5 default "/lib/modules/$UNAME_RELEASE/.config"
6 default "/etc/kernel-config"
7 default "/boot/config-$UNAME_RELEASE"
8 default "arch/$ARCH/defconfig"
13 bool "Prompt for development and/or incomplete code/drivers"
15 Some of the various things that Linux supports (such as network
16 drivers, file systems, network protocols, etc.) can be in a state
17 of development where the functionality, stability, or the level of
18 testing is not yet high enough for general use. This is usually
19 known as the "alpha-test" phase among developers. If a feature is
20 currently in alpha-test, then the developers usually discourage
21 uninformed widespread use of this feature by the general public to
22 avoid "Why doesn't this work?" type mail messages. However, active
23 testing and use of these systems is welcomed. Just be aware that it
24 may not meet the normal level of reliability or it may fail to work
25 in some special cases. Detailed bug reports from people familiar
26 with the kernel internals are usually welcomed by the developers
27 (before submitting bug reports, please read the documents
28 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
29 <file:Documentation/BUG-HUNTING>, and
30 <file:Documentation/oops-tracing.txt> in the kernel source).
32 This option will also make obsoleted drivers available. These are
33 drivers that have been replaced by something else, and/or are
34 scheduled to be removed in a future kernel release.
36 Unless you intend to help test and develop a feature or driver that
37 falls into this category, or you have a situation that requires
38 using these features, you should probably say N here, which will
39 cause the configurator to present you with fewer choices. If
40 you say Y here, you will be offered the choice of using features or
41 drivers that are currently considered to be in the alpha-test phase.
48 depends on BROKEN || !SMP
53 depends on SMP || PREEMPT
56 config INIT_ENV_ARG_LIMIT
61 Maximum of each of the number of arguments and environment
62 variables passed to init from the kernel command line.
66 string "Local version - append to kernel release"
68 Append an extra string to the end of your kernel version.
69 This will show up when you type uname, for example.
70 The string you set here will be appended after the contents of
71 any files with a filename matching localversion* in your
72 object and source tree, in that order. Your total string can
73 be a maximum of 64 characters.
75 config LOCALVERSION_AUTO
76 bool "Automatically append version information to the version string"
79 This will try to automatically determine if the current tree is a
80 release tree by looking for git tags that belong to the current
83 A string of the format -gxxxxxxxx will be added to the localversion
84 if a git-based tree is found. The string generated by this will be
85 appended after any matching localversion* files, and after the value
86 set in CONFIG_LOCALVERSION.
88 (The actual string used here is the first eight characters produced
89 by running the command:
91 $ git rev-parse --verify HEAD
93 which is done within the script "scripts/setlocalversion".)
96 bool "Support for paging of anonymous memory (swap)"
97 depends on MMU && BLOCK
100 This option allows you to choose whether you want to have support
101 for so called swap devices or swap files in your kernel that are
102 used to provide more virtual memory than the actual RAM present
103 in your computer. If unsure say Y.
108 Inter Process Communication is a suite of library functions and
109 system calls which let processes (running programs) synchronize and
110 exchange information. It is generally considered to be a good thing,
111 and some programs won't run unless you say Y here. In particular, if
112 you want to run the DOS emulator dosemu under Linux (read the
113 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
114 you'll need to say Y here.
116 You can find documentation about IPC with "info ipc" and also in
117 section 6.4 of the Linux Programmer's Guide, available from
118 <http://www.tldp.org/guides.html>.
120 config SYSVIPC_SYSCTL
127 bool "POSIX Message Queues"
128 depends on NET && EXPERIMENTAL
130 POSIX variant of message queues is a part of IPC. In POSIX message
131 queues every message has a priority which decides about succession
132 of receiving it by a process. If you want to compile and run
133 programs written e.g. for Solaris with use of its POSIX message
134 queues (functions mq_*) say Y here.
136 POSIX message queues are visible as a filesystem called 'mqueue'
137 and can be mounted somewhere if you want to do filesystem
138 operations on message queues.
142 config BSD_PROCESS_ACCT
143 bool "BSD Process Accounting"
145 If you say Y here, a user level program will be able to instruct the
146 kernel (via a special system call) to write process accounting
147 information to a file: whenever a process exits, information about
148 that process will be appended to the file by the kernel. The
149 information includes things such as creation time, owning user,
150 command name, memory usage, controlling terminal etc. (the complete
151 list is in the struct acct in <file:include/linux/acct.h>). It is
152 up to the user level program to do useful things with this
153 information. This is generally a good idea, so say Y.
155 config BSD_PROCESS_ACCT_V3
156 bool "BSD Process Accounting version 3 file format"
157 depends on BSD_PROCESS_ACCT
160 If you say Y here, the process accounting information is written
161 in a new file format that also logs the process IDs of each
162 process and it's parent. Note that this file format is incompatible
163 with previous v0/v1/v2 file formats, so you will need updated tools
164 for processing it. A preliminary version of these tools is available
165 at <http://www.physik3.uni-rostock.de/tim/kernel/utils/acct/>.
168 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
172 Export selected statistics for tasks/processes through the
173 generic netlink interface. Unlike BSD process accounting, the
174 statistics are available during the lifetime of tasks/processes as
175 responses to commands. Like BSD accounting, they are sent to user
180 config TASK_DELAY_ACCT
181 bool "Enable per-task delay accounting (EXPERIMENTAL)"
184 Collect information on time spent by a task waiting for system
185 resources like cpu, synchronous block I/O completion and swapping
186 in pages. Such statistics can help in setting a task's priorities
187 relative to other tasks for cpu, io, rss limits etc.
192 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
195 Collect extended task accounting data and send the data
196 to userland for processing over the taskstats interface.
200 config TASK_IO_ACCOUNTING
201 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
202 depends on TASK_XACCT
204 Collect information on the number of bytes of storage I/O which this
210 bool "User Namespaces (EXPERIMENTAL)"
212 depends on EXPERIMENTAL
214 Support user namespaces. This allows containers, i.e.
215 vservers, to use user namespaces to provide different
216 user info for different servers. If unsure, say N.
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)
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)"
263 default 17 if S390 || LOCKDEP
264 default 16 if X86_NUMAQ || IA64
268 Select kernel log buffer size as a power of 2.
269 Defaults and Examples:
270 17 => 128 KB for S/390
271 16 => 64 KB for x86 NUMAQ or IA-64
273 14 => 16 KB for uniprocessor
278 bool "Control Group support"
280 This option will let you use process cgroup subsystems
286 bool "Example debug cgroup subsystem"
289 This option enables a simple cgroup subsystem that
290 exports useful debugging information about the cgroups
296 bool "Namespace cgroup subsystem"
299 Provides a simple namespace cgroup subsystem to
300 provide hierarchical naming of sets of namespaces,
301 for instance virtual servers and checkpoint/restart
304 config CGROUP_CPUACCT
305 bool "Simple CPU accounting cgroup subsystem"
308 Provides a simple Resource Controller for monitoring the
309 total CPU consumed by the tasks in a cgroup
312 bool "Cpuset support"
313 depends on SMP && CGROUPS
315 This option will let you create and manage CPUSETs which
316 allow dynamically partitioning a system into sets of CPUs and
317 Memory Nodes and assigning tasks to run only within those sets.
318 This is primarily useful on large SMP or NUMA systems.
322 config FAIR_GROUP_SCHED
323 bool "Fair group CPU scheduler"
326 This feature lets CPU scheduler recognize task groups and control CPU
327 bandwidth allocation to such task groups.
330 depends on FAIR_GROUP_SCHED
331 prompt "Basis for grouping tasks"
332 default FAIR_USER_SCHED
334 config FAIR_USER_SCHED
337 This option will choose userid as the basis for grouping
338 tasks, thus providing equal CPU bandwidth to each user.
340 config FAIR_CGROUP_SCHED
341 bool "Control groups"
344 This option allows you to create arbitrary task groups
345 using the "cgroup" pseudo filesystem and control
346 the cpu bandwidth allocated to each such task group.
347 Refer to Documentation/cgroups.txt for more information
348 on "cgroup" pseudo filesystem.
352 config SYSFS_DEPRECATED
353 bool "Create deprecated sysfs files"
356 This option creates deprecated symlinks such as the
357 "device"-link, the <subsystem>:<name>-link, and the
358 "bus"-link. It may also add deprecated key in the
360 None of these features or values should be used today, as
361 they export driver core implementation details to userspace
362 or export properties which can't be kept stable across kernel
365 If enabled, this option will also move any device structures
366 that belong to a class, back into the /sys/class hierarchy, in
367 order to support older versions of udev.
369 If you are using a distro that was released in 2006 or later,
370 it should be safe to say N here.
372 config PROC_PID_CPUSET
373 bool "Include legacy /proc/<pid>/cpuset file"
378 bool "Kernel->user space relay support (formerly relayfs)"
380 This option enables support for relay interface support in
381 certain file systems (such as debugfs).
382 It is designed to provide an efficient mechanism for tools and
383 facilities to relay large amounts of data from kernel space to
388 config BLK_DEV_INITRD
389 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
390 depends on BROKEN || !FRV
392 The initial RAM filesystem is a ramfs which is loaded by the
393 boot loader (loadlin or lilo) and that is mounted as root
394 before the normal boot procedure. It is typically used to
395 load modules needed to mount the "real" root file system,
396 etc. See <file:Documentation/initrd.txt> for details.
398 If RAM disk support (BLK_DEV_RAM) is also included, this
399 also enables initial RAM disk (initrd) support and adds
400 15 Kbytes (more on some other architectures) to the kernel size.
410 config CC_OPTIMIZE_FOR_SIZE
411 bool "Optimize for size (Look out for broken compilers!)"
413 depends on ARM || H8300 || SUPERH || EXPERIMENTAL
415 Enabling this option will pass "-Os" instead of "-O2" to gcc
416 resulting in a smaller kernel.
418 WARNING: some versions of gcc may generate incorrect code with this
419 option. If problems are observed, a gcc upgrade may be needed.
427 bool "Configure standard kernel features (for small systems)"
429 This option allows certain base kernel options and settings
430 to be disabled or tweaked. This is for specialized
431 environments which can tolerate a "non-standard" kernel.
432 Only use this if you really know what you are doing.
435 bool "Enable 16-bit UID system calls" if EMBEDDED
436 depends on ARM || BFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_COMPAT) || UML || (X86_64 && IA32_EMULATION)
439 This enables the legacy 16-bit UID syscall wrappers.
441 config SYSCTL_SYSCALL
442 bool "Sysctl syscall support" if EMBEDDED
446 sys_sysctl uses binary paths that have been found challenging
447 to properly maintain and use. The interface in /proc/sys
448 using paths with ascii names is now the primary path to this
451 Almost nothing using the binary sysctl interface so if you are
452 trying to save some space it is probably safe to disable this,
453 making your kernel marginally smaller.
455 If unsure say Y here.
458 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
461 Say Y here to let the kernel print out symbolic crash information and
462 symbolic stack backtraces. This increases the size of the kernel
463 somewhat, as all symbols have to be loaded into the kernel image.
466 bool "Include all symbols in kallsyms"
467 depends on DEBUG_KERNEL && KALLSYMS
469 Normally kallsyms only contains the symbols of functions, for nicer
470 OOPS messages. Some debuggers can use kallsyms for other
471 symbols too: say Y here to include all symbols, if you need them
472 and you don't care about adding 300k to the size of your kernel.
476 config KALLSYMS_EXTRA_PASS
477 bool "Do an extra kallsyms pass"
480 If kallsyms is not working correctly, the build will fail with
481 inconsistent kallsyms data. If that occurs, log a bug report and
482 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
483 Always say N here unless you find a bug in kallsyms, which must be
484 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
485 you wait for kallsyms to be fixed.
489 bool "Support for hot-pluggable devices" if EMBEDDED
492 This option is provided for the case where no hotplug or uevent
493 capabilities is wanted by the kernel. You should only consider
494 disabling this option for embedded systems that do not use modules, a
495 dynamic /dev tree, or dynamic device discovery. Just say Y.
499 bool "Enable support for printk" if EMBEDDED
501 This option enables normal printk support. Removing it
502 eliminates most of the message strings from the kernel image
503 and makes the kernel more or less silent. As this makes it
504 very difficult to diagnose system problems, saying N here is
505 strongly discouraged.
508 bool "BUG() support" if EMBEDDED
511 Disabling this option eliminates support for BUG and WARN, reducing
512 the size of your kernel image and potentially quietly ignoring
513 numerous fatal conditions. You should only consider disabling this
514 option for embedded systems with no facilities for reporting errors.
519 bool "Enable ELF core dumps" if EMBEDDED
521 Enable support for generating core dumps. Disabling saves about 4k.
525 bool "Enable full-sized data structures for core" if EMBEDDED
527 Disabling this option reduces the size of miscellaneous core
528 kernel data structures. This saves memory on small machines,
529 but may reduce performance.
532 bool "Enable futex support" if EMBEDDED
536 Disabling this option will cause the kernel to be built without
537 support for "fast userspace mutexes". The resulting kernel may not
538 run glibc-based applications correctly.
544 bool "Enable eventpoll support" if EMBEDDED
548 Disabling this option will cause the kernel to be built without
549 support for epoll family of system calls.
552 bool "Enable signalfd() system call" if EMBEDDED
556 Enable the signalfd() system call that allows to receive signals
557 on a file descriptor.
562 bool "Enable timerfd() system call" if EMBEDDED
567 Enable the timerfd() system call that allows to receive timer
568 events on a file descriptor.
573 bool "Enable eventfd() system call" if EMBEDDED
577 Enable the eventfd() system call that allows to receive both
578 kernel notification (ie. KAIO) or userspace notifications.
583 bool "Use full shmem filesystem" if EMBEDDED
587 The shmem is an internal filesystem used to manage shared memory.
588 It is backed by swap and manages resource limits. It is also exported
589 to userspace as tmpfs if TMPFS is enabled. Disabling this
590 option replaces shmem and tmpfs with the much simpler ramfs code,
591 which may be appropriate on small systems without swap.
593 config VM_EVENT_COUNTERS
595 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
597 VM event counters are needed for event counts to be shown.
598 This option allows the disabling of the VM event counters
599 on EMBEDDED systems. /proc/vmstat will only show page counts
600 if VM event counters are disabled.
604 bool "Enable SLUB debugging support" if EMBEDDED
607 SLUB has extensive debug support features. Disabling these can
608 result in significant savings in code size. This also disables
609 SLUB sysfs support. /sys/slab will not exist and there will be
610 no support for cache validation etc.
613 prompt "Choose SLAB allocator"
616 This option allows to select a slab allocator.
621 The regular slab allocator that is established and known to work
622 well in all environments. It organizes cache hot objects in
623 per cpu and per node queues. SLAB is the default choice for
627 bool "SLUB (Unqueued Allocator)"
629 SLUB is a slab allocator that minimizes cache line usage
630 instead of managing queues of cached objects (SLAB approach).
631 Per cpu caching is realized using slabs of objects instead
632 of queues of objects. SLUB can use memory efficiently
633 and has enhanced diagnostics.
637 bool "SLOB (Simple Allocator)"
639 SLOB replaces the SLAB allocator with a drastically simpler
640 allocator. SLOB is more space efficient than SLAB but does not
641 scale well (single lock for all operations) and is also highly
642 susceptible to fragmentation. SLUB can accomplish a higher object
643 density. It is usually better to use SLUB instead of SLOB.
647 endmenu # General setup
659 default 0 if BASE_FULL
660 default 1 if !BASE_FULL
663 bool "Enable loadable module support"
665 Kernel modules are small pieces of compiled code which can
666 be inserted in the running kernel, rather than being
667 permanently built into the kernel. You use the "modprobe"
668 tool to add (and sometimes remove) them. If you say Y here,
669 many parts of the kernel can be built as modules (by
670 answering M instead of Y where indicated): this is most
671 useful for infrequently used options which are not required
672 for booting. For more information, see the man pages for
673 modprobe, lsmod, modinfo, insmod and rmmod.
675 If you say Y here, you will need to run "make
676 modules_install" to put the modules under /lib/modules/
677 where modprobe can find them (you may need to be root to do
683 bool "Module unloading"
686 Without this option you will not be able to unload any
687 modules (note that some modules may not be unloadable
688 anyway), which makes your kernel slightly smaller and
689 simpler. If unsure, say Y.
691 config MODULE_FORCE_UNLOAD
692 bool "Forced module unloading"
693 depends on MODULE_UNLOAD && EXPERIMENTAL
695 This option allows you to force a module to unload, even if the
696 kernel believes it is unsafe: the kernel will remove the module
697 without waiting for anyone to stop using it (using the -f option to
698 rmmod). This is mainly for kernel developers and desperate users.
702 bool "Module versioning support"
705 Usually, you have to use modules compiled with your kernel.
706 Saying Y here makes it sometimes possible to use modules
707 compiled for different kernels, by adding enough information
708 to the modules to (hopefully) spot any changes which would
709 make them incompatible with the kernel you are running. If
712 config MODULE_SRCVERSION_ALL
713 bool "Source checksum for all modules"
716 Modules which contain a MODULE_VERSION get an extra "srcversion"
717 field inserted into their modinfo section, which contains a
718 sum of the source files which made it. This helps maintainers
719 see exactly which source was used to build a module (since
720 others sometimes change the module source without updating
721 the version). With this option, such a "srcversion" field
722 will be created for all modules. If unsure, say N.
725 bool "Automatic kernel module loading"
728 Normally when you have selected some parts of the kernel to
729 be created as kernel modules, you must load them (using the
730 "modprobe" command) before you can use them. If you say Y
731 here, some parts of the kernel will be able to load modules
732 automatically: when a part of the kernel needs a module, it
733 runs modprobe with the appropriate arguments, thereby
734 loading the module if it is available. If unsure, say Y.
739 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
741 Need stop_machine() primitive.
743 source "block/Kconfig"
745 config PREEMPT_NOTIFIERS
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