Kconfig 53 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. config BUILDTIME_EXTABLE_SORT
  25. bool
  26. menu "General setup"
  27. config EXPERIMENTAL
  28. bool "Prompt for development and/or incomplete code/drivers"
  29. ---help---
  30. Some of the various things that Linux supports (such as network
  31. drivers, file systems, network protocols, etc.) can be in a state
  32. of development where the functionality, stability, or the level of
  33. testing is not yet high enough for general use. This is usually
  34. known as the "alpha-test" phase among developers. If a feature is
  35. currently in alpha-test, then the developers usually discourage
  36. uninformed widespread use of this feature by the general public to
  37. avoid "Why doesn't this work?" type mail messages. However, active
  38. testing and use of these systems is welcomed. Just be aware that it
  39. may not meet the normal level of reliability or it may fail to work
  40. in some special cases. Detailed bug reports from people familiar
  41. with the kernel internals are usually welcomed by the developers
  42. (before submitting bug reports, please read the documents
  43. <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
  44. <file:Documentation/BUG-HUNTING>, and
  45. <file:Documentation/oops-tracing.txt> in the kernel source).
  46. This option will also make obsoleted drivers available. These are
  47. drivers that have been replaced by something else, and/or are
  48. scheduled to be removed in a future kernel release.
  49. Unless you intend to help test and develop a feature or driver that
  50. falls into this category, or you have a situation that requires
  51. using these features, you should probably say N here, which will
  52. cause the configurator to present you with fewer choices. If
  53. you say Y here, you will be offered the choice of using features or
  54. drivers that are currently considered to be in the alpha-test phase.
  55. config BROKEN
  56. bool
  57. config BROKEN_ON_SMP
  58. bool
  59. depends on BROKEN || !SMP
  60. default y
  61. config INIT_ENV_ARG_LIMIT
  62. int
  63. default 32 if !UML
  64. default 128 if UML
  65. help
  66. Maximum of each of the number of arguments and environment
  67. variables passed to init from the kernel command line.
  68. config CROSS_COMPILE
  69. string "Cross-compiler tool prefix"
  70. help
  71. Same as running 'make CROSS_COMPILE=prefix-' but stored for
  72. default make runs in this kernel build directory. You don't
  73. need to set this unless you want the configured kernel build
  74. directory to select the cross-compiler automatically.
  75. config LOCALVERSION
  76. string "Local version - append to kernel release"
  77. help
  78. Append an extra string to the end of your kernel version.
  79. This will show up when you type uname, for example.
  80. The string you set here will be appended after the contents of
  81. any files with a filename matching localversion* in your
  82. object and source tree, in that order. Your total string can
  83. be a maximum of 64 characters.
  84. config LOCALVERSION_AUTO
  85. bool "Automatically append version information to the version string"
  86. default y
  87. help
  88. This will try to automatically determine if the current tree is a
  89. release tree by looking for git tags that belong to the current
  90. top of tree revision.
  91. A string of the format -gxxxxxxxx will be added to the localversion
  92. if a git-based tree is found. The string generated by this will be
  93. appended after any matching localversion* files, and after the value
  94. set in CONFIG_LOCALVERSION.
  95. (The actual string used here is the first eight characters produced
  96. by running the command:
  97. $ git rev-parse --verify HEAD
  98. which is done within the script "scripts/setlocalversion".)
  99. config HAVE_KERNEL_GZIP
  100. bool
  101. config HAVE_KERNEL_BZIP2
  102. bool
  103. config HAVE_KERNEL_LZMA
  104. bool
  105. config HAVE_KERNEL_XZ
  106. bool
  107. config HAVE_KERNEL_LZO
  108. bool
  109. choice
  110. prompt "Kernel compression mode"
  111. default KERNEL_GZIP
  112. depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
  113. help
  114. The linux kernel is a kind of self-extracting executable.
  115. Several compression algorithms are available, which differ
  116. in efficiency, compression and decompression speed.
  117. Compression speed is only relevant when building a kernel.
  118. Decompression speed is relevant at each boot.
  119. If you have any problems with bzip2 or lzma compressed
  120. kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
  121. version of this functionality (bzip2 only), for 2.4, was
  122. supplied by Christian Ludwig)
  123. High compression options are mostly useful for users, who
  124. are low on disk space (embedded systems), but for whom ram
  125. size matters less.
  126. If in doubt, select 'gzip'
  127. config KERNEL_GZIP
  128. bool "Gzip"
  129. depends on HAVE_KERNEL_GZIP
  130. help
  131. The old and tried gzip compression. It provides a good balance
  132. between compression ratio and decompression speed.
  133. config KERNEL_BZIP2
  134. bool "Bzip2"
  135. depends on HAVE_KERNEL_BZIP2
  136. help
  137. Its compression ratio and speed is intermediate.
  138. Decompression speed is slowest among the choices. The kernel
  139. size is about 10% smaller with bzip2, in comparison to gzip.
  140. Bzip2 uses a large amount of memory. For modern kernels you
  141. will need at least 8MB RAM or more for booting.
  142. config KERNEL_LZMA
  143. bool "LZMA"
  144. depends on HAVE_KERNEL_LZMA
  145. help
  146. This compression algorithm's ratio is best. Decompression speed
  147. is between gzip and bzip2. Compression is slowest.
  148. The kernel size is about 33% smaller with LZMA in comparison to gzip.
  149. config KERNEL_XZ
  150. bool "XZ"
  151. depends on HAVE_KERNEL_XZ
  152. help
  153. XZ uses the LZMA2 algorithm and instruction set specific
  154. BCJ filters which can improve compression ratio of executable
  155. code. The size of the kernel is about 30% smaller with XZ in
  156. comparison to gzip. On architectures for which there is a BCJ
  157. filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
  158. will create a few percent smaller kernel than plain LZMA.
  159. The speed is about the same as with LZMA: The decompression
  160. speed of XZ is better than that of bzip2 but worse than gzip
  161. and LZO. Compression is slow.
  162. config KERNEL_LZO
  163. bool "LZO"
  164. depends on HAVE_KERNEL_LZO
  165. help
  166. Its compression ratio is the poorest among the choices. The kernel
  167. size is about 10% bigger than gzip; however its speed
  168. (both compression and decompression) is the fastest.
  169. endchoice
  170. config DEFAULT_HOSTNAME
  171. string "Default hostname"
  172. default "(none)"
  173. help
  174. This option determines the default system hostname before userspace
  175. calls sethostname(2). The kernel traditionally uses "(none)" here,
  176. but you may wish to use a different default here to make a minimal
  177. system more usable with less configuration.
  178. config SWAP
  179. bool "Support for paging of anonymous memory (swap)"
  180. depends on MMU && BLOCK
  181. default y
  182. help
  183. This option allows you to choose whether you want to have support
  184. for so called swap devices or swap files in your kernel that are
  185. used to provide more virtual memory than the actual RAM present
  186. in your computer. If unsure say Y.
  187. config SYSVIPC
  188. bool "System V IPC"
  189. ---help---
  190. Inter Process Communication is a suite of library functions and
  191. system calls which let processes (running programs) synchronize and
  192. exchange information. It is generally considered to be a good thing,
  193. and some programs won't run unless you say Y here. In particular, if
  194. you want to run the DOS emulator dosemu under Linux (read the
  195. DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
  196. you'll need to say Y here.
  197. You can find documentation about IPC with "info ipc" and also in
  198. section 6.4 of the Linux Programmer's Guide, available from
  199. <http://www.tldp.org/guides.html>.
  200. config SYSVIPC_SYSCTL
  201. bool
  202. depends on SYSVIPC
  203. depends on SYSCTL
  204. default y
  205. config POSIX_MQUEUE
  206. bool "POSIX Message Queues"
  207. depends on NET && EXPERIMENTAL
  208. ---help---
  209. POSIX variant of message queues is a part of IPC. In POSIX message
  210. queues every message has a priority which decides about succession
  211. of receiving it by a process. If you want to compile and run
  212. programs written e.g. for Solaris with use of its POSIX message
  213. queues (functions mq_*) say Y here.
  214. POSIX message queues are visible as a filesystem called 'mqueue'
  215. and can be mounted somewhere if you want to do filesystem
  216. operations on message queues.
  217. If unsure, say Y.
  218. config POSIX_MQUEUE_SYSCTL
  219. bool
  220. depends on POSIX_MQUEUE
  221. depends on SYSCTL
  222. default y
  223. config FHANDLE
  224. bool "open by fhandle syscalls"
  225. select EXPORTFS
  226. help
  227. If you say Y here, a user level program will be able to map
  228. file names to handle and then later use the handle for
  229. different file system operations. This is useful in implementing
  230. userspace file servers, which now track files using handles instead
  231. of names. The handle would remain the same even if file names
  232. get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
  233. syscalls.
  234. config AUDIT
  235. bool "Auditing support"
  236. depends on NET
  237. help
  238. Enable auditing infrastructure that can be used with another
  239. kernel subsystem, such as SELinux (which requires this for
  240. logging of avc messages output). Does not do system-call
  241. auditing without CONFIG_AUDITSYSCALL.
  242. config AUDITSYSCALL
  243. bool "Enable system-call auditing support"
  244. depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || (ARM && AEABI && !OABI_COMPAT))
  245. default y if SECURITY_SELINUX
  246. help
  247. Enable low-overhead system-call auditing infrastructure that
  248. can be used independently or with another kernel subsystem,
  249. such as SELinux.
  250. config AUDIT_WATCH
  251. def_bool y
  252. depends on AUDITSYSCALL
  253. select FSNOTIFY
  254. config AUDIT_TREE
  255. def_bool y
  256. depends on AUDITSYSCALL
  257. select FSNOTIFY
  258. config AUDIT_LOGINUID_IMMUTABLE
  259. bool "Make audit loginuid immutable"
  260. depends on AUDIT
  261. help
  262. The config option toggles if a task setting its loginuid requires
  263. CAP_SYS_AUDITCONTROL or if that task should require no special permissions
  264. but should instead only allow setting its loginuid if it was never
  265. previously set. On systems which use systemd or a similar central
  266. process to restart login services this should be set to true. On older
  267. systems in which an admin would typically have to directly stop and
  268. start processes this should be set to false. Setting this to true allows
  269. one to drop potentially dangerous capabilites from the login tasks,
  270. but may not be backwards compatible with older init systems.
  271. source "kernel/irq/Kconfig"
  272. source "kernel/time/Kconfig"
  273. menu "CPU/Task time and stats accounting"
  274. choice
  275. prompt "Cputime accounting"
  276. default TICK_CPU_ACCOUNTING if !PPC64
  277. default VIRT_CPU_ACCOUNTING if PPC64
  278. # Kind of a stub config for the pure tick based cputime accounting
  279. config TICK_CPU_ACCOUNTING
  280. bool "Simple tick based cputime accounting"
  281. depends on !S390
  282. help
  283. This is the basic tick based cputime accounting that maintains
  284. statistics about user, system and idle time spent on per jiffies
  285. granularity.
  286. If unsure, say Y.
  287. config VIRT_CPU_ACCOUNTING
  288. bool "Deterministic task and CPU time accounting"
  289. depends on HAVE_VIRT_CPU_ACCOUNTING
  290. help
  291. Select this option to enable more accurate task and CPU time
  292. accounting. This is done by reading a CPU counter on each
  293. kernel entry and exit and on transitions within the kernel
  294. between system, softirq and hardirq state, so there is a
  295. small performance impact. In the case of s390 or IBM POWER > 5,
  296. this also enables accounting of stolen time on logically-partitioned
  297. systems.
  298. config IRQ_TIME_ACCOUNTING
  299. bool "Fine granularity task level IRQ time accounting"
  300. depends on HAVE_IRQ_TIME_ACCOUNTING
  301. help
  302. Select this option to enable fine granularity task irq time
  303. accounting. This is done by reading a timestamp on each
  304. transitions between softirq and hardirq state, so there can be a
  305. small performance impact.
  306. If in doubt, say N here.
  307. endchoice
  308. config BSD_PROCESS_ACCT
  309. bool "BSD Process Accounting"
  310. help
  311. If you say Y here, a user level program will be able to instruct the
  312. kernel (via a special system call) to write process accounting
  313. information to a file: whenever a process exits, information about
  314. that process will be appended to the file by the kernel. The
  315. information includes things such as creation time, owning user,
  316. command name, memory usage, controlling terminal etc. (the complete
  317. list is in the struct acct in <file:include/linux/acct.h>). It is
  318. up to the user level program to do useful things with this
  319. information. This is generally a good idea, so say Y.
  320. config BSD_PROCESS_ACCT_V3
  321. bool "BSD Process Accounting version 3 file format"
  322. depends on BSD_PROCESS_ACCT
  323. default n
  324. help
  325. If you say Y here, the process accounting information is written
  326. in a new file format that also logs the process IDs of each
  327. process and it's parent. Note that this file format is incompatible
  328. with previous v0/v1/v2 file formats, so you will need updated tools
  329. for processing it. A preliminary version of these tools is available
  330. at <http://www.gnu.org/software/acct/>.
  331. config TASKSTATS
  332. bool "Export task/process statistics through netlink (EXPERIMENTAL)"
  333. depends on NET
  334. default n
  335. help
  336. Export selected statistics for tasks/processes through the
  337. generic netlink interface. Unlike BSD process accounting, the
  338. statistics are available during the lifetime of tasks/processes as
  339. responses to commands. Like BSD accounting, they are sent to user
  340. space on task exit.
  341. Say N if unsure.
  342. config TASK_DELAY_ACCT
  343. bool "Enable per-task delay accounting (EXPERIMENTAL)"
  344. depends on TASKSTATS
  345. help
  346. Collect information on time spent by a task waiting for system
  347. resources like cpu, synchronous block I/O completion and swapping
  348. in pages. Such statistics can help in setting a task's priorities
  349. relative to other tasks for cpu, io, rss limits etc.
  350. Say N if unsure.
  351. config TASK_XACCT
  352. bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
  353. depends on TASKSTATS
  354. help
  355. Collect extended task accounting data and send the data
  356. to userland for processing over the taskstats interface.
  357. Say N if unsure.
  358. config TASK_IO_ACCOUNTING
  359. bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
  360. depends on TASK_XACCT
  361. help
  362. Collect information on the number of bytes of storage I/O which this
  363. task has caused.
  364. Say N if unsure.
  365. endmenu # "CPU/Task time and stats accounting"
  366. menu "RCU Subsystem"
  367. choice
  368. prompt "RCU Implementation"
  369. default TREE_RCU
  370. config TREE_RCU
  371. bool "Tree-based hierarchical RCU"
  372. depends on !PREEMPT && SMP
  373. help
  374. This option selects the RCU implementation that is
  375. designed for very large SMP system with hundreds or
  376. thousands of CPUs. It also scales down nicely to
  377. smaller systems.
  378. config TREE_PREEMPT_RCU
  379. bool "Preemptible tree-based hierarchical RCU"
  380. depends on PREEMPT && SMP
  381. help
  382. This option selects the RCU implementation that is
  383. designed for very large SMP systems with hundreds or
  384. thousands of CPUs, but for which real-time response
  385. is also required. It also scales down nicely to
  386. smaller systems.
  387. config TINY_RCU
  388. bool "UP-only small-memory-footprint RCU"
  389. depends on !PREEMPT && !SMP
  390. help
  391. This option selects the RCU implementation that is
  392. designed for UP systems from which real-time response
  393. is not required. This option greatly reduces the
  394. memory footprint of RCU.
  395. config TINY_PREEMPT_RCU
  396. bool "Preemptible UP-only small-memory-footprint RCU"
  397. depends on PREEMPT && !SMP
  398. help
  399. This option selects the RCU implementation that is designed
  400. for real-time UP systems. This option greatly reduces the
  401. memory footprint of RCU.
  402. endchoice
  403. config PREEMPT_RCU
  404. def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
  405. help
  406. This option enables preemptible-RCU code that is common between
  407. the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
  408. config RCU_USER_QS
  409. bool "Consider userspace as in RCU extended quiescent state"
  410. depends on HAVE_RCU_USER_QS && SMP
  411. help
  412. This option sets hooks on kernel / userspace boundaries and
  413. puts RCU in extended quiescent state when the CPU runs in
  414. userspace. It means that when a CPU runs in userspace, it is
  415. excluded from the global RCU state machine and thus doesn't
  416. to keep the timer tick on for RCU.
  417. Unless you want to hack and help the development of the full
  418. tickless feature, you shouldn't enable this option. It adds
  419. unnecessary overhead.
  420. If unsure say N
  421. config RCU_USER_QS_FORCE
  422. bool "Force userspace extended QS by default"
  423. depends on RCU_USER_QS
  424. help
  425. Set the hooks in user/kernel boundaries by default in order to
  426. test this feature that treats userspace as an extended quiescent
  427. state until we have a real user like a full adaptive nohz option.
  428. Unless you want to hack and help the development of the full
  429. tickless feature, you shouldn't enable this option. It adds
  430. unnecessary overhead.
  431. If unsure say N
  432. config RCU_FANOUT
  433. int "Tree-based hierarchical RCU fanout value"
  434. range 2 64 if 64BIT
  435. range 2 32 if !64BIT
  436. depends on TREE_RCU || TREE_PREEMPT_RCU
  437. default 64 if 64BIT
  438. default 32 if !64BIT
  439. help
  440. This option controls the fanout of hierarchical implementations
  441. of RCU, allowing RCU to work efficiently on machines with
  442. large numbers of CPUs. This value must be at least the fourth
  443. root of NR_CPUS, which allows NR_CPUS to be insanely large.
  444. The default value of RCU_FANOUT should be used for production
  445. systems, but if you are stress-testing the RCU implementation
  446. itself, small RCU_FANOUT values allow you to test large-system
  447. code paths on small(er) systems.
  448. Select a specific number if testing RCU itself.
  449. Take the default if unsure.
  450. config RCU_FANOUT_LEAF
  451. int "Tree-based hierarchical RCU leaf-level fanout value"
  452. range 2 RCU_FANOUT if 64BIT
  453. range 2 RCU_FANOUT if !64BIT
  454. depends on TREE_RCU || TREE_PREEMPT_RCU
  455. default 16
  456. help
  457. This option controls the leaf-level fanout of hierarchical
  458. implementations of RCU, and allows trading off cache misses
  459. against lock contention. Systems that synchronize their
  460. scheduling-clock interrupts for energy-efficiency reasons will
  461. want the default because the smaller leaf-level fanout keeps
  462. lock contention levels acceptably low. Very large systems
  463. (hundreds or thousands of CPUs) will instead want to set this
  464. value to the maximum value possible in order to reduce the
  465. number of cache misses incurred during RCU's grace-period
  466. initialization. These systems tend to run CPU-bound, and thus
  467. are not helped by synchronized interrupts, and thus tend to
  468. skew them, which reduces lock contention enough that large
  469. leaf-level fanouts work well.
  470. Select a specific number if testing RCU itself.
  471. Select the maximum permissible value for large systems.
  472. Take the default if unsure.
  473. config RCU_FANOUT_EXACT
  474. bool "Disable tree-based hierarchical RCU auto-balancing"
  475. depends on TREE_RCU || TREE_PREEMPT_RCU
  476. default n
  477. help
  478. This option forces use of the exact RCU_FANOUT value specified,
  479. regardless of imbalances in the hierarchy. This is useful for
  480. testing RCU itself, and might one day be useful on systems with
  481. strong NUMA behavior.
  482. Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
  483. Say N if unsure.
  484. config RCU_FAST_NO_HZ
  485. bool "Accelerate last non-dyntick-idle CPU's grace periods"
  486. depends on NO_HZ && SMP
  487. default n
  488. help
  489. This option causes RCU to attempt to accelerate grace periods
  490. in order to allow CPUs to enter dynticks-idle state more
  491. quickly. On the other hand, this option increases the overhead
  492. of the dynticks-idle checking, particularly on systems with
  493. large numbers of CPUs.
  494. Say Y if energy efficiency is critically important, particularly
  495. if you have relatively few CPUs.
  496. Say N if you are unsure.
  497. config TREE_RCU_TRACE
  498. def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
  499. select DEBUG_FS
  500. help
  501. This option provides tracing for the TREE_RCU and
  502. TREE_PREEMPT_RCU implementations, permitting Makefile to
  503. trivially select kernel/rcutree_trace.c.
  504. config RCU_BOOST
  505. bool "Enable RCU priority boosting"
  506. depends on RT_MUTEXES && PREEMPT_RCU
  507. default n
  508. help
  509. This option boosts the priority of preempted RCU readers that
  510. block the current preemptible RCU grace period for too long.
  511. This option also prevents heavy loads from blocking RCU
  512. callback invocation for all flavors of RCU.
  513. Say Y here if you are working with real-time apps or heavy loads
  514. Say N here if you are unsure.
  515. config RCU_BOOST_PRIO
  516. int "Real-time priority to boost RCU readers to"
  517. range 1 99
  518. depends on RCU_BOOST
  519. default 1
  520. help
  521. This option specifies the real-time priority to which long-term
  522. preempted RCU readers are to be boosted. If you are working
  523. with a real-time application that has one or more CPU-bound
  524. threads running at a real-time priority level, you should set
  525. RCU_BOOST_PRIO to a priority higher then the highest-priority
  526. real-time CPU-bound thread. The default RCU_BOOST_PRIO value
  527. of 1 is appropriate in the common case, which is real-time
  528. applications that do not have any CPU-bound threads.
  529. Some real-time applications might not have a single real-time
  530. thread that saturates a given CPU, but instead might have
  531. multiple real-time threads that, taken together, fully utilize
  532. that CPU. In this case, you should set RCU_BOOST_PRIO to
  533. a priority higher than the lowest-priority thread that is
  534. conspiring to prevent the CPU from running any non-real-time
  535. tasks. For example, if one thread at priority 10 and another
  536. thread at priority 5 are between themselves fully consuming
  537. the CPU time on a given CPU, then RCU_BOOST_PRIO should be
  538. set to priority 6 or higher.
  539. Specify the real-time priority, or take the default if unsure.
  540. config RCU_BOOST_DELAY
  541. int "Milliseconds to delay boosting after RCU grace-period start"
  542. range 0 3000
  543. depends on RCU_BOOST
  544. default 500
  545. help
  546. This option specifies the time to wait after the beginning of
  547. a given grace period before priority-boosting preempted RCU
  548. readers blocking that grace period. Note that any RCU reader
  549. blocking an expedited RCU grace period is boosted immediately.
  550. Accept the default if unsure.
  551. endmenu # "RCU Subsystem"
  552. config IKCONFIG
  553. tristate "Kernel .config support"
  554. ---help---
  555. This option enables the complete Linux kernel ".config" file
  556. contents to be saved in the kernel. It provides documentation
  557. of which kernel options are used in a running kernel or in an
  558. on-disk kernel. This information can be extracted from the kernel
  559. image file with the script scripts/extract-ikconfig and used as
  560. input to rebuild the current kernel or to build another kernel.
  561. It can also be extracted from a running kernel by reading
  562. /proc/config.gz if enabled (below).
  563. config IKCONFIG_PROC
  564. bool "Enable access to .config through /proc/config.gz"
  565. depends on IKCONFIG && PROC_FS
  566. ---help---
  567. This option enables access to the kernel configuration file
  568. through /proc/config.gz.
  569. config LOG_BUF_SHIFT
  570. int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
  571. range 12 21
  572. default 17
  573. help
  574. Select kernel log buffer size as a power of 2.
  575. Examples:
  576. 17 => 128 KB
  577. 16 => 64 KB
  578. 15 => 32 KB
  579. 14 => 16 KB
  580. 13 => 8 KB
  581. 12 => 4 KB
  582. #
  583. # Architectures with an unreliable sched_clock() should select this:
  584. #
  585. config HAVE_UNSTABLE_SCHED_CLOCK
  586. bool
  587. menuconfig CGROUPS
  588. boolean "Control Group support"
  589. depends on EVENTFD
  590. help
  591. This option adds support for grouping sets of processes together, for
  592. use with process control subsystems such as Cpusets, CFS, memory
  593. controls or device isolation.
  594. See
  595. - Documentation/scheduler/sched-design-CFS.txt (CFS)
  596. - Documentation/cgroups/ (features for grouping, isolation
  597. and resource control)
  598. Say N if unsure.
  599. if CGROUPS
  600. config CGROUP_DEBUG
  601. bool "Example debug cgroup subsystem"
  602. default n
  603. help
  604. This option enables a simple cgroup subsystem that
  605. exports useful debugging information about the cgroups
  606. framework.
  607. Say N if unsure.
  608. config CGROUP_FREEZER
  609. bool "Freezer cgroup subsystem"
  610. help
  611. Provides a way to freeze and unfreeze all tasks in a
  612. cgroup.
  613. config CGROUP_DEVICE
  614. bool "Device controller for cgroups"
  615. help
  616. Provides a cgroup implementing whitelists for devices which
  617. a process in the cgroup can mknod or open.
  618. config CPUSETS
  619. bool "Cpuset support"
  620. help
  621. This option will let you create and manage CPUSETs which
  622. allow dynamically partitioning a system into sets of CPUs and
  623. Memory Nodes and assigning tasks to run only within those sets.
  624. This is primarily useful on large SMP or NUMA systems.
  625. Say N if unsure.
  626. config PROC_PID_CPUSET
  627. bool "Include legacy /proc/<pid>/cpuset file"
  628. depends on CPUSETS
  629. default y
  630. config CGROUP_CPUACCT
  631. bool "Simple CPU accounting cgroup subsystem"
  632. help
  633. Provides a simple Resource Controller for monitoring the
  634. total CPU consumed by the tasks in a cgroup.
  635. config RESOURCE_COUNTERS
  636. bool "Resource counters"
  637. help
  638. This option enables controller independent resource accounting
  639. infrastructure that works with cgroups.
  640. config MEMCG
  641. bool "Memory Resource Controller for Control Groups"
  642. depends on RESOURCE_COUNTERS
  643. select MM_OWNER
  644. help
  645. Provides a memory resource controller that manages both anonymous
  646. memory and page cache. (See Documentation/cgroups/memory.txt)
  647. Note that setting this option increases fixed memory overhead
  648. associated with each page of memory in the system. By this,
  649. 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
  650. usage tracking struct at boot. Total amount of this is printed out
  651. at boot.
  652. Only enable when you're ok with these trade offs and really
  653. sure you need the memory resource controller. Even when you enable
  654. this, you can set "cgroup_disable=memory" at your boot option to
  655. disable memory resource controller and you can avoid overheads.
  656. (and lose benefits of memory resource controller)
  657. This config option also selects MM_OWNER config option, which
  658. could in turn add some fork/exit overhead.
  659. config MEMCG_SWAP
  660. bool "Memory Resource Controller Swap Extension"
  661. depends on MEMCG && SWAP
  662. help
  663. Add swap management feature to memory resource controller. When you
  664. enable this, you can limit mem+swap usage per cgroup. In other words,
  665. when you disable this, memory resource controller has no cares to
  666. usage of swap...a process can exhaust all of the swap. This extension
  667. is useful when you want to avoid exhaustion swap but this itself
  668. adds more overheads and consumes memory for remembering information.
  669. Especially if you use 32bit system or small memory system, please
  670. be careful about enabling this. When memory resource controller
  671. is disabled by boot option, this will be automatically disabled and
  672. there will be no overhead from this. Even when you set this config=y,
  673. if boot option "swapaccount=0" is set, swap will not be accounted.
  674. Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
  675. size is 4096bytes, 512k per 1Gbytes of swap.
  676. config MEMCG_SWAP_ENABLED
  677. bool "Memory Resource Controller Swap Extension enabled by default"
  678. depends on MEMCG_SWAP
  679. default y
  680. help
  681. Memory Resource Controller Swap Extension comes with its price in
  682. a bigger memory consumption. General purpose distribution kernels
  683. which want to enable the feature but keep it disabled by default
  684. and let the user enable it by swapaccount boot command line
  685. parameter should have this option unselected.
  686. For those who want to have the feature enabled by default should
  687. select this option (if, for some reason, they need to disable it
  688. then swapaccount=0 does the trick).
  689. config MEMCG_KMEM
  690. bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
  691. depends on MEMCG && EXPERIMENTAL
  692. default n
  693. help
  694. The Kernel Memory extension for Memory Resource Controller can limit
  695. the amount of memory used by kernel objects in the system. Those are
  696. fundamentally different from the entities handled by the standard
  697. Memory Controller, which are page-based, and can be swapped. Users of
  698. the kmem extension can use it to guarantee that no group of processes
  699. will ever exhaust kernel resources alone.
  700. config CGROUP_HUGETLB
  701. bool "HugeTLB Resource Controller for Control Groups"
  702. depends on RESOURCE_COUNTERS && HUGETLB_PAGE && EXPERIMENTAL
  703. default n
  704. help
  705. Provides a cgroup Resource Controller for HugeTLB pages.
  706. When you enable this, you can put a per cgroup limit on HugeTLB usage.
  707. The limit is enforced during page fault. Since HugeTLB doesn't
  708. support page reclaim, enforcing the limit at page fault time implies
  709. that, the application will get SIGBUS signal if it tries to access
  710. HugeTLB pages beyond its limit. This requires the application to know
  711. beforehand how much HugeTLB pages it would require for its use. The
  712. control group is tracked in the third page lru pointer. This means
  713. that we cannot use the controller with huge page less than 3 pages.
  714. config CGROUP_PERF
  715. bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
  716. depends on PERF_EVENTS && CGROUPS
  717. help
  718. This option extends the per-cpu mode to restrict monitoring to
  719. threads which belong to the cgroup specified and run on the
  720. designated cpu.
  721. Say N if unsure.
  722. menuconfig CGROUP_SCHED
  723. bool "Group CPU scheduler"
  724. default n
  725. help
  726. This feature lets CPU scheduler recognize task groups and control CPU
  727. bandwidth allocation to such task groups. It uses cgroups to group
  728. tasks.
  729. if CGROUP_SCHED
  730. config FAIR_GROUP_SCHED
  731. bool "Group scheduling for SCHED_OTHER"
  732. depends on CGROUP_SCHED
  733. default CGROUP_SCHED
  734. config CFS_BANDWIDTH
  735. bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
  736. depends on EXPERIMENTAL
  737. depends on FAIR_GROUP_SCHED
  738. default n
  739. help
  740. This option allows users to define CPU bandwidth rates (limits) for
  741. tasks running within the fair group scheduler. Groups with no limit
  742. set are considered to be unconstrained and will run with no
  743. restriction.
  744. See tip/Documentation/scheduler/sched-bwc.txt for more information.
  745. config RT_GROUP_SCHED
  746. bool "Group scheduling for SCHED_RR/FIFO"
  747. depends on EXPERIMENTAL
  748. depends on CGROUP_SCHED
  749. default n
  750. help
  751. This feature lets you explicitly allocate real CPU bandwidth
  752. to task groups. If enabled, it will also make it impossible to
  753. schedule realtime tasks for non-root users until you allocate
  754. realtime bandwidth for them.
  755. See Documentation/scheduler/sched-rt-group.txt for more information.
  756. endif #CGROUP_SCHED
  757. config BLK_CGROUP
  758. bool "Block IO controller"
  759. depends on BLOCK
  760. default n
  761. ---help---
  762. Generic block IO controller cgroup interface. This is the common
  763. cgroup interface which should be used by various IO controlling
  764. policies.
  765. Currently, CFQ IO scheduler uses it to recognize task groups and
  766. control disk bandwidth allocation (proportional time slice allocation)
  767. to such task groups. It is also used by bio throttling logic in
  768. block layer to implement upper limit in IO rates on a device.
  769. This option only enables generic Block IO controller infrastructure.
  770. One needs to also enable actual IO controlling logic/policy. For
  771. enabling proportional weight division of disk bandwidth in CFQ, set
  772. CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
  773. CONFIG_BLK_DEV_THROTTLING=y.
  774. See Documentation/cgroups/blkio-controller.txt for more information.
  775. config DEBUG_BLK_CGROUP
  776. bool "Enable Block IO controller debugging"
  777. depends on BLK_CGROUP
  778. default n
  779. ---help---
  780. Enable some debugging help. Currently it exports additional stat
  781. files in a cgroup which can be useful for debugging.
  782. endif # CGROUPS
  783. config CHECKPOINT_RESTORE
  784. bool "Checkpoint/restore support" if EXPERT
  785. default n
  786. help
  787. Enables additional kernel features in a sake of checkpoint/restore.
  788. In particular it adds auxiliary prctl codes to setup process text,
  789. data and heap segment sizes, and a few additional /proc filesystem
  790. entries.
  791. If unsure, say N here.
  792. menuconfig NAMESPACES
  793. bool "Namespaces support" if EXPERT
  794. default !EXPERT
  795. help
  796. Provides the way to make tasks work with different objects using
  797. the same id. For example same IPC id may refer to different objects
  798. or same user id or pid may refer to different tasks when used in
  799. different namespaces.
  800. if NAMESPACES
  801. config UTS_NS
  802. bool "UTS namespace"
  803. default y
  804. help
  805. In this namespace tasks see different info provided with the
  806. uname() system call
  807. config IPC_NS
  808. bool "IPC namespace"
  809. depends on (SYSVIPC || POSIX_MQUEUE)
  810. default y
  811. help
  812. In this namespace tasks work with IPC ids which correspond to
  813. different IPC objects in different namespaces.
  814. config USER_NS
  815. bool "User namespace (EXPERIMENTAL)"
  816. depends on EXPERIMENTAL
  817. depends on UIDGID_CONVERTED
  818. select UIDGID_STRICT_TYPE_CHECKS
  819. default n
  820. help
  821. This allows containers, i.e. vservers, to use user namespaces
  822. to provide different user info for different servers.
  823. If unsure, say N.
  824. config PID_NS
  825. bool "PID Namespaces"
  826. default y
  827. help
  828. Support process id namespaces. This allows having multiple
  829. processes with the same pid as long as they are in different
  830. pid namespaces. This is a building block of containers.
  831. config NET_NS
  832. bool "Network namespace"
  833. depends on NET
  834. default y
  835. help
  836. Allow user space to create what appear to be multiple instances
  837. of the network stack.
  838. endif # NAMESPACES
  839. config UIDGID_CONVERTED
  840. # True if all of the selected software conmponents are known
  841. # to have uid_t and gid_t converted to kuid_t and kgid_t
  842. # where appropriate and are otherwise safe to use with
  843. # the user namespace.
  844. bool
  845. default y
  846. # Networking
  847. depends on NET_9P = n
  848. # Filesystems
  849. depends on 9P_FS = n
  850. depends on AFS_FS = n
  851. depends on CEPH_FS = n
  852. depends on CIFS = n
  853. depends on CODA_FS = n
  854. depends on GFS2_FS = n
  855. depends on NCP_FS = n
  856. depends on NFSD = n
  857. depends on NFS_FS = n
  858. depends on OCFS2_FS = n
  859. depends on XFS_FS = n
  860. config UIDGID_STRICT_TYPE_CHECKS
  861. bool "Require conversions between uid/gids and their internal representation"
  862. depends on UIDGID_CONVERTED
  863. default n
  864. help
  865. While the nececessary conversions are being added to all subsystems this option allows
  866. the code to continue to build for unconverted subsystems.
  867. Say Y here if you want the strict type checking enabled
  868. config SCHED_AUTOGROUP
  869. bool "Automatic process group scheduling"
  870. select EVENTFD
  871. select CGROUPS
  872. select CGROUP_SCHED
  873. select FAIR_GROUP_SCHED
  874. help
  875. This option optimizes the scheduler for common desktop workloads by
  876. automatically creating and populating task groups. This separation
  877. of workloads isolates aggressive CPU burners (like build jobs) from
  878. desktop applications. Task group autogeneration is currently based
  879. upon task session.
  880. config MM_OWNER
  881. bool
  882. config SYSFS_DEPRECATED
  883. bool "Enable deprecated sysfs features to support old userspace tools"
  884. depends on SYSFS
  885. default n
  886. help
  887. This option adds code that switches the layout of the "block" class
  888. devices, to not show up in /sys/class/block/, but only in
  889. /sys/block/.
  890. This switch is only active when the sysfs.deprecated=1 boot option is
  891. passed or the SYSFS_DEPRECATED_V2 option is set.
  892. This option allows new kernels to run on old distributions and tools,
  893. which might get confused by /sys/class/block/. Since 2007/2008 all
  894. major distributions and tools handle this just fine.
  895. Recent distributions and userspace tools after 2009/2010 depend on
  896. the existence of /sys/class/block/, and will not work with this
  897. option enabled.
  898. Only if you are using a new kernel on an old distribution, you might
  899. need to say Y here.
  900. config SYSFS_DEPRECATED_V2
  901. bool "Enable deprecated sysfs features by default"
  902. default n
  903. depends on SYSFS
  904. depends on SYSFS_DEPRECATED
  905. help
  906. Enable deprecated sysfs by default.
  907. See the CONFIG_SYSFS_DEPRECATED option for more details about this
  908. option.
  909. Only if you are using a new kernel on an old distribution, you might
  910. need to say Y here. Even then, odds are you would not need it
  911. enabled, you can always pass the boot option if absolutely necessary.
  912. config RELAY
  913. bool "Kernel->user space relay support (formerly relayfs)"
  914. help
  915. This option enables support for relay interface support in
  916. certain file systems (such as debugfs).
  917. It is designed to provide an efficient mechanism for tools and
  918. facilities to relay large amounts of data from kernel space to
  919. user space.
  920. If unsure, say N.
  921. config BLK_DEV_INITRD
  922. bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
  923. depends on BROKEN || !FRV
  924. help
  925. The initial RAM filesystem is a ramfs which is loaded by the
  926. boot loader (loadlin or lilo) and that is mounted as root
  927. before the normal boot procedure. It is typically used to
  928. load modules needed to mount the "real" root file system,
  929. etc. See <file:Documentation/initrd.txt> for details.
  930. If RAM disk support (BLK_DEV_RAM) is also included, this
  931. also enables initial RAM disk (initrd) support and adds
  932. 15 Kbytes (more on some other architectures) to the kernel size.
  933. If unsure say Y.
  934. if BLK_DEV_INITRD
  935. source "usr/Kconfig"
  936. endif
  937. config CC_OPTIMIZE_FOR_SIZE
  938. bool "Optimize for size"
  939. help
  940. Enabling this option will pass "-Os" instead of "-O2" to gcc
  941. resulting in a smaller kernel.
  942. If unsure, say Y.
  943. config SYSCTL
  944. bool
  945. config ANON_INODES
  946. bool
  947. menuconfig EXPERT
  948. bool "Configure standard kernel features (expert users)"
  949. # Unhide debug options, to make the on-by-default options visible
  950. select DEBUG_KERNEL
  951. help
  952. This option allows certain base kernel options and settings
  953. to be disabled or tweaked. This is for specialized
  954. environments which can tolerate a "non-standard" kernel.
  955. Only use this if you really know what you are doing.
  956. config HAVE_UID16
  957. bool
  958. config UID16
  959. bool "Enable 16-bit UID system calls" if EXPERT
  960. depends on HAVE_UID16
  961. default y
  962. help
  963. This enables the legacy 16-bit UID syscall wrappers.
  964. config SYSCTL_SYSCALL
  965. bool "Sysctl syscall support" if EXPERT
  966. depends on PROC_SYSCTL
  967. default n
  968. select SYSCTL
  969. ---help---
  970. sys_sysctl uses binary paths that have been found challenging
  971. to properly maintain and use. The interface in /proc/sys
  972. using paths with ascii names is now the primary path to this
  973. information.
  974. Almost nothing using the binary sysctl interface so if you are
  975. trying to save some space it is probably safe to disable this,
  976. making your kernel marginally smaller.
  977. If unsure say N here.
  978. config SYSCTL_EXCEPTION_TRACE
  979. bool
  980. help
  981. Enable support for /proc/sys/debug/exception-trace.
  982. config KALLSYMS
  983. bool "Load all symbols for debugging/ksymoops" if EXPERT
  984. default y
  985. help
  986. Say Y here to let the kernel print out symbolic crash information and
  987. symbolic stack backtraces. This increases the size of the kernel
  988. somewhat, as all symbols have to be loaded into the kernel image.
  989. config KALLSYMS_ALL
  990. bool "Include all symbols in kallsyms"
  991. depends on DEBUG_KERNEL && KALLSYMS
  992. help
  993. Normally kallsyms only contains the symbols of functions for nicer
  994. OOPS messages and backtraces (i.e., symbols from the text and inittext
  995. sections). This is sufficient for most cases. And only in very rare
  996. cases (e.g., when a debugger is used) all symbols are required (e.g.,
  997. names of variables from the data sections, etc).
  998. This option makes sure that all symbols are loaded into the kernel
  999. image (i.e., symbols from all sections) in cost of increased kernel
  1000. size (depending on the kernel configuration, it may be 300KiB or
  1001. something like this).
  1002. Say N unless you really need all symbols.
  1003. config HOTPLUG
  1004. def_bool y
  1005. config PRINTK
  1006. default y
  1007. bool "Enable support for printk" if EXPERT
  1008. help
  1009. This option enables normal printk support. Removing it
  1010. eliminates most of the message strings from the kernel image
  1011. and makes the kernel more or less silent. As this makes it
  1012. very difficult to diagnose system problems, saying N here is
  1013. strongly discouraged.
  1014. config BUG
  1015. bool "BUG() support" if EXPERT
  1016. default y
  1017. help
  1018. Disabling this option eliminates support for BUG and WARN, reducing
  1019. the size of your kernel image and potentially quietly ignoring
  1020. numerous fatal conditions. You should only consider disabling this
  1021. option for embedded systems with no facilities for reporting errors.
  1022. Just say Y.
  1023. config ELF_CORE
  1024. depends on COREDUMP
  1025. default y
  1026. bool "Enable ELF core dumps" if EXPERT
  1027. help
  1028. Enable support for generating core dumps. Disabling saves about 4k.
  1029. config PCSPKR_PLATFORM
  1030. bool "Enable PC-Speaker support" if EXPERT
  1031. depends on HAVE_PCSPKR_PLATFORM
  1032. select I8253_LOCK
  1033. default y
  1034. help
  1035. This option allows to disable the internal PC-Speaker
  1036. support, saving some memory.
  1037. config HAVE_PCSPKR_PLATFORM
  1038. bool
  1039. config BASE_FULL
  1040. default y
  1041. bool "Enable full-sized data structures for core" if EXPERT
  1042. help
  1043. Disabling this option reduces the size of miscellaneous core
  1044. kernel data structures. This saves memory on small machines,
  1045. but may reduce performance.
  1046. config FUTEX
  1047. bool "Enable futex support" if EXPERT
  1048. default y
  1049. select RT_MUTEXES
  1050. help
  1051. Disabling this option will cause the kernel to be built without
  1052. support for "fast userspace mutexes". The resulting kernel may not
  1053. run glibc-based applications correctly.
  1054. config EPOLL
  1055. bool "Enable eventpoll support" if EXPERT
  1056. default y
  1057. select ANON_INODES
  1058. help
  1059. Disabling this option will cause the kernel to be built without
  1060. support for epoll family of system calls.
  1061. config SIGNALFD
  1062. bool "Enable signalfd() system call" if EXPERT
  1063. select ANON_INODES
  1064. default y
  1065. help
  1066. Enable the signalfd() system call that allows to receive signals
  1067. on a file descriptor.
  1068. If unsure, say Y.
  1069. config TIMERFD
  1070. bool "Enable timerfd() system call" if EXPERT
  1071. select ANON_INODES
  1072. default y
  1073. help
  1074. Enable the timerfd() system call that allows to receive timer
  1075. events on a file descriptor.
  1076. If unsure, say Y.
  1077. config EVENTFD
  1078. bool "Enable eventfd() system call" if EXPERT
  1079. select ANON_INODES
  1080. default y
  1081. help
  1082. Enable the eventfd() system call that allows to receive both
  1083. kernel notification (ie. KAIO) or userspace notifications.
  1084. If unsure, say Y.
  1085. config SHMEM
  1086. bool "Use full shmem filesystem" if EXPERT
  1087. default y
  1088. depends on MMU
  1089. help
  1090. The shmem is an internal filesystem used to manage shared memory.
  1091. It is backed by swap and manages resource limits. It is also exported
  1092. to userspace as tmpfs if TMPFS is enabled. Disabling this
  1093. option replaces shmem and tmpfs with the much simpler ramfs code,
  1094. which may be appropriate on small systems without swap.
  1095. config AIO
  1096. bool "Enable AIO support" if EXPERT
  1097. default y
  1098. help
  1099. This option enables POSIX asynchronous I/O which may by used
  1100. by some high performance threaded applications. Disabling
  1101. this option saves about 7k.
  1102. config EMBEDDED
  1103. bool "Embedded system"
  1104. select EXPERT
  1105. help
  1106. This option should be enabled if compiling the kernel for
  1107. an embedded system so certain expert options are available
  1108. for configuration.
  1109. config HAVE_PERF_EVENTS
  1110. bool
  1111. help
  1112. See tools/perf/design.txt for details.
  1113. config PERF_USE_VMALLOC
  1114. bool
  1115. help
  1116. See tools/perf/design.txt for details
  1117. menu "Kernel Performance Events And Counters"
  1118. config PERF_EVENTS
  1119. bool "Kernel performance events and counters"
  1120. default y if PROFILING
  1121. depends on HAVE_PERF_EVENTS
  1122. select ANON_INODES
  1123. select IRQ_WORK
  1124. help
  1125. Enable kernel support for various performance events provided
  1126. by software and hardware.
  1127. Software events are supported either built-in or via the
  1128. use of generic tracepoints.
  1129. Most modern CPUs support performance events via performance
  1130. counter registers. These registers count the number of certain
  1131. types of hw events: such as instructions executed, cachemisses
  1132. suffered, or branches mis-predicted - without slowing down the
  1133. kernel or applications. These registers can also trigger interrupts
  1134. when a threshold number of events have passed - and can thus be
  1135. used to profile the code that runs on that CPU.
  1136. The Linux Performance Event subsystem provides an abstraction of
  1137. these software and hardware event capabilities, available via a
  1138. system call and used by the "perf" utility in tools/perf/. It
  1139. provides per task and per CPU counters, and it provides event
  1140. capabilities on top of those.
  1141. Say Y if unsure.
  1142. config DEBUG_PERF_USE_VMALLOC
  1143. default n
  1144. bool "Debug: use vmalloc to back perf mmap() buffers"
  1145. depends on PERF_EVENTS && DEBUG_KERNEL
  1146. select PERF_USE_VMALLOC
  1147. help
  1148. Use vmalloc memory to back perf mmap() buffers.
  1149. Mostly useful for debugging the vmalloc code on platforms
  1150. that don't require it.
  1151. Say N if unsure.
  1152. endmenu
  1153. config VM_EVENT_COUNTERS
  1154. default y
  1155. bool "Enable VM event counters for /proc/vmstat" if EXPERT
  1156. help
  1157. VM event counters are needed for event counts to be shown.
  1158. This option allows the disabling of the VM event counters
  1159. on EXPERT systems. /proc/vmstat will only show page counts
  1160. if VM event counters are disabled.
  1161. config PCI_QUIRKS
  1162. default y
  1163. bool "Enable PCI quirk workarounds" if EXPERT
  1164. depends on PCI
  1165. help
  1166. This enables workarounds for various PCI chipset
  1167. bugs/quirks. Disable this only if your target machine is
  1168. unaffected by PCI quirks.
  1169. config SLUB_DEBUG
  1170. default y
  1171. bool "Enable SLUB debugging support" if EXPERT
  1172. depends on SLUB && SYSFS
  1173. help
  1174. SLUB has extensive debug support features. Disabling these can
  1175. result in significant savings in code size. This also disables
  1176. SLUB sysfs support. /sys/slab will not exist and there will be
  1177. no support for cache validation etc.
  1178. config COMPAT_BRK
  1179. bool "Disable heap randomization"
  1180. default y
  1181. help
  1182. Randomizing heap placement makes heap exploits harder, but it
  1183. also breaks ancient binaries (including anything libc5 based).
  1184. This option changes the bootup default to heap randomization
  1185. disabled, and can be overridden at runtime by setting
  1186. /proc/sys/kernel/randomize_va_space to 2.
  1187. On non-ancient distros (post-2000 ones) N is usually a safe choice.
  1188. choice
  1189. prompt "Choose SLAB allocator"
  1190. default SLUB
  1191. help
  1192. This option allows to select a slab allocator.
  1193. config SLAB
  1194. bool "SLAB"
  1195. help
  1196. The regular slab allocator that is established and known to work
  1197. well in all environments. It organizes cache hot objects in
  1198. per cpu and per node queues.
  1199. config SLUB
  1200. bool "SLUB (Unqueued Allocator)"
  1201. help
  1202. SLUB is a slab allocator that minimizes cache line usage
  1203. instead of managing queues of cached objects (SLAB approach).
  1204. Per cpu caching is realized using slabs of objects instead
  1205. of queues of objects. SLUB can use memory efficiently
  1206. and has enhanced diagnostics. SLUB is the default choice for
  1207. a slab allocator.
  1208. config SLOB
  1209. depends on EXPERT
  1210. bool "SLOB (Simple Allocator)"
  1211. help
  1212. SLOB replaces the stock allocator with a drastically simpler
  1213. allocator. SLOB is generally more space efficient but
  1214. does not perform as well on large systems.
  1215. endchoice
  1216. config MMAP_ALLOW_UNINITIALIZED
  1217. bool "Allow mmapped anonymous memory to be uninitialized"
  1218. depends on EXPERT && !MMU
  1219. default n
  1220. help
  1221. Normally, and according to the Linux spec, anonymous memory obtained
  1222. from mmap() has it's contents cleared before it is passed to
  1223. userspace. Enabling this config option allows you to request that
  1224. mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
  1225. providing a huge performance boost. If this option is not enabled,
  1226. then the flag will be ignored.
  1227. This is taken advantage of by uClibc's malloc(), and also by
  1228. ELF-FDPIC binfmt's brk and stack allocator.
  1229. Because of the obvious security issues, this option should only be
  1230. enabled on embedded devices where you control what is run in
  1231. userspace. Since that isn't generally a problem on no-MMU systems,
  1232. it is normally safe to say Y here.
  1233. See Documentation/nommu-mmap.txt for more information.
  1234. config PROFILING
  1235. bool "Profiling support"
  1236. help
  1237. Say Y here to enable the extended profiling support mechanisms used
  1238. by profilers such as OProfile.
  1239. #
  1240. # Place an empty function call at each tracepoint site. Can be
  1241. # dynamically changed for a probe function.
  1242. #
  1243. config TRACEPOINTS
  1244. bool
  1245. source "arch/Kconfig"
  1246. endmenu # General setup
  1247. config HAVE_GENERIC_DMA_COHERENT
  1248. bool
  1249. default n
  1250. config SLABINFO
  1251. bool
  1252. depends on PROC_FS
  1253. depends on SLAB || SLUB_DEBUG
  1254. default y
  1255. config RT_MUTEXES
  1256. boolean
  1257. config BASE_SMALL
  1258. int
  1259. default 0 if BASE_FULL
  1260. default 1 if !BASE_FULL
  1261. menuconfig MODULES
  1262. bool "Enable loadable module support"
  1263. help
  1264. Kernel modules are small pieces of compiled code which can
  1265. be inserted in the running kernel, rather than being
  1266. permanently built into the kernel. You use the "modprobe"
  1267. tool to add (and sometimes remove) them. If you say Y here,
  1268. many parts of the kernel can be built as modules (by
  1269. answering M instead of Y where indicated): this is most
  1270. useful for infrequently used options which are not required
  1271. for booting. For more information, see the man pages for
  1272. modprobe, lsmod, modinfo, insmod and rmmod.
  1273. If you say Y here, you will need to run "make
  1274. modules_install" to put the modules under /lib/modules/
  1275. where modprobe can find them (you may need to be root to do
  1276. this).
  1277. If unsure, say Y.
  1278. if MODULES
  1279. config MODULE_FORCE_LOAD
  1280. bool "Forced module loading"
  1281. default n
  1282. help
  1283. Allow loading of modules without version information (ie. modprobe
  1284. --force). Forced module loading sets the 'F' (forced) taint flag and
  1285. is usually a really bad idea.
  1286. config MODULE_UNLOAD
  1287. bool "Module unloading"
  1288. help
  1289. Without this option you will not be able to unload any
  1290. modules (note that some modules may not be unloadable
  1291. anyway), which makes your kernel smaller, faster
  1292. and simpler. If unsure, say Y.
  1293. config MODULE_FORCE_UNLOAD
  1294. bool "Forced module unloading"
  1295. depends on MODULE_UNLOAD && EXPERIMENTAL
  1296. help
  1297. This option allows you to force a module to unload, even if the
  1298. kernel believes it is unsafe: the kernel will remove the module
  1299. without waiting for anyone to stop using it (using the -f option to
  1300. rmmod). This is mainly for kernel developers and desperate users.
  1301. If unsure, say N.
  1302. config MODVERSIONS
  1303. bool "Module versioning support"
  1304. help
  1305. Usually, you have to use modules compiled with your kernel.
  1306. Saying Y here makes it sometimes possible to use modules
  1307. compiled for different kernels, by adding enough information
  1308. to the modules to (hopefully) spot any changes which would
  1309. make them incompatible with the kernel you are running. If
  1310. unsure, say N.
  1311. config MODULE_SRCVERSION_ALL
  1312. bool "Source checksum for all modules"
  1313. help
  1314. Modules which contain a MODULE_VERSION get an extra "srcversion"
  1315. field inserted into their modinfo section, which contains a
  1316. sum of the source files which made it. This helps maintainers
  1317. see exactly which source was used to build a module (since
  1318. others sometimes change the module source without updating
  1319. the version). With this option, such a "srcversion" field
  1320. will be created for all modules. If unsure, say N.
  1321. config MODULE_SIG
  1322. bool "Module signature verification"
  1323. depends on MODULES
  1324. select KEYS
  1325. select CRYPTO
  1326. select ASYMMETRIC_KEY_TYPE
  1327. select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
  1328. select PUBLIC_KEY_ALGO_RSA
  1329. select ASN1
  1330. select OID_REGISTRY
  1331. select X509_CERTIFICATE_PARSER
  1332. help
  1333. Check modules for valid signatures upon load: the signature
  1334. is simply appended to the module. For more information see
  1335. Documentation/module-signing.txt.
  1336. !!!WARNING!!! If you enable this option, you MUST make sure that the
  1337. module DOES NOT get stripped after being signed. This includes the
  1338. debuginfo strip done by some packagers (such as rpmbuild) and
  1339. inclusion into an initramfs that wants the module size reduced.
  1340. config MODULE_SIG_FORCE
  1341. bool "Require modules to be validly signed"
  1342. depends on MODULE_SIG
  1343. help
  1344. Reject unsigned modules or signed modules for which we don't have a
  1345. key. Without this, such modules will simply taint the kernel.
  1346. choice
  1347. prompt "Which hash algorithm should modules be signed with?"
  1348. depends on MODULE_SIG
  1349. help
  1350. This determines which sort of hashing algorithm will be used during
  1351. signature generation. This algorithm _must_ be built into the kernel
  1352. directly so that signature verification can take place. It is not
  1353. possible to load a signed module containing the algorithm to check
  1354. the signature on that module.
  1355. config MODULE_SIG_SHA1
  1356. bool "Sign modules with SHA-1"
  1357. select CRYPTO_SHA1
  1358. config MODULE_SIG_SHA224
  1359. bool "Sign modules with SHA-224"
  1360. select CRYPTO_SHA256
  1361. config MODULE_SIG_SHA256
  1362. bool "Sign modules with SHA-256"
  1363. select CRYPTO_SHA256
  1364. config MODULE_SIG_SHA384
  1365. bool "Sign modules with SHA-384"
  1366. select CRYPTO_SHA512
  1367. config MODULE_SIG_SHA512
  1368. bool "Sign modules with SHA-512"
  1369. select CRYPTO_SHA512
  1370. endchoice
  1371. endif # MODULES
  1372. config INIT_ALL_POSSIBLE
  1373. bool
  1374. help
  1375. Back when each arch used to define their own cpu_online_mask and
  1376. cpu_possible_mask, some of them chose to initialize cpu_possible_mask
  1377. with all 1s, and others with all 0s. When they were centralised,
  1378. it was better to provide this option than to break all the archs
  1379. and have several arch maintainers pursuing me down dark alleys.
  1380. config STOP_MACHINE
  1381. bool
  1382. default y
  1383. depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
  1384. help
  1385. Need stop_machine() primitive.
  1386. source "block/Kconfig"
  1387. config PREEMPT_NOTIFIERS
  1388. bool
  1389. config PADATA
  1390. depends on SMP
  1391. bool
  1392. # Can be selected by architectures with broken toolchains
  1393. # that get confused by correct const<->read_only section
  1394. # mappings
  1395. config BROKEN_RODATA
  1396. bool
  1397. config ASN1
  1398. tristate
  1399. help
  1400. Build a simple ASN.1 grammar compiler that produces a bytecode output
  1401. that can be interpreted by the ASN.1 stream decoder and used to
  1402. inform it as to what tags are to be expected in a stream and what
  1403. functions to call on what tags.
  1404. source "kernel/Kconfig.locks"