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. config HAVE_IRQ_WORK
  21. bool
  22. config IRQ_WORK
  23. bool
  24. depends on HAVE_IRQ_WORK
  25. menu "General setup"
  26. config EXPERIMENTAL
  27. bool "Prompt for development and/or incomplete code/drivers"
  28. ---help---
  29. Some of the various things that Linux supports (such as network
  30. drivers, file systems, network protocols, etc.) can be in a state
  31. of development where the functionality, stability, or the level of
  32. testing is not yet high enough for general use. This is usually
  33. known as the "alpha-test" phase among developers. If a feature is
  34. currently in alpha-test, then the developers usually discourage
  35. uninformed widespread use of this feature by the general public to
  36. avoid "Why doesn't this work?" type mail messages. However, active
  37. testing and use of these systems is welcomed. Just be aware that it
  38. may not meet the normal level of reliability or it may fail to work
  39. in some special cases. Detailed bug reports from people familiar
  40. with the kernel internals are usually welcomed by the developers
  41. (before submitting bug reports, please read the documents
  42. <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
  43. <file:Documentation/BUG-HUNTING>, and
  44. <file:Documentation/oops-tracing.txt> in the kernel source).
  45. This option will also make obsoleted drivers available. These are
  46. drivers that have been replaced by something else, and/or are
  47. scheduled to be removed in a future kernel release.
  48. Unless you intend to help test and develop a feature or driver that
  49. falls into this category, or you have a situation that requires
  50. using these features, you should probably say N here, which will
  51. cause the configurator to present you with fewer choices. If
  52. you say Y here, you will be offered the choice of using features or
  53. drivers that are currently considered to be in the alpha-test phase.
  54. config BROKEN
  55. bool
  56. config BROKEN_ON_SMP
  57. bool
  58. depends on BROKEN || !SMP
  59. default y
  60. config LOCK_KERNEL
  61. bool
  62. depends on (SMP || PREEMPT) && BKL
  63. default y
  64. config INIT_ENV_ARG_LIMIT
  65. int
  66. default 32 if !UML
  67. default 128 if UML
  68. help
  69. Maximum of each of the number of arguments and environment
  70. variables passed to init from the kernel command line.
  71. config CROSS_COMPILE
  72. string "Cross-compiler tool prefix"
  73. help
  74. Same as running 'make CROSS_COMPILE=prefix-' but stored for
  75. default make runs in this kernel build directory. You don't
  76. need to set this unless you want the configured kernel build
  77. directory to select the cross-compiler automatically.
  78. config LOCALVERSION
  79. string "Local version - append to kernel release"
  80. help
  81. Append an extra string to the end of your kernel version.
  82. This will show up when you type uname, for example.
  83. The string you set here will be appended after the contents of
  84. any files with a filename matching localversion* in your
  85. object and source tree, in that order. Your total string can
  86. be a maximum of 64 characters.
  87. config LOCALVERSION_AUTO
  88. bool "Automatically append version information to the version string"
  89. default y
  90. help
  91. This will try to automatically determine if the current tree is a
  92. release tree by looking for git tags that belong to the current
  93. top of tree revision.
  94. A string of the format -gxxxxxxxx will be added to the localversion
  95. if a git-based tree is found. The string generated by this will be
  96. appended after any matching localversion* files, and after the value
  97. set in CONFIG_LOCALVERSION.
  98. (The actual string used here is the first eight characters produced
  99. by running the command:
  100. $ git rev-parse --verify HEAD
  101. which is done within the script "scripts/setlocalversion".)
  102. config HAVE_KERNEL_GZIP
  103. bool
  104. config HAVE_KERNEL_BZIP2
  105. bool
  106. config HAVE_KERNEL_LZMA
  107. bool
  108. config HAVE_KERNEL_LZO
  109. bool
  110. choice
  111. prompt "Kernel compression mode"
  112. default KERNEL_GZIP
  113. depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_LZO
  114. help
  115. The linux kernel is a kind of self-extracting executable.
  116. Several compression algorithms are available, which differ
  117. in efficiency, compression and decompression speed.
  118. Compression speed is only relevant when building a kernel.
  119. Decompression speed is relevant at each boot.
  120. If you have any problems with bzip2 or lzma compressed
  121. kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
  122. version of this functionality (bzip2 only), for 2.4, was
  123. supplied by Christian Ludwig)
  124. High compression options are mostly useful for users, who
  125. are low on disk space (embedded systems), but for whom ram
  126. size matters less.
  127. If in doubt, select 'gzip'
  128. config KERNEL_GZIP
  129. bool "Gzip"
  130. depends on HAVE_KERNEL_GZIP
  131. help
  132. The old and tried gzip compression. It provides a good balance
  133. between compression ratio and decompression speed.
  134. config KERNEL_BZIP2
  135. bool "Bzip2"
  136. depends on HAVE_KERNEL_BZIP2
  137. help
  138. Its compression ratio and speed is intermediate.
  139. Decompression speed is slowest among the three. The kernel
  140. size is about 10% smaller with bzip2, in comparison to gzip.
  141. Bzip2 uses a large amount of memory. For modern kernels you
  142. will need at least 8MB RAM or more for booting.
  143. config KERNEL_LZMA
  144. bool "LZMA"
  145. depends on HAVE_KERNEL_LZMA
  146. help
  147. The most recent compression algorithm.
  148. Its ratio is best, decompression speed is between the other
  149. two. Compression is slowest. The kernel size is about 33%
  150. smaller with LZMA in comparison to gzip.
  151. config KERNEL_LZO
  152. bool "LZO"
  153. depends on HAVE_KERNEL_LZO
  154. help
  155. Its compression ratio is the poorest among the 4. The kernel
  156. size is about 10% bigger than gzip; however its speed
  157. (both compression and decompression) is the fastest.
  158. endchoice
  159. config SWAP
  160. bool "Support for paging of anonymous memory (swap)"
  161. depends on MMU && BLOCK
  162. default y
  163. help
  164. This option allows you to choose whether you want to have support
  165. for so called swap devices or swap files in your kernel that are
  166. used to provide more virtual memory than the actual RAM present
  167. in your computer. If unsure say Y.
  168. config SYSVIPC
  169. bool "System V IPC"
  170. ---help---
  171. Inter Process Communication is a suite of library functions and
  172. system calls which let processes (running programs) synchronize and
  173. exchange information. It is generally considered to be a good thing,
  174. and some programs won't run unless you say Y here. In particular, if
  175. you want to run the DOS emulator dosemu under Linux (read the
  176. DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
  177. you'll need to say Y here.
  178. You can find documentation about IPC with "info ipc" and also in
  179. section 6.4 of the Linux Programmer's Guide, available from
  180. <http://www.tldp.org/guides.html>.
  181. config SYSVIPC_SYSCTL
  182. bool
  183. depends on SYSVIPC
  184. depends on SYSCTL
  185. default y
  186. config POSIX_MQUEUE
  187. bool "POSIX Message Queues"
  188. depends on NET && EXPERIMENTAL
  189. ---help---
  190. POSIX variant of message queues is a part of IPC. In POSIX message
  191. queues every message has a priority which decides about succession
  192. of receiving it by a process. If you want to compile and run
  193. programs written e.g. for Solaris with use of its POSIX message
  194. queues (functions mq_*) say Y here.
  195. POSIX message queues are visible as a filesystem called 'mqueue'
  196. and can be mounted somewhere if you want to do filesystem
  197. operations on message queues.
  198. If unsure, say Y.
  199. config POSIX_MQUEUE_SYSCTL
  200. bool
  201. depends on POSIX_MQUEUE
  202. depends on SYSCTL
  203. default y
  204. config BSD_PROCESS_ACCT
  205. bool "BSD Process Accounting"
  206. help
  207. If you say Y here, a user level program will be able to instruct the
  208. kernel (via a special system call) to write process accounting
  209. information to a file: whenever a process exits, information about
  210. that process will be appended to the file by the kernel. The
  211. information includes things such as creation time, owning user,
  212. command name, memory usage, controlling terminal etc. (the complete
  213. list is in the struct acct in <file:include/linux/acct.h>). It is
  214. up to the user level program to do useful things with this
  215. information. This is generally a good idea, so say Y.
  216. config BSD_PROCESS_ACCT_V3
  217. bool "BSD Process Accounting version 3 file format"
  218. depends on BSD_PROCESS_ACCT
  219. default n
  220. help
  221. If you say Y here, the process accounting information is written
  222. in a new file format that also logs the process IDs of each
  223. process and it's parent. Note that this file format is incompatible
  224. with previous v0/v1/v2 file formats, so you will need updated tools
  225. for processing it. A preliminary version of these tools is available
  226. at <http://www.gnu.org/software/acct/>.
  227. config TASKSTATS
  228. bool "Export task/process statistics through netlink (EXPERIMENTAL)"
  229. depends on NET
  230. default n
  231. help
  232. Export selected statistics for tasks/processes through the
  233. generic netlink interface. Unlike BSD process accounting, the
  234. statistics are available during the lifetime of tasks/processes as
  235. responses to commands. Like BSD accounting, they are sent to user
  236. space on task exit.
  237. Say N if unsure.
  238. config TASK_DELAY_ACCT
  239. bool "Enable per-task delay accounting (EXPERIMENTAL)"
  240. depends on TASKSTATS
  241. help
  242. Collect information on time spent by a task waiting for system
  243. resources like cpu, synchronous block I/O completion and swapping
  244. in pages. Such statistics can help in setting a task's priorities
  245. relative to other tasks for cpu, io, rss limits etc.
  246. Say N if unsure.
  247. config TASK_XACCT
  248. bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
  249. depends on TASKSTATS
  250. help
  251. Collect extended task accounting data and send the data
  252. to userland for processing over the taskstats interface.
  253. Say N if unsure.
  254. config TASK_IO_ACCOUNTING
  255. bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
  256. depends on TASK_XACCT
  257. help
  258. Collect information on the number of bytes of storage I/O which this
  259. task has caused.
  260. Say N if unsure.
  261. config AUDIT
  262. bool "Auditing support"
  263. depends on NET
  264. help
  265. Enable auditing infrastructure that can be used with another
  266. kernel subsystem, such as SELinux (which requires this for
  267. logging of avc messages output). Does not do system-call
  268. auditing without CONFIG_AUDITSYSCALL.
  269. config AUDITSYSCALL
  270. bool "Enable system-call auditing support"
  271. depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
  272. default y if SECURITY_SELINUX
  273. help
  274. Enable low-overhead system-call auditing infrastructure that
  275. can be used independently or with another kernel subsystem,
  276. such as SELinux.
  277. config AUDIT_WATCH
  278. def_bool y
  279. depends on AUDITSYSCALL
  280. select FSNOTIFY
  281. config AUDIT_TREE
  282. def_bool y
  283. depends on AUDITSYSCALL
  284. select FSNOTIFY
  285. source "kernel/irq/Kconfig"
  286. menu "RCU Subsystem"
  287. choice
  288. prompt "RCU Implementation"
  289. default TREE_RCU
  290. config TREE_RCU
  291. bool "Tree-based hierarchical RCU"
  292. depends on !PREEMPT && SMP
  293. help
  294. This option selects the RCU implementation that is
  295. designed for very large SMP system with hundreds or
  296. thousands of CPUs. It also scales down nicely to
  297. smaller systems.
  298. config TREE_PREEMPT_RCU
  299. bool "Preemptible tree-based hierarchical RCU"
  300. depends on PREEMPT
  301. help
  302. This option selects the RCU implementation that is
  303. designed for very large SMP systems with hundreds or
  304. thousands of CPUs, but for which real-time response
  305. is also required. It also scales down nicely to
  306. smaller systems.
  307. config TINY_RCU
  308. bool "UP-only small-memory-footprint RCU"
  309. depends on !SMP
  310. help
  311. This option selects the RCU implementation that is
  312. designed for UP systems from which real-time response
  313. is not required. This option greatly reduces the
  314. memory footprint of RCU.
  315. config TINY_PREEMPT_RCU
  316. bool "Preemptible UP-only small-memory-footprint RCU"
  317. depends on !SMP && PREEMPT
  318. help
  319. This option selects the RCU implementation that is designed
  320. for real-time UP systems. This option greatly reduces the
  321. memory footprint of RCU.
  322. endchoice
  323. config PREEMPT_RCU
  324. def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
  325. help
  326. This option enables preemptible-RCU code that is common between
  327. the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
  328. config RCU_TRACE
  329. bool "Enable tracing for RCU"
  330. depends on TREE_RCU || TREE_PREEMPT_RCU
  331. help
  332. This option provides tracing in RCU which presents stats
  333. in debugfs for debugging RCU implementation.
  334. Say Y here if you want to enable RCU tracing
  335. Say N if you are unsure.
  336. config RCU_FANOUT
  337. int "Tree-based hierarchical RCU fanout value"
  338. range 2 64 if 64BIT
  339. range 2 32 if !64BIT
  340. depends on TREE_RCU || TREE_PREEMPT_RCU
  341. default 64 if 64BIT
  342. default 32 if !64BIT
  343. help
  344. This option controls the fanout of hierarchical implementations
  345. of RCU, allowing RCU to work efficiently on machines with
  346. large numbers of CPUs. This value must be at least the fourth
  347. root of NR_CPUS, which allows NR_CPUS to be insanely large.
  348. The default value of RCU_FANOUT should be used for production
  349. systems, but if you are stress-testing the RCU implementation
  350. itself, small RCU_FANOUT values allow you to test large-system
  351. code paths on small(er) systems.
  352. Select a specific number if testing RCU itself.
  353. Take the default if unsure.
  354. config RCU_FANOUT_EXACT
  355. bool "Disable tree-based hierarchical RCU auto-balancing"
  356. depends on TREE_RCU || TREE_PREEMPT_RCU
  357. default n
  358. help
  359. This option forces use of the exact RCU_FANOUT value specified,
  360. regardless of imbalances in the hierarchy. This is useful for
  361. testing RCU itself, and might one day be useful on systems with
  362. strong NUMA behavior.
  363. Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
  364. Say N if unsure.
  365. config RCU_FAST_NO_HZ
  366. bool "Accelerate last non-dyntick-idle CPU's grace periods"
  367. depends on TREE_RCU && NO_HZ && SMP
  368. default n
  369. help
  370. This option causes RCU to attempt to accelerate grace periods
  371. in order to allow the final CPU to enter dynticks-idle state
  372. more quickly. On the other hand, this option increases the
  373. overhead of the dynticks-idle checking, particularly on systems
  374. with large numbers of CPUs.
  375. Say Y if energy efficiency is critically important, particularly
  376. if you have relatively few CPUs.
  377. Say N if you are unsure.
  378. config TREE_RCU_TRACE
  379. def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
  380. select DEBUG_FS
  381. help
  382. This option provides tracing for the TREE_RCU and
  383. TREE_PREEMPT_RCU implementations, permitting Makefile to
  384. trivially select kernel/rcutree_trace.c.
  385. endmenu # "RCU Subsystem"
  386. config IKCONFIG
  387. tristate "Kernel .config support"
  388. ---help---
  389. This option enables the complete Linux kernel ".config" file
  390. contents to be saved in the kernel. It provides documentation
  391. of which kernel options are used in a running kernel or in an
  392. on-disk kernel. This information can be extracted from the kernel
  393. image file with the script scripts/extract-ikconfig and used as
  394. input to rebuild the current kernel or to build another kernel.
  395. It can also be extracted from a running kernel by reading
  396. /proc/config.gz if enabled (below).
  397. config IKCONFIG_PROC
  398. bool "Enable access to .config through /proc/config.gz"
  399. depends on IKCONFIG && PROC_FS
  400. ---help---
  401. This option enables access to the kernel configuration file
  402. through /proc/config.gz.
  403. config LOG_BUF_SHIFT
  404. int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
  405. range 12 21
  406. default 17
  407. help
  408. Select kernel log buffer size as a power of 2.
  409. Examples:
  410. 17 => 128 KB
  411. 16 => 64 KB
  412. 15 => 32 KB
  413. 14 => 16 KB
  414. 13 => 8 KB
  415. 12 => 4 KB
  416. #
  417. # Architectures with an unreliable sched_clock() should select this:
  418. #
  419. config HAVE_UNSTABLE_SCHED_CLOCK
  420. bool
  421. menuconfig CGROUPS
  422. boolean "Control Group support"
  423. depends on EVENTFD
  424. help
  425. This option adds support for grouping sets of processes together, for
  426. use with process control subsystems such as Cpusets, CFS, memory
  427. controls or device isolation.
  428. See
  429. - Documentation/scheduler/sched-design-CFS.txt (CFS)
  430. - Documentation/cgroups/ (features for grouping, isolation
  431. and resource control)
  432. Say N if unsure.
  433. if CGROUPS
  434. config CGROUP_DEBUG
  435. bool "Example debug cgroup subsystem"
  436. depends on CGROUPS
  437. default n
  438. help
  439. This option enables a simple cgroup subsystem that
  440. exports useful debugging information about the cgroups
  441. framework.
  442. Say N if unsure.
  443. config CGROUP_NS
  444. bool "Namespace cgroup subsystem"
  445. depends on CGROUPS
  446. help
  447. Provides a simple namespace cgroup subsystem to
  448. provide hierarchical naming of sets of namespaces,
  449. for instance virtual servers and checkpoint/restart
  450. jobs.
  451. config CGROUP_FREEZER
  452. bool "Freezer cgroup subsystem"
  453. depends on CGROUPS
  454. help
  455. Provides a way to freeze and unfreeze all tasks in a
  456. cgroup.
  457. config CGROUP_DEVICE
  458. bool "Device controller for cgroups"
  459. depends on CGROUPS && EXPERIMENTAL
  460. help
  461. Provides a cgroup implementing whitelists for devices which
  462. a process in the cgroup can mknod or open.
  463. config CPUSETS
  464. bool "Cpuset support"
  465. depends on CGROUPS
  466. help
  467. This option will let you create and manage CPUSETs which
  468. allow dynamically partitioning a system into sets of CPUs and
  469. Memory Nodes and assigning tasks to run only within those sets.
  470. This is primarily useful on large SMP or NUMA systems.
  471. Say N if unsure.
  472. config PROC_PID_CPUSET
  473. bool "Include legacy /proc/<pid>/cpuset file"
  474. depends on CPUSETS
  475. default y
  476. config CGROUP_CPUACCT
  477. bool "Simple CPU accounting cgroup subsystem"
  478. depends on CGROUPS
  479. help
  480. Provides a simple Resource Controller for monitoring the
  481. total CPU consumed by the tasks in a cgroup.
  482. config RESOURCE_COUNTERS
  483. bool "Resource counters"
  484. help
  485. This option enables controller independent resource accounting
  486. infrastructure that works with cgroups.
  487. depends on CGROUPS
  488. config CGROUP_MEM_RES_CTLR
  489. bool "Memory Resource Controller for Control Groups"
  490. depends on CGROUPS && RESOURCE_COUNTERS
  491. select MM_OWNER
  492. help
  493. Provides a memory resource controller that manages both anonymous
  494. memory and page cache. (See Documentation/cgroups/memory.txt)
  495. Note that setting this option increases fixed memory overhead
  496. associated with each page of memory in the system. By this,
  497. 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
  498. usage tracking struct at boot. Total amount of this is printed out
  499. at boot.
  500. Only enable when you're ok with these trade offs and really
  501. sure you need the memory resource controller. Even when you enable
  502. this, you can set "cgroup_disable=memory" at your boot option to
  503. disable memory resource controller and you can avoid overheads.
  504. (and lose benefits of memory resource controller)
  505. This config option also selects MM_OWNER config option, which
  506. could in turn add some fork/exit overhead.
  507. config CGROUP_MEM_RES_CTLR_SWAP
  508. bool "Memory Resource Controller Swap Extension"
  509. depends on CGROUP_MEM_RES_CTLR && SWAP
  510. help
  511. Add swap management feature to memory resource controller. When you
  512. enable this, you can limit mem+swap usage per cgroup. In other words,
  513. when you disable this, memory resource controller has no cares to
  514. usage of swap...a process can exhaust all of the swap. This extension
  515. is useful when you want to avoid exhaustion swap but this itself
  516. adds more overheads and consumes memory for remembering information.
  517. Especially if you use 32bit system or small memory system, please
  518. be careful about enabling this. When memory resource controller
  519. is disabled by boot option, this will be automatically disabled and
  520. there will be no overhead from this. Even when you set this config=y,
  521. if boot option "noswapaccount" is set, swap will not be accounted.
  522. Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
  523. size is 4096bytes, 512k per 1Gbytes of swap.
  524. menuconfig CGROUP_SCHED
  525. bool "Group CPU scheduler"
  526. depends on EXPERIMENTAL && CGROUPS
  527. default n
  528. help
  529. This feature lets CPU scheduler recognize task groups and control CPU
  530. bandwidth allocation to such task groups. It uses cgroups to group
  531. tasks.
  532. if CGROUP_SCHED
  533. config FAIR_GROUP_SCHED
  534. bool "Group scheduling for SCHED_OTHER"
  535. depends on CGROUP_SCHED
  536. default CGROUP_SCHED
  537. config RT_GROUP_SCHED
  538. bool "Group scheduling for SCHED_RR/FIFO"
  539. depends on EXPERIMENTAL
  540. depends on CGROUP_SCHED
  541. default n
  542. help
  543. This feature lets you explicitly allocate real CPU bandwidth
  544. to task groups. If enabled, it will also make it impossible to
  545. schedule realtime tasks for non-root users until you allocate
  546. realtime bandwidth for them.
  547. See Documentation/scheduler/sched-rt-group.txt for more information.
  548. endif #CGROUP_SCHED
  549. config BLK_CGROUP
  550. tristate "Block IO controller"
  551. depends on CGROUPS && BLOCK
  552. default n
  553. ---help---
  554. Generic block IO controller cgroup interface. This is the common
  555. cgroup interface which should be used by various IO controlling
  556. policies.
  557. Currently, CFQ IO scheduler uses it to recognize task groups and
  558. control disk bandwidth allocation (proportional time slice allocation)
  559. to such task groups. It is also used by bio throttling logic in
  560. block layer to implement upper limit in IO rates on a device.
  561. This option only enables generic Block IO controller infrastructure.
  562. One needs to also enable actual IO controlling logic/policy. For
  563. enabling proportional weight division of disk bandwidth in CFQ seti
  564. CONFIG_CFQ_GROUP_IOSCHED=y and for enabling throttling policy set
  565. CONFIG_BLK_THROTTLE=y.
  566. See Documentation/cgroups/blkio-controller.txt for more information.
  567. config DEBUG_BLK_CGROUP
  568. bool "Enable Block IO controller debugging"
  569. depends on BLK_CGROUP
  570. default n
  571. ---help---
  572. Enable some debugging help. Currently it exports additional stat
  573. files in a cgroup which can be useful for debugging.
  574. endif # CGROUPS
  575. config MM_OWNER
  576. bool
  577. config SYSFS_DEPRECATED
  578. bool "enable deprecated sysfs features to support old userspace tools"
  579. depends on SYSFS
  580. default n
  581. help
  582. This option adds code that switches the layout of the "block" class
  583. devices, to not show up in /sys/class/block/, but only in
  584. /sys/block/.
  585. This switch is only active when the sysfs.deprecated=1 boot option is
  586. passed or the SYSFS_DEPRECATED_V2 option is set.
  587. This option allows new kernels to run on old distributions and tools,
  588. which might get confused by /sys/class/block/. Since 2007/2008 all
  589. major distributions and tools handle this just fine.
  590. Recent distributions and userspace tools after 2009/2010 depend on
  591. the existence of /sys/class/block/, and will not work with this
  592. option enabled.
  593. Only if you are using a new kernel on an old distribution, you might
  594. need to say Y here.
  595. config SYSFS_DEPRECATED_V2
  596. bool "enabled deprecated sysfs features by default"
  597. default n
  598. depends on SYSFS
  599. depends on SYSFS_DEPRECATED
  600. help
  601. Enable deprecated sysfs by default.
  602. See the CONFIG_SYSFS_DEPRECATED option for more details about this
  603. option.
  604. Only if you are using a new kernel on an old distribution, you might
  605. need to say Y here. Even then, odds are you would not need it
  606. enabled, you can always pass the boot option if absolutely necessary.
  607. config RELAY
  608. bool "Kernel->user space relay support (formerly relayfs)"
  609. help
  610. This option enables support for relay interface support in
  611. certain file systems (such as debugfs).
  612. It is designed to provide an efficient mechanism for tools and
  613. facilities to relay large amounts of data from kernel space to
  614. user space.
  615. If unsure, say N.
  616. menuconfig NAMESPACES
  617. bool "Namespaces support" if EMBEDDED
  618. default !EMBEDDED
  619. help
  620. Provides the way to make tasks work with different objects using
  621. the same id. For example same IPC id may refer to different objects
  622. or same user id or pid may refer to different tasks when used in
  623. different namespaces.
  624. if NAMESPACES
  625. config UTS_NS
  626. bool "UTS namespace"
  627. default y
  628. help
  629. In this namespace tasks see different info provided with the
  630. uname() system call
  631. config IPC_NS
  632. bool "IPC namespace"
  633. depends on (SYSVIPC || POSIX_MQUEUE)
  634. default y
  635. help
  636. In this namespace tasks work with IPC ids which correspond to
  637. different IPC objects in different namespaces.
  638. config USER_NS
  639. bool "User namespace (EXPERIMENTAL)"
  640. depends on EXPERIMENTAL
  641. default y
  642. help
  643. This allows containers, i.e. vservers, to use user namespaces
  644. to provide different user info for different servers.
  645. If unsure, say N.
  646. config PID_NS
  647. bool "PID Namespaces"
  648. default y
  649. help
  650. Support process id namespaces. This allows having multiple
  651. processes with the same pid as long as they are in different
  652. pid namespaces. This is a building block of containers.
  653. config NET_NS
  654. bool "Network namespace"
  655. depends on NET
  656. default y
  657. help
  658. Allow user space to create what appear to be multiple instances
  659. of the network stack.
  660. endif # NAMESPACES
  661. config BLK_DEV_INITRD
  662. bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
  663. depends on BROKEN || !FRV
  664. help
  665. The initial RAM filesystem is a ramfs which is loaded by the
  666. boot loader (loadlin or lilo) and that is mounted as root
  667. before the normal boot procedure. It is typically used to
  668. load modules needed to mount the "real" root file system,
  669. etc. See <file:Documentation/initrd.txt> for details.
  670. If RAM disk support (BLK_DEV_RAM) is also included, this
  671. also enables initial RAM disk (initrd) support and adds
  672. 15 Kbytes (more on some other architectures) to the kernel size.
  673. If unsure say Y.
  674. if BLK_DEV_INITRD
  675. source "usr/Kconfig"
  676. endif
  677. config CC_OPTIMIZE_FOR_SIZE
  678. bool "Optimize for size"
  679. default y
  680. help
  681. Enabling this option will pass "-Os" instead of "-O2" to gcc
  682. resulting in a smaller kernel.
  683. If unsure, say Y.
  684. config SYSCTL
  685. bool
  686. config ANON_INODES
  687. bool
  688. menuconfig EMBEDDED
  689. bool "Configure standard kernel features (for small systems)"
  690. help
  691. This option allows certain base kernel options and settings
  692. to be disabled or tweaked. This is for specialized
  693. environments which can tolerate a "non-standard" kernel.
  694. Only use this if you really know what you are doing.
  695. config UID16
  696. bool "Enable 16-bit UID system calls" if EMBEDDED
  697. depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
  698. default y
  699. help
  700. This enables the legacy 16-bit UID syscall wrappers.
  701. config SYSCTL_SYSCALL
  702. bool "Sysctl syscall support" if EMBEDDED
  703. depends on PROC_SYSCTL
  704. default y
  705. select SYSCTL
  706. ---help---
  707. sys_sysctl uses binary paths that have been found challenging
  708. to properly maintain and use. The interface in /proc/sys
  709. using paths with ascii names is now the primary path to this
  710. information.
  711. Almost nothing using the binary sysctl interface so if you are
  712. trying to save some space it is probably safe to disable this,
  713. making your kernel marginally smaller.
  714. If unsure say Y here.
  715. config KALLSYMS
  716. bool "Load all symbols for debugging/ksymoops" if EMBEDDED
  717. default y
  718. help
  719. Say Y here to let the kernel print out symbolic crash information and
  720. symbolic stack backtraces. This increases the size of the kernel
  721. somewhat, as all symbols have to be loaded into the kernel image.
  722. config KALLSYMS_ALL
  723. bool "Include all symbols in kallsyms"
  724. depends on DEBUG_KERNEL && KALLSYMS
  725. help
  726. Normally kallsyms only contains the symbols of functions, for nicer
  727. OOPS messages. Some debuggers can use kallsyms for other
  728. symbols too: say Y here to include all symbols, if you need them
  729. and you don't care about adding 300k to the size of your kernel.
  730. Say N.
  731. config KALLSYMS_EXTRA_PASS
  732. bool "Do an extra kallsyms pass"
  733. depends on KALLSYMS
  734. help
  735. If kallsyms is not working correctly, the build will fail with
  736. inconsistent kallsyms data. If that occurs, log a bug report and
  737. turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
  738. Always say N here unless you find a bug in kallsyms, which must be
  739. reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
  740. you wait for kallsyms to be fixed.
  741. config HOTPLUG
  742. bool "Support for hot-pluggable devices" if EMBEDDED
  743. default y
  744. help
  745. This option is provided for the case where no hotplug or uevent
  746. capabilities is wanted by the kernel. You should only consider
  747. disabling this option for embedded systems that do not use modules, a
  748. dynamic /dev tree, or dynamic device discovery. Just say Y.
  749. config PRINTK
  750. default y
  751. bool "Enable support for printk" if EMBEDDED
  752. help
  753. This option enables normal printk support. Removing it
  754. eliminates most of the message strings from the kernel image
  755. and makes the kernel more or less silent. As this makes it
  756. very difficult to diagnose system problems, saying N here is
  757. strongly discouraged.
  758. config BUG
  759. bool "BUG() support" if EMBEDDED
  760. default y
  761. help
  762. Disabling this option eliminates support for BUG and WARN, reducing
  763. the size of your kernel image and potentially quietly ignoring
  764. numerous fatal conditions. You should only consider disabling this
  765. option for embedded systems with no facilities for reporting errors.
  766. Just say Y.
  767. config ELF_CORE
  768. default y
  769. bool "Enable ELF core dumps" if EMBEDDED
  770. help
  771. Enable support for generating core dumps. Disabling saves about 4k.
  772. config PCSPKR_PLATFORM
  773. bool "Enable PC-Speaker support" if EMBEDDED
  774. depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
  775. default y
  776. help
  777. This option allows to disable the internal PC-Speaker
  778. support, saving some memory.
  779. config BASE_FULL
  780. default y
  781. bool "Enable full-sized data structures for core" if EMBEDDED
  782. help
  783. Disabling this option reduces the size of miscellaneous core
  784. kernel data structures. This saves memory on small machines,
  785. but may reduce performance.
  786. config FUTEX
  787. bool "Enable futex support" if EMBEDDED
  788. default y
  789. select RT_MUTEXES
  790. help
  791. Disabling this option will cause the kernel to be built without
  792. support for "fast userspace mutexes". The resulting kernel may not
  793. run glibc-based applications correctly.
  794. config EPOLL
  795. bool "Enable eventpoll support" if EMBEDDED
  796. default y
  797. select ANON_INODES
  798. help
  799. Disabling this option will cause the kernel to be built without
  800. support for epoll family of system calls.
  801. config SIGNALFD
  802. bool "Enable signalfd() system call" if EMBEDDED
  803. select ANON_INODES
  804. default y
  805. help
  806. Enable the signalfd() system call that allows to receive signals
  807. on a file descriptor.
  808. If unsure, say Y.
  809. config TIMERFD
  810. bool "Enable timerfd() system call" if EMBEDDED
  811. select ANON_INODES
  812. default y
  813. help
  814. Enable the timerfd() system call that allows to receive timer
  815. events on a file descriptor.
  816. If unsure, say Y.
  817. config EVENTFD
  818. bool "Enable eventfd() system call" if EMBEDDED
  819. select ANON_INODES
  820. default y
  821. help
  822. Enable the eventfd() system call that allows to receive both
  823. kernel notification (ie. KAIO) or userspace notifications.
  824. If unsure, say Y.
  825. config SHMEM
  826. bool "Use full shmem filesystem" if EMBEDDED
  827. default y
  828. depends on MMU
  829. help
  830. The shmem is an internal filesystem used to manage shared memory.
  831. It is backed by swap and manages resource limits. It is also exported
  832. to userspace as tmpfs if TMPFS is enabled. Disabling this
  833. option replaces shmem and tmpfs with the much simpler ramfs code,
  834. which may be appropriate on small systems without swap.
  835. config AIO
  836. bool "Enable AIO support" if EMBEDDED
  837. default y
  838. help
  839. This option enables POSIX asynchronous I/O which may by used
  840. by some high performance threaded applications. Disabling
  841. this option saves about 7k.
  842. config HAVE_PERF_EVENTS
  843. bool
  844. help
  845. See tools/perf/design.txt for details.
  846. config PERF_USE_VMALLOC
  847. bool
  848. help
  849. See tools/perf/design.txt for details
  850. menu "Kernel Performance Events And Counters"
  851. config PERF_EVENTS
  852. bool "Kernel performance events and counters"
  853. default y if (PROFILING || PERF_COUNTERS)
  854. depends on HAVE_PERF_EVENTS
  855. select ANON_INODES
  856. select IRQ_WORK
  857. help
  858. Enable kernel support for various performance events provided
  859. by software and hardware.
  860. Software events are supported either built-in or via the
  861. use of generic tracepoints.
  862. Most modern CPUs support performance events via performance
  863. counter registers. These registers count the number of certain
  864. types of hw events: such as instructions executed, cachemisses
  865. suffered, or branches mis-predicted - without slowing down the
  866. kernel or applications. These registers can also trigger interrupts
  867. when a threshold number of events have passed - and can thus be
  868. used to profile the code that runs on that CPU.
  869. The Linux Performance Event subsystem provides an abstraction of
  870. these software and hardware event capabilities, available via a
  871. system call and used by the "perf" utility in tools/perf/. It
  872. provides per task and per CPU counters, and it provides event
  873. capabilities on top of those.
  874. Say Y if unsure.
  875. config PERF_COUNTERS
  876. bool "Kernel performance counters (old config option)"
  877. depends on HAVE_PERF_EVENTS
  878. help
  879. This config has been obsoleted by the PERF_EVENTS
  880. config option - please see that one for details.
  881. It has no effect on the kernel whether you enable
  882. it or not, it is a compatibility placeholder.
  883. Say N if unsure.
  884. config DEBUG_PERF_USE_VMALLOC
  885. default n
  886. bool "Debug: use vmalloc to back perf mmap() buffers"
  887. depends on PERF_EVENTS && DEBUG_KERNEL
  888. select PERF_USE_VMALLOC
  889. help
  890. Use vmalloc memory to back perf mmap() buffers.
  891. Mostly useful for debugging the vmalloc code on platforms
  892. that don't require it.
  893. Say N if unsure.
  894. endmenu
  895. config VM_EVENT_COUNTERS
  896. default y
  897. bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
  898. help
  899. VM event counters are needed for event counts to be shown.
  900. This option allows the disabling of the VM event counters
  901. on EMBEDDED systems. /proc/vmstat will only show page counts
  902. if VM event counters are disabled.
  903. config PCI_QUIRKS
  904. default y
  905. bool "Enable PCI quirk workarounds" if EMBEDDED
  906. depends on PCI
  907. help
  908. This enables workarounds for various PCI chipset
  909. bugs/quirks. Disable this only if your target machine is
  910. unaffected by PCI quirks.
  911. config SLUB_DEBUG
  912. default y
  913. bool "Enable SLUB debugging support" if EMBEDDED
  914. depends on SLUB && SYSFS
  915. help
  916. SLUB has extensive debug support features. Disabling these can
  917. result in significant savings in code size. This also disables
  918. SLUB sysfs support. /sys/slab will not exist and there will be
  919. no support for cache validation etc.
  920. config COMPAT_BRK
  921. bool "Disable heap randomization"
  922. default y
  923. help
  924. Randomizing heap placement makes heap exploits harder, but it
  925. also breaks ancient binaries (including anything libc5 based).
  926. This option changes the bootup default to heap randomization
  927. disabled, and can be overridden at runtime by setting
  928. /proc/sys/kernel/randomize_va_space to 2.
  929. On non-ancient distros (post-2000 ones) N is usually a safe choice.
  930. choice
  931. prompt "Choose SLAB allocator"
  932. default SLUB
  933. help
  934. This option allows to select a slab allocator.
  935. config SLAB
  936. bool "SLAB"
  937. help
  938. The regular slab allocator that is established and known to work
  939. well in all environments. It organizes cache hot objects in
  940. per cpu and per node queues.
  941. config SLUB
  942. bool "SLUB (Unqueued Allocator)"
  943. help
  944. SLUB is a slab allocator that minimizes cache line usage
  945. instead of managing queues of cached objects (SLAB approach).
  946. Per cpu caching is realized using slabs of objects instead
  947. of queues of objects. SLUB can use memory efficiently
  948. and has enhanced diagnostics. SLUB is the default choice for
  949. a slab allocator.
  950. config SLOB
  951. depends on EMBEDDED
  952. bool "SLOB (Simple Allocator)"
  953. help
  954. SLOB replaces the stock allocator with a drastically simpler
  955. allocator. SLOB is generally more space efficient but
  956. does not perform as well on large systems.
  957. endchoice
  958. config MMAP_ALLOW_UNINITIALIZED
  959. bool "Allow mmapped anonymous memory to be uninitialized"
  960. depends on EMBEDDED && !MMU
  961. default n
  962. help
  963. Normally, and according to the Linux spec, anonymous memory obtained
  964. from mmap() has it's contents cleared before it is passed to
  965. userspace. Enabling this config option allows you to request that
  966. mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
  967. providing a huge performance boost. If this option is not enabled,
  968. then the flag will be ignored.
  969. This is taken advantage of by uClibc's malloc(), and also by
  970. ELF-FDPIC binfmt's brk and stack allocator.
  971. Because of the obvious security issues, this option should only be
  972. enabled on embedded devices where you control what is run in
  973. userspace. Since that isn't generally a problem on no-MMU systems,
  974. it is normally safe to say Y here.
  975. See Documentation/nommu-mmap.txt for more information.
  976. config PROFILING
  977. bool "Profiling support"
  978. help
  979. Say Y here to enable the extended profiling support mechanisms used
  980. by profilers such as OProfile.
  981. #
  982. # Place an empty function call at each tracepoint site. Can be
  983. # dynamically changed for a probe function.
  984. #
  985. config TRACEPOINTS
  986. bool
  987. source "arch/Kconfig"
  988. endmenu # General setup
  989. config HAVE_GENERIC_DMA_COHERENT
  990. bool
  991. default n
  992. config SLABINFO
  993. bool
  994. depends on PROC_FS
  995. depends on SLAB || SLUB_DEBUG
  996. default y
  997. config RT_MUTEXES
  998. boolean
  999. config BASE_SMALL
  1000. int
  1001. default 0 if BASE_FULL
  1002. default 1 if !BASE_FULL
  1003. menuconfig MODULES
  1004. bool "Enable loadable module support"
  1005. help
  1006. Kernel modules are small pieces of compiled code which can
  1007. be inserted in the running kernel, rather than being
  1008. permanently built into the kernel. You use the "modprobe"
  1009. tool to add (and sometimes remove) them. If you say Y here,
  1010. many parts of the kernel can be built as modules (by
  1011. answering M instead of Y where indicated): this is most
  1012. useful for infrequently used options which are not required
  1013. for booting. For more information, see the man pages for
  1014. modprobe, lsmod, modinfo, insmod and rmmod.
  1015. If you say Y here, you will need to run "make
  1016. modules_install" to put the modules under /lib/modules/
  1017. where modprobe can find them (you may need to be root to do
  1018. this).
  1019. If unsure, say Y.
  1020. if MODULES
  1021. config MODULE_FORCE_LOAD
  1022. bool "Forced module loading"
  1023. default n
  1024. help
  1025. Allow loading of modules without version information (ie. modprobe
  1026. --force). Forced module loading sets the 'F' (forced) taint flag and
  1027. is usually a really bad idea.
  1028. config MODULE_UNLOAD
  1029. bool "Module unloading"
  1030. help
  1031. Without this option you will not be able to unload any
  1032. modules (note that some modules may not be unloadable
  1033. anyway), which makes your kernel smaller, faster
  1034. and simpler. If unsure, say Y.
  1035. config MODULE_FORCE_UNLOAD
  1036. bool "Forced module unloading"
  1037. depends on MODULE_UNLOAD && EXPERIMENTAL
  1038. help
  1039. This option allows you to force a module to unload, even if the
  1040. kernel believes it is unsafe: the kernel will remove the module
  1041. without waiting for anyone to stop using it (using the -f option to
  1042. rmmod). This is mainly for kernel developers and desperate users.
  1043. If unsure, say N.
  1044. config MODVERSIONS
  1045. bool "Module versioning support"
  1046. help
  1047. Usually, you have to use modules compiled with your kernel.
  1048. Saying Y here makes it sometimes possible to use modules
  1049. compiled for different kernels, by adding enough information
  1050. to the modules to (hopefully) spot any changes which would
  1051. make them incompatible with the kernel you are running. If
  1052. unsure, say N.
  1053. config MODULE_SRCVERSION_ALL
  1054. bool "Source checksum for all modules"
  1055. help
  1056. Modules which contain a MODULE_VERSION get an extra "srcversion"
  1057. field inserted into their modinfo section, which contains a
  1058. sum of the source files which made it. This helps maintainers
  1059. see exactly which source was used to build a module (since
  1060. others sometimes change the module source without updating
  1061. the version). With this option, such a "srcversion" field
  1062. will be created for all modules. If unsure, say N.
  1063. endif # MODULES
  1064. config INIT_ALL_POSSIBLE
  1065. bool
  1066. help
  1067. Back when each arch used to define their own cpu_online_map and
  1068. cpu_possible_map, some of them chose to initialize cpu_possible_map
  1069. with all 1s, and others with all 0s. When they were centralised,
  1070. it was better to provide this option than to break all the archs
  1071. and have several arch maintainers pursuing me down dark alleys.
  1072. config STOP_MACHINE
  1073. bool
  1074. default y
  1075. depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
  1076. help
  1077. Need stop_machine() primitive.
  1078. source "block/Kconfig"
  1079. config PREEMPT_NOTIFIERS
  1080. bool
  1081. config PADATA
  1082. depends on SMP
  1083. bool
  1084. source "kernel/Kconfig.locks"