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"
70 Some drivers can be compiled on a different platform than they are
71 intended to be run on. Despite they cannot be loaded there (or even
72 when they load they cannot be used due to missing HW support),
73 developers still, opposing to distributors, might want to build such
74 drivers to compile-test them.
76 If you are a developer and want to build everything available, say Y
77 here. If you are a user/distributor, say N here to exclude useless
78 drivers to be distributed.
81 string "Local version - append to kernel release"
83 Append an extra string to the end of your kernel version.
84 This will show up when you type uname, for example.
85 The string you set here will be appended after the contents of
86 any files with a filename matching localversion* in your
87 object and source tree, in that order. Your total string can
88 be a maximum of 64 characters.
90 config LOCALVERSION_AUTO
91 bool "Automatically append version information to the version string"
93 depends on !COMPILE_TEST
95 This will try to automatically determine if the current tree is a
96 release tree by looking for git tags that belong to the current
99 A string of the format -gxxxxxxxx will be added to the localversion
100 if a git-based tree is found. The string generated by this will be
101 appended after any matching localversion* files, and after the value
102 set in CONFIG_LOCALVERSION.
104 (The actual string used here is the first eight characters produced
105 by running the command:
107 $ git rev-parse --verify HEAD
109 which is done within the script "scripts/setlocalversion".)
111 config HAVE_KERNEL_GZIP
114 config HAVE_KERNEL_BZIP2
117 config HAVE_KERNEL_LZMA
120 config HAVE_KERNEL_XZ
123 config HAVE_KERNEL_LZO
126 config HAVE_KERNEL_LZ4
130 prompt "Kernel compression mode"
132 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4
134 The linux kernel is a kind of self-extracting executable.
135 Several compression algorithms are available, which differ
136 in efficiency, compression and decompression speed.
137 Compression speed is only relevant when building a kernel.
138 Decompression speed is relevant at each boot.
140 If you have any problems with bzip2 or lzma compressed
141 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
142 version of this functionality (bzip2 only), for 2.4, was
143 supplied by Christian Ludwig)
145 High compression options are mostly useful for users, who
146 are low on disk space (embedded systems), but for whom ram
149 If in doubt, select 'gzip'
153 depends on HAVE_KERNEL_GZIP
155 The old and tried gzip compression. It provides a good balance
156 between compression ratio and decompression speed.
160 depends on HAVE_KERNEL_BZIP2
162 Its compression ratio and speed is intermediate.
163 Decompression speed is slowest among the choices. The kernel
164 size is about 10% smaller with bzip2, in comparison to gzip.
165 Bzip2 uses a large amount of memory. For modern kernels you
166 will need at least 8MB RAM or more for booting.
170 depends on HAVE_KERNEL_LZMA
172 This compression algorithm's ratio is best. Decompression speed
173 is between gzip and bzip2. Compression is slowest.
174 The kernel size is about 33% smaller with LZMA in comparison to gzip.
178 depends on HAVE_KERNEL_XZ
180 XZ uses the LZMA2 algorithm and instruction set specific
181 BCJ filters which can improve compression ratio of executable
182 code. The size of the kernel is about 30% smaller with XZ in
183 comparison to gzip. On architectures for which there is a BCJ
184 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
185 will create a few percent smaller kernel than plain LZMA.
187 The speed is about the same as with LZMA: The decompression
188 speed of XZ is better than that of bzip2 but worse than gzip
189 and LZO. Compression is slow.
193 depends on HAVE_KERNEL_LZO
195 Its compression ratio is the poorest among the choices. The kernel
196 size is about 10% bigger than gzip; however its speed
197 (both compression and decompression) is the fastest.
201 depends on HAVE_KERNEL_LZ4
203 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
204 A preliminary version of LZ4 de/compression tool is available at
205 <https://code.google.com/p/lz4/>.
207 Its compression ratio is worse than LZO. The size of the kernel
208 is about 8% bigger than LZO. But the decompression speed is
213 config DEFAULT_HOSTNAME
214 string "Default hostname"
217 This option determines the default system hostname before userspace
218 calls sethostname(2). The kernel traditionally uses "(none)" here,
219 but you may wish to use a different default here to make a minimal
220 system more usable with less configuration.
223 bool "Support for paging of anonymous memory (swap)"
224 depends on MMU && BLOCK
227 This option allows you to choose whether you want to have support
228 for so called swap devices or swap files in your kernel that are
229 used to provide more virtual memory than the actual RAM present
230 in your computer. If unsure say Y.
235 Inter Process Communication is a suite of library functions and
236 system calls which let processes (running programs) synchronize and
237 exchange information. It is generally considered to be a good thing,
238 and some programs won't run unless you say Y here. In particular, if
239 you want to run the DOS emulator dosemu under Linux (read the
240 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
241 you'll need to say Y here.
243 You can find documentation about IPC with "info ipc" and also in
244 section 6.4 of the Linux Programmer's Guide, available from
245 <http://www.tldp.org/guides.html>.
247 config SYSVIPC_SYSCTL
254 bool "POSIX Message Queues"
257 POSIX variant of message queues is a part of IPC. In POSIX message
258 queues every message has a priority which decides about succession
259 of receiving it by a process. If you want to compile and run
260 programs written e.g. for Solaris with use of its POSIX message
261 queues (functions mq_*) say Y here.
263 POSIX message queues are visible as a filesystem called 'mqueue'
264 and can be mounted somewhere if you want to do filesystem
265 operations on message queues.
269 config POSIX_MQUEUE_SYSCTL
271 depends on POSIX_MQUEUE
275 config CROSS_MEMORY_ATTACH
276 bool "Enable process_vm_readv/writev syscalls"
280 Enabling this option adds the system calls process_vm_readv and
281 process_vm_writev which allow a process with the correct privileges
282 to directly read from or write to another process' address space.
283 See the man page for more details.
286 bool "open by fhandle syscalls" if EXPERT
290 If you say Y here, a user level program will be able to map
291 file names to handle and then later use the handle for
292 different file system operations. This is useful in implementing
293 userspace file servers, which now track files using handles instead
294 of names. The handle would remain the same even if file names
295 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
299 bool "uselib syscall"
300 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
302 This option enables the uselib syscall, a system call used in the
303 dynamic linker from libc5 and earlier. glibc does not use this
304 system call. If you intend to run programs built on libc5 or
305 earlier, you may need to enable this syscall. Current systems
306 running glibc can safely disable this.
309 bool "Auditing support"
312 Enable auditing infrastructure that can be used with another
313 kernel subsystem, such as SELinux (which requires this for
314 logging of avc messages output). System call auditing is included
315 on architectures which support it.
317 config HAVE_ARCH_AUDITSYSCALL
322 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
326 depends on AUDITSYSCALL
331 depends on AUDITSYSCALL
334 source "kernel/irq/Kconfig"
335 source "kernel/time/Kconfig"
337 menu "CPU/Task time and stats accounting"
339 config VIRT_CPU_ACCOUNTING
343 prompt "Cputime accounting"
344 default TICK_CPU_ACCOUNTING if !PPC64
345 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
347 # Kind of a stub config for the pure tick based cputime accounting
348 config TICK_CPU_ACCOUNTING
349 bool "Simple tick based cputime accounting"
350 depends on !S390 && !NO_HZ_FULL
352 This is the basic tick based cputime accounting that maintains
353 statistics about user, system and idle time spent on per jiffies
358 config VIRT_CPU_ACCOUNTING_NATIVE
359 bool "Deterministic task and CPU time accounting"
360 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
361 select VIRT_CPU_ACCOUNTING
363 Select this option to enable more accurate task and CPU time
364 accounting. This is done by reading a CPU counter on each
365 kernel entry and exit and on transitions within the kernel
366 between system, softirq and hardirq state, so there is a
367 small performance impact. In the case of s390 or IBM POWER > 5,
368 this also enables accounting of stolen time on logically-partitioned
371 config VIRT_CPU_ACCOUNTING_GEN
372 bool "Full dynticks CPU time accounting"
373 depends on HAVE_CONTEXT_TRACKING
374 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
375 select VIRT_CPU_ACCOUNTING
376 select CONTEXT_TRACKING
378 Select this option to enable task and CPU time accounting on full
379 dynticks systems. This accounting is implemented by watching every
380 kernel-user boundaries using the context tracking subsystem.
381 The accounting is thus performed at the expense of some significant
384 For now this is only useful if you are working on the full
385 dynticks subsystem development.
391 config IRQ_TIME_ACCOUNTING
392 bool "Fine granularity task level IRQ time accounting"
393 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
395 Select this option to enable fine granularity task irq time
396 accounting. This is done by reading a timestamp on each
397 transitions between softirq and hardirq state, so there can be a
398 small performance impact.
400 If in doubt, say N here.
402 config BSD_PROCESS_ACCT
403 bool "BSD Process Accounting"
406 If you say Y here, a user level program will be able to instruct the
407 kernel (via a special system call) to write process accounting
408 information to a file: whenever a process exits, information about
409 that process will be appended to the file by the kernel. The
410 information includes things such as creation time, owning user,
411 command name, memory usage, controlling terminal etc. (the complete
412 list is in the struct acct in <file:include/linux/acct.h>). It is
413 up to the user level program to do useful things with this
414 information. This is generally a good idea, so say Y.
416 config BSD_PROCESS_ACCT_V3
417 bool "BSD Process Accounting version 3 file format"
418 depends on BSD_PROCESS_ACCT
421 If you say Y here, the process accounting information is written
422 in a new file format that also logs the process IDs of each
423 process and it's parent. Note that this file format is incompatible
424 with previous v0/v1/v2 file formats, so you will need updated tools
425 for processing it. A preliminary version of these tools is available
426 at <http://www.gnu.org/software/acct/>.
429 bool "Export task/process statistics through netlink"
434 Export selected statistics for tasks/processes through the
435 generic netlink interface. Unlike BSD process accounting, the
436 statistics are available during the lifetime of tasks/processes as
437 responses to commands. Like BSD accounting, they are sent to user
442 config TASK_DELAY_ACCT
443 bool "Enable per-task delay accounting"
447 Collect information on time spent by a task waiting for system
448 resources like cpu, synchronous block I/O completion and swapping
449 in pages. Such statistics can help in setting a task's priorities
450 relative to other tasks for cpu, io, rss limits etc.
455 bool "Enable extended accounting over taskstats"
458 Collect extended task accounting data and send the data
459 to userland for processing over the taskstats interface.
463 config TASK_IO_ACCOUNTING
464 bool "Enable per-task storage I/O accounting"
465 depends on TASK_XACCT
467 Collect information on the number of bytes of storage I/O which this
472 endmenu # "CPU/Task time and stats accounting"
474 source "kernel/rcu/Kconfig"
481 tristate "Kernel .config support"
484 This option enables the complete Linux kernel ".config" file
485 contents to be saved in the kernel. It provides documentation
486 of which kernel options are used in a running kernel or in an
487 on-disk kernel. This information can be extracted from the kernel
488 image file with the script scripts/extract-ikconfig and used as
489 input to rebuild the current kernel or to build another kernel.
490 It can also be extracted from a running kernel by reading
491 /proc/config.gz if enabled (below).
494 bool "Enable access to .config through /proc/config.gz"
495 depends on IKCONFIG && PROC_FS
497 This option enables access to the kernel configuration file
498 through /proc/config.gz.
501 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
502 range 12 25 if !H8300
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 "Debug controller"
864 depends on DEBUG_KERNEL
866 This option enables a simple controller that exports
867 debugging information about the cgroups framework. This
868 controller is for control cgroup debugging only. Its
869 interfaces are not stable.
873 config SOCK_CGROUP_DATA
879 config CHECKPOINT_RESTORE
880 bool "Checkpoint/restore support" if EXPERT
884 Enables additional kernel features in a sake of checkpoint/restore.
885 In particular it adds auxiliary prctl codes to setup process text,
886 data and heap segment sizes, and a few additional /proc filesystem
889 If unsure, say N here.
891 menuconfig NAMESPACES
892 bool "Namespaces support" if EXPERT
896 Provides the way to make tasks work with different objects using
897 the same id. For example same IPC id may refer to different objects
898 or same user id or pid may refer to different tasks when used in
899 different namespaces.
907 In this namespace tasks see different info provided with the
912 depends on (SYSVIPC || POSIX_MQUEUE)
915 In this namespace tasks work with IPC ids which correspond to
916 different IPC objects in different namespaces.
919 bool "User namespace"
922 This allows containers, i.e. vservers, to use user namespaces
923 to provide different user info for different servers.
925 When user namespaces are enabled in the kernel it is
926 recommended that the MEMCG option also be enabled and that
927 user-space use the memory control groups to limit the amount
928 of memory a memory unprivileged users can use.
933 bool "PID Namespaces"
936 Support process id namespaces. This allows having multiple
937 processes with the same pid as long as they are in different
938 pid namespaces. This is a building block of containers.
941 bool "Network namespace"
945 Allow user space to create what appear to be multiple instances
946 of the network stack.
950 config SCHED_AUTOGROUP
951 bool "Automatic process group scheduling"
954 select FAIR_GROUP_SCHED
956 This option optimizes the scheduler for common desktop workloads by
957 automatically creating and populating task groups. This separation
958 of workloads isolates aggressive CPU burners (like build jobs) from
959 desktop applications. Task group autogeneration is currently based
962 config SYSFS_DEPRECATED
963 bool "Enable deprecated sysfs features to support old userspace tools"
967 This option adds code that switches the layout of the "block" class
968 devices, to not show up in /sys/class/block/, but only in
971 This switch is only active when the sysfs.deprecated=1 boot option is
972 passed or the SYSFS_DEPRECATED_V2 option is set.
974 This option allows new kernels to run on old distributions and tools,
975 which might get confused by /sys/class/block/. Since 2007/2008 all
976 major distributions and tools handle this just fine.
978 Recent distributions and userspace tools after 2009/2010 depend on
979 the existence of /sys/class/block/, and will not work with this
982 Only if you are using a new kernel on an old distribution, you might
985 config SYSFS_DEPRECATED_V2
986 bool "Enable deprecated sysfs features by default"
989 depends on SYSFS_DEPRECATED
991 Enable deprecated sysfs by default.
993 See the CONFIG_SYSFS_DEPRECATED option for more details about this
996 Only if you are using a new kernel on an old distribution, you might
997 need to say Y here. Even then, odds are you would not need it
998 enabled, you can always pass the boot option if absolutely necessary.
1001 bool "Kernel->user space relay support (formerly relayfs)"
1004 This option enables support for relay interface support in
1005 certain file systems (such as debugfs).
1006 It is designed to provide an efficient mechanism for tools and
1007 facilities to relay large amounts of data from kernel space to
1012 config BLK_DEV_INITRD
1013 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1014 depends on BROKEN || !FRV
1016 The initial RAM filesystem is a ramfs which is loaded by the
1017 boot loader (loadlin or lilo) and that is mounted as root
1018 before the normal boot procedure. It is typically used to
1019 load modules needed to mount the "real" root file system,
1020 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1022 If RAM disk support (BLK_DEV_RAM) is also included, this
1023 also enables initial RAM disk (initrd) support and adds
1024 15 Kbytes (more on some other architectures) to the kernel size.
1030 source "usr/Kconfig"
1035 prompt "Compiler optimization level"
1036 default CC_OPTIMIZE_FOR_PERFORMANCE
1038 config CC_OPTIMIZE_FOR_PERFORMANCE
1039 bool "Optimize for performance"
1041 This is the default optimization level for the kernel, building
1042 with the "-O2" compiler flag for best performance and most
1043 helpful compile-time warnings.
1045 config CC_OPTIMIZE_FOR_SIZE
1046 bool "Optimize for size"
1048 Enabling this option will pass "-Os" instead of "-O2" to
1049 your compiler resulting in a smaller kernel.
1064 config SYSCTL_EXCEPTION_TRACE
1067 Enable support for /proc/sys/debug/exception-trace.
1069 config SYSCTL_ARCH_UNALIGN_NO_WARN
1072 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1073 Allows arch to define/use @no_unaligned_warning to possibly warn
1074 about unaligned access emulation going on under the hood.
1076 config SYSCTL_ARCH_UNALIGN_ALLOW
1079 Enable support for /proc/sys/kernel/unaligned-trap
1080 Allows arches to define/use @unaligned_enabled to runtime toggle
1081 the unaligned access emulation.
1082 see arch/parisc/kernel/unaligned.c for reference
1084 config HAVE_PCSPKR_PLATFORM
1087 # interpreter that classic socket filters depend on
1092 bool "Configure standard kernel features (expert users)"
1093 # Unhide debug options, to make the on-by-default options visible
1096 This option allows certain base kernel options and settings
1097 to be disabled or tweaked. This is for specialized
1098 environments which can tolerate a "non-standard" kernel.
1099 Only use this if you really know what you are doing.
1102 bool "Enable 16-bit UID system calls" if EXPERT
1103 depends on HAVE_UID16 && MULTIUSER
1106 This enables the legacy 16-bit UID syscall wrappers.
1109 bool "Multiple users, groups and capabilities support" if EXPERT
1112 This option enables support for non-root users, groups and
1115 If you say N here, all processes will run with UID 0, GID 0, and all
1116 possible capabilities. Saying N here also compiles out support for
1117 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1120 If unsure, say Y here.
1122 config SGETMASK_SYSCALL
1123 bool "sgetmask/ssetmask syscalls support" if EXPERT
1124 def_bool PARISC || MN10300 || BLACKFIN || M68K || PPC || MIPS || X86 || SPARC || CRIS || MICROBLAZE || SUPERH
1126 sys_sgetmask and sys_ssetmask are obsolete system calls
1127 no longer supported in libc but still enabled by default in some
1130 If unsure, leave the default option here.
1132 config SYSFS_SYSCALL
1133 bool "Sysfs syscall support" if EXPERT
1136 sys_sysfs is an obsolete system call no longer supported in libc.
1137 Note that disabling this option is more secure but might break
1138 compatibility with some systems.
1140 If unsure say Y here.
1142 config SYSCTL_SYSCALL
1143 bool "Sysctl syscall support" if EXPERT
1144 depends on PROC_SYSCTL
1148 sys_sysctl uses binary paths that have been found challenging
1149 to properly maintain and use. The interface in /proc/sys
1150 using paths with ascii names is now the primary path to this
1153 Almost nothing using the binary sysctl interface so if you are
1154 trying to save some space it is probably safe to disable this,
1155 making your kernel marginally smaller.
1157 If unsure say N here.
1160 bool "Posix Clocks & timers" if EXPERT
1163 This includes native support for POSIX timers to the kernel.
1164 Some embedded systems have no use for them and therefore they
1165 can be configured out to reduce the size of the kernel image.
1167 When this option is disabled, the following syscalls won't be
1168 available: timer_create, timer_gettime: timer_getoverrun,
1169 timer_settime, timer_delete, clock_adjtime, getitimer,
1170 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1171 clock_getres and clock_nanosleep syscalls will be limited to
1172 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1177 bool "Load all symbols for debugging/ksymoops" if EXPERT
1180 Say Y here to let the kernel print out symbolic crash information and
1181 symbolic stack backtraces. This increases the size of the kernel
1182 somewhat, as all symbols have to be loaded into the kernel image.
1185 bool "Include all symbols in kallsyms"
1186 depends on DEBUG_KERNEL && KALLSYMS
1188 Normally kallsyms only contains the symbols of functions for nicer
1189 OOPS messages and backtraces (i.e., symbols from the text and inittext
1190 sections). This is sufficient for most cases. And only in very rare
1191 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1192 names of variables from the data sections, etc).
1194 This option makes sure that all symbols are loaded into the kernel
1195 image (i.e., symbols from all sections) in cost of increased kernel
1196 size (depending on the kernel configuration, it may be 300KiB or
1197 something like this).
1199 Say N unless you really need all symbols.
1201 config KALLSYMS_ABSOLUTE_PERCPU
1204 default X86_64 && SMP
1206 config KALLSYMS_BASE_RELATIVE
1209 default !IA64 && !(TILE && 64BIT)
1211 Instead of emitting them as absolute values in the native word size,
1212 emit the symbol references in the kallsyms table as 32-bit entries,
1213 each containing a relative value in the range [base, base + U32_MAX]
1214 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1215 an absolute value in the range [0, S32_MAX] or a relative value in the
1216 range [base, base + S32_MAX], where base is the lowest relative symbol
1217 address encountered in the image.
1219 On 64-bit builds, this reduces the size of the address table by 50%,
1220 but more importantly, it results in entries whose values are build
1221 time constants, and no relocation pass is required at runtime to fix
1222 up the entries based on the runtime load address of the kernel.
1226 bool "Enable support for printk" if EXPERT
1229 This option enables normal printk support. Removing it
1230 eliminates most of the message strings from the kernel image
1231 and makes the kernel more or less silent. As this makes it
1232 very difficult to diagnose system problems, saying N here is
1233 strongly discouraged.
1241 bool "BUG() support" if EXPERT
1244 Disabling this option eliminates support for BUG and WARN, reducing
1245 the size of your kernel image and potentially quietly ignoring
1246 numerous fatal conditions. You should only consider disabling this
1247 option for embedded systems with no facilities for reporting errors.
1253 bool "Enable ELF core dumps" if EXPERT
1255 Enable support for generating core dumps. Disabling saves about 4k.
1258 config PCSPKR_PLATFORM
1259 bool "Enable PC-Speaker support" if EXPERT
1260 depends on HAVE_PCSPKR_PLATFORM
1264 This option allows to disable the internal PC-Speaker
1265 support, saving some memory.
1269 bool "Enable full-sized data structures for core" if EXPERT
1271 Disabling this option reduces the size of miscellaneous core
1272 kernel data structures. This saves memory on small machines,
1273 but may reduce performance.
1276 bool "Enable futex support" if EXPERT
1280 Disabling this option will cause the kernel to be built without
1281 support for "fast userspace mutexes". The resulting kernel may not
1282 run glibc-based applications correctly.
1286 depends on FUTEX && RT_MUTEXES
1289 config HAVE_FUTEX_CMPXCHG
1293 Architectures should select this if futex_atomic_cmpxchg_inatomic()
1294 is implemented and always working. This removes a couple of runtime
1298 bool "Enable eventpoll support" if EXPERT
1302 Disabling this option will cause the kernel to be built without
1303 support for epoll family of system calls.
1306 bool "Enable signalfd() system call" if EXPERT
1310 Enable the signalfd() system call that allows to receive signals
1311 on a file descriptor.
1316 bool "Enable timerfd() system call" if EXPERT
1320 Enable the timerfd() system call that allows to receive timer
1321 events on a file descriptor.
1326 bool "Enable eventfd() system call" if EXPERT
1330 Enable the eventfd() system call that allows to receive both
1331 kernel notification (ie. KAIO) or userspace notifications.
1335 # syscall, maps, verifier
1337 bool "Enable bpf() system call"
1342 Enable the bpf() system call that allows to manipulate eBPF
1343 programs and maps via file descriptors.
1345 config BPF_JIT_ALWAYS_ON
1346 bool "Permanently enable BPF JIT and remove BPF interpreter"
1347 depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
1349 Enables BPF JIT and removes BPF interpreter to avoid
1350 speculative execution of BPF instructions by the interpreter
1353 bool "Use full shmem filesystem" if EXPERT
1357 The shmem is an internal filesystem used to manage shared memory.
1358 It is backed by swap and manages resource limits. It is also exported
1359 to userspace as tmpfs if TMPFS is enabled. Disabling this
1360 option replaces shmem and tmpfs with the much simpler ramfs code,
1361 which may be appropriate on small systems without swap.
1364 bool "Enable AIO support" if EXPERT
1367 This option enables POSIX asynchronous I/O which may by used
1368 by some high performance threaded applications. Disabling
1369 this option saves about 7k.
1371 config ADVISE_SYSCALLS
1372 bool "Enable madvise/fadvise syscalls" if EXPERT
1375 This option enables the madvise and fadvise syscalls, used by
1376 applications to advise the kernel about their future memory or file
1377 usage, improving performance. If building an embedded system where no
1378 applications use these syscalls, you can disable this option to save
1381 config BPF_UNPRIV_DEFAULT_OFF
1382 bool "Disable unprivileged BPF by default"
1383 depends on BPF_SYSCALL
1385 Disables unprivileged BPF by default by setting the corresponding
1386 /proc/sys/kernel/unprivileged_bpf_disabled knob to 2. An admin can
1387 still reenable it by setting it to 0 later on, or permanently
1388 disable it by setting it to 1 (from which no other transition to
1389 0 is possible anymore).
1392 bool "Enable userfaultfd() system call"
1396 Enable the userfaultfd() system call that allows to intercept and
1397 handle page faults in userland.
1401 bool "Enable PCI quirk workarounds" if EXPERT
1404 This enables workarounds for various PCI chipset
1405 bugs/quirks. Disable this only if your target machine is
1406 unaffected by PCI quirks.
1409 bool "Enable membarrier() system call" if EXPERT
1412 Enable the membarrier() system call that allows issuing memory
1413 barriers across all running threads, which can be used to distribute
1414 the cost of user-space memory barriers asymmetrically by transforming
1415 pairs of memory barriers into pairs consisting of membarrier() and a
1421 bool "Embedded system"
1422 option allnoconfig_y
1425 This option should be enabled if compiling the kernel for
1426 an embedded system so certain expert options are available
1429 config HAVE_PERF_EVENTS
1432 See tools/perf/design.txt for details.
1434 config PERF_USE_VMALLOC
1437 See tools/perf/design.txt for details
1440 bool "PC/104 support"
1442 Expose PC/104 form factor device drivers and options available for
1443 selection and configuration. Enable this option if your target
1444 machine has a PC/104 bus.
1446 menu "Kernel Performance Events And Counters"
1449 bool "Kernel performance events and counters"
1450 default y if PROFILING
1451 depends on HAVE_PERF_EVENTS
1456 Enable kernel support for various performance events provided
1457 by software and hardware.
1459 Software events are supported either built-in or via the
1460 use of generic tracepoints.
1462 Most modern CPUs support performance events via performance
1463 counter registers. These registers count the number of certain
1464 types of hw events: such as instructions executed, cachemisses
1465 suffered, or branches mis-predicted - without slowing down the
1466 kernel or applications. These registers can also trigger interrupts
1467 when a threshold number of events have passed - and can thus be
1468 used to profile the code that runs on that CPU.
1470 The Linux Performance Event subsystem provides an abstraction of
1471 these software and hardware event capabilities, available via a
1472 system call and used by the "perf" utility in tools/perf/. It
1473 provides per task and per CPU counters, and it provides event
1474 capabilities on top of those.
1478 config DEBUG_PERF_USE_VMALLOC
1480 bool "Debug: use vmalloc to back perf mmap() buffers"
1481 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1482 select PERF_USE_VMALLOC
1484 Use vmalloc memory to back perf mmap() buffers.
1486 Mostly useful for debugging the vmalloc code on platforms
1487 that don't require it.
1493 config VM_EVENT_COUNTERS
1495 bool "Enable VM event counters for /proc/vmstat" if EXPERT
1497 VM event counters are needed for event counts to be shown.
1498 This option allows the disabling of the VM event counters
1499 on EXPERT systems. /proc/vmstat will only show page counts
1500 if VM event counters are disabled.
1504 bool "Enable SLUB debugging support" if EXPERT
1505 depends on SLUB && SYSFS
1507 SLUB has extensive debug support features. Disabling these can
1508 result in significant savings in code size. This also disables
1509 SLUB sysfs support. /sys/slab will not exist and there will be
1510 no support for cache validation etc.
1512 config SLUB_MEMCG_SYSFS_ON
1514 bool "Enable memcg SLUB sysfs support by default" if EXPERT
1515 depends on SLUB && SYSFS && MEMCG
1517 SLUB creates a directory under /sys/kernel/slab for each
1518 allocation cache to host info and debug files. If memory
1519 cgroup is enabled, each cache can have per memory cgroup
1520 caches. SLUB can create the same sysfs directories for these
1521 caches under /sys/kernel/slab/CACHE/cgroup but it can lead
1522 to a very high number of debug files being created. This is
1523 controlled by slub_memcg_sysfs boot parameter and this
1524 config option determines the parameter's default value.
1527 bool "Disable heap randomization"
1530 Randomizing heap placement makes heap exploits harder, but it
1531 also breaks ancient binaries (including anything libc5 based).
1532 This option changes the bootup default to heap randomization
1533 disabled, and can be overridden at runtime by setting
1534 /proc/sys/kernel/randomize_va_space to 2.
1536 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1539 prompt "Choose SLAB allocator"
1542 This option allows to select a slab allocator.
1546 select HAVE_HARDENED_USERCOPY_ALLOCATOR
1548 The regular slab allocator that is established and known to work
1549 well in all environments. It organizes cache hot objects in
1550 per cpu and per node queues.
1553 bool "SLUB (Unqueued Allocator)"
1554 select HAVE_HARDENED_USERCOPY_ALLOCATOR
1556 SLUB is a slab allocator that minimizes cache line usage
1557 instead of managing queues of cached objects (SLAB approach).
1558 Per cpu caching is realized using slabs of objects instead
1559 of queues of objects. SLUB can use memory efficiently
1560 and has enhanced diagnostics. SLUB is the default choice for
1565 bool "SLOB (Simple Allocator)"
1567 SLOB replaces the stock allocator with a drastically simpler
1568 allocator. SLOB is generally more space efficient but
1569 does not perform as well on large systems.
1573 config SLAB_MERGE_DEFAULT
1574 bool "Allow slab caches to be merged"
1577 For reduced kernel memory fragmentation, slab caches can be
1578 merged when they share the same size and other characteristics.
1579 This carries a risk of kernel heap overflows being able to
1580 overwrite objects from merged caches (and more easily control
1581 cache layout), which makes such heap attacks easier to exploit
1582 by attackers. By keeping caches unmerged, these kinds of exploits
1583 can usually only damage objects in the same cache. To disable
1584 merging at runtime, "slab_nomerge" can be passed on the kernel
1587 config SLAB_FREELIST_RANDOM
1589 depends on SLAB || SLUB
1590 bool "SLAB freelist randomization"
1592 Randomizes the freelist order used on creating new pages. This
1593 security feature reduces the predictability of the kernel slab
1594 allocator against heap overflows.
1596 config SLAB_FREELIST_HARDENED
1597 bool "Harden slab freelist metadata"
1600 Many kernel heap attacks try to target slab cache metadata and
1601 other infrastructure. This options makes minor performance
1602 sacrifies to harden the kernel slab allocator against common
1603 freelist exploit methods.
1605 config SLUB_CPU_PARTIAL
1607 depends on SLUB && SMP
1608 bool "SLUB per cpu partial cache"
1610 Per cpu partial caches accellerate objects allocation and freeing
1611 that is local to a processor at the price of more indeterminism
1612 in the latency of the free. On overflow these caches will be cleared
1613 which requires the taking of locks that may cause latency spikes.
1614 Typically one would choose no for a realtime system.
1616 config MMAP_ALLOW_UNINITIALIZED
1617 bool "Allow mmapped anonymous memory to be uninitialized"
1618 depends on EXPERT && !MMU
1621 Normally, and according to the Linux spec, anonymous memory obtained
1622 from mmap() has it's contents cleared before it is passed to
1623 userspace. Enabling this config option allows you to request that
1624 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1625 providing a huge performance boost. If this option is not enabled,
1626 then the flag will be ignored.
1628 This is taken advantage of by uClibc's malloc(), and also by
1629 ELF-FDPIC binfmt's brk and stack allocator.
1631 Because of the obvious security issues, this option should only be
1632 enabled on embedded devices where you control what is run in
1633 userspace. Since that isn't generally a problem on no-MMU systems,
1634 it is normally safe to say Y here.
1636 See Documentation/nommu-mmap.txt for more information.
1638 config SYSTEM_DATA_VERIFICATION
1640 select SYSTEM_TRUSTED_KEYRING
1644 select ASYMMETRIC_KEY_TYPE
1645 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1648 select X509_CERTIFICATE_PARSER
1649 select PKCS7_MESSAGE_PARSER
1651 Provide PKCS#7 message verification using the contents of the system
1652 trusted keyring to provide public keys. This then can be used for
1653 module verification, kexec image verification and firmware blob
1657 bool "Profiling support"
1659 Say Y here to enable the extended profiling support mechanisms used
1660 by profilers such as OProfile.
1663 # Place an empty function call at each tracepoint site. Can be
1664 # dynamically changed for a probe function.
1669 source "arch/Kconfig"
1671 endmenu # General setup
1673 config HAVE_GENERIC_DMA_COHERENT
1680 depends on SLAB || SLUB_DEBUG
1688 default 0 if BASE_FULL
1689 default 1 if !BASE_FULL
1692 bool "Enable loadable module support"
1695 Kernel modules are small pieces of compiled code which can
1696 be inserted in the running kernel, rather than being
1697 permanently built into the kernel. You use the "modprobe"
1698 tool to add (and sometimes remove) them. If you say Y here,
1699 many parts of the kernel can be built as modules (by
1700 answering M instead of Y where indicated): this is most
1701 useful for infrequently used options which are not required
1702 for booting. For more information, see the man pages for
1703 modprobe, lsmod, modinfo, insmod and rmmod.
1705 If you say Y here, you will need to run "make
1706 modules_install" to put the modules under /lib/modules/
1707 where modprobe can find them (you may need to be root to do
1714 config MODULE_FORCE_LOAD
1715 bool "Forced module loading"
1718 Allow loading of modules without version information (ie. modprobe
1719 --force). Forced module loading sets the 'F' (forced) taint flag and
1720 is usually a really bad idea.
1722 config MODULE_UNLOAD
1723 bool "Module unloading"
1725 Without this option you will not be able to unload any
1726 modules (note that some modules may not be unloadable
1727 anyway), which makes your kernel smaller, faster
1728 and simpler. If unsure, say Y.
1730 config MODULE_FORCE_UNLOAD
1731 bool "Forced module unloading"
1732 depends on MODULE_UNLOAD
1734 This option allows you to force a module to unload, even if the
1735 kernel believes it is unsafe: the kernel will remove the module
1736 without waiting for anyone to stop using it (using the -f option to
1737 rmmod). This is mainly for kernel developers and desperate users.
1741 bool "Module versioning support"
1743 Usually, you have to use modules compiled with your kernel.
1744 Saying Y here makes it sometimes possible to use modules
1745 compiled for different kernels, by adding enough information
1746 to the modules to (hopefully) spot any changes which would
1747 make them incompatible with the kernel you are running. If
1750 config MODULE_REL_CRCS
1752 depends on MODVERSIONS
1754 config MODULE_SRCVERSION_ALL
1755 bool "Source checksum for all modules"
1757 Modules which contain a MODULE_VERSION get an extra "srcversion"
1758 field inserted into their modinfo section, which contains a
1759 sum of the source files which made it. This helps maintainers
1760 see exactly which source was used to build a module (since
1761 others sometimes change the module source without updating
1762 the version). With this option, such a "srcversion" field
1763 will be created for all modules. If unsure, say N.
1766 bool "Module signature verification"
1768 select SYSTEM_DATA_VERIFICATION
1770 Check modules for valid signatures upon load: the signature
1771 is simply appended to the module. For more information see
1772 Documentation/module-signing.txt.
1774 Note that this option adds the OpenSSL development packages as a
1775 kernel build dependency so that the signing tool can use its crypto
1778 !!!WARNING!!! If you enable this option, you MUST make sure that the
1779 module DOES NOT get stripped after being signed. This includes the
1780 debuginfo strip done by some packagers (such as rpmbuild) and
1781 inclusion into an initramfs that wants the module size reduced.
1783 config MODULE_SIG_FORCE
1784 bool "Require modules to be validly signed"
1785 depends on MODULE_SIG
1787 Reject unsigned modules or signed modules for which we don't have a
1788 key. Without this, such modules will simply taint the kernel.
1790 config MODULE_SIG_ALL
1791 bool "Automatically sign all modules"
1793 depends on MODULE_SIG
1795 Sign all modules during make modules_install. Without this option,
1796 modules must be signed manually, using the scripts/sign-file tool.
1798 comment "Do not forget to sign required modules with scripts/sign-file"
1799 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
1802 prompt "Which hash algorithm should modules be signed with?"
1803 depends on MODULE_SIG
1805 This determines which sort of hashing algorithm will be used during
1806 signature generation. This algorithm _must_ be built into the kernel
1807 directly so that signature verification can take place. It is not
1808 possible to load a signed module containing the algorithm to check
1809 the signature on that module.
1811 config MODULE_SIG_SHA1
1812 bool "Sign modules with SHA-1"
1815 config MODULE_SIG_SHA224
1816 bool "Sign modules with SHA-224"
1817 select CRYPTO_SHA256
1819 config MODULE_SIG_SHA256
1820 bool "Sign modules with SHA-256"
1821 select CRYPTO_SHA256
1823 config MODULE_SIG_SHA384
1824 bool "Sign modules with SHA-384"
1825 select CRYPTO_SHA512
1827 config MODULE_SIG_SHA512
1828 bool "Sign modules with SHA-512"
1829 select CRYPTO_SHA512
1833 config MODULE_SIG_HASH
1835 depends on MODULE_SIG
1836 default "sha1" if MODULE_SIG_SHA1
1837 default "sha224" if MODULE_SIG_SHA224
1838 default "sha256" if MODULE_SIG_SHA256
1839 default "sha384" if MODULE_SIG_SHA384
1840 default "sha512" if MODULE_SIG_SHA512
1842 config MODULE_COMPRESS
1843 bool "Compress modules on installation"
1847 Compresses kernel modules when 'make modules_install' is run; gzip or
1848 xz depending on "Compression algorithm" below.
1850 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
1852 Out-of-tree kernel modules installed using Kbuild will also be
1853 compressed upon installation.
1855 Note: for modules inside an initrd or initramfs, it's more efficient
1856 to compress the whole initrd or initramfs instead.
1858 Note: This is fully compatible with signed modules.
1863 prompt "Compression algorithm"
1864 depends on MODULE_COMPRESS
1865 default MODULE_COMPRESS_GZIP
1867 This determines which sort of compression will be used during
1868 'make modules_install'.
1870 GZIP (default) and XZ are supported.
1872 config MODULE_COMPRESS_GZIP
1875 config MODULE_COMPRESS_XZ
1880 config TRIM_UNUSED_KSYMS
1881 bool "Trim unused exported kernel symbols"
1882 depends on MODULES && !UNUSED_SYMBOLS
1884 The kernel and some modules make many symbols available for
1885 other modules to use via EXPORT_SYMBOL() and variants. Depending
1886 on the set of modules being selected in your kernel configuration,
1887 many of those exported symbols might never be used.
1889 This option allows for unused exported symbols to be dropped from
1890 the build. In turn, this provides the compiler more opportunities
1891 (especially when using LTO) for optimizing the code and reducing
1892 binary size. This might have some security advantages as well.
1894 If unsure, or if you need to build out-of-tree modules, say N.
1898 config MODULES_TREE_LOOKUP
1900 depends on PERF_EVENTS || TRACING
1902 config INIT_ALL_POSSIBLE
1905 Back when each arch used to define their own cpu_online_mask and
1906 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
1907 with all 1s, and others with all 0s. When they were centralised,
1908 it was better to provide this option than to break all the archs
1909 and have several arch maintainers pursuing me down dark alleys.
1911 source "block/Kconfig"
1913 config PREEMPT_NOTIFIERS
1923 Build a simple ASN.1 grammar compiler that produces a bytecode output
1924 that can be interpreted by the ASN.1 stream decoder and used to
1925 inform it as to what tags are to be expected in a stream and what
1926 functions to call on what tags.
1928 source "kernel/Kconfig.locks"
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