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
142 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
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.
223 config VERSION_SIGNATURE
224 string "Arbitrary version signature"
226 This string will be created in a file, /proc/version_signature. It
227 is useful in determining arbitrary data about your kernel. For instance,
228 if you have several kernels of the same version, but need to keep track
229 of a revision of the same kernel, but not affect it's ability to load
230 compatible modules, this is the easiest way to do that.
233 bool "Support for paging of anonymous memory (swap)"
234 depends on MMU && BLOCK
237 This option allows you to choose whether you want to have support
238 for so called swap devices or swap files in your kernel that are
239 used to provide more virtual memory than the actual RAM present
240 in your computer. If unsure say Y.
245 Inter Process Communication is a suite of library functions and
246 system calls which let processes (running programs) synchronize and
247 exchange information. It is generally considered to be a good thing,
248 and some programs won't run unless you say Y here. In particular, if
249 you want to run the DOS emulator dosemu under Linux (read the
250 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
251 you'll need to say Y here.
253 You can find documentation about IPC with "info ipc" and also in
254 section 6.4 of the Linux Programmer's Guide, available from
255 <http://www.tldp.org/guides.html>.
257 config SYSVIPC_SYSCTL
264 bool "POSIX Message Queues"
267 POSIX variant of message queues is a part of IPC. In POSIX message
268 queues every message has a priority which decides about succession
269 of receiving it by a process. If you want to compile and run
270 programs written e.g. for Solaris with use of its POSIX message
271 queues (functions mq_*) say Y here.
273 POSIX message queues are visible as a filesystem called 'mqueue'
274 and can be mounted somewhere if you want to do filesystem
275 operations on message queues.
279 config POSIX_MQUEUE_SYSCTL
281 depends on POSIX_MQUEUE
285 config CROSS_MEMORY_ATTACH
286 bool "Enable process_vm_readv/writev syscalls"
290 Enabling this option adds the system calls process_vm_readv and
291 process_vm_writev which allow a process with the correct privileges
292 to directly read from or write to another process' address space.
293 See the man page for more details.
296 bool "uselib syscall"
297 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
299 This option enables the uselib syscall, a system call used in the
300 dynamic linker from libc5 and earlier. glibc does not use this
301 system call. If you intend to run programs built on libc5 or
302 earlier, you may need to enable this syscall. Current systems
303 running glibc can safely disable this.
306 bool "Auditing support"
309 Enable auditing infrastructure that can be used with another
310 kernel subsystem, such as SELinux (which requires this for
311 logging of avc messages output). System call auditing is included
312 on architectures which support it.
314 config HAVE_ARCH_AUDITSYSCALL
319 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
323 depends on AUDITSYSCALL
328 depends on AUDITSYSCALL
331 source "kernel/irq/Kconfig"
332 source "kernel/time/Kconfig"
334 menu "CPU/Task time and stats accounting"
336 config VIRT_CPU_ACCOUNTING
340 prompt "Cputime accounting"
341 default TICK_CPU_ACCOUNTING if !PPC64
342 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
344 # Kind of a stub config for the pure tick based cputime accounting
345 config TICK_CPU_ACCOUNTING
346 bool "Simple tick based cputime accounting"
347 depends on !S390 && !NO_HZ_FULL
349 This is the basic tick based cputime accounting that maintains
350 statistics about user, system and idle time spent on per jiffies
355 config VIRT_CPU_ACCOUNTING_NATIVE
356 bool "Deterministic task and CPU time accounting"
357 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
358 select VIRT_CPU_ACCOUNTING
360 Select this option to enable more accurate task and CPU time
361 accounting. This is done by reading a CPU counter on each
362 kernel entry and exit and on transitions within the kernel
363 between system, softirq and hardirq state, so there is a
364 small performance impact. In the case of s390 or IBM POWER > 5,
365 this also enables accounting of stolen time on logically-partitioned
368 config VIRT_CPU_ACCOUNTING_GEN
369 bool "Full dynticks CPU time accounting"
370 depends on HAVE_CONTEXT_TRACKING
371 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
372 select VIRT_CPU_ACCOUNTING
373 select CONTEXT_TRACKING
375 Select this option to enable task and CPU time accounting on full
376 dynticks systems. This accounting is implemented by watching every
377 kernel-user boundaries using the context tracking subsystem.
378 The accounting is thus performed at the expense of some significant
381 For now this is only useful if you are working on the full
382 dynticks subsystem development.
388 config IRQ_TIME_ACCOUNTING
389 bool "Fine granularity task level IRQ time accounting"
390 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
392 Select this option to enable fine granularity task irq time
393 accounting. This is done by reading a timestamp on each
394 transitions between softirq and hardirq state, so there can be a
395 small performance impact.
397 If in doubt, say N here.
399 config BSD_PROCESS_ACCT
400 bool "BSD Process Accounting"
403 If you say Y here, a user level program will be able to instruct the
404 kernel (via a special system call) to write process accounting
405 information to a file: whenever a process exits, information about
406 that process will be appended to the file by the kernel. The
407 information includes things such as creation time, owning user,
408 command name, memory usage, controlling terminal etc. (the complete
409 list is in the struct acct in <file:include/linux/acct.h>). It is
410 up to the user level program to do useful things with this
411 information. This is generally a good idea, so say Y.
413 config BSD_PROCESS_ACCT_V3
414 bool "BSD Process Accounting version 3 file format"
415 depends on BSD_PROCESS_ACCT
418 If you say Y here, the process accounting information is written
419 in a new file format that also logs the process IDs of each
420 process and it's parent. Note that this file format is incompatible
421 with previous v0/v1/v2 file formats, so you will need updated tools
422 for processing it. A preliminary version of these tools is available
423 at <http://www.gnu.org/software/acct/>.
426 bool "Export task/process statistics through netlink"
431 Export selected statistics for tasks/processes through the
432 generic netlink interface. Unlike BSD process accounting, the
433 statistics are available during the lifetime of tasks/processes as
434 responses to commands. Like BSD accounting, they are sent to user
439 config TASK_DELAY_ACCT
440 bool "Enable per-task delay accounting"
444 Collect information on time spent by a task waiting for system
445 resources like cpu, synchronous block I/O completion and swapping
446 in pages. Such statistics can help in setting a task's priorities
447 relative to other tasks for cpu, io, rss limits etc.
452 bool "Enable extended accounting over taskstats"
455 Collect extended task accounting data and send the data
456 to userland for processing over the taskstats interface.
460 config TASK_IO_ACCOUNTING
461 bool "Enable per-task storage I/O accounting"
462 depends on TASK_XACCT
464 Collect information on the number of bytes of storage I/O which this
469 endmenu # "CPU/Task time and stats accounting"
473 depends on SMP || COMPILE_TEST
476 Make sure that CPUs running critical tasks are not disturbed by
477 any source of "noise" such as unbound workqueues, timers, kthreads...
478 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
479 the "isolcpus=" boot parameter.
483 source "kernel/rcu/Kconfig"
490 tristate "Kernel .config support"
493 This option enables the complete Linux kernel ".config" file
494 contents to be saved in the kernel. It provides documentation
495 of which kernel options are used in a running kernel or in an
496 on-disk kernel. This information can be extracted from the kernel
497 image file with the script scripts/extract-ikconfig and used as
498 input to rebuild the current kernel or to build another kernel.
499 It can also be extracted from a running kernel by reading
500 /proc/config.gz if enabled (below).
503 bool "Enable access to .config through /proc/config.gz"
504 depends on IKCONFIG && PROC_FS
506 This option enables access to the kernel configuration file
507 through /proc/config.gz.
510 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
515 Select the minimal kernel log buffer size as a power of 2.
516 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
517 parameter, see below. Any higher size also might be forced
518 by "log_buf_len" boot parameter.
528 config LOG_CPU_MAX_BUF_SHIFT
529 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
532 default 12 if !BASE_SMALL
533 default 0 if BASE_SMALL
536 This option allows to increase the default ring buffer size
537 according to the number of CPUs. The value defines the contribution
538 of each CPU as a power of 2. The used space is typically only few
539 lines however it might be much more when problems are reported,
542 The increased size means that a new buffer has to be allocated and
543 the original static one is unused. It makes sense only on systems
544 with more CPUs. Therefore this value is used only when the sum of
545 contributions is greater than the half of the default kernel ring
546 buffer as defined by LOG_BUF_SHIFT. The default values are set
547 so that more than 64 CPUs are needed to trigger the allocation.
549 Also this option is ignored when "log_buf_len" kernel parameter is
550 used as it forces an exact (power of two) size of the ring buffer.
552 The number of possible CPUs is used for this computation ignoring
553 hotplugging making the computation optimal for the worst case
554 scenario while allowing a simple algorithm to be used from bootup.
556 Examples shift values and their meaning:
557 17 => 128 KB for each CPU
558 16 => 64 KB for each CPU
559 15 => 32 KB for each CPU
560 14 => 16 KB for each CPU
561 13 => 8 KB for each CPU
562 12 => 4 KB for each CPU
564 config PRINTK_SAFE_LOG_BUF_SHIFT
565 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
570 Select the size of an alternate printk per-CPU buffer where messages
571 printed from usafe contexts are temporary stored. One example would
572 be NMI messages, another one - printk recursion. The messages are
573 copied to the main log buffer in a safe context to avoid a deadlock.
574 The value defines the size as a power of 2.
576 Those messages are rare and limited. The largest one is when
577 a backtrace is printed. It usually fits into 4KB. Select
578 8KB if you want to be on the safe side.
581 17 => 128 KB for each CPU
582 16 => 64 KB for each CPU
583 15 => 32 KB for each CPU
584 14 => 16 KB for each CPU
585 13 => 8 KB for each CPU
586 12 => 4 KB for each CPU
589 # Architectures with an unreliable sched_clock() should select this:
591 config HAVE_UNSTABLE_SCHED_CLOCK
594 config GENERIC_SCHED_CLOCK
598 # For architectures that want to enable the support for NUMA-affine scheduler
601 config ARCH_SUPPORTS_NUMA_BALANCING
605 # For architectures that prefer to flush all TLBs after a number of pages
606 # are unmapped instead of sending one IPI per page to flush. The architecture
607 # must provide guarantees on what happens if a clean TLB cache entry is
608 # written after the unmap. Details are in mm/rmap.c near the check for
609 # should_defer_flush. The architecture should also consider if the full flush
610 # and the refill costs are offset by the savings of sending fewer IPIs.
611 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
615 # For architectures that know their GCC __int128 support is sound
617 config ARCH_SUPPORTS_INT128
620 # For architectures that (ab)use NUMA to represent different memory regions
621 # all cpu-local but of different latencies, such as SuperH.
623 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
626 config NUMA_BALANCING
627 bool "Memory placement aware NUMA scheduler"
628 depends on ARCH_SUPPORTS_NUMA_BALANCING
629 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
630 depends on SMP && NUMA && MIGRATION
632 This option adds support for automatic NUMA aware memory/task placement.
633 The mechanism is quite primitive and is based on migrating memory when
634 it has references to the node the task is running on.
636 This system will be inactive on UMA systems.
638 config NUMA_BALANCING_DEFAULT_ENABLED
639 bool "Automatically enable NUMA aware memory/task placement"
641 depends on NUMA_BALANCING
643 If set, automatic NUMA balancing will be enabled if running on a NUMA
647 bool "Control Group support"
650 This option adds support for grouping sets of processes together, for
651 use with process control subsystems such as Cpusets, CFS, memory
652 controls or device isolation.
654 - Documentation/scheduler/sched-design-CFS.txt (CFS)
655 - Documentation/cgroup-v1/ (features for grouping, isolation
656 and resource control)
666 bool "Memory controller"
670 Provides control over the memory footprint of tasks in a cgroup.
673 bool "Swap controller"
674 depends on MEMCG && SWAP
676 Provides control over the swap space consumed by tasks in a cgroup.
678 config MEMCG_SWAP_ENABLED
679 bool "Swap controller enabled by default"
680 depends on MEMCG_SWAP
683 Memory Resource Controller Swap Extension comes with its price in
684 a bigger memory consumption. General purpose distribution kernels
685 which want to enable the feature but keep it disabled by default
686 and let the user enable it by swapaccount=1 boot command line
687 parameter should have this option unselected.
688 For those who want to have the feature enabled by default should
689 select this option (if, for some reason, they need to disable it
690 then swapaccount=0 does the trick).
697 Generic block IO controller cgroup interface. This is the common
698 cgroup interface which should be used by various IO controlling
701 Currently, CFQ IO scheduler uses it to recognize task groups and
702 control disk bandwidth allocation (proportional time slice allocation)
703 to such task groups. It is also used by bio throttling logic in
704 block layer to implement upper limit in IO rates on a device.
706 This option only enables generic Block IO controller infrastructure.
707 One needs to also enable actual IO controlling logic/policy. For
708 enabling proportional weight division of disk bandwidth in CFQ, set
709 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
710 CONFIG_BLK_DEV_THROTTLING=y.
712 See Documentation/cgroup-v1/blkio-controller.txt for more information.
714 config DEBUG_BLK_CGROUP
715 bool "IO controller debugging"
716 depends on BLK_CGROUP
719 Enable some debugging help. Currently it exports additional stat
720 files in a cgroup which can be useful for debugging.
722 config CGROUP_WRITEBACK
724 depends on MEMCG && BLK_CGROUP
727 menuconfig CGROUP_SCHED
728 bool "CPU controller"
731 This feature lets CPU scheduler recognize task groups and control CPU
732 bandwidth allocation to such task groups. It uses cgroups to group
736 config FAIR_GROUP_SCHED
737 bool "Group scheduling for SCHED_OTHER"
738 depends on CGROUP_SCHED
742 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
743 depends on FAIR_GROUP_SCHED
746 This option allows users to define CPU bandwidth rates (limits) for
747 tasks running within the fair group scheduler. Groups with no limit
748 set are considered to be unconstrained and will run with no
750 See tip/Documentation/scheduler/sched-bwc.txt for more information.
752 config RT_GROUP_SCHED
753 bool "Group scheduling for SCHED_RR/FIFO"
754 depends on CGROUP_SCHED
757 This feature lets you explicitly allocate real CPU bandwidth
758 to task groups. If enabled, it will also make it impossible to
759 schedule realtime tasks for non-root users until you allocate
760 realtime bandwidth for them.
761 See Documentation/scheduler/sched-rt-group.txt for more information.
766 bool "PIDs controller"
768 Provides enforcement of process number limits in the scope of a
769 cgroup. Any attempt to fork more processes than is allowed in the
770 cgroup will fail. PIDs are fundamentally a global resource because it
771 is fairly trivial to reach PID exhaustion before you reach even a
772 conservative kmemcg limit. As a result, it is possible to grind a
773 system to halt without being limited by other cgroup policies. The
774 PIDs controller is designed to stop this from happening.
776 It should be noted that organisational operations (such as attaching
777 to a cgroup hierarchy will *not* be blocked by the PIDs controller),
778 since the PIDs limit only affects a process's ability to fork, not to
782 bool "RDMA controller"
784 Provides enforcement of RDMA resources defined by IB stack.
785 It is fairly easy for consumers to exhaust RDMA resources, which
786 can result into resource unavailability to other consumers.
787 RDMA controller is designed to stop this from happening.
788 Attaching processes with active RDMA resources to the cgroup
789 hierarchy is allowed even if can cross the hierarchy's limit.
791 config CGROUP_FREEZER
792 bool "Freezer controller"
794 Provides a way to freeze and unfreeze all tasks in a
797 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
798 controller includes important in-kernel memory consumers per default.
800 If you're using cgroup2, say N.
802 config CGROUP_HUGETLB
803 bool "HugeTLB controller"
804 depends on HUGETLB_PAGE
808 Provides a cgroup controller for HugeTLB pages.
809 When you enable this, you can put a per cgroup limit on HugeTLB usage.
810 The limit is enforced during page fault. Since HugeTLB doesn't
811 support page reclaim, enforcing the limit at page fault time implies
812 that, the application will get SIGBUS signal if it tries to access
813 HugeTLB pages beyond its limit. This requires the application to know
814 beforehand how much HugeTLB pages it would require for its use. The
815 control group is tracked in the third page lru pointer. This means
816 that we cannot use the controller with huge page less than 3 pages.
819 bool "Cpuset controller"
822 This option will let you create and manage CPUSETs which
823 allow dynamically partitioning a system into sets of CPUs and
824 Memory Nodes and assigning tasks to run only within those sets.
825 This is primarily useful on large SMP or NUMA systems.
829 config PROC_PID_CPUSET
830 bool "Include legacy /proc/<pid>/cpuset file"
835 bool "Device controller"
837 Provides a cgroup controller implementing whitelists for
838 devices which a process in the cgroup can mknod or open.
840 config CGROUP_CPUACCT
841 bool "Simple CPU accounting controller"
843 Provides a simple controller for monitoring the
844 total CPU consumed by the tasks in a cgroup.
847 bool "Perf controller"
848 depends on PERF_EVENTS
850 This option extends the perf per-cpu mode to restrict monitoring
851 to threads which belong to the cgroup specified and run on the
857 bool "Support for eBPF programs attached to cgroups"
858 depends on BPF_SYSCALL
859 select SOCK_CGROUP_DATA
861 Allow attaching eBPF programs to a cgroup using the bpf(2)
862 syscall command BPF_PROG_ATTACH.
864 In which context these programs are accessed depends on the type
865 of attachment. For instance, programs that are attached using
866 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
870 bool "Debug controller"
872 depends on DEBUG_KERNEL
874 This option enables a simple controller that exports
875 debugging information about the cgroups framework. This
876 controller is for control cgroup debugging only. Its
877 interfaces are not stable.
881 config SOCK_CGROUP_DATA
887 menuconfig NAMESPACES
888 bool "Namespaces support" if EXPERT
892 Provides the way to make tasks work with different objects using
893 the same id. For example same IPC id may refer to different objects
894 or same user id or pid may refer to different tasks when used in
895 different namespaces.
903 In this namespace tasks see different info provided with the
908 depends on (SYSVIPC || POSIX_MQUEUE)
911 In this namespace tasks work with IPC ids which correspond to
912 different IPC objects in different namespaces.
915 bool "User namespace"
918 This allows containers, i.e. vservers, to use user namespaces
919 to provide different user info for different servers.
921 When user namespaces are enabled in the kernel it is
922 recommended that the MEMCG option also be enabled and that
923 user-space use the memory control groups to limit the amount
924 of memory a memory unprivileged users can use.
929 bool "PID Namespaces"
932 Support process id namespaces. This allows having multiple
933 processes with the same pid as long as they are in different
934 pid namespaces. This is a building block of containers.
937 bool "Network namespace"
941 Allow user space to create what appear to be multiple instances
942 of the network stack.
946 config SCHED_AUTOGROUP
947 bool "Automatic process group scheduling"
950 select FAIR_GROUP_SCHED
952 This option optimizes the scheduler for common desktop workloads by
953 automatically creating and populating task groups. This separation
954 of workloads isolates aggressive CPU burners (like build jobs) from
955 desktop applications. Task group autogeneration is currently based
958 config SYSFS_DEPRECATED
959 bool "Enable deprecated sysfs features to support old userspace tools"
963 This option adds code that switches the layout of the "block" class
964 devices, to not show up in /sys/class/block/, but only in
967 This switch is only active when the sysfs.deprecated=1 boot option is
968 passed or the SYSFS_DEPRECATED_V2 option is set.
970 This option allows new kernels to run on old distributions and tools,
971 which might get confused by /sys/class/block/. Since 2007/2008 all
972 major distributions and tools handle this just fine.
974 Recent distributions and userspace tools after 2009/2010 depend on
975 the existence of /sys/class/block/, and will not work with this
978 Only if you are using a new kernel on an old distribution, you might
981 config SYSFS_DEPRECATED_V2
982 bool "Enable deprecated sysfs features by default"
985 depends on SYSFS_DEPRECATED
987 Enable deprecated sysfs by default.
989 See the CONFIG_SYSFS_DEPRECATED option for more details about this
992 Only if you are using a new kernel on an old distribution, you might
993 need to say Y here. Even then, odds are you would not need it
994 enabled, you can always pass the boot option if absolutely necessary.
997 bool "Kernel->user space relay support (formerly relayfs)"
1000 This option enables support for relay interface support in
1001 certain file systems (such as debugfs).
1002 It is designed to provide an efficient mechanism for tools and
1003 facilities to relay large amounts of data from kernel space to
1008 config BLK_DEV_INITRD
1009 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1010 depends on BROKEN || !FRV
1012 The initial RAM filesystem is a ramfs which is loaded by the
1013 boot loader (loadlin or lilo) and that is mounted as root
1014 before the normal boot procedure. It is typically used to
1015 load modules needed to mount the "real" root file system,
1016 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1018 If RAM disk support (BLK_DEV_RAM) is also included, this
1019 also enables initial RAM disk (initrd) support and adds
1020 15 Kbytes (more on some other architectures) to the kernel size.
1026 source "usr/Kconfig"
1031 prompt "Compiler optimization level"
1032 default CC_OPTIMIZE_FOR_PERFORMANCE
1034 config CC_OPTIMIZE_FOR_PERFORMANCE
1035 bool "Optimize for performance"
1037 This is the default optimization level for the kernel, building
1038 with the "-O2" compiler flag for best performance and most
1039 helpful compile-time warnings.
1041 config CC_OPTIMIZE_FOR_SIZE
1042 bool "Optimize for size"
1044 Enabling this option will pass "-Os" instead of "-O2" to
1045 your compiler resulting in a smaller kernel.
1060 config SYSCTL_EXCEPTION_TRACE
1063 Enable support for /proc/sys/debug/exception-trace.
1065 config SYSCTL_ARCH_UNALIGN_NO_WARN
1068 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1069 Allows arch to define/use @no_unaligned_warning to possibly warn
1070 about unaligned access emulation going on under the hood.
1072 config SYSCTL_ARCH_UNALIGN_ALLOW
1075 Enable support for /proc/sys/kernel/unaligned-trap
1076 Allows arches to define/use @unaligned_enabled to runtime toggle
1077 the unaligned access emulation.
1078 see arch/parisc/kernel/unaligned.c for reference
1080 config HAVE_PCSPKR_PLATFORM
1083 # interpreter that classic socket filters depend on
1088 bool "Configure standard kernel features (expert users)"
1089 # Unhide debug options, to make the on-by-default options visible
1092 This option allows certain base kernel options and settings
1093 to be disabled or tweaked. This is for specialized
1094 environments which can tolerate a "non-standard" kernel.
1095 Only use this if you really know what you are doing.
1098 bool "Enable 16-bit UID system calls" if EXPERT
1099 depends on HAVE_UID16 && MULTIUSER
1102 This enables the legacy 16-bit UID syscall wrappers.
1105 bool "Multiple users, groups and capabilities support" if EXPERT
1108 This option enables support for non-root users, groups and
1111 If you say N here, all processes will run with UID 0, GID 0, and all
1112 possible capabilities. Saying N here also compiles out support for
1113 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1116 If unsure, say Y here.
1118 config SGETMASK_SYSCALL
1119 bool "sgetmask/ssetmask syscalls support" if EXPERT
1120 def_bool PARISC || MN10300 || BLACKFIN || M68K || PPC || MIPS || X86 || SPARC || CRIS || MICROBLAZE || SUPERH
1122 sys_sgetmask and sys_ssetmask are obsolete system calls
1123 no longer supported in libc but still enabled by default in some
1126 If unsure, leave the default option here.
1128 config SYSFS_SYSCALL
1129 bool "Sysfs syscall support" if EXPERT
1132 sys_sysfs is an obsolete system call no longer supported in libc.
1133 Note that disabling this option is more secure but might break
1134 compatibility with some systems.
1136 If unsure say Y here.
1138 config SYSCTL_SYSCALL
1139 bool "Sysctl syscall support" if EXPERT
1140 depends on PROC_SYSCTL
1144 sys_sysctl uses binary paths that have been found challenging
1145 to properly maintain and use. The interface in /proc/sys
1146 using paths with ascii names is now the primary path to this
1149 Almost nothing using the binary sysctl interface so if you are
1150 trying to save some space it is probably safe to disable this,
1151 making your kernel marginally smaller.
1153 If unsure say N here.
1156 bool "open by fhandle syscalls" if EXPERT
1160 If you say Y here, a user level program will be able to map
1161 file names to handle and then later use the handle for
1162 different file system operations. This is useful in implementing
1163 userspace file servers, which now track files using handles instead
1164 of names. The handle would remain the same even if file names
1165 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1169 bool "Posix Clocks & timers" if EXPERT
1172 This includes native support for POSIX timers to the kernel.
1173 Some embedded systems have no use for them and therefore they
1174 can be configured out to reduce the size of the kernel image.
1176 When this option is disabled, the following syscalls won't be
1177 available: timer_create, timer_gettime: timer_getoverrun,
1178 timer_settime, timer_delete, clock_adjtime, getitimer,
1179 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1180 clock_getres and clock_nanosleep syscalls will be limited to
1181 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1187 bool "Enable support for printk" if EXPERT
1190 This option enables normal printk support. Removing it
1191 eliminates most of the message strings from the kernel image
1192 and makes the kernel more or less silent. As this makes it
1193 very difficult to diagnose system problems, saying N here is
1194 strongly discouraged.
1202 bool "BUG() support" if EXPERT
1205 Disabling this option eliminates support for BUG and WARN, reducing
1206 the size of your kernel image and potentially quietly ignoring
1207 numerous fatal conditions. You should only consider disabling this
1208 option for embedded systems with no facilities for reporting errors.
1214 bool "Enable ELF core dumps" if EXPERT
1216 Enable support for generating core dumps. Disabling saves about 4k.
1219 config PCSPKR_PLATFORM
1220 bool "Enable PC-Speaker support" if EXPERT
1221 depends on HAVE_PCSPKR_PLATFORM
1225 This option allows to disable the internal PC-Speaker
1226 support, saving some memory.
1230 bool "Enable full-sized data structures for core" if EXPERT
1232 Disabling this option reduces the size of miscellaneous core
1233 kernel data structures. This saves memory on small machines,
1234 but may reduce performance.
1237 bool "Enable futex support" if EXPERT
1241 Disabling this option will cause the kernel to be built without
1242 support for "fast userspace mutexes". The resulting kernel may not
1243 run glibc-based applications correctly.
1247 depends on FUTEX && RT_MUTEXES
1250 config HAVE_FUTEX_CMPXCHG
1254 Architectures should select this if futex_atomic_cmpxchg_inatomic()
1255 is implemented and always working. This removes a couple of runtime
1259 bool "Enable eventpoll support" if EXPERT
1263 Disabling this option will cause the kernel to be built without
1264 support for epoll family of system calls.
1267 bool "Enable signalfd() system call" if EXPERT
1271 Enable the signalfd() system call that allows to receive signals
1272 on a file descriptor.
1277 bool "Enable timerfd() system call" if EXPERT
1281 Enable the timerfd() system call that allows to receive timer
1282 events on a file descriptor.
1287 bool "Enable eventfd() system call" if EXPERT
1291 Enable the eventfd() system call that allows to receive both
1292 kernel notification (ie. KAIO) or userspace notifications.
1297 bool "Use full shmem filesystem" if EXPERT
1301 The shmem is an internal filesystem used to manage shared memory.
1302 It is backed by swap and manages resource limits. It is also exported
1303 to userspace as tmpfs if TMPFS is enabled. Disabling this
1304 option replaces shmem and tmpfs with the much simpler ramfs code,
1305 which may be appropriate on small systems without swap.
1308 bool "Enable AIO support" if EXPERT
1311 This option enables POSIX asynchronous I/O which may by used
1312 by some high performance threaded applications. Disabling
1313 this option saves about 7k.
1315 config ADVISE_SYSCALLS
1316 bool "Enable madvise/fadvise syscalls" if EXPERT
1319 This option enables the madvise and fadvise syscalls, used by
1320 applications to advise the kernel about their future memory or file
1321 usage, improving performance. If building an embedded system where no
1322 applications use these syscalls, you can disable this option to save
1326 bool "Enable membarrier() system call" if EXPERT
1329 Enable the membarrier() system call that allows issuing memory
1330 barriers across all running threads, which can be used to distribute
1331 the cost of user-space memory barriers asymmetrically by transforming
1332 pairs of memory barriers into pairs consisting of membarrier() and a
1337 config CHECKPOINT_RESTORE
1338 bool "Checkpoint/restore support" if EXPERT
1339 select PROC_CHILDREN
1342 Enables additional kernel features in a sake of checkpoint/restore.
1343 In particular it adds auxiliary prctl codes to setup process text,
1344 data and heap segment sizes, and a few additional /proc filesystem
1347 If unsure, say N here.
1350 bool "Load all symbols for debugging/ksymoops" if EXPERT
1353 Say Y here to let the kernel print out symbolic crash information and
1354 symbolic stack backtraces. This increases the size of the kernel
1355 somewhat, as all symbols have to be loaded into the kernel image.
1358 bool "Include all symbols in kallsyms"
1359 depends on DEBUG_KERNEL && KALLSYMS
1361 Normally kallsyms only contains the symbols of functions for nicer
1362 OOPS messages and backtraces (i.e., symbols from the text and inittext
1363 sections). This is sufficient for most cases. And only in very rare
1364 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1365 names of variables from the data sections, etc).
1367 This option makes sure that all symbols are loaded into the kernel
1368 image (i.e., symbols from all sections) in cost of increased kernel
1369 size (depending on the kernel configuration, it may be 300KiB or
1370 something like this).
1372 Say N unless you really need all symbols.
1374 config KALLSYMS_ABSOLUTE_PERCPU
1377 default X86_64 && SMP
1379 config KALLSYMS_BASE_RELATIVE
1382 default !IA64 && !(TILE && 64BIT)
1384 Instead of emitting them as absolute values in the native word size,
1385 emit the symbol references in the kallsyms table as 32-bit entries,
1386 each containing a relative value in the range [base, base + U32_MAX]
1387 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1388 an absolute value in the range [0, S32_MAX] or a relative value in the
1389 range [base, base + S32_MAX], where base is the lowest relative symbol
1390 address encountered in the image.
1392 On 64-bit builds, this reduces the size of the address table by 50%,
1393 but more importantly, it results in entries whose values are build
1394 time constants, and no relocation pass is required at runtime to fix
1395 up the entries based on the runtime load address of the kernel.
1397 # end of the "standard kernel features (expert users)" menu
1399 # syscall, maps, verifier
1401 bool "Enable bpf() system call"
1406 Enable the bpf() system call that allows to manipulate eBPF
1407 programs and maps via file descriptors.
1409 config BPF_JIT_ALWAYS_ON
1410 bool "Permanently enable BPF JIT and remove BPF interpreter"
1411 depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
1413 Enables BPF JIT and removes BPF interpreter to avoid
1414 speculative execution of BPF instructions by the interpreter
1417 bool "Enable userfaultfd() system call"
1421 Enable the userfaultfd() system call that allows to intercept and
1422 handle page faults in userland.
1425 bool "Embedded system"
1426 option allnoconfig_y
1429 This option should be enabled if compiling the kernel for
1430 an embedded system so certain expert options are available
1433 config HAVE_PERF_EVENTS
1436 See tools/perf/design.txt for details.
1438 config PERF_USE_VMALLOC
1441 See tools/perf/design.txt for details
1444 bool "PC/104 support"
1446 Expose PC/104 form factor device drivers and options available for
1447 selection and configuration. Enable this option if your target
1448 machine has a PC/104 bus.
1450 menu "Kernel Performance Events And Counters"
1453 bool "Kernel performance events and counters"
1454 default y if PROFILING
1455 depends on HAVE_PERF_EVENTS
1460 Enable kernel support for various performance events provided
1461 by software and hardware.
1463 Software events are supported either built-in or via the
1464 use of generic tracepoints.
1466 Most modern CPUs support performance events via performance
1467 counter registers. These registers count the number of certain
1468 types of hw events: such as instructions executed, cachemisses
1469 suffered, or branches mis-predicted - without slowing down the
1470 kernel or applications. These registers can also trigger interrupts
1471 when a threshold number of events have passed - and can thus be
1472 used to profile the code that runs on that CPU.
1474 The Linux Performance Event subsystem provides an abstraction of
1475 these software and hardware event capabilities, available via a
1476 system call and used by the "perf" utility in tools/perf/. It
1477 provides per task and per CPU counters, and it provides event
1478 capabilities on top of those.
1482 config DEBUG_PERF_USE_VMALLOC
1484 bool "Debug: use vmalloc to back perf mmap() buffers"
1485 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1486 select PERF_USE_VMALLOC
1488 Use vmalloc memory to back perf mmap() buffers.
1490 Mostly useful for debugging the vmalloc code on platforms
1491 that don't require it.
1497 config VM_EVENT_COUNTERS
1499 bool "Enable VM event counters for /proc/vmstat" if EXPERT
1501 VM event counters are needed for event counts to be shown.
1502 This option allows the disabling of the VM event counters
1503 on EXPERT systems. /proc/vmstat will only show page counts
1504 if VM event counters are disabled.
1508 bool "Enable SLUB debugging support" if EXPERT
1509 depends on SLUB && SYSFS
1511 SLUB has extensive debug support features. Disabling these can
1512 result in significant savings in code size. This also disables
1513 SLUB sysfs support. /sys/slab will not exist and there will be
1514 no support for cache validation etc.
1516 config SLUB_MEMCG_SYSFS_ON
1518 bool "Enable memcg SLUB sysfs support by default" if EXPERT
1519 depends on SLUB && SYSFS && MEMCG
1521 SLUB creates a directory under /sys/kernel/slab for each
1522 allocation cache to host info and debug files. If memory
1523 cgroup is enabled, each cache can have per memory cgroup
1524 caches. SLUB can create the same sysfs directories for these
1525 caches under /sys/kernel/slab/CACHE/cgroup but it can lead
1526 to a very high number of debug files being created. This is
1527 controlled by slub_memcg_sysfs boot parameter and this
1528 config option determines the parameter's default value.
1531 bool "Disable heap randomization"
1534 Randomizing heap placement makes heap exploits harder, but it
1535 also breaks ancient binaries (including anything libc5 based).
1536 This option changes the bootup default to heap randomization
1537 disabled, and can be overridden at runtime by setting
1538 /proc/sys/kernel/randomize_va_space to 2.
1540 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1543 prompt "Choose SLAB allocator"
1546 This option allows to select a slab allocator.
1550 select HAVE_HARDENED_USERCOPY_ALLOCATOR
1552 The regular slab allocator that is established and known to work
1553 well in all environments. It organizes cache hot objects in
1554 per cpu and per node queues.
1557 bool "SLUB (Unqueued Allocator)"
1558 select HAVE_HARDENED_USERCOPY_ALLOCATOR
1560 SLUB is a slab allocator that minimizes cache line usage
1561 instead of managing queues of cached objects (SLAB approach).
1562 Per cpu caching is realized using slabs of objects instead
1563 of queues of objects. SLUB can use memory efficiently
1564 and has enhanced diagnostics. SLUB is the default choice for
1569 bool "SLOB (Simple Allocator)"
1571 SLOB replaces the stock allocator with a drastically simpler
1572 allocator. SLOB is generally more space efficient but
1573 does not perform as well on large systems.
1577 config SLAB_MERGE_DEFAULT
1578 bool "Allow slab caches to be merged"
1581 For reduced kernel memory fragmentation, slab caches can be
1582 merged when they share the same size and other characteristics.
1583 This carries a risk of kernel heap overflows being able to
1584 overwrite objects from merged caches (and more easily control
1585 cache layout), which makes such heap attacks easier to exploit
1586 by attackers. By keeping caches unmerged, these kinds of exploits
1587 can usually only damage objects in the same cache. To disable
1588 merging at runtime, "slab_nomerge" can be passed on the kernel
1591 config SLAB_FREELIST_RANDOM
1593 depends on SLAB || SLUB
1594 bool "SLAB freelist randomization"
1596 Randomizes the freelist order used on creating new pages. This
1597 security feature reduces the predictability of the kernel slab
1598 allocator against heap overflows.
1600 config SLAB_FREELIST_HARDENED
1601 bool "Harden slab freelist metadata"
1604 Many kernel heap attacks try to target slab cache metadata and
1605 other infrastructure. This options makes minor performance
1606 sacrifies to harden the kernel slab allocator against common
1607 freelist exploit methods.
1609 config SLUB_CPU_PARTIAL
1611 depends on SLUB && SMP
1612 bool "SLUB per cpu partial cache"
1614 Per cpu partial caches accellerate objects allocation and freeing
1615 that is local to a processor at the price of more indeterminism
1616 in the latency of the free. On overflow these caches will be cleared
1617 which requires the taking of locks that may cause latency spikes.
1618 Typically one would choose no for a realtime system.
1620 config MMAP_ALLOW_UNINITIALIZED
1621 bool "Allow mmapped anonymous memory to be uninitialized"
1622 depends on EXPERT && !MMU
1625 Normally, and according to the Linux spec, anonymous memory obtained
1626 from mmap() has it's contents cleared before it is passed to
1627 userspace. Enabling this config option allows you to request that
1628 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1629 providing a huge performance boost. If this option is not enabled,
1630 then the flag will be ignored.
1632 This is taken advantage of by uClibc's malloc(), and also by
1633 ELF-FDPIC binfmt's brk and stack allocator.
1635 Because of the obvious security issues, this option should only be
1636 enabled on embedded devices where you control what is run in
1637 userspace. Since that isn't generally a problem on no-MMU systems,
1638 it is normally safe to say Y here.
1640 See Documentation/nommu-mmap.txt for more information.
1642 config SYSTEM_DATA_VERIFICATION
1644 select SYSTEM_TRUSTED_KEYRING
1648 select ASYMMETRIC_KEY_TYPE
1649 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1652 select X509_CERTIFICATE_PARSER
1653 select PKCS7_MESSAGE_PARSER
1655 Provide PKCS#7 message verification using the contents of the system
1656 trusted keyring to provide public keys. This then can be used for
1657 module verification, kexec image verification and firmware blob
1661 bool "Profiling support"
1663 Say Y here to enable the extended profiling support mechanisms used
1664 by profilers such as OProfile.
1667 # Place an empty function call at each tracepoint site. Can be
1668 # dynamically changed for a probe function.
1673 source "arch/Kconfig"
1675 endmenu # General setup
1677 config HAVE_GENERIC_DMA_COHERENT
1686 default 0 if BASE_FULL
1687 default 1 if !BASE_FULL
1690 bool "Enable loadable module support"
1693 Kernel modules are small pieces of compiled code which can
1694 be inserted in the running kernel, rather than being
1695 permanently built into the kernel. You use the "modprobe"
1696 tool to add (and sometimes remove) them. If you say Y here,
1697 many parts of the kernel can be built as modules (by
1698 answering M instead of Y where indicated): this is most
1699 useful for infrequently used options which are not required
1700 for booting. For more information, see the man pages for
1701 modprobe, lsmod, modinfo, insmod and rmmod.
1703 If you say Y here, you will need to run "make
1704 modules_install" to put the modules under /lib/modules/
1705 where modprobe can find them (you may need to be root to do
1712 config MODULE_FORCE_LOAD
1713 bool "Forced module loading"
1716 Allow loading of modules without version information (ie. modprobe
1717 --force). Forced module loading sets the 'F' (forced) taint flag and
1718 is usually a really bad idea.
1720 config MODULE_UNLOAD
1721 bool "Module unloading"
1723 Without this option you will not be able to unload any
1724 modules (note that some modules may not be unloadable
1725 anyway), which makes your kernel smaller, faster
1726 and simpler. If unsure, say Y.
1728 config MODULE_FORCE_UNLOAD
1729 bool "Forced module unloading"
1730 depends on MODULE_UNLOAD
1732 This option allows you to force a module to unload, even if the
1733 kernel believes it is unsafe: the kernel will remove the module
1734 without waiting for anyone to stop using it (using the -f option to
1735 rmmod). This is mainly for kernel developers and desperate users.
1739 bool "Module versioning support"
1741 Usually, you have to use modules compiled with your kernel.
1742 Saying Y here makes it sometimes possible to use modules
1743 compiled for different kernels, by adding enough information
1744 to the modules to (hopefully) spot any changes which would
1745 make them incompatible with the kernel you are running. If
1748 config MODULE_REL_CRCS
1750 depends on MODVERSIONS
1752 config MODULE_SRCVERSION_ALL
1753 bool "Source checksum for all modules"
1755 Modules which contain a MODULE_VERSION get an extra "srcversion"
1756 field inserted into their modinfo section, which contains a
1757 sum of the source files which made it. This helps maintainers
1758 see exactly which source was used to build a module (since
1759 others sometimes change the module source without updating
1760 the version). With this option, such a "srcversion" field
1761 will be created for all modules. If unsure, say N.
1764 bool "Module signature verification"
1766 select SYSTEM_DATA_VERIFICATION
1768 Check modules for valid signatures upon load: the signature
1769 is simply appended to the module. For more information see
1770 <file:Documentation/admin-guide/module-signing.rst>.
1772 Note that this option adds the OpenSSL development packages as a
1773 kernel build dependency so that the signing tool can use its crypto
1776 !!!WARNING!!! If you enable this option, you MUST make sure that the
1777 module DOES NOT get stripped after being signed. This includes the
1778 debuginfo strip done by some packagers (such as rpmbuild) and
1779 inclusion into an initramfs that wants the module size reduced.
1781 config MODULE_SIG_FORCE
1782 bool "Require modules to be validly signed"
1783 depends on MODULE_SIG
1785 Reject unsigned modules or signed modules for which we don't have a
1786 key. Without this, such modules will simply taint the kernel.
1788 config MODULE_SIG_ALL
1789 bool "Automatically sign all modules"
1791 depends on MODULE_SIG
1793 Sign all modules during make modules_install. Without this option,
1794 modules must be signed manually, using the scripts/sign-file tool.
1796 comment "Do not forget to sign required modules with scripts/sign-file"
1797 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
1800 prompt "Which hash algorithm should modules be signed with?"
1801 depends on MODULE_SIG
1803 This determines which sort of hashing algorithm will be used during
1804 signature generation. This algorithm _must_ be built into the kernel
1805 directly so that signature verification can take place. It is not
1806 possible to load a signed module containing the algorithm to check
1807 the signature on that module.
1809 config MODULE_SIG_SHA1
1810 bool "Sign modules with SHA-1"
1813 config MODULE_SIG_SHA224
1814 bool "Sign modules with SHA-224"
1815 select CRYPTO_SHA256
1817 config MODULE_SIG_SHA256
1818 bool "Sign modules with SHA-256"
1819 select CRYPTO_SHA256
1821 config MODULE_SIG_SHA384
1822 bool "Sign modules with SHA-384"
1823 select CRYPTO_SHA512
1825 config MODULE_SIG_SHA512
1826 bool "Sign modules with SHA-512"
1827 select CRYPTO_SHA512
1831 config MODULE_SIG_HASH
1833 depends on MODULE_SIG
1834 default "sha1" if MODULE_SIG_SHA1
1835 default "sha224" if MODULE_SIG_SHA224
1836 default "sha256" if MODULE_SIG_SHA256
1837 default "sha384" if MODULE_SIG_SHA384
1838 default "sha512" if MODULE_SIG_SHA512
1840 config MODULE_COMPRESS
1841 bool "Compress modules on installation"
1845 Compresses kernel modules when 'make modules_install' is run; gzip or
1846 xz depending on "Compression algorithm" below.
1848 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
1850 Out-of-tree kernel modules installed using Kbuild will also be
1851 compressed upon installation.
1853 Note: for modules inside an initrd or initramfs, it's more efficient
1854 to compress the whole initrd or initramfs instead.
1856 Note: This is fully compatible with signed modules.
1861 prompt "Compression algorithm"
1862 depends on MODULE_COMPRESS
1863 default MODULE_COMPRESS_GZIP
1865 This determines which sort of compression will be used during
1866 'make modules_install'.
1868 GZIP (default) and XZ are supported.
1870 config MODULE_COMPRESS_GZIP
1873 config MODULE_COMPRESS_XZ
1878 config TRIM_UNUSED_KSYMS
1879 bool "Trim unused exported kernel symbols"
1880 depends on MODULES && !UNUSED_SYMBOLS
1882 The kernel and some modules make many symbols available for
1883 other modules to use via EXPORT_SYMBOL() and variants. Depending
1884 on the set of modules being selected in your kernel configuration,
1885 many of those exported symbols might never be used.
1887 This option allows for unused exported symbols to be dropped from
1888 the build. In turn, this provides the compiler more opportunities
1889 (especially when using LTO) for optimizing the code and reducing
1890 binary size. This might have some security advantages as well.
1892 If unsure, or if you need to build out-of-tree modules, say N.
1896 config MODULES_TREE_LOOKUP
1898 depends on PERF_EVENTS || TRACING
1900 config INIT_ALL_POSSIBLE
1903 Back when each arch used to define their own cpu_online_mask and
1904 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
1905 with all 1s, and others with all 0s. When they were centralised,
1906 it was better to provide this option than to break all the archs
1907 and have several arch maintainers pursuing me down dark alleys.
1909 source "block/Kconfig"
1911 config PREEMPT_NOTIFIERS
1921 Build a simple ASN.1 grammar compiler that produces a bytecode output
1922 that can be interpreted by the ASN.1 stream decoder and used to
1923 inform it as to what tags are to be expected in a stream and what
1924 functions to call on what tags.
1926 source "kernel/Kconfig.locks"
projects / mirror_ubuntu-bionic-kernel.git / blob