7 option env="KERNELVERSION"
13 default "/lib/modules/$UNAME_RELEASE/.config"
14 default "/etc/kernel-config"
15 default "/boot/config-$UNAME_RELEASE"
16 default "$ARCH_DEFCONFIG"
17 default "arch/$ARCH/defconfig"
26 config BUILDTIME_EXTABLE_SORT
29 config THREAD_INFO_IN_TASK
32 Select this to move thread_info off the stack into task_struct. To
33 make this work, an arch will need to remove all thread_info fields
34 except flags and fix any runtime bugs.
36 One subtle change that will be needed is to use try_get_task_stack()
37 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
46 depends on BROKEN || !SMP
49 config INIT_ENV_ARG_LIMIT
54 Maximum of each of the number of arguments and environment
55 variables passed to init from the kernel command line.
59 string "Cross-compiler tool prefix"
61 Same as running 'make CROSS_COMPILE=prefix-' but stored for
62 default make runs in this kernel build directory. You don't
63 need to set this unless you want the configured kernel build
64 directory to select the cross-compiler automatically.
67 bool "Compile also drivers which will not load"
71 Some drivers can be compiled on a different platform than they are
72 intended to be run on. Despite they cannot be loaded there (or even
73 when they load they cannot be used due to missing HW support),
74 developers still, opposing to distributors, might want to build such
75 drivers to compile-test them.
77 If you are a developer and want to build everything available, say Y
78 here. If you are a user/distributor, say N here to exclude useless
79 drivers to be distributed.
82 string "Local version - append to kernel release"
84 Append an extra string to the end of your kernel version.
85 This will show up when you type uname, for example.
86 The string you set here will be appended after the contents of
87 any files with a filename matching localversion* in your
88 object and source tree, in that order. Your total string can
89 be a maximum of 64 characters.
91 config LOCALVERSION_AUTO
92 bool "Automatically append version information to the version string"
94 depends on !COMPILE_TEST
96 This will try to automatically determine if the current tree is a
97 release tree by looking for git tags that belong to the current
100 A string of the format -gxxxxxxxx will be added to the localversion
101 if a git-based tree is found. The string generated by this will be
102 appended after any matching localversion* files, and after the value
103 set in CONFIG_LOCALVERSION.
105 (The actual string used here is the first eight characters produced
106 by running the command:
108 $ git rev-parse --verify HEAD
110 which is done within the script "scripts/setlocalversion".)
112 config HAVE_KERNEL_GZIP
115 config HAVE_KERNEL_BZIP2
118 config HAVE_KERNEL_LZMA
121 config HAVE_KERNEL_XZ
124 config HAVE_KERNEL_LZO
127 config HAVE_KERNEL_LZ4
131 prompt "Kernel compression mode"
133 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4
135 The linux kernel is a kind of self-extracting executable.
136 Several compression algorithms are available, which differ
137 in efficiency, compression and decompression speed.
138 Compression speed is only relevant when building a kernel.
139 Decompression speed is relevant at each boot.
141 If you have any problems with bzip2 or lzma compressed
143 version of this functionality (bzip2 only), for 2.4, was
144 supplied by Christian Ludwig)
146 High compression options are mostly useful for users, who
147 are low on disk space (embedded systems), but for whom ram
150 If in doubt, select 'gzip'
154 depends on HAVE_KERNEL_GZIP
156 The old and tried gzip compression. It provides a good balance
157 between compression ratio and decompression speed.
161 depends on HAVE_KERNEL_BZIP2
163 Its compression ratio and speed is intermediate.
164 Decompression speed is slowest among the choices. The kernel
165 size is about 10% smaller with bzip2, in comparison to gzip.
166 Bzip2 uses a large amount of memory. For modern kernels you
167 will need at least 8MB RAM or more for booting.
171 depends on HAVE_KERNEL_LZMA
173 This compression algorithm's ratio is best. Decompression speed
174 is between gzip and bzip2. Compression is slowest.
175 The kernel size is about 33% smaller with LZMA in comparison to gzip.
179 depends on HAVE_KERNEL_XZ
181 XZ uses the LZMA2 algorithm and instruction set specific
182 BCJ filters which can improve compression ratio of executable
183 code. The size of the kernel is about 30% smaller with XZ in
184 comparison to gzip. On architectures for which there is a BCJ
185 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
186 will create a few percent smaller kernel than plain LZMA.
188 The speed is about the same as with LZMA: The decompression
189 speed of XZ is better than that of bzip2 but worse than gzip
190 and LZO. Compression is slow.
194 depends on HAVE_KERNEL_LZO
196 Its compression ratio is the poorest among the choices. The kernel
197 size is about 10% bigger than gzip; however its speed
198 (both compression and decompression) is the fastest.
202 depends on HAVE_KERNEL_LZ4
204 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
205 A preliminary version of LZ4 de/compression tool is available at
206 <https://code.google.com/p/lz4/>.
208 Its compression ratio is worse than LZO. The size of the kernel
209 is about 8% bigger than LZO. But the decompression speed is
214 config DEFAULT_HOSTNAME
215 string "Default hostname"
218 This option determines the default system hostname before userspace
219 calls sethostname(2). The kernel traditionally uses "(none)" here,
220 but you may wish to use a different default here to make a minimal
221 system more usable with less configuration.
224 bool "Support for paging of anonymous memory (swap)"
225 depends on MMU && BLOCK
228 This option allows you to choose whether you want to have support
229 for so called swap devices or swap files in your kernel that are
230 used to provide more virtual memory than the actual RAM present
231 in your computer. If unsure say Y.
236 Inter Process Communication is a suite of library functions and
237 system calls which let processes (running programs) synchronize and
238 exchange information. It is generally considered to be a good thing,
239 and some programs won't run unless you say Y here. In particular, if
240 you want to run the DOS emulator dosemu under Linux (read the
241 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
242 you'll need to say Y here.
244 You can find documentation about IPC with "info ipc" and also in
245 section 6.4 of the Linux Programmer's Guide, available from
246 <http://www.tldp.org/guides.html>.
248 config SYSVIPC_SYSCTL
255 bool "POSIX Message Queues"
258 POSIX variant of message queues is a part of IPC. In POSIX message
259 queues every message has a priority which decides about succession
260 of receiving it by a process. If you want to compile and run
261 programs written e.g. for Solaris with use of its POSIX message
262 queues (functions mq_*) say Y here.
264 POSIX message queues are visible as a filesystem called 'mqueue'
265 and can be mounted somewhere if you want to do filesystem
266 operations on message queues.
270 config POSIX_MQUEUE_SYSCTL
272 depends on POSIX_MQUEUE
276 config CROSS_MEMORY_ATTACH
277 bool "Enable process_vm_readv/writev syscalls"
281 Enabling this option adds the system calls process_vm_readv and
282 process_vm_writev which allow a process with the correct privileges
283 to directly read from or write to another process' address space.
284 See the man page for more details.
287 bool "open by fhandle syscalls" if EXPERT
291 If you say Y here, a user level program will be able to map
292 file names to handle and then later use the handle for
293 different file system operations. This is useful in implementing
294 userspace file servers, which now track files using handles instead
295 of names. The handle would remain the same even if file names
296 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
300 bool "uselib syscall"
301 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
303 This option enables the uselib syscall, a system call used in the
304 dynamic linker from libc5 and earlier. glibc does not use this
305 system call. If you intend to run programs built on libc5 or
306 earlier, you may need to enable this syscall. Current systems
307 running glibc can safely disable this.
310 bool "Auditing support"
313 Enable auditing infrastructure that can be used with another
314 kernel subsystem, such as SELinux (which requires this for
315 logging of avc messages output). System call auditing is included
316 on architectures which support it.
318 config HAVE_ARCH_AUDITSYSCALL
323 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
327 depends on AUDITSYSCALL
332 depends on AUDITSYSCALL
335 source "kernel/irq/Kconfig"
336 source "kernel/time/Kconfig"
338 menu "CPU/Task time and stats accounting"
340 config VIRT_CPU_ACCOUNTING
344 prompt "Cputime accounting"
345 default TICK_CPU_ACCOUNTING if !PPC64
346 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
348 # Kind of a stub config for the pure tick based cputime accounting
349 config TICK_CPU_ACCOUNTING
350 bool "Simple tick based cputime accounting"
351 depends on !S390 && !NO_HZ_FULL
353 This is the basic tick based cputime accounting that maintains
354 statistics about user, system and idle time spent on per jiffies
359 config VIRT_CPU_ACCOUNTING_NATIVE
360 bool "Deterministic task and CPU time accounting"
361 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
362 select VIRT_CPU_ACCOUNTING
364 Select this option to enable more accurate task and CPU time
365 accounting. This is done by reading a CPU counter on each
366 kernel entry and exit and on transitions within the kernel
367 between system, softirq and hardirq state, so there is a
368 small performance impact. In the case of s390 or IBM POWER > 5,
369 this also enables accounting of stolen time on logically-partitioned
372 config VIRT_CPU_ACCOUNTING_GEN
373 bool "Full dynticks CPU time accounting"
374 depends on HAVE_CONTEXT_TRACKING
375 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
376 select VIRT_CPU_ACCOUNTING
377 select CONTEXT_TRACKING
379 Select this option to enable task and CPU time accounting on full
380 dynticks systems. This accounting is implemented by watching every
381 kernel-user boundaries using the context tracking subsystem.
382 The accounting is thus performed at the expense of some significant
385 For now this is only useful if you are working on the full
386 dynticks subsystem development.
392 config IRQ_TIME_ACCOUNTING
393 bool "Fine granularity task level IRQ time accounting"
394 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
396 Select this option to enable fine granularity task irq time
397 accounting. This is done by reading a timestamp on each
398 transitions between softirq and hardirq state, so there can be a
399 small performance impact.
401 If in doubt, say N here.
403 config BSD_PROCESS_ACCT
404 bool "BSD Process Accounting"
407 If you say Y here, a user level program will be able to instruct the
408 kernel (via a special system call) to write process accounting
409 information to a file: whenever a process exits, information about
410 that process will be appended to the file by the kernel. The
411 information includes things such as creation time, owning user,
412 command name, memory usage, controlling terminal etc. (the complete
413 list is in the struct acct in <file:include/linux/acct.h>). It is
414 up to the user level program to do useful things with this
415 information. This is generally a good idea, so say Y.
417 config BSD_PROCESS_ACCT_V3
418 bool "BSD Process Accounting version 3 file format"
419 depends on BSD_PROCESS_ACCT
422 If you say Y here, the process accounting information is written
423 in a new file format that also logs the process IDs of each
424 process and it's parent. Note that this file format is incompatible
425 with previous v0/v1/v2 file formats, so you will need updated tools
426 for processing it. A preliminary version of these tools is available
427 at <http://www.gnu.org/software/acct/>.
430 bool "Export task/process statistics through netlink"
435 Export selected statistics for tasks/processes through the
436 generic netlink interface. Unlike BSD process accounting, the
437 statistics are available during the lifetime of tasks/processes as
438 responses to commands. Like BSD accounting, they are sent to user
443 config TASK_DELAY_ACCT
444 bool "Enable per-task delay accounting"
448 Collect information on time spent by a task waiting for system
449 resources like cpu, synchronous block I/O completion and swapping
450 in pages. Such statistics can help in setting a task's priorities
451 relative to other tasks for cpu, io, rss limits etc.
456 bool "Enable extended accounting over taskstats"
459 Collect extended task accounting data and send the data
460 to userland for processing over the taskstats interface.
464 config TASK_IO_ACCOUNTING
465 bool "Enable per-task storage I/O accounting"
466 depends on TASK_XACCT
468 Collect information on the number of bytes of storage I/O which this
473 endmenu # "CPU/Task time and stats accounting"
478 Make sure that CPUs running critical tasks are not disturbed by
479 any source of "noise" such as unbound workqueues, timers, kthreads...
480 Unbound jobs get offloaded to housekeeping CPUs.
482 source "kernel/rcu/Kconfig"
489 tristate "Kernel .config support"
492 This option enables the complete Linux kernel ".config" file
493 contents to be saved in the kernel. It provides documentation
494 of which kernel options are used in a running kernel or in an
495 on-disk kernel. This information can be extracted from the kernel
496 image file with the script scripts/extract-ikconfig and used as
497 input to rebuild the current kernel or to build another kernel.
498 It can also be extracted from a running kernel by reading
499 /proc/config.gz if enabled (below).
502 bool "Enable access to .config through /proc/config.gz"
503 depends on IKCONFIG && PROC_FS
505 This option enables access to the kernel configuration file
506 through /proc/config.gz.
509 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
514 Select the minimal kernel log buffer size as a power of 2.
515 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
516 parameter, see below. Any higher size also might be forced
517 by "log_buf_len" boot parameter.
527 config LOG_CPU_MAX_BUF_SHIFT
528 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
531 default 12 if !BASE_SMALL
532 default 0 if BASE_SMALL
535 This option allows to increase the default ring buffer size
536 according to the number of CPUs. The value defines the contribution
537 of each CPU as a power of 2. The used space is typically only few
538 lines however it might be much more when problems are reported,
541 The increased size means that a new buffer has to be allocated and
542 the original static one is unused. It makes sense only on systems
543 with more CPUs. Therefore this value is used only when the sum of
544 contributions is greater than the half of the default kernel ring
545 buffer as defined by LOG_BUF_SHIFT. The default values are set
546 so that more than 64 CPUs are needed to trigger the allocation.
548 Also this option is ignored when "log_buf_len" kernel parameter is
549 used as it forces an exact (power of two) size of the ring buffer.
551 The number of possible CPUs is used for this computation ignoring
552 hotplugging making the computation optimal for the worst case
553 scenario while allowing a simple algorithm to be used from bootup.
555 Examples shift values and their meaning:
556 17 => 128 KB for each CPU
557 16 => 64 KB for each CPU
558 15 => 32 KB for each CPU
559 14 => 16 KB for each CPU
560 13 => 8 KB for each CPU
561 12 => 4 KB for each CPU
563 config PRINTK_SAFE_LOG_BUF_SHIFT
564 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
569 Select the size of an alternate printk per-CPU buffer where messages
570 printed from usafe contexts are temporary stored. One example would
571 be NMI messages, another one - printk recursion. The messages are
572 copied to the main log buffer in a safe context to avoid a deadlock.
573 The value defines the size as a power of 2.
575 Those messages are rare and limited. The largest one is when
576 a backtrace is printed. It usually fits into 4KB. Select
577 8KB if you want to be on the safe side.
580 17 => 128 KB for each CPU
581 16 => 64 KB for each CPU
582 15 => 32 KB for each CPU
583 14 => 16 KB for each CPU
584 13 => 8 KB for each CPU
585 12 => 4 KB for each CPU
588 # Architectures with an unreliable sched_clock() should select this:
590 config HAVE_UNSTABLE_SCHED_CLOCK
593 config GENERIC_SCHED_CLOCK
597 # For architectures that want to enable the support for NUMA-affine scheduler
600 config ARCH_SUPPORTS_NUMA_BALANCING
604 # For architectures that prefer to flush all TLBs after a number of pages
605 # are unmapped instead of sending one IPI per page to flush. The architecture
606 # must provide guarantees on what happens if a clean TLB cache entry is
607 # written after the unmap. Details are in mm/rmap.c near the check for
608 # should_defer_flush. The architecture should also consider if the full flush
609 # and the refill costs are offset by the savings of sending fewer IPIs.
610 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
614 # For architectures that know their GCC __int128 support is sound
616 config ARCH_SUPPORTS_INT128
619 # For architectures that (ab)use NUMA to represent different memory regions
620 # all cpu-local but of different latencies, such as SuperH.
622 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
625 config NUMA_BALANCING
626 bool "Memory placement aware NUMA scheduler"
627 depends on ARCH_SUPPORTS_NUMA_BALANCING
628 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
629 depends on SMP && NUMA && MIGRATION
631 This option adds support for automatic NUMA aware memory/task placement.
632 The mechanism is quite primitive and is based on migrating memory when
633 it has references to the node the task is running on.
635 This system will be inactive on UMA systems.
637 config NUMA_BALANCING_DEFAULT_ENABLED
638 bool "Automatically enable NUMA aware memory/task placement"
640 depends on NUMA_BALANCING
642 If set, automatic NUMA balancing will be enabled if running on a NUMA
646 bool "Control Group support"
649 This option adds support for grouping sets of processes together, for
650 use with process control subsystems such as Cpusets, CFS, memory
651 controls or device isolation.
653 - Documentation/scheduler/sched-design-CFS.txt (CFS)
654 - Documentation/cgroup-v1/ (features for grouping, isolation
655 and resource control)
665 bool "Memory controller"
669 Provides control over the memory footprint of tasks in a cgroup.
672 bool "Swap controller"
673 depends on MEMCG && SWAP
675 Provides control over the swap space consumed by tasks in a cgroup.
677 config MEMCG_SWAP_ENABLED
678 bool "Swap controller enabled by default"
679 depends on MEMCG_SWAP
682 Memory Resource Controller Swap Extension comes with its price in
683 a bigger memory consumption. General purpose distribution kernels
684 which want to enable the feature but keep it disabled by default
685 and let the user enable it by swapaccount=1 boot command line
686 parameter should have this option unselected.
687 For those who want to have the feature enabled by default should
688 select this option (if, for some reason, they need to disable it
689 then swapaccount=0 does the trick).
696 Generic block IO controller cgroup interface. This is the common
697 cgroup interface which should be used by various IO controlling
700 Currently, CFQ IO scheduler uses it to recognize task groups and
701 control disk bandwidth allocation (proportional time slice allocation)
702 to such task groups. It is also used by bio throttling logic in
703 block layer to implement upper limit in IO rates on a device.
705 This option only enables generic Block IO controller infrastructure.
706 One needs to also enable actual IO controlling logic/policy. For
707 enabling proportional weight division of disk bandwidth in CFQ, set
708 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
709 CONFIG_BLK_DEV_THROTTLING=y.
711 See Documentation/cgroup-v1/blkio-controller.txt for more information.
713 config DEBUG_BLK_CGROUP
714 bool "IO controller debugging"
715 depends on BLK_CGROUP
718 Enable some debugging help. Currently it exports additional stat
719 files in a cgroup which can be useful for debugging.
721 config CGROUP_WRITEBACK
723 depends on MEMCG && BLK_CGROUP
726 menuconfig CGROUP_SCHED
727 bool "CPU controller"
730 This feature lets CPU scheduler recognize task groups and control CPU
731 bandwidth allocation to such task groups. It uses cgroups to group
735 config FAIR_GROUP_SCHED
736 bool "Group scheduling for SCHED_OTHER"
737 depends on CGROUP_SCHED
741 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
742 depends on FAIR_GROUP_SCHED
745 This option allows users to define CPU bandwidth rates (limits) for
746 tasks running within the fair group scheduler. Groups with no limit
747 set are considered to be unconstrained and will run with no
749 See tip/Documentation/scheduler/sched-bwc.txt for more information.
751 config RT_GROUP_SCHED
752 bool "Group scheduling for SCHED_RR/FIFO"
753 depends on CGROUP_SCHED
756 This feature lets you explicitly allocate real CPU bandwidth
757 to task groups. If enabled, it will also make it impossible to
758 schedule realtime tasks for non-root users until you allocate
759 realtime bandwidth for them.
760 See Documentation/scheduler/sched-rt-group.txt for more information.
765 bool "PIDs controller"
767 Provides enforcement of process number limits in the scope of a
768 cgroup. Any attempt to fork more processes than is allowed in the
769 cgroup will fail. PIDs are fundamentally a global resource because it
770 is fairly trivial to reach PID exhaustion before you reach even a
771 conservative kmemcg limit. As a result, it is possible to grind a
772 system to halt without being limited by other cgroup policies. The
773 PIDs controller is designed to stop this from happening.
775 It should be noted that organisational operations (such as attaching
776 to a cgroup hierarchy will *not* be blocked by the PIDs controller),
777 since the PIDs limit only affects a process's ability to fork, not to
781 bool "RDMA controller"
783 Provides enforcement of RDMA resources defined by IB stack.
784 It is fairly easy for consumers to exhaust RDMA resources, which
785 can result into resource unavailability to other consumers.
786 RDMA controller is designed to stop this from happening.
787 Attaching processes with active RDMA resources to the cgroup
788 hierarchy is allowed even if can cross the hierarchy's limit.
790 config CGROUP_FREEZER
791 bool "Freezer controller"
793 Provides a way to freeze and unfreeze all tasks in a
796 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
797 controller includes important in-kernel memory consumers per default.
799 If you're using cgroup2, say N.
801 config CGROUP_HUGETLB
802 bool "HugeTLB controller"
803 depends on HUGETLB_PAGE
807 Provides a cgroup controller for HugeTLB pages.
808 When you enable this, you can put a per cgroup limit on HugeTLB usage.
809 The limit is enforced during page fault. Since HugeTLB doesn't
810 support page reclaim, enforcing the limit at page fault time implies
811 that, the application will get SIGBUS signal if it tries to access
812 HugeTLB pages beyond its limit. This requires the application to know
813 beforehand how much HugeTLB pages it would require for its use. The
814 control group is tracked in the third page lru pointer. This means
815 that we cannot use the controller with huge page less than 3 pages.
818 bool "Cpuset controller"
821 This option will let you create and manage CPUSETs which
822 allow dynamically partitioning a system into sets of CPUs and
823 Memory Nodes and assigning tasks to run only within those sets.
824 This is primarily useful on large SMP or NUMA systems.
828 config PROC_PID_CPUSET
829 bool "Include legacy /proc/<pid>/cpuset file"
834 bool "Device controller"
836 Provides a cgroup controller implementing whitelists for
837 devices which a process in the cgroup can mknod or open.
839 config CGROUP_CPUACCT
840 bool "Simple CPU accounting controller"
842 Provides a simple controller for monitoring the
843 total CPU consumed by the tasks in a cgroup.
846 bool "Perf controller"
847 depends on PERF_EVENTS
849 This option extends the perf per-cpu mode to restrict monitoring
850 to threads which belong to the cgroup specified and run on the
856 bool "Support for eBPF programs attached to cgroups"
857 depends on BPF_SYSCALL
858 select SOCK_CGROUP_DATA
860 Allow attaching eBPF programs to a cgroup using the bpf(2)
861 syscall command BPF_PROG_ATTACH.
863 In which context these programs are accessed depends on the type
864 of attachment. For instance, programs that are attached using
865 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
869 bool "Debug controller"
871 depends on DEBUG_KERNEL
873 This option enables a simple controller that exports
874 debugging information about the cgroups framework. This
875 controller is for control cgroup debugging only. Its
876 interfaces are not stable.
880 config SOCK_CGROUP_DATA
886 config CHECKPOINT_RESTORE
887 bool "Checkpoint/restore support" if EXPERT
891 Enables additional kernel features in a sake of checkpoint/restore.
892 In particular it adds auxiliary prctl codes to setup process text,
893 data and heap segment sizes, and a few additional /proc filesystem
896 If unsure, say N here.
898 menuconfig NAMESPACES
899 bool "Namespaces support" if EXPERT
903 Provides the way to make tasks work with different objects using
904 the same id. For example same IPC id may refer to different objects
905 or same user id or pid may refer to different tasks when used in
906 different namespaces.
914 In this namespace tasks see different info provided with the
919 depends on (SYSVIPC || POSIX_MQUEUE)
922 In this namespace tasks work with IPC ids which correspond to
923 different IPC objects in different namespaces.
926 bool "User namespace"
929 This allows containers, i.e. vservers, to use user namespaces
930 to provide different user info for different servers.
932 When user namespaces are enabled in the kernel it is
933 recommended that the MEMCG option also be enabled and that
934 user-space use the memory control groups to limit the amount
935 of memory a memory unprivileged users can use.
940 bool "PID Namespaces"
943 Support process id namespaces. This allows having multiple
944 processes with the same pid as long as they are in different
945 pid namespaces. This is a building block of containers.
948 bool "Network namespace"
952 Allow user space to create what appear to be multiple instances
953 of the network stack.
957 config SCHED_AUTOGROUP
958 bool "Automatic process group scheduling"
961 select FAIR_GROUP_SCHED
963 This option optimizes the scheduler for common desktop workloads by
964 automatically creating and populating task groups. This separation
965 of workloads isolates aggressive CPU burners (like build jobs) from
966 desktop applications. Task group autogeneration is currently based
969 config SYSFS_DEPRECATED
970 bool "Enable deprecated sysfs features to support old userspace tools"
974 This option adds code that switches the layout of the "block" class
975 devices, to not show up in /sys/class/block/, but only in
978 This switch is only active when the sysfs.deprecated=1 boot option is
979 passed or the SYSFS_DEPRECATED_V2 option is set.
981 This option allows new kernels to run on old distributions and tools,
982 which might get confused by /sys/class/block/. Since 2007/2008 all
983 major distributions and tools handle this just fine.
985 Recent distributions and userspace tools after 2009/2010 depend on
986 the existence of /sys/class/block/, and will not work with this
989 Only if you are using a new kernel on an old distribution, you might
992 config SYSFS_DEPRECATED_V2
993 bool "Enable deprecated sysfs features by default"
996 depends on SYSFS_DEPRECATED
998 Enable deprecated sysfs by default.
1000 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1003 Only if you are using a new kernel on an old distribution, you might
1004 need to say Y here. Even then, odds are you would not need it
1005 enabled, you can always pass the boot option if absolutely necessary.
1008 bool "Kernel->user space relay support (formerly relayfs)"
1011 This option enables support for relay interface support in
1012 certain file systems (such as debugfs).
1013 It is designed to provide an efficient mechanism for tools and
1014 facilities to relay large amounts of data from kernel space to
1019 config BLK_DEV_INITRD
1020 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1021 depends on BROKEN || !FRV
1023 The initial RAM filesystem is a ramfs which is loaded by the
1024 boot loader (loadlin or lilo) and that is mounted as root
1025 before the normal boot procedure. It is typically used to
1026 load modules needed to mount the "real" root file system,
1027 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1029 If RAM disk support (BLK_DEV_RAM) is also included, this
1030 also enables initial RAM disk (initrd) support and adds
1031 15 Kbytes (more on some other architectures) to the kernel size.
1037 source "usr/Kconfig"
1042 prompt "Compiler optimization level"
1043 default CC_OPTIMIZE_FOR_PERFORMANCE
1045 config CC_OPTIMIZE_FOR_PERFORMANCE
1046 bool "Optimize for performance"
1048 This is the default optimization level for the kernel, building
1049 with the "-O2" compiler flag for best performance and most
1050 helpful compile-time warnings.
1052 config CC_OPTIMIZE_FOR_SIZE
1053 bool "Optimize for size"
1055 Enabling this option will pass "-Os" instead of "-O2" to
1056 your compiler resulting in a smaller kernel.
1071 config SYSCTL_EXCEPTION_TRACE
1074 Enable support for /proc/sys/debug/exception-trace.
1076 config SYSCTL_ARCH_UNALIGN_NO_WARN
1079 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1080 Allows arch to define/use @no_unaligned_warning to possibly warn
1081 about unaligned access emulation going on under the hood.
1083 config SYSCTL_ARCH_UNALIGN_ALLOW
1086 Enable support for /proc/sys/kernel/unaligned-trap
1087 Allows arches to define/use @unaligned_enabled to runtime toggle
1088 the unaligned access emulation.
1089 see arch/parisc/kernel/unaligned.c for reference
1091 config HAVE_PCSPKR_PLATFORM
1094 # interpreter that classic socket filters depend on
1099 bool "Configure standard kernel features (expert users)"
1100 # Unhide debug options, to make the on-by-default options visible
1103 This option allows certain base kernel options and settings
1104 to be disabled or tweaked. This is for specialized
1105 environments which can tolerate a "non-standard" kernel.
1106 Only use this if you really know what you are doing.
1109 bool "Enable 16-bit UID system calls" if EXPERT
1110 depends on HAVE_UID16 && MULTIUSER
1113 This enables the legacy 16-bit UID syscall wrappers.
1116 bool "Multiple users, groups and capabilities support" if EXPERT
1119 This option enables support for non-root users, groups and
1122 If you say N here, all processes will run with UID 0, GID 0, and all
1123 possible capabilities. Saying N here also compiles out support for
1124 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1127 If unsure, say Y here.
1129 config SGETMASK_SYSCALL
1130 bool "sgetmask/ssetmask syscalls support" if EXPERT
1131 def_bool PARISC || MN10300 || BLACKFIN || M68K || PPC || MIPS || X86 || SPARC || CRIS || MICROBLAZE || SUPERH
1133 sys_sgetmask and sys_ssetmask are obsolete system calls
1134 no longer supported in libc but still enabled by default in some
1137 If unsure, leave the default option here.
1139 config SYSFS_SYSCALL
1140 bool "Sysfs syscall support" if EXPERT
1143 sys_sysfs is an obsolete system call no longer supported in libc.
1144 Note that disabling this option is more secure but might break
1145 compatibility with some systems.
1147 If unsure say Y here.
1149 config SYSCTL_SYSCALL
1150 bool "Sysctl syscall support" if EXPERT
1151 depends on PROC_SYSCTL
1155 sys_sysctl uses binary paths that have been found challenging
1156 to properly maintain and use. The interface in /proc/sys
1157 using paths with ascii names is now the primary path to this
1160 Almost nothing using the binary sysctl interface so if you are
1161 trying to save some space it is probably safe to disable this,
1162 making your kernel marginally smaller.
1164 If unsure say N here.
1167 bool "Posix Clocks & timers" if EXPERT
1170 This includes native support for POSIX timers to the kernel.
1171 Some embedded systems have no use for them and therefore they
1172 can be configured out to reduce the size of the kernel image.
1174 When this option is disabled, the following syscalls won't be
1175 available: timer_create, timer_gettime: timer_getoverrun,
1176 timer_settime, timer_delete, clock_adjtime, getitimer,
1177 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1178 clock_getres and clock_nanosleep syscalls will be limited to
1179 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1184 bool "Load all symbols for debugging/ksymoops" if EXPERT
1187 Say Y here to let the kernel print out symbolic crash information and
1188 symbolic stack backtraces. This increases the size of the kernel
1189 somewhat, as all symbols have to be loaded into the kernel image.
1192 bool "Include all symbols in kallsyms"
1193 depends on DEBUG_KERNEL && KALLSYMS
1195 Normally kallsyms only contains the symbols of functions for nicer
1196 OOPS messages and backtraces (i.e., symbols from the text and inittext
1197 sections). This is sufficient for most cases. And only in very rare
1198 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1199 names of variables from the data sections, etc).
1201 This option makes sure that all symbols are loaded into the kernel
1202 image (i.e., symbols from all sections) in cost of increased kernel
1203 size (depending on the kernel configuration, it may be 300KiB or
1204 something like this).
1206 Say N unless you really need all symbols.
1208 config KALLSYMS_ABSOLUTE_PERCPU
1211 default X86_64 && SMP
1213 config KALLSYMS_BASE_RELATIVE
1216 default !IA64 && !(TILE && 64BIT)
1218 Instead of emitting them as absolute values in the native word size,
1219 emit the symbol references in the kallsyms table as 32-bit entries,
1220 each containing a relative value in the range [base, base + U32_MAX]
1221 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1222 an absolute value in the range [0, S32_MAX] or a relative value in the
1223 range [base, base + S32_MAX], where base is the lowest relative symbol
1224 address encountered in the image.
1226 On 64-bit builds, this reduces the size of the address table by 50%,
1227 but more importantly, it results in entries whose values are build
1228 time constants, and no relocation pass is required at runtime to fix
1229 up the entries based on the runtime load address of the kernel.
1233 bool "Enable support for printk" if EXPERT
1236 This option enables normal printk support. Removing it
1237 eliminates most of the message strings from the kernel image
1238 and makes the kernel more or less silent. As this makes it
1239 very difficult to diagnose system problems, saying N here is
1240 strongly discouraged.
1248 bool "BUG() support" if EXPERT
1251 Disabling this option eliminates support for BUG and WARN, reducing
1252 the size of your kernel image and potentially quietly ignoring
1253 numerous fatal conditions. You should only consider disabling this
1254 option for embedded systems with no facilities for reporting errors.
1260 bool "Enable ELF core dumps" if EXPERT
1262 Enable support for generating core dumps. Disabling saves about 4k.
1265 config PCSPKR_PLATFORM
1266 bool "Enable PC-Speaker support" if EXPERT
1267 depends on HAVE_PCSPKR_PLATFORM
1271 This option allows to disable the internal PC-Speaker
1272 support, saving some memory.
1276 bool "Enable full-sized data structures for core" if EXPERT
1278 Disabling this option reduces the size of miscellaneous core
1279 kernel data structures. This saves memory on small machines,
1280 but may reduce performance.
1283 bool "Enable futex support" if EXPERT
1287 Disabling this option will cause the kernel to be built without
1288 support for "fast userspace mutexes". The resulting kernel may not
1289 run glibc-based applications correctly.
1293 depends on FUTEX && RT_MUTEXES
1296 config HAVE_FUTEX_CMPXCHG
1300 Architectures should select this if futex_atomic_cmpxchg_inatomic()
1301 is implemented and always working. This removes a couple of runtime
1305 bool "Enable eventpoll support" if EXPERT
1309 Disabling this option will cause the kernel to be built without
1310 support for epoll family of system calls.
1313 bool "Enable signalfd() system call" if EXPERT
1317 Enable the signalfd() system call that allows to receive signals
1318 on a file descriptor.
1323 bool "Enable timerfd() system call" if EXPERT
1327 Enable the timerfd() system call that allows to receive timer
1328 events on a file descriptor.
1333 bool "Enable eventfd() system call" if EXPERT
1337 Enable the eventfd() system call that allows to receive both
1338 kernel notification (ie. KAIO) or userspace notifications.
1342 # syscall, maps, verifier
1344 bool "Enable bpf() system call"
1349 Enable the bpf() system call that allows to manipulate eBPF
1350 programs and maps via file descriptors.
1353 bool "Use full shmem filesystem" if EXPERT
1357 The shmem is an internal filesystem used to manage shared memory.
1358 It is backed by swap and manages resource limits. It is also exported
1359 to userspace as tmpfs if TMPFS is enabled. Disabling this
1360 option replaces shmem and tmpfs with the much simpler ramfs code,
1361 which may be appropriate on small systems without swap.
1364 bool "Enable AIO support" if EXPERT
1367 This option enables POSIX asynchronous I/O which may by used
1368 by some high performance threaded applications. Disabling
1369 this option saves about 7k.
1371 config ADVISE_SYSCALLS
1372 bool "Enable madvise/fadvise syscalls" if EXPERT
1375 This option enables the madvise and fadvise syscalls, used by
1376 applications to advise the kernel about their future memory or file
1377 usage, improving performance. If building an embedded system where no
1378 applications use these syscalls, you can disable this option to save
1382 bool "Enable userfaultfd() system call"
1386 Enable the userfaultfd() system call that allows to intercept and
1387 handle page faults in userland.
1391 bool "Enable PCI quirk workarounds" if EXPERT
1394 This enables workarounds for various PCI chipset
1395 bugs/quirks. Disable this only if your target machine is
1396 unaffected by PCI quirks.
1399 bool "Enable membarrier() system call" if EXPERT
1402 Enable the membarrier() system call that allows issuing memory
1403 barriers across all running threads, which can be used to distribute
1404 the cost of user-space memory barriers asymmetrically by transforming
1405 pairs of memory barriers into pairs consisting of membarrier() and a
1411 bool "Embedded system"
1412 option allnoconfig_y
1415 This option should be enabled if compiling the kernel for
1416 an embedded system so certain expert options are available
1419 config HAVE_PERF_EVENTS
1422 See tools/perf/design.txt for details.
1424 config PERF_USE_VMALLOC
1427 See tools/perf/design.txt for details
1430 bool "PC/104 support"
1432 Expose PC/104 form factor device drivers and options available for
1433 selection and configuration. Enable this option if your target
1434 machine has a PC/104 bus.
1436 menu "Kernel Performance Events And Counters"
1439 bool "Kernel performance events and counters"
1440 default y if PROFILING
1441 depends on HAVE_PERF_EVENTS
1446 Enable kernel support for various performance events provided
1447 by software and hardware.
1449 Software events are supported either built-in or via the
1450 use of generic tracepoints.
1452 Most modern CPUs support performance events via performance
1453 counter registers. These registers count the number of certain
1454 types of hw events: such as instructions executed, cachemisses
1455 suffered, or branches mis-predicted - without slowing down the
1456 kernel or applications. These registers can also trigger interrupts
1457 when a threshold number of events have passed - and can thus be
1458 used to profile the code that runs on that CPU.
1460 The Linux Performance Event subsystem provides an abstraction of
1461 these software and hardware event capabilities, available via a
1462 system call and used by the "perf" utility in tools/perf/. It
1463 provides per task and per CPU counters, and it provides event
1464 capabilities on top of those.
1468 config DEBUG_PERF_USE_VMALLOC
1470 bool "Debug: use vmalloc to back perf mmap() buffers"
1471 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1472 select PERF_USE_VMALLOC
1474 Use vmalloc memory to back perf mmap() buffers.
1476 Mostly useful for debugging the vmalloc code on platforms
1477 that don't require it.
1483 config VM_EVENT_COUNTERS
1485 bool "Enable VM event counters for /proc/vmstat" if EXPERT
1487 VM event counters are needed for event counts to be shown.
1488 This option allows the disabling of the VM event counters
1489 on EXPERT systems. /proc/vmstat will only show page counts
1490 if VM event counters are disabled.
1494 bool "Enable SLUB debugging support" if EXPERT
1495 depends on SLUB && SYSFS
1497 SLUB has extensive debug support features. Disabling these can
1498 result in significant savings in code size. This also disables
1499 SLUB sysfs support. /sys/slab will not exist and there will be
1500 no support for cache validation etc.
1502 config SLUB_MEMCG_SYSFS_ON
1504 bool "Enable memcg SLUB sysfs support by default" if EXPERT
1505 depends on SLUB && SYSFS && MEMCG
1507 SLUB creates a directory under /sys/kernel/slab for each
1508 allocation cache to host info and debug files. If memory
1509 cgroup is enabled, each cache can have per memory cgroup
1510 caches. SLUB can create the same sysfs directories for these
1511 caches under /sys/kernel/slab/CACHE/cgroup but it can lead
1512 to a very high number of debug files being created. This is
1513 controlled by slub_memcg_sysfs boot parameter and this
1514 config option determines the parameter's default value.
1517 bool "Disable heap randomization"
1520 Randomizing heap placement makes heap exploits harder, but it
1521 also breaks ancient binaries (including anything libc5 based).
1522 This option changes the bootup default to heap randomization
1523 disabled, and can be overridden at runtime by setting
1524 /proc/sys/kernel/randomize_va_space to 2.
1526 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1529 prompt "Choose SLAB allocator"
1532 This option allows to select a slab allocator.
1536 select HAVE_HARDENED_USERCOPY_ALLOCATOR
1538 The regular slab allocator that is established and known to work
1539 well in all environments. It organizes cache hot objects in
1540 per cpu and per node queues.
1543 bool "SLUB (Unqueued Allocator)"
1544 select HAVE_HARDENED_USERCOPY_ALLOCATOR
1546 SLUB is a slab allocator that minimizes cache line usage
1547 instead of managing queues of cached objects (SLAB approach).
1548 Per cpu caching is realized using slabs of objects instead
1549 of queues of objects. SLUB can use memory efficiently
1550 and has enhanced diagnostics. SLUB is the default choice for
1555 bool "SLOB (Simple Allocator)"
1557 SLOB replaces the stock allocator with a drastically simpler
1558 allocator. SLOB is generally more space efficient but
1559 does not perform as well on large systems.
1563 config SLAB_MERGE_DEFAULT
1564 bool "Allow slab caches to be merged"
1567 For reduced kernel memory fragmentation, slab caches can be
1568 merged when they share the same size and other characteristics.
1569 This carries a risk of kernel heap overflows being able to
1570 overwrite objects from merged caches (and more easily control
1571 cache layout), which makes such heap attacks easier to exploit
1572 by attackers. By keeping caches unmerged, these kinds of exploits
1573 can usually only damage objects in the same cache. To disable
1574 merging at runtime, "slab_nomerge" can be passed on the kernel
1577 config SLAB_FREELIST_RANDOM
1579 depends on SLAB || SLUB
1580 bool "SLAB freelist randomization"
1582 Randomizes the freelist order used on creating new pages. This
1583 security feature reduces the predictability of the kernel slab
1584 allocator against heap overflows.
1586 config SLAB_FREELIST_HARDENED
1587 bool "Harden slab freelist metadata"
1590 Many kernel heap attacks try to target slab cache metadata and
1591 other infrastructure. This options makes minor performance
1592 sacrifies to harden the kernel slab allocator against common
1593 freelist exploit methods.
1595 config SLUB_CPU_PARTIAL
1597 depends on SLUB && SMP
1598 bool "SLUB per cpu partial cache"
1600 Per cpu partial caches accellerate objects allocation and freeing
1601 that is local to a processor at the price of more indeterminism
1602 in the latency of the free. On overflow these caches will be cleared
1603 which requires the taking of locks that may cause latency spikes.
1604 Typically one would choose no for a realtime system.
1606 config MMAP_ALLOW_UNINITIALIZED
1607 bool "Allow mmapped anonymous memory to be uninitialized"
1608 depends on EXPERT && !MMU
1611 Normally, and according to the Linux spec, anonymous memory obtained
1612 from mmap() has it's contents cleared before it is passed to
1613 userspace. Enabling this config option allows you to request that
1614 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1615 providing a huge performance boost. If this option is not enabled,
1616 then the flag will be ignored.
1618 This is taken advantage of by uClibc's malloc(), and also by
1619 ELF-FDPIC binfmt's brk and stack allocator.
1621 Because of the obvious security issues, this option should only be
1622 enabled on embedded devices where you control what is run in
1623 userspace. Since that isn't generally a problem on no-MMU systems,
1624 it is normally safe to say Y here.
1626 See Documentation/nommu-mmap.txt for more information.
1628 config SYSTEM_DATA_VERIFICATION
1630 select SYSTEM_TRUSTED_KEYRING
1634 select ASYMMETRIC_KEY_TYPE
1635 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1638 select X509_CERTIFICATE_PARSER
1639 select PKCS7_MESSAGE_PARSER
1641 Provide PKCS#7 message verification using the contents of the system
1642 trusted keyring to provide public keys. This then can be used for
1643 module verification, kexec image verification and firmware blob
1647 bool "Profiling support"
1649 Say Y here to enable the extended profiling support mechanisms used
1650 by profilers such as OProfile.
1653 # Place an empty function call at each tracepoint site. Can be
1654 # dynamically changed for a probe function.
1659 source "arch/Kconfig"
1661 endmenu # General setup
1663 config HAVE_GENERIC_DMA_COHERENT
1670 depends on SLAB || SLUB_DEBUG
1678 default 0 if BASE_FULL
1679 default 1 if !BASE_FULL
1682 bool "Enable loadable module support"
1685 Kernel modules are small pieces of compiled code which can
1686 be inserted in the running kernel, rather than being
1687 permanently built into the kernel. You use the "modprobe"
1688 tool to add (and sometimes remove) them. If you say Y here,
1689 many parts of the kernel can be built as modules (by
1690 answering M instead of Y where indicated): this is most
1691 useful for infrequently used options which are not required
1692 for booting. For more information, see the man pages for
1693 modprobe, lsmod, modinfo, insmod and rmmod.
1695 If you say Y here, you will need to run "make
1696 modules_install" to put the modules under /lib/modules/
1697 where modprobe can find them (you may need to be root to do
1704 config MODULE_FORCE_LOAD
1705 bool "Forced module loading"
1708 Allow loading of modules without version information (ie. modprobe
1709 --force). Forced module loading sets the 'F' (forced) taint flag and
1710 is usually a really bad idea.
1712 config MODULE_UNLOAD
1713 bool "Module unloading"
1715 Without this option you will not be able to unload any
1716 modules (note that some modules may not be unloadable
1717 anyway), which makes your kernel smaller, faster
1718 and simpler. If unsure, say Y.
1720 config MODULE_FORCE_UNLOAD
1721 bool "Forced module unloading"
1722 depends on MODULE_UNLOAD
1724 This option allows you to force a module to unload, even if the
1725 kernel believes it is unsafe: the kernel will remove the module
1726 without waiting for anyone to stop using it (using the -f option to
1727 rmmod). This is mainly for kernel developers and desperate users.
1731 bool "Module versioning support"
1733 Usually, you have to use modules compiled with your kernel.
1734 Saying Y here makes it sometimes possible to use modules
1735 compiled for different kernels, by adding enough information
1736 to the modules to (hopefully) spot any changes which would
1737 make them incompatible with the kernel you are running. If
1740 config MODULE_REL_CRCS
1742 depends on MODVERSIONS
1744 config MODULE_SRCVERSION_ALL
1745 bool "Source checksum for all modules"
1747 Modules which contain a MODULE_VERSION get an extra "srcversion"
1748 field inserted into their modinfo section, which contains a
1749 sum of the source files which made it. This helps maintainers
1750 see exactly which source was used to build a module (since
1751 others sometimes change the module source without updating
1752 the version). With this option, such a "srcversion" field
1753 will be created for all modules. If unsure, say N.
1756 bool "Module signature verification"
1758 select SYSTEM_DATA_VERIFICATION
1760 Check modules for valid signatures upon load: the signature
1761 is simply appended to the module. For more information see
1762 Documentation/module-signing.txt.
1764 Note that this option adds the OpenSSL development packages as a
1765 kernel build dependency so that the signing tool can use its crypto
1768 !!!WARNING!!! If you enable this option, you MUST make sure that the
1769 module DOES NOT get stripped after being signed. This includes the
1770 debuginfo strip done by some packagers (such as rpmbuild) and
1771 inclusion into an initramfs that wants the module size reduced.
1773 config MODULE_SIG_FORCE
1774 bool "Require modules to be validly signed"
1775 depends on MODULE_SIG
1777 Reject unsigned modules or signed modules for which we don't have a
1778 key. Without this, such modules will simply taint the kernel.
1780 config MODULE_SIG_ALL
1781 bool "Automatically sign all modules"
1783 depends on MODULE_SIG
1785 Sign all modules during make modules_install. Without this option,
1786 modules must be signed manually, using the scripts/sign-file tool.
1788 comment "Do not forget to sign required modules with scripts/sign-file"
1789 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
1792 prompt "Which hash algorithm should modules be signed with?"
1793 depends on MODULE_SIG
1795 This determines which sort of hashing algorithm will be used during
1796 signature generation. This algorithm _must_ be built into the kernel
1797 directly so that signature verification can take place. It is not
1798 possible to load a signed module containing the algorithm to check
1799 the signature on that module.
1801 config MODULE_SIG_SHA1
1802 bool "Sign modules with SHA-1"
1805 config MODULE_SIG_SHA224
1806 bool "Sign modules with SHA-224"
1807 select CRYPTO_SHA256
1809 config MODULE_SIG_SHA256
1810 bool "Sign modules with SHA-256"
1811 select CRYPTO_SHA256
1813 config MODULE_SIG_SHA384
1814 bool "Sign modules with SHA-384"
1815 select CRYPTO_SHA512
1817 config MODULE_SIG_SHA512
1818 bool "Sign modules with SHA-512"
1819 select CRYPTO_SHA512
1823 config MODULE_SIG_HASH
1825 depends on MODULE_SIG
1826 default "sha1" if MODULE_SIG_SHA1
1827 default "sha224" if MODULE_SIG_SHA224
1828 default "sha256" if MODULE_SIG_SHA256
1829 default "sha384" if MODULE_SIG_SHA384
1830 default "sha512" if MODULE_SIG_SHA512
1832 config MODULE_COMPRESS
1833 bool "Compress modules on installation"
1837 Compresses kernel modules when 'make modules_install' is run; gzip or
1838 xz depending on "Compression algorithm" below.
1840 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
1842 Out-of-tree kernel modules installed using Kbuild will also be
1843 compressed upon installation.
1845 Note: for modules inside an initrd or initramfs, it's more efficient
1846 to compress the whole initrd or initramfs instead.
1848 Note: This is fully compatible with signed modules.
1853 prompt "Compression algorithm"
1854 depends on MODULE_COMPRESS
1855 default MODULE_COMPRESS_GZIP
1857 This determines which sort of compression will be used during
1858 'make modules_install'.
1860 GZIP (default) and XZ are supported.
1862 config MODULE_COMPRESS_GZIP
1865 config MODULE_COMPRESS_XZ
1870 config TRIM_UNUSED_KSYMS
1871 bool "Trim unused exported kernel symbols"
1872 depends on MODULES && !UNUSED_SYMBOLS
1874 The kernel and some modules make many symbols available for
1875 other modules to use via EXPORT_SYMBOL() and variants. Depending
1876 on the set of modules being selected in your kernel configuration,
1877 many of those exported symbols might never be used.
1879 This option allows for unused exported symbols to be dropped from
1880 the build. In turn, this provides the compiler more opportunities
1881 (especially when using LTO) for optimizing the code and reducing
1882 binary size. This might have some security advantages as well.
1884 If unsure, or if you need to build out-of-tree modules, say N.
1888 config MODULES_TREE_LOOKUP
1890 depends on PERF_EVENTS || TRACING
1892 config INIT_ALL_POSSIBLE
1895 Back when each arch used to define their own cpu_online_mask and
1896 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
1897 with all 1s, and others with all 0s. When they were centralised,
1898 it was better to provide this option than to break all the archs
1899 and have several arch maintainers pursuing me down dark alleys.
1901 source "block/Kconfig"
1903 config PREEMPT_NOTIFIERS
1913 Build a simple ASN.1 grammar compiler that produces a bytecode output
1914 that can be interpreted by the ASN.1 stream decoder and used to
1915 inform it as to what tags are to be expected in a stream and what
1916 functions to call on what tags.
1918 source "kernel/Kconfig.locks"
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