5 default "/lib/modules/$(shell,uname -r)/.config"
6 default "/etc/kernel-config"
7 default "/boot/config-$(shell,uname -r)"
9 default "arch/$(ARCH)/defconfig"
12 def_bool $(success,$(CC) --version | head -n 1 | grep -q gcc)
16 default $(shell,$(srctree)/scripts/gcc-version.sh -p $(CC) | sed 's/^0*//') if CC_IS_GCC
20 def_bool $(success,$(CC) --version | head -n 1 | grep -q clang)
24 default $(shell,$(srctree)/scripts/clang-version.sh $(CC))
26 config CC_HAS_ASM_GOTO
27 def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC))
36 config BUILDTIME_EXTABLE_SORT
39 config THREAD_INFO_IN_TASK
42 Select this to move thread_info off the stack into task_struct. To
43 make this work, an arch will need to remove all thread_info fields
44 except flags and fix any runtime bugs.
46 One subtle change that will be needed is to use try_get_task_stack()
47 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
56 depends on BROKEN || !SMP
59 config INIT_ENV_ARG_LIMIT
64 Maximum of each of the number of arguments and environment
65 variables passed to init from the kernel command line.
68 bool "Compile also drivers which will not load"
72 Some drivers can be compiled on a different platform than they are
73 intended to be run on. Despite they cannot be loaded there (or even
74 when they load they cannot be used due to missing HW support),
75 developers still, opposing to distributors, might want to build such
76 drivers to compile-test them.
78 If you are a developer and want to build everything available, say Y
79 here. If you are a user/distributor, say N here to exclude useless
80 drivers to be distributed.
83 string "Local version - append to kernel release"
85 Append an extra string to the end of your kernel version.
86 This will show up when you type uname, for example.
87 The string you set here will be appended after the contents of
88 any files with a filename matching localversion* in your
89 object and source tree, in that order. Your total string can
90 be a maximum of 64 characters.
92 config LOCALVERSION_AUTO
93 bool "Automatically append version information to the version string"
95 depends on !COMPILE_TEST
97 This will try to automatically determine if the current tree is a
98 release tree by looking for git tags that belong to the current
101 A string of the format -gxxxxxxxx will be added to the localversion
102 if a git-based tree is found. The string generated by this will be
103 appended after any matching localversion* files, and after the value
104 set in CONFIG_LOCALVERSION.
106 (The actual string used here is the first eight characters produced
107 by running the command:
109 $ git rev-parse --verify HEAD
111 which is done within the script "scripts/setlocalversion".)
114 string "Build ID Salt"
117 The build ID is used to link binaries and their debug info. Setting
118 this option will use the value in the calculation of the build id.
119 This is mostly useful for distributions which want to ensure the
120 build is unique between builds. It's safe to leave the default.
122 config HAVE_KERNEL_GZIP
125 config HAVE_KERNEL_BZIP2
128 config HAVE_KERNEL_LZMA
131 config HAVE_KERNEL_XZ
134 config HAVE_KERNEL_LZO
137 config HAVE_KERNEL_LZ4
140 config HAVE_KERNEL_UNCOMPRESSED
144 prompt "Kernel compression mode"
146 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 || HAVE_KERNEL_UNCOMPRESSED
148 The linux kernel is a kind of self-extracting executable.
149 Several compression algorithms are available, which differ
150 in efficiency, compression and decompression speed.
151 Compression speed is only relevant when building a kernel.
152 Decompression speed is relevant at each boot.
154 If you have any problems with bzip2 or lzma compressed
155 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
156 version of this functionality (bzip2 only), for 2.4, was
157 supplied by Christian Ludwig)
159 High compression options are mostly useful for users, who
160 are low on disk space (embedded systems), but for whom ram
163 If in doubt, select 'gzip'
167 depends on HAVE_KERNEL_GZIP
169 The old and tried gzip compression. It provides a good balance
170 between compression ratio and decompression speed.
174 depends on HAVE_KERNEL_BZIP2
176 Its compression ratio and speed is intermediate.
177 Decompression speed is slowest among the choices. The kernel
178 size is about 10% smaller with bzip2, in comparison to gzip.
179 Bzip2 uses a large amount of memory. For modern kernels you
180 will need at least 8MB RAM or more for booting.
184 depends on HAVE_KERNEL_LZMA
186 This compression algorithm's ratio is best. Decompression speed
187 is between gzip and bzip2. Compression is slowest.
188 The kernel size is about 33% smaller with LZMA in comparison to gzip.
192 depends on HAVE_KERNEL_XZ
194 XZ uses the LZMA2 algorithm and instruction set specific
195 BCJ filters which can improve compression ratio of executable
196 code. The size of the kernel is about 30% smaller with XZ in
197 comparison to gzip. On architectures for which there is a BCJ
198 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
199 will create a few percent smaller kernel than plain LZMA.
201 The speed is about the same as with LZMA: The decompression
202 speed of XZ is better than that of bzip2 but worse than gzip
203 and LZO. Compression is slow.
207 depends on HAVE_KERNEL_LZO
209 Its compression ratio is the poorest among the choices. The kernel
210 size is about 10% bigger than gzip; however its speed
211 (both compression and decompression) is the fastest.
215 depends on HAVE_KERNEL_LZ4
217 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
218 A preliminary version of LZ4 de/compression tool is available at
219 <https://code.google.com/p/lz4/>.
221 Its compression ratio is worse than LZO. The size of the kernel
222 is about 8% bigger than LZO. But the decompression speed is
225 config KERNEL_UNCOMPRESSED
227 depends on HAVE_KERNEL_UNCOMPRESSED
229 Produce uncompressed kernel image. This option is usually not what
230 you want. It is useful for debugging the kernel in slow simulation
231 environments, where decompressing and moving the kernel is awfully
232 slow. This option allows early boot code to skip the decompressor
233 and jump right at uncompressed kernel image.
237 config DEFAULT_HOSTNAME
238 string "Default hostname"
241 This option determines the default system hostname before userspace
242 calls sethostname(2). The kernel traditionally uses "(none)" here,
243 but you may wish to use a different default here to make a minimal
244 system more usable with less configuration.
247 # For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can
248 # add proper SWAP support to them, in which case this can be remove.
254 bool "Support for paging of anonymous memory (swap)"
255 depends on MMU && BLOCK && !ARCH_NO_SWAP
258 This option allows you to choose whether you want to have support
259 for so called swap devices or swap files in your kernel that are
260 used to provide more virtual memory than the actual RAM present
261 in your computer. If unsure say Y.
266 Inter Process Communication is a suite of library functions and
267 system calls which let processes (running programs) synchronize and
268 exchange information. It is generally considered to be a good thing,
269 and some programs won't run unless you say Y here. In particular, if
270 you want to run the DOS emulator dosemu under Linux (read the
271 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
272 you'll need to say Y here.
274 You can find documentation about IPC with "info ipc" and also in
275 section 6.4 of the Linux Programmer's Guide, available from
276 <http://www.tldp.org/guides.html>.
278 config SYSVIPC_SYSCTL
285 bool "POSIX Message Queues"
288 POSIX variant of message queues is a part of IPC. In POSIX message
289 queues every message has a priority which decides about succession
290 of receiving it by a process. If you want to compile and run
291 programs written e.g. for Solaris with use of its POSIX message
292 queues (functions mq_*) say Y here.
294 POSIX message queues are visible as a filesystem called 'mqueue'
295 and can be mounted somewhere if you want to do filesystem
296 operations on message queues.
300 config POSIX_MQUEUE_SYSCTL
302 depends on POSIX_MQUEUE
306 config CROSS_MEMORY_ATTACH
307 bool "Enable process_vm_readv/writev syscalls"
311 Enabling this option adds the system calls process_vm_readv and
312 process_vm_writev which allow a process with the correct privileges
313 to directly read from or write to another process' address space.
314 See the man page for more details.
317 bool "uselib syscall"
318 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
320 This option enables the uselib syscall, a system call used in the
321 dynamic linker from libc5 and earlier. glibc does not use this
322 system call. If you intend to run programs built on libc5 or
323 earlier, you may need to enable this syscall. Current systems
324 running glibc can safely disable this.
327 bool "Auditing support"
330 Enable auditing infrastructure that can be used with another
331 kernel subsystem, such as SELinux (which requires this for
332 logging of avc messages output). System call auditing is included
333 on architectures which support it.
335 config HAVE_ARCH_AUDITSYSCALL
340 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
343 source "kernel/irq/Kconfig"
344 source "kernel/time/Kconfig"
345 source "kernel/Kconfig.preempt"
347 menu "CPU/Task time and stats accounting"
349 config VIRT_CPU_ACCOUNTING
353 prompt "Cputime accounting"
354 default TICK_CPU_ACCOUNTING if !PPC64
355 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
357 # Kind of a stub config for the pure tick based cputime accounting
358 config TICK_CPU_ACCOUNTING
359 bool "Simple tick based cputime accounting"
360 depends on !S390 && !NO_HZ_FULL
362 This is the basic tick based cputime accounting that maintains
363 statistics about user, system and idle time spent on per jiffies
368 config VIRT_CPU_ACCOUNTING_NATIVE
369 bool "Deterministic task and CPU time accounting"
370 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
371 select VIRT_CPU_ACCOUNTING
373 Select this option to enable more accurate task and CPU time
374 accounting. This is done by reading a CPU counter on each
375 kernel entry and exit and on transitions within the kernel
376 between system, softirq and hardirq state, so there is a
377 small performance impact. In the case of s390 or IBM POWER > 5,
378 this also enables accounting of stolen time on logically-partitioned
381 config VIRT_CPU_ACCOUNTING_GEN
382 bool "Full dynticks CPU time accounting"
383 depends on HAVE_CONTEXT_TRACKING
384 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
385 select VIRT_CPU_ACCOUNTING
386 select CONTEXT_TRACKING
388 Select this option to enable task and CPU time accounting on full
389 dynticks systems. This accounting is implemented by watching every
390 kernel-user boundaries using the context tracking subsystem.
391 The accounting is thus performed at the expense of some significant
394 For now this is only useful if you are working on the full
395 dynticks subsystem development.
401 config IRQ_TIME_ACCOUNTING
402 bool "Fine granularity task level IRQ time accounting"
403 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
405 Select this option to enable fine granularity task irq time
406 accounting. This is done by reading a timestamp on each
407 transitions between softirq and hardirq state, so there can be a
408 small performance impact.
410 If in doubt, say N here.
412 config HAVE_SCHED_AVG_IRQ
414 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
417 config BSD_PROCESS_ACCT
418 bool "BSD Process Accounting"
421 If you say Y here, a user level program will be able to instruct the
422 kernel (via a special system call) to write process accounting
423 information to a file: whenever a process exits, information about
424 that process will be appended to the file by the kernel. The
425 information includes things such as creation time, owning user,
426 command name, memory usage, controlling terminal etc. (the complete
427 list is in the struct acct in <file:include/linux/acct.h>). It is
428 up to the user level program to do useful things with this
429 information. This is generally a good idea, so say Y.
431 config BSD_PROCESS_ACCT_V3
432 bool "BSD Process Accounting version 3 file format"
433 depends on BSD_PROCESS_ACCT
436 If you say Y here, the process accounting information is written
437 in a new file format that also logs the process IDs of each
438 process and its parent. Note that this file format is incompatible
439 with previous v0/v1/v2 file formats, so you will need updated tools
440 for processing it. A preliminary version of these tools is available
441 at <http://www.gnu.org/software/acct/>.
444 bool "Export task/process statistics through netlink"
449 Export selected statistics for tasks/processes through the
450 generic netlink interface. Unlike BSD process accounting, the
451 statistics are available during the lifetime of tasks/processes as
452 responses to commands. Like BSD accounting, they are sent to user
457 config TASK_DELAY_ACCT
458 bool "Enable per-task delay accounting"
462 Collect information on time spent by a task waiting for system
463 resources like cpu, synchronous block I/O completion and swapping
464 in pages. Such statistics can help in setting a task's priorities
465 relative to other tasks for cpu, io, rss limits etc.
470 bool "Enable extended accounting over taskstats"
473 Collect extended task accounting data and send the data
474 to userland for processing over the taskstats interface.
478 config TASK_IO_ACCOUNTING
479 bool "Enable per-task storage I/O accounting"
480 depends on TASK_XACCT
482 Collect information on the number of bytes of storage I/O which this
488 bool "Pressure stall information tracking"
490 Collect metrics that indicate how overcommitted the CPU, memory,
491 and IO capacity are in the system.
493 If you say Y here, the kernel will create /proc/pressure/ with the
494 pressure statistics files cpu, memory, and io. These will indicate
495 the share of walltime in which some or all tasks in the system are
496 delayed due to contention of the respective resource.
498 In kernels with cgroup support, cgroups (cgroup2 only) will
499 have cpu.pressure, memory.pressure, and io.pressure files,
500 which aggregate pressure stalls for the grouped tasks only.
502 For more details see Documentation/accounting/psi.txt.
506 config PSI_DEFAULT_DISABLED
507 bool "Require boot parameter to enable pressure stall information tracking"
511 If set, pressure stall information tracking will be disabled
512 per default but can be enabled through passing psi=1 on the
513 kernel commandline during boot.
515 endmenu # "CPU/Task time and stats accounting"
519 depends on SMP || COMPILE_TEST
522 Make sure that CPUs running critical tasks are not disturbed by
523 any source of "noise" such as unbound workqueues, timers, kthreads...
524 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
525 the "isolcpus=" boot parameter.
529 source "kernel/rcu/Kconfig"
536 tristate "Kernel .config support"
539 This option enables the complete Linux kernel ".config" file
540 contents to be saved in the kernel. It provides documentation
541 of which kernel options are used in a running kernel or in an
542 on-disk kernel. This information can be extracted from the kernel
543 image file with the script scripts/extract-ikconfig and used as
544 input to rebuild the current kernel or to build another kernel.
545 It can also be extracted from a running kernel by reading
546 /proc/config.gz if enabled (below).
549 bool "Enable access to .config through /proc/config.gz"
550 depends on IKCONFIG && PROC_FS
552 This option enables access to the kernel configuration file
553 through /proc/config.gz.
556 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
561 Select the minimal kernel log buffer size as a power of 2.
562 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
563 parameter, see below. Any higher size also might be forced
564 by "log_buf_len" boot parameter.
574 config LOG_CPU_MAX_BUF_SHIFT
575 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
578 default 12 if !BASE_SMALL
579 default 0 if BASE_SMALL
582 This option allows to increase the default ring buffer size
583 according to the number of CPUs. The value defines the contribution
584 of each CPU as a power of 2. The used space is typically only few
585 lines however it might be much more when problems are reported,
588 The increased size means that a new buffer has to be allocated and
589 the original static one is unused. It makes sense only on systems
590 with more CPUs. Therefore this value is used only when the sum of
591 contributions is greater than the half of the default kernel ring
592 buffer as defined by LOG_BUF_SHIFT. The default values are set
593 so that more than 64 CPUs are needed to trigger the allocation.
595 Also this option is ignored when "log_buf_len" kernel parameter is
596 used as it forces an exact (power of two) size of the ring buffer.
598 The number of possible CPUs is used for this computation ignoring
599 hotplugging making the computation optimal for the worst case
600 scenario while allowing a simple algorithm to be used from bootup.
602 Examples shift values and their meaning:
603 17 => 128 KB for each CPU
604 16 => 64 KB for each CPU
605 15 => 32 KB for each CPU
606 14 => 16 KB for each CPU
607 13 => 8 KB for each CPU
608 12 => 4 KB for each CPU
610 config PRINTK_SAFE_LOG_BUF_SHIFT
611 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
616 Select the size of an alternate printk per-CPU buffer where messages
617 printed from usafe contexts are temporary stored. One example would
618 be NMI messages, another one - printk recursion. The messages are
619 copied to the main log buffer in a safe context to avoid a deadlock.
620 The value defines the size as a power of 2.
622 Those messages are rare and limited. The largest one is when
623 a backtrace is printed. It usually fits into 4KB. Select
624 8KB if you want to be on the safe side.
627 17 => 128 KB for each CPU
628 16 => 64 KB for each CPU
629 15 => 32 KB for each CPU
630 14 => 16 KB for each CPU
631 13 => 8 KB for each CPU
632 12 => 4 KB for each CPU
635 # Architectures with an unreliable sched_clock() should select this:
637 config HAVE_UNSTABLE_SCHED_CLOCK
640 config GENERIC_SCHED_CLOCK
644 # For architectures that want to enable the support for NUMA-affine scheduler
647 config ARCH_SUPPORTS_NUMA_BALANCING
651 # For architectures that prefer to flush all TLBs after a number of pages
652 # are unmapped instead of sending one IPI per page to flush. The architecture
653 # must provide guarantees on what happens if a clean TLB cache entry is
654 # written after the unmap. Details are in mm/rmap.c near the check for
655 # should_defer_flush. The architecture should also consider if the full flush
656 # and the refill costs are offset by the savings of sending fewer IPIs.
657 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
661 # For architectures that know their GCC __int128 support is sound
663 config ARCH_SUPPORTS_INT128
666 # For architectures that (ab)use NUMA to represent different memory regions
667 # all cpu-local but of different latencies, such as SuperH.
669 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
672 config NUMA_BALANCING
673 bool "Memory placement aware NUMA scheduler"
674 depends on ARCH_SUPPORTS_NUMA_BALANCING
675 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
676 depends on SMP && NUMA && MIGRATION
678 This option adds support for automatic NUMA aware memory/task placement.
679 The mechanism is quite primitive and is based on migrating memory when
680 it has references to the node the task is running on.
682 This system will be inactive on UMA systems.
684 config NUMA_BALANCING_DEFAULT_ENABLED
685 bool "Automatically enable NUMA aware memory/task placement"
687 depends on NUMA_BALANCING
689 If set, automatic NUMA balancing will be enabled if running on a NUMA
693 bool "Control Group support"
696 This option adds support for grouping sets of processes together, for
697 use with process control subsystems such as Cpusets, CFS, memory
698 controls or device isolation.
700 - Documentation/scheduler/sched-design-CFS.txt (CFS)
701 - Documentation/cgroup-v1/ (features for grouping, isolation
702 and resource control)
712 bool "Memory controller"
716 Provides control over the memory footprint of tasks in a cgroup.
719 bool "Swap controller"
720 depends on MEMCG && SWAP
722 Provides control over the swap space consumed by tasks in a cgroup.
724 config MEMCG_SWAP_ENABLED
725 bool "Swap controller enabled by default"
726 depends on MEMCG_SWAP
729 Memory Resource Controller Swap Extension comes with its price in
730 a bigger memory consumption. General purpose distribution kernels
731 which want to enable the feature but keep it disabled by default
732 and let the user enable it by swapaccount=1 boot command line
733 parameter should have this option unselected.
734 For those who want to have the feature enabled by default should
735 select this option (if, for some reason, they need to disable it
736 then swapaccount=0 does the trick).
740 depends on MEMCG && !SLOB
748 Generic block IO controller cgroup interface. This is the common
749 cgroup interface which should be used by various IO controlling
752 Currently, CFQ IO scheduler uses it to recognize task groups and
753 control disk bandwidth allocation (proportional time slice allocation)
754 to such task groups. It is also used by bio throttling logic in
755 block layer to implement upper limit in IO rates on a device.
757 This option only enables generic Block IO controller infrastructure.
758 One needs to also enable actual IO controlling logic/policy. For
759 enabling proportional weight division of disk bandwidth in CFQ, set
760 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
761 CONFIG_BLK_DEV_THROTTLING=y.
763 See Documentation/cgroup-v1/blkio-controller.txt for more information.
765 config DEBUG_BLK_CGROUP
766 bool "IO controller debugging"
767 depends on BLK_CGROUP
770 Enable some debugging help. Currently it exports additional stat
771 files in a cgroup which can be useful for debugging.
773 config CGROUP_WRITEBACK
775 depends on MEMCG && BLK_CGROUP
778 menuconfig CGROUP_SCHED
779 bool "CPU controller"
782 This feature lets CPU scheduler recognize task groups and control CPU
783 bandwidth allocation to such task groups. It uses cgroups to group
787 config FAIR_GROUP_SCHED
788 bool "Group scheduling for SCHED_OTHER"
789 depends on CGROUP_SCHED
793 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
794 depends on FAIR_GROUP_SCHED
797 This option allows users to define CPU bandwidth rates (limits) for
798 tasks running within the fair group scheduler. Groups with no limit
799 set are considered to be unconstrained and will run with no
801 See Documentation/scheduler/sched-bwc.txt for more information.
803 config RT_GROUP_SCHED
804 bool "Group scheduling for SCHED_RR/FIFO"
805 depends on CGROUP_SCHED
808 This feature lets you explicitly allocate real CPU bandwidth
809 to task groups. If enabled, it will also make it impossible to
810 schedule realtime tasks for non-root users until you allocate
811 realtime bandwidth for them.
812 See Documentation/scheduler/sched-rt-group.txt for more information.
817 bool "PIDs controller"
819 Provides enforcement of process number limits in the scope of a
820 cgroup. Any attempt to fork more processes than is allowed in the
821 cgroup will fail. PIDs are fundamentally a global resource because it
822 is fairly trivial to reach PID exhaustion before you reach even a
823 conservative kmemcg limit. As a result, it is possible to grind a
824 system to halt without being limited by other cgroup policies. The
825 PIDs controller is designed to stop this from happening.
827 It should be noted that organisational operations (such as attaching
828 to a cgroup hierarchy will *not* be blocked by the PIDs controller),
829 since the PIDs limit only affects a process's ability to fork, not to
833 bool "RDMA controller"
835 Provides enforcement of RDMA resources defined by IB stack.
836 It is fairly easy for consumers to exhaust RDMA resources, which
837 can result into resource unavailability to other consumers.
838 RDMA controller is designed to stop this from happening.
839 Attaching processes with active RDMA resources to the cgroup
840 hierarchy is allowed even if can cross the hierarchy's limit.
842 config CGROUP_FREEZER
843 bool "Freezer controller"
845 Provides a way to freeze and unfreeze all tasks in a
848 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
849 controller includes important in-kernel memory consumers per default.
851 If you're using cgroup2, say N.
853 config CGROUP_HUGETLB
854 bool "HugeTLB controller"
855 depends on HUGETLB_PAGE
859 Provides a cgroup controller for HugeTLB pages.
860 When you enable this, you can put a per cgroup limit on HugeTLB usage.
861 The limit is enforced during page fault. Since HugeTLB doesn't
862 support page reclaim, enforcing the limit at page fault time implies
863 that, the application will get SIGBUS signal if it tries to access
864 HugeTLB pages beyond its limit. This requires the application to know
865 beforehand how much HugeTLB pages it would require for its use. The
866 control group is tracked in the third page lru pointer. This means
867 that we cannot use the controller with huge page less than 3 pages.
870 bool "Cpuset controller"
873 This option will let you create and manage CPUSETs which
874 allow dynamically partitioning a system into sets of CPUs and
875 Memory Nodes and assigning tasks to run only within those sets.
876 This is primarily useful on large SMP or NUMA systems.
880 config PROC_PID_CPUSET
881 bool "Include legacy /proc/<pid>/cpuset file"
886 bool "Device controller"
888 Provides a cgroup controller implementing whitelists for
889 devices which a process in the cgroup can mknod or open.
891 config CGROUP_CPUACCT
892 bool "Simple CPU accounting controller"
894 Provides a simple controller for monitoring the
895 total CPU consumed by the tasks in a cgroup.
898 bool "Perf controller"
899 depends on PERF_EVENTS
901 This option extends the perf per-cpu mode to restrict monitoring
902 to threads which belong to the cgroup specified and run on the
908 bool "Support for eBPF programs attached to cgroups"
909 depends on BPF_SYSCALL
910 select SOCK_CGROUP_DATA
912 Allow attaching eBPF programs to a cgroup using the bpf(2)
913 syscall command BPF_PROG_ATTACH.
915 In which context these programs are accessed depends on the type
916 of attachment. For instance, programs that are attached using
917 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
921 bool "Debug controller"
923 depends on DEBUG_KERNEL
925 This option enables a simple controller that exports
926 debugging information about the cgroups framework. This
927 controller is for control cgroup debugging only. Its
928 interfaces are not stable.
932 config SOCK_CGROUP_DATA
938 menuconfig NAMESPACES
939 bool "Namespaces support" if EXPERT
943 Provides the way to make tasks work with different objects using
944 the same id. For example same IPC id may refer to different objects
945 or same user id or pid may refer to different tasks when used in
946 different namespaces.
954 In this namespace tasks see different info provided with the
959 depends on (SYSVIPC || POSIX_MQUEUE)
962 In this namespace tasks work with IPC ids which correspond to
963 different IPC objects in different namespaces.
966 bool "User namespace"
969 This allows containers, i.e. vservers, to use user namespaces
970 to provide different user info for different servers.
972 When user namespaces are enabled in the kernel it is
973 recommended that the MEMCG option also be enabled and that
974 user-space use the memory control groups to limit the amount
975 of memory a memory unprivileged users can use.
980 bool "PID Namespaces"
983 Support process id namespaces. This allows having multiple
984 processes with the same pid as long as they are in different
985 pid namespaces. This is a building block of containers.
988 bool "Network namespace"
992 Allow user space to create what appear to be multiple instances
993 of the network stack.
997 config CHECKPOINT_RESTORE
998 bool "Checkpoint/restore support"
1002 Enables additional kernel features in a sake of checkpoint/restore.
1003 In particular it adds auxiliary prctl codes to setup process text,
1004 data and heap segment sizes, and a few additional /proc filesystem
1007 If unsure, say N here.
1009 config SCHED_AUTOGROUP
1010 bool "Automatic process group scheduling"
1013 select FAIR_GROUP_SCHED
1015 This option optimizes the scheduler for common desktop workloads by
1016 automatically creating and populating task groups. This separation
1017 of workloads isolates aggressive CPU burners (like build jobs) from
1018 desktop applications. Task group autogeneration is currently based
1021 config SYSFS_DEPRECATED
1022 bool "Enable deprecated sysfs features to support old userspace tools"
1026 This option adds code that switches the layout of the "block" class
1027 devices, to not show up in /sys/class/block/, but only in
1030 This switch is only active when the sysfs.deprecated=1 boot option is
1031 passed or the SYSFS_DEPRECATED_V2 option is set.
1033 This option allows new kernels to run on old distributions and tools,
1034 which might get confused by /sys/class/block/. Since 2007/2008 all
1035 major distributions and tools handle this just fine.
1037 Recent distributions and userspace tools after 2009/2010 depend on
1038 the existence of /sys/class/block/, and will not work with this
1041 Only if you are using a new kernel on an old distribution, you might
1044 config SYSFS_DEPRECATED_V2
1045 bool "Enable deprecated sysfs features by default"
1048 depends on SYSFS_DEPRECATED
1050 Enable deprecated sysfs by default.
1052 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1055 Only if you are using a new kernel on an old distribution, you might
1056 need to say Y here. Even then, odds are you would not need it
1057 enabled, you can always pass the boot option if absolutely necessary.
1060 bool "Kernel->user space relay support (formerly relayfs)"
1063 This option enables support for relay interface support in
1064 certain file systems (such as debugfs).
1065 It is designed to provide an efficient mechanism for tools and
1066 facilities to relay large amounts of data from kernel space to
1071 config BLK_DEV_INITRD
1072 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1074 The initial RAM filesystem is a ramfs which is loaded by the
1075 boot loader (loadlin or lilo) and that is mounted as root
1076 before the normal boot procedure. It is typically used to
1077 load modules needed to mount the "real" root file system,
1078 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1080 If RAM disk support (BLK_DEV_RAM) is also included, this
1081 also enables initial RAM disk (initrd) support and adds
1082 15 Kbytes (more on some other architectures) to the kernel size.
1088 source "usr/Kconfig"
1093 prompt "Compiler optimization level"
1094 default CC_OPTIMIZE_FOR_PERFORMANCE
1096 config CC_OPTIMIZE_FOR_PERFORMANCE
1097 bool "Optimize for performance"
1099 This is the default optimization level for the kernel, building
1100 with the "-O2" compiler flag for best performance and most
1101 helpful compile-time warnings.
1103 config CC_OPTIMIZE_FOR_SIZE
1104 bool "Optimize for size"
1106 Enabling this option will pass "-Os" instead of "-O2" to
1107 your compiler resulting in a smaller kernel.
1113 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1116 This requires that the arch annotates or otherwise protects
1117 its external entry points from being discarded. Linker scripts
1118 must also merge .text.*, .data.*, and .bss.* correctly into
1119 output sections. Care must be taken not to pull in unrelated
1120 sections (e.g., '.text.init'). Typically '.' in section names
1121 is used to distinguish them from label names / C identifiers.
1123 config LD_DEAD_CODE_DATA_ELIMINATION
1124 bool "Dead code and data elimination (EXPERIMENTAL)"
1125 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1127 depends on !(FUNCTION_TRACER && CC_IS_GCC && GCC_VERSION < 40800)
1128 depends on $(cc-option,-ffunction-sections -fdata-sections)
1129 depends on $(ld-option,--gc-sections)
1131 Enable this if you want to do dead code and data elimination with
1132 the linker by compiling with -ffunction-sections -fdata-sections,
1133 and linking with --gc-sections.
1135 This can reduce on disk and in-memory size of the kernel
1136 code and static data, particularly for small configs and
1137 on small systems. This has the possibility of introducing
1138 silently broken kernel if the required annotations are not
1139 present. This option is not well tested yet, so use at your
1151 config SYSCTL_EXCEPTION_TRACE
1154 Enable support for /proc/sys/debug/exception-trace.
1156 config SYSCTL_ARCH_UNALIGN_NO_WARN
1159 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1160 Allows arch to define/use @no_unaligned_warning to possibly warn
1161 about unaligned access emulation going on under the hood.
1163 config SYSCTL_ARCH_UNALIGN_ALLOW
1166 Enable support for /proc/sys/kernel/unaligned-trap
1167 Allows arches to define/use @unaligned_enabled to runtime toggle
1168 the unaligned access emulation.
1169 see arch/parisc/kernel/unaligned.c for reference
1171 config HAVE_PCSPKR_PLATFORM
1174 # interpreter that classic socket filters depend on
1179 bool "Configure standard kernel features (expert users)"
1180 # Unhide debug options, to make the on-by-default options visible
1183 This option allows certain base kernel options and settings
1184 to be disabled or tweaked. This is for specialized
1185 environments which can tolerate a "non-standard" kernel.
1186 Only use this if you really know what you are doing.
1189 bool "Enable 16-bit UID system calls" if EXPERT
1190 depends on HAVE_UID16 && MULTIUSER
1193 This enables the legacy 16-bit UID syscall wrappers.
1196 bool "Multiple users, groups and capabilities support" if EXPERT
1199 This option enables support for non-root users, groups and
1202 If you say N here, all processes will run with UID 0, GID 0, and all
1203 possible capabilities. Saying N here also compiles out support for
1204 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1207 If unsure, say Y here.
1209 config SGETMASK_SYSCALL
1210 bool "sgetmask/ssetmask syscalls support" if EXPERT
1211 def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1213 sys_sgetmask and sys_ssetmask are obsolete system calls
1214 no longer supported in libc but still enabled by default in some
1217 If unsure, leave the default option here.
1219 config SYSFS_SYSCALL
1220 bool "Sysfs syscall support" if EXPERT
1223 sys_sysfs is an obsolete system call no longer supported in libc.
1224 Note that disabling this option is more secure but might break
1225 compatibility with some systems.
1227 If unsure say Y here.
1229 config SYSCTL_SYSCALL
1230 bool "Sysctl syscall support" if EXPERT
1231 depends on PROC_SYSCTL
1235 sys_sysctl uses binary paths that have been found challenging
1236 to properly maintain and use. The interface in /proc/sys
1237 using paths with ascii names is now the primary path to this
1240 Almost nothing using the binary sysctl interface so if you are
1241 trying to save some space it is probably safe to disable this,
1242 making your kernel marginally smaller.
1244 If unsure say N here.
1247 bool "open by fhandle syscalls" if EXPERT
1251 If you say Y here, a user level program will be able to map
1252 file names to handle and then later use the handle for
1253 different file system operations. This is useful in implementing
1254 userspace file servers, which now track files using handles instead
1255 of names. The handle would remain the same even if file names
1256 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1260 bool "Posix Clocks & timers" if EXPERT
1263 This includes native support for POSIX timers to the kernel.
1264 Some embedded systems have no use for them and therefore they
1265 can be configured out to reduce the size of the kernel image.
1267 When this option is disabled, the following syscalls won't be
1268 available: timer_create, timer_gettime: timer_getoverrun,
1269 timer_settime, timer_delete, clock_adjtime, getitimer,
1270 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1271 clock_getres and clock_nanosleep syscalls will be limited to
1272 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1278 bool "Enable support for printk" if EXPERT
1281 This option enables normal printk support. Removing it
1282 eliminates most of the message strings from the kernel image
1283 and makes the kernel more or less silent. As this makes it
1284 very difficult to diagnose system problems, saying N here is
1285 strongly discouraged.
1293 bool "BUG() support" if EXPERT
1296 Disabling this option eliminates support for BUG and WARN, reducing
1297 the size of your kernel image and potentially quietly ignoring
1298 numerous fatal conditions. You should only consider disabling this
1299 option for embedded systems with no facilities for reporting errors.
1305 bool "Enable ELF core dumps" if EXPERT
1307 Enable support for generating core dumps. Disabling saves about 4k.
1310 config PCSPKR_PLATFORM
1311 bool "Enable PC-Speaker support" if EXPERT
1312 depends on HAVE_PCSPKR_PLATFORM
1316 This option allows to disable the internal PC-Speaker
1317 support, saving some memory.
1321 bool "Enable full-sized data structures for core" if EXPERT
1323 Disabling this option reduces the size of miscellaneous core
1324 kernel data structures. This saves memory on small machines,
1325 but may reduce performance.
1328 bool "Enable futex support" if EXPERT
1332 Disabling this option will cause the kernel to be built without
1333 support for "fast userspace mutexes". The resulting kernel may not
1334 run glibc-based applications correctly.
1338 depends on FUTEX && RT_MUTEXES
1341 config HAVE_FUTEX_CMPXCHG
1345 Architectures should select this if futex_atomic_cmpxchg_inatomic()
1346 is implemented and always working. This removes a couple of runtime
1350 bool "Enable eventpoll support" if EXPERT
1354 Disabling this option will cause the kernel to be built without
1355 support for epoll family of system calls.
1358 bool "Enable signalfd() system call" if EXPERT
1362 Enable the signalfd() system call that allows to receive signals
1363 on a file descriptor.
1368 bool "Enable timerfd() system call" if EXPERT
1372 Enable the timerfd() system call that allows to receive timer
1373 events on a file descriptor.
1378 bool "Enable eventfd() system call" if EXPERT
1382 Enable the eventfd() system call that allows to receive both
1383 kernel notification (ie. KAIO) or userspace notifications.
1388 bool "Use full shmem filesystem" if EXPERT
1392 The shmem is an internal filesystem used to manage shared memory.
1393 It is backed by swap and manages resource limits. It is also exported
1394 to userspace as tmpfs if TMPFS is enabled. Disabling this
1395 option replaces shmem and tmpfs with the much simpler ramfs code,
1396 which may be appropriate on small systems without swap.
1399 bool "Enable AIO support" if EXPERT
1402 This option enables POSIX asynchronous I/O which may by used
1403 by some high performance threaded applications. Disabling
1404 this option saves about 7k.
1406 config ADVISE_SYSCALLS
1407 bool "Enable madvise/fadvise syscalls" if EXPERT
1410 This option enables the madvise and fadvise syscalls, used by
1411 applications to advise the kernel about their future memory or file
1412 usage, improving performance. If building an embedded system where no
1413 applications use these syscalls, you can disable this option to save
1417 bool "Enable membarrier() system call" if EXPERT
1420 Enable the membarrier() system call that allows issuing memory
1421 barriers across all running threads, which can be used to distribute
1422 the cost of user-space memory barriers asymmetrically by transforming
1423 pairs of memory barriers into pairs consisting of membarrier() and a
1429 bool "Load all symbols for debugging/ksymoops" if EXPERT
1432 Say Y here to let the kernel print out symbolic crash information and
1433 symbolic stack backtraces. This increases the size of the kernel
1434 somewhat, as all symbols have to be loaded into the kernel image.
1437 bool "Include all symbols in kallsyms"
1438 depends on DEBUG_KERNEL && KALLSYMS
1440 Normally kallsyms only contains the symbols of functions for nicer
1441 OOPS messages and backtraces (i.e., symbols from the text and inittext
1442 sections). This is sufficient for most cases. And only in very rare
1443 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1444 names of variables from the data sections, etc).
1446 This option makes sure that all symbols are loaded into the kernel
1447 image (i.e., symbols from all sections) in cost of increased kernel
1448 size (depending on the kernel configuration, it may be 300KiB or
1449 something like this).
1451 Say N unless you really need all symbols.
1453 config KALLSYMS_ABSOLUTE_PERCPU
1456 default X86_64 && SMP
1458 config KALLSYMS_BASE_RELATIVE
1463 Instead of emitting them as absolute values in the native word size,
1464 emit the symbol references in the kallsyms table as 32-bit entries,
1465 each containing a relative value in the range [base, base + U32_MAX]
1466 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1467 an absolute value in the range [0, S32_MAX] or a relative value in the
1468 range [base, base + S32_MAX], where base is the lowest relative symbol
1469 address encountered in the image.
1471 On 64-bit builds, this reduces the size of the address table by 50%,
1472 but more importantly, it results in entries whose values are build
1473 time constants, and no relocation pass is required at runtime to fix
1474 up the entries based on the runtime load address of the kernel.
1476 # end of the "standard kernel features (expert users)" menu
1478 # syscall, maps, verifier
1480 bool "Enable bpf() system call"
1486 Enable the bpf() system call that allows to manipulate eBPF
1487 programs and maps via file descriptors.
1489 config BPF_JIT_ALWAYS_ON
1490 bool "Permanently enable BPF JIT and remove BPF interpreter"
1491 depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
1493 Enables BPF JIT and removes BPF interpreter to avoid
1494 speculative execution of BPF instructions by the interpreter
1497 bool "Enable userfaultfd() system call"
1501 Enable the userfaultfd() system call that allows to intercept and
1502 handle page faults in userland.
1504 config ARCH_HAS_MEMBARRIER_CALLBACKS
1507 config ARCH_HAS_MEMBARRIER_SYNC_CORE
1511 bool "Enable rseq() system call" if EXPERT
1513 depends on HAVE_RSEQ
1516 Enable the restartable sequences system call. It provides a
1517 user-space cache for the current CPU number value, which
1518 speeds up getting the current CPU number from user-space,
1519 as well as an ABI to speed up user-space operations on
1526 bool "Enabled debugging of rseq() system call" if EXPERT
1527 depends on RSEQ && DEBUG_KERNEL
1529 Enable extra debugging checks for the rseq system call.
1534 bool "Embedded system"
1535 option allnoconfig_y
1538 This option should be enabled if compiling the kernel for
1539 an embedded system so certain expert options are available
1542 config HAVE_PERF_EVENTS
1545 See tools/perf/design.txt for details.
1547 config PERF_USE_VMALLOC
1550 See tools/perf/design.txt for details
1553 bool "PC/104 support" if EXPERT
1555 Expose PC/104 form factor device drivers and options available for
1556 selection and configuration. Enable this option if your target
1557 machine has a PC/104 bus.
1559 menu "Kernel Performance Events And Counters"
1562 bool "Kernel performance events and counters"
1563 default y if PROFILING
1564 depends on HAVE_PERF_EVENTS
1569 Enable kernel support for various performance events provided
1570 by software and hardware.
1572 Software events are supported either built-in or via the
1573 use of generic tracepoints.
1575 Most modern CPUs support performance events via performance
1576 counter registers. These registers count the number of certain
1577 types of hw events: such as instructions executed, cachemisses
1578 suffered, or branches mis-predicted - without slowing down the
1579 kernel or applications. These registers can also trigger interrupts
1580 when a threshold number of events have passed - and can thus be
1581 used to profile the code that runs on that CPU.
1583 The Linux Performance Event subsystem provides an abstraction of
1584 these software and hardware event capabilities, available via a
1585 system call and used by the "perf" utility in tools/perf/. It
1586 provides per task and per CPU counters, and it provides event
1587 capabilities on top of those.
1591 config DEBUG_PERF_USE_VMALLOC
1593 bool "Debug: use vmalloc to back perf mmap() buffers"
1594 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1595 select PERF_USE_VMALLOC
1597 Use vmalloc memory to back perf mmap() buffers.
1599 Mostly useful for debugging the vmalloc code on platforms
1600 that don't require it.
1606 config VM_EVENT_COUNTERS
1608 bool "Enable VM event counters for /proc/vmstat" if EXPERT
1610 VM event counters are needed for event counts to be shown.
1611 This option allows the disabling of the VM event counters
1612 on EXPERT systems. /proc/vmstat will only show page counts
1613 if VM event counters are disabled.
1617 bool "Enable SLUB debugging support" if EXPERT
1618 depends on SLUB && SYSFS
1620 SLUB has extensive debug support features. Disabling these can
1621 result in significant savings in code size. This also disables
1622 SLUB sysfs support. /sys/slab will not exist and there will be
1623 no support for cache validation etc.
1625 config SLUB_MEMCG_SYSFS_ON
1627 bool "Enable memcg SLUB sysfs support by default" if EXPERT
1628 depends on SLUB && SYSFS && MEMCG
1630 SLUB creates a directory under /sys/kernel/slab for each
1631 allocation cache to host info and debug files. If memory
1632 cgroup is enabled, each cache can have per memory cgroup
1633 caches. SLUB can create the same sysfs directories for these
1634 caches under /sys/kernel/slab/CACHE/cgroup but it can lead
1635 to a very high number of debug files being created. This is
1636 controlled by slub_memcg_sysfs boot parameter and this
1637 config option determines the parameter's default value.
1640 bool "Disable heap randomization"
1643 Randomizing heap placement makes heap exploits harder, but it
1644 also breaks ancient binaries (including anything libc5 based).
1645 This option changes the bootup default to heap randomization
1646 disabled, and can be overridden at runtime by setting
1647 /proc/sys/kernel/randomize_va_space to 2.
1649 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1652 prompt "Choose SLAB allocator"
1655 This option allows to select a slab allocator.
1659 select HAVE_HARDENED_USERCOPY_ALLOCATOR
1661 The regular slab allocator that is established and known to work
1662 well in all environments. It organizes cache hot objects in
1663 per cpu and per node queues.
1666 bool "SLUB (Unqueued Allocator)"
1667 select HAVE_HARDENED_USERCOPY_ALLOCATOR
1669 SLUB is a slab allocator that minimizes cache line usage
1670 instead of managing queues of cached objects (SLAB approach).
1671 Per cpu caching is realized using slabs of objects instead
1672 of queues of objects. SLUB can use memory efficiently
1673 and has enhanced diagnostics. SLUB is the default choice for
1678 bool "SLOB (Simple Allocator)"
1680 SLOB replaces the stock allocator with a drastically simpler
1681 allocator. SLOB is generally more space efficient but
1682 does not perform as well on large systems.
1686 config SLAB_MERGE_DEFAULT
1687 bool "Allow slab caches to be merged"
1690 For reduced kernel memory fragmentation, slab caches can be
1691 merged when they share the same size and other characteristics.
1692 This carries a risk of kernel heap overflows being able to
1693 overwrite objects from merged caches (and more easily control
1694 cache layout), which makes such heap attacks easier to exploit
1695 by attackers. By keeping caches unmerged, these kinds of exploits
1696 can usually only damage objects in the same cache. To disable
1697 merging at runtime, "slab_nomerge" can be passed on the kernel
1700 config SLAB_FREELIST_RANDOM
1702 depends on SLAB || SLUB
1703 bool "SLAB freelist randomization"
1705 Randomizes the freelist order used on creating new pages. This
1706 security feature reduces the predictability of the kernel slab
1707 allocator against heap overflows.
1709 config SLAB_FREELIST_HARDENED
1710 bool "Harden slab freelist metadata"
1713 Many kernel heap attacks try to target slab cache metadata and
1714 other infrastructure. This options makes minor performance
1715 sacrifies to harden the kernel slab allocator against common
1716 freelist exploit methods.
1718 config SLUB_CPU_PARTIAL
1720 depends on SLUB && SMP
1721 bool "SLUB per cpu partial cache"
1723 Per cpu partial caches accellerate objects allocation and freeing
1724 that is local to a processor at the price of more indeterminism
1725 in the latency of the free. On overflow these caches will be cleared
1726 which requires the taking of locks that may cause latency spikes.
1727 Typically one would choose no for a realtime system.
1729 config MMAP_ALLOW_UNINITIALIZED
1730 bool "Allow mmapped anonymous memory to be uninitialized"
1731 depends on EXPERT && !MMU
1734 Normally, and according to the Linux spec, anonymous memory obtained
1735 from mmap() has its contents cleared before it is passed to
1736 userspace. Enabling this config option allows you to request that
1737 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1738 providing a huge performance boost. If this option is not enabled,
1739 then the flag will be ignored.
1741 This is taken advantage of by uClibc's malloc(), and also by
1742 ELF-FDPIC binfmt's brk and stack allocator.
1744 Because of the obvious security issues, this option should only be
1745 enabled on embedded devices where you control what is run in
1746 userspace. Since that isn't generally a problem on no-MMU systems,
1747 it is normally safe to say Y here.
1749 See Documentation/nommu-mmap.txt for more information.
1751 config SYSTEM_DATA_VERIFICATION
1753 select SYSTEM_TRUSTED_KEYRING
1757 select ASYMMETRIC_KEY_TYPE
1758 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1761 select X509_CERTIFICATE_PARSER
1762 select PKCS7_MESSAGE_PARSER
1764 Provide PKCS#7 message verification using the contents of the system
1765 trusted keyring to provide public keys. This then can be used for
1766 module verification, kexec image verification and firmware blob
1770 bool "Profiling support"
1772 Say Y here to enable the extended profiling support mechanisms used
1773 by profilers such as OProfile.
1776 # Place an empty function call at each tracepoint site. Can be
1777 # dynamically changed for a probe function.
1782 endmenu # General setup
1784 source "arch/Kconfig"
1791 default 0 if BASE_FULL
1792 default 1 if !BASE_FULL
1795 bool "Enable loadable module support"
1798 Kernel modules are small pieces of compiled code which can
1799 be inserted in the running kernel, rather than being
1800 permanently built into the kernel. You use the "modprobe"
1801 tool to add (and sometimes remove) them. If you say Y here,
1802 many parts of the kernel can be built as modules (by
1803 answering M instead of Y where indicated): this is most
1804 useful for infrequently used options which are not required
1805 for booting. For more information, see the man pages for
1806 modprobe, lsmod, modinfo, insmod and rmmod.
1808 If you say Y here, you will need to run "make
1809 modules_install" to put the modules under /lib/modules/
1810 where modprobe can find them (you may need to be root to do
1817 config MODULE_FORCE_LOAD
1818 bool "Forced module loading"
1821 Allow loading of modules without version information (ie. modprobe
1822 --force). Forced module loading sets the 'F' (forced) taint flag and
1823 is usually a really bad idea.
1825 config MODULE_UNLOAD
1826 bool "Module unloading"
1828 Without this option you will not be able to unload any
1829 modules (note that some modules may not be unloadable
1830 anyway), which makes your kernel smaller, faster
1831 and simpler. If unsure, say Y.
1833 config MODULE_FORCE_UNLOAD
1834 bool "Forced module unloading"
1835 depends on MODULE_UNLOAD
1837 This option allows you to force a module to unload, even if the
1838 kernel believes it is unsafe: the kernel will remove the module
1839 without waiting for anyone to stop using it (using the -f option to
1840 rmmod). This is mainly for kernel developers and desperate users.
1844 bool "Module versioning support"
1846 Usually, you have to use modules compiled with your kernel.
1847 Saying Y here makes it sometimes possible to use modules
1848 compiled for different kernels, by adding enough information
1849 to the modules to (hopefully) spot any changes which would
1850 make them incompatible with the kernel you are running. If
1853 config MODULE_REL_CRCS
1855 depends on MODVERSIONS
1857 config MODULE_SRCVERSION_ALL
1858 bool "Source checksum for all modules"
1860 Modules which contain a MODULE_VERSION get an extra "srcversion"
1861 field inserted into their modinfo section, which contains a
1862 sum of the source files which made it. This helps maintainers
1863 see exactly which source was used to build a module (since
1864 others sometimes change the module source without updating
1865 the version). With this option, such a "srcversion" field
1866 will be created for all modules. If unsure, say N.
1869 bool "Module signature verification"
1871 select SYSTEM_DATA_VERIFICATION
1873 Check modules for valid signatures upon load: the signature
1874 is simply appended to the module. For more information see
1875 <file:Documentation/admin-guide/module-signing.rst>.
1877 Note that this option adds the OpenSSL development packages as a
1878 kernel build dependency so that the signing tool can use its crypto
1881 !!!WARNING!!! If you enable this option, you MUST make sure that the
1882 module DOES NOT get stripped after being signed. This includes the
1883 debuginfo strip done by some packagers (such as rpmbuild) and
1884 inclusion into an initramfs that wants the module size reduced.
1886 config MODULE_SIG_FORCE
1887 bool "Require modules to be validly signed"
1888 depends on MODULE_SIG
1890 Reject unsigned modules or signed modules for which we don't have a
1891 key. Without this, such modules will simply taint the kernel.
1893 config MODULE_SIG_ALL
1894 bool "Automatically sign all modules"
1896 depends on MODULE_SIG
1898 Sign all modules during make modules_install. Without this option,
1899 modules must be signed manually, using the scripts/sign-file tool.
1901 comment "Do not forget to sign required modules with scripts/sign-file"
1902 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
1905 prompt "Which hash algorithm should modules be signed with?"
1906 depends on MODULE_SIG
1908 This determines which sort of hashing algorithm will be used during
1909 signature generation. This algorithm _must_ be built into the kernel
1910 directly so that signature verification can take place. It is not
1911 possible to load a signed module containing the algorithm to check
1912 the signature on that module.
1914 config MODULE_SIG_SHA1
1915 bool "Sign modules with SHA-1"
1918 config MODULE_SIG_SHA224
1919 bool "Sign modules with SHA-224"
1920 select CRYPTO_SHA256
1922 config MODULE_SIG_SHA256
1923 bool "Sign modules with SHA-256"
1924 select CRYPTO_SHA256
1926 config MODULE_SIG_SHA384
1927 bool "Sign modules with SHA-384"
1928 select CRYPTO_SHA512
1930 config MODULE_SIG_SHA512
1931 bool "Sign modules with SHA-512"
1932 select CRYPTO_SHA512
1936 config MODULE_SIG_HASH
1938 depends on MODULE_SIG
1939 default "sha1" if MODULE_SIG_SHA1
1940 default "sha224" if MODULE_SIG_SHA224
1941 default "sha256" if MODULE_SIG_SHA256
1942 default "sha384" if MODULE_SIG_SHA384
1943 default "sha512" if MODULE_SIG_SHA512
1945 config MODULE_COMPRESS
1946 bool "Compress modules on installation"
1950 Compresses kernel modules when 'make modules_install' is run; gzip or
1951 xz depending on "Compression algorithm" below.
1953 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
1955 Out-of-tree kernel modules installed using Kbuild will also be
1956 compressed upon installation.
1958 Note: for modules inside an initrd or initramfs, it's more efficient
1959 to compress the whole initrd or initramfs instead.
1961 Note: This is fully compatible with signed modules.
1966 prompt "Compression algorithm"
1967 depends on MODULE_COMPRESS
1968 default MODULE_COMPRESS_GZIP
1970 This determines which sort of compression will be used during
1971 'make modules_install'.
1973 GZIP (default) and XZ are supported.
1975 config MODULE_COMPRESS_GZIP
1978 config MODULE_COMPRESS_XZ
1983 config TRIM_UNUSED_KSYMS
1984 bool "Trim unused exported kernel symbols"
1985 depends on MODULES && !UNUSED_SYMBOLS
1987 The kernel and some modules make many symbols available for
1988 other modules to use via EXPORT_SYMBOL() and variants. Depending
1989 on the set of modules being selected in your kernel configuration,
1990 many of those exported symbols might never be used.
1992 This option allows for unused exported symbols to be dropped from
1993 the build. In turn, this provides the compiler more opportunities
1994 (especially when using LTO) for optimizing the code and reducing
1995 binary size. This might have some security advantages as well.
1997 If unsure, or if you need to build out-of-tree modules, say N.
2001 config MODULES_TREE_LOOKUP
2003 depends on PERF_EVENTS || TRACING
2005 config INIT_ALL_POSSIBLE
2008 Back when each arch used to define their own cpu_online_mask and
2009 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2010 with all 1s, and others with all 0s. When they were centralised,
2011 it was better to provide this option than to break all the archs
2012 and have several arch maintainers pursuing me down dark alleys.
2014 source "block/Kconfig"
2016 config PREEMPT_NOTIFIERS
2026 Build a simple ASN.1 grammar compiler that produces a bytecode output
2027 that can be interpreted by the ASN.1 stream decoder and used to
2028 inform it as to what tags are to be expected in a stream and what
2029 functions to call on what tags.
2031 source "kernel/Kconfig.locks"
2033 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2036 # It may be useful for an architecture to override the definitions of the
2037 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2038 # and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2039 # different calling convention for syscalls. They can also override the
2040 # macros for not-implemented syscalls in kernel/sys_ni.c and
2041 # kernel/time/posix-stubs.c. All these overrides need to be available in
2042 # <asm/syscall_wrapper.h>.
2043 config ARCH_HAS_SYSCALL_WRAPPER
git.samba.org / sfrench / cifs-2.6.git / blob