Kconfig 40 KB

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 drivers that have been replaced by something else, and/or are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