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56 drivers that have been replaced by something else, and/or are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
271 bool "open by fhandle syscalls"
274 If you say Y here, a user level program will be able to map
275 file names to handle and then later use the handle for
276 different file system operations. This is useful in implementing
277 userspace file servers, which now track files using handles instead
278 of names. The handle would remain the same even if file names
279 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
283 bool "Auditing support"
286 Enable auditing infrastructure that can be used with another
287 kernel subsystem, such as SELinux (which requires this for
288 logging of avc messages output). Does not do system-call
289 auditing without CONFIG_AUDITSYSCALL.
292 bool "Enable system-call auditing support"
293 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || (ARM && AEABI && !OABI_COMPAT))
294 default y if SECURITY_SELINUX
296 Enable low-overhead system-call auditing infrastructure that
297 can be used independently or with another kernel subsystem,
302 depends on AUDITSYSCALL
307 depends on AUDITSYSCALL
310 config AUDIT_LOGINUID_IMMUTABLE
311 bool "Make audit loginuid immutable"
314 The config option toggles if a task setting its loginuid requires
315 CAP_SYS_AUDITCONTROL or if that task should require no special permissions
316 but should instead only allow setting its loginuid if it was never
317 previously set. On systems which use systemd or a similar central
318 process to restart login services this should be set to true. On older
319 systems in which an admin would typically have to directly stop and
320 start processes this should be set to false. Setting this to true allows
321 one to drop potentially dangerous capabilites from the login tasks,
322 but may not be backwards compatible with older init systems.
324 source "kernel/irq/Kconfig"
325 source "kernel/time/Kconfig"
327 menu "CPU/Task time and stats accounting"
330 prompt "Cputime accounting"
331 default TICK_CPU_ACCOUNTING if !PPC64
332 default VIRT_CPU_ACCOUNTING if PPC64
334 # Kind of a stub config for the pure tick based cputime accounting
335 config TICK_CPU_ACCOUNTING
336 bool "Simple tick based cputime accounting"
339 This is the basic tick based cputime accounting that maintains
340 statistics about user, system and idle time spent on per jiffies
345 config VIRT_CPU_ACCOUNTING
346 bool "Deterministic task and CPU time accounting"
347 depends on HAVE_VIRT_CPU_ACCOUNTING
349 Select this option to enable more accurate task and CPU time
350 accounting. This is done by reading a CPU counter on each
351 kernel entry and exit and on transitions within the kernel
352 between system, softirq and hardirq state, so there is a
353 small performance impact. In the case of s390 or IBM POWER > 5,
354 this also enables accounting of stolen time on logically-partitioned
357 config IRQ_TIME_ACCOUNTING
358 bool "Fine granularity task level IRQ time accounting"
359 depends on HAVE_IRQ_TIME_ACCOUNTING
361 Select this option to enable fine granularity task irq time
362 accounting. This is done by reading a timestamp on each
363 transitions between softirq and hardirq state, so there can be a
364 small performance impact.
366 If in doubt, say N here.
370 config BSD_PROCESS_ACCT
371 bool "BSD Process Accounting"
373 If you say Y here, a user level program will be able to instruct the
374 kernel (via a special system call) to write process accounting
375 information to a file: whenever a process exits, information about
376 that process will be appended to the file by the kernel. The
377 information includes things such as creation time, owning user,
378 command name, memory usage, controlling terminal etc. (the complete
379 list is in the struct acct in <file:include/linux/acct.h>). It is
380 up to the user level program to do useful things with this
381 information. This is generally a good idea, so say Y.
383 config BSD_PROCESS_ACCT_V3
384 bool "BSD Process Accounting version 3 file format"
385 depends on BSD_PROCESS_ACCT
388 If you say Y here, the process accounting information is written
389 in a new file format that also logs the process IDs of each
390 process and it's parent. Note that this file format is incompatible
391 with previous v0/v1/v2 file formats, so you will need updated tools
392 for processing it. A preliminary version of these tools is available
393 at <http://www.gnu.org/software/acct/>.
396 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
400 Export selected statistics for tasks/processes through the
401 generic netlink interface. Unlike BSD process accounting, the
402 statistics are available during the lifetime of tasks/processes as
403 responses to commands. Like BSD accounting, they are sent to user
408 config TASK_DELAY_ACCT
409 bool "Enable per-task delay accounting (EXPERIMENTAL)"
412 Collect information on time spent by a task waiting for system
413 resources like cpu, synchronous block I/O completion and swapping
414 in pages. Such statistics can help in setting a task's priorities
415 relative to other tasks for cpu, io, rss limits etc.
420 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
423 Collect extended task accounting data and send the data
424 to userland for processing over the taskstats interface.
428 config TASK_IO_ACCOUNTING
429 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
430 depends on TASK_XACCT
432 Collect information on the number of bytes of storage I/O which this
437 endmenu # "CPU/Task time and stats accounting"
442 prompt "RCU Implementation"
446 bool "Tree-based hierarchical RCU"
447 depends on !PREEMPT && SMP
449 This option selects the RCU implementation that is
450 designed for very large SMP system with hundreds or
451 thousands of CPUs. It also scales down nicely to
454 config TREE_PREEMPT_RCU
455 bool "Preemptible tree-based hierarchical RCU"
456 depends on PREEMPT && SMP
458 This option selects the RCU implementation that is
459 designed for very large SMP systems with hundreds or
460 thousands of CPUs, but for which real-time response
461 is also required. It also scales down nicely to
465 bool "UP-only small-memory-footprint RCU"
466 depends on !PREEMPT && !SMP
468 This option selects the RCU implementation that is
469 designed for UP systems from which real-time response
470 is not required. This option greatly reduces the
471 memory footprint of RCU.
473 config TINY_PREEMPT_RCU
474 bool "Preemptible UP-only small-memory-footprint RCU"
475 depends on PREEMPT && !SMP
477 This option selects the RCU implementation that is designed
478 for real-time UP systems. This option greatly reduces the
479 memory footprint of RCU.
484 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
486 This option enables preemptible-RCU code that is common between
487 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
490 int "Tree-based hierarchical RCU fanout value"
493 depends on TREE_RCU || TREE_PREEMPT_RCU
497 This option controls the fanout of hierarchical implementations
498 of RCU, allowing RCU to work efficiently on machines with
499 large numbers of CPUs. This value must be at least the fourth
500 root of NR_CPUS, which allows NR_CPUS to be insanely large.
501 The default value of RCU_FANOUT should be used for production
502 systems, but if you are stress-testing the RCU implementation
503 itself, small RCU_FANOUT values allow you to test large-system
504 code paths on small(er) systems.
506 Select a specific number if testing RCU itself.
507 Take the default if unsure.
509 config RCU_FANOUT_LEAF
510 int "Tree-based hierarchical RCU leaf-level fanout value"
511 range 2 RCU_FANOUT if 64BIT
512 range 2 RCU_FANOUT if !64BIT
513 depends on TREE_RCU || TREE_PREEMPT_RCU
516 This option controls the leaf-level fanout of hierarchical
517 implementations of RCU, and allows trading off cache misses
518 against lock contention. Systems that synchronize their
519 scheduling-clock interrupts for energy-efficiency reasons will
520 want the default because the smaller leaf-level fanout keeps
521 lock contention levels acceptably low. Very large systems
522 (hundreds or thousands of CPUs) will instead want to set this
523 value to the maximum value possible in order to reduce the
524 number of cache misses incurred during RCU's grace-period
525 initialization. These systems tend to run CPU-bound, and thus
526 are not helped by synchronized interrupts, and thus tend to
527 skew them, which reduces lock contention enough that large
528 leaf-level fanouts work well.
530 Select a specific number if testing RCU itself.
532 Select the maximum permissible value for large systems.
534 Take the default if unsure.
536 config RCU_FANOUT_EXACT
537 bool "Disable tree-based hierarchical RCU auto-balancing"
538 depends on TREE_RCU || TREE_PREEMPT_RCU
541 This option forces use of the exact RCU_FANOUT value specified,
542 regardless of imbalances in the hierarchy. This is useful for
543 testing RCU itself, and might one day be useful on systems with
544 strong NUMA behavior.
546 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
550 config RCU_FAST_NO_HZ
551 bool "Accelerate last non-dyntick-idle CPU's grace periods"
552 depends on NO_HZ && SMP
555 This option causes RCU to attempt to accelerate grace periods
556 in order to allow CPUs to enter dynticks-idle state more
557 quickly. On the other hand, this option increases the overhead
558 of the dynticks-idle checking, particularly on systems with
559 large numbers of CPUs.
561 Say Y if energy efficiency is critically important, particularly
562 if you have relatively few CPUs.
564 Say N if you are unsure.
566 config TREE_RCU_TRACE
567 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
570 This option provides tracing for the TREE_RCU and
571 TREE_PREEMPT_RCU implementations, permitting Makefile to
572 trivially select kernel/rcutree_trace.c.
575 bool "Enable RCU priority boosting"
576 depends on RT_MUTEXES && PREEMPT_RCU
579 This option boosts the priority of preempted RCU readers that
580 block the current preemptible RCU grace period for too long.
581 This option also prevents heavy loads from blocking RCU
582 callback invocation for all flavors of RCU.
584 Say Y here if you are working with real-time apps or heavy loads
585 Say N here if you are unsure.
587 config RCU_BOOST_PRIO
588 int "Real-time priority to boost RCU readers to"
593 This option specifies the real-time priority to which long-term
594 preempted RCU readers are to be boosted. If you are working
595 with a real-time application that has one or more CPU-bound
596 threads running at a real-time priority level, you should set
597 RCU_BOOST_PRIO to a priority higher then the highest-priority
598 real-time CPU-bound thread. The default RCU_BOOST_PRIO value
599 of 1 is appropriate in the common case, which is real-time
600 applications that do not have any CPU-bound threads.
602 Some real-time applications might not have a single real-time
603 thread that saturates a given CPU, but instead might have
604 multiple real-time threads that, taken together, fully utilize
605 that CPU. In this case, you should set RCU_BOOST_PRIO to
606 a priority higher than the lowest-priority thread that is
607 conspiring to prevent the CPU from running any non-real-time
608 tasks. For example, if one thread at priority 10 and another
609 thread at priority 5 are between themselves fully consuming
610 the CPU time on a given CPU, then RCU_BOOST_PRIO should be
611 set to priority 6 or higher.
613 Specify the real-time priority, or take the default if unsure.
615 config RCU_BOOST_DELAY
616 int "Milliseconds to delay boosting after RCU grace-period start"
621 This option specifies the time to wait after the beginning of
622 a given grace period before priority-boosting preempted RCU
623 readers blocking that grace period. Note that any RCU reader
624 blocking an expedited RCU grace period is boosted immediately.
626 Accept the default if unsure.
628 endmenu # "RCU Subsystem"
631 tristate "Kernel .config support"
633 This option enables the complete Linux kernel ".config" file
634 contents to be saved in the kernel. It provides documentation
635 of which kernel options are used in a running kernel or in an
636 on-disk kernel. This information can be extracted from the kernel
637 image file with the script scripts/extract-ikconfig and used as
638 input to rebuild the current kernel or to build another kernel.
639 It can also be extracted from a running kernel by reading
640 /proc/config.gz if enabled (below).
643 bool "Enable access to .config through /proc/config.gz"
644 depends on IKCONFIG && PROC_FS
646 This option enables access to the kernel configuration file
647 through /proc/config.gz.
650 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
654 Select kernel log buffer size as a power of 2.
664 # Architectures with an unreliable sched_clock() should select this:
666 config HAVE_UNSTABLE_SCHED_CLOCK
670 boolean "Control Group support"
673 This option adds support for grouping sets of processes together, for
674 use with process control subsystems such as Cpusets, CFS, memory
675 controls or device isolation.
677 - Documentation/scheduler/sched-design-CFS.txt (CFS)
678 - Documentation/cgroups/ (features for grouping, isolation
679 and resource control)
686 bool "Example debug cgroup subsystem"
689 This option enables a simple cgroup subsystem that
690 exports useful debugging information about the cgroups
695 config CGROUP_FREEZER
696 bool "Freezer cgroup subsystem"
698 Provides a way to freeze and unfreeze all tasks in a
702 bool "Device controller for cgroups"
704 Provides a cgroup implementing whitelists for devices which
705 a process in the cgroup can mknod or open.
708 bool "Cpuset support"
710 This option will let you create and manage CPUSETs which
711 allow dynamically partitioning a system into sets of CPUs and
712 Memory Nodes and assigning tasks to run only within those sets.
713 This is primarily useful on large SMP or NUMA systems.
717 config PROC_PID_CPUSET
718 bool "Include legacy /proc/<pid>/cpuset file"
722 config CGROUP_CPUACCT
723 bool "Simple CPU accounting cgroup subsystem"
725 Provides a simple Resource Controller for monitoring the
726 total CPU consumed by the tasks in a cgroup.
728 config RESOURCE_COUNTERS
729 bool "Resource counters"
731 This option enables controller independent resource accounting
732 infrastructure that works with cgroups.
735 bool "Memory Resource Controller for Control Groups"
736 depends on RESOURCE_COUNTERS
739 Provides a memory resource controller that manages both anonymous
740 memory and page cache. (See Documentation/cgroups/memory.txt)
742 Note that setting this option increases fixed memory overhead
743 associated with each page of memory in the system. By this,
744 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
745 usage tracking struct at boot. Total amount of this is printed out
748 Only enable when you're ok with these trade offs and really
749 sure you need the memory resource controller. Even when you enable
750 this, you can set "cgroup_disable=memory" at your boot option to
751 disable memory resource controller and you can avoid overheads.
752 (and lose benefits of memory resource controller)
754 This config option also selects MM_OWNER config option, which
755 could in turn add some fork/exit overhead.
758 bool "Memory Resource Controller Swap Extension"
759 depends on MEMCG && SWAP
761 Add swap management feature to memory resource controller. When you
762 enable this, you can limit mem+swap usage per cgroup. In other words,
763 when you disable this, memory resource controller has no cares to
764 usage of swap...a process can exhaust all of the swap. This extension
765 is useful when you want to avoid exhaustion swap but this itself
766 adds more overheads and consumes memory for remembering information.
767 Especially if you use 32bit system or small memory system, please
768 be careful about enabling this. When memory resource controller
769 is disabled by boot option, this will be automatically disabled and
770 there will be no overhead from this. Even when you set this config=y,
771 if boot option "swapaccount=0" is set, swap will not be accounted.
772 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
773 size is 4096bytes, 512k per 1Gbytes of swap.
774 config MEMCG_SWAP_ENABLED
775 bool "Memory Resource Controller Swap Extension enabled by default"
776 depends on MEMCG_SWAP
779 Memory Resource Controller Swap Extension comes with its price in
780 a bigger memory consumption. General purpose distribution kernels
781 which want to enable the feature but keep it disabled by default
782 and let the user enable it by swapaccount boot command line
783 parameter should have this option unselected.
784 For those who want to have the feature enabled by default should
785 select this option (if, for some reason, they need to disable it
786 then swapaccount=0 does the trick).
788 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
789 depends on MEMCG && EXPERIMENTAL
792 The Kernel Memory extension for Memory Resource Controller can limit
793 the amount of memory used by kernel objects in the system. Those are
794 fundamentally different from the entities handled by the standard
795 Memory Controller, which are page-based, and can be swapped. Users of
796 the kmem extension can use it to guarantee that no group of processes
797 will ever exhaust kernel resources alone.
799 config CGROUP_HUGETLB
800 bool "HugeTLB Resource Controller for Control Groups"
801 depends on RESOURCE_COUNTERS && HUGETLB_PAGE && EXPERIMENTAL
804 Provides a cgroup Resource Controller for HugeTLB pages.
805 When you enable this, you can put a per cgroup limit on HugeTLB usage.
806 The limit is enforced during page fault. Since HugeTLB doesn't
807 support page reclaim, enforcing the limit at page fault time implies
808 that, the application will get SIGBUS signal if it tries to access
809 HugeTLB pages beyond its limit. This requires the application to know
810 beforehand how much HugeTLB pages it would require for its use. The
811 control group is tracked in the third page lru pointer. This means
812 that we cannot use the controller with huge page less than 3 pages.
815 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
816 depends on PERF_EVENTS && CGROUPS
818 This option extends the per-cpu mode to restrict monitoring to
819 threads which belong to the cgroup specified and run on the
824 menuconfig CGROUP_SCHED
825 bool "Group CPU scheduler"
828 This feature lets CPU scheduler recognize task groups and control CPU
829 bandwidth allocation to such task groups. It uses cgroups to group
833 config FAIR_GROUP_SCHED
834 bool "Group scheduling for SCHED_OTHER"
835 depends on CGROUP_SCHED
839 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
840 depends on EXPERIMENTAL
841 depends on FAIR_GROUP_SCHED
844 This option allows users to define CPU bandwidth rates (limits) for
845 tasks running within the fair group scheduler. Groups with no limit
846 set are considered to be unconstrained and will run with no
848 See tip/Documentation/scheduler/sched-bwc.txt for more information.
850 config RT_GROUP_SCHED
851 bool "Group scheduling for SCHED_RR/FIFO"
852 depends on EXPERIMENTAL
853 depends on CGROUP_SCHED
856 This feature lets you explicitly allocate real CPU bandwidth
857 to task groups. If enabled, it will also make it impossible to
858 schedule realtime tasks for non-root users until you allocate
859 realtime bandwidth for them.
860 See Documentation/scheduler/sched-rt-group.txt for more information.
865 bool "Block IO controller"
869 Generic block IO controller cgroup interface. This is the common
870 cgroup interface which should be used by various IO controlling
873 Currently, CFQ IO scheduler uses it to recognize task groups and
874 control disk bandwidth allocation (proportional time slice allocation)
875 to such task groups. It is also used by bio throttling logic in
876 block layer to implement upper limit in IO rates on a device.
878 This option only enables generic Block IO controller infrastructure.
879 One needs to also enable actual IO controlling logic/policy. For
880 enabling proportional weight division of disk bandwidth in CFQ, set
881 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
882 CONFIG_BLK_DEV_THROTTLING=y.
884 See Documentation/cgroups/blkio-controller.txt for more information.
886 config DEBUG_BLK_CGROUP
887 bool "Enable Block IO controller debugging"
888 depends on BLK_CGROUP
891 Enable some debugging help. Currently it exports additional stat
892 files in a cgroup which can be useful for debugging.
896 config CHECKPOINT_RESTORE
897 bool "Checkpoint/restore support" if EXPERT
900 Enables additional kernel features in a sake of checkpoint/restore.
901 In particular it adds auxiliary prctl codes to setup process text,
902 data and heap segment sizes, and a few additional /proc filesystem
905 If unsure, say N here.
907 menuconfig NAMESPACES
908 bool "Namespaces support" if EXPERT
911 Provides the way to make tasks work with different objects using
912 the same id. For example same IPC id may refer to different objects
913 or same user id or pid may refer to different tasks when used in
914 different namespaces.
922 In this namespace tasks see different info provided with the
927 depends on (SYSVIPC || POSIX_MQUEUE)
930 In this namespace tasks work with IPC ids which correspond to
931 different IPC objects in different namespaces.
934 bool "User namespace (EXPERIMENTAL)"
935 depends on EXPERIMENTAL
936 depends on UIDGID_CONVERTED
937 select UIDGID_STRICT_TYPE_CHECKS
941 This allows containers, i.e. vservers, to use user namespaces
942 to provide different user info for different servers.
946 bool "PID Namespaces"
949 Support process id namespaces. This allows having multiple
950 processes with the same pid as long as they are in different
951 pid namespaces. This is a building block of containers.
954 bool "Network namespace"
958 Allow user space to create what appear to be multiple instances
959 of the network stack.
963 config UIDGID_CONVERTED
964 # True if all of the selected software conmponents are known
965 # to have uid_t and gid_t converted to kuid_t and kgid_t
966 # where appropriate and are otherwise safe to use with
967 # the user namespace.
971 # List of kernel pieces that need user namespace work
973 depends on SYSVIPC = n
978 depends on AUDITSYSCALL = n
979 depends on TASKSTATS = n
980 depends on TRACING = n
981 depends on FS_POSIX_ACL = n
983 depends on QUOTACTL = n
984 depends on DEBUG_CREDENTIALS = n
985 depends on BSD_PROCESS_ACCT = n
987 depends on PROC_EVENTS = n
991 depends on NET_9P = n
993 depends on PHONET = n
994 depends on NET_CLS_FLOW = n
995 depends on NETFILTER_XT_MATCH_OWNER = n
996 depends on NETFILTER_XT_MATCH_RECENT = n
997 depends on NETFILTER_XT_TARGET_LOG = n
998 depends on NETFILTER_NETLINK_LOG = n
1001 depends on IP_SCTP = n
1002 depends on AF_RXRPC = n
1004 depends on NET_KEY = n
1005 depends on INET_DIAG = n
1006 depends on DNS_RESOLVER = n
1008 depends on ATALK = n
1011 depends on USB_DEVICEFS = n
1012 depends on USB_GADGETFS = n
1013 depends on USB_FUNCTIONFS = n
1014 depends on DEVTMPFS = n
1015 depends on XENFS = n
1017 depends on 9P_FS = n
1018 depends on ADFS_FS = n
1019 depends on AFFS_FS = n
1020 depends on AFS_FS = n
1021 depends on AUTOFS4_FS = n
1022 depends on BEFS_FS = n
1023 depends on BFS_FS = n
1024 depends on BTRFS_FS = n
1025 depends on CEPH_FS = n
1027 depends on CODA_FS = n
1028 depends on CONFIGFS_FS = n
1029 depends on CRAMFS = n
1030 depends on DEBUG_FS = n
1031 depends on ECRYPT_FS = n
1032 depends on EFS_FS = n
1033 depends on EXOFS_FS = n
1034 depends on FAT_FS = n
1035 depends on FUSE_FS = n
1036 depends on GFS2_FS = n
1037 depends on HFS_FS = n
1038 depends on HFSPLUS_FS = n
1039 depends on HPFS_FS = n
1040 depends on HUGETLBFS = n
1041 depends on ISO9660_FS = n
1042 depends on JFFS2_FS = n
1043 depends on JFS_FS = n
1044 depends on LOGFS = n
1045 depends on MINIX_FS = n
1046 depends on NCP_FS = n
1048 depends on NFS_FS = n
1049 depends on NILFS2_FS = n
1050 depends on NTFS_FS = n
1051 depends on OCFS2_FS = n
1052 depends on OMFS_FS = n
1053 depends on QNX4FS_FS = n
1054 depends on QNX6FS_FS = n
1055 depends on REISERFS_FS = n
1056 depends on SQUASHFS = n
1057 depends on SYSV_FS = n
1058 depends on UBIFS_FS = n
1059 depends on UDF_FS = n
1060 depends on UFS_FS = n
1061 depends on VXFS_FS = n
1062 depends on XFS_FS = n
1064 depends on !UML || HOSTFS = n
1066 # The rare drivers that won't build
1068 depends on AIRO_CS = n
1070 depends on INFINIBAND_QIB = n
1071 depends on BLK_DEV_LOOP = n
1072 depends on ANDROID_BINDER_IPC = n
1075 depends on SECURITY_TOMOYO = n
1076 depends on SECURITY_APPARMOR = n
1078 config UIDGID_STRICT_TYPE_CHECKS
1079 bool "Require conversions between uid/gids and their internal representation"
1080 depends on UIDGID_CONVERTED
1083 While the nececessary conversions are being added to all subsystems this option allows
1084 the code to continue to build for unconverted subsystems.
1086 Say Y here if you want the strict type checking enabled
1088 config SCHED_AUTOGROUP
1089 bool "Automatic process group scheduling"
1093 select FAIR_GROUP_SCHED
1095 This option optimizes the scheduler for common desktop workloads by
1096 automatically creating and populating task groups. This separation
1097 of workloads isolates aggressive CPU burners (like build jobs) from
1098 desktop applications. Task group autogeneration is currently based
1104 config SYSFS_DEPRECATED
1105 bool "Enable deprecated sysfs features to support old userspace tools"
1109 This option adds code that switches the layout of the "block" class
1110 devices, to not show up in /sys/class/block/, but only in
1113 This switch is only active when the sysfs.deprecated=1 boot option is
1114 passed or the SYSFS_DEPRECATED_V2 option is set.
1116 This option allows new kernels to run on old distributions and tools,
1117 which might get confused by /sys/class/block/. Since 2007/2008 all
1118 major distributions and tools handle this just fine.
1120 Recent distributions and userspace tools after 2009/2010 depend on
1121 the existence of /sys/class/block/, and will not work with this
1124 Only if you are using a new kernel on an old distribution, you might
1127 config SYSFS_DEPRECATED_V2
1128 bool "Enable deprecated sysfs features by default"
1131 depends on SYSFS_DEPRECATED
1133 Enable deprecated sysfs by default.
1135 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1138 Only if you are using a new kernel on an old distribution, you might
1139 need to say Y here. Even then, odds are you would not need it
1140 enabled, you can always pass the boot option if absolutely necessary.
1143 bool "Kernel->user space relay support (formerly relayfs)"
1145 This option enables support for relay interface support in
1146 certain file systems (such as debugfs).
1147 It is designed to provide an efficient mechanism for tools and
1148 facilities to relay large amounts of data from kernel space to
1153 config BLK_DEV_INITRD
1154 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1155 depends on BROKEN || !FRV
1157 The initial RAM filesystem is a ramfs which is loaded by the
1158 boot loader (loadlin or lilo) and that is mounted as root
1159 before the normal boot procedure. It is typically used to
1160 load modules needed to mount the "real" root file system,
1161 etc. See <file:Documentation/initrd.txt> for details.
1163 If RAM disk support (BLK_DEV_RAM) is also included, this
1164 also enables initial RAM disk (initrd) support and adds
1165 15 Kbytes (more on some other architectures) to the kernel size.
1171 source "usr/Kconfig"
1175 config CC_OPTIMIZE_FOR_SIZE
1176 bool "Optimize for size"
1178 Enabling this option will pass "-Os" instead of "-O2" to gcc
1179 resulting in a smaller kernel.
1190 bool "Configure standard kernel features (expert users)"
1191 # Unhide debug options, to make the on-by-default options visible
1194 This option allows certain base kernel options and settings
1195 to be disabled or tweaked. This is for specialized
1196 environments which can tolerate a "non-standard" kernel.
1197 Only use this if you really know what you are doing.
1200 bool "Enable 16-bit UID system calls" if EXPERT
1201 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
1204 This enables the legacy 16-bit UID syscall wrappers.
1206 config SYSCTL_SYSCALL
1207 bool "Sysctl syscall support" if EXPERT
1208 depends on PROC_SYSCTL
1212 sys_sysctl uses binary paths that have been found challenging
1213 to properly maintain and use. The interface in /proc/sys
1214 using paths with ascii names is now the primary path to this
1217 Almost nothing using the binary sysctl interface so if you are
1218 trying to save some space it is probably safe to disable this,
1219 making your kernel marginally smaller.
1221 If unsure say N here.
1224 bool "Load all symbols for debugging/ksymoops" if EXPERT
1227 Say Y here to let the kernel print out symbolic crash information and
1228 symbolic stack backtraces. This increases the size of the kernel
1229 somewhat, as all symbols have to be loaded into the kernel image.
1232 bool "Include all symbols in kallsyms"
1233 depends on DEBUG_KERNEL && KALLSYMS
1235 Normally kallsyms only contains the symbols of functions for nicer
1236 OOPS messages and backtraces (i.e., symbols from the text and inittext
1237 sections). This is sufficient for most cases. And only in very rare
1238 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1239 names of variables from the data sections, etc).
1241 This option makes sure that all symbols are loaded into the kernel
1242 image (i.e., symbols from all sections) in cost of increased kernel
1243 size (depending on the kernel configuration, it may be 300KiB or
1244 something like this).
1246 Say N unless you really need all symbols.
1249 bool "Support for hot-pluggable devices" if EXPERT
1252 This option is provided for the case where no hotplug or uevent
1253 capabilities is wanted by the kernel. You should only consider
1254 disabling this option for embedded systems that do not use modules, a
1255 dynamic /dev tree, or dynamic device discovery. Just say Y.
1259 bool "Enable support for printk" if EXPERT
1261 This option enables normal printk support. Removing it
1262 eliminates most of the message strings from the kernel image
1263 and makes the kernel more or less silent. As this makes it
1264 very difficult to diagnose system problems, saying N here is
1265 strongly discouraged.
1268 bool "BUG() support" if EXPERT
1271 Disabling this option eliminates support for BUG and WARN, reducing
1272 the size of your kernel image and potentially quietly ignoring
1273 numerous fatal conditions. You should only consider disabling this
1274 option for embedded systems with no facilities for reporting errors.
1279 bool "Enable ELF core dumps" if EXPERT
1281 Enable support for generating core dumps. Disabling saves about 4k.
1284 config PCSPKR_PLATFORM
1285 bool "Enable PC-Speaker support" if EXPERT
1286 depends on HAVE_PCSPKR_PLATFORM
1290 This option allows to disable the internal PC-Speaker
1291 support, saving some memory.
1293 config HAVE_PCSPKR_PLATFORM
1298 bool "Enable full-sized data structures for core" if EXPERT
1300 Disabling this option reduces the size of miscellaneous core
1301 kernel data structures. This saves memory on small machines,
1302 but may reduce performance.
1305 bool "Enable futex support" if EXPERT
1309 Disabling this option will cause the kernel to be built without
1310 support for "fast userspace mutexes". The resulting kernel may not
1311 run glibc-based applications correctly.
1314 bool "Enable eventpoll support" if EXPERT
1318 Disabling this option will cause the kernel to be built without
1319 support for epoll family of system calls.
1322 bool "Enable signalfd() system call" if EXPERT
1326 Enable the signalfd() system call that allows to receive signals
1327 on a file descriptor.
1332 bool "Enable timerfd() system call" if EXPERT
1336 Enable the timerfd() system call that allows to receive timer
1337 events on a file descriptor.
1342 bool "Enable eventfd() system call" if EXPERT
1346 Enable the eventfd() system call that allows to receive both
1347 kernel notification (ie. KAIO) or userspace notifications.
1352 bool "Use full shmem filesystem" if EXPERT
1356 The shmem is an internal filesystem used to manage shared memory.
1357 It is backed by swap and manages resource limits. It is also exported
1358 to userspace as tmpfs if TMPFS is enabled. Disabling this
1359 option replaces shmem and tmpfs with the much simpler ramfs code,
1360 which may be appropriate on small systems without swap.
1363 bool "Enable AIO support" if EXPERT
1366 This option enables POSIX asynchronous I/O which may by used
1367 by some high performance threaded applications. Disabling
1368 this option saves about 7k.
1371 bool "Embedded system"
1374 This option should be enabled if compiling the kernel for
1375 an embedded system so certain expert options are available
1378 config HAVE_PERF_EVENTS
1381 See tools/perf/design.txt for details.
1383 config PERF_USE_VMALLOC
1386 See tools/perf/design.txt for details
1388 menu "Kernel Performance Events And Counters"
1391 bool "Kernel performance events and counters"
1392 default y if PROFILING
1393 depends on HAVE_PERF_EVENTS
1397 Enable kernel support for various performance events provided
1398 by software and hardware.
1400 Software events are supported either built-in or via the
1401 use of generic tracepoints.
1403 Most modern CPUs support performance events via performance
1404 counter registers. These registers count the number of certain
1405 types of hw events: such as instructions executed, cachemisses
1406 suffered, or branches mis-predicted - without slowing down the
1407 kernel or applications. These registers can also trigger interrupts
1408 when a threshold number of events have passed - and can thus be
1409 used to profile the code that runs on that CPU.
1411 The Linux Performance Event subsystem provides an abstraction of
1412 these software and hardware event capabilities, available via a
1413 system call and used by the "perf" utility in tools/perf/. It
1414 provides per task and per CPU counters, and it provides event
1415 capabilities on top of those.
1419 config DEBUG_PERF_USE_VMALLOC
1421 bool "Debug: use vmalloc to back perf mmap() buffers"
1422 depends on PERF_EVENTS && DEBUG_KERNEL
1423 select PERF_USE_VMALLOC
1425 Use vmalloc memory to back perf mmap() buffers.
1427 Mostly useful for debugging the vmalloc code on platforms
1428 that don't require it.
1434 config VM_EVENT_COUNTERS
1436 bool "Enable VM event counters for /proc/vmstat" if EXPERT
1438 VM event counters are needed for event counts to be shown.
1439 This option allows the disabling of the VM event counters
1440 on EXPERT systems. /proc/vmstat will only show page counts
1441 if VM event counters are disabled.
1445 bool "Enable PCI quirk workarounds" if EXPERT
1448 This enables workarounds for various PCI chipset
1449 bugs/quirks. Disable this only if your target machine is
1450 unaffected by PCI quirks.
1454 bool "Enable SLUB debugging support" if EXPERT
1455 depends on SLUB && SYSFS
1457 SLUB has extensive debug support features. Disabling these can
1458 result in significant savings in code size. This also disables
1459 SLUB sysfs support. /sys/slab will not exist and there will be
1460 no support for cache validation etc.
1463 bool "Disable heap randomization"
1466 Randomizing heap placement makes heap exploits harder, but it
1467 also breaks ancient binaries (including anything libc5 based).
1468 This option changes the bootup default to heap randomization
1469 disabled, and can be overridden at runtime by setting
1470 /proc/sys/kernel/randomize_va_space to 2.
1472 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1475 prompt "Choose SLAB allocator"
1478 This option allows to select a slab allocator.
1483 The regular slab allocator that is established and known to work
1484 well in all environments. It organizes cache hot objects in
1485 per cpu and per node queues.
1488 bool "SLUB (Unqueued Allocator)"
1490 SLUB is a slab allocator that minimizes cache line usage
1491 instead of managing queues of cached objects (SLAB approach).
1492 Per cpu caching is realized using slabs of objects instead
1493 of queues of objects. SLUB can use memory efficiently
1494 and has enhanced diagnostics. SLUB is the default choice for
1499 bool "SLOB (Simple Allocator)"
1501 SLOB replaces the stock allocator with a drastically simpler
1502 allocator. SLOB is generally more space efficient but
1503 does not perform as well on large systems.
1507 config MMAP_ALLOW_UNINITIALIZED
1508 bool "Allow mmapped anonymous memory to be uninitialized"
1509 depends on EXPERT && !MMU
1512 Normally, and according to the Linux spec, anonymous memory obtained
1513 from mmap() has it's contents cleared before it is passed to
1514 userspace. Enabling this config option allows you to request that
1515 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1516 providing a huge performance boost. If this option is not enabled,
1517 then the flag will be ignored.
1519 This is taken advantage of by uClibc's malloc(), and also by
1520 ELF-FDPIC binfmt's brk and stack allocator.
1522 Because of the obvious security issues, this option should only be
1523 enabled on embedded devices where you control what is run in
1524 userspace. Since that isn't generally a problem on no-MMU systems,
1525 it is normally safe to say Y here.
1527 See Documentation/nommu-mmap.txt for more information.
1530 bool "Profiling support"
1532 Say Y here to enable the extended profiling support mechanisms used
1533 by profilers such as OProfile.
1536 # Place an empty function call at each tracepoint site. Can be
1537 # dynamically changed for a probe function.
1542 source "arch/Kconfig"
1544 endmenu # General setup
1546 config HAVE_GENERIC_DMA_COHERENT
1553 depends on SLAB || SLUB_DEBUG
1561 default 0 if BASE_FULL
1562 default 1 if !BASE_FULL
1565 bool "Enable loadable module support"
1567 Kernel modules are small pieces of compiled code which can
1568 be inserted in the running kernel, rather than being
1569 permanently built into the kernel. You use the "modprobe"
1570 tool to add (and sometimes remove) them. If you say Y here,
1571 many parts of the kernel can be built as modules (by
1572 answering M instead of Y where indicated): this is most
1573 useful for infrequently used options which are not required
1574 for booting. For more information, see the man pages for
1575 modprobe, lsmod, modinfo, insmod and rmmod.
1577 If you say Y here, you will need to run "make
1578 modules_install" to put the modules under /lib/modules/
1579 where modprobe can find them (you may need to be root to do
1586 config MODULE_FORCE_LOAD
1587 bool "Forced module loading"
1590 Allow loading of modules without version information (ie. modprobe
1591 --force). Forced module loading sets the 'F' (forced) taint flag and
1592 is usually a really bad idea.
1594 config MODULE_UNLOAD
1595 bool "Module unloading"
1597 Without this option you will not be able to unload any
1598 modules (note that some modules may not be unloadable
1599 anyway), which makes your kernel smaller, faster
1600 and simpler. If unsure, say Y.
1602 config MODULE_FORCE_UNLOAD
1603 bool "Forced module unloading"
1604 depends on MODULE_UNLOAD && EXPERIMENTAL
1606 This option allows you to force a module to unload, even if the
1607 kernel believes it is unsafe: the kernel will remove the module
1608 without waiting for anyone to stop using it (using the -f option to
1609 rmmod). This is mainly for kernel developers and desperate users.
1613 bool "Module versioning support"
1615 Usually, you have to use modules compiled with your kernel.
1616 Saying Y here makes it sometimes possible to use modules
1617 compiled for different kernels, by adding enough information
1618 to the modules to (hopefully) spot any changes which would
1619 make them incompatible with the kernel you are running. If
1622 config MODULE_SRCVERSION_ALL
1623 bool "Source checksum for all modules"
1625 Modules which contain a MODULE_VERSION get an extra "srcversion"
1626 field inserted into their modinfo section, which contains a
1627 sum of the source files which made it. This helps maintainers
1628 see exactly which source was used to build a module (since
1629 others sometimes change the module source without updating
1630 the version). With this option, such a "srcversion" field
1631 will be created for all modules. If unsure, say N.
1635 config INIT_ALL_POSSIBLE
1638 Back when each arch used to define their own cpu_online_mask and
1639 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
1640 with all 1s, and others with all 0s. When they were centralised,
1641 it was better to provide this option than to break all the archs
1642 and have several arch maintainers pursuing me down dark alleys.
1647 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1649 Need stop_machine() primitive.
1651 source "block/Kconfig"
1653 config PREEMPT_NOTIFIERS
1660 source "kernel/Kconfig.locks"
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