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"
28 depends on HAVE_IRQ_WORK
30 config BUILDTIME_EXTABLE_SORT
36 bool "Prompt for development and/or incomplete code/drivers"
38 Some of the various things that Linux supports (such as network
39 drivers, file systems, network protocols, etc.) can be in a state
40 of development where the functionality, stability, or the level of
41 testing is not yet high enough for general use. This is usually
42 known as the "alpha-test" phase among developers. If a feature is
43 currently in alpha-test, then the developers usually discourage
44 uninformed widespread use of this feature by the general public to
45 avoid "Why doesn't this work?" type mail messages. However, active
46 testing and use of these systems is welcomed. Just be aware that it
47 may not meet the normal level of reliability or it may fail to work
48 in some special cases. Detailed bug reports from people familiar
49 with the kernel internals are usually welcomed by the developers
50 (before submitting bug reports, please read the documents
51 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
52 <file:Documentation/BUG-HUNTING>, and
53 <file:Documentation/oops-tracing.txt> in the kernel source).
55 This option will also make obsoleted drivers available. These are
56 drivers that have been replaced by something else, and/or are
57 scheduled to be removed in a future kernel release.
59 Unless you intend to help test and develop a feature or driver that
60 falls into this category, or you have a situation that requires
61 using these features, you should probably say N here, which will
62 cause the configurator to present you with fewer choices. If
63 you say Y here, you will be offered the choice of using features or
64 drivers that are currently considered to be in the alpha-test phase.
71 depends on BROKEN || !SMP
74 config INIT_ENV_ARG_LIMIT
79 Maximum of each of the number of arguments and environment
80 variables passed to init from the kernel command line.
84 string "Cross-compiler tool prefix"
86 Same as running 'make CROSS_COMPILE=prefix-' but stored for
87 default make runs in this kernel build directory. You don't
88 need to set this unless you want the configured kernel build
89 directory to select the cross-compiler automatically.
92 string "Local version - append to kernel release"
94 Append an extra string to the end of your kernel version.
95 This will show up when you type uname, for example.
96 The string you set here will be appended after the contents of
97 any files with a filename matching localversion* in your
98 object and source tree, in that order. Your total string can
99 be a maximum of 64 characters.
101 config LOCALVERSION_AUTO
102 bool "Automatically append version information to the version string"
105 This will try to automatically determine if the current tree is a
106 release tree by looking for git tags that belong to the current
107 top of tree revision.
109 A string of the format -gxxxxxxxx will be added to the localversion
110 if a git-based tree is found. The string generated by this will be
111 appended after any matching localversion* files, and after the value
112 set in CONFIG_LOCALVERSION.
114 (The actual string used here is the first eight characters produced
115 by running the command:
117 $ git rev-parse --verify HEAD
119 which is done within the script "scripts/setlocalversion".)
121 config HAVE_KERNEL_GZIP
124 config HAVE_KERNEL_BZIP2
127 config HAVE_KERNEL_LZMA
130 config HAVE_KERNEL_XZ
133 config HAVE_KERNEL_LZO
137 prompt "Kernel compression mode"
139 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
141 The linux kernel is a kind of self-extracting executable.
142 Several compression algorithms are available, which differ
143 in efficiency, compression and decompression speed.
144 Compression speed is only relevant when building a kernel.
145 Decompression speed is relevant at each boot.
147 If you have any problems with bzip2 or lzma compressed
148 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
149 version of this functionality (bzip2 only), for 2.4, was
150 supplied by Christian Ludwig)
152 High compression options are mostly useful for users, who
153 are low on disk space (embedded systems), but for whom ram
156 If in doubt, select 'gzip'
160 depends on HAVE_KERNEL_GZIP
162 The old and tried gzip compression. It provides a good balance
163 between compression ratio and decompression speed.
167 depends on HAVE_KERNEL_BZIP2
169 Its compression ratio and speed is intermediate.
170 Decompression speed is slowest among the choices. The kernel
171 size is about 10% smaller with bzip2, in comparison to gzip.
172 Bzip2 uses a large amount of memory. For modern kernels you
173 will need at least 8MB RAM or more for booting.
177 depends on HAVE_KERNEL_LZMA
179 This compression algorithm's ratio is best. Decompression speed
180 is between gzip and bzip2. Compression is slowest.
181 The kernel size is about 33% smaller with LZMA in comparison to gzip.
185 depends on HAVE_KERNEL_XZ
187 XZ uses the LZMA2 algorithm and instruction set specific
188 BCJ filters which can improve compression ratio of executable
189 code. The size of the kernel is about 30% smaller with XZ in
190 comparison to gzip. On architectures for which there is a BCJ
191 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
192 will create a few percent smaller kernel than plain LZMA.
194 The speed is about the same as with LZMA: The decompression
195 speed of XZ is better than that of bzip2 but worse than gzip
196 and LZO. Compression is slow.
200 depends on HAVE_KERNEL_LZO
202 Its compression ratio is the poorest among the choices. The kernel
203 size is about 10% bigger than gzip; however its speed
204 (both compression and decompression) is the fastest.
208 config DEFAULT_HOSTNAME
209 string "Default hostname"
212 This option determines the default system hostname before userspace
213 calls sethostname(2). The kernel traditionally uses "(none)" here,
214 but you may wish to use a different default here to make a minimal
215 system more usable with less configuration.
218 bool "Support for paging of anonymous memory (swap)"
219 depends on MMU && BLOCK
222 This option allows you to choose whether you want to have support
223 for so called swap devices or swap files in your kernel that are
224 used to provide more virtual memory than the actual RAM present
225 in your computer. If unsure say Y.
230 Inter Process Communication is a suite of library functions and
231 system calls which let processes (running programs) synchronize and
232 exchange information. It is generally considered to be a good thing,
233 and some programs won't run unless you say Y here. In particular, if
234 you want to run the DOS emulator dosemu under Linux (read the
235 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
236 you'll need to say Y here.
238 You can find documentation about IPC with "info ipc" and also in
239 section 6.4 of the Linux Programmer's Guide, available from
240 <http://www.tldp.org/guides.html>.
242 config SYSVIPC_SYSCTL
249 bool "POSIX Message Queues"
250 depends on NET && EXPERIMENTAL
252 POSIX variant of message queues is a part of IPC. In POSIX message
253 queues every message has a priority which decides about succession
254 of receiving it by a process. If you want to compile and run
255 programs written e.g. for Solaris with use of its POSIX message
256 queues (functions mq_*) say Y here.
258 POSIX message queues are visible as a filesystem called 'mqueue'
259 and can be mounted somewhere if you want to do filesystem
260 operations on message queues.
264 config POSIX_MQUEUE_SYSCTL
266 depends on POSIX_MQUEUE
270 config BSD_PROCESS_ACCT
271 bool "BSD Process Accounting"
273 If you say Y here, a user level program will be able to instruct the
274 kernel (via a special system call) to write process accounting
275 information to a file: whenever a process exits, information about
276 that process will be appended to the file by the kernel. The
277 information includes things such as creation time, owning user,
278 command name, memory usage, controlling terminal etc. (the complete
279 list is in the struct acct in <file:include/linux/acct.h>). It is
280 up to the user level program to do useful things with this
281 information. This is generally a good idea, so say Y.
283 config BSD_PROCESS_ACCT_V3
284 bool "BSD Process Accounting version 3 file format"
285 depends on BSD_PROCESS_ACCT
288 If you say Y here, the process accounting information is written
289 in a new file format that also logs the process IDs of each
290 process and it's parent. Note that this file format is incompatible
291 with previous v0/v1/v2 file formats, so you will need updated tools
292 for processing it. A preliminary version of these tools is available
293 at <http://www.gnu.org/software/acct/>.
296 bool "open by fhandle syscalls"
299 If you say Y here, a user level program will be able to map
300 file names to handle and then later use the handle for
301 different file system operations. This is useful in implementing
302 userspace file servers, which now track files using handles instead
303 of names. The handle would remain the same even if file names
304 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
308 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
312 Export selected statistics for tasks/processes through the
313 generic netlink interface. Unlike BSD process accounting, the
314 statistics are available during the lifetime of tasks/processes as
315 responses to commands. Like BSD accounting, they are sent to user
320 config TASK_DELAY_ACCT
321 bool "Enable per-task delay accounting (EXPERIMENTAL)"
324 Collect information on time spent by a task waiting for system
325 resources like cpu, synchronous block I/O completion and swapping
326 in pages. Such statistics can help in setting a task's priorities
327 relative to other tasks for cpu, io, rss limits etc.
332 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
335 Collect extended task accounting data and send the data
336 to userland for processing over the taskstats interface.
340 config TASK_IO_ACCOUNTING
341 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
342 depends on TASK_XACCT
344 Collect information on the number of bytes of storage I/O which this
350 bool "Auditing support"
353 Enable auditing infrastructure that can be used with another
354 kernel subsystem, such as SELinux (which requires this for
355 logging of avc messages output). Does not do system-call
356 auditing without CONFIG_AUDITSYSCALL.
359 bool "Enable system-call auditing support"
360 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || (ARM && AEABI && !OABI_COMPAT))
361 default y if SECURITY_SELINUX
363 Enable low-overhead system-call auditing infrastructure that
364 can be used independently or with another kernel subsystem,
369 depends on AUDITSYSCALL
374 depends on AUDITSYSCALL
377 config AUDIT_LOGINUID_IMMUTABLE
378 bool "Make audit loginuid immutable"
381 The config option toggles if a task setting its loginuid requires
382 CAP_SYS_AUDITCONTROL or if that task should require no special permissions
383 but should instead only allow setting its loginuid if it was never
384 previously set. On systems which use systemd or a similar central
385 process to restart login services this should be set to true. On older
386 systems in which an admin would typically have to directly stop and
387 start processes this should be set to false. Setting this to true allows
388 one to drop potentially dangerous capabilites from the login tasks,
389 but may not be backwards compatible with older init systems.
391 source "kernel/irq/Kconfig"
392 source "kernel/time/Kconfig"
397 prompt "RCU Implementation"
401 bool "Tree-based hierarchical RCU"
402 depends on !PREEMPT && SMP
404 This option selects the RCU implementation that is
405 designed for very large SMP system with hundreds or
406 thousands of CPUs. It also scales down nicely to
409 config TREE_PREEMPT_RCU
410 bool "Preemptible tree-based hierarchical RCU"
411 depends on PREEMPT && SMP
413 This option selects the RCU implementation that is
414 designed for very large SMP systems with hundreds or
415 thousands of CPUs, but for which real-time response
416 is also required. It also scales down nicely to
420 bool "UP-only small-memory-footprint RCU"
421 depends on !PREEMPT && !SMP
423 This option selects the RCU implementation that is
424 designed for UP systems from which real-time response
425 is not required. This option greatly reduces the
426 memory footprint of RCU.
428 config TINY_PREEMPT_RCU
429 bool "Preemptible UP-only small-memory-footprint RCU"
430 depends on PREEMPT && !SMP
432 This option selects the RCU implementation that is designed
433 for real-time UP systems. This option greatly reduces the
434 memory footprint of RCU.
439 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
441 This option enables preemptible-RCU code that is common between
442 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
445 bool "Consider userspace as in RCU extended quiescent state"
446 depends on HAVE_RCU_USER_QS && SMP
448 This option sets hooks on kernel / userspace boundaries and
449 puts RCU in extended quiescent state when the CPU runs in
450 userspace. It means that when a CPU runs in userspace, it is
451 excluded from the global RCU state machine and thus doesn't
452 to keep the timer tick on for RCU.
454 Unless you want to hack and help the development of the full
455 tickless feature, you shouldn't enable this option. It adds
456 unnecessary overhead.
460 config RCU_USER_QS_FORCE
461 bool "Force userspace extended QS by default"
462 depends on RCU_USER_QS
464 Set the hooks in user/kernel boundaries by default in order to
465 test this feature that treats userspace as an extended quiescent
466 state until we have a real user like a full adaptive nohz option.
468 Unless you want to hack and help the development of the full
469 tickless feature, you shouldn't enable this option. It adds
470 unnecessary overhead.
475 int "Tree-based hierarchical RCU fanout value"
478 depends on TREE_RCU || TREE_PREEMPT_RCU
482 This option controls the fanout of hierarchical implementations
483 of RCU, allowing RCU to work efficiently on machines with
484 large numbers of CPUs. This value must be at least the fourth
485 root of NR_CPUS, which allows NR_CPUS to be insanely large.
486 The default value of RCU_FANOUT should be used for production
487 systems, but if you are stress-testing the RCU implementation
488 itself, small RCU_FANOUT values allow you to test large-system
489 code paths on small(er) systems.
491 Select a specific number if testing RCU itself.
492 Take the default if unsure.
494 config RCU_FANOUT_LEAF
495 int "Tree-based hierarchical RCU leaf-level fanout value"
496 range 2 RCU_FANOUT if 64BIT
497 range 2 RCU_FANOUT if !64BIT
498 depends on TREE_RCU || TREE_PREEMPT_RCU
501 This option controls the leaf-level fanout of hierarchical
502 implementations of RCU, and allows trading off cache misses
503 against lock contention. Systems that synchronize their
504 scheduling-clock interrupts for energy-efficiency reasons will
505 want the default because the smaller leaf-level fanout keeps
506 lock contention levels acceptably low. Very large systems
507 (hundreds or thousands of CPUs) will instead want to set this
508 value to the maximum value possible in order to reduce the
509 number of cache misses incurred during RCU's grace-period
510 initialization. These systems tend to run CPU-bound, and thus
511 are not helped by synchronized interrupts, and thus tend to
512 skew them, which reduces lock contention enough that large
513 leaf-level fanouts work well.
515 Select a specific number if testing RCU itself.
517 Select the maximum permissible value for large systems.
519 Take the default if unsure.
521 config RCU_FANOUT_EXACT
522 bool "Disable tree-based hierarchical RCU auto-balancing"
523 depends on TREE_RCU || TREE_PREEMPT_RCU
526 This option forces use of the exact RCU_FANOUT value specified,
527 regardless of imbalances in the hierarchy. This is useful for
528 testing RCU itself, and might one day be useful on systems with
529 strong NUMA behavior.
531 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
535 config RCU_FAST_NO_HZ
536 bool "Accelerate last non-dyntick-idle CPU's grace periods"
537 depends on NO_HZ && SMP
540 This option causes RCU to attempt to accelerate grace periods
541 in order to allow CPUs to enter dynticks-idle state more
542 quickly. On the other hand, this option increases the overhead
543 of the dynticks-idle checking, particularly on systems with
544 large numbers of CPUs.
546 Say Y if energy efficiency is critically important, particularly
547 if you have relatively few CPUs.
549 Say N if you are unsure.
551 config TREE_RCU_TRACE
552 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
555 This option provides tracing for the TREE_RCU and
556 TREE_PREEMPT_RCU implementations, permitting Makefile to
557 trivially select kernel/rcutree_trace.c.
560 bool "Enable RCU priority boosting"
561 depends on RT_MUTEXES && PREEMPT_RCU
564 This option boosts the priority of preempted RCU readers that
565 block the current preemptible RCU grace period for too long.
566 This option also prevents heavy loads from blocking RCU
567 callback invocation for all flavors of RCU.
569 Say Y here if you are working with real-time apps or heavy loads
570 Say N here if you are unsure.
572 config RCU_BOOST_PRIO
573 int "Real-time priority to boost RCU readers to"
578 This option specifies the real-time priority to which long-term
579 preempted RCU readers are to be boosted. If you are working
580 with a real-time application that has one or more CPU-bound
581 threads running at a real-time priority level, you should set
582 RCU_BOOST_PRIO to a priority higher then the highest-priority
583 real-time CPU-bound thread. The default RCU_BOOST_PRIO value
584 of 1 is appropriate in the common case, which is real-time
585 applications that do not have any CPU-bound threads.
587 Some real-time applications might not have a single real-time
588 thread that saturates a given CPU, but instead might have
589 multiple real-time threads that, taken together, fully utilize
590 that CPU. In this case, you should set RCU_BOOST_PRIO to
591 a priority higher than the lowest-priority thread that is
592 conspiring to prevent the CPU from running any non-real-time
593 tasks. For example, if one thread at priority 10 and another
594 thread at priority 5 are between themselves fully consuming
595 the CPU time on a given CPU, then RCU_BOOST_PRIO should be
596 set to priority 6 or higher.
598 Specify the real-time priority, or take the default if unsure.
600 config RCU_BOOST_DELAY
601 int "Milliseconds to delay boosting after RCU grace-period start"
606 This option specifies the time to wait after the beginning of
607 a given grace period before priority-boosting preempted RCU
608 readers blocking that grace period. Note that any RCU reader
609 blocking an expedited RCU grace period is boosted immediately.
611 Accept the default if unsure.
613 endmenu # "RCU Subsystem"
616 tristate "Kernel .config support"
618 This option enables the complete Linux kernel ".config" file
619 contents to be saved in the kernel. It provides documentation
620 of which kernel options are used in a running kernel or in an
621 on-disk kernel. This information can be extracted from the kernel
622 image file with the script scripts/extract-ikconfig and used as
623 input to rebuild the current kernel or to build another kernel.
624 It can also be extracted from a running kernel by reading
625 /proc/config.gz if enabled (below).
628 bool "Enable access to .config through /proc/config.gz"
629 depends on IKCONFIG && PROC_FS
631 This option enables access to the kernel configuration file
632 through /proc/config.gz.
635 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
639 Select kernel log buffer size as a power of 2.
649 # Architectures with an unreliable sched_clock() should select this:
651 config HAVE_UNSTABLE_SCHED_CLOCK
655 boolean "Control Group support"
658 This option adds support for grouping sets of processes together, for
659 use with process control subsystems such as Cpusets, CFS, memory
660 controls or device isolation.
662 - Documentation/scheduler/sched-design-CFS.txt (CFS)
663 - Documentation/cgroups/ (features for grouping, isolation
664 and resource control)
671 bool "Example debug cgroup subsystem"
674 This option enables a simple cgroup subsystem that
675 exports useful debugging information about the cgroups
680 config CGROUP_FREEZER
681 bool "Freezer cgroup subsystem"
683 Provides a way to freeze and unfreeze all tasks in a
687 bool "Device controller for cgroups"
689 Provides a cgroup implementing whitelists for devices which
690 a process in the cgroup can mknod or open.
693 bool "Cpuset support"
695 This option will let you create and manage CPUSETs which
696 allow dynamically partitioning a system into sets of CPUs and
697 Memory Nodes and assigning tasks to run only within those sets.
698 This is primarily useful on large SMP or NUMA systems.
702 config PROC_PID_CPUSET
703 bool "Include legacy /proc/<pid>/cpuset file"
707 config CGROUP_CPUACCT
708 bool "Simple CPU accounting cgroup subsystem"
710 Provides a simple Resource Controller for monitoring the
711 total CPU consumed by the tasks in a cgroup.
713 config RESOURCE_COUNTERS
714 bool "Resource counters"
716 This option enables controller independent resource accounting
717 infrastructure that works with cgroups.
720 bool "Memory Resource Controller for Control Groups"
721 depends on RESOURCE_COUNTERS
724 Provides a memory resource controller that manages both anonymous
725 memory and page cache. (See Documentation/cgroups/memory.txt)
727 Note that setting this option increases fixed memory overhead
728 associated with each page of memory in the system. By this,
729 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
730 usage tracking struct at boot. Total amount of this is printed out
733 Only enable when you're ok with these trade offs and really
734 sure you need the memory resource controller. Even when you enable
735 this, you can set "cgroup_disable=memory" at your boot option to
736 disable memory resource controller and you can avoid overheads.
737 (and lose benefits of memory resource controller)
739 This config option also selects MM_OWNER config option, which
740 could in turn add some fork/exit overhead.
743 bool "Memory Resource Controller Swap Extension"
744 depends on MEMCG && SWAP
746 Add swap management feature to memory resource controller. When you
747 enable this, you can limit mem+swap usage per cgroup. In other words,
748 when you disable this, memory resource controller has no cares to
749 usage of swap...a process can exhaust all of the swap. This extension
750 is useful when you want to avoid exhaustion swap but this itself
751 adds more overheads and consumes memory for remembering information.
752 Especially if you use 32bit system or small memory system, please
753 be careful about enabling this. When memory resource controller
754 is disabled by boot option, this will be automatically disabled and
755 there will be no overhead from this. Even when you set this config=y,
756 if boot option "swapaccount=0" is set, swap will not be accounted.
757 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
758 size is 4096bytes, 512k per 1Gbytes of swap.
759 config MEMCG_SWAP_ENABLED
760 bool "Memory Resource Controller Swap Extension enabled by default"
761 depends on MEMCG_SWAP
764 Memory Resource Controller Swap Extension comes with its price in
765 a bigger memory consumption. General purpose distribution kernels
766 which want to enable the feature but keep it disabled by default
767 and let the user enable it by swapaccount boot command line
768 parameter should have this option unselected.
769 For those who want to have the feature enabled by default should
770 select this option (if, for some reason, they need to disable it
771 then swapaccount=0 does the trick).
773 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
774 depends on MEMCG && EXPERIMENTAL
777 The Kernel Memory extension for Memory Resource Controller can limit
778 the amount of memory used by kernel objects in the system. Those are
779 fundamentally different from the entities handled by the standard
780 Memory Controller, which are page-based, and can be swapped. Users of
781 the kmem extension can use it to guarantee that no group of processes
782 will ever exhaust kernel resources alone.
784 config CGROUP_HUGETLB
785 bool "HugeTLB Resource Controller for Control Groups"
786 depends on RESOURCE_COUNTERS && HUGETLB_PAGE && EXPERIMENTAL
789 Provides a cgroup Resource Controller for HugeTLB pages.
790 When you enable this, you can put a per cgroup limit on HugeTLB usage.
791 The limit is enforced during page fault. Since HugeTLB doesn't
792 support page reclaim, enforcing the limit at page fault time implies
793 that, the application will get SIGBUS signal if it tries to access
794 HugeTLB pages beyond its limit. This requires the application to know
795 beforehand how much HugeTLB pages it would require for its use. The
796 control group is tracked in the third page lru pointer. This means
797 that we cannot use the controller with huge page less than 3 pages.
800 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
801 depends on PERF_EVENTS && CGROUPS
803 This option extends the per-cpu mode to restrict monitoring to
804 threads which belong to the cgroup specified and run on the
809 menuconfig CGROUP_SCHED
810 bool "Group CPU scheduler"
813 This feature lets CPU scheduler recognize task groups and control CPU
814 bandwidth allocation to such task groups. It uses cgroups to group
818 config FAIR_GROUP_SCHED
819 bool "Group scheduling for SCHED_OTHER"
820 depends on CGROUP_SCHED
824 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
825 depends on EXPERIMENTAL
826 depends on FAIR_GROUP_SCHED
829 This option allows users to define CPU bandwidth rates (limits) for
830 tasks running within the fair group scheduler. Groups with no limit
831 set are considered to be unconstrained and will run with no
833 See tip/Documentation/scheduler/sched-bwc.txt for more information.
835 config RT_GROUP_SCHED
836 bool "Group scheduling for SCHED_RR/FIFO"
837 depends on EXPERIMENTAL
838 depends on CGROUP_SCHED
841 This feature lets you explicitly allocate real CPU bandwidth
842 to task groups. If enabled, it will also make it impossible to
843 schedule realtime tasks for non-root users until you allocate
844 realtime bandwidth for them.
845 See Documentation/scheduler/sched-rt-group.txt for more information.
850 bool "Block IO controller"
854 Generic block IO controller cgroup interface. This is the common
855 cgroup interface which should be used by various IO controlling
858 Currently, CFQ IO scheduler uses it to recognize task groups and
859 control disk bandwidth allocation (proportional time slice allocation)
860 to such task groups. It is also used by bio throttling logic in
861 block layer to implement upper limit in IO rates on a device.
863 This option only enables generic Block IO controller infrastructure.
864 One needs to also enable actual IO controlling logic/policy. For
865 enabling proportional weight division of disk bandwidth in CFQ, set
866 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
867 CONFIG_BLK_DEV_THROTTLING=y.
869 See Documentation/cgroups/blkio-controller.txt for more information.
871 config DEBUG_BLK_CGROUP
872 bool "Enable Block IO controller debugging"
873 depends on BLK_CGROUP
876 Enable some debugging help. Currently it exports additional stat
877 files in a cgroup which can be useful for debugging.
881 config CHECKPOINT_RESTORE
882 bool "Checkpoint/restore support" if EXPERT
885 Enables additional kernel features in a sake of checkpoint/restore.
886 In particular it adds auxiliary prctl codes to setup process text,
887 data and heap segment sizes, and a few additional /proc filesystem
890 If unsure, say N here.
892 menuconfig NAMESPACES
893 bool "Namespaces support" if EXPERT
896 Provides the way to make tasks work with different objects using
897 the same id. For example same IPC id may refer to different objects
898 or same user id or pid may refer to different tasks when used in
899 different namespaces.
907 In this namespace tasks see different info provided with the
912 depends on (SYSVIPC || POSIX_MQUEUE)
915 In this namespace tasks work with IPC ids which correspond to
916 different IPC objects in different namespaces.
919 bool "User namespace (EXPERIMENTAL)"
920 depends on EXPERIMENTAL
921 depends on UIDGID_CONVERTED
922 select UIDGID_STRICT_TYPE_CHECKS
926 This allows containers, i.e. vservers, to use user namespaces
927 to provide different user info for different servers.
931 bool "PID Namespaces"
934 Support process id namespaces. This allows having multiple
935 processes with the same pid as long as they are in different
936 pid namespaces. This is a building block of containers.
939 bool "Network namespace"
943 Allow user space to create what appear to be multiple instances
944 of the network stack.
948 config UIDGID_CONVERTED
949 # True if all of the selected software conmponents are known
950 # to have uid_t and gid_t converted to kuid_t and kgid_t
951 # where appropriate and are otherwise safe to use with
952 # the user namespace.
956 # List of kernel pieces that need user namespace work
958 depends on SYSVIPC = n
963 depends on AUDITSYSCALL = n
964 depends on TASKSTATS = n
965 depends on TRACING = n
966 depends on FS_POSIX_ACL = n
968 depends on QUOTACTL = n
969 depends on DEBUG_CREDENTIALS = n
970 depends on BSD_PROCESS_ACCT = n
972 depends on PROC_EVENTS = n
976 depends on NET_9P = n
978 depends on PHONET = n
979 depends on NET_CLS_FLOW = n
980 depends on NETFILTER_XT_MATCH_OWNER = n
981 depends on NETFILTER_XT_MATCH_RECENT = n
982 depends on NETFILTER_XT_TARGET_LOG = n
983 depends on NETFILTER_NETLINK_LOG = n
986 depends on IP_SCTP = n
987 depends on AF_RXRPC = n
989 depends on NET_KEY = n
990 depends on INET_DIAG = n
991 depends on DNS_RESOLVER = n
996 depends on USB_DEVICEFS = n
997 depends on USB_GADGETFS = n
998 depends on USB_FUNCTIONFS = n
999 depends on DEVTMPFS = n
1000 depends on XENFS = n
1002 depends on 9P_FS = n
1003 depends on ADFS_FS = n
1004 depends on AFFS_FS = n
1005 depends on AFS_FS = n
1006 depends on AUTOFS4_FS = n
1007 depends on BEFS_FS = n
1008 depends on BFS_FS = n
1009 depends on BTRFS_FS = n
1010 depends on CEPH_FS = n
1012 depends on CODA_FS = n
1013 depends on CONFIGFS_FS = n
1014 depends on CRAMFS = n
1015 depends on DEBUG_FS = n
1016 depends on ECRYPT_FS = n
1017 depends on EFS_FS = n
1018 depends on EXOFS_FS = n
1019 depends on FAT_FS = n
1020 depends on FUSE_FS = n
1021 depends on GFS2_FS = n
1022 depends on HFS_FS = n
1023 depends on HFSPLUS_FS = n
1024 depends on HPFS_FS = n
1025 depends on HUGETLBFS = n
1026 depends on ISO9660_FS = n
1027 depends on JFFS2_FS = n
1028 depends on JFS_FS = n
1029 depends on LOGFS = n
1030 depends on MINIX_FS = n
1031 depends on NCP_FS = n
1033 depends on NFS_FS = n
1034 depends on NILFS2_FS = n
1035 depends on NTFS_FS = n
1036 depends on OCFS2_FS = n
1037 depends on OMFS_FS = n
1038 depends on QNX4FS_FS = n
1039 depends on QNX6FS_FS = n
1040 depends on REISERFS_FS = n
1041 depends on SQUASHFS = n
1042 depends on SYSV_FS = n
1043 depends on UBIFS_FS = n
1044 depends on UDF_FS = n
1045 depends on UFS_FS = n
1046 depends on VXFS_FS = n
1047 depends on XFS_FS = n
1049 depends on !UML || HOSTFS = n
1051 # The rare drivers that won't build
1053 depends on AIRO_CS = n
1055 depends on INFINIBAND_QIB = n
1056 depends on BLK_DEV_LOOP = n
1057 depends on ANDROID_BINDER_IPC = n
1060 depends on SECURITY_TOMOYO = n
1061 depends on SECURITY_APPARMOR = n
1063 config UIDGID_STRICT_TYPE_CHECKS
1064 bool "Require conversions between uid/gids and their internal representation"
1065 depends on UIDGID_CONVERTED
1068 While the nececessary conversions are being added to all subsystems this option allows
1069 the code to continue to build for unconverted subsystems.
1071 Say Y here if you want the strict type checking enabled
1073 config SCHED_AUTOGROUP
1074 bool "Automatic process group scheduling"
1078 select FAIR_GROUP_SCHED
1080 This option optimizes the scheduler for common desktop workloads by
1081 automatically creating and populating task groups. This separation
1082 of workloads isolates aggressive CPU burners (like build jobs) from
1083 desktop applications. Task group autogeneration is currently based
1089 config SYSFS_DEPRECATED
1090 bool "Enable deprecated sysfs features to support old userspace tools"
1094 This option adds code that switches the layout of the "block" class
1095 devices, to not show up in /sys/class/block/, but only in
1098 This switch is only active when the sysfs.deprecated=1 boot option is
1099 passed or the SYSFS_DEPRECATED_V2 option is set.
1101 This option allows new kernels to run on old distributions and tools,
1102 which might get confused by /sys/class/block/. Since 2007/2008 all
1103 major distributions and tools handle this just fine.
1105 Recent distributions and userspace tools after 2009/2010 depend on
1106 the existence of /sys/class/block/, and will not work with this
1109 Only if you are using a new kernel on an old distribution, you might
1112 config SYSFS_DEPRECATED_V2
1113 bool "Enable deprecated sysfs features by default"
1116 depends on SYSFS_DEPRECATED
1118 Enable deprecated sysfs by default.
1120 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1123 Only if you are using a new kernel on an old distribution, you might
1124 need to say Y here. Even then, odds are you would not need it
1125 enabled, you can always pass the boot option if absolutely necessary.
1128 bool "Kernel->user space relay support (formerly relayfs)"
1130 This option enables support for relay interface support in
1131 certain file systems (such as debugfs).
1132 It is designed to provide an efficient mechanism for tools and
1133 facilities to relay large amounts of data from kernel space to
1138 config BLK_DEV_INITRD
1139 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1140 depends on BROKEN || !FRV
1142 The initial RAM filesystem is a ramfs which is loaded by the
1143 boot loader (loadlin or lilo) and that is mounted as root
1144 before the normal boot procedure. It is typically used to
1145 load modules needed to mount the "real" root file system,
1146 etc. See <file:Documentation/initrd.txt> for details.
1148 If RAM disk support (BLK_DEV_RAM) is also included, this
1149 also enables initial RAM disk (initrd) support and adds
1150 15 Kbytes (more on some other architectures) to the kernel size.
1156 source "usr/Kconfig"
1160 config CC_OPTIMIZE_FOR_SIZE
1161 bool "Optimize for size"
1163 Enabling this option will pass "-Os" instead of "-O2" to gcc
1164 resulting in a smaller kernel.
1175 bool "Configure standard kernel features (expert users)"
1176 # Unhide debug options, to make the on-by-default options visible
1179 This option allows certain base kernel options and settings
1180 to be disabled or tweaked. This is for specialized
1181 environments which can tolerate a "non-standard" kernel.
1182 Only use this if you really know what you are doing.
1185 bool "Enable 16-bit UID system calls" if EXPERT
1186 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
1189 This enables the legacy 16-bit UID syscall wrappers.
1191 config SYSCTL_SYSCALL
1192 bool "Sysctl syscall support" if EXPERT
1193 depends on PROC_SYSCTL
1197 sys_sysctl uses binary paths that have been found challenging
1198 to properly maintain and use. The interface in /proc/sys
1199 using paths with ascii names is now the primary path to this
1202 Almost nothing using the binary sysctl interface so if you are
1203 trying to save some space it is probably safe to disable this,
1204 making your kernel marginally smaller.
1206 If unsure say N here.
1209 bool "Load all symbols for debugging/ksymoops" if EXPERT
1212 Say Y here to let the kernel print out symbolic crash information and
1213 symbolic stack backtraces. This increases the size of the kernel
1214 somewhat, as all symbols have to be loaded into the kernel image.
1217 bool "Include all symbols in kallsyms"
1218 depends on DEBUG_KERNEL && KALLSYMS
1220 Normally kallsyms only contains the symbols of functions for nicer
1221 OOPS messages and backtraces (i.e., symbols from the text and inittext
1222 sections). This is sufficient for most cases. And only in very rare
1223 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1224 names of variables from the data sections, etc).
1226 This option makes sure that all symbols are loaded into the kernel
1227 image (i.e., symbols from all sections) in cost of increased kernel
1228 size (depending on the kernel configuration, it may be 300KiB or
1229 something like this).
1231 Say N unless you really need all symbols.
1234 bool "Support for hot-pluggable devices" if EXPERT
1237 This option is provided for the case where no hotplug or uevent
1238 capabilities is wanted by the kernel. You should only consider
1239 disabling this option for embedded systems that do not use modules, a
1240 dynamic /dev tree, or dynamic device discovery. Just say Y.
1244 bool "Enable support for printk" if EXPERT
1246 This option enables normal printk support. Removing it
1247 eliminates most of the message strings from the kernel image
1248 and makes the kernel more or less silent. As this makes it
1249 very difficult to diagnose system problems, saying N here is
1250 strongly discouraged.
1253 bool "BUG() support" if EXPERT
1256 Disabling this option eliminates support for BUG and WARN, reducing
1257 the size of your kernel image and potentially quietly ignoring
1258 numerous fatal conditions. You should only consider disabling this
1259 option for embedded systems with no facilities for reporting errors.
1264 bool "Enable ELF core dumps" if EXPERT
1266 Enable support for generating core dumps. Disabling saves about 4k.
1269 config PCSPKR_PLATFORM
1270 bool "Enable PC-Speaker support" if EXPERT
1271 depends on HAVE_PCSPKR_PLATFORM
1275 This option allows to disable the internal PC-Speaker
1276 support, saving some memory.
1278 config HAVE_PCSPKR_PLATFORM
1283 bool "Enable full-sized data structures for core" if EXPERT
1285 Disabling this option reduces the size of miscellaneous core
1286 kernel data structures. This saves memory on small machines,
1287 but may reduce performance.
1290 bool "Enable futex support" if EXPERT
1294 Disabling this option will cause the kernel to be built without
1295 support for "fast userspace mutexes". The resulting kernel may not
1296 run glibc-based applications correctly.
1299 bool "Enable eventpoll support" if EXPERT
1303 Disabling this option will cause the kernel to be built without
1304 support for epoll family of system calls.
1307 bool "Enable signalfd() system call" if EXPERT
1311 Enable the signalfd() system call that allows to receive signals
1312 on a file descriptor.
1317 bool "Enable timerfd() system call" if EXPERT
1321 Enable the timerfd() system call that allows to receive timer
1322 events on a file descriptor.
1327 bool "Enable eventfd() system call" if EXPERT
1331 Enable the eventfd() system call that allows to receive both
1332 kernel notification (ie. KAIO) or userspace notifications.
1337 bool "Use full shmem filesystem" if EXPERT
1341 The shmem is an internal filesystem used to manage shared memory.
1342 It is backed by swap and manages resource limits. It is also exported
1343 to userspace as tmpfs if TMPFS is enabled. Disabling this
1344 option replaces shmem and tmpfs with the much simpler ramfs code,
1345 which may be appropriate on small systems without swap.
1348 bool "Enable AIO support" if EXPERT
1351 This option enables POSIX asynchronous I/O which may by used
1352 by some high performance threaded applications. Disabling
1353 this option saves about 7k.
1356 bool "Embedded system"
1359 This option should be enabled if compiling the kernel for
1360 an embedded system so certain expert options are available
1363 config HAVE_PERF_EVENTS
1366 See tools/perf/design.txt for details.
1368 config PERF_USE_VMALLOC
1371 See tools/perf/design.txt for details
1373 menu "Kernel Performance Events And Counters"
1376 bool "Kernel performance events and counters"
1377 default y if PROFILING
1378 depends on HAVE_PERF_EVENTS
1382 Enable kernel support for various performance events provided
1383 by software and hardware.
1385 Software events are supported either built-in or via the
1386 use of generic tracepoints.
1388 Most modern CPUs support performance events via performance
1389 counter registers. These registers count the number of certain
1390 types of hw events: such as instructions executed, cachemisses
1391 suffered, or branches mis-predicted - without slowing down the
1392 kernel or applications. These registers can also trigger interrupts
1393 when a threshold number of events have passed - and can thus be
1394 used to profile the code that runs on that CPU.
1396 The Linux Performance Event subsystem provides an abstraction of
1397 these software and hardware event capabilities, available via a
1398 system call and used by the "perf" utility in tools/perf/. It
1399 provides per task and per CPU counters, and it provides event
1400 capabilities on top of those.
1404 config DEBUG_PERF_USE_VMALLOC
1406 bool "Debug: use vmalloc to back perf mmap() buffers"
1407 depends on PERF_EVENTS && DEBUG_KERNEL
1408 select PERF_USE_VMALLOC
1410 Use vmalloc memory to back perf mmap() buffers.
1412 Mostly useful for debugging the vmalloc code on platforms
1413 that don't require it.
1419 config VM_EVENT_COUNTERS
1421 bool "Enable VM event counters for /proc/vmstat" if EXPERT
1423 VM event counters are needed for event counts to be shown.
1424 This option allows the disabling of the VM event counters
1425 on EXPERT systems. /proc/vmstat will only show page counts
1426 if VM event counters are disabled.
1430 bool "Enable PCI quirk workarounds" if EXPERT
1433 This enables workarounds for various PCI chipset
1434 bugs/quirks. Disable this only if your target machine is
1435 unaffected by PCI quirks.
1439 bool "Enable SLUB debugging support" if EXPERT
1440 depends on SLUB && SYSFS
1442 SLUB has extensive debug support features. Disabling these can
1443 result in significant savings in code size. This also disables
1444 SLUB sysfs support. /sys/slab will not exist and there will be
1445 no support for cache validation etc.
1448 bool "Disable heap randomization"
1451 Randomizing heap placement makes heap exploits harder, but it
1452 also breaks ancient binaries (including anything libc5 based).
1453 This option changes the bootup default to heap randomization
1454 disabled, and can be overridden at runtime by setting
1455 /proc/sys/kernel/randomize_va_space to 2.
1457 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1460 prompt "Choose SLAB allocator"
1463 This option allows to select a slab allocator.
1468 The regular slab allocator that is established and known to work
1469 well in all environments. It organizes cache hot objects in
1470 per cpu and per node queues.
1473 bool "SLUB (Unqueued Allocator)"
1475 SLUB is a slab allocator that minimizes cache line usage
1476 instead of managing queues of cached objects (SLAB approach).
1477 Per cpu caching is realized using slabs of objects instead
1478 of queues of objects. SLUB can use memory efficiently
1479 and has enhanced diagnostics. SLUB is the default choice for
1484 bool "SLOB (Simple Allocator)"
1486 SLOB replaces the stock allocator with a drastically simpler
1487 allocator. SLOB is generally more space efficient but
1488 does not perform as well on large systems.
1492 config MMAP_ALLOW_UNINITIALIZED
1493 bool "Allow mmapped anonymous memory to be uninitialized"
1494 depends on EXPERT && !MMU
1497 Normally, and according to the Linux spec, anonymous memory obtained
1498 from mmap() has it's contents cleared before it is passed to
1499 userspace. Enabling this config option allows you to request that
1500 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1501 providing a huge performance boost. If this option is not enabled,
1502 then the flag will be ignored.
1504 This is taken advantage of by uClibc's malloc(), and also by
1505 ELF-FDPIC binfmt's brk and stack allocator.
1507 Because of the obvious security issues, this option should only be
1508 enabled on embedded devices where you control what is run in
1509 userspace. Since that isn't generally a problem on no-MMU systems,
1510 it is normally safe to say Y here.
1512 See Documentation/nommu-mmap.txt for more information.
1515 bool "Profiling support"
1517 Say Y here to enable the extended profiling support mechanisms used
1518 by profilers such as OProfile.
1521 # Place an empty function call at each tracepoint site. Can be
1522 # dynamically changed for a probe function.
1527 source "arch/Kconfig"
1529 endmenu # General setup
1531 config HAVE_GENERIC_DMA_COHERENT
1538 depends on SLAB || SLUB_DEBUG
1546 default 0 if BASE_FULL
1547 default 1 if !BASE_FULL
1550 bool "Enable loadable module support"
1552 Kernel modules are small pieces of compiled code which can
1553 be inserted in the running kernel, rather than being
1554 permanently built into the kernel. You use the "modprobe"
1555 tool to add (and sometimes remove) them. If you say Y here,
1556 many parts of the kernel can be built as modules (by
1557 answering M instead of Y where indicated): this is most
1558 useful for infrequently used options which are not required
1559 for booting. For more information, see the man pages for
1560 modprobe, lsmod, modinfo, insmod and rmmod.
1562 If you say Y here, you will need to run "make
1563 modules_install" to put the modules under /lib/modules/
1564 where modprobe can find them (you may need to be root to do
1571 config MODULE_FORCE_LOAD
1572 bool "Forced module loading"
1575 Allow loading of modules without version information (ie. modprobe
1576 --force). Forced module loading sets the 'F' (forced) taint flag and
1577 is usually a really bad idea.
1579 config MODULE_UNLOAD
1580 bool "Module unloading"
1582 Without this option you will not be able to unload any
1583 modules (note that some modules may not be unloadable
1584 anyway), which makes your kernel smaller, faster
1585 and simpler. If unsure, say Y.
1587 config MODULE_FORCE_UNLOAD
1588 bool "Forced module unloading"
1589 depends on MODULE_UNLOAD && EXPERIMENTAL
1591 This option allows you to force a module to unload, even if the
1592 kernel believes it is unsafe: the kernel will remove the module
1593 without waiting for anyone to stop using it (using the -f option to
1594 rmmod). This is mainly for kernel developers and desperate users.
1598 bool "Module versioning support"
1600 Usually, you have to use modules compiled with your kernel.
1601 Saying Y here makes it sometimes possible to use modules
1602 compiled for different kernels, by adding enough information
1603 to the modules to (hopefully) spot any changes which would
1604 make them incompatible with the kernel you are running. If
1607 config MODULE_SRCVERSION_ALL
1608 bool "Source checksum for all modules"
1610 Modules which contain a MODULE_VERSION get an extra "srcversion"
1611 field inserted into their modinfo section, which contains a
1612 sum of the source files which made it. This helps maintainers
1613 see exactly which source was used to build a module (since
1614 others sometimes change the module source without updating
1615 the version). With this option, such a "srcversion" field
1616 will be created for all modules. If unsure, say N.
1620 config INIT_ALL_POSSIBLE
1623 Back when each arch used to define their own cpu_online_mask and
1624 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
1625 with all 1s, and others with all 0s. When they were centralised,
1626 it was better to provide this option than to break all the archs
1627 and have several arch maintainers pursuing me down dark alleys.
1632 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1634 Need stop_machine() primitive.
1636 source "block/Kconfig"
1638 config PREEMPT_NOTIFIERS
1645 source "kernel/Kconfig.locks"