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33 drivers that have been replaced by something else, and/or are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 "PID Namespaces (EXPERIMENTAL)"
221 depends on EXPERIMENTAL
223 Suport process id namespaces. This allows having multiple
224 process with the same pid as long as they are in different
225 pid namespaces. This is a building block of containers.
227 Unless you want to work with an experimental feature
231 bool "Auditing support"
234 Enable auditing infrastructure that can be used with another
235 kernel subsystem, such as SELinux (which requires this for
236 logging of avc messages output). Does not do system-call
237 auditing without CONFIG_AUDITSYSCALL.
240 bool "Enable system-call auditing support"
241 depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64)
242 default y if SECURITY_SELINUX
244 Enable low-overhead system-call auditing infrastructure that
245 can be used independently or with another kernel subsystem,
246 such as SELinux. To use audit's filesystem watch feature, please
247 ensure that INOTIFY is configured.
251 depends on AUDITSYSCALL && INOTIFY
254 tristate "Kernel .config support"
256 This option enables the complete Linux kernel ".config" file
257 contents to be saved in the kernel. It provides documentation
258 of which kernel options are used in a running kernel or in an
259 on-disk kernel. This information can be extracted from the kernel
260 image file with the script scripts/extract-ikconfig and used as
261 input to rebuild the current kernel or to build another kernel.
262 It can also be extracted from a running kernel by reading
263 /proc/config.gz if enabled (below).
266 bool "Enable access to .config through /proc/config.gz"
267 depends on IKCONFIG && PROC_FS
269 This option enables access to the kernel configuration file
270 through /proc/config.gz.
273 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
275 default 17 if S390 || LOCKDEP
276 default 16 if X86_NUMAQ || IA64
280 Select kernel log buffer size as a power of 2.
281 Defaults and Examples:
282 17 => 128 KB for S/390
283 16 => 64 KB for x86 NUMAQ or IA-64
285 14 => 16 KB for uniprocessor
290 bool "Control Group support"
292 This option will let you use process cgroup subsystems
298 bool "Example debug cgroup subsystem"
301 This option enables a simple cgroup subsystem that
302 exports useful debugging information about the cgroups
308 bool "Namespace cgroup subsystem"
311 Provides a simple namespace cgroup subsystem to
312 provide hierarchical naming of sets of namespaces,
313 for instance virtual servers and checkpoint/restart
317 bool "Cpuset support"
318 depends on SMP && CGROUPS
320 This option will let you create and manage CPUSETs which
321 allow dynamically partitioning a system into sets of CPUs and
322 Memory Nodes and assigning tasks to run only within those sets.
323 This is primarily useful on large SMP or NUMA systems.
327 config FAIR_GROUP_SCHED
328 bool "Fair group CPU scheduler"
331 This feature lets CPU scheduler recognize task groups and control CPU
332 bandwidth allocation to such task groups.
335 depends on FAIR_GROUP_SCHED
336 prompt "Basis for grouping tasks"
337 default FAIR_USER_SCHED
339 config FAIR_USER_SCHED
342 This option will choose userid as the basis for grouping
343 tasks, thus providing equal CPU bandwidth to each user.
345 config FAIR_CGROUP_SCHED
346 bool "Control groups"
349 This option allows you to create arbitrary task groups
350 using the "cgroup" pseudo filesystem and control
351 the cpu bandwidth allocated to each such task group.
352 Refer to Documentation/cgroups.txt for more information
353 on "cgroup" pseudo filesystem.
357 config CGROUP_CPUACCT
358 bool "Simple CPU accounting cgroup subsystem"
361 Provides a simple Resource Controller for monitoring the
362 total CPU consumed by the tasks in a cgroup
364 config SYSFS_DEPRECATED
365 bool "Create deprecated sysfs files"
368 This option creates deprecated symlinks such as the
369 "device"-link, the <subsystem>:<name>-link, and the
370 "bus"-link. It may also add deprecated key in the
372 None of these features or values should be used today, as
373 they export driver core implementation details to userspace
374 or export properties which can't be kept stable across kernel
377 If enabled, this option will also move any device structures
378 that belong to a class, back into the /sys/class hierarchy, in
379 order to support older versions of udev.
381 If you are using a distro that was released in 2006 or later,
382 it should be safe to say N here.
384 config PROC_PID_CPUSET
385 bool "Include legacy /proc/<pid>/cpuset file"
390 bool "Kernel->user space relay support (formerly relayfs)"
392 This option enables support for relay interface support in
393 certain file systems (such as debugfs).
394 It is designed to provide an efficient mechanism for tools and
395 facilities to relay large amounts of data from kernel space to
400 config BLK_DEV_INITRD
401 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
402 depends on BROKEN || !FRV
404 The initial RAM filesystem is a ramfs which is loaded by the
405 boot loader (loadlin or lilo) and that is mounted as root
406 before the normal boot procedure. It is typically used to
407 load modules needed to mount the "real" root file system,
408 etc. See <file:Documentation/initrd.txt> for details.
410 If RAM disk support (BLK_DEV_RAM) is also included, this
411 also enables initial RAM disk (initrd) support and adds
412 15 Kbytes (more on some other architectures) to the kernel size.
422 config CC_OPTIMIZE_FOR_SIZE
423 bool "Optimize for size (Look out for broken compilers!)"
425 depends on ARM || H8300 || SUPERH || EXPERIMENTAL
427 Enabling this option will pass "-Os" instead of "-O2" to gcc
428 resulting in a smaller kernel.
430 WARNING: some versions of gcc may generate incorrect code with this
431 option. If problems are observed, a gcc upgrade may be needed.
439 bool "Configure standard kernel features (for small systems)"
441 This option allows certain base kernel options and settings
442 to be disabled or tweaked. This is for specialized
443 environments which can tolerate a "non-standard" kernel.
444 Only use this if you really know what you are doing.
447 bool "Enable 16-bit UID system calls" if EMBEDDED
448 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_COMPAT) || UML || (X86_64 && IA32_EMULATION)
451 This enables the legacy 16-bit UID syscall wrappers.
453 config SYSCTL_SYSCALL
454 bool "Sysctl syscall support" if EMBEDDED
458 sys_sysctl uses binary paths that have been found challenging
459 to properly maintain and use. The interface in /proc/sys
460 using paths with ascii names is now the primary path to this
463 Almost nothing using the binary sysctl interface so if you are
464 trying to save some space it is probably safe to disable this,
465 making your kernel marginally smaller.
467 If unsure say Y here.
470 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
473 Say Y here to let the kernel print out symbolic crash information and
474 symbolic stack backtraces. This increases the size of the kernel
475 somewhat, as all symbols have to be loaded into the kernel image.
478 bool "Include all symbols in kallsyms"
479 depends on DEBUG_KERNEL && KALLSYMS
481 Normally kallsyms only contains the symbols of functions, for nicer
482 OOPS messages. Some debuggers can use kallsyms for other
483 symbols too: say Y here to include all symbols, if you need them
484 and you don't care about adding 300k to the size of your kernel.
488 config KALLSYMS_EXTRA_PASS
489 bool "Do an extra kallsyms pass"
492 If kallsyms is not working correctly, the build will fail with
493 inconsistent kallsyms data. If that occurs, log a bug report and
494 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
495 Always say N here unless you find a bug in kallsyms, which must be
496 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
497 you wait for kallsyms to be fixed.
501 bool "Support for hot-pluggable devices" if EMBEDDED
504 This option is provided for the case where no hotplug or uevent
505 capabilities is wanted by the kernel. You should only consider
506 disabling this option for embedded systems that do not use modules, a
507 dynamic /dev tree, or dynamic device discovery. Just say Y.
511 bool "Enable support for printk" if EMBEDDED
513 This option enables normal printk support. Removing it
514 eliminates most of the message strings from the kernel image
515 and makes the kernel more or less silent. As this makes it
516 very difficult to diagnose system problems, saying N here is
517 strongly discouraged.
520 bool "BUG() support" if EMBEDDED
523 Disabling this option eliminates support for BUG and WARN, reducing
524 the size of your kernel image and potentially quietly ignoring
525 numerous fatal conditions. You should only consider disabling this
526 option for embedded systems with no facilities for reporting errors.
531 bool "Enable ELF core dumps" if EMBEDDED
533 Enable support for generating core dumps. Disabling saves about 4k.
537 bool "Enable full-sized data structures for core" if EMBEDDED
539 Disabling this option reduces the size of miscellaneous core
540 kernel data structures. This saves memory on small machines,
541 but may reduce performance.
544 bool "Enable futex support" if EMBEDDED
548 Disabling this option will cause the kernel to be built without
549 support for "fast userspace mutexes". The resulting kernel may not
550 run glibc-based applications correctly.
556 bool "Enable eventpoll support" if EMBEDDED
560 Disabling this option will cause the kernel to be built without
561 support for epoll family of system calls.
564 bool "Enable signalfd() system call" if EMBEDDED
568 Enable the signalfd() system call that allows to receive signals
569 on a file descriptor.
574 bool "Enable timerfd() system call" if EMBEDDED
579 Enable the timerfd() system call that allows to receive timer
580 events on a file descriptor.
585 bool "Enable eventfd() system call" if EMBEDDED
589 Enable the eventfd() system call that allows to receive both
590 kernel notification (ie. KAIO) or userspace notifications.
595 bool "Use full shmem filesystem" if EMBEDDED
599 The shmem is an internal filesystem used to manage shared memory.
600 It is backed by swap and manages resource limits. It is also exported
601 to userspace as tmpfs if TMPFS is enabled. Disabling this
602 option replaces shmem and tmpfs with the much simpler ramfs code,
603 which may be appropriate on small systems without swap.
605 config VM_EVENT_COUNTERS
607 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
609 VM event counters are needed for event counts to be shown.
610 This option allows the disabling of the VM event counters
611 on EMBEDDED systems. /proc/vmstat will only show page counts
612 if VM event counters are disabled.
616 bool "Enable SLUB debugging support" if EMBEDDED
619 SLUB has extensive debug support features. Disabling these can
620 result in significant savings in code size. This also disables
621 SLUB sysfs support. /sys/slab will not exist and there will be
622 no support for cache validation etc.
625 prompt "Choose SLAB allocator"
628 This option allows to select a slab allocator.
633 The regular slab allocator that is established and known to work
634 well in all environments. It organizes cache hot objects in
635 per cpu and per node queues. SLAB is the default choice for
639 bool "SLUB (Unqueued Allocator)"
641 SLUB is a slab allocator that minimizes cache line usage
642 instead of managing queues of cached objects (SLAB approach).
643 Per cpu caching is realized using slabs of objects instead
644 of queues of objects. SLUB can use memory efficiently
645 and has enhanced diagnostics.
649 bool "SLOB (Simple Allocator)"
651 SLOB replaces the SLAB allocator with a drastically simpler
652 allocator. SLOB is more space efficient than SLAB but does not
653 scale well (single lock for all operations) and is also highly
654 susceptible to fragmentation. SLUB can accomplish a higher object
655 density. It is usually better to use SLUB instead of SLOB.
659 endmenu # General setup
671 default 0 if BASE_FULL
672 default 1 if !BASE_FULL
675 bool "Enable loadable module support"
677 Kernel modules are small pieces of compiled code which can
678 be inserted in the running kernel, rather than being
679 permanently built into the kernel. You use the "modprobe"
680 tool to add (and sometimes remove) them. If you say Y here,
681 many parts of the kernel can be built as modules (by
682 answering M instead of Y where indicated): this is most
683 useful for infrequently used options which are not required
684 for booting. For more information, see the man pages for
685 modprobe, lsmod, modinfo, insmod and rmmod.
687 If you say Y here, you will need to run "make
688 modules_install" to put the modules under /lib/modules/
689 where modprobe can find them (you may need to be root to do
695 bool "Module unloading"
698 Without this option you will not be able to unload any
699 modules (note that some modules may not be unloadable
700 anyway), which makes your kernel slightly smaller and
701 simpler. If unsure, say Y.
703 config MODULE_FORCE_UNLOAD
704 bool "Forced module unloading"
705 depends on MODULE_UNLOAD && EXPERIMENTAL
707 This option allows you to force a module to unload, even if the
708 kernel believes it is unsafe: the kernel will remove the module
709 without waiting for anyone to stop using it (using the -f option to
710 rmmod). This is mainly for kernel developers and desperate users.
714 bool "Module versioning support"
717 Usually, you have to use modules compiled with your kernel.
718 Saying Y here makes it sometimes possible to use modules
719 compiled for different kernels, by adding enough information
720 to the modules to (hopefully) spot any changes which would
721 make them incompatible with the kernel you are running. If
724 config MODULE_SRCVERSION_ALL
725 bool "Source checksum for all modules"
728 Modules which contain a MODULE_VERSION get an extra "srcversion"
729 field inserted into their modinfo section, which contains a
730 sum of the source files which made it. This helps maintainers
731 see exactly which source was used to build a module (since
732 others sometimes change the module source without updating
733 the version). With this option, such a "srcversion" field
734 will be created for all modules. If unsure, say N.
737 bool "Automatic kernel module loading"
740 Normally when you have selected some parts of the kernel to
741 be created as kernel modules, you must load them (using the
742 "modprobe" command) before you can use them. If you say Y
743 here, some parts of the kernel will be able to load modules
744 automatically: when a part of the kernel needs a module, it
745 runs modprobe with the appropriate arguments, thereby
746 loading the module if it is available. If unsure, say Y.
751 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
753 Need stop_machine() primitive.
755 source "block/Kconfig"
757 config PREEMPT_NOTIFIERS