7 option env="KERNELVERSION"
13 default "/lib/modules/$UNAME_RELEASE/.config"
14 default "/etc/kernel-config"
15 default "/boot/config-$UNAME_RELEASE"
16 default "$ARCH_DEFCONFIG"
17 default "arch/$ARCH/defconfig"
22 bool "Prompt for development and/or incomplete code/drivers"
24 Some of the various things that Linux supports (such as network
25 drivers, file systems, network protocols, etc.) can be in a state
26 of development where the functionality, stability, or the level of
27 testing is not yet high enough for general use. This is usually
28 known as the "alpha-test" phase among developers. If a feature is
29 currently in alpha-test, then the developers usually discourage
30 uninformed widespread use of this feature by the general public to
31 avoid "Why doesn't this work?" type mail messages. However, active
32 testing and use of these systems is welcomed. Just be aware that it
33 may not meet the normal level of reliability or it may fail to work
34 in some special cases. Detailed bug reports from people familiar
35 with the kernel internals are usually welcomed by the developers
36 (before submitting bug reports, please read the documents
37 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
38 <file:Documentation/BUG-HUNTING>, and
39 <file:Documentation/oops-tracing.txt> in the kernel source).
41 This option will also make obsoleted drivers available. These are
42 drivers that have been replaced by something else, and/or are
43 scheduled to be removed in a future kernel release.
45 Unless you intend to help test and develop a feature or driver that
46 falls into this category, or you have a situation that requires
47 using these features, you should probably say N here, which will
48 cause the configurator to present you with fewer choices. If
49 you say Y here, you will be offered the choice of using features or
50 drivers that are currently considered to be in the alpha-test phase.
57 depends on BROKEN || !SMP
62 depends on SMP || PREEMPT
65 config INIT_ENV_ARG_LIMIT
70 Maximum of each of the number of arguments and environment
71 variables passed to init from the kernel command line.
75 string "Local version - append to kernel release"
77 Append an extra string to the end of your kernel version.
78 This will show up when you type uname, for example.
79 The string you set here will be appended after the contents of
80 any files with a filename matching localversion* in your
81 object and source tree, in that order. Your total string can
82 be a maximum of 64 characters.
84 config LOCALVERSION_AUTO
85 bool "Automatically append version information to the version string"
88 This will try to automatically determine if the current tree is a
89 release tree by looking for git tags that belong to the current
92 A string of the format -gxxxxxxxx will be added to the localversion
93 if a git-based tree is found. The string generated by this will be
94 appended after any matching localversion* files, and after the value
95 set in CONFIG_LOCALVERSION.
97 (The actual string used here is the first eight characters produced
98 by running the command:
100 $ git rev-parse --verify HEAD
102 which is done within the script "scripts/setlocalversion".)
105 bool "Support for paging of anonymous memory (swap)"
106 depends on MMU && BLOCK
109 This option allows you to choose whether you want to have support
110 for so called swap devices or swap files in your kernel that are
111 used to provide more virtual memory than the actual RAM present
112 in your computer. If unsure say Y.
117 Inter Process Communication is a suite of library functions and
118 system calls which let processes (running programs) synchronize and
119 exchange information. It is generally considered to be a good thing,
120 and some programs won't run unless you say Y here. In particular, if
121 you want to run the DOS emulator dosemu under Linux (read the
122 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
123 you'll need to say Y here.
125 You can find documentation about IPC with "info ipc" and also in
126 section 6.4 of the Linux Programmer's Guide, available from
127 <http://www.tldp.org/guides.html>.
129 config SYSVIPC_SYSCTL
136 bool "POSIX Message Queues"
137 depends on NET && EXPERIMENTAL
139 POSIX variant of message queues is a part of IPC. In POSIX message
140 queues every message has a priority which decides about succession
141 of receiving it by a process. If you want to compile and run
142 programs written e.g. for Solaris with use of its POSIX message
143 queues (functions mq_*) say Y here.
145 POSIX message queues are visible as a filesystem called 'mqueue'
146 and can be mounted somewhere if you want to do filesystem
147 operations on message queues.
151 config BSD_PROCESS_ACCT
152 bool "BSD Process Accounting"
154 If you say Y here, a user level program will be able to instruct the
155 kernel (via a special system call) to write process accounting
156 information to a file: whenever a process exits, information about
157 that process will be appended to the file by the kernel. The
158 information includes things such as creation time, owning user,
159 command name, memory usage, controlling terminal etc. (the complete
160 list is in the struct acct in <file:include/linux/acct.h>). It is
161 up to the user level program to do useful things with this
162 information. This is generally a good idea, so say Y.
164 config BSD_PROCESS_ACCT_V3
165 bool "BSD Process Accounting version 3 file format"
166 depends on BSD_PROCESS_ACCT
169 If you say Y here, the process accounting information is written
170 in a new file format that also logs the process IDs of each
171 process and it's parent. Note that this file format is incompatible
172 with previous v0/v1/v2 file formats, so you will need updated tools
173 for processing it. A preliminary version of these tools is available
174 at <http://www.gnu.org/software/acct/>.
177 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
181 Export selected statistics for tasks/processes through the
182 generic netlink interface. Unlike BSD process accounting, the
183 statistics are available during the lifetime of tasks/processes as
184 responses to commands. Like BSD accounting, they are sent to user
189 config TASK_DELAY_ACCT
190 bool "Enable per-task delay accounting (EXPERIMENTAL)"
193 Collect information on time spent by a task waiting for system
194 resources like cpu, synchronous block I/O completion and swapping
195 in pages. Such statistics can help in setting a task's priorities
196 relative to other tasks for cpu, io, rss limits etc.
201 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
204 Collect extended task accounting data and send the data
205 to userland for processing over the taskstats interface.
209 config TASK_IO_ACCOUNTING
210 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
211 depends on TASK_XACCT
213 Collect information on the number of bytes of storage I/O which this
219 bool "Auditing support"
222 Enable auditing infrastructure that can be used with another
223 kernel subsystem, such as SELinux (which requires this for
224 logging of avc messages output). Does not do system-call
225 auditing without CONFIG_AUDITSYSCALL.
228 bool "Enable system-call auditing support"
229 depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64|| SUPERH)
230 default y if SECURITY_SELINUX
232 Enable low-overhead system-call auditing infrastructure that
233 can be used independently or with another kernel subsystem,
234 such as SELinux. To use audit's filesystem watch feature, please
235 ensure that INOTIFY is configured.
239 depends on AUDITSYSCALL && INOTIFY
242 tristate "Kernel .config support"
244 This option enables the complete Linux kernel ".config" file
245 contents to be saved in the kernel. It provides documentation
246 of which kernel options are used in a running kernel or in an
247 on-disk kernel. This information can be extracted from the kernel
248 image file with the script scripts/extract-ikconfig and used as
249 input to rebuild the current kernel or to build another kernel.
250 It can also be extracted from a running kernel by reading
251 /proc/config.gz if enabled (below).
254 bool "Enable access to .config through /proc/config.gz"
255 depends on IKCONFIG && PROC_FS
257 This option enables access to the kernel configuration file
258 through /proc/config.gz.
261 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
265 Select kernel log buffer size as a power of 2.
275 bool "Control Group support"
277 This option will let you use process cgroup subsystems
283 bool "Example debug cgroup subsystem"
287 This option enables a simple cgroup subsystem that
288 exports useful debugging information about the cgroups
294 bool "Namespace cgroup subsystem"
297 Provides a simple namespace cgroup subsystem to
298 provide hierarchical naming of sets of namespaces,
299 for instance virtual servers and checkpoint/restart
302 config CGROUP_FREEZER
303 bool "control group freezer subsystem"
306 Provides a way to freeze and unfreeze all tasks in a
310 bool "Device controller for cgroups"
311 depends on CGROUPS && EXPERIMENTAL
313 Provides a cgroup implementing whitelists for devices which
314 a process in the cgroup can mknod or open.
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.
328 # Architectures with an unreliable sched_clock() should select this:
330 config HAVE_UNSTABLE_SCHED_CLOCK
334 bool "Group CPU scheduler"
335 depends on EXPERIMENTAL
338 This feature lets CPU scheduler recognize task groups and control CPU
339 bandwidth allocation to such task groups.
341 config FAIR_GROUP_SCHED
342 bool "Group scheduling for SCHED_OTHER"
343 depends on GROUP_SCHED
346 config RT_GROUP_SCHED
347 bool "Group scheduling for SCHED_RR/FIFO"
348 depends on EXPERIMENTAL
349 depends on GROUP_SCHED
352 This feature lets you explicitly allocate real CPU bandwidth
353 to users or control groups (depending on the "Basis for grouping tasks"
354 setting below. If enabled, it will also make it impossible to
355 schedule realtime tasks for non-root users until you allocate
356 realtime bandwidth for them.
357 See Documentation/sched-rt-group.txt for more information.
360 depends on GROUP_SCHED
361 prompt "Basis for grouping tasks"
367 This option will choose userid as the basis for grouping
368 tasks, thus providing equal CPU bandwidth to each user.
371 bool "Control groups"
374 This option allows you to create arbitrary task groups
375 using the "cgroup" pseudo filesystem and control
376 the cpu bandwidth allocated to each such task group.
377 Refer to Documentation/cgroups.txt for more information
378 on "cgroup" pseudo filesystem.
382 config CGROUP_CPUACCT
383 bool "Simple CPU accounting cgroup subsystem"
386 Provides a simple Resource Controller for monitoring the
387 total CPU consumed by the tasks in a cgroup
389 config RESOURCE_COUNTERS
390 bool "Resource counters"
392 This option enables controller independent resource accounting
393 infrastructure that works with cgroups
399 config CGROUP_MEM_RES_CTLR
400 bool "Memory Resource Controller for Control Groups"
401 depends on CGROUPS && RESOURCE_COUNTERS
404 Provides a memory resource controller that manages both page cache and
407 Note that setting this option increases fixed memory overhead
408 associated with each page of memory in the system by 4/8 bytes
409 and also increases cache misses because struct page on many 64bit
410 systems will not fit into a single cache line anymore.
412 Only enable when you're ok with these trade offs and really
413 sure you need the memory resource controller.
415 This config option also selects MM_OWNER config option, which
416 could in turn add some fork/exit overhead.
418 config SYSFS_DEPRECATED
421 config SYSFS_DEPRECATED_V2
422 bool "Create deprecated sysfs files"
425 select SYSFS_DEPRECATED
427 This option creates deprecated symlinks such as the
428 "device"-link, the <subsystem>:<name>-link, and the
429 "bus"-link. It may also add deprecated key in the
431 None of these features or values should be used today, as
432 they export driver core implementation details to userspace
433 or export properties which can't be kept stable across kernel
436 If enabled, this option will also move any device structures
437 that belong to a class, back into the /sys/class hierarchy, in
438 order to support older versions of udev and some userspace
441 If you are using a distro with the most recent userspace
442 packages, it should be safe to say N here.
444 config PROC_PID_CPUSET
445 bool "Include legacy /proc/<pid>/cpuset file"
450 bool "Kernel->user space relay support (formerly relayfs)"
452 This option enables support for relay interface support in
453 certain file systems (such as debugfs).
454 It is designed to provide an efficient mechanism for tools and
455 facilities to relay large amounts of data from kernel space to
461 bool "Namespaces support" if EMBEDDED
464 Provides the way to make tasks work with different objects using
465 the same id. For example same IPC id may refer to different objects
466 or same user id or pid may refer to different tasks when used in
467 different namespaces.
471 depends on NAMESPACES
473 In this namespace tasks see different info provided with the
478 depends on NAMESPACES && SYSVIPC
480 In this namespace tasks work with IPC ids which correspond to
481 different IPC objects in different namespaces
484 bool "User namespace (EXPERIMENTAL)"
485 depends on NAMESPACES && EXPERIMENTAL
487 This allows containers, i.e. vservers, to use user namespaces
488 to provide different user info for different servers.
492 bool "PID Namespaces (EXPERIMENTAL)"
494 depends on NAMESPACES && EXPERIMENTAL
496 Support process id namespaces. This allows having multiple
497 process with the same pid as long as they are in different
498 pid namespaces. This is a building block of containers.
500 Unless you want to work with an experimental feature
503 config BLK_DEV_INITRD
504 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
505 depends on BROKEN || !FRV
507 The initial RAM filesystem is a ramfs which is loaded by the
508 boot loader (loadlin or lilo) and that is mounted as root
509 before the normal boot procedure. It is typically used to
510 load modules needed to mount the "real" root file system,
511 etc. See <file:Documentation/initrd.txt> for details.
513 If RAM disk support (BLK_DEV_RAM) is also included, this
514 also enables initial RAM disk (initrd) support and adds
515 15 Kbytes (more on some other architectures) to the kernel size.
525 config CC_OPTIMIZE_FOR_SIZE
526 bool "Optimize for size"
529 Enabling this option will pass "-Os" instead of "-O2" to gcc
530 resulting in a smaller kernel.
538 bool "Configure standard kernel features (for small systems)"
540 This option allows certain base kernel options and settings
541 to be disabled or tweaked. This is for specialized
542 environments which can tolerate a "non-standard" kernel.
543 Only use this if you really know what you are doing.
546 bool "Enable 16-bit UID system calls" if EMBEDDED
547 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
550 This enables the legacy 16-bit UID syscall wrappers.
552 config SYSCTL_SYSCALL
553 bool "Sysctl syscall support" if EMBEDDED
557 sys_sysctl uses binary paths that have been found challenging
558 to properly maintain and use. The interface in /proc/sys
559 using paths with ascii names is now the primary path to this
562 Almost nothing using the binary sysctl interface so if you are
563 trying to save some space it is probably safe to disable this,
564 making your kernel marginally smaller.
566 If unsure say Y here.
569 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
572 Say Y here to let the kernel print out symbolic crash information and
573 symbolic stack backtraces. This increases the size of the kernel
574 somewhat, as all symbols have to be loaded into the kernel image.
577 bool "Include all symbols in kallsyms"
578 depends on DEBUG_KERNEL && KALLSYMS
580 Normally kallsyms only contains the symbols of functions, for nicer
581 OOPS messages. Some debuggers can use kallsyms for other
582 symbols too: say Y here to include all symbols, if you need them
583 and you don't care about adding 300k to the size of your kernel.
587 config KALLSYMS_EXTRA_PASS
588 bool "Do an extra kallsyms pass"
591 If kallsyms is not working correctly, the build will fail with
592 inconsistent kallsyms data. If that occurs, log a bug report and
593 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
594 Always say N here unless you find a bug in kallsyms, which must be
595 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
596 you wait for kallsyms to be fixed.
600 bool "Support for hot-pluggable devices" if EMBEDDED
603 This option is provided for the case where no hotplug or uevent
604 capabilities is wanted by the kernel. You should only consider
605 disabling this option for embedded systems that do not use modules, a
606 dynamic /dev tree, or dynamic device discovery. Just say Y.
610 bool "Enable support for printk" if EMBEDDED
612 This option enables normal printk support. Removing it
613 eliminates most of the message strings from the kernel image
614 and makes the kernel more or less silent. As this makes it
615 very difficult to diagnose system problems, saying N here is
616 strongly discouraged.
619 bool "BUG() support" if EMBEDDED
622 Disabling this option eliminates support for BUG and WARN, reducing
623 the size of your kernel image and potentially quietly ignoring
624 numerous fatal conditions. You should only consider disabling this
625 option for embedded systems with no facilities for reporting errors.
630 bool "Enable ELF core dumps" if EMBEDDED
632 Enable support for generating core dumps. Disabling saves about 4k.
634 config PCSPKR_PLATFORM
635 bool "Enable PC-Speaker support" if EMBEDDED
636 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
639 This option allows to disable the internal PC-Speaker
640 support, saving some memory.
643 bool "Disable heap randomization"
646 Randomizing heap placement makes heap exploits harder, but it
647 also breaks ancient binaries (including anything libc5 based).
648 This option changes the bootup default to heap randomization
649 disabled, and can be overriden runtime by setting
650 /proc/sys/kernel/randomize_va_space to 2.
652 On non-ancient distros (post-2000 ones) N is usually a safe choice.
656 bool "Enable full-sized data structures for core" if EMBEDDED
658 Disabling this option reduces the size of miscellaneous core
659 kernel data structures. This saves memory on small machines,
660 but may reduce performance.
663 bool "Enable futex support" if EMBEDDED
667 Disabling this option will cause the kernel to be built without
668 support for "fast userspace mutexes". The resulting kernel may not
669 run glibc-based applications correctly.
675 bool "Enable eventpoll support" if EMBEDDED
679 Disabling this option will cause the kernel to be built without
680 support for epoll family of system calls.
683 bool "Enable signalfd() system call" if EMBEDDED
687 Enable the signalfd() system call that allows to receive signals
688 on a file descriptor.
693 bool "Enable timerfd() system call" if EMBEDDED
697 Enable the timerfd() system call that allows to receive timer
698 events on a file descriptor.
703 bool "Enable eventfd() system call" if EMBEDDED
707 Enable the eventfd() system call that allows to receive both
708 kernel notification (ie. KAIO) or userspace notifications.
713 bool "Use full shmem filesystem" if EMBEDDED
717 The shmem is an internal filesystem used to manage shared memory.
718 It is backed by swap and manages resource limits. It is also exported
719 to userspace as tmpfs if TMPFS is enabled. Disabling this
720 option replaces shmem and tmpfs with the much simpler ramfs code,
721 which may be appropriate on small systems without swap.
724 bool "Enable AIO support" if EMBEDDED
727 This option enables POSIX asynchronous I/O which may by used
728 by some high performance threaded applications. Disabling
729 this option saves about 7k.
731 config VM_EVENT_COUNTERS
733 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
735 VM event counters are needed for event counts to be shown.
736 This option allows the disabling of the VM event counters
737 on EMBEDDED systems. /proc/vmstat will only show page counts
738 if VM event counters are disabled.
742 bool "Enable PCI quirk workarounds" if EMBEDDED && PCI
744 This enables workarounds for various PCI chipset
745 bugs/quirks. Disable this only if your target machine is
746 unaffected by PCI quirks.
750 bool "Enable SLUB debugging support" if EMBEDDED
751 depends on SLUB && SYSFS
753 SLUB has extensive debug support features. Disabling these can
754 result in significant savings in code size. This also disables
755 SLUB sysfs support. /sys/slab will not exist and there will be
756 no support for cache validation etc.
759 prompt "Choose SLAB allocator"
762 This option allows to select a slab allocator.
767 The regular slab allocator that is established and known to work
768 well in all environments. It organizes cache hot objects in
769 per cpu and per node queues. SLAB is the default choice for
773 bool "SLUB (Unqueued Allocator)"
775 SLUB is a slab allocator that minimizes cache line usage
776 instead of managing queues of cached objects (SLAB approach).
777 Per cpu caching is realized using slabs of objects instead
778 of queues of objects. SLUB can use memory efficiently
779 and has enhanced diagnostics.
783 bool "SLOB (Simple Allocator)"
785 SLOB replaces the stock allocator with a drastically simpler
786 allocator. SLOB is generally more space efficient but
787 does not perform as well on large systems.
792 bool "Profiling support (EXPERIMENTAL)"
794 Say Y here to enable the extended profiling support mechanisms used
795 by profilers such as OProfile.
798 # Place an empty function call at each tracepoint site. Can be
799 # dynamically changed for a probe function.
805 bool "Activate markers"
807 Place an empty function call at each marker site. Can be
808 dynamically changed for a probe function.
810 source "arch/Kconfig"
812 endmenu # General setup
814 config HAVE_GENERIC_DMA_COHERENT
821 depends on SLAB || SLUB_DEBUG
834 default 0 if BASE_FULL
835 default 1 if !BASE_FULL
838 bool "Enable loadable module support"
840 Kernel modules are small pieces of compiled code which can
841 be inserted in the running kernel, rather than being
842 permanently built into the kernel. You use the "modprobe"
843 tool to add (and sometimes remove) them. If you say Y here,
844 many parts of the kernel can be built as modules (by
845 answering M instead of Y where indicated): this is most
846 useful for infrequently used options which are not required
847 for booting. For more information, see the man pages for
848 modprobe, lsmod, modinfo, insmod and rmmod.
850 If you say Y here, you will need to run "make
851 modules_install" to put the modules under /lib/modules/
852 where modprobe can find them (you may need to be root to do
859 config MODULE_FORCE_LOAD
860 bool "Forced module loading"
863 Allow loading of modules without version information (ie. modprobe
864 --force). Forced module loading sets the 'F' (forced) taint flag and
865 is usually a really bad idea.
868 bool "Module unloading"
870 Without this option you will not be able to unload any
871 modules (note that some modules may not be unloadable
872 anyway), which makes your kernel smaller, faster
873 and simpler. If unsure, say Y.
875 config MODULE_FORCE_UNLOAD
876 bool "Forced module unloading"
877 depends on MODULE_UNLOAD && EXPERIMENTAL
879 This option allows you to force a module to unload, even if the
880 kernel believes it is unsafe: the kernel will remove the module
881 without waiting for anyone to stop using it (using the -f option to
882 rmmod). This is mainly for kernel developers and desperate users.
886 bool "Module versioning support"
888 Usually, you have to use modules compiled with your kernel.
889 Saying Y here makes it sometimes possible to use modules
890 compiled for different kernels, by adding enough information
891 to the modules to (hopefully) spot any changes which would
892 make them incompatible with the kernel you are running. If
895 config MODULE_SRCVERSION_ALL
896 bool "Source checksum for all modules"
898 Modules which contain a MODULE_VERSION get an extra "srcversion"
899 field inserted into their modinfo section, which contains a
900 sum of the source files which made it. This helps maintainers
901 see exactly which source was used to build a module (since
902 others sometimes change the module source without updating
903 the version). With this option, such a "srcversion" field
904 will be created for all modules. If unsure, say N.
909 This is being removed soon. These days, CONFIG_MODULES
910 implies CONFIG_KMOD, so use that instead.
917 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
919 Need stop_machine() primitive.
921 source "block/Kconfig"
923 config PREEMPT_NOTIFIERS
927 def_bool !PREEMPT_RCU
929 This option selects the classic RCU implementation that is
930 designed for best read-side performance on non-realtime
931 systems. Classic RCU is the default. Note that the
932 PREEMPT_RCU symbol is used to select/deselect this option.
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