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42 drivers that have been replaced by something else, and/or are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 # Architectures with an unreliable sched_clock() should select this:
277 config HAVE_UNSTABLE_SCHED_CLOCK
281 bool "Group CPU scheduler"
282 depends on EXPERIMENTAL
285 This feature lets CPU scheduler recognize task groups and control CPU
286 bandwidth allocation to such task groups.
287 In order to create a group from arbitrary set of processes, use
288 CONFIG_CGROUPS. (See Control Group support.)
290 config FAIR_GROUP_SCHED
291 bool "Group scheduling for SCHED_OTHER"
292 depends on GROUP_SCHED
295 config RT_GROUP_SCHED
296 bool "Group scheduling for SCHED_RR/FIFO"
297 depends on EXPERIMENTAL
298 depends on GROUP_SCHED
301 This feature lets you explicitly allocate real CPU bandwidth
302 to users or control groups (depending on the "Basis for grouping tasks"
303 setting below. If enabled, it will also make it impossible to
304 schedule realtime tasks for non-root users until you allocate
305 realtime bandwidth for them.
306 See Documentation/scheduler/sched-rt-group.txt for more information.
309 depends on GROUP_SCHED
310 prompt "Basis for grouping tasks"
316 This option will choose userid as the basis for grouping
317 tasks, thus providing equal CPU bandwidth to each user.
320 bool "Control groups"
323 This option allows you to create arbitrary task groups
324 using the "cgroup" pseudo filesystem and control
325 the cpu bandwidth allocated to each such task group.
326 Refer to Documentation/cgroups/cgroups.txt for more
327 information on "cgroup" pseudo filesystem.
332 boolean "Control Group support"
334 This option adds support for grouping sets of processes together, for
335 use with process control subsystems such as Cpusets, CFS, memory
336 controls or device isolation.
338 - Documentation/scheduler/sched-design-CFS.txt (CFS)
339 - Documentation/cgroups/ (features for grouping, isolation
340 and resource control)
347 bool "Example debug cgroup subsystem"
351 This option enables a simple cgroup subsystem that
352 exports useful debugging information about the cgroups
358 bool "Namespace cgroup subsystem"
361 Provides a simple namespace cgroup subsystem to
362 provide hierarchical naming of sets of namespaces,
363 for instance virtual servers and checkpoint/restart
366 config CGROUP_FREEZER
367 bool "Freezer cgroup subsystem"
370 Provides a way to freeze and unfreeze all tasks in a
374 bool "Device controller for cgroups"
375 depends on CGROUPS && EXPERIMENTAL
377 Provides a cgroup implementing whitelists for devices which
378 a process in the cgroup can mknod or open.
381 bool "Cpuset support"
382 depends on SMP && CGROUPS
384 This option will let you create and manage CPUSETs which
385 allow dynamically partitioning a system into sets of CPUs and
386 Memory Nodes and assigning tasks to run only within those sets.
387 This is primarily useful on large SMP or NUMA systems.
391 config PROC_PID_CPUSET
392 bool "Include legacy /proc/<pid>/cpuset file"
396 config CGROUP_CPUACCT
397 bool "Simple CPU accounting cgroup subsystem"
400 Provides a simple Resource Controller for monitoring the
401 total CPU consumed by the tasks in a cgroup.
403 config RESOURCE_COUNTERS
404 bool "Resource counters"
406 This option enables controller independent resource accounting
407 infrastructure that works with cgroups.
410 config CGROUP_MEM_RES_CTLR
411 bool "Memory Resource Controller for Control Groups"
412 depends on CGROUPS && RESOURCE_COUNTERS
415 Provides a memory resource controller that manages both anonymous
416 memory and page cache. (See Documentation/controllers/memory.txt)
418 Note that setting this option increases fixed memory overhead
419 associated with each page of memory in the system. By this,
420 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
421 usage tracking struct at boot. Total amount of this is printed out
424 Only enable when you're ok with these trade offs and really
425 sure you need the memory resource controller. Even when you enable
426 this, you can set "cgroup_disable=memory" at your boot option to
427 disable memory resource controller and you can avoid overheads.
428 (and lose benefits of memory resource controller)
430 This config option also selects MM_OWNER config option, which
431 could in turn add some fork/exit overhead.
433 config CGROUP_MEM_RES_CTLR_SWAP
434 bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)"
435 depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL
437 Add swap management feature to memory resource controller. When you
438 enable this, you can limit mem+swap usage per cgroup. In other words,
439 when you disable this, memory resource controller has no cares to
440 usage of swap...a process can exhaust all of the swap. This extension
441 is useful when you want to avoid exhaustion swap but this itself
442 adds more overheads and consumes memory for remembering information.
443 Especially if you use 32bit system or small memory system, please
444 be careful about enabling this. When memory resource controller
445 is disabled by boot option, this will be automatically disabled and
446 there will be no overhead from this. Even when you set this config=y,
447 if boot option "noswapaccount" is set, swap will not be accounted.
454 config SYSFS_DEPRECATED
457 config SYSFS_DEPRECATED_V2
458 bool "Create deprecated sysfs layout for older userspace tools"
461 select SYSFS_DEPRECATED
463 This option switches the layout of sysfs to the deprecated
466 The current sysfs layout features a unified device tree at
467 /sys/devices/, which is able to express a hierarchy between
468 class devices. If the deprecated option is set to Y, the
469 unified device tree is split into a bus device tree at
470 /sys/devices/ and several individual class device trees at
471 /sys/class/. The class and bus devices will be connected by
472 "<subsystem>:<name>" and the "device" links. The "block"
473 class devices, will not show up in /sys/class/block/. Some
474 subsystems will suppress the creation of some devices which
475 depend on the unified device tree.
477 This option is not a pure compatibility option that can
478 be safely enabled on newer distributions. It will change the
479 layout of sysfs to the non-extensible deprecated version,
480 and disable some features, which can not be exported without
481 confusing older userspace tools. Since 2007/2008 all major
482 distributions do not enable this option, and ship no tools which
483 depend on the deprecated layout or this option.
485 If you are using a new kernel on an older distribution, or use
486 older userspace tools, you might need to say Y here. Do not say Y,
487 if the original kernel, that came with your distribution, has
488 this option set to N.
491 bool "Kernel->user space relay support (formerly relayfs)"
493 This option enables support for relay interface support in
494 certain file systems (such as debugfs).
495 It is designed to provide an efficient mechanism for tools and
496 facilities to relay large amounts of data from kernel space to
502 bool "Namespaces support" if EMBEDDED
505 Provides the way to make tasks work with different objects using
506 the same id. For example same IPC id may refer to different objects
507 or same user id or pid may refer to different tasks when used in
508 different namespaces.
512 depends on NAMESPACES
514 In this namespace tasks see different info provided with the
519 depends on NAMESPACES && SYSVIPC
521 In this namespace tasks work with IPC ids which correspond to
522 different IPC objects in different namespaces
525 bool "User namespace (EXPERIMENTAL)"
526 depends on NAMESPACES && EXPERIMENTAL
528 This allows containers, i.e. vservers, to use user namespaces
529 to provide different user info for different servers.
533 bool "PID Namespaces (EXPERIMENTAL)"
535 depends on NAMESPACES && EXPERIMENTAL
537 Support process id namespaces. This allows having multiple
538 process with the same pid as long as they are in different
539 pid namespaces. This is a building block of containers.
541 Unless you want to work with an experimental feature
544 config BLK_DEV_INITRD
545 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
546 depends on BROKEN || !FRV
548 The initial RAM filesystem is a ramfs which is loaded by the
549 boot loader (loadlin or lilo) and that is mounted as root
550 before the normal boot procedure. It is typically used to
551 load modules needed to mount the "real" root file system,
552 etc. See <file:Documentation/initrd.txt> for details.
554 If RAM disk support (BLK_DEV_RAM) is also included, this
555 also enables initial RAM disk (initrd) support and adds
556 15 Kbytes (more on some other architectures) to the kernel size.
566 config CC_OPTIMIZE_FOR_SIZE
567 bool "Optimize for size"
570 Enabling this option will pass "-Os" instead of "-O2" to gcc
571 resulting in a smaller kernel.
579 bool "Configure standard kernel features (for small systems)"
581 This option allows certain base kernel options and settings
582 to be disabled or tweaked. This is for specialized
583 environments which can tolerate a "non-standard" kernel.
584 Only use this if you really know what you are doing.
587 bool "Enable 16-bit UID system calls" if EMBEDDED
588 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
591 This enables the legacy 16-bit UID syscall wrappers.
593 config SYSCTL_SYSCALL
594 bool "Sysctl syscall support" if EMBEDDED
598 sys_sysctl uses binary paths that have been found challenging
599 to properly maintain and use. The interface in /proc/sys
600 using paths with ascii names is now the primary path to this
603 Almost nothing using the binary sysctl interface so if you are
604 trying to save some space it is probably safe to disable this,
605 making your kernel marginally smaller.
607 If unsure say Y here.
610 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
613 Say Y here to let the kernel print out symbolic crash information and
614 symbolic stack backtraces. This increases the size of the kernel
615 somewhat, as all symbols have to be loaded into the kernel image.
618 bool "Include all symbols in kallsyms"
619 depends on DEBUG_KERNEL && KALLSYMS
621 Normally kallsyms only contains the symbols of functions, for nicer
622 OOPS messages. Some debuggers can use kallsyms for other
623 symbols too: say Y here to include all symbols, if you need them
624 and you don't care about adding 300k to the size of your kernel.
628 config KALLSYMS_STRIP_GENERATED
629 bool "Strip machine generated symbols from kallsyms"
630 depends on KALLSYMS_ALL
633 Say N if you want kallsyms to retain even machine generated symbols.
635 config KALLSYMS_EXTRA_PASS
636 bool "Do an extra kallsyms pass"
639 If kallsyms is not working correctly, the build will fail with
640 inconsistent kallsyms data. If that occurs, log a bug report and
641 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
642 Always say N here unless you find a bug in kallsyms, which must be
643 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
644 you wait for kallsyms to be fixed.
648 bool "Support for hot-pluggable devices" if EMBEDDED
651 This option is provided for the case where no hotplug or uevent
652 capabilities is wanted by the kernel. You should only consider
653 disabling this option for embedded systems that do not use modules, a
654 dynamic /dev tree, or dynamic device discovery. Just say Y.
658 bool "Enable support for printk" if EMBEDDED
660 This option enables normal printk support. Removing it
661 eliminates most of the message strings from the kernel image
662 and makes the kernel more or less silent. As this makes it
663 very difficult to diagnose system problems, saying N here is
664 strongly discouraged.
667 bool "BUG() support" if EMBEDDED
670 Disabling this option eliminates support for BUG and WARN, reducing
671 the size of your kernel image and potentially quietly ignoring
672 numerous fatal conditions. You should only consider disabling this
673 option for embedded systems with no facilities for reporting errors.
678 bool "Enable ELF core dumps" if EMBEDDED
680 Enable support for generating core dumps. Disabling saves about 4k.
682 config PCSPKR_PLATFORM
683 bool "Enable PC-Speaker support" if EMBEDDED
684 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
687 This option allows to disable the internal PC-Speaker
688 support, saving some memory.
691 bool "Disable heap randomization"
694 Randomizing heap placement makes heap exploits harder, but it
695 also breaks ancient binaries (including anything libc5 based).
696 This option changes the bootup default to heap randomization
697 disabled, and can be overriden runtime by setting
698 /proc/sys/kernel/randomize_va_space to 2.
700 On non-ancient distros (post-2000 ones) N is usually a safe choice.
704 bool "Enable full-sized data structures for core" if EMBEDDED
706 Disabling this option reduces the size of miscellaneous core
707 kernel data structures. This saves memory on small machines,
708 but may reduce performance.
711 bool "Enable futex support" if EMBEDDED
715 Disabling this option will cause the kernel to be built without
716 support for "fast userspace mutexes". The resulting kernel may not
717 run glibc-based applications correctly.
723 bool "Enable eventpoll support" if EMBEDDED
727 Disabling this option will cause the kernel to be built without
728 support for epoll family of system calls.
731 bool "Enable signalfd() system call" if EMBEDDED
735 Enable the signalfd() system call that allows to receive signals
736 on a file descriptor.
741 bool "Enable timerfd() system call" if EMBEDDED
745 Enable the timerfd() system call that allows to receive timer
746 events on a file descriptor.
751 bool "Enable eventfd() system call" if EMBEDDED
755 Enable the eventfd() system call that allows to receive both
756 kernel notification (ie. KAIO) or userspace notifications.
761 bool "Use full shmem filesystem" if EMBEDDED
765 The shmem is an internal filesystem used to manage shared memory.
766 It is backed by swap and manages resource limits. It is also exported
767 to userspace as tmpfs if TMPFS is enabled. Disabling this
768 option replaces shmem and tmpfs with the much simpler ramfs code,
769 which may be appropriate on small systems without swap.
772 bool "Enable AIO support" if EMBEDDED
775 This option enables POSIX asynchronous I/O which may by used
776 by some high performance threaded applications. Disabling
777 this option saves about 7k.
779 config VM_EVENT_COUNTERS
781 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
783 VM event counters are needed for event counts to be shown.
784 This option allows the disabling of the VM event counters
785 on EMBEDDED systems. /proc/vmstat will only show page counts
786 if VM event counters are disabled.
790 bool "Enable PCI quirk workarounds" if EMBEDDED
793 This enables workarounds for various PCI chipset
794 bugs/quirks. Disable this only if your target machine is
795 unaffected by PCI quirks.
799 bool "Enable SLUB debugging support" if EMBEDDED
800 depends on SLUB && SYSFS
802 SLUB has extensive debug support features. Disabling these can
803 result in significant savings in code size. This also disables
804 SLUB sysfs support. /sys/slab will not exist and there will be
805 no support for cache validation etc.
808 prompt "Choose SLAB allocator"
811 This option allows to select a slab allocator.
816 The regular slab allocator that is established and known to work
817 well in all environments. It organizes cache hot objects in
818 per cpu and per node queues.
821 bool "SLUB (Unqueued Allocator)"
823 SLUB is a slab allocator that minimizes cache line usage
824 instead of managing queues of cached objects (SLAB approach).
825 Per cpu caching is realized using slabs of objects instead
826 of queues of objects. SLUB can use memory efficiently
827 and has enhanced diagnostics. SLUB is the default choice for
832 bool "SLOB (Simple Allocator)"
834 SLOB replaces the stock allocator with a drastically simpler
835 allocator. SLOB is generally more space efficient but
836 does not perform as well on large systems.
841 bool "Profiling support (EXPERIMENTAL)"
843 Say Y here to enable the extended profiling support mechanisms used
844 by profilers such as OProfile.
847 # Place an empty function call at each tracepoint site. Can be
848 # dynamically changed for a probe function.
854 bool "Activate markers"
855 depends on TRACEPOINTS
857 Place an empty function call at each marker site. Can be
858 dynamically changed for a probe function.
860 source "arch/Kconfig"
862 endmenu # General setup
864 config HAVE_GENERIC_DMA_COHERENT
871 depends on SLAB || SLUB_DEBUG
880 default 0 if BASE_FULL
881 default 1 if !BASE_FULL
884 bool "Enable loadable module support"
886 Kernel modules are small pieces of compiled code which can
887 be inserted in the running kernel, rather than being
888 permanently built into the kernel. You use the "modprobe"
889 tool to add (and sometimes remove) them. If you say Y here,
890 many parts of the kernel can be built as modules (by
891 answering M instead of Y where indicated): this is most
892 useful for infrequently used options which are not required
893 for booting. For more information, see the man pages for
894 modprobe, lsmod, modinfo, insmod and rmmod.
896 If you say Y here, you will need to run "make
897 modules_install" to put the modules under /lib/modules/
898 where modprobe can find them (you may need to be root to do
905 config MODULE_FORCE_LOAD
906 bool "Forced module loading"
909 Allow loading of modules without version information (ie. modprobe
910 --force). Forced module loading sets the 'F' (forced) taint flag and
911 is usually a really bad idea.
914 bool "Module unloading"
916 Without this option you will not be able to unload any
917 modules (note that some modules may not be unloadable
918 anyway), which makes your kernel smaller, faster
919 and simpler. If unsure, say Y.
921 config MODULE_FORCE_UNLOAD
922 bool "Forced module unloading"
923 depends on MODULE_UNLOAD && EXPERIMENTAL
925 This option allows you to force a module to unload, even if the
926 kernel believes it is unsafe: the kernel will remove the module
927 without waiting for anyone to stop using it (using the -f option to
928 rmmod). This is mainly for kernel developers and desperate users.
932 bool "Module versioning support"
934 Usually, you have to use modules compiled with your kernel.
935 Saying Y here makes it sometimes possible to use modules
936 compiled for different kernels, by adding enough information
937 to the modules to (hopefully) spot any changes which would
938 make them incompatible with the kernel you are running. If
941 config MODULE_SRCVERSION_ALL
942 bool "Source checksum for all modules"
944 Modules which contain a MODULE_VERSION get an extra "srcversion"
945 field inserted into their modinfo section, which contains a
946 sum of the source files which made it. This helps maintainers
947 see exactly which source was used to build a module (since
948 others sometimes change the module source without updating
949 the version). With this option, such a "srcversion" field
950 will be created for all modules. If unsure, say N.
954 config INIT_ALL_POSSIBLE
957 Back when each arch used to define their own cpu_online_map and
958 cpu_possible_map, some of them chose to initialize cpu_possible_map
959 with all 1s, and others with all 0s. When they were centralised,
960 it was better to provide this option than to break all the archs
961 and have several arch maintainers persuing me down dark alleys.
966 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
968 Need stop_machine() primitive.
970 source "block/Kconfig"
972 config PREEMPT_NOTIFIERS
976 prompt "RCU Implementation"
982 This option selects the classic RCU implementation that is
983 designed for best read-side performance on non-realtime
986 Select this option if you are unsure.
989 bool "Tree-based hierarchical RCU"
991 This option selects the RCU implementation that is
992 designed for very large SMP system with hundreds or
996 bool "Preemptible RCU"
999 This option reduces the latency of the kernel by making certain
1000 RCU sections preemptible. Normally RCU code is non-preemptible, if
1001 this option is selected then read-only RCU sections become
1002 preemptible. This helps latency, but may expose bugs due to
1003 now-naive assumptions about each RCU read-side critical section
1004 remaining on a given CPU through its execution.
1009 bool "Enable tracing for RCU"
1010 depends on TREE_RCU || PREEMPT_RCU
1012 This option provides tracing in RCU which presents stats
1013 in debugfs for debugging RCU implementation.
1015 Say Y here if you want to enable RCU tracing
1016 Say N if you are unsure.
1019 int "Tree-based hierarchical RCU fanout value"
1021 range 2 32 if !64BIT
1024 default 32 if !64BIT
1026 This option controls the fanout of hierarchical implementations
1027 of RCU, allowing RCU to work efficiently on machines with
1028 large numbers of CPUs. This value must be at least the cube
1029 root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
1030 systems and up to 262,144 for 64-bit systems.
1032 Select a specific number if testing RCU itself.
1033 Take the default if unsure.
1035 config RCU_FANOUT_EXACT
1036 bool "Disable tree-based hierarchical RCU auto-balancing"
1040 This option forces use of the exact RCU_FANOUT value specified,
1041 regardless of imbalances in the hierarchy. This is useful for
1042 testing RCU itself, and might one day be useful on systems with
1043 strong NUMA behavior.
1045 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
1049 config TREE_RCU_TRACE
1050 def_bool RCU_TRACE && TREE_RCU
1053 This option provides tracing for the TREE_RCU implementation,
1054 permitting Makefile to trivially select kernel/rcutree_trace.c.
1056 config PREEMPT_RCU_TRACE
1057 def_bool RCU_TRACE && PREEMPT_RCU
1060 This option provides tracing for the PREEMPT_RCU implementation,
1061 permitting Makefile to trivially select kernel/rcupreempt_trace.c.
git://ftp.safe.ca / safe / jmp / linux-2.6 / blob