Kconfig 37 KB

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  1. config ARCH
  2. string
  3. option env="ARCH"
  4. config KERNELVERSION
  5. string
  6. option env="KERNELVERSION"
  7. config DEFCONFIG_LIST
  8. string
  9. depends on !UML
  10. option defconfig_list
  11. default "/lib/modules/$UNAME_RELEASE/.config"
  12. default "/etc/kernel-config"
  13. default "/boot/config-$UNAME_RELEASE"
  14. default "$ARCH_DEFCONFIG"
  15. default "arch/$ARCH/defconfig"
  16. config CONSTRUCTORS
  17. bool
  18. depends on !UML
  19. default y
  20. menu "General setup"
  21. config EXPERIMENTAL
  22. bool "Prompt for development and/or incomplete code/drivers"
  23. ---help---
  24. Some of the various things that Linux supports (such as network
  25. drivers, file systems, network protocols, etc.) can be in a state
  26. of development where the functionality, stability, or the level of
  27. testing is not yet high enough for general use. This is usually
  28. known as the "alpha-test" phase among developers. If a feature is
  29. currently in alpha-test, then the developers usually discourage
  30. uninformed widespread use of this feature by the general public to
  31. avoid "Why doesn't this work?" type mail messages. However, active
  32. testing and use of these systems is welcomed. Just be aware that it
  33. may not meet the normal level of reliability or it may fail to work
  34. in some special cases. Detailed bug reports from people familiar
  35. with the kernel internals are usually welcomed by the developers
  36. (before submitting bug reports, please read the documents
  37. <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
  38. <file:Documentation/BUG-HUNTING>, and
  39. <file:Documentation/oops-tracing.txt> in the kernel source).
  40. This option will also make obsoleted drivers available. These are
  41. drivers that have been replaced by something else, and/or are
  42. scheduled to be removed in a future kernel release.
  43. Unless you intend to help test and develop a feature or driver that
  44. falls into this category, or you have a situation that requires
  45. using these features, you should probably say N here, which will
  46. cause the configurator to present you with fewer choices. If
  47. you say Y here, you will be offered the choice of using features or
  48. drivers that are currently considered to be in the alpha-test phase.
  49. config BROKEN
  50. bool
  51. config BROKEN_ON_SMP
  52. bool
  53. depends on BROKEN || !SMP
  54. default y
  55. config LOCK_KERNEL
  56. bool
  57. depends on SMP || PREEMPT
  58. default y
  59. config INIT_ENV_ARG_LIMIT
  60. int
  61. default 32 if !UML
  62. default 128 if UML
  63. help
  64. Maximum of each of the number of arguments and environment
  65. variables passed to init from the kernel command line.
  66. config LOCALVERSION
  67. string "Local version - append to kernel release"
  68. help
  69. Append an extra string to the end of your kernel version.
  70. This will show up when you type uname, for example.
  71. The string you set here will be appended after the contents of
  72. any files with a filename matching localversion* in your
  73. object and source tree, in that order. Your total string can
  74. be a maximum of 64 characters.
  75. config LOCALVERSION_AUTO
  76. bool "Automatically append version information to the version string"
  77. default y
  78. help
  79. This will try to automatically determine if the current tree is a
  80. release tree by looking for git tags that belong to the current
  81. top of tree revision.
  82. A string of the format -gxxxxxxxx will be added to the localversion
  83. if a git-based tree is found. The string generated by this will be
  84. appended after any matching localversion* files, and after the value
  85. set in CONFIG_LOCALVERSION.
  86. (The actual string used here is the first eight characters produced
  87. by running the command:
  88. $ git rev-parse --verify HEAD
  89. which is done within the script "scripts/setlocalversion".)
  90. config HAVE_KERNEL_GZIP
  91. bool
  92. config HAVE_KERNEL_BZIP2
  93. bool
  94. config HAVE_KERNEL_LZMA
  95. bool
  96. choice
  97. prompt "Kernel compression mode"
  98. default KERNEL_GZIP
  99. depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA
  100. help
  101. The linux kernel is a kind of self-extracting executable.
  102. Several compression algorithms are available, which differ
  103. in efficiency, compression and decompression speed.
  104. Compression speed is only relevant when building a kernel.
  105. Decompression speed is relevant at each boot.
  106. If you have any problems with bzip2 or lzma compressed
  107. kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
  108. version of this functionality (bzip2 only), for 2.4, was
  109. supplied by Christian Ludwig)
  110. High compression options are mostly useful for users, who
  111. are low on disk space (embedded systems), but for whom ram
  112. size matters less.
  113. If in doubt, select 'gzip'
  114. config KERNEL_GZIP
  115. bool "Gzip"
  116. depends on HAVE_KERNEL_GZIP
  117. help
  118. The old and tried gzip compression. Its compression ratio is
  119. the poorest among the 3 choices; however its speed (both
  120. compression and decompression) is the fastest.
  121. config KERNEL_BZIP2
  122. bool "Bzip2"
  123. depends on HAVE_KERNEL_BZIP2
  124. help
  125. Its compression ratio and speed is intermediate.
  126. Decompression speed is slowest among the three. The kernel
  127. size is about 10% smaller with bzip2, in comparison to gzip.
  128. Bzip2 uses a large amount of memory. For modern kernels you
  129. will need at least 8MB RAM or more for booting.
  130. config KERNEL_LZMA
  131. bool "LZMA"
  132. depends on HAVE_KERNEL_LZMA
  133. help
  134. The most recent compression algorithm.
  135. Its ratio is best, decompression speed is between the other
  136. two. Compression is slowest. The kernel size is about 33%
  137. smaller with LZMA in comparison to gzip.
  138. endchoice
  139. config SWAP
  140. bool "Support for paging of anonymous memory (swap)"
  141. depends on MMU && BLOCK
  142. default y
  143. help
  144. This option allows you to choose whether you want to have support
  145. for so called swap devices or swap files in your kernel that are
  146. used to provide more virtual memory than the actual RAM present
  147. in your computer. If unsure say Y.
  148. config SYSVIPC
  149. bool "System V IPC"
  150. ---help---
  151. Inter Process Communication is a suite of library functions and
  152. system calls which let processes (running programs) synchronize and
  153. exchange information. It is generally considered to be a good thing,
  154. and some programs won't run unless you say Y here. In particular, if
  155. you want to run the DOS emulator dosemu under Linux (read the
  156. DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
  157. you'll need to say Y here.
  158. You can find documentation about IPC with "info ipc" and also in
  159. section 6.4 of the Linux Programmer's Guide, available from
  160. <http://www.tldp.org/guides.html>.
  161. config SYSVIPC_SYSCTL
  162. bool
  163. depends on SYSVIPC
  164. depends on SYSCTL
  165. default y
  166. config POSIX_MQUEUE
  167. bool "POSIX Message Queues"
  168. depends on NET && EXPERIMENTAL
  169. ---help---
  170. POSIX variant of message queues is a part of IPC. In POSIX message
  171. queues every message has a priority which decides about succession
  172. of receiving it by a process. If you want to compile and run
  173. programs written e.g. for Solaris with use of its POSIX message
  174. queues (functions mq_*) say Y here.
  175. POSIX message queues are visible as a filesystem called 'mqueue'
  176. and can be mounted somewhere if you want to do filesystem
  177. operations on message queues.
  178. If unsure, say Y.
  179. config POSIX_MQUEUE_SYSCTL
  180. bool
  181. depends on POSIX_MQUEUE
  182. depends on SYSCTL
  183. default y
  184. config BSD_PROCESS_ACCT
  185. bool "BSD Process Accounting"
  186. help
  187. If you say Y here, a user level program will be able to instruct the
  188. kernel (via a special system call) to write process accounting
  189. information to a file: whenever a process exits, information about
  190. that process will be appended to the file by the kernel. The
  191. information includes things such as creation time, owning user,
  192. command name, memory usage, controlling terminal etc. (the complete
  193. list is in the struct acct in <file:include/linux/acct.h>). It is
  194. up to the user level program to do useful things with this
  195. information. This is generally a good idea, so say Y.
  196. config BSD_PROCESS_ACCT_V3
  197. bool "BSD Process Accounting version 3 file format"
  198. depends on BSD_PROCESS_ACCT
  199. default n
  200. help
  201. If you say Y here, the process accounting information is written
  202. in a new file format that also logs the process IDs of each
  203. process and it's parent. Note that this file format is incompatible
  204. with previous v0/v1/v2 file formats, so you will need updated tools
  205. for processing it. A preliminary version of these tools is available
  206. at <http://www.gnu.org/software/acct/>.
  207. config TASKSTATS
  208. bool "Export task/process statistics through netlink (EXPERIMENTAL)"
  209. depends on NET
  210. default n
  211. help
  212. Export selected statistics for tasks/processes through the
  213. generic netlink interface. Unlike BSD process accounting, the
  214. statistics are available during the lifetime of tasks/processes as
  215. responses to commands. Like BSD accounting, they are sent to user
  216. space on task exit.
  217. Say N if unsure.
  218. config TASK_DELAY_ACCT
  219. bool "Enable per-task delay accounting (EXPERIMENTAL)"
  220. depends on TASKSTATS
  221. help
  222. Collect information on time spent by a task waiting for system
  223. resources like cpu, synchronous block I/O completion and swapping
  224. in pages. Such statistics can help in setting a task's priorities
  225. relative to other tasks for cpu, io, rss limits etc.
  226. Say N if unsure.
  227. config TASK_XACCT
  228. bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
  229. depends on TASKSTATS
  230. help
  231. Collect extended task accounting data and send the data
  232. to userland for processing over the taskstats interface.
  233. Say N if unsure.
  234. config TASK_IO_ACCOUNTING
  235. bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
  236. depends on TASK_XACCT
  237. help
  238. Collect information on the number of bytes of storage I/O which this
  239. task has caused.
  240. Say N if unsure.
  241. config AUDIT
  242. bool "Auditing support"
  243. depends on NET
  244. help
  245. Enable auditing infrastructure that can be used with another
  246. kernel subsystem, such as SELinux (which requires this for
  247. logging of avc messages output). Does not do system-call
  248. auditing without CONFIG_AUDITSYSCALL.
  249. config AUDITSYSCALL
  250. bool "Enable system-call auditing support"
  251. depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64|| SUPERH)
  252. default y if SECURITY_SELINUX
  253. help
  254. Enable low-overhead system-call auditing infrastructure that
  255. can be used independently or with another kernel subsystem,
  256. such as SELinux. To use audit's filesystem watch feature, please
  257. ensure that INOTIFY is configured.
  258. config AUDIT_TREE
  259. def_bool y
  260. depends on AUDITSYSCALL
  261. select INOTIFY
  262. menu "RCU Subsystem"
  263. choice
  264. prompt "RCU Implementation"
  265. default TREE_RCU
  266. config TREE_RCU
  267. bool "Tree-based hierarchical RCU"
  268. help
  269. This option selects the RCU implementation that is
  270. designed for very large SMP system with hundreds or
  271. thousands of CPUs. It also scales down nicely to
  272. smaller systems.
  273. config TREE_PREEMPT_RCU
  274. bool "Preemptable tree-based hierarchical RCU"
  275. depends on PREEMPT
  276. help
  277. This option selects the RCU implementation that is
  278. designed for very large SMP systems with hundreds or
  279. thousands of CPUs, but for which real-time response
  280. is also required.
  281. endchoice
  282. config RCU_TRACE
  283. bool "Enable tracing for RCU"
  284. depends on TREE_RCU || TREE_PREEMPT_RCU
  285. help
  286. This option provides tracing in RCU which presents stats
  287. in debugfs for debugging RCU implementation.
  288. Say Y here if you want to enable RCU tracing
  289. Say N if you are unsure.
  290. config RCU_FANOUT
  291. int "Tree-based hierarchical RCU fanout value"
  292. range 2 64 if 64BIT
  293. range 2 32 if !64BIT
  294. depends on TREE_RCU || TREE_PREEMPT_RCU
  295. default 64 if 64BIT
  296. default 32 if !64BIT
  297. help
  298. This option controls the fanout of hierarchical implementations
  299. of RCU, allowing RCU to work efficiently on machines with
  300. large numbers of CPUs. This value must be at least the cube
  301. root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
  302. systems and up to 262,144 for 64-bit systems.
  303. Select a specific number if testing RCU itself.
  304. Take the default if unsure.
  305. config RCU_FANOUT_EXACT
  306. bool "Disable tree-based hierarchical RCU auto-balancing"
  307. depends on TREE_RCU || TREE_PREEMPT_RCU
  308. default n
  309. help
  310. This option forces use of the exact RCU_FANOUT value specified,
  311. regardless of imbalances in the hierarchy. This is useful for
  312. testing RCU itself, and might one day be useful on systems with
  313. strong NUMA behavior.
  314. Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
  315. Say N if unsure.
  316. config TREE_RCU_TRACE
  317. def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
  318. select DEBUG_FS
  319. help
  320. This option provides tracing for the TREE_RCU and
  321. TREE_PREEMPT_RCU implementations, permitting Makefile to
  322. trivially select kernel/rcutree_trace.c.
  323. endmenu # "RCU Subsystem"
  324. config IKCONFIG
  325. tristate "Kernel .config support"
  326. ---help---
  327. This option enables the complete Linux kernel ".config" file
  328. contents to be saved in the kernel. It provides documentation
  329. of which kernel options are used in a running kernel or in an
  330. on-disk kernel. This information can be extracted from the kernel
  331. image file with the script scripts/extract-ikconfig and used as
  332. input to rebuild the current kernel or to build another kernel.
  333. It can also be extracted from a running kernel by reading
  334. /proc/config.gz if enabled (below).
  335. config IKCONFIG_PROC
  336. bool "Enable access to .config through /proc/config.gz"
  337. depends on IKCONFIG && PROC_FS
  338. ---help---
  339. This option enables access to the kernel configuration file
  340. through /proc/config.gz.
  341. config LOG_BUF_SHIFT
  342. int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
  343. range 12 21
  344. default 17
  345. help
  346. Select kernel log buffer size as a power of 2.
  347. Examples:
  348. 17 => 128 KB
  349. 16 => 64 KB
  350. 15 => 32 KB
  351. 14 => 16 KB
  352. 13 => 8 KB
  353. 12 => 4 KB
  354. #
  355. # Architectures with an unreliable sched_clock() should select this:
  356. #
  357. config HAVE_UNSTABLE_SCHED_CLOCK
  358. bool
  359. config GROUP_SCHED
  360. bool "Group CPU scheduler"
  361. depends on EXPERIMENTAL
  362. default n
  363. help
  364. This feature lets CPU scheduler recognize task groups and control CPU
  365. bandwidth allocation to such task groups.
  366. In order to create a group from arbitrary set of processes, use
  367. CONFIG_CGROUPS. (See Control Group support.)
  368. config FAIR_GROUP_SCHED
  369. bool "Group scheduling for SCHED_OTHER"
  370. depends on GROUP_SCHED
  371. default GROUP_SCHED
  372. config RT_GROUP_SCHED
  373. bool "Group scheduling for SCHED_RR/FIFO"
  374. depends on EXPERIMENTAL
  375. depends on GROUP_SCHED
  376. default n
  377. help
  378. This feature lets you explicitly allocate real CPU bandwidth
  379. to users or control groups (depending on the "Basis for grouping tasks"
  380. setting below. If enabled, it will also make it impossible to
  381. schedule realtime tasks for non-root users until you allocate
  382. realtime bandwidth for them.
  383. See Documentation/scheduler/sched-rt-group.txt for more information.
  384. choice
  385. depends on GROUP_SCHED
  386. prompt "Basis for grouping tasks"
  387. default USER_SCHED
  388. config USER_SCHED
  389. bool "user id"
  390. help
  391. This option will choose userid as the basis for grouping
  392. tasks, thus providing equal CPU bandwidth to each user.
  393. config CGROUP_SCHED
  394. bool "Control groups"
  395. depends on CGROUPS
  396. help
  397. This option allows you to create arbitrary task groups
  398. using the "cgroup" pseudo filesystem and control
  399. the cpu bandwidth allocated to each such task group.
  400. Refer to Documentation/cgroups/cgroups.txt for more
  401. information on "cgroup" pseudo filesystem.
  402. endchoice
  403. menuconfig CGROUPS
  404. boolean "Control Group support"
  405. help
  406. This option adds support for grouping sets of processes together, for
  407. use with process control subsystems such as Cpusets, CFS, memory
  408. controls or device isolation.
  409. See
  410. - Documentation/scheduler/sched-design-CFS.txt (CFS)
  411. - Documentation/cgroups/ (features for grouping, isolation
  412. and resource control)
  413. Say N if unsure.
  414. if CGROUPS
  415. config CGROUP_DEBUG
  416. bool "Example debug cgroup subsystem"
  417. depends on CGROUPS
  418. default n
  419. help
  420. This option enables a simple cgroup subsystem that
  421. exports useful debugging information about the cgroups
  422. framework.
  423. Say N if unsure.
  424. config CGROUP_NS
  425. bool "Namespace cgroup subsystem"
  426. depends on CGROUPS
  427. help
  428. Provides a simple namespace cgroup subsystem to
  429. provide hierarchical naming of sets of namespaces,
  430. for instance virtual servers and checkpoint/restart
  431. jobs.
  432. config CGROUP_FREEZER
  433. bool "Freezer cgroup subsystem"
  434. depends on CGROUPS
  435. help
  436. Provides a way to freeze and unfreeze all tasks in a
  437. cgroup.
  438. config CGROUP_DEVICE
  439. bool "Device controller for cgroups"
  440. depends on CGROUPS && EXPERIMENTAL
  441. help
  442. Provides a cgroup implementing whitelists for devices which
  443. a process in the cgroup can mknod or open.
  444. config CPUSETS
  445. bool "Cpuset support"
  446. depends on CGROUPS
  447. help
  448. This option will let you create and manage CPUSETs which
  449. allow dynamically partitioning a system into sets of CPUs and
  450. Memory Nodes and assigning tasks to run only within those sets.
  451. This is primarily useful on large SMP or NUMA systems.
  452. Say N if unsure.
  453. config PROC_PID_CPUSET
  454. bool "Include legacy /proc/<pid>/cpuset file"
  455. depends on CPUSETS
  456. default y
  457. config CGROUP_CPUACCT
  458. bool "Simple CPU accounting cgroup subsystem"
  459. depends on CGROUPS
  460. help
  461. Provides a simple Resource Controller for monitoring the
  462. total CPU consumed by the tasks in a cgroup.
  463. config RESOURCE_COUNTERS
  464. bool "Resource counters"
  465. help
  466. This option enables controller independent resource accounting
  467. infrastructure that works with cgroups.
  468. depends on CGROUPS
  469. config CGROUP_MEM_RES_CTLR
  470. bool "Memory Resource Controller for Control Groups"
  471. depends on CGROUPS && RESOURCE_COUNTERS
  472. select MM_OWNER
  473. help
  474. Provides a memory resource controller that manages both anonymous
  475. memory and page cache. (See Documentation/cgroups/memory.txt)
  476. Note that setting this option increases fixed memory overhead
  477. associated with each page of memory in the system. By this,
  478. 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
  479. usage tracking struct at boot. Total amount of this is printed out
  480. at boot.
  481. Only enable when you're ok with these trade offs and really
  482. sure you need the memory resource controller. Even when you enable
  483. this, you can set "cgroup_disable=memory" at your boot option to
  484. disable memory resource controller and you can avoid overheads.
  485. (and lose benefits of memory resource controller)
  486. This config option also selects MM_OWNER config option, which
  487. could in turn add some fork/exit overhead.
  488. config CGROUP_MEM_RES_CTLR_SWAP
  489. bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)"
  490. depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL
  491. help
  492. Add swap management feature to memory resource controller. When you
  493. enable this, you can limit mem+swap usage per cgroup. In other words,
  494. when you disable this, memory resource controller has no cares to
  495. usage of swap...a process can exhaust all of the swap. This extension
  496. is useful when you want to avoid exhaustion swap but this itself
  497. adds more overheads and consumes memory for remembering information.
  498. Especially if you use 32bit system or small memory system, please
  499. be careful about enabling this. When memory resource controller
  500. is disabled by boot option, this will be automatically disabled and
  501. there will be no overhead from this. Even when you set this config=y,
  502. if boot option "noswapaccount" is set, swap will not be accounted.
  503. Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
  504. size is 4096bytes, 512k per 1Gbytes of swap.
  505. endif # CGROUPS
  506. config MM_OWNER
  507. bool
  508. config SYSFS_DEPRECATED
  509. bool
  510. config SYSFS_DEPRECATED_V2
  511. bool "remove sysfs features which may confuse old userspace tools"
  512. depends on SYSFS
  513. default n
  514. select SYSFS_DEPRECATED
  515. help
  516. This option switches the layout of sysfs to the deprecated
  517. version. Do not use it on recent distributions.
  518. The current sysfs layout features a unified device tree at
  519. /sys/devices/, which is able to express a hierarchy between
  520. class devices. If the deprecated option is set to Y, the
  521. unified device tree is split into a bus device tree at
  522. /sys/devices/ and several individual class device trees at
  523. /sys/class/. The class and bus devices will be connected by
  524. "<subsystem>:<name>" and the "device" links. The "block"
  525. class devices, will not show up in /sys/class/block/. Some
  526. subsystems will suppress the creation of some devices which
  527. depend on the unified device tree.
  528. This option is not a pure compatibility option that can
  529. be safely enabled on newer distributions. It will change the
  530. layout of sysfs to the non-extensible deprecated version,
  531. and disable some features, which can not be exported without
  532. confusing older userspace tools. Since 2007/2008 all major
  533. distributions do not enable this option, and ship no tools which
  534. depend on the deprecated layout or this option.
  535. If you are using a new kernel on an older distribution, or use
  536. older userspace tools, you might need to say Y here. Do not say Y,
  537. if the original kernel, that came with your distribution, has
  538. this option set to N.
  539. config RELAY
  540. bool "Kernel->user space relay support (formerly relayfs)"
  541. help
  542. This option enables support for relay interface support in
  543. certain file systems (such as debugfs).
  544. It is designed to provide an efficient mechanism for tools and
  545. facilities to relay large amounts of data from kernel space to
  546. user space.
  547. If unsure, say N.
  548. config NAMESPACES
  549. bool "Namespaces support" if EMBEDDED
  550. default !EMBEDDED
  551. help
  552. Provides the way to make tasks work with different objects using
  553. the same id. For example same IPC id may refer to different objects
  554. or same user id or pid may refer to different tasks when used in
  555. different namespaces.
  556. config UTS_NS
  557. bool "UTS namespace"
  558. depends on NAMESPACES
  559. help
  560. In this namespace tasks see different info provided with the
  561. uname() system call
  562. config IPC_NS
  563. bool "IPC namespace"
  564. depends on NAMESPACES && (SYSVIPC || POSIX_MQUEUE)
  565. help
  566. In this namespace tasks work with IPC ids which correspond to
  567. different IPC objects in different namespaces.
  568. config USER_NS
  569. bool "User namespace (EXPERIMENTAL)"
  570. depends on NAMESPACES && EXPERIMENTAL
  571. help
  572. This allows containers, i.e. vservers, to use user namespaces
  573. to provide different user info for different servers.
  574. If unsure, say N.
  575. config PID_NS
  576. bool "PID Namespaces (EXPERIMENTAL)"
  577. default n
  578. depends on NAMESPACES && EXPERIMENTAL
  579. help
  580. Support process id namespaces. This allows having multiple
  581. processes with the same pid as long as they are in different
  582. pid namespaces. This is a building block of containers.
  583. Unless you want to work with an experimental feature
  584. say N here.
  585. config NET_NS
  586. bool "Network namespace"
  587. default n
  588. depends on NAMESPACES && EXPERIMENTAL && NET
  589. help
  590. Allow user space to create what appear to be multiple instances
  591. of the network stack.
  592. config BLK_DEV_INITRD
  593. bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
  594. depends on BROKEN || !FRV
  595. help
  596. The initial RAM filesystem is a ramfs which is loaded by the
  597. boot loader (loadlin or lilo) and that is mounted as root
  598. before the normal boot procedure. It is typically used to
  599. load modules needed to mount the "real" root file system,
  600. etc. See <file:Documentation/initrd.txt> for details.
  601. If RAM disk support (BLK_DEV_RAM) is also included, this
  602. also enables initial RAM disk (initrd) support and adds
  603. 15 Kbytes (more on some other architectures) to the kernel size.
  604. If unsure say Y.
  605. if BLK_DEV_INITRD
  606. source "usr/Kconfig"
  607. endif
  608. config CC_OPTIMIZE_FOR_SIZE
  609. bool "Optimize for size"
  610. default y
  611. help
  612. Enabling this option will pass "-Os" instead of "-O2" to gcc
  613. resulting in a smaller kernel.
  614. If unsure, say Y.
  615. config SYSCTL
  616. bool
  617. config ANON_INODES
  618. bool
  619. menuconfig EMBEDDED
  620. bool "Configure standard kernel features (for small systems)"
  621. help
  622. This option allows certain base kernel options and settings
  623. to be disabled or tweaked. This is for specialized
  624. environments which can tolerate a "non-standard" kernel.
  625. Only use this if you really know what you are doing.
  626. config UID16
  627. bool "Enable 16-bit UID system calls" if EMBEDDED
  628. depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
  629. default y
  630. help
  631. This enables the legacy 16-bit UID syscall wrappers.
  632. config SYSCTL_SYSCALL
  633. bool "Sysctl syscall support" if EMBEDDED
  634. default y
  635. select SYSCTL
  636. ---help---
  637. sys_sysctl uses binary paths that have been found challenging
  638. to properly maintain and use. The interface in /proc/sys
  639. using paths with ascii names is now the primary path to this
  640. information.
  641. Almost nothing using the binary sysctl interface so if you are
  642. trying to save some space it is probably safe to disable this,
  643. making your kernel marginally smaller.
  644. If unsure say Y here.
  645. config KALLSYMS
  646. bool "Load all symbols for debugging/ksymoops" if EMBEDDED
  647. default y
  648. help
  649. Say Y here to let the kernel print out symbolic crash information and
  650. symbolic stack backtraces. This increases the size of the kernel
  651. somewhat, as all symbols have to be loaded into the kernel image.
  652. config KALLSYMS_ALL
  653. bool "Include all symbols in kallsyms"
  654. depends on DEBUG_KERNEL && KALLSYMS
  655. help
  656. Normally kallsyms only contains the symbols of functions, for nicer
  657. OOPS messages. Some debuggers can use kallsyms for other
  658. symbols too: say Y here to include all symbols, if you need them
  659. and you don't care about adding 300k to the size of your kernel.
  660. Say N.
  661. config KALLSYMS_EXTRA_PASS
  662. bool "Do an extra kallsyms pass"
  663. depends on KALLSYMS
  664. help
  665. If kallsyms is not working correctly, the build will fail with
  666. inconsistent kallsyms data. If that occurs, log a bug report and
  667. turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
  668. Always say N here unless you find a bug in kallsyms, which must be
  669. reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
  670. you wait for kallsyms to be fixed.
  671. config HOTPLUG
  672. bool "Support for hot-pluggable devices" if EMBEDDED
  673. default y
  674. help
  675. This option is provided for the case where no hotplug or uevent
  676. capabilities is wanted by the kernel. You should only consider
  677. disabling this option for embedded systems that do not use modules, a
  678. dynamic /dev tree, or dynamic device discovery. Just say Y.
  679. config PRINTK
  680. default y
  681. bool "Enable support for printk" if EMBEDDED
  682. help
  683. This option enables normal printk support. Removing it
  684. eliminates most of the message strings from the kernel image
  685. and makes the kernel more or less silent. As this makes it
  686. very difficult to diagnose system problems, saying N here is
  687. strongly discouraged.
  688. config BUG
  689. bool "BUG() support" if EMBEDDED
  690. default y
  691. help
  692. Disabling this option eliminates support for BUG and WARN, reducing
  693. the size of your kernel image and potentially quietly ignoring
  694. numerous fatal conditions. You should only consider disabling this
  695. option for embedded systems with no facilities for reporting errors.
  696. Just say Y.
  697. config ELF_CORE
  698. default y
  699. bool "Enable ELF core dumps" if EMBEDDED
  700. help
  701. Enable support for generating core dumps. Disabling saves about 4k.
  702. config PCSPKR_PLATFORM
  703. bool "Enable PC-Speaker support" if EMBEDDED
  704. depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
  705. default y
  706. help
  707. This option allows to disable the internal PC-Speaker
  708. support, saving some memory.
  709. config BASE_FULL
  710. default y
  711. bool "Enable full-sized data structures for core" if EMBEDDED
  712. help
  713. Disabling this option reduces the size of miscellaneous core
  714. kernel data structures. This saves memory on small machines,
  715. but may reduce performance.
  716. config FUTEX
  717. bool "Enable futex support" if EMBEDDED
  718. default y
  719. select RT_MUTEXES
  720. help
  721. Disabling this option will cause the kernel to be built without
  722. support for "fast userspace mutexes". The resulting kernel may not
  723. run glibc-based applications correctly.
  724. config EPOLL
  725. bool "Enable eventpoll support" if EMBEDDED
  726. default y
  727. select ANON_INODES
  728. help
  729. Disabling this option will cause the kernel to be built without
  730. support for epoll family of system calls.
  731. config SIGNALFD
  732. bool "Enable signalfd() system call" if EMBEDDED
  733. select ANON_INODES
  734. default y
  735. help
  736. Enable the signalfd() system call that allows to receive signals
  737. on a file descriptor.
  738. If unsure, say Y.
  739. config TIMERFD
  740. bool "Enable timerfd() system call" if EMBEDDED
  741. select ANON_INODES
  742. default y
  743. help
  744. Enable the timerfd() system call that allows to receive timer
  745. events on a file descriptor.
  746. If unsure, say Y.
  747. config EVENTFD
  748. bool "Enable eventfd() system call" if EMBEDDED
  749. select ANON_INODES
  750. default y
  751. help
  752. Enable the eventfd() system call that allows to receive both
  753. kernel notification (ie. KAIO) or userspace notifications.
  754. If unsure, say Y.
  755. config SHMEM
  756. bool "Use full shmem filesystem" if EMBEDDED
  757. default y
  758. depends on MMU
  759. help
  760. The shmem is an internal filesystem used to manage shared memory.
  761. It is backed by swap and manages resource limits. It is also exported
  762. to userspace as tmpfs if TMPFS is enabled. Disabling this
  763. option replaces shmem and tmpfs with the much simpler ramfs code,
  764. which may be appropriate on small systems without swap.
  765. config AIO
  766. bool "Enable AIO support" if EMBEDDED
  767. default y
  768. help
  769. This option enables POSIX asynchronous I/O which may by used
  770. by some high performance threaded applications. Disabling
  771. this option saves about 7k.
  772. config HAVE_PERF_COUNTERS
  773. bool
  774. help
  775. See tools/perf/design.txt for details.
  776. menu "Performance Counters"
  777. config PERF_COUNTERS
  778. bool "Kernel Performance Counters"
  779. default y if PROFILING
  780. depends on HAVE_PERF_COUNTERS
  781. select ANON_INODES
  782. help
  783. Enable kernel support for performance counter hardware.
  784. Performance counters are special hardware registers available
  785. on most modern CPUs. These registers count the number of certain
  786. types of hw events: such as instructions executed, cachemisses
  787. suffered, or branches mis-predicted - without slowing down the
  788. kernel or applications. These registers can also trigger interrupts
  789. when a threshold number of events have passed - and can thus be
  790. used to profile the code that runs on that CPU.
  791. The Linux Performance Counter subsystem provides an abstraction of
  792. these hardware capabilities, available via a system call. It
  793. provides per task and per CPU counters, and it provides event
  794. capabilities on top of those.
  795. Say Y if unsure.
  796. config EVENT_PROFILE
  797. bool "Tracepoint profiling sources"
  798. depends on PERF_COUNTERS && EVENT_TRACING
  799. default y
  800. help
  801. Allow the use of tracepoints as software performance counters.
  802. When this is enabled, you can create perf counters based on
  803. tracepoints using PERF_TYPE_TRACEPOINT and the tracepoint ID
  804. found in debugfs://tracing/events/*/*/id. (The -e/--events
  805. option to the perf tool can parse and interpret symbolic
  806. tracepoints, in the subsystem:tracepoint_name format.)
  807. endmenu
  808. config VM_EVENT_COUNTERS
  809. default y
  810. bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
  811. help
  812. VM event counters are needed for event counts to be shown.
  813. This option allows the disabling of the VM event counters
  814. on EMBEDDED systems. /proc/vmstat will only show page counts
  815. if VM event counters are disabled.
  816. config PCI_QUIRKS
  817. default y
  818. bool "Enable PCI quirk workarounds" if EMBEDDED
  819. depends on PCI
  820. help
  821. This enables workarounds for various PCI chipset
  822. bugs/quirks. Disable this only if your target machine is
  823. unaffected by PCI quirks.
  824. config SLUB_DEBUG
  825. default y
  826. bool "Enable SLUB debugging support" if EMBEDDED
  827. depends on SLUB && SYSFS
  828. help
  829. SLUB has extensive debug support features. Disabling these can
  830. result in significant savings in code size. This also disables
  831. SLUB sysfs support. /sys/slab will not exist and there will be
  832. no support for cache validation etc.
  833. config STRIP_ASM_SYMS
  834. bool "Strip assembler-generated symbols during link"
  835. default n
  836. help
  837. Strip internal assembler-generated symbols during a link (symbols
  838. that look like '.Lxxx') so they don't pollute the output of
  839. get_wchan() and suchlike.
  840. config COMPAT_BRK
  841. bool "Disable heap randomization"
  842. default y
  843. help
  844. Randomizing heap placement makes heap exploits harder, but it
  845. also breaks ancient binaries (including anything libc5 based).
  846. This option changes the bootup default to heap randomization
  847. disabled, and can be overridden at runtime by setting
  848. /proc/sys/kernel/randomize_va_space to 2.
  849. On non-ancient distros (post-2000 ones) N is usually a safe choice.
  850. choice
  851. prompt "Choose SLAB allocator"
  852. default SLUB
  853. help
  854. This option allows to select a slab allocator.
  855. config SLAB
  856. bool "SLAB"
  857. help
  858. The regular slab allocator that is established and known to work
  859. well in all environments. It organizes cache hot objects in
  860. per cpu and per node queues.
  861. config SLUB
  862. bool "SLUB (Unqueued Allocator)"
  863. help
  864. SLUB is a slab allocator that minimizes cache line usage
  865. instead of managing queues of cached objects (SLAB approach).
  866. Per cpu caching is realized using slabs of objects instead
  867. of queues of objects. SLUB can use memory efficiently
  868. and has enhanced diagnostics. SLUB is the default choice for
  869. a slab allocator.
  870. config SLOB
  871. depends on EMBEDDED
  872. bool "SLOB (Simple Allocator)"
  873. help
  874. SLOB replaces the stock allocator with a drastically simpler
  875. allocator. SLOB is generally more space efficient but
  876. does not perform as well on large systems.
  877. endchoice
  878. config PROFILING
  879. bool "Profiling support (EXPERIMENTAL)"
  880. help
  881. Say Y here to enable the extended profiling support mechanisms used
  882. by profilers such as OProfile.
  883. #
  884. # Place an empty function call at each tracepoint site. Can be
  885. # dynamically changed for a probe function.
  886. #
  887. config TRACEPOINTS
  888. bool
  889. config MARKERS
  890. bool "Activate markers"
  891. select TRACEPOINTS
  892. help
  893. Place an empty function call at each marker site. Can be
  894. dynamically changed for a probe function.
  895. source "arch/Kconfig"
  896. config SLOW_WORK
  897. default n
  898. bool
  899. help
  900. The slow work thread pool provides a number of dynamically allocated
  901. threads that can be used by the kernel to perform operations that
  902. take a relatively long time.
  903. An example of this would be CacheFiles doing a path lookup followed
  904. by a series of mkdirs and a create call, all of which have to touch
  905. disk.
  906. See Documentation/slow-work.txt.
  907. endmenu # General setup
  908. config HAVE_GENERIC_DMA_COHERENT
  909. bool
  910. default n
  911. config SLABINFO
  912. bool
  913. depends on PROC_FS
  914. depends on SLAB || SLUB_DEBUG
  915. default y
  916. config RT_MUTEXES
  917. boolean
  918. config BASE_SMALL
  919. int
  920. default 0 if BASE_FULL
  921. default 1 if !BASE_FULL
  922. menuconfig MODULES
  923. bool "Enable loadable module support"
  924. help
  925. Kernel modules are small pieces of compiled code which can
  926. be inserted in the running kernel, rather than being
  927. permanently built into the kernel. You use the "modprobe"
  928. tool to add (and sometimes remove) them. If you say Y here,
  929. many parts of the kernel can be built as modules (by
  930. answering M instead of Y where indicated): this is most
  931. useful for infrequently used options which are not required
  932. for booting. For more information, see the man pages for
  933. modprobe, lsmod, modinfo, insmod and rmmod.
  934. If you say Y here, you will need to run "make
  935. modules_install" to put the modules under /lib/modules/
  936. where modprobe can find them (you may need to be root to do
  937. this).
  938. If unsure, say Y.
  939. if MODULES
  940. config MODULE_FORCE_LOAD
  941. bool "Forced module loading"
  942. default n
  943. help
  944. Allow loading of modules without version information (ie. modprobe
  945. --force). Forced module loading sets the 'F' (forced) taint flag and
  946. is usually a really bad idea.
  947. config MODULE_UNLOAD
  948. bool "Module unloading"
  949. help
  950. Without this option you will not be able to unload any
  951. modules (note that some modules may not be unloadable
  952. anyway), which makes your kernel smaller, faster
  953. and simpler. If unsure, say Y.
  954. config MODULE_FORCE_UNLOAD
  955. bool "Forced module unloading"
  956. depends on MODULE_UNLOAD && EXPERIMENTAL
  957. help
  958. This option allows you to force a module to unload, even if the
  959. kernel believes it is unsafe: the kernel will remove the module
  960. without waiting for anyone to stop using it (using the -f option to
  961. rmmod). This is mainly for kernel developers and desperate users.
  962. If unsure, say N.
  963. config MODVERSIONS
  964. bool "Module versioning support"
  965. help
  966. Usually, you have to use modules compiled with your kernel.
  967. Saying Y here makes it sometimes possible to use modules
  968. compiled for different kernels, by adding enough information
  969. to the modules to (hopefully) spot any changes which would
  970. make them incompatible with the kernel you are running. If
  971. unsure, say N.
  972. config MODULE_SRCVERSION_ALL
  973. bool "Source checksum for all modules"
  974. help
  975. Modules which contain a MODULE_VERSION get an extra "srcversion"
  976. field inserted into their modinfo section, which contains a
  977. sum of the source files which made it. This helps maintainers
  978. see exactly which source was used to build a module (since
  979. others sometimes change the module source without updating
  980. the version). With this option, such a "srcversion" field
  981. will be created for all modules. If unsure, say N.
  982. endif # MODULES
  983. config INIT_ALL_POSSIBLE
  984. bool
  985. help
  986. Back when each arch used to define their own cpu_online_map and
  987. cpu_possible_map, some of them chose to initialize cpu_possible_map
  988. with all 1s, and others with all 0s. When they were centralised,
  989. it was better to provide this option than to break all the archs
  990. and have several arch maintainers pursuing me down dark alleys.
  991. config STOP_MACHINE
  992. bool
  993. default y
  994. depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
  995. help
  996. Need stop_machine() primitive.
  997. source "block/Kconfig"
  998. config PREEMPT_NOTIFIERS
  999. bool