Kconfig 47 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. config HAVE_IRQ_WORK
  20. bool
  21. config IRQ_WORK
  22. bool
  23. depends on HAVE_IRQ_WORK
  24. menu "General setup"
  25. config EXPERIMENTAL
  26. bool "Prompt for development and/or incomplete code/drivers"
  27. ---help---
  28. Some of the various things that Linux supports (such as network
  29. drivers, file systems, network protocols, etc.) can be in a state
  30. of development where the functionality, stability, or the level of
  31. testing is not yet high enough for general use. This is usually
  32. known as the "alpha-test" phase among developers. If a feature is
  33. currently in alpha-test, then the developers usually discourage
  34. uninformed widespread use of this feature by the general public to
  35. avoid "Why doesn't this work?" type mail messages. However, active
  36. testing and use of these systems is welcomed. Just be aware that it
  37. may not meet the normal level of reliability or it may fail to work
  38. in some special cases. Detailed bug reports from people familiar
  39. with the kernel internals are usually welcomed by the developers
  40. (before submitting bug reports, please read the documents
  41. <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
  42. <file:Documentation/BUG-HUNTING>, and
  43. <file:Documentation/oops-tracing.txt> in the kernel source).
  44. This option will also make obsoleted drivers available. These are
  45. drivers that have been replaced by something else, and/or are
  46. scheduled to be removed in a future kernel release.
  47. Unless you intend to help test and develop a feature or driver that
  48. falls into this category, or you have a situation that requires
  49. using these features, you should probably say N here, which will
  50. cause the configurator to present you with fewer choices. If
  51. you say Y here, you will be offered the choice of using features or
  52. drivers that are currently considered to be in the alpha-test phase.
  53. config BROKEN
  54. bool
  55. config BROKEN_ON_SMP
  56. bool
  57. depends on BROKEN || !SMP
  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_XZ
  104. bool
  105. config HAVE_KERNEL_LZO
  106. bool
  107. choice
  108. prompt "Kernel compression mode"
  109. default KERNEL_GZIP
  110. depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
  111. help
  112. The linux kernel is a kind of self-extracting executable.
  113. Several compression algorithms are available, which differ
  114. in efficiency, compression and decompression speed.
  115. Compression speed is only relevant when building a kernel.
  116. Decompression speed is relevant at each boot.
  117. If you have any problems with bzip2 or lzma compressed
  118. kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
  119. version of this functionality (bzip2 only), for 2.4, was
  120. supplied by Christian Ludwig)
  121. High compression options are mostly useful for users, who
  122. are low on disk space (embedded systems), but for whom ram
  123. size matters less.
  124. If in doubt, select 'gzip'
  125. config KERNEL_GZIP
  126. bool "Gzip"
  127. depends on HAVE_KERNEL_GZIP
  128. help
  129. The old and tried gzip compression. It provides a good balance
  130. between compression ratio and decompression speed.
  131. config KERNEL_BZIP2
  132. bool "Bzip2"
  133. depends on HAVE_KERNEL_BZIP2
  134. help
  135. Its compression ratio and speed is intermediate.
  136. Decompression speed is slowest among the three. The kernel
  137. size is about 10% smaller with bzip2, in comparison to gzip.
  138. Bzip2 uses a large amount of memory. For modern kernels you
  139. will need at least 8MB RAM or more for booting.
  140. config KERNEL_LZMA
  141. bool "LZMA"
  142. depends on HAVE_KERNEL_LZMA
  143. help
  144. The most recent compression algorithm.
  145. Its ratio is best, decompression speed is between the other
  146. two. Compression is slowest. The kernel size is about 33%
  147. smaller with LZMA in comparison to gzip.
  148. config KERNEL_XZ
  149. bool "XZ"
  150. depends on HAVE_KERNEL_XZ
  151. help
  152. XZ uses the LZMA2 algorithm and instruction set specific
  153. BCJ filters which can improve compression ratio of executable
  154. code. The size of the kernel is about 30% smaller with XZ in
  155. comparison to gzip. On architectures for which there is a BCJ
  156. filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
  157. will create a few percent smaller kernel than plain LZMA.
  158. The speed is about the same as with LZMA: The decompression
  159. speed of XZ is better than that of bzip2 but worse than gzip
  160. and LZO. Compression is slow.
  161. config KERNEL_LZO
  162. bool "LZO"
  163. depends on HAVE_KERNEL_LZO
  164. help
  165. Its compression ratio is the poorest among the 4. The kernel
  166. size is about 10% bigger than gzip; however its speed
  167. (both compression and decompression) is the fastest.
  168. endchoice
  169. config DEFAULT_HOSTNAME
  170. string "Default hostname"
  171. default "(none)"
  172. help
  173. This option determines the default system hostname before userspace
  174. calls sethostname(2). The kernel traditionally uses "(none)" here,
  175. but you may wish to use a different default here to make a minimal
  176. system more usable with less configuration.
  177. config SWAP
  178. bool "Support for paging of anonymous memory (swap)"
  179. depends on MMU && BLOCK
  180. default y
  181. help
  182. This option allows you to choose whether you want to have support
  183. for so called swap devices or swap files in your kernel that are
  184. used to provide more virtual memory than the actual RAM present
  185. in your computer. If unsure say Y.
  186. config SYSVIPC
  187. bool "System V IPC"
  188. ---help---
  189. Inter Process Communication is a suite of library functions and
  190. system calls which let processes (running programs) synchronize and
  191. exchange information. It is generally considered to be a good thing,
  192. and some programs won't run unless you say Y here. In particular, if
  193. you want to run the DOS emulator dosemu under Linux (read the
  194. DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
  195. you'll need to say Y here.
  196. You can find documentation about IPC with "info ipc" and also in
  197. section 6.4 of the Linux Programmer's Guide, available from
  198. <http://www.tldp.org/guides.html>.
  199. config SYSVIPC_SYSCTL
  200. bool
  201. depends on SYSVIPC
  202. depends on SYSCTL
  203. default y
  204. config POSIX_MQUEUE
  205. bool "POSIX Message Queues"
  206. depends on NET && EXPERIMENTAL
  207. ---help---
  208. POSIX variant of message queues is a part of IPC. In POSIX message
  209. queues every message has a priority which decides about succession
  210. of receiving it by a process. If you want to compile and run
  211. programs written e.g. for Solaris with use of its POSIX message
  212. queues (functions mq_*) say Y here.
  213. POSIX message queues are visible as a filesystem called 'mqueue'
  214. and can be mounted somewhere if you want to do filesystem
  215. operations on message queues.
  216. If unsure, say Y.
  217. config POSIX_MQUEUE_SYSCTL
  218. bool
  219. depends on POSIX_MQUEUE
  220. depends on SYSCTL
  221. default y
  222. config BSD_PROCESS_ACCT
  223. bool "BSD Process Accounting"
  224. help
  225. If you say Y here, a user level program will be able to instruct the
  226. kernel (via a special system call) to write process accounting
  227. information to a file: whenever a process exits, information about
  228. that process will be appended to the file by the kernel. The
  229. information includes things such as creation time, owning user,
  230. command name, memory usage, controlling terminal etc. (the complete
  231. list is in the struct acct in <file:include/linux/acct.h>). It is
  232. up to the user level program to do useful things with this
  233. information. This is generally a good idea, so say Y.
  234. config BSD_PROCESS_ACCT_V3
  235. bool "BSD Process Accounting version 3 file format"
  236. depends on BSD_PROCESS_ACCT
  237. default n
  238. help
  239. If you say Y here, the process accounting information is written
  240. in a new file format that also logs the process IDs of each
  241. process and it's parent. Note that this file format is incompatible
  242. with previous v0/v1/v2 file formats, so you will need updated tools
  243. for processing it. A preliminary version of these tools is available
  244. at <http://www.gnu.org/software/acct/>.
  245. config FHANDLE
  246. bool "open by fhandle syscalls"
  247. select EXPORTFS
  248. help
  249. If you say Y here, a user level program will be able to map
  250. file names to handle and then later use the handle for
  251. different file system operations. This is useful in implementing
  252. userspace file servers, which now track files using handles instead
  253. of names. The handle would remain the same even if file names
  254. get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
  255. syscalls.
  256. config TASKSTATS
  257. bool "Export task/process statistics through netlink (EXPERIMENTAL)"
  258. depends on NET
  259. default n
  260. help
  261. Export selected statistics for tasks/processes through the
  262. generic netlink interface. Unlike BSD process accounting, the
  263. statistics are available during the lifetime of tasks/processes as
  264. responses to commands. Like BSD accounting, they are sent to user
  265. space on task exit.
  266. Say N if unsure.
  267. config TASK_DELAY_ACCT
  268. bool "Enable per-task delay accounting (EXPERIMENTAL)"
  269. depends on TASKSTATS
  270. help
  271. Collect information on time spent by a task waiting for system
  272. resources like cpu, synchronous block I/O completion and swapping
  273. in pages. Such statistics can help in setting a task's priorities
  274. relative to other tasks for cpu, io, rss limits etc.
  275. Say N if unsure.
  276. config TASK_XACCT
  277. bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
  278. depends on TASKSTATS
  279. help
  280. Collect extended task accounting data and send the data
  281. to userland for processing over the taskstats interface.
  282. Say N if unsure.
  283. config TASK_IO_ACCOUNTING
  284. bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
  285. depends on TASK_XACCT
  286. help
  287. Collect information on the number of bytes of storage I/O which this
  288. task has caused.
  289. Say N if unsure.
  290. config AUDIT
  291. bool "Auditing support"
  292. depends on NET
  293. help
  294. Enable auditing infrastructure that can be used with another
  295. kernel subsystem, such as SELinux (which requires this for
  296. logging of avc messages output). Does not do system-call
  297. auditing without CONFIG_AUDITSYSCALL.
  298. config AUDITSYSCALL
  299. bool "Enable system-call auditing support"
  300. depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || ARM)
  301. default y if SECURITY_SELINUX
  302. help
  303. Enable low-overhead system-call auditing infrastructure that
  304. can be used independently or with another kernel subsystem,
  305. such as SELinux.
  306. config AUDIT_WATCH
  307. def_bool y
  308. depends on AUDITSYSCALL
  309. select FSNOTIFY
  310. config AUDIT_TREE
  311. def_bool y
  312. depends on AUDITSYSCALL
  313. select FSNOTIFY
  314. config AUDIT_LOGINUID_IMMUTABLE
  315. bool "Make audit loginuid immutable"
  316. depends on AUDIT
  317. help
  318. The config option toggles if a task setting its loginuid requires
  319. CAP_SYS_AUDITCONTROL or if that task should require no special permissions
  320. but should instead only allow setting its loginuid if it was never
  321. previously set. On systems which use systemd or a similar central
  322. process to restart login services this should be set to true. On older
  323. systems in which an admin would typically have to directly stop and
  324. start processes this should be set to false. Setting this to true allows
  325. one to drop potentially dangerous capabilites from the login tasks,
  326. but may not be backwards compatible with older init systems.
  327. source "kernel/irq/Kconfig"
  328. menu "RCU Subsystem"
  329. choice
  330. prompt "RCU Implementation"
  331. default TREE_RCU
  332. config TREE_RCU
  333. bool "Tree-based hierarchical RCU"
  334. depends on !PREEMPT && SMP
  335. help
  336. This option selects the RCU implementation that is
  337. designed for very large SMP system with hundreds or
  338. thousands of CPUs. It also scales down nicely to
  339. smaller systems.
  340. config TREE_PREEMPT_RCU
  341. bool "Preemptible tree-based hierarchical RCU"
  342. depends on PREEMPT && SMP
  343. help
  344. This option selects the RCU implementation that is
  345. designed for very large SMP systems with hundreds or
  346. thousands of CPUs, but for which real-time response
  347. is also required. It also scales down nicely to
  348. smaller systems.
  349. config TINY_RCU
  350. bool "UP-only small-memory-footprint RCU"
  351. depends on !PREEMPT && !SMP
  352. help
  353. This option selects the RCU implementation that is
  354. designed for UP systems from which real-time response
  355. is not required. This option greatly reduces the
  356. memory footprint of RCU.
  357. config TINY_PREEMPT_RCU
  358. bool "Preemptible UP-only small-memory-footprint RCU"
  359. depends on PREEMPT && !SMP
  360. help
  361. This option selects the RCU implementation that is designed
  362. for real-time UP systems. This option greatly reduces the
  363. memory footprint of RCU.
  364. endchoice
  365. config PREEMPT_RCU
  366. def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
  367. help
  368. This option enables preemptible-RCU code that is common between
  369. the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
  370. config RCU_FANOUT
  371. int "Tree-based hierarchical RCU fanout value"
  372. range 2 64 if 64BIT
  373. range 2 32 if !64BIT
  374. depends on TREE_RCU || TREE_PREEMPT_RCU
  375. default 64 if 64BIT
  376. default 32 if !64BIT
  377. help
  378. This option controls the fanout of hierarchical implementations
  379. of RCU, allowing RCU to work efficiently on machines with
  380. large numbers of CPUs. This value must be at least the fourth
  381. root of NR_CPUS, which allows NR_CPUS to be insanely large.
  382. The default value of RCU_FANOUT should be used for production
  383. systems, but if you are stress-testing the RCU implementation
  384. itself, small RCU_FANOUT values allow you to test large-system
  385. code paths on small(er) systems.
  386. Select a specific number if testing RCU itself.
  387. Take the default if unsure.
  388. config RCU_FANOUT_EXACT
  389. bool "Disable tree-based hierarchical RCU auto-balancing"
  390. depends on TREE_RCU || TREE_PREEMPT_RCU
  391. default n
  392. help
  393. This option forces use of the exact RCU_FANOUT value specified,
  394. regardless of imbalances in the hierarchy. This is useful for
  395. testing RCU itself, and might one day be useful on systems with
  396. strong NUMA behavior.
  397. Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
  398. Say N if unsure.
  399. config RCU_FAST_NO_HZ
  400. bool "Accelerate last non-dyntick-idle CPU's grace periods"
  401. depends on NO_HZ && SMP
  402. default n
  403. help
  404. This option causes RCU to attempt to accelerate grace periods
  405. in order to allow CPUs to enter dynticks-idle state more
  406. quickly. On the other hand, this option increases the overhead
  407. of the dynticks-idle checking, particularly on systems with
  408. large numbers of CPUs.
  409. Say Y if energy efficiency is critically important, particularly
  410. if you have relatively few CPUs.
  411. Say N if you are unsure.
  412. config TREE_RCU_TRACE
  413. def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
  414. select DEBUG_FS
  415. help
  416. This option provides tracing for the TREE_RCU and
  417. TREE_PREEMPT_RCU implementations, permitting Makefile to
  418. trivially select kernel/rcutree_trace.c.
  419. config RCU_BOOST
  420. bool "Enable RCU priority boosting"
  421. depends on RT_MUTEXES && PREEMPT_RCU
  422. default n
  423. help
  424. This option boosts the priority of preempted RCU readers that
  425. block the current preemptible RCU grace period for too long.
  426. This option also prevents heavy loads from blocking RCU
  427. callback invocation for all flavors of RCU.
  428. Say Y here if you are working with real-time apps or heavy loads
  429. Say N here if you are unsure.
  430. config RCU_BOOST_PRIO
  431. int "Real-time priority to boost RCU readers to"
  432. range 1 99
  433. depends on RCU_BOOST
  434. default 1
  435. help
  436. This option specifies the real-time priority to which long-term
  437. preempted RCU readers are to be boosted. If you are working
  438. with a real-time application that has one or more CPU-bound
  439. threads running at a real-time priority level, you should set
  440. RCU_BOOST_PRIO to a priority higher then the highest-priority
  441. real-time CPU-bound thread. The default RCU_BOOST_PRIO value
  442. of 1 is appropriate in the common case, which is real-time
  443. applications that do not have any CPU-bound threads.
  444. Some real-time applications might not have a single real-time
  445. thread that saturates a given CPU, but instead might have
  446. multiple real-time threads that, taken together, fully utilize
  447. that CPU. In this case, you should set RCU_BOOST_PRIO to
  448. a priority higher than the lowest-priority thread that is
  449. conspiring to prevent the CPU from running any non-real-time
  450. tasks. For example, if one thread at priority 10 and another
  451. thread at priority 5 are between themselves fully consuming
  452. the CPU time on a given CPU, then RCU_BOOST_PRIO should be
  453. set to priority 6 or higher.
  454. Specify the real-time priority, or take the default if unsure.
  455. config RCU_BOOST_DELAY
  456. int "Milliseconds to delay boosting after RCU grace-period start"
  457. range 0 3000
  458. depends on RCU_BOOST
  459. default 500
  460. help
  461. This option specifies the time to wait after the beginning of
  462. a given grace period before priority-boosting preempted RCU
  463. readers blocking that grace period. Note that any RCU reader
  464. blocking an expedited RCU grace period is boosted immediately.
  465. Accept the default if unsure.
  466. endmenu # "RCU Subsystem"
  467. config IKCONFIG
  468. tristate "Kernel .config support"
  469. ---help---
  470. This option enables the complete Linux kernel ".config" file
  471. contents to be saved in the kernel. It provides documentation
  472. of which kernel options are used in a running kernel or in an
  473. on-disk kernel. This information can be extracted from the kernel
  474. image file with the script scripts/extract-ikconfig and used as
  475. input to rebuild the current kernel or to build another kernel.
  476. It can also be extracted from a running kernel by reading
  477. /proc/config.gz if enabled (below).
  478. config IKCONFIG_PROC
  479. bool "Enable access to .config through /proc/config.gz"
  480. depends on IKCONFIG && PROC_FS
  481. ---help---
  482. This option enables access to the kernel configuration file
  483. through /proc/config.gz.
  484. config LOG_BUF_SHIFT
  485. int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
  486. range 12 21
  487. default 17
  488. help
  489. Select kernel log buffer size as a power of 2.
  490. Examples:
  491. 17 => 128 KB
  492. 16 => 64 KB
  493. 15 => 32 KB
  494. 14 => 16 KB
  495. 13 => 8 KB
  496. 12 => 4 KB
  497. #
  498. # Architectures with an unreliable sched_clock() should select this:
  499. #
  500. config HAVE_UNSTABLE_SCHED_CLOCK
  501. bool
  502. menuconfig CGROUPS
  503. boolean "Control Group support"
  504. depends on EVENTFD
  505. help
  506. This option adds support for grouping sets of processes together, for
  507. use with process control subsystems such as Cpusets, CFS, memory
  508. controls or device isolation.
  509. See
  510. - Documentation/scheduler/sched-design-CFS.txt (CFS)
  511. - Documentation/cgroups/ (features for grouping, isolation
  512. and resource control)
  513. Say N if unsure.
  514. if CGROUPS
  515. config CGROUP_DEBUG
  516. bool "Example debug cgroup subsystem"
  517. default n
  518. help
  519. This option enables a simple cgroup subsystem that
  520. exports useful debugging information about the cgroups
  521. framework.
  522. Say N if unsure.
  523. config CGROUP_FREEZER
  524. bool "Freezer cgroup subsystem"
  525. help
  526. Provides a way to freeze and unfreeze all tasks in a
  527. cgroup.
  528. config CGROUP_DEVICE
  529. bool "Device controller for cgroups"
  530. help
  531. Provides a cgroup implementing whitelists for devices which
  532. a process in the cgroup can mknod or open.
  533. config CPUSETS
  534. bool "Cpuset support"
  535. help
  536. This option will let you create and manage CPUSETs which
  537. allow dynamically partitioning a system into sets of CPUs and
  538. Memory Nodes and assigning tasks to run only within those sets.
  539. This is primarily useful on large SMP or NUMA systems.
  540. Say N if unsure.
  541. config PROC_PID_CPUSET
  542. bool "Include legacy /proc/<pid>/cpuset file"
  543. depends on CPUSETS
  544. default y
  545. config CGROUP_CPUACCT
  546. bool "Simple CPU accounting cgroup subsystem"
  547. help
  548. Provides a simple Resource Controller for monitoring the
  549. total CPU consumed by the tasks in a cgroup.
  550. config RESOURCE_COUNTERS
  551. bool "Resource counters"
  552. help
  553. This option enables controller independent resource accounting
  554. infrastructure that works with cgroups.
  555. config CGROUP_MEM_RES_CTLR
  556. bool "Memory Resource Controller for Control Groups"
  557. depends on RESOURCE_COUNTERS
  558. select MM_OWNER
  559. help
  560. Provides a memory resource controller that manages both anonymous
  561. memory and page cache. (See Documentation/cgroups/memory.txt)
  562. Note that setting this option increases fixed memory overhead
  563. associated with each page of memory in the system. By this,
  564. 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
  565. usage tracking struct at boot. Total amount of this is printed out
  566. at boot.
  567. Only enable when you're ok with these trade offs and really
  568. sure you need the memory resource controller. Even when you enable
  569. this, you can set "cgroup_disable=memory" at your boot option to
  570. disable memory resource controller and you can avoid overheads.
  571. (and lose benefits of memory resource controller)
  572. This config option also selects MM_OWNER config option, which
  573. could in turn add some fork/exit overhead.
  574. config CGROUP_MEM_RES_CTLR_SWAP
  575. bool "Memory Resource Controller Swap Extension"
  576. depends on CGROUP_MEM_RES_CTLR && SWAP
  577. help
  578. Add swap management feature to memory resource controller. When you
  579. enable this, you can limit mem+swap usage per cgroup. In other words,
  580. when you disable this, memory resource controller has no cares to
  581. usage of swap...a process can exhaust all of the swap. This extension
  582. is useful when you want to avoid exhaustion swap but this itself
  583. adds more overheads and consumes memory for remembering information.
  584. Especially if you use 32bit system or small memory system, please
  585. be careful about enabling this. When memory resource controller
  586. is disabled by boot option, this will be automatically disabled and
  587. there will be no overhead from this. Even when you set this config=y,
  588. if boot option "swapaccount=0" is set, swap will not be accounted.
  589. Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
  590. size is 4096bytes, 512k per 1Gbytes of swap.
  591. config CGROUP_MEM_RES_CTLR_SWAP_ENABLED
  592. bool "Memory Resource Controller Swap Extension enabled by default"
  593. depends on CGROUP_MEM_RES_CTLR_SWAP
  594. default y
  595. help
  596. Memory Resource Controller Swap Extension comes with its price in
  597. a bigger memory consumption. General purpose distribution kernels
  598. which want to enable the feature but keep it disabled by default
  599. and let the user enable it by swapaccount boot command line
  600. parameter should have this option unselected.
  601. For those who want to have the feature enabled by default should
  602. select this option (if, for some reason, they need to disable it
  603. then swapaccount=0 does the trick).
  604. config CGROUP_MEM_RES_CTLR_KMEM
  605. bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
  606. depends on CGROUP_MEM_RES_CTLR && EXPERIMENTAL
  607. default n
  608. help
  609. The Kernel Memory extension for Memory Resource Controller can limit
  610. the amount of memory used by kernel objects in the system. Those are
  611. fundamentally different from the entities handled by the standard
  612. Memory Controller, which are page-based, and can be swapped. Users of
  613. the kmem extension can use it to guarantee that no group of processes
  614. will ever exhaust kernel resources alone.
  615. config CGROUP_PERF
  616. bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
  617. depends on PERF_EVENTS && CGROUPS
  618. help
  619. This option extends the per-cpu mode to restrict monitoring to
  620. threads which belong to the cgroup specified and run on the
  621. designated cpu.
  622. Say N if unsure.
  623. menuconfig CGROUP_SCHED
  624. bool "Group CPU scheduler"
  625. default n
  626. help
  627. This feature lets CPU scheduler recognize task groups and control CPU
  628. bandwidth allocation to such task groups. It uses cgroups to group
  629. tasks.
  630. if CGROUP_SCHED
  631. config FAIR_GROUP_SCHED
  632. bool "Group scheduling for SCHED_OTHER"
  633. depends on CGROUP_SCHED
  634. default CGROUP_SCHED
  635. config CFS_BANDWIDTH
  636. bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
  637. depends on EXPERIMENTAL
  638. depends on FAIR_GROUP_SCHED
  639. default n
  640. help
  641. This option allows users to define CPU bandwidth rates (limits) for
  642. tasks running within the fair group scheduler. Groups with no limit
  643. set are considered to be unconstrained and will run with no
  644. restriction.
  645. See tip/Documentation/scheduler/sched-bwc.txt for more information.
  646. config RT_GROUP_SCHED
  647. bool "Group scheduling for SCHED_RR/FIFO"
  648. depends on EXPERIMENTAL
  649. depends on CGROUP_SCHED
  650. default n
  651. help
  652. This feature lets you explicitly allocate real CPU bandwidth
  653. to task groups. If enabled, it will also make it impossible to
  654. schedule realtime tasks for non-root users until you allocate
  655. realtime bandwidth for them.
  656. See Documentation/scheduler/sched-rt-group.txt for more information.
  657. endif #CGROUP_SCHED
  658. config BLK_CGROUP
  659. tristate "Block IO controller"
  660. depends on BLOCK
  661. default n
  662. ---help---
  663. Generic block IO controller cgroup interface. This is the common
  664. cgroup interface which should be used by various IO controlling
  665. policies.
  666. Currently, CFQ IO scheduler uses it to recognize task groups and
  667. control disk bandwidth allocation (proportional time slice allocation)
  668. to such task groups. It is also used by bio throttling logic in
  669. block layer to implement upper limit in IO rates on a device.
  670. This option only enables generic Block IO controller infrastructure.
  671. One needs to also enable actual IO controlling logic/policy. For
  672. enabling proportional weight division of disk bandwidth in CFQ, set
  673. CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
  674. CONFIG_BLK_DEV_THROTTLING=y.
  675. See Documentation/cgroups/blkio-controller.txt for more information.
  676. config DEBUG_BLK_CGROUP
  677. bool "Enable Block IO controller debugging"
  678. depends on BLK_CGROUP
  679. default n
  680. ---help---
  681. Enable some debugging help. Currently it exports additional stat
  682. files in a cgroup which can be useful for debugging.
  683. endif # CGROUPS
  684. config CHECKPOINT_RESTORE
  685. bool "Checkpoint/restore support" if EXPERT
  686. default n
  687. help
  688. Enables additional kernel features in a sake of checkpoint/restore.
  689. In particular it adds auxiliary prctl codes to setup process text,
  690. data and heap segment sizes, and a few additional /proc filesystem
  691. entries.
  692. If unsure, say N here.
  693. menuconfig NAMESPACES
  694. bool "Namespaces support" if EXPERT
  695. default !EXPERT
  696. help
  697. Provides the way to make tasks work with different objects using
  698. the same id. For example same IPC id may refer to different objects
  699. or same user id or pid may refer to different tasks when used in
  700. different namespaces.
  701. if NAMESPACES
  702. config UTS_NS
  703. bool "UTS namespace"
  704. default y
  705. help
  706. In this namespace tasks see different info provided with the
  707. uname() system call
  708. config IPC_NS
  709. bool "IPC namespace"
  710. depends on (SYSVIPC || POSIX_MQUEUE)
  711. default y
  712. help
  713. In this namespace tasks work with IPC ids which correspond to
  714. different IPC objects in different namespaces.
  715. config USER_NS
  716. bool "User namespace (EXPERIMENTAL)"
  717. depends on EXPERIMENTAL
  718. default y
  719. help
  720. This allows containers, i.e. vservers, to use user namespaces
  721. to provide different user info for different servers.
  722. If unsure, say N.
  723. config PID_NS
  724. bool "PID Namespaces"
  725. default y
  726. help
  727. Support process id namespaces. This allows having multiple
  728. processes with the same pid as long as they are in different
  729. pid namespaces. This is a building block of containers.
  730. config NET_NS
  731. bool "Network namespace"
  732. depends on NET
  733. default y
  734. help
  735. Allow user space to create what appear to be multiple instances
  736. of the network stack.
  737. endif # NAMESPACES
  738. config SCHED_AUTOGROUP
  739. bool "Automatic process group scheduling"
  740. select EVENTFD
  741. select CGROUPS
  742. select CGROUP_SCHED
  743. select FAIR_GROUP_SCHED
  744. help
  745. This option optimizes the scheduler for common desktop workloads by
  746. automatically creating and populating task groups. This separation
  747. of workloads isolates aggressive CPU burners (like build jobs) from
  748. desktop applications. Task group autogeneration is currently based
  749. upon task session.
  750. config MM_OWNER
  751. bool
  752. config SYSFS_DEPRECATED
  753. bool "Enable deprecated sysfs features to support old userspace tools"
  754. depends on SYSFS
  755. default n
  756. help
  757. This option adds code that switches the layout of the "block" class
  758. devices, to not show up in /sys/class/block/, but only in
  759. /sys/block/.
  760. This switch is only active when the sysfs.deprecated=1 boot option is
  761. passed or the SYSFS_DEPRECATED_V2 option is set.
  762. This option allows new kernels to run on old distributions and tools,
  763. which might get confused by /sys/class/block/. Since 2007/2008 all
  764. major distributions and tools handle this just fine.
  765. Recent distributions and userspace tools after 2009/2010 depend on
  766. the existence of /sys/class/block/, and will not work with this
  767. option enabled.
  768. Only if you are using a new kernel on an old distribution, you might
  769. need to say Y here.
  770. config SYSFS_DEPRECATED_V2
  771. bool "Enable deprecated sysfs features by default"
  772. default n
  773. depends on SYSFS
  774. depends on SYSFS_DEPRECATED
  775. help
  776. Enable deprecated sysfs by default.
  777. See the CONFIG_SYSFS_DEPRECATED option for more details about this
  778. option.
  779. Only if you are using a new kernel on an old distribution, you might
  780. need to say Y here. Even then, odds are you would not need it
  781. enabled, you can always pass the boot option if absolutely necessary.
  782. config RELAY
  783. bool "Kernel->user space relay support (formerly relayfs)"
  784. help
  785. This option enables support for relay interface support in
  786. certain file systems (such as debugfs).
  787. It is designed to provide an efficient mechanism for tools and
  788. facilities to relay large amounts of data from kernel space to
  789. user space.
  790. If unsure, say N.
  791. config BLK_DEV_INITRD
  792. bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
  793. depends on BROKEN || !FRV
  794. help
  795. The initial RAM filesystem is a ramfs which is loaded by the
  796. boot loader (loadlin or lilo) and that is mounted as root
  797. before the normal boot procedure. It is typically used to
  798. load modules needed to mount the "real" root file system,
  799. etc. See <file:Documentation/initrd.txt> for details.
  800. If RAM disk support (BLK_DEV_RAM) is also included, this
  801. also enables initial RAM disk (initrd) support and adds
  802. 15 Kbytes (more on some other architectures) to the kernel size.
  803. If unsure say Y.
  804. if BLK_DEV_INITRD
  805. source "usr/Kconfig"
  806. endif
  807. config CC_OPTIMIZE_FOR_SIZE
  808. bool "Optimize for size"
  809. help
  810. Enabling this option will pass "-Os" instead of "-O2" to gcc
  811. resulting in a smaller kernel.
  812. If unsure, say Y.
  813. config SYSCTL
  814. bool
  815. config ANON_INODES
  816. bool
  817. menuconfig EXPERT
  818. bool "Configure standard kernel features (expert users)"
  819. # Unhide debug options, to make the on-by-default options visible
  820. select DEBUG_KERNEL
  821. help
  822. This option allows certain base kernel options and settings
  823. to be disabled or tweaked. This is for specialized
  824. environments which can tolerate a "non-standard" kernel.
  825. Only use this if you really know what you are doing.
  826. config UID16
  827. bool "Enable 16-bit UID system calls" if EXPERT
  828. depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
  829. default y
  830. help
  831. This enables the legacy 16-bit UID syscall wrappers.
  832. config SYSCTL_SYSCALL
  833. bool "Sysctl syscall support" if EXPERT
  834. depends on PROC_SYSCTL
  835. default n
  836. select SYSCTL
  837. ---help---
  838. sys_sysctl uses binary paths that have been found challenging
  839. to properly maintain and use. The interface in /proc/sys
  840. using paths with ascii names is now the primary path to this
  841. information.
  842. Almost nothing using the binary sysctl interface so if you are
  843. trying to save some space it is probably safe to disable this,
  844. making your kernel marginally smaller.
  845. If unsure say N here.
  846. config KALLSYMS
  847. bool "Load all symbols for debugging/ksymoops" if EXPERT
  848. default y
  849. help
  850. Say Y here to let the kernel print out symbolic crash information and
  851. symbolic stack backtraces. This increases the size of the kernel
  852. somewhat, as all symbols have to be loaded into the kernel image.
  853. config KALLSYMS_ALL
  854. bool "Include all symbols in kallsyms"
  855. depends on DEBUG_KERNEL && KALLSYMS
  856. help
  857. Normally kallsyms only contains the symbols of functions for nicer
  858. OOPS messages and backtraces (i.e., symbols from the text and inittext
  859. sections). This is sufficient for most cases. And only in very rare
  860. cases (e.g., when a debugger is used) all symbols are required (e.g.,
  861. names of variables from the data sections, etc).
  862. This option makes sure that all symbols are loaded into the kernel
  863. image (i.e., symbols from all sections) in cost of increased kernel
  864. size (depending on the kernel configuration, it may be 300KiB or
  865. something like this).
  866. Say N unless you really need all symbols.
  867. config HOTPLUG
  868. bool "Support for hot-pluggable devices" if EXPERT
  869. default y
  870. help
  871. This option is provided for the case where no hotplug or uevent
  872. capabilities is wanted by the kernel. You should only consider
  873. disabling this option for embedded systems that do not use modules, a
  874. dynamic /dev tree, or dynamic device discovery. Just say Y.
  875. config PRINTK
  876. default y
  877. bool "Enable support for printk" if EXPERT
  878. help
  879. This option enables normal printk support. Removing it
  880. eliminates most of the message strings from the kernel image
  881. and makes the kernel more or less silent. As this makes it
  882. very difficult to diagnose system problems, saying N here is
  883. strongly discouraged.
  884. config BUG
  885. bool "BUG() support" if EXPERT
  886. default y
  887. help
  888. Disabling this option eliminates support for BUG and WARN, reducing
  889. the size of your kernel image and potentially quietly ignoring
  890. numerous fatal conditions. You should only consider disabling this
  891. option for embedded systems with no facilities for reporting errors.
  892. Just say Y.
  893. config ELF_CORE
  894. default y
  895. bool "Enable ELF core dumps" if EXPERT
  896. help
  897. Enable support for generating core dumps. Disabling saves about 4k.
  898. config PCSPKR_PLATFORM
  899. bool "Enable PC-Speaker support" if EXPERT
  900. depends on HAVE_PCSPKR_PLATFORM
  901. select I8253_LOCK
  902. default y
  903. help
  904. This option allows to disable the internal PC-Speaker
  905. support, saving some memory.
  906. config HAVE_PCSPKR_PLATFORM
  907. bool
  908. config BASE_FULL
  909. default y
  910. bool "Enable full-sized data structures for core" if EXPERT
  911. help
  912. Disabling this option reduces the size of miscellaneous core
  913. kernel data structures. This saves memory on small machines,
  914. but may reduce performance.
  915. config FUTEX
  916. bool "Enable futex support" if EXPERT
  917. default y
  918. select RT_MUTEXES
  919. help
  920. Disabling this option will cause the kernel to be built without
  921. support for "fast userspace mutexes". The resulting kernel may not
  922. run glibc-based applications correctly.
  923. config EPOLL
  924. bool "Enable eventpoll support" if EXPERT
  925. default y
  926. select ANON_INODES
  927. help
  928. Disabling this option will cause the kernel to be built without
  929. support for epoll family of system calls.
  930. config SIGNALFD
  931. bool "Enable signalfd() system call" if EXPERT
  932. select ANON_INODES
  933. default y
  934. help
  935. Enable the signalfd() system call that allows to receive signals
  936. on a file descriptor.
  937. If unsure, say Y.
  938. config TIMERFD
  939. bool "Enable timerfd() system call" if EXPERT
  940. select ANON_INODES
  941. default y
  942. help
  943. Enable the timerfd() system call that allows to receive timer
  944. events on a file descriptor.
  945. If unsure, say Y.
  946. config EVENTFD
  947. bool "Enable eventfd() system call" if EXPERT
  948. select ANON_INODES
  949. default y
  950. help
  951. Enable the eventfd() system call that allows to receive both
  952. kernel notification (ie. KAIO) or userspace notifications.
  953. If unsure, say Y.
  954. config SHMEM
  955. bool "Use full shmem filesystem" if EXPERT
  956. default y
  957. depends on MMU
  958. help
  959. The shmem is an internal filesystem used to manage shared memory.
  960. It is backed by swap and manages resource limits. It is also exported
  961. to userspace as tmpfs if TMPFS is enabled. Disabling this
  962. option replaces shmem and tmpfs with the much simpler ramfs code,
  963. which may be appropriate on small systems without swap.
  964. config AIO
  965. bool "Enable AIO support" if EXPERT
  966. default y
  967. help
  968. This option enables POSIX asynchronous I/O which may by used
  969. by some high performance threaded applications. Disabling
  970. this option saves about 7k.
  971. config EMBEDDED
  972. bool "Embedded system"
  973. select EXPERT
  974. help
  975. This option should be enabled if compiling the kernel for
  976. an embedded system so certain expert options are available
  977. for configuration.
  978. config HAVE_PERF_EVENTS
  979. bool
  980. help
  981. See tools/perf/design.txt for details.
  982. config PERF_USE_VMALLOC
  983. bool
  984. help
  985. See tools/perf/design.txt for details
  986. menu "Kernel Performance Events And Counters"
  987. config PERF_EVENTS
  988. bool "Kernel performance events and counters"
  989. default y if (PROFILING || PERF_COUNTERS)
  990. depends on HAVE_PERF_EVENTS
  991. select ANON_INODES
  992. select IRQ_WORK
  993. help
  994. Enable kernel support for various performance events provided
  995. by software and hardware.
  996. Software events are supported either built-in or via the
  997. use of generic tracepoints.
  998. Most modern CPUs support performance events via performance
  999. counter registers. These registers count the number of certain
  1000. types of hw events: such as instructions executed, cachemisses
  1001. suffered, or branches mis-predicted - without slowing down the
  1002. kernel or applications. These registers can also trigger interrupts
  1003. when a threshold number of events have passed - and can thus be
  1004. used to profile the code that runs on that CPU.
  1005. The Linux Performance Event subsystem provides an abstraction of
  1006. these software and hardware event capabilities, available via a
  1007. system call and used by the "perf" utility in tools/perf/. It
  1008. provides per task and per CPU counters, and it provides event
  1009. capabilities on top of those.
  1010. Say Y if unsure.
  1011. config PERF_COUNTERS
  1012. bool "Kernel performance counters (old config option)"
  1013. depends on HAVE_PERF_EVENTS
  1014. help
  1015. This config has been obsoleted by the PERF_EVENTS
  1016. config option - please see that one for details.
  1017. It has no effect on the kernel whether you enable
  1018. it or not, it is a compatibility placeholder.
  1019. Say N if unsure.
  1020. config DEBUG_PERF_USE_VMALLOC
  1021. default n
  1022. bool "Debug: use vmalloc to back perf mmap() buffers"
  1023. depends on PERF_EVENTS && DEBUG_KERNEL
  1024. select PERF_USE_VMALLOC
  1025. help
  1026. Use vmalloc memory to back perf mmap() buffers.
  1027. Mostly useful for debugging the vmalloc code on platforms
  1028. that don't require it.
  1029. Say N if unsure.
  1030. endmenu
  1031. config VM_EVENT_COUNTERS
  1032. default y
  1033. bool "Enable VM event counters for /proc/vmstat" if EXPERT
  1034. help
  1035. VM event counters are needed for event counts to be shown.
  1036. This option allows the disabling of the VM event counters
  1037. on EXPERT systems. /proc/vmstat will only show page counts
  1038. if VM event counters are disabled.
  1039. config PCI_QUIRKS
  1040. default y
  1041. bool "Enable PCI quirk workarounds" if EXPERT
  1042. depends on PCI
  1043. help
  1044. This enables workarounds for various PCI chipset
  1045. bugs/quirks. Disable this only if your target machine is
  1046. unaffected by PCI quirks.
  1047. config SLUB_DEBUG
  1048. default y
  1049. bool "Enable SLUB debugging support" if EXPERT
  1050. depends on SLUB && SYSFS
  1051. help
  1052. SLUB has extensive debug support features. Disabling these can
  1053. result in significant savings in code size. This also disables
  1054. SLUB sysfs support. /sys/slab will not exist and there will be
  1055. no support for cache validation etc.
  1056. config COMPAT_BRK
  1057. bool "Disable heap randomization"
  1058. default y
  1059. help
  1060. Randomizing heap placement makes heap exploits harder, but it
  1061. also breaks ancient binaries (including anything libc5 based).
  1062. This option changes the bootup default to heap randomization
  1063. disabled, and can be overridden at runtime by setting
  1064. /proc/sys/kernel/randomize_va_space to 2.
  1065. On non-ancient distros (post-2000 ones) N is usually a safe choice.
  1066. choice
  1067. prompt "Choose SLAB allocator"
  1068. default SLUB
  1069. help
  1070. This option allows to select a slab allocator.
  1071. config SLAB
  1072. bool "SLAB"
  1073. help
  1074. The regular slab allocator that is established and known to work
  1075. well in all environments. It organizes cache hot objects in
  1076. per cpu and per node queues.
  1077. config SLUB
  1078. bool "SLUB (Unqueued Allocator)"
  1079. help
  1080. SLUB is a slab allocator that minimizes cache line usage
  1081. instead of managing queues of cached objects (SLAB approach).
  1082. Per cpu caching is realized using slabs of objects instead
  1083. of queues of objects. SLUB can use memory efficiently
  1084. and has enhanced diagnostics. SLUB is the default choice for
  1085. a slab allocator.
  1086. config SLOB
  1087. depends on EXPERT
  1088. bool "SLOB (Simple Allocator)"
  1089. help
  1090. SLOB replaces the stock allocator with a drastically simpler
  1091. allocator. SLOB is generally more space efficient but
  1092. does not perform as well on large systems.
  1093. endchoice
  1094. config MMAP_ALLOW_UNINITIALIZED
  1095. bool "Allow mmapped anonymous memory to be uninitialized"
  1096. depends on EXPERT && !MMU
  1097. default n
  1098. help
  1099. Normally, and according to the Linux spec, anonymous memory obtained
  1100. from mmap() has it's contents cleared before it is passed to
  1101. userspace. Enabling this config option allows you to request that
  1102. mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
  1103. providing a huge performance boost. If this option is not enabled,
  1104. then the flag will be ignored.
  1105. This is taken advantage of by uClibc's malloc(), and also by
  1106. ELF-FDPIC binfmt's brk and stack allocator.
  1107. Because of the obvious security issues, this option should only be
  1108. enabled on embedded devices where you control what is run in
  1109. userspace. Since that isn't generally a problem on no-MMU systems,
  1110. it is normally safe to say Y here.
  1111. See Documentation/nommu-mmap.txt for more information.
  1112. config PROFILING
  1113. bool "Profiling support"
  1114. help
  1115. Say Y here to enable the extended profiling support mechanisms used
  1116. by profilers such as OProfile.
  1117. #
  1118. # Place an empty function call at each tracepoint site. Can be
  1119. # dynamically changed for a probe function.
  1120. #
  1121. config TRACEPOINTS
  1122. bool
  1123. source "arch/Kconfig"
  1124. endmenu # General setup
  1125. config HAVE_GENERIC_DMA_COHERENT
  1126. bool
  1127. default n
  1128. config SLABINFO
  1129. bool
  1130. depends on PROC_FS
  1131. depends on SLAB || SLUB_DEBUG
  1132. default y
  1133. config RT_MUTEXES
  1134. boolean
  1135. config BASE_SMALL
  1136. int
  1137. default 0 if BASE_FULL
  1138. default 1 if !BASE_FULL
  1139. menuconfig MODULES
  1140. bool "Enable loadable module support"
  1141. help
  1142. Kernel modules are small pieces of compiled code which can
  1143. be inserted in the running kernel, rather than being
  1144. permanently built into the kernel. You use the "modprobe"
  1145. tool to add (and sometimes remove) them. If you say Y here,
  1146. many parts of the kernel can be built as modules (by
  1147. answering M instead of Y where indicated): this is most
  1148. useful for infrequently used options which are not required
  1149. for booting. For more information, see the man pages for
  1150. modprobe, lsmod, modinfo, insmod and rmmod.
  1151. If you say Y here, you will need to run "make
  1152. modules_install" to put the modules under /lib/modules/
  1153. where modprobe can find them (you may need to be root to do
  1154. this).
  1155. If unsure, say Y.
  1156. if MODULES
  1157. config MODULE_FORCE_LOAD
  1158. bool "Forced module loading"
  1159. default n
  1160. help
  1161. Allow loading of modules without version information (ie. modprobe
  1162. --force). Forced module loading sets the 'F' (forced) taint flag and
  1163. is usually a really bad idea.
  1164. config MODULE_UNLOAD
  1165. bool "Module unloading"
  1166. help
  1167. Without this option you will not be able to unload any
  1168. modules (note that some modules may not be unloadable
  1169. anyway), which makes your kernel smaller, faster
  1170. and simpler. If unsure, say Y.
  1171. config MODULE_FORCE_UNLOAD
  1172. bool "Forced module unloading"
  1173. depends on MODULE_UNLOAD && EXPERIMENTAL
  1174. help
  1175. This option allows you to force a module to unload, even if the
  1176. kernel believes it is unsafe: the kernel will remove the module
  1177. without waiting for anyone to stop using it (using the -f option to
  1178. rmmod). This is mainly for kernel developers and desperate users.
  1179. If unsure, say N.
  1180. config MODVERSIONS
  1181. bool "Module versioning support"
  1182. help
  1183. Usually, you have to use modules compiled with your kernel.
  1184. Saying Y here makes it sometimes possible to use modules
  1185. compiled for different kernels, by adding enough information
  1186. to the modules to (hopefully) spot any changes which would
  1187. make them incompatible with the kernel you are running. If
  1188. unsure, say N.
  1189. config MODULE_SRCVERSION_ALL
  1190. bool "Source checksum for all modules"
  1191. help
  1192. Modules which contain a MODULE_VERSION get an extra "srcversion"
  1193. field inserted into their modinfo section, which contains a
  1194. sum of the source files which made it. This helps maintainers
  1195. see exactly which source was used to build a module (since
  1196. others sometimes change the module source without updating
  1197. the version). With this option, such a "srcversion" field
  1198. will be created for all modules. If unsure, say N.
  1199. endif # MODULES
  1200. config INIT_ALL_POSSIBLE
  1201. bool
  1202. help
  1203. Back when each arch used to define their own cpu_online_mask and
  1204. cpu_possible_mask, some of them chose to initialize cpu_possible_mask
  1205. with all 1s, and others with all 0s. When they were centralised,
  1206. it was better to provide this option than to break all the archs
  1207. and have several arch maintainers pursuing me down dark alleys.
  1208. config STOP_MACHINE
  1209. bool
  1210. default y
  1211. depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
  1212. help
  1213. Need stop_machine() primitive.
  1214. source "block/Kconfig"
  1215. config PREEMPT_NOTIFIERS
  1216. bool
  1217. config PADATA
  1218. depends on SMP
  1219. bool
  1220. source "kernel/Kconfig.locks"