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41 drivers that have been replaced by something else, and/or are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)"
264 Select kernel log buffer size as a power of 2.
274 bool "Control Group support"
276 This option will let you use process cgroup subsystems
282 bool "Example debug cgroup subsystem"
286 This option enables a simple cgroup subsystem that
287 exports useful debugging information about the cgroups
293 bool "Namespace cgroup subsystem"
296 Provides a simple namespace cgroup subsystem to
297 provide hierarchical naming of sets of namespaces,
298 for instance virtual servers and checkpoint/restart
302 bool "Cpuset support"
303 depends on SMP && CGROUPS
305 This option will let you create and manage CPUSETs which
306 allow dynamically partitioning a system into sets of CPUs and
307 Memory Nodes and assigning tasks to run only within those sets.
308 This is primarily useful on large SMP or NUMA systems.
313 bool "Group CPU scheduler"
316 This feature lets CPU scheduler recognize task groups and control CPU
317 bandwidth allocation to such task groups.
319 config FAIR_GROUP_SCHED
320 bool "Group scheduling for SCHED_OTHER"
321 depends on GROUP_SCHED
324 config RT_GROUP_SCHED
325 bool "Group scheduling for SCHED_RR/FIFO"
326 depends on EXPERIMENTAL
327 depends on GROUP_SCHED
330 This feature lets you explicitly allocate real CPU bandwidth
331 to users or control groups (depending on the "Basis for grouping tasks"
332 setting below. If enabled, it will also make it impossible to
333 schedule realtime tasks for non-root users until you allocate
334 realtime bandwidth for them.
335 See Documentation/sched-rt-group.txt for more information.
338 depends on GROUP_SCHED
339 prompt "Basis for grouping tasks"
345 This option will choose userid as the basis for grouping
346 tasks, thus providing equal CPU bandwidth to each user.
349 bool "Control groups"
352 This option allows you to create arbitrary task groups
353 using the "cgroup" pseudo filesystem and control
354 the cpu bandwidth allocated to each such task group.
355 Refer to Documentation/cgroups.txt for more information
356 on "cgroup" pseudo filesystem.
360 config CGROUP_CPUACCT
361 bool "Simple CPU accounting cgroup subsystem"
364 Provides a simple Resource Controller for monitoring the
365 total CPU consumed by the tasks in a cgroup
367 config RESOURCE_COUNTERS
368 bool "Resource counters"
370 This option enables controller independent resource accounting
371 infrastructure that works with cgroups
374 config CGROUP_MEM_RES_CTLR
375 bool "Memory Resource Controller for Control Groups"
376 depends on CGROUPS && RESOURCE_COUNTERS
378 Provides a memory resource controller that manages both page cache and
381 Note that setting this option increases fixed memory overhead
382 associated with each page of memory in the system by 4/8 bytes
383 and also increases cache misses because struct page on many 64bit
384 systems will not fit into a single cache line anymore.
386 Only enable when you're ok with these trade offs and really
387 sure you need the memory resource controller.
389 config SYSFS_DEPRECATED
392 config SYSFS_DEPRECATED_V2
393 bool "Create deprecated sysfs files"
396 select SYSFS_DEPRECATED
398 This option creates deprecated symlinks such as the
399 "device"-link, the <subsystem>:<name>-link, and the
400 "bus"-link. It may also add deprecated key in the
402 None of these features or values should be used today, as
403 they export driver core implementation details to userspace
404 or export properties which can't be kept stable across kernel
407 If enabled, this option will also move any device structures
408 that belong to a class, back into the /sys/class hierarchy, in
409 order to support older versions of udev and some userspace
412 If you are using a distro with the most recent userspace
413 packages, it should be safe to say N here.
415 config PROC_PID_CPUSET
416 bool "Include legacy /proc/<pid>/cpuset file"
421 bool "Kernel->user space relay support (formerly relayfs)"
423 This option enables support for relay interface support in
424 certain file systems (such as debugfs).
425 It is designed to provide an efficient mechanism for tools and
426 facilities to relay large amounts of data from kernel space to
432 bool "Namespaces support" if EMBEDDED
435 Provides the way to make tasks work with different objects using
436 the same id. For example same IPC id may refer to different objects
437 or same user id or pid may refer to different tasks when used in
438 different namespaces.
442 depends on NAMESPACES
444 In this namespace tasks see different info provided with the
449 depends on NAMESPACES && SYSVIPC
451 In this namespace tasks work with IPC ids which correspond to
452 different IPC objects in different namespaces
455 bool "User namespace (EXPERIMENTAL)"
456 depends on NAMESPACES && EXPERIMENTAL
458 This allows containers, i.e. vservers, to use user namespaces
459 to provide different user info for different servers.
463 bool "PID Namespaces (EXPERIMENTAL)"
465 depends on NAMESPACES && EXPERIMENTAL
467 Suport process id namespaces. This allows having multiple
468 process with the same pid as long as they are in different
469 pid namespaces. This is a building block of containers.
471 Unless you want to work with an experimental feature
474 config BLK_DEV_INITRD
475 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
476 depends on BROKEN || !FRV
478 The initial RAM filesystem is a ramfs which is loaded by the
479 boot loader (loadlin or lilo) and that is mounted as root
480 before the normal boot procedure. It is typically used to
481 load modules needed to mount the "real" root file system,
482 etc. See <file:Documentation/initrd.txt> for details.
484 If RAM disk support (BLK_DEV_RAM) is also included, this
485 also enables initial RAM disk (initrd) support and adds
486 15 Kbytes (more on some other architectures) to the kernel size.
496 config CC_OPTIMIZE_FOR_SIZE
497 bool "Optimize for size"
500 Enabling this option will pass "-Os" instead of "-O2" to gcc
501 resulting in a smaller kernel.
509 bool "Configure standard kernel features (for small systems)"
511 This option allows certain base kernel options and settings
512 to be disabled or tweaked. This is for specialized
513 environments which can tolerate a "non-standard" kernel.
514 Only use this if you really know what you are doing.
517 bool "Enable 16-bit UID system calls" if EMBEDDED
518 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
521 This enables the legacy 16-bit UID syscall wrappers.
523 config SYSCTL_SYSCALL
524 bool "Sysctl syscall support" if EMBEDDED
528 sys_sysctl uses binary paths that have been found challenging
529 to properly maintain and use. The interface in /proc/sys
530 using paths with ascii names is now the primary path to this
533 Almost nothing using the binary sysctl interface so if you are
534 trying to save some space it is probably safe to disable this,
535 making your kernel marginally smaller.
537 If unsure say Y here.
540 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
543 Say Y here to let the kernel print out symbolic crash information and
544 symbolic stack backtraces. This increases the size of the kernel
545 somewhat, as all symbols have to be loaded into the kernel image.
548 bool "Include all symbols in kallsyms"
549 depends on DEBUG_KERNEL && KALLSYMS
551 Normally kallsyms only contains the symbols of functions, for nicer
552 OOPS messages. Some debuggers can use kallsyms for other
553 symbols too: say Y here to include all symbols, if you need them
554 and you don't care about adding 300k to the size of your kernel.
558 config KALLSYMS_EXTRA_PASS
559 bool "Do an extra kallsyms pass"
562 If kallsyms is not working correctly, the build will fail with
563 inconsistent kallsyms data. If that occurs, log a bug report and
564 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
565 Always say N here unless you find a bug in kallsyms, which must be
566 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
567 you wait for kallsyms to be fixed.
571 bool "Support for hot-pluggable devices" if EMBEDDED
574 This option is provided for the case where no hotplug or uevent
575 capabilities is wanted by the kernel. You should only consider
576 disabling this option for embedded systems that do not use modules, a
577 dynamic /dev tree, or dynamic device discovery. Just say Y.
581 bool "Enable support for printk" if EMBEDDED
583 This option enables normal printk support. Removing it
584 eliminates most of the message strings from the kernel image
585 and makes the kernel more or less silent. As this makes it
586 very difficult to diagnose system problems, saying N here is
587 strongly discouraged.
590 bool "BUG() support" if EMBEDDED
593 Disabling this option eliminates support for BUG and WARN, reducing
594 the size of your kernel image and potentially quietly ignoring
595 numerous fatal conditions. You should only consider disabling this
596 option for embedded systems with no facilities for reporting errors.
601 bool "Enable ELF core dumps" if EMBEDDED
603 Enable support for generating core dumps. Disabling saves about 4k.
606 bool "Disable heap randomization"
609 Randomizing heap placement makes heap exploits harder, but it
610 also breaks ancient binaries (including anything libc5 based).
611 This option changes the bootup default to heap randomization
612 disabled, and can be overriden runtime by setting
613 /proc/sys/kernel/randomize_va_space to 2.
615 On non-ancient distros (post-2000 ones) N is usually a safe choice.
619 bool "Enable full-sized data structures for core" if EMBEDDED
621 Disabling this option reduces the size of miscellaneous core
622 kernel data structures. This saves memory on small machines,
623 but may reduce performance.
626 bool "Enable futex support" if EMBEDDED
630 Disabling this option will cause the kernel to be built without
631 support for "fast userspace mutexes". The resulting kernel may not
632 run glibc-based applications correctly.
638 bool "Enable eventpoll support" if EMBEDDED
642 Disabling this option will cause the kernel to be built without
643 support for epoll family of system calls.
646 bool "Enable signalfd() system call" if EMBEDDED
650 Enable the signalfd() system call that allows to receive signals
651 on a file descriptor.
656 bool "Enable timerfd() system call" if EMBEDDED
660 Enable the timerfd() system call that allows to receive timer
661 events on a file descriptor.
666 bool "Enable eventfd() system call" if EMBEDDED
670 Enable the eventfd() system call that allows to receive both
671 kernel notification (ie. KAIO) or userspace notifications.
676 bool "Use full shmem filesystem" if EMBEDDED
680 The shmem is an internal filesystem used to manage shared memory.
681 It is backed by swap and manages resource limits. It is also exported
682 to userspace as tmpfs if TMPFS is enabled. Disabling this
683 option replaces shmem and tmpfs with the much simpler ramfs code,
684 which may be appropriate on small systems without swap.
686 config VM_EVENT_COUNTERS
688 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
690 VM event counters are needed for event counts to be shown.
691 This option allows the disabling of the VM event counters
692 on EMBEDDED systems. /proc/vmstat will only show page counts
693 if VM event counters are disabled.
697 bool "Enable SLUB debugging support" if EMBEDDED
700 SLUB has extensive debug support features. Disabling these can
701 result in significant savings in code size. This also disables
702 SLUB sysfs support. /sys/slab will not exist and there will be
703 no support for cache validation etc.
706 prompt "Choose SLAB allocator"
709 This option allows to select a slab allocator.
714 The regular slab allocator that is established and known to work
715 well in all environments. It organizes cache hot objects in
716 per cpu and per node queues. SLAB is the default choice for
720 bool "SLUB (Unqueued Allocator)"
722 SLUB is a slab allocator that minimizes cache line usage
723 instead of managing queues of cached objects (SLAB approach).
724 Per cpu caching is realized using slabs of objects instead
725 of queues of objects. SLUB can use memory efficiently
726 and has enhanced diagnostics.
730 bool "SLOB (Simple Allocator)"
732 SLOB replaces the stock allocator with a drastically simpler
733 allocator. SLOB is generally more space efficient but
734 does not perform as well on large systems.
739 bool "Profiling support (EXPERIMENTAL)"
741 Say Y here to enable the extended profiling support mechanisms used
742 by profilers such as OProfile.
745 bool "Activate markers"
747 Place an empty function call at each marker site. Can be
748 dynamically changed for a probe function.
750 source "arch/Kconfig"
752 config PROC_PAGE_MONITOR
754 depends on PROC_FS && MMU
755 bool "Enable /proc page monitoring" if EMBEDDED
757 Various /proc files exist to monitor process memory utilization:
758 /proc/pid/smaps, /proc/pid/clear_refs, /proc/pid/pagemap,
759 /proc/kpagecount, and /proc/kpageflags. Disabling these
760 interfaces will reduce the size of the kernel by approximately 4kb.
762 endmenu # General setup
767 depends on SLAB || SLUB_DEBUG
780 default 0 if BASE_FULL
781 default 1 if !BASE_FULL
784 bool "Enable loadable module support"
786 Kernel modules are small pieces of compiled code which can
787 be inserted in the running kernel, rather than being
788 permanently built into the kernel. You use the "modprobe"
789 tool to add (and sometimes remove) them. If you say Y here,
790 many parts of the kernel can be built as modules (by
791 answering M instead of Y where indicated): this is most
792 useful for infrequently used options which are not required
793 for booting. For more information, see the man pages for
794 modprobe, lsmod, modinfo, insmod and rmmod.
796 If you say Y here, you will need to run "make
797 modules_install" to put the modules under /lib/modules/
798 where modprobe can find them (you may need to be root to do
804 bool "Module unloading"
807 Without this option you will not be able to unload any
808 modules (note that some modules may not be unloadable
809 anyway), which makes your kernel slightly smaller and
810 simpler. If unsure, say Y.
812 config MODULE_FORCE_UNLOAD
813 bool "Forced module unloading"
814 depends on MODULE_UNLOAD && EXPERIMENTAL
816 This option allows you to force a module to unload, even if the
817 kernel believes it is unsafe: the kernel will remove the module
818 without waiting for anyone to stop using it (using the -f option to
819 rmmod). This is mainly for kernel developers and desperate users.
823 bool "Module versioning support"
826 Usually, you have to use modules compiled with your kernel.
827 Saying Y here makes it sometimes possible to use modules
828 compiled for different kernels, by adding enough information
829 to the modules to (hopefully) spot any changes which would
830 make them incompatible with the kernel you are running. If
833 config MODULE_SRCVERSION_ALL
834 bool "Source checksum for all modules"
837 Modules which contain a MODULE_VERSION get an extra "srcversion"
838 field inserted into their modinfo section, which contains a
839 sum of the source files which made it. This helps maintainers
840 see exactly which source was used to build a module (since
841 others sometimes change the module source without updating
842 the version). With this option, such a "srcversion" field
843 will be created for all modules. If unsure, say N.
846 bool "Automatic kernel module loading"
849 Normally when you have selected some parts of the kernel to
850 be created as kernel modules, you must load them (using the
851 "modprobe" command) before you can use them. If you say Y
852 here, some parts of the kernel will be able to load modules
853 automatically: when a part of the kernel needs a module, it
854 runs modprobe with the appropriate arguments, thereby
855 loading the module if it is available. If unsure, say Y.
860 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
862 Need stop_machine() primitive.
864 source "block/Kconfig"
866 config PREEMPT_NOTIFIERS
870 def_bool !PREEMPT_RCU
872 This option selects the classic RCU implementation that is
873 designed for best read-side performance on non-realtime
874 systems. Classic RCU is the default. Note that the
875 PREEMPT_RCU symbol is used to select/deselect this option.
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