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41 drivers that have been replaced by something else, and/or are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.
314 config FAIR_GROUP_SCHED
315 bool "Fair group CPU scheduler"
318 This feature lets CPU scheduler recognize task groups and control CPU
319 bandwidth allocation to such task groups.
322 depends on FAIR_GROUP_SCHED
323 prompt "Basis for grouping tasks"
324 default FAIR_USER_SCHED
326 config FAIR_USER_SCHED
329 This option will choose userid as the basis for grouping
330 tasks, thus providing equal CPU bandwidth to each user.
332 config FAIR_CGROUP_SCHED
333 bool "Control groups"
336 This option allows you to create arbitrary task groups
337 using the "cgroup" pseudo filesystem and control
338 the cpu bandwidth allocated to each such task group.
339 Refer to Documentation/cgroups.txt for more information
340 on "cgroup" pseudo filesystem.
344 config CGROUP_CPUACCT
345 bool "Simple CPU accounting cgroup subsystem"
348 Provides a simple Resource Controller for monitoring the
349 total CPU consumed by the tasks in a cgroup
351 config RESOURCE_COUNTERS
352 bool "Resource counters"
354 This option enables controller independent resource accounting
355 infrastructure that works with cgroups
358 config SYSFS_DEPRECATED
359 bool "Create deprecated sysfs files"
363 This option creates deprecated symlinks such as the
364 "device"-link, the <subsystem>:<name>-link, and the
365 "bus"-link. It may also add deprecated key in the
367 None of these features or values should be used today, as
368 they export driver core implementation details to userspace
369 or export properties which can't be kept stable across kernel
372 If enabled, this option will also move any device structures
373 that belong to a class, back into the /sys/class hierarchy, in
374 order to support older versions of udev.
376 If you are using a distro that was released in 2006 or later,
377 it should be safe to say N here.
379 config CGROUP_MEM_CONT
380 bool "Memory controller for cgroups"
381 depends on CGROUPS && RESOURCE_COUNTERS
383 Provides a memory controller that manages both page cache and
386 config PROC_PID_CPUSET
387 bool "Include legacy /proc/<pid>/cpuset file"
392 bool "Kernel->user space relay support (formerly relayfs)"
394 This option enables support for relay interface support in
395 certain file systems (such as debugfs).
396 It is designed to provide an efficient mechanism for tools and
397 facilities to relay large amounts of data from kernel space to
403 bool "Namespaces support" if EMBEDDED
406 Provides the way to make tasks work with different objects using
407 the same id. For example same IPC id may refer to different objects
408 or same user id or pid may refer to different tasks when used in
409 different namespaces.
413 depends on NAMESPACES
415 In this namespace tasks see different info provided with the
420 depends on NAMESPACES && SYSVIPC
422 In this namespace tasks work with IPC ids which correspond to
423 different IPC objects in different namespaces
426 bool "User namespace (EXPERIMENTAL)"
427 depends on NAMESPACES && EXPERIMENTAL
429 This allows containers, i.e. vservers, to use user namespaces
430 to provide different user info for different servers.
434 bool "PID Namespaces (EXPERIMENTAL)"
436 depends on NAMESPACES && EXPERIMENTAL
438 Suport process id namespaces. This allows having multiple
439 process with the same pid as long as they are in different
440 pid namespaces. This is a building block of containers.
442 Unless you want to work with an experimental feature
445 config BLK_DEV_INITRD
446 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
447 depends on BROKEN || !FRV
449 The initial RAM filesystem is a ramfs which is loaded by the
450 boot loader (loadlin or lilo) and that is mounted as root
451 before the normal boot procedure. It is typically used to
452 load modules needed to mount the "real" root file system,
453 etc. See <file:Documentation/initrd.txt> for details.
455 If RAM disk support (BLK_DEV_RAM) is also included, this
456 also enables initial RAM disk (initrd) support and adds
457 15 Kbytes (more on some other architectures) to the kernel size.
467 config CC_OPTIMIZE_FOR_SIZE
468 bool "Optimize for size (Look out for broken compilers!)"
470 depends on ARM || H8300 || SUPERH || EXPERIMENTAL
472 Enabling this option will pass "-Os" instead of "-O2" to gcc
473 resulting in a smaller kernel.
475 WARNING: some versions of gcc may generate incorrect code with this
476 option. If problems are observed, a gcc upgrade may be needed.
484 bool "Configure standard kernel features (for small systems)"
486 This option allows certain base kernel options and settings
487 to be disabled or tweaked. This is for specialized
488 environments which can tolerate a "non-standard" kernel.
489 Only use this if you really know what you are doing.
492 bool "Enable 16-bit UID system calls" if EMBEDDED
493 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_COMPAT) || UML || (X86_64 && IA32_EMULATION)
496 This enables the legacy 16-bit UID syscall wrappers.
498 config SYSCTL_SYSCALL
499 bool "Sysctl syscall support" if EMBEDDED
503 sys_sysctl uses binary paths that have been found challenging
504 to properly maintain and use. The interface in /proc/sys
505 using paths with ascii names is now the primary path to this
508 Almost nothing using the binary sysctl interface so if you are
509 trying to save some space it is probably safe to disable this,
510 making your kernel marginally smaller.
512 If unsure say Y here.
515 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
518 Say Y here to let the kernel print out symbolic crash information and
519 symbolic stack backtraces. This increases the size of the kernel
520 somewhat, as all symbols have to be loaded into the kernel image.
523 bool "Include all symbols in kallsyms"
524 depends on DEBUG_KERNEL && KALLSYMS
526 Normally kallsyms only contains the symbols of functions, for nicer
527 OOPS messages. Some debuggers can use kallsyms for other
528 symbols too: say Y here to include all symbols, if you need them
529 and you don't care about adding 300k to the size of your kernel.
533 config KALLSYMS_EXTRA_PASS
534 bool "Do an extra kallsyms pass"
537 If kallsyms is not working correctly, the build will fail with
538 inconsistent kallsyms data. If that occurs, log a bug report and
539 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
540 Always say N here unless you find a bug in kallsyms, which must be
541 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
542 you wait for kallsyms to be fixed.
546 bool "Support for hot-pluggable devices" if EMBEDDED
549 This option is provided for the case where no hotplug or uevent
550 capabilities is wanted by the kernel. You should only consider
551 disabling this option for embedded systems that do not use modules, a
552 dynamic /dev tree, or dynamic device discovery. Just say Y.
556 bool "Enable support for printk" if EMBEDDED
558 This option enables normal printk support. Removing it
559 eliminates most of the message strings from the kernel image
560 and makes the kernel more or less silent. As this makes it
561 very difficult to diagnose system problems, saying N here is
562 strongly discouraged.
565 bool "BUG() support" if EMBEDDED
568 Disabling this option eliminates support for BUG and WARN, reducing
569 the size of your kernel image and potentially quietly ignoring
570 numerous fatal conditions. You should only consider disabling this
571 option for embedded systems with no facilities for reporting errors.
576 bool "Enable ELF core dumps" if EMBEDDED
578 Enable support for generating core dumps. Disabling saves about 4k.
581 bool "Disable heap randomization"
584 Randomizing heap placement makes heap exploits harder, but it
585 also breaks ancient binaries (including anything libc5 based).
586 This option changes the bootup default to heap randomization
587 disabled, and can be overriden runtime by setting
588 /proc/sys/kernel/randomize_va_space to 2.
590 On non-ancient distros (post-2000 ones) N is usually a safe choice.
594 bool "Enable full-sized data structures for core" if EMBEDDED
596 Disabling this option reduces the size of miscellaneous core
597 kernel data structures. This saves memory on small machines,
598 but may reduce performance.
601 bool "Enable futex support" if EMBEDDED
605 Disabling this option will cause the kernel to be built without
606 support for "fast userspace mutexes". The resulting kernel may not
607 run glibc-based applications correctly.
613 bool "Enable eventpoll support" if EMBEDDED
617 Disabling this option will cause the kernel to be built without
618 support for epoll family of system calls.
621 bool "Enable signalfd() system call" if EMBEDDED
625 Enable the signalfd() system call that allows to receive signals
626 on a file descriptor.
631 bool "Enable timerfd() system call" if EMBEDDED
635 Enable the timerfd() system call that allows to receive timer
636 events on a file descriptor.
641 bool "Enable eventfd() system call" if EMBEDDED
645 Enable the eventfd() system call that allows to receive both
646 kernel notification (ie. KAIO) or userspace notifications.
651 bool "Use full shmem filesystem" if EMBEDDED
655 The shmem is an internal filesystem used to manage shared memory.
656 It is backed by swap and manages resource limits. It is also exported
657 to userspace as tmpfs if TMPFS is enabled. Disabling this
658 option replaces shmem and tmpfs with the much simpler ramfs code,
659 which may be appropriate on small systems without swap.
661 config VM_EVENT_COUNTERS
663 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
665 VM event counters are needed for event counts to be shown.
666 This option allows the disabling of the VM event counters
667 on EMBEDDED systems. /proc/vmstat will only show page counts
668 if VM event counters are disabled.
672 bool "Enable SLUB debugging support" if EMBEDDED
675 SLUB has extensive debug support features. Disabling these can
676 result in significant savings in code size. This also disables
677 SLUB sysfs support. /sys/slab will not exist and there will be
678 no support for cache validation etc.
681 prompt "Choose SLAB allocator"
684 This option allows to select a slab allocator.
689 The regular slab allocator that is established and known to work
690 well in all environments. It organizes cache hot objects in
691 per cpu and per node queues. SLAB is the default choice for
695 bool "SLUB (Unqueued Allocator)"
697 SLUB is a slab allocator that minimizes cache line usage
698 instead of managing queues of cached objects (SLAB approach).
699 Per cpu caching is realized using slabs of objects instead
700 of queues of objects. SLUB can use memory efficiently
701 and has enhanced diagnostics.
705 bool "SLOB (Simple Allocator)"
707 SLOB replaces the stock allocator with a drastically simpler
708 allocator. SLOB is generally more space efficient but
709 does not perform as well on large systems.
714 bool "Profiling support (EXPERIMENTAL)"
716 Say Y here to enable the extended profiling support mechanisms used
717 by profilers such as OProfile.
720 bool "Activate markers"
722 Place an empty function call at each marker site. Can be
723 dynamically changed for a probe function.
725 source "arch/Kconfig"
727 config PROC_PAGE_MONITOR
729 depends on PROC_FS && MMU
730 bool "Enable /proc page monitoring" if EMBEDDED
732 Various /proc files exist to monitor process memory utilization:
733 /proc/pid/smaps, /proc/pid/clear_refs, /proc/pid/pagemap,
734 /proc/kpagecount, and /proc/kpageflags. Disabling these
735 interfaces will reduce the size of the kernel by approximately 4kb.
737 endmenu # General setup
742 depends on SLAB || SLUB
755 default 0 if BASE_FULL
756 default 1 if !BASE_FULL
759 bool "Enable loadable module support"
761 Kernel modules are small pieces of compiled code which can
762 be inserted in the running kernel, rather than being
763 permanently built into the kernel. You use the "modprobe"
764 tool to add (and sometimes remove) them. If you say Y here,
765 many parts of the kernel can be built as modules (by
766 answering M instead of Y where indicated): this is most
767 useful for infrequently used options which are not required
768 for booting. For more information, see the man pages for
769 modprobe, lsmod, modinfo, insmod and rmmod.
771 If you say Y here, you will need to run "make
772 modules_install" to put the modules under /lib/modules/
773 where modprobe can find them (you may need to be root to do
779 bool "Module unloading"
782 Without this option you will not be able to unload any
783 modules (note that some modules may not be unloadable
784 anyway), which makes your kernel slightly smaller and
785 simpler. If unsure, say Y.
787 config MODULE_FORCE_UNLOAD
788 bool "Forced module unloading"
789 depends on MODULE_UNLOAD && EXPERIMENTAL
791 This option allows you to force a module to unload, even if the
792 kernel believes it is unsafe: the kernel will remove the module
793 without waiting for anyone to stop using it (using the -f option to
794 rmmod). This is mainly for kernel developers and desperate users.
798 bool "Module versioning support"
801 Usually, you have to use modules compiled with your kernel.
802 Saying Y here makes it sometimes possible to use modules
803 compiled for different kernels, by adding enough information
804 to the modules to (hopefully) spot any changes which would
805 make them incompatible with the kernel you are running. If
808 config MODULE_SRCVERSION_ALL
809 bool "Source checksum for all modules"
812 Modules which contain a MODULE_VERSION get an extra "srcversion"
813 field inserted into their modinfo section, which contains a
814 sum of the source files which made it. This helps maintainers
815 see exactly which source was used to build a module (since
816 others sometimes change the module source without updating
817 the version). With this option, such a "srcversion" field
818 will be created for all modules. If unsure, say N.
821 bool "Automatic kernel module loading"
824 Normally when you have selected some parts of the kernel to
825 be created as kernel modules, you must load them (using the
826 "modprobe" command) before you can use them. If you say Y
827 here, some parts of the kernel will be able to load modules
828 automatically: when a part of the kernel needs a module, it
829 runs modprobe with the appropriate arguments, thereby
830 loading the module if it is available. If unsure, say Y.
835 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
837 Need stop_machine() primitive.
839 source "block/Kconfig"
841 config PREEMPT_NOTIFIERS
845 prompt "RCU implementation type:"
848 This allows you to choose either the classic RCU implementation
849 that is designed for best read-side performance on non-realtime
850 systems, or the preemptible RCU implementation for best latency
851 on realtime systems. Note that some kernel preemption modes
852 will restrict your choice.
854 Select the default if you are unsure.
859 This option selects the classic RCU implementation that is
860 designed for best read-side performance on non-realtime
863 Say Y if you are unsure.
866 bool "Preemptible RCU"
869 This option reduces the latency of the kernel by making certain
870 RCU sections preemptible. Normally RCU code is non-preemptible, if
871 this option is selected then read-only RCU sections become
872 preemptible. This helps latency, but may expose bugs due to
873 now-naive assumptions about each RCU read-side critical section
874 remaining on a given CPU through its execution.
876 Say N if you are unsure.
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