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"
122 The linux kernel is a kind of self-extracting executable.
123 Several compression algorithms are available, which differ
124 in efficiency, compression and decompression speed.
125 Compression speed is only relevant when building a kernel.
126 Decompression speed is relevant at each boot.
128 If you have any problems with bzip2 or lzma compressed
129 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
130 version of this functionality (bzip2 only), for 2.4, was
131 supplied by Christian Ludwig)
133 High compression options are mostly useful for users, who
134 are low on disk space (embedded systems), but for whom ram
137 If in doubt, select 'gzip'
139 config KERNEL_UNCOMPRESSED
140 bool "No compression"
142 No compression at all. The kernel is huge but the compression and
143 decompression times are zero.
144 This is usually not what you want.
148 depends on HAVE_KERNEL_GZIP
150 The old and tried gzip compression. It provides a good balance
151 between compression ratio and decompression speed.
155 depends on HAVE_KERNEL_BZIP2
157 Its compression ratio and speed is intermediate.
158 Decompression speed is slowest among the choices. The kernel
159 size is about 10% smaller with bzip2, in comparison to gzip.
160 Bzip2 uses a large amount of memory. For modern kernels you
161 will need at least 8MB RAM or more for booting.
165 depends on HAVE_KERNEL_LZMA
167 This compression algorithm's ratio is best. Decompression speed
168 is between gzip and bzip2. Compression is slowest.
169 The kernel size is about 33% smaller with LZMA in comparison to gzip.
173 depends on HAVE_KERNEL_XZ
175 XZ uses the LZMA2 algorithm and instruction set specific
176 BCJ filters which can improve compression ratio of executable
177 code. The size of the kernel is about 30% smaller with XZ in
178 comparison to gzip. On architectures for which there is a BCJ
179 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
180 will create a few percent smaller kernel than plain LZMA.
182 The speed is about the same as with LZMA: The decompression
183 speed of XZ is better than that of bzip2 but worse than gzip
184 and LZO. Compression is slow.
188 depends on HAVE_KERNEL_LZO
190 Its compression ratio is the poorest among the choices. The kernel
191 size is about 10% bigger than gzip; however its speed
192 (both compression and decompression) is the fastest.
196 depends on HAVE_KERNEL_LZ4
198 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
199 A preliminary version of LZ4 de/compression tool is available at
200 <https://code.google.com/p/lz4/>.
202 Its compression ratio is worse than LZO. The size of the kernel
203 is about 8% bigger than LZO. But the decompression speed is
208 config DEFAULT_HOSTNAME
209 string "Default hostname"
212 This option determines the default system hostname before userspace
213 calls sethostname(2). The kernel traditionally uses "(none)" here,
214 but you may wish to use a different default here to make a minimal
215 system more usable with less configuration.
218 bool "Support for paging of anonymous memory (swap)"
219 depends on MMU && BLOCK
222 This option allows you to choose whether you want to have support
223 for so called swap devices or swap files in your kernel that are
224 used to provide more virtual memory than the actual RAM present
225 in your computer. If unsure say Y.
230 Inter Process Communication is a suite of library functions and
231 system calls which let processes (running programs) synchronize and
232 exchange information. It is generally considered to be a good thing,
233 and some programs won't run unless you say Y here. In particular, if
234 you want to run the DOS emulator dosemu under Linux (read the
235 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
236 you'll need to say Y here.
238 You can find documentation about IPC with "info ipc" and also in
239 section 6.4 of the Linux Programmer's Guide, available from
240 <http://www.tldp.org/guides.html>.
242 config SYSVIPC_SYSCTL
249 bool "POSIX Message Queues"
252 POSIX variant of message queues is a part of IPC. In POSIX message
253 queues every message has a priority which decides about succession
254 of receiving it by a process. If you want to compile and run
255 programs written e.g. for Solaris with use of its POSIX message
256 queues (functions mq_*) say Y here.
258 POSIX message queues are visible as a filesystem called 'mqueue'
259 and can be mounted somewhere if you want to do filesystem
260 operations on message queues.
264 config POSIX_MQUEUE_SYSCTL
266 depends on POSIX_MQUEUE
271 bool "open by fhandle syscalls"
274 If you say Y here, a user level program will be able to map
275 file names to handle and then later use the handle for
276 different file system operations. This is useful in implementing
277 userspace file servers, which now track files using handles instead
278 of names. The handle would remain the same even if file names
279 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
283 bool "Auditing support"
286 Enable auditing infrastructure that can be used with another
287 kernel subsystem, such as SELinux (which requires this for
288 logging of avc messages output). Does not do system-call
289 auditing without CONFIG_AUDITSYSCALL.
292 bool "Enable system-call auditing support"
293 depends on AUDIT && (X86 || PARISC || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || (ARM && AEABI && !OABI_COMPAT))
294 default y if SECURITY_SELINUX
296 Enable low-overhead system-call auditing infrastructure that
297 can be used independently or with another kernel subsystem,
302 depends on AUDITSYSCALL
307 depends on AUDITSYSCALL
310 config AUDIT_LOGINUID_IMMUTABLE
311 bool "Make audit loginuid immutable"
314 The config option toggles if a task setting its loginuid requires
315 CAP_SYS_AUDITCONTROL or if that task should require no special permissions
316 but should instead only allow setting its loginuid if it was never
317 previously set. On systems which use systemd or a similar central
318 process to restart login services this should be set to true. On older
319 systems in which an admin would typically have to directly stop and
320 start processes this should be set to false. Setting this to true allows
321 one to drop potentially dangerous capabilites from the login tasks,
322 but may not be backwards compatible with older init systems.
324 source "kernel/irq/Kconfig"
325 source "kernel/time/Kconfig"
327 menu "CPU/Task time and stats accounting"
329 config VIRT_CPU_ACCOUNTING
333 prompt "Cputime accounting"
334 default TICK_CPU_ACCOUNTING if !PPC64
335 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
337 # Kind of a stub config for the pure tick based cputime accounting
338 config TICK_CPU_ACCOUNTING
339 bool "Simple tick based cputime accounting"
340 depends on !S390 && !NO_HZ_FULL
342 This is the basic tick based cputime accounting that maintains
343 statistics about user, system and idle time spent on per jiffies
348 config VIRT_CPU_ACCOUNTING_NATIVE
349 bool "Deterministic task and CPU time accounting"
350 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
351 select VIRT_CPU_ACCOUNTING
353 Select this option to enable more accurate task and CPU time
354 accounting. This is done by reading a CPU counter on each
355 kernel entry and exit and on transitions within the kernel
356 between system, softirq and hardirq state, so there is a
357 small performance impact. In the case of s390 or IBM POWER > 5,
358 this also enables accounting of stolen time on logically-partitioned
361 config VIRT_CPU_ACCOUNTING_GEN
362 bool "Full dynticks CPU time accounting"
363 depends on HAVE_CONTEXT_TRACKING
364 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
365 select VIRT_CPU_ACCOUNTING
366 select CONTEXT_TRACKING
368 Select this option to enable task and CPU time accounting on full
369 dynticks systems. This accounting is implemented by watching every
370 kernel-user boundaries using the context tracking subsystem.
371 The accounting is thus performed at the expense of some significant
374 For now this is only useful if you are working on the full
375 dynticks subsystem development.
379 config IRQ_TIME_ACCOUNTING
380 bool "Fine granularity task level IRQ time accounting"
381 depends on HAVE_IRQ_TIME_ACCOUNTING && !NO_HZ_FULL
383 Select this option to enable fine granularity task irq time
384 accounting. This is done by reading a timestamp on each
385 transitions between softirq and hardirq state, so there can be a
386 small performance impact.
388 If in doubt, say N here.
392 config BSD_PROCESS_ACCT
393 bool "BSD Process Accounting"
395 If you say Y here, a user level program will be able to instruct the
396 kernel (via a special system call) to write process accounting
397 information to a file: whenever a process exits, information about
398 that process will be appended to the file by the kernel. The
399 information includes things such as creation time, owning user,
400 command name, memory usage, controlling terminal etc. (the complete
401 list is in the struct acct in <file:include/linux/acct.h>). It is
402 up to the user level program to do useful things with this
403 information. This is generally a good idea, so say Y.
405 config BSD_PROCESS_ACCT_V3
406 bool "BSD Process Accounting version 3 file format"
407 depends on BSD_PROCESS_ACCT
410 If you say Y here, the process accounting information is written
411 in a new file format that also logs the process IDs of each
412 process and it's parent. Note that this file format is incompatible
413 with previous v0/v1/v2 file formats, so you will need updated tools
414 for processing it. A preliminary version of these tools is available
415 at <http://www.gnu.org/software/acct/>.
418 bool "Export task/process statistics through netlink"
422 Export selected statistics for tasks/processes through the
423 generic netlink interface. Unlike BSD process accounting, the
424 statistics are available during the lifetime of tasks/processes as
425 responses to commands. Like BSD accounting, they are sent to user
430 config TASK_DELAY_ACCT
431 bool "Enable per-task delay accounting"
434 Collect information on time spent by a task waiting for system
435 resources like cpu, synchronous block I/O completion and swapping
436 in pages. Such statistics can help in setting a task's priorities
437 relative to other tasks for cpu, io, rss limits etc.
442 bool "Enable extended accounting over taskstats"
445 Collect extended task accounting data and send the data
446 to userland for processing over the taskstats interface.
450 config TASK_IO_ACCOUNTING
451 bool "Enable per-task storage I/O accounting"
452 depends on TASK_XACCT
454 Collect information on the number of bytes of storage I/O which this
459 endmenu # "CPU/Task time and stats accounting"
464 prompt "RCU Implementation"
468 bool "Tree-based hierarchical RCU"
469 depends on !PREEMPT && SMP
472 This option selects the RCU implementation that is
473 designed for very large SMP system with hundreds or
474 thousands of CPUs. It also scales down nicely to
477 config TREE_PREEMPT_RCU
478 bool "Preemptible tree-based hierarchical RCU"
482 This option selects the RCU implementation that is
483 designed for very large SMP systems with hundreds or
484 thousands of CPUs, but for which real-time response
485 is also required. It also scales down nicely to
488 Select this option if you are unsure.
491 bool "UP-only small-memory-footprint RCU"
492 depends on !PREEMPT && !SMP
494 This option selects the RCU implementation that is
495 designed for UP systems from which real-time response
496 is not required. This option greatly reduces the
497 memory footprint of RCU.
502 def_bool TREE_PREEMPT_RCU
504 This option enables preemptible-RCU code that is common between
505 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
507 config RCU_STALL_COMMON
508 def_bool ( TREE_RCU || TREE_PREEMPT_RCU || RCU_TRACE )
510 This option enables RCU CPU stall code that is common between
511 the TINY and TREE variants of RCU. The purpose is to allow
512 the tiny variants to disable RCU CPU stall warnings, while
513 making these warnings mandatory for the tree variants.
515 config CONTEXT_TRACKING
519 bool "Consider userspace as in RCU extended quiescent state"
520 depends on HAVE_CONTEXT_TRACKING && SMP
521 select CONTEXT_TRACKING
523 This option sets hooks on kernel / userspace boundaries and
524 puts RCU in extended quiescent state when the CPU runs in
525 userspace. It means that when a CPU runs in userspace, it is
526 excluded from the global RCU state machine and thus doesn't
527 try to keep the timer tick on for RCU.
529 Unless you want to hack and help the development of the full
530 dynticks mode, you shouldn't enable this option. It also
531 adds unnecessary overhead.
535 config CONTEXT_TRACKING_FORCE
536 bool "Force context tracking"
537 depends on CONTEXT_TRACKING
538 default y if !NO_HZ_FULL
540 The major pre-requirement for full dynticks to work is to
541 support the context tracking subsystem. But there are also
542 other dependencies to provide in order to make the full
545 This option stands for testing when an arch implements the
546 context tracking backend but doesn't yet fullfill all the
547 requirements to make the full dynticks feature working.
548 Without the full dynticks, there is no way to test the support
549 for context tracking and the subsystems that rely on it: RCU
550 userspace extended quiescent state and tickless cputime
551 accounting. This option copes with the absence of the full
552 dynticks subsystem by forcing the context tracking on all
555 Say Y only if you're working on the developpement of an
556 architecture backend for the context tracking.
558 Say N otherwise, this option brings an overhead that you
559 don't want in production.
563 int "Tree-based hierarchical RCU fanout value"
566 depends on TREE_RCU || TREE_PREEMPT_RCU
570 This option controls the fanout of hierarchical implementations
571 of RCU, allowing RCU to work efficiently on machines with
572 large numbers of CPUs. This value must be at least the fourth
573 root of NR_CPUS, which allows NR_CPUS to be insanely large.
574 The default value of RCU_FANOUT should be used for production
575 systems, but if you are stress-testing the RCU implementation
576 itself, small RCU_FANOUT values allow you to test large-system
577 code paths on small(er) systems.
579 Select a specific number if testing RCU itself.
580 Take the default if unsure.
582 config RCU_FANOUT_LEAF
583 int "Tree-based hierarchical RCU leaf-level fanout value"
584 range 2 RCU_FANOUT if 64BIT
585 range 2 RCU_FANOUT if !64BIT
586 depends on TREE_RCU || TREE_PREEMPT_RCU
589 This option controls the leaf-level fanout of hierarchical
590 implementations of RCU, and allows trading off cache misses
591 against lock contention. Systems that synchronize their
592 scheduling-clock interrupts for energy-efficiency reasons will
593 want the default because the smaller leaf-level fanout keeps
594 lock contention levels acceptably low. Very large systems
595 (hundreds or thousands of CPUs) will instead want to set this
596 value to the maximum value possible in order to reduce the
597 number of cache misses incurred during RCU's grace-period
598 initialization. These systems tend to run CPU-bound, and thus
599 are not helped by synchronized interrupts, and thus tend to
600 skew them, which reduces lock contention enough that large
601 leaf-level fanouts work well.
603 Select a specific number if testing RCU itself.
605 Select the maximum permissible value for large systems.
607 Take the default if unsure.
609 config RCU_FANOUT_EXACT
610 bool "Disable tree-based hierarchical RCU auto-balancing"
611 depends on TREE_RCU || TREE_PREEMPT_RCU
614 This option forces use of the exact RCU_FANOUT value specified,
615 regardless of imbalances in the hierarchy. This is useful for
616 testing RCU itself, and might one day be useful on systems with
617 strong NUMA behavior.
619 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
623 config RCU_FAST_NO_HZ
624 bool "Accelerate last non-dyntick-idle CPU's grace periods"
625 depends on NO_HZ_COMMON && SMP
628 This option permits CPUs to enter dynticks-idle state even if
629 they have RCU callbacks queued, and prevents RCU from waking
630 these CPUs up more than roughly once every four jiffies (by
631 default, you can adjust this using the rcutree.rcu_idle_gp_delay
632 parameter), thus improving energy efficiency. On the other
633 hand, this option increases the duration of RCU grace periods,
634 for example, slowing down synchronize_rcu().
636 Say Y if energy efficiency is critically important, and you
637 don't care about increased grace-period durations.
639 Say N if you are unsure.
641 config TREE_RCU_TRACE
642 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
645 This option provides tracing for the TREE_RCU and
646 TREE_PREEMPT_RCU implementations, permitting Makefile to
647 trivially select kernel/rcutree_trace.c.
650 bool "Enable RCU priority boosting"
651 depends on RT_MUTEXES && PREEMPT_RCU
654 This option boosts the priority of preempted RCU readers that
655 block the current preemptible RCU grace period for too long.
656 This option also prevents heavy loads from blocking RCU
657 callback invocation for all flavors of RCU.
659 Say Y here if you are working with real-time apps or heavy loads
660 Say N here if you are unsure.
662 config RCU_BOOST_PRIO
663 int "Real-time priority to boost RCU readers to"
668 This option specifies the real-time priority to which long-term
669 preempted RCU readers are to be boosted. If you are working
670 with a real-time application that has one or more CPU-bound
671 threads running at a real-time priority level, you should set
672 RCU_BOOST_PRIO to a priority higher then the highest-priority
673 real-time CPU-bound thread. The default RCU_BOOST_PRIO value
674 of 1 is appropriate in the common case, which is real-time
675 applications that do not have any CPU-bound threads.
677 Some real-time applications might not have a single real-time
678 thread that saturates a given CPU, but instead might have
679 multiple real-time threads that, taken together, fully utilize
680 that CPU. In this case, you should set RCU_BOOST_PRIO to
681 a priority higher than the lowest-priority thread that is
682 conspiring to prevent the CPU from running any non-real-time
683 tasks. For example, if one thread at priority 10 and another
684 thread at priority 5 are between themselves fully consuming
685 the CPU time on a given CPU, then RCU_BOOST_PRIO should be
686 set to priority 6 or higher.
688 Specify the real-time priority, or take the default if unsure.
690 config RCU_BOOST_DELAY
691 int "Milliseconds to delay boosting after RCU grace-period start"
696 This option specifies the time to wait after the beginning of
697 a given grace period before priority-boosting preempted RCU
698 readers blocking that grace period. Note that any RCU reader
699 blocking an expedited RCU grace period is boosted immediately.
701 Accept the default if unsure.
704 bool "Offload RCU callback processing from boot-selected CPUs"
705 depends on TREE_RCU || TREE_PREEMPT_RCU
708 Use this option to reduce OS jitter for aggressive HPC or
709 real-time workloads. It can also be used to offload RCU
710 callback invocation to energy-efficient CPUs in battery-powered
711 asymmetric multiprocessors.
713 This option offloads callback invocation from the set of
714 CPUs specified at boot time by the rcu_nocbs parameter.
715 For each such CPU, a kthread ("rcuox/N") will be created to
716 invoke callbacks, where the "N" is the CPU being offloaded,
717 and where the "x" is "b" for RCU-bh, "p" for RCU-preempt, and
718 "s" for RCU-sched. Nothing prevents this kthread from running
719 on the specified CPUs, but (1) the kthreads may be preempted
720 between each callback, and (2) affinity or cgroups can be used
721 to force the kthreads to run on whatever set of CPUs is desired.
723 Say Y here if you want to help to debug reduced OS jitter.
724 Say N here if you are unsure.
727 prompt "Build-forced no-CBs CPUs"
728 default RCU_NOCB_CPU_NONE
730 This option allows no-CBs CPUs (whose RCU callbacks are invoked
731 from kthreads rather than from softirq context) to be specified
732 at build time. Additional no-CBs CPUs may be specified by
733 the rcu_nocbs= boot parameter.
735 config RCU_NOCB_CPU_NONE
736 bool "No build_forced no-CBs CPUs"
737 depends on RCU_NOCB_CPU && !NO_HZ_FULL
739 This option does not force any of the CPUs to be no-CBs CPUs.
740 Only CPUs designated by the rcu_nocbs= boot parameter will be
741 no-CBs CPUs, whose RCU callbacks will be invoked by per-CPU
742 kthreads whose names begin with "rcuo". All other CPUs will
743 invoke their own RCU callbacks in softirq context.
745 Select this option if you want to choose no-CBs CPUs at
746 boot time, for example, to allow testing of different no-CBs
747 configurations without having to rebuild the kernel each time.
749 config RCU_NOCB_CPU_ZERO
750 bool "CPU 0 is a build_forced no-CBs CPU"
751 depends on RCU_NOCB_CPU && !NO_HZ_FULL
753 This option forces CPU 0 to be a no-CBs CPU, so that its RCU
754 callbacks are invoked by a per-CPU kthread whose name begins
755 with "rcuo". Additional CPUs may be designated as no-CBs
756 CPUs using the rcu_nocbs= boot parameter will be no-CBs CPUs.
757 All other CPUs will invoke their own RCU callbacks in softirq
760 Select this if CPU 0 needs to be a no-CBs CPU for real-time
761 or energy-efficiency reasons, but the real reason it exists
762 is to ensure that randconfig testing covers mixed systems.
764 config RCU_NOCB_CPU_ALL
765 bool "All CPUs are build_forced no-CBs CPUs"
766 depends on RCU_NOCB_CPU
768 This option forces all CPUs to be no-CBs CPUs. The rcu_nocbs=
769 boot parameter will be ignored. All CPUs' RCU callbacks will
770 be executed in the context of per-CPU rcuo kthreads created for
771 this purpose. Assuming that the kthreads whose names start with
772 "rcuo" are bound to "housekeeping" CPUs, this reduces OS jitter
773 on the remaining CPUs, but might decrease memory locality during
774 RCU-callback invocation, thus potentially degrading throughput.
776 Select this if all CPUs need to be no-CBs CPUs for real-time
777 or energy-efficiency reasons.
781 endmenu # "RCU Subsystem"
784 tristate "Kernel .config support"
786 This option enables the complete Linux kernel ".config" file
787 contents to be saved in the kernel. It provides documentation
788 of which kernel options are used in a running kernel or in an
789 on-disk kernel. This information can be extracted from the kernel
790 image file with the script scripts/extract-ikconfig and used as
791 input to rebuild the current kernel or to build another kernel.
792 It can also be extracted from a running kernel by reading
793 /proc/config.gz if enabled (below).
796 bool "Enable access to .config through /proc/config.gz"
797 depends on IKCONFIG && PROC_FS
799 This option enables access to the kernel configuration file
800 through /proc/config.gz.
803 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
807 Select kernel log buffer size as a power of 2.
817 # Architectures with an unreliable sched_clock() should select this:
819 config HAVE_UNSTABLE_SCHED_CLOCK
822 config GENERIC_SCHED_CLOCK
826 # For architectures that want to enable the support for NUMA-affine scheduler
829 config ARCH_SUPPORTS_NUMA_BALANCING
832 # For architectures that (ab)use NUMA to represent different memory regions
833 # all cpu-local but of different latencies, such as SuperH.
835 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
839 # For architectures that are willing to define _PAGE_NUMA as _PAGE_PROTNONE
840 config ARCH_WANTS_PROT_NUMA_PROT_NONE
843 config ARCH_USES_NUMA_PROT_NONE
846 depends on ARCH_WANTS_PROT_NUMA_PROT_NONE
847 depends on NUMA_BALANCING
849 config NUMA_BALANCING_DEFAULT_ENABLED
850 bool "Automatically enable NUMA aware memory/task placement"
852 depends on NUMA_BALANCING
854 If set, autonumic NUMA balancing will be enabled if running on a NUMA
857 config NUMA_BALANCING
858 bool "Memory placement aware NUMA scheduler"
859 depends on ARCH_SUPPORTS_NUMA_BALANCING
860 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
861 depends on SMP && NUMA && MIGRATION
863 This option adds support for automatic NUMA aware memory/task placement.
864 The mechanism is quite primitive and is based on migrating memory when
865 it is references to the node the task is running on.
867 This system will be inactive on UMA systems.
870 boolean "Control Group support"
873 This option adds support for grouping sets of processes together, for
874 use with process control subsystems such as Cpusets, CFS, memory
875 controls or device isolation.
877 - Documentation/scheduler/sched-design-CFS.txt (CFS)
878 - Documentation/cgroups/ (features for grouping, isolation
879 and resource control)
886 bool "Example debug cgroup subsystem"
889 This option enables a simple cgroup subsystem that
890 exports useful debugging information about the cgroups
895 config CGROUP_FREEZER
896 bool "Freezer cgroup subsystem"
898 Provides a way to freeze and unfreeze all tasks in a
902 bool "Device controller for cgroups"
904 Provides a cgroup implementing whitelists for devices which
905 a process in the cgroup can mknod or open.
908 bool "Cpuset support"
910 This option will let you create and manage CPUSETs which
911 allow dynamically partitioning a system into sets of CPUs and
912 Memory Nodes and assigning tasks to run only within those sets.
913 This is primarily useful on large SMP or NUMA systems.
917 config PROC_PID_CPUSET
918 bool "Include legacy /proc/<pid>/cpuset file"
922 config CGROUP_CPUACCT
923 bool "Simple CPU accounting cgroup subsystem"
925 Provides a simple Resource Controller for monitoring the
926 total CPU consumed by the tasks in a cgroup.
928 config RESOURCE_COUNTERS
929 bool "Resource counters"
931 This option enables controller independent resource accounting
932 infrastructure that works with cgroups.
935 bool "Memory Resource Controller for Control Groups"
936 depends on RESOURCE_COUNTERS
939 Provides a memory resource controller that manages both anonymous
940 memory and page cache. (See Documentation/cgroups/memory.txt)
942 Note that setting this option increases fixed memory overhead
943 associated with each page of memory in the system. By this,
944 8(16)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
945 usage tracking struct at boot. Total amount of this is printed out
948 Only enable when you're ok with these trade offs and really
949 sure you need the memory resource controller. Even when you enable
950 this, you can set "cgroup_disable=memory" at your boot option to
951 disable memory resource controller and you can avoid overheads.
952 (and lose benefits of memory resource controller)
954 This config option also selects MM_OWNER config option, which
955 could in turn add some fork/exit overhead.
958 bool "Memory Resource Controller Swap Extension"
959 depends on MEMCG && SWAP
961 Add swap management feature to memory resource controller. When you
962 enable this, you can limit mem+swap usage per cgroup. In other words,
963 when you disable this, memory resource controller has no cares to
964 usage of swap...a process can exhaust all of the swap. This extension
965 is useful when you want to avoid exhaustion swap but this itself
966 adds more overheads and consumes memory for remembering information.
967 Especially if you use 32bit system or small memory system, please
968 be careful about enabling this. When memory resource controller
969 is disabled by boot option, this will be automatically disabled and
970 there will be no overhead from this. Even when you set this config=y,
971 if boot option "swapaccount=0" is set, swap will not be accounted.
972 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
973 size is 4096bytes, 512k per 1Gbytes of swap.
974 config MEMCG_SWAP_ENABLED
975 bool "Memory Resource Controller Swap Extension enabled by default"
976 depends on MEMCG_SWAP
979 Memory Resource Controller Swap Extension comes with its price in
980 a bigger memory consumption. General purpose distribution kernels
981 which want to enable the feature but keep it disabled by default
982 and let the user enable it by swapaccount=1 boot command line
983 parameter should have this option unselected.
984 For those who want to have the feature enabled by default should
985 select this option (if, for some reason, they need to disable it
986 then swapaccount=0 does the trick).
988 bool "Memory Resource Controller Kernel Memory accounting"
990 depends on SLUB || SLAB
992 The Kernel Memory extension for Memory Resource Controller can limit
993 the amount of memory used by kernel objects in the system. Those are
994 fundamentally different from the entities handled by the standard
995 Memory Controller, which are page-based, and can be swapped. Users of
996 the kmem extension can use it to guarantee that no group of processes
997 will ever exhaust kernel resources alone.
999 config CGROUP_HUGETLB
1000 bool "HugeTLB Resource Controller for Control Groups"
1001 depends on RESOURCE_COUNTERS && HUGETLB_PAGE
1004 Provides a cgroup Resource Controller for HugeTLB pages.
1005 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1006 The limit is enforced during page fault. Since HugeTLB doesn't
1007 support page reclaim, enforcing the limit at page fault time implies
1008 that, the application will get SIGBUS signal if it tries to access
1009 HugeTLB pages beyond its limit. This requires the application to know
1010 beforehand how much HugeTLB pages it would require for its use. The
1011 control group is tracked in the third page lru pointer. This means
1012 that we cannot use the controller with huge page less than 3 pages.
1015 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
1016 depends on PERF_EVENTS && CGROUPS
1018 This option extends the per-cpu mode to restrict monitoring to
1019 threads which belong to the cgroup specified and run on the
1024 menuconfig CGROUP_SCHED
1025 bool "Group CPU scheduler"
1028 This feature lets CPU scheduler recognize task groups and control CPU
1029 bandwidth allocation to such task groups. It uses cgroups to group
1033 config FAIR_GROUP_SCHED
1034 bool "Group scheduling for SCHED_OTHER"
1035 depends on CGROUP_SCHED
1036 default CGROUP_SCHED
1038 config CFS_BANDWIDTH
1039 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
1040 depends on FAIR_GROUP_SCHED
1043 This option allows users to define CPU bandwidth rates (limits) for
1044 tasks running within the fair group scheduler. Groups with no limit
1045 set are considered to be unconstrained and will run with no
1047 See tip/Documentation/scheduler/sched-bwc.txt for more information.
1049 config RT_GROUP_SCHED
1050 bool "Group scheduling for SCHED_RR/FIFO"
1051 depends on CGROUP_SCHED
1054 This feature lets you explicitly allocate real CPU bandwidth
1055 to task groups. If enabled, it will also make it impossible to
1056 schedule realtime tasks for non-root users until you allocate
1057 realtime bandwidth for them.
1058 See Documentation/scheduler/sched-rt-group.txt for more information.
1063 bool "Block IO controller"
1067 Generic block IO controller cgroup interface. This is the common
1068 cgroup interface which should be used by various IO controlling
1071 Currently, CFQ IO scheduler uses it to recognize task groups and
1072 control disk bandwidth allocation (proportional time slice allocation)
1073 to such task groups. It is also used by bio throttling logic in
1074 block layer to implement upper limit in IO rates on a device.
1076 This option only enables generic Block IO controller infrastructure.
1077 One needs to also enable actual IO controlling logic/policy. For
1078 enabling proportional weight division of disk bandwidth in CFQ, set
1079 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1080 CONFIG_BLK_DEV_THROTTLING=y.
1082 See Documentation/cgroups/blkio-controller.txt for more information.
1084 config DEBUG_BLK_CGROUP
1085 bool "Enable Block IO controller debugging"
1086 depends on BLK_CGROUP
1089 Enable some debugging help. Currently it exports additional stat
1090 files in a cgroup which can be useful for debugging.
1094 config CHECKPOINT_RESTORE
1095 bool "Checkpoint/restore support" if EXPERT
1098 Enables additional kernel features in a sake of checkpoint/restore.
1099 In particular it adds auxiliary prctl codes to setup process text,
1100 data and heap segment sizes, and a few additional /proc filesystem
1103 If unsure, say N here.
1105 menuconfig NAMESPACES
1106 bool "Namespaces support" if EXPERT
1109 Provides the way to make tasks work with different objects using
1110 the same id. For example same IPC id may refer to different objects
1111 or same user id or pid may refer to different tasks when used in
1112 different namespaces.
1117 bool "UTS namespace"
1120 In this namespace tasks see different info provided with the
1124 bool "IPC namespace"
1125 depends on (SYSVIPC || POSIX_MQUEUE)
1128 In this namespace tasks work with IPC ids which correspond to
1129 different IPC objects in different namespaces.
1132 bool "User namespace"
1133 select UIDGID_STRICT_TYPE_CHECKS
1137 This allows containers, i.e. vservers, to use user namespaces
1138 to provide different user info for different servers.
1140 When user namespaces are enabled in the kernel it is
1141 recommended that the MEMCG and MEMCG_KMEM options also be
1142 enabled and that user-space use the memory control groups to
1143 limit the amount of memory a memory unprivileged users can
1149 bool "PID Namespaces"
1152 Support process id namespaces. This allows having multiple
1153 processes with the same pid as long as they are in different
1154 pid namespaces. This is a building block of containers.
1157 bool "Network namespace"
1161 Allow user space to create what appear to be multiple instances
1162 of the network stack.
1166 config UIDGID_STRICT_TYPE_CHECKS
1167 bool "Require conversions between uid/gids and their internal representation"
1170 While the nececessary conversions are being added to all subsystems this option allows
1171 the code to continue to build for unconverted subsystems.
1173 Say Y here if you want the strict type checking enabled
1175 config SCHED_AUTOGROUP
1176 bool "Automatic process group scheduling"
1180 select FAIR_GROUP_SCHED
1182 This option optimizes the scheduler for common desktop workloads by
1183 automatically creating and populating task groups. This separation
1184 of workloads isolates aggressive CPU burners (like build jobs) from
1185 desktop applications. Task group autogeneration is currently based
1191 config SYSFS_DEPRECATED
1192 bool "Enable deprecated sysfs features to support old userspace tools"
1196 This option adds code that switches the layout of the "block" class
1197 devices, to not show up in /sys/class/block/, but only in
1200 This switch is only active when the sysfs.deprecated=1 boot option is
1201 passed or the SYSFS_DEPRECATED_V2 option is set.
1203 This option allows new kernels to run on old distributions and tools,
1204 which might get confused by /sys/class/block/. Since 2007/2008 all
1205 major distributions and tools handle this just fine.
1207 Recent distributions and userspace tools after 2009/2010 depend on
1208 the existence of /sys/class/block/, and will not work with this
1211 Only if you are using a new kernel on an old distribution, you might
1214 config SYSFS_DEPRECATED_V2
1215 bool "Enable deprecated sysfs features by default"
1218 depends on SYSFS_DEPRECATED
1220 Enable deprecated sysfs by default.
1222 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1225 Only if you are using a new kernel on an old distribution, you might
1226 need to say Y here. Even then, odds are you would not need it
1227 enabled, you can always pass the boot option if absolutely necessary.
1230 bool "Kernel->user space relay support (formerly relayfs)"
1232 This option enables support for relay interface support in
1233 certain file systems (such as debugfs).
1234 It is designed to provide an efficient mechanism for tools and
1235 facilities to relay large amounts of data from kernel space to
1240 config BLK_DEV_INITRD
1241 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1242 depends on BROKEN || !FRV
1244 The initial RAM filesystem is a ramfs which is loaded by the
1245 boot loader (loadlin or lilo) and that is mounted as root
1246 before the normal boot procedure. It is typically used to
1247 load modules needed to mount the "real" root file system,
1248 etc. See <file:Documentation/initrd.txt> for details.
1250 If RAM disk support (BLK_DEV_RAM) is also included, this
1251 also enables initial RAM disk (initrd) support and adds
1252 15 Kbytes (more on some other architectures) to the kernel size.
1258 source "usr/Kconfig"
1262 config CC_OPTIMIZE_FOR_SIZE
1263 bool "Optimize for size"
1265 Enabling this option will pass "-Os" instead of "-O2" to gcc
1266 resulting in a smaller kernel.
1279 config SYSCTL_EXCEPTION_TRACE
1282 Enable support for /proc/sys/debug/exception-trace.
1284 config SYSCTL_ARCH_UNALIGN_NO_WARN
1287 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1288 Allows arch to define/use @no_unaligned_warning to possibly warn
1289 about unaligned access emulation going on under the hood.
1291 config SYSCTL_ARCH_UNALIGN_ALLOW
1294 Enable support for /proc/sys/kernel/unaligned-trap
1295 Allows arches to define/use @unaligned_enabled to runtime toggle
1296 the unaligned access emulation.
1297 see arch/parisc/kernel/unaligned.c for reference
1299 config HAVE_PCSPKR_PLATFORM
1303 bool "Configure standard kernel features (expert users)"
1304 # Unhide debug options, to make the on-by-default options visible
1307 This option allows certain base kernel options and settings
1308 to be disabled or tweaked. This is for specialized
1309 environments which can tolerate a "non-standard" kernel.
1310 Only use this if you really know what you are doing.
1313 bool "Enable 16-bit UID system calls" if EXPERT
1314 depends on HAVE_UID16
1317 This enables the legacy 16-bit UID syscall wrappers.
1319 config SYSCTL_SYSCALL
1320 bool "Sysctl syscall support" if EXPERT
1321 depends on PROC_SYSCTL
1325 sys_sysctl uses binary paths that have been found challenging
1326 to properly maintain and use. The interface in /proc/sys
1327 using paths with ascii names is now the primary path to this
1330 Almost nothing using the binary sysctl interface so if you are
1331 trying to save some space it is probably safe to disable this,
1332 making your kernel marginally smaller.
1334 If unsure say N here.
1337 bool "Load all symbols for debugging/ksymoops" if EXPERT
1340 Say Y here to let the kernel print out symbolic crash information and
1341 symbolic stack backtraces. This increases the size of the kernel
1342 somewhat, as all symbols have to be loaded into the kernel image.
1345 bool "Include all symbols in kallsyms"
1346 depends on DEBUG_KERNEL && KALLSYMS
1348 Normally kallsyms only contains the symbols of functions for nicer
1349 OOPS messages and backtraces (i.e., symbols from the text and inittext
1350 sections). This is sufficient for most cases. And only in very rare
1351 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1352 names of variables from the data sections, etc).
1354 This option makes sure that all symbols are loaded into the kernel
1355 image (i.e., symbols from all sections) in cost of increased kernel
1356 size (depending on the kernel configuration, it may be 300KiB or
1357 something like this).
1359 Say N unless you really need all symbols.
1363 bool "Enable support for printk" if EXPERT
1366 This option enables normal printk support. Removing it
1367 eliminates most of the message strings from the kernel image
1368 and makes the kernel more or less silent. As this makes it
1369 very difficult to diagnose system problems, saying N here is
1370 strongly discouraged.
1373 bool "BUG() support" if EXPERT
1376 Disabling this option eliminates support for BUG and WARN, reducing
1377 the size of your kernel image and potentially quietly ignoring
1378 numerous fatal conditions. You should only consider disabling this
1379 option for embedded systems with no facilities for reporting errors.
1385 bool "Enable ELF core dumps" if EXPERT
1387 Enable support for generating core dumps. Disabling saves about 4k.
1390 config PCSPKR_PLATFORM
1391 bool "Enable PC-Speaker support" if EXPERT
1392 depends on HAVE_PCSPKR_PLATFORM
1396 This option allows to disable the internal PC-Speaker
1397 support, saving some memory.
1401 bool "Enable full-sized data structures for core" if EXPERT
1403 Disabling this option reduces the size of miscellaneous core
1404 kernel data structures. This saves memory on small machines,
1405 but may reduce performance.
1408 bool "Enable futex support" if EXPERT
1412 Disabling this option will cause the kernel to be built without
1413 support for "fast userspace mutexes". The resulting kernel may not
1414 run glibc-based applications correctly.
1417 bool "Enable eventpoll support" if EXPERT
1421 Disabling this option will cause the kernel to be built without
1422 support for epoll family of system calls.
1425 bool "Enable signalfd() system call" if EXPERT
1429 Enable the signalfd() system call that allows to receive signals
1430 on a file descriptor.
1435 bool "Enable timerfd() system call" if EXPERT
1439 Enable the timerfd() system call that allows to receive timer
1440 events on a file descriptor.
1445 bool "Enable eventfd() system call" if EXPERT
1449 Enable the eventfd() system call that allows to receive both
1450 kernel notification (ie. KAIO) or userspace notifications.
1455 bool "Use full shmem filesystem" if EXPERT
1459 The shmem is an internal filesystem used to manage shared memory.
1460 It is backed by swap and manages resource limits. It is also exported
1461 to userspace as tmpfs if TMPFS is enabled. Disabling this
1462 option replaces shmem and tmpfs with the much simpler ramfs code,
1463 which may be appropriate on small systems without swap.
1466 bool "Enable AIO support" if EXPERT
1469 This option enables POSIX asynchronous I/O which may by used
1470 by some high performance threaded applications. Disabling
1471 this option saves about 7k.
1475 bool "Enable PCI quirk workarounds" if EXPERT
1478 This enables workarounds for various PCI chipset
1479 bugs/quirks. Disable this only if your target machine is
1480 unaffected by PCI quirks.
1483 bool "Embedded system"
1486 This option should be enabled if compiling the kernel for
1487 an embedded system so certain expert options are available
1490 config HAVE_PERF_EVENTS
1493 See tools/perf/design.txt for details.
1495 config PERF_USE_VMALLOC
1498 See tools/perf/design.txt for details
1500 menu "Kernel Performance Events And Counters"
1503 bool "Kernel performance events and counters"
1504 default y if PROFILING
1505 depends on HAVE_PERF_EVENTS
1509 Enable kernel support for various performance events provided
1510 by software and hardware.
1512 Software events are supported either built-in or via the
1513 use of generic tracepoints.
1515 Most modern CPUs support performance events via performance
1516 counter registers. These registers count the number of certain
1517 types of hw events: such as instructions executed, cachemisses
1518 suffered, or branches mis-predicted - without slowing down the
1519 kernel or applications. These registers can also trigger interrupts
1520 when a threshold number of events have passed - and can thus be
1521 used to profile the code that runs on that CPU.
1523 The Linux Performance Event subsystem provides an abstraction of
1524 these software and hardware event capabilities, available via a
1525 system call and used by the "perf" utility in tools/perf/. It
1526 provides per task and per CPU counters, and it provides event
1527 capabilities on top of those.
1531 config DEBUG_PERF_USE_VMALLOC
1533 bool "Debug: use vmalloc to back perf mmap() buffers"
1534 depends on PERF_EVENTS && DEBUG_KERNEL
1535 select PERF_USE_VMALLOC
1537 Use vmalloc memory to back perf mmap() buffers.
1539 Mostly useful for debugging the vmalloc code on platforms
1540 that don't require it.
1546 config VM_EVENT_COUNTERS
1548 bool "Enable VM event counters for /proc/vmstat" if EXPERT
1550 VM event counters are needed for event counts to be shown.
1551 This option allows the disabling of the VM event counters
1552 on EXPERT systems. /proc/vmstat will only show page counts
1553 if VM event counters are disabled.
1557 bool "Enable SLUB debugging support" if EXPERT
1558 depends on SLUB && SYSFS
1560 SLUB has extensive debug support features. Disabling these can
1561 result in significant savings in code size. This also disables
1562 SLUB sysfs support. /sys/slab will not exist and there will be
1563 no support for cache validation etc.
1566 bool "Disable heap randomization"
1569 Randomizing heap placement makes heap exploits harder, but it
1570 also breaks ancient binaries (including anything libc5 based).
1571 This option changes the bootup default to heap randomization
1572 disabled, and can be overridden at runtime by setting
1573 /proc/sys/kernel/randomize_va_space to 2.
1575 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1578 prompt "Choose SLAB allocator"
1581 This option allows to select a slab allocator.
1586 The regular slab allocator that is established and known to work
1587 well in all environments. It organizes cache hot objects in
1588 per cpu and per node queues.
1591 bool "SLUB (Unqueued Allocator)"
1593 SLUB is a slab allocator that minimizes cache line usage
1594 instead of managing queues of cached objects (SLAB approach).
1595 Per cpu caching is realized using slabs of objects instead
1596 of queues of objects. SLUB can use memory efficiently
1597 and has enhanced diagnostics. SLUB is the default choice for
1602 bool "SLOB (Simple Allocator)"
1604 SLOB replaces the stock allocator with a drastically simpler
1605 allocator. SLOB is generally more space efficient but
1606 does not perform as well on large systems.
1610 config SLUB_CPU_PARTIAL
1612 depends on SLUB && SMP
1613 bool "SLUB per cpu partial cache"
1615 Per cpu partial caches accellerate objects allocation and freeing
1616 that is local to a processor at the price of more indeterminism
1617 in the latency of the free. On overflow these caches will be cleared
1618 which requires the taking of locks that may cause latency spikes.
1619 Typically one would choose no for a realtime system.
1621 config MMAP_ALLOW_UNINITIALIZED
1622 bool "Allow mmapped anonymous memory to be uninitialized"
1623 depends on EXPERT && !MMU
1626 Normally, and according to the Linux spec, anonymous memory obtained
1627 from mmap() has it's contents cleared before it is passed to
1628 userspace. Enabling this config option allows you to request that
1629 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1630 providing a huge performance boost. If this option is not enabled,
1631 then the flag will be ignored.
1633 This is taken advantage of by uClibc's malloc(), and also by
1634 ELF-FDPIC binfmt's brk and stack allocator.
1636 Because of the obvious security issues, this option should only be
1637 enabled on embedded devices where you control what is run in
1638 userspace. Since that isn't generally a problem on no-MMU systems,
1639 it is normally safe to say Y here.
1641 See Documentation/nommu-mmap.txt for more information.
1644 bool "Profiling support"
1646 Say Y here to enable the extended profiling support mechanisms used
1647 by profilers such as OProfile.
1650 # Place an empty function call at each tracepoint site. Can be
1651 # dynamically changed for a probe function.
1656 source "arch/Kconfig"
1658 endmenu # General setup
1660 config HAVE_GENERIC_DMA_COHERENT
1667 depends on SLAB || SLUB_DEBUG
1675 default 0 if BASE_FULL
1676 default 1 if !BASE_FULL
1679 bool "Enable loadable module support"
1682 Kernel modules are small pieces of compiled code which can
1683 be inserted in the running kernel, rather than being
1684 permanently built into the kernel. You use the "modprobe"
1685 tool to add (and sometimes remove) them. If you say Y here,
1686 many parts of the kernel can be built as modules (by
1687 answering M instead of Y where indicated): this is most
1688 useful for infrequently used options which are not required
1689 for booting. For more information, see the man pages for
1690 modprobe, lsmod, modinfo, insmod and rmmod.
1692 If you say Y here, you will need to run "make
1693 modules_install" to put the modules under /lib/modules/
1694 where modprobe can find them (you may need to be root to do
1701 config MODULE_FORCE_LOAD
1702 bool "Forced module loading"
1705 Allow loading of modules without version information (ie. modprobe
1706 --force). Forced module loading sets the 'F' (forced) taint flag and
1707 is usually a really bad idea.
1709 config MODULE_UNLOAD
1710 bool "Module unloading"
1712 Without this option you will not be able to unload any
1713 modules (note that some modules may not be unloadable
1714 anyway), which makes your kernel smaller, faster
1715 and simpler. If unsure, say Y.
1717 config MODULE_FORCE_UNLOAD
1718 bool "Forced module unloading"
1719 depends on MODULE_UNLOAD
1721 This option allows you to force a module to unload, even if the
1722 kernel believes it is unsafe: the kernel will remove the module
1723 without waiting for anyone to stop using it (using the -f option to
1724 rmmod). This is mainly for kernel developers and desperate users.
1728 bool "Module versioning support"
1730 Usually, you have to use modules compiled with your kernel.
1731 Saying Y here makes it sometimes possible to use modules
1732 compiled for different kernels, by adding enough information
1733 to the modules to (hopefully) spot any changes which would
1734 make them incompatible with the kernel you are running. If
1737 config MODULE_SRCVERSION_ALL
1738 bool "Source checksum for all modules"
1740 Modules which contain a MODULE_VERSION get an extra "srcversion"
1741 field inserted into their modinfo section, which contains a
1742 sum of the source files which made it. This helps maintainers
1743 see exactly which source was used to build a module (since
1744 others sometimes change the module source without updating
1745 the version). With this option, such a "srcversion" field
1746 will be created for all modules. If unsure, say N.
1749 bool "Module signature verification"
1753 select ASYMMETRIC_KEY_TYPE
1754 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1755 select PUBLIC_KEY_ALGO_RSA
1758 select X509_CERTIFICATE_PARSER
1760 Check modules for valid signatures upon load: the signature
1761 is simply appended to the module. For more information see
1762 Documentation/module-signing.txt.
1764 !!!WARNING!!! If you enable this option, you MUST make sure that the
1765 module DOES NOT get stripped after being signed. This includes the
1766 debuginfo strip done by some packagers (such as rpmbuild) and
1767 inclusion into an initramfs that wants the module size reduced.
1769 config MODULE_SIG_FORCE
1770 bool "Require modules to be validly signed"
1771 depends on MODULE_SIG
1773 Reject unsigned modules or signed modules for which we don't have a
1774 key. Without this, such modules will simply taint the kernel.
1776 config MODULE_SIG_ALL
1777 bool "Automatically sign all modules"
1779 depends on MODULE_SIG
1781 Sign all modules during make modules_install. Without this option,
1782 modules must be signed manually, using the scripts/sign-file tool.
1784 comment "Do not forget to sign required modules with scripts/sign-file"
1785 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
1788 prompt "Which hash algorithm should modules be signed with?"
1789 depends on MODULE_SIG
1791 This determines which sort of hashing algorithm will be used during
1792 signature generation. This algorithm _must_ be built into the kernel
1793 directly so that signature verification can take place. It is not
1794 possible to load a signed module containing the algorithm to check
1795 the signature on that module.
1797 config MODULE_SIG_SHA1
1798 bool "Sign modules with SHA-1"
1801 config MODULE_SIG_SHA224
1802 bool "Sign modules with SHA-224"
1803 select CRYPTO_SHA256
1805 config MODULE_SIG_SHA256
1806 bool "Sign modules with SHA-256"
1807 select CRYPTO_SHA256
1809 config MODULE_SIG_SHA384
1810 bool "Sign modules with SHA-384"
1811 select CRYPTO_SHA512
1813 config MODULE_SIG_SHA512
1814 bool "Sign modules with SHA-512"
1815 select CRYPTO_SHA512
1819 config MODULE_SIG_HASH
1821 depends on MODULE_SIG
1822 default "sha1" if MODULE_SIG_SHA1
1823 default "sha224" if MODULE_SIG_SHA224
1824 default "sha256" if MODULE_SIG_SHA256
1825 default "sha384" if MODULE_SIG_SHA384
1826 default "sha512" if MODULE_SIG_SHA512
1830 config INIT_ALL_POSSIBLE
1833 Back when each arch used to define their own cpu_online_mask and
1834 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
1835 with all 1s, and others with all 0s. When they were centralised,
1836 it was better to provide this option than to break all the archs
1837 and have several arch maintainers pursuing me down dark alleys.
1842 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1844 Need stop_machine() primitive.
1846 source "block/Kconfig"
1848 config PREEMPT_NOTIFIERS
1855 # Can be selected by architectures with broken toolchains
1856 # that get confused by correct const<->read_only section
1858 config BROKEN_RODATA
1864 Build a simple ASN.1 grammar compiler that produces a bytecode output
1865 that can be interpreted by the ASN.1 stream decoder and used to
1866 inform it as to what tags are to be expected in a stream and what
1867 functions to call on what tags.
1869 source "kernel/Kconfig.locks"
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