7 option env="KERNELVERSION"
13 default "/lib/modules/$UNAME_RELEASE/.config"
14 default "/etc/kernel-config"
15 default "/boot/config-$UNAME_RELEASE"
16 default "arch/$ARCH/defconfig"
21 bool "Prompt for development and/or incomplete code/drivers"
23 Some of the various things that Linux supports (such as network
24 drivers, file systems, network protocols, etc.) can be in a state
25 of development where the functionality, stability, or the level of
26 testing is not yet high enough for general use. This is usually
27 known as the "alpha-test" phase among developers. If a feature is
28 currently in alpha-test, then the developers usually discourage
29 uninformed widespread use of this feature by the general public to
30 avoid "Why doesn't this work?" type mail messages. However, active
31 testing and use of these systems is welcomed. Just be aware that it
32 may not meet the normal level of reliability or it may fail to work
33 in some special cases. Detailed bug reports from people familiar
34 with the kernel internals are usually welcomed by the developers
35 (before submitting bug reports, please read the documents
36 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
37 <file:Documentation/BUG-HUNTING>, and
38 <file:Documentation/oops-tracing.txt> in the kernel source).
40 This option will also make obsoleted drivers available. These are
41 drivers that have been replaced by something else, and/or are
42 scheduled to be removed in a future kernel release.
44 Unless you intend to help test and develop a feature or driver that
45 falls into this category, or you have a situation that requires
46 using these features, you should probably say N here, which will
47 cause the configurator to present you with fewer choices. If
48 you say Y here, you will be offered the choice of using features or
49 drivers that are currently considered to be in the alpha-test phase.
56 depends on BROKEN || !SMP
61 depends on SMP || PREEMPT
64 config INIT_ENV_ARG_LIMIT
69 Maximum of each of the number of arguments and environment
70 variables passed to init from the kernel command line.
74 string "Local version - append to kernel release"
76 Append an extra string to the end of your kernel version.
77 This will show up when you type uname, for example.
78 The string you set here will be appended after the contents of
79 any files with a filename matching localversion* in your
80 object and source tree, in that order. Your total string can
81 be a maximum of 64 characters.
83 config LOCALVERSION_AUTO
84 bool "Automatically append version information to the version string"
87 This will try to automatically determine if the current tree is a
88 release tree by looking for git tags that belong to the current
91 A string of the format -gxxxxxxxx will be added to the localversion
92 if a git-based tree is found. The string generated by this will be
93 appended after any matching localversion* files, and after the value
94 set in CONFIG_LOCALVERSION.
96 (The actual string used here is the first eight characters produced
97 by running the command:
99 $ git rev-parse --verify HEAD
101 which is done within the script "scripts/setlocalversion".)
104 bool "Support for paging of anonymous memory (swap)"
105 depends on MMU && BLOCK
108 This option allows you to choose whether you want to have support
109 for so called swap devices or swap files in your kernel that are
110 used to provide more virtual memory than the actual RAM present
111 in your computer. If unsure say Y.
116 Inter Process Communication is a suite of library functions and
117 system calls which let processes (running programs) synchronize and
118 exchange information. It is generally considered to be a good thing,
119 and some programs won't run unless you say Y here. In particular, if
120 you want to run the DOS emulator dosemu under Linux (read the
121 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
122 you'll need to say Y here.
124 You can find documentation about IPC with "info ipc" and also in
125 section 6.4 of the Linux Programmer's Guide, available from
126 <http://www.tldp.org/guides.html>.
128 config SYSVIPC_SYSCTL
135 bool "POSIX Message Queues"
136 depends on NET && EXPERIMENTAL
138 POSIX variant of message queues is a part of IPC. In POSIX message
139 queues every message has a priority which decides about succession
140 of receiving it by a process. If you want to compile and run
141 programs written e.g. for Solaris with use of its POSIX message
142 queues (functions mq_*) say Y here.
144 POSIX message queues are visible as a filesystem called 'mqueue'
145 and can be mounted somewhere if you want to do filesystem
146 operations on message queues.
150 config BSD_PROCESS_ACCT
151 bool "BSD Process Accounting"
153 If you say Y here, a user level program will be able to instruct the
154 kernel (via a special system call) to write process accounting
155 information to a file: whenever a process exits, information about
156 that process will be appended to the file by the kernel. The
157 information includes things such as creation time, owning user,
158 command name, memory usage, controlling terminal etc. (the complete
159 list is in the struct acct in <file:include/linux/acct.h>). It is
160 up to the user level program to do useful things with this
161 information. This is generally a good idea, so say Y.
163 config BSD_PROCESS_ACCT_V3
164 bool "BSD Process Accounting version 3 file format"
165 depends on BSD_PROCESS_ACCT
168 If you say Y here, the process accounting information is written
169 in a new file format that also logs the process IDs of each
170 process and it's parent. Note that this file format is incompatible
171 with previous v0/v1/v2 file formats, so you will need updated tools
172 for processing it. A preliminary version of these tools is available
173 at <http://www.physik3.uni-rostock.de/tim/kernel/utils/acct/>.
176 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
180 Export selected statistics for tasks/processes through the
181 generic netlink interface. Unlike BSD process accounting, the
182 statistics are available during the lifetime of tasks/processes as
183 responses to commands. Like BSD accounting, they are sent to user
188 config TASK_DELAY_ACCT
189 bool "Enable per-task delay accounting (EXPERIMENTAL)"
192 Collect information on time spent by a task waiting for system
193 resources like cpu, synchronous block I/O completion and swapping
194 in pages. Such statistics can help in setting a task's priorities
195 relative to other tasks for cpu, io, rss limits etc.
200 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
203 Collect extended task accounting data and send the data
204 to userland for processing over the taskstats interface.
208 config TASK_IO_ACCOUNTING
209 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
210 depends on TASK_XACCT
212 Collect information on the number of bytes of storage I/O which this
218 bool "Auditing support"
221 Enable auditing infrastructure that can be used with another
222 kernel subsystem, such as SELinux (which requires this for
223 logging of avc messages output). Does not do system-call
224 auditing without CONFIG_AUDITSYSCALL.
227 bool "Enable system-call auditing support"
228 depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64|| SUPERH)
229 default y if SECURITY_SELINUX
231 Enable low-overhead system-call auditing infrastructure that
232 can be used independently or with another kernel subsystem,
233 such as SELinux. To use audit's filesystem watch feature, please
234 ensure that INOTIFY is configured.
238 depends on AUDITSYSCALL && INOTIFY
241 tristate "Kernel .config support"
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).
253 bool "Enable access to .config through /proc/config.gz"
254 depends on IKCONFIG && PROC_FS
256 This option enables access to the kernel configuration file
257 through /proc/config.gz.
260 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
262 default 17 if S390 || LOCKDEP
263 default 16 if X86_NUMAQ || IA64
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
272 14 => 16 KB for uniprocessor
277 bool "Control Group support"
279 This option will let you use process cgroup subsystems
285 bool "Example debug cgroup subsystem"
288 This option enables a simple cgroup subsystem that
289 exports useful debugging information about the cgroups
295 bool "Namespace cgroup subsystem"
298 Provides a simple namespace cgroup subsystem to
299 provide hierarchical naming of sets of namespaces,
300 for instance virtual servers and checkpoint/restart
304 bool "Cpuset support"
305 depends on SMP && CGROUPS
307 This option will let you create and manage CPUSETs which
308 allow dynamically partitioning a system into sets of CPUs and
309 Memory Nodes and assigning tasks to run only within those sets.
310 This is primarily useful on large SMP or NUMA systems.
315 bool "Group CPU scheduler"
318 This feature lets CPU scheduler recognize task groups and control CPU
319 bandwidth allocation to such task groups.
321 config FAIR_GROUP_SCHED
322 bool "Group scheduling for SCHED_OTHER"
323 depends on GROUP_SCHED
326 config RT_GROUP_SCHED
327 bool "Group scheduling for SCHED_RR/FIFO"
328 depends on EXPERIMENTAL
329 depends on GROUP_SCHED
332 This feature lets you explicitly allocate real CPU bandwidth
333 to users or control groups (depending on the "Basis for grouping tasks"
334 setting below. If enabled, it will also make it impossible to
335 schedule realtime tasks for non-root users until you allocate
336 realtime bandwidth for them.
337 See Documentation/sched-rt-group.txt for more information.
340 depends on GROUP_SCHED
341 prompt "Basis for grouping tasks"
347 This option will choose userid as the basis for grouping
348 tasks, thus providing equal CPU bandwidth to each user.
351 bool "Control groups"
354 This option allows you to create arbitrary task groups
355 using the "cgroup" pseudo filesystem and control
356 the cpu bandwidth allocated to each such task group.
357 Refer to Documentation/cgroups.txt for more information
358 on "cgroup" pseudo filesystem.
362 config CGROUP_CPUACCT
363 bool "Simple CPU accounting cgroup subsystem"
366 Provides a simple Resource Controller for monitoring the
367 total CPU consumed by the tasks in a cgroup
369 config RESOURCE_COUNTERS
370 bool "Resource counters"
372 This option enables controller independent resource accounting
373 infrastructure that works with cgroups
376 config CGROUP_MEM_RES_CTLR
377 bool "Memory Resource Controller for Control Groups"
378 depends on CGROUPS && RESOURCE_COUNTERS
380 Provides a memory resource controller that manages both page cache and
383 Note that setting this option increases fixed memory overhead
384 associated with each page of memory in the system by 4/8 bytes
385 and also increases cache misses because struct page on many 64bit
386 systems will not fit into a single cache line anymore.
388 Only enable when you're ok with these trade offs and really
389 sure you need the memory resource controller.
391 config SYSFS_DEPRECATED
394 config SYSFS_DEPRECATED_V2
395 bool "Create deprecated sysfs files"
398 select SYSFS_DEPRECATED
400 This option creates deprecated symlinks such as the
401 "device"-link, the <subsystem>:<name>-link, and the
402 "bus"-link. It may also add deprecated key in the
404 None of these features or values should be used today, as
405 they export driver core implementation details to userspace
406 or export properties which can't be kept stable across kernel
409 If enabled, this option will also move any device structures
410 that belong to a class, back into the /sys/class hierarchy, in
411 order to support older versions of udev and some userspace
414 If you are using a distro with the most recent userspace
415 packages, it should be safe to say N here.
417 config PROC_PID_CPUSET
418 bool "Include legacy /proc/<pid>/cpuset file"
423 bool "Kernel->user space relay support (formerly relayfs)"
425 This option enables support for relay interface support in
426 certain file systems (such as debugfs).
427 It is designed to provide an efficient mechanism for tools and
428 facilities to relay large amounts of data from kernel space to
434 bool "Namespaces support" if EMBEDDED
437 Provides the way to make tasks work with different objects using
438 the same id. For example same IPC id may refer to different objects
439 or same user id or pid may refer to different tasks when used in
440 different namespaces.
444 depends on NAMESPACES
446 In this namespace tasks see different info provided with the
451 depends on NAMESPACES && SYSVIPC
453 In this namespace tasks work with IPC ids which correspond to
454 different IPC objects in different namespaces
457 bool "User namespace (EXPERIMENTAL)"
458 depends on NAMESPACES && EXPERIMENTAL
460 This allows containers, i.e. vservers, to use user namespaces
461 to provide different user info for different servers.
465 bool "PID Namespaces (EXPERIMENTAL)"
467 depends on NAMESPACES && EXPERIMENTAL
469 Suport process id namespaces. This allows having multiple
470 process with the same pid as long as they are in different
471 pid namespaces. This is a building block of containers.
473 Unless you want to work with an experimental feature
476 config BLK_DEV_INITRD
477 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
478 depends on BROKEN || !FRV
480 The initial RAM filesystem is a ramfs which is loaded by the
481 boot loader (loadlin or lilo) and that is mounted as root
482 before the normal boot procedure. It is typically used to
483 load modules needed to mount the "real" root file system,
484 etc. See <file:Documentation/initrd.txt> for details.
486 If RAM disk support (BLK_DEV_RAM) is also included, this
487 also enables initial RAM disk (initrd) support and adds
488 15 Kbytes (more on some other architectures) to the kernel size.
498 config CC_OPTIMIZE_FOR_SIZE
499 bool "Optimize for size (Look out for broken compilers!)"
501 depends on ARM || H8300 || SUPERH || EXPERIMENTAL
503 Enabling this option will pass "-Os" instead of "-O2" to gcc
504 resulting in a smaller kernel.
506 WARNING: some versions of gcc may generate incorrect code with this
507 option. If problems are observed, a gcc upgrade may be needed.
515 bool "Configure standard kernel features (for small systems)"
517 This option allows certain base kernel options and settings
518 to be disabled or tweaked. This is for specialized
519 environments which can tolerate a "non-standard" kernel.
520 Only use this if you really know what you are doing.
523 bool "Enable 16-bit UID system calls" if EMBEDDED
524 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_COMPAT) || UML || (X86_64 && IA32_EMULATION)
527 This enables the legacy 16-bit UID syscall wrappers.
529 config SYSCTL_SYSCALL
530 bool "Sysctl syscall support" if EMBEDDED
534 sys_sysctl uses binary paths that have been found challenging
535 to properly maintain and use. The interface in /proc/sys
536 using paths with ascii names is now the primary path to this
539 Almost nothing using the binary sysctl interface so if you are
540 trying to save some space it is probably safe to disable this,
541 making your kernel marginally smaller.
543 If unsure say Y here.
546 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
549 Say Y here to let the kernel print out symbolic crash information and
550 symbolic stack backtraces. This increases the size of the kernel
551 somewhat, as all symbols have to be loaded into the kernel image.
554 bool "Include all symbols in kallsyms"
555 depends on DEBUG_KERNEL && KALLSYMS
557 Normally kallsyms only contains the symbols of functions, for nicer
558 OOPS messages. Some debuggers can use kallsyms for other
559 symbols too: say Y here to include all symbols, if you need them
560 and you don't care about adding 300k to the size of your kernel.
564 config KALLSYMS_EXTRA_PASS
565 bool "Do an extra kallsyms pass"
568 If kallsyms is not working correctly, the build will fail with
569 inconsistent kallsyms data. If that occurs, log a bug report and
570 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
571 Always say N here unless you find a bug in kallsyms, which must be
572 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
573 you wait for kallsyms to be fixed.
577 bool "Support for hot-pluggable devices" if EMBEDDED
580 This option is provided for the case where no hotplug or uevent
581 capabilities is wanted by the kernel. You should only consider
582 disabling this option for embedded systems that do not use modules, a
583 dynamic /dev tree, or dynamic device discovery. Just say Y.
587 bool "Enable support for printk" if EMBEDDED
589 This option enables normal printk support. Removing it
590 eliminates most of the message strings from the kernel image
591 and makes the kernel more or less silent. As this makes it
592 very difficult to diagnose system problems, saying N here is
593 strongly discouraged.
596 bool "BUG() support" if EMBEDDED
599 Disabling this option eliminates support for BUG and WARN, reducing
600 the size of your kernel image and potentially quietly ignoring
601 numerous fatal conditions. You should only consider disabling this
602 option for embedded systems with no facilities for reporting errors.
607 bool "Enable ELF core dumps" if EMBEDDED
609 Enable support for generating core dumps. Disabling saves about 4k.
612 bool "Disable heap randomization"
615 Randomizing heap placement makes heap exploits harder, but it
616 also breaks ancient binaries (including anything libc5 based).
617 This option changes the bootup default to heap randomization
618 disabled, and can be overriden runtime by setting
619 /proc/sys/kernel/randomize_va_space to 2.
621 On non-ancient distros (post-2000 ones) N is usually a safe choice.
625 bool "Enable full-sized data structures for core" if EMBEDDED
627 Disabling this option reduces the size of miscellaneous core
628 kernel data structures. This saves memory on small machines,
629 but may reduce performance.
632 bool "Enable futex support" if EMBEDDED
636 Disabling this option will cause the kernel to be built without
637 support for "fast userspace mutexes". The resulting kernel may not
638 run glibc-based applications correctly.
644 bool "Enable eventpoll support" if EMBEDDED
648 Disabling this option will cause the kernel to be built without
649 support for epoll family of system calls.
652 bool "Enable signalfd() system call" if EMBEDDED
656 Enable the signalfd() system call that allows to receive signals
657 on a file descriptor.
662 bool "Enable timerfd() system call" if EMBEDDED
666 Enable the timerfd() system call that allows to receive timer
667 events on a file descriptor.
672 bool "Enable eventfd() system call" if EMBEDDED
676 Enable the eventfd() system call that allows to receive both
677 kernel notification (ie. KAIO) or userspace notifications.
682 bool "Use full shmem filesystem" if EMBEDDED
686 The shmem is an internal filesystem used to manage shared memory.
687 It is backed by swap and manages resource limits. It is also exported
688 to userspace as tmpfs if TMPFS is enabled. Disabling this
689 option replaces shmem and tmpfs with the much simpler ramfs code,
690 which may be appropriate on small systems without swap.
692 config VM_EVENT_COUNTERS
694 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
696 VM event counters are needed for event counts to be shown.
697 This option allows the disabling of the VM event counters
698 on EMBEDDED systems. /proc/vmstat will only show page counts
699 if VM event counters are disabled.
703 bool "Enable SLUB debugging support" if EMBEDDED
706 SLUB has extensive debug support features. Disabling these can
707 result in significant savings in code size. This also disables
708 SLUB sysfs support. /sys/slab will not exist and there will be
709 no support for cache validation etc.
712 prompt "Choose SLAB allocator"
715 This option allows to select a slab allocator.
720 The regular slab allocator that is established and known to work
721 well in all environments. It organizes cache hot objects in
722 per cpu and per node queues. SLAB is the default choice for
726 bool "SLUB (Unqueued Allocator)"
728 SLUB is a slab allocator that minimizes cache line usage
729 instead of managing queues of cached objects (SLAB approach).
730 Per cpu caching is realized using slabs of objects instead
731 of queues of objects. SLUB can use memory efficiently
732 and has enhanced diagnostics.
736 bool "SLOB (Simple Allocator)"
738 SLOB replaces the stock allocator with a drastically simpler
739 allocator. SLOB is generally more space efficient but
740 does not perform as well on large systems.
745 bool "Profiling support (EXPERIMENTAL)"
747 Say Y here to enable the extended profiling support mechanisms used
748 by profilers such as OProfile.
751 bool "Activate markers"
753 Place an empty function call at each marker site. Can be
754 dynamically changed for a probe function.
756 source "arch/Kconfig"
758 config PROC_PAGE_MONITOR
760 depends on PROC_FS && MMU
761 bool "Enable /proc page monitoring" if EMBEDDED
763 Various /proc files exist to monitor process memory utilization:
764 /proc/pid/smaps, /proc/pid/clear_refs, /proc/pid/pagemap,
765 /proc/kpagecount, and /proc/kpageflags. Disabling these
766 interfaces will reduce the size of the kernel by approximately 4kb.
768 endmenu # General setup
773 depends on SLAB || SLUB_DEBUG
786 default 0 if BASE_FULL
787 default 1 if !BASE_FULL
790 bool "Enable loadable module support"
792 Kernel modules are small pieces of compiled code which can
793 be inserted in the running kernel, rather than being
794 permanently built into the kernel. You use the "modprobe"
795 tool to add (and sometimes remove) them. If you say Y here,
796 many parts of the kernel can be built as modules (by
797 answering M instead of Y where indicated): this is most
798 useful for infrequently used options which are not required
799 for booting. For more information, see the man pages for
800 modprobe, lsmod, modinfo, insmod and rmmod.
802 If you say Y here, you will need to run "make
803 modules_install" to put the modules under /lib/modules/
804 where modprobe can find them (you may need to be root to do
810 bool "Module unloading"
813 Without this option you will not be able to unload any
814 modules (note that some modules may not be unloadable
815 anyway), which makes your kernel slightly smaller and
816 simpler. If unsure, say Y.
818 config MODULE_FORCE_UNLOAD
819 bool "Forced module unloading"
820 depends on MODULE_UNLOAD && EXPERIMENTAL
822 This option allows you to force a module to unload, even if the
823 kernel believes it is unsafe: the kernel will remove the module
824 without waiting for anyone to stop using it (using the -f option to
825 rmmod). This is mainly for kernel developers and desperate users.
829 bool "Module versioning support"
832 Usually, you have to use modules compiled with your kernel.
833 Saying Y here makes it sometimes possible to use modules
834 compiled for different kernels, by adding enough information
835 to the modules to (hopefully) spot any changes which would
836 make them incompatible with the kernel you are running. If
839 config MODULE_SRCVERSION_ALL
840 bool "Source checksum for all modules"
843 Modules which contain a MODULE_VERSION get an extra "srcversion"
844 field inserted into their modinfo section, which contains a
845 sum of the source files which made it. This helps maintainers
846 see exactly which source was used to build a module (since
847 others sometimes change the module source without updating
848 the version). With this option, such a "srcversion" field
849 will be created for all modules. If unsure, say N.
852 bool "Automatic kernel module loading"
855 Normally when you have selected some parts of the kernel to
856 be created as kernel modules, you must load them (using the
857 "modprobe" command) before you can use them. If you say Y
858 here, some parts of the kernel will be able to load modules
859 automatically: when a part of the kernel needs a module, it
860 runs modprobe with the appropriate arguments, thereby
861 loading the module if it is available. If unsure, say Y.
866 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
868 Need stop_machine() primitive.
870 source "block/Kconfig"
872 config PREEMPT_NOTIFIERS
876 def_bool !PREEMPT_RCU
878 This option selects the classic RCU implementation that is
879 designed for best read-side performance on non-realtime
880 systems. Classic RCU is the default. Note that the
881 PREEMPT_RCU symbol is used to select/deselect this option.