| blob | dcc96a8c8c697451412d811a759b0a3683c265f8 |
1 config ARCH
2 string
3 option env="ARCH"
5 config KERNELVERSION
6 string
7 option env="KERNELVERSION"
9 config DEFCONFIG_LIST
10 string
11 depends on !UML
12 option defconfig_list
13 default "/lib/modules/$UNAME_RELEASE/.config"
14 default "/etc/kernel-config"
15 default "/boot/config-$UNAME_RELEASE"
16 default "arch/$ARCH/defconfig"
18 menu "General setup"
20 config EXPERIMENTAL
21 bool "Prompt for development and/or incomplete code/drivers"
22 ---help---
23 Some of the various things that Linux supports (such as network
24 drivers, file systems, network protocols, etc.) can be in a state
25 of development where the functionality, stability, or the level of
26 testing is not yet high enough for general use. This is usually
27 known as the "alpha-test" phase among developers. If a feature is
28 currently in alpha-test, then the developers usually discourage
29 uninformed widespread use of this feature by the general public to
30 avoid "Why doesn't this work?" type mail messages. However, active
31 testing and use of these systems is welcomed. Just be aware that it
32 may not meet the normal level of reliability or it may fail to work
33 in some special cases. Detailed bug reports from people familiar
34 with the kernel internals are usually welcomed by the developers
35 (before submitting bug reports, please read the documents
36 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
37 <file:Documentation/BUG-HUNTING>, and
38 <file:Documentation/oops-tracing.txt> in the kernel source).
40 This option will also make obsoleted drivers available. These are
41 drivers that have been replaced by something else, and/or are
42 scheduled to be removed in a future kernel release.
44 Unless you intend to help test and develop a feature or driver that
45 falls into this category, or you have a situation that requires
46 using these features, you should probably say N here, which will
47 cause the configurator to present you with fewer choices. If
48 you say Y here, you will be offered the choice of using features or
49 drivers that are currently considered to be in the alpha-test phase.
51 config BROKEN
52 bool
54 config BROKEN_ON_SMP
55 bool
56 depends on BROKEN || !SMP
57 default y
59 config LOCK_KERNEL
60 bool
61 depends on SMP || PREEMPT
62 default y
64 config INIT_ENV_ARG_LIMIT
65 int
66 default 32 if !UML
67 default 128 if UML
68 help
69 Maximum of each of the number of arguments and environment
70 variables passed to init from the kernel command line.
73 config LOCALVERSION
74 string "Local version - append to kernel release"
75 help
76 Append an extra string to the end of your kernel version.
77 This will show up when you type uname, for example.
78 The string you set here will be appended after the contents of
79 any files with a filename matching localversion* in your
80 object and source tree, in that order. Your total string can
81 be a maximum of 64 characters.
83 config LOCALVERSION_AUTO
84 bool "Automatically append version information to the version string"
85 default y
86 help
87 This will try to automatically determine if the current tree is a
88 release tree by looking for git tags that belong to the current
89 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.
96 (The actual string used here is the first eight characters produced
97 by running the command:
99 $ git rev-parse --verify HEAD
101 which is done within the script "scripts/setlocalversion".)
103 config SWAP
104 bool "Support for paging of anonymous memory (swap)"
105 depends on MMU && BLOCK
106 default y
107 help
108 This option allows you to choose whether you want to have support
109 for so called swap devices or swap files in your kernel that are
110 used to provide more virtual memory than the actual RAM present
111 in your computer. If unsure say Y.
113 config SYSVIPC
114 bool "System V IPC"
115 ---help---
116 Inter Process Communication is a suite of library functions and
117 system calls which let processes (running programs) synchronize and
118 exchange information. It is generally considered to be a good thing,
119 and some programs won't run unless you say Y here. In particular, if
120 you want to run the DOS emulator dosemu under Linux (read the
121 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
122 you'll need to say Y here.
124 You can find documentation about IPC with "info ipc" and also in
125 section 6.4 of the Linux Programmer's Guide, available from
126 <http://www.tldp.org/guides.html>.
128 config SYSVIPC_SYSCTL
129 bool
130 depends on SYSVIPC
131 depends on SYSCTL
132 default y
134 config POSIX_MQUEUE
135 bool "POSIX Message Queues"
136 depends on NET && EXPERIMENTAL
137 ---help---
138 POSIX variant of message queues is a part of IPC. In POSIX message
139 queues every message has a priority which decides about succession
140 of receiving it by a process. If you want to compile and run
141 programs written e.g. for Solaris with use of its POSIX message
142 queues (functions mq_*) say Y here.
144 POSIX message queues are visible as a filesystem called 'mqueue'
145 and can be mounted somewhere if you want to do filesystem
146 operations on message queues.
148 If unsure, say Y.
150 config BSD_PROCESS_ACCT
151 bool "BSD Process Accounting"
152 help
153 If you say Y here, a user level program will be able to instruct the
154 kernel (via a special system call) to write process accounting
155 information to a file: whenever a process exits, information about
156 that process will be appended to the file by the kernel. The
157 information includes things such as creation time, owning user,
158 command name, memory usage, controlling terminal etc. (the complete
159 list is in the struct acct in <file:include/linux/acct.h>). It is
160 up to the user level program to do useful things with this
161 information. This is generally a good idea, so say Y.
163 config BSD_PROCESS_ACCT_V3
164 bool "BSD Process Accounting version 3 file format"
165 depends on BSD_PROCESS_ACCT
166 default n
167 help
168 If you say Y here, the process accounting information is written
169 in a new file format that also logs the process IDs of each
170 process and it's parent. Note that this file format is incompatible
171 with previous v0/v1/v2 file formats, so you will need updated tools
172 for processing it. A preliminary version of these tools is available
173 at <http://www.physik3.uni-rostock.de/tim/kernel/utils/acct/>.
175 config TASKSTATS
176 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
177 depends on NET
178 default n
179 help
180 Export selected statistics for tasks/processes through the
181 generic netlink interface. Unlike BSD process accounting, the
182 statistics are available during the lifetime of tasks/processes as
183 responses to commands. Like BSD accounting, they are sent to user
184 space on task exit.
186 Say N if unsure.
188 config TASK_DELAY_ACCT
189 bool "Enable per-task delay accounting (EXPERIMENTAL)"
190 depends on TASKSTATS
191 help
192 Collect information on time spent by a task waiting for system
193 resources like cpu, synchronous block I/O completion and swapping
194 in pages. Such statistics can help in setting a task's priorities
195 relative to other tasks for cpu, io, rss limits etc.
197 Say N if unsure.
199 config TASK_XACCT
200 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
201 depends on TASKSTATS
202 help
203 Collect extended task accounting data and send the data
204 to userland for processing over the taskstats interface.
206 Say N if unsure.
208 config TASK_IO_ACCOUNTING
209 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
210 depends on TASK_XACCT
211 help
212 Collect information on the number of bytes of storage I/O which this
213 task has caused.
215 Say N if unsure.
217 config USER_NS
218 bool "User Namespaces (EXPERIMENTAL)"
219 default n
220 depends on EXPERIMENTAL
221 help
222 Support user namespaces. This allows containers, i.e.
223 vservers, to use user namespaces to provide different
224 user info for different servers. If unsure, say N.
226 config PID_NS
227 bool "PID Namespaces (EXPERIMENTAL)"
228 default n
229 depends on EXPERIMENTAL
230 help
231 Suport process id namespaces. This allows having multiple
232 process with the same pid as long as they are in different
233 pid namespaces. This is a building block of containers.
235 Unless you want to work with an experimental feature
236 say N here.
238 config AUDIT
239 bool "Auditing support"
240 depends on NET
241 help
242 Enable auditing infrastructure that can be used with another
243 kernel subsystem, such as SELinux (which requires this for
244 logging of avc messages output). Does not do system-call
245 auditing without CONFIG_AUDITSYSCALL.
247 config AUDITSYSCALL
248 bool "Enable system-call auditing support"
249 depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64|| SUPERH)
250 default y if SECURITY_SELINUX
251 help
252 Enable low-overhead system-call auditing infrastructure that
253 can be used independently or with another kernel subsystem,
254 such as SELinux. To use audit's filesystem watch feature, please
255 ensure that INOTIFY is configured.
257 config AUDIT_TREE
258 def_bool y
259 depends on AUDITSYSCALL && INOTIFY
261 config IKCONFIG
262 tristate "Kernel .config support"
263 ---help---
264 This option enables the complete Linux kernel ".config" file
265 contents to be saved in the kernel. It provides documentation
266 of which kernel options are used in a running kernel or in an
267 on-disk kernel. This information can be extracted from the kernel
268 image file with the script scripts/extract-ikconfig and used as
269 input to rebuild the current kernel or to build another kernel.
270 It can also be extracted from a running kernel by reading
271 /proc/config.gz if enabled (below).
273 config IKCONFIG_PROC
274 bool "Enable access to .config through /proc/config.gz"
275 depends on IKCONFIG && PROC_FS
276 ---help---
277 This option enables access to the kernel configuration file
278 through /proc/config.gz.
280 config LOG_BUF_SHIFT
281 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
282 range 12 21
283 default 17 if S390 || LOCKDEP
284 default 16 if X86_NUMAQ || IA64
285 default 15 if SMP
286 default 14
287 help
288 Select kernel log buffer size as a power of 2.
289 Defaults and Examples:
290 17 => 128 KB for S/390
291 16 => 64 KB for x86 NUMAQ or IA-64
292 15 => 32 KB for SMP
293 14 => 16 KB for uniprocessor
294 13 => 8 KB
295 12 => 4 KB
297 config CGROUPS
298 bool "Control Group support"
299 help
300 This option will let you use process cgroup subsystems
301 such as Cpusets
303 Say N if unsure.
305 config CGROUP_DEBUG
306 bool "Example debug cgroup subsystem"
307 depends on CGROUPS
308 help
309 This option enables a simple cgroup subsystem that
310 exports useful debugging information about the cgroups
311 framework
313 Say N if unsure
315 config CGROUP_NS
316 bool "Namespace cgroup subsystem"
317 depends on CGROUPS
318 help
319 Provides a simple namespace cgroup subsystem to
320 provide hierarchical naming of sets of namespaces,
321 for instance virtual servers and checkpoint/restart
322 jobs.
324 config CPUSETS
325 bool "Cpuset support"
326 depends on SMP && CGROUPS
327 help
328 This option will let you create and manage CPUSETs which
329 allow dynamically partitioning a system into sets of CPUs and
330 Memory Nodes and assigning tasks to run only within those sets.
331 This is primarily useful on large SMP or NUMA systems.
333 Say N if unsure.
335 config FAIR_GROUP_SCHED
336 bool "Fair group CPU scheduler"
337 default y
338 help
339 This feature lets CPU scheduler recognize task groups and control CPU
340 bandwidth allocation to such task groups.
342 choice
343 depends on FAIR_GROUP_SCHED
344 prompt "Basis for grouping tasks"
345 default FAIR_USER_SCHED
347 config FAIR_USER_SCHED
348 bool "user id"
349 help
350 This option will choose userid as the basis for grouping
351 tasks, thus providing equal CPU bandwidth to each user.
353 config FAIR_CGROUP_SCHED
354 bool "Control groups"
355 depends on CGROUPS
356 help
357 This option allows you to create arbitrary task groups
358 using the "cgroup" pseudo filesystem and control
359 the cpu bandwidth allocated to each such task group.
360 Refer to Documentation/cgroups.txt for more information
361 on "cgroup" pseudo filesystem.
363 endchoice
365 config CGROUP_CPUACCT
366 bool "Simple CPU accounting cgroup subsystem"
367 depends on CGROUPS
368 help
369 Provides a simple Resource Controller for monitoring the
370 total CPU consumed by the tasks in a cgroup
372 config SYSFS_DEPRECATED
373 bool "Create deprecated sysfs files"
374 depends on SYSFS
375 default y
376 help
377 This option creates deprecated symlinks such as the
378 "device"-link, the <subsystem>:<name>-link, and the
379 "bus"-link. It may also add deprecated key in the
380 uevent environment.
381 None of these features or values should be used today, as
382 they export driver core implementation details to userspace
383 or export properties which can't be kept stable across kernel
384 releases.
386 If enabled, this option will also move any device structures
387 that belong to a class, back into the /sys/class hierarchy, in
388 order to support older versions of udev.
390 If you are using a distro that was released in 2006 or later,
391 it should be safe to say N here.
393 config PROC_PID_CPUSET
394 bool "Include legacy /proc/<pid>/cpuset file"
395 depends on CPUSETS
396 default y
398 config RELAY
399 bool "Kernel->user space relay support (formerly relayfs)"
400 help
401 This option enables support for relay interface support in
402 certain file systems (such as debugfs).
403 It is designed to provide an efficient mechanism for tools and
404 facilities to relay large amounts of data from kernel space to
405 user space.
407 If unsure, say N.
409 config BLK_DEV_INITRD
410 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
411 depends on BROKEN || !FRV
412 help
413 The initial RAM filesystem is a ramfs which is loaded by the
414 boot loader (loadlin or lilo) and that is mounted as root
415 before the normal boot procedure. It is typically used to
416 load modules needed to mount the "real" root file system,
417 etc. See <file:Documentation/initrd.txt> for details.
419 If RAM disk support (BLK_DEV_RAM) is also included, this
420 also enables initial RAM disk (initrd) support and adds
421 15 Kbytes (more on some other architectures) to the kernel size.
423 If unsure say Y.
425 if BLK_DEV_INITRD
427 source "usr/Kconfig"
429 endif
431 config CC_OPTIMIZE_FOR_SIZE
432 bool "Optimize for size (Look out for broken compilers!)"
433 default y
434 depends on ARM || H8300 || SUPERH || EXPERIMENTAL
435 help
436 Enabling this option will pass "-Os" instead of "-O2" to gcc
437 resulting in a smaller kernel.
439 WARNING: some versions of gcc may generate incorrect code with this
440 option. If problems are observed, a gcc upgrade may be needed.
442 If unsure, say N.
444 config SYSCTL
445 bool
447 menuconfig EMBEDDED
448 bool "Configure standard kernel features (for small systems)"
449 help
450 This option allows certain base kernel options and settings
451 to be disabled or tweaked. This is for specialized
452 environments which can tolerate a "non-standard" kernel.
453 Only use this if you really know what you are doing.
455 config UID16
456 bool "Enable 16-bit UID system calls" if EMBEDDED
457 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_COMPAT) || UML || (X86_64 && IA32_EMULATION)
458 default y
459 help
460 This enables the legacy 16-bit UID syscall wrappers.
462 config SYSCTL_SYSCALL
463 bool "Sysctl syscall support" if EMBEDDED
464 default y
465 select SYSCTL
466 ---help---
467 sys_sysctl uses binary paths that have been found challenging
468 to properly maintain and use. The interface in /proc/sys
469 using paths with ascii names is now the primary path to this
470 information.
472 Almost nothing using the binary sysctl interface so if you are
473 trying to save some space it is probably safe to disable this,
474 making your kernel marginally smaller.
476 If unsure say Y here.
478 config KALLSYMS
479 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
480 default y
481 help
482 Say Y here to let the kernel print out symbolic crash information and
483 symbolic stack backtraces. This increases the size of the kernel
484 somewhat, as all symbols have to be loaded into the kernel image.
486 config KALLSYMS_ALL
487 bool "Include all symbols in kallsyms"
488 depends on DEBUG_KERNEL && KALLSYMS
489 help
490 Normally kallsyms only contains the symbols of functions, for nicer
491 OOPS messages. Some debuggers can use kallsyms for other
492 symbols too: say Y here to include all symbols, if you need them
493 and you don't care about adding 300k to the size of your kernel.
495 Say N.
497 config KALLSYMS_EXTRA_PASS
498 bool "Do an extra kallsyms pass"
499 depends on KALLSYMS
500 help
501 If kallsyms is not working correctly, the build will fail with
502 inconsistent kallsyms data. If that occurs, log a bug report and
503 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
504 Always say N here unless you find a bug in kallsyms, which must be
505 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
506 you wait for kallsyms to be fixed.
509 config HOTPLUG
510 bool "Support for hot-pluggable devices" if EMBEDDED
511 default y
512 help
513 This option is provided for the case where no hotplug or uevent
514 capabilities is wanted by the kernel. You should only consider
515 disabling this option for embedded systems that do not use modules, a
516 dynamic /dev tree, or dynamic device discovery. Just say Y.
518 config PRINTK
519 default y
520 bool "Enable support for printk" if EMBEDDED
521 help
522 This option enables normal printk support. Removing it
523 eliminates most of the message strings from the kernel image
524 and makes the kernel more or less silent. As this makes it
525 very difficult to diagnose system problems, saying N here is
526 strongly discouraged.
528 config BUG
529 bool "BUG() support" if EMBEDDED
530 default y
531 help
532 Disabling this option eliminates support for BUG and WARN, reducing
533 the size of your kernel image and potentially quietly ignoring
534 numerous fatal conditions. You should only consider disabling this
535 option for embedded systems with no facilities for reporting errors.
536 Just say Y.
538 config ELF_CORE
539 default y
540 bool "Enable ELF core dumps" if EMBEDDED
541 help
542 Enable support for generating core dumps. Disabling saves about 4k.
544 config BASE_FULL
545 default y
546 bool "Enable full-sized data structures for core" if EMBEDDED
547 help
548 Disabling this option reduces the size of miscellaneous core
549 kernel data structures. This saves memory on small machines,
550 but may reduce performance.
552 config FUTEX
553 bool "Enable futex support" if EMBEDDED
554 default y
555 select RT_MUTEXES
556 help
557 Disabling this option will cause the kernel to be built without
558 support for "fast userspace mutexes". The resulting kernel may not
559 run glibc-based applications correctly.
561 config ANON_INODES
562 bool
564 config EPOLL
565 bool "Enable eventpoll support" if EMBEDDED
566 default y
567 select ANON_INODES
568 help
569 Disabling this option will cause the kernel to be built without
570 support for epoll family of system calls.
572 config SIGNALFD
573 bool "Enable signalfd() system call" if EMBEDDED
574 select ANON_INODES
575 default y
576 help
577 Enable the signalfd() system call that allows to receive signals
578 on a file descriptor.
580 If unsure, say Y.
582 config TIMERFD
583 bool "Enable timerfd() system call" if EMBEDDED
584 select ANON_INODES
585 depends on BROKEN
586 default y
587 help
588 Enable the timerfd() system call that allows to receive timer
589 events on a file descriptor.
591 If unsure, say Y.
593 config EVENTFD
594 bool "Enable eventfd() system call" if EMBEDDED
595 select ANON_INODES
596 default y
597 help
598 Enable the eventfd() system call that allows to receive both
599 kernel notification (ie. KAIO) or userspace notifications.
601 If unsure, say Y.
603 config SHMEM
604 bool "Use full shmem filesystem" if EMBEDDED
605 default y
606 depends on MMU
607 help
608 The shmem is an internal filesystem used to manage shared memory.
609 It is backed by swap and manages resource limits. It is also exported
610 to userspace as tmpfs if TMPFS is enabled. Disabling this
611 option replaces shmem and tmpfs with the much simpler ramfs code,
612 which may be appropriate on small systems without swap.
614 config VM_EVENT_COUNTERS
615 default y
616 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
617 help
618 VM event counters are needed for event counts to be shown.
619 This option allows the disabling of the VM event counters
620 on EMBEDDED systems. /proc/vmstat will only show page counts
621 if VM event counters are disabled.
623 config SLUB_DEBUG
624 default y
625 bool "Enable SLUB debugging support" if EMBEDDED
626 depends on SLUB
627 help
628 SLUB has extensive debug support features. Disabling these can
629 result in significant savings in code size. This also disables
630 SLUB sysfs support. /sys/slab will not exist and there will be
631 no support for cache validation etc.
633 choice
634 prompt "Choose SLAB allocator"
635 default SLUB
636 help
637 This option allows to select a slab allocator.
639 config SLAB
640 bool "SLAB"
641 help
642 The regular slab allocator that is established and known to work
643 well in all environments. It organizes cache hot objects in
644 per cpu and per node queues. SLAB is the default choice for
645 a slab allocator.
647 config SLUB
648 bool "SLUB (Unqueued Allocator)"
649 help
650 SLUB is a slab allocator that minimizes cache line usage
651 instead of managing queues of cached objects (SLAB approach).
652 Per cpu caching is realized using slabs of objects instead
653 of queues of objects. SLUB can use memory efficiently
654 and has enhanced diagnostics.
656 config SLOB
657 depends on EMBEDDED
658 bool "SLOB (Simple Allocator)"
659 help
660 SLOB replaces the SLAB allocator with a drastically simpler
661 allocator. SLOB is more space efficient than SLAB but does not
662 scale well (single lock for all operations) and is also highly
663 susceptible to fragmentation. SLUB can accomplish a higher object
664 density. It is usually better to use SLUB instead of SLOB.
666 endchoice
668 endmenu # General setup
670 config SLABINFO
671 bool
672 depends on PROC_FS
673 depends on SLAB || SLUB
674 default y
676 config RT_MUTEXES
677 boolean
678 select PLIST
680 config TINY_SHMEM
681 default !SHMEM
682 bool
684 config BASE_SMALL
685 int
686 default 0 if BASE_FULL
687 default 1 if !BASE_FULL
689 menuconfig MODULES
690 bool "Enable loadable module support"
691 help
692 Kernel modules are small pieces of compiled code which can
693 be inserted in the running kernel, rather than being
694 permanently built into the kernel. You use the "modprobe"
695 tool to add (and sometimes remove) them. If you say Y here,
696 many parts of the kernel can be built as modules (by
697 answering M instead of Y where indicated): this is most
698 useful for infrequently used options which are not required
699 for booting. For more information, see the man pages for
700 modprobe, lsmod, modinfo, insmod and rmmod.
702 If you say Y here, you will need to run "make
703 modules_install" to put the modules under /lib/modules/
704 where modprobe can find them (you may need to be root to do
705 this).
707 If unsure, say Y.
709 config MODULE_UNLOAD
710 bool "Module unloading"
711 depends on MODULES
712 help
713 Without this option you will not be able to unload any
714 modules (note that some modules may not be unloadable
715 anyway), which makes your kernel slightly smaller and
716 simpler. If unsure, say Y.
718 config MODULE_FORCE_UNLOAD
719 bool "Forced module unloading"
720 depends on MODULE_UNLOAD && EXPERIMENTAL
721 help
722 This option allows you to force a module to unload, even if the
723 kernel believes it is unsafe: the kernel will remove the module
724 without waiting for anyone to stop using it (using the -f option to
725 rmmod). This is mainly for kernel developers and desperate users.
726 If unsure, say N.
728 config MODVERSIONS
729 bool "Module versioning support"
730 depends on MODULES
731 help
732 Usually, you have to use modules compiled with your kernel.
733 Saying Y here makes it sometimes possible to use modules
734 compiled for different kernels, by adding enough information
735 to the modules to (hopefully) spot any changes which would
736 make them incompatible with the kernel you are running. If
737 unsure, say N.
739 config MODULE_SRCVERSION_ALL
740 bool "Source checksum for all modules"
741 depends on MODULES
742 help
743 Modules which contain a MODULE_VERSION get an extra "srcversion"
744 field inserted into their modinfo section, which contains a
745 sum of the source files which made it. This helps maintainers
746 see exactly which source was used to build a module (since
747 others sometimes change the module source without updating
748 the version). With this option, such a "srcversion" field
749 will be created for all modules. If unsure, say N.
751 config KMOD
752 bool "Automatic kernel module loading"
753 depends on MODULES
754 help
755 Normally when you have selected some parts of the kernel to
756 be created as kernel modules, you must load them (using the
757 "modprobe" command) before you can use them. If you say Y
758 here, some parts of the kernel will be able to load modules
759 automatically: when a part of the kernel needs a module, it
760 runs modprobe with the appropriate arguments, thereby
761 loading the module if it is available. If unsure, say Y.
763 config STOP_MACHINE
764 bool
765 default y
766 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
767 help
768 Need stop_machine() primitive.
770 source "block/Kconfig"
772 config PREEMPT_NOTIFIERS
773 bool
775 choice
776 prompt "RCU implementation type:"
777 default CLASSIC_RCU
778 help
779 This allows you to choose either the classic RCU implementation
780 that is designed for best read-side performance on non-realtime
781 systems, or the preemptible RCU implementation for best latency
782 on realtime systems. Note that some kernel preemption modes
783 will restrict your choice.
785 Select the default if you are unsure.
787 config CLASSIC_RCU
788 bool "Classic RCU"
789 help
790 This option selects the classic RCU implementation that is
791 designed for best read-side performance on non-realtime
792 systems.
794 Say Y if you are unsure.
796 config PREEMPT_RCU
797 bool "Preemptible RCU"
798 depends on PREEMPT
799 help
800 This option reduces the latency of the kernel by making certain
801 RCU sections preemptible. Normally RCU code is non-preemptible, if
802 this option is selected then read-only RCU sections become
803 preemptible. This helps latency, but may expose bugs due to
804 now-naive assumptions about each RCU read-side critical section
805 remaining on a given CPU through its execution.
807 Say N if you are unsure.
809 endchoice