5 default "/lib/modules/$(shell,uname --release)/.config"
6 default "/etc/kernel-config"
7 default "/boot/config-$(shell,uname --release)"
9 default "arch/$(ARCH)/defconfig"
18 config BUILDTIME_EXTABLE_SORT
21 config THREAD_INFO_IN_TASK
24 Select this to move thread_info off the stack into task_struct. To
25 make this work, an arch will need to remove all thread_info fields
26 except flags and fix any runtime bugs.
28 One subtle change that will be needed is to use try_get_task_stack()
29 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
38 depends on BROKEN || !SMP
41 config INIT_ENV_ARG_LIMIT
46 Maximum of each of the number of arguments and environment
47 variables passed to init from the kernel command line.
50 bool "Compile also drivers which will not load"
54 Some drivers can be compiled on a different platform than they are
55 intended to be run on. Despite they cannot be loaded there (or even
56 when they load they cannot be used due to missing HW support),
57 developers still, opposing to distributors, might want to build such
58 drivers to compile-test them.
60 If you are a developer and want to build everything available, say Y
61 here. If you are a user/distributor, say N here to exclude useless
62 drivers to be distributed.
65 string "Local version - append to kernel release"
67 Append an extra string to the end of your kernel version.
68 This will show up when you type uname, for example.
69 The string you set here will be appended after the contents of
70 any files with a filename matching localversion* in your
71 object and source tree, in that order. Your total string can
72 be a maximum of 64 characters.
74 config LOCALVERSION_AUTO
75 bool "Automatically append version information to the version string"
77 depends on !COMPILE_TEST
79 This will try to automatically determine if the current tree is a
80 release tree by looking for git tags that belong to the current
83 A string of the format -gxxxxxxxx will be added to the localversion
84 if a git-based tree is found. The string generated by this will be
85 appended after any matching localversion* files, and after the value
86 set in CONFIG_LOCALVERSION.
88 (The actual string used here is the first eight characters produced
89 by running the command:
91 $ git rev-parse --verify HEAD
93 which is done within the script "scripts/setlocalversion".)
95 config HAVE_KERNEL_GZIP
98 config HAVE_KERNEL_BZIP2
101 config HAVE_KERNEL_LZMA
104 config HAVE_KERNEL_XZ
107 config HAVE_KERNEL_LZO
110 config HAVE_KERNEL_LZ4
114 prompt "Kernel compression mode"
116 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4
118 The linux kernel is a kind of self-extracting executable.
119 Several compression algorithms are available, which differ
120 in efficiency, compression and decompression speed.
121 Compression speed is only relevant when building a kernel.
122 Decompression speed is relevant at each boot.
124 If you have any problems with bzip2 or lzma compressed
125 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
126 version of this functionality (bzip2 only), for 2.4, was
127 supplied by Christian Ludwig)
129 High compression options are mostly useful for users, who
130 are low on disk space (embedded systems), but for whom ram
133 If in doubt, select 'gzip'
137 depends on HAVE_KERNEL_GZIP
139 The old and tried gzip compression. It provides a good balance
140 between compression ratio and decompression speed.
144 depends on HAVE_KERNEL_BZIP2
146 Its compression ratio and speed is intermediate.
147 Decompression speed is slowest among the choices. The kernel
148 size is about 10% smaller with bzip2, in comparison to gzip.
149 Bzip2 uses a large amount of memory. For modern kernels you
150 will need at least 8MB RAM or more for booting.
154 depends on HAVE_KERNEL_LZMA
156 This compression algorithm's ratio is best. Decompression speed
157 is between gzip and bzip2. Compression is slowest.
158 The kernel size is about 33% smaller with LZMA in comparison to gzip.
162 depends on HAVE_KERNEL_XZ
164 XZ uses the LZMA2 algorithm and instruction set specific
165 BCJ filters which can improve compression ratio of executable
166 code. The size of the kernel is about 30% smaller with XZ in
167 comparison to gzip. On architectures for which there is a BCJ
168 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
169 will create a few percent smaller kernel than plain LZMA.
171 The speed is about the same as with LZMA: The decompression
172 speed of XZ is better than that of bzip2 but worse than gzip
173 and LZO. Compression is slow.
177 depends on HAVE_KERNEL_LZO
179 Its compression ratio is the poorest among the choices. The kernel
180 size is about 10% bigger than gzip; however its speed
181 (both compression and decompression) is the fastest.
185 depends on HAVE_KERNEL_LZ4
187 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
188 A preliminary version of LZ4 de/compression tool is available at
189 <https://code.google.com/p/lz4/>.
191 Its compression ratio is worse than LZO. The size of the kernel
192 is about 8% bigger than LZO. But the decompression speed is
197 config DEFAULT_HOSTNAME
198 string "Default hostname"
201 This option determines the default system hostname before userspace
202 calls sethostname(2). The kernel traditionally uses "(none)" here,
203 but you may wish to use a different default here to make a minimal
204 system more usable with less configuration.
207 bool "Support for paging of anonymous memory (swap)"
208 depends on MMU && BLOCK
211 This option allows you to choose whether you want to have support
212 for so called swap devices or swap files in your kernel that are
213 used to provide more virtual memory than the actual RAM present
214 in your computer. If unsure say Y.
219 Inter Process Communication is a suite of library functions and
220 system calls which let processes (running programs) synchronize and
221 exchange information. It is generally considered to be a good thing,
222 and some programs won't run unless you say Y here. In particular, if
223 you want to run the DOS emulator dosemu under Linux (read the
224 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
225 you'll need to say Y here.
227 You can find documentation about IPC with "info ipc" and also in
228 section 6.4 of the Linux Programmer's Guide, available from
229 <http://www.tldp.org/guides.html>.
231 config SYSVIPC_SYSCTL
238 bool "POSIX Message Queues"
241 POSIX variant of message queues is a part of IPC. In POSIX message
242 queues every message has a priority which decides about succession
243 of receiving it by a process. If you want to compile and run
244 programs written e.g. for Solaris with use of its POSIX message
245 queues (functions mq_*) say Y here.
247 POSIX message queues are visible as a filesystem called 'mqueue'
248 and can be mounted somewhere if you want to do filesystem
249 operations on message queues.
253 config POSIX_MQUEUE_SYSCTL
255 depends on POSIX_MQUEUE
259 config CROSS_MEMORY_ATTACH
260 bool "Enable process_vm_readv/writev syscalls"
264 Enabling this option adds the system calls process_vm_readv and
265 process_vm_writev which allow a process with the correct privileges
266 to directly read from or write to another process' address space.
267 See the man page for more details.
270 bool "uselib syscall"
271 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
273 This option enables the uselib syscall, a system call used in the
274 dynamic linker from libc5 and earlier. glibc does not use this
275 system call. If you intend to run programs built on libc5 or
276 earlier, you may need to enable this syscall. Current systems
277 running glibc can safely disable this.
280 bool "Auditing support"
283 Enable auditing infrastructure that can be used with another
284 kernel subsystem, such as SELinux (which requires this for
285 logging of avc messages output). System call auditing is included
286 on architectures which support it.
288 config HAVE_ARCH_AUDITSYSCALL
293 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
297 depends on AUDITSYSCALL
302 depends on AUDITSYSCALL
305 source "kernel/irq/Kconfig"
306 source "kernel/time/Kconfig"
308 menu "CPU/Task time and stats accounting"
310 config VIRT_CPU_ACCOUNTING
314 prompt "Cputime accounting"
315 default TICK_CPU_ACCOUNTING if !PPC64
316 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
318 # Kind of a stub config for the pure tick based cputime accounting
319 config TICK_CPU_ACCOUNTING
320 bool "Simple tick based cputime accounting"
321 depends on !S390 && !NO_HZ_FULL
323 This is the basic tick based cputime accounting that maintains
324 statistics about user, system and idle time spent on per jiffies
329 config VIRT_CPU_ACCOUNTING_NATIVE
330 bool "Deterministic task and CPU time accounting"
331 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
332 select VIRT_CPU_ACCOUNTING
334 Select this option to enable more accurate task and CPU time
335 accounting. This is done by reading a CPU counter on each
336 kernel entry and exit and on transitions within the kernel
337 between system, softirq and hardirq state, so there is a
338 small performance impact. In the case of s390 or IBM POWER > 5,
339 this also enables accounting of stolen time on logically-partitioned
342 config VIRT_CPU_ACCOUNTING_GEN
343 bool "Full dynticks CPU time accounting"
344 depends on HAVE_CONTEXT_TRACKING
345 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
346 select VIRT_CPU_ACCOUNTING
347 select CONTEXT_TRACKING
349 Select this option to enable task and CPU time accounting on full
350 dynticks systems. This accounting is implemented by watching every
351 kernel-user boundaries using the context tracking subsystem.
352 The accounting is thus performed at the expense of some significant
355 For now this is only useful if you are working on the full
356 dynticks subsystem development.
362 config IRQ_TIME_ACCOUNTING
363 bool "Fine granularity task level IRQ time accounting"
364 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
366 Select this option to enable fine granularity task irq time
367 accounting. This is done by reading a timestamp on each
368 transitions between softirq and hardirq state, so there can be a
369 small performance impact.
371 If in doubt, say N here.
373 config BSD_PROCESS_ACCT
374 bool "BSD Process Accounting"
377 If you say Y here, a user level program will be able to instruct the
378 kernel (via a special system call) to write process accounting
379 information to a file: whenever a process exits, information about
380 that process will be appended to the file by the kernel. The
381 information includes things such as creation time, owning user,
382 command name, memory usage, controlling terminal etc. (the complete
383 list is in the struct acct in <file:include/linux/acct.h>). It is
384 up to the user level program to do useful things with this
385 information. This is generally a good idea, so say Y.
387 config BSD_PROCESS_ACCT_V3
388 bool "BSD Process Accounting version 3 file format"
389 depends on BSD_PROCESS_ACCT
392 If you say Y here, the process accounting information is written
393 in a new file format that also logs the process IDs of each
394 process and it's parent. Note that this file format is incompatible
395 with previous v0/v1/v2 file formats, so you will need updated tools
396 for processing it. A preliminary version of these tools is available
397 at <http://www.gnu.org/software/acct/>.
400 bool "Export task/process statistics through netlink"
405 Export selected statistics for tasks/processes through the
406 generic netlink interface. Unlike BSD process accounting, the
407 statistics are available during the lifetime of tasks/processes as
408 responses to commands. Like BSD accounting, they are sent to user
413 config TASK_DELAY_ACCT
414 bool "Enable per-task delay accounting"
418 Collect information on time spent by a task waiting for system
419 resources like cpu, synchronous block I/O completion and swapping
420 in pages. Such statistics can help in setting a task's priorities
421 relative to other tasks for cpu, io, rss limits etc.
426 bool "Enable extended accounting over taskstats"
429 Collect extended task accounting data and send the data
430 to userland for processing over the taskstats interface.
434 config TASK_IO_ACCOUNTING
435 bool "Enable per-task storage I/O accounting"
436 depends on TASK_XACCT
438 Collect information on the number of bytes of storage I/O which this
443 endmenu # "CPU/Task time and stats accounting"
447 depends on SMP || COMPILE_TEST
450 Make sure that CPUs running critical tasks are not disturbed by
451 any source of "noise" such as unbound workqueues, timers, kthreads...
452 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
453 the "isolcpus=" boot parameter.
457 source "kernel/rcu/Kconfig"
464 tristate "Kernel .config support"
467 This option enables the complete Linux kernel ".config" file
468 contents to be saved in the kernel. It provides documentation
469 of which kernel options are used in a running kernel or in an
470 on-disk kernel. This information can be extracted from the kernel
471 image file with the script scripts/extract-ikconfig and used as
472 input to rebuild the current kernel or to build another kernel.
473 It can also be extracted from a running kernel by reading
474 /proc/config.gz if enabled (below).
477 bool "Enable access to .config through /proc/config.gz"
478 depends on IKCONFIG && PROC_FS
480 This option enables access to the kernel configuration file
481 through /proc/config.gz.
484 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
489 Select the minimal kernel log buffer size as a power of 2.
490 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
491 parameter, see below. Any higher size also might be forced
492 by "log_buf_len" boot parameter.
502 config LOG_CPU_MAX_BUF_SHIFT
503 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
506 default 12 if !BASE_SMALL
507 default 0 if BASE_SMALL
510 This option allows to increase the default ring buffer size
511 according to the number of CPUs. The value defines the contribution
512 of each CPU as a power of 2. The used space is typically only few
513 lines however it might be much more when problems are reported,
516 The increased size means that a new buffer has to be allocated and
517 the original static one is unused. It makes sense only on systems
518 with more CPUs. Therefore this value is used only when the sum of
519 contributions is greater than the half of the default kernel ring
520 buffer as defined by LOG_BUF_SHIFT. The default values are set
521 so that more than 64 CPUs are needed to trigger the allocation.
523 Also this option is ignored when "log_buf_len" kernel parameter is
524 used as it forces an exact (power of two) size of the ring buffer.
526 The number of possible CPUs is used for this computation ignoring
527 hotplugging making the computation optimal for the worst case
528 scenario while allowing a simple algorithm to be used from bootup.
530 Examples shift values and their meaning:
531 17 => 128 KB for each CPU
532 16 => 64 KB for each CPU
533 15 => 32 KB for each CPU
534 14 => 16 KB for each CPU
535 13 => 8 KB for each CPU
536 12 => 4 KB for each CPU
538 config PRINTK_SAFE_LOG_BUF_SHIFT
539 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
544 Select the size of an alternate printk per-CPU buffer where messages
545 printed from usafe contexts are temporary stored. One example would
546 be NMI messages, another one - printk recursion. The messages are
547 copied to the main log buffer in a safe context to avoid a deadlock.
548 The value defines the size as a power of 2.
550 Those messages are rare and limited. The largest one is when
551 a backtrace is printed. It usually fits into 4KB. Select
552 8KB if you want to be on the safe side.
555 17 => 128 KB for each CPU
556 16 => 64 KB for each CPU
557 15 => 32 KB for each CPU
558 14 => 16 KB for each CPU
559 13 => 8 KB for each CPU
560 12 => 4 KB for each CPU
563 # Architectures with an unreliable sched_clock() should select this:
565 config HAVE_UNSTABLE_SCHED_CLOCK
568 config GENERIC_SCHED_CLOCK
572 # For architectures that want to enable the support for NUMA-affine scheduler
575 config ARCH_SUPPORTS_NUMA_BALANCING
579 # For architectures that prefer to flush all TLBs after a number of pages
580 # are unmapped instead of sending one IPI per page to flush. The architecture
581 # must provide guarantees on what happens if a clean TLB cache entry is
582 # written after the unmap. Details are in mm/rmap.c near the check for
583 # should_defer_flush. The architecture should also consider if the full flush
584 # and the refill costs are offset by the savings of sending fewer IPIs.
585 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
589 # For architectures that know their GCC __int128 support is sound
591 config ARCH_SUPPORTS_INT128
594 # For architectures that (ab)use NUMA to represent different memory regions
595 # all cpu-local but of different latencies, such as SuperH.
597 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
600 config NUMA_BALANCING
601 bool "Memory placement aware NUMA scheduler"
602 depends on ARCH_SUPPORTS_NUMA_BALANCING
603 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
604 depends on SMP && NUMA && MIGRATION
606 This option adds support for automatic NUMA aware memory/task placement.
607 The mechanism is quite primitive and is based on migrating memory when
608 it has references to the node the task is running on.
610 This system will be inactive on UMA systems.
612 config NUMA_BALANCING_DEFAULT_ENABLED
613 bool "Automatically enable NUMA aware memory/task placement"
615 depends on NUMA_BALANCING
617 If set, automatic NUMA balancing will be enabled if running on a NUMA
621 bool "Control Group support"
624 This option adds support for grouping sets of processes together, for
625 use with process control subsystems such as Cpusets, CFS, memory
626 controls or device isolation.
628 - Documentation/scheduler/sched-design-CFS.txt (CFS)
629 - Documentation/cgroup-v1/ (features for grouping, isolation
630 and resource control)
640 bool "Memory controller"
644 Provides control over the memory footprint of tasks in a cgroup.
647 bool "Swap controller"
648 depends on MEMCG && SWAP
650 Provides control over the swap space consumed by tasks in a cgroup.
652 config MEMCG_SWAP_ENABLED
653 bool "Swap controller enabled by default"
654 depends on MEMCG_SWAP
657 Memory Resource Controller Swap Extension comes with its price in
658 a bigger memory consumption. General purpose distribution kernels
659 which want to enable the feature but keep it disabled by default
660 and let the user enable it by swapaccount=1 boot command line
661 parameter should have this option unselected.
662 For those who want to have the feature enabled by default should
663 select this option (if, for some reason, they need to disable it
664 then swapaccount=0 does the trick).
671 Generic block IO controller cgroup interface. This is the common
672 cgroup interface which should be used by various IO controlling
675 Currently, CFQ IO scheduler uses it to recognize task groups and
676 control disk bandwidth allocation (proportional time slice allocation)
677 to such task groups. It is also used by bio throttling logic in
678 block layer to implement upper limit in IO rates on a device.
680 This option only enables generic Block IO controller infrastructure.
681 One needs to also enable actual IO controlling logic/policy. For
682 enabling proportional weight division of disk bandwidth in CFQ, set
683 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
684 CONFIG_BLK_DEV_THROTTLING=y.
686 See Documentation/cgroup-v1/blkio-controller.txt for more information.
688 config DEBUG_BLK_CGROUP
689 bool "IO controller debugging"
690 depends on BLK_CGROUP
693 Enable some debugging help. Currently it exports additional stat
694 files in a cgroup which can be useful for debugging.
696 config CGROUP_WRITEBACK
698 depends on MEMCG && BLK_CGROUP
701 menuconfig CGROUP_SCHED
702 bool "CPU controller"
705 This feature lets CPU scheduler recognize task groups and control CPU
706 bandwidth allocation to such task groups. It uses cgroups to group
710 config FAIR_GROUP_SCHED
711 bool "Group scheduling for SCHED_OTHER"
712 depends on CGROUP_SCHED
716 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
717 depends on FAIR_GROUP_SCHED
720 This option allows users to define CPU bandwidth rates (limits) for
721 tasks running within the fair group scheduler. Groups with no limit
722 set are considered to be unconstrained and will run with no
724 See Documentation/scheduler/sched-bwc.txt for more information.
726 config RT_GROUP_SCHED
727 bool "Group scheduling for SCHED_RR/FIFO"
728 depends on CGROUP_SCHED
731 This feature lets you explicitly allocate real CPU bandwidth
732 to task groups. If enabled, it will also make it impossible to
733 schedule realtime tasks for non-root users until you allocate
734 realtime bandwidth for them.
735 See Documentation/scheduler/sched-rt-group.txt for more information.
740 bool "PIDs controller"
742 Provides enforcement of process number limits in the scope of a
743 cgroup. Any attempt to fork more processes than is allowed in the
744 cgroup will fail. PIDs are fundamentally a global resource because it
745 is fairly trivial to reach PID exhaustion before you reach even a
746 conservative kmemcg limit. As a result, it is possible to grind a
747 system to halt without being limited by other cgroup policies. The
748 PIDs controller is designed to stop this from happening.
750 It should be noted that organisational operations (such as attaching
751 to a cgroup hierarchy will *not* be blocked by the PIDs controller),
752 since the PIDs limit only affects a process's ability to fork, not to
756 bool "RDMA controller"
758 Provides enforcement of RDMA resources defined by IB stack.
759 It is fairly easy for consumers to exhaust RDMA resources, which
760 can result into resource unavailability to other consumers.
761 RDMA controller is designed to stop this from happening.
762 Attaching processes with active RDMA resources to the cgroup
763 hierarchy is allowed even if can cross the hierarchy's limit.
765 config CGROUP_FREEZER
766 bool "Freezer controller"
768 Provides a way to freeze and unfreeze all tasks in a
771 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
772 controller includes important in-kernel memory consumers per default.
774 If you're using cgroup2, say N.
776 config CGROUP_HUGETLB
777 bool "HugeTLB controller"
778 depends on HUGETLB_PAGE
782 Provides a cgroup controller for HugeTLB pages.
783 When you enable this, you can put a per cgroup limit on HugeTLB usage.
784 The limit is enforced during page fault. Since HugeTLB doesn't
785 support page reclaim, enforcing the limit at page fault time implies
786 that, the application will get SIGBUS signal if it tries to access
787 HugeTLB pages beyond its limit. This requires the application to know
788 beforehand how much HugeTLB pages it would require for its use. The
789 control group is tracked in the third page lru pointer. This means
790 that we cannot use the controller with huge page less than 3 pages.
793 bool "Cpuset controller"
796 This option will let you create and manage CPUSETs which
797 allow dynamically partitioning a system into sets of CPUs and
798 Memory Nodes and assigning tasks to run only within those sets.
799 This is primarily useful on large SMP or NUMA systems.
803 config PROC_PID_CPUSET
804 bool "Include legacy /proc/<pid>/cpuset file"
809 bool "Device controller"
811 Provides a cgroup controller implementing whitelists for
812 devices which a process in the cgroup can mknod or open.
814 config CGROUP_CPUACCT
815 bool "Simple CPU accounting controller"
817 Provides a simple controller for monitoring the
818 total CPU consumed by the tasks in a cgroup.
821 bool "Perf controller"
822 depends on PERF_EVENTS
824 This option extends the perf per-cpu mode to restrict monitoring
825 to threads which belong to the cgroup specified and run on the
831 bool "Support for eBPF programs attached to cgroups"
832 depends on BPF_SYSCALL
833 select SOCK_CGROUP_DATA
835 Allow attaching eBPF programs to a cgroup using the bpf(2)
836 syscall command BPF_PROG_ATTACH.
838 In which context these programs are accessed depends on the type
839 of attachment. For instance, programs that are attached using
840 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
844 bool "Debug controller"
846 depends on DEBUG_KERNEL
848 This option enables a simple controller that exports
849 debugging information about the cgroups framework. This
850 controller is for control cgroup debugging only. Its
851 interfaces are not stable.
855 config SOCK_CGROUP_DATA
861 menuconfig NAMESPACES
862 bool "Namespaces support" if EXPERT
866 Provides the way to make tasks work with different objects using
867 the same id. For example same IPC id may refer to different objects
868 or same user id or pid may refer to different tasks when used in
869 different namespaces.
877 In this namespace tasks see different info provided with the
882 depends on (SYSVIPC || POSIX_MQUEUE)
885 In this namespace tasks work with IPC ids which correspond to
886 different IPC objects in different namespaces.
889 bool "User namespace"
892 This allows containers, i.e. vservers, to use user namespaces
893 to provide different user info for different servers.
895 When user namespaces are enabled in the kernel it is
896 recommended that the MEMCG option also be enabled and that
897 user-space use the memory control groups to limit the amount
898 of memory a memory unprivileged users can use.
903 bool "PID Namespaces"
906 Support process id namespaces. This allows having multiple
907 processes with the same pid as long as they are in different
908 pid namespaces. This is a building block of containers.
911 bool "Network namespace"
915 Allow user space to create what appear to be multiple instances
916 of the network stack.
920 config SCHED_AUTOGROUP
921 bool "Automatic process group scheduling"
924 select FAIR_GROUP_SCHED
926 This option optimizes the scheduler for common desktop workloads by
927 automatically creating and populating task groups. This separation
928 of workloads isolates aggressive CPU burners (like build jobs) from
929 desktop applications. Task group autogeneration is currently based
932 config SYSFS_DEPRECATED
933 bool "Enable deprecated sysfs features to support old userspace tools"
937 This option adds code that switches the layout of the "block" class
938 devices, to not show up in /sys/class/block/, but only in
941 This switch is only active when the sysfs.deprecated=1 boot option is
942 passed or the SYSFS_DEPRECATED_V2 option is set.
944 This option allows new kernels to run on old distributions and tools,
945 which might get confused by /sys/class/block/. Since 2007/2008 all
946 major distributions and tools handle this just fine.
948 Recent distributions and userspace tools after 2009/2010 depend on
949 the existence of /sys/class/block/, and will not work with this
952 Only if you are using a new kernel on an old distribution, you might
955 config SYSFS_DEPRECATED_V2
956 bool "Enable deprecated sysfs features by default"
959 depends on SYSFS_DEPRECATED
961 Enable deprecated sysfs by default.
963 See the CONFIG_SYSFS_DEPRECATED option for more details about this
966 Only if you are using a new kernel on an old distribution, you might
967 need to say Y here. Even then, odds are you would not need it
968 enabled, you can always pass the boot option if absolutely necessary.
971 bool "Kernel->user space relay support (formerly relayfs)"
974 This option enables support for relay interface support in
975 certain file systems (such as debugfs).
976 It is designed to provide an efficient mechanism for tools and
977 facilities to relay large amounts of data from kernel space to
982 config BLK_DEV_INITRD
983 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
985 The initial RAM filesystem is a ramfs which is loaded by the
986 boot loader (loadlin or lilo) and that is mounted as root
987 before the normal boot procedure. It is typically used to
988 load modules needed to mount the "real" root file system,
989 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
991 If RAM disk support (BLK_DEV_RAM) is also included, this
992 also enables initial RAM disk (initrd) support and adds
993 15 Kbytes (more on some other architectures) to the kernel size.
1004 prompt "Compiler optimization level"
1005 default CC_OPTIMIZE_FOR_PERFORMANCE
1007 config CC_OPTIMIZE_FOR_PERFORMANCE
1008 bool "Optimize for performance"
1010 This is the default optimization level for the kernel, building
1011 with the "-O2" compiler flag for best performance and most
1012 helpful compile-time warnings.
1014 config CC_OPTIMIZE_FOR_SIZE
1015 bool "Optimize for size"
1017 Enabling this option will pass "-Os" instead of "-O2" to
1018 your compiler resulting in a smaller kernel.
1024 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1027 This requires that the arch annotates or otherwise protects
1028 its external entry points from being discarded. Linker scripts
1029 must also merge .text.*, .data.*, and .bss.* correctly into
1030 output sections. Care must be taken not to pull in unrelated
1031 sections (e.g., '.text.init'). Typically '.' in section names
1032 is used to distinguish them from label names / C identifiers.
1034 config LD_DEAD_CODE_DATA_ELIMINATION
1035 bool "Dead code and data elimination (EXPERIMENTAL)"
1036 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1039 Select this if the architecture wants to do dead code and
1040 data elimination with the linker by compiling with
1041 -ffunction-sections -fdata-sections, and linking with
1044 This can reduce on disk and in-memory size of the kernel
1045 code and static data, particularly for small configs and
1046 on small systems. This has the possibility of introducing
1047 silently broken kernel if the required annotations are not
1048 present. This option is not well tested yet, so use at your
1060 config SYSCTL_EXCEPTION_TRACE
1063 Enable support for /proc/sys/debug/exception-trace.
1065 config SYSCTL_ARCH_UNALIGN_NO_WARN
1068 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1069 Allows arch to define/use @no_unaligned_warning to possibly warn
1070 about unaligned access emulation going on under the hood.
1072 config SYSCTL_ARCH_UNALIGN_ALLOW
1075 Enable support for /proc/sys/kernel/unaligned-trap
1076 Allows arches to define/use @unaligned_enabled to runtime toggle
1077 the unaligned access emulation.
1078 see arch/parisc/kernel/unaligned.c for reference
1080 config HAVE_PCSPKR_PLATFORM
1083 # interpreter that classic socket filters depend on
1088 bool "Configure standard kernel features (expert users)"
1089 # Unhide debug options, to make the on-by-default options visible
1092 This option allows certain base kernel options and settings
1093 to be disabled or tweaked. This is for specialized
1094 environments which can tolerate a "non-standard" kernel.
1095 Only use this if you really know what you are doing.
1098 bool "Enable 16-bit UID system calls" if EXPERT
1099 depends on HAVE_UID16 && MULTIUSER
1102 This enables the legacy 16-bit UID syscall wrappers.
1105 bool "Multiple users, groups and capabilities support" if EXPERT
1108 This option enables support for non-root users, groups and
1111 If you say N here, all processes will run with UID 0, GID 0, and all
1112 possible capabilities. Saying N here also compiles out support for
1113 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1116 If unsure, say Y here.
1118 config SGETMASK_SYSCALL
1119 bool "sgetmask/ssetmask syscalls support" if EXPERT
1120 def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1122 sys_sgetmask and sys_ssetmask are obsolete system calls
1123 no longer supported in libc but still enabled by default in some
1126 If unsure, leave the default option here.
1128 config SYSFS_SYSCALL
1129 bool "Sysfs syscall support" if EXPERT
1132 sys_sysfs is an obsolete system call no longer supported in libc.
1133 Note that disabling this option is more secure but might break
1134 compatibility with some systems.
1136 If unsure say Y here.
1138 config SYSCTL_SYSCALL
1139 bool "Sysctl syscall support" if EXPERT
1140 depends on PROC_SYSCTL
1144 sys_sysctl uses binary paths that have been found challenging
1145 to properly maintain and use. The interface in /proc/sys
1146 using paths with ascii names is now the primary path to this
1149 Almost nothing using the binary sysctl interface so if you are
1150 trying to save some space it is probably safe to disable this,
1151 making your kernel marginally smaller.
1153 If unsure say N here.
1156 bool "open by fhandle syscalls" if EXPERT
1160 If you say Y here, a user level program will be able to map
1161 file names to handle and then later use the handle for
1162 different file system operations. This is useful in implementing
1163 userspace file servers, which now track files using handles instead
1164 of names. The handle would remain the same even if file names
1165 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1169 bool "Posix Clocks & timers" if EXPERT
1172 This includes native support for POSIX timers to the kernel.
1173 Some embedded systems have no use for them and therefore they
1174 can be configured out to reduce the size of the kernel image.
1176 When this option is disabled, the following syscalls won't be
1177 available: timer_create, timer_gettime: timer_getoverrun,
1178 timer_settime, timer_delete, clock_adjtime, getitimer,
1179 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1180 clock_getres and clock_nanosleep syscalls will be limited to
1181 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1187 bool "Enable support for printk" if EXPERT
1190 This option enables normal printk support. Removing it
1191 eliminates most of the message strings from the kernel image
1192 and makes the kernel more or less silent. As this makes it
1193 very difficult to diagnose system problems, saying N here is
1194 strongly discouraged.
1202 bool "BUG() support" if EXPERT
1205 Disabling this option eliminates support for BUG and WARN, reducing
1206 the size of your kernel image and potentially quietly ignoring
1207 numerous fatal conditions. You should only consider disabling this
1208 option for embedded systems with no facilities for reporting errors.
1214 bool "Enable ELF core dumps" if EXPERT
1216 Enable support for generating core dumps. Disabling saves about 4k.
1219 config PCSPKR_PLATFORM
1220 bool "Enable PC-Speaker support" if EXPERT
1221 depends on HAVE_PCSPKR_PLATFORM
1225 This option allows to disable the internal PC-Speaker
1226 support, saving some memory.
1230 bool "Enable full-sized data structures for core" if EXPERT
1232 Disabling this option reduces the size of miscellaneous core
1233 kernel data structures. This saves memory on small machines,
1234 but may reduce performance.
1237 bool "Enable futex support" if EXPERT
1241 Disabling this option will cause the kernel to be built without
1242 support for "fast userspace mutexes". The resulting kernel may not
1243 run glibc-based applications correctly.
1247 depends on FUTEX && RT_MUTEXES
1250 config HAVE_FUTEX_CMPXCHG
1254 Architectures should select this if futex_atomic_cmpxchg_inatomic()
1255 is implemented and always working. This removes a couple of runtime
1259 bool "Enable eventpoll support" if EXPERT
1263 Disabling this option will cause the kernel to be built without
1264 support for epoll family of system calls.
1267 bool "Enable signalfd() system call" if EXPERT
1271 Enable the signalfd() system call that allows to receive signals
1272 on a file descriptor.
1277 bool "Enable timerfd() system call" if EXPERT
1281 Enable the timerfd() system call that allows to receive timer
1282 events on a file descriptor.
1287 bool "Enable eventfd() system call" if EXPERT
1291 Enable the eventfd() system call that allows to receive both
1292 kernel notification (ie. KAIO) or userspace notifications.
1297 bool "Use full shmem filesystem" if EXPERT
1301 The shmem is an internal filesystem used to manage shared memory.
1302 It is backed by swap and manages resource limits. It is also exported
1303 to userspace as tmpfs if TMPFS is enabled. Disabling this
1304 option replaces shmem and tmpfs with the much simpler ramfs code,
1305 which may be appropriate on small systems without swap.
1308 bool "Enable AIO support" if EXPERT
1311 This option enables POSIX asynchronous I/O which may by used
1312 by some high performance threaded applications. Disabling
1313 this option saves about 7k.
1315 config ADVISE_SYSCALLS
1316 bool "Enable madvise/fadvise syscalls" if EXPERT
1319 This option enables the madvise and fadvise syscalls, used by
1320 applications to advise the kernel about their future memory or file
1321 usage, improving performance. If building an embedded system where no
1322 applications use these syscalls, you can disable this option to save
1326 bool "Enable membarrier() system call" if EXPERT
1329 Enable the membarrier() system call that allows issuing memory
1330 barriers across all running threads, which can be used to distribute
1331 the cost of user-space memory barriers asymmetrically by transforming
1332 pairs of memory barriers into pairs consisting of membarrier() and a
1337 config CHECKPOINT_RESTORE
1338 bool "Checkpoint/restore support" if EXPERT
1339 select PROC_CHILDREN
1342 Enables additional kernel features in a sake of checkpoint/restore.
1343 In particular it adds auxiliary prctl codes to setup process text,
1344 data and heap segment sizes, and a few additional /proc filesystem
1347 If unsure, say N here.
1350 bool "Load all symbols for debugging/ksymoops" if EXPERT
1353 Say Y here to let the kernel print out symbolic crash information and
1354 symbolic stack backtraces. This increases the size of the kernel
1355 somewhat, as all symbols have to be loaded into the kernel image.
1358 bool "Include all symbols in kallsyms"
1359 depends on DEBUG_KERNEL && KALLSYMS
1361 Normally kallsyms only contains the symbols of functions for nicer
1362 OOPS messages and backtraces (i.e., symbols from the text and inittext
1363 sections). This is sufficient for most cases. And only in very rare
1364 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1365 names of variables from the data sections, etc).
1367 This option makes sure that all symbols are loaded into the kernel
1368 image (i.e., symbols from all sections) in cost of increased kernel
1369 size (depending on the kernel configuration, it may be 300KiB or
1370 something like this).
1372 Say N unless you really need all symbols.
1374 config KALLSYMS_ABSOLUTE_PERCPU
1377 default X86_64 && SMP
1379 config KALLSYMS_BASE_RELATIVE
1384 Instead of emitting them as absolute values in the native word size,
1385 emit the symbol references in the kallsyms table as 32-bit entries,
1386 each containing a relative value in the range [base, base + U32_MAX]
1387 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1388 an absolute value in the range [0, S32_MAX] or a relative value in the
1389 range [base, base + S32_MAX], where base is the lowest relative symbol
1390 address encountered in the image.
1392 On 64-bit builds, this reduces the size of the address table by 50%,
1393 but more importantly, it results in entries whose values are build
1394 time constants, and no relocation pass is required at runtime to fix
1395 up the entries based on the runtime load address of the kernel.
1397 # end of the "standard kernel features (expert users)" menu
1399 # syscall, maps, verifier
1401 bool "Enable bpf() system call"
1407 Enable the bpf() system call that allows to manipulate eBPF
1408 programs and maps via file descriptors.
1410 config BPF_JIT_ALWAYS_ON
1411 bool "Permanently enable BPF JIT and remove BPF interpreter"
1412 depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
1414 Enables BPF JIT and removes BPF interpreter to avoid
1415 speculative execution of BPF instructions by the interpreter
1418 bool "Enable userfaultfd() system call"
1422 Enable the userfaultfd() system call that allows to intercept and
1423 handle page faults in userland.
1425 config ARCH_HAS_MEMBARRIER_CALLBACKS
1428 config ARCH_HAS_MEMBARRIER_SYNC_CORE
1432 bool "Enable rseq() system call" if EXPERT
1434 depends on HAVE_RSEQ
1437 Enable the restartable sequences system call. It provides a
1438 user-space cache for the current CPU number value, which
1439 speeds up getting the current CPU number from user-space,
1440 as well as an ABI to speed up user-space operations on
1447 bool "Enabled debugging of rseq() system call" if EXPERT
1448 depends on RSEQ && DEBUG_KERNEL
1450 Enable extra debugging checks for the rseq system call.
1455 bool "Embedded system"
1456 option allnoconfig_y
1459 This option should be enabled if compiling the kernel for
1460 an embedded system so certain expert options are available
1463 config HAVE_PERF_EVENTS
1466 See tools/perf/design.txt for details.
1468 config PERF_USE_VMALLOC
1471 See tools/perf/design.txt for details
1474 bool "PC/104 support" if EXPERT
1476 Expose PC/104 form factor device drivers and options available for
1477 selection and configuration. Enable this option if your target
1478 machine has a PC/104 bus.
1480 menu "Kernel Performance Events And Counters"
1483 bool "Kernel performance events and counters"
1484 default y if PROFILING
1485 depends on HAVE_PERF_EVENTS
1490 Enable kernel support for various performance events provided
1491 by software and hardware.
1493 Software events are supported either built-in or via the
1494 use of generic tracepoints.
1496 Most modern CPUs support performance events via performance
1497 counter registers. These registers count the number of certain
1498 types of hw events: such as instructions executed, cachemisses
1499 suffered, or branches mis-predicted - without slowing down the
1500 kernel or applications. These registers can also trigger interrupts
1501 when a threshold number of events have passed - and can thus be
1502 used to profile the code that runs on that CPU.
1504 The Linux Performance Event subsystem provides an abstraction of
1505 these software and hardware event capabilities, available via a
1506 system call and used by the "perf" utility in tools/perf/. It
1507 provides per task and per CPU counters, and it provides event
1508 capabilities on top of those.
1512 config DEBUG_PERF_USE_VMALLOC
1514 bool "Debug: use vmalloc to back perf mmap() buffers"
1515 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1516 select PERF_USE_VMALLOC
1518 Use vmalloc memory to back perf mmap() buffers.
1520 Mostly useful for debugging the vmalloc code on platforms
1521 that don't require it.
1527 config VM_EVENT_COUNTERS
1529 bool "Enable VM event counters for /proc/vmstat" if EXPERT
1531 VM event counters are needed for event counts to be shown.
1532 This option allows the disabling of the VM event counters
1533 on EXPERT systems. /proc/vmstat will only show page counts
1534 if VM event counters are disabled.
1538 bool "Enable SLUB debugging support" if EXPERT
1539 depends on SLUB && SYSFS
1541 SLUB has extensive debug support features. Disabling these can
1542 result in significant savings in code size. This also disables
1543 SLUB sysfs support. /sys/slab will not exist and there will be
1544 no support for cache validation etc.
1546 config SLUB_MEMCG_SYSFS_ON
1548 bool "Enable memcg SLUB sysfs support by default" if EXPERT
1549 depends on SLUB && SYSFS && MEMCG
1551 SLUB creates a directory under /sys/kernel/slab for each
1552 allocation cache to host info and debug files. If memory
1553 cgroup is enabled, each cache can have per memory cgroup
1554 caches. SLUB can create the same sysfs directories for these
1555 caches under /sys/kernel/slab/CACHE/cgroup but it can lead
1556 to a very high number of debug files being created. This is
1557 controlled by slub_memcg_sysfs boot parameter and this
1558 config option determines the parameter's default value.
1561 bool "Disable heap randomization"
1564 Randomizing heap placement makes heap exploits harder, but it
1565 also breaks ancient binaries (including anything libc5 based).
1566 This option changes the bootup default to heap randomization
1567 disabled, and can be overridden at runtime by setting
1568 /proc/sys/kernel/randomize_va_space to 2.
1570 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1573 prompt "Choose SLAB allocator"
1576 This option allows to select a slab allocator.
1580 select HAVE_HARDENED_USERCOPY_ALLOCATOR
1582 The regular slab allocator that is established and known to work
1583 well in all environments. It organizes cache hot objects in
1584 per cpu and per node queues.
1587 bool "SLUB (Unqueued Allocator)"
1588 select HAVE_HARDENED_USERCOPY_ALLOCATOR
1590 SLUB is a slab allocator that minimizes cache line usage
1591 instead of managing queues of cached objects (SLAB approach).
1592 Per cpu caching is realized using slabs of objects instead
1593 of queues of objects. SLUB can use memory efficiently
1594 and has enhanced diagnostics. SLUB is the default choice for
1599 bool "SLOB (Simple Allocator)"
1601 SLOB replaces the stock allocator with a drastically simpler
1602 allocator. SLOB is generally more space efficient but
1603 does not perform as well on large systems.
1607 config SLAB_MERGE_DEFAULT
1608 bool "Allow slab caches to be merged"
1611 For reduced kernel memory fragmentation, slab caches can be
1612 merged when they share the same size and other characteristics.
1613 This carries a risk of kernel heap overflows being able to
1614 overwrite objects from merged caches (and more easily control
1615 cache layout), which makes such heap attacks easier to exploit
1616 by attackers. By keeping caches unmerged, these kinds of exploits
1617 can usually only damage objects in the same cache. To disable
1618 merging at runtime, "slab_nomerge" can be passed on the kernel
1621 config SLAB_FREELIST_RANDOM
1623 depends on SLAB || SLUB
1624 bool "SLAB freelist randomization"
1626 Randomizes the freelist order used on creating new pages. This
1627 security feature reduces the predictability of the kernel slab
1628 allocator against heap overflows.
1630 config SLAB_FREELIST_HARDENED
1631 bool "Harden slab freelist metadata"
1634 Many kernel heap attacks try to target slab cache metadata and
1635 other infrastructure. This options makes minor performance
1636 sacrifies to harden the kernel slab allocator against common
1637 freelist exploit methods.
1639 config SLUB_CPU_PARTIAL
1641 depends on SLUB && SMP
1642 bool "SLUB per cpu partial cache"
1644 Per cpu partial caches accellerate objects allocation and freeing
1645 that is local to a processor at the price of more indeterminism
1646 in the latency of the free. On overflow these caches will be cleared
1647 which requires the taking of locks that may cause latency spikes.
1648 Typically one would choose no for a realtime system.
1650 config MMAP_ALLOW_UNINITIALIZED
1651 bool "Allow mmapped anonymous memory to be uninitialized"
1652 depends on EXPERT && !MMU
1655 Normally, and according to the Linux spec, anonymous memory obtained
1656 from mmap() has it's contents cleared before it is passed to
1657 userspace. Enabling this config option allows you to request that
1658 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1659 providing a huge performance boost. If this option is not enabled,
1660 then the flag will be ignored.
1662 This is taken advantage of by uClibc's malloc(), and also by
1663 ELF-FDPIC binfmt's brk and stack allocator.
1665 Because of the obvious security issues, this option should only be
1666 enabled on embedded devices where you control what is run in
1667 userspace. Since that isn't generally a problem on no-MMU systems,
1668 it is normally safe to say Y here.
1670 See Documentation/nommu-mmap.txt for more information.
1672 config SYSTEM_DATA_VERIFICATION
1674 select SYSTEM_TRUSTED_KEYRING
1678 select ASYMMETRIC_KEY_TYPE
1679 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1682 select X509_CERTIFICATE_PARSER
1683 select PKCS7_MESSAGE_PARSER
1685 Provide PKCS#7 message verification using the contents of the system
1686 trusted keyring to provide public keys. This then can be used for
1687 module verification, kexec image verification and firmware blob
1691 bool "Profiling support"
1693 Say Y here to enable the extended profiling support mechanisms used
1694 by profilers such as OProfile.
1697 # Place an empty function call at each tracepoint site. Can be
1698 # dynamically changed for a probe function.
1703 source "arch/Kconfig"
1705 endmenu # General setup
1707 config HAVE_GENERIC_DMA_COHERENT
1716 default 0 if BASE_FULL
1717 default 1 if !BASE_FULL
1720 bool "Enable loadable module support"
1723 Kernel modules are small pieces of compiled code which can
1724 be inserted in the running kernel, rather than being
1725 permanently built into the kernel. You use the "modprobe"
1726 tool to add (and sometimes remove) them. If you say Y here,
1727 many parts of the kernel can be built as modules (by
1728 answering M instead of Y where indicated): this is most
1729 useful for infrequently used options which are not required
1730 for booting. For more information, see the man pages for
1731 modprobe, lsmod, modinfo, insmod and rmmod.
1733 If you say Y here, you will need to run "make
1734 modules_install" to put the modules under /lib/modules/
1735 where modprobe can find them (you may need to be root to do
1742 config MODULE_FORCE_LOAD
1743 bool "Forced module loading"
1746 Allow loading of modules without version information (ie. modprobe
1747 --force). Forced module loading sets the 'F' (forced) taint flag and
1748 is usually a really bad idea.
1750 config MODULE_UNLOAD
1751 bool "Module unloading"
1753 Without this option you will not be able to unload any
1754 modules (note that some modules may not be unloadable
1755 anyway), which makes your kernel smaller, faster
1756 and simpler. If unsure, say Y.
1758 config MODULE_FORCE_UNLOAD
1759 bool "Forced module unloading"
1760 depends on MODULE_UNLOAD
1762 This option allows you to force a module to unload, even if the
1763 kernel believes it is unsafe: the kernel will remove the module
1764 without waiting for anyone to stop using it (using the -f option to
1765 rmmod). This is mainly for kernel developers and desperate users.
1769 bool "Module versioning support"
1771 Usually, you have to use modules compiled with your kernel.
1772 Saying Y here makes it sometimes possible to use modules
1773 compiled for different kernels, by adding enough information
1774 to the modules to (hopefully) spot any changes which would
1775 make them incompatible with the kernel you are running. If
1778 config MODULE_REL_CRCS
1780 depends on MODVERSIONS
1782 config MODULE_SRCVERSION_ALL
1783 bool "Source checksum for all modules"
1785 Modules which contain a MODULE_VERSION get an extra "srcversion"
1786 field inserted into their modinfo section, which contains a
1787 sum of the source files which made it. This helps maintainers
1788 see exactly which source was used to build a module (since
1789 others sometimes change the module source without updating
1790 the version). With this option, such a "srcversion" field
1791 will be created for all modules. If unsure, say N.
1794 bool "Module signature verification"
1796 select SYSTEM_DATA_VERIFICATION
1798 Check modules for valid signatures upon load: the signature
1799 is simply appended to the module. For more information see
1800 <file:Documentation/admin-guide/module-signing.rst>.
1802 Note that this option adds the OpenSSL development packages as a
1803 kernel build dependency so that the signing tool can use its crypto
1806 !!!WARNING!!! If you enable this option, you MUST make sure that the
1807 module DOES NOT get stripped after being signed. This includes the
1808 debuginfo strip done by some packagers (such as rpmbuild) and
1809 inclusion into an initramfs that wants the module size reduced.
1811 config MODULE_SIG_FORCE
1812 bool "Require modules to be validly signed"
1813 depends on MODULE_SIG
1815 Reject unsigned modules or signed modules for which we don't have a
1816 key. Without this, such modules will simply taint the kernel.
1818 config MODULE_SIG_ALL
1819 bool "Automatically sign all modules"
1821 depends on MODULE_SIG
1823 Sign all modules during make modules_install. Without this option,
1824 modules must be signed manually, using the scripts/sign-file tool.
1826 comment "Do not forget to sign required modules with scripts/sign-file"
1827 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
1830 prompt "Which hash algorithm should modules be signed with?"
1831 depends on MODULE_SIG
1833 This determines which sort of hashing algorithm will be used during
1834 signature generation. This algorithm _must_ be built into the kernel
1835 directly so that signature verification can take place. It is not
1836 possible to load a signed module containing the algorithm to check
1837 the signature on that module.
1839 config MODULE_SIG_SHA1
1840 bool "Sign modules with SHA-1"
1843 config MODULE_SIG_SHA224
1844 bool "Sign modules with SHA-224"
1845 select CRYPTO_SHA256
1847 config MODULE_SIG_SHA256
1848 bool "Sign modules with SHA-256"
1849 select CRYPTO_SHA256
1851 config MODULE_SIG_SHA384
1852 bool "Sign modules with SHA-384"
1853 select CRYPTO_SHA512
1855 config MODULE_SIG_SHA512
1856 bool "Sign modules with SHA-512"
1857 select CRYPTO_SHA512
1861 config MODULE_SIG_HASH
1863 depends on MODULE_SIG
1864 default "sha1" if MODULE_SIG_SHA1
1865 default "sha224" if MODULE_SIG_SHA224
1866 default "sha256" if MODULE_SIG_SHA256
1867 default "sha384" if MODULE_SIG_SHA384
1868 default "sha512" if MODULE_SIG_SHA512
1870 config MODULE_COMPRESS
1871 bool "Compress modules on installation"
1875 Compresses kernel modules when 'make modules_install' is run; gzip or
1876 xz depending on "Compression algorithm" below.
1878 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
1880 Out-of-tree kernel modules installed using Kbuild will also be
1881 compressed upon installation.
1883 Note: for modules inside an initrd or initramfs, it's more efficient
1884 to compress the whole initrd or initramfs instead.
1886 Note: This is fully compatible with signed modules.
1891 prompt "Compression algorithm"
1892 depends on MODULE_COMPRESS
1893 default MODULE_COMPRESS_GZIP
1895 This determines which sort of compression will be used during
1896 'make modules_install'.
1898 GZIP (default) and XZ are supported.
1900 config MODULE_COMPRESS_GZIP
1903 config MODULE_COMPRESS_XZ
1908 config TRIM_UNUSED_KSYMS
1909 bool "Trim unused exported kernel symbols"
1910 depends on MODULES && !UNUSED_SYMBOLS
1912 The kernel and some modules make many symbols available for
1913 other modules to use via EXPORT_SYMBOL() and variants. Depending
1914 on the set of modules being selected in your kernel configuration,
1915 many of those exported symbols might never be used.
1917 This option allows for unused exported symbols to be dropped from
1918 the build. In turn, this provides the compiler more opportunities
1919 (especially when using LTO) for optimizing the code and reducing
1920 binary size. This might have some security advantages as well.
1922 If unsure, or if you need to build out-of-tree modules, say N.
1926 config MODULES_TREE_LOOKUP
1928 depends on PERF_EVENTS || TRACING
1930 config INIT_ALL_POSSIBLE
1933 Back when each arch used to define their own cpu_online_mask and
1934 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
1935 with all 1s, and others with all 0s. When they were centralised,
1936 it was better to provide this option than to break all the archs
1937 and have several arch maintainers pursuing me down dark alleys.
1939 source "block/Kconfig"
1941 config PREEMPT_NOTIFIERS
1951 Build a simple ASN.1 grammar compiler that produces a bytecode output
1952 that can be interpreted by the ASN.1 stream decoder and used to
1953 inform it as to what tags are to be expected in a stream and what
1954 functions to call on what tags.
1956 source "kernel/Kconfig.locks"
1958 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
1961 # It may be useful for an architecture to override the definitions of the
1962 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
1963 # and the COMPAT_ variants in <linux/compat.h>, in particular to use a
1964 # different calling convention for syscalls. They can also override the
1965 # macros for not-implemented syscalls in kernel/sys_ni.c and
1966 # kernel/time/posix-stubs.c. All these overrides need to be available in
1967 # <asm/syscall_wrapper.h>.
1968 config ARCH_HAS_SYSCALL_WRAPPER
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