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 drivers that have been replaced by something else, and/or are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. config RCU_USER_QS_FORCE
  382. bool "Force userspace extended QS by default"
  383. depends on RCU_USER_QS
  384. help
  385. Set the hooks in user/kernel boundaries by default in order to
  386. test this feature that treats userspace as an extended quiescent
  387. state until we have a real user like a full adaptive nohz option.
  388. config RCU_FANOUT
  389. int "Tree-based hierarchical RCU fanout value"
  390. range 2 64 if 64BIT
  391. range 2 32 if !64BIT
  392. depends on TREE_RCU || TREE_PREEMPT_RCU
  393. default 64 if 64BIT
  394. default 32 if !64BIT
  395. help
  396. This option controls the fanout of hierarchical implementations
  397. of RCU, allowing RCU to work efficiently on machines with
  398. large numbers of CPUs. This value must be at least the fourth
  399. root of NR_CPUS, which allows NR_CPUS to be insanely large.
  400. The default value of RCU_FANOUT should be used for production
  401. systems, but if you are stress-testing the RCU implementation
  402. itself, small RCU_FANOUT values allow you to test large-system
  403. code paths on small(er) systems.
  404. Select a specific number if testing RCU itself.
  405. Take the default if unsure.
  406. config RCU_FANOUT_LEAF
  407. int "Tree-based hierarchical RCU leaf-level fanout value"
  408. range 2 RCU_FANOUT if 64BIT
  409. range 2 RCU_FANOUT if !64BIT
  410. depends on TREE_RCU || TREE_PREEMPT_RCU
  411. default 16
  412. help
  413. This option controls the leaf-level fanout of hierarchical
  414. implementations of RCU, and allows trading off cache misses
  415. against lock contention. Systems that synchronize their
  416. scheduling-clock interrupts for energy-efficiency reasons will
  417. want the default because the smaller leaf-level fanout keeps
  418. lock contention levels acceptably low. Very large systems
  419. (hundreds or thousands of CPUs) will instead want to set this
  420. value to the maximum value possible in order to reduce the
  421. number of cache misses incurred during RCU's grace-period
  422. initialization. These systems tend to run CPU-bound, and thus
  423. are not helped by synchronized interrupts, and thus tend to
  424. skew them, which reduces lock contention enough that large
  425. leaf-level fanouts work well.
  426. Select a specific number if testing RCU itself.
  427. Select the maximum permissible value for large systems.
  428. Take the default if unsure.
  429. config RCU_FANOUT_EXACT
  430. bool "Disable tree-based hierarchical RCU auto-balancing"
  431. depends on TREE_RCU || TREE_PREEMPT_RCU
  432. default n
  433. help
  434. This option forces use of the exact RCU_FANOUT value specified,
  435. regardless of imbalances in the hierarchy. This is useful for
  436. testing RCU itself, and might one day be useful on systems with
  437. strong NUMA behavior.
  438. Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
  439. Say N if unsure.
  440. config RCU_FAST_NO_HZ
  441. bool "Accelerate last non-dyntick-idle CPU's grace periods"
  442. depends on NO_HZ && SMP
  443. default n
  444. help
  445. This option causes RCU to attempt to accelerate grace periods
  446. in order to allow CPUs to enter dynticks-idle state more
  447. quickly. On the other hand, this option increases the overhead
  448. of the dynticks-idle checking, particularly on systems with
  449. large numbers of CPUs.
  450. Say Y if energy efficiency is critically important, particularly
  451. if you have relatively few CPUs.
  452. Say N if you are unsure.
  453. config TREE_RCU_TRACE
  454. def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
  455. select DEBUG_FS
  456. help
  457. This option provides tracing for the TREE_RCU and
  458. TREE_PREEMPT_RCU implementations, permitting Makefile to
  459. trivially select kernel/rcutree_trace.c.
  460. config RCU_BOOST
  461. bool "Enable RCU priority boosting"
  462. depends on RT_MUTEXES && PREEMPT_RCU
  463. default n
  464. help
  465. This option boosts the priority of preempted RCU readers that
  466. block the current preemptible RCU grace period for too long.
  467. This option also prevents heavy loads from blocking RCU
  468. callback invocation for all flavors of RCU.
  469. Say Y here if you are working with real-time apps or heavy loads
  470. Say N here if you are unsure.
  471. config RCU_BOOST_PRIO
  472. int "Real-time priority to boost RCU readers to"
  473. range 1 99
  474. depends on RCU_BOOST
  475. default 1
  476. help
  477. This option specifies the real-time priority to which long-term
  478. preempted RCU readers are to be boosted. If you are working
  479. with a real-time application that has one or more CPU-bound
  480. threads running at a real-time priority level, you should set
  481. RCU_BOOST_PRIO to a priority higher then the highest-priority
  482. real-time CPU-bound thread. The default RCU_BOOST_PRIO value
  483. of 1 is appropriate in the common case, which is real-time
  484. applications that do not have any CPU-bound threads.
  485. Some real-time applications might not have a single real-time
  486. thread that saturates a given CPU, but instead might have
  487. multiple real-time threads that, taken together, fully utilize
  488. that CPU. In this case, you should set RCU_BOOST_PRIO to
  489. a priority higher than the lowest-priority thread that is
  490. conspiring to prevent the CPU from running any non-real-time
  491. tasks. For example, if one thread at priority 10 and another
  492. thread at priority 5 are between themselves fully consuming
  493. the CPU time on a given CPU, then RCU_BOOST_PRIO should be
  494. set to priority 6 or higher.
  495. Specify the real-time priority, or take the default if unsure.
  496. config RCU_BOOST_DELAY
  497. int "Milliseconds to delay boosting after RCU grace-period start"
  498. range 0 3000
  499. depends on RCU_BOOST
  500. default 500
  501. help
  502. This option specifies the time to wait after the beginning of
  503. a given grace period before priority-boosting preempted RCU
  504. readers blocking that grace period. Note that any RCU reader
  505. blocking an expedited RCU grace period is boosted immediately.
  506. Accept the default if unsure.
  507. endmenu # "RCU Subsystem"
  508. config IKCONFIG
  509. tristate "Kernel .config support"
  510. ---help---
  511. This option enables the complete Linux kernel ".config" file
  512. contents to be saved in the kernel. It provides documentation
  513. of which kernel options are used in a running kernel or in an
  514. on-disk kernel. This information can be extracted from the kernel
  515. image file with the script scripts/extract-ikconfig and used as
  516. input to rebuild the current kernel or to build another kernel.
  517. It can also be extracted from a running kernel by reading
  518. /proc/config.gz if enabled (below).
  519. config IKCONFIG_PROC
  520. bool "Enable access to .config through /proc/config.gz"
  521. depends on IKCONFIG && PROC_FS
  522. ---help---
  523. This option enables access to the kernel configuration file
  524. through /proc/config.gz.
  525. config LOG_BUF_SHIFT
  526. int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
  527. range 12 21
  528. default 17
  529. help
  530. Select kernel log buffer size as a power of 2.
  531. Examples:
  532. 17 => 128 KB
  533. 16 => 64 KB
  534. 15 => 32 KB
  535. 14 => 16 KB
  536. 13 => 8 KB
  537. 12 => 4 KB
  538. #
  539. # Architectures with an unreliable sched_clock() should select this:
  540. #
  541. config HAVE_UNSTABLE_SCHED_CLOCK
  542. bool
  543. menuconfig CGROUPS
  544. boolean "Control Group support"
  545. depends on EVENTFD
  546. help
  547. This option adds support for grouping sets of processes together, for
  548. use with process control subsystems such as Cpusets, CFS, memory
  549. controls or device isolation.
  550. See
  551. - Documentation/scheduler/sched-design-CFS.txt (CFS)
  552. - Documentation/cgroups/ (features for grouping, isolation
  553. and resource control)
  554. Say N if unsure.
  555. if CGROUPS
  556. config CGROUP_DEBUG
  557. bool "Example debug cgroup subsystem"
  558. default n
  559. help
  560. This option enables a simple cgroup subsystem that
  561. exports useful debugging information about the cgroups
  562. framework.
  563. Say N if unsure.
  564. config CGROUP_FREEZER
  565. bool "Freezer cgroup subsystem"
  566. help
  567. Provides a way to freeze and unfreeze all tasks in a
  568. cgroup.
  569. config CGROUP_DEVICE
  570. bool "Device controller for cgroups"
  571. help
  572. Provides a cgroup implementing whitelists for devices which
  573. a process in the cgroup can mknod or open.
  574. config CPUSETS
  575. bool "Cpuset support"
  576. help
  577. This option will let you create and manage CPUSETs which
  578. allow dynamically partitioning a system into sets of CPUs and
  579. Memory Nodes and assigning tasks to run only within those sets.
  580. This is primarily useful on large SMP or NUMA systems.
  581. Say N if unsure.
  582. config PROC_PID_CPUSET
  583. bool "Include legacy /proc/<pid>/cpuset file"
  584. depends on CPUSETS
  585. default y
  586. config CGROUP_CPUACCT
  587. bool "Simple CPU accounting cgroup subsystem"
  588. help
  589. Provides a simple Resource Controller for monitoring the
  590. total CPU consumed by the tasks in a cgroup.
  591. config RESOURCE_COUNTERS
  592. bool "Resource counters"
  593. help
  594. This option enables controller independent resource accounting
  595. infrastructure that works with cgroups.
  596. config MEMCG
  597. bool "Memory Resource Controller for Control Groups"
  598. depends on RESOURCE_COUNTERS
  599. select MM_OWNER
  600. help
  601. Provides a memory resource controller that manages both anonymous
  602. memory and page cache. (See Documentation/cgroups/memory.txt)
  603. Note that setting this option increases fixed memory overhead
  604. associated with each page of memory in the system. By this,
  605. 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
  606. usage tracking struct at boot. Total amount of this is printed out
  607. at boot.
  608. Only enable when you're ok with these trade offs and really
  609. sure you need the memory resource controller. Even when you enable
  610. this, you can set "cgroup_disable=memory" at your boot option to
  611. disable memory resource controller and you can avoid overheads.
  612. (and lose benefits of memory resource controller)
  613. This config option also selects MM_OWNER config option, which
  614. could in turn add some fork/exit overhead.
  615. config MEMCG_SWAP
  616. bool "Memory Resource Controller Swap Extension"
  617. depends on MEMCG && SWAP
  618. help
  619. Add swap management feature to memory resource controller. When you
  620. enable this, you can limit mem+swap usage per cgroup. In other words,
  621. when you disable this, memory resource controller has no cares to
  622. usage of swap...a process can exhaust all of the swap. This extension
  623. is useful when you want to avoid exhaustion swap but this itself
  624. adds more overheads and consumes memory for remembering information.
  625. Especially if you use 32bit system or small memory system, please
  626. be careful about enabling this. When memory resource controller
  627. is disabled by boot option, this will be automatically disabled and
  628. there will be no overhead from this. Even when you set this config=y,
  629. if boot option "swapaccount=0" is set, swap will not be accounted.
  630. Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
  631. size is 4096bytes, 512k per 1Gbytes of swap.
  632. config MEMCG_SWAP_ENABLED
  633. bool "Memory Resource Controller Swap Extension enabled by default"
  634. depends on MEMCG_SWAP
  635. default y
  636. help
  637. Memory Resource Controller Swap Extension comes with its price in
  638. a bigger memory consumption. General purpose distribution kernels
  639. which want to enable the feature but keep it disabled by default
  640. and let the user enable it by swapaccount boot command line
  641. parameter should have this option unselected.
  642. For those who want to have the feature enabled by default should
  643. select this option (if, for some reason, they need to disable it
  644. then swapaccount=0 does the trick).
  645. config MEMCG_KMEM
  646. bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
  647. depends on MEMCG && EXPERIMENTAL
  648. default n
  649. help
  650. The Kernel Memory extension for Memory Resource Controller can limit
  651. the amount of memory used by kernel objects in the system. Those are
  652. fundamentally different from the entities handled by the standard
  653. Memory Controller, which are page-based, and can be swapped. Users of
  654. the kmem extension can use it to guarantee that no group of processes
  655. will ever exhaust kernel resources alone.
  656. config CGROUP_HUGETLB
  657. bool "HugeTLB Resource Controller for Control Groups"
  658. depends on RESOURCE_COUNTERS && HUGETLB_PAGE && EXPERIMENTAL
  659. default n
  660. help
  661. Provides a cgroup Resource Controller for HugeTLB pages.
  662. When you enable this, you can put a per cgroup limit on HugeTLB usage.
  663. The limit is enforced during page fault. Since HugeTLB doesn't
  664. support page reclaim, enforcing the limit at page fault time implies
  665. that, the application will get SIGBUS signal if it tries to access
  666. HugeTLB pages beyond its limit. This requires the application to know
  667. beforehand how much HugeTLB pages it would require for its use. The
  668. control group is tracked in the third page lru pointer. This means
  669. that we cannot use the controller with huge page less than 3 pages.
  670. config CGROUP_PERF
  671. bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
  672. depends on PERF_EVENTS && CGROUPS
  673. help
  674. This option extends the per-cpu mode to restrict monitoring to
  675. threads which belong to the cgroup specified and run on the
  676. designated cpu.
  677. Say N if unsure.
  678. menuconfig CGROUP_SCHED
  679. bool "Group CPU scheduler"
  680. default n
  681. help
  682. This feature lets CPU scheduler recognize task groups and control CPU
  683. bandwidth allocation to such task groups. It uses cgroups to group
  684. tasks.
  685. if CGROUP_SCHED
  686. config FAIR_GROUP_SCHED
  687. bool "Group scheduling for SCHED_OTHER"
  688. depends on CGROUP_SCHED
  689. default CGROUP_SCHED
  690. config CFS_BANDWIDTH
  691. bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
  692. depends on EXPERIMENTAL
  693. depends on FAIR_GROUP_SCHED
  694. default n
  695. help
  696. This option allows users to define CPU bandwidth rates (limits) for
  697. tasks running within the fair group scheduler. Groups with no limit
  698. set are considered to be unconstrained and will run with no
  699. restriction.
  700. See tip/Documentation/scheduler/sched-bwc.txt for more information.
  701. config RT_GROUP_SCHED
  702. bool "Group scheduling for SCHED_RR/FIFO"
  703. depends on EXPERIMENTAL
  704. depends on CGROUP_SCHED
  705. default n
  706. help
  707. This feature lets you explicitly allocate real CPU bandwidth
  708. to task groups. If enabled, it will also make it impossible to
  709. schedule realtime tasks for non-root users until you allocate
  710. realtime bandwidth for them.
  711. See Documentation/scheduler/sched-rt-group.txt for more information.
  712. endif #CGROUP_SCHED
  713. config BLK_CGROUP
  714. bool "Block IO controller"
  715. depends on BLOCK
  716. default n
  717. ---help---
  718. Generic block IO controller cgroup interface. This is the common
  719. cgroup interface which should be used by various IO controlling
  720. policies.
  721. Currently, CFQ IO scheduler uses it to recognize task groups and
  722. control disk bandwidth allocation (proportional time slice allocation)
  723. to such task groups. It is also used by bio throttling logic in
  724. block layer to implement upper limit in IO rates on a device.
  725. This option only enables generic Block IO controller infrastructure.
  726. One needs to also enable actual IO controlling logic/policy. For
  727. enabling proportional weight division of disk bandwidth in CFQ, set
  728. CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
  729. CONFIG_BLK_DEV_THROTTLING=y.
  730. See Documentation/cgroups/blkio-controller.txt for more information.
  731. config DEBUG_BLK_CGROUP
  732. bool "Enable Block IO controller debugging"
  733. depends on BLK_CGROUP
  734. default n
  735. ---help---
  736. Enable some debugging help. Currently it exports additional stat
  737. files in a cgroup which can be useful for debugging.
  738. endif # CGROUPS
  739. config CHECKPOINT_RESTORE
  740. bool "Checkpoint/restore support" if EXPERT
  741. default n
  742. help
  743. Enables additional kernel features in a sake of checkpoint/restore.
  744. In particular it adds auxiliary prctl codes to setup process text,
  745. data and heap segment sizes, and a few additional /proc filesystem
  746. entries.
  747. If unsure, say N here.
  748. menuconfig NAMESPACES
  749. bool "Namespaces support" if EXPERT
  750. default !EXPERT
  751. help
  752. Provides the way to make tasks work with different objects using
  753. the same id. For example same IPC id may refer to different objects
  754. or same user id or pid may refer to different tasks when used in
  755. different namespaces.
  756. if NAMESPACES
  757. config UTS_NS
  758. bool "UTS namespace"
  759. default y
  760. help
  761. In this namespace tasks see different info provided with the
  762. uname() system call
  763. config IPC_NS
  764. bool "IPC namespace"
  765. depends on (SYSVIPC || POSIX_MQUEUE)
  766. default y
  767. help
  768. In this namespace tasks work with IPC ids which correspond to
  769. different IPC objects in different namespaces.
  770. config USER_NS
  771. bool "User namespace (EXPERIMENTAL)"
  772. depends on EXPERIMENTAL
  773. depends on UIDGID_CONVERTED
  774. select UIDGID_STRICT_TYPE_CHECKS
  775. default n
  776. help
  777. This allows containers, i.e. vservers, to use user namespaces
  778. to provide different user info for different servers.
  779. If unsure, say N.
  780. config PID_NS
  781. bool "PID Namespaces"
  782. default y
  783. help
  784. Support process id namespaces. This allows having multiple
  785. processes with the same pid as long as they are in different
  786. pid namespaces. This is a building block of containers.
  787. config NET_NS
  788. bool "Network namespace"
  789. depends on NET
  790. default y
  791. help
  792. Allow user space to create what appear to be multiple instances
  793. of the network stack.
  794. endif # NAMESPACES
  795. config UIDGID_CONVERTED
  796. # True if all of the selected software conmponents are known
  797. # to have uid_t and gid_t converted to kuid_t and kgid_t
  798. # where appropriate and are otherwise safe to use with
  799. # the user namespace.
  800. bool
  801. default y
  802. # List of kernel pieces that need user namespace work
  803. # Features
  804. depends on SYSVIPC = n
  805. depends on IMA = n
  806. depends on EVM = n
  807. depends on KEYS = n
  808. depends on AUDIT = n
  809. depends on AUDITSYSCALL = n
  810. depends on TASKSTATS = n
  811. depends on TRACING = n
  812. depends on FS_POSIX_ACL = n
  813. depends on QUOTA = n
  814. depends on QUOTACTL = n
  815. depends on DEBUG_CREDENTIALS = n
  816. depends on BSD_PROCESS_ACCT = n
  817. depends on DRM = n
  818. depends on PROC_EVENTS = n
  819. # Networking
  820. depends on NET = n
  821. depends on NET_9P = n
  822. depends on IPX = n
  823. depends on PHONET = n
  824. depends on NET_CLS_FLOW = n
  825. depends on NETFILTER_XT_MATCH_OWNER = n
  826. depends on NETFILTER_XT_MATCH_RECENT = n
  827. depends on NETFILTER_XT_TARGET_LOG = n
  828. depends on NETFILTER_NETLINK_LOG = n
  829. depends on INET = n
  830. depends on IPV6 = n
  831. depends on IP_SCTP = n
  832. depends on AF_RXRPC = n
  833. depends on LLC2 = n
  834. depends on NET_KEY = n
  835. depends on INET_DIAG = n
  836. depends on DNS_RESOLVER = n
  837. depends on AX25 = n
  838. depends on ATALK = n
  839. # Filesystems
  840. depends on USB_DEVICEFS = n
  841. depends on USB_GADGETFS = n
  842. depends on USB_FUNCTIONFS = n
  843. depends on DEVTMPFS = n
  844. depends on XENFS = n
  845. depends on 9P_FS = n
  846. depends on ADFS_FS = n
  847. depends on AFFS_FS = n
  848. depends on AFS_FS = n
  849. depends on AUTOFS4_FS = n
  850. depends on BEFS_FS = n
  851. depends on BFS_FS = n
  852. depends on BTRFS_FS = n
  853. depends on CEPH_FS = n
  854. depends on CIFS = n
  855. depends on CODA_FS = n
  856. depends on CONFIGFS_FS = n
  857. depends on CRAMFS = n
  858. depends on DEBUG_FS = n
  859. depends on ECRYPT_FS = n
  860. depends on EFS_FS = n
  861. depends on EXOFS_FS = n
  862. depends on FAT_FS = n
  863. depends on FUSE_FS = n
  864. depends on GFS2_FS = n
  865. depends on HFS_FS = n
  866. depends on HFSPLUS_FS = n
  867. depends on HPFS_FS = n
  868. depends on HUGETLBFS = n
  869. depends on ISO9660_FS = n
  870. depends on JFFS2_FS = n
  871. depends on JFS_FS = n
  872. depends on LOGFS = n
  873. depends on MINIX_FS = n
  874. depends on NCP_FS = n
  875. depends on NFSD = n
  876. depends on NFS_FS = n
  877. depends on NILFS2_FS = n
  878. depends on NTFS_FS = n
  879. depends on OCFS2_FS = n
  880. depends on OMFS_FS = n
  881. depends on QNX4FS_FS = n
  882. depends on QNX6FS_FS = n
  883. depends on REISERFS_FS = n
  884. depends on SQUASHFS = n
  885. depends on SYSV_FS = n
  886. depends on UBIFS_FS = n
  887. depends on UDF_FS = n
  888. depends on UFS_FS = n
  889. depends on VXFS_FS = n
  890. depends on XFS_FS = n
  891. depends on !UML || HOSTFS = n
  892. # The rare drivers that won't build
  893. depends on AIRO = n
  894. depends on AIRO_CS = n
  895. depends on TUN = n
  896. depends on INFINIBAND_QIB = n
  897. depends on BLK_DEV_LOOP = n
  898. depends on ANDROID_BINDER_IPC = n
  899. # Security modules
  900. depends on SECURITY_TOMOYO = n
  901. depends on SECURITY_APPARMOR = n
  902. config UIDGID_STRICT_TYPE_CHECKS
  903. bool "Require conversions between uid/gids and their internal representation"
  904. depends on UIDGID_CONVERTED
  905. default n
  906. help
  907. While the nececessary conversions are being added to all subsystems this option allows
  908. the code to continue to build for unconverted subsystems.
  909. Say Y here if you want the strict type checking enabled
  910. config SCHED_AUTOGROUP
  911. bool "Automatic process group scheduling"
  912. select EVENTFD
  913. select CGROUPS
  914. select CGROUP_SCHED
  915. select FAIR_GROUP_SCHED
  916. help
  917. This option optimizes the scheduler for common desktop workloads by
  918. automatically creating and populating task groups. This separation
  919. of workloads isolates aggressive CPU burners (like build jobs) from
  920. desktop applications. Task group autogeneration is currently based
  921. upon task session.
  922. config MM_OWNER
  923. bool
  924. config SYSFS_DEPRECATED
  925. bool "Enable deprecated sysfs features to support old userspace tools"
  926. depends on SYSFS
  927. default n
  928. help
  929. This option adds code that switches the layout of the "block" class
  930. devices, to not show up in /sys/class/block/, but only in
  931. /sys/block/.
  932. This switch is only active when the sysfs.deprecated=1 boot option is
  933. passed or the SYSFS_DEPRECATED_V2 option is set.
  934. This option allows new kernels to run on old distributions and tools,
  935. which might get confused by /sys/class/block/. Since 2007/2008 all
  936. major distributions and tools handle this just fine.
  937. Recent distributions and userspace tools after 2009/2010 depend on
  938. the existence of /sys/class/block/, and will not work with this
  939. option enabled.
  940. Only if you are using a new kernel on an old distribution, you might
  941. need to say Y here.
  942. config SYSFS_DEPRECATED_V2
  943. bool "Enable deprecated sysfs features by default"
  944. default n
  945. depends on SYSFS
  946. depends on SYSFS_DEPRECATED
  947. help
  948. Enable deprecated sysfs by default.
  949. See the CONFIG_SYSFS_DEPRECATED option for more details about this
  950. option.
  951. Only if you are using a new kernel on an old distribution, you might
  952. need to say Y here. Even then, odds are you would not need it
  953. enabled, you can always pass the boot option if absolutely necessary.
  954. config RELAY
  955. bool "Kernel->user space relay support (formerly relayfs)"
  956. help
  957. This option enables support for relay interface support in
  958. certain file systems (such as debugfs).
  959. It is designed to provide an efficient mechanism for tools and
  960. facilities to relay large amounts of data from kernel space to
  961. user space.
  962. If unsure, say N.
  963. config BLK_DEV_INITRD
  964. bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
  965. depends on BROKEN || !FRV
  966. help
  967. The initial RAM filesystem is a ramfs which is loaded by the
  968. boot loader (loadlin or lilo) and that is mounted as root
  969. before the normal boot procedure. It is typically used to
  970. load modules needed to mount the "real" root file system,
  971. etc. See <file:Documentation/initrd.txt> for details.
  972. If RAM disk support (BLK_DEV_RAM) is also included, this
  973. also enables initial RAM disk (initrd) support and adds
  974. 15 Kbytes (more on some other architectures) to the kernel size.
  975. If unsure say Y.
  976. if BLK_DEV_INITRD
  977. source "usr/Kconfig"
  978. endif
  979. config CC_OPTIMIZE_FOR_SIZE
  980. bool "Optimize for size"
  981. help
  982. Enabling this option will pass "-Os" instead of "-O2" to gcc
  983. resulting in a smaller kernel.
  984. If unsure, say Y.
  985. config SYSCTL
  986. bool
  987. config ANON_INODES
  988. bool
  989. menuconfig EXPERT
  990. bool "Configure standard kernel features (expert users)"
  991. # Unhide debug options, to make the on-by-default options visible
  992. select DEBUG_KERNEL
  993. help
  994. This option allows certain base kernel options and settings
  995. to be disabled or tweaked. This is for specialized
  996. environments which can tolerate a "non-standard" kernel.
  997. Only use this if you really know what you are doing.
  998. config UID16
  999. bool "Enable 16-bit UID system calls" if EXPERT
  1000. depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
  1001. default y
  1002. help
  1003. This enables the legacy 16-bit UID syscall wrappers.
  1004. config SYSCTL_SYSCALL
  1005. bool "Sysctl syscall support" if EXPERT
  1006. depends on PROC_SYSCTL
  1007. default n
  1008. select SYSCTL
  1009. ---help---
  1010. sys_sysctl uses binary paths that have been found challenging
  1011. to properly maintain and use. The interface in /proc/sys
  1012. using paths with ascii names is now the primary path to this
  1013. information.
  1014. Almost nothing using the binary sysctl interface so if you are
  1015. trying to save some space it is probably safe to disable this,
  1016. making your kernel marginally smaller.
  1017. If unsure say N here.
  1018. config KALLSYMS
  1019. bool "Load all symbols for debugging/ksymoops" if EXPERT
  1020. default y
  1021. help
  1022. Say Y here to let the kernel print out symbolic crash information and
  1023. symbolic stack backtraces. This increases the size of the kernel
  1024. somewhat, as all symbols have to be loaded into the kernel image.
  1025. config KALLSYMS_ALL
  1026. bool "Include all symbols in kallsyms"
  1027. depends on DEBUG_KERNEL && KALLSYMS
  1028. help
  1029. Normally kallsyms only contains the symbols of functions for nicer
  1030. OOPS messages and backtraces (i.e., symbols from the text and inittext
  1031. sections). This is sufficient for most cases. And only in very rare
  1032. cases (e.g., when a debugger is used) all symbols are required (e.g.,
  1033. names of variables from the data sections, etc).
  1034. This option makes sure that all symbols are loaded into the kernel
  1035. image (i.e., symbols from all sections) in cost of increased kernel
  1036. size (depending on the kernel configuration, it may be 300KiB or
  1037. something like this).
  1038. Say N unless you really need all symbols.
  1039. config HOTPLUG
  1040. bool "Support for hot-pluggable devices" if EXPERT
  1041. default y
  1042. help
  1043. This option is provided for the case where no hotplug or uevent
  1044. capabilities is wanted by the kernel. You should only consider
  1045. disabling this option for embedded systems that do not use modules, a
  1046. dynamic /dev tree, or dynamic device discovery. Just say Y.
  1047. config PRINTK
  1048. default y
  1049. bool "Enable support for printk" if EXPERT
  1050. help
  1051. This option enables normal printk support. Removing it
  1052. eliminates most of the message strings from the kernel image
  1053. and makes the kernel more or less silent. As this makes it
  1054. very difficult to diagnose system problems, saying N here is
  1055. strongly discouraged.
  1056. config BUG
  1057. bool "BUG() support" if EXPERT
  1058. default y
  1059. help
  1060. Disabling this option eliminates support for BUG and WARN, reducing
  1061. the size of your kernel image and potentially quietly ignoring
  1062. numerous fatal conditions. You should only consider disabling this
  1063. option for embedded systems with no facilities for reporting errors.
  1064. Just say Y.
  1065. config ELF_CORE
  1066. default y
  1067. bool "Enable ELF core dumps" if EXPERT
  1068. help
  1069. Enable support for generating core dumps. Disabling saves about 4k.
  1070. config PCSPKR_PLATFORM
  1071. bool "Enable PC-Speaker support" if EXPERT
  1072. depends on HAVE_PCSPKR_PLATFORM
  1073. select I8253_LOCK
  1074. default y
  1075. help
  1076. This option allows to disable the internal PC-Speaker
  1077. support, saving some memory.
  1078. config HAVE_PCSPKR_PLATFORM
  1079. bool
  1080. config BASE_FULL
  1081. default y
  1082. bool "Enable full-sized data structures for core" if EXPERT
  1083. help
  1084. Disabling this option reduces the size of miscellaneous core
  1085. kernel data structures. This saves memory on small machines,
  1086. but may reduce performance.
  1087. config FUTEX
  1088. bool "Enable futex support" if EXPERT
  1089. default y
  1090. select RT_MUTEXES
  1091. help
  1092. Disabling this option will cause the kernel to be built without
  1093. support for "fast userspace mutexes". The resulting kernel may not
  1094. run glibc-based applications correctly.
  1095. config EPOLL
  1096. bool "Enable eventpoll support" if EXPERT
  1097. default y
  1098. select ANON_INODES
  1099. help
  1100. Disabling this option will cause the kernel to be built without
  1101. support for epoll family of system calls.
  1102. config SIGNALFD
  1103. bool "Enable signalfd() system call" if EXPERT
  1104. select ANON_INODES
  1105. default y
  1106. help
  1107. Enable the signalfd() system call that allows to receive signals
  1108. on a file descriptor.
  1109. If unsure, say Y.
  1110. config TIMERFD
  1111. bool "Enable timerfd() system call" if EXPERT
  1112. select ANON_INODES
  1113. default y
  1114. help
  1115. Enable the timerfd() system call that allows to receive timer
  1116. events on a file descriptor.
  1117. If unsure, say Y.
  1118. config EVENTFD
  1119. bool "Enable eventfd() system call" if EXPERT
  1120. select ANON_INODES
  1121. default y
  1122. help
  1123. Enable the eventfd() system call that allows to receive both
  1124. kernel notification (ie. KAIO) or userspace notifications.
  1125. If unsure, say Y.
  1126. config SHMEM
  1127. bool "Use full shmem filesystem" if EXPERT
  1128. default y
  1129. depends on MMU
  1130. help
  1131. The shmem is an internal filesystem used to manage shared memory.
  1132. It is backed by swap and manages resource limits. It is also exported
  1133. to userspace as tmpfs if TMPFS is enabled. Disabling this
  1134. option replaces shmem and tmpfs with the much simpler ramfs code,
  1135. which may be appropriate on small systems without swap.
  1136. config AIO
  1137. bool "Enable AIO support" if EXPERT
  1138. default y
  1139. help
  1140. This option enables POSIX asynchronous I/O which may by used
  1141. by some high performance threaded applications. Disabling
  1142. this option saves about 7k.
  1143. config EMBEDDED
  1144. bool "Embedded system"
  1145. select EXPERT
  1146. help
  1147. This option should be enabled if compiling the kernel for
  1148. an embedded system so certain expert options are available
  1149. for configuration.
  1150. config HAVE_PERF_EVENTS
  1151. bool
  1152. help
  1153. See tools/perf/design.txt for details.
  1154. config PERF_USE_VMALLOC
  1155. bool
  1156. help
  1157. See tools/perf/design.txt for details
  1158. menu "Kernel Performance Events And Counters"
  1159. config PERF_EVENTS
  1160. bool "Kernel performance events and counters"
  1161. default y if PROFILING
  1162. depends on HAVE_PERF_EVENTS
  1163. select ANON_INODES
  1164. select IRQ_WORK
  1165. help
  1166. Enable kernel support for various performance events provided
  1167. by software and hardware.
  1168. Software events are supported either built-in or via the
  1169. use of generic tracepoints.
  1170. Most modern CPUs support performance events via performance
  1171. counter registers. These registers count the number of certain
  1172. types of hw events: such as instructions executed, cachemisses
  1173. suffered, or branches mis-predicted - without slowing down the
  1174. kernel or applications. These registers can also trigger interrupts
  1175. when a threshold number of events have passed - and can thus be
  1176. used to profile the code that runs on that CPU.
  1177. The Linux Performance Event subsystem provides an abstraction of
  1178. these software and hardware event capabilities, available via a
  1179. system call and used by the "perf" utility in tools/perf/. It
  1180. provides per task and per CPU counters, and it provides event
  1181. capabilities on top of those.
  1182. Say Y if unsure.
  1183. config DEBUG_PERF_USE_VMALLOC
  1184. default n
  1185. bool "Debug: use vmalloc to back perf mmap() buffers"
  1186. depends on PERF_EVENTS && DEBUG_KERNEL
  1187. select PERF_USE_VMALLOC
  1188. help
  1189. Use vmalloc memory to back perf mmap() buffers.
  1190. Mostly useful for debugging the vmalloc code on platforms
  1191. that don't require it.
  1192. Say N if unsure.
  1193. endmenu
  1194. config VM_EVENT_COUNTERS
  1195. default y
  1196. bool "Enable VM event counters for /proc/vmstat" if EXPERT
  1197. help
  1198. VM event counters are needed for event counts to be shown.
  1199. This option allows the disabling of the VM event counters
  1200. on EXPERT systems. /proc/vmstat will only show page counts
  1201. if VM event counters are disabled.
  1202. config PCI_QUIRKS
  1203. default y
  1204. bool "Enable PCI quirk workarounds" if EXPERT
  1205. depends on PCI
  1206. help
  1207. This enables workarounds for various PCI chipset
  1208. bugs/quirks. Disable this only if your target machine is
  1209. unaffected by PCI quirks.
  1210. config SLUB_DEBUG
  1211. default y
  1212. bool "Enable SLUB debugging support" if EXPERT
  1213. depends on SLUB && SYSFS
  1214. help
  1215. SLUB has extensive debug support features. Disabling these can
  1216. result in significant savings in code size. This also disables
  1217. SLUB sysfs support. /sys/slab will not exist and there will be
  1218. no support for cache validation etc.
  1219. config COMPAT_BRK
  1220. bool "Disable heap randomization"
  1221. default y
  1222. help
  1223. Randomizing heap placement makes heap exploits harder, but it
  1224. also breaks ancient binaries (including anything libc5 based).
  1225. This option changes the bootup default to heap randomization
  1226. disabled, and can be overridden at runtime by setting
  1227. /proc/sys/kernel/randomize_va_space to 2.
  1228. On non-ancient distros (post-2000 ones) N is usually a safe choice.
  1229. choice
  1230. prompt "Choose SLAB allocator"
  1231. default SLUB
  1232. help
  1233. This option allows to select a slab allocator.
  1234. config SLAB
  1235. bool "SLAB"
  1236. help
  1237. The regular slab allocator that is established and known to work
  1238. well in all environments. It organizes cache hot objects in
  1239. per cpu and per node queues.
  1240. config SLUB
  1241. bool "SLUB (Unqueued Allocator)"
  1242. help
  1243. SLUB is a slab allocator that minimizes cache line usage
  1244. instead of managing queues of cached objects (SLAB approach).
  1245. Per cpu caching is realized using slabs of objects instead
  1246. of queues of objects. SLUB can use memory efficiently
  1247. and has enhanced diagnostics. SLUB is the default choice for
  1248. a slab allocator.
  1249. config SLOB
  1250. depends on EXPERT
  1251. bool "SLOB (Simple Allocator)"
  1252. help
  1253. SLOB replaces the stock allocator with a drastically simpler
  1254. allocator. SLOB is generally more space efficient but
  1255. does not perform as well on large systems.
  1256. endchoice
  1257. config MMAP_ALLOW_UNINITIALIZED
  1258. bool "Allow mmapped anonymous memory to be uninitialized"
  1259. depends on EXPERT && !MMU
  1260. default n
  1261. help
  1262. Normally, and according to the Linux spec, anonymous memory obtained
  1263. from mmap() has it's contents cleared before it is passed to
  1264. userspace. Enabling this config option allows you to request that
  1265. mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
  1266. providing a huge performance boost. If this option is not enabled,
  1267. then the flag will be ignored.
  1268. This is taken advantage of by uClibc's malloc(), and also by
  1269. ELF-FDPIC binfmt's brk and stack allocator.
  1270. Because of the obvious security issues, this option should only be
  1271. enabled on embedded devices where you control what is run in
  1272. userspace. Since that isn't generally a problem on no-MMU systems,
  1273. it is normally safe to say Y here.
  1274. See Documentation/nommu-mmap.txt for more information.
  1275. config PROFILING
  1276. bool "Profiling support"
  1277. help
  1278. Say Y here to enable the extended profiling support mechanisms used
  1279. by profilers such as OProfile.
  1280. #
  1281. # Place an empty function call at each tracepoint site. Can be
  1282. # dynamically changed for a probe function.
  1283. #
  1284. config TRACEPOINTS
  1285. bool
  1286. source "arch/Kconfig"
  1287. endmenu # General setup
  1288. config HAVE_GENERIC_DMA_COHERENT
  1289. bool
  1290. default n
  1291. config SLABINFO
  1292. bool
  1293. depends on PROC_FS
  1294. depends on SLAB || SLUB_DEBUG
  1295. default y
  1296. config RT_MUTEXES
  1297. boolean
  1298. config BASE_SMALL
  1299. int
  1300. default 0 if BASE_FULL
  1301. default 1 if !BASE_FULL
  1302. menuconfig MODULES
  1303. bool "Enable loadable module support"
  1304. help
  1305. Kernel modules are small pieces of compiled code which can
  1306. be inserted in the running kernel, rather than being
  1307. permanently built into the kernel. You use the "modprobe"
  1308. tool to add (and sometimes remove) them. If you say Y here,
  1309. many parts of the kernel can be built as modules (by
  1310. answering M instead of Y where indicated): this is most
  1311. useful for infrequently used options which are not required
  1312. for booting. For more information, see the man pages for
  1313. modprobe, lsmod, modinfo, insmod and rmmod.
  1314. If you say Y here, you will need to run "make
  1315. modules_install" to put the modules under /lib/modules/
  1316. where modprobe can find them (you may need to be root to do
  1317. this).
  1318. If unsure, say Y.
  1319. if MODULES
  1320. config MODULE_FORCE_LOAD
  1321. bool "Forced module loading"
  1322. default n
  1323. help
  1324. Allow loading of modules without version information (ie. modprobe
  1325. --force). Forced module loading sets the 'F' (forced) taint flag and
  1326. is usually a really bad idea.
  1327. config MODULE_UNLOAD
  1328. bool "Module unloading"
  1329. help
  1330. Without this option you will not be able to unload any
  1331. modules (note that some modules may not be unloadable
  1332. anyway), which makes your kernel smaller, faster
  1333. and simpler. If unsure, say Y.
  1334. config MODULE_FORCE_UNLOAD
  1335. bool "Forced module unloading"
  1336. depends on MODULE_UNLOAD && EXPERIMENTAL
  1337. help
  1338. This option allows you to force a module to unload, even if the
  1339. kernel believes it is unsafe: the kernel will remove the module
  1340. without waiting for anyone to stop using it (using the -f option to
  1341. rmmod). This is mainly for kernel developers and desperate users.
  1342. If unsure, say N.
  1343. config MODVERSIONS
  1344. bool "Module versioning support"
  1345. help
  1346. Usually, you have to use modules compiled with your kernel.
  1347. Saying Y here makes it sometimes possible to use modules
  1348. compiled for different kernels, by adding enough information
  1349. to the modules to (hopefully) spot any changes which would
  1350. make them incompatible with the kernel you are running. If
  1351. unsure, say N.
  1352. config MODULE_SRCVERSION_ALL
  1353. bool "Source checksum for all modules"
  1354. help
  1355. Modules which contain a MODULE_VERSION get an extra "srcversion"
  1356. field inserted into their modinfo section, which contains a
  1357. sum of the source files which made it. This helps maintainers
  1358. see exactly which source was used to build a module (since
  1359. others sometimes change the module source without updating
  1360. the version). With this option, such a "srcversion" field
  1361. will be created for all modules. If unsure, say N.
  1362. endif # MODULES
  1363. config INIT_ALL_POSSIBLE
  1364. bool
  1365. help
  1366. Back when each arch used to define their own cpu_online_mask and
  1367. cpu_possible_mask, some of them chose to initialize cpu_possible_mask
  1368. with all 1s, and others with all 0s. When they were centralised,
  1369. it was better to provide this option than to break all the archs
  1370. and have several arch maintainers pursuing me down dark alleys.
  1371. config STOP_MACHINE
  1372. bool
  1373. default y
  1374. depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
  1375. help
  1376. Need stop_machine() primitive.
  1377. source "block/Kconfig"
  1378. config PREEMPT_NOTIFIERS
  1379. bool
  1380. config PADATA
  1381. depends on SMP
  1382. bool
  1383. source "kernel/Kconfig.locks"