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42 drivers that have been replaced by something else, and/or are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/scheduler/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 anonymous
405 memory and page cache. (See Documentation/controllers/memory.txt)
407 Note that setting this option increases fixed memory overhead
408 associated with each page of memory in the system. By this,
409 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
410 usage tracking struct at boot. Total amount of this is printed out
413 Only enable when you're ok with these trade offs and really
414 sure you need the memory resource controller. Even when you enable
415 this, you can set "cgroup_disable=memory" at your boot option to
416 disable memory resource controller and you can avoid overheads.
417 (and lose benefits of memory resource contoller)
419 This config option also selects MM_OWNER config option, which
420 could in turn add some fork/exit overhead.
422 config SYSFS_DEPRECATED
425 config SYSFS_DEPRECATED_V2
426 bool "Create deprecated sysfs files"
429 select SYSFS_DEPRECATED
431 This option creates deprecated symlinks such as the
432 "device"-link, the <subsystem>:<name>-link, and the
433 "bus"-link. It may also add deprecated key in the
435 None of these features or values should be used today, as
436 they export driver core implementation details to userspace
437 or export properties which can't be kept stable across kernel
440 If enabled, this option will also move any device structures
441 that belong to a class, back into the /sys/class hierarchy, in
442 order to support older versions of udev and some userspace
445 If you are using a distro with the most recent userspace
446 packages, it should be safe to say N here.
448 config PROC_PID_CPUSET
449 bool "Include legacy /proc/<pid>/cpuset file"
454 bool "Kernel->user space relay support (formerly relayfs)"
456 This option enables support for relay interface support in
457 certain file systems (such as debugfs).
458 It is designed to provide an efficient mechanism for tools and
459 facilities to relay large amounts of data from kernel space to
465 bool "Namespaces support" if EMBEDDED
468 Provides the way to make tasks work with different objects using
469 the same id. For example same IPC id may refer to different objects
470 or same user id or pid may refer to different tasks when used in
471 different namespaces.
475 depends on NAMESPACES
477 In this namespace tasks see different info provided with the
482 depends on NAMESPACES && SYSVIPC
484 In this namespace tasks work with IPC ids which correspond to
485 different IPC objects in different namespaces
488 bool "User namespace (EXPERIMENTAL)"
489 depends on NAMESPACES && EXPERIMENTAL
491 This allows containers, i.e. vservers, to use user namespaces
492 to provide different user info for different servers.
496 bool "PID Namespaces (EXPERIMENTAL)"
498 depends on NAMESPACES && EXPERIMENTAL
500 Support process id namespaces. This allows having multiple
501 process with the same pid as long as they are in different
502 pid namespaces. This is a building block of containers.
504 Unless you want to work with an experimental feature
507 config BLK_DEV_INITRD
508 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
509 depends on BROKEN || !FRV
511 The initial RAM filesystem is a ramfs which is loaded by the
512 boot loader (loadlin or lilo) and that is mounted as root
513 before the normal boot procedure. It is typically used to
514 load modules needed to mount the "real" root file system,
515 etc. See <file:Documentation/initrd.txt> for details.
517 If RAM disk support (BLK_DEV_RAM) is also included, this
518 also enables initial RAM disk (initrd) support and adds
519 15 Kbytes (more on some other architectures) to the kernel size.
529 config CC_OPTIMIZE_FOR_SIZE
530 bool "Optimize for size"
533 Enabling this option will pass "-Os" instead of "-O2" to gcc
534 resulting in a smaller kernel.
542 bool "Configure standard kernel features (for small systems)"
544 This option allows certain base kernel options and settings
545 to be disabled or tweaked. This is for specialized
546 environments which can tolerate a "non-standard" kernel.
547 Only use this if you really know what you are doing.
550 bool "Enable 16-bit UID system calls" if EMBEDDED
551 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
554 This enables the legacy 16-bit UID syscall wrappers.
556 config SYSCTL_SYSCALL
557 bool "Sysctl syscall support" if EMBEDDED
561 sys_sysctl uses binary paths that have been found challenging
562 to properly maintain and use. The interface in /proc/sys
563 using paths with ascii names is now the primary path to this
566 Almost nothing using the binary sysctl interface so if you are
567 trying to save some space it is probably safe to disable this,
568 making your kernel marginally smaller.
570 If unsure say Y here.
573 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
576 Say Y here to let the kernel print out symbolic crash information and
577 symbolic stack backtraces. This increases the size of the kernel
578 somewhat, as all symbols have to be loaded into the kernel image.
581 bool "Include all symbols in kallsyms"
582 depends on DEBUG_KERNEL && KALLSYMS
584 Normally kallsyms only contains the symbols of functions, for nicer
585 OOPS messages. Some debuggers can use kallsyms for other
586 symbols too: say Y here to include all symbols, if you need them
587 and you don't care about adding 300k to the size of your kernel.
591 config KALLSYMS_EXTRA_PASS
592 bool "Do an extra kallsyms pass"
595 If kallsyms is not working correctly, the build will fail with
596 inconsistent kallsyms data. If that occurs, log a bug report and
597 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
598 Always say N here unless you find a bug in kallsyms, which must be
599 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
600 you wait for kallsyms to be fixed.
604 bool "Support for hot-pluggable devices" if EMBEDDED
607 This option is provided for the case where no hotplug or uevent
608 capabilities is wanted by the kernel. You should only consider
609 disabling this option for embedded systems that do not use modules, a
610 dynamic /dev tree, or dynamic device discovery. Just say Y.
614 bool "Enable support for printk" if EMBEDDED
616 This option enables normal printk support. Removing it
617 eliminates most of the message strings from the kernel image
618 and makes the kernel more or less silent. As this makes it
619 very difficult to diagnose system problems, saying N here is
620 strongly discouraged.
623 bool "BUG() support" if EMBEDDED
626 Disabling this option eliminates support for BUG and WARN, reducing
627 the size of your kernel image and potentially quietly ignoring
628 numerous fatal conditions. You should only consider disabling this
629 option for embedded systems with no facilities for reporting errors.
634 bool "Enable ELF core dumps" if EMBEDDED
636 Enable support for generating core dumps. Disabling saves about 4k.
638 config PCSPKR_PLATFORM
639 bool "Enable PC-Speaker support" if EMBEDDED
640 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
643 This option allows to disable the internal PC-Speaker
644 support, saving some memory.
647 bool "Disable heap randomization"
650 Randomizing heap placement makes heap exploits harder, but it
651 also breaks ancient binaries (including anything libc5 based).
652 This option changes the bootup default to heap randomization
653 disabled, and can be overriden runtime by setting
654 /proc/sys/kernel/randomize_va_space to 2.
656 On non-ancient distros (post-2000 ones) N is usually a safe choice.
660 bool "Enable full-sized data structures for core" if EMBEDDED
662 Disabling this option reduces the size of miscellaneous core
663 kernel data structures. This saves memory on small machines,
664 but may reduce performance.
667 bool "Enable futex support" if EMBEDDED
671 Disabling this option will cause the kernel to be built without
672 support for "fast userspace mutexes". The resulting kernel may not
673 run glibc-based applications correctly.
679 bool "Enable eventpoll support" if EMBEDDED
683 Disabling this option will cause the kernel to be built without
684 support for epoll family of system calls.
687 bool "Enable signalfd() system call" if EMBEDDED
691 Enable the signalfd() system call that allows to receive signals
692 on a file descriptor.
697 bool "Enable timerfd() system call" if EMBEDDED
701 Enable the timerfd() system call that allows to receive timer
702 events on a file descriptor.
707 bool "Enable eventfd() system call" if EMBEDDED
711 Enable the eventfd() system call that allows to receive both
712 kernel notification (ie. KAIO) or userspace notifications.
717 bool "Use full shmem filesystem" if EMBEDDED
721 The shmem is an internal filesystem used to manage shared memory.
722 It is backed by swap and manages resource limits. It is also exported
723 to userspace as tmpfs if TMPFS is enabled. Disabling this
724 option replaces shmem and tmpfs with the much simpler ramfs code,
725 which may be appropriate on small systems without swap.
728 bool "Enable AIO support" if EMBEDDED
731 This option enables POSIX asynchronous I/O which may by used
732 by some high performance threaded applications. Disabling
733 this option saves about 7k.
735 config VM_EVENT_COUNTERS
737 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
739 VM event counters are needed for event counts to be shown.
740 This option allows the disabling of the VM event counters
741 on EMBEDDED systems. /proc/vmstat will only show page counts
742 if VM event counters are disabled.
746 bool "Enable PCI quirk workarounds" if EMBEDDED
749 This enables workarounds for various PCI chipset
750 bugs/quirks. Disable this only if your target machine is
751 unaffected by PCI quirks.
755 bool "Enable SLUB debugging support" if EMBEDDED
756 depends on SLUB && SYSFS
758 SLUB has extensive debug support features. Disabling these can
759 result in significant savings in code size. This also disables
760 SLUB sysfs support. /sys/slab will not exist and there will be
761 no support for cache validation etc.
764 prompt "Choose SLAB allocator"
767 This option allows to select a slab allocator.
772 The regular slab allocator that is established and known to work
773 well in all environments. It organizes cache hot objects in
774 per cpu and per node queues.
777 bool "SLUB (Unqueued Allocator)"
779 SLUB is a slab allocator that minimizes cache line usage
780 instead of managing queues of cached objects (SLAB approach).
781 Per cpu caching is realized using slabs of objects instead
782 of queues of objects. SLUB can use memory efficiently
783 and has enhanced diagnostics. SLUB is the default choice for
788 bool "SLOB (Simple Allocator)"
790 SLOB replaces the stock allocator with a drastically simpler
791 allocator. SLOB is generally more space efficient but
792 does not perform as well on large systems.
797 bool "Profiling support (EXPERIMENTAL)"
799 Say Y here to enable the extended profiling support mechanisms used
800 by profilers such as OProfile.
803 # Place an empty function call at each tracepoint site. Can be
804 # dynamically changed for a probe function.
810 bool "Activate markers"
812 Place an empty function call at each marker site. Can be
813 dynamically changed for a probe function.
815 source "arch/Kconfig"
817 endmenu # General setup
819 config HAVE_GENERIC_DMA_COHERENT
826 depends on SLAB || SLUB_DEBUG
839 default 0 if BASE_FULL
840 default 1 if !BASE_FULL
843 bool "Enable loadable module support"
845 Kernel modules are small pieces of compiled code which can
846 be inserted in the running kernel, rather than being
847 permanently built into the kernel. You use the "modprobe"
848 tool to add (and sometimes remove) them. If you say Y here,
849 many parts of the kernel can be built as modules (by
850 answering M instead of Y where indicated): this is most
851 useful for infrequently used options which are not required
852 for booting. For more information, see the man pages for
853 modprobe, lsmod, modinfo, insmod and rmmod.
855 If you say Y here, you will need to run "make
856 modules_install" to put the modules under /lib/modules/
857 where modprobe can find them (you may need to be root to do
864 config MODULE_FORCE_LOAD
865 bool "Forced module loading"
868 Allow loading of modules without version information (ie. modprobe
869 --force). Forced module loading sets the 'F' (forced) taint flag and
870 is usually a really bad idea.
873 bool "Module unloading"
875 Without this option you will not be able to unload any
876 modules (note that some modules may not be unloadable
877 anyway), which makes your kernel smaller, faster
878 and simpler. If unsure, say Y.
880 config MODULE_FORCE_UNLOAD
881 bool "Forced module unloading"
882 depends on MODULE_UNLOAD && EXPERIMENTAL
884 This option allows you to force a module to unload, even if the
885 kernel believes it is unsafe: the kernel will remove the module
886 without waiting for anyone to stop using it (using the -f option to
887 rmmod). This is mainly for kernel developers and desperate users.
891 bool "Module versioning support"
893 Usually, you have to use modules compiled with your kernel.
894 Saying Y here makes it sometimes possible to use modules
895 compiled for different kernels, by adding enough information
896 to the modules to (hopefully) spot any changes which would
897 make them incompatible with the kernel you are running. If
900 config MODULE_SRCVERSION_ALL
901 bool "Source checksum for all modules"
903 Modules which contain a MODULE_VERSION get an extra "srcversion"
904 field inserted into their modinfo section, which contains a
905 sum of the source files which made it. This helps maintainers
906 see exactly which source was used to build a module (since
907 others sometimes change the module source without updating
908 the version). With this option, such a "srcversion" field
909 will be created for all modules. If unsure, say N.
914 This is being removed soon. These days, CONFIG_MODULES
915 implies CONFIG_KMOD, so use that instead.
922 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
924 Need stop_machine() primitive.
926 source "block/Kconfig"
928 config PREEMPT_NOTIFIERS
932 def_bool !PREEMPT_RCU
934 This option selects the classic RCU implementation that is
935 designed for best read-side performance on non-realtime
936 systems. Classic RCU is the default. Note that the
937 PREEMPT_RCU symbol is used to select/deselect this option.
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