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 drivers that have been replaced by something else, and/or are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