Kconfig 52 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. config HAVE_IRQ_WORK
  20. bool
  21. config IRQ_WORK
  22. bool
  23. depends on HAVE_IRQ_WORK
  24. config BUILDTIME_EXTABLE_SORT
  25. bool
  26. menu "General setup"
  27. config EXPERIMENTAL
  28. bool "Prompt for development and/or incomplete code/drivers"
  29. ---help---
  30. Some of the various things that Linux supports (such as network
  31. drivers, file systems, network protocols, etc.) can be in a state
  32. of development where the functionality, stability, or the level of
  33. testing is not yet high enough for general use. This is usually
  34. known as the "alpha-test" phase among developers. If a feature is
  35. currently in alpha-test, then the developers usually discourage
  36. uninformed widespread use of this feature by the general public to
  37. avoid "Why doesn't this work?" type mail messages. However, active
  38. testing and use of these systems is welcomed. Just be aware that it
  39. may not meet the normal level of reliability or it may fail to work
  40. in some special cases. Detailed bug reports from people familiar
  41. with the kernel internals are usually welcomed by the developers
  42. (before submitting bug reports, please read the documents
  43. <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
  44. <file:Documentation/BUG-HUNTING>, and
  45. <file:Documentation/oops-tracing.txt> in the kernel source).
  46. This option will also make obsoleted drivers available. These are
  47. drivers that have been replaced by something else, and/or are
  48. scheduled to be removed in a future kernel release.
  49. Unless you intend to help test and develop a feature or driver that
  50. falls into this category, or you have a situation that requires
  51. using these features, you should probably say N here, which will
  52. cause the configurator to present you with fewer choices. If
  53. you say Y here, you will be offered the choice of using features or
  54. drivers that are currently considered to be in the alpha-test phase.
  55. config BROKEN
  56. bool
  57. config BROKEN_ON_SMP
  58. bool
  59. depends on BROKEN || !SMP
  60. default y
  61. config INIT_ENV_ARG_LIMIT
  62. int
  63. default 32 if !UML
  64. default 128 if UML
  65. help
  66. Maximum of each of the number of arguments and environment
  67. variables passed to init from the kernel command line.
  68. config CROSS_COMPILE
  69. string "Cross-compiler tool prefix"
  70. help
  71. Same as running 'make CROSS_COMPILE=prefix-' but stored for
  72. default make runs in this kernel build directory. You don't
  73. need to set this unless you want the configured kernel build
  74. directory to select the cross-compiler automatically.
  75. config LOCALVERSION
  76. string "Local version - append to kernel release"
  77. help
  78. Append an extra string to the end of your kernel version.
  79. This will show up when you type uname, for example.
  80. The string you set here will be appended after the contents of
  81. any files with a filename matching localversion* in your
  82. object and source tree, in that order. Your total string can
  83. be a maximum of 64 characters.
  84. config LOCALVERSION_AUTO
  85. bool "Automatically append version information to the version string"
  86. default y
  87. help
  88. This will try to automatically determine if the current tree is a
  89. release tree by looking for git tags that belong to the current
  90. top of tree revision.
  91. A string of the format -gxxxxxxxx will be added to the localversion
  92. if a git-based tree is found. The string generated by this will be
  93. appended after any matching localversion* files, and after the value
  94. set in CONFIG_LOCALVERSION.
  95. (The actual string used here is the first eight characters produced
  96. by running the command:
  97. $ git rev-parse --verify HEAD
  98. which is done within the script "scripts/setlocalversion".)
  99. config HAVE_KERNEL_GZIP
  100. bool
  101. config HAVE_KERNEL_BZIP2
  102. bool
  103. config HAVE_KERNEL_LZMA
  104. bool
  105. config HAVE_KERNEL_XZ
  106. bool
  107. config HAVE_KERNEL_LZO
  108. bool
  109. choice
  110. prompt "Kernel compression mode"
  111. default KERNEL_GZIP
  112. depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
  113. help
  114. The linux kernel is a kind of self-extracting executable.
  115. Several compression algorithms are available, which differ
  116. in efficiency, compression and decompression speed.
  117. Compression speed is only relevant when building a kernel.
  118. Decompression speed is relevant at each boot.
  119. If you have any problems with bzip2 or lzma compressed
  120. kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
  121. version of this functionality (bzip2 only), for 2.4, was
  122. supplied by Christian Ludwig)
  123. High compression options are mostly useful for users, who
  124. are low on disk space (embedded systems), but for whom ram
  125. size matters less.
  126. If in doubt, select 'gzip'
  127. config KERNEL_GZIP
  128. bool "Gzip"
  129. depends on HAVE_KERNEL_GZIP
  130. help
  131. The old and tried gzip compression. It provides a good balance
  132. between compression ratio and decompression speed.
  133. config KERNEL_BZIP2
  134. bool "Bzip2"
  135. depends on HAVE_KERNEL_BZIP2
  136. help
  137. Its compression ratio and speed is intermediate.
  138. Decompression speed is slowest among the choices. The kernel
  139. size is about 10% smaller with bzip2, in comparison to gzip.
  140. Bzip2 uses a large amount of memory. For modern kernels you
  141. will need at least 8MB RAM or more for booting.
  142. config KERNEL_LZMA
  143. bool "LZMA"
  144. depends on HAVE_KERNEL_LZMA
  145. help
  146. This compression algorithm's ratio is best. Decompression speed
  147. is between gzip and bzip2. Compression is slowest.
  148. The kernel size is about 33% smaller with LZMA in comparison to gzip.
  149. config KERNEL_XZ
  150. bool "XZ"
  151. depends on HAVE_KERNEL_XZ
  152. help
  153. XZ uses the LZMA2 algorithm and instruction set specific
  154. BCJ filters which can improve compression ratio of executable
  155. code. The size of the kernel is about 30% smaller with XZ in
  156. comparison to gzip. On architectures for which there is a BCJ
  157. filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
  158. will create a few percent smaller kernel than plain LZMA.
  159. The speed is about the same as with LZMA: The decompression
  160. speed of XZ is better than that of bzip2 but worse than gzip
  161. and LZO. Compression is slow.
  162. config KERNEL_LZO
  163. bool "LZO"
  164. depends on HAVE_KERNEL_LZO
  165. help
  166. Its compression ratio is the poorest among the choices. The kernel
  167. size is about 10% bigger than gzip; however its speed
  168. (both compression and decompression) is the fastest.
  169. endchoice
  170. config DEFAULT_HOSTNAME
  171. string "Default hostname"
  172. default "(none)"
  173. help
  174. This option determines the default system hostname before userspace
  175. calls sethostname(2). The kernel traditionally uses "(none)" here,
  176. but you may wish to use a different default here to make a minimal
  177. system more usable with less configuration.
  178. config SWAP
  179. bool "Support for paging of anonymous memory (swap)"
  180. depends on MMU && BLOCK
  181. default y
  182. help
  183. This option allows you to choose whether you want to have support
  184. for so called swap devices or swap files in your kernel that are
  185. used to provide more virtual memory than the actual RAM present
  186. in your computer. If unsure say Y.
  187. config SYSVIPC
  188. bool "System V IPC"
  189. ---help---
  190. Inter Process Communication is a suite of library functions and
  191. system calls which let processes (running programs) synchronize and
  192. exchange information. It is generally considered to be a good thing,
  193. and some programs won't run unless you say Y here. In particular, if
  194. you want to run the DOS emulator dosemu under Linux (read the
  195. DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
  196. you'll need to say Y here.
  197. You can find documentation about IPC with "info ipc" and also in
  198. section 6.4 of the Linux Programmer's Guide, available from
  199. <http://www.tldp.org/guides.html>.
  200. config SYSVIPC_SYSCTL
  201. bool
  202. depends on SYSVIPC
  203. depends on SYSCTL
  204. default y
  205. config POSIX_MQUEUE
  206. bool "POSIX Message Queues"
  207. depends on NET && EXPERIMENTAL
  208. ---help---
  209. POSIX variant of message queues is a part of IPC. In POSIX message
  210. queues every message has a priority which decides about succession
  211. of receiving it by a process. If you want to compile and run
  212. programs written e.g. for Solaris with use of its POSIX message
  213. queues (functions mq_*) say Y here.
  214. POSIX message queues are visible as a filesystem called 'mqueue'
  215. and can be mounted somewhere if you want to do filesystem
  216. operations on message queues.
  217. If unsure, say Y.
  218. config POSIX_MQUEUE_SYSCTL
  219. bool
  220. depends on POSIX_MQUEUE
  221. depends on SYSCTL
  222. default y
  223. config BSD_PROCESS_ACCT
  224. bool "BSD Process Accounting"
  225. help
  226. If you say Y here, a user level program will be able to instruct the
  227. kernel (via a special system call) to write process accounting
  228. information to a file: whenever a process exits, information about
  229. that process will be appended to the file by the kernel. The
  230. information includes things such as creation time, owning user,
  231. command name, memory usage, controlling terminal etc. (the complete
  232. list is in the struct acct in <file:include/linux/acct.h>). It is
  233. up to the user level program to do useful things with this
  234. information. This is generally a good idea, so say Y.
  235. config BSD_PROCESS_ACCT_V3
  236. bool "BSD Process Accounting version 3 file format"
  237. depends on BSD_PROCESS_ACCT
  238. default n
  239. help
  240. If you say Y here, the process accounting information is written
  241. in a new file format that also logs the process IDs of each
  242. process and it's parent. Note that this file format is incompatible
  243. with previous v0/v1/v2 file formats, so you will need updated tools
  244. for processing it. A preliminary version of these tools is available
  245. at <http://www.gnu.org/software/acct/>.
  246. config FHANDLE
  247. bool "open by fhandle syscalls"
  248. select EXPORTFS
  249. help
  250. If you say Y here, a user level program will be able to map
  251. file names to handle and then later use the handle for
  252. different file system operations. This is useful in implementing
  253. userspace file servers, which now track files using handles instead
  254. of names. The handle would remain the same even if file names
  255. get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
  256. syscalls.
  257. config TASKSTATS
  258. bool "Export task/process statistics through netlink (EXPERIMENTAL)"
  259. depends on NET
  260. default n
  261. help
  262. Export selected statistics for tasks/processes through the
  263. generic netlink interface. Unlike BSD process accounting, the
  264. statistics are available during the lifetime of tasks/processes as
  265. responses to commands. Like BSD accounting, they are sent to user
  266. space on task exit.
  267. Say N if unsure.
  268. config TASK_DELAY_ACCT
  269. bool "Enable per-task delay accounting (EXPERIMENTAL)"
  270. depends on TASKSTATS
  271. help
  272. Collect information on time spent by a task waiting for system
  273. resources like cpu, synchronous block I/O completion and swapping
  274. in pages. Such statistics can help in setting a task's priorities
  275. relative to other tasks for cpu, io, rss limits etc.
  276. Say N if unsure.
  277. config TASK_XACCT
  278. bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
  279. depends on TASKSTATS
  280. help
  281. Collect extended task accounting data and send the data
  282. to userland for processing over the taskstats interface.
  283. Say N if unsure.
  284. config TASK_IO_ACCOUNTING
  285. bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
  286. depends on TASK_XACCT
  287. help
  288. Collect information on the number of bytes of storage I/O which this
  289. task has caused.
  290. Say N if unsure.
  291. config AUDIT
  292. bool "Auditing support"
  293. depends on NET
  294. help
  295. Enable auditing infrastructure that can be used with another
  296. kernel subsystem, such as SELinux (which requires this for
  297. logging of avc messages output). Does not do system-call
  298. auditing without CONFIG_AUDITSYSCALL.
  299. config AUDITSYSCALL
  300. bool "Enable system-call auditing support"
  301. depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || (ARM && AEABI && !OABI_COMPAT))
  302. default y if SECURITY_SELINUX
  303. help
  304. Enable low-overhead system-call auditing infrastructure that
  305. can be used independently or with another kernel subsystem,
  306. such as SELinux.
  307. config AUDIT_WATCH
  308. def_bool y
  309. depends on AUDITSYSCALL
  310. select FSNOTIFY
  311. config AUDIT_TREE
  312. def_bool y
  313. depends on AUDITSYSCALL
  314. select FSNOTIFY
  315. config AUDIT_LOGINUID_IMMUTABLE
  316. bool "Make audit loginuid immutable"
  317. depends on AUDIT
  318. help
  319. The config option toggles if a task setting its loginuid requires
  320. CAP_SYS_AUDITCONTROL or if that task should require no special permissions
  321. but should instead only allow setting its loginuid if it was never
  322. previously set. On systems which use systemd or a similar central
  323. process to restart login services this should be set to true. On older
  324. systems in which an admin would typically have to directly stop and
  325. start processes this should be set to false. Setting this to true allows
  326. one to drop potentially dangerous capabilites from the login tasks,
  327. but may not be backwards compatible with older init systems.
  328. source "kernel/irq/Kconfig"
  329. source "kernel/time/Kconfig"
  330. menu "RCU Subsystem"
  331. choice
  332. prompt "RCU Implementation"
  333. default TREE_RCU
  334. config TREE_RCU
  335. bool "Tree-based hierarchical RCU"
  336. depends on !PREEMPT && SMP
  337. help
  338. This option selects the RCU implementation that is
  339. designed for very large SMP system with hundreds or
  340. thousands of CPUs. It also scales down nicely to
  341. smaller systems.
  342. config TREE_PREEMPT_RCU
  343. bool "Preemptible tree-based hierarchical RCU"
  344. depends on PREEMPT && SMP
  345. help
  346. This option selects the RCU implementation that is
  347. designed for very large SMP systems with hundreds or
  348. thousands of CPUs, but for which real-time response
  349. is also required. It also scales down nicely to
  350. smaller systems.
  351. config TINY_RCU
  352. bool "UP-only small-memory-footprint RCU"
  353. depends on !PREEMPT && !SMP
  354. help
  355. This option selects the RCU implementation that is
  356. designed for UP systems from which real-time response
  357. is not required. This option greatly reduces the
  358. memory footprint of RCU.
  359. config TINY_PREEMPT_RCU
  360. bool "Preemptible UP-only small-memory-footprint RCU"
  361. depends on PREEMPT && !SMP
  362. help
  363. This option selects the RCU implementation that is designed
  364. for real-time UP systems. This option greatly reduces the
  365. memory footprint of RCU.
  366. endchoice
  367. config PREEMPT_RCU
  368. def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
  369. help
  370. This option enables preemptible-RCU code that is common between
  371. the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
  372. config RCU_USER_QS
  373. bool "Consider userspace as in RCU extended quiescent state"
  374. depends on HAVE_RCU_USER_QS && SMP
  375. help
  376. This option sets hooks on kernel / userspace boundaries and
  377. puts RCU in extended quiescent state when the CPU runs in
  378. userspace. It means that when a CPU runs in userspace, it is
  379. excluded from the global RCU state machine and thus doesn't
  380. to keep the timer tick on for RCU.
  381. Unless you want to hack and help the development of the full
  382. tickless feature, you shouldn't enable this option. It adds
  383. unnecessary overhead.
  384. If unsure say N
  385. config RCU_USER_QS_FORCE
  386. bool "Force userspace extended QS by default"
  387. depends on RCU_USER_QS
  388. help
  389. Set the hooks in user/kernel boundaries by default in order to
  390. test this feature that treats userspace as an extended quiescent
  391. state until we have a real user like a full adaptive nohz option.
  392. Unless you want to hack and help the development of the full
  393. tickless feature, you shouldn't enable this option. It adds
  394. unnecessary overhead.
  395. If unsure say N
  396. config RCU_FANOUT
  397. int "Tree-based hierarchical RCU fanout value"
  398. range 2 64 if 64BIT
  399. range 2 32 if !64BIT
  400. depends on TREE_RCU || TREE_PREEMPT_RCU
  401. default 64 if 64BIT
  402. default 32 if !64BIT
  403. help
  404. This option controls the fanout of hierarchical implementations
  405. of RCU, allowing RCU to work efficiently on machines with
  406. large numbers of CPUs. This value must be at least the fourth
  407. root of NR_CPUS, which allows NR_CPUS to be insanely large.
  408. The default value of RCU_FANOUT should be used for production
  409. systems, but if you are stress-testing the RCU implementation
  410. itself, small RCU_FANOUT values allow you to test large-system
  411. code paths on small(er) systems.
  412. Select a specific number if testing RCU itself.
  413. Take the default if unsure.
  414. config RCU_FANOUT_LEAF
  415. int "Tree-based hierarchical RCU leaf-level fanout value"
  416. range 2 RCU_FANOUT if 64BIT
  417. range 2 RCU_FANOUT if !64BIT
  418. depends on TREE_RCU || TREE_PREEMPT_RCU
  419. default 16
  420. help
  421. This option controls the leaf-level fanout of hierarchical
  422. implementations of RCU, and allows trading off cache misses
  423. against lock contention. Systems that synchronize their
  424. scheduling-clock interrupts for energy-efficiency reasons will
  425. want the default because the smaller leaf-level fanout keeps
  426. lock contention levels acceptably low. Very large systems
  427. (hundreds or thousands of CPUs) will instead want to set this
  428. value to the maximum value possible in order to reduce the
  429. number of cache misses incurred during RCU's grace-period
  430. initialization. These systems tend to run CPU-bound, and thus
  431. are not helped by synchronized interrupts, and thus tend to
  432. skew them, which reduces lock contention enough that large
  433. leaf-level fanouts work well.
  434. Select a specific number if testing RCU itself.
  435. Select the maximum permissible value for large systems.
  436. Take the default if unsure.
  437. config RCU_FANOUT_EXACT
  438. bool "Disable tree-based hierarchical RCU auto-balancing"
  439. depends on TREE_RCU || TREE_PREEMPT_RCU
  440. default n
  441. help
  442. This option forces use of the exact RCU_FANOUT value specified,
  443. regardless of imbalances in the hierarchy. This is useful for
  444. testing RCU itself, and might one day be useful on systems with
  445. strong NUMA behavior.
  446. Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
  447. Say N if unsure.
  448. config RCU_FAST_NO_HZ
  449. bool "Accelerate last non-dyntick-idle CPU's grace periods"
  450. depends on NO_HZ && SMP
  451. default n
  452. help
  453. This option causes RCU to attempt to accelerate grace periods
  454. in order to allow CPUs to enter dynticks-idle state more
  455. quickly. On the other hand, this option increases the overhead
  456. of the dynticks-idle checking, particularly on systems with
  457. large numbers of CPUs.
  458. Say Y if energy efficiency is critically important, particularly
  459. if you have relatively few CPUs.
  460. Say N if you are unsure.
  461. config TREE_RCU_TRACE
  462. def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
  463. select DEBUG_FS
  464. help
  465. This option provides tracing for the TREE_RCU and
  466. TREE_PREEMPT_RCU implementations, permitting Makefile to
  467. trivially select kernel/rcutree_trace.c.
  468. config RCU_BOOST
  469. bool "Enable RCU priority boosting"
  470. depends on RT_MUTEXES && PREEMPT_RCU
  471. default n
  472. help
  473. This option boosts the priority of preempted RCU readers that
  474. block the current preemptible RCU grace period for too long.
  475. This option also prevents heavy loads from blocking RCU
  476. callback invocation for all flavors of RCU.
  477. Say Y here if you are working with real-time apps or heavy loads
  478. Say N here if you are unsure.
  479. config RCU_BOOST_PRIO
  480. int "Real-time priority to boost RCU readers to"
  481. range 1 99
  482. depends on RCU_BOOST
  483. default 1
  484. help
  485. This option specifies the real-time priority to which long-term
  486. preempted RCU readers are to be boosted. If you are working
  487. with a real-time application that has one or more CPU-bound
  488. threads running at a real-time priority level, you should set
  489. RCU_BOOST_PRIO to a priority higher then the highest-priority
  490. real-time CPU-bound thread. The default RCU_BOOST_PRIO value
  491. of 1 is appropriate in the common case, which is real-time
  492. applications that do not have any CPU-bound threads.
  493. Some real-time applications might not have a single real-time
  494. thread that saturates a given CPU, but instead might have
  495. multiple real-time threads that, taken together, fully utilize
  496. that CPU. In this case, you should set RCU_BOOST_PRIO to
  497. a priority higher than the lowest-priority thread that is
  498. conspiring to prevent the CPU from running any non-real-time
  499. tasks. For example, if one thread at priority 10 and another
  500. thread at priority 5 are between themselves fully consuming
  501. the CPU time on a given CPU, then RCU_BOOST_PRIO should be
  502. set to priority 6 or higher.
  503. Specify the real-time priority, or take the default if unsure.
  504. config RCU_BOOST_DELAY
  505. int "Milliseconds to delay boosting after RCU grace-period start"
  506. range 0 3000
  507. depends on RCU_BOOST
  508. default 500
  509. help
  510. This option specifies the time to wait after the beginning of
  511. a given grace period before priority-boosting preempted RCU
  512. readers blocking that grace period. Note that any RCU reader
  513. blocking an expedited RCU grace period is boosted immediately.
  514. Accept the default if unsure.
  515. endmenu # "RCU Subsystem"
  516. config IKCONFIG
  517. tristate "Kernel .config support"
  518. ---help---
  519. This option enables the complete Linux kernel ".config" file
  520. contents to be saved in the kernel. It provides documentation
  521. of which kernel options are used in a running kernel or in an
  522. on-disk kernel. This information can be extracted from the kernel
  523. image file with the script scripts/extract-ikconfig and used as
  524. input to rebuild the current kernel or to build another kernel.
  525. It can also be extracted from a running kernel by reading
  526. /proc/config.gz if enabled (below).
  527. config IKCONFIG_PROC
  528. bool "Enable access to .config through /proc/config.gz"
  529. depends on IKCONFIG && PROC_FS
  530. ---help---
  531. This option enables access to the kernel configuration file
  532. through /proc/config.gz.
  533. config LOG_BUF_SHIFT
  534. int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
  535. range 12 21
  536. default 17
  537. help
  538. Select kernel log buffer size as a power of 2.
  539. Examples:
  540. 17 => 128 KB
  541. 16 => 64 KB
  542. 15 => 32 KB
  543. 14 => 16 KB
  544. 13 => 8 KB
  545. 12 => 4 KB
  546. #
  547. # Architectures with an unreliable sched_clock() should select this:
  548. #
  549. config HAVE_UNSTABLE_SCHED_CLOCK
  550. bool
  551. menuconfig CGROUPS
  552. boolean "Control Group support"
  553. depends on EVENTFD
  554. help
  555. This option adds support for grouping sets of processes together, for
  556. use with process control subsystems such as Cpusets, CFS, memory
  557. controls or device isolation.
  558. See
  559. - Documentation/scheduler/sched-design-CFS.txt (CFS)
  560. - Documentation/cgroups/ (features for grouping, isolation
  561. and resource control)
  562. Say N if unsure.
  563. if CGROUPS
  564. config CGROUP_DEBUG
  565. bool "Example debug cgroup subsystem"
  566. default n
  567. help
  568. This option enables a simple cgroup subsystem that
  569. exports useful debugging information about the cgroups
  570. framework.
  571. Say N if unsure.
  572. config CGROUP_FREEZER
  573. bool "Freezer cgroup subsystem"
  574. help
  575. Provides a way to freeze and unfreeze all tasks in a
  576. cgroup.
  577. config CGROUP_DEVICE
  578. bool "Device controller for cgroups"
  579. help
  580. Provides a cgroup implementing whitelists for devices which
  581. a process in the cgroup can mknod or open.
  582. config CPUSETS
  583. bool "Cpuset support"
  584. help
  585. This option will let you create and manage CPUSETs which
  586. allow dynamically partitioning a system into sets of CPUs and
  587. Memory Nodes and assigning tasks to run only within those sets.
  588. This is primarily useful on large SMP or NUMA systems.
  589. Say N if unsure.
  590. config PROC_PID_CPUSET
  591. bool "Include legacy /proc/<pid>/cpuset file"
  592. depends on CPUSETS
  593. default y
  594. config CGROUP_CPUACCT
  595. bool "Simple CPU accounting cgroup subsystem"
  596. help
  597. Provides a simple Resource Controller for monitoring the
  598. total CPU consumed by the tasks in a cgroup.
  599. config RESOURCE_COUNTERS
  600. bool "Resource counters"
  601. help
  602. This option enables controller independent resource accounting
  603. infrastructure that works with cgroups.
  604. config MEMCG
  605. bool "Memory Resource Controller for Control Groups"
  606. depends on RESOURCE_COUNTERS
  607. select MM_OWNER
  608. help
  609. Provides a memory resource controller that manages both anonymous
  610. memory and page cache. (See Documentation/cgroups/memory.txt)
  611. Note that setting this option increases fixed memory overhead
  612. associated with each page of memory in the system. By this,
  613. 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
  614. usage tracking struct at boot. Total amount of this is printed out
  615. at boot.
  616. Only enable when you're ok with these trade offs and really
  617. sure you need the memory resource controller. Even when you enable
  618. this, you can set "cgroup_disable=memory" at your boot option to
  619. disable memory resource controller and you can avoid overheads.
  620. (and lose benefits of memory resource controller)
  621. This config option also selects MM_OWNER config option, which
  622. could in turn add some fork/exit overhead.
  623. config MEMCG_SWAP
  624. bool "Memory Resource Controller Swap Extension"
  625. depends on MEMCG && SWAP
  626. help
  627. Add swap management feature to memory resource controller. When you
  628. enable this, you can limit mem+swap usage per cgroup. In other words,
  629. when you disable this, memory resource controller has no cares to
  630. usage of swap...a process can exhaust all of the swap. This extension
  631. is useful when you want to avoid exhaustion swap but this itself
  632. adds more overheads and consumes memory for remembering information.
  633. Especially if you use 32bit system or small memory system, please
  634. be careful about enabling this. When memory resource controller
  635. is disabled by boot option, this will be automatically disabled and
  636. there will be no overhead from this. Even when you set this config=y,
  637. if boot option "swapaccount=0" is set, swap will not be accounted.
  638. Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
  639. size is 4096bytes, 512k per 1Gbytes of swap.
  640. config MEMCG_SWAP_ENABLED
  641. bool "Memory Resource Controller Swap Extension enabled by default"
  642. depends on MEMCG_SWAP
  643. default y
  644. help
  645. Memory Resource Controller Swap Extension comes with its price in
  646. a bigger memory consumption. General purpose distribution kernels
  647. which want to enable the feature but keep it disabled by default
  648. and let the user enable it by swapaccount boot command line
  649. parameter should have this option unselected.
  650. For those who want to have the feature enabled by default should
  651. select this option (if, for some reason, they need to disable it
  652. then swapaccount=0 does the trick).
  653. config MEMCG_KMEM
  654. bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
  655. depends on MEMCG && EXPERIMENTAL
  656. default n
  657. help
  658. The Kernel Memory extension for Memory Resource Controller can limit
  659. the amount of memory used by kernel objects in the system. Those are
  660. fundamentally different from the entities handled by the standard
  661. Memory Controller, which are page-based, and can be swapped. Users of
  662. the kmem extension can use it to guarantee that no group of processes
  663. will ever exhaust kernel resources alone.
  664. config CGROUP_HUGETLB
  665. bool "HugeTLB Resource Controller for Control Groups"
  666. depends on RESOURCE_COUNTERS && HUGETLB_PAGE && EXPERIMENTAL
  667. default n
  668. help
  669. Provides a cgroup Resource Controller for HugeTLB pages.
  670. When you enable this, you can put a per cgroup limit on HugeTLB usage.
  671. The limit is enforced during page fault. Since HugeTLB doesn't
  672. support page reclaim, enforcing the limit at page fault time implies
  673. that, the application will get SIGBUS signal if it tries to access
  674. HugeTLB pages beyond its limit. This requires the application to know
  675. beforehand how much HugeTLB pages it would require for its use. The
  676. control group is tracked in the third page lru pointer. This means
  677. that we cannot use the controller with huge page less than 3 pages.
  678. config CGROUP_PERF
  679. bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
  680. depends on PERF_EVENTS && CGROUPS
  681. help
  682. This option extends the per-cpu mode to restrict monitoring to
  683. threads which belong to the cgroup specified and run on the
  684. designated cpu.
  685. Say N if unsure.
  686. menuconfig CGROUP_SCHED
  687. bool "Group CPU scheduler"
  688. default n
  689. help
  690. This feature lets CPU scheduler recognize task groups and control CPU
  691. bandwidth allocation to such task groups. It uses cgroups to group
  692. tasks.
  693. if CGROUP_SCHED
  694. config FAIR_GROUP_SCHED
  695. bool "Group scheduling for SCHED_OTHER"
  696. depends on CGROUP_SCHED
  697. default CGROUP_SCHED
  698. config CFS_BANDWIDTH
  699. bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
  700. depends on EXPERIMENTAL
  701. depends on FAIR_GROUP_SCHED
  702. default n
  703. help
  704. This option allows users to define CPU bandwidth rates (limits) for
  705. tasks running within the fair group scheduler. Groups with no limit
  706. set are considered to be unconstrained and will run with no
  707. restriction.
  708. See tip/Documentation/scheduler/sched-bwc.txt for more information.
  709. config RT_GROUP_SCHED
  710. bool "Group scheduling for SCHED_RR/FIFO"
  711. depends on EXPERIMENTAL
  712. depends on CGROUP_SCHED
  713. default n
  714. help
  715. This feature lets you explicitly allocate real CPU bandwidth
  716. to task groups. If enabled, it will also make it impossible to
  717. schedule realtime tasks for non-root users until you allocate
  718. realtime bandwidth for them.
  719. See Documentation/scheduler/sched-rt-group.txt for more information.
  720. endif #CGROUP_SCHED
  721. config BLK_CGROUP
  722. bool "Block IO controller"
  723. depends on BLOCK
  724. default n
  725. ---help---
  726. Generic block IO controller cgroup interface. This is the common
  727. cgroup interface which should be used by various IO controlling
  728. policies.
  729. Currently, CFQ IO scheduler uses it to recognize task groups and
  730. control disk bandwidth allocation (proportional time slice allocation)
  731. to such task groups. It is also used by bio throttling logic in
  732. block layer to implement upper limit in IO rates on a device.
  733. This option only enables generic Block IO controller infrastructure.
  734. One needs to also enable actual IO controlling logic/policy. For
  735. enabling proportional weight division of disk bandwidth in CFQ, set
  736. CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
  737. CONFIG_BLK_DEV_THROTTLING=y.
  738. See Documentation/cgroups/blkio-controller.txt for more information.
  739. config DEBUG_BLK_CGROUP
  740. bool "Enable Block IO controller debugging"
  741. depends on BLK_CGROUP
  742. default n
  743. ---help---
  744. Enable some debugging help. Currently it exports additional stat
  745. files in a cgroup which can be useful for debugging.
  746. endif # CGROUPS
  747. config CHECKPOINT_RESTORE
  748. bool "Checkpoint/restore support" if EXPERT
  749. default n
  750. help
  751. Enables additional kernel features in a sake of checkpoint/restore.
  752. In particular it adds auxiliary prctl codes to setup process text,
  753. data and heap segment sizes, and a few additional /proc filesystem
  754. entries.
  755. If unsure, say N here.
  756. menuconfig NAMESPACES
  757. bool "Namespaces support" if EXPERT
  758. default !EXPERT
  759. help
  760. Provides the way to make tasks work with different objects using
  761. the same id. For example same IPC id may refer to different objects
  762. or same user id or pid may refer to different tasks when used in
  763. different namespaces.
  764. if NAMESPACES
  765. config UTS_NS
  766. bool "UTS namespace"
  767. default y
  768. help
  769. In this namespace tasks see different info provided with the
  770. uname() system call
  771. config IPC_NS
  772. bool "IPC namespace"
  773. depends on (SYSVIPC || POSIX_MQUEUE)
  774. default y
  775. help
  776. In this namespace tasks work with IPC ids which correspond to
  777. different IPC objects in different namespaces.
  778. config USER_NS
  779. bool "User namespace (EXPERIMENTAL)"
  780. depends on EXPERIMENTAL
  781. depends on UIDGID_CONVERTED
  782. select UIDGID_STRICT_TYPE_CHECKS
  783. default n
  784. help
  785. This allows containers, i.e. vservers, to use user namespaces
  786. to provide different user info for different servers.
  787. If unsure, say N.
  788. config PID_NS
  789. bool "PID Namespaces"
  790. default y
  791. help
  792. Support process id namespaces. This allows having multiple
  793. processes with the same pid as long as they are in different
  794. pid namespaces. This is a building block of containers.
  795. config NET_NS
  796. bool "Network namespace"
  797. depends on NET
  798. default y
  799. help
  800. Allow user space to create what appear to be multiple instances
  801. of the network stack.
  802. endif # NAMESPACES
  803. config UIDGID_CONVERTED
  804. # True if all of the selected software conmponents are known
  805. # to have uid_t and gid_t converted to kuid_t and kgid_t
  806. # where appropriate and are otherwise safe to use with
  807. # the user namespace.
  808. bool
  809. default y
  810. # List of kernel pieces that need user namespace work
  811. # Features
  812. depends on SYSVIPC = n
  813. depends on IMA = n
  814. depends on EVM = n
  815. depends on KEYS = n
  816. depends on AUDIT = n
  817. depends on AUDITSYSCALL = n
  818. depends on TASKSTATS = n
  819. depends on TRACING = n
  820. depends on FS_POSIX_ACL = n
  821. depends on QUOTA = n
  822. depends on QUOTACTL = n
  823. depends on DEBUG_CREDENTIALS = n
  824. depends on BSD_PROCESS_ACCT = n
  825. depends on DRM = n
  826. depends on PROC_EVENTS = n
  827. # Networking
  828. depends on NET = n
  829. depends on NET_9P = n
  830. depends on IPX = n
  831. depends on PHONET = n
  832. depends on NET_CLS_FLOW = n
  833. depends on NETFILTER_XT_MATCH_OWNER = n
  834. depends on NETFILTER_XT_MATCH_RECENT = n
  835. depends on NETFILTER_XT_TARGET_LOG = n
  836. depends on NETFILTER_NETLINK_LOG = n
  837. depends on INET = n
  838. depends on IPV6 = n
  839. depends on IP_SCTP = n
  840. depends on AF_RXRPC = n
  841. depends on LLC2 = n
  842. depends on NET_KEY = n
  843. depends on INET_DIAG = n
  844. depends on DNS_RESOLVER = n
  845. depends on AX25 = n
  846. depends on ATALK = n
  847. # Filesystems
  848. depends on USB_DEVICEFS = n
  849. depends on USB_GADGETFS = n
  850. depends on USB_FUNCTIONFS = n
  851. depends on DEVTMPFS = n
  852. depends on XENFS = n
  853. depends on 9P_FS = n
  854. depends on ADFS_FS = n
  855. depends on AFFS_FS = n
  856. depends on AFS_FS = n
  857. depends on AUTOFS4_FS = n
  858. depends on BEFS_FS = n
  859. depends on BFS_FS = n
  860. depends on BTRFS_FS = n
  861. depends on CEPH_FS = n
  862. depends on CIFS = n
  863. depends on CODA_FS = n
  864. depends on CONFIGFS_FS = n
  865. depends on CRAMFS = n
  866. depends on DEBUG_FS = n
  867. depends on ECRYPT_FS = n
  868. depends on EFS_FS = n
  869. depends on EXOFS_FS = n
  870. depends on FAT_FS = n
  871. depends on FUSE_FS = n
  872. depends on GFS2_FS = n
  873. depends on HFS_FS = n
  874. depends on HFSPLUS_FS = n
  875. depends on HPFS_FS = n
  876. depends on HUGETLBFS = n
  877. depends on ISO9660_FS = n
  878. depends on JFFS2_FS = n
  879. depends on JFS_FS = n
  880. depends on LOGFS = n
  881. depends on MINIX_FS = n
  882. depends on NCP_FS = n
  883. depends on NFSD = n
  884. depends on NFS_FS = n
  885. depends on NILFS2_FS = n
  886. depends on NTFS_FS = n
  887. depends on OCFS2_FS = n
  888. depends on OMFS_FS = n
  889. depends on QNX4FS_FS = n
  890. depends on QNX6FS_FS = n
  891. depends on REISERFS_FS = n
  892. depends on SQUASHFS = n
  893. depends on SYSV_FS = n
  894. depends on UBIFS_FS = n
  895. depends on UDF_FS = n
  896. depends on UFS_FS = n
  897. depends on VXFS_FS = n
  898. depends on XFS_FS = n
  899. depends on !UML || HOSTFS = n
  900. # The rare drivers that won't build
  901. depends on AIRO = n
  902. depends on AIRO_CS = n
  903. depends on TUN = n
  904. depends on INFINIBAND_QIB = n
  905. depends on BLK_DEV_LOOP = n
  906. depends on ANDROID_BINDER_IPC = n
  907. # Security modules
  908. depends on SECURITY_TOMOYO = n
  909. depends on SECURITY_APPARMOR = n
  910. config UIDGID_STRICT_TYPE_CHECKS
  911. bool "Require conversions between uid/gids and their internal representation"
  912. depends on UIDGID_CONVERTED
  913. default n
  914. help
  915. While the nececessary conversions are being added to all subsystems this option allows
  916. the code to continue to build for unconverted subsystems.
  917. Say Y here if you want the strict type checking enabled
  918. config SCHED_AUTOGROUP
  919. bool "Automatic process group scheduling"
  920. select EVENTFD
  921. select CGROUPS
  922. select CGROUP_SCHED
  923. select FAIR_GROUP_SCHED
  924. help
  925. This option optimizes the scheduler for common desktop workloads by
  926. automatically creating and populating task groups. This separation
  927. of workloads isolates aggressive CPU burners (like build jobs) from
  928. desktop applications. Task group autogeneration is currently based
  929. upon task session.
  930. config MM_OWNER
  931. bool
  932. config SYSFS_DEPRECATED
  933. bool "Enable deprecated sysfs features to support old userspace tools"
  934. depends on SYSFS
  935. default n
  936. help
  937. This option adds code that switches the layout of the "block" class
  938. devices, to not show up in /sys/class/block/, but only in
  939. /sys/block/.
  940. This switch is only active when the sysfs.deprecated=1 boot option is
  941. passed or the SYSFS_DEPRECATED_V2 option is set.
  942. This option allows new kernels to run on old distributions and tools,
  943. which might get confused by /sys/class/block/. Since 2007/2008 all
  944. major distributions and tools handle this just fine.
  945. Recent distributions and userspace tools after 2009/2010 depend on
  946. the existence of /sys/class/block/, and will not work with this
  947. option enabled.
  948. Only if you are using a new kernel on an old distribution, you might
  949. need to say Y here.
  950. config SYSFS_DEPRECATED_V2
  951. bool "Enable deprecated sysfs features by default"
  952. default n
  953. depends on SYSFS
  954. depends on SYSFS_DEPRECATED
  955. help
  956. Enable deprecated sysfs by default.
  957. See the CONFIG_SYSFS_DEPRECATED option for more details about this
  958. option.
  959. Only if you are using a new kernel on an old distribution, you might
  960. need to say Y here. Even then, odds are you would not need it
  961. enabled, you can always pass the boot option if absolutely necessary.
  962. config RELAY
  963. bool "Kernel->user space relay support (formerly relayfs)"
  964. help
  965. This option enables support for relay interface support in
  966. certain file systems (such as debugfs).
  967. It is designed to provide an efficient mechanism for tools and
  968. facilities to relay large amounts of data from kernel space to
  969. user space.
  970. If unsure, say N.
  971. config BLK_DEV_INITRD
  972. bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
  973. depends on BROKEN || !FRV
  974. help
  975. The initial RAM filesystem is a ramfs which is loaded by the
  976. boot loader (loadlin or lilo) and that is mounted as root
  977. before the normal boot procedure. It is typically used to
  978. load modules needed to mount the "real" root file system,
  979. etc. See <file:Documentation/initrd.txt> for details.
  980. If RAM disk support (BLK_DEV_RAM) is also included, this
  981. also enables initial RAM disk (initrd) support and adds
  982. 15 Kbytes (more on some other architectures) to the kernel size.
  983. If unsure say Y.
  984. if BLK_DEV_INITRD
  985. source "usr/Kconfig"
  986. endif
  987. config CC_OPTIMIZE_FOR_SIZE
  988. bool "Optimize for size"
  989. help
  990. Enabling this option will pass "-Os" instead of "-O2" to gcc
  991. resulting in a smaller kernel.
  992. If unsure, say Y.
  993. config SYSCTL
  994. bool
  995. config ANON_INODES
  996. bool
  997. menuconfig EXPERT
  998. bool "Configure standard kernel features (expert users)"
  999. # Unhide debug options, to make the on-by-default options visible
  1000. select DEBUG_KERNEL
  1001. help
  1002. This option allows certain base kernel options and settings
  1003. to be disabled or tweaked. This is for specialized
  1004. environments which can tolerate a "non-standard" kernel.
  1005. Only use this if you really know what you are doing.
  1006. config UID16
  1007. bool "Enable 16-bit UID system calls" if EXPERT
  1008. depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
  1009. default y
  1010. help
  1011. This enables the legacy 16-bit UID syscall wrappers.
  1012. config SYSCTL_SYSCALL
  1013. bool "Sysctl syscall support" if EXPERT
  1014. depends on PROC_SYSCTL
  1015. default n
  1016. select SYSCTL
  1017. ---help---
  1018. sys_sysctl uses binary paths that have been found challenging
  1019. to properly maintain and use. The interface in /proc/sys
  1020. using paths with ascii names is now the primary path to this
  1021. information.
  1022. Almost nothing using the binary sysctl interface so if you are
  1023. trying to save some space it is probably safe to disable this,
  1024. making your kernel marginally smaller.
  1025. If unsure say N here.
  1026. config KALLSYMS
  1027. bool "Load all symbols for debugging/ksymoops" if EXPERT
  1028. default y
  1029. help
  1030. Say Y here to let the kernel print out symbolic crash information and
  1031. symbolic stack backtraces. This increases the size of the kernel
  1032. somewhat, as all symbols have to be loaded into the kernel image.
  1033. config KALLSYMS_ALL
  1034. bool "Include all symbols in kallsyms"
  1035. depends on DEBUG_KERNEL && KALLSYMS
  1036. help
  1037. Normally kallsyms only contains the symbols of functions for nicer
  1038. OOPS messages and backtraces (i.e., symbols from the text and inittext
  1039. sections). This is sufficient for most cases. And only in very rare
  1040. cases (e.g., when a debugger is used) all symbols are required (e.g.,
  1041. names of variables from the data sections, etc).
  1042. This option makes sure that all symbols are loaded into the kernel
  1043. image (i.e., symbols from all sections) in cost of increased kernel
  1044. size (depending on the kernel configuration, it may be 300KiB or
  1045. something like this).
  1046. Say N unless you really need all symbols.
  1047. config HOTPLUG
  1048. bool "Support for hot-pluggable devices" if EXPERT
  1049. default y
  1050. help
  1051. This option is provided for the case where no hotplug or uevent
  1052. capabilities is wanted by the kernel. You should only consider
  1053. disabling this option for embedded systems that do not use modules, a
  1054. dynamic /dev tree, or dynamic device discovery. Just say Y.
  1055. config PRINTK
  1056. default y
  1057. bool "Enable support for printk" if EXPERT
  1058. help
  1059. This option enables normal printk support. Removing it
  1060. eliminates most of the message strings from the kernel image
  1061. and makes the kernel more or less silent. As this makes it
  1062. very difficult to diagnose system problems, saying N here is
  1063. strongly discouraged.
  1064. config BUG
  1065. bool "BUG() support" if EXPERT
  1066. default y
  1067. help
  1068. Disabling this option eliminates support for BUG and WARN, reducing
  1069. the size of your kernel image and potentially quietly ignoring
  1070. numerous fatal conditions. You should only consider disabling this
  1071. option for embedded systems with no facilities for reporting errors.
  1072. Just say Y.
  1073. config ELF_CORE
  1074. default y
  1075. bool "Enable ELF core dumps" if EXPERT
  1076. help
  1077. Enable support for generating core dumps. Disabling saves about 4k.
  1078. config PCSPKR_PLATFORM
  1079. bool "Enable PC-Speaker support" if EXPERT
  1080. depends on HAVE_PCSPKR_PLATFORM
  1081. select I8253_LOCK
  1082. default y
  1083. help
  1084. This option allows to disable the internal PC-Speaker
  1085. support, saving some memory.
  1086. config HAVE_PCSPKR_PLATFORM
  1087. bool
  1088. config BASE_FULL
  1089. default y
  1090. bool "Enable full-sized data structures for core" if EXPERT
  1091. help
  1092. Disabling this option reduces the size of miscellaneous core
  1093. kernel data structures. This saves memory on small machines,
  1094. but may reduce performance.
  1095. config FUTEX
  1096. bool "Enable futex support" if EXPERT
  1097. default y
  1098. select RT_MUTEXES
  1099. help
  1100. Disabling this option will cause the kernel to be built without
  1101. support for "fast userspace mutexes". The resulting kernel may not
  1102. run glibc-based applications correctly.
  1103. config EPOLL
  1104. bool "Enable eventpoll support" if EXPERT
  1105. default y
  1106. select ANON_INODES
  1107. help
  1108. Disabling this option will cause the kernel to be built without
  1109. support for epoll family of system calls.
  1110. config SIGNALFD
  1111. bool "Enable signalfd() system call" if EXPERT
  1112. select ANON_INODES
  1113. default y
  1114. help
  1115. Enable the signalfd() system call that allows to receive signals
  1116. on a file descriptor.
  1117. If unsure, say Y.
  1118. config TIMERFD
  1119. bool "Enable timerfd() system call" if EXPERT
  1120. select ANON_INODES
  1121. default y
  1122. help
  1123. Enable the timerfd() system call that allows to receive timer
  1124. events on a file descriptor.
  1125. If unsure, say Y.
  1126. config EVENTFD
  1127. bool "Enable eventfd() system call" if EXPERT
  1128. select ANON_INODES
  1129. default y
  1130. help
  1131. Enable the eventfd() system call that allows to receive both
  1132. kernel notification (ie. KAIO) or userspace notifications.
  1133. If unsure, say Y.
  1134. config SHMEM
  1135. bool "Use full shmem filesystem" if EXPERT
  1136. default y
  1137. depends on MMU
  1138. help
  1139. The shmem is an internal filesystem used to manage shared memory.
  1140. It is backed by swap and manages resource limits. It is also exported
  1141. to userspace as tmpfs if TMPFS is enabled. Disabling this
  1142. option replaces shmem and tmpfs with the much simpler ramfs code,
  1143. which may be appropriate on small systems without swap.
  1144. config AIO
  1145. bool "Enable AIO support" if EXPERT
  1146. default y
  1147. help
  1148. This option enables POSIX asynchronous I/O which may by used
  1149. by some high performance threaded applications. Disabling
  1150. this option saves about 7k.
  1151. config EMBEDDED
  1152. bool "Embedded system"
  1153. select EXPERT
  1154. help
  1155. This option should be enabled if compiling the kernel for
  1156. an embedded system so certain expert options are available
  1157. for configuration.
  1158. config HAVE_PERF_EVENTS
  1159. bool
  1160. help
  1161. See tools/perf/design.txt for details.
  1162. config PERF_USE_VMALLOC
  1163. bool
  1164. help
  1165. See tools/perf/design.txt for details
  1166. menu "Kernel Performance Events And Counters"
  1167. config PERF_EVENTS
  1168. bool "Kernel performance events and counters"
  1169. default y if PROFILING
  1170. depends on HAVE_PERF_EVENTS
  1171. select ANON_INODES
  1172. select IRQ_WORK
  1173. help
  1174. Enable kernel support for various performance events provided
  1175. by software and hardware.
  1176. Software events are supported either built-in or via the
  1177. use of generic tracepoints.
  1178. Most modern CPUs support performance events via performance
  1179. counter registers. These registers count the number of certain
  1180. types of hw events: such as instructions executed, cachemisses
  1181. suffered, or branches mis-predicted - without slowing down the
  1182. kernel or applications. These registers can also trigger interrupts
  1183. when a threshold number of events have passed - and can thus be
  1184. used to profile the code that runs on that CPU.
  1185. The Linux Performance Event subsystem provides an abstraction of
  1186. these software and hardware event capabilities, available via a
  1187. system call and used by the "perf" utility in tools/perf/. It
  1188. provides per task and per CPU counters, and it provides event
  1189. capabilities on top of those.
  1190. Say Y if unsure.
  1191. config DEBUG_PERF_USE_VMALLOC
  1192. default n
  1193. bool "Debug: use vmalloc to back perf mmap() buffers"
  1194. depends on PERF_EVENTS && DEBUG_KERNEL
  1195. select PERF_USE_VMALLOC
  1196. help
  1197. Use vmalloc memory to back perf mmap() buffers.
  1198. Mostly useful for debugging the vmalloc code on platforms
  1199. that don't require it.
  1200. Say N if unsure.
  1201. endmenu
  1202. config VM_EVENT_COUNTERS
  1203. default y
  1204. bool "Enable VM event counters for /proc/vmstat" if EXPERT
  1205. help
  1206. VM event counters are needed for event counts to be shown.
  1207. This option allows the disabling of the VM event counters
  1208. on EXPERT systems. /proc/vmstat will only show page counts
  1209. if VM event counters are disabled.
  1210. config PCI_QUIRKS
  1211. default y
  1212. bool "Enable PCI quirk workarounds" if EXPERT
  1213. depends on PCI
  1214. help
  1215. This enables workarounds for various PCI chipset
  1216. bugs/quirks. Disable this only if your target machine is
  1217. unaffected by PCI quirks.
  1218. config SLUB_DEBUG
  1219. default y
  1220. bool "Enable SLUB debugging support" if EXPERT
  1221. depends on SLUB && SYSFS
  1222. help
  1223. SLUB has extensive debug support features. Disabling these can
  1224. result in significant savings in code size. This also disables
  1225. SLUB sysfs support. /sys/slab will not exist and there will be
  1226. no support for cache validation etc.
  1227. config COMPAT_BRK
  1228. bool "Disable heap randomization"
  1229. default y
  1230. help
  1231. Randomizing heap placement makes heap exploits harder, but it
  1232. also breaks ancient binaries (including anything libc5 based).
  1233. This option changes the bootup default to heap randomization
  1234. disabled, and can be overridden at runtime by setting
  1235. /proc/sys/kernel/randomize_va_space to 2.
  1236. On non-ancient distros (post-2000 ones) N is usually a safe choice.
  1237. choice
  1238. prompt "Choose SLAB allocator"
  1239. default SLUB
  1240. help
  1241. This option allows to select a slab allocator.
  1242. config SLAB
  1243. bool "SLAB"
  1244. help
  1245. The regular slab allocator that is established and known to work
  1246. well in all environments. It organizes cache hot objects in
  1247. per cpu and per node queues.
  1248. config SLUB
  1249. bool "SLUB (Unqueued Allocator)"
  1250. help
  1251. SLUB is a slab allocator that minimizes cache line usage
  1252. instead of managing queues of cached objects (SLAB approach).
  1253. Per cpu caching is realized using slabs of objects instead
  1254. of queues of objects. SLUB can use memory efficiently
  1255. and has enhanced diagnostics. SLUB is the default choice for
  1256. a slab allocator.
  1257. config SLOB
  1258. depends on EXPERT
  1259. bool "SLOB (Simple Allocator)"
  1260. help
  1261. SLOB replaces the stock allocator with a drastically simpler
  1262. allocator. SLOB is generally more space efficient but
  1263. does not perform as well on large systems.
  1264. endchoice
  1265. config MMAP_ALLOW_UNINITIALIZED
  1266. bool "Allow mmapped anonymous memory to be uninitialized"
  1267. depends on EXPERT && !MMU
  1268. default n
  1269. help
  1270. Normally, and according to the Linux spec, anonymous memory obtained
  1271. from mmap() has it's contents cleared before it is passed to
  1272. userspace. Enabling this config option allows you to request that
  1273. mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
  1274. providing a huge performance boost. If this option is not enabled,
  1275. then the flag will be ignored.
  1276. This is taken advantage of by uClibc's malloc(), and also by
  1277. ELF-FDPIC binfmt's brk and stack allocator.
  1278. Because of the obvious security issues, this option should only be
  1279. enabled on embedded devices where you control what is run in
  1280. userspace. Since that isn't generally a problem on no-MMU systems,
  1281. it is normally safe to say Y here.
  1282. See Documentation/nommu-mmap.txt for more information.
  1283. config PROFILING
  1284. bool "Profiling support"
  1285. help
  1286. Say Y here to enable the extended profiling support mechanisms used
  1287. by profilers such as OProfile.
  1288. #
  1289. # Place an empty function call at each tracepoint site. Can be
  1290. # dynamically changed for a probe function.
  1291. #
  1292. config TRACEPOINTS
  1293. bool
  1294. source "arch/Kconfig"
  1295. endmenu # General setup
  1296. config HAVE_GENERIC_DMA_COHERENT
  1297. bool
  1298. default n
  1299. config SLABINFO
  1300. bool
  1301. depends on PROC_FS
  1302. depends on SLAB || SLUB_DEBUG
  1303. default y
  1304. config RT_MUTEXES
  1305. boolean
  1306. config BASE_SMALL
  1307. int
  1308. default 0 if BASE_FULL
  1309. default 1 if !BASE_FULL
  1310. menuconfig MODULES
  1311. bool "Enable loadable module support"
  1312. help
  1313. Kernel modules are small pieces of compiled code which can
  1314. be inserted in the running kernel, rather than being
  1315. permanently built into the kernel. You use the "modprobe"
  1316. tool to add (and sometimes remove) them. If you say Y here,
  1317. many parts of the kernel can be built as modules (by
  1318. answering M instead of Y where indicated): this is most
  1319. useful for infrequently used options which are not required
  1320. for booting. For more information, see the man pages for
  1321. modprobe, lsmod, modinfo, insmod and rmmod.
  1322. If you say Y here, you will need to run "make
  1323. modules_install" to put the modules under /lib/modules/
  1324. where modprobe can find them (you may need to be root to do
  1325. this).
  1326. If unsure, say Y.
  1327. if MODULES
  1328. config MODULE_FORCE_LOAD
  1329. bool "Forced module loading"
  1330. default n
  1331. help
  1332. Allow loading of modules without version information (ie. modprobe
  1333. --force). Forced module loading sets the 'F' (forced) taint flag and
  1334. is usually a really bad idea.
  1335. config MODULE_UNLOAD
  1336. bool "Module unloading"
  1337. help
  1338. Without this option you will not be able to unload any
  1339. modules (note that some modules may not be unloadable
  1340. anyway), which makes your kernel smaller, faster
  1341. and simpler. If unsure, say Y.
  1342. config MODULE_FORCE_UNLOAD
  1343. bool "Forced module unloading"
  1344. depends on MODULE_UNLOAD && EXPERIMENTAL
  1345. help
  1346. This option allows you to force a module to unload, even if the
  1347. kernel believes it is unsafe: the kernel will remove the module
  1348. without waiting for anyone to stop using it (using the -f option to
  1349. rmmod). This is mainly for kernel developers and desperate users.
  1350. If unsure, say N.
  1351. config MODVERSIONS
  1352. bool "Module versioning support"
  1353. help
  1354. Usually, you have to use modules compiled with your kernel.
  1355. Saying Y here makes it sometimes possible to use modules
  1356. compiled for different kernels, by adding enough information
  1357. to the modules to (hopefully) spot any changes which would
  1358. make them incompatible with the kernel you are running. If
  1359. unsure, say N.
  1360. config MODULE_SRCVERSION_ALL
  1361. bool "Source checksum for all modules"
  1362. help
  1363. Modules which contain a MODULE_VERSION get an extra "srcversion"
  1364. field inserted into their modinfo section, which contains a
  1365. sum of the source files which made it. This helps maintainers
  1366. see exactly which source was used to build a module (since
  1367. others sometimes change the module source without updating
  1368. the version). With this option, such a "srcversion" field
  1369. will be created for all modules. If unsure, say N.
  1370. endif # MODULES
  1371. config INIT_ALL_POSSIBLE
  1372. bool
  1373. help
  1374. Back when each arch used to define their own cpu_online_mask and
  1375. cpu_possible_mask, some of them chose to initialize cpu_possible_mask
  1376. with all 1s, and others with all 0s. When they were centralised,
  1377. it was better to provide this option than to break all the archs
  1378. and have several arch maintainers pursuing me down dark alleys.
  1379. config STOP_MACHINE
  1380. bool
  1381. default y
  1382. depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
  1383. help
  1384. Need stop_machine() primitive.
  1385. source "block/Kconfig"
  1386. config PREEMPT_NOTIFIERS
  1387. bool
  1388. config PADATA
  1389. depends on SMP
  1390. bool
  1391. source "kernel/Kconfig.locks"