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"
26 config BUILDTIME_EXTABLE_SORT
32 bool "Prompt for development and/or incomplete code/drivers"
34 Some of the various things that Linux supports (such as network
35 drivers, file systems, network protocols, etc.) can be in a state
36 of development where the functionality, stability, or the level of
37 testing is not yet high enough for general use. This is usually
38 known as the "alpha-test" phase among developers. If a feature is
39 currently in alpha-test, then the developers usually discourage
40 uninformed widespread use of this feature by the general public to
41 avoid "Why doesn't this work?" type mail messages. However, active
42 testing and use of these systems is welcomed. Just be aware that it
43 may not meet the normal level of reliability or it may fail to work
44 in some special cases. Detailed bug reports from people familiar
45 with the kernel internals are usually welcomed by the developers
46 (before submitting bug reports, please read the documents
47 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
48 <file:Documentation/BUG-HUNTING>, and
49 <file:Documentation/oops-tracing.txt> in the kernel source).
51 This option will also make obsoleted drivers available. These are
52 drivers that have been replaced by something else, and/or are
53 scheduled to be removed in a future kernel release.
55 Unless you intend to help test and develop a feature or driver that
56 falls into this category, or you have a situation that requires
57 using these features, you should probably say N here, which will
58 cause the configurator to present you with fewer choices. If
59 you say Y here, you will be offered the choice of using features or
60 drivers that are currently considered to be in the alpha-test phase.
67 depends on BROKEN || !SMP
70 config INIT_ENV_ARG_LIMIT
75 Maximum of each of the number of arguments and environment
76 variables passed to init from the kernel command line.
80 string "Cross-compiler tool prefix"
82 Same as running 'make CROSS_COMPILE=prefix-' but stored for
83 default make runs in this kernel build directory. You don't
84 need to set this unless you want the configured kernel build
85 directory to select the cross-compiler automatically.
88 string "Local version - append to kernel release"
90 Append an extra string to the end of your kernel version.
91 This will show up when you type uname, for example.
92 The string you set here will be appended after the contents of
93 any files with a filename matching localversion* in your
94 object and source tree, in that order. Your total string can
95 be a maximum of 64 characters.
97 config LOCALVERSION_AUTO
98 bool "Automatically append version information to the version string"
101 This will try to automatically determine if the current tree is a
102 release tree by looking for git tags that belong to the current
103 top of tree revision.
105 A string of the format -gxxxxxxxx will be added to the localversion
106 if a git-based tree is found. The string generated by this will be
107 appended after any matching localversion* files, and after the value
108 set in CONFIG_LOCALVERSION.
110 (The actual string used here is the first eight characters produced
111 by running the command:
113 $ git rev-parse --verify HEAD
115 which is done within the script "scripts/setlocalversion".)
117 config HAVE_KERNEL_GZIP
120 config HAVE_KERNEL_BZIP2
123 config HAVE_KERNEL_LZMA
126 config HAVE_KERNEL_XZ
129 config HAVE_KERNEL_LZO
133 prompt "Kernel compression mode"
135 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
137 The linux kernel is a kind of self-extracting executable.
138 Several compression algorithms are available, which differ
139 in efficiency, compression and decompression speed.
140 Compression speed is only relevant when building a kernel.
141 Decompression speed is relevant at each boot.
143 If you have any problems with bzip2 or lzma compressed
144 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
145 version of this functionality (bzip2 only), for 2.4, was
146 supplied by Christian Ludwig)
148 High compression options are mostly useful for users, who
149 are low on disk space (embedded systems), but for whom ram
152 If in doubt, select 'gzip'
156 depends on HAVE_KERNEL_GZIP
158 The old and tried gzip compression. It provides a good balance
159 between compression ratio and decompression speed.
163 depends on HAVE_KERNEL_BZIP2
165 Its compression ratio and speed is intermediate.
166 Decompression speed is slowest among the choices. The kernel
167 size is about 10% smaller with bzip2, in comparison to gzip.
168 Bzip2 uses a large amount of memory. For modern kernels you
169 will need at least 8MB RAM or more for booting.
173 depends on HAVE_KERNEL_LZMA
175 This compression algorithm's ratio is best. Decompression speed
176 is between gzip and bzip2. Compression is slowest.
177 The kernel size is about 33% smaller with LZMA in comparison to gzip.
181 depends on HAVE_KERNEL_XZ
183 XZ uses the LZMA2 algorithm and instruction set specific
184 BCJ filters which can improve compression ratio of executable
185 code. The size of the kernel is about 30% smaller with XZ in
186 comparison to gzip. On architectures for which there is a BCJ
187 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
188 will create a few percent smaller kernel than plain LZMA.
190 The speed is about the same as with LZMA: The decompression
191 speed of XZ is better than that of bzip2 but worse than gzip
192 and LZO. Compression is slow.
196 depends on HAVE_KERNEL_LZO
198 Its compression ratio is the poorest among the choices. The kernel
199 size is about 10% bigger than gzip; however its speed
200 (both compression and decompression) is the fastest.
204 config DEFAULT_HOSTNAME
205 string "Default hostname"
208 This option determines the default system hostname before userspace
209 calls sethostname(2). The kernel traditionally uses "(none)" here,
210 but you may wish to use a different default here to make a minimal
211 system more usable with less configuration.
214 bool "Support for paging of anonymous memory (swap)"
215 depends on MMU && BLOCK
218 This option allows you to choose whether you want to have support
219 for so called swap devices or swap files in your kernel that are
220 used to provide more virtual memory than the actual RAM present
221 in your computer. If unsure say Y.
226 Inter Process Communication is a suite of library functions and
227 system calls which let processes (running programs) synchronize and
228 exchange information. It is generally considered to be a good thing,
229 and some programs won't run unless you say Y here. In particular, if
230 you want to run the DOS emulator dosemu under Linux (read the
231 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
232 you'll need to say Y here.
234 You can find documentation about IPC with "info ipc" and also in
235 section 6.4 of the Linux Programmer's Guide, available from
236 <http://www.tldp.org/guides.html>.
238 config SYSVIPC_SYSCTL
245 bool "POSIX Message Queues"
246 depends on NET && EXPERIMENTAL
248 POSIX variant of message queues is a part of IPC. In POSIX message
249 queues every message has a priority which decides about succession
250 of receiving it by a process. If you want to compile and run
251 programs written e.g. for Solaris with use of its POSIX message
252 queues (functions mq_*) say Y here.
254 POSIX message queues are visible as a filesystem called 'mqueue'
255 and can be mounted somewhere if you want to do filesystem
256 operations on message queues.
260 config POSIX_MQUEUE_SYSCTL
262 depends on POSIX_MQUEUE
267 bool "open by fhandle syscalls"
270 If you say Y here, a user level program will be able to map
271 file names to handle and then later use the handle for
272 different file system operations. This is useful in implementing
273 userspace file servers, which now track files using handles instead
274 of names. The handle would remain the same even if file names
275 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
279 bool "Auditing support"
282 Enable auditing infrastructure that can be used with another
283 kernel subsystem, such as SELinux (which requires this for
284 logging of avc messages output). Does not do system-call
285 auditing without CONFIG_AUDITSYSCALL.
288 bool "Enable system-call auditing support"
289 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || (ARM && AEABI && !OABI_COMPAT))
290 default y if SECURITY_SELINUX
292 Enable low-overhead system-call auditing infrastructure that
293 can be used independently or with another kernel subsystem,
298 depends on AUDITSYSCALL
303 depends on AUDITSYSCALL
306 config AUDIT_LOGINUID_IMMUTABLE
307 bool "Make audit loginuid immutable"
310 The config option toggles if a task setting its loginuid requires
311 CAP_SYS_AUDITCONTROL or if that task should require no special permissions
312 but should instead only allow setting its loginuid if it was never
313 previously set. On systems which use systemd or a similar central
314 process to restart login services this should be set to true. On older
315 systems in which an admin would typically have to directly stop and
316 start processes this should be set to false. Setting this to true allows
317 one to drop potentially dangerous capabilites from the login tasks,
318 but may not be backwards compatible with older init systems.
320 source "kernel/irq/Kconfig"
321 source "kernel/time/Kconfig"
323 menu "CPU/Task time and stats accounting"
325 config VIRT_CPU_ACCOUNTING
329 prompt "Cputime accounting"
330 default TICK_CPU_ACCOUNTING if !PPC64
331 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
333 # Kind of a stub config for the pure tick based cputime accounting
334 config TICK_CPU_ACCOUNTING
335 bool "Simple tick based cputime accounting"
338 This is the basic tick based cputime accounting that maintains
339 statistics about user, system and idle time spent on per jiffies
344 config VIRT_CPU_ACCOUNTING_NATIVE
345 bool "Deterministic task and CPU time accounting"
346 depends on HAVE_VIRT_CPU_ACCOUNTING
347 select 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 VIRT_CPU_ACCOUNTING_GEN
358 bool "Full dynticks CPU time accounting"
359 depends on HAVE_CONTEXT_TRACKING && 64BIT
360 select VIRT_CPU_ACCOUNTING
361 select CONTEXT_TRACKING
363 Select this option to enable task and CPU time accounting on full
364 dynticks systems. This accounting is implemented by watching every
365 kernel-user boundaries using the context tracking subsystem.
366 The accounting is thus performed at the expense of some significant
369 For now this is only useful if you are working on the full
370 dynticks subsystem development.
374 config IRQ_TIME_ACCOUNTING
375 bool "Fine granularity task level IRQ time accounting"
376 depends on HAVE_IRQ_TIME_ACCOUNTING
378 Select this option to enable fine granularity task irq time
379 accounting. This is done by reading a timestamp on each
380 transitions between softirq and hardirq state, so there can be a
381 small performance impact.
383 If in doubt, say N here.
387 config BSD_PROCESS_ACCT
388 bool "BSD Process Accounting"
390 If you say Y here, a user level program will be able to instruct the
391 kernel (via a special system call) to write process accounting
392 information to a file: whenever a process exits, information about
393 that process will be appended to the file by the kernel. The
394 information includes things such as creation time, owning user,
395 command name, memory usage, controlling terminal etc. (the complete
396 list is in the struct acct in <file:include/linux/acct.h>). It is
397 up to the user level program to do useful things with this
398 information. This is generally a good idea, so say Y.
400 config BSD_PROCESS_ACCT_V3
401 bool "BSD Process Accounting version 3 file format"
402 depends on BSD_PROCESS_ACCT
405 If you say Y here, the process accounting information is written
406 in a new file format that also logs the process IDs of each
407 process and it's parent. Note that this file format is incompatible
408 with previous v0/v1/v2 file formats, so you will need updated tools
409 for processing it. A preliminary version of these tools is available
410 at <http://www.gnu.org/software/acct/>.
413 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
417 Export selected statistics for tasks/processes through the
418 generic netlink interface. Unlike BSD process accounting, the
419 statistics are available during the lifetime of tasks/processes as
420 responses to commands. Like BSD accounting, they are sent to user
425 config TASK_DELAY_ACCT
426 bool "Enable per-task delay accounting (EXPERIMENTAL)"
429 Collect information on time spent by a task waiting for system
430 resources like cpu, synchronous block I/O completion and swapping
431 in pages. Such statistics can help in setting a task's priorities
432 relative to other tasks for cpu, io, rss limits etc.
437 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
440 Collect extended task accounting data and send the data
441 to userland for processing over the taskstats interface.
445 config TASK_IO_ACCOUNTING
446 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
447 depends on TASK_XACCT
449 Collect information on the number of bytes of storage I/O which this
454 endmenu # "CPU/Task time and stats accounting"
459 prompt "RCU Implementation"
463 bool "Tree-based hierarchical RCU"
464 depends on !PREEMPT && SMP
466 This option selects the RCU implementation that is
467 designed for very large SMP system with hundreds or
468 thousands of CPUs. It also scales down nicely to
471 config TREE_PREEMPT_RCU
472 bool "Preemptible tree-based hierarchical RCU"
475 This option selects the RCU implementation that is
476 designed for very large SMP systems with hundreds or
477 thousands of CPUs, but for which real-time response
478 is also required. It also scales down nicely to
481 Select this option if you are unsure.
484 bool "UP-only small-memory-footprint RCU"
485 depends on !PREEMPT && !SMP
487 This option selects the RCU implementation that is
488 designed for UP systems from which real-time response
489 is not required. This option greatly reduces the
490 memory footprint of RCU.
492 config TINY_PREEMPT_RCU
493 bool "Preemptible UP-only small-memory-footprint RCU"
494 depends on PREEMPT && !SMP
496 This option selects the RCU implementation that is designed
497 for real-time UP systems. This option greatly reduces the
498 memory footprint of RCU.
503 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
505 This option enables preemptible-RCU code that is common between
506 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
508 config RCU_STALL_COMMON
509 def_bool ( TREE_RCU || TREE_PREEMPT_RCU || RCU_TRACE )
511 This option enables RCU CPU stall code that is common between
512 the TINY and TREE variants of RCU. The purpose is to allow
513 the tiny variants to disable RCU CPU stall warnings, while
514 making these warnings mandatory for the tree variants.
516 config CONTEXT_TRACKING
520 bool "Consider userspace as in RCU extended quiescent state"
521 depends on HAVE_CONTEXT_TRACKING && SMP
522 select CONTEXT_TRACKING
524 This option sets hooks on kernel / userspace boundaries and
525 puts RCU in extended quiescent state when the CPU runs in
526 userspace. It means that when a CPU runs in userspace, it is
527 excluded from the global RCU state machine and thus doesn't
528 try to keep the timer tick on for RCU.
530 Unless you want to hack and help the development of the full
531 dynticks mode, you shouldn't enable this option. It also
532 adds unnecessary overhead.
536 config CONTEXT_TRACKING_FORCE
537 bool "Force context tracking"
538 depends on CONTEXT_TRACKING
540 Probe on user/kernel boundaries by default in order to
541 test the features that rely on it such as userspace RCU extended
543 This test is there for debugging until we have a real user like the
547 int "Tree-based hierarchical RCU fanout value"
550 depends on TREE_RCU || TREE_PREEMPT_RCU
554 This option controls the fanout of hierarchical implementations
555 of RCU, allowing RCU to work efficiently on machines with
556 large numbers of CPUs. This value must be at least the fourth
557 root of NR_CPUS, which allows NR_CPUS to be insanely large.
558 The default value of RCU_FANOUT should be used for production
559 systems, but if you are stress-testing the RCU implementation
560 itself, small RCU_FANOUT values allow you to test large-system
561 code paths on small(er) systems.
563 Select a specific number if testing RCU itself.
564 Take the default if unsure.
566 config RCU_FANOUT_LEAF
567 int "Tree-based hierarchical RCU leaf-level fanout value"
568 range 2 RCU_FANOUT if 64BIT
569 range 2 RCU_FANOUT if !64BIT
570 depends on TREE_RCU || TREE_PREEMPT_RCU
573 This option controls the leaf-level fanout of hierarchical
574 implementations of RCU, and allows trading off cache misses
575 against lock contention. Systems that synchronize their
576 scheduling-clock interrupts for energy-efficiency reasons will
577 want the default because the smaller leaf-level fanout keeps
578 lock contention levels acceptably low. Very large systems
579 (hundreds or thousands of CPUs) will instead want to set this
580 value to the maximum value possible in order to reduce the
581 number of cache misses incurred during RCU's grace-period
582 initialization. These systems tend to run CPU-bound, and thus
583 are not helped by synchronized interrupts, and thus tend to
584 skew them, which reduces lock contention enough that large
585 leaf-level fanouts work well.
587 Select a specific number if testing RCU itself.
589 Select the maximum permissible value for large systems.
591 Take the default if unsure.
593 config RCU_FANOUT_EXACT
594 bool "Disable tree-based hierarchical RCU auto-balancing"
595 depends on TREE_RCU || TREE_PREEMPT_RCU
598 This option forces use of the exact RCU_FANOUT value specified,
599 regardless of imbalances in the hierarchy. This is useful for
600 testing RCU itself, and might one day be useful on systems with
601 strong NUMA behavior.
603 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
607 config RCU_FAST_NO_HZ
608 bool "Accelerate last non-dyntick-idle CPU's grace periods"
609 depends on NO_HZ && SMP
612 This option causes RCU to attempt to accelerate grace periods in
613 order to allow CPUs to enter dynticks-idle state more quickly.
614 On the other hand, this option increases the overhead of the
615 dynticks-idle checking, thus degrading scheduling latency.
617 Say Y if energy efficiency is critically important, and you don't
618 care about real-time response.
620 Say N if you are unsure.
622 config TREE_RCU_TRACE
623 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
626 This option provides tracing for the TREE_RCU and
627 TREE_PREEMPT_RCU implementations, permitting Makefile to
628 trivially select kernel/rcutree_trace.c.
631 bool "Enable RCU priority boosting"
632 depends on RT_MUTEXES && PREEMPT_RCU
635 This option boosts the priority of preempted RCU readers that
636 block the current preemptible RCU grace period for too long.
637 This option also prevents heavy loads from blocking RCU
638 callback invocation for all flavors of RCU.
640 Say Y here if you are working with real-time apps or heavy loads
641 Say N here if you are unsure.
643 config RCU_BOOST_PRIO
644 int "Real-time priority to boost RCU readers to"
649 This option specifies the real-time priority to which long-term
650 preempted RCU readers are to be boosted. If you are working
651 with a real-time application that has one or more CPU-bound
652 threads running at a real-time priority level, you should set
653 RCU_BOOST_PRIO to a priority higher then the highest-priority
654 real-time CPU-bound thread. The default RCU_BOOST_PRIO value
655 of 1 is appropriate in the common case, which is real-time
656 applications that do not have any CPU-bound threads.
658 Some real-time applications might not have a single real-time
659 thread that saturates a given CPU, but instead might have
660 multiple real-time threads that, taken together, fully utilize
661 that CPU. In this case, you should set RCU_BOOST_PRIO to
662 a priority higher than the lowest-priority thread that is
663 conspiring to prevent the CPU from running any non-real-time
664 tasks. For example, if one thread at priority 10 and another
665 thread at priority 5 are between themselves fully consuming
666 the CPU time on a given CPU, then RCU_BOOST_PRIO should be
667 set to priority 6 or higher.
669 Specify the real-time priority, or take the default if unsure.
671 config RCU_BOOST_DELAY
672 int "Milliseconds to delay boosting after RCU grace-period start"
677 This option specifies the time to wait after the beginning of
678 a given grace period before priority-boosting preempted RCU
679 readers blocking that grace period. Note that any RCU reader
680 blocking an expedited RCU grace period is boosted immediately.
682 Accept the default if unsure.
685 bool "Offload RCU callback processing from boot-selected CPUs"
686 depends on TREE_RCU || TREE_PREEMPT_RCU
689 Use this option to reduce OS jitter for aggressive HPC or
690 real-time workloads. It can also be used to offload RCU
691 callback invocation to energy-efficient CPUs in battery-powered
692 asymmetric multiprocessors.
694 This option offloads callback invocation from the set of
695 CPUs specified at boot time by the rcu_nocbs parameter.
696 For each such CPU, a kthread ("rcuoN") will be created to
697 invoke callbacks, where the "N" is the CPU being offloaded.
698 Nothing prevents this kthread from running on the specified
699 CPUs, but (1) the kthreads may be preempted between each
700 callback, and (2) affinity or cgroups can be used to force
701 the kthreads to run on whatever set of CPUs is desired.
703 Say Y here if you want reduced OS jitter on selected CPUs.
704 Say N here if you are unsure.
706 endmenu # "RCU Subsystem"
709 tristate "Kernel .config support"
711 This option enables the complete Linux kernel ".config" file
712 contents to be saved in the kernel. It provides documentation
713 of which kernel options are used in a running kernel or in an
714 on-disk kernel. This information can be extracted from the kernel
715 image file with the script scripts/extract-ikconfig and used as
716 input to rebuild the current kernel or to build another kernel.
717 It can also be extracted from a running kernel by reading
718 /proc/config.gz if enabled (below).
721 bool "Enable access to .config through /proc/config.gz"
722 depends on IKCONFIG && PROC_FS
724 This option enables access to the kernel configuration file
725 through /proc/config.gz.
728 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
732 Select kernel log buffer size as a power of 2.
742 # Architectures with an unreliable sched_clock() should select this:
744 config HAVE_UNSTABLE_SCHED_CLOCK
748 # For architectures that want to enable the support for NUMA-affine scheduler
751 config ARCH_SUPPORTS_NUMA_BALANCING
754 # For architectures that (ab)use NUMA to represent different memory regions
755 # all cpu-local but of different latencies, such as SuperH.
757 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
761 # For architectures that are willing to define _PAGE_NUMA as _PAGE_PROTNONE
762 config ARCH_WANTS_PROT_NUMA_PROT_NONE
765 config ARCH_USES_NUMA_PROT_NONE
768 depends on ARCH_WANTS_PROT_NUMA_PROT_NONE
769 depends on NUMA_BALANCING
771 config NUMA_BALANCING_DEFAULT_ENABLED
772 bool "Automatically enable NUMA aware memory/task placement"
774 depends on NUMA_BALANCING
776 If set, autonumic NUMA balancing will be enabled if running on a NUMA
779 config NUMA_BALANCING
780 bool "Memory placement aware NUMA scheduler"
781 depends on ARCH_SUPPORTS_NUMA_BALANCING
782 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
783 depends on SMP && NUMA && MIGRATION
785 This option adds support for automatic NUMA aware memory/task placement.
786 The mechanism is quite primitive and is based on migrating memory when
787 it is references to the node the task is running on.
789 This system will be inactive on UMA systems.
792 boolean "Control Group support"
795 This option adds support for grouping sets of processes together, for
796 use with process control subsystems such as Cpusets, CFS, memory
797 controls or device isolation.
799 - Documentation/scheduler/sched-design-CFS.txt (CFS)
800 - Documentation/cgroups/ (features for grouping, isolation
801 and resource control)
808 bool "Example debug cgroup subsystem"
811 This option enables a simple cgroup subsystem that
812 exports useful debugging information about the cgroups
817 config CGROUP_FREEZER
818 bool "Freezer cgroup subsystem"
820 Provides a way to freeze and unfreeze all tasks in a
824 bool "Device controller for cgroups"
826 Provides a cgroup implementing whitelists for devices which
827 a process in the cgroup can mknod or open.
830 bool "Cpuset support"
832 This option will let you create and manage CPUSETs which
833 allow dynamically partitioning a system into sets of CPUs and
834 Memory Nodes and assigning tasks to run only within those sets.
835 This is primarily useful on large SMP or NUMA systems.
839 config PROC_PID_CPUSET
840 bool "Include legacy /proc/<pid>/cpuset file"
844 config CGROUP_CPUACCT
845 bool "Simple CPU accounting cgroup subsystem"
847 Provides a simple Resource Controller for monitoring the
848 total CPU consumed by the tasks in a cgroup.
850 config RESOURCE_COUNTERS
851 bool "Resource counters"
853 This option enables controller independent resource accounting
854 infrastructure that works with cgroups.
857 bool "Memory Resource Controller for Control Groups"
858 depends on RESOURCE_COUNTERS
861 Provides a memory resource controller that manages both anonymous
862 memory and page cache. (See Documentation/cgroups/memory.txt)
864 Note that setting this option increases fixed memory overhead
865 associated with each page of memory in the system. By this,
866 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
867 usage tracking struct at boot. Total amount of this is printed out
870 Only enable when you're ok with these trade offs and really
871 sure you need the memory resource controller. Even when you enable
872 this, you can set "cgroup_disable=memory" at your boot option to
873 disable memory resource controller and you can avoid overheads.
874 (and lose benefits of memory resource controller)
876 This config option also selects MM_OWNER config option, which
877 could in turn add some fork/exit overhead.
880 bool "Memory Resource Controller Swap Extension"
881 depends on MEMCG && SWAP
883 Add swap management feature to memory resource controller. When you
884 enable this, you can limit mem+swap usage per cgroup. In other words,
885 when you disable this, memory resource controller has no cares to
886 usage of swap...a process can exhaust all of the swap. This extension
887 is useful when you want to avoid exhaustion swap but this itself
888 adds more overheads and consumes memory for remembering information.
889 Especially if you use 32bit system or small memory system, please
890 be careful about enabling this. When memory resource controller
891 is disabled by boot option, this will be automatically disabled and
892 there will be no overhead from this. Even when you set this config=y,
893 if boot option "swapaccount=0" is set, swap will not be accounted.
894 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
895 size is 4096bytes, 512k per 1Gbytes of swap.
896 config MEMCG_SWAP_ENABLED
897 bool "Memory Resource Controller Swap Extension enabled by default"
898 depends on MEMCG_SWAP
901 Memory Resource Controller Swap Extension comes with its price in
902 a bigger memory consumption. General purpose distribution kernels
903 which want to enable the feature but keep it disabled by default
904 and let the user enable it by swapaccount boot command line
905 parameter should have this option unselected.
906 For those who want to have the feature enabled by default should
907 select this option (if, for some reason, they need to disable it
908 then swapaccount=0 does the trick).
910 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
911 depends on MEMCG && EXPERIMENTAL
912 depends on SLUB || SLAB
914 The Kernel Memory extension for Memory Resource Controller can limit
915 the amount of memory used by kernel objects in the system. Those are
916 fundamentally different from the entities handled by the standard
917 Memory Controller, which are page-based, and can be swapped. Users of
918 the kmem extension can use it to guarantee that no group of processes
919 will ever exhaust kernel resources alone.
921 config CGROUP_HUGETLB
922 bool "HugeTLB Resource Controller for Control Groups"
923 depends on RESOURCE_COUNTERS && HUGETLB_PAGE && EXPERIMENTAL
926 Provides a cgroup Resource Controller for HugeTLB pages.
927 When you enable this, you can put a per cgroup limit on HugeTLB usage.
928 The limit is enforced during page fault. Since HugeTLB doesn't
929 support page reclaim, enforcing the limit at page fault time implies
930 that, the application will get SIGBUS signal if it tries to access
931 HugeTLB pages beyond its limit. This requires the application to know
932 beforehand how much HugeTLB pages it would require for its use. The
933 control group is tracked in the third page lru pointer. This means
934 that we cannot use the controller with huge page less than 3 pages.
937 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
938 depends on PERF_EVENTS && CGROUPS
940 This option extends the per-cpu mode to restrict monitoring to
941 threads which belong to the cgroup specified and run on the
946 menuconfig CGROUP_SCHED
947 bool "Group CPU scheduler"
950 This feature lets CPU scheduler recognize task groups and control CPU
951 bandwidth allocation to such task groups. It uses cgroups to group
955 config FAIR_GROUP_SCHED
956 bool "Group scheduling for SCHED_OTHER"
957 depends on CGROUP_SCHED
961 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
962 depends on EXPERIMENTAL
963 depends on FAIR_GROUP_SCHED
966 This option allows users to define CPU bandwidth rates (limits) for
967 tasks running within the fair group scheduler. Groups with no limit
968 set are considered to be unconstrained and will run with no
970 See tip/Documentation/scheduler/sched-bwc.txt for more information.
972 config RT_GROUP_SCHED
973 bool "Group scheduling for SCHED_RR/FIFO"
974 depends on EXPERIMENTAL
975 depends on CGROUP_SCHED
978 This feature lets you explicitly allocate real CPU bandwidth
979 to task groups. If enabled, it will also make it impossible to
980 schedule realtime tasks for non-root users until you allocate
981 realtime bandwidth for them.
982 See Documentation/scheduler/sched-rt-group.txt for more information.
987 bool "Block IO controller"
991 Generic block IO controller cgroup interface. This is the common
992 cgroup interface which should be used by various IO controlling
995 Currently, CFQ IO scheduler uses it to recognize task groups and
996 control disk bandwidth allocation (proportional time slice allocation)
997 to such task groups. It is also used by bio throttling logic in
998 block layer to implement upper limit in IO rates on a device.
1000 This option only enables generic Block IO controller infrastructure.
1001 One needs to also enable actual IO controlling logic/policy. For
1002 enabling proportional weight division of disk bandwidth in CFQ, set
1003 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1004 CONFIG_BLK_DEV_THROTTLING=y.
1006 See Documentation/cgroups/blkio-controller.txt for more information.
1008 config DEBUG_BLK_CGROUP
1009 bool "Enable Block IO controller debugging"
1010 depends on BLK_CGROUP
1013 Enable some debugging help. Currently it exports additional stat
1014 files in a cgroup which can be useful for debugging.
1018 config CHECKPOINT_RESTORE
1019 bool "Checkpoint/restore support" if EXPERT
1022 Enables additional kernel features in a sake of checkpoint/restore.
1023 In particular it adds auxiliary prctl codes to setup process text,
1024 data and heap segment sizes, and a few additional /proc filesystem
1027 If unsure, say N here.
1029 menuconfig NAMESPACES
1030 bool "Namespaces support" if EXPERT
1033 Provides the way to make tasks work with different objects using
1034 the same id. For example same IPC id may refer to different objects
1035 or same user id or pid may refer to different tasks when used in
1036 different namespaces.
1041 bool "UTS namespace"
1044 In this namespace tasks see different info provided with the
1048 bool "IPC namespace"
1049 depends on (SYSVIPC || POSIX_MQUEUE)
1052 In this namespace tasks work with IPC ids which correspond to
1053 different IPC objects in different namespaces.
1056 bool "User namespace (EXPERIMENTAL)"
1057 depends on EXPERIMENTAL
1058 depends on UIDGID_CONVERTED
1059 select UIDGID_STRICT_TYPE_CHECKS
1063 This allows containers, i.e. vservers, to use user namespaces
1064 to provide different user info for different servers.
1068 bool "PID Namespaces"
1071 Support process id namespaces. This allows having multiple
1072 processes with the same pid as long as they are in different
1073 pid namespaces. This is a building block of containers.
1076 bool "Network namespace"
1080 Allow user space to create what appear to be multiple instances
1081 of the network stack.
1085 config UIDGID_CONVERTED
1086 # True if all of the selected software conmponents are known
1087 # to have uid_t and gid_t converted to kuid_t and kgid_t
1088 # where appropriate and are otherwise safe to use with
1089 # the user namespace.
1094 depends on NET_9P = n
1097 depends on 9P_FS = n
1098 depends on AFS_FS = n
1099 depends on CEPH_FS = n
1101 depends on CODA_FS = n
1102 depends on GFS2_FS = n
1103 depends on NCP_FS = n
1105 depends on NFS_FS = n
1106 depends on OCFS2_FS = n
1107 depends on XFS_FS = n
1109 config UIDGID_STRICT_TYPE_CHECKS
1110 bool "Require conversions between uid/gids and their internal representation"
1111 depends on UIDGID_CONVERTED
1114 While the nececessary conversions are being added to all subsystems this option allows
1115 the code to continue to build for unconverted subsystems.
1117 Say Y here if you want the strict type checking enabled
1119 config SCHED_AUTOGROUP
1120 bool "Automatic process group scheduling"
1124 select FAIR_GROUP_SCHED
1126 This option optimizes the scheduler for common desktop workloads by
1127 automatically creating and populating task groups. This separation
1128 of workloads isolates aggressive CPU burners (like build jobs) from
1129 desktop applications. Task group autogeneration is currently based
1135 config SYSFS_DEPRECATED
1136 bool "Enable deprecated sysfs features to support old userspace tools"
1140 This option adds code that switches the layout of the "block" class
1141 devices, to not show up in /sys/class/block/, but only in
1144 This switch is only active when the sysfs.deprecated=1 boot option is
1145 passed or the SYSFS_DEPRECATED_V2 option is set.
1147 This option allows new kernels to run on old distributions and tools,
1148 which might get confused by /sys/class/block/. Since 2007/2008 all
1149 major distributions and tools handle this just fine.
1151 Recent distributions and userspace tools after 2009/2010 depend on
1152 the existence of /sys/class/block/, and will not work with this
1155 Only if you are using a new kernel on an old distribution, you might
1158 config SYSFS_DEPRECATED_V2
1159 bool "Enable deprecated sysfs features by default"
1162 depends on SYSFS_DEPRECATED
1164 Enable deprecated sysfs by default.
1166 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1169 Only if you are using a new kernel on an old distribution, you might
1170 need to say Y here. Even then, odds are you would not need it
1171 enabled, you can always pass the boot option if absolutely necessary.
1174 bool "Kernel->user space relay support (formerly relayfs)"
1176 This option enables support for relay interface support in
1177 certain file systems (such as debugfs).
1178 It is designed to provide an efficient mechanism for tools and
1179 facilities to relay large amounts of data from kernel space to
1184 config BLK_DEV_INITRD
1185 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1186 depends on BROKEN || !FRV
1188 The initial RAM filesystem is a ramfs which is loaded by the
1189 boot loader (loadlin or lilo) and that is mounted as root
1190 before the normal boot procedure. It is typically used to
1191 load modules needed to mount the "real" root file system,
1192 etc. See <file:Documentation/initrd.txt> for details.
1194 If RAM disk support (BLK_DEV_RAM) is also included, this
1195 also enables initial RAM disk (initrd) support and adds
1196 15 Kbytes (more on some other architectures) to the kernel size.
1202 source "usr/Kconfig"
1206 config CC_OPTIMIZE_FOR_SIZE
1207 bool "Optimize for size"
1209 Enabling this option will pass "-Os" instead of "-O2" to gcc
1210 resulting in a smaller kernel.
1221 bool "Configure standard kernel features (expert users)"
1222 # Unhide debug options, to make the on-by-default options visible
1225 This option allows certain base kernel options and settings
1226 to be disabled or tweaked. This is for specialized
1227 environments which can tolerate a "non-standard" kernel.
1228 Only use this if you really know what you are doing.
1234 bool "Enable 16-bit UID system calls" if EXPERT
1235 depends on HAVE_UID16
1238 This enables the legacy 16-bit UID syscall wrappers.
1240 config SYSCTL_SYSCALL
1241 bool "Sysctl syscall support" if EXPERT
1242 depends on PROC_SYSCTL
1246 sys_sysctl uses binary paths that have been found challenging
1247 to properly maintain and use. The interface in /proc/sys
1248 using paths with ascii names is now the primary path to this
1251 Almost nothing using the binary sysctl interface so if you are
1252 trying to save some space it is probably safe to disable this,
1253 making your kernel marginally smaller.
1255 If unsure say N here.
1257 config SYSCTL_EXCEPTION_TRACE
1260 Enable support for /proc/sys/debug/exception-trace.
1263 bool "Load all symbols for debugging/ksymoops" if EXPERT
1266 Say Y here to let the kernel print out symbolic crash information and
1267 symbolic stack backtraces. This increases the size of the kernel
1268 somewhat, as all symbols have to be loaded into the kernel image.
1271 bool "Include all symbols in kallsyms"
1272 depends on DEBUG_KERNEL && KALLSYMS
1274 Normally kallsyms only contains the symbols of functions for nicer
1275 OOPS messages and backtraces (i.e., symbols from the text and inittext
1276 sections). This is sufficient for most cases. And only in very rare
1277 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1278 names of variables from the data sections, etc).
1280 This option makes sure that all symbols are loaded into the kernel
1281 image (i.e., symbols from all sections) in cost of increased kernel
1282 size (depending on the kernel configuration, it may be 300KiB or
1283 something like this).
1285 Say N unless you really need all symbols.
1292 bool "Enable support for printk" if EXPERT
1295 This option enables normal printk support. Removing it
1296 eliminates most of the message strings from the kernel image
1297 and makes the kernel more or less silent. As this makes it
1298 very difficult to diagnose system problems, saying N here is
1299 strongly discouraged.
1302 bool "BUG() support" if EXPERT
1305 Disabling this option eliminates support for BUG and WARN, reducing
1306 the size of your kernel image and potentially quietly ignoring
1307 numerous fatal conditions. You should only consider disabling this
1308 option for embedded systems with no facilities for reporting errors.
1314 bool "Enable ELF core dumps" if EXPERT
1316 Enable support for generating core dumps. Disabling saves about 4k.
1319 config PCSPKR_PLATFORM
1320 bool "Enable PC-Speaker support" if EXPERT
1321 depends on HAVE_PCSPKR_PLATFORM
1325 This option allows to disable the internal PC-Speaker
1326 support, saving some memory.
1328 config HAVE_PCSPKR_PLATFORM
1333 bool "Enable full-sized data structures for core" if EXPERT
1335 Disabling this option reduces the size of miscellaneous core
1336 kernel data structures. This saves memory on small machines,
1337 but may reduce performance.
1340 bool "Enable futex support" if EXPERT
1344 Disabling this option will cause the kernel to be built without
1345 support for "fast userspace mutexes". The resulting kernel may not
1346 run glibc-based applications correctly.
1349 bool "Enable eventpoll support" if EXPERT
1353 Disabling this option will cause the kernel to be built without
1354 support for epoll family of system calls.
1357 bool "Enable signalfd() system call" if EXPERT
1361 Enable the signalfd() system call that allows to receive signals
1362 on a file descriptor.
1367 bool "Enable timerfd() system call" if EXPERT
1371 Enable the timerfd() system call that allows to receive timer
1372 events on a file descriptor.
1377 bool "Enable eventfd() system call" if EXPERT
1381 Enable the eventfd() system call that allows to receive both
1382 kernel notification (ie. KAIO) or userspace notifications.
1387 bool "Use full shmem filesystem" if EXPERT
1391 The shmem is an internal filesystem used to manage shared memory.
1392 It is backed by swap and manages resource limits. It is also exported
1393 to userspace as tmpfs if TMPFS is enabled. Disabling this
1394 option replaces shmem and tmpfs with the much simpler ramfs code,
1395 which may be appropriate on small systems without swap.
1398 bool "Enable AIO support" if EXPERT
1401 This option enables POSIX asynchronous I/O which may by used
1402 by some high performance threaded applications. Disabling
1403 this option saves about 7k.
1406 bool "Embedded system"
1409 This option should be enabled if compiling the kernel for
1410 an embedded system so certain expert options are available
1413 config HAVE_PERF_EVENTS
1416 See tools/perf/design.txt for details.
1418 config PERF_USE_VMALLOC
1421 See tools/perf/design.txt for details
1423 menu "Kernel Performance Events And Counters"
1426 bool "Kernel performance events and counters"
1427 default y if PROFILING
1428 depends on HAVE_PERF_EVENTS
1432 Enable kernel support for various performance events provided
1433 by software and hardware.
1435 Software events are supported either built-in or via the
1436 use of generic tracepoints.
1438 Most modern CPUs support performance events via performance
1439 counter registers. These registers count the number of certain
1440 types of hw events: such as instructions executed, cachemisses
1441 suffered, or branches mis-predicted - without slowing down the
1442 kernel or applications. These registers can also trigger interrupts
1443 when a threshold number of events have passed - and can thus be
1444 used to profile the code that runs on that CPU.
1446 The Linux Performance Event subsystem provides an abstraction of
1447 these software and hardware event capabilities, available via a
1448 system call and used by the "perf" utility in tools/perf/. It
1449 provides per task and per CPU counters, and it provides event
1450 capabilities on top of those.
1454 config DEBUG_PERF_USE_VMALLOC
1456 bool "Debug: use vmalloc to back perf mmap() buffers"
1457 depends on PERF_EVENTS && DEBUG_KERNEL
1458 select PERF_USE_VMALLOC
1460 Use vmalloc memory to back perf mmap() buffers.
1462 Mostly useful for debugging the vmalloc code on platforms
1463 that don't require it.
1469 config VM_EVENT_COUNTERS
1471 bool "Enable VM event counters for /proc/vmstat" if EXPERT
1473 VM event counters are needed for event counts to be shown.
1474 This option allows the disabling of the VM event counters
1475 on EXPERT systems. /proc/vmstat will only show page counts
1476 if VM event counters are disabled.
1480 bool "Enable PCI quirk workarounds" if EXPERT
1483 This enables workarounds for various PCI chipset
1484 bugs/quirks. Disable this only if your target machine is
1485 unaffected by PCI quirks.
1489 bool "Enable SLUB debugging support" if EXPERT
1490 depends on SLUB && SYSFS
1492 SLUB has extensive debug support features. Disabling these can
1493 result in significant savings in code size. This also disables
1494 SLUB sysfs support. /sys/slab will not exist and there will be
1495 no support for cache validation etc.
1498 bool "Disable heap randomization"
1501 Randomizing heap placement makes heap exploits harder, but it
1502 also breaks ancient binaries (including anything libc5 based).
1503 This option changes the bootup default to heap randomization
1504 disabled, and can be overridden at runtime by setting
1505 /proc/sys/kernel/randomize_va_space to 2.
1507 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1510 prompt "Choose SLAB allocator"
1513 This option allows to select a slab allocator.
1518 The regular slab allocator that is established and known to work
1519 well in all environments. It organizes cache hot objects in
1520 per cpu and per node queues.
1523 bool "SLUB (Unqueued Allocator)"
1525 SLUB is a slab allocator that minimizes cache line usage
1526 instead of managing queues of cached objects (SLAB approach).
1527 Per cpu caching is realized using slabs of objects instead
1528 of queues of objects. SLUB can use memory efficiently
1529 and has enhanced diagnostics. SLUB is the default choice for
1534 bool "SLOB (Simple Allocator)"
1536 SLOB replaces the stock allocator with a drastically simpler
1537 allocator. SLOB is generally more space efficient but
1538 does not perform as well on large systems.
1542 config MMAP_ALLOW_UNINITIALIZED
1543 bool "Allow mmapped anonymous memory to be uninitialized"
1544 depends on EXPERT && !MMU
1547 Normally, and according to the Linux spec, anonymous memory obtained
1548 from mmap() has it's contents cleared before it is passed to
1549 userspace. Enabling this config option allows you to request that
1550 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1551 providing a huge performance boost. If this option is not enabled,
1552 then the flag will be ignored.
1554 This is taken advantage of by uClibc's malloc(), and also by
1555 ELF-FDPIC binfmt's brk and stack allocator.
1557 Because of the obvious security issues, this option should only be
1558 enabled on embedded devices where you control what is run in
1559 userspace. Since that isn't generally a problem on no-MMU systems,
1560 it is normally safe to say Y here.
1562 See Documentation/nommu-mmap.txt for more information.
1565 bool "Profiling support"
1567 Say Y here to enable the extended profiling support mechanisms used
1568 by profilers such as OProfile.
1571 # Place an empty function call at each tracepoint site. Can be
1572 # dynamically changed for a probe function.
1577 source "arch/Kconfig"
1579 endmenu # General setup
1581 config HAVE_GENERIC_DMA_COHERENT
1588 depends on SLAB || SLUB_DEBUG
1596 default 0 if BASE_FULL
1597 default 1 if !BASE_FULL
1600 bool "Enable loadable module support"
1602 Kernel modules are small pieces of compiled code which can
1603 be inserted in the running kernel, rather than being
1604 permanently built into the kernel. You use the "modprobe"
1605 tool to add (and sometimes remove) them. If you say Y here,
1606 many parts of the kernel can be built as modules (by
1607 answering M instead of Y where indicated): this is most
1608 useful for infrequently used options which are not required
1609 for booting. For more information, see the man pages for
1610 modprobe, lsmod, modinfo, insmod and rmmod.
1612 If you say Y here, you will need to run "make
1613 modules_install" to put the modules under /lib/modules/
1614 where modprobe can find them (you may need to be root to do
1621 config MODULE_FORCE_LOAD
1622 bool "Forced module loading"
1625 Allow loading of modules without version information (ie. modprobe
1626 --force). Forced module loading sets the 'F' (forced) taint flag and
1627 is usually a really bad idea.
1629 config MODULE_UNLOAD
1630 bool "Module unloading"
1632 Without this option you will not be able to unload any
1633 modules (note that some modules may not be unloadable
1634 anyway), which makes your kernel smaller, faster
1635 and simpler. If unsure, say Y.
1637 config MODULE_FORCE_UNLOAD
1638 bool "Forced module unloading"
1639 depends on MODULE_UNLOAD && EXPERIMENTAL
1641 This option allows you to force a module to unload, even if the
1642 kernel believes it is unsafe: the kernel will remove the module
1643 without waiting for anyone to stop using it (using the -f option to
1644 rmmod). This is mainly for kernel developers and desperate users.
1648 bool "Module versioning support"
1650 Usually, you have to use modules compiled with your kernel.
1651 Saying Y here makes it sometimes possible to use modules
1652 compiled for different kernels, by adding enough information
1653 to the modules to (hopefully) spot any changes which would
1654 make them incompatible with the kernel you are running. If
1657 config MODULE_SRCVERSION_ALL
1658 bool "Source checksum for all modules"
1660 Modules which contain a MODULE_VERSION get an extra "srcversion"
1661 field inserted into their modinfo section, which contains a
1662 sum of the source files which made it. This helps maintainers
1663 see exactly which source was used to build a module (since
1664 others sometimes change the module source without updating
1665 the version). With this option, such a "srcversion" field
1666 will be created for all modules. If unsure, say N.
1669 bool "Module signature verification"
1673 select ASYMMETRIC_KEY_TYPE
1674 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1675 select PUBLIC_KEY_ALGO_RSA
1678 select X509_CERTIFICATE_PARSER
1680 Check modules for valid signatures upon load: the signature
1681 is simply appended to the module. For more information see
1682 Documentation/module-signing.txt.
1684 !!!WARNING!!! If you enable this option, you MUST make sure that the
1685 module DOES NOT get stripped after being signed. This includes the
1686 debuginfo strip done by some packagers (such as rpmbuild) and
1687 inclusion into an initramfs that wants the module size reduced.
1689 config MODULE_SIG_FORCE
1690 bool "Require modules to be validly signed"
1691 depends on MODULE_SIG
1693 Reject unsigned modules or signed modules for which we don't have a
1694 key. Without this, such modules will simply taint the kernel.
1697 prompt "Which hash algorithm should modules be signed with?"
1698 depends on MODULE_SIG
1700 This determines which sort of hashing algorithm will be used during
1701 signature generation. This algorithm _must_ be built into the kernel
1702 directly so that signature verification can take place. It is not
1703 possible to load a signed module containing the algorithm to check
1704 the signature on that module.
1706 config MODULE_SIG_SHA1
1707 bool "Sign modules with SHA-1"
1710 config MODULE_SIG_SHA224
1711 bool "Sign modules with SHA-224"
1712 select CRYPTO_SHA256
1714 config MODULE_SIG_SHA256
1715 bool "Sign modules with SHA-256"
1716 select CRYPTO_SHA256
1718 config MODULE_SIG_SHA384
1719 bool "Sign modules with SHA-384"
1720 select CRYPTO_SHA512
1722 config MODULE_SIG_SHA512
1723 bool "Sign modules with SHA-512"
1724 select CRYPTO_SHA512
1730 config INIT_ALL_POSSIBLE
1733 Back when each arch used to define their own cpu_online_mask and
1734 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
1735 with all 1s, and others with all 0s. When they were centralised,
1736 it was better to provide this option than to break all the archs
1737 and have several arch maintainers pursuing me down dark alleys.
1742 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1744 Need stop_machine() primitive.
1746 source "block/Kconfig"
1748 config PREEMPT_NOTIFIERS
1755 # Can be selected by architectures with broken toolchains
1756 # that get confused by correct const<->read_only section
1758 config BROKEN_RODATA
1764 Build a simple ASN.1 grammar compiler that produces a bytecode output
1765 that can be interpreted by the ASN.1 stream decoder and used to
1766 inform it as to what tags are to be expected in a stream and what
1767 functions to call on what tags.
1769 source "kernel/Kconfig.locks"
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