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 drivers that have been replaced by something else, and/or are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