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))
33 config BUILDTIME_EXTABLE_SORT
36 config THREAD_INFO_IN_TASK
39 Select this to move thread_info off the stack into task_struct. To
40 make this work, an arch will need to remove all thread_info fields
41 except flags and fix any runtime bugs.
43 One subtle change that will be needed is to use try_get_task_stack()
44 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
53 depends on BROKEN || !SMP
56 config INIT_ENV_ARG_LIMIT
61 Maximum of each of the number of arguments and environment
62 variables passed to init from the kernel command line.
65 bool "Compile also drivers which will not load"
69 Some drivers can be compiled on a different platform than they are
70 intended to be run on. Despite they cannot be loaded there (or even
71 when they load they cannot be used due to missing HW support),
72 developers still, opposing to distributors, might want to build such
73 drivers to compile-test them.
75 If you are a developer and want to build everything available, say Y
76 here. If you are a user/distributor, say N here to exclude useless
77 drivers to be distributed.
80 string "Local version - append to kernel release"
82 Append an extra string to the end of your kernel version.
83 This will show up when you type uname, for example.
84 The string you set here will be appended after the contents of
85 any files with a filename matching localversion* in your
86 object and source tree, in that order. Your total string can
87 be a maximum of 64 characters.
89 config LOCALVERSION_AUTO
90 bool "Automatically append version information to the version string"
92 depends on !COMPILE_TEST
94 This will try to automatically determine if the current tree is a
95 release tree by looking for git tags that belong to the current
98 A string of the format -gxxxxxxxx will be added to the localversion
99 if a git-based tree is found. The string generated by this will be
100 appended after any matching localversion* files, and after the value
101 set in CONFIG_LOCALVERSION.
103 (The actual string used here is the first eight characters produced
104 by running the command:
106 $ git rev-parse --verify HEAD
108 which is done within the script "scripts/setlocalversion".)
111 string "Build ID Salt"
114 The build ID is used to link binaries and their debug info. Setting
115 this option will use the value in the calculation of the build id.
116 This is mostly useful for distributions which want to ensure the
117 build is unique between builds. It's safe to leave the default.
119 config HAVE_KERNEL_GZIP
122 config HAVE_KERNEL_BZIP2
125 config HAVE_KERNEL_LZMA
128 config HAVE_KERNEL_XZ
131 config HAVE_KERNEL_LZO
134 config HAVE_KERNEL_LZ4
137 config HAVE_KERNEL_UNCOMPRESSED
141 prompt "Kernel compression mode"
143 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 || HAVE_KERNEL_UNCOMPRESSED
145 The linux kernel is a kind of self-extracting executable.
146 Several compression algorithms are available, which differ
147 in efficiency, compression and decompression speed.
148 Compression speed is only relevant when building a kernel.
149 Decompression speed is relevant at each boot.
151 If you have any problems with bzip2 or lzma compressed
152 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
153 version of this functionality (bzip2 only), for 2.4, was
154 supplied by Christian Ludwig)
156 High compression options are mostly useful for users, who
157 are low on disk space (embedded systems), but for whom ram
160 If in doubt, select 'gzip'
164 depends on HAVE_KERNEL_GZIP
166 The old and tried gzip compression. It provides a good balance
167 between compression ratio and decompression speed.
171 depends on HAVE_KERNEL_BZIP2
173 Its compression ratio and speed is intermediate.
174 Decompression speed is slowest among the choices. The kernel
175 size is about 10% smaller with bzip2, in comparison to gzip.
176 Bzip2 uses a large amount of memory. For modern kernels you
177 will need at least 8MB RAM or more for booting.
181 depends on HAVE_KERNEL_LZMA
183 This compression algorithm's ratio is best. Decompression speed
184 is between gzip and bzip2. Compression is slowest.
185 The kernel size is about 33% smaller with LZMA in comparison to gzip.
189 depends on HAVE_KERNEL_XZ
191 XZ uses the LZMA2 algorithm and instruction set specific
192 BCJ filters which can improve compression ratio of executable
193 code. The size of the kernel is about 30% smaller with XZ in
194 comparison to gzip. On architectures for which there is a BCJ
195 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
196 will create a few percent smaller kernel than plain LZMA.
198 The speed is about the same as with LZMA: The decompression
199 speed of XZ is better than that of bzip2 but worse than gzip
200 and LZO. Compression is slow.
204 depends on HAVE_KERNEL_LZO
206 Its compression ratio is the poorest among the choices. The kernel
207 size is about 10% bigger than gzip; however its speed
208 (both compression and decompression) is the fastest.
212 depends on HAVE_KERNEL_LZ4
214 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
215 A preliminary version of LZ4 de/compression tool is available at
216 <https://code.google.com/p/lz4/>.
218 Its compression ratio is worse than LZO. The size of the kernel
219 is about 8% bigger than LZO. But the decompression speed is
222 config KERNEL_UNCOMPRESSED
224 depends on HAVE_KERNEL_UNCOMPRESSED
226 Produce uncompressed kernel image. This option is usually not what
227 you want. It is useful for debugging the kernel in slow simulation
228 environments, where decompressing and moving the kernel is awfully
229 slow. This option allows early boot code to skip the decompressor
230 and jump right at uncompressed kernel image.
234 config DEFAULT_HOSTNAME
235 string "Default hostname"
238 This option determines the default system hostname before userspace
239 calls sethostname(2). The kernel traditionally uses "(none)" here,
240 but you may wish to use a different default here to make a minimal
241 system more usable with less configuration.
244 # For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can
245 # add proper SWAP support to them, in which case this can be remove.
251 bool "Support for paging of anonymous memory (swap)"
252 depends on MMU && BLOCK && !ARCH_NO_SWAP
255 This option allows you to choose whether you want to have support
256 for so called swap devices or swap files in your kernel that are
257 used to provide more virtual memory than the actual RAM present
258 in your computer. If unsure say Y.
263 Inter Process Communication is a suite of library functions and
264 system calls which let processes (running programs) synchronize and
265 exchange information. It is generally considered to be a good thing,
266 and some programs won't run unless you say Y here. In particular, if
267 you want to run the DOS emulator dosemu under Linux (read the
268 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
269 you'll need to say Y here.
271 You can find documentation about IPC with "info ipc" and also in
272 section 6.4 of the Linux Programmer's Guide, available from
273 <http://www.tldp.org/guides.html>.
275 config SYSVIPC_SYSCTL
282 bool "POSIX Message Queues"
285 POSIX variant of message queues is a part of IPC. In POSIX message
286 queues every message has a priority which decides about succession
287 of receiving it by a process. If you want to compile and run
288 programs written e.g. for Solaris with use of its POSIX message
289 queues (functions mq_*) say Y here.
291 POSIX message queues are visible as a filesystem called 'mqueue'
292 and can be mounted somewhere if you want to do filesystem
293 operations on message queues.
297 config POSIX_MQUEUE_SYSCTL
299 depends on POSIX_MQUEUE
303 config CROSS_MEMORY_ATTACH
304 bool "Enable process_vm_readv/writev syscalls"
308 Enabling this option adds the system calls process_vm_readv and
309 process_vm_writev which allow a process with the correct privileges
310 to directly read from or write to another process' address space.
311 See the man page for more details.
314 bool "uselib syscall"
315 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
317 This option enables the uselib syscall, a system call used in the
318 dynamic linker from libc5 and earlier. glibc does not use this
319 system call. If you intend to run programs built on libc5 or
320 earlier, you may need to enable this syscall. Current systems
321 running glibc can safely disable this.
324 bool "Auditing support"
327 Enable auditing infrastructure that can be used with another
328 kernel subsystem, such as SELinux (which requires this for
329 logging of avc messages output). System call auditing is included
330 on architectures which support it.
332 config HAVE_ARCH_AUDITSYSCALL
337 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
341 depends on AUDITSYSCALL
346 depends on AUDITSYSCALL
349 source "kernel/irq/Kconfig"
350 source "kernel/time/Kconfig"
351 source "kernel/Kconfig.preempt"
353 menu "CPU/Task time and stats accounting"
355 config VIRT_CPU_ACCOUNTING
359 prompt "Cputime accounting"
360 default TICK_CPU_ACCOUNTING if !PPC64
361 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
363 # Kind of a stub config for the pure tick based cputime accounting
364 config TICK_CPU_ACCOUNTING
365 bool "Simple tick based cputime accounting"
366 depends on !S390 && !NO_HZ_FULL
368 This is the basic tick based cputime accounting that maintains
369 statistics about user, system and idle time spent on per jiffies
374 config VIRT_CPU_ACCOUNTING_NATIVE
375 bool "Deterministic task and CPU time accounting"
376 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
377 select VIRT_CPU_ACCOUNTING
379 Select this option to enable more accurate task and CPU time
380 accounting. This is done by reading a CPU counter on each
381 kernel entry and exit and on transitions within the kernel
382 between system, softirq and hardirq state, so there is a
383 small performance impact. In the case of s390 or IBM POWER > 5,
384 this also enables accounting of stolen time on logically-partitioned
387 config VIRT_CPU_ACCOUNTING_GEN
388 bool "Full dynticks CPU time accounting"
389 depends on HAVE_CONTEXT_TRACKING
390 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
391 select VIRT_CPU_ACCOUNTING
392 select CONTEXT_TRACKING
394 Select this option to enable task and CPU time accounting on full
395 dynticks systems. This accounting is implemented by watching every
396 kernel-user boundaries using the context tracking subsystem.
397 The accounting is thus performed at the expense of some significant
400 For now this is only useful if you are working on the full
401 dynticks subsystem development.
407 config IRQ_TIME_ACCOUNTING
408 bool "Fine granularity task level IRQ time accounting"
409 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
411 Select this option to enable fine granularity task irq time
412 accounting. This is done by reading a timestamp on each
413 transitions between softirq and hardirq state, so there can be a
414 small performance impact.
416 If in doubt, say N here.
418 config HAVE_SCHED_AVG_IRQ
420 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
423 config BSD_PROCESS_ACCT
424 bool "BSD Process Accounting"
427 If you say Y here, a user level program will be able to instruct the
428 kernel (via a special system call) to write process accounting
429 information to a file: whenever a process exits, information about
430 that process will be appended to the file by the kernel. The
431 information includes things such as creation time, owning user,
432 command name, memory usage, controlling terminal etc. (the complete
433 list is in the struct acct in <file:include/linux/acct.h>). It is
434 up to the user level program to do useful things with this
435 information. This is generally a good idea, so say Y.
437 config BSD_PROCESS_ACCT_V3
438 bool "BSD Process Accounting version 3 file format"
439 depends on BSD_PROCESS_ACCT
442 If you say Y here, the process accounting information is written
443 in a new file format that also logs the process IDs of each
444 process and its parent. Note that this file format is incompatible
445 with previous v0/v1/v2 file formats, so you will need updated tools
446 for processing it. A preliminary version of these tools is available
447 at <http://www.gnu.org/software/acct/>.
450 bool "Export task/process statistics through netlink"
455 Export selected statistics for tasks/processes through the
456 generic netlink interface. Unlike BSD process accounting, the
457 statistics are available during the lifetime of tasks/processes as
458 responses to commands. Like BSD accounting, they are sent to user
463 config TASK_DELAY_ACCT
464 bool "Enable per-task delay accounting"
468 Collect information on time spent by a task waiting for system
469 resources like cpu, synchronous block I/O completion and swapping
470 in pages. Such statistics can help in setting a task's priorities
471 relative to other tasks for cpu, io, rss limits etc.
476 bool "Enable extended accounting over taskstats"
479 Collect extended task accounting data and send the data
480 to userland for processing over the taskstats interface.
484 config TASK_IO_ACCOUNTING
485 bool "Enable per-task storage I/O accounting"
486 depends on TASK_XACCT
488 Collect information on the number of bytes of storage I/O which this
494 bool "Pressure stall information tracking"
496 Collect metrics that indicate how overcommitted the CPU, memory,
497 and IO capacity are in the system.
499 If you say Y here, the kernel will create /proc/pressure/ with the
500 pressure statistics files cpu, memory, and io. These will indicate
501 the share of walltime in which some or all tasks in the system are
502 delayed due to contention of the respective resource.
504 In kernels with cgroup support, cgroups (cgroup2 only) will
505 have cpu.pressure, memory.pressure, and io.pressure files,
506 which aggregate pressure stalls for the grouped tasks only.
508 For more details see Documentation/accounting/psi.txt.
512 endmenu # "CPU/Task time and stats accounting"
516 depends on SMP || COMPILE_TEST
519 Make sure that CPUs running critical tasks are not disturbed by
520 any source of "noise" such as unbound workqueues, timers, kthreads...
521 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
522 the "isolcpus=" boot parameter.
526 source "kernel/rcu/Kconfig"
533 tristate "Kernel .config support"
536 This option enables the complete Linux kernel ".config" file
537 contents to be saved in the kernel. It provides documentation
538 of which kernel options are used in a running kernel or in an
539 on-disk kernel. This information can be extracted from the kernel
540 image file with the script scripts/extract-ikconfig and used as
541 input to rebuild the current kernel or to build another kernel.
542 It can also be extracted from a running kernel by reading
543 /proc/config.gz if enabled (below).
546 bool "Enable access to .config through /proc/config.gz"
547 depends on IKCONFIG && PROC_FS
549 This option enables access to the kernel configuration file
550 through /proc/config.gz.
553 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
558 Select the minimal kernel log buffer size as a power of 2.
559 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
560 parameter, see below. Any higher size also might be forced
561 by "log_buf_len" boot parameter.
571 config LOG_CPU_MAX_BUF_SHIFT
572 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
575 default 12 if !BASE_SMALL
576 default 0 if BASE_SMALL
579 This option allows to increase the default ring buffer size
580 according to the number of CPUs. The value defines the contribution
581 of each CPU as a power of 2. The used space is typically only few
582 lines however it might be much more when problems are reported,
585 The increased size means that a new buffer has to be allocated and
586 the original static one is unused. It makes sense only on systems
587 with more CPUs. Therefore this value is used only when the sum of
588 contributions is greater than the half of the default kernel ring
589 buffer as defined by LOG_BUF_SHIFT. The default values are set
590 so that more than 64 CPUs are needed to trigger the allocation.
592 Also this option is ignored when "log_buf_len" kernel parameter is
593 used as it forces an exact (power of two) size of the ring buffer.
595 The number of possible CPUs is used for this computation ignoring
596 hotplugging making the computation optimal for the worst case
597 scenario while allowing a simple algorithm to be used from bootup.
599 Examples shift values and their meaning:
600 17 => 128 KB for each CPU
601 16 => 64 KB for each CPU
602 15 => 32 KB for each CPU
603 14 => 16 KB for each CPU
604 13 => 8 KB for each CPU
605 12 => 4 KB for each CPU
607 config PRINTK_SAFE_LOG_BUF_SHIFT
608 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
613 Select the size of an alternate printk per-CPU buffer where messages
614 printed from usafe contexts are temporary stored. One example would
615 be NMI messages, another one - printk recursion. The messages are
616 copied to the main log buffer in a safe context to avoid a deadlock.
617 The value defines the size as a power of 2.
619 Those messages are rare and limited. The largest one is when
620 a backtrace is printed. It usually fits into 4KB. Select
621 8KB if you want to be on the safe side.
624 17 => 128 KB for each CPU
625 16 => 64 KB for each CPU
626 15 => 32 KB for each CPU
627 14 => 16 KB for each CPU
628 13 => 8 KB for each CPU
629 12 => 4 KB for each CPU
632 # Architectures with an unreliable sched_clock() should select this:
634 config HAVE_UNSTABLE_SCHED_CLOCK
637 config GENERIC_SCHED_CLOCK
641 # For architectures that want to enable the support for NUMA-affine scheduler
644 config ARCH_SUPPORTS_NUMA_BALANCING
648 # For architectures that prefer to flush all TLBs after a number of pages
649 # are unmapped instead of sending one IPI per page to flush. The architecture
650 # must provide guarantees on what happens if a clean TLB cache entry is
651 # written after the unmap. Details are in mm/rmap.c near the check for
652 # should_defer_flush. The architecture should also consider if the full flush
653 # and the refill costs are offset by the savings of sending fewer IPIs.
654 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
658 # For architectures that know their GCC __int128 support is sound
660 config ARCH_SUPPORTS_INT128
663 # For architectures that (ab)use NUMA to represent different memory regions
664 # all cpu-local but of different latencies, such as SuperH.
666 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
669 config NUMA_BALANCING
670 bool "Memory placement aware NUMA scheduler"
671 depends on ARCH_SUPPORTS_NUMA_BALANCING
672 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
673 depends on SMP && NUMA && MIGRATION
675 This option adds support for automatic NUMA aware memory/task placement.
676 The mechanism is quite primitive and is based on migrating memory when
677 it has references to the node the task is running on.
679 This system will be inactive on UMA systems.
681 config NUMA_BALANCING_DEFAULT_ENABLED
682 bool "Automatically enable NUMA aware memory/task placement"
684 depends on NUMA_BALANCING
686 If set, automatic NUMA balancing will be enabled if running on a NUMA
690 bool "Control Group support"
693 This option adds support for grouping sets of processes together, for
694 use with process control subsystems such as Cpusets, CFS, memory
695 controls or device isolation.
697 - Documentation/scheduler/sched-design-CFS.txt (CFS)
698 - Documentation/cgroup-v1/ (features for grouping, isolation
699 and resource control)
709 bool "Memory controller"
713 Provides control over the memory footprint of tasks in a cgroup.
716 bool "Swap controller"
717 depends on MEMCG && SWAP
719 Provides control over the swap space consumed by tasks in a cgroup.
721 config MEMCG_SWAP_ENABLED
722 bool "Swap controller enabled by default"
723 depends on MEMCG_SWAP
726 Memory Resource Controller Swap Extension comes with its price in
727 a bigger memory consumption. General purpose distribution kernels
728 which want to enable the feature but keep it disabled by default
729 and let the user enable it by swapaccount=1 boot command line
730 parameter should have this option unselected.
731 For those who want to have the feature enabled by default should
732 select this option (if, for some reason, they need to disable it
733 then swapaccount=0 does the trick).
737 depends on MEMCG && !SLOB
745 Generic block IO controller cgroup interface. This is the common
746 cgroup interface which should be used by various IO controlling
749 Currently, CFQ IO scheduler uses it to recognize task groups and
750 control disk bandwidth allocation (proportional time slice allocation)
751 to such task groups. It is also used by bio throttling logic in
752 block layer to implement upper limit in IO rates on a device.
754 This option only enables generic Block IO controller infrastructure.
755 One needs to also enable actual IO controlling logic/policy. For
756 enabling proportional weight division of disk bandwidth in CFQ, set
757 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
758 CONFIG_BLK_DEV_THROTTLING=y.
760 See Documentation/cgroup-v1/blkio-controller.txt for more information.
762 config DEBUG_BLK_CGROUP
763 bool "IO controller debugging"
764 depends on BLK_CGROUP
767 Enable some debugging help. Currently it exports additional stat
768 files in a cgroup which can be useful for debugging.
770 config CGROUP_WRITEBACK
772 depends on MEMCG && BLK_CGROUP
775 menuconfig CGROUP_SCHED
776 bool "CPU controller"
779 This feature lets CPU scheduler recognize task groups and control CPU
780 bandwidth allocation to such task groups. It uses cgroups to group
784 config FAIR_GROUP_SCHED
785 bool "Group scheduling for SCHED_OTHER"
786 depends on CGROUP_SCHED
790 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
791 depends on FAIR_GROUP_SCHED
794 This option allows users to define CPU bandwidth rates (limits) for
795 tasks running within the fair group scheduler. Groups with no limit
796 set are considered to be unconstrained and will run with no
798 See Documentation/scheduler/sched-bwc.txt for more information.
800 config RT_GROUP_SCHED
801 bool "Group scheduling for SCHED_RR/FIFO"
802 depends on CGROUP_SCHED
805 This feature lets you explicitly allocate real CPU bandwidth
806 to task groups. If enabled, it will also make it impossible to
807 schedule realtime tasks for non-root users until you allocate
808 realtime bandwidth for them.
809 See Documentation/scheduler/sched-rt-group.txt for more information.
814 bool "PIDs controller"
816 Provides enforcement of process number limits in the scope of a
817 cgroup. Any attempt to fork more processes than is allowed in the
818 cgroup will fail. PIDs are fundamentally a global resource because it
819 is fairly trivial to reach PID exhaustion before you reach even a
820 conservative kmemcg limit. As a result, it is possible to grind a
821 system to halt without being limited by other cgroup policies. The
822 PIDs controller is designed to stop this from happening.
824 It should be noted that organisational operations (such as attaching
825 to a cgroup hierarchy will *not* be blocked by the PIDs controller),
826 since the PIDs limit only affects a process's ability to fork, not to
830 bool "RDMA controller"
832 Provides enforcement of RDMA resources defined by IB stack.
833 It is fairly easy for consumers to exhaust RDMA resources, which
834 can result into resource unavailability to other consumers.
835 RDMA controller is designed to stop this from happening.
836 Attaching processes with active RDMA resources to the cgroup
837 hierarchy is allowed even if can cross the hierarchy's limit.
839 config CGROUP_FREEZER
840 bool "Freezer controller"
842 Provides a way to freeze and unfreeze all tasks in a
845 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
846 controller includes important in-kernel memory consumers per default.
848 If you're using cgroup2, say N.
850 config CGROUP_HUGETLB
851 bool "HugeTLB controller"
852 depends on HUGETLB_PAGE
856 Provides a cgroup controller for HugeTLB pages.
857 When you enable this, you can put a per cgroup limit on HugeTLB usage.
858 The limit is enforced during page fault. Since HugeTLB doesn't
859 support page reclaim, enforcing the limit at page fault time implies
860 that, the application will get SIGBUS signal if it tries to access
861 HugeTLB pages beyond its limit. This requires the application to know
862 beforehand how much HugeTLB pages it would require for its use. The
863 control group is tracked in the third page lru pointer. This means
864 that we cannot use the controller with huge page less than 3 pages.
867 bool "Cpuset controller"
870 This option will let you create and manage CPUSETs which
871 allow dynamically partitioning a system into sets of CPUs and
872 Memory Nodes and assigning tasks to run only within those sets.
873 This is primarily useful on large SMP or NUMA systems.
877 config PROC_PID_CPUSET
878 bool "Include legacy /proc/<pid>/cpuset file"
883 bool "Device controller"
885 Provides a cgroup controller implementing whitelists for
886 devices which a process in the cgroup can mknod or open.
888 config CGROUP_CPUACCT
889 bool "Simple CPU accounting controller"
891 Provides a simple controller for monitoring the
892 total CPU consumed by the tasks in a cgroup.
895 bool "Perf controller"
896 depends on PERF_EVENTS
898 This option extends the perf per-cpu mode to restrict monitoring
899 to threads which belong to the cgroup specified and run on the
905 bool "Support for eBPF programs attached to cgroups"
906 depends on BPF_SYSCALL
907 select SOCK_CGROUP_DATA
909 Allow attaching eBPF programs to a cgroup using the bpf(2)
910 syscall command BPF_PROG_ATTACH.
912 In which context these programs are accessed depends on the type
913 of attachment. For instance, programs that are attached using
914 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
918 bool "Debug controller"
920 depends on DEBUG_KERNEL
922 This option enables a simple controller that exports
923 debugging information about the cgroups framework. This
924 controller is for control cgroup debugging only. Its
925 interfaces are not stable.
929 config SOCK_CGROUP_DATA
935 menuconfig NAMESPACES
936 bool "Namespaces support" if EXPERT
940 Provides the way to make tasks work with different objects using
941 the same id. For example same IPC id may refer to different objects
942 or same user id or pid may refer to different tasks when used in
943 different namespaces.
951 In this namespace tasks see different info provided with the
956 depends on (SYSVIPC || POSIX_MQUEUE)
959 In this namespace tasks work with IPC ids which correspond to
960 different IPC objects in different namespaces.
963 bool "User namespace"
966 This allows containers, i.e. vservers, to use user namespaces
967 to provide different user info for different servers.
969 When user namespaces are enabled in the kernel it is
970 recommended that the MEMCG option also be enabled and that
971 user-space use the memory control groups to limit the amount
972 of memory a memory unprivileged users can use.
977 bool "PID Namespaces"
980 Support process id namespaces. This allows having multiple
981 processes with the same pid as long as they are in different
982 pid namespaces. This is a building block of containers.
985 bool "Network namespace"
989 Allow user space to create what appear to be multiple instances
990 of the network stack.
994 config CHECKPOINT_RESTORE
995 bool "Checkpoint/restore support"
999 Enables additional kernel features in a sake of checkpoint/restore.
1000 In particular it adds auxiliary prctl codes to setup process text,
1001 data and heap segment sizes, and a few additional /proc filesystem
1004 If unsure, say N here.
1006 config SCHED_AUTOGROUP
1007 bool "Automatic process group scheduling"
1010 select FAIR_GROUP_SCHED
1012 This option optimizes the scheduler for common desktop workloads by
1013 automatically creating and populating task groups. This separation
1014 of workloads isolates aggressive CPU burners (like build jobs) from
1015 desktop applications. Task group autogeneration is currently based
1018 config SYSFS_DEPRECATED
1019 bool "Enable deprecated sysfs features to support old userspace tools"
1023 This option adds code that switches the layout of the "block" class
1024 devices, to not show up in /sys/class/block/, but only in
1027 This switch is only active when the sysfs.deprecated=1 boot option is
1028 passed or the SYSFS_DEPRECATED_V2 option is set.
1030 This option allows new kernels to run on old distributions and tools,
1031 which might get confused by /sys/class/block/. Since 2007/2008 all
1032 major distributions and tools handle this just fine.
1034 Recent distributions and userspace tools after 2009/2010 depend on
1035 the existence of /sys/class/block/, and will not work with this
1038 Only if you are using a new kernel on an old distribution, you might
1041 config SYSFS_DEPRECATED_V2
1042 bool "Enable deprecated sysfs features by default"
1045 depends on SYSFS_DEPRECATED
1047 Enable deprecated sysfs by default.
1049 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1052 Only if you are using a new kernel on an old distribution, you might
1053 need to say Y here. Even then, odds are you would not need it
1054 enabled, you can always pass the boot option if absolutely necessary.
1057 bool "Kernel->user space relay support (formerly relayfs)"
1060 This option enables support for relay interface support in
1061 certain file systems (such as debugfs).
1062 It is designed to provide an efficient mechanism for tools and
1063 facilities to relay large amounts of data from kernel space to
1068 config BLK_DEV_INITRD
1069 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1071 The initial RAM filesystem is a ramfs which is loaded by the
1072 boot loader (loadlin or lilo) and that is mounted as root
1073 before the normal boot procedure. It is typically used to
1074 load modules needed to mount the "real" root file system,
1075 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1077 If RAM disk support (BLK_DEV_RAM) is also included, this
1078 also enables initial RAM disk (initrd) support and adds
1079 15 Kbytes (more on some other architectures) to the kernel size.
1085 source "usr/Kconfig"
1090 prompt "Compiler optimization level"
1091 default CC_OPTIMIZE_FOR_PERFORMANCE
1093 config CC_OPTIMIZE_FOR_PERFORMANCE
1094 bool "Optimize for performance"
1096 This is the default optimization level for the kernel, building
1097 with the "-O2" compiler flag for best performance and most
1098 helpful compile-time warnings.
1100 config CC_OPTIMIZE_FOR_SIZE
1101 bool "Optimize for size"
1103 Enabling this option will pass "-Os" instead of "-O2" to
1104 your compiler resulting in a smaller kernel.
1110 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1113 This requires that the arch annotates or otherwise protects
1114 its external entry points from being discarded. Linker scripts
1115 must also merge .text.*, .data.*, and .bss.* correctly into
1116 output sections. Care must be taken not to pull in unrelated
1117 sections (e.g., '.text.init'). Typically '.' in section names
1118 is used to distinguish them from label names / C identifiers.
1120 config LD_DEAD_CODE_DATA_ELIMINATION
1121 bool "Dead code and data elimination (EXPERIMENTAL)"
1122 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1124 depends on $(cc-option,-ffunction-sections -fdata-sections)
1125 depends on $(ld-option,--gc-sections)
1127 Enable this if you want to do dead code and data elimination with
1128 the linker by compiling with -ffunction-sections -fdata-sections,
1129 and linking with --gc-sections.
1131 This can reduce on disk and in-memory size of the kernel
1132 code and static data, particularly for small configs and
1133 on small systems. This has the possibility of introducing
1134 silently broken kernel if the required annotations are not
1135 present. This option is not well tested yet, so use at your
1147 config SYSCTL_EXCEPTION_TRACE
1150 Enable support for /proc/sys/debug/exception-trace.
1152 config SYSCTL_ARCH_UNALIGN_NO_WARN
1155 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1156 Allows arch to define/use @no_unaligned_warning to possibly warn
1157 about unaligned access emulation going on under the hood.
1159 config SYSCTL_ARCH_UNALIGN_ALLOW
1162 Enable support for /proc/sys/kernel/unaligned-trap
1163 Allows arches to define/use @unaligned_enabled to runtime toggle
1164 the unaligned access emulation.
1165 see arch/parisc/kernel/unaligned.c for reference
1167 config HAVE_PCSPKR_PLATFORM
1170 # interpreter that classic socket filters depend on
1175 bool "Configure standard kernel features (expert users)"
1176 # Unhide debug options, to make the on-by-default options visible
1179 This option allows certain base kernel options and settings
1180 to be disabled or tweaked. This is for specialized
1181 environments which can tolerate a "non-standard" kernel.
1182 Only use this if you really know what you are doing.
1185 bool "Enable 16-bit UID system calls" if EXPERT
1186 depends on HAVE_UID16 && MULTIUSER
1189 This enables the legacy 16-bit UID syscall wrappers.
1192 bool "Multiple users, groups and capabilities support" if EXPERT
1195 This option enables support for non-root users, groups and
1198 If you say N here, all processes will run with UID 0, GID 0, and all
1199 possible capabilities. Saying N here also compiles out support for
1200 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1203 If unsure, say Y here.
1205 config SGETMASK_SYSCALL
1206 bool "sgetmask/ssetmask syscalls support" if EXPERT
1207 def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1209 sys_sgetmask and sys_ssetmask are obsolete system calls
1210 no longer supported in libc but still enabled by default in some
1213 If unsure, leave the default option here.
1215 config SYSFS_SYSCALL
1216 bool "Sysfs syscall support" if EXPERT
1219 sys_sysfs is an obsolete system call no longer supported in libc.
1220 Note that disabling this option is more secure but might break
1221 compatibility with some systems.
1223 If unsure say Y here.
1225 config SYSCTL_SYSCALL
1226 bool "Sysctl syscall support" if EXPERT
1227 depends on PROC_SYSCTL
1231 sys_sysctl uses binary paths that have been found challenging
1232 to properly maintain and use. The interface in /proc/sys
1233 using paths with ascii names is now the primary path to this
1236 Almost nothing using the binary sysctl interface so if you are
1237 trying to save some space it is probably safe to disable this,
1238 making your kernel marginally smaller.
1240 If unsure say N here.
1243 bool "open by fhandle syscalls" if EXPERT
1247 If you say Y here, a user level program will be able to map
1248 file names to handle and then later use the handle for
1249 different file system operations. This is useful in implementing
1250 userspace file servers, which now track files using handles instead
1251 of names. The handle would remain the same even if file names
1252 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1256 bool "Posix Clocks & timers" if EXPERT
1259 This includes native support for POSIX timers to the kernel.
1260 Some embedded systems have no use for them and therefore they
1261 can be configured out to reduce the size of the kernel image.
1263 When this option is disabled, the following syscalls won't be
1264 available: timer_create, timer_gettime: timer_getoverrun,
1265 timer_settime, timer_delete, clock_adjtime, getitimer,
1266 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1267 clock_getres and clock_nanosleep syscalls will be limited to
1268 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1274 bool "Enable support for printk" if EXPERT
1277 This option enables normal printk support. Removing it
1278 eliminates most of the message strings from the kernel image
1279 and makes the kernel more or less silent. As this makes it
1280 very difficult to diagnose system problems, saying N here is
1281 strongly discouraged.
1289 bool "BUG() support" if EXPERT
1292 Disabling this option eliminates support for BUG and WARN, reducing
1293 the size of your kernel image and potentially quietly ignoring
1294 numerous fatal conditions. You should only consider disabling this
1295 option for embedded systems with no facilities for reporting errors.
1301 bool "Enable ELF core dumps" if EXPERT
1303 Enable support for generating core dumps. Disabling saves about 4k.
1306 config PCSPKR_PLATFORM
1307 bool "Enable PC-Speaker support" if EXPERT
1308 depends on HAVE_PCSPKR_PLATFORM
1312 This option allows to disable the internal PC-Speaker
1313 support, saving some memory.
1317 bool "Enable full-sized data structures for core" if EXPERT
1319 Disabling this option reduces the size of miscellaneous core
1320 kernel data structures. This saves memory on small machines,
1321 but may reduce performance.
1324 bool "Enable futex support" if EXPERT
1328 Disabling this option will cause the kernel to be built without
1329 support for "fast userspace mutexes". The resulting kernel may not
1330 run glibc-based applications correctly.
1334 depends on FUTEX && RT_MUTEXES
1337 config HAVE_FUTEX_CMPXCHG
1341 Architectures should select this if futex_atomic_cmpxchg_inatomic()
1342 is implemented and always working. This removes a couple of runtime
1346 bool "Enable eventpoll support" if EXPERT
1350 Disabling this option will cause the kernel to be built without
1351 support for epoll family of system calls.
1354 bool "Enable signalfd() system call" if EXPERT
1358 Enable the signalfd() system call that allows to receive signals
1359 on a file descriptor.
1364 bool "Enable timerfd() system call" if EXPERT
1368 Enable the timerfd() system call that allows to receive timer
1369 events on a file descriptor.
1374 bool "Enable eventfd() system call" if EXPERT
1378 Enable the eventfd() system call that allows to receive both
1379 kernel notification (ie. KAIO) or userspace notifications.
1384 bool "Use full shmem filesystem" if EXPERT
1388 The shmem is an internal filesystem used to manage shared memory.
1389 It is backed by swap and manages resource limits. It is also exported
1390 to userspace as tmpfs if TMPFS is enabled. Disabling this
1391 option replaces shmem and tmpfs with the much simpler ramfs code,
1392 which may be appropriate on small systems without swap.
1395 bool "Enable AIO support" if EXPERT
1398 This option enables POSIX asynchronous I/O which may by used
1399 by some high performance threaded applications. Disabling
1400 this option saves about 7k.
1402 config ADVISE_SYSCALLS
1403 bool "Enable madvise/fadvise syscalls" if EXPERT
1406 This option enables the madvise and fadvise syscalls, used by
1407 applications to advise the kernel about their future memory or file
1408 usage, improving performance. If building an embedded system where no
1409 applications use these syscalls, you can disable this option to save
1413 bool "Enable membarrier() system call" if EXPERT
1416 Enable the membarrier() system call that allows issuing memory
1417 barriers across all running threads, which can be used to distribute
1418 the cost of user-space memory barriers asymmetrically by transforming
1419 pairs of memory barriers into pairs consisting of membarrier() and a
1425 bool "Load all symbols for debugging/ksymoops" if EXPERT
1428 Say Y here to let the kernel print out symbolic crash information and
1429 symbolic stack backtraces. This increases the size of the kernel
1430 somewhat, as all symbols have to be loaded into the kernel image.
1433 bool "Include all symbols in kallsyms"
1434 depends on DEBUG_KERNEL && KALLSYMS
1436 Normally kallsyms only contains the symbols of functions for nicer
1437 OOPS messages and backtraces (i.e., symbols from the text and inittext
1438 sections). This is sufficient for most cases. And only in very rare
1439 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1440 names of variables from the data sections, etc).
1442 This option makes sure that all symbols are loaded into the kernel
1443 image (i.e., symbols from all sections) in cost of increased kernel
1444 size (depending on the kernel configuration, it may be 300KiB or
1445 something like this).
1447 Say N unless you really need all symbols.
1449 config KALLSYMS_ABSOLUTE_PERCPU
1452 default X86_64 && SMP
1454 config KALLSYMS_BASE_RELATIVE
1459 Instead of emitting them as absolute values in the native word size,
1460 emit the symbol references in the kallsyms table as 32-bit entries,
1461 each containing a relative value in the range [base, base + U32_MAX]
1462 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1463 an absolute value in the range [0, S32_MAX] or a relative value in the
1464 range [base, base + S32_MAX], where base is the lowest relative symbol
1465 address encountered in the image.
1467 On 64-bit builds, this reduces the size of the address table by 50%,
1468 but more importantly, it results in entries whose values are build
1469 time constants, and no relocation pass is required at runtime to fix
1470 up the entries based on the runtime load address of the kernel.
1472 # end of the "standard kernel features (expert users)" menu
1474 # syscall, maps, verifier
1476 bool "Enable bpf() system call"
1482 Enable the bpf() system call that allows to manipulate eBPF
1483 programs and maps via file descriptors.
1485 config BPF_JIT_ALWAYS_ON
1486 bool "Permanently enable BPF JIT and remove BPF interpreter"
1487 depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
1489 Enables BPF JIT and removes BPF interpreter to avoid
1490 speculative execution of BPF instructions by the interpreter
1493 bool "Enable userfaultfd() system call"
1497 Enable the userfaultfd() system call that allows to intercept and
1498 handle page faults in userland.
1500 config ARCH_HAS_MEMBARRIER_CALLBACKS
1503 config ARCH_HAS_MEMBARRIER_SYNC_CORE
1507 bool "Enable rseq() system call" if EXPERT
1509 depends on HAVE_RSEQ
1512 Enable the restartable sequences system call. It provides a
1513 user-space cache for the current CPU number value, which
1514 speeds up getting the current CPU number from user-space,
1515 as well as an ABI to speed up user-space operations on
1522 bool "Enabled debugging of rseq() system call" if EXPERT
1523 depends on RSEQ && DEBUG_KERNEL
1525 Enable extra debugging checks for the rseq system call.
1530 bool "Embedded system"
1531 option allnoconfig_y
1534 This option should be enabled if compiling the kernel for
1535 an embedded system so certain expert options are available
1538 config HAVE_PERF_EVENTS
1541 See tools/perf/design.txt for details.
1543 config PERF_USE_VMALLOC
1546 See tools/perf/design.txt for details
1549 bool "PC/104 support" if EXPERT
1551 Expose PC/104 form factor device drivers and options available for
1552 selection and configuration. Enable this option if your target
1553 machine has a PC/104 bus.
1555 menu "Kernel Performance Events And Counters"
1558 bool "Kernel performance events and counters"
1559 default y if PROFILING
1560 depends on HAVE_PERF_EVENTS
1565 Enable kernel support for various performance events provided
1566 by software and hardware.
1568 Software events are supported either built-in or via the
1569 use of generic tracepoints.
1571 Most modern CPUs support performance events via performance
1572 counter registers. These registers count the number of certain
1573 types of hw events: such as instructions executed, cachemisses
1574 suffered, or branches mis-predicted - without slowing down the
1575 kernel or applications. These registers can also trigger interrupts
1576 when a threshold number of events have passed - and can thus be
1577 used to profile the code that runs on that CPU.
1579 The Linux Performance Event subsystem provides an abstraction of
1580 these software and hardware event capabilities, available via a
1581 system call and used by the "perf" utility in tools/perf/. It
1582 provides per task and per CPU counters, and it provides event
1583 capabilities on top of those.
1587 config DEBUG_PERF_USE_VMALLOC
1589 bool "Debug: use vmalloc to back perf mmap() buffers"
1590 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1591 select PERF_USE_VMALLOC
1593 Use vmalloc memory to back perf mmap() buffers.
1595 Mostly useful for debugging the vmalloc code on platforms
1596 that don't require it.
1602 config VM_EVENT_COUNTERS
1604 bool "Enable VM event counters for /proc/vmstat" if EXPERT
1606 VM event counters are needed for event counts to be shown.
1607 This option allows the disabling of the VM event counters
1608 on EXPERT systems. /proc/vmstat will only show page counts
1609 if VM event counters are disabled.
1613 bool "Enable SLUB debugging support" if EXPERT
1614 depends on SLUB && SYSFS
1616 SLUB has extensive debug support features. Disabling these can
1617 result in significant savings in code size. This also disables
1618 SLUB sysfs support. /sys/slab will not exist and there will be
1619 no support for cache validation etc.
1621 config SLUB_MEMCG_SYSFS_ON
1623 bool "Enable memcg SLUB sysfs support by default" if EXPERT
1624 depends on SLUB && SYSFS && MEMCG
1626 SLUB creates a directory under /sys/kernel/slab for each
1627 allocation cache to host info and debug files. If memory
1628 cgroup is enabled, each cache can have per memory cgroup
1629 caches. SLUB can create the same sysfs directories for these
1630 caches under /sys/kernel/slab/CACHE/cgroup but it can lead
1631 to a very high number of debug files being created. This is
1632 controlled by slub_memcg_sysfs boot parameter and this
1633 config option determines the parameter's default value.
1636 bool "Disable heap randomization"
1639 Randomizing heap placement makes heap exploits harder, but it
1640 also breaks ancient binaries (including anything libc5 based).
1641 This option changes the bootup default to heap randomization
1642 disabled, and can be overridden at runtime by setting
1643 /proc/sys/kernel/randomize_va_space to 2.
1645 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1648 prompt "Choose SLAB allocator"
1651 This option allows to select a slab allocator.
1655 select HAVE_HARDENED_USERCOPY_ALLOCATOR
1657 The regular slab allocator that is established and known to work
1658 well in all environments. It organizes cache hot objects in
1659 per cpu and per node queues.
1662 bool "SLUB (Unqueued Allocator)"
1663 select HAVE_HARDENED_USERCOPY_ALLOCATOR
1665 SLUB is a slab allocator that minimizes cache line usage
1666 instead of managing queues of cached objects (SLAB approach).
1667 Per cpu caching is realized using slabs of objects instead
1668 of queues of objects. SLUB can use memory efficiently
1669 and has enhanced diagnostics. SLUB is the default choice for
1674 bool "SLOB (Simple Allocator)"
1676 SLOB replaces the stock allocator with a drastically simpler
1677 allocator. SLOB is generally more space efficient but
1678 does not perform as well on large systems.
1682 config SLAB_MERGE_DEFAULT
1683 bool "Allow slab caches to be merged"
1686 For reduced kernel memory fragmentation, slab caches can be
1687 merged when they share the same size and other characteristics.
1688 This carries a risk of kernel heap overflows being able to
1689 overwrite objects from merged caches (and more easily control
1690 cache layout), which makes such heap attacks easier to exploit
1691 by attackers. By keeping caches unmerged, these kinds of exploits
1692 can usually only damage objects in the same cache. To disable
1693 merging at runtime, "slab_nomerge" can be passed on the kernel
1696 config SLAB_FREELIST_RANDOM
1698 depends on SLAB || SLUB
1699 bool "SLAB freelist randomization"
1701 Randomizes the freelist order used on creating new pages. This
1702 security feature reduces the predictability of the kernel slab
1703 allocator against heap overflows.
1705 config SLAB_FREELIST_HARDENED
1706 bool "Harden slab freelist metadata"
1709 Many kernel heap attacks try to target slab cache metadata and
1710 other infrastructure. This options makes minor performance
1711 sacrifies to harden the kernel slab allocator against common
1712 freelist exploit methods.
1714 config SLUB_CPU_PARTIAL
1716 depends on SLUB && SMP
1717 bool "SLUB per cpu partial cache"
1719 Per cpu partial caches accellerate objects allocation and freeing
1720 that is local to a processor at the price of more indeterminism
1721 in the latency of the free. On overflow these caches will be cleared
1722 which requires the taking of locks that may cause latency spikes.
1723 Typically one would choose no for a realtime system.
1725 config MMAP_ALLOW_UNINITIALIZED
1726 bool "Allow mmapped anonymous memory to be uninitialized"
1727 depends on EXPERT && !MMU
1730 Normally, and according to the Linux spec, anonymous memory obtained
1731 from mmap() has its contents cleared before it is passed to
1732 userspace. Enabling this config option allows you to request that
1733 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1734 providing a huge performance boost. If this option is not enabled,
1735 then the flag will be ignored.
1737 This is taken advantage of by uClibc's malloc(), and also by
1738 ELF-FDPIC binfmt's brk and stack allocator.
1740 Because of the obvious security issues, this option should only be
1741 enabled on embedded devices where you control what is run in
1742 userspace. Since that isn't generally a problem on no-MMU systems,
1743 it is normally safe to say Y here.
1745 See Documentation/nommu-mmap.txt for more information.
1747 config SYSTEM_DATA_VERIFICATION
1749 select SYSTEM_TRUSTED_KEYRING
1753 select ASYMMETRIC_KEY_TYPE
1754 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1757 select X509_CERTIFICATE_PARSER
1758 select PKCS7_MESSAGE_PARSER
1760 Provide PKCS#7 message verification using the contents of the system
1761 trusted keyring to provide public keys. This then can be used for
1762 module verification, kexec image verification and firmware blob
1766 bool "Profiling support"
1768 Say Y here to enable the extended profiling support mechanisms used
1769 by profilers such as OProfile.
1772 # Place an empty function call at each tracepoint site. Can be
1773 # dynamically changed for a probe function.
1778 endmenu # General setup
1780 source "arch/Kconfig"
1787 default 0 if BASE_FULL
1788 default 1 if !BASE_FULL
1791 bool "Enable loadable module support"
1794 Kernel modules are small pieces of compiled code which can
1795 be inserted in the running kernel, rather than being
1796 permanently built into the kernel. You use the "modprobe"
1797 tool to add (and sometimes remove) them. If you say Y here,
1798 many parts of the kernel can be built as modules (by
1799 answering M instead of Y where indicated): this is most
1800 useful for infrequently used options which are not required
1801 for booting. For more information, see the man pages for
1802 modprobe, lsmod, modinfo, insmod and rmmod.
1804 If you say Y here, you will need to run "make
1805 modules_install" to put the modules under /lib/modules/
1806 where modprobe can find them (you may need to be root to do
1813 config MODULE_FORCE_LOAD
1814 bool "Forced module loading"
1817 Allow loading of modules without version information (ie. modprobe
1818 --force). Forced module loading sets the 'F' (forced) taint flag and
1819 is usually a really bad idea.
1821 config MODULE_UNLOAD
1822 bool "Module unloading"
1824 Without this option you will not be able to unload any
1825 modules (note that some modules may not be unloadable
1826 anyway), which makes your kernel smaller, faster
1827 and simpler. If unsure, say Y.
1829 config MODULE_FORCE_UNLOAD
1830 bool "Forced module unloading"
1831 depends on MODULE_UNLOAD
1833 This option allows you to force a module to unload, even if the
1834 kernel believes it is unsafe: the kernel will remove the module
1835 without waiting for anyone to stop using it (using the -f option to
1836 rmmod). This is mainly for kernel developers and desperate users.
1840 bool "Module versioning support"
1842 Usually, you have to use modules compiled with your kernel.
1843 Saying Y here makes it sometimes possible to use modules
1844 compiled for different kernels, by adding enough information
1845 to the modules to (hopefully) spot any changes which would
1846 make them incompatible with the kernel you are running. If
1849 config MODULE_REL_CRCS
1851 depends on MODVERSIONS
1853 config MODULE_SRCVERSION_ALL
1854 bool "Source checksum for all modules"
1856 Modules which contain a MODULE_VERSION get an extra "srcversion"
1857 field inserted into their modinfo section, which contains a
1858 sum of the source files which made it. This helps maintainers
1859 see exactly which source was used to build a module (since
1860 others sometimes change the module source without updating
1861 the version). With this option, such a "srcversion" field
1862 will be created for all modules. If unsure, say N.
1865 bool "Module signature verification"
1867 select SYSTEM_DATA_VERIFICATION
1869 Check modules for valid signatures upon load: the signature
1870 is simply appended to the module. For more information see
1871 <file:Documentation/admin-guide/module-signing.rst>.
1873 Note that this option adds the OpenSSL development packages as a
1874 kernel build dependency so that the signing tool can use its crypto
1877 !!!WARNING!!! If you enable this option, you MUST make sure that the
1878 module DOES NOT get stripped after being signed. This includes the
1879 debuginfo strip done by some packagers (such as rpmbuild) and
1880 inclusion into an initramfs that wants the module size reduced.
1882 config MODULE_SIG_FORCE
1883 bool "Require modules to be validly signed"
1884 depends on MODULE_SIG
1886 Reject unsigned modules or signed modules for which we don't have a
1887 key. Without this, such modules will simply taint the kernel.
1889 config MODULE_SIG_ALL
1890 bool "Automatically sign all modules"
1892 depends on MODULE_SIG
1894 Sign all modules during make modules_install. Without this option,
1895 modules must be signed manually, using the scripts/sign-file tool.
1897 comment "Do not forget to sign required modules with scripts/sign-file"
1898 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
1901 prompt "Which hash algorithm should modules be signed with?"
1902 depends on MODULE_SIG
1904 This determines which sort of hashing algorithm will be used during
1905 signature generation. This algorithm _must_ be built into the kernel
1906 directly so that signature verification can take place. It is not
1907 possible to load a signed module containing the algorithm to check
1908 the signature on that module.
1910 config MODULE_SIG_SHA1
1911 bool "Sign modules with SHA-1"
1914 config MODULE_SIG_SHA224
1915 bool "Sign modules with SHA-224"
1916 select CRYPTO_SHA256
1918 config MODULE_SIG_SHA256
1919 bool "Sign modules with SHA-256"
1920 select CRYPTO_SHA256
1922 config MODULE_SIG_SHA384
1923 bool "Sign modules with SHA-384"
1924 select CRYPTO_SHA512
1926 config MODULE_SIG_SHA512
1927 bool "Sign modules with SHA-512"
1928 select CRYPTO_SHA512
1932 config MODULE_SIG_HASH
1934 depends on MODULE_SIG
1935 default "sha1" if MODULE_SIG_SHA1
1936 default "sha224" if MODULE_SIG_SHA224
1937 default "sha256" if MODULE_SIG_SHA256
1938 default "sha384" if MODULE_SIG_SHA384
1939 default "sha512" if MODULE_SIG_SHA512
1941 config MODULE_COMPRESS
1942 bool "Compress modules on installation"
1946 Compresses kernel modules when 'make modules_install' is run; gzip or
1947 xz depending on "Compression algorithm" below.
1949 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
1951 Out-of-tree kernel modules installed using Kbuild will also be
1952 compressed upon installation.
1954 Note: for modules inside an initrd or initramfs, it's more efficient
1955 to compress the whole initrd or initramfs instead.
1957 Note: This is fully compatible with signed modules.
1962 prompt "Compression algorithm"
1963 depends on MODULE_COMPRESS
1964 default MODULE_COMPRESS_GZIP
1966 This determines which sort of compression will be used during
1967 'make modules_install'.
1969 GZIP (default) and XZ are supported.
1971 config MODULE_COMPRESS_GZIP
1974 config MODULE_COMPRESS_XZ
1979 config TRIM_UNUSED_KSYMS
1980 bool "Trim unused exported kernel symbols"
1981 depends on MODULES && !UNUSED_SYMBOLS
1983 The kernel and some modules make many symbols available for
1984 other modules to use via EXPORT_SYMBOL() and variants. Depending
1985 on the set of modules being selected in your kernel configuration,
1986 many of those exported symbols might never be used.
1988 This option allows for unused exported symbols to be dropped from
1989 the build. In turn, this provides the compiler more opportunities
1990 (especially when using LTO) for optimizing the code and reducing
1991 binary size. This might have some security advantages as well.
1993 If unsure, or if you need to build out-of-tree modules, say N.
1997 config MODULES_TREE_LOOKUP
1999 depends on PERF_EVENTS || TRACING
2001 config INIT_ALL_POSSIBLE
2004 Back when each arch used to define their own cpu_online_mask and
2005 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2006 with all 1s, and others with all 0s. When they were centralised,
2007 it was better to provide this option than to break all the archs
2008 and have several arch maintainers pursuing me down dark alleys.
2010 source "block/Kconfig"
2012 config PREEMPT_NOTIFIERS
2022 Build a simple ASN.1 grammar compiler that produces a bytecode output
2023 that can be interpreted by the ASN.1 stream decoder and used to
2024 inform it as to what tags are to be expected in a stream and what
2025 functions to call on what tags.
2027 source "kernel/Kconfig.locks"
2029 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2032 # It may be useful for an architecture to override the definitions of the
2033 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2034 # and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2035 # different calling convention for syscalls. They can also override the
2036 # macros for not-implemented syscalls in kernel/sys_ni.c and
2037 # kernel/time/posix-stubs.c. All these overrides need to be available in
2038 # <asm/syscall_wrapper.h>.
2039 config ARCH_HAS_SYSCALL_WRAPPER
projects / platform / kernel / linux-rpi.git / blob