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 drivers that have been replaced by something else, and/or are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. help
  287. This option selects the RCU implementation that is
  288. designed for very large SMP system with hundreds or
  289. thousands of CPUs. It also scales down nicely to
  290. smaller systems.
  291. config TREE_PREEMPT_RCU
  292. bool "Preemptable tree-based hierarchical RCU"
  293. depends on PREEMPT
  294. help
  295. This option selects the RCU implementation that is
  296. designed for very large SMP systems with hundreds or
  297. thousands of CPUs, but for which real-time response
  298. is also required. It also scales down nicely to
  299. smaller systems.
  300. config TINY_RCU
  301. bool "UP-only small-memory-footprint RCU"
  302. depends on !SMP
  303. help
  304. This option selects the RCU implementation that is
  305. designed for UP systems from which real-time response
  306. is not required. This option greatly reduces the
  307. memory footprint of RCU.
  308. endchoice
  309. config RCU_TRACE
  310. bool "Enable tracing for RCU"
  311. depends on TREE_RCU || TREE_PREEMPT_RCU
  312. help
  313. This option provides tracing in RCU which presents stats
  314. in debugfs for debugging RCU implementation.
  315. Say Y here if you want to enable RCU tracing
  316. Say N if you are unsure.
  317. config RCU_FANOUT
  318. int "Tree-based hierarchical RCU fanout value"
  319. range 2 64 if 64BIT
  320. range 2 32 if !64BIT
  321. depends on TREE_RCU || TREE_PREEMPT_RCU
  322. default 64 if 64BIT
  323. default 32 if !64BIT
  324. help
  325. This option controls the fanout of hierarchical implementations
  326. of RCU, allowing RCU to work efficiently on machines with
  327. large numbers of CPUs. This value must be at least the cube
  328. root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
  329. systems and up to 262,144 for 64-bit systems.
  330. Select a specific number if testing RCU itself.
  331. Take the default if unsure.
  332. config RCU_FANOUT_EXACT
  333. bool "Disable tree-based hierarchical RCU auto-balancing"
  334. depends on TREE_RCU || TREE_PREEMPT_RCU
  335. default n
  336. help
  337. This option forces use of the exact RCU_FANOUT value specified,
  338. regardless of imbalances in the hierarchy. This is useful for
  339. testing RCU itself, and might one day be useful on systems with
  340. strong NUMA behavior.
  341. Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
  342. Say N if unsure.
  343. config RCU_FAST_NO_HZ
  344. bool "Accelerate last non-dyntick-idle CPU's grace periods"
  345. depends on TREE_RCU && NO_HZ && SMP
  346. default n
  347. help
  348. This option causes RCU to attempt to accelerate grace periods
  349. in order to allow the final CPU to enter dynticks-idle state
  350. more quickly. On the other hand, this option increases the
  351. overhead of the dynticks-idle checking, particularly on systems
  352. with large numbers of CPUs.
  353. Say Y if energy efficiency is critically important, particularly
  354. if you have relatively few CPUs.
  355. Say N if you are unsure.
  356. config TREE_RCU_TRACE
  357. def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
  358. select DEBUG_FS
  359. help
  360. This option provides tracing for the TREE_RCU and
  361. TREE_PREEMPT_RCU implementations, permitting Makefile to
  362. trivially select kernel/rcutree_trace.c.
  363. endmenu # "RCU Subsystem"
  364. config IKCONFIG
  365. tristate "Kernel .config support"
  366. ---help---
  367. This option enables the complete Linux kernel ".config" file
  368. contents to be saved in the kernel. It provides documentation
  369. of which kernel options are used in a running kernel or in an
  370. on-disk kernel. This information can be extracted from the kernel
  371. image file with the script scripts/extract-ikconfig and used as
  372. input to rebuild the current kernel or to build another kernel.
  373. It can also be extracted from a running kernel by reading
  374. /proc/config.gz if enabled (below).
  375. config IKCONFIG_PROC
  376. bool "Enable access to .config through /proc/config.gz"
  377. depends on IKCONFIG && PROC_FS
  378. ---help---
  379. This option enables access to the kernel configuration file
  380. through /proc/config.gz.
  381. config LOG_BUF_SHIFT
  382. int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
  383. range 12 21
  384. default 17
  385. help
  386. Select kernel log buffer size as a power of 2.
  387. Examples:
  388. 17 => 128 KB
  389. 16 => 64 KB
  390. 15 => 32 KB
  391. 14 => 16 KB
  392. 13 => 8 KB
  393. 12 => 4 KB
  394. #
  395. # Architectures with an unreliable sched_clock() should select this:
  396. #
  397. config HAVE_UNSTABLE_SCHED_CLOCK
  398. bool
  399. menuconfig CGROUPS
  400. boolean "Control Group support"
  401. depends on EVENTFD
  402. help
  403. This option adds support for grouping sets of processes together, for
  404. use with process control subsystems such as Cpusets, CFS, memory
  405. controls or device isolation.
  406. See
  407. - Documentation/scheduler/sched-design-CFS.txt (CFS)
  408. - Documentation/cgroups/ (features for grouping, isolation
  409. and resource control)
  410. Say N if unsure.
  411. if CGROUPS
  412. config CGROUP_DEBUG
  413. bool "Example debug cgroup subsystem"
  414. depends on CGROUPS
  415. default n
  416. help
  417. This option enables a simple cgroup subsystem that
  418. exports useful debugging information about the cgroups
  419. framework.
  420. Say N if unsure.
  421. config CGROUP_NS
  422. bool "Namespace cgroup subsystem"
  423. depends on CGROUPS
  424. help
  425. Provides a simple namespace cgroup subsystem to
  426. provide hierarchical naming of sets of namespaces,
  427. for instance virtual servers and checkpoint/restart
  428. jobs.
  429. config CGROUP_FREEZER
  430. bool "Freezer cgroup subsystem"
  431. depends on CGROUPS
  432. help
  433. Provides a way to freeze and unfreeze all tasks in a
  434. cgroup.
  435. config CGROUP_DEVICE
  436. bool "Device controller for cgroups"
  437. depends on CGROUPS && EXPERIMENTAL
  438. help
  439. Provides a cgroup implementing whitelists for devices which
  440. a process in the cgroup can mknod or open.
  441. config CPUSETS
  442. bool "Cpuset support"
  443. depends on CGROUPS
  444. help
  445. This option will let you create and manage CPUSETs which
  446. allow dynamically partitioning a system into sets of CPUs and
  447. Memory Nodes and assigning tasks to run only within those sets.
  448. This is primarily useful on large SMP or NUMA systems.
  449. Say N if unsure.
  450. config PROC_PID_CPUSET
  451. bool "Include legacy /proc/<pid>/cpuset file"
  452. depends on CPUSETS
  453. default y
  454. config CGROUP_CPUACCT
  455. bool "Simple CPU accounting cgroup subsystem"
  456. depends on CGROUPS
  457. help
  458. Provides a simple Resource Controller for monitoring the
  459. total CPU consumed by the tasks in a cgroup.
  460. config RESOURCE_COUNTERS
  461. bool "Resource counters"
  462. help
  463. This option enables controller independent resource accounting
  464. infrastructure that works with cgroups.
  465. depends on CGROUPS
  466. config CGROUP_MEM_RES_CTLR
  467. bool "Memory Resource Controller for Control Groups"
  468. depends on CGROUPS && RESOURCE_COUNTERS
  469. select MM_OWNER
  470. help
  471. Provides a memory resource controller that manages both anonymous
  472. memory and page cache. (See Documentation/cgroups/memory.txt)
  473. Note that setting this option increases fixed memory overhead
  474. associated with each page of memory in the system. By this,
  475. 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
  476. usage tracking struct at boot. Total amount of this is printed out
  477. at boot.
  478. Only enable when you're ok with these trade offs and really
  479. sure you need the memory resource controller. Even when you enable
  480. this, you can set "cgroup_disable=memory" at your boot option to
  481. disable memory resource controller and you can avoid overheads.
  482. (and lose benefits of memory resource controller)
  483. This config option also selects MM_OWNER config option, which
  484. could in turn add some fork/exit overhead.
  485. config CGROUP_MEM_RES_CTLR_SWAP
  486. bool "Memory Resource Controller Swap Extension"
  487. depends on CGROUP_MEM_RES_CTLR && SWAP
  488. help
  489. Add swap management feature to memory resource controller. When you
  490. enable this, you can limit mem+swap usage per cgroup. In other words,
  491. when you disable this, memory resource controller has no cares to
  492. usage of swap...a process can exhaust all of the swap. This extension
  493. is useful when you want to avoid exhaustion swap but this itself
  494. adds more overheads and consumes memory for remembering information.
  495. Especially if you use 32bit system or small memory system, please
  496. be careful about enabling this. When memory resource controller
  497. is disabled by boot option, this will be automatically disabled and
  498. there will be no overhead from this. Even when you set this config=y,
  499. if boot option "noswapaccount" is set, swap will not be accounted.
  500. Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
  501. size is 4096bytes, 512k per 1Gbytes of swap.
  502. menuconfig CGROUP_SCHED
  503. bool "Group CPU scheduler"
  504. depends on EXPERIMENTAL && CGROUPS
  505. default n
  506. help
  507. This feature lets CPU scheduler recognize task groups and control CPU
  508. bandwidth allocation to such task groups. It uses cgroups to group
  509. tasks.
  510. if CGROUP_SCHED
  511. config FAIR_GROUP_SCHED
  512. bool "Group scheduling for SCHED_OTHER"
  513. depends on CGROUP_SCHED
  514. default CGROUP_SCHED
  515. config RT_GROUP_SCHED
  516. bool "Group scheduling for SCHED_RR/FIFO"
  517. depends on EXPERIMENTAL
  518. depends on CGROUP_SCHED
  519. default n
  520. help
  521. This feature lets you explicitly allocate real CPU bandwidth
  522. to task groups. If enabled, it will also make it impossible to
  523. schedule realtime tasks for non-root users until you allocate
  524. realtime bandwidth for them.
  525. See Documentation/scheduler/sched-rt-group.txt for more information.
  526. endif #CGROUP_SCHED
  527. config BLK_CGROUP
  528. tristate "Block IO controller"
  529. depends on CGROUPS && BLOCK
  530. default n
  531. ---help---
  532. Generic block IO controller cgroup interface. This is the common
  533. cgroup interface which should be used by various IO controlling
  534. policies.
  535. Currently, CFQ IO scheduler uses it to recognize task groups and
  536. control disk bandwidth allocation (proportional time slice allocation)
  537. to such task groups.
  538. This option only enables generic Block IO controller infrastructure.
  539. One needs to also enable actual IO controlling logic in CFQ for it
  540. to take effect. (CONFIG_CFQ_GROUP_IOSCHED=y).
  541. See Documentation/cgroups/blkio-controller.txt for more information.
  542. config DEBUG_BLK_CGROUP
  543. bool "Enable Block IO controller debugging"
  544. depends on BLK_CGROUP
  545. default n
  546. ---help---
  547. Enable some debugging help. Currently it exports additional stat
  548. files in a cgroup which can be useful for debugging.
  549. endif # CGROUPS
  550. config MM_OWNER
  551. bool
  552. config SYSFS_DEPRECATED
  553. bool
  554. config SYSFS_DEPRECATED_V2
  555. bool "enable deprecated sysfs features to support old userspace tools"
  556. depends on SYSFS
  557. default n
  558. select SYSFS_DEPRECATED
  559. help
  560. This option switches the layout of sysfs to the deprecated
  561. version. Do not use it on recent distributions.
  562. The current sysfs layout features a unified device tree at
  563. /sys/devices/, which is able to express a hierarchy between
  564. class devices. If the deprecated option is set to Y, the
  565. unified device tree is split into a bus device tree at
  566. /sys/devices/ and several individual class device trees at
  567. /sys/class/. The class and bus devices will be connected by
  568. "<subsystem>:<name>" and the "device" links. The "block"
  569. class devices, will not show up in /sys/class/block/. Some
  570. subsystems will suppress the creation of some devices which
  571. depend on the unified device tree.
  572. This option is not a pure compatibility option that can
  573. be safely enabled on newer distributions. It will change the
  574. layout of sysfs to the non-extensible deprecated version,
  575. and disable some features, which can not be exported without
  576. confusing older userspace tools. Since 2007/2008 all major
  577. distributions do not enable this option, and ship no tools which
  578. depend on the deprecated layout or this option.
  579. If you are using a new kernel on an older distribution, or use
  580. older userspace tools, you might need to say Y here. Do not say Y,
  581. if the original kernel, that came with your distribution, has
  582. this option set to N.
  583. config RELAY
  584. bool "Kernel->user space relay support (formerly relayfs)"
  585. help
  586. This option enables support for relay interface support in
  587. certain file systems (such as debugfs).
  588. It is designed to provide an efficient mechanism for tools and
  589. facilities to relay large amounts of data from kernel space to
  590. user space.
  591. If unsure, say N.
  592. config NAMESPACES
  593. bool "Namespaces support" if EMBEDDED
  594. default !EMBEDDED
  595. help
  596. Provides the way to make tasks work with different objects using
  597. the same id. For example same IPC id may refer to different objects
  598. or same user id or pid may refer to different tasks when used in
  599. different namespaces.
  600. config UTS_NS
  601. bool "UTS namespace"
  602. depends on NAMESPACES
  603. help
  604. In this namespace tasks see different info provided with the
  605. uname() system call
  606. config IPC_NS
  607. bool "IPC namespace"
  608. depends on NAMESPACES && (SYSVIPC || POSIX_MQUEUE)
  609. help
  610. In this namespace tasks work with IPC ids which correspond to
  611. different IPC objects in different namespaces.
  612. config USER_NS
  613. bool "User namespace (EXPERIMENTAL)"
  614. depends on NAMESPACES && EXPERIMENTAL
  615. help
  616. This allows containers, i.e. vservers, to use user namespaces
  617. to provide different user info for different servers.
  618. If unsure, say N.
  619. config PID_NS
  620. bool "PID Namespaces (EXPERIMENTAL)"
  621. default n
  622. depends on NAMESPACES && EXPERIMENTAL
  623. help
  624. Support process id namespaces. This allows having multiple
  625. processes with the same pid as long as they are in different
  626. pid namespaces. This is a building block of containers.
  627. Unless you want to work with an experimental feature
  628. say N here.
  629. config NET_NS
  630. bool "Network namespace"
  631. default n
  632. depends on NAMESPACES && EXPERIMENTAL && NET
  633. help
  634. Allow user space to create what appear to be multiple instances
  635. of the network stack.
  636. config BLK_DEV_INITRD
  637. bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
  638. depends on BROKEN || !FRV
  639. help
  640. The initial RAM filesystem is a ramfs which is loaded by the
  641. boot loader (loadlin or lilo) and that is mounted as root
  642. before the normal boot procedure. It is typically used to
  643. load modules needed to mount the "real" root file system,
  644. etc. See <file:Documentation/initrd.txt> for details.
  645. If RAM disk support (BLK_DEV_RAM) is also included, this
  646. also enables initial RAM disk (initrd) support and adds
  647. 15 Kbytes (more on some other architectures) to the kernel size.
  648. If unsure say Y.
  649. if BLK_DEV_INITRD
  650. source "usr/Kconfig"
  651. endif
  652. config CC_OPTIMIZE_FOR_SIZE
  653. bool "Optimize for size"
  654. default y
  655. help
  656. Enabling this option will pass "-Os" instead of "-O2" to gcc
  657. resulting in a smaller kernel.
  658. If unsure, say Y.
  659. config SYSCTL
  660. bool
  661. config ANON_INODES
  662. bool
  663. menuconfig EMBEDDED
  664. bool "Configure standard kernel features (for small systems)"
  665. help
  666. This option allows certain base kernel options and settings
  667. to be disabled or tweaked. This is for specialized
  668. environments which can tolerate a "non-standard" kernel.
  669. Only use this if you really know what you are doing.
  670. config UID16
  671. bool "Enable 16-bit UID system calls" if EMBEDDED
  672. depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
  673. default y
  674. help
  675. This enables the legacy 16-bit UID syscall wrappers.
  676. config SYSCTL_SYSCALL
  677. bool "Sysctl syscall support" if EMBEDDED
  678. depends on PROC_SYSCTL
  679. default y
  680. select SYSCTL
  681. ---help---
  682. sys_sysctl uses binary paths that have been found challenging
  683. to properly maintain and use. The interface in /proc/sys
  684. using paths with ascii names is now the primary path to this
  685. information.
  686. Almost nothing using the binary sysctl interface so if you are
  687. trying to save some space it is probably safe to disable this,
  688. making your kernel marginally smaller.
  689. If unsure say Y here.
  690. config KALLSYMS
  691. bool "Load all symbols for debugging/ksymoops" if EMBEDDED
  692. default y
  693. help
  694. Say Y here to let the kernel print out symbolic crash information and
  695. symbolic stack backtraces. This increases the size of the kernel
  696. somewhat, as all symbols have to be loaded into the kernel image.
  697. config KALLSYMS_ALL
  698. bool "Include all symbols in kallsyms"
  699. depends on DEBUG_KERNEL && KALLSYMS
  700. help
  701. Normally kallsyms only contains the symbols of functions, for nicer
  702. OOPS messages. Some debuggers can use kallsyms for other
  703. symbols too: say Y here to include all symbols, if you need them
  704. and you don't care about adding 300k to the size of your kernel.
  705. Say N.
  706. config KALLSYMS_EXTRA_PASS
  707. bool "Do an extra kallsyms pass"
  708. depends on KALLSYMS
  709. help
  710. If kallsyms is not working correctly, the build will fail with
  711. inconsistent kallsyms data. If that occurs, log a bug report and
  712. turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
  713. Always say N here unless you find a bug in kallsyms, which must be
  714. reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
  715. you wait for kallsyms to be fixed.
  716. config HOTPLUG
  717. bool "Support for hot-pluggable devices" if EMBEDDED
  718. default y
  719. help
  720. This option is provided for the case where no hotplug or uevent
  721. capabilities is wanted by the kernel. You should only consider
  722. disabling this option for embedded systems that do not use modules, a
  723. dynamic /dev tree, or dynamic device discovery. Just say Y.
  724. config PRINTK
  725. default y
  726. bool "Enable support for printk" if EMBEDDED
  727. help
  728. This option enables normal printk support. Removing it
  729. eliminates most of the message strings from the kernel image
  730. and makes the kernel more or less silent. As this makes it
  731. very difficult to diagnose system problems, saying N here is
  732. strongly discouraged.
  733. config BUG
  734. bool "BUG() support" if EMBEDDED
  735. default y
  736. help
  737. Disabling this option eliminates support for BUG and WARN, reducing
  738. the size of your kernel image and potentially quietly ignoring
  739. numerous fatal conditions. You should only consider disabling this
  740. option for embedded systems with no facilities for reporting errors.
  741. Just say Y.
  742. config ELF_CORE
  743. default y
  744. bool "Enable ELF core dumps" if EMBEDDED
  745. help
  746. Enable support for generating core dumps. Disabling saves about 4k.
  747. config PCSPKR_PLATFORM
  748. bool "Enable PC-Speaker support" if EMBEDDED
  749. depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
  750. default y
  751. help
  752. This option allows to disable the internal PC-Speaker
  753. support, saving some memory.
  754. config BASE_FULL
  755. default y
  756. bool "Enable full-sized data structures for core" if EMBEDDED
  757. help
  758. Disabling this option reduces the size of miscellaneous core
  759. kernel data structures. This saves memory on small machines,
  760. but may reduce performance.
  761. config FUTEX
  762. bool "Enable futex support" if EMBEDDED
  763. default y
  764. select RT_MUTEXES
  765. help
  766. Disabling this option will cause the kernel to be built without
  767. support for "fast userspace mutexes". The resulting kernel may not
  768. run glibc-based applications correctly.
  769. config EPOLL
  770. bool "Enable eventpoll support" if EMBEDDED
  771. default y
  772. select ANON_INODES
  773. help
  774. Disabling this option will cause the kernel to be built without
  775. support for epoll family of system calls.
  776. config SIGNALFD
  777. bool "Enable signalfd() system call" if EMBEDDED
  778. select ANON_INODES
  779. default y
  780. help
  781. Enable the signalfd() system call that allows to receive signals
  782. on a file descriptor.
  783. If unsure, say Y.
  784. config TIMERFD
  785. bool "Enable timerfd() system call" if EMBEDDED
  786. select ANON_INODES
  787. default y
  788. help
  789. Enable the timerfd() system call that allows to receive timer
  790. events on a file descriptor.
  791. If unsure, say Y.
  792. config EVENTFD
  793. bool "Enable eventfd() system call" if EMBEDDED
  794. select ANON_INODES
  795. default y
  796. help
  797. Enable the eventfd() system call that allows to receive both
  798. kernel notification (ie. KAIO) or userspace notifications.
  799. If unsure, say Y.
  800. config SHMEM
  801. bool "Use full shmem filesystem" if EMBEDDED
  802. default y
  803. depends on MMU
  804. help
  805. The shmem is an internal filesystem used to manage shared memory.
  806. It is backed by swap and manages resource limits. It is also exported
  807. to userspace as tmpfs if TMPFS is enabled. Disabling this
  808. option replaces shmem and tmpfs with the much simpler ramfs code,
  809. which may be appropriate on small systems without swap.
  810. config AIO
  811. bool "Enable AIO support" if EMBEDDED
  812. default y
  813. help
  814. This option enables POSIX asynchronous I/O which may by used
  815. by some high performance threaded applications. Disabling
  816. this option saves about 7k.
  817. config HAVE_PERF_EVENTS
  818. bool
  819. help
  820. See tools/perf/design.txt for details.
  821. config PERF_USE_VMALLOC
  822. bool
  823. help
  824. See tools/perf/design.txt for details
  825. menu "Kernel Performance Events And Counters"
  826. config PERF_EVENTS
  827. bool "Kernel performance events and counters"
  828. default y if (PROFILING || PERF_COUNTERS)
  829. depends on HAVE_PERF_EVENTS
  830. select ANON_INODES
  831. help
  832. Enable kernel support for various performance events provided
  833. by software and hardware.
  834. Software events are supported either built-in or via the
  835. use of generic tracepoints.
  836. Most modern CPUs support performance events via performance
  837. counter registers. These registers count the number of certain
  838. types of hw events: such as instructions executed, cachemisses
  839. suffered, or branches mis-predicted - without slowing down the
  840. kernel or applications. These registers can also trigger interrupts
  841. when a threshold number of events have passed - and can thus be
  842. used to profile the code that runs on that CPU.
  843. The Linux Performance Event subsystem provides an abstraction of
  844. these software and hardware event capabilities, available via a
  845. system call and used by the "perf" utility in tools/perf/. It
  846. provides per task and per CPU counters, and it provides event
  847. capabilities on top of those.
  848. Say Y if unsure.
  849. config PERF_COUNTERS
  850. bool "Kernel performance counters (old config option)"
  851. depends on HAVE_PERF_EVENTS
  852. help
  853. This config has been obsoleted by the PERF_EVENTS
  854. config option - please see that one for details.
  855. It has no effect on the kernel whether you enable
  856. it or not, it is a compatibility placeholder.
  857. Say N if unsure.
  858. config DEBUG_PERF_USE_VMALLOC
  859. default n
  860. bool "Debug: use vmalloc to back perf mmap() buffers"
  861. depends on PERF_EVENTS && DEBUG_KERNEL
  862. select PERF_USE_VMALLOC
  863. help
  864. Use vmalloc memory to back perf mmap() buffers.
  865. Mostly useful for debugging the vmalloc code on platforms
  866. that don't require it.
  867. Say N if unsure.
  868. endmenu
  869. config VM_EVENT_COUNTERS
  870. default y
  871. bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
  872. help
  873. VM event counters are needed for event counts to be shown.
  874. This option allows the disabling of the VM event counters
  875. on EMBEDDED systems. /proc/vmstat will only show page counts
  876. if VM event counters are disabled.
  877. config PCI_QUIRKS
  878. default y
  879. bool "Enable PCI quirk workarounds" if EMBEDDED
  880. depends on PCI
  881. help
  882. This enables workarounds for various PCI chipset
  883. bugs/quirks. Disable this only if your target machine is
  884. unaffected by PCI quirks.
  885. config SLUB_DEBUG
  886. default y
  887. bool "Enable SLUB debugging support" if EMBEDDED
  888. depends on SLUB && SYSFS
  889. help
  890. SLUB has extensive debug support features. Disabling these can
  891. result in significant savings in code size. This also disables
  892. SLUB sysfs support. /sys/slab will not exist and there will be
  893. no support for cache validation etc.
  894. config COMPAT_BRK
  895. bool "Disable heap randomization"
  896. default y
  897. help
  898. Randomizing heap placement makes heap exploits harder, but it
  899. also breaks ancient binaries (including anything libc5 based).
  900. This option changes the bootup default to heap randomization
  901. disabled, and can be overridden at runtime by setting
  902. /proc/sys/kernel/randomize_va_space to 2.
  903. On non-ancient distros (post-2000 ones) N is usually a safe choice.
  904. choice
  905. prompt "Choose SLAB allocator"
  906. default SLUB
  907. help
  908. This option allows to select a slab allocator.
  909. config SLAB
  910. bool "SLAB"
  911. help
  912. The regular slab allocator that is established and known to work
  913. well in all environments. It organizes cache hot objects in
  914. per cpu and per node queues.
  915. config SLUB
  916. bool "SLUB (Unqueued Allocator)"
  917. help
  918. SLUB is a slab allocator that minimizes cache line usage
  919. instead of managing queues of cached objects (SLAB approach).
  920. Per cpu caching is realized using slabs of objects instead
  921. of queues of objects. SLUB can use memory efficiently
  922. and has enhanced diagnostics. SLUB is the default choice for
  923. a slab allocator.
  924. config SLOB
  925. depends on EMBEDDED
  926. bool "SLOB (Simple Allocator)"
  927. help
  928. SLOB replaces the stock allocator with a drastically simpler
  929. allocator. SLOB is generally more space efficient but
  930. does not perform as well on large systems.
  931. endchoice
  932. config MMAP_ALLOW_UNINITIALIZED
  933. bool "Allow mmapped anonymous memory to be uninitialized"
  934. depends on EMBEDDED && !MMU
  935. default n
  936. help
  937. Normally, and according to the Linux spec, anonymous memory obtained
  938. from mmap() has it's contents cleared before it is passed to
  939. userspace. Enabling this config option allows you to request that
  940. mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
  941. providing a huge performance boost. If this option is not enabled,
  942. then the flag will be ignored.
  943. This is taken advantage of by uClibc's malloc(), and also by
  944. ELF-FDPIC binfmt's brk and stack allocator.
  945. Because of the obvious security issues, this option should only be
  946. enabled on embedded devices where you control what is run in
  947. userspace. Since that isn't generally a problem on no-MMU systems,
  948. it is normally safe to say Y here.
  949. See Documentation/nommu-mmap.txt for more information.
  950. config PROFILING
  951. bool "Profiling support"
  952. help
  953. Say Y here to enable the extended profiling support mechanisms used
  954. by profilers such as OProfile.
  955. #
  956. # Place an empty function call at each tracepoint site. Can be
  957. # dynamically changed for a probe function.
  958. #
  959. config TRACEPOINTS
  960. bool
  961. source "arch/Kconfig"
  962. endmenu # General setup
  963. config HAVE_GENERIC_DMA_COHERENT
  964. bool
  965. default n
  966. config SLABINFO
  967. bool
  968. depends on PROC_FS
  969. depends on SLAB || SLUB_DEBUG
  970. default y
  971. config RT_MUTEXES
  972. boolean
  973. config BASE_SMALL
  974. int
  975. default 0 if BASE_FULL
  976. default 1 if !BASE_FULL
  977. menuconfig MODULES
  978. bool "Enable loadable module support"
  979. help
  980. Kernel modules are small pieces of compiled code which can
  981. be inserted in the running kernel, rather than being
  982. permanently built into the kernel. You use the "modprobe"
  983. tool to add (and sometimes remove) them. If you say Y here,
  984. many parts of the kernel can be built as modules (by
  985. answering M instead of Y where indicated): this is most
  986. useful for infrequently used options which are not required
  987. for booting. For more information, see the man pages for
  988. modprobe, lsmod, modinfo, insmod and rmmod.
  989. If you say Y here, you will need to run "make
  990. modules_install" to put the modules under /lib/modules/
  991. where modprobe can find them (you may need to be root to do
  992. this).
  993. If unsure, say Y.
  994. if MODULES
  995. config MODULE_FORCE_LOAD
  996. bool "Forced module loading"
  997. default n
  998. help
  999. Allow loading of modules without version information (ie. modprobe
  1000. --force). Forced module loading sets the 'F' (forced) taint flag and
  1001. is usually a really bad idea.
  1002. config MODULE_UNLOAD
  1003. bool "Module unloading"
  1004. help
  1005. Without this option you will not be able to unload any
  1006. modules (note that some modules may not be unloadable
  1007. anyway), which makes your kernel smaller, faster
  1008. and simpler. If unsure, say Y.
  1009. config MODULE_FORCE_UNLOAD
  1010. bool "Forced module unloading"
  1011. depends on MODULE_UNLOAD && EXPERIMENTAL
  1012. help
  1013. This option allows you to force a module to unload, even if the
  1014. kernel believes it is unsafe: the kernel will remove the module
  1015. without waiting for anyone to stop using it (using the -f option to
  1016. rmmod). This is mainly for kernel developers and desperate users.
  1017. If unsure, say N.
  1018. config MODVERSIONS
  1019. bool "Module versioning support"
  1020. help
  1021. Usually, you have to use modules compiled with your kernel.
  1022. Saying Y here makes it sometimes possible to use modules
  1023. compiled for different kernels, by adding enough information
  1024. to the modules to (hopefully) spot any changes which would
  1025. make them incompatible with the kernel you are running. If
  1026. unsure, say N.
  1027. config MODULE_SRCVERSION_ALL
  1028. bool "Source checksum for all modules"
  1029. help
  1030. Modules which contain a MODULE_VERSION get an extra "srcversion"
  1031. field inserted into their modinfo section, which contains a
  1032. sum of the source files which made it. This helps maintainers
  1033. see exactly which source was used to build a module (since
  1034. others sometimes change the module source without updating
  1035. the version). With this option, such a "srcversion" field
  1036. will be created for all modules. If unsure, say N.
  1037. endif # MODULES
  1038. config INIT_ALL_POSSIBLE
  1039. bool
  1040. help
  1041. Back when each arch used to define their own cpu_online_map and
  1042. cpu_possible_map, some of them chose to initialize cpu_possible_map
  1043. with all 1s, and others with all 0s. When they were centralised,
  1044. it was better to provide this option than to break all the archs
  1045. and have several arch maintainers pursuing me down dark alleys.
  1046. config STOP_MACHINE
  1047. bool
  1048. default y
  1049. depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
  1050. help
  1051. Need stop_machine() primitive.
  1052. source "block/Kconfig"
  1053. config PREEMPT_NOTIFIERS
  1054. bool
  1055. config PADATA
  1056. depends on SMP
  1057. bool
  1058. source "kernel/Kconfig.locks"