5 default "/lib/modules/$(shell,uname -r)/.config"
6 default "/etc/kernel-config"
7 default "/boot/config-$(shell,uname -r)"
9 default "arch/$(ARCH)/defconfig"
12 def_bool $(success,$(CC) --version | head -n 1 | grep -q gcc)
16 default $(shell,$(srctree)/scripts/gcc-version.sh -p $(CC) | sed 's/^0*//') if CC_IS_GCC
20 def_bool $(success,$(CC) --version | head -n 1 | grep -q clang)
24 default $(shell,$(srctree)/scripts/clang-version.sh $(CC))
26 config CC_HAS_ASM_GOTO
27 def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC))
36 config BUILDTIME_EXTABLE_SORT
39 config THREAD_INFO_IN_TASK
42 Select this to move thread_info off the stack into task_struct. To
43 make this work, an arch will need to remove all thread_info fields
44 except flags and fix any runtime bugs.
46 One subtle change that will be needed is to use try_get_task_stack()
47 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
56 depends on BROKEN || !SMP
59 config INIT_ENV_ARG_LIMIT
64 Maximum of each of the number of arguments and environment
65 variables passed to init from the kernel command line.
68 bool "Compile also drivers which will not load"
72 Some drivers can be compiled on a different platform than they are
73 intended to be run on. Despite they cannot be loaded there (or even
74 when they load they cannot be used due to missing HW support),
75 developers still, opposing to distributors, might want to build such
76 drivers to compile-test them.
78 If you are a developer and want to build everything available, say Y
79 here. If you are a user/distributor, say N here to exclude useless
80 drivers to be distributed.
83 string "Local version - append to kernel release"
85 Append an extra string to the end of your kernel version.
86 This will show up when you type uname, for example.
87 The string you set here will be appended after the contents of
88 any files with a filename matching localversion* in your
89 object and source tree, in that order. Your total string can
90 be a maximum of 64 characters.
92 config LOCALVERSION_AUTO
93 bool "Automatically append version information to the version string"
95 depends on !COMPILE_TEST
97 This will try to automatically determine if the current tree is a
98 release tree by looking for git tags that belong to the current
101 A string of the format -gxxxxxxxx will be added to the localversion
102 if a git-based tree is found. The string generated by this will be
103 appended after any matching localversion* files, and after the value
104 set in CONFIG_LOCALVERSION.
106 (The actual string used here is the first eight characters produced
107 by running the command:
109 $ git rev-parse --verify HEAD
111 which is done within the script "scripts/setlocalversion".)
114 string "Build ID Salt"
117 The build ID is used to link binaries and their debug info. Setting
118 this option will use the value in the calculation of the build id.
119 This is mostly useful for distributions which want to ensure the
120 build is unique between builds. It's safe to leave the default.
122 config HAVE_KERNEL_GZIP
125 config HAVE_KERNEL_BZIP2
128 config HAVE_KERNEL_LZMA
131 config HAVE_KERNEL_XZ
134 config HAVE_KERNEL_LZO
137 config HAVE_KERNEL_LZ4
140 config HAVE_KERNEL_UNCOMPRESSED
144 prompt "Kernel compression mode"
146 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 || HAVE_KERNEL_UNCOMPRESSED
148 The linux kernel is a kind of self-extracting executable.
149 Several compression algorithms are available, which differ
150 in efficiency, compression and decompression speed.
151 Compression speed is only relevant when building a kernel.
152 Decompression speed is relevant at each boot.
154 If you have any problems with bzip2 or lzma compressed
155 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
156 version of this functionality (bzip2 only), for 2.4, was
157 supplied by Christian Ludwig)
159 High compression options are mostly useful for users, who
160 are low on disk space (embedded systems), but for whom ram
163 If in doubt, select 'gzip'
167 depends on HAVE_KERNEL_GZIP
169 The old and tried gzip compression. It provides a good balance
170 between compression ratio and decompression speed.
174 depends on HAVE_KERNEL_BZIP2
176 Its compression ratio and speed is intermediate.
177 Decompression speed is slowest among the choices. The kernel
178 size is about 10% smaller with bzip2, in comparison to gzip.
179 Bzip2 uses a large amount of memory. For modern kernels you
180 will need at least 8MB RAM or more for booting.
184 depends on HAVE_KERNEL_LZMA
186 This compression algorithm's ratio is best. Decompression speed
187 is between gzip and bzip2. Compression is slowest.
188 The kernel size is about 33% smaller with LZMA in comparison to gzip.
192 depends on HAVE_KERNEL_XZ
194 XZ uses the LZMA2 algorithm and instruction set specific
195 BCJ filters which can improve compression ratio of executable
196 code. The size of the kernel is about 30% smaller with XZ in
197 comparison to gzip. On architectures for which there is a BCJ
198 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
199 will create a few percent smaller kernel than plain LZMA.
201 The speed is about the same as with LZMA: The decompression
202 speed of XZ is better than that of bzip2 but worse than gzip
203 and LZO. Compression is slow.
207 depends on HAVE_KERNEL_LZO
209 Its compression ratio is the poorest among the choices. The kernel
210 size is about 10% bigger than gzip; however its speed
211 (both compression and decompression) is the fastest.
215 depends on HAVE_KERNEL_LZ4
217 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
218 A preliminary version of LZ4 de/compression tool is available at
219 <https://code.google.com/p/lz4/>.
221 Its compression ratio is worse than LZO. The size of the kernel
222 is about 8% bigger than LZO. But the decompression speed is
225 config KERNEL_UNCOMPRESSED
227 depends on HAVE_KERNEL_UNCOMPRESSED
229 Produce uncompressed kernel image. This option is usually not what
230 you want. It is useful for debugging the kernel in slow simulation
231 environments, where decompressing and moving the kernel is awfully
232 slow. This option allows early boot code to skip the decompressor
233 and jump right at uncompressed kernel image.
237 config DEFAULT_HOSTNAME
238 string "Default hostname"
241 This option determines the default system hostname before userspace
242 calls sethostname(2). The kernel traditionally uses "(none)" here,
243 but you may wish to use a different default here to make a minimal
244 system more usable with less configuration.
247 # For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can
248 # add proper SWAP support to them, in which case this can be remove.
254 bool "Support for paging of anonymous memory (swap)"
255 depends on MMU && BLOCK && !ARCH_NO_SWAP
258 This option allows you to choose whether you want to have support
259 for so called swap devices or swap files in your kernel that are
260 used to provide more virtual memory than the actual RAM present
261 in your computer. If unsure say Y.
266 Inter Process Communication is a suite of library functions and
267 system calls which let processes (running programs) synchronize and
268 exchange information. It is generally considered to be a good thing,
269 and some programs won't run unless you say Y here. In particular, if
270 you want to run the DOS emulator dosemu under Linux (read the
271 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
272 you'll need to say Y here.
274 You can find documentation about IPC with "info ipc" and also in
275 section 6.4 of the Linux Programmer's Guide, available from
276 <http://www.tldp.org/guides.html>.
278 config SYSVIPC_SYSCTL
285 bool "POSIX Message Queues"
288 POSIX variant of message queues is a part of IPC. In POSIX message
289 queues every message has a priority which decides about succession
290 of receiving it by a process. If you want to compile and run
291 programs written e.g. for Solaris with use of its POSIX message
292 queues (functions mq_*) say Y here.
294 POSIX message queues are visible as a filesystem called 'mqueue'
295 and can be mounted somewhere if you want to do filesystem
296 operations on message queues.
300 config POSIX_MQUEUE_SYSCTL
302 depends on POSIX_MQUEUE
306 config CROSS_MEMORY_ATTACH
307 bool "Enable process_vm_readv/writev syscalls"
311 Enabling this option adds the system calls process_vm_readv and
312 process_vm_writev which allow a process with the correct privileges
313 to directly read from or write to another process' address space.
314 See the man page for more details.
317 bool "uselib syscall"
318 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
320 This option enables the uselib syscall, a system call used in the
321 dynamic linker from libc5 and earlier. glibc does not use this
322 system call. If you intend to run programs built on libc5 or
323 earlier, you may need to enable this syscall. Current systems
324 running glibc can safely disable this.
327 bool "Auditing support"
330 Enable auditing infrastructure that can be used with another
331 kernel subsystem, such as SELinux (which requires this for
332 logging of avc messages output). System call auditing is included
333 on architectures which support it.
335 config HAVE_ARCH_AUDITSYSCALL
340 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
343 source "kernel/irq/Kconfig"
344 source "kernel/time/Kconfig"
345 source "kernel/Kconfig.preempt"
347 menu "CPU/Task time and stats accounting"
349 config VIRT_CPU_ACCOUNTING
353 prompt "Cputime accounting"
354 default TICK_CPU_ACCOUNTING if !PPC64
355 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
357 # Kind of a stub config for the pure tick based cputime accounting
358 config TICK_CPU_ACCOUNTING
359 bool "Simple tick based cputime accounting"
360 depends on !S390 && !NO_HZ_FULL
362 This is the basic tick based cputime accounting that maintains
363 statistics about user, system and idle time spent on per jiffies
368 config VIRT_CPU_ACCOUNTING_NATIVE
369 bool "Deterministic task and CPU time accounting"
370 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
371 select VIRT_CPU_ACCOUNTING
373 Select this option to enable more accurate task and CPU time
374 accounting. This is done by reading a CPU counter on each
375 kernel entry and exit and on transitions within the kernel
376 between system, softirq and hardirq state, so there is a
377 small performance impact. In the case of s390 or IBM POWER > 5,
378 this also enables accounting of stolen time on logically-partitioned
381 config VIRT_CPU_ACCOUNTING_GEN
382 bool "Full dynticks CPU time accounting"
383 depends on HAVE_CONTEXT_TRACKING
384 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
385 select VIRT_CPU_ACCOUNTING
386 select CONTEXT_TRACKING
388 Select this option to enable task and CPU time accounting on full
389 dynticks systems. This accounting is implemented by watching every
390 kernel-user boundaries using the context tracking subsystem.
391 The accounting is thus performed at the expense of some significant
394 For now this is only useful if you are working on the full
395 dynticks subsystem development.
401 config IRQ_TIME_ACCOUNTING
402 bool "Fine granularity task level IRQ time accounting"
403 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
405 Select this option to enable fine granularity task irq time
406 accounting. This is done by reading a timestamp on each
407 transitions between softirq and hardirq state, so there can be a
408 small performance impact.
410 If in doubt, say N here.
412 config HAVE_SCHED_AVG_IRQ
414 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
417 config BSD_PROCESS_ACCT
418 bool "BSD Process Accounting"
421 If you say Y here, a user level program will be able to instruct the
422 kernel (via a special system call) to write process accounting
423 information to a file: whenever a process exits, information about
424 that process will be appended to the file by the kernel. The
425 information includes things such as creation time, owning user,
426 command name, memory usage, controlling terminal etc. (the complete
427 list is in the struct acct in <file:include/linux/acct.h>). It is
428 up to the user level program to do useful things with this
429 information. This is generally a good idea, so say Y.
431 config BSD_PROCESS_ACCT_V3
432 bool "BSD Process Accounting version 3 file format"
433 depends on BSD_PROCESS_ACCT
436 If you say Y here, the process accounting information is written
437 in a new file format that also logs the process IDs of each
438 process and its parent. Note that this file format is incompatible
439 with previous v0/v1/v2 file formats, so you will need updated tools
440 for processing it. A preliminary version of these tools is available
441 at <http://www.gnu.org/software/acct/>.
444 bool "Export task/process statistics through netlink"
449 Export selected statistics for tasks/processes through the
450 generic netlink interface. Unlike BSD process accounting, the
451 statistics are available during the lifetime of tasks/processes as
452 responses to commands. Like BSD accounting, they are sent to user
457 config TASK_DELAY_ACCT
458 bool "Enable per-task delay accounting"
462 Collect information on time spent by a task waiting for system
463 resources like cpu, synchronous block I/O completion and swapping
464 in pages. Such statistics can help in setting a task's priorities
465 relative to other tasks for cpu, io, rss limits etc.
470 bool "Enable extended accounting over taskstats"
473 Collect extended task accounting data and send the data
474 to userland for processing over the taskstats interface.
478 config TASK_IO_ACCOUNTING
479 bool "Enable per-task storage I/O accounting"
480 depends on TASK_XACCT
482 Collect information on the number of bytes of storage I/O which this
488 bool "Pressure stall information tracking"
490 Collect metrics that indicate how overcommitted the CPU, memory,
491 and IO capacity are in the system.
493 If you say Y here, the kernel will create /proc/pressure/ with the
494 pressure statistics files cpu, memory, and io. These will indicate
495 the share of walltime in which some or all tasks in the system are
496 delayed due to contention of the respective resource.
498 In kernels with cgroup support, cgroups (cgroup2 only) will
499 have cpu.pressure, memory.pressure, and io.pressure files,
500 which aggregate pressure stalls for the grouped tasks only.
502 For more details see Documentation/accounting/psi.txt.
506 config PSI_DEFAULT_DISABLED
507 bool "Require boot parameter to enable pressure stall information tracking"
511 If set, pressure stall information tracking will be disabled
512 per default but can be enabled through passing psi=1 on the
513 kernel commandline during boot.
515 This feature adds some code to the task wakeup and sleep
516 paths of the scheduler. The overhead is too low to affect
517 common scheduling-intense workloads in practice (such as
518 webservers, memcache), but it does show up in artificial
519 scheduler stress tests, such as hackbench.
521 If you are paranoid and not sure what the kernel will be
526 endmenu # "CPU/Task time and stats accounting"
530 depends on SMP || COMPILE_TEST
533 Make sure that CPUs running critical tasks are not disturbed by
534 any source of "noise" such as unbound workqueues, timers, kthreads...
535 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
536 the "isolcpus=" boot parameter.
540 source "kernel/rcu/Kconfig"
547 tristate "Kernel .config support"
550 This option enables the complete Linux kernel ".config" file
551 contents to be saved in the kernel. It provides documentation
552 of which kernel options are used in a running kernel or in an
553 on-disk kernel. This information can be extracted from the kernel
554 image file with the script scripts/extract-ikconfig and used as
555 input to rebuild the current kernel or to build another kernel.
556 It can also be extracted from a running kernel by reading
557 /proc/config.gz if enabled (below).
560 bool "Enable access to .config through /proc/config.gz"
561 depends on IKCONFIG && PROC_FS
563 This option enables access to the kernel configuration file
564 through /proc/config.gz.
567 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
572 Select the minimal kernel log buffer size as a power of 2.
573 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
574 parameter, see below. Any higher size also might be forced
575 by "log_buf_len" boot parameter.
585 config LOG_CPU_MAX_BUF_SHIFT
586 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
589 default 12 if !BASE_SMALL
590 default 0 if BASE_SMALL
593 This option allows to increase the default ring buffer size
594 according to the number of CPUs. The value defines the contribution
595 of each CPU as a power of 2. The used space is typically only few
596 lines however it might be much more when problems are reported,
599 The increased size means that a new buffer has to be allocated and
600 the original static one is unused. It makes sense only on systems
601 with more CPUs. Therefore this value is used only when the sum of
602 contributions is greater than the half of the default kernel ring
603 buffer as defined by LOG_BUF_SHIFT. The default values are set
604 so that more than 64 CPUs are needed to trigger the allocation.
606 Also this option is ignored when "log_buf_len" kernel parameter is
607 used as it forces an exact (power of two) size of the ring buffer.
609 The number of possible CPUs is used for this computation ignoring
610 hotplugging making the computation optimal for the worst case
611 scenario while allowing a simple algorithm to be used from bootup.
613 Examples shift values and their meaning:
614 17 => 128 KB for each CPU
615 16 => 64 KB for each CPU
616 15 => 32 KB for each CPU
617 14 => 16 KB for each CPU
618 13 => 8 KB for each CPU
619 12 => 4 KB for each CPU
621 config PRINTK_SAFE_LOG_BUF_SHIFT
622 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
627 Select the size of an alternate printk per-CPU buffer where messages
628 printed from usafe contexts are temporary stored. One example would
629 be NMI messages, another one - printk recursion. The messages are
630 copied to the main log buffer in a safe context to avoid a deadlock.
631 The value defines the size as a power of 2.
633 Those messages are rare and limited. The largest one is when
634 a backtrace is printed. It usually fits into 4KB. Select
635 8KB if you want to be on the safe side.
638 17 => 128 KB for each CPU
639 16 => 64 KB for each CPU
640 15 => 32 KB for each CPU
641 14 => 16 KB for each CPU
642 13 => 8 KB for each CPU
643 12 => 4 KB for each CPU
646 # Architectures with an unreliable sched_clock() should select this:
648 config HAVE_UNSTABLE_SCHED_CLOCK
651 config GENERIC_SCHED_CLOCK
655 # For architectures that want to enable the support for NUMA-affine scheduler
658 config ARCH_SUPPORTS_NUMA_BALANCING
662 # For architectures that prefer to flush all TLBs after a number of pages
663 # are unmapped instead of sending one IPI per page to flush. The architecture
664 # must provide guarantees on what happens if a clean TLB cache entry is
665 # written after the unmap. Details are in mm/rmap.c near the check for
666 # should_defer_flush. The architecture should also consider if the full flush
667 # and the refill costs are offset by the savings of sending fewer IPIs.
668 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
672 # For architectures that know their GCC __int128 support is sound
674 config ARCH_SUPPORTS_INT128
677 # For architectures that (ab)use NUMA to represent different memory regions
678 # all cpu-local but of different latencies, such as SuperH.
680 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
683 config NUMA_BALANCING
684 bool "Memory placement aware NUMA scheduler"
685 depends on ARCH_SUPPORTS_NUMA_BALANCING
686 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
687 depends on SMP && NUMA && MIGRATION
689 This option adds support for automatic NUMA aware memory/task placement.
690 The mechanism is quite primitive and is based on migrating memory when
691 it has references to the node the task is running on.
693 This system will be inactive on UMA systems.
695 config NUMA_BALANCING_DEFAULT_ENABLED
696 bool "Automatically enable NUMA aware memory/task placement"
698 depends on NUMA_BALANCING
700 If set, automatic NUMA balancing will be enabled if running on a NUMA
704 bool "Control Group support"
707 This option adds support for grouping sets of processes together, for
708 use with process control subsystems such as Cpusets, CFS, memory
709 controls or device isolation.
711 - Documentation/scheduler/sched-design-CFS.txt (CFS)
712 - Documentation/cgroup-v1/ (features for grouping, isolation
713 and resource control)
723 bool "Memory controller"
727 Provides control over the memory footprint of tasks in a cgroup.
730 bool "Swap controller"
731 depends on MEMCG && SWAP
733 Provides control over the swap space consumed by tasks in a cgroup.
735 config MEMCG_SWAP_ENABLED
736 bool "Swap controller enabled by default"
737 depends on MEMCG_SWAP
740 Memory Resource Controller Swap Extension comes with its price in
741 a bigger memory consumption. General purpose distribution kernels
742 which want to enable the feature but keep it disabled by default
743 and let the user enable it by swapaccount=1 boot command line
744 parameter should have this option unselected.
745 For those who want to have the feature enabled by default should
746 select this option (if, for some reason, they need to disable it
747 then swapaccount=0 does the trick).
751 depends on MEMCG && !SLOB
759 Generic block IO controller cgroup interface. This is the common
760 cgroup interface which should be used by various IO controlling
763 Currently, CFQ IO scheduler uses it to recognize task groups and
764 control disk bandwidth allocation (proportional time slice allocation)
765 to such task groups. It is also used by bio throttling logic in
766 block layer to implement upper limit in IO rates on a device.
768 This option only enables generic Block IO controller infrastructure.
769 One needs to also enable actual IO controlling logic/policy. For
770 enabling proportional weight division of disk bandwidth in CFQ, set
771 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
772 CONFIG_BLK_DEV_THROTTLING=y.
774 See Documentation/cgroup-v1/blkio-controller.txt for more information.
776 config DEBUG_BLK_CGROUP
777 bool "IO controller debugging"
778 depends on BLK_CGROUP
781 Enable some debugging help. Currently it exports additional stat
782 files in a cgroup which can be useful for debugging.
784 config CGROUP_WRITEBACK
786 depends on MEMCG && BLK_CGROUP
789 menuconfig CGROUP_SCHED
790 bool "CPU controller"
793 This feature lets CPU scheduler recognize task groups and control CPU
794 bandwidth allocation to such task groups. It uses cgroups to group
798 config FAIR_GROUP_SCHED
799 bool "Group scheduling for SCHED_OTHER"
800 depends on CGROUP_SCHED
804 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
805 depends on FAIR_GROUP_SCHED
808 This option allows users to define CPU bandwidth rates (limits) for
809 tasks running within the fair group scheduler. Groups with no limit
810 set are considered to be unconstrained and will run with no
812 See Documentation/scheduler/sched-bwc.txt for more information.
814 config RT_GROUP_SCHED
815 bool "Group scheduling for SCHED_RR/FIFO"
816 depends on CGROUP_SCHED
819 This feature lets you explicitly allocate real CPU bandwidth
820 to task groups. If enabled, it will also make it impossible to
821 schedule realtime tasks for non-root users until you allocate
822 realtime bandwidth for them.
823 See Documentation/scheduler/sched-rt-group.txt for more information.
828 bool "PIDs controller"
830 Provides enforcement of process number limits in the scope of a
831 cgroup. Any attempt to fork more processes than is allowed in the
832 cgroup will fail. PIDs are fundamentally a global resource because it
833 is fairly trivial to reach PID exhaustion before you reach even a
834 conservative kmemcg limit. As a result, it is possible to grind a
835 system to halt without being limited by other cgroup policies. The
836 PIDs controller is designed to stop this from happening.
838 It should be noted that organisational operations (such as attaching
839 to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
840 since the PIDs limit only affects a process's ability to fork, not to
844 bool "RDMA controller"
846 Provides enforcement of RDMA resources defined by IB stack.
847 It is fairly easy for consumers to exhaust RDMA resources, which
848 can result into resource unavailability to other consumers.
849 RDMA controller is designed to stop this from happening.
850 Attaching processes with active RDMA resources to the cgroup
851 hierarchy is allowed even if can cross the hierarchy's limit.
853 config CGROUP_FREEZER
854 bool "Freezer controller"
856 Provides a way to freeze and unfreeze all tasks in a
859 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
860 controller includes important in-kernel memory consumers per default.
862 If you're using cgroup2, say N.
864 config CGROUP_HUGETLB
865 bool "HugeTLB controller"
866 depends on HUGETLB_PAGE
870 Provides a cgroup controller for HugeTLB pages.
871 When you enable this, you can put a per cgroup limit on HugeTLB usage.
872 The limit is enforced during page fault. Since HugeTLB doesn't
873 support page reclaim, enforcing the limit at page fault time implies
874 that, the application will get SIGBUS signal if it tries to access
875 HugeTLB pages beyond its limit. This requires the application to know
876 beforehand how much HugeTLB pages it would require for its use. The
877 control group is tracked in the third page lru pointer. This means
878 that we cannot use the controller with huge page less than 3 pages.
881 bool "Cpuset controller"
884 This option will let you create and manage CPUSETs which
885 allow dynamically partitioning a system into sets of CPUs and
886 Memory Nodes and assigning tasks to run only within those sets.
887 This is primarily useful on large SMP or NUMA systems.
891 config PROC_PID_CPUSET
892 bool "Include legacy /proc/<pid>/cpuset file"
897 bool "Device controller"
899 Provides a cgroup controller implementing whitelists for
900 devices which a process in the cgroup can mknod or open.
902 config CGROUP_CPUACCT
903 bool "Simple CPU accounting controller"
905 Provides a simple controller for monitoring the
906 total CPU consumed by the tasks in a cgroup.
909 bool "Perf controller"
910 depends on PERF_EVENTS
912 This option extends the perf per-cpu mode to restrict monitoring
913 to threads which belong to the cgroup specified and run on the
919 bool "Support for eBPF programs attached to cgroups"
920 depends on BPF_SYSCALL
921 select SOCK_CGROUP_DATA
923 Allow attaching eBPF programs to a cgroup using the bpf(2)
924 syscall command BPF_PROG_ATTACH.
926 In which context these programs are accessed depends on the type
927 of attachment. For instance, programs that are attached using
928 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
932 bool "Debug controller"
934 depends on DEBUG_KERNEL
936 This option enables a simple controller that exports
937 debugging information about the cgroups framework. This
938 controller is for control cgroup debugging only. Its
939 interfaces are not stable.
943 config SOCK_CGROUP_DATA
949 menuconfig NAMESPACES
950 bool "Namespaces support" if EXPERT
954 Provides the way to make tasks work with different objects using
955 the same id. For example same IPC id may refer to different objects
956 or same user id or pid may refer to different tasks when used in
957 different namespaces.
965 In this namespace tasks see different info provided with the
970 depends on (SYSVIPC || POSIX_MQUEUE)
973 In this namespace tasks work with IPC ids which correspond to
974 different IPC objects in different namespaces.
977 bool "User namespace"
980 This allows containers, i.e. vservers, to use user namespaces
981 to provide different user info for different servers.
983 When user namespaces are enabled in the kernel it is
984 recommended that the MEMCG option also be enabled and that
985 user-space use the memory control groups to limit the amount
986 of memory a memory unprivileged users can use.
991 bool "PID Namespaces"
994 Support process id namespaces. This allows having multiple
995 processes with the same pid as long as they are in different
996 pid namespaces. This is a building block of containers.
999 bool "Network namespace"
1003 Allow user space to create what appear to be multiple instances
1004 of the network stack.
1008 config CHECKPOINT_RESTORE
1009 bool "Checkpoint/restore support"
1010 select PROC_CHILDREN
1013 Enables additional kernel features in a sake of checkpoint/restore.
1014 In particular it adds auxiliary prctl codes to setup process text,
1015 data and heap segment sizes, and a few additional /proc filesystem
1018 If unsure, say N here.
1020 config SCHED_AUTOGROUP
1021 bool "Automatic process group scheduling"
1024 select FAIR_GROUP_SCHED
1026 This option optimizes the scheduler for common desktop workloads by
1027 automatically creating and populating task groups. This separation
1028 of workloads isolates aggressive CPU burners (like build jobs) from
1029 desktop applications. Task group autogeneration is currently based
1032 config SYSFS_DEPRECATED
1033 bool "Enable deprecated sysfs features to support old userspace tools"
1037 This option adds code that switches the layout of the "block" class
1038 devices, to not show up in /sys/class/block/, but only in
1041 This switch is only active when the sysfs.deprecated=1 boot option is
1042 passed or the SYSFS_DEPRECATED_V2 option is set.
1044 This option allows new kernels to run on old distributions and tools,
1045 which might get confused by /sys/class/block/. Since 2007/2008 all
1046 major distributions and tools handle this just fine.
1048 Recent distributions and userspace tools after 2009/2010 depend on
1049 the existence of /sys/class/block/, and will not work with this
1052 Only if you are using a new kernel on an old distribution, you might
1055 config SYSFS_DEPRECATED_V2
1056 bool "Enable deprecated sysfs features by default"
1059 depends on SYSFS_DEPRECATED
1061 Enable deprecated sysfs by default.
1063 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1066 Only if you are using a new kernel on an old distribution, you might
1067 need to say Y here. Even then, odds are you would not need it
1068 enabled, you can always pass the boot option if absolutely necessary.
1071 bool "Kernel->user space relay support (formerly relayfs)"
1074 This option enables support for relay interface support in
1075 certain file systems (such as debugfs).
1076 It is designed to provide an efficient mechanism for tools and
1077 facilities to relay large amounts of data from kernel space to
1082 config BLK_DEV_INITRD
1083 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1085 The initial RAM filesystem is a ramfs which is loaded by the
1086 boot loader (loadlin or lilo) and that is mounted as root
1087 before the normal boot procedure. It is typically used to
1088 load modules needed to mount the "real" root file system,
1089 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1091 If RAM disk support (BLK_DEV_RAM) is also included, this
1092 also enables initial RAM disk (initrd) support and adds
1093 15 Kbytes (more on some other architectures) to the kernel size.
1099 source "usr/Kconfig"
1104 prompt "Compiler optimization level"
1105 default CC_OPTIMIZE_FOR_PERFORMANCE
1107 config CC_OPTIMIZE_FOR_PERFORMANCE
1108 bool "Optimize for performance"
1110 This is the default optimization level for the kernel, building
1111 with the "-O2" compiler flag for best performance and most
1112 helpful compile-time warnings.
1114 config CC_OPTIMIZE_FOR_SIZE
1115 bool "Optimize for size"
1117 Enabling this option will pass "-Os" instead of "-O2" to
1118 your compiler resulting in a smaller kernel.
1124 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1127 This requires that the arch annotates or otherwise protects
1128 its external entry points from being discarded. Linker scripts
1129 must also merge .text.*, .data.*, and .bss.* correctly into
1130 output sections. Care must be taken not to pull in unrelated
1131 sections (e.g., '.text.init'). Typically '.' in section names
1132 is used to distinguish them from label names / C identifiers.
1134 config LD_DEAD_CODE_DATA_ELIMINATION
1135 bool "Dead code and data elimination (EXPERIMENTAL)"
1136 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1138 depends on !(FUNCTION_TRACER && CC_IS_GCC && GCC_VERSION < 40800)
1139 depends on $(cc-option,-ffunction-sections -fdata-sections)
1140 depends on $(ld-option,--gc-sections)
1142 Enable this if you want to do dead code and data elimination with
1143 the linker by compiling with -ffunction-sections -fdata-sections,
1144 and linking with --gc-sections.
1146 This can reduce on disk and in-memory size of the kernel
1147 code and static data, particularly for small configs and
1148 on small systems. This has the possibility of introducing
1149 silently broken kernel if the required annotations are not
1150 present. This option is not well tested yet, so use at your
1162 config SYSCTL_EXCEPTION_TRACE
1165 Enable support for /proc/sys/debug/exception-trace.
1167 config SYSCTL_ARCH_UNALIGN_NO_WARN
1170 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1171 Allows arch to define/use @no_unaligned_warning to possibly warn
1172 about unaligned access emulation going on under the hood.
1174 config SYSCTL_ARCH_UNALIGN_ALLOW
1177 Enable support for /proc/sys/kernel/unaligned-trap
1178 Allows arches to define/use @unaligned_enabled to runtime toggle
1179 the unaligned access emulation.
1180 see arch/parisc/kernel/unaligned.c for reference
1182 config HAVE_PCSPKR_PLATFORM
1185 # interpreter that classic socket filters depend on
1190 bool "Configure standard kernel features (expert users)"
1191 # Unhide debug options, to make the on-by-default options visible
1194 This option allows certain base kernel options and settings
1195 to be disabled or tweaked. This is for specialized
1196 environments which can tolerate a "non-standard" kernel.
1197 Only use this if you really know what you are doing.
1200 bool "Enable 16-bit UID system calls" if EXPERT
1201 depends on HAVE_UID16 && MULTIUSER
1204 This enables the legacy 16-bit UID syscall wrappers.
1207 bool "Multiple users, groups and capabilities support" if EXPERT
1210 This option enables support for non-root users, groups and
1213 If you say N here, all processes will run with UID 0, GID 0, and all
1214 possible capabilities. Saying N here also compiles out support for
1215 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1218 If unsure, say Y here.
1220 config SGETMASK_SYSCALL
1221 bool "sgetmask/ssetmask syscalls support" if EXPERT
1222 def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1224 sys_sgetmask and sys_ssetmask are obsolete system calls
1225 no longer supported in libc but still enabled by default in some
1228 If unsure, leave the default option here.
1230 config SYSFS_SYSCALL
1231 bool "Sysfs syscall support" if EXPERT
1234 sys_sysfs is an obsolete system call no longer supported in libc.
1235 Note that disabling this option is more secure but might break
1236 compatibility with some systems.
1238 If unsure say Y here.
1240 config SYSCTL_SYSCALL
1241 bool "Sysctl syscall support" if EXPERT
1242 depends on PROC_SYSCTL
1246 sys_sysctl uses binary paths that have been found challenging
1247 to properly maintain and use. The interface in /proc/sys
1248 using paths with ascii names is now the primary path to this
1251 Almost nothing using the binary sysctl interface so if you are
1252 trying to save some space it is probably safe to disable this,
1253 making your kernel marginally smaller.
1255 If unsure say N here.
1258 bool "open by fhandle syscalls" if EXPERT
1262 If you say Y here, a user level program will be able to map
1263 file names to handle and then later use the handle for
1264 different file system operations. This is useful in implementing
1265 userspace file servers, which now track files using handles instead
1266 of names. The handle would remain the same even if file names
1267 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1271 bool "Posix Clocks & timers" if EXPERT
1274 This includes native support for POSIX timers to the kernel.
1275 Some embedded systems have no use for them and therefore they
1276 can be configured out to reduce the size of the kernel image.
1278 When this option is disabled, the following syscalls won't be
1279 available: timer_create, timer_gettime: timer_getoverrun,
1280 timer_settime, timer_delete, clock_adjtime, getitimer,
1281 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1282 clock_getres and clock_nanosleep syscalls will be limited to
1283 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1289 bool "Enable support for printk" if EXPERT
1292 This option enables normal printk support. Removing it
1293 eliminates most of the message strings from the kernel image
1294 and makes the kernel more or less silent. As this makes it
1295 very difficult to diagnose system problems, saying N here is
1296 strongly discouraged.
1304 bool "BUG() support" if EXPERT
1307 Disabling this option eliminates support for BUG and WARN, reducing
1308 the size of your kernel image and potentially quietly ignoring
1309 numerous fatal conditions. You should only consider disabling this
1310 option for embedded systems with no facilities for reporting errors.
1316 bool "Enable ELF core dumps" if EXPERT
1318 Enable support for generating core dumps. Disabling saves about 4k.
1321 config PCSPKR_PLATFORM
1322 bool "Enable PC-Speaker support" if EXPERT
1323 depends on HAVE_PCSPKR_PLATFORM
1327 This option allows to disable the internal PC-Speaker
1328 support, saving some memory.
1332 bool "Enable full-sized data structures for core" if EXPERT
1334 Disabling this option reduces the size of miscellaneous core
1335 kernel data structures. This saves memory on small machines,
1336 but may reduce performance.
1339 bool "Enable futex support" if EXPERT
1343 Disabling this option will cause the kernel to be built without
1344 support for "fast userspace mutexes". The resulting kernel may not
1345 run glibc-based applications correctly.
1349 depends on FUTEX && RT_MUTEXES
1352 config HAVE_FUTEX_CMPXCHG
1356 Architectures should select this if futex_atomic_cmpxchg_inatomic()
1357 is implemented and always working. This removes a couple of runtime
1361 bool "Enable eventpoll support" if EXPERT
1365 Disabling this option will cause the kernel to be built without
1366 support for epoll family of system calls.
1369 bool "Enable signalfd() system call" if EXPERT
1373 Enable the signalfd() system call that allows to receive signals
1374 on a file descriptor.
1379 bool "Enable timerfd() system call" if EXPERT
1383 Enable the timerfd() system call that allows to receive timer
1384 events on a file descriptor.
1389 bool "Enable eventfd() system call" if EXPERT
1393 Enable the eventfd() system call that allows to receive both
1394 kernel notification (ie. KAIO) or userspace notifications.
1399 bool "Use full shmem filesystem" if EXPERT
1403 The shmem is an internal filesystem used to manage shared memory.
1404 It is backed by swap and manages resource limits. It is also exported
1405 to userspace as tmpfs if TMPFS is enabled. Disabling this
1406 option replaces shmem and tmpfs with the much simpler ramfs code,
1407 which may be appropriate on small systems without swap.
1410 bool "Enable AIO support" if EXPERT
1413 This option enables POSIX asynchronous I/O which may by used
1414 by some high performance threaded applications. Disabling
1415 this option saves about 7k.
1417 config ADVISE_SYSCALLS
1418 bool "Enable madvise/fadvise syscalls" if EXPERT
1421 This option enables the madvise and fadvise syscalls, used by
1422 applications to advise the kernel about their future memory or file
1423 usage, improving performance. If building an embedded system where no
1424 applications use these syscalls, you can disable this option to save
1428 bool "Enable membarrier() system call" if EXPERT
1431 Enable the membarrier() system call that allows issuing memory
1432 barriers across all running threads, which can be used to distribute
1433 the cost of user-space memory barriers asymmetrically by transforming
1434 pairs of memory barriers into pairs consisting of membarrier() and a
1440 bool "Load all symbols for debugging/ksymoops" if EXPERT
1443 Say Y here to let the kernel print out symbolic crash information and
1444 symbolic stack backtraces. This increases the size of the kernel
1445 somewhat, as all symbols have to be loaded into the kernel image.
1448 bool "Include all symbols in kallsyms"
1449 depends on DEBUG_KERNEL && KALLSYMS
1451 Normally kallsyms only contains the symbols of functions for nicer
1452 OOPS messages and backtraces (i.e., symbols from the text and inittext
1453 sections). This is sufficient for most cases. And only in very rare
1454 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1455 names of variables from the data sections, etc).
1457 This option makes sure that all symbols are loaded into the kernel
1458 image (i.e., symbols from all sections) in cost of increased kernel
1459 size (depending on the kernel configuration, it may be 300KiB or
1460 something like this).
1462 Say N unless you really need all symbols.
1464 config KALLSYMS_ABSOLUTE_PERCPU
1467 default X86_64 && SMP
1469 config KALLSYMS_BASE_RELATIVE
1474 Instead of emitting them as absolute values in the native word size,
1475 emit the symbol references in the kallsyms table as 32-bit entries,
1476 each containing a relative value in the range [base, base + U32_MAX]
1477 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1478 an absolute value in the range [0, S32_MAX] or a relative value in the
1479 range [base, base + S32_MAX], where base is the lowest relative symbol
1480 address encountered in the image.
1482 On 64-bit builds, this reduces the size of the address table by 50%,
1483 but more importantly, it results in entries whose values are build
1484 time constants, and no relocation pass is required at runtime to fix
1485 up the entries based on the runtime load address of the kernel.
1487 # end of the "standard kernel features (expert users)" menu
1489 # syscall, maps, verifier
1491 bool "Enable bpf() system call"
1497 Enable the bpf() system call that allows to manipulate eBPF
1498 programs and maps via file descriptors.
1500 config BPF_JIT_ALWAYS_ON
1501 bool "Permanently enable BPF JIT and remove BPF interpreter"
1502 depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
1504 Enables BPF JIT and removes BPF interpreter to avoid
1505 speculative execution of BPF instructions by the interpreter
1508 bool "Enable userfaultfd() system call"
1512 Enable the userfaultfd() system call that allows to intercept and
1513 handle page faults in userland.
1515 config ARCH_HAS_MEMBARRIER_CALLBACKS
1518 config ARCH_HAS_MEMBARRIER_SYNC_CORE
1522 bool "Enable rseq() system call" if EXPERT
1524 depends on HAVE_RSEQ
1527 Enable the restartable sequences system call. It provides a
1528 user-space cache for the current CPU number value, which
1529 speeds up getting the current CPU number from user-space,
1530 as well as an ABI to speed up user-space operations on
1537 bool "Enabled debugging of rseq() system call" if EXPERT
1538 depends on RSEQ && DEBUG_KERNEL
1540 Enable extra debugging checks for the rseq system call.
1545 bool "Embedded system"
1546 option allnoconfig_y
1549 This option should be enabled if compiling the kernel for
1550 an embedded system so certain expert options are available
1553 config HAVE_PERF_EVENTS
1556 See tools/perf/design.txt for details.
1558 config PERF_USE_VMALLOC
1561 See tools/perf/design.txt for details
1564 bool "PC/104 support" if EXPERT
1566 Expose PC/104 form factor device drivers and options available for
1567 selection and configuration. Enable this option if your target
1568 machine has a PC/104 bus.
1570 menu "Kernel Performance Events And Counters"
1573 bool "Kernel performance events and counters"
1574 default y if PROFILING
1575 depends on HAVE_PERF_EVENTS
1580 Enable kernel support for various performance events provided
1581 by software and hardware.
1583 Software events are supported either built-in or via the
1584 use of generic tracepoints.
1586 Most modern CPUs support performance events via performance
1587 counter registers. These registers count the number of certain
1588 types of hw events: such as instructions executed, cachemisses
1589 suffered, or branches mis-predicted - without slowing down the
1590 kernel or applications. These registers can also trigger interrupts
1591 when a threshold number of events have passed - and can thus be
1592 used to profile the code that runs on that CPU.
1594 The Linux Performance Event subsystem provides an abstraction of
1595 these software and hardware event capabilities, available via a
1596 system call and used by the "perf" utility in tools/perf/. It
1597 provides per task and per CPU counters, and it provides event
1598 capabilities on top of those.
1602 config DEBUG_PERF_USE_VMALLOC
1604 bool "Debug: use vmalloc to back perf mmap() buffers"
1605 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1606 select PERF_USE_VMALLOC
1608 Use vmalloc memory to back perf mmap() buffers.
1610 Mostly useful for debugging the vmalloc code on platforms
1611 that don't require it.
1617 config VM_EVENT_COUNTERS
1619 bool "Enable VM event counters for /proc/vmstat" if EXPERT
1621 VM event counters are needed for event counts to be shown.
1622 This option allows the disabling of the VM event counters
1623 on EXPERT systems. /proc/vmstat will only show page counts
1624 if VM event counters are disabled.
1628 bool "Enable SLUB debugging support" if EXPERT
1629 depends on SLUB && SYSFS
1631 SLUB has extensive debug support features. Disabling these can
1632 result in significant savings in code size. This also disables
1633 SLUB sysfs support. /sys/slab will not exist and there will be
1634 no support for cache validation etc.
1636 config SLUB_MEMCG_SYSFS_ON
1638 bool "Enable memcg SLUB sysfs support by default" if EXPERT
1639 depends on SLUB && SYSFS && MEMCG
1641 SLUB creates a directory under /sys/kernel/slab for each
1642 allocation cache to host info and debug files. If memory
1643 cgroup is enabled, each cache can have per memory cgroup
1644 caches. SLUB can create the same sysfs directories for these
1645 caches under /sys/kernel/slab/CACHE/cgroup but it can lead
1646 to a very high number of debug files being created. This is
1647 controlled by slub_memcg_sysfs boot parameter and this
1648 config option determines the parameter's default value.
1651 bool "Disable heap randomization"
1654 Randomizing heap placement makes heap exploits harder, but it
1655 also breaks ancient binaries (including anything libc5 based).
1656 This option changes the bootup default to heap randomization
1657 disabled, and can be overridden at runtime by setting
1658 /proc/sys/kernel/randomize_va_space to 2.
1660 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1663 prompt "Choose SLAB allocator"
1666 This option allows to select a slab allocator.
1670 select HAVE_HARDENED_USERCOPY_ALLOCATOR
1672 The regular slab allocator that is established and known to work
1673 well in all environments. It organizes cache hot objects in
1674 per cpu and per node queues.
1677 bool "SLUB (Unqueued Allocator)"
1678 select HAVE_HARDENED_USERCOPY_ALLOCATOR
1680 SLUB is a slab allocator that minimizes cache line usage
1681 instead of managing queues of cached objects (SLAB approach).
1682 Per cpu caching is realized using slabs of objects instead
1683 of queues of objects. SLUB can use memory efficiently
1684 and has enhanced diagnostics. SLUB is the default choice for
1689 bool "SLOB (Simple Allocator)"
1691 SLOB replaces the stock allocator with a drastically simpler
1692 allocator. SLOB is generally more space efficient but
1693 does not perform as well on large systems.
1697 config SLAB_MERGE_DEFAULT
1698 bool "Allow slab caches to be merged"
1701 For reduced kernel memory fragmentation, slab caches can be
1702 merged when they share the same size and other characteristics.
1703 This carries a risk of kernel heap overflows being able to
1704 overwrite objects from merged caches (and more easily control
1705 cache layout), which makes such heap attacks easier to exploit
1706 by attackers. By keeping caches unmerged, these kinds of exploits
1707 can usually only damage objects in the same cache. To disable
1708 merging at runtime, "slab_nomerge" can be passed on the kernel
1711 config SLAB_FREELIST_RANDOM
1713 depends on SLAB || SLUB
1714 bool "SLAB freelist randomization"
1716 Randomizes the freelist order used on creating new pages. This
1717 security feature reduces the predictability of the kernel slab
1718 allocator against heap overflows.
1720 config SLAB_FREELIST_HARDENED
1721 bool "Harden slab freelist metadata"
1724 Many kernel heap attacks try to target slab cache metadata and
1725 other infrastructure. This options makes minor performance
1726 sacrifies to harden the kernel slab allocator against common
1727 freelist exploit methods.
1729 config SLUB_CPU_PARTIAL
1731 depends on SLUB && SMP
1732 bool "SLUB per cpu partial cache"
1734 Per cpu partial caches accellerate objects allocation and freeing
1735 that is local to a processor at the price of more indeterminism
1736 in the latency of the free. On overflow these caches will be cleared
1737 which requires the taking of locks that may cause latency spikes.
1738 Typically one would choose no for a realtime system.
1740 config MMAP_ALLOW_UNINITIALIZED
1741 bool "Allow mmapped anonymous memory to be uninitialized"
1742 depends on EXPERT && !MMU
1745 Normally, and according to the Linux spec, anonymous memory obtained
1746 from mmap() has its contents cleared before it is passed to
1747 userspace. Enabling this config option allows you to request that
1748 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1749 providing a huge performance boost. If this option is not enabled,
1750 then the flag will be ignored.
1752 This is taken advantage of by uClibc's malloc(), and also by
1753 ELF-FDPIC binfmt's brk and stack allocator.
1755 Because of the obvious security issues, this option should only be
1756 enabled on embedded devices where you control what is run in
1757 userspace. Since that isn't generally a problem on no-MMU systems,
1758 it is normally safe to say Y here.
1760 See Documentation/nommu-mmap.txt for more information.
1762 config SYSTEM_DATA_VERIFICATION
1764 select SYSTEM_TRUSTED_KEYRING
1768 select ASYMMETRIC_KEY_TYPE
1769 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1772 select X509_CERTIFICATE_PARSER
1773 select PKCS7_MESSAGE_PARSER
1775 Provide PKCS#7 message verification using the contents of the system
1776 trusted keyring to provide public keys. This then can be used for
1777 module verification, kexec image verification and firmware blob
1781 bool "Profiling support"
1783 Say Y here to enable the extended profiling support mechanisms used
1784 by profilers such as OProfile.
1787 # Place an empty function call at each tracepoint site. Can be
1788 # dynamically changed for a probe function.
1793 endmenu # General setup
1795 source "arch/Kconfig"
1802 default 0 if BASE_FULL
1803 default 1 if !BASE_FULL
1806 bool "Enable loadable module support"
1809 Kernel modules are small pieces of compiled code which can
1810 be inserted in the running kernel, rather than being
1811 permanently built into the kernel. You use the "modprobe"
1812 tool to add (and sometimes remove) them. If you say Y here,
1813 many parts of the kernel can be built as modules (by
1814 answering M instead of Y where indicated): this is most
1815 useful for infrequently used options which are not required
1816 for booting. For more information, see the man pages for
1817 modprobe, lsmod, modinfo, insmod and rmmod.
1819 If you say Y here, you will need to run "make
1820 modules_install" to put the modules under /lib/modules/
1821 where modprobe can find them (you may need to be root to do
1828 config MODULE_FORCE_LOAD
1829 bool "Forced module loading"
1832 Allow loading of modules without version information (ie. modprobe
1833 --force). Forced module loading sets the 'F' (forced) taint flag and
1834 is usually a really bad idea.
1836 config MODULE_UNLOAD
1837 bool "Module unloading"
1839 Without this option you will not be able to unload any
1840 modules (note that some modules may not be unloadable
1841 anyway), which makes your kernel smaller, faster
1842 and simpler. If unsure, say Y.
1844 config MODULE_FORCE_UNLOAD
1845 bool "Forced module unloading"
1846 depends on MODULE_UNLOAD
1848 This option allows you to force a module to unload, even if the
1849 kernel believes it is unsafe: the kernel will remove the module
1850 without waiting for anyone to stop using it (using the -f option to
1851 rmmod). This is mainly for kernel developers and desperate users.
1855 bool "Module versioning support"
1857 Usually, you have to use modules compiled with your kernel.
1858 Saying Y here makes it sometimes possible to use modules
1859 compiled for different kernels, by adding enough information
1860 to the modules to (hopefully) spot any changes which would
1861 make them incompatible with the kernel you are running. If
1864 config MODULE_REL_CRCS
1866 depends on MODVERSIONS
1868 config MODULE_SRCVERSION_ALL
1869 bool "Source checksum for all modules"
1871 Modules which contain a MODULE_VERSION get an extra "srcversion"
1872 field inserted into their modinfo section, which contains a
1873 sum of the source files which made it. This helps maintainers
1874 see exactly which source was used to build a module (since
1875 others sometimes change the module source without updating
1876 the version). With this option, such a "srcversion" field
1877 will be created for all modules. If unsure, say N.
1880 bool "Module signature verification"
1882 select SYSTEM_DATA_VERIFICATION
1884 Check modules for valid signatures upon load: the signature
1885 is simply appended to the module. For more information see
1886 <file:Documentation/admin-guide/module-signing.rst>.
1888 Note that this option adds the OpenSSL development packages as a
1889 kernel build dependency so that the signing tool can use its crypto
1892 !!!WARNING!!! If you enable this option, you MUST make sure that the
1893 module DOES NOT get stripped after being signed. This includes the
1894 debuginfo strip done by some packagers (such as rpmbuild) and
1895 inclusion into an initramfs that wants the module size reduced.
1897 config MODULE_SIG_FORCE
1898 bool "Require modules to be validly signed"
1899 depends on MODULE_SIG
1901 Reject unsigned modules or signed modules for which we don't have a
1902 key. Without this, such modules will simply taint the kernel.
1904 config MODULE_SIG_ALL
1905 bool "Automatically sign all modules"
1907 depends on MODULE_SIG
1909 Sign all modules during make modules_install. Without this option,
1910 modules must be signed manually, using the scripts/sign-file tool.
1912 comment "Do not forget to sign required modules with scripts/sign-file"
1913 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
1916 prompt "Which hash algorithm should modules be signed with?"
1917 depends on MODULE_SIG
1919 This determines which sort of hashing algorithm will be used during
1920 signature generation. This algorithm _must_ be built into the kernel
1921 directly so that signature verification can take place. It is not
1922 possible to load a signed module containing the algorithm to check
1923 the signature on that module.
1925 config MODULE_SIG_SHA1
1926 bool "Sign modules with SHA-1"
1929 config MODULE_SIG_SHA224
1930 bool "Sign modules with SHA-224"
1931 select CRYPTO_SHA256
1933 config MODULE_SIG_SHA256
1934 bool "Sign modules with SHA-256"
1935 select CRYPTO_SHA256
1937 config MODULE_SIG_SHA384
1938 bool "Sign modules with SHA-384"
1939 select CRYPTO_SHA512
1941 config MODULE_SIG_SHA512
1942 bool "Sign modules with SHA-512"
1943 select CRYPTO_SHA512
1947 config MODULE_SIG_HASH
1949 depends on MODULE_SIG
1950 default "sha1" if MODULE_SIG_SHA1
1951 default "sha224" if MODULE_SIG_SHA224
1952 default "sha256" if MODULE_SIG_SHA256
1953 default "sha384" if MODULE_SIG_SHA384
1954 default "sha512" if MODULE_SIG_SHA512
1956 config MODULE_COMPRESS
1957 bool "Compress modules on installation"
1961 Compresses kernel modules when 'make modules_install' is run; gzip or
1962 xz depending on "Compression algorithm" below.
1964 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
1966 Out-of-tree kernel modules installed using Kbuild will also be
1967 compressed upon installation.
1969 Note: for modules inside an initrd or initramfs, it's more efficient
1970 to compress the whole initrd or initramfs instead.
1972 Note: This is fully compatible with signed modules.
1977 prompt "Compression algorithm"
1978 depends on MODULE_COMPRESS
1979 default MODULE_COMPRESS_GZIP
1981 This determines which sort of compression will be used during
1982 'make modules_install'.
1984 GZIP (default) and XZ are supported.
1986 config MODULE_COMPRESS_GZIP
1989 config MODULE_COMPRESS_XZ
1994 config TRIM_UNUSED_KSYMS
1995 bool "Trim unused exported kernel symbols"
1996 depends on MODULES && !UNUSED_SYMBOLS
1998 The kernel and some modules make many symbols available for
1999 other modules to use via EXPORT_SYMBOL() and variants. Depending
2000 on the set of modules being selected in your kernel configuration,
2001 many of those exported symbols might never be used.
2003 This option allows for unused exported symbols to be dropped from
2004 the build. In turn, this provides the compiler more opportunities
2005 (especially when using LTO) for optimizing the code and reducing
2006 binary size. This might have some security advantages as well.
2008 If unsure, or if you need to build out-of-tree modules, say N.
2012 config MODULES_TREE_LOOKUP
2014 depends on PERF_EVENTS || TRACING
2016 config INIT_ALL_POSSIBLE
2019 Back when each arch used to define their own cpu_online_mask and
2020 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2021 with all 1s, and others with all 0s. When they were centralised,
2022 it was better to provide this option than to break all the archs
2023 and have several arch maintainers pursuing me down dark alleys.
2025 source "block/Kconfig"
2027 config PREEMPT_NOTIFIERS
2037 Build a simple ASN.1 grammar compiler that produces a bytecode output
2038 that can be interpreted by the ASN.1 stream decoder and used to
2039 inform it as to what tags are to be expected in a stream and what
2040 functions to call on what tags.
2042 source "kernel/Kconfig.locks"
2044 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2047 # It may be useful for an architecture to override the definitions of the
2048 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2049 # and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2050 # different calling convention for syscalls. They can also override the
2051 # macros for not-implemented syscalls in kernel/sys_ni.c and
2052 # kernel/time/posix-stubs.c. All these overrides need to be available in
2053 # <asm/syscall_wrapper.h>.
2054 config ARCH_HAS_SYSCALL_WRAPPER
git.samba.org / sfrench / cifs-2.6.git / blob