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 drivers that have been replaced by something else, and/or are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 VIRT_CPU_ACCOUNTING
  224. bool "Deterministic task and CPU time accounting"
  225. depends on HAVE_VIRT_CPU_ACCOUNTING
  226. default y if PPC64
  227. help
  228. Select this option to enable more accurate task and CPU time
  229. accounting. This is done by reading a CPU counter on each
  230. kernel entry and exit and on transitions within the kernel
  231. between system, softirq and hardirq state, so there is a
  232. small performance impact. In the case of s390 or IBM POWER > 5,
  233. this also enables accounting of stolen time on logically-partitioned
  234. systems.
  235. config BSD_PROCESS_ACCT
  236. bool "BSD Process Accounting"
  237. help
  238. If you say Y here, a user level program will be able to instruct the
  239. kernel (via a special system call) to write process accounting
  240. information to a file: whenever a process exits, information about
  241. that process will be appended to the file by the kernel. The
  242. information includes things such as creation time, owning user,
  243. command name, memory usage, controlling terminal etc. (the complete
  244. list is in the struct acct in <file:include/linux/acct.h>). It is
  245. up to the user level program to do useful things with this
  246. information. This is generally a good idea, so say Y.
  247. config BSD_PROCESS_ACCT_V3
  248. bool "BSD Process Accounting version 3 file format"
  249. depends on BSD_PROCESS_ACCT
  250. default n
  251. help
  252. If you say Y here, the process accounting information is written
  253. in a new file format that also logs the process IDs of each
  254. process and it's parent. Note that this file format is incompatible
  255. with previous v0/v1/v2 file formats, so you will need updated tools
  256. for processing it. A preliminary version of these tools is available
  257. at <http://www.gnu.org/software/acct/>.
  258. config FHANDLE
  259. bool "open by fhandle syscalls"
  260. select EXPORTFS
  261. help
  262. If you say Y here, a user level program will be able to map
  263. file names to handle and then later use the handle for
  264. different file system operations. This is useful in implementing
  265. userspace file servers, which now track files using handles instead
  266. of names. The handle would remain the same even if file names
  267. get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
  268. syscalls.
  269. config TASKSTATS
  270. bool "Export task/process statistics through netlink (EXPERIMENTAL)"
  271. depends on NET
  272. default n
  273. help
  274. Export selected statistics for tasks/processes through the
  275. generic netlink interface. Unlike BSD process accounting, the
  276. statistics are available during the lifetime of tasks/processes as
  277. responses to commands. Like BSD accounting, they are sent to user
  278. space on task exit.
  279. Say N if unsure.
  280. config TASK_DELAY_ACCT
  281. bool "Enable per-task delay accounting (EXPERIMENTAL)"
  282. depends on TASKSTATS
  283. help
  284. Collect information on time spent by a task waiting for system
  285. resources like cpu, synchronous block I/O completion and swapping
  286. in pages. Such statistics can help in setting a task's priorities
  287. relative to other tasks for cpu, io, rss limits etc.
  288. Say N if unsure.
  289. config TASK_XACCT
  290. bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
  291. depends on TASKSTATS
  292. help
  293. Collect extended task accounting data and send the data
  294. to userland for processing over the taskstats interface.
  295. Say N if unsure.
  296. config TASK_IO_ACCOUNTING
  297. bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
  298. depends on TASK_XACCT
  299. help
  300. Collect information on the number of bytes of storage I/O which this
  301. task has caused.
  302. Say N if unsure.
  303. config AUDIT
  304. bool "Auditing support"
  305. depends on NET
  306. help
  307. Enable auditing infrastructure that can be used with another
  308. kernel subsystem, such as SELinux (which requires this for
  309. logging of avc messages output). Does not do system-call
  310. auditing without CONFIG_AUDITSYSCALL.
  311. config AUDITSYSCALL
  312. bool "Enable system-call auditing support"
  313. depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || (ARM && AEABI && !OABI_COMPAT))
  314. default y if SECURITY_SELINUX
  315. help
  316. Enable low-overhead system-call auditing infrastructure that
  317. can be used independently or with another kernel subsystem,
  318. such as SELinux.
  319. config AUDIT_WATCH
  320. def_bool y
  321. depends on AUDITSYSCALL
  322. select FSNOTIFY
  323. config AUDIT_TREE
  324. def_bool y
  325. depends on AUDITSYSCALL
  326. select FSNOTIFY
  327. config AUDIT_LOGINUID_IMMUTABLE
  328. bool "Make audit loginuid immutable"
  329. depends on AUDIT
  330. help
  331. The config option toggles if a task setting its loginuid requires
  332. CAP_SYS_AUDITCONTROL or if that task should require no special permissions
  333. but should instead only allow setting its loginuid if it was never
  334. previously set. On systems which use systemd or a similar central
  335. process to restart login services this should be set to true. On older
  336. systems in which an admin would typically have to directly stop and
  337. start processes this should be set to false. Setting this to true allows
  338. one to drop potentially dangerous capabilites from the login tasks,
  339. but may not be backwards compatible with older init systems.
  340. source "kernel/irq/Kconfig"
  341. source "kernel/time/Kconfig"
  342. menu "RCU Subsystem"
  343. choice
  344. prompt "RCU Implementation"
  345. default TREE_RCU
  346. config TREE_RCU
  347. bool "Tree-based hierarchical RCU"
  348. depends on !PREEMPT && SMP
  349. help
  350. This option selects the RCU implementation that is
  351. designed for very large SMP system with hundreds or
  352. thousands of CPUs. It also scales down nicely to
  353. smaller systems.
  354. config TREE_PREEMPT_RCU
  355. bool "Preemptible tree-based hierarchical RCU"
  356. depends on PREEMPT && SMP
  357. help
  358. This option selects the RCU implementation that is
  359. designed for very large SMP systems with hundreds or
  360. thousands of CPUs, but for which real-time response
  361. is also required. It also scales down nicely to
  362. smaller systems.
  363. config TINY_RCU
  364. bool "UP-only small-memory-footprint RCU"
  365. depends on !PREEMPT && !SMP
  366. help
  367. This option selects the RCU implementation that is
  368. designed for UP systems from which real-time response
  369. is not required. This option greatly reduces the
  370. memory footprint of RCU.
  371. config TINY_PREEMPT_RCU
  372. bool "Preemptible UP-only small-memory-footprint RCU"
  373. depends on PREEMPT && !SMP
  374. help
  375. This option selects the RCU implementation that is designed
  376. for real-time UP systems. This option greatly reduces the
  377. memory footprint of RCU.
  378. endchoice
  379. config PREEMPT_RCU
  380. def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
  381. help
  382. This option enables preemptible-RCU code that is common between
  383. the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
  384. config RCU_FANOUT
  385. int "Tree-based hierarchical RCU fanout value"
  386. range 2 64 if 64BIT
  387. range 2 32 if !64BIT
  388. depends on TREE_RCU || TREE_PREEMPT_RCU
  389. default 64 if 64BIT
  390. default 32 if !64BIT
  391. help
  392. This option controls the fanout of hierarchical implementations
  393. of RCU, allowing RCU to work efficiently on machines with
  394. large numbers of CPUs. This value must be at least the fourth
  395. root of NR_CPUS, which allows NR_CPUS to be insanely large.
  396. The default value of RCU_FANOUT should be used for production
  397. systems, but if you are stress-testing the RCU implementation
  398. itself, small RCU_FANOUT values allow you to test large-system
  399. code paths on small(er) systems.
  400. Select a specific number if testing RCU itself.
  401. Take the default if unsure.
  402. config RCU_FANOUT_LEAF
  403. int "Tree-based hierarchical RCU leaf-level fanout value"
  404. range 2 RCU_FANOUT if 64BIT
  405. range 2 RCU_FANOUT if !64BIT
  406. depends on TREE_RCU || TREE_PREEMPT_RCU
  407. default 16
  408. help
  409. This option controls the leaf-level fanout of hierarchical
  410. implementations of RCU, and allows trading off cache misses
  411. against lock contention. Systems that synchronize their
  412. scheduling-clock interrupts for energy-efficiency reasons will
  413. want the default because the smaller leaf-level fanout keeps
  414. lock contention levels acceptably low. Very large systems
  415. (hundreds or thousands of CPUs) will instead want to set this
  416. value to the maximum value possible in order to reduce the
  417. number of cache misses incurred during RCU's grace-period
  418. initialization. These systems tend to run CPU-bound, and thus
  419. are not helped by synchronized interrupts, and thus tend to
  420. skew them, which reduces lock contention enough that large
  421. leaf-level fanouts work well.
  422. Select a specific number if testing RCU itself.
  423. Select the maximum permissible value for large systems.
  424. Take the default if unsure.
  425. config RCU_FANOUT_EXACT
  426. bool "Disable tree-based hierarchical RCU auto-balancing"
  427. depends on TREE_RCU || TREE_PREEMPT_RCU
  428. default n
  429. help
  430. This option forces use of the exact RCU_FANOUT value specified,
  431. regardless of imbalances in the hierarchy. This is useful for
  432. testing RCU itself, and might one day be useful on systems with
  433. strong NUMA behavior.
  434. Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
  435. Say N if unsure.
  436. config RCU_FAST_NO_HZ
  437. bool "Accelerate last non-dyntick-idle CPU's grace periods"
  438. depends on NO_HZ && SMP
  439. default n
  440. help
  441. This option causes RCU to attempt to accelerate grace periods
  442. in order to allow CPUs to enter dynticks-idle state more
  443. quickly. On the other hand, this option increases the overhead
  444. of the dynticks-idle checking, particularly on systems with
  445. large numbers of CPUs.
  446. Say Y if energy efficiency is critically important, particularly
  447. if you have relatively few CPUs.
  448. Say N if you are unsure.
  449. config TREE_RCU_TRACE
  450. def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
  451. select DEBUG_FS
  452. help
  453. This option provides tracing for the TREE_RCU and
  454. TREE_PREEMPT_RCU implementations, permitting Makefile to
  455. trivially select kernel/rcutree_trace.c.
  456. config RCU_BOOST
  457. bool "Enable RCU priority boosting"
  458. depends on RT_MUTEXES && PREEMPT_RCU
  459. default n
  460. help
  461. This option boosts the priority of preempted RCU readers that
  462. block the current preemptible RCU grace period for too long.
  463. This option also prevents heavy loads from blocking RCU
  464. callback invocation for all flavors of RCU.
  465. Say Y here if you are working with real-time apps or heavy loads
  466. Say N here if you are unsure.
  467. config RCU_BOOST_PRIO
  468. int "Real-time priority to boost RCU readers to"
  469. range 1 99
  470. depends on RCU_BOOST
  471. default 1
  472. help
  473. This option specifies the real-time priority to which long-term
  474. preempted RCU readers are to be boosted. If you are working
  475. with a real-time application that has one or more CPU-bound
  476. threads running at a real-time priority level, you should set
  477. RCU_BOOST_PRIO to a priority higher then the highest-priority
  478. real-time CPU-bound thread. The default RCU_BOOST_PRIO value
  479. of 1 is appropriate in the common case, which is real-time
  480. applications that do not have any CPU-bound threads.
  481. Some real-time applications might not have a single real-time
  482. thread that saturates a given CPU, but instead might have
  483. multiple real-time threads that, taken together, fully utilize
  484. that CPU. In this case, you should set RCU_BOOST_PRIO to
  485. a priority higher than the lowest-priority thread that is
  486. conspiring to prevent the CPU from running any non-real-time
  487. tasks. For example, if one thread at priority 10 and another
  488. thread at priority 5 are between themselves fully consuming
  489. the CPU time on a given CPU, then RCU_BOOST_PRIO should be
  490. set to priority 6 or higher.
  491. Specify the real-time priority, or take the default if unsure.
  492. config RCU_BOOST_DELAY
  493. int "Milliseconds to delay boosting after RCU grace-period start"
  494. range 0 3000
  495. depends on RCU_BOOST
  496. default 500
  497. help
  498. This option specifies the time to wait after the beginning of
  499. a given grace period before priority-boosting preempted RCU
  500. readers blocking that grace period. Note that any RCU reader
  501. blocking an expedited RCU grace period is boosted immediately.
  502. Accept the default if unsure.
  503. endmenu # "RCU Subsystem"
  504. config IKCONFIG
  505. tristate "Kernel .config support"
  506. ---help---
  507. This option enables the complete Linux kernel ".config" file
  508. contents to be saved in the kernel. It provides documentation
  509. of which kernel options are used in a running kernel or in an
  510. on-disk kernel. This information can be extracted from the kernel
  511. image file with the script scripts/extract-ikconfig and used as
  512. input to rebuild the current kernel or to build another kernel.
  513. It can also be extracted from a running kernel by reading
  514. /proc/config.gz if enabled (below).
  515. config IKCONFIG_PROC
  516. bool "Enable access to .config through /proc/config.gz"
  517. depends on IKCONFIG && PROC_FS
  518. ---help---
  519. This option enables access to the kernel configuration file
  520. through /proc/config.gz.
  521. config LOG_BUF_SHIFT
  522. int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
  523. range 12 21
  524. default 17
  525. help
  526. Select kernel log buffer size as a power of 2.
  527. Examples:
  528. 17 => 128 KB
  529. 16 => 64 KB
  530. 15 => 32 KB
  531. 14 => 16 KB
  532. 13 => 8 KB
  533. 12 => 4 KB
  534. #
  535. # Architectures with an unreliable sched_clock() should select this:
  536. #
  537. config HAVE_UNSTABLE_SCHED_CLOCK
  538. bool
  539. menuconfig CGROUPS
  540. boolean "Control Group support"
  541. depends on EVENTFD
  542. help
  543. This option adds support for grouping sets of processes together, for
  544. use with process control subsystems such as Cpusets, CFS, memory
  545. controls or device isolation.
  546. See
  547. - Documentation/scheduler/sched-design-CFS.txt (CFS)
  548. - Documentation/cgroups/ (features for grouping, isolation
  549. and resource control)
  550. Say N if unsure.
  551. if CGROUPS
  552. config CGROUP_DEBUG
  553. bool "Example debug cgroup subsystem"
  554. default n
  555. help
  556. This option enables a simple cgroup subsystem that
  557. exports useful debugging information about the cgroups
  558. framework.
  559. Say N if unsure.
  560. config CGROUP_FREEZER
  561. bool "Freezer cgroup subsystem"
  562. help
  563. Provides a way to freeze and unfreeze all tasks in a
  564. cgroup.
  565. config CGROUP_DEVICE
  566. bool "Device controller for cgroups"
  567. help
  568. Provides a cgroup implementing whitelists for devices which
  569. a process in the cgroup can mknod or open.
  570. config CPUSETS
  571. bool "Cpuset support"
  572. help
  573. This option will let you create and manage CPUSETs which
  574. allow dynamically partitioning a system into sets of CPUs and
  575. Memory Nodes and assigning tasks to run only within those sets.
  576. This is primarily useful on large SMP or NUMA systems.
  577. Say N if unsure.
  578. config PROC_PID_CPUSET
  579. bool "Include legacy /proc/<pid>/cpuset file"
  580. depends on CPUSETS
  581. default y
  582. config CGROUP_CPUACCT
  583. bool "Simple CPU accounting cgroup subsystem"
  584. help
  585. Provides a simple Resource Controller for monitoring the
  586. total CPU consumed by the tasks in a cgroup.
  587. config RESOURCE_COUNTERS
  588. bool "Resource counters"
  589. help
  590. This option enables controller independent resource accounting
  591. infrastructure that works with cgroups.
  592. config MEMCG
  593. bool "Memory Resource Controller for Control Groups"
  594. depends on RESOURCE_COUNTERS
  595. select MM_OWNER
  596. help
  597. Provides a memory resource controller that manages both anonymous
  598. memory and page cache. (See Documentation/cgroups/memory.txt)
  599. Note that setting this option increases fixed memory overhead
  600. associated with each page of memory in the system. By this,
  601. 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
  602. usage tracking struct at boot. Total amount of this is printed out
  603. at boot.
  604. Only enable when you're ok with these trade offs and really
  605. sure you need the memory resource controller. Even when you enable
  606. this, you can set "cgroup_disable=memory" at your boot option to
  607. disable memory resource controller and you can avoid overheads.
  608. (and lose benefits of memory resource controller)
  609. This config option also selects MM_OWNER config option, which
  610. could in turn add some fork/exit overhead.
  611. config MEMCG_SWAP
  612. bool "Memory Resource Controller Swap Extension"
  613. depends on MEMCG && SWAP
  614. help
  615. Add swap management feature to memory resource controller. When you
  616. enable this, you can limit mem+swap usage per cgroup. In other words,
  617. when you disable this, memory resource controller has no cares to
  618. usage of swap...a process can exhaust all of the swap. This extension
  619. is useful when you want to avoid exhaustion swap but this itself
  620. adds more overheads and consumes memory for remembering information.
  621. Especially if you use 32bit system or small memory system, please
  622. be careful about enabling this. When memory resource controller
  623. is disabled by boot option, this will be automatically disabled and
  624. there will be no overhead from this. Even when you set this config=y,
  625. if boot option "swapaccount=0" is set, swap will not be accounted.
  626. Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
  627. size is 4096bytes, 512k per 1Gbytes of swap.
  628. config MEMCG_SWAP_ENABLED
  629. bool "Memory Resource Controller Swap Extension enabled by default"
  630. depends on MEMCG_SWAP
  631. default y
  632. help
  633. Memory Resource Controller Swap Extension comes with its price in
  634. a bigger memory consumption. General purpose distribution kernels
  635. which want to enable the feature but keep it disabled by default
  636. and let the user enable it by swapaccount boot command line
  637. parameter should have this option unselected.
  638. For those who want to have the feature enabled by default should
  639. select this option (if, for some reason, they need to disable it
  640. then swapaccount=0 does the trick).
  641. config MEMCG_KMEM
  642. bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
  643. depends on MEMCG && EXPERIMENTAL
  644. default n
  645. help
  646. The Kernel Memory extension for Memory Resource Controller can limit
  647. the amount of memory used by kernel objects in the system. Those are
  648. fundamentally different from the entities handled by the standard
  649. Memory Controller, which are page-based, and can be swapped. Users of
  650. the kmem extension can use it to guarantee that no group of processes
  651. will ever exhaust kernel resources alone.
  652. config CGROUP_HUGETLB
  653. bool "HugeTLB Resource Controller for Control Groups"
  654. depends on RESOURCE_COUNTERS && HUGETLB_PAGE && EXPERIMENTAL
  655. default n
  656. help
  657. Provides a cgroup Resource Controller for HugeTLB pages.
  658. When you enable this, you can put a per cgroup limit on HugeTLB usage.
  659. The limit is enforced during page fault. Since HugeTLB doesn't
  660. support page reclaim, enforcing the limit at page fault time implies
  661. that, the application will get SIGBUS signal if it tries to access
  662. HugeTLB pages beyond its limit. This requires the application to know
  663. beforehand how much HugeTLB pages it would require for its use. The
  664. control group is tracked in the third page lru pointer. This means
  665. that we cannot use the controller with huge page less than 3 pages.
  666. config CGROUP_PERF
  667. bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
  668. depends on PERF_EVENTS && CGROUPS
  669. help
  670. This option extends the per-cpu mode to restrict monitoring to
  671. threads which belong to the cgroup specified and run on the
  672. designated cpu.
  673. Say N if unsure.
  674. menuconfig CGROUP_SCHED
  675. bool "Group CPU scheduler"
  676. default n
  677. help
  678. This feature lets CPU scheduler recognize task groups and control CPU
  679. bandwidth allocation to such task groups. It uses cgroups to group
  680. tasks.
  681. if CGROUP_SCHED
  682. config FAIR_GROUP_SCHED
  683. bool "Group scheduling for SCHED_OTHER"
  684. depends on CGROUP_SCHED
  685. default CGROUP_SCHED
  686. config CFS_BANDWIDTH
  687. bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
  688. depends on EXPERIMENTAL
  689. depends on FAIR_GROUP_SCHED
  690. default n
  691. help
  692. This option allows users to define CPU bandwidth rates (limits) for
  693. tasks running within the fair group scheduler. Groups with no limit
  694. set are considered to be unconstrained and will run with no
  695. restriction.
  696. See tip/Documentation/scheduler/sched-bwc.txt for more information.
  697. config RT_GROUP_SCHED
  698. bool "Group scheduling for SCHED_RR/FIFO"
  699. depends on EXPERIMENTAL
  700. depends on CGROUP_SCHED
  701. default n
  702. help
  703. This feature lets you explicitly allocate real CPU bandwidth
  704. to task groups. If enabled, it will also make it impossible to
  705. schedule realtime tasks for non-root users until you allocate
  706. realtime bandwidth for them.
  707. See Documentation/scheduler/sched-rt-group.txt for more information.
  708. endif #CGROUP_SCHED
  709. config BLK_CGROUP
  710. bool "Block IO controller"
  711. depends on BLOCK
  712. default n
  713. ---help---
  714. Generic block IO controller cgroup interface. This is the common
  715. cgroup interface which should be used by various IO controlling
  716. policies.
  717. Currently, CFQ IO scheduler uses it to recognize task groups and
  718. control disk bandwidth allocation (proportional time slice allocation)
  719. to such task groups. It is also used by bio throttling logic in
  720. block layer to implement upper limit in IO rates on a device.
  721. This option only enables generic Block IO controller infrastructure.
  722. One needs to also enable actual IO controlling logic/policy. For
  723. enabling proportional weight division of disk bandwidth in CFQ, set
  724. CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
  725. CONFIG_BLK_DEV_THROTTLING=y.
  726. See Documentation/cgroups/blkio-controller.txt for more information.
  727. config DEBUG_BLK_CGROUP
  728. bool "Enable Block IO controller debugging"
  729. depends on BLK_CGROUP
  730. default n
  731. ---help---
  732. Enable some debugging help. Currently it exports additional stat
  733. files in a cgroup which can be useful for debugging.
  734. endif # CGROUPS
  735. config CHECKPOINT_RESTORE
  736. bool "Checkpoint/restore support" if EXPERT
  737. default n
  738. help
  739. Enables additional kernel features in a sake of checkpoint/restore.
  740. In particular it adds auxiliary prctl codes to setup process text,
  741. data and heap segment sizes, and a few additional /proc filesystem
  742. entries.
  743. If unsure, say N here.
  744. menuconfig NAMESPACES
  745. bool "Namespaces support" if EXPERT
  746. default !EXPERT
  747. help
  748. Provides the way to make tasks work with different objects using
  749. the same id. For example same IPC id may refer to different objects
  750. or same user id or pid may refer to different tasks when used in
  751. different namespaces.
  752. if NAMESPACES
  753. config UTS_NS
  754. bool "UTS namespace"
  755. default y
  756. help
  757. In this namespace tasks see different info provided with the
  758. uname() system call
  759. config IPC_NS
  760. bool "IPC namespace"
  761. depends on (SYSVIPC || POSIX_MQUEUE)
  762. default y
  763. help
  764. In this namespace tasks work with IPC ids which correspond to
  765. different IPC objects in different namespaces.
  766. config USER_NS
  767. bool "User namespace (EXPERIMENTAL)"
  768. depends on EXPERIMENTAL
  769. depends on UIDGID_CONVERTED
  770. select UIDGID_STRICT_TYPE_CHECKS
  771. default n
  772. help
  773. This allows containers, i.e. vservers, to use user namespaces
  774. to provide different user info for different servers.
  775. If unsure, say N.
  776. config PID_NS
  777. bool "PID Namespaces"
  778. default y
  779. help
  780. Support process id namespaces. This allows having multiple
  781. processes with the same pid as long as they are in different
  782. pid namespaces. This is a building block of containers.
  783. config NET_NS
  784. bool "Network namespace"
  785. depends on NET
  786. default y
  787. help
  788. Allow user space to create what appear to be multiple instances
  789. of the network stack.
  790. endif # NAMESPACES
  791. config UIDGID_CONVERTED
  792. # True if all of the selected software conmponents are known
  793. # to have uid_t and gid_t converted to kuid_t and kgid_t
  794. # where appropriate and are otherwise safe to use with
  795. # the user namespace.
  796. bool
  797. default y
  798. # List of kernel pieces that need user namespace work
  799. # Features
  800. depends on SYSVIPC = n
  801. depends on IMA = n
  802. depends on EVM = n
  803. depends on KEYS = n
  804. depends on AUDIT = n
  805. depends on AUDITSYSCALL = n
  806. depends on TASKSTATS = n
  807. depends on TRACING = n
  808. depends on FS_POSIX_ACL = n
  809. depends on QUOTA = n
  810. depends on QUOTACTL = n
  811. depends on DEBUG_CREDENTIALS = n
  812. depends on BSD_PROCESS_ACCT = n
  813. depends on DRM = n
  814. depends on PROC_EVENTS = n
  815. # Networking
  816. depends on NET = n
  817. depends on NET_9P = n
  818. depends on IPX = n
  819. depends on PHONET = n
  820. depends on NET_CLS_FLOW = n
  821. depends on NETFILTER_XT_MATCH_OWNER = n
  822. depends on NETFILTER_XT_MATCH_RECENT = n
  823. depends on NETFILTER_XT_TARGET_LOG = n
  824. depends on NETFILTER_NETLINK_LOG = n
  825. depends on INET = n
  826. depends on IPV6 = n
  827. depends on IP_SCTP = n
  828. depends on AF_RXRPC = n
  829. depends on LLC2 = n
  830. depends on NET_KEY = n
  831. depends on INET_DIAG = n
  832. depends on DNS_RESOLVER = n
  833. depends on AX25 = n
  834. depends on ATALK = n
  835. # Filesystems
  836. depends on USB_DEVICEFS = n
  837. depends on USB_GADGETFS = n
  838. depends on USB_FUNCTIONFS = n
  839. depends on DEVTMPFS = n
  840. depends on XENFS = n
  841. depends on 9P_FS = n
  842. depends on ADFS_FS = n
  843. depends on AFFS_FS = n
  844. depends on AFS_FS = n
  845. depends on AUTOFS4_FS = n
  846. depends on BEFS_FS = n
  847. depends on BFS_FS = n
  848. depends on BTRFS_FS = n
  849. depends on CEPH_FS = n
  850. depends on CIFS = n
  851. depends on CODA_FS = n
  852. depends on CONFIGFS_FS = n
  853. depends on CRAMFS = n
  854. depends on DEBUG_FS = n
  855. depends on ECRYPT_FS = n
  856. depends on EFS_FS = n
  857. depends on EXOFS_FS = n
  858. depends on FAT_FS = n
  859. depends on FUSE_FS = n
  860. depends on GFS2_FS = n
  861. depends on HFS_FS = n
  862. depends on HFSPLUS_FS = n
  863. depends on HPFS_FS = n
  864. depends on HUGETLBFS = n
  865. depends on ISO9660_FS = n
  866. depends on JFFS2_FS = n
  867. depends on JFS_FS = n
  868. depends on LOGFS = n
  869. depends on MINIX_FS = n
  870. depends on NCP_FS = n
  871. depends on NFSD = n
  872. depends on NFS_FS = n
  873. depends on NILFS2_FS = n
  874. depends on NTFS_FS = n
  875. depends on OCFS2_FS = n
  876. depends on OMFS_FS = n
  877. depends on QNX4FS_FS = n
  878. depends on QNX6FS_FS = n
  879. depends on REISERFS_FS = n
  880. depends on SQUASHFS = n
  881. depends on SYSV_FS = n
  882. depends on UBIFS_FS = n
  883. depends on UDF_FS = n
  884. depends on UFS_FS = n
  885. depends on VXFS_FS = n
  886. depends on XFS_FS = n
  887. depends on !UML || HOSTFS = n
  888. # The rare drivers that won't build
  889. depends on AIRO = n
  890. depends on AIRO_CS = n
  891. depends on TUN = n
  892. depends on INFINIBAND_QIB = n
  893. depends on BLK_DEV_LOOP = n
  894. depends on ANDROID_BINDER_IPC = n
  895. # Security modules
  896. depends on SECURITY_TOMOYO = n
  897. depends on SECURITY_APPARMOR = n
  898. config UIDGID_STRICT_TYPE_CHECKS
  899. bool "Require conversions between uid/gids and their internal representation"
  900. depends on UIDGID_CONVERTED
  901. default n
  902. help
  903. While the nececessary conversions are being added to all subsystems this option allows
  904. the code to continue to build for unconverted subsystems.
  905. Say Y here if you want the strict type checking enabled
  906. config SCHED_AUTOGROUP
  907. bool "Automatic process group scheduling"
  908. select EVENTFD
  909. select CGROUPS
  910. select CGROUP_SCHED
  911. select FAIR_GROUP_SCHED
  912. help
  913. This option optimizes the scheduler for common desktop workloads by
  914. automatically creating and populating task groups. This separation
  915. of workloads isolates aggressive CPU burners (like build jobs) from
  916. desktop applications. Task group autogeneration is currently based
  917. upon task session.
  918. config MM_OWNER
  919. bool
  920. config SYSFS_DEPRECATED
  921. bool "Enable deprecated sysfs features to support old userspace tools"
  922. depends on SYSFS
  923. default n
  924. help
  925. This option adds code that switches the layout of the "block" class
  926. devices, to not show up in /sys/class/block/, but only in
  927. /sys/block/.
  928. This switch is only active when the sysfs.deprecated=1 boot option is
  929. passed or the SYSFS_DEPRECATED_V2 option is set.
  930. This option allows new kernels to run on old distributions and tools,
  931. which might get confused by /sys/class/block/. Since 2007/2008 all
  932. major distributions and tools handle this just fine.
  933. Recent distributions and userspace tools after 2009/2010 depend on
  934. the existence of /sys/class/block/, and will not work with this
  935. option enabled.
  936. Only if you are using a new kernel on an old distribution, you might
  937. need to say Y here.
  938. config SYSFS_DEPRECATED_V2
  939. bool "Enable deprecated sysfs features by default"
  940. default n
  941. depends on SYSFS
  942. depends on SYSFS_DEPRECATED
  943. help
  944. Enable deprecated sysfs by default.
  945. See the CONFIG_SYSFS_DEPRECATED option for more details about this
  946. option.
  947. Only if you are using a new kernel on an old distribution, you might
  948. need to say Y here. Even then, odds are you would not need it
  949. enabled, you can always pass the boot option if absolutely necessary.
  950. config RELAY
  951. bool "Kernel->user space relay support (formerly relayfs)"
  952. help
  953. This option enables support for relay interface support in
  954. certain file systems (such as debugfs).
  955. It is designed to provide an efficient mechanism for tools and
  956. facilities to relay large amounts of data from kernel space to
  957. user space.
  958. If unsure, say N.
  959. config BLK_DEV_INITRD
  960. bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
  961. depends on BROKEN || !FRV
  962. help
  963. The initial RAM filesystem is a ramfs which is loaded by the
  964. boot loader (loadlin or lilo) and that is mounted as root
  965. before the normal boot procedure. It is typically used to
  966. load modules needed to mount the "real" root file system,
  967. etc. See <file:Documentation/initrd.txt> for details.
  968. If RAM disk support (BLK_DEV_RAM) is also included, this
  969. also enables initial RAM disk (initrd) support and adds
  970. 15 Kbytes (more on some other architectures) to the kernel size.
  971. If unsure say Y.
  972. if BLK_DEV_INITRD
  973. source "usr/Kconfig"
  974. endif
  975. config CC_OPTIMIZE_FOR_SIZE
  976. bool "Optimize for size"
  977. help
  978. Enabling this option will pass "-Os" instead of "-O2" to gcc
  979. resulting in a smaller kernel.
  980. If unsure, say Y.
  981. config SYSCTL
  982. bool
  983. config ANON_INODES
  984. bool
  985. menuconfig EXPERT
  986. bool "Configure standard kernel features (expert users)"
  987. # Unhide debug options, to make the on-by-default options visible
  988. select DEBUG_KERNEL
  989. help
  990. This option allows certain base kernel options and settings
  991. to be disabled or tweaked. This is for specialized
  992. environments which can tolerate a "non-standard" kernel.
  993. Only use this if you really know what you are doing.
  994. config UID16
  995. bool "Enable 16-bit UID system calls" if EXPERT
  996. depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
  997. default y
  998. help
  999. This enables the legacy 16-bit UID syscall wrappers.
  1000. config SYSCTL_SYSCALL
  1001. bool "Sysctl syscall support" if EXPERT
  1002. depends on PROC_SYSCTL
  1003. default n
  1004. select SYSCTL
  1005. ---help---
  1006. sys_sysctl uses binary paths that have been found challenging
  1007. to properly maintain and use. The interface in /proc/sys
  1008. using paths with ascii names is now the primary path to this
  1009. information.
  1010. Almost nothing using the binary sysctl interface so if you are
  1011. trying to save some space it is probably safe to disable this,
  1012. making your kernel marginally smaller.
  1013. If unsure say N here.
  1014. config KALLSYMS
  1015. bool "Load all symbols for debugging/ksymoops" if EXPERT
  1016. default y
  1017. help
  1018. Say Y here to let the kernel print out symbolic crash information and
  1019. symbolic stack backtraces. This increases the size of the kernel
  1020. somewhat, as all symbols have to be loaded into the kernel image.
  1021. config KALLSYMS_ALL
  1022. bool "Include all symbols in kallsyms"
  1023. depends on DEBUG_KERNEL && KALLSYMS
  1024. help
  1025. Normally kallsyms only contains the symbols of functions for nicer
  1026. OOPS messages and backtraces (i.e., symbols from the text and inittext
  1027. sections). This is sufficient for most cases. And only in very rare
  1028. cases (e.g., when a debugger is used) all symbols are required (e.g.,
  1029. names of variables from the data sections, etc).
  1030. This option makes sure that all symbols are loaded into the kernel
  1031. image (i.e., symbols from all sections) in cost of increased kernel
  1032. size (depending on the kernel configuration, it may be 300KiB or
  1033. something like this).
  1034. Say N unless you really need all symbols.
  1035. config HOTPLUG
  1036. bool "Support for hot-pluggable devices" if EXPERT
  1037. default y
  1038. help
  1039. This option is provided for the case where no hotplug or uevent
  1040. capabilities is wanted by the kernel. You should only consider
  1041. disabling this option for embedded systems that do not use modules, a
  1042. dynamic /dev tree, or dynamic device discovery. Just say Y.
  1043. config PRINTK
  1044. default y
  1045. bool "Enable support for printk" if EXPERT
  1046. help
  1047. This option enables normal printk support. Removing it
  1048. eliminates most of the message strings from the kernel image
  1049. and makes the kernel more or less silent. As this makes it
  1050. very difficult to diagnose system problems, saying N here is
  1051. strongly discouraged.
  1052. config BUG
  1053. bool "BUG() support" if EXPERT
  1054. default y
  1055. help
  1056. Disabling this option eliminates support for BUG and WARN, reducing
  1057. the size of your kernel image and potentially quietly ignoring
  1058. numerous fatal conditions. You should only consider disabling this
  1059. option for embedded systems with no facilities for reporting errors.
  1060. Just say Y.
  1061. config ELF_CORE
  1062. default y
  1063. bool "Enable ELF core dumps" if EXPERT
  1064. help
  1065. Enable support for generating core dumps. Disabling saves about 4k.
  1066. config PCSPKR_PLATFORM
  1067. bool "Enable PC-Speaker support" if EXPERT
  1068. depends on HAVE_PCSPKR_PLATFORM
  1069. select I8253_LOCK
  1070. default y
  1071. help
  1072. This option allows to disable the internal PC-Speaker
  1073. support, saving some memory.
  1074. config HAVE_PCSPKR_PLATFORM
  1075. bool
  1076. config BASE_FULL
  1077. default y
  1078. bool "Enable full-sized data structures for core" if EXPERT
  1079. help
  1080. Disabling this option reduces the size of miscellaneous core
  1081. kernel data structures. This saves memory on small machines,
  1082. but may reduce performance.
  1083. config FUTEX
  1084. bool "Enable futex support" if EXPERT
  1085. default y
  1086. select RT_MUTEXES
  1087. help
  1088. Disabling this option will cause the kernel to be built without
  1089. support for "fast userspace mutexes". The resulting kernel may not
  1090. run glibc-based applications correctly.
  1091. config EPOLL
  1092. bool "Enable eventpoll support" if EXPERT
  1093. default y
  1094. select ANON_INODES
  1095. help
  1096. Disabling this option will cause the kernel to be built without
  1097. support for epoll family of system calls.
  1098. config SIGNALFD
  1099. bool "Enable signalfd() system call" if EXPERT
  1100. select ANON_INODES
  1101. default y
  1102. help
  1103. Enable the signalfd() system call that allows to receive signals
  1104. on a file descriptor.
  1105. If unsure, say Y.
  1106. config TIMERFD
  1107. bool "Enable timerfd() system call" if EXPERT
  1108. select ANON_INODES
  1109. default y
  1110. help
  1111. Enable the timerfd() system call that allows to receive timer
  1112. events on a file descriptor.
  1113. If unsure, say Y.
  1114. config EVENTFD
  1115. bool "Enable eventfd() system call" if EXPERT
  1116. select ANON_INODES
  1117. default y
  1118. help
  1119. Enable the eventfd() system call that allows to receive both
  1120. kernel notification (ie. KAIO) or userspace notifications.
  1121. If unsure, say Y.
  1122. config SHMEM
  1123. bool "Use full shmem filesystem" if EXPERT
  1124. default y
  1125. depends on MMU
  1126. help
  1127. The shmem is an internal filesystem used to manage shared memory.
  1128. It is backed by swap and manages resource limits. It is also exported
  1129. to userspace as tmpfs if TMPFS is enabled. Disabling this
  1130. option replaces shmem and tmpfs with the much simpler ramfs code,
  1131. which may be appropriate on small systems without swap.
  1132. config AIO
  1133. bool "Enable AIO support" if EXPERT
  1134. default y
  1135. help
  1136. This option enables POSIX asynchronous I/O which may by used
  1137. by some high performance threaded applications. Disabling
  1138. this option saves about 7k.
  1139. config EMBEDDED
  1140. bool "Embedded system"
  1141. select EXPERT
  1142. help
  1143. This option should be enabled if compiling the kernel for
  1144. an embedded system so certain expert options are available
  1145. for configuration.
  1146. config HAVE_PERF_EVENTS
  1147. bool
  1148. help
  1149. See tools/perf/design.txt for details.
  1150. config PERF_USE_VMALLOC
  1151. bool
  1152. help
  1153. See tools/perf/design.txt for details
  1154. menu "Kernel Performance Events And Counters"
  1155. config PERF_EVENTS
  1156. bool "Kernel performance events and counters"
  1157. default y if PROFILING
  1158. depends on HAVE_PERF_EVENTS
  1159. select ANON_INODES
  1160. select IRQ_WORK
  1161. help
  1162. Enable kernel support for various performance events provided
  1163. by software and hardware.
  1164. Software events are supported either built-in or via the
  1165. use of generic tracepoints.
  1166. Most modern CPUs support performance events via performance
  1167. counter registers. These registers count the number of certain
  1168. types of hw events: such as instructions executed, cachemisses
  1169. suffered, or branches mis-predicted - without slowing down the
  1170. kernel or applications. These registers can also trigger interrupts
  1171. when a threshold number of events have passed - and can thus be
  1172. used to profile the code that runs on that CPU.
  1173. The Linux Performance Event subsystem provides an abstraction of
  1174. these software and hardware event capabilities, available via a
  1175. system call and used by the "perf" utility in tools/perf/. It
  1176. provides per task and per CPU counters, and it provides event
  1177. capabilities on top of those.
  1178. Say Y if unsure.
  1179. config DEBUG_PERF_USE_VMALLOC
  1180. default n
  1181. bool "Debug: use vmalloc to back perf mmap() buffers"
  1182. depends on PERF_EVENTS && DEBUG_KERNEL
  1183. select PERF_USE_VMALLOC
  1184. help
  1185. Use vmalloc memory to back perf mmap() buffers.
  1186. Mostly useful for debugging the vmalloc code on platforms
  1187. that don't require it.
  1188. Say N if unsure.
  1189. endmenu
  1190. config VM_EVENT_COUNTERS
  1191. default y
  1192. bool "Enable VM event counters for /proc/vmstat" if EXPERT
  1193. help
  1194. VM event counters are needed for event counts to be shown.
  1195. This option allows the disabling of the VM event counters
  1196. on EXPERT systems. /proc/vmstat will only show page counts
  1197. if VM event counters are disabled.
  1198. config PCI_QUIRKS
  1199. default y
  1200. bool "Enable PCI quirk workarounds" if EXPERT
  1201. depends on PCI
  1202. help
  1203. This enables workarounds for various PCI chipset
  1204. bugs/quirks. Disable this only if your target machine is
  1205. unaffected by PCI quirks.
  1206. config SLUB_DEBUG
  1207. default y
  1208. bool "Enable SLUB debugging support" if EXPERT
  1209. depends on SLUB && SYSFS
  1210. help
  1211. SLUB has extensive debug support features. Disabling these can
  1212. result in significant savings in code size. This also disables
  1213. SLUB sysfs support. /sys/slab will not exist and there will be
  1214. no support for cache validation etc.
  1215. config COMPAT_BRK
  1216. bool "Disable heap randomization"
  1217. default y
  1218. help
  1219. Randomizing heap placement makes heap exploits harder, but it
  1220. also breaks ancient binaries (including anything libc5 based).
  1221. This option changes the bootup default to heap randomization
  1222. disabled, and can be overridden at runtime by setting
  1223. /proc/sys/kernel/randomize_va_space to 2.
  1224. On non-ancient distros (post-2000 ones) N is usually a safe choice.
  1225. choice
  1226. prompt "Choose SLAB allocator"
  1227. default SLUB
  1228. help
  1229. This option allows to select a slab allocator.
  1230. config SLAB
  1231. bool "SLAB"
  1232. help
  1233. The regular slab allocator that is established and known to work
  1234. well in all environments. It organizes cache hot objects in
  1235. per cpu and per node queues.
  1236. config SLUB
  1237. bool "SLUB (Unqueued Allocator)"
  1238. help
  1239. SLUB is a slab allocator that minimizes cache line usage
  1240. instead of managing queues of cached objects (SLAB approach).
  1241. Per cpu caching is realized using slabs of objects instead
  1242. of queues of objects. SLUB can use memory efficiently
  1243. and has enhanced diagnostics. SLUB is the default choice for
  1244. a slab allocator.
  1245. config SLOB
  1246. depends on EXPERT
  1247. bool "SLOB (Simple Allocator)"
  1248. help
  1249. SLOB replaces the stock allocator with a drastically simpler
  1250. allocator. SLOB is generally more space efficient but
  1251. does not perform as well on large systems.
  1252. endchoice
  1253. config MMAP_ALLOW_UNINITIALIZED
  1254. bool "Allow mmapped anonymous memory to be uninitialized"
  1255. depends on EXPERT && !MMU
  1256. default n
  1257. help
  1258. Normally, and according to the Linux spec, anonymous memory obtained
  1259. from mmap() has it's contents cleared before it is passed to
  1260. userspace. Enabling this config option allows you to request that
  1261. mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
  1262. providing a huge performance boost. If this option is not enabled,
  1263. then the flag will be ignored.
  1264. This is taken advantage of by uClibc's malloc(), and also by
  1265. ELF-FDPIC binfmt's brk and stack allocator.
  1266. Because of the obvious security issues, this option should only be
  1267. enabled on embedded devices where you control what is run in
  1268. userspace. Since that isn't generally a problem on no-MMU systems,
  1269. it is normally safe to say Y here.
  1270. See Documentation/nommu-mmap.txt for more information.
  1271. config PROFILING
  1272. bool "Profiling support"
  1273. help
  1274. Say Y here to enable the extended profiling support mechanisms used
  1275. by profilers such as OProfile.
  1276. #
  1277. # Place an empty function call at each tracepoint site. Can be
  1278. # dynamically changed for a probe function.
  1279. #
  1280. config TRACEPOINTS
  1281. bool
  1282. source "arch/Kconfig"
  1283. endmenu # General setup
  1284. config HAVE_GENERIC_DMA_COHERENT
  1285. bool
  1286. default n
  1287. config SLABINFO
  1288. bool
  1289. depends on PROC_FS
  1290. depends on SLAB || SLUB_DEBUG
  1291. default y
  1292. config RT_MUTEXES
  1293. boolean
  1294. config BASE_SMALL
  1295. int
  1296. default 0 if BASE_FULL
  1297. default 1 if !BASE_FULL
  1298. menuconfig MODULES
  1299. bool "Enable loadable module support"
  1300. help
  1301. Kernel modules are small pieces of compiled code which can
  1302. be inserted in the running kernel, rather than being
  1303. permanently built into the kernel. You use the "modprobe"
  1304. tool to add (and sometimes remove) them. If you say Y here,
  1305. many parts of the kernel can be built as modules (by
  1306. answering M instead of Y where indicated): this is most
  1307. useful for infrequently used options which are not required
  1308. for booting. For more information, see the man pages for
  1309. modprobe, lsmod, modinfo, insmod and rmmod.
  1310. If you say Y here, you will need to run "make
  1311. modules_install" to put the modules under /lib/modules/
  1312. where modprobe can find them (you may need to be root to do
  1313. this).
  1314. If unsure, say Y.
  1315. if MODULES
  1316. config MODULE_FORCE_LOAD
  1317. bool "Forced module loading"
  1318. default n
  1319. help
  1320. Allow loading of modules without version information (ie. modprobe
  1321. --force). Forced module loading sets the 'F' (forced) taint flag and
  1322. is usually a really bad idea.
  1323. config MODULE_UNLOAD
  1324. bool "Module unloading"
  1325. help
  1326. Without this option you will not be able to unload any
  1327. modules (note that some modules may not be unloadable
  1328. anyway), which makes your kernel smaller, faster
  1329. and simpler. If unsure, say Y.
  1330. config MODULE_FORCE_UNLOAD
  1331. bool "Forced module unloading"
  1332. depends on MODULE_UNLOAD && EXPERIMENTAL
  1333. help
  1334. This option allows you to force a module to unload, even if the
  1335. kernel believes it is unsafe: the kernel will remove the module
  1336. without waiting for anyone to stop using it (using the -f option to
  1337. rmmod). This is mainly for kernel developers and desperate users.
  1338. If unsure, say N.
  1339. config MODVERSIONS
  1340. bool "Module versioning support"
  1341. help
  1342. Usually, you have to use modules compiled with your kernel.
  1343. Saying Y here makes it sometimes possible to use modules
  1344. compiled for different kernels, by adding enough information
  1345. to the modules to (hopefully) spot any changes which would
  1346. make them incompatible with the kernel you are running. If
  1347. unsure, say N.
  1348. config MODULE_SRCVERSION_ALL
  1349. bool "Source checksum for all modules"
  1350. help
  1351. Modules which contain a MODULE_VERSION get an extra "srcversion"
  1352. field inserted into their modinfo section, which contains a
  1353. sum of the source files which made it. This helps maintainers
  1354. see exactly which source was used to build a module (since
  1355. others sometimes change the module source without updating
  1356. the version). With this option, such a "srcversion" field
  1357. will be created for all modules. If unsure, say N.
  1358. endif # MODULES
  1359. config INIT_ALL_POSSIBLE
  1360. bool
  1361. help
  1362. Back when each arch used to define their own cpu_online_mask and
  1363. cpu_possible_mask, some of them chose to initialize cpu_possible_mask
  1364. with all 1s, and others with all 0s. When they were centralised,
  1365. it was better to provide this option than to break all the archs
  1366. and have several arch maintainers pursuing me down dark alleys.
  1367. config STOP_MACHINE
  1368. bool
  1369. default y
  1370. depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
  1371. help
  1372. Need stop_machine() primitive.
  1373. source "block/Kconfig"
  1374. config PREEMPT_NOTIFIERS
  1375. bool
  1376. config PADATA
  1377. depends on SMP
  1378. bool
  1379. source "kernel/Kconfig.locks"