5 default "/lib/modules/$UNAME_RELEASE/.config"
6 default "/etc/kernel-config"
7 default "/boot/config-$UNAME_RELEASE"
8 default "arch/$ARCH/defconfig"
13 bool "Prompt for development and/or incomplete code/drivers"
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33 drivers that have been replaced by something else, and/or are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.
48 depends on BROKEN || !SMP
53 depends on SMP || PREEMPT
56 config INIT_ENV_ARG_LIMIT
61 Maximum of each of the number of arguments and environment
62 variables passed to init from the kernel command line.
66 string "Local version - append to kernel release"
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"
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
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".)
96 bool "Support for paging of anonymous memory (swap)"
97 depends on MMU && BLOCK
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.
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
127 bool "POSIX Message Queues"
128 depends on NET && EXPERIMENTAL
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.
142 config BSD_PROCESS_ACCT
143 bool "BSD Process Accounting"
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
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/>.
168 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
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
180 config TASK_DELAY_ACCT
181 bool "Enable per-task delay accounting (EXPERIMENTAL)"
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.
192 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
195 Collect extended task accounting data and send the data
196 to userland for processing over the taskstats interface.
200 config TASK_IO_ACCOUNTING
201 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
202 depends on TASK_XACCT
204 Collect information on the number of bytes of storage I/O which this
210 bool "User Namespaces (EXPERIMENTAL)"
212 depends on EXPERIMENTAL
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.
219 bool "Auditing support"
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.
228 bool "Enable system-call auditing support"
229 depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64)
230 default y if SECURITY_SELINUX
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.
238 tristate "Kernel .config support"
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).
250 bool "Enable access to .config through /proc/config.gz"
251 depends on IKCONFIG && PROC_FS
253 This option enables access to the kernel configuration file
254 through /proc/config.gz.
257 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
259 default 17 if S390 || LOCKDEP
260 default 16 if X86_NUMAQ || IA64
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
269 14 => 16 KB for uniprocessor
274 bool "Control Group support"
276 This option will let you use process cgroup subsystems
282 bool "Example debug cgroup subsystem"
285 This option enables a simple cgroup subsystem that
286 exports useful debugging information about the cgroups
292 bool "Namespace cgroup subsystem"
295 Provides a simple namespace cgroup subsystem to
296 provide hierarchical naming of sets of namespaces,
297 for instance virtual servers and checkpoint/restart
300 config CGROUP_CPUACCT
301 bool "Simple CPU accounting cgroup subsystem"
304 Provides a simple Resource Controller for monitoring the
305 total CPU consumed by the tasks in a cgroup
308 bool "Cpuset support"
309 depends on SMP && CGROUPS
311 This option will let you create and manage CPUSETs which
312 allow dynamically partitioning a system into sets of CPUs and
313 Memory Nodes and assigning tasks to run only within those sets.
314 This is primarily useful on large SMP or NUMA systems.
318 config FAIR_GROUP_SCHED
319 bool "Fair group CPU scheduler"
321 depends on EXPERIMENTAL
323 This feature lets CPU scheduler recognize task groups and control CPU
324 bandwidth allocation to such task groups.
327 depends on FAIR_GROUP_SCHED
328 prompt "Basis for grouping tasks"
329 default FAIR_USER_SCHED
331 config FAIR_USER_SCHED
334 This option will choose userid as the basis for grouping
335 tasks, thus providing equal CPU bandwidth to each user.
337 config FAIR_CGROUP_SCHED
338 bool "Control groups"
341 This option allows you to create arbitrary task groups
342 using the "cgroup" pseudo filesystem and control
343 the cpu bandwidth allocated to each such task group.
344 Refer to Documentation/cgroups.txt for more information
345 on "cgroup" pseudo filesystem.
349 config SYSFS_DEPRECATED
350 bool "Create deprecated sysfs files"
353 This option creates deprecated symlinks such as the
354 "device"-link, the <subsystem>:<name>-link, and the
355 "bus"-link. It may also add deprecated key in the
357 None of these features or values should be used today, as
358 they export driver core implementation details to userspace
359 or export properties which can't be kept stable across kernel
362 If enabled, this option will also move any device structures
363 that belong to a class, back into the /sys/class hierarchy, in
364 order to support older versions of udev.
366 If you are using a distro that was released in 2006 or later,
367 it should be safe to say N here.
369 config PROC_PID_CPUSET
370 bool "Include legacy /proc/<pid>/cpuset file"
375 bool "Kernel->user space relay support (formerly relayfs)"
377 This option enables support for relay interface support in
378 certain file systems (such as debugfs).
379 It is designed to provide an efficient mechanism for tools and
380 facilities to relay large amounts of data from kernel space to
385 config BLK_DEV_INITRD
386 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
387 depends on BROKEN || !FRV
389 The initial RAM filesystem is a ramfs which is loaded by the
390 boot loader (loadlin or lilo) and that is mounted as root
391 before the normal boot procedure. It is typically used to
392 load modules needed to mount the "real" root file system,
393 etc. See <file:Documentation/initrd.txt> for details.
395 If RAM disk support (BLK_DEV_RAM) is also included, this
396 also enables initial RAM disk (initrd) support and adds
397 15 Kbytes (more on some other architectures) to the kernel size.
407 config CC_OPTIMIZE_FOR_SIZE
408 bool "Optimize for size (Look out for broken compilers!)"
410 depends on ARM || H8300 || SUPERH || EXPERIMENTAL
412 Enabling this option will pass "-Os" instead of "-O2" to gcc
413 resulting in a smaller kernel.
415 WARNING: some versions of gcc may generate incorrect code with this
416 option. If problems are observed, a gcc upgrade may be needed.
424 bool "Configure standard kernel features (for small systems)"
426 This option allows certain base kernel options and settings
427 to be disabled or tweaked. This is for specialized
428 environments which can tolerate a "non-standard" kernel.
429 Only use this if you really know what you are doing.
432 bool "Enable 16-bit UID system calls" if EMBEDDED
433 depends on ARM || BFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_COMPAT) || UML || (X86_64 && IA32_EMULATION)
436 This enables the legacy 16-bit UID syscall wrappers.
438 config SYSCTL_SYSCALL
439 bool "Sysctl syscall support" if EMBEDDED
443 sys_sysctl uses binary paths that have been found challenging
444 to properly maintain and use. The interface in /proc/sys
445 using paths with ascii names is now the primary path to this
448 Almost nothing using the binary sysctl interface so if you are
449 trying to save some space it is probably safe to disable this,
450 making your kernel marginally smaller.
452 If unsure say Y here.
455 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
458 Say Y here to let the kernel print out symbolic crash information and
459 symbolic stack backtraces. This increases the size of the kernel
460 somewhat, as all symbols have to be loaded into the kernel image.
463 bool "Include all symbols in kallsyms"
464 depends on DEBUG_KERNEL && KALLSYMS
466 Normally kallsyms only contains the symbols of functions, for nicer
467 OOPS messages. Some debuggers can use kallsyms for other
468 symbols too: say Y here to include all symbols, if you need them
469 and you don't care about adding 300k to the size of your kernel.
473 config KALLSYMS_EXTRA_PASS
474 bool "Do an extra kallsyms pass"
477 If kallsyms is not working correctly, the build will fail with
478 inconsistent kallsyms data. If that occurs, log a bug report and
479 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
480 Always say N here unless you find a bug in kallsyms, which must be
481 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
482 you wait for kallsyms to be fixed.
486 bool "Support for hot-pluggable devices" if EMBEDDED
489 This option is provided for the case where no hotplug or uevent
490 capabilities is wanted by the kernel. You should only consider
491 disabling this option for embedded systems that do not use modules, a
492 dynamic /dev tree, or dynamic device discovery. Just say Y.
496 bool "Enable support for printk" if EMBEDDED
498 This option enables normal printk support. Removing it
499 eliminates most of the message strings from the kernel image
500 and makes the kernel more or less silent. As this makes it
501 very difficult to diagnose system problems, saying N here is
502 strongly discouraged.
505 bool "BUG() support" if EMBEDDED
508 Disabling this option eliminates support for BUG and WARN, reducing
509 the size of your kernel image and potentially quietly ignoring
510 numerous fatal conditions. You should only consider disabling this
511 option for embedded systems with no facilities for reporting errors.
516 bool "Enable ELF core dumps" if EMBEDDED
518 Enable support for generating core dumps. Disabling saves about 4k.
522 bool "Enable full-sized data structures for core" if EMBEDDED
524 Disabling this option reduces the size of miscellaneous core
525 kernel data structures. This saves memory on small machines,
526 but may reduce performance.
529 bool "Enable futex support" if EMBEDDED
533 Disabling this option will cause the kernel to be built without
534 support for "fast userspace mutexes". The resulting kernel may not
535 run glibc-based applications correctly.
541 bool "Enable eventpoll support" if EMBEDDED
545 Disabling this option will cause the kernel to be built without
546 support for epoll family of system calls.
549 bool "Enable signalfd() system call" if EMBEDDED
553 Enable the signalfd() system call that allows to receive signals
554 on a file descriptor.
559 bool "Enable timerfd() system call" if EMBEDDED
564 Enable the timerfd() system call that allows to receive timer
565 events on a file descriptor.
570 bool "Enable eventfd() system call" if EMBEDDED
574 Enable the eventfd() system call that allows to receive both
575 kernel notification (ie. KAIO) or userspace notifications.
580 bool "Use full shmem filesystem" if EMBEDDED
584 The shmem is an internal filesystem used to manage shared memory.
585 It is backed by swap and manages resource limits. It is also exported
586 to userspace as tmpfs if TMPFS is enabled. Disabling this
587 option replaces shmem and tmpfs with the much simpler ramfs code,
588 which may be appropriate on small systems without swap.
590 config VM_EVENT_COUNTERS
592 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
594 VM event counters are needed for event counts to be shown.
595 This option allows the disabling of the VM event counters
596 on EMBEDDED systems. /proc/vmstat will only show page counts
597 if VM event counters are disabled.
601 bool "Enable SLUB debugging support" if EMBEDDED
604 SLUB has extensive debug support features. Disabling these can
605 result in significant savings in code size. This also disables
606 SLUB sysfs support. /sys/slab will not exist and there will be
607 no support for cache validation etc.
610 prompt "Choose SLAB allocator"
613 This option allows to select a slab allocator.
618 The regular slab allocator that is established and known to work
619 well in all environments. It organizes cache hot objects in
620 per cpu and per node queues. SLAB is the default choice for
624 bool "SLUB (Unqueued Allocator)"
626 SLUB is a slab allocator that minimizes cache line usage
627 instead of managing queues of cached objects (SLAB approach).
628 Per cpu caching is realized using slabs of objects instead
629 of queues of objects. SLUB can use memory efficiently
630 and has enhanced diagnostics.
634 bool "SLOB (Simple Allocator)"
636 SLOB replaces the SLAB allocator with a drastically simpler
637 allocator. SLOB is more space efficient than SLAB but does not
638 scale well (single lock for all operations) and is also highly
639 susceptible to fragmentation. SLUB can accomplish a higher object
640 density. It is usually better to use SLUB instead of SLOB.
644 endmenu # General setup
656 default 0 if BASE_FULL
657 default 1 if !BASE_FULL
660 bool "Enable loadable module support"
662 Kernel modules are small pieces of compiled code which can
663 be inserted in the running kernel, rather than being
664 permanently built into the kernel. You use the "modprobe"
665 tool to add (and sometimes remove) them. If you say Y here,
666 many parts of the kernel can be built as modules (by
667 answering M instead of Y where indicated): this is most
668 useful for infrequently used options which are not required
669 for booting. For more information, see the man pages for
670 modprobe, lsmod, modinfo, insmod and rmmod.
672 If you say Y here, you will need to run "make
673 modules_install" to put the modules under /lib/modules/
674 where modprobe can find them (you may need to be root to do
680 bool "Module unloading"
683 Without this option you will not be able to unload any
684 modules (note that some modules may not be unloadable
685 anyway), which makes your kernel slightly smaller and
686 simpler. If unsure, say Y.
688 config MODULE_FORCE_UNLOAD
689 bool "Forced module unloading"
690 depends on MODULE_UNLOAD && EXPERIMENTAL
692 This option allows you to force a module to unload, even if the
693 kernel believes it is unsafe: the kernel will remove the module
694 without waiting for anyone to stop using it (using the -f option to
695 rmmod). This is mainly for kernel developers and desperate users.
699 bool "Module versioning support"
702 Usually, you have to use modules compiled with your kernel.
703 Saying Y here makes it sometimes possible to use modules
704 compiled for different kernels, by adding enough information
705 to the modules to (hopefully) spot any changes which would
706 make them incompatible with the kernel you are running. If
709 config MODULE_SRCVERSION_ALL
710 bool "Source checksum for all modules"
713 Modules which contain a MODULE_VERSION get an extra "srcversion"
714 field inserted into their modinfo section, which contains a
715 sum of the source files which made it. This helps maintainers
716 see exactly which source was used to build a module (since
717 others sometimes change the module source without updating
718 the version). With this option, such a "srcversion" field
719 will be created for all modules. If unsure, say N.
722 bool "Automatic kernel module loading"
725 Normally when you have selected some parts of the kernel to
726 be created as kernel modules, you must load them (using the
727 "modprobe" command) before you can use them. If you say Y
728 here, some parts of the kernel will be able to load modules
729 automatically: when a part of the kernel needs a module, it
730 runs modprobe with the appropriate arguments, thereby
731 loading the module if it is available. If unsure, say Y.
736 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
738 Need stop_machine() primitive.
740 source "block/Kconfig"
742 config PREEMPT_NOTIFIERS
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