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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 "Code maturity level options"
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33 drivers that have been replaced by something else, and/or are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.
64 endmenu
66 menu "General setup"
68 config LOCALVERSION
69 string "Local version - append to kernel release"
70 help
71 Append an extra string to the end of your kernel version.
72 This will show up when you type uname, for example.
73 The string you set here will be appended after the contents of
74 any files with a filename matching localversion* in your
75 object and source tree, in that order. Your total string can
76 be a maximum of 64 characters.
78 config LOCALVERSION_AUTO
79 bool "Automatically append version information to the version string"
80 default y
81 help
82 This will try to automatically determine if the current tree is a
83 release tree by looking for git tags that belong to the current
84 top of tree revision.
86 A string of the format -gxxxxxxxx will be added to the localversion
87 if a git-based tree is found. The string generated by this will be
88 appended after any matching localversion* files, and after the value
89 set in CONFIG_LOCALVERSION.
91 (The actual string used here is the first eight characters produced
92 by running the command:
94 $ git rev-parse --verify HEAD
96 which is done within the script "scripts/setlocalversion".)
98 config SWAP
99 bool "Support for paging of anonymous memory (swap)"
100 depends on MMU && BLOCK
101 default y
102 help
103 This option allows you to choose whether you want to have support
104 for so called swap devices or swap files in your kernel that are
105 used to provide more virtual memory than the actual RAM present
106 in your computer. If unsure say Y.
108 config SYSVIPC
109 bool "System V IPC"
110 ---help---
111 Inter Process Communication is a suite of library functions and
112 system calls which let processes (running programs) synchronize and
113 exchange information. It is generally considered to be a good thing,
114 and some programs won't run unless you say Y here. In particular, if
115 you want to run the DOS emulator dosemu under Linux (read the
116 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
117 you'll need to say Y here.
119 You can find documentation about IPC with "info ipc" and also in
120 section 6.4 of the Linux Programmer's Guide, available from
121 <http://www.tldp.org/guides.html>.
123 config SYSVIPC_SYSCTL
124 bool
125 depends on SYSVIPC
126 depends on SYSCTL
127 default y
129 config POSIX_MQUEUE
130 bool "POSIX Message Queues"
131 depends on NET && EXPERIMENTAL
132 ---help---
133 POSIX variant of message queues is a part of IPC. In POSIX message
134 queues every message has a priority which decides about succession
135 of receiving it by a process. If you want to compile and run
136 programs written e.g. for Solaris with use of its POSIX message
137 queues (functions mq_*) say Y here.
139 POSIX message queues are visible as a filesystem called 'mqueue'
140 and can be mounted somewhere if you want to do filesystem
141 operations on message queues.
143 If unsure, say Y.
145 config BSD_PROCESS_ACCT
146 bool "BSD Process Accounting"
147 help
148 If you say Y here, a user level program will be able to instruct the
149 kernel (via a special system call) to write process accounting
150 information to a file: whenever a process exits, information about
151 that process will be appended to the file by the kernel. The
152 information includes things such as creation time, owning user,
153 command name, memory usage, controlling terminal etc. (the complete
154 list is in the struct acct in <file:include/linux/acct.h>). It is
155 up to the user level program to do useful things with this
156 information. This is generally a good idea, so say Y.
158 config BSD_PROCESS_ACCT_V3
159 bool "BSD Process Accounting version 3 file format"
160 depends on BSD_PROCESS_ACCT
161 default n
162 help
163 If you say Y here, the process accounting information is written
164 in a new file format that also logs the process IDs of each
165 process and it's parent. Note that this file format is incompatible
166 with previous v0/v1/v2 file formats, so you will need updated tools
167 for processing it. A preliminary version of these tools is available
168 at <http://www.physik3.uni-rostock.de/tim/kernel/utils/acct/>.
170 config TASKSTATS
171 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
172 depends on NET
173 default n
174 help
175 Export selected statistics for tasks/processes through the
176 generic netlink interface. Unlike BSD process accounting, the
177 statistics are available during the lifetime of tasks/processes as
178 responses to commands. Like BSD accounting, they are sent to user
179 space on task exit.
181 Say N if unsure.
183 config TASK_DELAY_ACCT
184 bool "Enable per-task delay accounting (EXPERIMENTAL)"
185 depends on TASKSTATS
186 help
187 Collect information on time spent by a task waiting for system
188 resources like cpu, synchronous block I/O completion and swapping
189 in pages. Such statistics can help in setting a task's priorities
190 relative to other tasks for cpu, io, rss limits etc.
192 Say N if unsure.
194 config TASK_XACCT
195 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
196 depends on TASKSTATS
197 help
198 Collect extended task accounting data and send the data
199 to userland for processing over the taskstats interface.
201 Say N if unsure.
203 config TASK_IO_ACCOUNTING
204 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
205 depends on TASK_XACCT
206 help
207 Collect information on the number of bytes of storage I/O which this
208 task has caused.
210 Say N if unsure.
212 config USER_NS
213 bool "User Namespaces (EXPERIMENTAL)"
214 default n
215 depends on EXPERIMENTAL
216 help
217 Support user namespaces. This allows containers, i.e.
218 vservers, to use user namespaces to provide different
219 user info for different servers. If unsure, say N.
221 config AUDIT
222 bool "Auditing support"
223 depends on NET
224 help
225 Enable auditing infrastructure that can be used with another
226 kernel subsystem, such as SELinux (which requires this for
227 logging of avc messages output). Does not do system-call
228 auditing without CONFIG_AUDITSYSCALL.
230 config AUDITSYSCALL
231 bool "Enable system-call auditing support"
232 depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64)
233 default y if SECURITY_SELINUX
234 help
235 Enable low-overhead system-call auditing infrastructure that
236 can be used independently or with another kernel subsystem,
237 such as SELinux. To use audit's filesystem watch feature, please
238 ensure that INOTIFY is configured.
240 config IKCONFIG
241 tristate "Kernel .config support"
242 ---help---
243 This option enables the complete Linux kernel ".config" file
244 contents to be saved in the kernel. It provides documentation
245 of which kernel options are used in a running kernel or in an
246 on-disk kernel. This information can be extracted from the kernel
247 image file with the script scripts/extract-ikconfig and used as
248 input to rebuild the current kernel or to build another kernel.
249 It can also be extracted from a running kernel by reading
250 /proc/config.gz if enabled (below).
252 config IKCONFIG_PROC
253 bool "Enable access to .config through /proc/config.gz"
254 depends on IKCONFIG && PROC_FS
255 ---help---
256 This option enables access to the kernel configuration file
257 through /proc/config.gz.
259 config LOG_BUF_SHIFT
260 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
261 range 12 21
262 default 17 if S390 || LOCKDEP
263 default 16 if X86_NUMAQ || IA64
264 default 15 if SMP
265 default 14
266 help
267 Select kernel log buffer size as a power of 2.
268 Defaults and Examples:
269 17 => 128 KB for S/390
270 16 => 64 KB for x86 NUMAQ or IA-64
271 15 => 32 KB for SMP
272 14 => 16 KB for uniprocessor
273 13 => 8 KB
274 12 => 4 KB
276 config CPUSETS
277 bool "Cpuset support"
278 depends on SMP
279 help
280 This option will let you create and manage CPUSETs which
281 allow dynamically partitioning a system into sets of CPUs and
282 Memory Nodes and assigning tasks to run only within those sets.
283 This is primarily useful on large SMP or NUMA systems.
285 Say N if unsure.
287 config SYSFS_DEPRECATED
288 bool "Create deprecated sysfs files"
289 default y
290 help
291 This option creates deprecated symlinks such as the
292 "device"-link, the <subsystem>:<name>-link, and the
293 "bus"-link. It may also add deprecated key in the
294 uevent environment.
295 None of these features or values should be used today, as
296 they export driver core implementation details to userspace
297 or export properties which can't be kept stable across kernel
298 releases.
300 If enabled, this option will also move any device structures
301 that belong to a class, back into the /sys/class hierarchy, in
302 order to support older versions of udev.
304 If you are using a distro that was released in 2006 or later,
305 it should be safe to say N here.
307 config RELAY
308 bool "Kernel->user space relay support (formerly relayfs)"
309 help
310 This option enables support for relay interface support in
311 certain file systems (such as debugfs).
312 It is designed to provide an efficient mechanism for tools and
313 facilities to relay large amounts of data from kernel space to
314 user space.
316 If unsure, say N.
318 config BLK_DEV_INITRD
319 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
320 depends on BROKEN || !FRV
321 help
322 The initial RAM filesystem is a ramfs which is loaded by the
323 boot loader (loadlin or lilo) and that is mounted as root
324 before the normal boot procedure. It is typically used to
325 load modules needed to mount the "real" root file system,
326 etc. See <file:Documentation/initrd.txt> for details.
328 If RAM disk support (BLK_DEV_RAM) is also included, this
329 also enables initial RAM disk (initrd) support and adds
330 15 Kbytes (more on some other architectures) to the kernel size.
332 If unsure say Y.
334 if BLK_DEV_INITRD
336 source "usr/Kconfig"
338 endif
340 config CC_OPTIMIZE_FOR_SIZE
341 bool "Optimize for size (Look out for broken compilers!)"
342 default y
343 depends on ARM || H8300 || EXPERIMENTAL
344 help
345 Enabling this option will pass "-Os" instead of "-O2" to gcc
346 resulting in a smaller kernel.
348 WARNING: some versions of gcc may generate incorrect code with this
349 option. If problems are observed, a gcc upgrade may be needed.
351 If unsure, say N.
353 config SYSCTL
354 bool
356 menuconfig EMBEDDED
357 bool "Configure standard kernel features (for small systems)"
358 help
359 This option allows certain base kernel options and settings
360 to be disabled or tweaked. This is for specialized
361 environments which can tolerate a "non-standard" kernel.
362 Only use this if you really know what you are doing.
364 config UID16
365 bool "Enable 16-bit UID system calls" if EMBEDDED
366 depends on ARM || BFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_COMPAT) || UML || (X86_64 && IA32_EMULATION)
367 default y
368 help
369 This enables the legacy 16-bit UID syscall wrappers.
371 config SYSCTL_SYSCALL
372 bool "Sysctl syscall support" if EMBEDDED
373 default y
374 select SYSCTL
375 ---help---
376 sys_sysctl uses binary paths that have been found challenging
377 to properly maintain and use. The interface in /proc/sys
378 using paths with ascii names is now the primary path to this
379 information.
381 Almost nothing using the binary sysctl interface so if you are
382 trying to save some space it is probably safe to disable this,
383 making your kernel marginally smaller.
385 If unsure say Y here.
387 config KALLSYMS
388 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
389 default y
390 help
391 Say Y here to let the kernel print out symbolic crash information and
392 symbolic stack backtraces. This increases the size of the kernel
393 somewhat, as all symbols have to be loaded into the kernel image.
395 config KALLSYMS_ALL
396 bool "Include all symbols in kallsyms"
397 depends on DEBUG_KERNEL && KALLSYMS
398 help
399 Normally kallsyms only contains the symbols of functions, for nicer
400 OOPS messages. Some debuggers can use kallsyms for other
401 symbols too: say Y here to include all symbols, if you need them
402 and you don't care about adding 300k to the size of your kernel.
404 Say N.
406 config KALLSYMS_EXTRA_PASS
407 bool "Do an extra kallsyms pass"
408 depends on KALLSYMS
409 help
410 If kallsyms is not working correctly, the build will fail with
411 inconsistent kallsyms data. If that occurs, log a bug report and
412 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
413 Always say N here unless you find a bug in kallsyms, which must be
414 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
415 you wait for kallsyms to be fixed.
418 config HOTPLUG
419 bool "Support for hot-pluggable devices" if EMBEDDED
420 default y
421 help
422 This option is provided for the case where no hotplug or uevent
423 capabilities is wanted by the kernel. You should only consider
424 disabling this option for embedded systems that do not use modules, a
425 dynamic /dev tree, or dynamic device discovery. Just say Y.
427 config PRINTK
428 default y
429 bool "Enable support for printk" if EMBEDDED
430 help
431 This option enables normal printk support. Removing it
432 eliminates most of the message strings from the kernel image
433 and makes the kernel more or less silent. As this makes it
434 very difficult to diagnose system problems, saying N here is
435 strongly discouraged.
437 config BUG
438 bool "BUG() support" if EMBEDDED
439 default y
440 help
441 Disabling this option eliminates support for BUG and WARN, reducing
442 the size of your kernel image and potentially quietly ignoring
443 numerous fatal conditions. You should only consider disabling this
444 option for embedded systems with no facilities for reporting errors.
445 Just say Y.
447 config ELF_CORE
448 default y
449 bool "Enable ELF core dumps" if EMBEDDED
450 help
451 Enable support for generating core dumps. Disabling saves about 4k.
453 config BASE_FULL
454 default y
455 bool "Enable full-sized data structures for core" if EMBEDDED
456 help
457 Disabling this option reduces the size of miscellaneous core
458 kernel data structures. This saves memory on small machines,
459 but may reduce performance.
461 config FUTEX
462 bool "Enable futex support" if EMBEDDED
463 default y
464 select RT_MUTEXES
465 help
466 Disabling this option will cause the kernel to be built without
467 support for "fast userspace mutexes". The resulting kernel may not
468 run glibc-based applications correctly.
470 config ANON_INODES
471 bool "Enable anonymous inode source" if EMBEDDED
472 default y
473 help
474 Anonymous inode source for pseudo-files like epoll, signalfd,
475 timerfd and eventfd.
477 If unsure, say Y.
479 config EPOLL
480 bool "Enable eventpoll support" if EMBEDDED
481 default y
482 depends on ANON_INODES
483 help
484 Disabling this option will cause the kernel to be built without
485 support for epoll family of system calls.
487 config SIGNALFD
488 bool "Enable signalfd() system call" if EMBEDDED
489 depends on ANON_INODES
490 default y
491 help
492 Enable the signalfd() system call that allows to receive signals
493 on a file descriptor.
495 If unsure, say Y.
497 config TIMERFD
498 bool "Enable timerfd() system call" if EMBEDDED
499 depends on ANON_INODES
500 default y
501 help
502 Enable the timerfd() system call that allows to receive timer
503 events on a file descriptor.
505 If unsure, say Y.
507 config EVENTFD
508 bool "Enable eventfd() system call" if EMBEDDED
509 depends on ANON_INODES
510 default y
511 help
512 Enable the eventfd() system call that allows to receive both
513 kernel notification (ie. KAIO) or userspace notifications.
515 If unsure, say Y.
517 config SHMEM
518 bool "Use full shmem filesystem" if EMBEDDED
519 default y
520 depends on MMU
521 help
522 The shmem is an internal filesystem used to manage shared memory.
523 It is backed by swap and manages resource limits. It is also exported
524 to userspace as tmpfs if TMPFS is enabled. Disabling this
525 option replaces shmem and tmpfs with the much simpler ramfs code,
526 which may be appropriate on small systems without swap.
528 config VM_EVENT_COUNTERS
529 default y
530 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
531 help
532 VM event counters are needed for event counts to be shown.
533 This option allows the disabling of the VM event counters
534 on EMBEDDED systems. /proc/vmstat will only show page counts
535 if VM event counters are disabled.
537 config SLUB_DEBUG
538 default y
539 bool "Enable SLUB debugging support" if EMBEDDED
540 depends on SLUB
541 help
542 SLUB has extensive debug support features. Disabling these can
543 result in significant savings in code size. This also disables
544 SLUB sysfs support. /sys/slab will not exist and there will be
545 no support for cache validation etc.
547 choice
548 prompt "Choose SLAB allocator"
549 default SLAB
550 help
551 This option allows to select a slab allocator.
553 config SLAB
554 bool "SLAB"
555 help
556 The regular slab allocator that is established and known to work
557 well in all environments. It organizes cache hot objects in
558 per cpu and per node queues. SLAB is the default choice for
559 a slab allocator.
561 config SLUB
562 bool "SLUB (Unqueued Allocator)"
563 help
564 SLUB is a slab allocator that minimizes cache line usage
565 instead of managing queues of cached objects (SLAB approach).
566 Per cpu caching is realized using slabs of objects instead
567 of queues of objects. SLUB can use memory efficiently
568 and has enhanced diagnostics.
570 config SLOB
571 depends on EMBEDDED
572 bool "SLOB (Simple Allocator)"
573 help
574 SLOB replaces the SLAB allocator with a drastically simpler
575 allocator. SLOB is more space efficient than SLAB but does not
576 scale well (single lock for all operations) and is also highly
577 susceptible to fragmentation. SLUB can accomplish a higher object
578 density. It is usually better to use SLUB instead of SLOB.
580 endchoice
582 endmenu # General setup
584 config RT_MUTEXES
585 boolean
586 select PLIST
588 config TINY_SHMEM
589 default !SHMEM
590 bool
592 config BASE_SMALL
593 int
594 default 0 if BASE_FULL
595 default 1 if !BASE_FULL
597 menuconfig MODULES
598 bool "Enable loadable module support"
599 help
600 Kernel modules are small pieces of compiled code which can
601 be inserted in the running kernel, rather than being
602 permanently built into the kernel. You use the "modprobe"
603 tool to add (and sometimes remove) them. If you say Y here,
604 many parts of the kernel can be built as modules (by
605 answering M instead of Y where indicated): this is most
606 useful for infrequently used options which are not required
607 for booting. For more information, see the man pages for
608 modprobe, lsmod, modinfo, insmod and rmmod.
610 If you say Y here, you will need to run "make
611 modules_install" to put the modules under /lib/modules/
612 where modprobe can find them (you may need to be root to do
613 this).
615 If unsure, say Y.
617 config MODULE_UNLOAD
618 bool "Module unloading"
619 depends on MODULES
620 help
621 Without this option you will not be able to unload any
622 modules (note that some modules may not be unloadable
623 anyway), which makes your kernel slightly smaller and
624 simpler. If unsure, say Y.
626 config MODULE_FORCE_UNLOAD
627 bool "Forced module unloading"
628 depends on MODULE_UNLOAD && EXPERIMENTAL
629 help
630 This option allows you to force a module to unload, even if the
631 kernel believes it is unsafe: the kernel will remove the module
632 without waiting for anyone to stop using it (using the -f option to
633 rmmod). This is mainly for kernel developers and desperate users.
634 If unsure, say N.
636 config MODVERSIONS
637 bool "Module versioning support"
638 depends on MODULES
639 help
640 Usually, you have to use modules compiled with your kernel.
641 Saying Y here makes it sometimes possible to use modules
642 compiled for different kernels, by adding enough information
643 to the modules to (hopefully) spot any changes which would
644 make them incompatible with the kernel you are running. If
645 unsure, say N.
647 config MODULE_SRCVERSION_ALL
648 bool "Source checksum for all modules"
649 depends on MODULES
650 help
651 Modules which contain a MODULE_VERSION get an extra "srcversion"
652 field inserted into their modinfo section, which contains a
653 sum of the source files which made it. This helps maintainers
654 see exactly which source was used to build a module (since
655 others sometimes change the module source without updating
656 the version). With this option, such a "srcversion" field
657 will be created for all modules. If unsure, say N.
659 config KMOD
660 bool "Automatic kernel module loading"
661 depends on MODULES
662 help
663 Normally when you have selected some parts of the kernel to
664 be created as kernel modules, you must load them (using the
665 "modprobe" command) before you can use them. If you say Y
666 here, some parts of the kernel will be able to load modules
667 automatically: when a part of the kernel needs a module, it
668 runs modprobe with the appropriate arguments, thereby
669 loading the module if it is available. If unsure, say Y.
671 config STOP_MACHINE
672 bool
673 default y
674 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
675 help
676 Need stop_machine() primitive.
678 source "block/Kconfig"