Kconfig 39 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 drivers that have been replaced by something else, and/or are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. menuconfig CGROUPS
  390. boolean "Control Group support"
  391. depends on EVENTFD
  392. help
  393. This option adds support for grouping sets of processes together, for
  394. use with process control subsystems such as Cpusets, CFS, memory
  395. controls or device isolation.
  396. See
  397. - Documentation/scheduler/sched-design-CFS.txt (CFS)
  398. - Documentation/cgroups/ (features for grouping, isolation
  399. and resource control)
  400. Say N if unsure.
  401. if CGROUPS
  402. config CGROUP_DEBUG
  403. bool "Example debug cgroup subsystem"
  404. depends on CGROUPS
  405. default n
  406. help
  407. This option enables a simple cgroup subsystem that
  408. exports useful debugging information about the cgroups
  409. framework.
  410. Say N if unsure.
  411. config CGROUP_NS
  412. bool "Namespace cgroup subsystem"
  413. depends on CGROUPS
  414. help
  415. Provides a simple namespace cgroup subsystem to
  416. provide hierarchical naming of sets of namespaces,
  417. for instance virtual servers and checkpoint/restart
  418. jobs.
  419. config CGROUP_FREEZER
  420. bool "Freezer cgroup subsystem"
  421. depends on CGROUPS
  422. help
  423. Provides a way to freeze and unfreeze all tasks in a
  424. cgroup.
  425. config CGROUP_DEVICE
  426. bool "Device controller for cgroups"
  427. depends on CGROUPS && EXPERIMENTAL
  428. help
  429. Provides a cgroup implementing whitelists for devices which
  430. a process in the cgroup can mknod or open.
  431. config CPUSETS
  432. bool "Cpuset support"
  433. depends on CGROUPS
  434. help
  435. This option will let you create and manage CPUSETs which
  436. allow dynamically partitioning a system into sets of CPUs and
  437. Memory Nodes and assigning tasks to run only within those sets.
  438. This is primarily useful on large SMP or NUMA systems.
  439. Say N if unsure.
  440. config PROC_PID_CPUSET
  441. bool "Include legacy /proc/<pid>/cpuset file"
  442. depends on CPUSETS
  443. default y
  444. config CGROUP_CPUACCT
  445. bool "Simple CPU accounting cgroup subsystem"
  446. depends on CGROUPS
  447. help
  448. Provides a simple Resource Controller for monitoring the
  449. total CPU consumed by the tasks in a cgroup.
  450. config RESOURCE_COUNTERS
  451. bool "Resource counters"
  452. help
  453. This option enables controller independent resource accounting
  454. infrastructure that works with cgroups.
  455. depends on CGROUPS
  456. config CGROUP_MEM_RES_CTLR
  457. bool "Memory Resource Controller for Control Groups"
  458. depends on CGROUPS && RESOURCE_COUNTERS
  459. select MM_OWNER
  460. help
  461. Provides a memory resource controller that manages both anonymous
  462. memory and page cache. (See Documentation/cgroups/memory.txt)
  463. Note that setting this option increases fixed memory overhead
  464. associated with each page of memory in the system. By this,
  465. 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
  466. usage tracking struct at boot. Total amount of this is printed out
  467. at boot.
  468. Only enable when you're ok with these trade offs and really
  469. sure you need the memory resource controller. Even when you enable
  470. this, you can set "cgroup_disable=memory" at your boot option to
  471. disable memory resource controller and you can avoid overheads.
  472. (and lose benefits of memory resource controller)
  473. This config option also selects MM_OWNER config option, which
  474. could in turn add some fork/exit overhead.
  475. config CGROUP_MEM_RES_CTLR_SWAP
  476. bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)"
  477. depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL
  478. help
  479. Add swap management feature to memory resource controller. When you
  480. enable this, you can limit mem+swap usage per cgroup. In other words,
  481. when you disable this, memory resource controller has no cares to
  482. usage of swap...a process can exhaust all of the swap. This extension
  483. is useful when you want to avoid exhaustion swap but this itself
  484. adds more overheads and consumes memory for remembering information.
  485. Especially if you use 32bit system or small memory system, please
  486. be careful about enabling this. When memory resource controller
  487. is disabled by boot option, this will be automatically disabled and
  488. there will be no overhead from this. Even when you set this config=y,
  489. if boot option "noswapaccount" is set, swap will not be accounted.
  490. Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
  491. size is 4096bytes, 512k per 1Gbytes of swap.
  492. menuconfig CGROUP_SCHED
  493. bool "Group CPU scheduler"
  494. depends on EXPERIMENTAL && CGROUPS
  495. default n
  496. help
  497. This feature lets CPU scheduler recognize task groups and control CPU
  498. bandwidth allocation to such task groups. It uses cgroups to group
  499. tasks.
  500. if CGROUP_SCHED
  501. config FAIR_GROUP_SCHED
  502. bool "Group scheduling for SCHED_OTHER"
  503. depends on CGROUP_SCHED
  504. default CGROUP_SCHED
  505. config RT_GROUP_SCHED
  506. bool "Group scheduling for SCHED_RR/FIFO"
  507. depends on EXPERIMENTAL
  508. depends on CGROUP_SCHED
  509. default n
  510. help
  511. This feature lets you explicitly allocate real CPU bandwidth
  512. to users or control groups (depending on the "Basis for grouping tasks"
  513. setting below. If enabled, it will also make it impossible to
  514. schedule realtime tasks for non-root users until you allocate
  515. realtime bandwidth for them.
  516. See Documentation/scheduler/sched-rt-group.txt for more information.
  517. endif #CGROUP_SCHED
  518. endif # CGROUPS
  519. config MM_OWNER
  520. bool
  521. config SYSFS_DEPRECATED
  522. bool
  523. config SYSFS_DEPRECATED_V2
  524. bool "enable deprecated sysfs features to support old userspace tools"
  525. depends on SYSFS
  526. default n
  527. select SYSFS_DEPRECATED
  528. help
  529. This option switches the layout of sysfs to the deprecated
  530. version. Do not use it on recent distributions.
  531. The current sysfs layout features a unified device tree at
  532. /sys/devices/, which is able to express a hierarchy between
  533. class devices. If the deprecated option is set to Y, the
  534. unified device tree is split into a bus device tree at
  535. /sys/devices/ and several individual class device trees at
  536. /sys/class/. The class and bus devices will be connected by
  537. "<subsystem>:<name>" and the "device" links. The "block"
  538. class devices, will not show up in /sys/class/block/. Some
  539. subsystems will suppress the creation of some devices which
  540. depend on the unified device tree.
  541. This option is not a pure compatibility option that can
  542. be safely enabled on newer distributions. It will change the
  543. layout of sysfs to the non-extensible deprecated version,
  544. and disable some features, which can not be exported without
  545. confusing older userspace tools. Since 2007/2008 all major
  546. distributions do not enable this option, and ship no tools which
  547. depend on the deprecated layout or this option.
  548. If you are using a new kernel on an older distribution, or use
  549. older userspace tools, you might need to say Y here. Do not say Y,
  550. if the original kernel, that came with your distribution, has
  551. this option set to N.
  552. config RELAY
  553. bool "Kernel->user space relay support (formerly relayfs)"
  554. help
  555. This option enables support for relay interface support in
  556. certain file systems (such as debugfs).
  557. It is designed to provide an efficient mechanism for tools and
  558. facilities to relay large amounts of data from kernel space to
  559. user space.
  560. If unsure, say N.
  561. config NAMESPACES
  562. bool "Namespaces support" if EMBEDDED
  563. default !EMBEDDED
  564. help
  565. Provides the way to make tasks work with different objects using
  566. the same id. For example same IPC id may refer to different objects
  567. or same user id or pid may refer to different tasks when used in
  568. different namespaces.
  569. config UTS_NS
  570. bool "UTS namespace"
  571. depends on NAMESPACES
  572. help
  573. In this namespace tasks see different info provided with the
  574. uname() system call
  575. config IPC_NS
  576. bool "IPC namespace"
  577. depends on NAMESPACES && (SYSVIPC || POSIX_MQUEUE)
  578. help
  579. In this namespace tasks work with IPC ids which correspond to
  580. different IPC objects in different namespaces.
  581. config USER_NS
  582. bool "User namespace (EXPERIMENTAL)"
  583. depends on NAMESPACES && EXPERIMENTAL
  584. help
  585. This allows containers, i.e. vservers, to use user namespaces
  586. to provide different user info for different servers.
  587. If unsure, say N.
  588. config PID_NS
  589. bool "PID Namespaces (EXPERIMENTAL)"
  590. default n
  591. depends on NAMESPACES && EXPERIMENTAL
  592. help
  593. Support process id namespaces. This allows having multiple
  594. processes with the same pid as long as they are in different
  595. pid namespaces. This is a building block of containers.
  596. Unless you want to work with an experimental feature
  597. say N here.
  598. config NET_NS
  599. bool "Network namespace"
  600. default n
  601. depends on NAMESPACES && EXPERIMENTAL && NET
  602. help
  603. Allow user space to create what appear to be multiple instances
  604. of the network stack.
  605. config BLK_DEV_INITRD
  606. bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
  607. depends on BROKEN || !FRV
  608. help
  609. The initial RAM filesystem is a ramfs which is loaded by the
  610. boot loader (loadlin or lilo) and that is mounted as root
  611. before the normal boot procedure. It is typically used to
  612. load modules needed to mount the "real" root file system,
  613. etc. See <file:Documentation/initrd.txt> for details.
  614. If RAM disk support (BLK_DEV_RAM) is also included, this
  615. also enables initial RAM disk (initrd) support and adds
  616. 15 Kbytes (more on some other architectures) to the kernel size.
  617. If unsure say Y.
  618. if BLK_DEV_INITRD
  619. source "usr/Kconfig"
  620. endif
  621. config CC_OPTIMIZE_FOR_SIZE
  622. bool "Optimize for size"
  623. default y
  624. help
  625. Enabling this option will pass "-Os" instead of "-O2" to gcc
  626. resulting in a smaller kernel.
  627. If unsure, say Y.
  628. config SYSCTL
  629. bool
  630. config ANON_INODES
  631. bool
  632. menuconfig EMBEDDED
  633. bool "Configure standard kernel features (for small systems)"
  634. help
  635. This option allows certain base kernel options and settings
  636. to be disabled or tweaked. This is for specialized
  637. environments which can tolerate a "non-standard" kernel.
  638. Only use this if you really know what you are doing.
  639. config UID16
  640. bool "Enable 16-bit UID system calls" if EMBEDDED
  641. depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
  642. default y
  643. help
  644. This enables the legacy 16-bit UID syscall wrappers.
  645. config SYSCTL_SYSCALL
  646. bool "Sysctl syscall support" if EMBEDDED
  647. depends on PROC_SYSCTL
  648. default y
  649. select SYSCTL
  650. ---help---
  651. sys_sysctl uses binary paths that have been found challenging
  652. to properly maintain and use. The interface in /proc/sys
  653. using paths with ascii names is now the primary path to this
  654. information.
  655. Almost nothing using the binary sysctl interface so if you are
  656. trying to save some space it is probably safe to disable this,
  657. making your kernel marginally smaller.
  658. If unsure say Y here.
  659. config KALLSYMS
  660. bool "Load all symbols for debugging/ksymoops" if EMBEDDED
  661. default y
  662. help
  663. Say Y here to let the kernel print out symbolic crash information and
  664. symbolic stack backtraces. This increases the size of the kernel
  665. somewhat, as all symbols have to be loaded into the kernel image.
  666. config KALLSYMS_ALL
  667. bool "Include all symbols in kallsyms"
  668. depends on DEBUG_KERNEL && KALLSYMS
  669. help
  670. Normally kallsyms only contains the symbols of functions, for nicer
  671. OOPS messages. Some debuggers can use kallsyms for other
  672. symbols too: say Y here to include all symbols, if you need them
  673. and you don't care about adding 300k to the size of your kernel.
  674. Say N.
  675. config KALLSYMS_EXTRA_PASS
  676. bool "Do an extra kallsyms pass"
  677. depends on KALLSYMS
  678. help
  679. If kallsyms is not working correctly, the build will fail with
  680. inconsistent kallsyms data. If that occurs, log a bug report and
  681. turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
  682. Always say N here unless you find a bug in kallsyms, which must be
  683. reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
  684. you wait for kallsyms to be fixed.
  685. config HOTPLUG
  686. bool "Support for hot-pluggable devices" if EMBEDDED
  687. default y
  688. help
  689. This option is provided for the case where no hotplug or uevent
  690. capabilities is wanted by the kernel. You should only consider
  691. disabling this option for embedded systems that do not use modules, a
  692. dynamic /dev tree, or dynamic device discovery. Just say Y.
  693. config PRINTK
  694. default y
  695. bool "Enable support for printk" if EMBEDDED
  696. help
  697. This option enables normal printk support. Removing it
  698. eliminates most of the message strings from the kernel image
  699. and makes the kernel more or less silent. As this makes it
  700. very difficult to diagnose system problems, saying N here is
  701. strongly discouraged.
  702. config BUG
  703. bool "BUG() support" if EMBEDDED
  704. default y
  705. help
  706. Disabling this option eliminates support for BUG and WARN, reducing
  707. the size of your kernel image and potentially quietly ignoring
  708. numerous fatal conditions. You should only consider disabling this
  709. option for embedded systems with no facilities for reporting errors.
  710. Just say Y.
  711. config ELF_CORE
  712. default y
  713. bool "Enable ELF core dumps" if EMBEDDED
  714. help
  715. Enable support for generating core dumps. Disabling saves about 4k.
  716. config PCSPKR_PLATFORM
  717. bool "Enable PC-Speaker support" if EMBEDDED
  718. depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
  719. default y
  720. help
  721. This option allows to disable the internal PC-Speaker
  722. support, saving some memory.
  723. config BASE_FULL
  724. default y
  725. bool "Enable full-sized data structures for core" if EMBEDDED
  726. help
  727. Disabling this option reduces the size of miscellaneous core
  728. kernel data structures. This saves memory on small machines,
  729. but may reduce performance.
  730. config FUTEX
  731. bool "Enable futex support" if EMBEDDED
  732. default y
  733. select RT_MUTEXES
  734. help
  735. Disabling this option will cause the kernel to be built without
  736. support for "fast userspace mutexes". The resulting kernel may not
  737. run glibc-based applications correctly.
  738. config EPOLL
  739. bool "Enable eventpoll support" if EMBEDDED
  740. default y
  741. select ANON_INODES
  742. help
  743. Disabling this option will cause the kernel to be built without
  744. support for epoll family of system calls.
  745. config SIGNALFD
  746. bool "Enable signalfd() system call" if EMBEDDED
  747. select ANON_INODES
  748. default y
  749. help
  750. Enable the signalfd() system call that allows to receive signals
  751. on a file descriptor.
  752. If unsure, say Y.
  753. config TIMERFD
  754. bool "Enable timerfd() system call" if EMBEDDED
  755. select ANON_INODES
  756. default y
  757. help
  758. Enable the timerfd() system call that allows to receive timer
  759. events on a file descriptor.
  760. If unsure, say Y.
  761. config EVENTFD
  762. bool "Enable eventfd() system call" if EMBEDDED
  763. select ANON_INODES
  764. default y
  765. help
  766. Enable the eventfd() system call that allows to receive both
  767. kernel notification (ie. KAIO) or userspace notifications.
  768. If unsure, say Y.
  769. config SHMEM
  770. bool "Use full shmem filesystem" if EMBEDDED
  771. default y
  772. depends on MMU
  773. help
  774. The shmem is an internal filesystem used to manage shared memory.
  775. It is backed by swap and manages resource limits. It is also exported
  776. to userspace as tmpfs if TMPFS is enabled. Disabling this
  777. option replaces shmem and tmpfs with the much simpler ramfs code,
  778. which may be appropriate on small systems without swap.
  779. config AIO
  780. bool "Enable AIO support" if EMBEDDED
  781. default y
  782. help
  783. This option enables POSIX asynchronous I/O which may by used
  784. by some high performance threaded applications. Disabling
  785. this option saves about 7k.
  786. config HAVE_PERF_EVENTS
  787. bool
  788. help
  789. See tools/perf/design.txt for details.
  790. config PERF_USE_VMALLOC
  791. bool
  792. help
  793. See tools/perf/design.txt for details
  794. menu "Kernel Performance Events And Counters"
  795. config PERF_EVENTS
  796. bool "Kernel performance events and counters"
  797. default y if (PROFILING || PERF_COUNTERS)
  798. depends on HAVE_PERF_EVENTS
  799. select ANON_INODES
  800. help
  801. Enable kernel support for various performance events provided
  802. by software and hardware.
  803. Software events are supported either built-in or via the
  804. use of generic tracepoints.
  805. Most modern CPUs support performance events via performance
  806. counter registers. These registers count the number of certain
  807. types of hw events: such as instructions executed, cachemisses
  808. suffered, or branches mis-predicted - without slowing down the
  809. kernel or applications. These registers can also trigger interrupts
  810. when a threshold number of events have passed - and can thus be
  811. used to profile the code that runs on that CPU.
  812. The Linux Performance Event subsystem provides an abstraction of
  813. these software and hardware event capabilities, available via a
  814. system call and used by the "perf" utility in tools/perf/. It
  815. provides per task and per CPU counters, and it provides event
  816. capabilities on top of those.
  817. Say Y if unsure.
  818. config PERF_COUNTERS
  819. bool "Kernel performance counters (old config option)"
  820. depends on HAVE_PERF_EVENTS
  821. help
  822. This config has been obsoleted by the PERF_EVENTS
  823. config option - please see that one for details.
  824. It has no effect on the kernel whether you enable
  825. it or not, it is a compatibility placeholder.
  826. Say N if unsure.
  827. config DEBUG_PERF_USE_VMALLOC
  828. default n
  829. bool "Debug: use vmalloc to back perf mmap() buffers"
  830. depends on PERF_EVENTS && DEBUG_KERNEL
  831. select PERF_USE_VMALLOC
  832. help
  833. Use vmalloc memory to back perf mmap() buffers.
  834. Mostly useful for debugging the vmalloc code on platforms
  835. that don't require it.
  836. Say N if unsure.
  837. endmenu
  838. config VM_EVENT_COUNTERS
  839. default y
  840. bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
  841. help
  842. VM event counters are needed for event counts to be shown.
  843. This option allows the disabling of the VM event counters
  844. on EMBEDDED systems. /proc/vmstat will only show page counts
  845. if VM event counters are disabled.
  846. config PCI_QUIRKS
  847. default y
  848. bool "Enable PCI quirk workarounds" if EMBEDDED
  849. depends on PCI
  850. help
  851. This enables workarounds for various PCI chipset
  852. bugs/quirks. Disable this only if your target machine is
  853. unaffected by PCI quirks.
  854. config SLUB_DEBUG
  855. default y
  856. bool "Enable SLUB debugging support" if EMBEDDED
  857. depends on SLUB && SYSFS
  858. help
  859. SLUB has extensive debug support features. Disabling these can
  860. result in significant savings in code size. This also disables
  861. SLUB sysfs support. /sys/slab will not exist and there will be
  862. no support for cache validation etc.
  863. config COMPAT_BRK
  864. bool "Disable heap randomization"
  865. default y
  866. help
  867. Randomizing heap placement makes heap exploits harder, but it
  868. also breaks ancient binaries (including anything libc5 based).
  869. This option changes the bootup default to heap randomization
  870. disabled, and can be overridden at runtime by setting
  871. /proc/sys/kernel/randomize_va_space to 2.
  872. On non-ancient distros (post-2000 ones) N is usually a safe choice.
  873. choice
  874. prompt "Choose SLAB allocator"
  875. default SLUB
  876. help
  877. This option allows to select a slab allocator.
  878. config SLAB
  879. bool "SLAB"
  880. help
  881. The regular slab allocator that is established and known to work
  882. well in all environments. It organizes cache hot objects in
  883. per cpu and per node queues.
  884. config SLUB
  885. bool "SLUB (Unqueued Allocator)"
  886. help
  887. SLUB is a slab allocator that minimizes cache line usage
  888. instead of managing queues of cached objects (SLAB approach).
  889. Per cpu caching is realized using slabs of objects instead
  890. of queues of objects. SLUB can use memory efficiently
  891. and has enhanced diagnostics. SLUB is the default choice for
  892. a slab allocator.
  893. config SLOB
  894. depends on EMBEDDED
  895. bool "SLOB (Simple Allocator)"
  896. help
  897. SLOB replaces the stock allocator with a drastically simpler
  898. allocator. SLOB is generally more space efficient but
  899. does not perform as well on large systems.
  900. endchoice
  901. config MMAP_ALLOW_UNINITIALIZED
  902. bool "Allow mmapped anonymous memory to be uninitialized"
  903. depends on EMBEDDED && !MMU
  904. default n
  905. help
  906. Normally, and according to the Linux spec, anonymous memory obtained
  907. from mmap() has it's contents cleared before it is passed to
  908. userspace. Enabling this config option allows you to request that
  909. mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
  910. providing a huge performance boost. If this option is not enabled,
  911. then the flag will be ignored.
  912. This is taken advantage of by uClibc's malloc(), and also by
  913. ELF-FDPIC binfmt's brk and stack allocator.
  914. Because of the obvious security issues, this option should only be
  915. enabled on embedded devices where you control what is run in
  916. userspace. Since that isn't generally a problem on no-MMU systems,
  917. it is normally safe to say Y here.
  918. See Documentation/nommu-mmap.txt for more information.
  919. config PROFILING
  920. bool "Profiling support"
  921. help
  922. Say Y here to enable the extended profiling support mechanisms used
  923. by profilers such as OProfile.
  924. #
  925. # Place an empty function call at each tracepoint site. Can be
  926. # dynamically changed for a probe function.
  927. #
  928. config TRACEPOINTS
  929. bool
  930. source "arch/Kconfig"
  931. config SLOW_WORK
  932. default n
  933. bool
  934. help
  935. The slow work thread pool provides a number of dynamically allocated
  936. threads that can be used by the kernel to perform operations that
  937. take a relatively long time.
  938. An example of this would be CacheFiles doing a path lookup followed
  939. by a series of mkdirs and a create call, all of which have to touch
  940. disk.
  941. See Documentation/slow-work.txt.
  942. config SLOW_WORK_DEBUG
  943. bool "Slow work debugging through debugfs"
  944. default n
  945. depends on SLOW_WORK && DEBUG_FS
  946. help
  947. Display the contents of the slow work run queue through debugfs,
  948. including items currently executing.
  949. See Documentation/slow-work.txt.
  950. endmenu # General setup
  951. config HAVE_GENERIC_DMA_COHERENT
  952. bool
  953. default n
  954. config SLABINFO
  955. bool
  956. depends on PROC_FS
  957. depends on SLAB || SLUB_DEBUG
  958. default y
  959. config RT_MUTEXES
  960. boolean
  961. config BASE_SMALL
  962. int
  963. default 0 if BASE_FULL
  964. default 1 if !BASE_FULL
  965. menuconfig MODULES
  966. bool "Enable loadable module support"
  967. help
  968. Kernel modules are small pieces of compiled code which can
  969. be inserted in the running kernel, rather than being
  970. permanently built into the kernel. You use the "modprobe"
  971. tool to add (and sometimes remove) them. If you say Y here,
  972. many parts of the kernel can be built as modules (by
  973. answering M instead of Y where indicated): this is most
  974. useful for infrequently used options which are not required
  975. for booting. For more information, see the man pages for
  976. modprobe, lsmod, modinfo, insmod and rmmod.
  977. If you say Y here, you will need to run "make
  978. modules_install" to put the modules under /lib/modules/
  979. where modprobe can find them (you may need to be root to do
  980. this).
  981. If unsure, say Y.
  982. if MODULES
  983. config MODULE_FORCE_LOAD
  984. bool "Forced module loading"
  985. default n
  986. help
  987. Allow loading of modules without version information (ie. modprobe
  988. --force). Forced module loading sets the 'F' (forced) taint flag and
  989. is usually a really bad idea.
  990. config MODULE_UNLOAD
  991. bool "Module unloading"
  992. help
  993. Without this option you will not be able to unload any
  994. modules (note that some modules may not be unloadable
  995. anyway), which makes your kernel smaller, faster
  996. and simpler. If unsure, say Y.
  997. config MODULE_FORCE_UNLOAD
  998. bool "Forced module unloading"
  999. depends on MODULE_UNLOAD && EXPERIMENTAL
  1000. help
  1001. This option allows you to force a module to unload, even if the
  1002. kernel believes it is unsafe: the kernel will remove the module
  1003. without waiting for anyone to stop using it (using the -f option to
  1004. rmmod). This is mainly for kernel developers and desperate users.
  1005. If unsure, say N.
  1006. config MODVERSIONS
  1007. bool "Module versioning support"
  1008. help
  1009. Usually, you have to use modules compiled with your kernel.
  1010. Saying Y here makes it sometimes possible to use modules
  1011. compiled for different kernels, by adding enough information
  1012. to the modules to (hopefully) spot any changes which would
  1013. make them incompatible with the kernel you are running. If
  1014. unsure, say N.
  1015. config MODULE_SRCVERSION_ALL
  1016. bool "Source checksum for all modules"
  1017. help
  1018. Modules which contain a MODULE_VERSION get an extra "srcversion"
  1019. field inserted into their modinfo section, which contains a
  1020. sum of the source files which made it. This helps maintainers
  1021. see exactly which source was used to build a module (since
  1022. others sometimes change the module source without updating
  1023. the version). With this option, such a "srcversion" field
  1024. will be created for all modules. If unsure, say N.
  1025. endif # MODULES
  1026. config INIT_ALL_POSSIBLE
  1027. bool
  1028. help
  1029. Back when each arch used to define their own cpu_online_map and
  1030. cpu_possible_map, some of them chose to initialize cpu_possible_map
  1031. with all 1s, and others with all 0s. When they were centralised,
  1032. it was better to provide this option than to break all the archs
  1033. and have several arch maintainers pursuing me down dark alleys.
  1034. config STOP_MACHINE
  1035. bool
  1036. default y
  1037. depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
  1038. help
  1039. Need stop_machine() primitive.
  1040. source "block/Kconfig"
  1041. config PREEMPT_NOTIFIERS
  1042. bool
  1043. config PADATA
  1044. depends on SMP
  1045. bool
  1046. source "kernel/Kconfig.locks"