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
36 depends on BROKEN || !SMP
39 config INIT_ENV_ARG_LIMIT
44 Maximum of each of the number of arguments and environment
45 variables passed to init from the kernel command line.
49 string "Cross-compiler tool prefix"
51 Same as running 'make CROSS_COMPILE=prefix-' but stored for
52 default make runs in this kernel build directory. You don't
53 need to set this unless you want the configured kernel build
54 directory to select the cross-compiler automatically.
57 bool "Compile also drivers which will not load"
60 Some drivers can be compiled on a different platform than they are
61 intended to be run on. Despite they cannot be loaded there (or even
62 when they load they cannot be used due to missing HW support),
63 developers still, opposing to distributors, might want to build such
64 drivers to compile-test them.
66 If you are a developer and want to build everything available, say Y
67 here. If you are a user/distributor, say N here to exclude useless
68 drivers to be distributed.
71 string "Local version - append to kernel release"
73 Append an extra string to the end of your kernel version.
74 This will show up when you type uname, for example.
75 The string you set here will be appended after the contents of
76 any files with a filename matching localversion* in your
77 object and source tree, in that order. Your total string can
78 be a maximum of 64 characters.
80 config LOCALVERSION_AUTO
81 bool "Automatically append version information to the version string"
84 This will try to automatically determine if the current tree is a
85 release tree by looking for git tags that belong to the current
88 A string of the format -gxxxxxxxx will be added to the localversion
89 if a git-based tree is found. The string generated by this will be
90 appended after any matching localversion* files, and after the value
91 set in CONFIG_LOCALVERSION.
93 (The actual string used here is the first eight characters produced
94 by running the command:
96 $ git rev-parse --verify HEAD
98 which is done within the script "scripts/setlocalversion".)
100 config HAVE_KERNEL_GZIP
103 config HAVE_KERNEL_BZIP2
106 config HAVE_KERNEL_LZMA
109 config HAVE_KERNEL_XZ
112 config HAVE_KERNEL_LZO
115 config HAVE_KERNEL_LZ4
119 prompt "Kernel compression mode"
121 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4
123 The linux kernel is a kind of self-extracting executable.
124 Several compression algorithms are available, which differ
125 in efficiency, compression and decompression speed.
126 Compression speed is only relevant when building a kernel.
127 Decompression speed is relevant at each boot.
129 If you have any problems with bzip2 or lzma compressed
130 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
131 version of this functionality (bzip2 only), for 2.4, was
132 supplied by Christian Ludwig)
134 High compression options are mostly useful for users, who
135 are low on disk space (embedded systems), but for whom ram
138 If in doubt, select 'gzip'
142 depends on HAVE_KERNEL_GZIP
144 The old and tried gzip compression. It provides a good balance
145 between compression ratio and decompression speed.
149 depends on HAVE_KERNEL_BZIP2
151 Its compression ratio and speed is intermediate.
152 Decompression speed is slowest among the choices. The kernel
153 size is about 10% smaller with bzip2, in comparison to gzip.
154 Bzip2 uses a large amount of memory. For modern kernels you
155 will need at least 8MB RAM or more for booting.
159 depends on HAVE_KERNEL_LZMA
161 This compression algorithm's ratio is best. Decompression speed
162 is between gzip and bzip2. Compression is slowest.
163 The kernel size is about 33% smaller with LZMA in comparison to gzip.
167 depends on HAVE_KERNEL_XZ
169 XZ uses the LZMA2 algorithm and instruction set specific
170 BCJ filters which can improve compression ratio of executable
171 code. The size of the kernel is about 30% smaller with XZ in
172 comparison to gzip. On architectures for which there is a BCJ
173 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
174 will create a few percent smaller kernel than plain LZMA.
176 The speed is about the same as with LZMA: The decompression
177 speed of XZ is better than that of bzip2 but worse than gzip
178 and LZO. Compression is slow.
182 depends on HAVE_KERNEL_LZO
184 Its compression ratio is the poorest among the choices. The kernel
185 size is about 10% bigger than gzip; however its speed
186 (both compression and decompression) is the fastest.
190 depends on HAVE_KERNEL_LZ4
192 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
193 A preliminary version of LZ4 de/compression tool is available at
194 <https://code.google.com/p/lz4/>.
196 Its compression ratio is worse than LZO. The size of the kernel
197 is about 8% bigger than LZO. But the decompression speed is
202 config DEFAULT_HOSTNAME
203 string "Default hostname"
206 This option determines the default system hostname before userspace
207 calls sethostname(2). The kernel traditionally uses "(none)" here,
208 but you may wish to use a different default here to make a minimal
209 system more usable with less configuration.
212 bool "Support for paging of anonymous memory (swap)"
213 depends on MMU && BLOCK
216 This option allows you to choose whether you want to have support
217 for so called swap devices or swap files in your kernel that are
218 used to provide more virtual memory than the actual RAM present
219 in your computer. If unsure say Y.
224 Inter Process Communication is a suite of library functions and
225 system calls which let processes (running programs) synchronize and
226 exchange information. It is generally considered to be a good thing,
227 and some programs won't run unless you say Y here. In particular, if
228 you want to run the DOS emulator dosemu under Linux (read the
229 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
230 you'll need to say Y here.
232 You can find documentation about IPC with "info ipc" and also in
233 section 6.4 of the Linux Programmer's Guide, available from
234 <http://www.tldp.org/guides.html>.
236 config SYSVIPC_SYSCTL
243 bool "POSIX Message Queues"
246 POSIX variant of message queues is a part of IPC. In POSIX message
247 queues every message has a priority which decides about succession
248 of receiving it by a process. If you want to compile and run
249 programs written e.g. for Solaris with use of its POSIX message
250 queues (functions mq_*) say Y here.
252 POSIX message queues are visible as a filesystem called 'mqueue'
253 and can be mounted somewhere if you want to do filesystem
254 operations on message queues.
258 config POSIX_MQUEUE_SYSCTL
260 depends on POSIX_MQUEUE
265 bool "open by fhandle syscalls"
268 If you say Y here, a user level program will be able to map
269 file names to handle and then later use the handle for
270 different file system operations. This is useful in implementing
271 userspace file servers, which now track files using handles instead
272 of names. The handle would remain the same even if file names
273 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
277 bool "Auditing support"
280 Enable auditing infrastructure that can be used with another
281 kernel subsystem, such as SELinux (which requires this for
282 logging of avc messages output). Does not do system-call
283 auditing without CONFIG_AUDITSYSCALL.
286 bool "Enable system-call auditing support"
287 depends on AUDIT && (X86 || PARISC || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || (ARM && AEABI && !OABI_COMPAT))
288 default y if SECURITY_SELINUX
290 Enable low-overhead system-call auditing infrastructure that
291 can be used independently or with another kernel subsystem,
296 depends on AUDITSYSCALL
301 depends on AUDITSYSCALL
304 source "kernel/irq/Kconfig"
305 source "kernel/time/Kconfig"
307 menu "CPU/Task time and stats accounting"
309 config VIRT_CPU_ACCOUNTING
313 prompt "Cputime accounting"
314 default TICK_CPU_ACCOUNTING if !PPC64
315 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
317 # Kind of a stub config for the pure tick based cputime accounting
318 config TICK_CPU_ACCOUNTING
319 bool "Simple tick based cputime accounting"
320 depends on !S390 && !NO_HZ_FULL
322 This is the basic tick based cputime accounting that maintains
323 statistics about user, system and idle time spent on per jiffies
328 config VIRT_CPU_ACCOUNTING_NATIVE
329 bool "Deterministic task and CPU time accounting"
330 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
331 select VIRT_CPU_ACCOUNTING
333 Select this option to enable more accurate task and CPU time
334 accounting. This is done by reading a CPU counter on each
335 kernel entry and exit and on transitions within the kernel
336 between system, softirq and hardirq state, so there is a
337 small performance impact. In the case of s390 or IBM POWER > 5,
338 this also enables accounting of stolen time on logically-partitioned
341 config VIRT_CPU_ACCOUNTING_GEN
342 bool "Full dynticks CPU time accounting"
343 depends on HAVE_CONTEXT_TRACKING
344 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
345 select VIRT_CPU_ACCOUNTING
346 select CONTEXT_TRACKING
348 Select this option to enable task and CPU time accounting on full
349 dynticks systems. This accounting is implemented by watching every
350 kernel-user boundaries using the context tracking subsystem.
351 The accounting is thus performed at the expense of some significant
354 For now this is only useful if you are working on the full
355 dynticks subsystem development.
359 config IRQ_TIME_ACCOUNTING
360 bool "Fine granularity task level IRQ time accounting"
361 depends on HAVE_IRQ_TIME_ACCOUNTING && !NO_HZ_FULL
363 Select this option to enable fine granularity task irq time
364 accounting. This is done by reading a timestamp on each
365 transitions between softirq and hardirq state, so there can be a
366 small performance impact.
368 If in doubt, say N here.
372 config BSD_PROCESS_ACCT
373 bool "BSD Process Accounting"
375 If you say Y here, a user level program will be able to instruct the
376 kernel (via a special system call) to write process accounting
377 information to a file: whenever a process exits, information about
378 that process will be appended to the file by the kernel. The
379 information includes things such as creation time, owning user,
380 command name, memory usage, controlling terminal etc. (the complete
381 list is in the struct acct in <file:include/linux/acct.h>). It is
382 up to the user level program to do useful things with this
383 information. This is generally a good idea, so say Y.
385 config BSD_PROCESS_ACCT_V3
386 bool "BSD Process Accounting version 3 file format"
387 depends on BSD_PROCESS_ACCT
390 If you say Y here, the process accounting information is written
391 in a new file format that also logs the process IDs of each
392 process and it's parent. Note that this file format is incompatible
393 with previous v0/v1/v2 file formats, so you will need updated tools
394 for processing it. A preliminary version of these tools is available
395 at <http://www.gnu.org/software/acct/>.
398 bool "Export task/process statistics through netlink"
402 Export selected statistics for tasks/processes through the
403 generic netlink interface. Unlike BSD process accounting, the
404 statistics are available during the lifetime of tasks/processes as
405 responses to commands. Like BSD accounting, they are sent to user
410 config TASK_DELAY_ACCT
411 bool "Enable per-task delay accounting"
414 Collect information on time spent by a task waiting for system
415 resources like cpu, synchronous block I/O completion and swapping
416 in pages. Such statistics can help in setting a task's priorities
417 relative to other tasks for cpu, io, rss limits etc.
422 bool "Enable extended accounting over taskstats"
425 Collect extended task accounting data and send the data
426 to userland for processing over the taskstats interface.
430 config TASK_IO_ACCOUNTING
431 bool "Enable per-task storage I/O accounting"
432 depends on TASK_XACCT
434 Collect information on the number of bytes of storage I/O which this
439 endmenu # "CPU/Task time and stats accounting"
444 prompt "RCU Implementation"
448 bool "Tree-based hierarchical RCU"
449 depends on !PREEMPT && SMP
452 This option selects the RCU implementation that is
453 designed for very large SMP system with hundreds or
454 thousands of CPUs. It also scales down nicely to
457 config TREE_PREEMPT_RCU
458 bool "Preemptible tree-based hierarchical RCU"
462 This option selects the RCU implementation that is
463 designed for very large SMP systems with hundreds or
464 thousands of CPUs, but for which real-time response
465 is also required. It also scales down nicely to
468 Select this option if you are unsure.
471 bool "UP-only small-memory-footprint RCU"
472 depends on !PREEMPT && !SMP
474 This option selects the RCU implementation that is
475 designed for UP systems from which real-time response
476 is not required. This option greatly reduces the
477 memory footprint of RCU.
482 def_bool TREE_PREEMPT_RCU
484 This option enables preemptible-RCU code that is common between
485 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
487 config RCU_STALL_COMMON
488 def_bool ( TREE_RCU || TREE_PREEMPT_RCU || RCU_TRACE )
490 This option enables RCU CPU stall code that is common between
491 the TINY and TREE variants of RCU. The purpose is to allow
492 the tiny variants to disable RCU CPU stall warnings, while
493 making these warnings mandatory for the tree variants.
495 config CONTEXT_TRACKING
499 bool "Consider userspace as in RCU extended quiescent state"
500 depends on HAVE_CONTEXT_TRACKING && SMP
501 select CONTEXT_TRACKING
503 This option sets hooks on kernel / userspace boundaries and
504 puts RCU in extended quiescent state when the CPU runs in
505 userspace. It means that when a CPU runs in userspace, it is
506 excluded from the global RCU state machine and thus doesn't
507 try to keep the timer tick on for RCU.
509 Unless you want to hack and help the development of the full
510 dynticks mode, you shouldn't enable this option. It also
511 adds unnecessary overhead.
515 config CONTEXT_TRACKING_FORCE
516 bool "Force context tracking"
517 depends on CONTEXT_TRACKING
518 default y if !NO_HZ_FULL
520 The major pre-requirement for full dynticks to work is to
521 support the context tracking subsystem. But there are also
522 other dependencies to provide in order to make the full
525 This option stands for testing when an arch implements the
526 context tracking backend but doesn't yet fullfill all the
527 requirements to make the full dynticks feature working.
528 Without the full dynticks, there is no way to test the support
529 for context tracking and the subsystems that rely on it: RCU
530 userspace extended quiescent state and tickless cputime
531 accounting. This option copes with the absence of the full
532 dynticks subsystem by forcing the context tracking on all
535 Say Y only if you're working on the developpement of an
536 architecture backend for the context tracking.
538 Say N otherwise, this option brings an overhead that you
539 don't want in production.
543 int "Tree-based hierarchical RCU fanout value"
546 depends on TREE_RCU || TREE_PREEMPT_RCU
550 This option controls the fanout of hierarchical implementations
551 of RCU, allowing RCU to work efficiently on machines with
552 large numbers of CPUs. This value must be at least the fourth
553 root of NR_CPUS, which allows NR_CPUS to be insanely large.
554 The default value of RCU_FANOUT should be used for production
555 systems, but if you are stress-testing the RCU implementation
556 itself, small RCU_FANOUT values allow you to test large-system
557 code paths on small(er) systems.
559 Select a specific number if testing RCU itself.
560 Take the default if unsure.
562 config RCU_FANOUT_LEAF
563 int "Tree-based hierarchical RCU leaf-level fanout value"
564 range 2 RCU_FANOUT if 64BIT
565 range 2 RCU_FANOUT if !64BIT
566 depends on TREE_RCU || TREE_PREEMPT_RCU
569 This option controls the leaf-level fanout of hierarchical
570 implementations of RCU, and allows trading off cache misses
571 against lock contention. Systems that synchronize their
572 scheduling-clock interrupts for energy-efficiency reasons will
573 want the default because the smaller leaf-level fanout keeps
574 lock contention levels acceptably low. Very large systems
575 (hundreds or thousands of CPUs) will instead want to set this
576 value to the maximum value possible in order to reduce the
577 number of cache misses incurred during RCU's grace-period
578 initialization. These systems tend to run CPU-bound, and thus
579 are not helped by synchronized interrupts, and thus tend to
580 skew them, which reduces lock contention enough that large
581 leaf-level fanouts work well.
583 Select a specific number if testing RCU itself.
585 Select the maximum permissible value for large systems.
587 Take the default if unsure.
589 config RCU_FANOUT_EXACT
590 bool "Disable tree-based hierarchical RCU auto-balancing"
591 depends on TREE_RCU || TREE_PREEMPT_RCU
594 This option forces use of the exact RCU_FANOUT value specified,
595 regardless of imbalances in the hierarchy. This is useful for
596 testing RCU itself, and might one day be useful on systems with
597 strong NUMA behavior.
599 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
603 config RCU_FAST_NO_HZ
604 bool "Accelerate last non-dyntick-idle CPU's grace periods"
605 depends on NO_HZ_COMMON && SMP
608 This option permits CPUs to enter dynticks-idle state even if
609 they have RCU callbacks queued, and prevents RCU from waking
610 these CPUs up more than roughly once every four jiffies (by
611 default, you can adjust this using the rcutree.rcu_idle_gp_delay
612 parameter), thus improving energy efficiency. On the other
613 hand, this option increases the duration of RCU grace periods,
614 for example, slowing down synchronize_rcu().
616 Say Y if energy efficiency is critically important, and you
617 don't care about increased grace-period durations.
619 Say N if you are unsure.
621 config TREE_RCU_TRACE
622 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
625 This option provides tracing for the TREE_RCU and
626 TREE_PREEMPT_RCU implementations, permitting Makefile to
627 trivially select kernel/rcutree_trace.c.
630 bool "Enable RCU priority boosting"
631 depends on RT_MUTEXES && PREEMPT_RCU
634 This option boosts the priority of preempted RCU readers that
635 block the current preemptible RCU grace period for too long.
636 This option also prevents heavy loads from blocking RCU
637 callback invocation for all flavors of RCU.
639 Say Y here if you are working with real-time apps or heavy loads
640 Say N here if you are unsure.
642 config RCU_BOOST_PRIO
643 int "Real-time priority to boost RCU readers to"
648 This option specifies the real-time priority to which long-term
649 preempted RCU readers are to be boosted. If you are working
650 with a real-time application that has one or more CPU-bound
651 threads running at a real-time priority level, you should set
652 RCU_BOOST_PRIO to a priority higher then the highest-priority
653 real-time CPU-bound thread. The default RCU_BOOST_PRIO value
654 of 1 is appropriate in the common case, which is real-time
655 applications that do not have any CPU-bound threads.
657 Some real-time applications might not have a single real-time
658 thread that saturates a given CPU, but instead might have
659 multiple real-time threads that, taken together, fully utilize
660 that CPU. In this case, you should set RCU_BOOST_PRIO to
661 a priority higher than the lowest-priority thread that is
662 conspiring to prevent the CPU from running any non-real-time
663 tasks. For example, if one thread at priority 10 and another
664 thread at priority 5 are between themselves fully consuming
665 the CPU time on a given CPU, then RCU_BOOST_PRIO should be
666 set to priority 6 or higher.
668 Specify the real-time priority, or take the default if unsure.
670 config RCU_BOOST_DELAY
671 int "Milliseconds to delay boosting after RCU grace-period start"
676 This option specifies the time to wait after the beginning of
677 a given grace period before priority-boosting preempted RCU
678 readers blocking that grace period. Note that any RCU reader
679 blocking an expedited RCU grace period is boosted immediately.
681 Accept the default if unsure.
684 bool "Offload RCU callback processing from boot-selected CPUs"
685 depends on TREE_RCU || TREE_PREEMPT_RCU
688 Use this option to reduce OS jitter for aggressive HPC or
689 real-time workloads. It can also be used to offload RCU
690 callback invocation to energy-efficient CPUs in battery-powered
691 asymmetric multiprocessors.
693 This option offloads callback invocation from the set of
694 CPUs specified at boot time by the rcu_nocbs parameter.
695 For each such CPU, a kthread ("rcuox/N") will be created to
696 invoke callbacks, where the "N" is the CPU being offloaded,
697 and where the "x" is "b" for RCU-bh, "p" for RCU-preempt, and
698 "s" for RCU-sched. Nothing prevents this kthread from running
699 on the specified CPUs, but (1) the kthreads may be preempted
700 between each callback, and (2) affinity or cgroups can be used
701 to force the kthreads to run on whatever set of CPUs is desired.
703 Say Y here if you want to help to debug reduced OS jitter.
704 Say N here if you are unsure.
707 prompt "Build-forced no-CBs CPUs"
708 default RCU_NOCB_CPU_NONE
710 This option allows no-CBs CPUs (whose RCU callbacks are invoked
711 from kthreads rather than from softirq context) to be specified
712 at build time. Additional no-CBs CPUs may be specified by
713 the rcu_nocbs= boot parameter.
715 config RCU_NOCB_CPU_NONE
716 bool "No build_forced no-CBs CPUs"
717 depends on RCU_NOCB_CPU && !NO_HZ_FULL
719 This option does not force any of the CPUs to be no-CBs CPUs.
720 Only CPUs designated by the rcu_nocbs= boot parameter will be
721 no-CBs CPUs, whose RCU callbacks will be invoked by per-CPU
722 kthreads whose names begin with "rcuo". All other CPUs will
723 invoke their own RCU callbacks in softirq context.
725 Select this option if you want to choose no-CBs CPUs at
726 boot time, for example, to allow testing of different no-CBs
727 configurations without having to rebuild the kernel each time.
729 config RCU_NOCB_CPU_ZERO
730 bool "CPU 0 is a build_forced no-CBs CPU"
731 depends on RCU_NOCB_CPU && !NO_HZ_FULL
733 This option forces CPU 0 to be a no-CBs CPU, so that its RCU
734 callbacks are invoked by a per-CPU kthread whose name begins
735 with "rcuo". Additional CPUs may be designated as no-CBs
736 CPUs using the rcu_nocbs= boot parameter will be no-CBs CPUs.
737 All other CPUs will invoke their own RCU callbacks in softirq
740 Select this if CPU 0 needs to be a no-CBs CPU for real-time
741 or energy-efficiency reasons, but the real reason it exists
742 is to ensure that randconfig testing covers mixed systems.
744 config RCU_NOCB_CPU_ALL
745 bool "All CPUs are build_forced no-CBs CPUs"
746 depends on RCU_NOCB_CPU
748 This option forces all CPUs to be no-CBs CPUs. The rcu_nocbs=
749 boot parameter will be ignored. All CPUs' RCU callbacks will
750 be executed in the context of per-CPU rcuo kthreads created for
751 this purpose. Assuming that the kthreads whose names start with
752 "rcuo" are bound to "housekeeping" CPUs, this reduces OS jitter
753 on the remaining CPUs, but might decrease memory locality during
754 RCU-callback invocation, thus potentially degrading throughput.
756 Select this if all CPUs need to be no-CBs CPUs for real-time
757 or energy-efficiency reasons.
761 endmenu # "RCU Subsystem"
764 tristate "Kernel .config support"
766 This option enables the complete Linux kernel ".config" file
767 contents to be saved in the kernel. It provides documentation
768 of which kernel options are used in a running kernel or in an
769 on-disk kernel. This information can be extracted from the kernel
770 image file with the script scripts/extract-ikconfig and used as
771 input to rebuild the current kernel or to build another kernel.
772 It can also be extracted from a running kernel by reading
773 /proc/config.gz if enabled (below).
776 bool "Enable access to .config through /proc/config.gz"
777 depends on IKCONFIG && PROC_FS
779 This option enables access to the kernel configuration file
780 through /proc/config.gz.
783 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
787 Select kernel log buffer size as a power of 2.
797 # Architectures with an unreliable sched_clock() should select this:
799 config HAVE_UNSTABLE_SCHED_CLOCK
802 config GENERIC_SCHED_CLOCK
806 # For architectures that want to enable the support for NUMA-affine scheduler
809 config ARCH_SUPPORTS_NUMA_BALANCING
813 # For architectures that know their GCC __int128 support is sound
815 config ARCH_SUPPORTS_INT128
818 # For architectures that (ab)use NUMA to represent different memory regions
819 # all cpu-local but of different latencies, such as SuperH.
821 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
825 # For architectures that are willing to define _PAGE_NUMA as _PAGE_PROTNONE
826 config ARCH_WANTS_PROT_NUMA_PROT_NONE
829 config ARCH_USES_NUMA_PROT_NONE
832 depends on ARCH_WANTS_PROT_NUMA_PROT_NONE
833 depends on NUMA_BALANCING
835 config NUMA_BALANCING_DEFAULT_ENABLED
836 bool "Automatically enable NUMA aware memory/task placement"
838 depends on NUMA_BALANCING
840 If set, automatic NUMA balancing will be enabled if running on a NUMA
843 config NUMA_BALANCING
844 bool "Memory placement aware NUMA scheduler"
845 depends on ARCH_SUPPORTS_NUMA_BALANCING
846 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
847 depends on SMP && NUMA && MIGRATION
849 This option adds support for automatic NUMA aware memory/task placement.
850 The mechanism is quite primitive and is based on migrating memory when
851 it has references to the node the task is running on.
853 This system will be inactive on UMA systems.
856 boolean "Control Group support"
859 This option adds support for grouping sets of processes together, for
860 use with process control subsystems such as Cpusets, CFS, memory
861 controls or device isolation.
863 - Documentation/scheduler/sched-design-CFS.txt (CFS)
864 - Documentation/cgroups/ (features for grouping, isolation
865 and resource control)
872 bool "Example debug cgroup subsystem"
875 This option enables a simple cgroup subsystem that
876 exports useful debugging information about the cgroups
881 config CGROUP_FREEZER
882 bool "Freezer cgroup subsystem"
884 Provides a way to freeze and unfreeze all tasks in a
888 bool "Device controller for cgroups"
890 Provides a cgroup implementing whitelists for devices which
891 a process in the cgroup can mknod or open.
894 bool "Cpuset support"
896 This option will let you create and manage CPUSETs which
897 allow dynamically partitioning a system into sets of CPUs and
898 Memory Nodes and assigning tasks to run only within those sets.
899 This is primarily useful on large SMP or NUMA systems.
903 config PROC_PID_CPUSET
904 bool "Include legacy /proc/<pid>/cpuset file"
908 config CGROUP_CPUACCT
909 bool "Simple CPU accounting cgroup subsystem"
911 Provides a simple Resource Controller for monitoring the
912 total CPU consumed by the tasks in a cgroup.
914 config RESOURCE_COUNTERS
915 bool "Resource counters"
917 This option enables controller independent resource accounting
918 infrastructure that works with cgroups.
921 bool "Memory Resource Controller for Control Groups"
922 depends on RESOURCE_COUNTERS
925 Provides a memory resource controller that manages both anonymous
926 memory and page cache. (See Documentation/cgroups/memory.txt)
928 Note that setting this option increases fixed memory overhead
929 associated with each page of memory in the system. By this,
930 8(16)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
931 usage tracking struct at boot. Total amount of this is printed out
934 Only enable when you're ok with these trade offs and really
935 sure you need the memory resource controller. Even when you enable
936 this, you can set "cgroup_disable=memory" at your boot option to
937 disable memory resource controller and you can avoid overheads.
938 (and lose benefits of memory resource controller)
940 This config option also selects MM_OWNER config option, which
941 could in turn add some fork/exit overhead.
944 bool "Memory Resource Controller Swap Extension"
945 depends on MEMCG && SWAP
947 Add swap management feature to memory resource controller. When you
948 enable this, you can limit mem+swap usage per cgroup. In other words,
949 when you disable this, memory resource controller has no cares to
950 usage of swap...a process can exhaust all of the swap. This extension
951 is useful when you want to avoid exhaustion swap but this itself
952 adds more overheads and consumes memory for remembering information.
953 Especially if you use 32bit system or small memory system, please
954 be careful about enabling this. When memory resource controller
955 is disabled by boot option, this will be automatically disabled and
956 there will be no overhead from this. Even when you set this config=y,
957 if boot option "swapaccount=0" is set, swap will not be accounted.
958 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
959 size is 4096bytes, 512k per 1Gbytes of swap.
960 config MEMCG_SWAP_ENABLED
961 bool "Memory Resource Controller Swap Extension enabled by default"
962 depends on MEMCG_SWAP
965 Memory Resource Controller Swap Extension comes with its price in
966 a bigger memory consumption. General purpose distribution kernels
967 which want to enable the feature but keep it disabled by default
968 and let the user enable it by swapaccount=1 boot command line
969 parameter should have this option unselected.
970 For those who want to have the feature enabled by default should
971 select this option (if, for some reason, they need to disable it
972 then swapaccount=0 does the trick).
974 bool "Memory Resource Controller Kernel Memory accounting"
976 depends on SLUB || SLAB
978 The Kernel Memory extension for Memory Resource Controller can limit
979 the amount of memory used by kernel objects in the system. Those are
980 fundamentally different from the entities handled by the standard
981 Memory Controller, which are page-based, and can be swapped. Users of
982 the kmem extension can use it to guarantee that no group of processes
983 will ever exhaust kernel resources alone.
985 config CGROUP_HUGETLB
986 bool "HugeTLB Resource Controller for Control Groups"
987 depends on RESOURCE_COUNTERS && HUGETLB_PAGE
990 Provides a cgroup Resource Controller for HugeTLB pages.
991 When you enable this, you can put a per cgroup limit on HugeTLB usage.
992 The limit is enforced during page fault. Since HugeTLB doesn't
993 support page reclaim, enforcing the limit at page fault time implies
994 that, the application will get SIGBUS signal if it tries to access
995 HugeTLB pages beyond its limit. This requires the application to know
996 beforehand how much HugeTLB pages it would require for its use. The
997 control group is tracked in the third page lru pointer. This means
998 that we cannot use the controller with huge page less than 3 pages.
1001 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
1002 depends on PERF_EVENTS && CGROUPS
1004 This option extends the per-cpu mode to restrict monitoring to
1005 threads which belong to the cgroup specified and run on the
1010 menuconfig CGROUP_SCHED
1011 bool "Group CPU scheduler"
1014 This feature lets CPU scheduler recognize task groups and control CPU
1015 bandwidth allocation to such task groups. It uses cgroups to group
1019 config FAIR_GROUP_SCHED
1020 bool "Group scheduling for SCHED_OTHER"
1021 depends on CGROUP_SCHED
1022 default CGROUP_SCHED
1024 config CFS_BANDWIDTH
1025 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
1026 depends on FAIR_GROUP_SCHED
1029 This option allows users to define CPU bandwidth rates (limits) for
1030 tasks running within the fair group scheduler. Groups with no limit
1031 set are considered to be unconstrained and will run with no
1033 See tip/Documentation/scheduler/sched-bwc.txt for more information.
1035 config RT_GROUP_SCHED
1036 bool "Group scheduling for SCHED_RR/FIFO"
1037 depends on CGROUP_SCHED
1040 This feature lets you explicitly allocate real CPU bandwidth
1041 to task groups. If enabled, it will also make it impossible to
1042 schedule realtime tasks for non-root users until you allocate
1043 realtime bandwidth for them.
1044 See Documentation/scheduler/sched-rt-group.txt for more information.
1049 bool "Block IO controller"
1053 Generic block IO controller cgroup interface. This is the common
1054 cgroup interface which should be used by various IO controlling
1057 Currently, CFQ IO scheduler uses it to recognize task groups and
1058 control disk bandwidth allocation (proportional time slice allocation)
1059 to such task groups. It is also used by bio throttling logic in
1060 block layer to implement upper limit in IO rates on a device.
1062 This option only enables generic Block IO controller infrastructure.
1063 One needs to also enable actual IO controlling logic/policy. For
1064 enabling proportional weight division of disk bandwidth in CFQ, set
1065 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1066 CONFIG_BLK_DEV_THROTTLING=y.
1068 See Documentation/cgroups/blkio-controller.txt for more information.
1070 config DEBUG_BLK_CGROUP
1071 bool "Enable Block IO controller debugging"
1072 depends on BLK_CGROUP
1075 Enable some debugging help. Currently it exports additional stat
1076 files in a cgroup which can be useful for debugging.
1080 config CHECKPOINT_RESTORE
1081 bool "Checkpoint/restore support" if EXPERT
1084 Enables additional kernel features in a sake of checkpoint/restore.
1085 In particular it adds auxiliary prctl codes to setup process text,
1086 data and heap segment sizes, and a few additional /proc filesystem
1089 If unsure, say N here.
1091 menuconfig NAMESPACES
1092 bool "Namespaces support" if EXPERT
1095 Provides the way to make tasks work with different objects using
1096 the same id. For example same IPC id may refer to different objects
1097 or same user id or pid may refer to different tasks when used in
1098 different namespaces.
1103 bool "UTS namespace"
1106 In this namespace tasks see different info provided with the
1110 bool "IPC namespace"
1111 depends on (SYSVIPC || POSIX_MQUEUE)
1114 In this namespace tasks work with IPC ids which correspond to
1115 different IPC objects in different namespaces.
1118 bool "User namespace"
1119 select UIDGID_STRICT_TYPE_CHECKS
1123 This allows containers, i.e. vservers, to use user namespaces
1124 to provide different user info for different servers.
1126 When user namespaces are enabled in the kernel it is
1127 recommended that the MEMCG and MEMCG_KMEM options also be
1128 enabled and that user-space use the memory control groups to
1129 limit the amount of memory a memory unprivileged users can
1135 bool "PID Namespaces"
1138 Support process id namespaces. This allows having multiple
1139 processes with the same pid as long as they are in different
1140 pid namespaces. This is a building block of containers.
1143 bool "Network namespace"
1147 Allow user space to create what appear to be multiple instances
1148 of the network stack.
1152 config UIDGID_STRICT_TYPE_CHECKS
1153 bool "Require conversions between uid/gids and their internal representation"
1156 While the nececessary conversions are being added to all subsystems this option allows
1157 the code to continue to build for unconverted subsystems.
1159 Say Y here if you want the strict type checking enabled
1161 config SCHED_AUTOGROUP
1162 bool "Automatic process group scheduling"
1166 select FAIR_GROUP_SCHED
1168 This option optimizes the scheduler for common desktop workloads by
1169 automatically creating and populating task groups. This separation
1170 of workloads isolates aggressive CPU burners (like build jobs) from
1171 desktop applications. Task group autogeneration is currently based
1177 config SYSFS_DEPRECATED
1178 bool "Enable deprecated sysfs features to support old userspace tools"
1182 This option adds code that switches the layout of the "block" class
1183 devices, to not show up in /sys/class/block/, but only in
1186 This switch is only active when the sysfs.deprecated=1 boot option is
1187 passed or the SYSFS_DEPRECATED_V2 option is set.
1189 This option allows new kernels to run on old distributions and tools,
1190 which might get confused by /sys/class/block/. Since 2007/2008 all
1191 major distributions and tools handle this just fine.
1193 Recent distributions and userspace tools after 2009/2010 depend on
1194 the existence of /sys/class/block/, and will not work with this
1197 Only if you are using a new kernel on an old distribution, you might
1200 config SYSFS_DEPRECATED_V2
1201 bool "Enable deprecated sysfs features by default"
1204 depends on SYSFS_DEPRECATED
1206 Enable deprecated sysfs by default.
1208 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1211 Only if you are using a new kernel on an old distribution, you might
1212 need to say Y here. Even then, odds are you would not need it
1213 enabled, you can always pass the boot option if absolutely necessary.
1216 bool "Kernel->user space relay support (formerly relayfs)"
1218 This option enables support for relay interface support in
1219 certain file systems (such as debugfs).
1220 It is designed to provide an efficient mechanism for tools and
1221 facilities to relay large amounts of data from kernel space to
1226 config BLK_DEV_INITRD
1227 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1228 depends on BROKEN || !FRV
1230 The initial RAM filesystem is a ramfs which is loaded by the
1231 boot loader (loadlin or lilo) and that is mounted as root
1232 before the normal boot procedure. It is typically used to
1233 load modules needed to mount the "real" root file system,
1234 etc. See <file:Documentation/initrd.txt> for details.
1236 If RAM disk support (BLK_DEV_RAM) is also included, this
1237 also enables initial RAM disk (initrd) support and adds
1238 15 Kbytes (more on some other architectures) to the kernel size.
1244 source "usr/Kconfig"
1248 config CC_OPTIMIZE_FOR_SIZE
1249 bool "Optimize for size"
1251 Enabling this option will pass "-Os" instead of "-O2" to gcc
1252 resulting in a smaller kernel.
1265 config SYSCTL_EXCEPTION_TRACE
1268 Enable support for /proc/sys/debug/exception-trace.
1270 config SYSCTL_ARCH_UNALIGN_NO_WARN
1273 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1274 Allows arch to define/use @no_unaligned_warning to possibly warn
1275 about unaligned access emulation going on under the hood.
1277 config SYSCTL_ARCH_UNALIGN_ALLOW
1280 Enable support for /proc/sys/kernel/unaligned-trap
1281 Allows arches to define/use @unaligned_enabled to runtime toggle
1282 the unaligned access emulation.
1283 see arch/parisc/kernel/unaligned.c for reference
1285 config HAVE_PCSPKR_PLATFORM
1289 bool "Configure standard kernel features (expert users)"
1290 # Unhide debug options, to make the on-by-default options visible
1293 This option allows certain base kernel options and settings
1294 to be disabled or tweaked. This is for specialized
1295 environments which can tolerate a "non-standard" kernel.
1296 Only use this if you really know what you are doing.
1299 bool "Enable 16-bit UID system calls" if EXPERT
1300 depends on HAVE_UID16
1303 This enables the legacy 16-bit UID syscall wrappers.
1305 config SYSCTL_SYSCALL
1306 bool "Sysctl syscall support" if EXPERT
1307 depends on PROC_SYSCTL
1311 sys_sysctl uses binary paths that have been found challenging
1312 to properly maintain and use. The interface in /proc/sys
1313 using paths with ascii names is now the primary path to this
1316 Almost nothing using the binary sysctl interface so if you are
1317 trying to save some space it is probably safe to disable this,
1318 making your kernel marginally smaller.
1320 If unsure say N here.
1323 bool "Load all symbols for debugging/ksymoops" if EXPERT
1326 Say Y here to let the kernel print out symbolic crash information and
1327 symbolic stack backtraces. This increases the size of the kernel
1328 somewhat, as all symbols have to be loaded into the kernel image.
1331 bool "Include all symbols in kallsyms"
1332 depends on DEBUG_KERNEL && KALLSYMS
1334 Normally kallsyms only contains the symbols of functions for nicer
1335 OOPS messages and backtraces (i.e., symbols from the text and inittext
1336 sections). This is sufficient for most cases. And only in very rare
1337 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1338 names of variables from the data sections, etc).
1340 This option makes sure that all symbols are loaded into the kernel
1341 image (i.e., symbols from all sections) in cost of increased kernel
1342 size (depending on the kernel configuration, it may be 300KiB or
1343 something like this).
1345 Say N unless you really need all symbols.
1349 bool "Enable support for printk" if EXPERT
1352 This option enables normal printk support. Removing it
1353 eliminates most of the message strings from the kernel image
1354 and makes the kernel more or less silent. As this makes it
1355 very difficult to diagnose system problems, saying N here is
1356 strongly discouraged.
1359 bool "BUG() support" if EXPERT
1362 Disabling this option eliminates support for BUG and WARN, reducing
1363 the size of your kernel image and potentially quietly ignoring
1364 numerous fatal conditions. You should only consider disabling this
1365 option for embedded systems with no facilities for reporting errors.
1371 bool "Enable ELF core dumps" if EXPERT
1373 Enable support for generating core dumps. Disabling saves about 4k.
1376 config PCSPKR_PLATFORM
1377 bool "Enable PC-Speaker support" if EXPERT
1378 depends on HAVE_PCSPKR_PLATFORM
1382 This option allows to disable the internal PC-Speaker
1383 support, saving some memory.
1387 bool "Enable full-sized data structures for core" if EXPERT
1389 Disabling this option reduces the size of miscellaneous core
1390 kernel data structures. This saves memory on small machines,
1391 but may reduce performance.
1394 bool "Enable futex support" if EXPERT
1398 Disabling this option will cause the kernel to be built without
1399 support for "fast userspace mutexes". The resulting kernel may not
1400 run glibc-based applications correctly.
1403 bool "Enable eventpoll support" if EXPERT
1407 Disabling this option will cause the kernel to be built without
1408 support for epoll family of system calls.
1411 bool "Enable signalfd() system call" if EXPERT
1415 Enable the signalfd() system call that allows to receive signals
1416 on a file descriptor.
1421 bool "Enable timerfd() system call" if EXPERT
1425 Enable the timerfd() system call that allows to receive timer
1426 events on a file descriptor.
1431 bool "Enable eventfd() system call" if EXPERT
1435 Enable the eventfd() system call that allows to receive both
1436 kernel notification (ie. KAIO) or userspace notifications.
1441 bool "Use full shmem filesystem" if EXPERT
1445 The shmem is an internal filesystem used to manage shared memory.
1446 It is backed by swap and manages resource limits. It is also exported
1447 to userspace as tmpfs if TMPFS is enabled. Disabling this
1448 option replaces shmem and tmpfs with the much simpler ramfs code,
1449 which may be appropriate on small systems without swap.
1452 bool "Enable AIO support" if EXPERT
1455 This option enables POSIX asynchronous I/O which may by used
1456 by some high performance threaded applications. Disabling
1457 this option saves about 7k.
1461 bool "Enable PCI quirk workarounds" if EXPERT
1464 This enables workarounds for various PCI chipset
1465 bugs/quirks. Disable this only if your target machine is
1466 unaffected by PCI quirks.
1469 bool "Embedded system"
1472 This option should be enabled if compiling the kernel for
1473 an embedded system so certain expert options are available
1476 config HAVE_PERF_EVENTS
1479 See tools/perf/design.txt for details.
1481 config PERF_USE_VMALLOC
1484 See tools/perf/design.txt for details
1486 menu "Kernel Performance Events And Counters"
1489 bool "Kernel performance events and counters"
1490 default y if PROFILING
1491 depends on HAVE_PERF_EVENTS
1495 Enable kernel support for various performance events provided
1496 by software and hardware.
1498 Software events are supported either built-in or via the
1499 use of generic tracepoints.
1501 Most modern CPUs support performance events via performance
1502 counter registers. These registers count the number of certain
1503 types of hw events: such as instructions executed, cachemisses
1504 suffered, or branches mis-predicted - without slowing down the
1505 kernel or applications. These registers can also trigger interrupts
1506 when a threshold number of events have passed - and can thus be
1507 used to profile the code that runs on that CPU.
1509 The Linux Performance Event subsystem provides an abstraction of
1510 these software and hardware event capabilities, available via a
1511 system call and used by the "perf" utility in tools/perf/. It
1512 provides per task and per CPU counters, and it provides event
1513 capabilities on top of those.
1517 config DEBUG_PERF_USE_VMALLOC
1519 bool "Debug: use vmalloc to back perf mmap() buffers"
1520 depends on PERF_EVENTS && DEBUG_KERNEL
1521 select PERF_USE_VMALLOC
1523 Use vmalloc memory to back perf mmap() buffers.
1525 Mostly useful for debugging the vmalloc code on platforms
1526 that don't require it.
1532 config VM_EVENT_COUNTERS
1534 bool "Enable VM event counters for /proc/vmstat" if EXPERT
1536 VM event counters are needed for event counts to be shown.
1537 This option allows the disabling of the VM event counters
1538 on EXPERT systems. /proc/vmstat will only show page counts
1539 if VM event counters are disabled.
1543 bool "Enable SLUB debugging support" if EXPERT
1544 depends on SLUB && SYSFS
1546 SLUB has extensive debug support features. Disabling these can
1547 result in significant savings in code size. This also disables
1548 SLUB sysfs support. /sys/slab will not exist and there will be
1549 no support for cache validation etc.
1552 bool "Disable heap randomization"
1555 Randomizing heap placement makes heap exploits harder, but it
1556 also breaks ancient binaries (including anything libc5 based).
1557 This option changes the bootup default to heap randomization
1558 disabled, and can be overridden at runtime by setting
1559 /proc/sys/kernel/randomize_va_space to 2.
1561 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1564 prompt "Choose SLAB allocator"
1567 This option allows to select a slab allocator.
1572 The regular slab allocator that is established and known to work
1573 well in all environments. It organizes cache hot objects in
1574 per cpu and per node queues.
1577 bool "SLUB (Unqueued Allocator)"
1579 SLUB is a slab allocator that minimizes cache line usage
1580 instead of managing queues of cached objects (SLAB approach).
1581 Per cpu caching is realized using slabs of objects instead
1582 of queues of objects. SLUB can use memory efficiently
1583 and has enhanced diagnostics. SLUB is the default choice for
1588 bool "SLOB (Simple Allocator)"
1590 SLOB replaces the stock allocator with a drastically simpler
1591 allocator. SLOB is generally more space efficient but
1592 does not perform as well on large systems.
1596 config SLUB_CPU_PARTIAL
1598 depends on SLUB && SMP
1599 bool "SLUB per cpu partial cache"
1601 Per cpu partial caches accellerate objects allocation and freeing
1602 that is local to a processor at the price of more indeterminism
1603 in the latency of the free. On overflow these caches will be cleared
1604 which requires the taking of locks that may cause latency spikes.
1605 Typically one would choose no for a realtime system.
1607 config MMAP_ALLOW_UNINITIALIZED
1608 bool "Allow mmapped anonymous memory to be uninitialized"
1609 depends on EXPERT && !MMU
1612 Normally, and according to the Linux spec, anonymous memory obtained
1613 from mmap() has it's contents cleared before it is passed to
1614 userspace. Enabling this config option allows you to request that
1615 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1616 providing a huge performance boost. If this option is not enabled,
1617 then the flag will be ignored.
1619 This is taken advantage of by uClibc's malloc(), and also by
1620 ELF-FDPIC binfmt's brk and stack allocator.
1622 Because of the obvious security issues, this option should only be
1623 enabled on embedded devices where you control what is run in
1624 userspace. Since that isn't generally a problem on no-MMU systems,
1625 it is normally safe to say Y here.
1627 See Documentation/nommu-mmap.txt for more information.
1630 bool "Profiling support"
1632 Say Y here to enable the extended profiling support mechanisms used
1633 by profilers such as OProfile.
1636 # Place an empty function call at each tracepoint site. Can be
1637 # dynamically changed for a probe function.
1642 source "arch/Kconfig"
1644 endmenu # General setup
1646 config HAVE_GENERIC_DMA_COHERENT
1653 depends on SLAB || SLUB_DEBUG
1661 default 0 if BASE_FULL
1662 default 1 if !BASE_FULL
1664 config SYSTEM_TRUSTED_KEYRING
1665 bool "Provide system-wide ring of trusted keys"
1668 Provide a system keyring to which trusted keys can be added. Keys in
1669 the keyring are considered to be trusted. Keys may be added at will
1670 by the kernel from compiled-in data and from hardware key stores, but
1671 userspace may only add extra keys if those keys can be verified by
1672 keys already in the keyring.
1674 Keys in this keyring are used by module signature checking.
1677 bool "Enable loadable module support"
1680 Kernel modules are small pieces of compiled code which can
1681 be inserted in the running kernel, rather than being
1682 permanently built into the kernel. You use the "modprobe"
1683 tool to add (and sometimes remove) them. If you say Y here,
1684 many parts of the kernel can be built as modules (by
1685 answering M instead of Y where indicated): this is most
1686 useful for infrequently used options which are not required
1687 for booting. For more information, see the man pages for
1688 modprobe, lsmod, modinfo, insmod and rmmod.
1690 If you say Y here, you will need to run "make
1691 modules_install" to put the modules under /lib/modules/
1692 where modprobe can find them (you may need to be root to do
1699 config MODULE_FORCE_LOAD
1700 bool "Forced module loading"
1703 Allow loading of modules without version information (ie. modprobe
1704 --force). Forced module loading sets the 'F' (forced) taint flag and
1705 is usually a really bad idea.
1707 config MODULE_UNLOAD
1708 bool "Module unloading"
1710 Without this option you will not be able to unload any
1711 modules (note that some modules may not be unloadable
1712 anyway), which makes your kernel smaller, faster
1713 and simpler. If unsure, say Y.
1715 config MODULE_FORCE_UNLOAD
1716 bool "Forced module unloading"
1717 depends on MODULE_UNLOAD
1719 This option allows you to force a module to unload, even if the
1720 kernel believes it is unsafe: the kernel will remove the module
1721 without waiting for anyone to stop using it (using the -f option to
1722 rmmod). This is mainly for kernel developers and desperate users.
1726 bool "Module versioning support"
1728 Usually, you have to use modules compiled with your kernel.
1729 Saying Y here makes it sometimes possible to use modules
1730 compiled for different kernels, by adding enough information
1731 to the modules to (hopefully) spot any changes which would
1732 make them incompatible with the kernel you are running. If
1735 config MODULE_SRCVERSION_ALL
1736 bool "Source checksum for all modules"
1738 Modules which contain a MODULE_VERSION get an extra "srcversion"
1739 field inserted into their modinfo section, which contains a
1740 sum of the source files which made it. This helps maintainers
1741 see exactly which source was used to build a module (since
1742 others sometimes change the module source without updating
1743 the version). With this option, such a "srcversion" field
1744 will be created for all modules. If unsure, say N.
1747 bool "Module signature verification"
1749 select SYSTEM_TRUSTED_KEYRING
1752 select ASYMMETRIC_KEY_TYPE
1753 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1754 select PUBLIC_KEY_ALGO_RSA
1757 select X509_CERTIFICATE_PARSER
1759 Check modules for valid signatures upon load: the signature
1760 is simply appended to the module. For more information see
1761 Documentation/module-signing.txt.
1763 !!!WARNING!!! If you enable this option, you MUST make sure that the
1764 module DOES NOT get stripped after being signed. This includes the
1765 debuginfo strip done by some packagers (such as rpmbuild) and
1766 inclusion into an initramfs that wants the module size reduced.
1768 config MODULE_SIG_FORCE
1769 bool "Require modules to be validly signed"
1770 depends on MODULE_SIG
1772 Reject unsigned modules or signed modules for which we don't have a
1773 key. Without this, such modules will simply taint the kernel.
1775 config MODULE_SIG_ALL
1776 bool "Automatically sign all modules"
1778 depends on MODULE_SIG
1780 Sign all modules during make modules_install. Without this option,
1781 modules must be signed manually, using the scripts/sign-file tool.
1783 comment "Do not forget to sign required modules with scripts/sign-file"
1784 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
1787 prompt "Which hash algorithm should modules be signed with?"
1788 depends on MODULE_SIG
1790 This determines which sort of hashing algorithm will be used during
1791 signature generation. This algorithm _must_ be built into the kernel
1792 directly so that signature verification can take place. It is not
1793 possible to load a signed module containing the algorithm to check
1794 the signature on that module.
1796 config MODULE_SIG_SHA1
1797 bool "Sign modules with SHA-1"
1800 config MODULE_SIG_SHA224
1801 bool "Sign modules with SHA-224"
1802 select CRYPTO_SHA256
1804 config MODULE_SIG_SHA256
1805 bool "Sign modules with SHA-256"
1806 select CRYPTO_SHA256
1808 config MODULE_SIG_SHA384
1809 bool "Sign modules with SHA-384"
1810 select CRYPTO_SHA512
1812 config MODULE_SIG_SHA512
1813 bool "Sign modules with SHA-512"
1814 select CRYPTO_SHA512
1818 config MODULE_SIG_HASH
1820 depends on MODULE_SIG
1821 default "sha1" if MODULE_SIG_SHA1
1822 default "sha224" if MODULE_SIG_SHA224
1823 default "sha256" if MODULE_SIG_SHA256
1824 default "sha384" if MODULE_SIG_SHA384
1825 default "sha512" if MODULE_SIG_SHA512
1829 config INIT_ALL_POSSIBLE
1832 Back when each arch used to define their own cpu_online_mask and
1833 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
1834 with all 1s, and others with all 0s. When they were centralised,
1835 it was better to provide this option than to break all the archs
1836 and have several arch maintainers pursuing me down dark alleys.
1841 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1843 Need stop_machine() primitive.
1845 source "block/Kconfig"
1847 config PREEMPT_NOTIFIERS
1854 # Can be selected by architectures with broken toolchains
1855 # that get confused by correct const<->read_only section
1857 config BROKEN_RODATA
1863 Build a simple ASN.1 grammar compiler that produces a bytecode output
1864 that can be interpreted by the ASN.1 stream decoder and used to
1865 inform it as to what tags are to be expected in a stream and what
1866 functions to call on what tags.
1868 source "kernel/Kconfig.locks"
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