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 drivers that have been replaced by something else, and/or are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