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 config AUDIT_LOGINUID_IMMUTABLE
305 bool "Make audit loginuid immutable"
308 The config option toggles if a task setting its loginuid requires
309 CAP_SYS_AUDITCONTROL or if that task should require no special permissions
310 but should instead only allow setting its loginuid if it was never
311 previously set. On systems which use systemd or a similar central
312 process to restart login services this should be set to true. On older
313 systems in which an admin would typically have to directly stop and
314 start processes this should be set to false. Setting this to true allows
315 one to drop potentially dangerous capabilites from the login tasks,
316 but may not be backwards compatible with older init systems.
318 source "kernel/irq/Kconfig"
319 source "kernel/time/Kconfig"
321 menu "CPU/Task time and stats accounting"
323 config VIRT_CPU_ACCOUNTING
327 prompt "Cputime accounting"
328 default TICK_CPU_ACCOUNTING if !PPC64
329 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
331 # Kind of a stub config for the pure tick based cputime accounting
332 config TICK_CPU_ACCOUNTING
333 bool "Simple tick based cputime accounting"
334 depends on !S390 && !NO_HZ_FULL
336 This is the basic tick based cputime accounting that maintains
337 statistics about user, system and idle time spent on per jiffies
342 config VIRT_CPU_ACCOUNTING_NATIVE
343 bool "Deterministic task and CPU time accounting"
344 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
345 select VIRT_CPU_ACCOUNTING
347 Select this option to enable more accurate task and CPU time
348 accounting. This is done by reading a CPU counter on each
349 kernel entry and exit and on transitions within the kernel
350 between system, softirq and hardirq state, so there is a
351 small performance impact. In the case of s390 or IBM POWER > 5,
352 this also enables accounting of stolen time on logically-partitioned
355 config VIRT_CPU_ACCOUNTING_GEN
356 bool "Full dynticks CPU time accounting"
357 depends on HAVE_CONTEXT_TRACKING
358 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
359 select VIRT_CPU_ACCOUNTING
360 select CONTEXT_TRACKING
362 Select this option to enable task and CPU time accounting on full
363 dynticks systems. This accounting is implemented by watching every
364 kernel-user boundaries using the context tracking subsystem.
365 The accounting is thus performed at the expense of some significant
368 For now this is only useful if you are working on the full
369 dynticks subsystem development.
373 config IRQ_TIME_ACCOUNTING
374 bool "Fine granularity task level IRQ time accounting"
375 depends on HAVE_IRQ_TIME_ACCOUNTING && !NO_HZ_FULL
377 Select this option to enable fine granularity task irq time
378 accounting. This is done by reading a timestamp on each
379 transitions between softirq and hardirq state, so there can be a
380 small performance impact.
382 If in doubt, say N here.
386 config BSD_PROCESS_ACCT
387 bool "BSD Process Accounting"
389 If you say Y here, a user level program will be able to instruct the
390 kernel (via a special system call) to write process accounting
391 information to a file: whenever a process exits, information about
392 that process will be appended to the file by the kernel. The
393 information includes things such as creation time, owning user,
394 command name, memory usage, controlling terminal etc. (the complete
395 list is in the struct acct in <file:include/linux/acct.h>). It is
396 up to the user level program to do useful things with this
397 information. This is generally a good idea, so say Y.
399 config BSD_PROCESS_ACCT_V3
400 bool "BSD Process Accounting version 3 file format"
401 depends on BSD_PROCESS_ACCT
404 If you say Y here, the process accounting information is written
405 in a new file format that also logs the process IDs of each
406 process and it's parent. Note that this file format is incompatible
407 with previous v0/v1/v2 file formats, so you will need updated tools
408 for processing it. A preliminary version of these tools is available
409 at <http://www.gnu.org/software/acct/>.
412 bool "Export task/process statistics through netlink"
416 Export selected statistics for tasks/processes through the
417 generic netlink interface. Unlike BSD process accounting, the
418 statistics are available during the lifetime of tasks/processes as
419 responses to commands. Like BSD accounting, they are sent to user
424 config TASK_DELAY_ACCT
425 bool "Enable per-task delay accounting"
428 Collect information on time spent by a task waiting for system
429 resources like cpu, synchronous block I/O completion and swapping
430 in pages. Such statistics can help in setting a task's priorities
431 relative to other tasks for cpu, io, rss limits etc.
436 bool "Enable extended accounting over taskstats"
439 Collect extended task accounting data and send the data
440 to userland for processing over the taskstats interface.
444 config TASK_IO_ACCOUNTING
445 bool "Enable per-task storage I/O accounting"
446 depends on TASK_XACCT
448 Collect information on the number of bytes of storage I/O which this
453 endmenu # "CPU/Task time and stats accounting"
458 prompt "RCU Implementation"
462 bool "Tree-based hierarchical RCU"
463 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"
476 This option selects the RCU implementation that is
477 designed for very large SMP systems with hundreds or
478 thousands of CPUs, but for which real-time response
479 is also required. It also scales down nicely to
482 Select this option if you are unsure.
485 bool "UP-only small-memory-footprint RCU"
486 depends on !PREEMPT && !SMP
488 This option selects the RCU implementation that is
489 designed for UP systems from which real-time response
490 is not required. This option greatly reduces the
491 memory footprint of RCU.
496 def_bool TREE_PREEMPT_RCU
498 This option enables preemptible-RCU code that is common between
499 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
501 config RCU_STALL_COMMON
502 def_bool ( TREE_RCU || TREE_PREEMPT_RCU || RCU_TRACE )
504 This option enables RCU CPU stall code that is common between
505 the TINY and TREE variants of RCU. The purpose is to allow
506 the tiny variants to disable RCU CPU stall warnings, while
507 making these warnings mandatory for the tree variants.
509 config CONTEXT_TRACKING
513 bool "Consider userspace as in RCU extended quiescent state"
514 depends on HAVE_CONTEXT_TRACKING && SMP
515 select CONTEXT_TRACKING
517 This option sets hooks on kernel / userspace boundaries and
518 puts RCU in extended quiescent state when the CPU runs in
519 userspace. It means that when a CPU runs in userspace, it is
520 excluded from the global RCU state machine and thus doesn't
521 try to keep the timer tick on for RCU.
523 Unless you want to hack and help the development of the full
524 dynticks mode, you shouldn't enable this option. It also
525 adds unnecessary overhead.
529 config CONTEXT_TRACKING_FORCE
530 bool "Force context tracking"
531 depends on CONTEXT_TRACKING
532 default y if !NO_HZ_FULL
534 The major pre-requirement for full dynticks to work is to
535 support the context tracking subsystem. But there are also
536 other dependencies to provide in order to make the full
539 This option stands for testing when an arch implements the
540 context tracking backend but doesn't yet fullfill all the
541 requirements to make the full dynticks feature working.
542 Without the full dynticks, there is no way to test the support
543 for context tracking and the subsystems that rely on it: RCU
544 userspace extended quiescent state and tickless cputime
545 accounting. This option copes with the absence of the full
546 dynticks subsystem by forcing the context tracking on all
549 Say Y only if you're working on the developpement of an
550 architecture backend for the context tracking.
552 Say N otherwise, this option brings an overhead that you
553 don't want in production.
557 int "Tree-based hierarchical RCU fanout value"
560 depends on TREE_RCU || TREE_PREEMPT_RCU
564 This option controls the fanout of hierarchical implementations
565 of RCU, allowing RCU to work efficiently on machines with
566 large numbers of CPUs. This value must be at least the fourth
567 root of NR_CPUS, which allows NR_CPUS to be insanely large.
568 The default value of RCU_FANOUT should be used for production
569 systems, but if you are stress-testing the RCU implementation
570 itself, small RCU_FANOUT values allow you to test large-system
571 code paths on small(er) systems.
573 Select a specific number if testing RCU itself.
574 Take the default if unsure.
576 config RCU_FANOUT_LEAF
577 int "Tree-based hierarchical RCU leaf-level fanout value"
578 range 2 RCU_FANOUT if 64BIT
579 range 2 RCU_FANOUT if !64BIT
580 depends on TREE_RCU || TREE_PREEMPT_RCU
583 This option controls the leaf-level fanout of hierarchical
584 implementations of RCU, and allows trading off cache misses
585 against lock contention. Systems that synchronize their
586 scheduling-clock interrupts for energy-efficiency reasons will
587 want the default because the smaller leaf-level fanout keeps
588 lock contention levels acceptably low. Very large systems
589 (hundreds or thousands of CPUs) will instead want to set this
590 value to the maximum value possible in order to reduce the
591 number of cache misses incurred during RCU's grace-period
592 initialization. These systems tend to run CPU-bound, and thus
593 are not helped by synchronized interrupts, and thus tend to
594 skew them, which reduces lock contention enough that large
595 leaf-level fanouts work well.
597 Select a specific number if testing RCU itself.
599 Select the maximum permissible value for large systems.
601 Take the default if unsure.
603 config RCU_FANOUT_EXACT
604 bool "Disable tree-based hierarchical RCU auto-balancing"
605 depends on TREE_RCU || TREE_PREEMPT_RCU
608 This option forces use of the exact RCU_FANOUT value specified,
609 regardless of imbalances in the hierarchy. This is useful for
610 testing RCU itself, and might one day be useful on systems with
611 strong NUMA behavior.
613 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
617 config RCU_FAST_NO_HZ
618 bool "Accelerate last non-dyntick-idle CPU's grace periods"
619 depends on NO_HZ_COMMON && SMP
622 This option permits CPUs to enter dynticks-idle state even if
623 they have RCU callbacks queued, and prevents RCU from waking
624 these CPUs up more than roughly once every four jiffies (by
625 default, you can adjust this using the rcutree.rcu_idle_gp_delay
626 parameter), thus improving energy efficiency. On the other
627 hand, this option increases the duration of RCU grace periods,
628 for example, slowing down synchronize_rcu().
630 Say Y if energy efficiency is critically important, and you
631 don't care about increased grace-period durations.
633 Say N if you are unsure.
635 config TREE_RCU_TRACE
636 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
639 This option provides tracing for the TREE_RCU and
640 TREE_PREEMPT_RCU implementations, permitting Makefile to
641 trivially select kernel/rcutree_trace.c.
644 bool "Enable RCU priority boosting"
645 depends on RT_MUTEXES && PREEMPT_RCU
648 This option boosts the priority of preempted RCU readers that
649 block the current preemptible RCU grace period for too long.
650 This option also prevents heavy loads from blocking RCU
651 callback invocation for all flavors of RCU.
653 Say Y here if you are working with real-time apps or heavy loads
654 Say N here if you are unsure.
656 config RCU_BOOST_PRIO
657 int "Real-time priority to boost RCU readers to"
662 This option specifies the real-time priority to which long-term
663 preempted RCU readers are to be boosted. If you are working
664 with a real-time application that has one or more CPU-bound
665 threads running at a real-time priority level, you should set
666 RCU_BOOST_PRIO to a priority higher then the highest-priority
667 real-time CPU-bound thread. The default RCU_BOOST_PRIO value
668 of 1 is appropriate in the common case, which is real-time
669 applications that do not have any CPU-bound threads.
671 Some real-time applications might not have a single real-time
672 thread that saturates a given CPU, but instead might have
673 multiple real-time threads that, taken together, fully utilize
674 that CPU. In this case, you should set RCU_BOOST_PRIO to
675 a priority higher than the lowest-priority thread that is
676 conspiring to prevent the CPU from running any non-real-time
677 tasks. For example, if one thread at priority 10 and another
678 thread at priority 5 are between themselves fully consuming
679 the CPU time on a given CPU, then RCU_BOOST_PRIO should be
680 set to priority 6 or higher.
682 Specify the real-time priority, or take the default if unsure.
684 config RCU_BOOST_DELAY
685 int "Milliseconds to delay boosting after RCU grace-period start"
690 This option specifies the time to wait after the beginning of
691 a given grace period before priority-boosting preempted RCU
692 readers blocking that grace period. Note that any RCU reader
693 blocking an expedited RCU grace period is boosted immediately.
695 Accept the default if unsure.
698 bool "Offload RCU callback processing from boot-selected CPUs"
699 depends on TREE_RCU || TREE_PREEMPT_RCU
702 Use this option to reduce OS jitter for aggressive HPC or
703 real-time workloads. It can also be used to offload RCU
704 callback invocation to energy-efficient CPUs in battery-powered
705 asymmetric multiprocessors.
707 This option offloads callback invocation from the set of
708 CPUs specified at boot time by the rcu_nocbs parameter.
709 For each such CPU, a kthread ("rcuox/N") will be created to
710 invoke callbacks, where the "N" is the CPU being offloaded,
711 and where the "x" is "b" for RCU-bh, "p" for RCU-preempt, and
712 "s" for RCU-sched. Nothing prevents this kthread from running
713 on the specified CPUs, but (1) the kthreads may be preempted
714 between each callback, and (2) affinity or cgroups can be used
715 to force the kthreads to run on whatever set of CPUs is desired.
717 Say Y here if you want to help to debug reduced OS jitter.
718 Say N here if you are unsure.
721 prompt "Build-forced no-CBs CPUs"
722 default RCU_NOCB_CPU_NONE
724 This option allows no-CBs CPUs (whose RCU callbacks are invoked
725 from kthreads rather than from softirq context) to be specified
726 at build time. Additional no-CBs CPUs may be specified by
727 the rcu_nocbs= boot parameter.
729 config RCU_NOCB_CPU_NONE
730 bool "No build_forced no-CBs CPUs"
731 depends on RCU_NOCB_CPU && !NO_HZ_FULL
733 This option does not force any of the CPUs to be no-CBs CPUs.
734 Only CPUs designated by the rcu_nocbs= boot parameter will be
735 no-CBs CPUs, whose RCU callbacks will be invoked by per-CPU
736 kthreads whose names begin with "rcuo". All other CPUs will
737 invoke their own RCU callbacks in softirq context.
739 Select this option if you want to choose no-CBs CPUs at
740 boot time, for example, to allow testing of different no-CBs
741 configurations without having to rebuild the kernel each time.
743 config RCU_NOCB_CPU_ZERO
744 bool "CPU 0 is a build_forced no-CBs CPU"
745 depends on RCU_NOCB_CPU && !NO_HZ_FULL
747 This option forces CPU 0 to be a no-CBs CPU, so that its RCU
748 callbacks are invoked by a per-CPU kthread whose name begins
749 with "rcuo". Additional CPUs may be designated as no-CBs
750 CPUs using the rcu_nocbs= boot parameter will be no-CBs CPUs.
751 All other CPUs will invoke their own RCU callbacks in softirq
754 Select this if CPU 0 needs to be a no-CBs CPU for real-time
755 or energy-efficiency reasons, but the real reason it exists
756 is to ensure that randconfig testing covers mixed systems.
758 config RCU_NOCB_CPU_ALL
759 bool "All CPUs are build_forced no-CBs CPUs"
760 depends on RCU_NOCB_CPU
762 This option forces all CPUs to be no-CBs CPUs. The rcu_nocbs=
763 boot parameter will be ignored. All CPUs' RCU callbacks will
764 be executed in the context of per-CPU rcuo kthreads created for
765 this purpose. Assuming that the kthreads whose names start with
766 "rcuo" are bound to "housekeeping" CPUs, this reduces OS jitter
767 on the remaining CPUs, but might decrease memory locality during
768 RCU-callback invocation, thus potentially degrading throughput.
770 Select this if all CPUs need to be no-CBs CPUs for real-time
771 or energy-efficiency reasons.
775 endmenu # "RCU Subsystem"
778 tristate "Kernel .config support"
780 This option enables the complete Linux kernel ".config" file
781 contents to be saved in the kernel. It provides documentation
782 of which kernel options are used in a running kernel or in an
783 on-disk kernel. This information can be extracted from the kernel
784 image file with the script scripts/extract-ikconfig and used as
785 input to rebuild the current kernel or to build another kernel.
786 It can also be extracted from a running kernel by reading
787 /proc/config.gz if enabled (below).
790 bool "Enable access to .config through /proc/config.gz"
791 depends on IKCONFIG && PROC_FS
793 This option enables access to the kernel configuration file
794 through /proc/config.gz.
797 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
801 Select kernel log buffer size as a power of 2.
811 # Architectures with an unreliable sched_clock() should select this:
813 config HAVE_UNSTABLE_SCHED_CLOCK
816 config GENERIC_SCHED_CLOCK
820 # For architectures that want to enable the support for NUMA-affine scheduler
823 config ARCH_SUPPORTS_NUMA_BALANCING
826 # For architectures that (ab)use NUMA to represent different memory regions
827 # all cpu-local but of different latencies, such as SuperH.
829 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
833 # For architectures that are willing to define _PAGE_NUMA as _PAGE_PROTNONE
834 config ARCH_WANTS_PROT_NUMA_PROT_NONE
837 config ARCH_USES_NUMA_PROT_NONE
840 depends on ARCH_WANTS_PROT_NUMA_PROT_NONE
841 depends on NUMA_BALANCING
843 config NUMA_BALANCING_DEFAULT_ENABLED
844 bool "Automatically enable NUMA aware memory/task placement"
846 depends on NUMA_BALANCING
848 If set, automatic NUMA balancing will be enabled if running on a NUMA
851 config NUMA_BALANCING
852 bool "Memory placement aware NUMA scheduler"
853 depends on ARCH_SUPPORTS_NUMA_BALANCING
854 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
855 depends on SMP && NUMA && MIGRATION
857 This option adds support for automatic NUMA aware memory/task placement.
858 The mechanism is quite primitive and is based on migrating memory when
859 it has references to the node the task is running on.
861 This system will be inactive on UMA systems.
864 boolean "Control Group support"
867 This option adds support for grouping sets of processes together, for
868 use with process control subsystems such as Cpusets, CFS, memory
869 controls or device isolation.
871 - Documentation/scheduler/sched-design-CFS.txt (CFS)
872 - Documentation/cgroups/ (features for grouping, isolation
873 and resource control)
880 bool "Example debug cgroup subsystem"
883 This option enables a simple cgroup subsystem that
884 exports useful debugging information about the cgroups
889 config CGROUP_FREEZER
890 bool "Freezer cgroup subsystem"
892 Provides a way to freeze and unfreeze all tasks in a
896 bool "Device controller for cgroups"
898 Provides a cgroup implementing whitelists for devices which
899 a process in the cgroup can mknod or open.
902 bool "Cpuset support"
904 This option will let you create and manage CPUSETs which
905 allow dynamically partitioning a system into sets of CPUs and
906 Memory Nodes and assigning tasks to run only within those sets.
907 This is primarily useful on large SMP or NUMA systems.
911 config PROC_PID_CPUSET
912 bool "Include legacy /proc/<pid>/cpuset file"
916 config CGROUP_CPUACCT
917 bool "Simple CPU accounting cgroup subsystem"
919 Provides a simple Resource Controller for monitoring the
920 total CPU consumed by the tasks in a cgroup.
922 config RESOURCE_COUNTERS
923 bool "Resource counters"
925 This option enables controller independent resource accounting
926 infrastructure that works with cgroups.
929 bool "Memory Resource Controller for Control Groups"
930 depends on RESOURCE_COUNTERS
933 Provides a memory resource controller that manages both anonymous
934 memory and page cache. (See Documentation/cgroups/memory.txt)
936 Note that setting this option increases fixed memory overhead
937 associated with each page of memory in the system. By this,
938 8(16)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
939 usage tracking struct at boot. Total amount of this is printed out
942 Only enable when you're ok with these trade offs and really
943 sure you need the memory resource controller. Even when you enable
944 this, you can set "cgroup_disable=memory" at your boot option to
945 disable memory resource controller and you can avoid overheads.
946 (and lose benefits of memory resource controller)
948 This config option also selects MM_OWNER config option, which
949 could in turn add some fork/exit overhead.
952 bool "Memory Resource Controller Swap Extension"
953 depends on MEMCG && SWAP
955 Add swap management feature to memory resource controller. When you
956 enable this, you can limit mem+swap usage per cgroup. In other words,
957 when you disable this, memory resource controller has no cares to
958 usage of swap...a process can exhaust all of the swap. This extension
959 is useful when you want to avoid exhaustion swap but this itself
960 adds more overheads and consumes memory for remembering information.
961 Especially if you use 32bit system or small memory system, please
962 be careful about enabling this. When memory resource controller
963 is disabled by boot option, this will be automatically disabled and
964 there will be no overhead from this. Even when you set this config=y,
965 if boot option "swapaccount=0" is set, swap will not be accounted.
966 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
967 size is 4096bytes, 512k per 1Gbytes of swap.
968 config MEMCG_SWAP_ENABLED
969 bool "Memory Resource Controller Swap Extension enabled by default"
970 depends on MEMCG_SWAP
973 Memory Resource Controller Swap Extension comes with its price in
974 a bigger memory consumption. General purpose distribution kernels
975 which want to enable the feature but keep it disabled by default
976 and let the user enable it by swapaccount=1 boot command line
977 parameter should have this option unselected.
978 For those who want to have the feature enabled by default should
979 select this option (if, for some reason, they need to disable it
980 then swapaccount=0 does the trick).
982 bool "Memory Resource Controller Kernel Memory accounting"
984 depends on SLUB || SLAB
986 The Kernel Memory extension for Memory Resource Controller can limit
987 the amount of memory used by kernel objects in the system. Those are
988 fundamentally different from the entities handled by the standard
989 Memory Controller, which are page-based, and can be swapped. Users of
990 the kmem extension can use it to guarantee that no group of processes
991 will ever exhaust kernel resources alone.
993 config CGROUP_HUGETLB
994 bool "HugeTLB Resource Controller for Control Groups"
995 depends on RESOURCE_COUNTERS && HUGETLB_PAGE
998 Provides a cgroup Resource Controller for HugeTLB pages.
999 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1000 The limit is enforced during page fault. Since HugeTLB doesn't
1001 support page reclaim, enforcing the limit at page fault time implies
1002 that, the application will get SIGBUS signal if it tries to access
1003 HugeTLB pages beyond its limit. This requires the application to know
1004 beforehand how much HugeTLB pages it would require for its use. The
1005 control group is tracked in the third page lru pointer. This means
1006 that we cannot use the controller with huge page less than 3 pages.
1009 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
1010 depends on PERF_EVENTS && CGROUPS
1012 This option extends the per-cpu mode to restrict monitoring to
1013 threads which belong to the cgroup specified and run on the
1018 menuconfig CGROUP_SCHED
1019 bool "Group CPU scheduler"
1022 This feature lets CPU scheduler recognize task groups and control CPU
1023 bandwidth allocation to such task groups. It uses cgroups to group
1027 config FAIR_GROUP_SCHED
1028 bool "Group scheduling for SCHED_OTHER"
1029 depends on CGROUP_SCHED
1030 default CGROUP_SCHED
1032 config CFS_BANDWIDTH
1033 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
1034 depends on FAIR_GROUP_SCHED
1037 This option allows users to define CPU bandwidth rates (limits) for
1038 tasks running within the fair group scheduler. Groups with no limit
1039 set are considered to be unconstrained and will run with no
1041 See tip/Documentation/scheduler/sched-bwc.txt for more information.
1043 config RT_GROUP_SCHED
1044 bool "Group scheduling for SCHED_RR/FIFO"
1045 depends on CGROUP_SCHED
1048 This feature lets you explicitly allocate real CPU bandwidth
1049 to task groups. If enabled, it will also make it impossible to
1050 schedule realtime tasks for non-root users until you allocate
1051 realtime bandwidth for them.
1052 See Documentation/scheduler/sched-rt-group.txt for more information.
1057 bool "Block IO controller"
1061 Generic block IO controller cgroup interface. This is the common
1062 cgroup interface which should be used by various IO controlling
1065 Currently, CFQ IO scheduler uses it to recognize task groups and
1066 control disk bandwidth allocation (proportional time slice allocation)
1067 to such task groups. It is also used by bio throttling logic in
1068 block layer to implement upper limit in IO rates on a device.
1070 This option only enables generic Block IO controller infrastructure.
1071 One needs to also enable actual IO controlling logic/policy. For
1072 enabling proportional weight division of disk bandwidth in CFQ, set
1073 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1074 CONFIG_BLK_DEV_THROTTLING=y.
1076 See Documentation/cgroups/blkio-controller.txt for more information.
1078 config DEBUG_BLK_CGROUP
1079 bool "Enable Block IO controller debugging"
1080 depends on BLK_CGROUP
1083 Enable some debugging help. Currently it exports additional stat
1084 files in a cgroup which can be useful for debugging.
1088 config CHECKPOINT_RESTORE
1089 bool "Checkpoint/restore support" if EXPERT
1092 Enables additional kernel features in a sake of checkpoint/restore.
1093 In particular it adds auxiliary prctl codes to setup process text,
1094 data and heap segment sizes, and a few additional /proc filesystem
1097 If unsure, say N here.
1099 menuconfig NAMESPACES
1100 bool "Namespaces support" if EXPERT
1103 Provides the way to make tasks work with different objects using
1104 the same id. For example same IPC id may refer to different objects
1105 or same user id or pid may refer to different tasks when used in
1106 different namespaces.
1111 bool "UTS namespace"
1114 In this namespace tasks see different info provided with the
1118 bool "IPC namespace"
1119 depends on (SYSVIPC || POSIX_MQUEUE)
1122 In this namespace tasks work with IPC ids which correspond to
1123 different IPC objects in different namespaces.
1126 bool "User namespace"
1127 select UIDGID_STRICT_TYPE_CHECKS
1131 This allows containers, i.e. vservers, to use user namespaces
1132 to provide different user info for different servers.
1134 When user namespaces are enabled in the kernel it is
1135 recommended that the MEMCG and MEMCG_KMEM options also be
1136 enabled and that user-space use the memory control groups to
1137 limit the amount of memory a memory unprivileged users can
1143 bool "PID Namespaces"
1146 Support process id namespaces. This allows having multiple
1147 processes with the same pid as long as they are in different
1148 pid namespaces. This is a building block of containers.
1151 bool "Network namespace"
1155 Allow user space to create what appear to be multiple instances
1156 of the network stack.
1160 config UIDGID_STRICT_TYPE_CHECKS
1161 bool "Require conversions between uid/gids and their internal representation"
1164 While the nececessary conversions are being added to all subsystems this option allows
1165 the code to continue to build for unconverted subsystems.
1167 Say Y here if you want the strict type checking enabled
1169 config SCHED_AUTOGROUP
1170 bool "Automatic process group scheduling"
1174 select FAIR_GROUP_SCHED
1176 This option optimizes the scheduler for common desktop workloads by
1177 automatically creating and populating task groups. This separation
1178 of workloads isolates aggressive CPU burners (like build jobs) from
1179 desktop applications. Task group autogeneration is currently based
1185 config SYSFS_DEPRECATED
1186 bool "Enable deprecated sysfs features to support old userspace tools"
1190 This option adds code that switches the layout of the "block" class
1191 devices, to not show up in /sys/class/block/, but only in
1194 This switch is only active when the sysfs.deprecated=1 boot option is
1195 passed or the SYSFS_DEPRECATED_V2 option is set.
1197 This option allows new kernels to run on old distributions and tools,
1198 which might get confused by /sys/class/block/. Since 2007/2008 all
1199 major distributions and tools handle this just fine.
1201 Recent distributions and userspace tools after 2009/2010 depend on
1202 the existence of /sys/class/block/, and will not work with this
1205 Only if you are using a new kernel on an old distribution, you might
1208 config SYSFS_DEPRECATED_V2
1209 bool "Enable deprecated sysfs features by default"
1212 depends on SYSFS_DEPRECATED
1214 Enable deprecated sysfs by default.
1216 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1219 Only if you are using a new kernel on an old distribution, you might
1220 need to say Y here. Even then, odds are you would not need it
1221 enabled, you can always pass the boot option if absolutely necessary.
1224 bool "Kernel->user space relay support (formerly relayfs)"
1226 This option enables support for relay interface support in
1227 certain file systems (such as debugfs).
1228 It is designed to provide an efficient mechanism for tools and
1229 facilities to relay large amounts of data from kernel space to
1234 config BLK_DEV_INITRD
1235 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1236 depends on BROKEN || !FRV
1238 The initial RAM filesystem is a ramfs which is loaded by the
1239 boot loader (loadlin or lilo) and that is mounted as root
1240 before the normal boot procedure. It is typically used to
1241 load modules needed to mount the "real" root file system,
1242 etc. See <file:Documentation/initrd.txt> for details.
1244 If RAM disk support (BLK_DEV_RAM) is also included, this
1245 also enables initial RAM disk (initrd) support and adds
1246 15 Kbytes (more on some other architectures) to the kernel size.
1252 source "usr/Kconfig"
1256 config CC_OPTIMIZE_FOR_SIZE
1257 bool "Optimize for size"
1259 Enabling this option will pass "-Os" instead of "-O2" to gcc
1260 resulting in a smaller kernel.
1273 config SYSCTL_EXCEPTION_TRACE
1276 Enable support for /proc/sys/debug/exception-trace.
1278 config SYSCTL_ARCH_UNALIGN_NO_WARN
1281 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1282 Allows arch to define/use @no_unaligned_warning to possibly warn
1283 about unaligned access emulation going on under the hood.
1285 config SYSCTL_ARCH_UNALIGN_ALLOW
1288 Enable support for /proc/sys/kernel/unaligned-trap
1289 Allows arches to define/use @unaligned_enabled to runtime toggle
1290 the unaligned access emulation.
1291 see arch/parisc/kernel/unaligned.c for reference
1293 config HAVE_PCSPKR_PLATFORM
1297 bool "Configure standard kernel features (expert users)"
1298 # Unhide debug options, to make the on-by-default options visible
1301 This option allows certain base kernel options and settings
1302 to be disabled or tweaked. This is for specialized
1303 environments which can tolerate a "non-standard" kernel.
1304 Only use this if you really know what you are doing.
1307 bool "Enable 16-bit UID system calls" if EXPERT
1308 depends on HAVE_UID16
1311 This enables the legacy 16-bit UID syscall wrappers.
1313 config SYSCTL_SYSCALL
1314 bool "Sysctl syscall support" if EXPERT
1315 depends on PROC_SYSCTL
1319 sys_sysctl uses binary paths that have been found challenging
1320 to properly maintain and use. The interface in /proc/sys
1321 using paths with ascii names is now the primary path to this
1324 Almost nothing using the binary sysctl interface so if you are
1325 trying to save some space it is probably safe to disable this,
1326 making your kernel marginally smaller.
1328 If unsure say N here.
1331 bool "Load all symbols for debugging/ksymoops" if EXPERT
1334 Say Y here to let the kernel print out symbolic crash information and
1335 symbolic stack backtraces. This increases the size of the kernel
1336 somewhat, as all symbols have to be loaded into the kernel image.
1339 bool "Include all symbols in kallsyms"
1340 depends on DEBUG_KERNEL && KALLSYMS
1342 Normally kallsyms only contains the symbols of functions for nicer
1343 OOPS messages and backtraces (i.e., symbols from the text and inittext
1344 sections). This is sufficient for most cases. And only in very rare
1345 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1346 names of variables from the data sections, etc).
1348 This option makes sure that all symbols are loaded into the kernel
1349 image (i.e., symbols from all sections) in cost of increased kernel
1350 size (depending on the kernel configuration, it may be 300KiB or
1351 something like this).
1353 Say N unless you really need all symbols.
1357 bool "Enable support for printk" if EXPERT
1360 This option enables normal printk support. Removing it
1361 eliminates most of the message strings from the kernel image
1362 and makes the kernel more or less silent. As this makes it
1363 very difficult to diagnose system problems, saying N here is
1364 strongly discouraged.
1367 bool "BUG() support" if EXPERT
1370 Disabling this option eliminates support for BUG and WARN, reducing
1371 the size of your kernel image and potentially quietly ignoring
1372 numerous fatal conditions. You should only consider disabling this
1373 option for embedded systems with no facilities for reporting errors.
1379 bool "Enable ELF core dumps" if EXPERT
1381 Enable support for generating core dumps. Disabling saves about 4k.
1384 config PCSPKR_PLATFORM
1385 bool "Enable PC-Speaker support" if EXPERT
1386 depends on HAVE_PCSPKR_PLATFORM
1390 This option allows to disable the internal PC-Speaker
1391 support, saving some memory.
1395 bool "Enable full-sized data structures for core" if EXPERT
1397 Disabling this option reduces the size of miscellaneous core
1398 kernel data structures. This saves memory on small machines,
1399 but may reduce performance.
1402 bool "Enable futex support" if EXPERT
1406 Disabling this option will cause the kernel to be built without
1407 support for "fast userspace mutexes". The resulting kernel may not
1408 run glibc-based applications correctly.
1411 bool "Enable eventpoll support" if EXPERT
1415 Disabling this option will cause the kernel to be built without
1416 support for epoll family of system calls.
1419 bool "Enable signalfd() system call" if EXPERT
1423 Enable the signalfd() system call that allows to receive signals
1424 on a file descriptor.
1429 bool "Enable timerfd() system call" if EXPERT
1433 Enable the timerfd() system call that allows to receive timer
1434 events on a file descriptor.
1439 bool "Enable eventfd() system call" if EXPERT
1443 Enable the eventfd() system call that allows to receive both
1444 kernel notification (ie. KAIO) or userspace notifications.
1449 bool "Use full shmem filesystem" if EXPERT
1453 The shmem is an internal filesystem used to manage shared memory.
1454 It is backed by swap and manages resource limits. It is also exported
1455 to userspace as tmpfs if TMPFS is enabled. Disabling this
1456 option replaces shmem and tmpfs with the much simpler ramfs code,
1457 which may be appropriate on small systems without swap.
1460 bool "Enable AIO support" if EXPERT
1463 This option enables POSIX asynchronous I/O which may by used
1464 by some high performance threaded applications. Disabling
1465 this option saves about 7k.
1469 bool "Enable PCI quirk workarounds" if EXPERT
1472 This enables workarounds for various PCI chipset
1473 bugs/quirks. Disable this only if your target machine is
1474 unaffected by PCI quirks.
1477 bool "Embedded system"
1480 This option should be enabled if compiling the kernel for
1481 an embedded system so certain expert options are available
1484 config HAVE_PERF_EVENTS
1487 See tools/perf/design.txt for details.
1489 config PERF_USE_VMALLOC
1492 See tools/perf/design.txt for details
1494 menu "Kernel Performance Events And Counters"
1497 bool "Kernel performance events and counters"
1498 default y if PROFILING
1499 depends on HAVE_PERF_EVENTS
1503 Enable kernel support for various performance events provided
1504 by software and hardware.
1506 Software events are supported either built-in or via the
1507 use of generic tracepoints.
1509 Most modern CPUs support performance events via performance
1510 counter registers. These registers count the number of certain
1511 types of hw events: such as instructions executed, cachemisses
1512 suffered, or branches mis-predicted - without slowing down the
1513 kernel or applications. These registers can also trigger interrupts
1514 when a threshold number of events have passed - and can thus be
1515 used to profile the code that runs on that CPU.
1517 The Linux Performance Event subsystem provides an abstraction of
1518 these software and hardware event capabilities, available via a
1519 system call and used by the "perf" utility in tools/perf/. It
1520 provides per task and per CPU counters, and it provides event
1521 capabilities on top of those.
1525 config DEBUG_PERF_USE_VMALLOC
1527 bool "Debug: use vmalloc to back perf mmap() buffers"
1528 depends on PERF_EVENTS && DEBUG_KERNEL
1529 select PERF_USE_VMALLOC
1531 Use vmalloc memory to back perf mmap() buffers.
1533 Mostly useful for debugging the vmalloc code on platforms
1534 that don't require it.
1540 config VM_EVENT_COUNTERS
1542 bool "Enable VM event counters for /proc/vmstat" if EXPERT
1544 VM event counters are needed for event counts to be shown.
1545 This option allows the disabling of the VM event counters
1546 on EXPERT systems. /proc/vmstat will only show page counts
1547 if VM event counters are disabled.
1551 bool "Enable SLUB debugging support" if EXPERT
1552 depends on SLUB && SYSFS
1554 SLUB has extensive debug support features. Disabling these can
1555 result in significant savings in code size. This also disables
1556 SLUB sysfs support. /sys/slab will not exist and there will be
1557 no support for cache validation etc.
1560 bool "Disable heap randomization"
1563 Randomizing heap placement makes heap exploits harder, but it
1564 also breaks ancient binaries (including anything libc5 based).
1565 This option changes the bootup default to heap randomization
1566 disabled, and can be overridden at runtime by setting
1567 /proc/sys/kernel/randomize_va_space to 2.
1569 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1572 prompt "Choose SLAB allocator"
1575 This option allows to select a slab allocator.
1580 The regular slab allocator that is established and known to work
1581 well in all environments. It organizes cache hot objects in
1582 per cpu and per node queues.
1585 bool "SLUB (Unqueued Allocator)"
1587 SLUB is a slab allocator that minimizes cache line usage
1588 instead of managing queues of cached objects (SLAB approach).
1589 Per cpu caching is realized using slabs of objects instead
1590 of queues of objects. SLUB can use memory efficiently
1591 and has enhanced diagnostics. SLUB is the default choice for
1596 bool "SLOB (Simple Allocator)"
1598 SLOB replaces the stock allocator with a drastically simpler
1599 allocator. SLOB is generally more space efficient but
1600 does not perform as well on large systems.
1604 config SLUB_CPU_PARTIAL
1606 depends on SLUB && SMP
1607 bool "SLUB per cpu partial cache"
1609 Per cpu partial caches accellerate objects allocation and freeing
1610 that is local to a processor at the price of more indeterminism
1611 in the latency of the free. On overflow these caches will be cleared
1612 which requires the taking of locks that may cause latency spikes.
1613 Typically one would choose no for a realtime system.
1615 config MMAP_ALLOW_UNINITIALIZED
1616 bool "Allow mmapped anonymous memory to be uninitialized"
1617 depends on EXPERT && !MMU
1620 Normally, and according to the Linux spec, anonymous memory obtained
1621 from mmap() has it's contents cleared before it is passed to
1622 userspace. Enabling this config option allows you to request that
1623 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1624 providing a huge performance boost. If this option is not enabled,
1625 then the flag will be ignored.
1627 This is taken advantage of by uClibc's malloc(), and also by
1628 ELF-FDPIC binfmt's brk and stack allocator.
1630 Because of the obvious security issues, this option should only be
1631 enabled on embedded devices where you control what is run in
1632 userspace. Since that isn't generally a problem on no-MMU systems,
1633 it is normally safe to say Y here.
1635 See Documentation/nommu-mmap.txt for more information.
1638 bool "Profiling support"
1640 Say Y here to enable the extended profiling support mechanisms used
1641 by profilers such as OProfile.
1644 # Place an empty function call at each tracepoint site. Can be
1645 # dynamically changed for a probe function.
1650 source "arch/Kconfig"
1652 endmenu # General setup
1654 config HAVE_GENERIC_DMA_COHERENT
1661 depends on SLAB || SLUB_DEBUG
1669 default 0 if BASE_FULL
1670 default 1 if !BASE_FULL
1672 config SYSTEM_TRUSTED_KEYRING
1673 bool "Provide system-wide ring of trusted keys"
1676 Provide a system keyring to which trusted keys can be added. Keys in
1677 the keyring are considered to be trusted. Keys may be added at will
1678 by the kernel from compiled-in data and from hardware key stores, but
1679 userspace may only add extra keys if those keys can be verified by
1680 keys already in the keyring.
1682 Keys in this keyring are used by module signature checking.
1685 bool "Enable loadable module support"
1688 Kernel modules are small pieces of compiled code which can
1689 be inserted in the running kernel, rather than being
1690 permanently built into the kernel. You use the "modprobe"
1691 tool to add (and sometimes remove) them. If you say Y here,
1692 many parts of the kernel can be built as modules (by
1693 answering M instead of Y where indicated): this is most
1694 useful for infrequently used options which are not required
1695 for booting. For more information, see the man pages for
1696 modprobe, lsmod, modinfo, insmod and rmmod.
1698 If you say Y here, you will need to run "make
1699 modules_install" to put the modules under /lib/modules/
1700 where modprobe can find them (you may need to be root to do
1707 config MODULE_FORCE_LOAD
1708 bool "Forced module loading"
1711 Allow loading of modules without version information (ie. modprobe
1712 --force). Forced module loading sets the 'F' (forced) taint flag and
1713 is usually a really bad idea.
1715 config MODULE_UNLOAD
1716 bool "Module unloading"
1718 Without this option you will not be able to unload any
1719 modules (note that some modules may not be unloadable
1720 anyway), which makes your kernel smaller, faster
1721 and simpler. If unsure, say Y.
1723 config MODULE_FORCE_UNLOAD
1724 bool "Forced module unloading"
1725 depends on MODULE_UNLOAD
1727 This option allows you to force a module to unload, even if the
1728 kernel believes it is unsafe: the kernel will remove the module
1729 without waiting for anyone to stop using it (using the -f option to
1730 rmmod). This is mainly for kernel developers and desperate users.
1734 bool "Module versioning support"
1736 Usually, you have to use modules compiled with your kernel.
1737 Saying Y here makes it sometimes possible to use modules
1738 compiled for different kernels, by adding enough information
1739 to the modules to (hopefully) spot any changes which would
1740 make them incompatible with the kernel you are running. If
1743 config MODULE_SRCVERSION_ALL
1744 bool "Source checksum for all modules"
1746 Modules which contain a MODULE_VERSION get an extra "srcversion"
1747 field inserted into their modinfo section, which contains a
1748 sum of the source files which made it. This helps maintainers
1749 see exactly which source was used to build a module (since
1750 others sometimes change the module source without updating
1751 the version). With this option, such a "srcversion" field
1752 will be created for all modules. If unsure, say N.
1755 bool "Module signature verification"
1757 select SYSTEM_TRUSTED_KEYRING
1760 select ASYMMETRIC_KEY_TYPE
1761 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1762 select PUBLIC_KEY_ALGO_RSA
1765 select X509_CERTIFICATE_PARSER
1767 Check modules for valid signatures upon load: the signature
1768 is simply appended to the module. For more information see
1769 Documentation/module-signing.txt.
1771 !!!WARNING!!! If you enable this option, you MUST make sure that the
1772 module DOES NOT get stripped after being signed. This includes the
1773 debuginfo strip done by some packagers (such as rpmbuild) and
1774 inclusion into an initramfs that wants the module size reduced.
1776 config MODULE_SIG_FORCE
1777 bool "Require modules to be validly signed"
1778 depends on MODULE_SIG
1780 Reject unsigned modules or signed modules for which we don't have a
1781 key. Without this, such modules will simply taint the kernel.
1783 config MODULE_SIG_ALL
1784 bool "Automatically sign all modules"
1786 depends on MODULE_SIG
1788 Sign all modules during make modules_install. Without this option,
1789 modules must be signed manually, using the scripts/sign-file tool.
1791 comment "Do not forget to sign required modules with scripts/sign-file"
1792 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
1795 prompt "Which hash algorithm should modules be signed with?"
1796 depends on MODULE_SIG
1798 This determines which sort of hashing algorithm will be used during
1799 signature generation. This algorithm _must_ be built into the kernel
1800 directly so that signature verification can take place. It is not
1801 possible to load a signed module containing the algorithm to check
1802 the signature on that module.
1804 config MODULE_SIG_SHA1
1805 bool "Sign modules with SHA-1"
1808 config MODULE_SIG_SHA224
1809 bool "Sign modules with SHA-224"
1810 select CRYPTO_SHA256
1812 config MODULE_SIG_SHA256
1813 bool "Sign modules with SHA-256"
1814 select CRYPTO_SHA256
1816 config MODULE_SIG_SHA384
1817 bool "Sign modules with SHA-384"
1818 select CRYPTO_SHA512
1820 config MODULE_SIG_SHA512
1821 bool "Sign modules with SHA-512"
1822 select CRYPTO_SHA512
1826 config MODULE_SIG_HASH
1828 depends on MODULE_SIG
1829 default "sha1" if MODULE_SIG_SHA1
1830 default "sha224" if MODULE_SIG_SHA224
1831 default "sha256" if MODULE_SIG_SHA256
1832 default "sha384" if MODULE_SIG_SHA384
1833 default "sha512" if MODULE_SIG_SHA512
1837 config INIT_ALL_POSSIBLE
1840 Back when each arch used to define their own cpu_online_mask and
1841 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
1842 with all 1s, and others with all 0s. When they were centralised,
1843 it was better to provide this option than to break all the archs
1844 and have several arch maintainers pursuing me down dark alleys.
1849 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1851 Need stop_machine() primitive.
1853 source "block/Kconfig"
1855 config PREEMPT_NOTIFIERS
1862 # Can be selected by architectures with broken toolchains
1863 # that get confused by correct const<->read_only section
1865 config BROKEN_RODATA
1871 Build a simple ASN.1 grammar compiler that produces a bytecode output
1872 that can be interpreted by the ASN.1 stream decoder and used to
1873 inform it as to what tags are to be expected in a stream and what
1874 functions to call on what tags.
1876 source "kernel/Kconfig.locks"
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