Kconfig 54 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
  29. default y
  30. config BROKEN
  31. bool
  32. config BROKEN_ON_SMP
  33. bool
  34. depends on BROKEN || !SMP
  35. default y
  36. config INIT_ENV_ARG_LIMIT
  37. int
  38. default 32 if !UML
  39. default 128 if UML
  40. help
  41. Maximum of each of the number of arguments and environment
  42. variables passed to init from the kernel command line.
  43. config CROSS_COMPILE
  44. string "Cross-compiler tool prefix"
  45. help
  46. Same as running 'make CROSS_COMPILE=prefix-' but stored for
  47. default make runs in this kernel build directory. You don't
  48. need to set this unless you want the configured kernel build
  49. directory to select the cross-compiler automatically.
  50. config LOCALVERSION
  51. string "Local version - append to kernel release"
  52. help
  53. Append an extra string to the end of your kernel version.
  54. This will show up when you type uname, for example.
  55. The string you set here will be appended after the contents of
  56. any files with a filename matching localversion* in your
  57. object and source tree, in that order. Your total string can
  58. be a maximum of 64 characters.
  59. config LOCALVERSION_AUTO
  60. bool "Automatically append version information to the version string"
  61. default y
  62. help
  63. This will try to automatically determine if the current tree is a
  64. release tree by looking for git tags that belong to the current
  65. top of tree revision.
  66. A string of the format -gxxxxxxxx will be added to the localversion
  67. if a git-based tree is found. The string generated by this will be
  68. appended after any matching localversion* files, and after the value
  69. set in CONFIG_LOCALVERSION.
  70. (The actual string used here is the first eight characters produced
  71. by running the command:
  72. $ git rev-parse --verify HEAD
  73. which is done within the script "scripts/setlocalversion".)
  74. config HAVE_KERNEL_GZIP
  75. bool
  76. config HAVE_KERNEL_BZIP2
  77. bool
  78. config HAVE_KERNEL_LZMA
  79. bool
  80. config HAVE_KERNEL_XZ
  81. bool
  82. config HAVE_KERNEL_LZO
  83. bool
  84. choice
  85. prompt "Kernel compression mode"
  86. default KERNEL_GZIP
  87. depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
  88. help
  89. The linux kernel is a kind of self-extracting executable.
  90. Several compression algorithms are available, which differ
  91. in efficiency, compression and decompression speed.
  92. Compression speed is only relevant when building a kernel.
  93. Decompression speed is relevant at each boot.
  94. If you have any problems with bzip2 or lzma compressed
  95. kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
  96. version of this functionality (bzip2 only), for 2.4, was
  97. supplied by Christian Ludwig)
  98. High compression options are mostly useful for users, who
  99. are low on disk space (embedded systems), but for whom ram
  100. size matters less.
  101. If in doubt, select 'gzip'
  102. config KERNEL_GZIP
  103. bool "Gzip"
  104. depends on HAVE_KERNEL_GZIP
  105. help
  106. The old and tried gzip compression. It provides a good balance
  107. between compression ratio and decompression speed.
  108. config KERNEL_BZIP2
  109. bool "Bzip2"
  110. depends on HAVE_KERNEL_BZIP2
  111. help
  112. Its compression ratio and speed is intermediate.
  113. Decompression speed is slowest among the choices. The kernel
  114. size is about 10% smaller with bzip2, in comparison to gzip.
  115. Bzip2 uses a large amount of memory. For modern kernels you
  116. will need at least 8MB RAM or more for booting.
  117. config KERNEL_LZMA
  118. bool "LZMA"
  119. depends on HAVE_KERNEL_LZMA
  120. help
  121. This compression algorithm's ratio is best. Decompression speed
  122. is between gzip and bzip2. Compression is slowest.
  123. The kernel size is about 33% smaller with LZMA in comparison to gzip.
  124. config KERNEL_XZ
  125. bool "XZ"
  126. depends on HAVE_KERNEL_XZ
  127. help
  128. XZ uses the LZMA2 algorithm and instruction set specific
  129. BCJ filters which can improve compression ratio of executable
  130. code. The size of the kernel is about 30% smaller with XZ in
  131. comparison to gzip. On architectures for which there is a BCJ
  132. filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
  133. will create a few percent smaller kernel than plain LZMA.
  134. The speed is about the same as with LZMA: The decompression
  135. speed of XZ is better than that of bzip2 but worse than gzip
  136. and LZO. Compression is slow.
  137. config KERNEL_LZO
  138. bool "LZO"
  139. depends on HAVE_KERNEL_LZO
  140. help
  141. Its compression ratio is the poorest among the choices. The kernel
  142. size is about 10% bigger than gzip; however its speed
  143. (both compression and decompression) is the fastest.
  144. endchoice
  145. config DEFAULT_HOSTNAME
  146. string "Default hostname"
  147. default "(none)"
  148. help
  149. This option determines the default system hostname before userspace
  150. calls sethostname(2). The kernel traditionally uses "(none)" here,
  151. but you may wish to use a different default here to make a minimal
  152. system more usable with less configuration.
  153. config SWAP
  154. bool "Support for paging of anonymous memory (swap)"
  155. depends on MMU && BLOCK
  156. default y
  157. help
  158. This option allows you to choose whether you want to have support
  159. for so called swap devices or swap files in your kernel that are
  160. used to provide more virtual memory than the actual RAM present
  161. in your computer. If unsure say Y.
  162. config SYSVIPC
  163. bool "System V IPC"
  164. ---help---
  165. Inter Process Communication is a suite of library functions and
  166. system calls which let processes (running programs) synchronize and
  167. exchange information. It is generally considered to be a good thing,
  168. and some programs won't run unless you say Y here. In particular, if
  169. you want to run the DOS emulator dosemu under Linux (read the
  170. DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
  171. you'll need to say Y here.
  172. You can find documentation about IPC with "info ipc" and also in
  173. section 6.4 of the Linux Programmer's Guide, available from
  174. <http://www.tldp.org/guides.html>.
  175. config SYSVIPC_SYSCTL
  176. bool
  177. depends on SYSVIPC
  178. depends on SYSCTL
  179. default y
  180. config POSIX_MQUEUE
  181. bool "POSIX Message Queues"
  182. depends on NET
  183. ---help---
  184. POSIX variant of message queues is a part of IPC. In POSIX message
  185. queues every message has a priority which decides about succession
  186. of receiving it by a process. If you want to compile and run
  187. programs written e.g. for Solaris with use of its POSIX message
  188. queues (functions mq_*) say Y here.
  189. POSIX message queues are visible as a filesystem called 'mqueue'
  190. and can be mounted somewhere if you want to do filesystem
  191. operations on message queues.
  192. If unsure, say Y.
  193. config POSIX_MQUEUE_SYSCTL
  194. bool
  195. depends on POSIX_MQUEUE
  196. depends on SYSCTL
  197. default y
  198. config FHANDLE
  199. bool "open by fhandle syscalls"
  200. select EXPORTFS
  201. help
  202. If you say Y here, a user level program will be able to map
  203. file names to handle and then later use the handle for
  204. different file system operations. This is useful in implementing
  205. userspace file servers, which now track files using handles instead
  206. of names. The handle would remain the same even if file names
  207. get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
  208. syscalls.
  209. config AUDIT
  210. bool "Auditing support"
  211. depends on NET
  212. help
  213. Enable auditing infrastructure that can be used with another
  214. kernel subsystem, such as SELinux (which requires this for
  215. logging of avc messages output). Does not do system-call
  216. auditing without CONFIG_AUDITSYSCALL.
  217. config AUDITSYSCALL
  218. bool "Enable system-call auditing support"
  219. depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || (ARM && AEABI && !OABI_COMPAT))
  220. default y if SECURITY_SELINUX
  221. help
  222. Enable low-overhead system-call auditing infrastructure that
  223. can be used independently or with another kernel subsystem,
  224. such as SELinux.
  225. config AUDIT_WATCH
  226. def_bool y
  227. depends on AUDITSYSCALL
  228. select FSNOTIFY
  229. config AUDIT_TREE
  230. def_bool y
  231. depends on AUDITSYSCALL
  232. select FSNOTIFY
  233. config AUDIT_LOGINUID_IMMUTABLE
  234. bool "Make audit loginuid immutable"
  235. depends on AUDIT
  236. help
  237. The config option toggles if a task setting its loginuid requires
  238. CAP_SYS_AUDITCONTROL or if that task should require no special permissions
  239. but should instead only allow setting its loginuid if it was never
  240. previously set. On systems which use systemd or a similar central
  241. process to restart login services this should be set to true. On older
  242. systems in which an admin would typically have to directly stop and
  243. start processes this should be set to false. Setting this to true allows
  244. one to drop potentially dangerous capabilites from the login tasks,
  245. but may not be backwards compatible with older init systems.
  246. source "kernel/irq/Kconfig"
  247. source "kernel/time/Kconfig"
  248. menu "CPU/Task time and stats accounting"
  249. choice
  250. prompt "Cputime accounting"
  251. default TICK_CPU_ACCOUNTING if !PPC64
  252. default VIRT_CPU_ACCOUNTING if PPC64
  253. # Kind of a stub config for the pure tick based cputime accounting
  254. config TICK_CPU_ACCOUNTING
  255. bool "Simple tick based cputime accounting"
  256. depends on !S390
  257. help
  258. This is the basic tick based cputime accounting that maintains
  259. statistics about user, system and idle time spent on per jiffies
  260. granularity.
  261. If unsure, say Y.
  262. config VIRT_CPU_ACCOUNTING
  263. bool "Deterministic task and CPU time accounting"
  264. depends on HAVE_VIRT_CPU_ACCOUNTING
  265. help
  266. Select this option to enable more accurate task and CPU time
  267. accounting. This is done by reading a CPU counter on each
  268. kernel entry and exit and on transitions within the kernel
  269. between system, softirq and hardirq state, so there is a
  270. small performance impact. In the case of s390 or IBM POWER > 5,
  271. this also enables accounting of stolen time on logically-partitioned
  272. systems.
  273. config IRQ_TIME_ACCOUNTING
  274. bool "Fine granularity task level IRQ time accounting"
  275. depends on HAVE_IRQ_TIME_ACCOUNTING
  276. help
  277. Select this option to enable fine granularity task irq time
  278. accounting. This is done by reading a timestamp on each
  279. transitions between softirq and hardirq state, so there can be a
  280. small performance impact.
  281. If in doubt, say N here.
  282. endchoice
  283. config BSD_PROCESS_ACCT
  284. bool "BSD Process Accounting"
  285. help
  286. If you say Y here, a user level program will be able to instruct the
  287. kernel (via a special system call) to write process accounting
  288. information to a file: whenever a process exits, information about
  289. that process will be appended to the file by the kernel. The
  290. information includes things such as creation time, owning user,
  291. command name, memory usage, controlling terminal etc. (the complete
  292. list is in the struct acct in <file:include/linux/acct.h>). It is
  293. up to the user level program to do useful things with this
  294. information. This is generally a good idea, so say Y.
  295. config BSD_PROCESS_ACCT_V3
  296. bool "BSD Process Accounting version 3 file format"
  297. depends on BSD_PROCESS_ACCT
  298. default n
  299. help
  300. If you say Y here, the process accounting information is written
  301. in a new file format that also logs the process IDs of each
  302. process and it's parent. Note that this file format is incompatible
  303. with previous v0/v1/v2 file formats, so you will need updated tools
  304. for processing it. A preliminary version of these tools is available
  305. at <http://www.gnu.org/software/acct/>.
  306. config TASKSTATS
  307. bool "Export task/process statistics through netlink"
  308. depends on NET
  309. default n
  310. help
  311. Export selected statistics for tasks/processes through the
  312. generic netlink interface. Unlike BSD process accounting, the
  313. statistics are available during the lifetime of tasks/processes as
  314. responses to commands. Like BSD accounting, they are sent to user
  315. space on task exit.
  316. Say N if unsure.
  317. config TASK_DELAY_ACCT
  318. bool "Enable per-task delay accounting"
  319. depends on TASKSTATS
  320. help
  321. Collect information on time spent by a task waiting for system
  322. resources like cpu, synchronous block I/O completion and swapping
  323. in pages. Such statistics can help in setting a task's priorities
  324. relative to other tasks for cpu, io, rss limits etc.
  325. Say N if unsure.
  326. config TASK_XACCT
  327. bool "Enable extended accounting over taskstats"
  328. depends on TASKSTATS
  329. help
  330. Collect extended task accounting data and send the data
  331. to userland for processing over the taskstats interface.
  332. Say N if unsure.
  333. config TASK_IO_ACCOUNTING
  334. bool "Enable per-task storage I/O accounting"
  335. depends on TASK_XACCT
  336. help
  337. Collect information on the number of bytes of storage I/O which this
  338. task has caused.
  339. Say N if unsure.
  340. endmenu # "CPU/Task time and stats accounting"
  341. menu "RCU Subsystem"
  342. choice
  343. prompt "RCU Implementation"
  344. default TREE_RCU
  345. config TREE_RCU
  346. bool "Tree-based hierarchical RCU"
  347. depends on !PREEMPT && SMP
  348. help
  349. This option selects the RCU implementation that is
  350. designed for very large SMP system with hundreds or
  351. thousands of CPUs. It also scales down nicely to
  352. smaller systems.
  353. config TREE_PREEMPT_RCU
  354. bool "Preemptible tree-based hierarchical RCU"
  355. depends on PREEMPT && SMP
  356. help
  357. This option selects the RCU implementation that is
  358. designed for very large SMP systems with hundreds or
  359. thousands of CPUs, but for which real-time response
  360. is also required. It also scales down nicely to
  361. smaller systems.
  362. config TINY_RCU
  363. bool "UP-only small-memory-footprint RCU"
  364. depends on !PREEMPT && !SMP
  365. help
  366. This option selects the RCU implementation that is
  367. designed for UP systems from which real-time response
  368. is not required. This option greatly reduces the
  369. memory footprint of RCU.
  370. config TINY_PREEMPT_RCU
  371. bool "Preemptible UP-only small-memory-footprint RCU"
  372. depends on PREEMPT && !SMP
  373. help
  374. This option selects the RCU implementation that is designed
  375. for real-time UP systems. This option greatly reduces the
  376. memory footprint of RCU.
  377. endchoice
  378. config PREEMPT_RCU
  379. def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
  380. help
  381. This option enables preemptible-RCU code that is common between
  382. the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
  383. config CONTEXT_TRACKING
  384. bool
  385. config RCU_USER_QS
  386. bool "Consider userspace as in RCU extended quiescent state"
  387. depends on HAVE_CONTEXT_TRACKING && SMP
  388. select CONTEXT_TRACKING
  389. help
  390. This option sets hooks on kernel / userspace boundaries and
  391. puts RCU in extended quiescent state when the CPU runs in
  392. userspace. It means that when a CPU runs in userspace, it is
  393. excluded from the global RCU state machine and thus doesn't
  394. try to keep the timer tick on for RCU.
  395. Unless you want to hack and help the development of the full
  396. dynticks mode, you shouldn't enable this option. It also
  397. adds unnecessary overhead.
  398. If unsure say N
  399. config CONTEXT_TRACKING_FORCE
  400. bool "Force context tracking"
  401. depends on CONTEXT_TRACKING
  402. help
  403. Probe on user/kernel boundaries by default in order to
  404. test the features that rely on it such as userspace RCU extended
  405. quiescent states.
  406. This test is there for debugging until we have a real user like the
  407. full dynticks mode.
  408. config RCU_FANOUT
  409. int "Tree-based hierarchical RCU fanout value"
  410. range 2 64 if 64BIT
  411. range 2 32 if !64BIT
  412. depends on TREE_RCU || TREE_PREEMPT_RCU
  413. default 64 if 64BIT
  414. default 32 if !64BIT
  415. help
  416. This option controls the fanout of hierarchical implementations
  417. of RCU, allowing RCU to work efficiently on machines with
  418. large numbers of CPUs. This value must be at least the fourth
  419. root of NR_CPUS, which allows NR_CPUS to be insanely large.
  420. The default value of RCU_FANOUT should be used for production
  421. systems, but if you are stress-testing the RCU implementation
  422. itself, small RCU_FANOUT values allow you to test large-system
  423. code paths on small(er) systems.
  424. Select a specific number if testing RCU itself.
  425. Take the default if unsure.
  426. config RCU_FANOUT_LEAF
  427. int "Tree-based hierarchical RCU leaf-level fanout value"
  428. range 2 RCU_FANOUT if 64BIT
  429. range 2 RCU_FANOUT if !64BIT
  430. depends on TREE_RCU || TREE_PREEMPT_RCU
  431. default 16
  432. help
  433. This option controls the leaf-level fanout of hierarchical
  434. implementations of RCU, and allows trading off cache misses
  435. against lock contention. Systems that synchronize their
  436. scheduling-clock interrupts for energy-efficiency reasons will
  437. want the default because the smaller leaf-level fanout keeps
  438. lock contention levels acceptably low. Very large systems
  439. (hundreds or thousands of CPUs) will instead want to set this
  440. value to the maximum value possible in order to reduce the
  441. number of cache misses incurred during RCU's grace-period
  442. initialization. These systems tend to run CPU-bound, and thus
  443. are not helped by synchronized interrupts, and thus tend to
  444. skew them, which reduces lock contention enough that large
  445. leaf-level fanouts work well.
  446. Select a specific number if testing RCU itself.
  447. Select the maximum permissible value for large systems.
  448. Take the default if unsure.
  449. config RCU_FANOUT_EXACT
  450. bool "Disable tree-based hierarchical RCU auto-balancing"
  451. depends on TREE_RCU || TREE_PREEMPT_RCU
  452. default n
  453. help
  454. This option forces use of the exact RCU_FANOUT value specified,
  455. regardless of imbalances in the hierarchy. This is useful for
  456. testing RCU itself, and might one day be useful on systems with
  457. strong NUMA behavior.
  458. Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
  459. Say N if unsure.
  460. config RCU_FAST_NO_HZ
  461. bool "Accelerate last non-dyntick-idle CPU's grace periods"
  462. depends on NO_HZ && SMP
  463. default n
  464. help
  465. This option causes RCU to attempt to accelerate grace periods in
  466. order to allow CPUs to enter dynticks-idle state more quickly.
  467. On the other hand, this option increases the overhead of the
  468. dynticks-idle checking, thus degrading scheduling latency.
  469. Say Y if energy efficiency is critically important, and you don't
  470. care about real-time response.
  471. Say N if you are unsure.
  472. config TREE_RCU_TRACE
  473. def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
  474. select DEBUG_FS
  475. help
  476. This option provides tracing for the TREE_RCU and
  477. TREE_PREEMPT_RCU implementations, permitting Makefile to
  478. trivially select kernel/rcutree_trace.c.
  479. config RCU_BOOST
  480. bool "Enable RCU priority boosting"
  481. depends on RT_MUTEXES && PREEMPT_RCU
  482. default n
  483. help
  484. This option boosts the priority of preempted RCU readers that
  485. block the current preemptible RCU grace period for too long.
  486. This option also prevents heavy loads from blocking RCU
  487. callback invocation for all flavors of RCU.
  488. Say Y here if you are working with real-time apps or heavy loads
  489. Say N here if you are unsure.
  490. config RCU_BOOST_PRIO
  491. int "Real-time priority to boost RCU readers to"
  492. range 1 99
  493. depends on RCU_BOOST
  494. default 1
  495. help
  496. This option specifies the real-time priority to which long-term
  497. preempted RCU readers are to be boosted. If you are working
  498. with a real-time application that has one or more CPU-bound
  499. threads running at a real-time priority level, you should set
  500. RCU_BOOST_PRIO to a priority higher then the highest-priority
  501. real-time CPU-bound thread. The default RCU_BOOST_PRIO value
  502. of 1 is appropriate in the common case, which is real-time
  503. applications that do not have any CPU-bound threads.
  504. Some real-time applications might not have a single real-time
  505. thread that saturates a given CPU, but instead might have
  506. multiple real-time threads that, taken together, fully utilize
  507. that CPU. In this case, you should set RCU_BOOST_PRIO to
  508. a priority higher than the lowest-priority thread that is
  509. conspiring to prevent the CPU from running any non-real-time
  510. tasks. For example, if one thread at priority 10 and another
  511. thread at priority 5 are between themselves fully consuming
  512. the CPU time on a given CPU, then RCU_BOOST_PRIO should be
  513. set to priority 6 or higher.
  514. Specify the real-time priority, or take the default if unsure.
  515. config RCU_BOOST_DELAY
  516. int "Milliseconds to delay boosting after RCU grace-period start"
  517. range 0 3000
  518. depends on RCU_BOOST
  519. default 500
  520. help
  521. This option specifies the time to wait after the beginning of
  522. a given grace period before priority-boosting preempted RCU
  523. readers blocking that grace period. Note that any RCU reader
  524. blocking an expedited RCU grace period is boosted immediately.
  525. Accept the default if unsure.
  526. config RCU_NOCB_CPU
  527. bool "Offload RCU callback processing from boot-selected CPUs"
  528. depends on TREE_RCU || TREE_PREEMPT_RCU
  529. default n
  530. help
  531. Use this option to reduce OS jitter for aggressive HPC or
  532. real-time workloads. It can also be used to offload RCU
  533. callback invocation to energy-efficient CPUs in battery-powered
  534. asymmetric multiprocessors.
  535. This option offloads callback invocation from the set of
  536. CPUs specified at boot time by the rcu_nocbs parameter.
  537. For each such CPU, a kthread ("rcuoN") will be created to
  538. invoke callbacks, where the "N" is the CPU being offloaded.
  539. Nothing prevents this kthread from running on the specified
  540. CPUs, but (1) the kthreads may be preempted between each
  541. callback, and (2) affinity or cgroups can be used to force
  542. the kthreads to run on whatever set of CPUs is desired.
  543. Say Y here if you want reduced OS jitter on selected CPUs.
  544. Say N here if you are unsure.
  545. endmenu # "RCU Subsystem"
  546. config IKCONFIG
  547. tristate "Kernel .config support"
  548. ---help---
  549. This option enables the complete Linux kernel ".config" file
  550. contents to be saved in the kernel. It provides documentation
  551. of which kernel options are used in a running kernel or in an
  552. on-disk kernel. This information can be extracted from the kernel
  553. image file with the script scripts/extract-ikconfig and used as
  554. input to rebuild the current kernel or to build another kernel.
  555. It can also be extracted from a running kernel by reading
  556. /proc/config.gz if enabled (below).
  557. config IKCONFIG_PROC
  558. bool "Enable access to .config through /proc/config.gz"
  559. depends on IKCONFIG && PROC_FS
  560. ---help---
  561. This option enables access to the kernel configuration file
  562. through /proc/config.gz.
  563. config LOG_BUF_SHIFT
  564. int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
  565. range 12 21
  566. default 17
  567. help
  568. Select kernel log buffer size as a power of 2.
  569. Examples:
  570. 17 => 128 KB
  571. 16 => 64 KB
  572. 15 => 32 KB
  573. 14 => 16 KB
  574. 13 => 8 KB
  575. 12 => 4 KB
  576. #
  577. # Architectures with an unreliable sched_clock() should select this:
  578. #
  579. config HAVE_UNSTABLE_SCHED_CLOCK
  580. bool
  581. #
  582. # For architectures that want to enable the support for NUMA-affine scheduler
  583. # balancing logic:
  584. #
  585. config ARCH_SUPPORTS_NUMA_BALANCING
  586. bool
  587. # For architectures that (ab)use NUMA to represent different memory regions
  588. # all cpu-local but of different latencies, such as SuperH.
  589. #
  590. config ARCH_WANT_NUMA_VARIABLE_LOCALITY
  591. bool
  592. #
  593. # For architectures that are willing to define _PAGE_NUMA as _PAGE_PROTNONE
  594. config ARCH_WANTS_PROT_NUMA_PROT_NONE
  595. bool
  596. config ARCH_USES_NUMA_PROT_NONE
  597. bool
  598. default y
  599. depends on ARCH_WANTS_PROT_NUMA_PROT_NONE
  600. depends on NUMA_BALANCING
  601. config NUMA_BALANCING_DEFAULT_ENABLED
  602. bool "Automatically enable NUMA aware memory/task placement"
  603. default y
  604. depends on NUMA_BALANCING
  605. help
  606. If set, autonumic NUMA balancing will be enabled if running on a NUMA
  607. machine.
  608. config NUMA_BALANCING
  609. bool "Memory placement aware NUMA scheduler"
  610. depends on ARCH_SUPPORTS_NUMA_BALANCING
  611. depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
  612. depends on SMP && NUMA && MIGRATION
  613. help
  614. This option adds support for automatic NUMA aware memory/task placement.
  615. The mechanism is quite primitive and is based on migrating memory when
  616. it is references to the node the task is running on.
  617. This system will be inactive on UMA systems.
  618. menuconfig CGROUPS
  619. boolean "Control Group support"
  620. depends on EVENTFD
  621. help
  622. This option adds support for grouping sets of processes together, for
  623. use with process control subsystems such as Cpusets, CFS, memory
  624. controls or device isolation.
  625. See
  626. - Documentation/scheduler/sched-design-CFS.txt (CFS)
  627. - Documentation/cgroups/ (features for grouping, isolation
  628. and resource control)
  629. Say N if unsure.
  630. if CGROUPS
  631. config CGROUP_DEBUG
  632. bool "Example debug cgroup subsystem"
  633. default n
  634. help
  635. This option enables a simple cgroup subsystem that
  636. exports useful debugging information about the cgroups
  637. framework.
  638. Say N if unsure.
  639. config CGROUP_FREEZER
  640. bool "Freezer cgroup subsystem"
  641. help
  642. Provides a way to freeze and unfreeze all tasks in a
  643. cgroup.
  644. config CGROUP_DEVICE
  645. bool "Device controller for cgroups"
  646. help
  647. Provides a cgroup implementing whitelists for devices which
  648. a process in the cgroup can mknod or open.
  649. config CPUSETS
  650. bool "Cpuset support"
  651. help
  652. This option will let you create and manage CPUSETs which
  653. allow dynamically partitioning a system into sets of CPUs and
  654. Memory Nodes and assigning tasks to run only within those sets.
  655. This is primarily useful on large SMP or NUMA systems.
  656. Say N if unsure.
  657. config PROC_PID_CPUSET
  658. bool "Include legacy /proc/<pid>/cpuset file"
  659. depends on CPUSETS
  660. default y
  661. config CGROUP_CPUACCT
  662. bool "Simple CPU accounting cgroup subsystem"
  663. help
  664. Provides a simple Resource Controller for monitoring the
  665. total CPU consumed by the tasks in a cgroup.
  666. config RESOURCE_COUNTERS
  667. bool "Resource counters"
  668. help
  669. This option enables controller independent resource accounting
  670. infrastructure that works with cgroups.
  671. config MEMCG
  672. bool "Memory Resource Controller for Control Groups"
  673. depends on RESOURCE_COUNTERS
  674. select MM_OWNER
  675. help
  676. Provides a memory resource controller that manages both anonymous
  677. memory and page cache. (See Documentation/cgroups/memory.txt)
  678. Note that setting this option increases fixed memory overhead
  679. associated with each page of memory in the system. By this,
  680. 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
  681. usage tracking struct at boot. Total amount of this is printed out
  682. at boot.
  683. Only enable when you're ok with these trade offs and really
  684. sure you need the memory resource controller. Even when you enable
  685. this, you can set "cgroup_disable=memory" at your boot option to
  686. disable memory resource controller and you can avoid overheads.
  687. (and lose benefits of memory resource controller)
  688. This config option also selects MM_OWNER config option, which
  689. could in turn add some fork/exit overhead.
  690. config MEMCG_SWAP
  691. bool "Memory Resource Controller Swap Extension"
  692. depends on MEMCG && SWAP
  693. help
  694. Add swap management feature to memory resource controller. When you
  695. enable this, you can limit mem+swap usage per cgroup. In other words,
  696. when you disable this, memory resource controller has no cares to
  697. usage of swap...a process can exhaust all of the swap. This extension
  698. is useful when you want to avoid exhaustion swap but this itself
  699. adds more overheads and consumes memory for remembering information.
  700. Especially if you use 32bit system or small memory system, please
  701. be careful about enabling this. When memory resource controller
  702. is disabled by boot option, this will be automatically disabled and
  703. there will be no overhead from this. Even when you set this config=y,
  704. if boot option "swapaccount=0" is set, swap will not be accounted.
  705. Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
  706. size is 4096bytes, 512k per 1Gbytes of swap.
  707. config MEMCG_SWAP_ENABLED
  708. bool "Memory Resource Controller Swap Extension enabled by default"
  709. depends on MEMCG_SWAP
  710. default y
  711. help
  712. Memory Resource Controller Swap Extension comes with its price in
  713. a bigger memory consumption. General purpose distribution kernels
  714. which want to enable the feature but keep it disabled by default
  715. and let the user enable it by swapaccount boot command line
  716. parameter should have this option unselected.
  717. For those who want to have the feature enabled by default should
  718. select this option (if, for some reason, they need to disable it
  719. then swapaccount=0 does the trick).
  720. config MEMCG_KMEM
  721. bool "Memory Resource Controller Kernel Memory accounting"
  722. depends on MEMCG
  723. depends on SLUB || SLAB
  724. help
  725. The Kernel Memory extension for Memory Resource Controller can limit
  726. the amount of memory used by kernel objects in the system. Those are
  727. fundamentally different from the entities handled by the standard
  728. Memory Controller, which are page-based, and can be swapped. Users of
  729. the kmem extension can use it to guarantee that no group of processes
  730. will ever exhaust kernel resources alone.
  731. config CGROUP_HUGETLB
  732. bool "HugeTLB Resource Controller for Control Groups"
  733. depends on RESOURCE_COUNTERS && HUGETLB_PAGE
  734. default n
  735. help
  736. Provides a cgroup Resource Controller for HugeTLB pages.
  737. When you enable this, you can put a per cgroup limit on HugeTLB usage.
  738. The limit is enforced during page fault. Since HugeTLB doesn't
  739. support page reclaim, enforcing the limit at page fault time implies
  740. that, the application will get SIGBUS signal if it tries to access
  741. HugeTLB pages beyond its limit. This requires the application to know
  742. beforehand how much HugeTLB pages it would require for its use. The
  743. control group is tracked in the third page lru pointer. This means
  744. that we cannot use the controller with huge page less than 3 pages.
  745. config CGROUP_PERF
  746. bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
  747. depends on PERF_EVENTS && CGROUPS
  748. help
  749. This option extends the per-cpu mode to restrict monitoring to
  750. threads which belong to the cgroup specified and run on the
  751. designated cpu.
  752. Say N if unsure.
  753. menuconfig CGROUP_SCHED
  754. bool "Group CPU scheduler"
  755. default n
  756. help
  757. This feature lets CPU scheduler recognize task groups and control CPU
  758. bandwidth allocation to such task groups. It uses cgroups to group
  759. tasks.
  760. if CGROUP_SCHED
  761. config FAIR_GROUP_SCHED
  762. bool "Group scheduling for SCHED_OTHER"
  763. depends on CGROUP_SCHED
  764. default CGROUP_SCHED
  765. config CFS_BANDWIDTH
  766. bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
  767. depends on FAIR_GROUP_SCHED
  768. default n
  769. help
  770. This option allows users to define CPU bandwidth rates (limits) for
  771. tasks running within the fair group scheduler. Groups with no limit
  772. set are considered to be unconstrained and will run with no
  773. restriction.
  774. See tip/Documentation/scheduler/sched-bwc.txt for more information.
  775. config RT_GROUP_SCHED
  776. bool "Group scheduling for SCHED_RR/FIFO"
  777. depends on CGROUP_SCHED
  778. default n
  779. help
  780. This feature lets you explicitly allocate real CPU bandwidth
  781. to task groups. If enabled, it will also make it impossible to
  782. schedule realtime tasks for non-root users until you allocate
  783. realtime bandwidth for them.
  784. See Documentation/scheduler/sched-rt-group.txt for more information.
  785. endif #CGROUP_SCHED
  786. config BLK_CGROUP
  787. bool "Block IO controller"
  788. depends on BLOCK
  789. default n
  790. ---help---
  791. Generic block IO controller cgroup interface. This is the common
  792. cgroup interface which should be used by various IO controlling
  793. policies.
  794. Currently, CFQ IO scheduler uses it to recognize task groups and
  795. control disk bandwidth allocation (proportional time slice allocation)
  796. to such task groups. It is also used by bio throttling logic in
  797. block layer to implement upper limit in IO rates on a device.
  798. This option only enables generic Block IO controller infrastructure.
  799. One needs to also enable actual IO controlling logic/policy. For
  800. enabling proportional weight division of disk bandwidth in CFQ, set
  801. CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
  802. CONFIG_BLK_DEV_THROTTLING=y.
  803. See Documentation/cgroups/blkio-controller.txt for more information.
  804. config DEBUG_BLK_CGROUP
  805. bool "Enable Block IO controller debugging"
  806. depends on BLK_CGROUP
  807. default n
  808. ---help---
  809. Enable some debugging help. Currently it exports additional stat
  810. files in a cgroup which can be useful for debugging.
  811. endif # CGROUPS
  812. config CHECKPOINT_RESTORE
  813. bool "Checkpoint/restore support" if EXPERT
  814. default n
  815. help
  816. Enables additional kernel features in a sake of checkpoint/restore.
  817. In particular it adds auxiliary prctl codes to setup process text,
  818. data and heap segment sizes, and a few additional /proc filesystem
  819. entries.
  820. If unsure, say N here.
  821. menuconfig NAMESPACES
  822. bool "Namespaces support" if EXPERT
  823. default !EXPERT
  824. help
  825. Provides the way to make tasks work with different objects using
  826. the same id. For example same IPC id may refer to different objects
  827. or same user id or pid may refer to different tasks when used in
  828. different namespaces.
  829. if NAMESPACES
  830. config UTS_NS
  831. bool "UTS namespace"
  832. default y
  833. help
  834. In this namespace tasks see different info provided with the
  835. uname() system call
  836. config IPC_NS
  837. bool "IPC namespace"
  838. depends on (SYSVIPC || POSIX_MQUEUE)
  839. default y
  840. help
  841. In this namespace tasks work with IPC ids which correspond to
  842. different IPC objects in different namespaces.
  843. config USER_NS
  844. bool "User namespace"
  845. depends on UIDGID_CONVERTED
  846. select UIDGID_STRICT_TYPE_CHECKS
  847. default n
  848. help
  849. This allows containers, i.e. vservers, to use user namespaces
  850. to provide different user info for different servers.
  851. If unsure, say N.
  852. config PID_NS
  853. bool "PID Namespaces"
  854. default y
  855. help
  856. Support process id namespaces. This allows having multiple
  857. processes with the same pid as long as they are in different
  858. pid namespaces. This is a building block of containers.
  859. config NET_NS
  860. bool "Network namespace"
  861. depends on NET
  862. default y
  863. help
  864. Allow user space to create what appear to be multiple instances
  865. of the network stack.
  866. endif # NAMESPACES
  867. config UIDGID_CONVERTED
  868. # True if all of the selected software conmponents are known
  869. # to have uid_t and gid_t converted to kuid_t and kgid_t
  870. # where appropriate and are otherwise safe to use with
  871. # the user namespace.
  872. bool
  873. default y
  874. # Networking
  875. depends on NET_9P = n
  876. # Filesystems
  877. depends on 9P_FS = n
  878. depends on AFS_FS = n
  879. depends on CEPH_FS = n
  880. depends on CIFS = n
  881. depends on CODA_FS = n
  882. depends on GFS2_FS = n
  883. depends on NCP_FS = n
  884. depends on NFSD = n
  885. depends on NFS_FS = n
  886. depends on OCFS2_FS = n
  887. depends on XFS_FS = n
  888. config UIDGID_STRICT_TYPE_CHECKS
  889. bool "Require conversions between uid/gids and their internal representation"
  890. depends on UIDGID_CONVERTED
  891. default n
  892. help
  893. While the nececessary conversions are being added to all subsystems this option allows
  894. the code to continue to build for unconverted subsystems.
  895. Say Y here if you want the strict type checking enabled
  896. config SCHED_AUTOGROUP
  897. bool "Automatic process group scheduling"
  898. select EVENTFD
  899. select CGROUPS
  900. select CGROUP_SCHED
  901. select FAIR_GROUP_SCHED
  902. help
  903. This option optimizes the scheduler for common desktop workloads by
  904. automatically creating and populating task groups. This separation
  905. of workloads isolates aggressive CPU burners (like build jobs) from
  906. desktop applications. Task group autogeneration is currently based
  907. upon task session.
  908. config MM_OWNER
  909. bool
  910. config SYSFS_DEPRECATED
  911. bool "Enable deprecated sysfs features to support old userspace tools"
  912. depends on SYSFS
  913. default n
  914. help
  915. This option adds code that switches the layout of the "block" class
  916. devices, to not show up in /sys/class/block/, but only in
  917. /sys/block/.
  918. This switch is only active when the sysfs.deprecated=1 boot option is
  919. passed or the SYSFS_DEPRECATED_V2 option is set.
  920. This option allows new kernels to run on old distributions and tools,
  921. which might get confused by /sys/class/block/. Since 2007/2008 all
  922. major distributions and tools handle this just fine.
  923. Recent distributions and userspace tools after 2009/2010 depend on
  924. the existence of /sys/class/block/, and will not work with this
  925. option enabled.
  926. Only if you are using a new kernel on an old distribution, you might
  927. need to say Y here.
  928. config SYSFS_DEPRECATED_V2
  929. bool "Enable deprecated sysfs features by default"
  930. default n
  931. depends on SYSFS
  932. depends on SYSFS_DEPRECATED
  933. help
  934. Enable deprecated sysfs by default.
  935. See the CONFIG_SYSFS_DEPRECATED option for more details about this
  936. option.
  937. Only if you are using a new kernel on an old distribution, you might
  938. need to say Y here. Even then, odds are you would not need it
  939. enabled, you can always pass the boot option if absolutely necessary.
  940. config RELAY
  941. bool "Kernel->user space relay support (formerly relayfs)"
  942. help
  943. This option enables support for relay interface support in
  944. certain file systems (such as debugfs).
  945. It is designed to provide an efficient mechanism for tools and
  946. facilities to relay large amounts of data from kernel space to
  947. user space.
  948. If unsure, say N.
  949. config BLK_DEV_INITRD
  950. bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
  951. depends on BROKEN || !FRV
  952. help
  953. The initial RAM filesystem is a ramfs which is loaded by the
  954. boot loader (loadlin or lilo) and that is mounted as root
  955. before the normal boot procedure. It is typically used to
  956. load modules needed to mount the "real" root file system,
  957. etc. See <file:Documentation/initrd.txt> for details.
  958. If RAM disk support (BLK_DEV_RAM) is also included, this
  959. also enables initial RAM disk (initrd) support and adds
  960. 15 Kbytes (more on some other architectures) to the kernel size.
  961. If unsure say Y.
  962. if BLK_DEV_INITRD
  963. source "usr/Kconfig"
  964. endif
  965. config CC_OPTIMIZE_FOR_SIZE
  966. bool "Optimize for size"
  967. help
  968. Enabling this option will pass "-Os" instead of "-O2" to gcc
  969. resulting in a smaller kernel.
  970. If unsure, say Y.
  971. config SYSCTL
  972. bool
  973. config ANON_INODES
  974. bool
  975. menuconfig EXPERT
  976. bool "Configure standard kernel features (expert users)"
  977. # Unhide debug options, to make the on-by-default options visible
  978. select DEBUG_KERNEL
  979. help
  980. This option allows certain base kernel options and settings
  981. to be disabled or tweaked. This is for specialized
  982. environments which can tolerate a "non-standard" kernel.
  983. Only use this if you really know what you are doing.
  984. config HAVE_UID16
  985. bool
  986. config UID16
  987. bool "Enable 16-bit UID system calls" if EXPERT
  988. depends on HAVE_UID16
  989. default y
  990. help
  991. This enables the legacy 16-bit UID syscall wrappers.
  992. config SYSCTL_SYSCALL
  993. bool "Sysctl syscall support" if EXPERT
  994. depends on PROC_SYSCTL
  995. default n
  996. select SYSCTL
  997. ---help---
  998. sys_sysctl uses binary paths that have been found challenging
  999. to properly maintain and use. The interface in /proc/sys
  1000. using paths with ascii names is now the primary path to this
  1001. information.
  1002. Almost nothing using the binary sysctl interface so if you are
  1003. trying to save some space it is probably safe to disable this,
  1004. making your kernel marginally smaller.
  1005. If unsure say N here.
  1006. config SYSCTL_EXCEPTION_TRACE
  1007. bool
  1008. help
  1009. Enable support for /proc/sys/debug/exception-trace.
  1010. config KALLSYMS
  1011. bool "Load all symbols for debugging/ksymoops" if EXPERT
  1012. default y
  1013. help
  1014. Say Y here to let the kernel print out symbolic crash information and
  1015. symbolic stack backtraces. This increases the size of the kernel
  1016. somewhat, as all symbols have to be loaded into the kernel image.
  1017. config KALLSYMS_ALL
  1018. bool "Include all symbols in kallsyms"
  1019. depends on DEBUG_KERNEL && KALLSYMS
  1020. help
  1021. Normally kallsyms only contains the symbols of functions for nicer
  1022. OOPS messages and backtraces (i.e., symbols from the text and inittext
  1023. sections). This is sufficient for most cases. And only in very rare
  1024. cases (e.g., when a debugger is used) all symbols are required (e.g.,
  1025. names of variables from the data sections, etc).
  1026. This option makes sure that all symbols are loaded into the kernel
  1027. image (i.e., symbols from all sections) in cost of increased kernel
  1028. size (depending on the kernel configuration, it may be 300KiB or
  1029. something like this).
  1030. Say N unless you really need all symbols.
  1031. config HOTPLUG
  1032. def_bool y
  1033. config PRINTK
  1034. default y
  1035. bool "Enable support for printk" if EXPERT
  1036. help
  1037. This option enables normal printk support. Removing it
  1038. eliminates most of the message strings from the kernel image
  1039. and makes the kernel more or less silent. As this makes it
  1040. very difficult to diagnose system problems, saying N here is
  1041. strongly discouraged.
  1042. config BUG
  1043. bool "BUG() support" if EXPERT
  1044. default y
  1045. help
  1046. Disabling this option eliminates support for BUG and WARN, reducing
  1047. the size of your kernel image and potentially quietly ignoring
  1048. numerous fatal conditions. You should only consider disabling this
  1049. option for embedded systems with no facilities for reporting errors.
  1050. Just say Y.
  1051. config ELF_CORE
  1052. depends on COREDUMP
  1053. default y
  1054. bool "Enable ELF core dumps" if EXPERT
  1055. help
  1056. Enable support for generating core dumps. Disabling saves about 4k.
  1057. config PCSPKR_PLATFORM
  1058. bool "Enable PC-Speaker support" if EXPERT
  1059. depends on HAVE_PCSPKR_PLATFORM
  1060. select I8253_LOCK
  1061. default y
  1062. help
  1063. This option allows to disable the internal PC-Speaker
  1064. support, saving some memory.
  1065. config HAVE_PCSPKR_PLATFORM
  1066. bool
  1067. config BASE_FULL
  1068. default y
  1069. bool "Enable full-sized data structures for core" if EXPERT
  1070. help
  1071. Disabling this option reduces the size of miscellaneous core
  1072. kernel data structures. This saves memory on small machines,
  1073. but may reduce performance.
  1074. config FUTEX
  1075. bool "Enable futex support" if EXPERT
  1076. default y
  1077. select RT_MUTEXES
  1078. help
  1079. Disabling this option will cause the kernel to be built without
  1080. support for "fast userspace mutexes". The resulting kernel may not
  1081. run glibc-based applications correctly.
  1082. config EPOLL
  1083. bool "Enable eventpoll support" if EXPERT
  1084. default y
  1085. select ANON_INODES
  1086. help
  1087. Disabling this option will cause the kernel to be built without
  1088. support for epoll family of system calls.
  1089. config SIGNALFD
  1090. bool "Enable signalfd() system call" if EXPERT
  1091. select ANON_INODES
  1092. default y
  1093. help
  1094. Enable the signalfd() system call that allows to receive signals
  1095. on a file descriptor.
  1096. If unsure, say Y.
  1097. config TIMERFD
  1098. bool "Enable timerfd() system call" if EXPERT
  1099. select ANON_INODES
  1100. default y
  1101. help
  1102. Enable the timerfd() system call that allows to receive timer
  1103. events on a file descriptor.
  1104. If unsure, say Y.
  1105. config EVENTFD
  1106. bool "Enable eventfd() system call" if EXPERT
  1107. select ANON_INODES
  1108. default y
  1109. help
  1110. Enable the eventfd() system call that allows to receive both
  1111. kernel notification (ie. KAIO) or userspace notifications.
  1112. If unsure, say Y.
  1113. config SHMEM
  1114. bool "Use full shmem filesystem" if EXPERT
  1115. default y
  1116. depends on MMU
  1117. help
  1118. The shmem is an internal filesystem used to manage shared memory.
  1119. It is backed by swap and manages resource limits. It is also exported
  1120. to userspace as tmpfs if TMPFS is enabled. Disabling this
  1121. option replaces shmem and tmpfs with the much simpler ramfs code,
  1122. which may be appropriate on small systems without swap.
  1123. config AIO
  1124. bool "Enable AIO support" if EXPERT
  1125. default y
  1126. help
  1127. This option enables POSIX asynchronous I/O which may by used
  1128. by some high performance threaded applications. Disabling
  1129. this option saves about 7k.
  1130. config EMBEDDED
  1131. bool "Embedded system"
  1132. select EXPERT
  1133. help
  1134. This option should be enabled if compiling the kernel for
  1135. an embedded system so certain expert options are available
  1136. for configuration.
  1137. config HAVE_PERF_EVENTS
  1138. bool
  1139. help
  1140. See tools/perf/design.txt for details.
  1141. config PERF_USE_VMALLOC
  1142. bool
  1143. help
  1144. See tools/perf/design.txt for details
  1145. menu "Kernel Performance Events And Counters"
  1146. config PERF_EVENTS
  1147. bool "Kernel performance events and counters"
  1148. default y if PROFILING
  1149. depends on HAVE_PERF_EVENTS
  1150. select ANON_INODES
  1151. select IRQ_WORK
  1152. help
  1153. Enable kernel support for various performance events provided
  1154. by software and hardware.
  1155. Software events are supported either built-in or via the
  1156. use of generic tracepoints.
  1157. Most modern CPUs support performance events via performance
  1158. counter registers. These registers count the number of certain
  1159. types of hw events: such as instructions executed, cachemisses
  1160. suffered, or branches mis-predicted - without slowing down the
  1161. kernel or applications. These registers can also trigger interrupts
  1162. when a threshold number of events have passed - and can thus be
  1163. used to profile the code that runs on that CPU.
  1164. The Linux Performance Event subsystem provides an abstraction of
  1165. these software and hardware event capabilities, available via a
  1166. system call and used by the "perf" utility in tools/perf/. It
  1167. provides per task and per CPU counters, and it provides event
  1168. capabilities on top of those.
  1169. Say Y if unsure.
  1170. config DEBUG_PERF_USE_VMALLOC
  1171. default n
  1172. bool "Debug: use vmalloc to back perf mmap() buffers"
  1173. depends on PERF_EVENTS && DEBUG_KERNEL
  1174. select PERF_USE_VMALLOC
  1175. help
  1176. Use vmalloc memory to back perf mmap() buffers.
  1177. Mostly useful for debugging the vmalloc code on platforms
  1178. that don't require it.
  1179. Say N if unsure.
  1180. endmenu
  1181. config VM_EVENT_COUNTERS
  1182. default y
  1183. bool "Enable VM event counters for /proc/vmstat" if EXPERT
  1184. help
  1185. VM event counters are needed for event counts to be shown.
  1186. This option allows the disabling of the VM event counters
  1187. on EXPERT systems. /proc/vmstat will only show page counts
  1188. if VM event counters are disabled.
  1189. config PCI_QUIRKS
  1190. default y
  1191. bool "Enable PCI quirk workarounds" if EXPERT
  1192. depends on PCI
  1193. help
  1194. This enables workarounds for various PCI chipset
  1195. bugs/quirks. Disable this only if your target machine is
  1196. unaffected by PCI quirks.
  1197. config SLUB_DEBUG
  1198. default y
  1199. bool "Enable SLUB debugging support" if EXPERT
  1200. depends on SLUB && SYSFS
  1201. help
  1202. SLUB has extensive debug support features. Disabling these can
  1203. result in significant savings in code size. This also disables
  1204. SLUB sysfs support. /sys/slab will not exist and there will be
  1205. no support for cache validation etc.
  1206. config COMPAT_BRK
  1207. bool "Disable heap randomization"
  1208. default y
  1209. help
  1210. Randomizing heap placement makes heap exploits harder, but it
  1211. also breaks ancient binaries (including anything libc5 based).
  1212. This option changes the bootup default to heap randomization
  1213. disabled, and can be overridden at runtime by setting
  1214. /proc/sys/kernel/randomize_va_space to 2.
  1215. On non-ancient distros (post-2000 ones) N is usually a safe choice.
  1216. choice
  1217. prompt "Choose SLAB allocator"
  1218. default SLUB
  1219. help
  1220. This option allows to select a slab allocator.
  1221. config SLAB
  1222. bool "SLAB"
  1223. help
  1224. The regular slab allocator that is established and known to work
  1225. well in all environments. It organizes cache hot objects in
  1226. per cpu and per node queues.
  1227. config SLUB
  1228. bool "SLUB (Unqueued Allocator)"
  1229. help
  1230. SLUB is a slab allocator that minimizes cache line usage
  1231. instead of managing queues of cached objects (SLAB approach).
  1232. Per cpu caching is realized using slabs of objects instead
  1233. of queues of objects. SLUB can use memory efficiently
  1234. and has enhanced diagnostics. SLUB is the default choice for
  1235. a slab allocator.
  1236. config SLOB
  1237. depends on EXPERT
  1238. bool "SLOB (Simple Allocator)"
  1239. help
  1240. SLOB replaces the stock allocator with a drastically simpler
  1241. allocator. SLOB is generally more space efficient but
  1242. does not perform as well on large systems.
  1243. endchoice
  1244. config MMAP_ALLOW_UNINITIALIZED
  1245. bool "Allow mmapped anonymous memory to be uninitialized"
  1246. depends on EXPERT && !MMU
  1247. default n
  1248. help
  1249. Normally, and according to the Linux spec, anonymous memory obtained
  1250. from mmap() has it's contents cleared before it is passed to
  1251. userspace. Enabling this config option allows you to request that
  1252. mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
  1253. providing a huge performance boost. If this option is not enabled,
  1254. then the flag will be ignored.
  1255. This is taken advantage of by uClibc's malloc(), and also by
  1256. ELF-FDPIC binfmt's brk and stack allocator.
  1257. Because of the obvious security issues, this option should only be
  1258. enabled on embedded devices where you control what is run in
  1259. userspace. Since that isn't generally a problem on no-MMU systems,
  1260. it is normally safe to say Y here.
  1261. See Documentation/nommu-mmap.txt for more information.
  1262. config PROFILING
  1263. bool "Profiling support"
  1264. help
  1265. Say Y here to enable the extended profiling support mechanisms used
  1266. by profilers such as OProfile.
  1267. #
  1268. # Place an empty function call at each tracepoint site. Can be
  1269. # dynamically changed for a probe function.
  1270. #
  1271. config TRACEPOINTS
  1272. bool
  1273. source "arch/Kconfig"
  1274. endmenu # General setup
  1275. config HAVE_GENERIC_DMA_COHERENT
  1276. bool
  1277. default n
  1278. config SLABINFO
  1279. bool
  1280. depends on PROC_FS
  1281. depends on SLAB || SLUB_DEBUG
  1282. default y
  1283. config RT_MUTEXES
  1284. boolean
  1285. config BASE_SMALL
  1286. int
  1287. default 0 if BASE_FULL
  1288. default 1 if !BASE_FULL
  1289. menuconfig MODULES
  1290. bool "Enable loadable module support"
  1291. help
  1292. Kernel modules are small pieces of compiled code which can
  1293. be inserted in the running kernel, rather than being
  1294. permanently built into the kernel. You use the "modprobe"
  1295. tool to add (and sometimes remove) them. If you say Y here,
  1296. many parts of the kernel can be built as modules (by
  1297. answering M instead of Y where indicated): this is most
  1298. useful for infrequently used options which are not required
  1299. for booting. For more information, see the man pages for
  1300. modprobe, lsmod, modinfo, insmod and rmmod.
  1301. If you say Y here, you will need to run "make
  1302. modules_install" to put the modules under /lib/modules/
  1303. where modprobe can find them (you may need to be root to do
  1304. this).
  1305. If unsure, say Y.
  1306. if MODULES
  1307. config MODULE_FORCE_LOAD
  1308. bool "Forced module loading"
  1309. default n
  1310. help
  1311. Allow loading of modules without version information (ie. modprobe
  1312. --force). Forced module loading sets the 'F' (forced) taint flag and
  1313. is usually a really bad idea.
  1314. config MODULE_UNLOAD
  1315. bool "Module unloading"
  1316. help
  1317. Without this option you will not be able to unload any
  1318. modules (note that some modules may not be unloadable
  1319. anyway), which makes your kernel smaller, faster
  1320. and simpler. If unsure, say Y.
  1321. config MODULE_FORCE_UNLOAD
  1322. bool "Forced module unloading"
  1323. depends on MODULE_UNLOAD
  1324. help
  1325. This option allows you to force a module to unload, even if the
  1326. kernel believes it is unsafe: the kernel will remove the module
  1327. without waiting for anyone to stop using it (using the -f option to
  1328. rmmod). This is mainly for kernel developers and desperate users.
  1329. If unsure, say N.
  1330. config MODVERSIONS
  1331. bool "Module versioning support"
  1332. help
  1333. Usually, you have to use modules compiled with your kernel.
  1334. Saying Y here makes it sometimes possible to use modules
  1335. compiled for different kernels, by adding enough information
  1336. to the modules to (hopefully) spot any changes which would
  1337. make them incompatible with the kernel you are running. If
  1338. unsure, say N.
  1339. config MODULE_SRCVERSION_ALL
  1340. bool "Source checksum for all modules"
  1341. help
  1342. Modules which contain a MODULE_VERSION get an extra "srcversion"
  1343. field inserted into their modinfo section, which contains a
  1344. sum of the source files which made it. This helps maintainers
  1345. see exactly which source was used to build a module (since
  1346. others sometimes change the module source without updating
  1347. the version). With this option, such a "srcversion" field
  1348. will be created for all modules. If unsure, say N.
  1349. config MODULE_SIG
  1350. bool "Module signature verification"
  1351. depends on MODULES
  1352. select KEYS
  1353. select CRYPTO
  1354. select ASYMMETRIC_KEY_TYPE
  1355. select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
  1356. select PUBLIC_KEY_ALGO_RSA
  1357. select ASN1
  1358. select OID_REGISTRY
  1359. select X509_CERTIFICATE_PARSER
  1360. help
  1361. Check modules for valid signatures upon load: the signature
  1362. is simply appended to the module. For more information see
  1363. Documentation/module-signing.txt.
  1364. !!!WARNING!!! If you enable this option, you MUST make sure that the
  1365. module DOES NOT get stripped after being signed. This includes the
  1366. debuginfo strip done by some packagers (such as rpmbuild) and
  1367. inclusion into an initramfs that wants the module size reduced.
  1368. config MODULE_SIG_FORCE
  1369. bool "Require modules to be validly signed"
  1370. depends on MODULE_SIG
  1371. help
  1372. Reject unsigned modules or signed modules for which we don't have a
  1373. key. Without this, such modules will simply taint the kernel.
  1374. choice
  1375. prompt "Which hash algorithm should modules be signed with?"
  1376. depends on MODULE_SIG
  1377. help
  1378. This determines which sort of hashing algorithm will be used during
  1379. signature generation. This algorithm _must_ be built into the kernel
  1380. directly so that signature verification can take place. It is not
  1381. possible to load a signed module containing the algorithm to check
  1382. the signature on that module.
  1383. config MODULE_SIG_SHA1
  1384. bool "Sign modules with SHA-1"
  1385. select CRYPTO_SHA1
  1386. config MODULE_SIG_SHA224
  1387. bool "Sign modules with SHA-224"
  1388. select CRYPTO_SHA256
  1389. config MODULE_SIG_SHA256
  1390. bool "Sign modules with SHA-256"
  1391. select CRYPTO_SHA256
  1392. config MODULE_SIG_SHA384
  1393. bool "Sign modules with SHA-384"
  1394. select CRYPTO_SHA512
  1395. config MODULE_SIG_SHA512
  1396. bool "Sign modules with SHA-512"
  1397. select CRYPTO_SHA512
  1398. endchoice
  1399. endif # MODULES
  1400. config INIT_ALL_POSSIBLE
  1401. bool
  1402. help
  1403. Back when each arch used to define their own cpu_online_mask and
  1404. cpu_possible_mask, some of them chose to initialize cpu_possible_mask
  1405. with all 1s, and others with all 0s. When they were centralised,
  1406. it was better to provide this option than to break all the archs
  1407. and have several arch maintainers pursuing me down dark alleys.
  1408. config STOP_MACHINE
  1409. bool
  1410. default y
  1411. depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
  1412. help
  1413. Need stop_machine() primitive.
  1414. source "block/Kconfig"
  1415. config PREEMPT_NOTIFIERS
  1416. bool
  1417. config PADATA
  1418. depends on SMP
  1419. bool
  1420. # Can be selected by architectures with broken toolchains
  1421. # that get confused by correct const<->read_only section
  1422. # mappings
  1423. config BROKEN_RODATA
  1424. bool
  1425. config ASN1
  1426. tristate
  1427. help
  1428. Build a simple ASN.1 grammar compiler that produces a bytecode output
  1429. that can be interpreted by the ASN.1 stream decoder and used to
  1430. inform it as to what tags are to be expected in a stream and what
  1431. functions to call on what tags.
  1432. source "kernel/Kconfig.locks"