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 "uselib syscall"
288 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
290 This option enables the uselib syscall, a system call used in the
291 dynamic linker from libc5 and earlier. glibc does not use this
292 system call. If you intend to run programs built on libc5 or
293 earlier, you may need to enable this syscall. Current systems
294 running glibc can safely disable this.
297 bool "Auditing support"
300 Enable auditing infrastructure that can be used with another
301 kernel subsystem, such as SELinux (which requires this for
302 logging of avc messages output). System call auditing is included
303 on architectures which support it.
305 config HAVE_ARCH_AUDITSYSCALL
310 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
314 depends on AUDITSYSCALL
319 depends on AUDITSYSCALL
322 source "kernel/irq/Kconfig"
323 source "kernel/time/Kconfig"
325 menu "CPU/Task time and stats accounting"
327 config VIRT_CPU_ACCOUNTING
331 prompt "Cputime accounting"
332 default TICK_CPU_ACCOUNTING if !PPC64
333 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
335 # Kind of a stub config for the pure tick based cputime accounting
336 config TICK_CPU_ACCOUNTING
337 bool "Simple tick based cputime accounting"
338 depends on !S390 && !NO_HZ_FULL
340 This is the basic tick based cputime accounting that maintains
341 statistics about user, system and idle time spent on per jiffies
346 config VIRT_CPU_ACCOUNTING_NATIVE
347 bool "Deterministic task and CPU time accounting"
348 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
349 select VIRT_CPU_ACCOUNTING
351 Select this option to enable more accurate task and CPU time
352 accounting. This is done by reading a CPU counter on each
353 kernel entry and exit and on transitions within the kernel
354 between system, softirq and hardirq state, so there is a
355 small performance impact. In the case of s390 or IBM POWER > 5,
356 this also enables accounting of stolen time on logically-partitioned
359 config VIRT_CPU_ACCOUNTING_GEN
360 bool "Full dynticks CPU time accounting"
361 depends on HAVE_CONTEXT_TRACKING
362 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
363 select VIRT_CPU_ACCOUNTING
364 select CONTEXT_TRACKING
366 Select this option to enable task and CPU time accounting on full
367 dynticks systems. This accounting is implemented by watching every
368 kernel-user boundaries using the context tracking subsystem.
369 The accounting is thus performed at the expense of some significant
372 For now this is only useful if you are working on the full
373 dynticks subsystem development.
379 config IRQ_TIME_ACCOUNTING
380 bool "Fine granularity task level IRQ time accounting"
381 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
383 Select this option to enable fine granularity task irq time
384 accounting. This is done by reading a timestamp on each
385 transitions between softirq and hardirq state, so there can be a
386 small performance impact.
388 If in doubt, say N here.
390 config BSD_PROCESS_ACCT
391 bool "BSD Process Accounting"
394 If you say Y here, a user level program will be able to instruct the
395 kernel (via a special system call) to write process accounting
396 information to a file: whenever a process exits, information about
397 that process will be appended to the file by the kernel. The
398 information includes things such as creation time, owning user,
399 command name, memory usage, controlling terminal etc. (the complete
400 list is in the struct acct in <file:include/linux/acct.h>). It is
401 up to the user level program to do useful things with this
402 information. This is generally a good idea, so say Y.
404 config BSD_PROCESS_ACCT_V3
405 bool "BSD Process Accounting version 3 file format"
406 depends on BSD_PROCESS_ACCT
409 If you say Y here, the process accounting information is written
410 in a new file format that also logs the process IDs of each
411 process and it's parent. Note that this file format is incompatible
412 with previous v0/v1/v2 file formats, so you will need updated tools
413 for processing it. A preliminary version of these tools is available
414 at <http://www.gnu.org/software/acct/>.
417 bool "Export task/process statistics through netlink"
422 Export selected statistics for tasks/processes through the
423 generic netlink interface. Unlike BSD process accounting, the
424 statistics are available during the lifetime of tasks/processes as
425 responses to commands. Like BSD accounting, they are sent to user
430 config TASK_DELAY_ACCT
431 bool "Enable per-task delay accounting"
435 Collect information on time spent by a task waiting for system
436 resources like cpu, synchronous block I/O completion and swapping
437 in pages. Such statistics can help in setting a task's priorities
438 relative to other tasks for cpu, io, rss limits etc.
443 bool "Enable extended accounting over taskstats"
446 Collect extended task accounting data and send the data
447 to userland for processing over the taskstats interface.
451 config TASK_IO_ACCOUNTING
452 bool "Enable per-task storage I/O accounting"
453 depends on TASK_XACCT
455 Collect information on the number of bytes of storage I/O which this
460 endmenu # "CPU/Task time and stats accounting"
464 depends on SMP || COMPILE_TEST
467 Make sure that CPUs running critical tasks are not disturbed by
468 any source of "noise" such as unbound workqueues, timers, kthreads...
469 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
470 the "isolcpus=" boot parameter.
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)"
506 Select the minimal kernel log buffer size as a power of 2.
507 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
508 parameter, see below. Any higher size also might be forced
509 by "log_buf_len" boot parameter.
519 config LOG_CPU_MAX_BUF_SHIFT
520 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
523 default 12 if !BASE_SMALL
524 default 0 if BASE_SMALL
527 This option allows to increase the default ring buffer size
528 according to the number of CPUs. The value defines the contribution
529 of each CPU as a power of 2. The used space is typically only few
530 lines however it might be much more when problems are reported,
533 The increased size means that a new buffer has to be allocated and
534 the original static one is unused. It makes sense only on systems
535 with more CPUs. Therefore this value is used only when the sum of
536 contributions is greater than the half of the default kernel ring
537 buffer as defined by LOG_BUF_SHIFT. The default values are set
538 so that more than 64 CPUs are needed to trigger the allocation.
540 Also this option is ignored when "log_buf_len" kernel parameter is
541 used as it forces an exact (power of two) size of the ring buffer.
543 The number of possible CPUs is used for this computation ignoring
544 hotplugging making the computation optimal for the worst case
545 scenario while allowing a simple algorithm to be used from bootup.
547 Examples shift values and their meaning:
548 17 => 128 KB for each CPU
549 16 => 64 KB for each CPU
550 15 => 32 KB for each CPU
551 14 => 16 KB for each CPU
552 13 => 8 KB for each CPU
553 12 => 4 KB for each CPU
555 config PRINTK_SAFE_LOG_BUF_SHIFT
556 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
561 Select the size of an alternate printk per-CPU buffer where messages
562 printed from usafe contexts are temporary stored. One example would
563 be NMI messages, another one - printk recursion. The messages are
564 copied to the main log buffer in a safe context to avoid a deadlock.
565 The value defines the size as a power of 2.
567 Those messages are rare and limited. The largest one is when
568 a backtrace is printed. It usually fits into 4KB. Select
569 8KB if you want to be on the safe side.
572 17 => 128 KB for each CPU
573 16 => 64 KB for each CPU
574 15 => 32 KB for each CPU
575 14 => 16 KB for each CPU
576 13 => 8 KB for each CPU
577 12 => 4 KB for each CPU
580 # Architectures with an unreliable sched_clock() should select this:
582 config HAVE_UNSTABLE_SCHED_CLOCK
585 config GENERIC_SCHED_CLOCK
589 # For architectures that want to enable the support for NUMA-affine scheduler
592 config ARCH_SUPPORTS_NUMA_BALANCING
596 # For architectures that prefer to flush all TLBs after a number of pages
597 # are unmapped instead of sending one IPI per page to flush. The architecture
598 # must provide guarantees on what happens if a clean TLB cache entry is
599 # written after the unmap. Details are in mm/rmap.c near the check for
600 # should_defer_flush. The architecture should also consider if the full flush
601 # and the refill costs are offset by the savings of sending fewer IPIs.
602 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
606 # For architectures that know their GCC __int128 support is sound
608 config ARCH_SUPPORTS_INT128
611 # For architectures that (ab)use NUMA to represent different memory regions
612 # all cpu-local but of different latencies, such as SuperH.
614 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
617 config NUMA_BALANCING
618 bool "Memory placement aware NUMA scheduler"
619 depends on ARCH_SUPPORTS_NUMA_BALANCING
620 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
621 depends on SMP && NUMA && MIGRATION
623 This option adds support for automatic NUMA aware memory/task placement.
624 The mechanism is quite primitive and is based on migrating memory when
625 it has references to the node the task is running on.
627 This system will be inactive on UMA systems.
629 config NUMA_BALANCING_DEFAULT_ENABLED
630 bool "Automatically enable NUMA aware memory/task placement"
632 depends on NUMA_BALANCING
634 If set, automatic NUMA balancing will be enabled if running on a NUMA
638 bool "Control Group support"
641 This option adds support for grouping sets of processes together, for
642 use with process control subsystems such as Cpusets, CFS, memory
643 controls or device isolation.
645 - Documentation/scheduler/sched-design-CFS.txt (CFS)
646 - Documentation/cgroup-v1/ (features for grouping, isolation
647 and resource control)
657 bool "Memory controller"
661 Provides control over the memory footprint of tasks in a cgroup.
664 bool "Swap controller"
665 depends on MEMCG && SWAP
667 Provides control over the swap space consumed by tasks in a cgroup.
669 config MEMCG_SWAP_ENABLED
670 bool "Swap controller enabled by default"
671 depends on MEMCG_SWAP
674 Memory Resource Controller Swap Extension comes with its price in
675 a bigger memory consumption. General purpose distribution kernels
676 which want to enable the feature but keep it disabled by default
677 and let the user enable it by swapaccount=1 boot command line
678 parameter should have this option unselected.
679 For those who want to have the feature enabled by default should
680 select this option (if, for some reason, they need to disable it
681 then swapaccount=0 does the trick).
688 Generic block IO controller cgroup interface. This is the common
689 cgroup interface which should be used by various IO controlling
692 Currently, CFQ IO scheduler uses it to recognize task groups and
693 control disk bandwidth allocation (proportional time slice allocation)
694 to such task groups. It is also used by bio throttling logic in
695 block layer to implement upper limit in IO rates on a device.
697 This option only enables generic Block IO controller infrastructure.
698 One needs to also enable actual IO controlling logic/policy. For
699 enabling proportional weight division of disk bandwidth in CFQ, set
700 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
701 CONFIG_BLK_DEV_THROTTLING=y.
703 See Documentation/cgroup-v1/blkio-controller.txt for more information.
705 config DEBUG_BLK_CGROUP
706 bool "IO controller debugging"
707 depends on BLK_CGROUP
710 Enable some debugging help. Currently it exports additional stat
711 files in a cgroup which can be useful for debugging.
713 config CGROUP_WRITEBACK
715 depends on MEMCG && BLK_CGROUP
718 menuconfig CGROUP_SCHED
719 bool "CPU controller"
722 This feature lets CPU scheduler recognize task groups and control CPU
723 bandwidth allocation to such task groups. It uses cgroups to group
727 config FAIR_GROUP_SCHED
728 bool "Group scheduling for SCHED_OTHER"
729 depends on CGROUP_SCHED
733 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
734 depends on FAIR_GROUP_SCHED
737 This option allows users to define CPU bandwidth rates (limits) for
738 tasks running within the fair group scheduler. Groups with no limit
739 set are considered to be unconstrained and will run with no
741 See tip/Documentation/scheduler/sched-bwc.txt for more information.
743 config RT_GROUP_SCHED
744 bool "Group scheduling for SCHED_RR/FIFO"
745 depends on CGROUP_SCHED
748 This feature lets you explicitly allocate real CPU bandwidth
749 to task groups. If enabled, it will also make it impossible to
750 schedule realtime tasks for non-root users until you allocate
751 realtime bandwidth for them.
752 See Documentation/scheduler/sched-rt-group.txt for more information.
757 bool "PIDs controller"
759 Provides enforcement of process number limits in the scope of a
760 cgroup. Any attempt to fork more processes than is allowed in the
761 cgroup will fail. PIDs are fundamentally a global resource because it
762 is fairly trivial to reach PID exhaustion before you reach even a
763 conservative kmemcg limit. As a result, it is possible to grind a
764 system to halt without being limited by other cgroup policies. The
765 PIDs controller is designed to stop this from happening.
767 It should be noted that organisational operations (such as attaching
768 to a cgroup hierarchy will *not* be blocked by the PIDs controller),
769 since the PIDs limit only affects a process's ability to fork, not to
773 bool "RDMA controller"
775 Provides enforcement of RDMA resources defined by IB stack.
776 It is fairly easy for consumers to exhaust RDMA resources, which
777 can result into resource unavailability to other consumers.
778 RDMA controller is designed to stop this from happening.
779 Attaching processes with active RDMA resources to the cgroup
780 hierarchy is allowed even if can cross the hierarchy's limit.
782 config CGROUP_FREEZER
783 bool "Freezer controller"
785 Provides a way to freeze and unfreeze all tasks in a
788 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
789 controller includes important in-kernel memory consumers per default.
791 If you're using cgroup2, say N.
793 config CGROUP_HUGETLB
794 bool "HugeTLB controller"
795 depends on HUGETLB_PAGE
799 Provides a cgroup controller for HugeTLB pages.
800 When you enable this, you can put a per cgroup limit on HugeTLB usage.
801 The limit is enforced during page fault. Since HugeTLB doesn't
802 support page reclaim, enforcing the limit at page fault time implies
803 that, the application will get SIGBUS signal if it tries to access
804 HugeTLB pages beyond its limit. This requires the application to know
805 beforehand how much HugeTLB pages it would require for its use. The
806 control group is tracked in the third page lru pointer. This means
807 that we cannot use the controller with huge page less than 3 pages.
810 bool "Cpuset controller"
813 This option will let you create and manage CPUSETs which
814 allow dynamically partitioning a system into sets of CPUs and
815 Memory Nodes and assigning tasks to run only within those sets.
816 This is primarily useful on large SMP or NUMA systems.
820 config PROC_PID_CPUSET
821 bool "Include legacy /proc/<pid>/cpuset file"
826 bool "Device controller"
828 Provides a cgroup controller implementing whitelists for
829 devices which a process in the cgroup can mknod or open.
831 config CGROUP_CPUACCT
832 bool "Simple CPU accounting controller"
834 Provides a simple controller for monitoring the
835 total CPU consumed by the tasks in a cgroup.
838 bool "Perf controller"
839 depends on PERF_EVENTS
841 This option extends the perf per-cpu mode to restrict monitoring
842 to threads which belong to the cgroup specified and run on the
848 bool "Support for eBPF programs attached to cgroups"
849 depends on BPF_SYSCALL
850 select SOCK_CGROUP_DATA
852 Allow attaching eBPF programs to a cgroup using the bpf(2)
853 syscall command BPF_PROG_ATTACH.
855 In which context these programs are accessed depends on the type
856 of attachment. For instance, programs that are attached using
857 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
861 bool "Debug controller"
863 depends on DEBUG_KERNEL
865 This option enables a simple controller that exports
866 debugging information about the cgroups framework. This
867 controller is for control cgroup debugging only. Its
868 interfaces are not stable.
872 config SOCK_CGROUP_DATA
878 menuconfig NAMESPACES
879 bool "Namespaces support" if EXPERT
883 Provides the way to make tasks work with different objects using
884 the same id. For example same IPC id may refer to different objects
885 or same user id or pid may refer to different tasks when used in
886 different namespaces.
894 In this namespace tasks see different info provided with the
899 depends on (SYSVIPC || POSIX_MQUEUE)
902 In this namespace tasks work with IPC ids which correspond to
903 different IPC objects in different namespaces.
906 bool "User namespace"
909 This allows containers, i.e. vservers, to use user namespaces
910 to provide different user info for different servers.
912 When user namespaces are enabled in the kernel it is
913 recommended that the MEMCG option also be enabled and that
914 user-space use the memory control groups to limit the amount
915 of memory a memory unprivileged users can use.
920 bool "PID Namespaces"
923 Support process id namespaces. This allows having multiple
924 processes with the same pid as long as they are in different
925 pid namespaces. This is a building block of containers.
928 bool "Network namespace"
932 Allow user space to create what appear to be multiple instances
933 of the network stack.
937 config SCHED_AUTOGROUP
938 bool "Automatic process group scheduling"
941 select FAIR_GROUP_SCHED
943 This option optimizes the scheduler for common desktop workloads by
944 automatically creating and populating task groups. This separation
945 of workloads isolates aggressive CPU burners (like build jobs) from
946 desktop applications. Task group autogeneration is currently based
949 config SYSFS_DEPRECATED
950 bool "Enable deprecated sysfs features to support old userspace tools"
954 This option adds code that switches the layout of the "block" class
955 devices, to not show up in /sys/class/block/, but only in
958 This switch is only active when the sysfs.deprecated=1 boot option is
959 passed or the SYSFS_DEPRECATED_V2 option is set.
961 This option allows new kernels to run on old distributions and tools,
962 which might get confused by /sys/class/block/. Since 2007/2008 all
963 major distributions and tools handle this just fine.
965 Recent distributions and userspace tools after 2009/2010 depend on
966 the existence of /sys/class/block/, and will not work with this
969 Only if you are using a new kernel on an old distribution, you might
972 config SYSFS_DEPRECATED_V2
973 bool "Enable deprecated sysfs features by default"
976 depends on SYSFS_DEPRECATED
978 Enable deprecated sysfs by default.
980 See the CONFIG_SYSFS_DEPRECATED option for more details about this
983 Only if you are using a new kernel on an old distribution, you might
984 need to say Y here. Even then, odds are you would not need it
985 enabled, you can always pass the boot option if absolutely necessary.
988 bool "Kernel->user space relay support (formerly relayfs)"
991 This option enables support for relay interface support in
992 certain file systems (such as debugfs).
993 It is designed to provide an efficient mechanism for tools and
994 facilities to relay large amounts of data from kernel space to
999 config BLK_DEV_INITRD
1000 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1002 The initial RAM filesystem is a ramfs which is loaded by the
1003 boot loader (loadlin or lilo) and that is mounted as root
1004 before the normal boot procedure. It is typically used to
1005 load modules needed to mount the "real" root file system,
1006 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1008 If RAM disk support (BLK_DEV_RAM) is also included, this
1009 also enables initial RAM disk (initrd) support and adds
1010 15 Kbytes (more on some other architectures) to the kernel size.
1016 source "usr/Kconfig"
1021 prompt "Compiler optimization level"
1022 default CC_OPTIMIZE_FOR_PERFORMANCE
1024 config CC_OPTIMIZE_FOR_PERFORMANCE
1025 bool "Optimize for performance"
1027 This is the default optimization level for the kernel, building
1028 with the "-O2" compiler flag for best performance and most
1029 helpful compile-time warnings.
1031 config CC_OPTIMIZE_FOR_SIZE
1032 bool "Optimize for size"
1034 Enabling this option will pass "-Os" instead of "-O2" to
1035 your compiler resulting in a smaller kernel.
1050 config SYSCTL_EXCEPTION_TRACE
1053 Enable support for /proc/sys/debug/exception-trace.
1055 config SYSCTL_ARCH_UNALIGN_NO_WARN
1058 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1059 Allows arch to define/use @no_unaligned_warning to possibly warn
1060 about unaligned access emulation going on under the hood.
1062 config SYSCTL_ARCH_UNALIGN_ALLOW
1065 Enable support for /proc/sys/kernel/unaligned-trap
1066 Allows arches to define/use @unaligned_enabled to runtime toggle
1067 the unaligned access emulation.
1068 see arch/parisc/kernel/unaligned.c for reference
1070 config HAVE_PCSPKR_PLATFORM
1073 # interpreter that classic socket filters depend on
1078 bool "Configure standard kernel features (expert users)"
1079 # Unhide debug options, to make the on-by-default options visible
1082 This option allows certain base kernel options and settings
1083 to be disabled or tweaked. This is for specialized
1084 environments which can tolerate a "non-standard" kernel.
1085 Only use this if you really know what you are doing.
1088 bool "Enable 16-bit UID system calls" if EXPERT
1089 depends on HAVE_UID16 && MULTIUSER
1092 This enables the legacy 16-bit UID syscall wrappers.
1095 bool "Multiple users, groups and capabilities support" if EXPERT
1098 This option enables support for non-root users, groups and
1101 If you say N here, all processes will run with UID 0, GID 0, and all
1102 possible capabilities. Saying N here also compiles out support for
1103 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1106 If unsure, say Y here.
1108 config SGETMASK_SYSCALL
1109 bool "sgetmask/ssetmask syscalls support" if EXPERT
1110 def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1112 sys_sgetmask and sys_ssetmask are obsolete system calls
1113 no longer supported in libc but still enabled by default in some
1116 If unsure, leave the default option here.
1118 config SYSFS_SYSCALL
1119 bool "Sysfs syscall support" if EXPERT
1122 sys_sysfs is an obsolete system call no longer supported in libc.
1123 Note that disabling this option is more secure but might break
1124 compatibility with some systems.
1126 If unsure say Y here.
1128 config SYSCTL_SYSCALL
1129 bool "Sysctl syscall support" if EXPERT
1130 depends on PROC_SYSCTL
1134 sys_sysctl uses binary paths that have been found challenging
1135 to properly maintain and use. The interface in /proc/sys
1136 using paths with ascii names is now the primary path to this
1139 Almost nothing using the binary sysctl interface so if you are
1140 trying to save some space it is probably safe to disable this,
1141 making your kernel marginally smaller.
1143 If unsure say N here.
1146 bool "open by fhandle syscalls" if EXPERT
1150 If you say Y here, a user level program will be able to map
1151 file names to handle and then later use the handle for
1152 different file system operations. This is useful in implementing
1153 userspace file servers, which now track files using handles instead
1154 of names. The handle would remain the same even if file names
1155 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1159 bool "Posix Clocks & timers" if EXPERT
1162 This includes native support for POSIX timers to the kernel.
1163 Some embedded systems have no use for them and therefore they
1164 can be configured out to reduce the size of the kernel image.
1166 When this option is disabled, the following syscalls won't be
1167 available: timer_create, timer_gettime: timer_getoverrun,
1168 timer_settime, timer_delete, clock_adjtime, getitimer,
1169 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1170 clock_getres and clock_nanosleep syscalls will be limited to
1171 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1177 bool "Enable support for printk" if EXPERT
1180 This option enables normal printk support. Removing it
1181 eliminates most of the message strings from the kernel image
1182 and makes the kernel more or less silent. As this makes it
1183 very difficult to diagnose system problems, saying N here is
1184 strongly discouraged.
1192 bool "BUG() support" if EXPERT
1195 Disabling this option eliminates support for BUG and WARN, reducing
1196 the size of your kernel image and potentially quietly ignoring
1197 numerous fatal conditions. You should only consider disabling this
1198 option for embedded systems with no facilities for reporting errors.
1204 bool "Enable ELF core dumps" if EXPERT
1206 Enable support for generating core dumps. Disabling saves about 4k.
1209 config PCSPKR_PLATFORM
1210 bool "Enable PC-Speaker support" if EXPERT
1211 depends on HAVE_PCSPKR_PLATFORM
1215 This option allows to disable the internal PC-Speaker
1216 support, saving some memory.
1220 bool "Enable full-sized data structures for core" if EXPERT
1222 Disabling this option reduces the size of miscellaneous core
1223 kernel data structures. This saves memory on small machines,
1224 but may reduce performance.
1227 bool "Enable futex support" if EXPERT
1231 Disabling this option will cause the kernel to be built without
1232 support for "fast userspace mutexes". The resulting kernel may not
1233 run glibc-based applications correctly.
1237 depends on FUTEX && RT_MUTEXES
1240 config HAVE_FUTEX_CMPXCHG
1244 Architectures should select this if futex_atomic_cmpxchg_inatomic()
1245 is implemented and always working. This removes a couple of runtime
1249 bool "Enable eventpoll support" if EXPERT
1253 Disabling this option will cause the kernel to be built without
1254 support for epoll family of system calls.
1257 bool "Enable signalfd() system call" if EXPERT
1261 Enable the signalfd() system call that allows to receive signals
1262 on a file descriptor.
1267 bool "Enable timerfd() system call" if EXPERT
1271 Enable the timerfd() system call that allows to receive timer
1272 events on a file descriptor.
1277 bool "Enable eventfd() system call" if EXPERT
1281 Enable the eventfd() system call that allows to receive both
1282 kernel notification (ie. KAIO) or userspace notifications.
1287 bool "Use full shmem filesystem" if EXPERT
1291 The shmem is an internal filesystem used to manage shared memory.
1292 It is backed by swap and manages resource limits. It is also exported
1293 to userspace as tmpfs if TMPFS is enabled. Disabling this
1294 option replaces shmem and tmpfs with the much simpler ramfs code,
1295 which may be appropriate on small systems without swap.
1298 bool "Enable AIO support" if EXPERT
1301 This option enables POSIX asynchronous I/O which may by used
1302 by some high performance threaded applications. Disabling
1303 this option saves about 7k.
1305 config ADVISE_SYSCALLS
1306 bool "Enable madvise/fadvise syscalls" if EXPERT
1309 This option enables the madvise and fadvise syscalls, used by
1310 applications to advise the kernel about their future memory or file
1311 usage, improving performance. If building an embedded system where no
1312 applications use these syscalls, you can disable this option to save
1316 bool "Enable membarrier() system call" if EXPERT
1319 Enable the membarrier() system call that allows issuing memory
1320 barriers across all running threads, which can be used to distribute
1321 the cost of user-space memory barriers asymmetrically by transforming
1322 pairs of memory barriers into pairs consisting of membarrier() and a
1327 config CHECKPOINT_RESTORE
1328 bool "Checkpoint/restore support" if EXPERT
1329 select PROC_CHILDREN
1332 Enables additional kernel features in a sake of checkpoint/restore.
1333 In particular it adds auxiliary prctl codes to setup process text,
1334 data and heap segment sizes, and a few additional /proc filesystem
1337 If unsure, say N here.
1340 bool "Load all symbols for debugging/ksymoops" if EXPERT
1343 Say Y here to let the kernel print out symbolic crash information and
1344 symbolic stack backtraces. This increases the size of the kernel
1345 somewhat, as all symbols have to be loaded into the kernel image.
1348 bool "Include all symbols in kallsyms"
1349 depends on DEBUG_KERNEL && KALLSYMS
1351 Normally kallsyms only contains the symbols of functions for nicer
1352 OOPS messages and backtraces (i.e., symbols from the text and inittext
1353 sections). This is sufficient for most cases. And only in very rare
1354 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1355 names of variables from the data sections, etc).
1357 This option makes sure that all symbols are loaded into the kernel
1358 image (i.e., symbols from all sections) in cost of increased kernel
1359 size (depending on the kernel configuration, it may be 300KiB or
1360 something like this).
1362 Say N unless you really need all symbols.
1364 config KALLSYMS_ABSOLUTE_PERCPU
1367 default X86_64 && SMP
1369 config KALLSYMS_BASE_RELATIVE
1374 Instead of emitting them as absolute values in the native word size,
1375 emit the symbol references in the kallsyms table as 32-bit entries,
1376 each containing a relative value in the range [base, base + U32_MAX]
1377 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1378 an absolute value in the range [0, S32_MAX] or a relative value in the
1379 range [base, base + S32_MAX], where base is the lowest relative symbol
1380 address encountered in the image.
1382 On 64-bit builds, this reduces the size of the address table by 50%,
1383 but more importantly, it results in entries whose values are build
1384 time constants, and no relocation pass is required at runtime to fix
1385 up the entries based on the runtime load address of the kernel.
1387 # end of the "standard kernel features (expert users)" menu
1389 # syscall, maps, verifier
1391 bool "Enable bpf() system call"
1396 Enable the bpf() system call that allows to manipulate eBPF
1397 programs and maps via file descriptors.
1399 config BPF_JIT_ALWAYS_ON
1400 bool "Permanently enable BPF JIT and remove BPF interpreter"
1401 depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
1403 Enables BPF JIT and removes BPF interpreter to avoid
1404 speculative execution of BPF instructions by the interpreter
1407 bool "Enable userfaultfd() system call"
1411 Enable the userfaultfd() system call that allows to intercept and
1412 handle page faults in userland.
1414 config ARCH_HAS_MEMBARRIER_CALLBACKS
1417 config ARCH_HAS_MEMBARRIER_SYNC_CORE
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" if EXPERT
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
1682 default 0 if BASE_FULL
1683 default 1 if !BASE_FULL
1686 bool "Enable loadable module support"
1689 Kernel modules are small pieces of compiled code which can
1690 be inserted in the running kernel, rather than being
1691 permanently built into the kernel. You use the "modprobe"
1692 tool to add (and sometimes remove) them. If you say Y here,
1693 many parts of the kernel can be built as modules (by
1694 answering M instead of Y where indicated): this is most
1695 useful for infrequently used options which are not required
1696 for booting. For more information, see the man pages for
1697 modprobe, lsmod, modinfo, insmod and rmmod.
1699 If you say Y here, you will need to run "make
1700 modules_install" to put the modules under /lib/modules/
1701 where modprobe can find them (you may need to be root to do
1708 config MODULE_FORCE_LOAD
1709 bool "Forced module loading"
1712 Allow loading of modules without version information (ie. modprobe
1713 --force). Forced module loading sets the 'F' (forced) taint flag and
1714 is usually a really bad idea.
1716 config MODULE_UNLOAD
1717 bool "Module unloading"
1719 Without this option you will not be able to unload any
1720 modules (note that some modules may not be unloadable
1721 anyway), which makes your kernel smaller, faster
1722 and simpler. If unsure, say Y.
1724 config MODULE_FORCE_UNLOAD
1725 bool "Forced module unloading"
1726 depends on MODULE_UNLOAD
1728 This option allows you to force a module to unload, even if the
1729 kernel believes it is unsafe: the kernel will remove the module
1730 without waiting for anyone to stop using it (using the -f option to
1731 rmmod). This is mainly for kernel developers and desperate users.
1735 bool "Module versioning support"
1737 Usually, you have to use modules compiled with your kernel.
1738 Saying Y here makes it sometimes possible to use modules
1739 compiled for different kernels, by adding enough information
1740 to the modules to (hopefully) spot any changes which would
1741 make them incompatible with the kernel you are running. If
1744 config MODULE_REL_CRCS
1746 depends on MODVERSIONS
1748 config MODULE_SRCVERSION_ALL
1749 bool "Source checksum for all modules"
1751 Modules which contain a MODULE_VERSION get an extra "srcversion"
1752 field inserted into their modinfo section, which contains a
1753 sum of the source files which made it. This helps maintainers
1754 see exactly which source was used to build a module (since
1755 others sometimes change the module source without updating
1756 the version). With this option, such a "srcversion" field
1757 will be created for all modules. If unsure, say N.
1760 bool "Module signature verification"
1762 select SYSTEM_DATA_VERIFICATION
1764 Check modules for valid signatures upon load: the signature
1765 is simply appended to the module. For more information see
1766 <file:Documentation/admin-guide/module-signing.rst>.
1768 Note that this option adds the OpenSSL development packages as a
1769 kernel build dependency so that the signing tool can use its crypto
1772 !!!WARNING!!! If you enable this option, you MUST make sure that the
1773 module DOES NOT get stripped after being signed. This includes the
1774 debuginfo strip done by some packagers (such as rpmbuild) and
1775 inclusion into an initramfs that wants the module size reduced.
1777 config MODULE_SIG_FORCE
1778 bool "Require modules to be validly signed"
1779 depends on MODULE_SIG
1781 Reject unsigned modules or signed modules for which we don't have a
1782 key. Without this, such modules will simply taint the kernel.
1784 config MODULE_SIG_ALL
1785 bool "Automatically sign all modules"
1787 depends on MODULE_SIG
1789 Sign all modules during make modules_install. Without this option,
1790 modules must be signed manually, using the scripts/sign-file tool.
1792 comment "Do not forget to sign required modules with scripts/sign-file"
1793 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
1796 prompt "Which hash algorithm should modules be signed with?"
1797 depends on MODULE_SIG
1799 This determines which sort of hashing algorithm will be used during
1800 signature generation. This algorithm _must_ be built into the kernel
1801 directly so that signature verification can take place. It is not
1802 possible to load a signed module containing the algorithm to check
1803 the signature on that module.
1805 config MODULE_SIG_SHA1
1806 bool "Sign modules with SHA-1"
1809 config MODULE_SIG_SHA224
1810 bool "Sign modules with SHA-224"
1811 select CRYPTO_SHA256
1813 config MODULE_SIG_SHA256
1814 bool "Sign modules with SHA-256"
1815 select CRYPTO_SHA256
1817 config MODULE_SIG_SHA384
1818 bool "Sign modules with SHA-384"
1819 select CRYPTO_SHA512
1821 config MODULE_SIG_SHA512
1822 bool "Sign modules with SHA-512"
1823 select CRYPTO_SHA512
1827 config MODULE_SIG_HASH
1829 depends on MODULE_SIG
1830 default "sha1" if MODULE_SIG_SHA1
1831 default "sha224" if MODULE_SIG_SHA224
1832 default "sha256" if MODULE_SIG_SHA256
1833 default "sha384" if MODULE_SIG_SHA384
1834 default "sha512" if MODULE_SIG_SHA512
1836 config MODULE_COMPRESS
1837 bool "Compress modules on installation"
1841 Compresses kernel modules when 'make modules_install' is run; gzip or
1842 xz depending on "Compression algorithm" below.
1844 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
1846 Out-of-tree kernel modules installed using Kbuild will also be
1847 compressed upon installation.
1849 Note: for modules inside an initrd or initramfs, it's more efficient
1850 to compress the whole initrd or initramfs instead.
1852 Note: This is fully compatible with signed modules.
1857 prompt "Compression algorithm"
1858 depends on MODULE_COMPRESS
1859 default MODULE_COMPRESS_GZIP
1861 This determines which sort of compression will be used during
1862 'make modules_install'.
1864 GZIP (default) and XZ are supported.
1866 config MODULE_COMPRESS_GZIP
1869 config MODULE_COMPRESS_XZ
1874 config TRIM_UNUSED_KSYMS
1875 bool "Trim unused exported kernel symbols"
1876 depends on MODULES && !UNUSED_SYMBOLS
1878 The kernel and some modules make many symbols available for
1879 other modules to use via EXPORT_SYMBOL() and variants. Depending
1880 on the set of modules being selected in your kernel configuration,
1881 many of those exported symbols might never be used.
1883 This option allows for unused exported symbols to be dropped from
1884 the build. In turn, this provides the compiler more opportunities
1885 (especially when using LTO) for optimizing the code and reducing
1886 binary size. This might have some security advantages as well.
1888 If unsure, or if you need to build out-of-tree modules, say N.
1892 config MODULES_TREE_LOOKUP
1894 depends on PERF_EVENTS || TRACING
1896 config INIT_ALL_POSSIBLE
1899 Back when each arch used to define their own cpu_online_mask and
1900 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
1901 with all 1s, and others with all 0s. When they were centralised,
1902 it was better to provide this option than to break all the archs
1903 and have several arch maintainers pursuing me down dark alleys.
1905 source "block/Kconfig"
1907 config PREEMPT_NOTIFIERS
1917 Build a simple ASN.1 grammar compiler that produces a bytecode output
1918 that can be interpreted by the ASN.1 stream decoder and used to
1919 inform it as to what tags are to be expected in a stream and what
1920 functions to call on what tags.
1922 source "kernel/Kconfig.locks"
1924 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
1927 # It may be useful for an architecture to override the definitions of the
1928 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
1929 # and the COMPAT_ variants in <linux/compat.h>, in particular to use a
1930 # different calling convention for syscalls. They can also override the
1931 # macros for not-implemented syscalls in kernel/sys_ni.c and
1932 # kernel/time/posix-stubs.c. All these overrides need to be available in
1933 # <asm/syscall_wrapper.h>.
1934 config ARCH_HAS_SYSCALL_WRAPPER
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