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 "uselib syscall"
280 This option enables the uselib syscall, a system call used in the
281 dynamic linker from libc5 and earlier. glibc does not use this
282 system call. If you intend to run programs built on libc5 or
283 earlier, you may need to enable this syscall. Current systems
284 running glibc can safely disable this.
287 bool "Auditing support"
290 Enable auditing infrastructure that can be used with another
291 kernel subsystem, such as SELinux (which requires this for
292 logging of avc messages output). Does not do system-call
293 auditing without CONFIG_AUDITSYSCALL.
296 bool "Enable system-call auditing support"
297 depends on AUDIT && (X86 || PARISC || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || (ARM && AEABI && !OABI_COMPAT) || ALPHA)
298 default y if SECURITY_SELINUX
300 Enable low-overhead system-call auditing infrastructure that
301 can be used independently or with another kernel subsystem,
306 depends on AUDITSYSCALL
311 depends on AUDITSYSCALL
314 source "kernel/irq/Kconfig"
315 source "kernel/time/Kconfig"
317 menu "CPU/Task time and stats accounting"
319 config VIRT_CPU_ACCOUNTING
323 prompt "Cputime accounting"
324 default TICK_CPU_ACCOUNTING if !PPC64
325 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
327 # Kind of a stub config for the pure tick based cputime accounting
328 config TICK_CPU_ACCOUNTING
329 bool "Simple tick based cputime accounting"
330 depends on !S390 && !NO_HZ_FULL
332 This is the basic tick based cputime accounting that maintains
333 statistics about user, system and idle time spent on per jiffies
338 config VIRT_CPU_ACCOUNTING_NATIVE
339 bool "Deterministic task and CPU time accounting"
340 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
341 select VIRT_CPU_ACCOUNTING
343 Select this option to enable more accurate task and CPU time
344 accounting. This is done by reading a CPU counter on each
345 kernel entry and exit and on transitions within the kernel
346 between system, softirq and hardirq state, so there is a
347 small performance impact. In the case of s390 or IBM POWER > 5,
348 this also enables accounting of stolen time on logically-partitioned
351 config VIRT_CPU_ACCOUNTING_GEN
352 bool "Full dynticks CPU time accounting"
353 depends on HAVE_CONTEXT_TRACKING
354 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
355 select VIRT_CPU_ACCOUNTING
356 select CONTEXT_TRACKING
358 Select this option to enable task and CPU time accounting on full
359 dynticks systems. This accounting is implemented by watching every
360 kernel-user boundaries using the context tracking subsystem.
361 The accounting is thus performed at the expense of some significant
364 For now this is only useful if you are working on the full
365 dynticks subsystem development.
369 config IRQ_TIME_ACCOUNTING
370 bool "Fine granularity task level IRQ time accounting"
371 depends on HAVE_IRQ_TIME_ACCOUNTING && !NO_HZ_FULL
373 Select this option to enable fine granularity task irq time
374 accounting. This is done by reading a timestamp on each
375 transitions between softirq and hardirq state, so there can be a
376 small performance impact.
378 If in doubt, say N here.
382 config BSD_PROCESS_ACCT
383 bool "BSD Process Accounting"
385 If you say Y here, a user level program will be able to instruct the
386 kernel (via a special system call) to write process accounting
387 information to a file: whenever a process exits, information about
388 that process will be appended to the file by the kernel. The
389 information includes things such as creation time, owning user,
390 command name, memory usage, controlling terminal etc. (the complete
391 list is in the struct acct in <file:include/linux/acct.h>). It is
392 up to the user level program to do useful things with this
393 information. This is generally a good idea, so say Y.
395 config BSD_PROCESS_ACCT_V3
396 bool "BSD Process Accounting version 3 file format"
397 depends on BSD_PROCESS_ACCT
400 If you say Y here, the process accounting information is written
401 in a new file format that also logs the process IDs of each
402 process and it's parent. Note that this file format is incompatible
403 with previous v0/v1/v2 file formats, so you will need updated tools
404 for processing it. A preliminary version of these tools is available
405 at <http://www.gnu.org/software/acct/>.
408 bool "Export task/process statistics through netlink"
412 Export selected statistics for tasks/processes through the
413 generic netlink interface. Unlike BSD process accounting, the
414 statistics are available during the lifetime of tasks/processes as
415 responses to commands. Like BSD accounting, they are sent to user
420 config TASK_DELAY_ACCT
421 bool "Enable per-task delay accounting"
424 Collect information on time spent by a task waiting for system
425 resources like cpu, synchronous block I/O completion and swapping
426 in pages. Such statistics can help in setting a task's priorities
427 relative to other tasks for cpu, io, rss limits etc.
432 bool "Enable extended accounting over taskstats"
435 Collect extended task accounting data and send the data
436 to userland for processing over the taskstats interface.
440 config TASK_IO_ACCOUNTING
441 bool "Enable per-task storage I/O accounting"
442 depends on TASK_XACCT
444 Collect information on the number of bytes of storage I/O which this
449 endmenu # "CPU/Task time and stats accounting"
454 prompt "RCU Implementation"
458 bool "Tree-based hierarchical RCU"
459 depends on !PREEMPT && SMP
462 This option selects the RCU implementation that is
463 designed for very large SMP system with hundreds or
464 thousands of CPUs. It also scales down nicely to
467 config TREE_PREEMPT_RCU
468 bool "Preemptible tree-based hierarchical RCU"
472 This option selects the RCU implementation that is
473 designed for very large SMP systems with hundreds or
474 thousands of CPUs, but for which real-time response
475 is also required. It also scales down nicely to
478 Select this option if you are unsure.
481 bool "UP-only small-memory-footprint RCU"
482 depends on !PREEMPT && !SMP
484 This option selects the RCU implementation that is
485 designed for UP systems from which real-time response
486 is not required. This option greatly reduces the
487 memory footprint of RCU.
492 def_bool TREE_PREEMPT_RCU
494 This option enables preemptible-RCU code that is common between
495 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
497 config RCU_STALL_COMMON
498 def_bool ( TREE_RCU || TREE_PREEMPT_RCU || RCU_TRACE )
500 This option enables RCU CPU stall code that is common between
501 the TINY and TREE variants of RCU. The purpose is to allow
502 the tiny variants to disable RCU CPU stall warnings, while
503 making these warnings mandatory for the tree variants.
505 config CONTEXT_TRACKING
509 bool "Consider userspace as in RCU extended quiescent state"
510 depends on HAVE_CONTEXT_TRACKING && SMP
511 select CONTEXT_TRACKING
513 This option sets hooks on kernel / userspace boundaries and
514 puts RCU in extended quiescent state when the CPU runs in
515 userspace. It means that when a CPU runs in userspace, it is
516 excluded from the global RCU state machine and thus doesn't
517 try to keep the timer tick on for RCU.
519 Unless you want to hack and help the development of the full
520 dynticks mode, you shouldn't enable this option. It also
521 adds unnecessary overhead.
525 config CONTEXT_TRACKING_FORCE
526 bool "Force context tracking"
527 depends on CONTEXT_TRACKING
528 default y if !NO_HZ_FULL
530 The major pre-requirement for full dynticks to work is to
531 support the context tracking subsystem. But there are also
532 other dependencies to provide in order to make the full
535 This option stands for testing when an arch implements the
536 context tracking backend but doesn't yet fullfill all the
537 requirements to make the full dynticks feature working.
538 Without the full dynticks, there is no way to test the support
539 for context tracking and the subsystems that rely on it: RCU
540 userspace extended quiescent state and tickless cputime
541 accounting. This option copes with the absence of the full
542 dynticks subsystem by forcing the context tracking on all
545 Say Y only if you're working on the development of an
546 architecture backend for the context tracking.
548 Say N otherwise, this option brings an overhead that you
549 don't want in production.
553 int "Tree-based hierarchical RCU fanout value"
556 depends on TREE_RCU || TREE_PREEMPT_RCU
560 This option controls the fanout of hierarchical implementations
561 of RCU, allowing RCU to work efficiently on machines with
562 large numbers of CPUs. This value must be at least the fourth
563 root of NR_CPUS, which allows NR_CPUS to be insanely large.
564 The default value of RCU_FANOUT should be used for production
565 systems, but if you are stress-testing the RCU implementation
566 itself, small RCU_FANOUT values allow you to test large-system
567 code paths on small(er) systems.
569 Select a specific number if testing RCU itself.
570 Take the default if unsure.
572 config RCU_FANOUT_LEAF
573 int "Tree-based hierarchical RCU leaf-level fanout value"
574 range 2 RCU_FANOUT if 64BIT
575 range 2 RCU_FANOUT if !64BIT
576 depends on TREE_RCU || TREE_PREEMPT_RCU
579 This option controls the leaf-level fanout of hierarchical
580 implementations of RCU, and allows trading off cache misses
581 against lock contention. Systems that synchronize their
582 scheduling-clock interrupts for energy-efficiency reasons will
583 want the default because the smaller leaf-level fanout keeps
584 lock contention levels acceptably low. Very large systems
585 (hundreds or thousands of CPUs) will instead want to set this
586 value to the maximum value possible in order to reduce the
587 number of cache misses incurred during RCU's grace-period
588 initialization. These systems tend to run CPU-bound, and thus
589 are not helped by synchronized interrupts, and thus tend to
590 skew them, which reduces lock contention enough that large
591 leaf-level fanouts work well.
593 Select a specific number if testing RCU itself.
595 Select the maximum permissible value for large systems.
597 Take the default if unsure.
599 config RCU_FANOUT_EXACT
600 bool "Disable tree-based hierarchical RCU auto-balancing"
601 depends on TREE_RCU || TREE_PREEMPT_RCU
604 This option forces use of the exact RCU_FANOUT value specified,
605 regardless of imbalances in the hierarchy. This is useful for
606 testing RCU itself, and might one day be useful on systems with
607 strong NUMA behavior.
609 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
613 config RCU_FAST_NO_HZ
614 bool "Accelerate last non-dyntick-idle CPU's grace periods"
615 depends on NO_HZ_COMMON && SMP
618 This option permits CPUs to enter dynticks-idle state even if
619 they have RCU callbacks queued, and prevents RCU from waking
620 these CPUs up more than roughly once every four jiffies (by
621 default, you can adjust this using the rcutree.rcu_idle_gp_delay
622 parameter), thus improving energy efficiency. On the other
623 hand, this option increases the duration of RCU grace periods,
624 for example, slowing down synchronize_rcu().
626 Say Y if energy efficiency is critically important, and you
627 don't care about increased grace-period durations.
629 Say N if you are unsure.
631 config TREE_RCU_TRACE
632 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
635 This option provides tracing for the TREE_RCU and
636 TREE_PREEMPT_RCU implementations, permitting Makefile to
637 trivially select kernel/rcutree_trace.c.
640 bool "Enable RCU priority boosting"
641 depends on RT_MUTEXES && PREEMPT_RCU
644 This option boosts the priority of preempted RCU readers that
645 block the current preemptible RCU grace period for too long.
646 This option also prevents heavy loads from blocking RCU
647 callback invocation for all flavors of RCU.
649 Say Y here if you are working with real-time apps or heavy loads
650 Say N here if you are unsure.
652 config RCU_BOOST_PRIO
653 int "Real-time priority to boost RCU readers to"
658 This option specifies the real-time priority to which long-term
659 preempted RCU readers are to be boosted. If you are working
660 with a real-time application that has one or more CPU-bound
661 threads running at a real-time priority level, you should set
662 RCU_BOOST_PRIO to a priority higher then the highest-priority
663 real-time CPU-bound thread. The default RCU_BOOST_PRIO value
664 of 1 is appropriate in the common case, which is real-time
665 applications that do not have any CPU-bound threads.
667 Some real-time applications might not have a single real-time
668 thread that saturates a given CPU, but instead might have
669 multiple real-time threads that, taken together, fully utilize
670 that CPU. In this case, you should set RCU_BOOST_PRIO to
671 a priority higher than the lowest-priority thread that is
672 conspiring to prevent the CPU from running any non-real-time
673 tasks. For example, if one thread at priority 10 and another
674 thread at priority 5 are between themselves fully consuming
675 the CPU time on a given CPU, then RCU_BOOST_PRIO should be
676 set to priority 6 or higher.
678 Specify the real-time priority, or take the default if unsure.
680 config RCU_BOOST_DELAY
681 int "Milliseconds to delay boosting after RCU grace-period start"
686 This option specifies the time to wait after the beginning of
687 a given grace period before priority-boosting preempted RCU
688 readers blocking that grace period. Note that any RCU reader
689 blocking an expedited RCU grace period is boosted immediately.
691 Accept the default if unsure.
694 bool "Offload RCU callback processing from boot-selected CPUs"
695 depends on TREE_RCU || TREE_PREEMPT_RCU
698 Use this option to reduce OS jitter for aggressive HPC or
699 real-time workloads. It can also be used to offload RCU
700 callback invocation to energy-efficient CPUs in battery-powered
701 asymmetric multiprocessors.
703 This option offloads callback invocation from the set of
704 CPUs specified at boot time by the rcu_nocbs parameter.
705 For each such CPU, a kthread ("rcuox/N") will be created to
706 invoke callbacks, where the "N" is the CPU being offloaded,
707 and where the "x" is "b" for RCU-bh, "p" for RCU-preempt, and
708 "s" for RCU-sched. Nothing prevents this kthread from running
709 on the specified CPUs, but (1) the kthreads may be preempted
710 between each callback, and (2) affinity or cgroups can be used
711 to force the kthreads to run on whatever set of CPUs is desired.
713 Say Y here if you want to help to debug reduced OS jitter.
714 Say N here if you are unsure.
717 prompt "Build-forced no-CBs CPUs"
718 default RCU_NOCB_CPU_NONE
720 This option allows no-CBs CPUs (whose RCU callbacks are invoked
721 from kthreads rather than from softirq context) to be specified
722 at build time. Additional no-CBs CPUs may be specified by
723 the rcu_nocbs= boot parameter.
725 config RCU_NOCB_CPU_NONE
726 bool "No build_forced no-CBs CPUs"
727 depends on RCU_NOCB_CPU && !NO_HZ_FULL
729 This option does not force any of the CPUs to be no-CBs CPUs.
730 Only CPUs designated by the rcu_nocbs= boot parameter will be
731 no-CBs CPUs, whose RCU callbacks will be invoked by per-CPU
732 kthreads whose names begin with "rcuo". All other CPUs will
733 invoke their own RCU callbacks in softirq context.
735 Select this option if you want to choose no-CBs CPUs at
736 boot time, for example, to allow testing of different no-CBs
737 configurations without having to rebuild the kernel each time.
739 config RCU_NOCB_CPU_ZERO
740 bool "CPU 0 is a build_forced no-CBs CPU"
741 depends on RCU_NOCB_CPU && !NO_HZ_FULL
743 This option forces CPU 0 to be a no-CBs CPU, so that its RCU
744 callbacks are invoked by a per-CPU kthread whose name begins
745 with "rcuo". Additional CPUs may be designated as no-CBs
746 CPUs using the rcu_nocbs= boot parameter will be no-CBs CPUs.
747 All other CPUs will invoke their own RCU callbacks in softirq
750 Select this if CPU 0 needs to be a no-CBs CPU for real-time
751 or energy-efficiency reasons, but the real reason it exists
752 is to ensure that randconfig testing covers mixed systems.
754 config RCU_NOCB_CPU_ALL
755 bool "All CPUs are build_forced no-CBs CPUs"
756 depends on RCU_NOCB_CPU
758 This option forces all CPUs to be no-CBs CPUs. The rcu_nocbs=
759 boot parameter will be ignored. All CPUs' RCU callbacks will
760 be executed in the context of per-CPU rcuo kthreads created for
761 this purpose. Assuming that the kthreads whose names start with
762 "rcuo" are bound to "housekeeping" CPUs, this reduces OS jitter
763 on the remaining CPUs, but might decrease memory locality during
764 RCU-callback invocation, thus potentially degrading throughput.
766 Select this if all CPUs need to be no-CBs CPUs for real-time
767 or energy-efficiency reasons.
771 endmenu # "RCU Subsystem"
774 tristate "Kernel .config support"
776 This option enables the complete Linux kernel ".config" file
777 contents to be saved in the kernel. It provides documentation
778 of which kernel options are used in a running kernel or in an
779 on-disk kernel. This information can be extracted from the kernel
780 image file with the script scripts/extract-ikconfig and used as
781 input to rebuild the current kernel or to build another kernel.
782 It can also be extracted from a running kernel by reading
783 /proc/config.gz if enabled (below).
786 bool "Enable access to .config through /proc/config.gz"
787 depends on IKCONFIG && PROC_FS
789 This option enables access to the kernel configuration file
790 through /proc/config.gz.
793 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
797 Select kernel log buffer size as a power of 2.
807 # Architectures with an unreliable sched_clock() should select this:
809 config HAVE_UNSTABLE_SCHED_CLOCK
812 config GENERIC_SCHED_CLOCK
816 # For architectures that want to enable the support for NUMA-affine scheduler
819 config ARCH_SUPPORTS_NUMA_BALANCING
823 # For architectures that know their GCC __int128 support is sound
825 config ARCH_SUPPORTS_INT128
828 # For architectures that (ab)use NUMA to represent different memory regions
829 # all cpu-local but of different latencies, such as SuperH.
831 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
835 # For architectures that are willing to define _PAGE_NUMA as _PAGE_PROTNONE
836 config ARCH_WANTS_PROT_NUMA_PROT_NONE
839 config ARCH_USES_NUMA_PROT_NONE
842 depends on ARCH_WANTS_PROT_NUMA_PROT_NONE
843 depends on NUMA_BALANCING
845 config NUMA_BALANCING_DEFAULT_ENABLED
846 bool "Automatically enable NUMA aware memory/task placement"
848 depends on NUMA_BALANCING
850 If set, automatic NUMA balancing will be enabled if running on a NUMA
853 config NUMA_BALANCING
854 bool "Memory placement aware NUMA scheduler"
855 depends on ARCH_SUPPORTS_NUMA_BALANCING
856 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
857 depends on SMP && NUMA && MIGRATION
859 This option adds support for automatic NUMA aware memory/task placement.
860 The mechanism is quite primitive and is based on migrating memory when
861 it has references to the node the task is running on.
863 This system will be inactive on UMA systems.
866 boolean "Control Group support"
869 This option adds support for grouping sets of processes together, for
870 use with process control subsystems such as Cpusets, CFS, memory
871 controls or device isolation.
873 - Documentation/scheduler/sched-design-CFS.txt (CFS)
874 - Documentation/cgroups/ (features for grouping, isolation
875 and resource control)
882 bool "Example debug cgroup subsystem"
885 This option enables a simple cgroup subsystem that
886 exports useful debugging information about the cgroups
891 config CGROUP_FREEZER
892 bool "Freezer cgroup subsystem"
894 Provides a way to freeze and unfreeze all tasks in a
898 bool "Device controller for cgroups"
900 Provides a cgroup implementing whitelists for devices which
901 a process in the cgroup can mknod or open.
904 bool "Cpuset support"
906 This option will let you create and manage CPUSETs which
907 allow dynamically partitioning a system into sets of CPUs and
908 Memory Nodes and assigning tasks to run only within those sets.
909 This is primarily useful on large SMP or NUMA systems.
913 config PROC_PID_CPUSET
914 bool "Include legacy /proc/<pid>/cpuset file"
918 config CGROUP_CPUACCT
919 bool "Simple CPU accounting cgroup subsystem"
921 Provides a simple Resource Controller for monitoring the
922 total CPU consumed by the tasks in a cgroup.
924 config RESOURCE_COUNTERS
925 bool "Resource counters"
927 This option enables controller independent resource accounting
928 infrastructure that works with cgroups.
931 bool "Memory Resource Controller for Control Groups"
932 depends on RESOURCE_COUNTERS
936 Provides a memory resource controller that manages both anonymous
937 memory and page cache. (See Documentation/cgroups/memory.txt)
939 Note that setting this option increases fixed memory overhead
940 associated with each page of memory in the system. By this,
941 8(16)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
942 usage tracking struct at boot. Total amount of this is printed out
945 Only enable when you're ok with these trade offs and really
946 sure you need the memory resource controller. Even when you enable
947 this, you can set "cgroup_disable=memory" at your boot option to
948 disable memory resource controller and you can avoid overheads.
949 (and lose benefits of memory resource controller)
951 This config option also selects MM_OWNER config option, which
952 could in turn add some fork/exit overhead.
955 bool "Memory Resource Controller Swap Extension"
956 depends on MEMCG && SWAP
958 Add swap management feature to memory resource controller. When you
959 enable this, you can limit mem+swap usage per cgroup. In other words,
960 when you disable this, memory resource controller has no cares to
961 usage of swap...a process can exhaust all of the swap. This extension
962 is useful when you want to avoid exhaustion swap but this itself
963 adds more overheads and consumes memory for remembering information.
964 Especially if you use 32bit system or small memory system, please
965 be careful about enabling this. When memory resource controller
966 is disabled by boot option, this will be automatically disabled and
967 there will be no overhead from this. Even when you set this config=y,
968 if boot option "swapaccount=0" is set, swap will not be accounted.
969 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
970 size is 4096bytes, 512k per 1Gbytes of swap.
971 config MEMCG_SWAP_ENABLED
972 bool "Memory Resource Controller Swap Extension enabled by default"
973 depends on MEMCG_SWAP
976 Memory Resource Controller Swap Extension comes with its price in
977 a bigger memory consumption. General purpose distribution kernels
978 which want to enable the feature but keep it disabled by default
979 and let the user enable it by swapaccount=1 boot command line
980 parameter should have this option unselected.
981 For those who want to have the feature enabled by default should
982 select this option (if, for some reason, they need to disable it
983 then swapaccount=0 does the trick).
985 bool "Memory Resource Controller Kernel Memory accounting"
987 depends on SLUB || SLAB
989 The Kernel Memory extension for Memory Resource Controller can limit
990 the amount of memory used by kernel objects in the system. Those are
991 fundamentally different from the entities handled by the standard
992 Memory Controller, which are page-based, and can be swapped. Users of
993 the kmem extension can use it to guarantee that no group of processes
994 will ever exhaust kernel resources alone.
996 config CGROUP_HUGETLB
997 bool "HugeTLB Resource Controller for Control Groups"
998 depends on RESOURCE_COUNTERS && HUGETLB_PAGE
1001 Provides a cgroup Resource Controller for HugeTLB pages.
1002 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1003 The limit is enforced during page fault. Since HugeTLB doesn't
1004 support page reclaim, enforcing the limit at page fault time implies
1005 that, the application will get SIGBUS signal if it tries to access
1006 HugeTLB pages beyond its limit. This requires the application to know
1007 beforehand how much HugeTLB pages it would require for its use. The
1008 control group is tracked in the third page lru pointer. This means
1009 that we cannot use the controller with huge page less than 3 pages.
1012 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
1013 depends on PERF_EVENTS && CGROUPS
1015 This option extends the per-cpu mode to restrict monitoring to
1016 threads which belong to the cgroup specified and run on the
1021 menuconfig CGROUP_SCHED
1022 bool "Group CPU scheduler"
1025 This feature lets CPU scheduler recognize task groups and control CPU
1026 bandwidth allocation to such task groups. It uses cgroups to group
1030 config FAIR_GROUP_SCHED
1031 bool "Group scheduling for SCHED_OTHER"
1032 depends on CGROUP_SCHED
1033 default CGROUP_SCHED
1035 config CFS_BANDWIDTH
1036 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
1037 depends on FAIR_GROUP_SCHED
1040 This option allows users to define CPU bandwidth rates (limits) for
1041 tasks running within the fair group scheduler. Groups with no limit
1042 set are considered to be unconstrained and will run with no
1044 See tip/Documentation/scheduler/sched-bwc.txt for more information.
1046 config RT_GROUP_SCHED
1047 bool "Group scheduling for SCHED_RR/FIFO"
1048 depends on CGROUP_SCHED
1051 This feature lets you explicitly allocate real CPU bandwidth
1052 to task groups. If enabled, it will also make it impossible to
1053 schedule realtime tasks for non-root users until you allocate
1054 realtime bandwidth for them.
1055 See Documentation/scheduler/sched-rt-group.txt for more information.
1060 bool "Block IO controller"
1064 Generic block IO controller cgroup interface. This is the common
1065 cgroup interface which should be used by various IO controlling
1068 Currently, CFQ IO scheduler uses it to recognize task groups and
1069 control disk bandwidth allocation (proportional time slice allocation)
1070 to such task groups. It is also used by bio throttling logic in
1071 block layer to implement upper limit in IO rates on a device.
1073 This option only enables generic Block IO controller infrastructure.
1074 One needs to also enable actual IO controlling logic/policy. For
1075 enabling proportional weight division of disk bandwidth in CFQ, set
1076 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1077 CONFIG_BLK_DEV_THROTTLING=y.
1079 See Documentation/cgroups/blkio-controller.txt for more information.
1081 config DEBUG_BLK_CGROUP
1082 bool "Enable Block IO controller debugging"
1083 depends on BLK_CGROUP
1086 Enable some debugging help. Currently it exports additional stat
1087 files in a cgroup which can be useful for debugging.
1091 config CHECKPOINT_RESTORE
1092 bool "Checkpoint/restore support" if EXPERT
1095 Enables additional kernel features in a sake of checkpoint/restore.
1096 In particular it adds auxiliary prctl codes to setup process text,
1097 data and heap segment sizes, and a few additional /proc filesystem
1100 If unsure, say N here.
1102 menuconfig NAMESPACES
1103 bool "Namespaces support" if EXPERT
1106 Provides the way to make tasks work with different objects using
1107 the same id. For example same IPC id may refer to different objects
1108 or same user id or pid may refer to different tasks when used in
1109 different namespaces.
1114 bool "UTS namespace"
1117 In this namespace tasks see different info provided with the
1121 bool "IPC namespace"
1122 depends on (SYSVIPC || POSIX_MQUEUE)
1125 In this namespace tasks work with IPC ids which correspond to
1126 different IPC objects in different namespaces.
1129 bool "User namespace"
1132 This allows containers, i.e. vservers, to use user namespaces
1133 to provide different user info for different servers.
1135 When user namespaces are enabled in the kernel it is
1136 recommended that the MEMCG and MEMCG_KMEM options also be
1137 enabled and that user-space use the memory control groups to
1138 limit the amount of memory a memory unprivileged users can
1144 bool "PID Namespaces"
1147 Support process id namespaces. This allows having multiple
1148 processes with the same pid as long as they are in different
1149 pid namespaces. This is a building block of containers.
1152 bool "Network namespace"
1156 Allow user space to create what appear to be multiple instances
1157 of the network stack.
1161 config SCHED_AUTOGROUP
1162 bool "Automatic process group scheduling"
1165 select FAIR_GROUP_SCHED
1167 This option optimizes the scheduler for common desktop workloads by
1168 automatically creating and populating task groups. This separation
1169 of workloads isolates aggressive CPU burners (like build jobs) from
1170 desktop applications. Task group autogeneration is currently based
1176 config SYSFS_DEPRECATED
1177 bool "Enable deprecated sysfs features to support old userspace tools"
1181 This option adds code that switches the layout of the "block" class
1182 devices, to not show up in /sys/class/block/, but only in
1185 This switch is only active when the sysfs.deprecated=1 boot option is
1186 passed or the SYSFS_DEPRECATED_V2 option is set.
1188 This option allows new kernels to run on old distributions and tools,
1189 which might get confused by /sys/class/block/. Since 2007/2008 all
1190 major distributions and tools handle this just fine.
1192 Recent distributions and userspace tools after 2009/2010 depend on
1193 the existence of /sys/class/block/, and will not work with this
1196 Only if you are using a new kernel on an old distribution, you might
1199 config SYSFS_DEPRECATED_V2
1200 bool "Enable deprecated sysfs features by default"
1203 depends on SYSFS_DEPRECATED
1205 Enable deprecated sysfs by default.
1207 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1210 Only if you are using a new kernel on an old distribution, you might
1211 need to say Y here. Even then, odds are you would not need it
1212 enabled, you can always pass the boot option if absolutely necessary.
1215 bool "Kernel->user space relay support (formerly relayfs)"
1217 This option enables support for relay interface support in
1218 certain file systems (such as debugfs).
1219 It is designed to provide an efficient mechanism for tools and
1220 facilities to relay large amounts of data from kernel space to
1225 config BLK_DEV_INITRD
1226 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1227 depends on BROKEN || !FRV
1229 The initial RAM filesystem is a ramfs which is loaded by the
1230 boot loader (loadlin or lilo) and that is mounted as root
1231 before the normal boot procedure. It is typically used to
1232 load modules needed to mount the "real" root file system,
1233 etc. See <file:Documentation/initrd.txt> for details.
1235 If RAM disk support (BLK_DEV_RAM) is also included, this
1236 also enables initial RAM disk (initrd) support and adds
1237 15 Kbytes (more on some other architectures) to the kernel size.
1243 source "usr/Kconfig"
1247 config CC_OPTIMIZE_FOR_SIZE
1248 bool "Optimize for size"
1250 Enabling this option will pass "-Os" instead of "-O2" to gcc
1251 resulting in a smaller kernel.
1264 config SYSCTL_EXCEPTION_TRACE
1267 Enable support for /proc/sys/debug/exception-trace.
1269 config SYSCTL_ARCH_UNALIGN_NO_WARN
1272 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1273 Allows arch to define/use @no_unaligned_warning to possibly warn
1274 about unaligned access emulation going on under the hood.
1276 config SYSCTL_ARCH_UNALIGN_ALLOW
1279 Enable support for /proc/sys/kernel/unaligned-trap
1280 Allows arches to define/use @unaligned_enabled to runtime toggle
1281 the unaligned access emulation.
1282 see arch/parisc/kernel/unaligned.c for reference
1284 config HAVE_PCSPKR_PLATFORM
1288 bool "Configure standard kernel features (expert users)"
1289 # Unhide debug options, to make the on-by-default options visible
1292 This option allows certain base kernel options and settings
1293 to be disabled or tweaked. This is for specialized
1294 environments which can tolerate a "non-standard" kernel.
1295 Only use this if you really know what you are doing.
1298 bool "Enable 16-bit UID system calls" if EXPERT
1299 depends on HAVE_UID16
1302 This enables the legacy 16-bit UID syscall wrappers.
1304 config SYSFS_SYSCALL
1305 bool "Sysfs syscall support" if EXPERT
1308 sys_sysfs is an obsolete system call no longer supported in libc.
1309 Note that disabling this option is more secure but might break
1310 compatibility with some systems.
1312 If unsure say Y here.
1314 config SYSCTL_SYSCALL
1315 bool "Sysctl syscall support" if EXPERT
1316 depends on PROC_SYSCTL
1320 sys_sysctl uses binary paths that have been found challenging
1321 to properly maintain and use. The interface in /proc/sys
1322 using paths with ascii names is now the primary path to this
1325 Almost nothing using the binary sysctl interface so if you are
1326 trying to save some space it is probably safe to disable this,
1327 making your kernel marginally smaller.
1329 If unsure say N here.
1332 bool "Load all symbols for debugging/ksymoops" if EXPERT
1335 Say Y here to let the kernel print out symbolic crash information and
1336 symbolic stack backtraces. This increases the size of the kernel
1337 somewhat, as all symbols have to be loaded into the kernel image.
1340 bool "Include all symbols in kallsyms"
1341 depends on DEBUG_KERNEL && KALLSYMS
1343 Normally kallsyms only contains the symbols of functions for nicer
1344 OOPS messages and backtraces (i.e., symbols from the text and inittext
1345 sections). This is sufficient for most cases. And only in very rare
1346 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1347 names of variables from the data sections, etc).
1349 This option makes sure that all symbols are loaded into the kernel
1350 image (i.e., symbols from all sections) in cost of increased kernel
1351 size (depending on the kernel configuration, it may be 300KiB or
1352 something like this).
1354 Say N unless you really need all symbols.
1358 bool "Enable support for printk" if EXPERT
1361 This option enables normal printk support. Removing it
1362 eliminates most of the message strings from the kernel image
1363 and makes the kernel more or less silent. As this makes it
1364 very difficult to diagnose system problems, saying N here is
1365 strongly discouraged.
1368 bool "BUG() support" if EXPERT
1371 Disabling this option eliminates support for BUG and WARN, reducing
1372 the size of your kernel image and potentially quietly ignoring
1373 numerous fatal conditions. You should only consider disabling this
1374 option for embedded systems with no facilities for reporting errors.
1380 bool "Enable ELF core dumps" if EXPERT
1382 Enable support for generating core dumps. Disabling saves about 4k.
1385 config PCSPKR_PLATFORM
1386 bool "Enable PC-Speaker support" if EXPERT
1387 depends on HAVE_PCSPKR_PLATFORM
1391 This option allows to disable the internal PC-Speaker
1392 support, saving some memory.
1396 bool "Enable full-sized data structures for core" if EXPERT
1398 Disabling this option reduces the size of miscellaneous core
1399 kernel data structures. This saves memory on small machines,
1400 but may reduce performance.
1403 bool "Enable futex support" if EXPERT
1407 Disabling this option will cause the kernel to be built without
1408 support for "fast userspace mutexes". The resulting kernel may not
1409 run glibc-based applications correctly.
1411 config HAVE_FUTEX_CMPXCHG
1414 Architectures should select this if futex_atomic_cmpxchg_inatomic()
1415 is implemented and always working. This removes a couple of runtime
1419 bool "Enable eventpoll support" if EXPERT
1423 Disabling this option will cause the kernel to be built without
1424 support for epoll family of system calls.
1427 bool "Enable signalfd() system call" if EXPERT
1431 Enable the signalfd() system call that allows to receive signals
1432 on a file descriptor.
1437 bool "Enable timerfd() system call" if EXPERT
1441 Enable the timerfd() system call that allows to receive timer
1442 events on a file descriptor.
1447 bool "Enable eventfd() system call" if EXPERT
1451 Enable the eventfd() system call that allows to receive both
1452 kernel notification (ie. KAIO) or userspace notifications.
1457 bool "Use full shmem filesystem" if EXPERT
1461 The shmem is an internal filesystem used to manage shared memory.
1462 It is backed by swap and manages resource limits. It is also exported
1463 to userspace as tmpfs if TMPFS is enabled. Disabling this
1464 option replaces shmem and tmpfs with the much simpler ramfs code,
1465 which may be appropriate on small systems without swap.
1468 bool "Enable AIO support" if EXPERT
1471 This option enables POSIX asynchronous I/O which may by used
1472 by some high performance threaded applications. Disabling
1473 this option saves about 7k.
1477 bool "Enable PCI quirk workarounds" if EXPERT
1480 This enables workarounds for various PCI chipset
1481 bugs/quirks. Disable this only if your target machine is
1482 unaffected by PCI quirks.
1485 bool "Embedded system"
1486 option allnoconfig_y
1489 This option should be enabled if compiling the kernel for
1490 an embedded system so certain expert options are available
1493 config HAVE_PERF_EVENTS
1496 See tools/perf/design.txt for details.
1498 config PERF_USE_VMALLOC
1501 See tools/perf/design.txt for details
1503 menu "Kernel Performance Events And Counters"
1506 bool "Kernel performance events and counters"
1507 default y if PROFILING
1508 depends on HAVE_PERF_EVENTS
1512 Enable kernel support for various performance events provided
1513 by software and hardware.
1515 Software events are supported either built-in or via the
1516 use of generic tracepoints.
1518 Most modern CPUs support performance events via performance
1519 counter registers. These registers count the number of certain
1520 types of hw events: such as instructions executed, cachemisses
1521 suffered, or branches mis-predicted - without slowing down the
1522 kernel or applications. These registers can also trigger interrupts
1523 when a threshold number of events have passed - and can thus be
1524 used to profile the code that runs on that CPU.
1526 The Linux Performance Event subsystem provides an abstraction of
1527 these software and hardware event capabilities, available via a
1528 system call and used by the "perf" utility in tools/perf/. It
1529 provides per task and per CPU counters, and it provides event
1530 capabilities on top of those.
1534 config DEBUG_PERF_USE_VMALLOC
1536 bool "Debug: use vmalloc to back perf mmap() buffers"
1537 depends on PERF_EVENTS && DEBUG_KERNEL
1538 select PERF_USE_VMALLOC
1540 Use vmalloc memory to back perf mmap() buffers.
1542 Mostly useful for debugging the vmalloc code on platforms
1543 that don't require it.
1549 config VM_EVENT_COUNTERS
1551 bool "Enable VM event counters for /proc/vmstat" if EXPERT
1553 VM event counters are needed for event counts to be shown.
1554 This option allows the disabling of the VM event counters
1555 on EXPERT systems. /proc/vmstat will only show page counts
1556 if VM event counters are disabled.
1560 bool "Enable SLUB debugging support" if EXPERT
1561 depends on SLUB && SYSFS
1563 SLUB has extensive debug support features. Disabling these can
1564 result in significant savings in code size. This also disables
1565 SLUB sysfs support. /sys/slab will not exist and there will be
1566 no support for cache validation etc.
1569 bool "Disable heap randomization"
1572 Randomizing heap placement makes heap exploits harder, but it
1573 also breaks ancient binaries (including anything libc5 based).
1574 This option changes the bootup default to heap randomization
1575 disabled, and can be overridden at runtime by setting
1576 /proc/sys/kernel/randomize_va_space to 2.
1578 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1581 prompt "Choose SLAB allocator"
1584 This option allows to select a slab allocator.
1589 The regular slab allocator that is established and known to work
1590 well in all environments. It organizes cache hot objects in
1591 per cpu and per node queues.
1594 bool "SLUB (Unqueued Allocator)"
1596 SLUB is a slab allocator that minimizes cache line usage
1597 instead of managing queues of cached objects (SLAB approach).
1598 Per cpu caching is realized using slabs of objects instead
1599 of queues of objects. SLUB can use memory efficiently
1600 and has enhanced diagnostics. SLUB is the default choice for
1605 bool "SLOB (Simple Allocator)"
1607 SLOB replaces the stock allocator with a drastically simpler
1608 allocator. SLOB is generally more space efficient but
1609 does not perform as well on large systems.
1613 config SLUB_CPU_PARTIAL
1615 depends on SLUB && SMP
1616 bool "SLUB per cpu partial cache"
1618 Per cpu partial caches accellerate objects allocation and freeing
1619 that is local to a processor at the price of more indeterminism
1620 in the latency of the free. On overflow these caches will be cleared
1621 which requires the taking of locks that may cause latency spikes.
1622 Typically one would choose no for a realtime system.
1624 config MMAP_ALLOW_UNINITIALIZED
1625 bool "Allow mmapped anonymous memory to be uninitialized"
1626 depends on EXPERT && !MMU
1629 Normally, and according to the Linux spec, anonymous memory obtained
1630 from mmap() has it's contents cleared before it is passed to
1631 userspace. Enabling this config option allows you to request that
1632 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1633 providing a huge performance boost. If this option is not enabled,
1634 then the flag will be ignored.
1636 This is taken advantage of by uClibc's malloc(), and also by
1637 ELF-FDPIC binfmt's brk and stack allocator.
1639 Because of the obvious security issues, this option should only be
1640 enabled on embedded devices where you control what is run in
1641 userspace. Since that isn't generally a problem on no-MMU systems,
1642 it is normally safe to say Y here.
1644 See Documentation/nommu-mmap.txt for more information.
1647 bool "Profiling support"
1649 Say Y here to enable the extended profiling support mechanisms used
1650 by profilers such as OProfile.
1653 # Place an empty function call at each tracepoint site. Can be
1654 # dynamically changed for a probe function.
1659 source "arch/Kconfig"
1661 endmenu # General setup
1663 config HAVE_GENERIC_DMA_COHERENT
1670 depends on SLAB || SLUB_DEBUG
1678 default 0 if BASE_FULL
1679 default 1 if !BASE_FULL
1681 config SYSTEM_TRUSTED_KEYRING
1682 bool "Provide system-wide ring of trusted keys"
1685 Provide a system keyring to which trusted keys can be added. Keys in
1686 the keyring are considered to be trusted. Keys may be added at will
1687 by the kernel from compiled-in data and from hardware key stores, but
1688 userspace may only add extra keys if those keys can be verified by
1689 keys already in the keyring.
1691 Keys in this keyring are used by module signature checking.
1694 bool "Enable loadable module support"
1697 Kernel modules are small pieces of compiled code which can
1698 be inserted in the running kernel, rather than being
1699 permanently built into the kernel. You use the "modprobe"
1700 tool to add (and sometimes remove) them. If you say Y here,
1701 many parts of the kernel can be built as modules (by
1702 answering M instead of Y where indicated): this is most
1703 useful for infrequently used options which are not required
1704 for booting. For more information, see the man pages for
1705 modprobe, lsmod, modinfo, insmod and rmmod.
1707 If you say Y here, you will need to run "make
1708 modules_install" to put the modules under /lib/modules/
1709 where modprobe can find them (you may need to be root to do
1716 config MODULE_FORCE_LOAD
1717 bool "Forced module loading"
1720 Allow loading of modules without version information (ie. modprobe
1721 --force). Forced module loading sets the 'F' (forced) taint flag and
1722 is usually a really bad idea.
1724 config MODULE_UNLOAD
1725 bool "Module unloading"
1727 Without this option you will not be able to unload any
1728 modules (note that some modules may not be unloadable
1729 anyway), which makes your kernel smaller, faster
1730 and simpler. If unsure, say Y.
1732 config MODULE_FORCE_UNLOAD
1733 bool "Forced module unloading"
1734 depends on MODULE_UNLOAD
1736 This option allows you to force a module to unload, even if the
1737 kernel believes it is unsafe: the kernel will remove the module
1738 without waiting for anyone to stop using it (using the -f option to
1739 rmmod). This is mainly for kernel developers and desperate users.
1743 bool "Module versioning support"
1745 Usually, you have to use modules compiled with your kernel.
1746 Saying Y here makes it sometimes possible to use modules
1747 compiled for different kernels, by adding enough information
1748 to the modules to (hopefully) spot any changes which would
1749 make them incompatible with the kernel you are running. If
1752 config MODULE_SRCVERSION_ALL
1753 bool "Source checksum for all modules"
1755 Modules which contain a MODULE_VERSION get an extra "srcversion"
1756 field inserted into their modinfo section, which contains a
1757 sum of the source files which made it. This helps maintainers
1758 see exactly which source was used to build a module (since
1759 others sometimes change the module source without updating
1760 the version). With this option, such a "srcversion" field
1761 will be created for all modules. If unsure, say N.
1764 bool "Module signature verification"
1766 select SYSTEM_TRUSTED_KEYRING
1769 select ASYMMETRIC_KEY_TYPE
1770 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1771 select PUBLIC_KEY_ALGO_RSA
1774 select X509_CERTIFICATE_PARSER
1776 Check modules for valid signatures upon load: the signature
1777 is simply appended to the module. For more information see
1778 Documentation/module-signing.txt.
1780 !!!WARNING!!! If you enable this option, you MUST make sure that the
1781 module DOES NOT get stripped after being signed. This includes the
1782 debuginfo strip done by some packagers (such as rpmbuild) and
1783 inclusion into an initramfs that wants the module size reduced.
1785 config MODULE_SIG_FORCE
1786 bool "Require modules to be validly signed"
1787 depends on MODULE_SIG
1789 Reject unsigned modules or signed modules for which we don't have a
1790 key. Without this, such modules will simply taint the kernel.
1792 config MODULE_SIG_ALL
1793 bool "Automatically sign all modules"
1795 depends on MODULE_SIG
1797 Sign all modules during make modules_install. Without this option,
1798 modules must be signed manually, using the scripts/sign-file tool.
1800 comment "Do not forget to sign required modules with scripts/sign-file"
1801 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
1804 prompt "Which hash algorithm should modules be signed with?"
1805 depends on MODULE_SIG
1807 This determines which sort of hashing algorithm will be used during
1808 signature generation. This algorithm _must_ be built into the kernel
1809 directly so that signature verification can take place. It is not
1810 possible to load a signed module containing the algorithm to check
1811 the signature on that module.
1813 config MODULE_SIG_SHA1
1814 bool "Sign modules with SHA-1"
1817 config MODULE_SIG_SHA224
1818 bool "Sign modules with SHA-224"
1819 select CRYPTO_SHA256
1821 config MODULE_SIG_SHA256
1822 bool "Sign modules with SHA-256"
1823 select CRYPTO_SHA256
1825 config MODULE_SIG_SHA384
1826 bool "Sign modules with SHA-384"
1827 select CRYPTO_SHA512
1829 config MODULE_SIG_SHA512
1830 bool "Sign modules with SHA-512"
1831 select CRYPTO_SHA512
1835 config MODULE_SIG_HASH
1837 depends on MODULE_SIG
1838 default "sha1" if MODULE_SIG_SHA1
1839 default "sha224" if MODULE_SIG_SHA224
1840 default "sha256" if MODULE_SIG_SHA256
1841 default "sha384" if MODULE_SIG_SHA384
1842 default "sha512" if MODULE_SIG_SHA512
1846 config INIT_ALL_POSSIBLE
1849 Back when each arch used to define their own cpu_online_mask and
1850 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
1851 with all 1s, and others with all 0s. When they were centralised,
1852 it was better to provide this option than to break all the archs
1853 and have several arch maintainers pursuing me down dark alleys.
1858 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1860 Need stop_machine() primitive.
1862 source "block/Kconfig"
1864 config PREEMPT_NOTIFIERS
1871 # Can be selected by architectures with broken toolchains
1872 # that get confused by correct const<->read_only section
1874 config BROKEN_RODATA
1880 Build a simple ASN.1 grammar compiler that produces a bytecode output
1881 that can be interpreted by the ASN.1 stream decoder and used to
1882 inform it as to what tags are to be expected in a stream and what
1883 functions to call on what tags.
1885 source "kernel/Kconfig.locks"
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