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1 config DEFCONFIG_LIST
2 string
3 depends on !UML
4 option defconfig_list
5 default "/lib/modules/$UNAME_RELEASE/.config"
6 default "/etc/kernel-config"
7 default "/boot/config-$UNAME_RELEASE"
8 default "arch/$ARCH/defconfig"
10 menu "General setup"
12 config EXPERIMENTAL
13 bool "Prompt for development and/or incomplete code/drivers"
14 ---help---
15 Some of the various things that Linux supports (such as network
16 drivers, file systems, network protocols, etc.) can be in a state
17 of development where the functionality, stability, or the level of
18 testing is not yet high enough for general use. This is usually
19 known as the "alpha-test" phase among developers. If a feature is
20 currently in alpha-test, then the developers usually discourage
21 uninformed widespread use of this feature by the general public to
22 avoid "Why doesn't this work?" type mail messages. However, active
23 testing and use of these systems is welcomed. Just be aware that it
24 may not meet the normal level of reliability or it may fail to work
25 in some special cases. Detailed bug reports from people familiar
26 with the kernel internals are usually welcomed by the developers
27 (before submitting bug reports, please read the documents
28 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
29 <file:Documentation/BUG-HUNTING>, and
30 <file:Documentation/oops-tracing.txt> in the kernel source).
32 This option will also make obsoleted drivers available. These are
33 drivers that have been replaced by something else, and/or are
34 scheduled to be removed in a future kernel release.
36 Unless you intend to help test and develop a feature or driver that
37 falls into this category, or you have a situation that requires
38 using these features, you should probably say N here, which will
39 cause the configurator to present you with fewer choices. If
40 you say Y here, you will be offered the choice of using features or
41 drivers that are currently considered to be in the alpha-test phase.
43 config BROKEN
44 bool
46 config BROKEN_ON_SMP
47 bool
48 depends on BROKEN || !SMP
49 default y
51 config LOCK_KERNEL
52 bool
53 depends on SMP || PREEMPT
54 default y
56 config INIT_ENV_ARG_LIMIT
57 int
58 default 32 if !UML
59 default 128 if UML
60 help
61 Maximum of each of the number of arguments and environment
62 variables passed to init from the kernel command line.
65 config LOCALVERSION
66 string "Local version - append to kernel release"
67 help
68 Append an extra string to the end of your kernel version.
69 This will show up when you type uname, for example.
70 The string you set here will be appended after the contents of
71 any files with a filename matching localversion* in your
72 object and source tree, in that order. Your total string can
73 be a maximum of 64 characters.
75 config LOCALVERSION_AUTO
76 bool "Automatically append version information to the version string"
77 default y
78 help
79 This will try to automatically determine if the current tree is a
80 release tree by looking for git tags that belong to the current
81 top of tree revision.
83 A string of the format -gxxxxxxxx will be added to the localversion
84 if a git-based tree is found. The string generated by this will be
85 appended after any matching localversion* files, and after the value
86 set in CONFIG_LOCALVERSION.
88 (The actual string used here is the first eight characters produced
89 by running the command:
91 $ git rev-parse --verify HEAD
93 which is done within the script "scripts/setlocalversion".)
95 config SWAP
96 bool "Support for paging of anonymous memory (swap)"
97 depends on MMU && BLOCK
98 default y
99 help
100 This option allows you to choose whether you want to have support
101 for so called swap devices or swap files in your kernel that are
102 used to provide more virtual memory than the actual RAM present
103 in your computer. If unsure say Y.
105 config SYSVIPC
106 bool "System V IPC"
107 ---help---
108 Inter Process Communication is a suite of library functions and
109 system calls which let processes (running programs) synchronize and
110 exchange information. It is generally considered to be a good thing,
111 and some programs won't run unless you say Y here. In particular, if
112 you want to run the DOS emulator dosemu under Linux (read the
113 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
114 you'll need to say Y here.
116 You can find documentation about IPC with "info ipc" and also in
117 section 6.4 of the Linux Programmer's Guide, available from
118 <http://www.tldp.org/guides.html>.
120 config SYSVIPC_SYSCTL
121 bool
122 depends on SYSVIPC
123 depends on SYSCTL
124 default y
126 config POSIX_MQUEUE
127 bool "POSIX Message Queues"
128 depends on NET && EXPERIMENTAL
129 ---help---
130 POSIX variant of message queues is a part of IPC. In POSIX message
131 queues every message has a priority which decides about succession
132 of receiving it by a process. If you want to compile and run
133 programs written e.g. for Solaris with use of its POSIX message
134 queues (functions mq_*) say Y here.
136 POSIX message queues are visible as a filesystem called 'mqueue'
137 and can be mounted somewhere if you want to do filesystem
138 operations on message queues.
140 If unsure, say Y.
142 config BSD_PROCESS_ACCT
143 bool "BSD Process Accounting"
144 help
145 If you say Y here, a user level program will be able to instruct the
146 kernel (via a special system call) to write process accounting
147 information to a file: whenever a process exits, information about
148 that process will be appended to the file by the kernel. The
149 information includes things such as creation time, owning user,
150 command name, memory usage, controlling terminal etc. (the complete
151 list is in the struct acct in <file:include/linux/acct.h>). It is
152 up to the user level program to do useful things with this
153 information. This is generally a good idea, so say Y.
155 config BSD_PROCESS_ACCT_V3
156 bool "BSD Process Accounting version 3 file format"
157 depends on BSD_PROCESS_ACCT
158 default n
159 help
160 If you say Y here, the process accounting information is written
161 in a new file format that also logs the process IDs of each
162 process and it's parent. Note that this file format is incompatible
163 with previous v0/v1/v2 file formats, so you will need updated tools
164 for processing it. A preliminary version of these tools is available
165 at <http://www.physik3.uni-rostock.de/tim/kernel/utils/acct/>.
167 config TASKSTATS
168 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
169 depends on NET
170 default n
171 help
172 Export selected statistics for tasks/processes through the
173 generic netlink interface. Unlike BSD process accounting, the
174 statistics are available during the lifetime of tasks/processes as
175 responses to commands. Like BSD accounting, they are sent to user
176 space on task exit.
178 Say N if unsure.
180 config TASK_DELAY_ACCT
181 bool "Enable per-task delay accounting (EXPERIMENTAL)"
182 depends on TASKSTATS
183 help
184 Collect information on time spent by a task waiting for system
185 resources like cpu, synchronous block I/O completion and swapping
186 in pages. Such statistics can help in setting a task's priorities
187 relative to other tasks for cpu, io, rss limits etc.
189 Say N if unsure.
191 config TASK_XACCT
192 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
193 depends on TASKSTATS
194 help
195 Collect extended task accounting data and send the data
196 to userland for processing over the taskstats interface.
198 Say N if unsure.
200 config TASK_IO_ACCOUNTING
201 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
202 depends on TASK_XACCT
203 help
204 Collect information on the number of bytes of storage I/O which this
205 task has caused.
207 Say N if unsure.
209 config USER_NS
210 bool "User Namespaces (EXPERIMENTAL)"
211 default n
212 depends on EXPERIMENTAL
213 help
214 Support user namespaces. This allows containers, i.e.
215 vservers, to use user namespaces to provide different
216 user info for different servers. If unsure, say N.
218 config AUDIT
219 bool "Auditing support"
220 depends on NET
221 help
222 Enable auditing infrastructure that can be used with another
223 kernel subsystem, such as SELinux (which requires this for
224 logging of avc messages output). Does not do system-call
225 auditing without CONFIG_AUDITSYSCALL.
227 config AUDITSYSCALL
228 bool "Enable system-call auditing support"
229 depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64)
230 default y if SECURITY_SELINUX
231 help
232 Enable low-overhead system-call auditing infrastructure that
233 can be used independently or with another kernel subsystem,
234 such as SELinux. To use audit's filesystem watch feature, please
235 ensure that INOTIFY is configured.
237 config IKCONFIG
238 tristate "Kernel .config support"
239 ---help---
240 This option enables the complete Linux kernel ".config" file
241 contents to be saved in the kernel. It provides documentation
242 of which kernel options are used in a running kernel or in an
243 on-disk kernel. This information can be extracted from the kernel
244 image file with the script scripts/extract-ikconfig and used as
245 input to rebuild the current kernel or to build another kernel.
246 It can also be extracted from a running kernel by reading
247 /proc/config.gz if enabled (below).
249 config IKCONFIG_PROC
250 bool "Enable access to .config through /proc/config.gz"
251 depends on IKCONFIG && PROC_FS
252 ---help---
253 This option enables access to the kernel configuration file
254 through /proc/config.gz.
256 config LOG_BUF_SHIFT
257 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
258 range 12 21
259 default 17 if S390 || LOCKDEP
260 default 16 if X86_NUMAQ || IA64
261 default 15 if SMP
262 default 14
263 help
264 Select kernel log buffer size as a power of 2.
265 Defaults and Examples:
266 17 => 128 KB for S/390
267 16 => 64 KB for x86 NUMAQ or IA-64
268 15 => 32 KB for SMP
269 14 => 16 KB for uniprocessor
270 13 => 8 KB
271 12 => 4 KB
273 config CPUSETS
274 bool "Cpuset support"
275 depends on SMP
276 help
277 This option will let you create and manage CPUSETs which
278 allow dynamically partitioning a system into sets of CPUs and
279 Memory Nodes and assigning tasks to run only within those sets.
280 This is primarily useful on large SMP or NUMA systems.
282 Say N if unsure.
284 config FAIR_GROUP_SCHED
285 bool "Fair group CPU scheduler"
286 default y
287 depends on EXPERIMENTAL
288 help
289 This feature lets CPU scheduler recognize task groups and control CPU
290 bandwidth allocation to such task groups.
292 choice
293 depends on FAIR_GROUP_SCHED
294 prompt "Basis for grouping tasks"
295 default FAIR_USER_SCHED
297 config FAIR_USER_SCHED
298 bool "user id"
299 help
300 This option will choose userid as the basis for grouping
301 tasks, thus providing equal CPU bandwidth to each user.
303 endchoice
305 config SYSFS_DEPRECATED
306 bool "Create deprecated sysfs files"
307 default y
308 help
309 This option creates deprecated symlinks such as the
310 "device"-link, the <subsystem>:<name>-link, and the
311 "bus"-link. It may also add deprecated key in the
312 uevent environment.
313 None of these features or values should be used today, as
314 they export driver core implementation details to userspace
315 or export properties which can't be kept stable across kernel
316 releases.
318 If enabled, this option will also move any device structures
319 that belong to a class, back into the /sys/class hierarchy, in
320 order to support older versions of udev.
322 If you are using a distro that was released in 2006 or later,
323 it should be safe to say N here.
325 config RELAY
326 bool "Kernel->user space relay support (formerly relayfs)"
327 help
328 This option enables support for relay interface support in
329 certain file systems (such as debugfs).
330 It is designed to provide an efficient mechanism for tools and
331 facilities to relay large amounts of data from kernel space to
332 user space.
334 If unsure, say N.
336 config BLK_DEV_INITRD
337 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
338 depends on BROKEN || !FRV
339 help
340 The initial RAM filesystem is a ramfs which is loaded by the
341 boot loader (loadlin or lilo) and that is mounted as root
342 before the normal boot procedure. It is typically used to
343 load modules needed to mount the "real" root file system,
344 etc. See <file:Documentation/initrd.txt> for details.
346 If RAM disk support (BLK_DEV_RAM) is also included, this
347 also enables initial RAM disk (initrd) support and adds
348 15 Kbytes (more on some other architectures) to the kernel size.
350 If unsure say Y.
352 if BLK_DEV_INITRD
354 source "usr/Kconfig"
356 endif
358 config CC_OPTIMIZE_FOR_SIZE
359 bool "Optimize for size (Look out for broken compilers!)"
360 default y
361 depends on ARM || H8300 || SUPERH || EXPERIMENTAL
362 help
363 Enabling this option will pass "-Os" instead of "-O2" to gcc
364 resulting in a smaller kernel.
366 WARNING: some versions of gcc may generate incorrect code with this
367 option. If problems are observed, a gcc upgrade may be needed.
369 If unsure, say N.
371 config SYSCTL
372 bool
374 menuconfig EMBEDDED
375 bool "Configure standard kernel features (for small systems)"
376 help
377 This option allows certain base kernel options and settings
378 to be disabled or tweaked. This is for specialized
379 environments which can tolerate a "non-standard" kernel.
380 Only use this if you really know what you are doing.
382 config UID16
383 bool "Enable 16-bit UID system calls" if EMBEDDED
384 depends on ARM || BFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_COMPAT) || UML || (X86_64 && IA32_EMULATION)
385 default y
386 help
387 This enables the legacy 16-bit UID syscall wrappers.
389 config SYSCTL_SYSCALL
390 bool "Sysctl syscall support" if EMBEDDED
391 default y
392 select SYSCTL
393 ---help---
394 sys_sysctl uses binary paths that have been found challenging
395 to properly maintain and use. The interface in /proc/sys
396 using paths with ascii names is now the primary path to this
397 information.
399 Almost nothing using the binary sysctl interface so if you are
400 trying to save some space it is probably safe to disable this,
401 making your kernel marginally smaller.
403 If unsure say Y here.
405 config KALLSYMS
406 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
407 default y
408 help
409 Say Y here to let the kernel print out symbolic crash information and
410 symbolic stack backtraces. This increases the size of the kernel
411 somewhat, as all symbols have to be loaded into the kernel image.
413 config KALLSYMS_ALL
414 bool "Include all symbols in kallsyms"
415 depends on DEBUG_KERNEL && KALLSYMS
416 help
417 Normally kallsyms only contains the symbols of functions, for nicer
418 OOPS messages. Some debuggers can use kallsyms for other
419 symbols too: say Y here to include all symbols, if you need them
420 and you don't care about adding 300k to the size of your kernel.
422 Say N.
424 config KALLSYMS_EXTRA_PASS
425 bool "Do an extra kallsyms pass"
426 depends on KALLSYMS
427 help
428 If kallsyms is not working correctly, the build will fail with
429 inconsistent kallsyms data. If that occurs, log a bug report and
430 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
431 Always say N here unless you find a bug in kallsyms, which must be
432 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
433 you wait for kallsyms to be fixed.
436 config HOTPLUG
437 bool "Support for hot-pluggable devices" if EMBEDDED
438 default y
439 help
440 This option is provided for the case where no hotplug or uevent
441 capabilities is wanted by the kernel. You should only consider
442 disabling this option for embedded systems that do not use modules, a
443 dynamic /dev tree, or dynamic device discovery. Just say Y.
445 config PRINTK
446 default y
447 bool "Enable support for printk" if EMBEDDED
448 help
449 This option enables normal printk support. Removing it
450 eliminates most of the message strings from the kernel image
451 and makes the kernel more or less silent. As this makes it
452 very difficult to diagnose system problems, saying N here is
453 strongly discouraged.
455 config BUG
456 bool "BUG() support" if EMBEDDED
457 default y
458 help
459 Disabling this option eliminates support for BUG and WARN, reducing
460 the size of your kernel image and potentially quietly ignoring
461 numerous fatal conditions. You should only consider disabling this
462 option for embedded systems with no facilities for reporting errors.
463 Just say Y.
465 config ELF_CORE
466 default y
467 bool "Enable ELF core dumps" if EMBEDDED
468 help
469 Enable support for generating core dumps. Disabling saves about 4k.
471 config BASE_FULL
472 default y
473 bool "Enable full-sized data structures for core" if EMBEDDED
474 help
475 Disabling this option reduces the size of miscellaneous core
476 kernel data structures. This saves memory on small machines,
477 but may reduce performance.
479 config FUTEX
480 bool "Enable futex support" if EMBEDDED
481 default y
482 select RT_MUTEXES
483 help
484 Disabling this option will cause the kernel to be built without
485 support for "fast userspace mutexes". The resulting kernel may not
486 run glibc-based applications correctly.
488 config ANON_INODES
489 bool
491 config EPOLL
492 bool "Enable eventpoll support" if EMBEDDED
493 default y
494 select ANON_INODES
495 help
496 Disabling this option will cause the kernel to be built without
497 support for epoll family of system calls.
499 config SIGNALFD
500 bool "Enable signalfd() system call" if EMBEDDED
501 select ANON_INODES
502 default y
503 help
504 Enable the signalfd() system call that allows to receive signals
505 on a file descriptor.
507 If unsure, say Y.
509 config TIMERFD
510 bool "Enable timerfd() system call" if EMBEDDED
511 select ANON_INODES
512 depends on BROKEN
513 default y
514 help
515 Enable the timerfd() system call that allows to receive timer
516 events on a file descriptor.
518 If unsure, say Y.
520 config EVENTFD
521 bool "Enable eventfd() system call" if EMBEDDED
522 select ANON_INODES
523 default y
524 help
525 Enable the eventfd() system call that allows to receive both
526 kernel notification (ie. KAIO) or userspace notifications.
528 If unsure, say Y.
530 config SHMEM
531 bool "Use full shmem filesystem" if EMBEDDED
532 default y
533 depends on MMU
534 help
535 The shmem is an internal filesystem used to manage shared memory.
536 It is backed by swap and manages resource limits. It is also exported
537 to userspace as tmpfs if TMPFS is enabled. Disabling this
538 option replaces shmem and tmpfs with the much simpler ramfs code,
539 which may be appropriate on small systems without swap.
541 config VM_EVENT_COUNTERS
542 default y
543 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
544 help
545 VM event counters are needed for event counts to be shown.
546 This option allows the disabling of the VM event counters
547 on EMBEDDED systems. /proc/vmstat will only show page counts
548 if VM event counters are disabled.
550 config SLUB_DEBUG
551 default y
552 bool "Enable SLUB debugging support" if EMBEDDED
553 depends on SLUB
554 help
555 SLUB has extensive debug support features. Disabling these can
556 result in significant savings in code size. This also disables
557 SLUB sysfs support. /sys/slab will not exist and there will be
558 no support for cache validation etc.
560 choice
561 prompt "Choose SLAB allocator"
562 default SLUB
563 help
564 This option allows to select a slab allocator.
566 config SLAB
567 bool "SLAB"
568 help
569 The regular slab allocator that is established and known to work
570 well in all environments. It organizes cache hot objects in
571 per cpu and per node queues. SLAB is the default choice for
572 a slab allocator.
574 config SLUB
575 bool "SLUB (Unqueued Allocator)"
576 help
577 SLUB is a slab allocator that minimizes cache line usage
578 instead of managing queues of cached objects (SLAB approach).
579 Per cpu caching is realized using slabs of objects instead
580 of queues of objects. SLUB can use memory efficiently
581 and has enhanced diagnostics.
583 config SLOB
584 depends on EMBEDDED
585 bool "SLOB (Simple Allocator)"
586 help
587 SLOB replaces the SLAB allocator with a drastically simpler
588 allocator. SLOB is more space efficient than SLAB but does not
589 scale well (single lock for all operations) and is also highly
590 susceptible to fragmentation. SLUB can accomplish a higher object
591 density. It is usually better to use SLUB instead of SLOB.
593 endchoice
595 endmenu # General setup
597 config RT_MUTEXES
598 boolean
599 select PLIST
601 config TINY_SHMEM
602 default !SHMEM
603 bool
605 config BASE_SMALL
606 int
607 default 0 if BASE_FULL
608 default 1 if !BASE_FULL
610 menuconfig MODULES
611 bool "Enable loadable module support"
612 help
613 Kernel modules are small pieces of compiled code which can
614 be inserted in the running kernel, rather than being
615 permanently built into the kernel. You use the "modprobe"
616 tool to add (and sometimes remove) them. If you say Y here,
617 many parts of the kernel can be built as modules (by
618 answering M instead of Y where indicated): this is most
619 useful for infrequently used options which are not required
620 for booting. For more information, see the man pages for
621 modprobe, lsmod, modinfo, insmod and rmmod.
623 If you say Y here, you will need to run "make
624 modules_install" to put the modules under /lib/modules/
625 where modprobe can find them (you may need to be root to do
626 this).
628 If unsure, say Y.
630 config MODULE_UNLOAD
631 bool "Module unloading"
632 depends on MODULES
633 help
634 Without this option you will not be able to unload any
635 modules (note that some modules may not be unloadable
636 anyway), which makes your kernel slightly smaller and
637 simpler. If unsure, say Y.
639 config MODULE_FORCE_UNLOAD
640 bool "Forced module unloading"
641 depends on MODULE_UNLOAD && EXPERIMENTAL
642 help
643 This option allows you to force a module to unload, even if the
644 kernel believes it is unsafe: the kernel will remove the module
645 without waiting for anyone to stop using it (using the -f option to
646 rmmod). This is mainly for kernel developers and desperate users.
647 If unsure, say N.
649 config MODVERSIONS
650 bool "Module versioning support"
651 depends on MODULES
652 help
653 Usually, you have to use modules compiled with your kernel.
654 Saying Y here makes it sometimes possible to use modules
655 compiled for different kernels, by adding enough information
656 to the modules to (hopefully) spot any changes which would
657 make them incompatible with the kernel you are running. If
658 unsure, say N.
660 config MODULE_SRCVERSION_ALL
661 bool "Source checksum for all modules"
662 depends on MODULES
663 help
664 Modules which contain a MODULE_VERSION get an extra "srcversion"
665 field inserted into their modinfo section, which contains a
666 sum of the source files which made it. This helps maintainers
667 see exactly which source was used to build a module (since
668 others sometimes change the module source without updating
669 the version). With this option, such a "srcversion" field
670 will be created for all modules. If unsure, say N.
672 config KMOD
673 bool "Automatic kernel module loading"
674 depends on MODULES
675 help
676 Normally when you have selected some parts of the kernel to
677 be created as kernel modules, you must load them (using the
678 "modprobe" command) before you can use them. If you say Y
679 here, some parts of the kernel will be able to load modules
680 automatically: when a part of the kernel needs a module, it
681 runs modprobe with the appropriate arguments, thereby
682 loading the module if it is available. If unsure, say Y.
684 config STOP_MACHINE
685 bool
686 default y
687 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
688 help
689 Need stop_machine() primitive.
691 source "block/Kconfig"
693 config PREEMPT_NOTIFIERS
694 bool