. When they were centralised,
  1161. it was better to provide this option than to break all the archs
  1162. and have several arch maintainers pursuing me down dark alleys.
  1163. config STOP_MACHINE
  1164. bool
  1165. default y
  1166. depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
  1167. help
  1168. Need stop_machine() primitive.
  1169. source "block/Kconfig"
  1170. config PREEMPT_NOTIFIERS
  1171. bool
  1172. config PADATA
  1173. depends on SMP
  1174. bool
  1175. source "kernel/Kconfig.locks"