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.
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"
475 source "kernel/rcu/Kconfig"
482 tristate "Kernel .config support"
485 This option enables the complete Linux kernel ".config" file
486 contents to be saved in the kernel. It provides documentation
487 of which kernel options are used in a running kernel or in an
488 on-disk kernel. This information can be extracted from the kernel
489 image file with the script scripts/extract-ikconfig and used as
490 input to rebuild the current kernel or to build another kernel.
491 It can also be extracted from a running kernel by reading
492 /proc/config.gz if enabled (below).
495 bool "Enable access to .config through /proc/config.gz"
496 depends on IKCONFIG && PROC_FS
498 This option enables access to the kernel configuration file
499 through /proc/config.gz.
502 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
507 Select the minimal kernel log buffer size as a power of 2.
508 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
509 parameter, see below. Any higher size also might be forced
510 by "log_buf_len" boot parameter.
520 config LOG_CPU_MAX_BUF_SHIFT
521 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
524 default 12 if !BASE_SMALL
525 default 0 if BASE_SMALL
528 This option allows to increase the default ring buffer size
529 according to the number of CPUs. The value defines the contribution
530 of each CPU as a power of 2. The used space is typically only few
531 lines however it might be much more when problems are reported,
534 The increased size means that a new buffer has to be allocated and
535 the original static one is unused. It makes sense only on systems
536 with more CPUs. Therefore this value is used only when the sum of
537 contributions is greater than the half of the default kernel ring
538 buffer as defined by LOG_BUF_SHIFT. The default values are set
539 so that more than 64 CPUs are needed to trigger the allocation.
541 Also this option is ignored when "log_buf_len" kernel parameter is
542 used as it forces an exact (power of two) size of the ring buffer.
544 The number of possible CPUs is used for this computation ignoring
545 hotplugging making the computation optimal for the worst case
546 scenario while allowing a simple algorithm to be used from bootup.
548 Examples shift values and their meaning:
549 17 => 128 KB for each CPU
550 16 => 64 KB for each CPU
551 15 => 32 KB for each CPU
552 14 => 16 KB for each CPU
553 13 => 8 KB for each CPU
554 12 => 4 KB for each CPU
556 config PRINTK_SAFE_LOG_BUF_SHIFT
557 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
562 Select the size of an alternate printk per-CPU buffer where messages
563 printed from usafe contexts are temporary stored. One example would
564 be NMI messages, another one - printk recursion. The messages are
565 copied to the main log buffer in a safe context to avoid a deadlock.
566 The value defines the size as a power of 2.
568 Those messages are rare and limited. The largest one is when
569 a backtrace is printed. It usually fits into 4KB. Select
570 8KB if you want to be on the safe side.
573 17 => 128 KB for each CPU
574 16 => 64 KB for each CPU
575 15 => 32 KB for each CPU
576 14 => 16 KB for each CPU
577 13 => 8 KB for each CPU
578 12 => 4 KB for each CPU
581 # Architectures with an unreliable sched_clock() should select this:
583 config HAVE_UNSTABLE_SCHED_CLOCK
586 config GENERIC_SCHED_CLOCK
590 # For architectures that want to enable the support for NUMA-affine scheduler
593 config ARCH_SUPPORTS_NUMA_BALANCING
597 # For architectures that prefer to flush all TLBs after a number of pages
598 # are unmapped instead of sending one IPI per page to flush. The architecture
599 # must provide guarantees on what happens if a clean TLB cache entry is
600 # written after the unmap. Details are in mm/rmap.c near the check for
601 # should_defer_flush. The architecture should also consider if the full flush
602 # and the refill costs are offset by the savings of sending fewer IPIs.
603 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
607 # For architectures that know their GCC __int128 support is sound
609 config ARCH_SUPPORTS_INT128
612 # For architectures that (ab)use NUMA to represent different memory regions
613 # all cpu-local but of different latencies, such as SuperH.
615 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
618 config NUMA_BALANCING
619 bool "Memory placement aware NUMA scheduler"
620 depends on ARCH_SUPPORTS_NUMA_BALANCING
621 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
622 depends on SMP && NUMA && MIGRATION
624 This option adds support for automatic NUMA aware memory/task placement.
625 The mechanism is quite primitive and is based on migrating memory when
626 it has references to the node the task is running on.
628 This system will be inactive on UMA systems.
630 config NUMA_BALANCING_DEFAULT_ENABLED
631 bool "Automatically enable NUMA aware memory/task placement"
633 depends on NUMA_BALANCING
635 If set, automatic NUMA balancing will be enabled if running on a NUMA
639 bool "Control Group support"
642 This option adds support for grouping sets of processes together, for
643 use with process control subsystems such as Cpusets, CFS, memory
644 controls or device isolation.
646 - Documentation/scheduler/sched-design-CFS.txt (CFS)
647 - Documentation/cgroup-v1/ (features for grouping, isolation
648 and resource control)
658 bool "Memory controller"
662 Provides control over the memory footprint of tasks in a cgroup.
665 bool "Swap controller"
666 depends on MEMCG && SWAP
668 Provides control over the swap space consumed by tasks in a cgroup.
670 config MEMCG_SWAP_ENABLED
671 bool "Swap controller enabled by default"
672 depends on MEMCG_SWAP
675 Memory Resource Controller Swap Extension comes with its price in
676 a bigger memory consumption. General purpose distribution kernels
677 which want to enable the feature but keep it disabled by default
678 and let the user enable it by swapaccount=1 boot command line
679 parameter should have this option unselected.
680 For those who want to have the feature enabled by default should
681 select this option (if, for some reason, they need to disable it
682 then swapaccount=0 does the trick).
689 Generic block IO controller cgroup interface. This is the common
690 cgroup interface which should be used by various IO controlling
693 Currently, CFQ IO scheduler uses it to recognize task groups and
694 control disk bandwidth allocation (proportional time slice allocation)
695 to such task groups. It is also used by bio throttling logic in
696 block layer to implement upper limit in IO rates on a device.
698 This option only enables generic Block IO controller infrastructure.
699 One needs to also enable actual IO controlling logic/policy. For
700 enabling proportional weight division of disk bandwidth in CFQ, set
701 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
702 CONFIG_BLK_DEV_THROTTLING=y.
704 See Documentation/cgroup-v1/blkio-controller.txt for more information.
706 config DEBUG_BLK_CGROUP
707 bool "IO controller debugging"
708 depends on BLK_CGROUP
711 Enable some debugging help. Currently it exports additional stat
712 files in a cgroup which can be useful for debugging.
714 config CGROUP_WRITEBACK
716 depends on MEMCG && BLK_CGROUP
719 menuconfig CGROUP_SCHED
720 bool "CPU controller"
723 This feature lets CPU scheduler recognize task groups and control CPU
724 bandwidth allocation to such task groups. It uses cgroups to group
728 config FAIR_GROUP_SCHED
729 bool "Group scheduling for SCHED_OTHER"
730 depends on CGROUP_SCHED
734 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
735 depends on FAIR_GROUP_SCHED
738 This option allows users to define CPU bandwidth rates (limits) for
739 tasks running within the fair group scheduler. Groups with no limit
740 set are considered to be unconstrained and will run with no
742 See tip/Documentation/scheduler/sched-bwc.txt for more information.
744 config RT_GROUP_SCHED
745 bool "Group scheduling for SCHED_RR/FIFO"
746 depends on CGROUP_SCHED
749 This feature lets you explicitly allocate real CPU bandwidth
750 to task groups. If enabled, it will also make it impossible to
751 schedule realtime tasks for non-root users until you allocate
752 realtime bandwidth for them.
753 See Documentation/scheduler/sched-rt-group.txt for more information.
758 bool "PIDs controller"
760 Provides enforcement of process number limits in the scope of a
761 cgroup. Any attempt to fork more processes than is allowed in the
762 cgroup will fail. PIDs are fundamentally a global resource because it
763 is fairly trivial to reach PID exhaustion before you reach even a
764 conservative kmemcg limit. As a result, it is possible to grind a
765 system to halt without being limited by other cgroup policies. The
766 PIDs controller is designed to stop this from happening.
768 It should be noted that organisational operations (such as attaching
769 to a cgroup hierarchy will *not* be blocked by the PIDs controller),
770 since the PIDs limit only affects a process's ability to fork, not to
774 bool "RDMA controller"
776 Provides enforcement of RDMA resources defined by IB stack.
777 It is fairly easy for consumers to exhaust RDMA resources, which
778 can result into resource unavailability to other consumers.
779 RDMA controller is designed to stop this from happening.
780 Attaching processes with active RDMA resources to the cgroup
781 hierarchy is allowed even if can cross the hierarchy's limit.
783 config CGROUP_FREEZER
784 bool "Freezer controller"
786 Provides a way to freeze and unfreeze all tasks in a
789 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
790 controller includes important in-kernel memory consumers per default.
792 If you're using cgroup2, say N.
794 config CGROUP_HUGETLB
795 bool "HugeTLB controller"
796 depends on HUGETLB_PAGE
800 Provides a cgroup controller for HugeTLB pages.
801 When you enable this, you can put a per cgroup limit on HugeTLB usage.
802 The limit is enforced during page fault. Since HugeTLB doesn't
803 support page reclaim, enforcing the limit at page fault time implies
804 that, the application will get SIGBUS signal if it tries to access
805 HugeTLB pages beyond its limit. This requires the application to know
806 beforehand how much HugeTLB pages it would require for its use. The
807 control group is tracked in the third page lru pointer. This means
808 that we cannot use the controller with huge page less than 3 pages.
811 bool "Cpuset controller"
814 This option will let you create and manage CPUSETs which
815 allow dynamically partitioning a system into sets of CPUs and
816 Memory Nodes and assigning tasks to run only within those sets.
817 This is primarily useful on large SMP or NUMA systems.
821 config PROC_PID_CPUSET
822 bool "Include legacy /proc/<pid>/cpuset file"
827 bool "Device controller"
829 Provides a cgroup controller implementing whitelists for
830 devices which a process in the cgroup can mknod or open.
832 config CGROUP_CPUACCT
833 bool "Simple CPU accounting controller"
835 Provides a simple controller for monitoring the
836 total CPU consumed by the tasks in a cgroup.
839 bool "Perf controller"
840 depends on PERF_EVENTS
842 This option extends the perf per-cpu mode to restrict monitoring
843 to threads which belong to the cgroup specified and run on the
849 bool "Support for eBPF programs attached to cgroups"
850 depends on BPF_SYSCALL
851 select SOCK_CGROUP_DATA
853 Allow attaching eBPF programs to a cgroup using the bpf(2)
854 syscall command BPF_PROG_ATTACH.
856 In which context these programs are accessed depends on the type
857 of attachment. For instance, programs that are attached using
858 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
862 bool "Example controller"
865 This option enables a simple controller that exports
866 debugging information about the cgroups framework.
870 config SOCK_CGROUP_DATA
876 config CHECKPOINT_RESTORE
877 bool "Checkpoint/restore support" if EXPERT
881 Enables additional kernel features in a sake of checkpoint/restore.
882 In particular it adds auxiliary prctl codes to setup process text,
883 data and heap segment sizes, and a few additional /proc filesystem
886 If unsure, say N here.
888 menuconfig NAMESPACES
889 bool "Namespaces support" if EXPERT
893 Provides the way to make tasks work with different objects using
894 the same id. For example same IPC id may refer to different objects
895 or same user id or pid may refer to different tasks when used in
896 different namespaces.
904 In this namespace tasks see different info provided with the
909 depends on (SYSVIPC || POSIX_MQUEUE)
912 In this namespace tasks work with IPC ids which correspond to
913 different IPC objects in different namespaces.
916 bool "User namespace"
919 This allows containers, i.e. vservers, to use user namespaces
920 to provide different user info for different servers.
922 When user namespaces are enabled in the kernel it is
923 recommended that the MEMCG option also be enabled and that
924 user-space use the memory control groups to limit the amount
925 of memory a memory unprivileged users can use.
930 bool "PID Namespaces"
933 Support process id namespaces. This allows having multiple
934 processes with the same pid as long as they are in different
935 pid namespaces. This is a building block of containers.
938 bool "Network namespace"
942 Allow user space to create what appear to be multiple instances
943 of the network stack.
947 config SCHED_AUTOGROUP
948 bool "Automatic process group scheduling"
951 select FAIR_GROUP_SCHED
953 This option optimizes the scheduler for common desktop workloads by
954 automatically creating and populating task groups. This separation
955 of workloads isolates aggressive CPU burners (like build jobs) from
956 desktop applications. Task group autogeneration is currently based
959 config SYSFS_DEPRECATED
960 bool "Enable deprecated sysfs features to support old userspace tools"
964 This option adds code that switches the layout of the "block" class
965 devices, to not show up in /sys/class/block/, but only in
968 This switch is only active when the sysfs.deprecated=1 boot option is
969 passed or the SYSFS_DEPRECATED_V2 option is set.
971 This option allows new kernels to run on old distributions and tools,
972 which might get confused by /sys/class/block/. Since 2007/2008 all
973 major distributions and tools handle this just fine.
975 Recent distributions and userspace tools after 2009/2010 depend on
976 the existence of /sys/class/block/, and will not work with this
979 Only if you are using a new kernel on an old distribution, you might
982 config SYSFS_DEPRECATED_V2
983 bool "Enable deprecated sysfs features by default"
986 depends on SYSFS_DEPRECATED
988 Enable deprecated sysfs by default.
990 See the CONFIG_SYSFS_DEPRECATED option for more details about this
993 Only if you are using a new kernel on an old distribution, you might
994 need to say Y here. Even then, odds are you would not need it
995 enabled, you can always pass the boot option if absolutely necessary.
998 bool "Kernel->user space relay support (formerly relayfs)"
1001 This option enables support for relay interface support in
1002 certain file systems (such as debugfs).
1003 It is designed to provide an efficient mechanism for tools and
1004 facilities to relay large amounts of data from kernel space to
1009 config BLK_DEV_INITRD
1010 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1011 depends on BROKEN || !FRV
1013 The initial RAM filesystem is a ramfs which is loaded by the
1014 boot loader (loadlin or lilo) and that is mounted as root
1015 before the normal boot procedure. It is typically used to
1016 load modules needed to mount the "real" root file system,
1017 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1019 If RAM disk support (BLK_DEV_RAM) is also included, this
1020 also enables initial RAM disk (initrd) support and adds
1021 15 Kbytes (more on some other architectures) to the kernel size.
1027 source "usr/Kconfig"
1032 prompt "Compiler optimization level"
1033 default CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE
1035 config CC_OPTIMIZE_FOR_PERFORMANCE
1036 bool "Optimize for performance"
1038 This is the default optimization level for the kernel, building
1039 with the "-O2" compiler flag for best performance and most
1040 helpful compile-time warnings.
1042 config CC_OPTIMIZE_FOR_SIZE
1043 bool "Optimize for size"
1045 Enabling this option will pass "-Os" instead of "-O2" to
1046 your compiler resulting in a smaller kernel.
1061 config SYSCTL_EXCEPTION_TRACE
1064 Enable support for /proc/sys/debug/exception-trace.
1066 config SYSCTL_ARCH_UNALIGN_NO_WARN
1069 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1070 Allows arch to define/use @no_unaligned_warning to possibly warn
1071 about unaligned access emulation going on under the hood.
1073 config SYSCTL_ARCH_UNALIGN_ALLOW
1076 Enable support for /proc/sys/kernel/unaligned-trap
1077 Allows arches to define/use @unaligned_enabled to runtime toggle
1078 the unaligned access emulation.
1079 see arch/parisc/kernel/unaligned.c for reference
1081 config HAVE_PCSPKR_PLATFORM
1084 # interpreter that classic socket filters depend on
1089 bool "Configure standard kernel features (expert users)"
1090 # Unhide debug options, to make the on-by-default options visible
1093 This option allows certain base kernel options and settings
1094 to be disabled or tweaked. This is for specialized
1095 environments which can tolerate a "non-standard" kernel.
1096 Only use this if you really know what you are doing.
1099 bool "Enable 16-bit UID system calls" if EXPERT
1100 depends on HAVE_UID16 && MULTIUSER
1103 This enables the legacy 16-bit UID syscall wrappers.
1106 bool "Multiple users, groups and capabilities support" if EXPERT
1109 This option enables support for non-root users, groups and
1112 If you say N here, all processes will run with UID 0, GID 0, and all
1113 possible capabilities. Saying N here also compiles out support for
1114 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1117 If unsure, say Y here.
1119 config SGETMASK_SYSCALL
1120 bool "sgetmask/ssetmask syscalls support" if EXPERT
1121 def_bool PARISC || MN10300 || BLACKFIN || M68K || PPC || MIPS || X86 || SPARC || CRIS || MICROBLAZE || SUPERH
1123 sys_sgetmask and sys_ssetmask are obsolete system calls
1124 no longer supported in libc but still enabled by default in some
1127 If unsure, leave the default option here.
1129 config SYSFS_SYSCALL
1130 bool "Sysfs syscall support" if EXPERT
1133 sys_sysfs is an obsolete system call no longer supported in libc.
1134 Note that disabling this option is more secure but might break
1135 compatibility with some systems.
1137 If unsure say Y here.
1139 config SYSCTL_SYSCALL
1140 bool "Sysctl syscall support" if EXPERT
1141 depends on PROC_SYSCTL
1145 sys_sysctl uses binary paths that have been found challenging
1146 to properly maintain and use. The interface in /proc/sys
1147 using paths with ascii names is now the primary path to this
1150 Almost nothing using the binary sysctl interface so if you are
1151 trying to save some space it is probably safe to disable this,
1152 making your kernel marginally smaller.
1154 If unsure say N here.
1157 bool "Posix Clocks & timers" if EXPERT
1160 This includes native support for POSIX timers to the kernel.
1161 Some embedded systems have no use for them and therefore they
1162 can be configured out to reduce the size of the kernel image.
1164 When this option is disabled, the following syscalls won't be
1165 available: timer_create, timer_gettime: timer_getoverrun,
1166 timer_settime, timer_delete, clock_adjtime, getitimer,
1167 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1168 clock_getres and clock_nanosleep syscalls will be limited to
1169 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1174 bool "Load all symbols for debugging/ksymoops" if EXPERT
1177 Say Y here to let the kernel print out symbolic crash information and
1178 symbolic stack backtraces. This increases the size of the kernel
1179 somewhat, as all symbols have to be loaded into the kernel image.
1182 bool "Include all symbols in kallsyms"
1183 depends on DEBUG_KERNEL && KALLSYMS
1185 Normally kallsyms only contains the symbols of functions for nicer
1186 OOPS messages and backtraces (i.e., symbols from the text and inittext
1187 sections). This is sufficient for most cases. And only in very rare
1188 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1189 names of variables from the data sections, etc).
1191 This option makes sure that all symbols are loaded into the kernel
1192 image (i.e., symbols from all sections) in cost of increased kernel
1193 size (depending on the kernel configuration, it may be 300KiB or
1194 something like this).
1196 Say N unless you really need all symbols.
1198 config KALLSYMS_ABSOLUTE_PERCPU
1201 default X86_64 && SMP
1203 config KALLSYMS_BASE_RELATIVE
1206 default !IA64 && !(TILE && 64BIT)
1208 Instead of emitting them as absolute values in the native word size,
1209 emit the symbol references in the kallsyms table as 32-bit entries,
1210 each containing a relative value in the range [base, base + U32_MAX]
1211 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1212 an absolute value in the range [0, S32_MAX] or a relative value in the
1213 range [base, base + S32_MAX], where base is the lowest relative symbol
1214 address encountered in the image.
1216 On 64-bit builds, this reduces the size of the address table by 50%,
1217 but more importantly, it results in entries whose values are build
1218 time constants, and no relocation pass is required at runtime to fix
1219 up the entries based on the runtime load address of the kernel.
1223 bool "Enable support for printk" if EXPERT
1226 This option enables normal printk support. Removing it
1227 eliminates most of the message strings from the kernel image
1228 and makes the kernel more or less silent. As this makes it
1229 very difficult to diagnose system problems, saying N here is
1230 strongly discouraged.
1238 bool "BUG() support" if EXPERT
1241 Disabling this option eliminates support for BUG and WARN, reducing
1242 the size of your kernel image and potentially quietly ignoring
1243 numerous fatal conditions. You should only consider disabling this
1244 option for embedded systems with no facilities for reporting errors.
1250 bool "Enable ELF core dumps" if EXPERT
1252 Enable support for generating core dumps. Disabling saves about 4k.
1255 config PCSPKR_PLATFORM
1256 bool "Enable PC-Speaker support" if EXPERT
1257 depends on HAVE_PCSPKR_PLATFORM
1261 This option allows to disable the internal PC-Speaker
1262 support, saving some memory.
1266 bool "Enable full-sized data structures for core" if EXPERT
1268 Disabling this option reduces the size of miscellaneous core
1269 kernel data structures. This saves memory on small machines,
1270 but may reduce performance.
1273 bool "Enable futex support" if EXPERT
1277 Disabling this option will cause the kernel to be built without
1278 support for "fast userspace mutexes". The resulting kernel may not
1279 run glibc-based applications correctly.
1281 config HAVE_FUTEX_CMPXCHG
1285 Architectures should select this if futex_atomic_cmpxchg_inatomic()
1286 is implemented and always working. This removes a couple of runtime
1290 bool "Enable eventpoll support" if EXPERT
1294 Disabling this option will cause the kernel to be built without
1295 support for epoll family of system calls.
1298 bool "Enable signalfd() system call" if EXPERT
1302 Enable the signalfd() system call that allows to receive signals
1303 on a file descriptor.
1308 bool "Enable timerfd() system call" if EXPERT
1312 Enable the timerfd() system call that allows to receive timer
1313 events on a file descriptor.
1318 bool "Enable eventfd() system call" if EXPERT
1322 Enable the eventfd() system call that allows to receive both
1323 kernel notification (ie. KAIO) or userspace notifications.
1327 # syscall, maps, verifier
1329 bool "Enable bpf() system call"
1334 Enable the bpf() system call that allows to manipulate eBPF
1335 programs and maps via file descriptors.
1338 bool "Use full shmem filesystem" if EXPERT
1342 The shmem is an internal filesystem used to manage shared memory.
1343 It is backed by swap and manages resource limits. It is also exported
1344 to userspace as tmpfs if TMPFS is enabled. Disabling this
1345 option replaces shmem and tmpfs with the much simpler ramfs code,
1346 which may be appropriate on small systems without swap.
1349 bool "Enable AIO support" if EXPERT
1352 This option enables POSIX asynchronous I/O which may by used
1353 by some high performance threaded applications. Disabling
1354 this option saves about 7k.
1356 config ADVISE_SYSCALLS
1357 bool "Enable madvise/fadvise syscalls" if EXPERT
1360 This option enables the madvise and fadvise syscalls, used by
1361 applications to advise the kernel about their future memory or file
1362 usage, improving performance. If building an embedded system where no
1363 applications use these syscalls, you can disable this option to save
1367 bool "Enable userfaultfd() system call"
1371 Enable the userfaultfd() system call that allows to intercept and
1372 handle page faults in userland.
1376 bool "Enable PCI quirk workarounds" if EXPERT
1379 This enables workarounds for various PCI chipset
1380 bugs/quirks. Disable this only if your target machine is
1381 unaffected by PCI quirks.
1384 bool "Enable membarrier() system call" if EXPERT
1387 Enable the membarrier() system call that allows issuing memory
1388 barriers across all running threads, which can be used to distribute
1389 the cost of user-space memory barriers asymmetrically by transforming
1390 pairs of memory barriers into pairs consisting of membarrier() and a
1396 bool "Embedded system"
1397 option allnoconfig_y
1400 This option should be enabled if compiling the kernel for
1401 an embedded system so certain expert options are available
1404 config HAVE_PERF_EVENTS
1407 See tools/perf/design.txt for details.
1409 config PERF_USE_VMALLOC
1412 See tools/perf/design.txt for details
1415 bool "PC/104 support"
1417 Expose PC/104 form factor device drivers and options available for
1418 selection and configuration. Enable this option if your target
1419 machine has a PC/104 bus.
1421 menu "Kernel Performance Events And Counters"
1424 bool "Kernel performance events and counters"
1425 default y if PROFILING
1426 depends on HAVE_PERF_EVENTS
1431 Enable kernel support for various performance events provided
1432 by software and hardware.
1434 Software events are supported either built-in or via the
1435 use of generic tracepoints.
1437 Most modern CPUs support performance events via performance
1438 counter registers. These registers count the number of certain
1439 types of hw events: such as instructions executed, cachemisses
1440 suffered, or branches mis-predicted - without slowing down the
1441 kernel or applications. These registers can also trigger interrupts
1442 when a threshold number of events have passed - and can thus be
1443 used to profile the code that runs on that CPU.
1445 The Linux Performance Event subsystem provides an abstraction of
1446 these software and hardware event capabilities, available via a
1447 system call and used by the "perf" utility in tools/perf/. It
1448 provides per task and per CPU counters, and it provides event
1449 capabilities on top of those.
1453 config DEBUG_PERF_USE_VMALLOC
1455 bool "Debug: use vmalloc to back perf mmap() buffers"
1456 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1457 select PERF_USE_VMALLOC
1459 Use vmalloc memory to back perf mmap() buffers.
1461 Mostly useful for debugging the vmalloc code on platforms
1462 that don't require it.
1468 config VM_EVENT_COUNTERS
1470 bool "Enable VM event counters for /proc/vmstat" if EXPERT
1472 VM event counters are needed for event counts to be shown.
1473 This option allows the disabling of the VM event counters
1474 on EXPERT systems. /proc/vmstat will only show page counts
1475 if VM event counters are disabled.
1479 bool "Enable SLUB debugging support" if EXPERT
1480 depends on SLUB && SYSFS
1482 SLUB has extensive debug support features. Disabling these can
1483 result in significant savings in code size. This also disables
1484 SLUB sysfs support. /sys/slab will not exist and there will be
1485 no support for cache validation etc.
1487 config SLUB_MEMCG_SYSFS_ON
1489 bool "Enable memcg SLUB sysfs support by default" if EXPERT
1490 depends on SLUB && SYSFS && MEMCG
1492 SLUB creates a directory under /sys/kernel/slab for each
1493 allocation cache to host info and debug files. If memory
1494 cgroup is enabled, each cache can have per memory cgroup
1495 caches. SLUB can create the same sysfs directories for these
1496 caches under /sys/kernel/slab/CACHE/cgroup but it can lead
1497 to a very high number of debug files being created. This is
1498 controlled by slub_memcg_sysfs boot parameter and this
1499 config option determines the parameter's default value.
1502 bool "Disable heap randomization"
1505 Randomizing heap placement makes heap exploits harder, but it
1506 also breaks ancient binaries (including anything libc5 based).
1507 This option changes the bootup default to heap randomization
1508 disabled, and can be overridden at runtime by setting
1509 /proc/sys/kernel/randomize_va_space to 2.
1511 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1514 prompt "Choose SLAB allocator"
1517 This option allows to select a slab allocator.
1521 select HAVE_HARDENED_USERCOPY_ALLOCATOR
1523 The regular slab allocator that is established and known to work
1524 well in all environments. It organizes cache hot objects in
1525 per cpu and per node queues.
1528 bool "SLUB (Unqueued Allocator)"
1529 select HAVE_HARDENED_USERCOPY_ALLOCATOR
1531 SLUB is a slab allocator that minimizes cache line usage
1532 instead of managing queues of cached objects (SLAB approach).
1533 Per cpu caching is realized using slabs of objects instead
1534 of queues of objects. SLUB can use memory efficiently
1535 and has enhanced diagnostics. SLUB is the default choice for
1540 bool "SLOB (Simple Allocator)"
1542 SLOB replaces the stock allocator with a drastically simpler
1543 allocator. SLOB is generally more space efficient but
1544 does not perform as well on large systems.
1548 config SLAB_FREELIST_RANDOM
1550 depends on SLAB || SLUB
1551 bool "SLAB freelist randomization"
1553 Randomizes the freelist order used on creating new pages. This
1554 security feature reduces the predictability of the kernel slab
1555 allocator against heap overflows.
1557 config SLUB_CPU_PARTIAL
1559 depends on SLUB && SMP
1560 bool "SLUB per cpu partial cache"
1562 Per cpu partial caches accellerate objects allocation and freeing
1563 that is local to a processor at the price of more indeterminism
1564 in the latency of the free. On overflow these caches will be cleared
1565 which requires the taking of locks that may cause latency spikes.
1566 Typically one would choose no for a realtime system.
1568 config MMAP_ALLOW_UNINITIALIZED
1569 bool "Allow mmapped anonymous memory to be uninitialized"
1570 depends on EXPERT && !MMU
1573 Normally, and according to the Linux spec, anonymous memory obtained
1574 from mmap() has it's contents cleared before it is passed to
1575 userspace. Enabling this config option allows you to request that
1576 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1577 providing a huge performance boost. If this option is not enabled,
1578 then the flag will be ignored.
1580 This is taken advantage of by uClibc's malloc(), and also by
1581 ELF-FDPIC binfmt's brk and stack allocator.
1583 Because of the obvious security issues, this option should only be
1584 enabled on embedded devices where you control what is run in
1585 userspace. Since that isn't generally a problem on no-MMU systems,
1586 it is normally safe to say Y here.
1588 See Documentation/nommu-mmap.txt for more information.
1590 config SYSTEM_DATA_VERIFICATION
1592 select SYSTEM_TRUSTED_KEYRING
1596 select ASYMMETRIC_KEY_TYPE
1597 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1600 select X509_CERTIFICATE_PARSER
1601 select PKCS7_MESSAGE_PARSER
1603 Provide PKCS#7 message verification using the contents of the system
1604 trusted keyring to provide public keys. This then can be used for
1605 module verification, kexec image verification and firmware blob
1609 bool "Profiling support"
1611 Say Y here to enable the extended profiling support mechanisms used
1612 by profilers such as OProfile.
1615 # Place an empty function call at each tracepoint site. Can be
1616 # dynamically changed for a probe function.
1621 source "arch/Kconfig"
1623 endmenu # General setup
1625 config HAVE_GENERIC_DMA_COHERENT
1632 depends on SLAB || SLUB_DEBUG
1640 default 0 if BASE_FULL
1641 default 1 if !BASE_FULL
1644 bool "Enable loadable module support"
1647 Kernel modules are small pieces of compiled code which can
1648 be inserted in the running kernel, rather than being
1649 permanently built into the kernel. You use the "modprobe"
1650 tool to add (and sometimes remove) them. If you say Y here,
1651 many parts of the kernel can be built as modules (by
1652 answering M instead of Y where indicated): this is most
1653 useful for infrequently used options which are not required
1654 for booting. For more information, see the man pages for
1655 modprobe, lsmod, modinfo, insmod and rmmod.
1657 If you say Y here, you will need to run "make
1658 modules_install" to put the modules under /lib/modules/
1659 where modprobe can find them (you may need to be root to do
1666 config MODULE_FORCE_LOAD
1667 bool "Forced module loading"
1670 Allow loading of modules without version information (ie. modprobe
1671 --force). Forced module loading sets the 'F' (forced) taint flag and
1672 is usually a really bad idea.
1674 config MODULE_UNLOAD
1675 bool "Module unloading"
1677 Without this option you will not be able to unload any
1678 modules (note that some modules may not be unloadable
1679 anyway), which makes your kernel smaller, faster
1680 and simpler. If unsure, say Y.
1682 config MODULE_FORCE_UNLOAD
1683 bool "Forced module unloading"
1684 depends on MODULE_UNLOAD
1686 This option allows you to force a module to unload, even if the
1687 kernel believes it is unsafe: the kernel will remove the module
1688 without waiting for anyone to stop using it (using the -f option to
1689 rmmod). This is mainly for kernel developers and desperate users.
1693 bool "Module versioning support"
1695 Usually, you have to use modules compiled with your kernel.
1696 Saying Y here makes it sometimes possible to use modules
1697 compiled for different kernels, by adding enough information
1698 to the modules to (hopefully) spot any changes which would
1699 make them incompatible with the kernel you are running. If
1702 config MODULE_REL_CRCS
1704 depends on MODVERSIONS
1706 config MODULE_SRCVERSION_ALL
1707 bool "Source checksum for all modules"
1709 Modules which contain a MODULE_VERSION get an extra "srcversion"
1710 field inserted into their modinfo section, which contains a
1711 sum of the source files which made it. This helps maintainers
1712 see exactly which source was used to build a module (since
1713 others sometimes change the module source without updating
1714 the version). With this option, such a "srcversion" field
1715 will be created for all modules. If unsure, say N.
1718 bool "Module signature verification"
1720 select SYSTEM_DATA_VERIFICATION
1722 Check modules for valid signatures upon load: the signature
1723 is simply appended to the module. For more information see
1724 Documentation/module-signing.txt.
1726 Note that this option adds the OpenSSL development packages as a
1727 kernel build dependency so that the signing tool can use its crypto
1730 !!!WARNING!!! If you enable this option, you MUST make sure that the
1731 module DOES NOT get stripped after being signed. This includes the
1732 debuginfo strip done by some packagers (such as rpmbuild) and
1733 inclusion into an initramfs that wants the module size reduced.
1735 config MODULE_SIG_FORCE
1736 bool "Require modules to be validly signed"
1737 depends on MODULE_SIG
1739 Reject unsigned modules or signed modules for which we don't have a
1740 key. Without this, such modules will simply taint the kernel.
1742 config MODULE_SIG_ALL
1743 bool "Automatically sign all modules"
1745 depends on MODULE_SIG
1747 Sign all modules during make modules_install. Without this option,
1748 modules must be signed manually, using the scripts/sign-file tool.
1750 comment "Do not forget to sign required modules with scripts/sign-file"
1751 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
1754 prompt "Which hash algorithm should modules be signed with?"
1755 depends on MODULE_SIG
1757 This determines which sort of hashing algorithm will be used during
1758 signature generation. This algorithm _must_ be built into the kernel
1759 directly so that signature verification can take place. It is not
1760 possible to load a signed module containing the algorithm to check
1761 the signature on that module.
1763 config MODULE_SIG_SHA1
1764 bool "Sign modules with SHA-1"
1767 config MODULE_SIG_SHA224
1768 bool "Sign modules with SHA-224"
1769 select CRYPTO_SHA256
1771 config MODULE_SIG_SHA256
1772 bool "Sign modules with SHA-256"
1773 select CRYPTO_SHA256
1775 config MODULE_SIG_SHA384
1776 bool "Sign modules with SHA-384"
1777 select CRYPTO_SHA512
1779 config MODULE_SIG_SHA512
1780 bool "Sign modules with SHA-512"
1781 select CRYPTO_SHA512
1785 config MODULE_SIG_HASH
1787 depends on MODULE_SIG
1788 default "sha1" if MODULE_SIG_SHA1
1789 default "sha224" if MODULE_SIG_SHA224
1790 default "sha256" if MODULE_SIG_SHA256
1791 default "sha384" if MODULE_SIG_SHA384
1792 default "sha512" if MODULE_SIG_SHA512
1794 config MODULE_COMPRESS
1795 bool "Compress modules on installation"
1799 Compresses kernel modules when 'make modules_install' is run; gzip or
1800 xz depending on "Compression algorithm" below.
1802 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
1804 Out-of-tree kernel modules installed using Kbuild will also be
1805 compressed upon installation.
1807 Note: for modules inside an initrd or initramfs, it's more efficient
1808 to compress the whole initrd or initramfs instead.
1810 Note: This is fully compatible with signed modules.
1815 prompt "Compression algorithm"
1816 depends on MODULE_COMPRESS
1817 default MODULE_COMPRESS_GZIP
1819 This determines which sort of compression will be used during
1820 'make modules_install'.
1822 GZIP (default) and XZ are supported.
1824 config MODULE_COMPRESS_GZIP
1827 config MODULE_COMPRESS_XZ
1832 config TRIM_UNUSED_KSYMS
1833 bool "Trim unused exported kernel symbols"
1834 depends on MODULES && !UNUSED_SYMBOLS
1836 The kernel and some modules make many symbols available for
1837 other modules to use via EXPORT_SYMBOL() and variants. Depending
1838 on the set of modules being selected in your kernel configuration,
1839 many of those exported symbols might never be used.
1841 This option allows for unused exported symbols to be dropped from
1842 the build. In turn, this provides the compiler more opportunities
1843 (especially when using LTO) for optimizing the code and reducing
1844 binary size. This might have some security advantages as well.
1846 If unsure, or if you need to build out-of-tree modules, say N.
1850 config MODULES_TREE_LOOKUP
1852 depends on PERF_EVENTS || TRACING
1854 config INIT_ALL_POSSIBLE
1857 Back when each arch used to define their own cpu_online_mask and
1858 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
1859 with all 1s, and others with all 0s. When they were centralised,
1860 it was better to provide this option than to break all the archs
1861 and have several arch maintainers pursuing me down dark alleys.
1863 source "block/Kconfig"
1865 config PREEMPT_NOTIFIERS
1875 Build a simple ASN.1 grammar compiler that produces a bytecode output
1876 that can be interpreted by the ASN.1 stream decoder and used to
1877 inform it as to what tags are to be expected in a stream and what
1878 functions to call on what tags.
1880 source "kernel/Kconfig.locks"
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