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
44 depends on BROKEN || !SMP
47 config INIT_ENV_ARG_LIMIT
52 Maximum of each of the number of arguments and environment
53 variables passed to init from the kernel command line.
57 string "Cross-compiler tool prefix"
59 Same as running 'make CROSS_COMPILE=prefix-' but stored for
60 default make runs in this kernel build directory. You don't
61 need to set this unless you want the configured kernel build
62 directory to select the cross-compiler automatically.
65 string "Local version - append to kernel release"
67 Append an extra string to the end of your kernel version.
68 This will show up when you type uname, for example.
69 The string you set here will be appended after the contents of
70 any files with a filename matching localversion* in your
71 object and source tree, in that order. Your total string can
72 be a maximum of 64 characters.
74 config LOCALVERSION_AUTO
75 bool "Automatically append version information to the version string"
78 This will try to automatically determine if the current tree is a
79 release tree by looking for git tags that belong to the current
82 A string of the format -gxxxxxxxx will be added to the localversion
83 if a git-based tree is found. The string generated by this will be
84 appended after any matching localversion* files, and after the value
85 set in CONFIG_LOCALVERSION.
87 (The actual string used here is the first eight characters produced
88 by running the command:
90 $ git rev-parse --verify HEAD
92 which is done within the script "scripts/setlocalversion".)
94 config HAVE_KERNEL_GZIP
97 config HAVE_KERNEL_BZIP2
100 config HAVE_KERNEL_LZMA
103 config HAVE_KERNEL_XZ
106 config HAVE_KERNEL_LZO
110 prompt "Kernel compression mode"
112 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
114 The linux kernel is a kind of self-extracting executable.
115 Several compression algorithms are available, which differ
116 in efficiency, compression and decompression speed.
117 Compression speed is only relevant when building a kernel.
118 Decompression speed is relevant at each boot.
120 If you have any problems with bzip2 or lzma compressed
121 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
122 version of this functionality (bzip2 only), for 2.4, was
123 supplied by Christian Ludwig)
125 High compression options are mostly useful for users, who
126 are low on disk space (embedded systems), but for whom ram
129 If in doubt, select 'gzip'
133 depends on HAVE_KERNEL_GZIP
135 The old and tried gzip compression. It provides a good balance
136 between compression ratio and decompression speed.
140 depends on HAVE_KERNEL_BZIP2
142 Its compression ratio and speed is intermediate.
143 Decompression speed is slowest among the choices. The kernel
144 size is about 10% smaller with bzip2, in comparison to gzip.
145 Bzip2 uses a large amount of memory. For modern kernels you
146 will need at least 8MB RAM or more for booting.
150 depends on HAVE_KERNEL_LZMA
152 This compression algorithm's ratio is best. Decompression speed
153 is between gzip and bzip2. Compression is slowest.
154 The kernel size is about 33% smaller with LZMA in comparison to gzip.
158 depends on HAVE_KERNEL_XZ
160 XZ uses the LZMA2 algorithm and instruction set specific
161 BCJ filters which can improve compression ratio of executable
162 code. The size of the kernel is about 30% smaller with XZ in
163 comparison to gzip. On architectures for which there is a BCJ
164 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
165 will create a few percent smaller kernel than plain LZMA.
167 The speed is about the same as with LZMA: The decompression
168 speed of XZ is better than that of bzip2 but worse than gzip
169 and LZO. Compression is slow.
173 depends on HAVE_KERNEL_LZO
175 Its compression ratio is the poorest among the choices. The kernel
176 size is about 10% bigger than gzip; however its speed
177 (both compression and decompression) is the fastest.
181 config DEFAULT_HOSTNAME
182 string "Default hostname"
185 This option determines the default system hostname before userspace
186 calls sethostname(2). The kernel traditionally uses "(none)" here,
187 but you may wish to use a different default here to make a minimal
188 system more usable with less configuration.
191 bool "Support for paging of anonymous memory (swap)"
192 depends on MMU && BLOCK
195 This option allows you to choose whether you want to have support
196 for so called swap devices or swap files in your kernel that are
197 used to provide more virtual memory than the actual RAM present
198 in your computer. If unsure say Y.
203 Inter Process Communication is a suite of library functions and
204 system calls which let processes (running programs) synchronize and
205 exchange information. It is generally considered to be a good thing,
206 and some programs won't run unless you say Y here. In particular, if
207 you want to run the DOS emulator dosemu under Linux (read the
208 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
209 you'll need to say Y here.
211 You can find documentation about IPC with "info ipc" and also in
212 section 6.4 of the Linux Programmer's Guide, available from
213 <http://www.tldp.org/guides.html>.
215 config SYSVIPC_SYSCTL
222 bool "POSIX Message Queues"
225 POSIX variant of message queues is a part of IPC. In POSIX message
226 queues every message has a priority which decides about succession
227 of receiving it by a process. If you want to compile and run
228 programs written e.g. for Solaris with use of its POSIX message
229 queues (functions mq_*) say Y here.
231 POSIX message queues are visible as a filesystem called 'mqueue'
232 and can be mounted somewhere if you want to do filesystem
233 operations on message queues.
237 config POSIX_MQUEUE_SYSCTL
239 depends on POSIX_MQUEUE
244 bool "open by fhandle syscalls"
247 If you say Y here, a user level program will be able to map
248 file names to handle and then later use the handle for
249 different file system operations. This is useful in implementing
250 userspace file servers, which now track files using handles instead
251 of names. The handle would remain the same even if file names
252 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
256 bool "Auditing support"
259 Enable auditing infrastructure that can be used with another
260 kernel subsystem, such as SELinux (which requires this for
261 logging of avc messages output). Does not do system-call
262 auditing without CONFIG_AUDITSYSCALL.
265 bool "Enable system-call auditing support"
266 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || (ARM && AEABI && !OABI_COMPAT))
267 default y if SECURITY_SELINUX
269 Enable low-overhead system-call auditing infrastructure that
270 can be used independently or with another kernel subsystem,
275 depends on AUDITSYSCALL
280 depends on AUDITSYSCALL
283 config AUDIT_LOGINUID_IMMUTABLE
284 bool "Make audit loginuid immutable"
287 The config option toggles if a task setting its loginuid requires
288 CAP_SYS_AUDITCONTROL or if that task should require no special permissions
289 but should instead only allow setting its loginuid if it was never
290 previously set. On systems which use systemd or a similar central
291 process to restart login services this should be set to true. On older
292 systems in which an admin would typically have to directly stop and
293 start processes this should be set to false. Setting this to true allows
294 one to drop potentially dangerous capabilites from the login tasks,
295 but may not be backwards compatible with older init systems.
297 source "kernel/irq/Kconfig"
298 source "kernel/time/Kconfig"
300 menu "CPU/Task time and stats accounting"
303 prompt "Cputime accounting"
304 default TICK_CPU_ACCOUNTING if !PPC64
305 default VIRT_CPU_ACCOUNTING if PPC64
307 # Kind of a stub config for the pure tick based cputime accounting
308 config TICK_CPU_ACCOUNTING
309 bool "Simple tick based cputime accounting"
312 This is the basic tick based cputime accounting that maintains
313 statistics about user, system and idle time spent on per jiffies
318 config VIRT_CPU_ACCOUNTING
319 bool "Deterministic task and CPU time accounting"
320 depends on HAVE_VIRT_CPU_ACCOUNTING
322 Select this option to enable more accurate task and CPU time
323 accounting. This is done by reading a CPU counter on each
324 kernel entry and exit and on transitions within the kernel
325 between system, softirq and hardirq state, so there is a
326 small performance impact. In the case of s390 or IBM POWER > 5,
327 this also enables accounting of stolen time on logically-partitioned
330 config IRQ_TIME_ACCOUNTING
331 bool "Fine granularity task level IRQ time accounting"
332 depends on HAVE_IRQ_TIME_ACCOUNTING
334 Select this option to enable fine granularity task irq time
335 accounting. This is done by reading a timestamp on each
336 transitions between softirq and hardirq state, so there can be a
337 small performance impact.
339 If in doubt, say N here.
343 config BSD_PROCESS_ACCT
344 bool "BSD Process Accounting"
346 If you say Y here, a user level program will be able to instruct the
347 kernel (via a special system call) to write process accounting
348 information to a file: whenever a process exits, information about
349 that process will be appended to the file by the kernel. The
350 information includes things such as creation time, owning user,
351 command name, memory usage, controlling terminal etc. (the complete
352 list is in the struct acct in <file:include/linux/acct.h>). It is
353 up to the user level program to do useful things with this
354 information. This is generally a good idea, so say Y.
356 config BSD_PROCESS_ACCT_V3
357 bool "BSD Process Accounting version 3 file format"
358 depends on BSD_PROCESS_ACCT
361 If you say Y here, the process accounting information is written
362 in a new file format that also logs the process IDs of each
363 process and it's parent. Note that this file format is incompatible
364 with previous v0/v1/v2 file formats, so you will need updated tools
365 for processing it. A preliminary version of these tools is available
366 at <http://www.gnu.org/software/acct/>.
369 bool "Export task/process statistics through netlink"
373 Export selected statistics for tasks/processes through the
374 generic netlink interface. Unlike BSD process accounting, the
375 statistics are available during the lifetime of tasks/processes as
376 responses to commands. Like BSD accounting, they are sent to user
381 config TASK_DELAY_ACCT
382 bool "Enable per-task delay accounting"
385 Collect information on time spent by a task waiting for system
386 resources like cpu, synchronous block I/O completion and swapping
387 in pages. Such statistics can help in setting a task's priorities
388 relative to other tasks for cpu, io, rss limits etc.
393 bool "Enable extended accounting over taskstats"
396 Collect extended task accounting data and send the data
397 to userland for processing over the taskstats interface.
401 config TASK_IO_ACCOUNTING
402 bool "Enable per-task storage I/O accounting"
403 depends on TASK_XACCT
405 Collect information on the number of bytes of storage I/O which this
410 endmenu # "CPU/Task time and stats accounting"
415 prompt "RCU Implementation"
419 bool "Tree-based hierarchical RCU"
420 depends on !PREEMPT && SMP
422 This option selects the RCU implementation that is
423 designed for very large SMP system with hundreds or
424 thousands of CPUs. It also scales down nicely to
427 config TREE_PREEMPT_RCU
428 bool "Preemptible tree-based hierarchical RCU"
429 depends on PREEMPT && SMP
431 This option selects the RCU implementation that is
432 designed for very large SMP systems with hundreds or
433 thousands of CPUs, but for which real-time response
434 is also required. It also scales down nicely to
438 bool "UP-only small-memory-footprint RCU"
439 depends on !PREEMPT && !SMP
441 This option selects the RCU implementation that is
442 designed for UP systems from which real-time response
443 is not required. This option greatly reduces the
444 memory footprint of RCU.
446 config TINY_PREEMPT_RCU
447 bool "Preemptible UP-only small-memory-footprint RCU"
448 depends on PREEMPT && !SMP
450 This option selects the RCU implementation that is designed
451 for real-time UP systems. This option greatly reduces the
452 memory footprint of RCU.
457 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
459 This option enables preemptible-RCU code that is common between
460 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
462 config CONTEXT_TRACKING
466 bool "Consider userspace as in RCU extended quiescent state"
467 depends on HAVE_CONTEXT_TRACKING && SMP
468 select CONTEXT_TRACKING
470 This option sets hooks on kernel / userspace boundaries and
471 puts RCU in extended quiescent state when the CPU runs in
472 userspace. It means that when a CPU runs in userspace, it is
473 excluded from the global RCU state machine and thus doesn't
474 try to keep the timer tick on for RCU.
476 Unless you want to hack and help the development of the full
477 dynticks mode, you shouldn't enable this option. It also
478 adds unnecessary overhead.
482 config CONTEXT_TRACKING_FORCE
483 bool "Force context tracking"
484 depends on CONTEXT_TRACKING
486 Probe on user/kernel boundaries by default in order to
487 test the features that rely on it such as userspace RCU extended
489 This test is there for debugging until we have a real user like the
493 int "Tree-based hierarchical RCU fanout value"
496 depends on TREE_RCU || TREE_PREEMPT_RCU
500 This option controls the fanout of hierarchical implementations
501 of RCU, allowing RCU to work efficiently on machines with
502 large numbers of CPUs. This value must be at least the fourth
503 root of NR_CPUS, which allows NR_CPUS to be insanely large.
504 The default value of RCU_FANOUT should be used for production
505 systems, but if you are stress-testing the RCU implementation
506 itself, small RCU_FANOUT values allow you to test large-system
507 code paths on small(er) systems.
509 Select a specific number if testing RCU itself.
510 Take the default if unsure.
512 config RCU_FANOUT_LEAF
513 int "Tree-based hierarchical RCU leaf-level fanout value"
514 range 2 RCU_FANOUT if 64BIT
515 range 2 RCU_FANOUT if !64BIT
516 depends on TREE_RCU || TREE_PREEMPT_RCU
519 This option controls the leaf-level fanout of hierarchical
520 implementations of RCU, and allows trading off cache misses
521 against lock contention. Systems that synchronize their
522 scheduling-clock interrupts for energy-efficiency reasons will
523 want the default because the smaller leaf-level fanout keeps
524 lock contention levels acceptably low. Very large systems
525 (hundreds or thousands of CPUs) will instead want to set this
526 value to the maximum value possible in order to reduce the
527 number of cache misses incurred during RCU's grace-period
528 initialization. These systems tend to run CPU-bound, and thus
529 are not helped by synchronized interrupts, and thus tend to
530 skew them, which reduces lock contention enough that large
531 leaf-level fanouts work well.
533 Select a specific number if testing RCU itself.
535 Select the maximum permissible value for large systems.
537 Take the default if unsure.
539 config RCU_FANOUT_EXACT
540 bool "Disable tree-based hierarchical RCU auto-balancing"
541 depends on TREE_RCU || TREE_PREEMPT_RCU
544 This option forces use of the exact RCU_FANOUT value specified,
545 regardless of imbalances in the hierarchy. This is useful for
546 testing RCU itself, and might one day be useful on systems with
547 strong NUMA behavior.
549 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
553 config RCU_FAST_NO_HZ
554 bool "Accelerate last non-dyntick-idle CPU's grace periods"
555 depends on NO_HZ && SMP
558 This option causes RCU to attempt to accelerate grace periods in
559 order to allow CPUs to enter dynticks-idle state more quickly.
560 On the other hand, this option increases the overhead of the
561 dynticks-idle checking, thus degrading scheduling latency.
563 Say Y if energy efficiency is critically important, and you don't
564 care about real-time response.
566 Say N if you are unsure.
568 config TREE_RCU_TRACE
569 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
572 This option provides tracing for the TREE_RCU and
573 TREE_PREEMPT_RCU implementations, permitting Makefile to
574 trivially select kernel/rcutree_trace.c.
577 bool "Enable RCU priority boosting"
578 depends on RT_MUTEXES && PREEMPT_RCU
581 This option boosts the priority of preempted RCU readers that
582 block the current preemptible RCU grace period for too long.
583 This option also prevents heavy loads from blocking RCU
584 callback invocation for all flavors of RCU.
586 Say Y here if you are working with real-time apps or heavy loads
587 Say N here if you are unsure.
589 config RCU_BOOST_PRIO
590 int "Real-time priority to boost RCU readers to"
595 This option specifies the real-time priority to which long-term
596 preempted RCU readers are to be boosted. If you are working
597 with a real-time application that has one or more CPU-bound
598 threads running at a real-time priority level, you should set
599 RCU_BOOST_PRIO to a priority higher then the highest-priority
600 real-time CPU-bound thread. The default RCU_BOOST_PRIO value
601 of 1 is appropriate in the common case, which is real-time
602 applications that do not have any CPU-bound threads.
604 Some real-time applications might not have a single real-time
605 thread that saturates a given CPU, but instead might have
606 multiple real-time threads that, taken together, fully utilize
607 that CPU. In this case, you should set RCU_BOOST_PRIO to
608 a priority higher than the lowest-priority thread that is
609 conspiring to prevent the CPU from running any non-real-time
610 tasks. For example, if one thread at priority 10 and another
611 thread at priority 5 are between themselves fully consuming
612 the CPU time on a given CPU, then RCU_BOOST_PRIO should be
613 set to priority 6 or higher.
615 Specify the real-time priority, or take the default if unsure.
617 config RCU_BOOST_DELAY
618 int "Milliseconds to delay boosting after RCU grace-period start"
623 This option specifies the time to wait after the beginning of
624 a given grace period before priority-boosting preempted RCU
625 readers blocking that grace period. Note that any RCU reader
626 blocking an expedited RCU grace period is boosted immediately.
628 Accept the default if unsure.
631 bool "Offload RCU callback processing from boot-selected CPUs"
632 depends on TREE_RCU || TREE_PREEMPT_RCU
635 Use this option to reduce OS jitter for aggressive HPC or
636 real-time workloads. It can also be used to offload RCU
637 callback invocation to energy-efficient CPUs in battery-powered
638 asymmetric multiprocessors.
640 This option offloads callback invocation from the set of
641 CPUs specified at boot time by the rcu_nocbs parameter.
642 For each such CPU, a kthread ("rcuoN") will be created to
643 invoke callbacks, where the "N" is the CPU being offloaded.
644 Nothing prevents this kthread from running on the specified
645 CPUs, but (1) the kthreads may be preempted between each
646 callback, and (2) affinity or cgroups can be used to force
647 the kthreads to run on whatever set of CPUs is desired.
649 Say Y here if you want reduced OS jitter on selected CPUs.
650 Say N here if you are unsure.
652 endmenu # "RCU Subsystem"
655 tristate "Kernel .config support"
657 This option enables the complete Linux kernel ".config" file
658 contents to be saved in the kernel. It provides documentation
659 of which kernel options are used in a running kernel or in an
660 on-disk kernel. This information can be extracted from the kernel
661 image file with the script scripts/extract-ikconfig and used as
662 input to rebuild the current kernel or to build another kernel.
663 It can also be extracted from a running kernel by reading
664 /proc/config.gz if enabled (below).
667 bool "Enable access to .config through /proc/config.gz"
668 depends on IKCONFIG && PROC_FS
670 This option enables access to the kernel configuration file
671 through /proc/config.gz.
674 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
678 Select kernel log buffer size as a power of 2.
688 # Architectures with an unreliable sched_clock() should select this:
690 config HAVE_UNSTABLE_SCHED_CLOCK
694 # For architectures that want to enable the support for NUMA-affine scheduler
697 config ARCH_SUPPORTS_NUMA_BALANCING
700 # For architectures that (ab)use NUMA to represent different memory regions
701 # all cpu-local but of different latencies, such as SuperH.
703 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
707 # For architectures that are willing to define _PAGE_NUMA as _PAGE_PROTNONE
708 config ARCH_WANTS_PROT_NUMA_PROT_NONE
711 config ARCH_USES_NUMA_PROT_NONE
714 depends on ARCH_WANTS_PROT_NUMA_PROT_NONE
715 depends on NUMA_BALANCING
717 config NUMA_BALANCING_DEFAULT_ENABLED
718 bool "Automatically enable NUMA aware memory/task placement"
720 depends on NUMA_BALANCING
722 If set, autonumic NUMA balancing will be enabled if running on a NUMA
725 config NUMA_BALANCING
726 bool "Memory placement aware NUMA scheduler"
727 depends on ARCH_SUPPORTS_NUMA_BALANCING
728 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
729 depends on SMP && NUMA && MIGRATION
731 This option adds support for automatic NUMA aware memory/task placement.
732 The mechanism is quite primitive and is based on migrating memory when
733 it is references to the node the task is running on.
735 This system will be inactive on UMA systems.
738 boolean "Control Group support"
741 This option adds support for grouping sets of processes together, for
742 use with process control subsystems such as Cpusets, CFS, memory
743 controls or device isolation.
745 - Documentation/scheduler/sched-design-CFS.txt (CFS)
746 - Documentation/cgroups/ (features for grouping, isolation
747 and resource control)
754 bool "Example debug cgroup subsystem"
757 This option enables a simple cgroup subsystem that
758 exports useful debugging information about the cgroups
763 config CGROUP_FREEZER
764 bool "Freezer cgroup subsystem"
766 Provides a way to freeze and unfreeze all tasks in a
770 bool "Device controller for cgroups"
772 Provides a cgroup implementing whitelists for devices which
773 a process in the cgroup can mknod or open.
776 bool "Cpuset support"
778 This option will let you create and manage CPUSETs which
779 allow dynamically partitioning a system into sets of CPUs and
780 Memory Nodes and assigning tasks to run only within those sets.
781 This is primarily useful on large SMP or NUMA systems.
785 config PROC_PID_CPUSET
786 bool "Include legacy /proc/<pid>/cpuset file"
790 config CGROUP_CPUACCT
791 bool "Simple CPU accounting cgroup subsystem"
793 Provides a simple Resource Controller for monitoring the
794 total CPU consumed by the tasks in a cgroup.
796 config RESOURCE_COUNTERS
797 bool "Resource counters"
799 This option enables controller independent resource accounting
800 infrastructure that works with cgroups.
803 bool "Memory Resource Controller for Control Groups"
804 depends on RESOURCE_COUNTERS
807 Provides a memory resource controller that manages both anonymous
808 memory and page cache. (See Documentation/cgroups/memory.txt)
810 Note that setting this option increases fixed memory overhead
811 associated with each page of memory in the system. By this,
812 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
813 usage tracking struct at boot. Total amount of this is printed out
816 Only enable when you're ok with these trade offs and really
817 sure you need the memory resource controller. Even when you enable
818 this, you can set "cgroup_disable=memory" at your boot option to
819 disable memory resource controller and you can avoid overheads.
820 (and lose benefits of memory resource controller)
822 This config option also selects MM_OWNER config option, which
823 could in turn add some fork/exit overhead.
826 bool "Memory Resource Controller Swap Extension"
827 depends on MEMCG && SWAP
829 Add swap management feature to memory resource controller. When you
830 enable this, you can limit mem+swap usage per cgroup. In other words,
831 when you disable this, memory resource controller has no cares to
832 usage of swap...a process can exhaust all of the swap. This extension
833 is useful when you want to avoid exhaustion swap but this itself
834 adds more overheads and consumes memory for remembering information.
835 Especially if you use 32bit system or small memory system, please
836 be careful about enabling this. When memory resource controller
837 is disabled by boot option, this will be automatically disabled and
838 there will be no overhead from this. Even when you set this config=y,
839 if boot option "swapaccount=0" is set, swap will not be accounted.
840 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
841 size is 4096bytes, 512k per 1Gbytes of swap.
842 config MEMCG_SWAP_ENABLED
843 bool "Memory Resource Controller Swap Extension enabled by default"
844 depends on MEMCG_SWAP
847 Memory Resource Controller Swap Extension comes with its price in
848 a bigger memory consumption. General purpose distribution kernels
849 which want to enable the feature but keep it disabled by default
850 and let the user enable it by swapaccount boot command line
851 parameter should have this option unselected.
852 For those who want to have the feature enabled by default should
853 select this option (if, for some reason, they need to disable it
854 then swapaccount=0 does the trick).
856 bool "Memory Resource Controller Kernel Memory accounting"
858 depends on SLUB || SLAB
860 The Kernel Memory extension for Memory Resource Controller can limit
861 the amount of memory used by kernel objects in the system. Those are
862 fundamentally different from the entities handled by the standard
863 Memory Controller, which are page-based, and can be swapped. Users of
864 the kmem extension can use it to guarantee that no group of processes
865 will ever exhaust kernel resources alone.
867 config CGROUP_HUGETLB
868 bool "HugeTLB Resource Controller for Control Groups"
869 depends on RESOURCE_COUNTERS && HUGETLB_PAGE
872 Provides a cgroup Resource Controller for HugeTLB pages.
873 When you enable this, you can put a per cgroup limit on HugeTLB usage.
874 The limit is enforced during page fault. Since HugeTLB doesn't
875 support page reclaim, enforcing the limit at page fault time implies
876 that, the application will get SIGBUS signal if it tries to access
877 HugeTLB pages beyond its limit. This requires the application to know
878 beforehand how much HugeTLB pages it would require for its use. The
879 control group is tracked in the third page lru pointer. This means
880 that we cannot use the controller with huge page less than 3 pages.
883 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
884 depends on PERF_EVENTS && CGROUPS
886 This option extends the per-cpu mode to restrict monitoring to
887 threads which belong to the cgroup specified and run on the
892 menuconfig CGROUP_SCHED
893 bool "Group CPU scheduler"
896 This feature lets CPU scheduler recognize task groups and control CPU
897 bandwidth allocation to such task groups. It uses cgroups to group
901 config FAIR_GROUP_SCHED
902 bool "Group scheduling for SCHED_OTHER"
903 depends on CGROUP_SCHED
907 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
908 depends on FAIR_GROUP_SCHED
911 This option allows users to define CPU bandwidth rates (limits) for
912 tasks running within the fair group scheduler. Groups with no limit
913 set are considered to be unconstrained and will run with no
915 See tip/Documentation/scheduler/sched-bwc.txt for more information.
917 config RT_GROUP_SCHED
918 bool "Group scheduling for SCHED_RR/FIFO"
919 depends on CGROUP_SCHED
922 This feature lets you explicitly allocate real CPU bandwidth
923 to task groups. If enabled, it will also make it impossible to
924 schedule realtime tasks for non-root users until you allocate
925 realtime bandwidth for them.
926 See Documentation/scheduler/sched-rt-group.txt for more information.
931 bool "Block IO controller"
935 Generic block IO controller cgroup interface. This is the common
936 cgroup interface which should be used by various IO controlling
939 Currently, CFQ IO scheduler uses it to recognize task groups and
940 control disk bandwidth allocation (proportional time slice allocation)
941 to such task groups. It is also used by bio throttling logic in
942 block layer to implement upper limit in IO rates on a device.
944 This option only enables generic Block IO controller infrastructure.
945 One needs to also enable actual IO controlling logic/policy. For
946 enabling proportional weight division of disk bandwidth in CFQ, set
947 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
948 CONFIG_BLK_DEV_THROTTLING=y.
950 See Documentation/cgroups/blkio-controller.txt for more information.
952 config DEBUG_BLK_CGROUP
953 bool "Enable Block IO controller debugging"
954 depends on BLK_CGROUP
957 Enable some debugging help. Currently it exports additional stat
958 files in a cgroup which can be useful for debugging.
962 config CHECKPOINT_RESTORE
963 bool "Checkpoint/restore support" if EXPERT
966 Enables additional kernel features in a sake of checkpoint/restore.
967 In particular it adds auxiliary prctl codes to setup process text,
968 data and heap segment sizes, and a few additional /proc filesystem
971 If unsure, say N here.
973 menuconfig NAMESPACES
974 bool "Namespaces support" if EXPERT
977 Provides the way to make tasks work with different objects using
978 the same id. For example same IPC id may refer to different objects
979 or same user id or pid may refer to different tasks when used in
980 different namespaces.
988 In this namespace tasks see different info provided with the
993 depends on (SYSVIPC || POSIX_MQUEUE)
996 In this namespace tasks work with IPC ids which correspond to
997 different IPC objects in different namespaces.
1000 bool "User namespace"
1001 depends on UIDGID_CONVERTED
1002 select UIDGID_STRICT_TYPE_CHECKS
1006 This allows containers, i.e. vservers, to use user namespaces
1007 to provide different user info for different servers.
1011 bool "PID Namespaces"
1014 Support process id namespaces. This allows having multiple
1015 processes with the same pid as long as they are in different
1016 pid namespaces. This is a building block of containers.
1019 bool "Network namespace"
1023 Allow user space to create what appear to be multiple instances
1024 of the network stack.
1028 config UIDGID_CONVERTED
1029 # True if all of the selected software conmponents are known
1030 # to have uid_t and gid_t converted to kuid_t and kgid_t
1031 # where appropriate and are otherwise safe to use with
1032 # the user namespace.
1037 depends on NET_9P = n
1040 depends on 9P_FS = n
1041 depends on AFS_FS = n
1042 depends on CEPH_FS = n
1044 depends on CODA_FS = n
1045 depends on GFS2_FS = n
1046 depends on NCP_FS = n
1048 depends on NFS_FS = n
1049 depends on OCFS2_FS = n
1050 depends on XFS_FS = n
1052 config UIDGID_STRICT_TYPE_CHECKS
1053 bool "Require conversions between uid/gids and their internal representation"
1054 depends on UIDGID_CONVERTED
1057 While the nececessary conversions are being added to all subsystems this option allows
1058 the code to continue to build for unconverted subsystems.
1060 Say Y here if you want the strict type checking enabled
1062 config SCHED_AUTOGROUP
1063 bool "Automatic process group scheduling"
1067 select FAIR_GROUP_SCHED
1069 This option optimizes the scheduler for common desktop workloads by
1070 automatically creating and populating task groups. This separation
1071 of workloads isolates aggressive CPU burners (like build jobs) from
1072 desktop applications. Task group autogeneration is currently based
1078 config SYSFS_DEPRECATED
1079 bool "Enable deprecated sysfs features to support old userspace tools"
1083 This option adds code that switches the layout of the "block" class
1084 devices, to not show up in /sys/class/block/, but only in
1087 This switch is only active when the sysfs.deprecated=1 boot option is
1088 passed or the SYSFS_DEPRECATED_V2 option is set.
1090 This option allows new kernels to run on old distributions and tools,
1091 which might get confused by /sys/class/block/. Since 2007/2008 all
1092 major distributions and tools handle this just fine.
1094 Recent distributions and userspace tools after 2009/2010 depend on
1095 the existence of /sys/class/block/, and will not work with this
1098 Only if you are using a new kernel on an old distribution, you might
1101 config SYSFS_DEPRECATED_V2
1102 bool "Enable deprecated sysfs features by default"
1105 depends on SYSFS_DEPRECATED
1107 Enable deprecated sysfs by default.
1109 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1112 Only if you are using a new kernel on an old distribution, you might
1113 need to say Y here. Even then, odds are you would not need it
1114 enabled, you can always pass the boot option if absolutely necessary.
1117 bool "Kernel->user space relay support (formerly relayfs)"
1119 This option enables support for relay interface support in
1120 certain file systems (such as debugfs).
1121 It is designed to provide an efficient mechanism for tools and
1122 facilities to relay large amounts of data from kernel space to
1127 config BLK_DEV_INITRD
1128 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1129 depends on BROKEN || !FRV
1131 The initial RAM filesystem is a ramfs which is loaded by the
1132 boot loader (loadlin or lilo) and that is mounted as root
1133 before the normal boot procedure. It is typically used to
1134 load modules needed to mount the "real" root file system,
1135 etc. See <file:Documentation/initrd.txt> for details.
1137 If RAM disk support (BLK_DEV_RAM) is also included, this
1138 also enables initial RAM disk (initrd) support and adds
1139 15 Kbytes (more on some other architectures) to the kernel size.
1145 source "usr/Kconfig"
1149 config CC_OPTIMIZE_FOR_SIZE
1150 bool "Optimize for size"
1152 Enabling this option will pass "-Os" instead of "-O2" to gcc
1153 resulting in a smaller kernel.
1164 bool "Configure standard kernel features (expert users)"
1165 # Unhide debug options, to make the on-by-default options visible
1168 This option allows certain base kernel options and settings
1169 to be disabled or tweaked. This is for specialized
1170 environments which can tolerate a "non-standard" kernel.
1171 Only use this if you really know what you are doing.
1177 bool "Enable 16-bit UID system calls" if EXPERT
1178 depends on HAVE_UID16
1181 This enables the legacy 16-bit UID syscall wrappers.
1183 config SYSCTL_SYSCALL
1184 bool "Sysctl syscall support" if EXPERT
1185 depends on PROC_SYSCTL
1189 sys_sysctl uses binary paths that have been found challenging
1190 to properly maintain and use. The interface in /proc/sys
1191 using paths with ascii names is now the primary path to this
1194 Almost nothing using the binary sysctl interface so if you are
1195 trying to save some space it is probably safe to disable this,
1196 making your kernel marginally smaller.
1198 If unsure say N here.
1200 config SYSCTL_EXCEPTION_TRACE
1203 Enable support for /proc/sys/debug/exception-trace.
1206 bool "Load all symbols for debugging/ksymoops" if EXPERT
1209 Say Y here to let the kernel print out symbolic crash information and
1210 symbolic stack backtraces. This increases the size of the kernel
1211 somewhat, as all symbols have to be loaded into the kernel image.
1214 bool "Include all symbols in kallsyms"
1215 depends on DEBUG_KERNEL && KALLSYMS
1217 Normally kallsyms only contains the symbols of functions for nicer
1218 OOPS messages and backtraces (i.e., symbols from the text and inittext
1219 sections). This is sufficient for most cases. And only in very rare
1220 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1221 names of variables from the data sections, etc).
1223 This option makes sure that all symbols are loaded into the kernel
1224 image (i.e., symbols from all sections) in cost of increased kernel
1225 size (depending on the kernel configuration, it may be 300KiB or
1226 something like this).
1228 Say N unless you really need all symbols.
1235 bool "Enable support for printk" if EXPERT
1237 This option enables normal printk support. Removing it
1238 eliminates most of the message strings from the kernel image
1239 and makes the kernel more or less silent. As this makes it
1240 very difficult to diagnose system problems, saying N here is
1241 strongly discouraged.
1244 bool "BUG() support" if EXPERT
1247 Disabling this option eliminates support for BUG and WARN, reducing
1248 the size of your kernel image and potentially quietly ignoring
1249 numerous fatal conditions. You should only consider disabling this
1250 option for embedded systems with no facilities for reporting errors.
1256 bool "Enable ELF core dumps" if EXPERT
1258 Enable support for generating core dumps. Disabling saves about 4k.
1261 config PCSPKR_PLATFORM
1262 bool "Enable PC-Speaker support" if EXPERT
1263 depends on HAVE_PCSPKR_PLATFORM
1267 This option allows to disable the internal PC-Speaker
1268 support, saving some memory.
1270 config HAVE_PCSPKR_PLATFORM
1275 bool "Enable full-sized data structures for core" if EXPERT
1277 Disabling this option reduces the size of miscellaneous core
1278 kernel data structures. This saves memory on small machines,
1279 but may reduce performance.
1282 bool "Enable futex support" if EXPERT
1286 Disabling this option will cause the kernel to be built without
1287 support for "fast userspace mutexes". The resulting kernel may not
1288 run glibc-based applications correctly.
1291 bool "Enable eventpoll support" if EXPERT
1295 Disabling this option will cause the kernel to be built without
1296 support for epoll family of system calls.
1299 bool "Enable signalfd() system call" if EXPERT
1303 Enable the signalfd() system call that allows to receive signals
1304 on a file descriptor.
1309 bool "Enable timerfd() system call" if EXPERT
1313 Enable the timerfd() system call that allows to receive timer
1314 events on a file descriptor.
1319 bool "Enable eventfd() system call" if EXPERT
1323 Enable the eventfd() system call that allows to receive both
1324 kernel notification (ie. KAIO) or userspace notifications.
1329 bool "Use full shmem filesystem" if EXPERT
1333 The shmem is an internal filesystem used to manage shared memory.
1334 It is backed by swap and manages resource limits. It is also exported
1335 to userspace as tmpfs if TMPFS is enabled. Disabling this
1336 option replaces shmem and tmpfs with the much simpler ramfs code,
1337 which may be appropriate on small systems without swap.
1340 bool "Enable AIO support" if EXPERT
1343 This option enables POSIX asynchronous I/O which may by used
1344 by some high performance threaded applications. Disabling
1345 this option saves about 7k.
1348 bool "Embedded system"
1351 This option should be enabled if compiling the kernel for
1352 an embedded system so certain expert options are available
1355 config HAVE_PERF_EVENTS
1358 See tools/perf/design.txt for details.
1360 config PERF_USE_VMALLOC
1363 See tools/perf/design.txt for details
1365 menu "Kernel Performance Events And Counters"
1368 bool "Kernel performance events and counters"
1369 default y if PROFILING
1370 depends on HAVE_PERF_EVENTS
1374 Enable kernel support for various performance events provided
1375 by software and hardware.
1377 Software events are supported either built-in or via the
1378 use of generic tracepoints.
1380 Most modern CPUs support performance events via performance
1381 counter registers. These registers count the number of certain
1382 types of hw events: such as instructions executed, cachemisses
1383 suffered, or branches mis-predicted - without slowing down the
1384 kernel or applications. These registers can also trigger interrupts
1385 when a threshold number of events have passed - and can thus be
1386 used to profile the code that runs on that CPU.
1388 The Linux Performance Event subsystem provides an abstraction of
1389 these software and hardware event capabilities, available via a
1390 system call and used by the "perf" utility in tools/perf/. It
1391 provides per task and per CPU counters, and it provides event
1392 capabilities on top of those.
1396 config DEBUG_PERF_USE_VMALLOC
1398 bool "Debug: use vmalloc to back perf mmap() buffers"
1399 depends on PERF_EVENTS && DEBUG_KERNEL
1400 select PERF_USE_VMALLOC
1402 Use vmalloc memory to back perf mmap() buffers.
1404 Mostly useful for debugging the vmalloc code on platforms
1405 that don't require it.
1411 config VM_EVENT_COUNTERS
1413 bool "Enable VM event counters for /proc/vmstat" if EXPERT
1415 VM event counters are needed for event counts to be shown.
1416 This option allows the disabling of the VM event counters
1417 on EXPERT systems. /proc/vmstat will only show page counts
1418 if VM event counters are disabled.
1422 bool "Enable PCI quirk workarounds" if EXPERT
1425 This enables workarounds for various PCI chipset
1426 bugs/quirks. Disable this only if your target machine is
1427 unaffected by PCI quirks.
1431 bool "Enable SLUB debugging support" if EXPERT
1432 depends on SLUB && SYSFS
1434 SLUB has extensive debug support features. Disabling these can
1435 result in significant savings in code size. This also disables
1436 SLUB sysfs support. /sys/slab will not exist and there will be
1437 no support for cache validation etc.
1440 bool "Disable heap randomization"
1443 Randomizing heap placement makes heap exploits harder, but it
1444 also breaks ancient binaries (including anything libc5 based).
1445 This option changes the bootup default to heap randomization
1446 disabled, and can be overridden at runtime by setting
1447 /proc/sys/kernel/randomize_va_space to 2.
1449 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1452 prompt "Choose SLAB allocator"
1455 This option allows to select a slab allocator.
1460 The regular slab allocator that is established and known to work
1461 well in all environments. It organizes cache hot objects in
1462 per cpu and per node queues.
1465 bool "SLUB (Unqueued Allocator)"
1467 SLUB is a slab allocator that minimizes cache line usage
1468 instead of managing queues of cached objects (SLAB approach).
1469 Per cpu caching is realized using slabs of objects instead
1470 of queues of objects. SLUB can use memory efficiently
1471 and has enhanced diagnostics. SLUB is the default choice for
1476 bool "SLOB (Simple Allocator)"
1478 SLOB replaces the stock allocator with a drastically simpler
1479 allocator. SLOB is generally more space efficient but
1480 does not perform as well on large systems.
1484 config MMAP_ALLOW_UNINITIALIZED
1485 bool "Allow mmapped anonymous memory to be uninitialized"
1486 depends on EXPERT && !MMU
1489 Normally, and according to the Linux spec, anonymous memory obtained
1490 from mmap() has it's contents cleared before it is passed to
1491 userspace. Enabling this config option allows you to request that
1492 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1493 providing a huge performance boost. If this option is not enabled,
1494 then the flag will be ignored.
1496 This is taken advantage of by uClibc's malloc(), and also by
1497 ELF-FDPIC binfmt's brk and stack allocator.
1499 Because of the obvious security issues, this option should only be
1500 enabled on embedded devices where you control what is run in
1501 userspace. Since that isn't generally a problem on no-MMU systems,
1502 it is normally safe to say Y here.
1504 See Documentation/nommu-mmap.txt for more information.
1507 bool "Profiling support"
1509 Say Y here to enable the extended profiling support mechanisms used
1510 by profilers such as OProfile.
1513 # Place an empty function call at each tracepoint site. Can be
1514 # dynamically changed for a probe function.
1519 source "arch/Kconfig"
1521 endmenu # General setup
1523 config HAVE_GENERIC_DMA_COHERENT
1530 depends on SLAB || SLUB_DEBUG
1538 default 0 if BASE_FULL
1539 default 1 if !BASE_FULL
1542 bool "Enable loadable module support"
1544 Kernel modules are small pieces of compiled code which can
1545 be inserted in the running kernel, rather than being
1546 permanently built into the kernel. You use the "modprobe"
1547 tool to add (and sometimes remove) them. If you say Y here,
1548 many parts of the kernel can be built as modules (by
1549 answering M instead of Y where indicated): this is most
1550 useful for infrequently used options which are not required
1551 for booting. For more information, see the man pages for
1552 modprobe, lsmod, modinfo, insmod and rmmod.
1554 If you say Y here, you will need to run "make
1555 modules_install" to put the modules under /lib/modules/
1556 where modprobe can find them (you may need to be root to do
1563 config MODULE_FORCE_LOAD
1564 bool "Forced module loading"
1567 Allow loading of modules without version information (ie. modprobe
1568 --force). Forced module loading sets the 'F' (forced) taint flag and
1569 is usually a really bad idea.
1571 config MODULE_UNLOAD
1572 bool "Module unloading"
1574 Without this option you will not be able to unload any
1575 modules (note that some modules may not be unloadable
1576 anyway), which makes your kernel smaller, faster
1577 and simpler. If unsure, say Y.
1579 config MODULE_FORCE_UNLOAD
1580 bool "Forced module unloading"
1581 depends on MODULE_UNLOAD
1583 This option allows you to force a module to unload, even if the
1584 kernel believes it is unsafe: the kernel will remove the module
1585 without waiting for anyone to stop using it (using the -f option to
1586 rmmod). This is mainly for kernel developers and desperate users.
1590 bool "Module versioning support"
1592 Usually, you have to use modules compiled with your kernel.
1593 Saying Y here makes it sometimes possible to use modules
1594 compiled for different kernels, by adding enough information
1595 to the modules to (hopefully) spot any changes which would
1596 make them incompatible with the kernel you are running. If
1599 config MODULE_SRCVERSION_ALL
1600 bool "Source checksum for all modules"
1602 Modules which contain a MODULE_VERSION get an extra "srcversion"
1603 field inserted into their modinfo section, which contains a
1604 sum of the source files which made it. This helps maintainers
1605 see exactly which source was used to build a module (since
1606 others sometimes change the module source without updating
1607 the version). With this option, such a "srcversion" field
1608 will be created for all modules. If unsure, say N.
1611 bool "Module signature verification"
1615 select ASYMMETRIC_KEY_TYPE
1616 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1617 select PUBLIC_KEY_ALGO_RSA
1620 select X509_CERTIFICATE_PARSER
1622 Check modules for valid signatures upon load: the signature
1623 is simply appended to the module. For more information see
1624 Documentation/module-signing.txt.
1626 !!!WARNING!!! If you enable this option, you MUST make sure that the
1627 module DOES NOT get stripped after being signed. This includes the
1628 debuginfo strip done by some packagers (such as rpmbuild) and
1629 inclusion into an initramfs that wants the module size reduced.
1631 config MODULE_SIG_FORCE
1632 bool "Require modules to be validly signed"
1633 depends on MODULE_SIG
1635 Reject unsigned modules or signed modules for which we don't have a
1636 key. Without this, such modules will simply taint the kernel.
1639 prompt "Which hash algorithm should modules be signed with?"
1640 depends on MODULE_SIG
1642 This determines which sort of hashing algorithm will be used during
1643 signature generation. This algorithm _must_ be built into the kernel
1644 directly so that signature verification can take place. It is not
1645 possible to load a signed module containing the algorithm to check
1646 the signature on that module.
1648 config MODULE_SIG_SHA1
1649 bool "Sign modules with SHA-1"
1652 config MODULE_SIG_SHA224
1653 bool "Sign modules with SHA-224"
1654 select CRYPTO_SHA256
1656 config MODULE_SIG_SHA256
1657 bool "Sign modules with SHA-256"
1658 select CRYPTO_SHA256
1660 config MODULE_SIG_SHA384
1661 bool "Sign modules with SHA-384"
1662 select CRYPTO_SHA512
1664 config MODULE_SIG_SHA512
1665 bool "Sign modules with SHA-512"
1666 select CRYPTO_SHA512
1672 config INIT_ALL_POSSIBLE
1675 Back when each arch used to define their own cpu_online_mask and
1676 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
1677 with all 1s, and others with all 0s. When they were centralised,
1678 it was better to provide this option than to break all the archs
1679 and have several arch maintainers pursuing me down dark alleys.
1684 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1686 Need stop_machine() primitive.
1688 source "block/Kconfig"
1690 config PREEMPT_NOTIFIERS
1697 # Can be selected by architectures with broken toolchains
1698 # that get confused by correct const<->read_only section
1700 config BROKEN_RODATA
1706 Build a simple ASN.1 grammar compiler that produces a bytecode output
1707 that can be interpreted by the ASN.1 stream decoder and used to
1708 inform it as to what tags are to be expected in a stream and what
1709 functions to call on what tags.
1711 source "kernel/Kconfig.locks"
projects / deliverable / linux.git / blob