7 option env="KERNELVERSION"
13 default "/lib/modules/$UNAME_RELEASE/.config"
14 default "/etc/kernel-config"
15 default "/boot/config-$UNAME_RELEASE"
16 default "$ARCH_DEFCONFIG"
17 default "arch/$ARCH/defconfig"
26 config BUILDTIME_EXTABLE_SORT
29 config THREAD_INFO_IN_TASK
32 Select this to move thread_info off the stack into task_struct. To
33 make this work, an arch will need to remove all thread_info fields
34 except flags and fix any runtime bugs.
36 One subtle change that will be needed is to use try_get_task_stack()
37 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
46 depends on BROKEN || !SMP
49 config INIT_ENV_ARG_LIMIT
54 Maximum of each of the number of arguments and environment
55 variables passed to init from the kernel command line.
59 string "Cross-compiler tool prefix"
61 Same as running 'make CROSS_COMPILE=prefix-' but stored for
62 default make runs in this kernel build directory. You don't
63 need to set this unless you want the configured kernel build
64 directory to select the cross-compiler automatically.
67 bool "Compile also drivers which will not load"
71 Some drivers can be compiled on a different platform than they are
72 intended to be run on. Despite they cannot be loaded there (or even
73 when they load they cannot be used due to missing HW support),
74 developers still, opposing to distributors, might want to build such
75 drivers to compile-test them.
77 If you are a developer and want to build everything available, say Y
78 here. If you are a user/distributor, say N here to exclude useless
79 drivers to be distributed.
82 string "Local version - append to kernel release"
84 Append an extra string to the end of your kernel version.
85 This will show up when you type uname, for example.
86 The string you set here will be appended after the contents of
87 any files with a filename matching localversion* in your
88 object and source tree, in that order. Your total string can
89 be a maximum of 64 characters.
91 config LOCALVERSION_AUTO
92 bool "Automatically append version information to the version string"
94 depends on !COMPILE_TEST
96 This will try to automatically determine if the current tree is a
97 release tree by looking for git tags that belong to the current
100 A string of the format -gxxxxxxxx will be added to the localversion
101 if a git-based tree is found. The string generated by this will be
102 appended after any matching localversion* files, and after the value
103 set in CONFIG_LOCALVERSION.
105 (The actual string used here is the first eight characters produced
106 by running the command:
108 $ git rev-parse --verify HEAD
110 which is done within the script "scripts/setlocalversion".)
112 config HAVE_KERNEL_GZIP
115 config HAVE_KERNEL_BZIP2
118 config HAVE_KERNEL_LZMA
121 config HAVE_KERNEL_XZ
124 config HAVE_KERNEL_LZO
127 config HAVE_KERNEL_LZ4
131 prompt "Kernel compression mode"
133 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4
135 The linux kernel is a kind of self-extracting executable.
136 Several compression algorithms are available, which differ
137 in efficiency, compression and decompression speed.
138 Compression speed is only relevant when building a kernel.
139 Decompression speed is relevant at each boot.
141 If you have any problems with bzip2 or lzma compressed
143 version of this functionality (bzip2 only), for 2.4, was
144 supplied by Christian Ludwig)
146 High compression options are mostly useful for users, who
147 are low on disk space (embedded systems), but for whom ram
150 If in doubt, select 'gzip'
154 depends on HAVE_KERNEL_GZIP
156 The old and tried gzip compression. It provides a good balance
157 between compression ratio and decompression speed.
161 depends on HAVE_KERNEL_BZIP2
163 Its compression ratio and speed is intermediate.
164 Decompression speed is slowest among the choices. The kernel
165 size is about 10% smaller with bzip2, in comparison to gzip.
166 Bzip2 uses a large amount of memory. For modern kernels you
167 will need at least 8MB RAM or more for booting.
171 depends on HAVE_KERNEL_LZMA
173 This compression algorithm's ratio is best. Decompression speed
174 is between gzip and bzip2. Compression is slowest.
175 The kernel size is about 33% smaller with LZMA in comparison to gzip.
179 depends on HAVE_KERNEL_XZ
181 XZ uses the LZMA2 algorithm and instruction set specific
182 BCJ filters which can improve compression ratio of executable
183 code. The size of the kernel is about 30% smaller with XZ in
184 comparison to gzip. On architectures for which there is a BCJ
185 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
186 will create a few percent smaller kernel than plain LZMA.
188 The speed is about the same as with LZMA: The decompression
189 speed of XZ is better than that of bzip2 but worse than gzip
190 and LZO. Compression is slow.
194 depends on HAVE_KERNEL_LZO
196 Its compression ratio is the poorest among the choices. The kernel
197 size is about 10% bigger than gzip; however its speed
198 (both compression and decompression) is the fastest.
202 depends on HAVE_KERNEL_LZ4
204 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
205 A preliminary version of LZ4 de/compression tool is available at
206 <https://code.google.com/p/lz4/>.
208 Its compression ratio is worse than LZO. The size of the kernel
209 is about 8% bigger than LZO. But the decompression speed is
214 config DEFAULT_HOSTNAME
215 string "Default hostname"
218 This option determines the default system hostname before userspace
219 calls sethostname(2). The kernel traditionally uses "(none)" here,
220 but you may wish to use a different default here to make a minimal
221 system more usable with less configuration.
224 bool "Support for paging of anonymous memory (swap)"
225 depends on MMU && BLOCK
228 This option allows you to choose whether you want to have support
229 for so called swap devices or swap files in your kernel that are
230 used to provide more virtual memory than the actual RAM present
231 in your computer. If unsure say Y.
236 Inter Process Communication is a suite of library functions and
237 system calls which let processes (running programs) synchronize and
238 exchange information. It is generally considered to be a good thing,
239 and some programs won't run unless you say Y here. In particular, if
240 you want to run the DOS emulator dosemu under Linux (read the
241 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
242 you'll need to say Y here.
244 You can find documentation about IPC with "info ipc" and also in
245 section 6.4 of the Linux Programmer's Guide, available from
246 <http://www.tldp.org/guides.html>.
248 config SYSVIPC_SYSCTL
255 bool "POSIX Message Queues"
258 POSIX variant of message queues is a part of IPC. In POSIX message
259 queues every message has a priority which decides about succession
260 of receiving it by a process. If you want to compile and run
261 programs written e.g. for Solaris with use of its POSIX message
262 queues (functions mq_*) say Y here.
264 POSIX message queues are visible as a filesystem called 'mqueue'
265 and can be mounted somewhere if you want to do filesystem
266 operations on message queues.
270 config POSIX_MQUEUE_SYSCTL
272 depends on POSIX_MQUEUE
276 config CROSS_MEMORY_ATTACH
277 bool "Enable process_vm_readv/writev syscalls"
281 Enabling this option adds the system calls process_vm_readv and
282 process_vm_writev which allow a process with the correct privileges
283 to directly read from or write to another process' address space.
284 See the man page for more details.
287 bool "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"
465 Make sure that CPUs running critical tasks are not disturbed by
466 any source of "noise" such as unbound workqueues, timers, kthreads...
467 Unbound jobs get offloaded to housekeeping CPUs.
469 source "kernel/rcu/Kconfig"
476 tristate "Kernel .config support"
479 This option enables the complete Linux kernel ".config" file
480 contents to be saved in the kernel. It provides documentation
481 of which kernel options are used in a running kernel or in an
482 on-disk kernel. This information can be extracted from the kernel
483 image file with the script scripts/extract-ikconfig and used as
484 input to rebuild the current kernel or to build another kernel.
485 It can also be extracted from a running kernel by reading
486 /proc/config.gz if enabled (below).
489 bool "Enable access to .config through /proc/config.gz"
490 depends on IKCONFIG && PROC_FS
492 This option enables access to the kernel configuration file
493 through /proc/config.gz.
496 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
501 Select the minimal kernel log buffer size as a power of 2.
502 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
503 parameter, see below. Any higher size also might be forced
504 by "log_buf_len" boot parameter.
514 config LOG_CPU_MAX_BUF_SHIFT
515 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
518 default 12 if !BASE_SMALL
519 default 0 if BASE_SMALL
522 This option allows to increase the default ring buffer size
523 according to the number of CPUs. The value defines the contribution
524 of each CPU as a power of 2. The used space is typically only few
525 lines however it might be much more when problems are reported,
528 The increased size means that a new buffer has to be allocated and
529 the original static one is unused. It makes sense only on systems
530 with more CPUs. Therefore this value is used only when the sum of
531 contributions is greater than the half of the default kernel ring
532 buffer as defined by LOG_BUF_SHIFT. The default values are set
533 so that more than 64 CPUs are needed to trigger the allocation.
535 Also this option is ignored when "log_buf_len" kernel parameter is
536 used as it forces an exact (power of two) size of the ring buffer.
538 The number of possible CPUs is used for this computation ignoring
539 hotplugging making the computation optimal for the worst case
540 scenario while allowing a simple algorithm to be used from bootup.
542 Examples shift values and their meaning:
543 17 => 128 KB for each CPU
544 16 => 64 KB for each CPU
545 15 => 32 KB for each CPU
546 14 => 16 KB for each CPU
547 13 => 8 KB for each CPU
548 12 => 4 KB for each CPU
550 config PRINTK_SAFE_LOG_BUF_SHIFT
551 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
556 Select the size of an alternate printk per-CPU buffer where messages
557 printed from usafe contexts are temporary stored. One example would
558 be NMI messages, another one - printk recursion. The messages are
559 copied to the main log buffer in a safe context to avoid a deadlock.
560 The value defines the size as a power of 2.
562 Those messages are rare and limited. The largest one is when
563 a backtrace is printed. It usually fits into 4KB. Select
564 8KB if you want to be on the safe side.
567 17 => 128 KB for each CPU
568 16 => 64 KB for each CPU
569 15 => 32 KB for each CPU
570 14 => 16 KB for each CPU
571 13 => 8 KB for each CPU
572 12 => 4 KB for each CPU
575 # Architectures with an unreliable sched_clock() should select this:
577 config HAVE_UNSTABLE_SCHED_CLOCK
580 config GENERIC_SCHED_CLOCK
584 # For architectures that want to enable the support for NUMA-affine scheduler
587 config ARCH_SUPPORTS_NUMA_BALANCING
591 # For architectures that prefer to flush all TLBs after a number of pages
592 # are unmapped instead of sending one IPI per page to flush. The architecture
593 # must provide guarantees on what happens if a clean TLB cache entry is
594 # written after the unmap. Details are in mm/rmap.c near the check for
595 # should_defer_flush. The architecture should also consider if the full flush
596 # and the refill costs are offset by the savings of sending fewer IPIs.
597 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
601 # For architectures that know their GCC __int128 support is sound
603 config ARCH_SUPPORTS_INT128
606 # For architectures that (ab)use NUMA to represent different memory regions
607 # all cpu-local but of different latencies, such as SuperH.
609 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
612 config NUMA_BALANCING
613 bool "Memory placement aware NUMA scheduler"
614 depends on ARCH_SUPPORTS_NUMA_BALANCING
615 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
616 depends on SMP && NUMA && MIGRATION
618 This option adds support for automatic NUMA aware memory/task placement.
619 The mechanism is quite primitive and is based on migrating memory when
620 it has references to the node the task is running on.
622 This system will be inactive on UMA systems.
624 config NUMA_BALANCING_DEFAULT_ENABLED
625 bool "Automatically enable NUMA aware memory/task placement"
627 depends on NUMA_BALANCING
629 If set, automatic NUMA balancing will be enabled if running on a NUMA
633 bool "Control Group support"
636 This option adds support for grouping sets of processes together, for
637 use with process control subsystems such as Cpusets, CFS, memory
638 controls or device isolation.
640 - Documentation/scheduler/sched-design-CFS.txt (CFS)
641 - Documentation/cgroup-v1/ (features for grouping, isolation
642 and resource control)
652 bool "Memory controller"
656 Provides control over the memory footprint of tasks in a cgroup.
659 bool "Swap controller"
660 depends on MEMCG && SWAP
662 Provides control over the swap space consumed by tasks in a cgroup.
664 config MEMCG_SWAP_ENABLED
665 bool "Swap controller enabled by default"
666 depends on MEMCG_SWAP
669 Memory Resource Controller Swap Extension comes with its price in
670 a bigger memory consumption. General purpose distribution kernels
671 which want to enable the feature but keep it disabled by default
672 and let the user enable it by swapaccount=1 boot command line
673 parameter should have this option unselected.
674 For those who want to have the feature enabled by default should
675 select this option (if, for some reason, they need to disable it
676 then swapaccount=0 does the trick).
683 Generic block IO controller cgroup interface. This is the common
684 cgroup interface which should be used by various IO controlling
687 Currently, CFQ IO scheduler uses it to recognize task groups and
688 control disk bandwidth allocation (proportional time slice allocation)
689 to such task groups. It is also used by bio throttling logic in
690 block layer to implement upper limit in IO rates on a device.
692 This option only enables generic Block IO controller infrastructure.
693 One needs to also enable actual IO controlling logic/policy. For
694 enabling proportional weight division of disk bandwidth in CFQ, set
695 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
696 CONFIG_BLK_DEV_THROTTLING=y.
698 See Documentation/cgroup-v1/blkio-controller.txt for more information.
700 config DEBUG_BLK_CGROUP
701 bool "IO controller debugging"
702 depends on BLK_CGROUP
705 Enable some debugging help. Currently it exports additional stat
706 files in a cgroup which can be useful for debugging.
708 config CGROUP_WRITEBACK
710 depends on MEMCG && BLK_CGROUP
713 menuconfig CGROUP_SCHED
714 bool "CPU controller"
717 This feature lets CPU scheduler recognize task groups and control CPU
718 bandwidth allocation to such task groups. It uses cgroups to group
722 config FAIR_GROUP_SCHED
723 bool "Group scheduling for SCHED_OTHER"
724 depends on CGROUP_SCHED
728 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
729 depends on FAIR_GROUP_SCHED
732 This option allows users to define CPU bandwidth rates (limits) for
733 tasks running within the fair group scheduler. Groups with no limit
734 set are considered to be unconstrained and will run with no
736 See tip/Documentation/scheduler/sched-bwc.txt for more information.
738 config RT_GROUP_SCHED
739 bool "Group scheduling for SCHED_RR/FIFO"
740 depends on CGROUP_SCHED
743 This feature lets you explicitly allocate real CPU bandwidth
744 to task groups. If enabled, it will also make it impossible to
745 schedule realtime tasks for non-root users until you allocate
746 realtime bandwidth for them.
747 See Documentation/scheduler/sched-rt-group.txt for more information.
752 bool "PIDs controller"
754 Provides enforcement of process number limits in the scope of a
755 cgroup. Any attempt to fork more processes than is allowed in the
756 cgroup will fail. PIDs are fundamentally a global resource because it
757 is fairly trivial to reach PID exhaustion before you reach even a
758 conservative kmemcg limit. As a result, it is possible to grind a
759 system to halt without being limited by other cgroup policies. The
760 PIDs controller is designed to stop this from happening.
762 It should be noted that organisational operations (such as attaching
763 to a cgroup hierarchy will *not* be blocked by the PIDs controller),
764 since the PIDs limit only affects a process's ability to fork, not to
768 bool "RDMA controller"
770 Provides enforcement of RDMA resources defined by IB stack.
771 It is fairly easy for consumers to exhaust RDMA resources, which
772 can result into resource unavailability to other consumers.
773 RDMA controller is designed to stop this from happening.
774 Attaching processes with active RDMA resources to the cgroup
775 hierarchy is allowed even if can cross the hierarchy's limit.
777 config CGROUP_FREEZER
778 bool "Freezer controller"
780 Provides a way to freeze and unfreeze all tasks in a
783 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
784 controller includes important in-kernel memory consumers per default.
786 If you're using cgroup2, say N.
788 config CGROUP_HUGETLB
789 bool "HugeTLB controller"
790 depends on HUGETLB_PAGE
794 Provides a cgroup controller for HugeTLB pages.
795 When you enable this, you can put a per cgroup limit on HugeTLB usage.
796 The limit is enforced during page fault. Since HugeTLB doesn't
797 support page reclaim, enforcing the limit at page fault time implies
798 that, the application will get SIGBUS signal if it tries to access
799 HugeTLB pages beyond its limit. This requires the application to know
800 beforehand how much HugeTLB pages it would require for its use. The
801 control group is tracked in the third page lru pointer. This means
802 that we cannot use the controller with huge page less than 3 pages.
805 bool "Cpuset controller"
808 This option will let you create and manage CPUSETs which
809 allow dynamically partitioning a system into sets of CPUs and
810 Memory Nodes and assigning tasks to run only within those sets.
811 This is primarily useful on large SMP or NUMA systems.
815 config PROC_PID_CPUSET
816 bool "Include legacy /proc/<pid>/cpuset file"
821 bool "Device controller"
823 Provides a cgroup controller implementing whitelists for
824 devices which a process in the cgroup can mknod or open.
826 config CGROUP_CPUACCT
827 bool "Simple CPU accounting controller"
829 Provides a simple controller for monitoring the
830 total CPU consumed by the tasks in a cgroup.
833 bool "Perf controller"
834 depends on PERF_EVENTS
836 This option extends the perf per-cpu mode to restrict monitoring
837 to threads which belong to the cgroup specified and run on the
843 bool "Support for eBPF programs attached to cgroups"
844 depends on BPF_SYSCALL
845 select SOCK_CGROUP_DATA
847 Allow attaching eBPF programs to a cgroup using the bpf(2)
848 syscall command BPF_PROG_ATTACH.
850 In which context these programs are accessed depends on the type
851 of attachment. For instance, programs that are attached using
852 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
856 bool "Debug controller"
858 depends on DEBUG_KERNEL
860 This option enables a simple controller that exports
861 debugging information about the cgroups framework. This
862 controller is for control cgroup debugging only. Its
863 interfaces are not stable.
867 config SOCK_CGROUP_DATA
873 menuconfig NAMESPACES
874 bool "Namespaces support" if EXPERT
878 Provides the way to make tasks work with different objects using
879 the same id. For example same IPC id may refer to different objects
880 or same user id or pid may refer to different tasks when used in
881 different namespaces.
889 In this namespace tasks see different info provided with the
894 depends on (SYSVIPC || POSIX_MQUEUE)
897 In this namespace tasks work with IPC ids which correspond to
898 different IPC objects in different namespaces.
901 bool "User namespace"
904 This allows containers, i.e. vservers, to use user namespaces
905 to provide different user info for different servers.
907 When user namespaces are enabled in the kernel it is
908 recommended that the MEMCG option also be enabled and that
909 user-space use the memory control groups to limit the amount
910 of memory a memory unprivileged users can use.
915 bool "PID Namespaces"
918 Support process id namespaces. This allows having multiple
919 processes with the same pid as long as they are in different
920 pid namespaces. This is a building block of containers.
923 bool "Network namespace"
927 Allow user space to create what appear to be multiple instances
928 of the network stack.
932 config SCHED_AUTOGROUP
933 bool "Automatic process group scheduling"
936 select FAIR_GROUP_SCHED
938 This option optimizes the scheduler for common desktop workloads by
939 automatically creating and populating task groups. This separation
940 of workloads isolates aggressive CPU burners (like build jobs) from
941 desktop applications. Task group autogeneration is currently based
944 config SYSFS_DEPRECATED
945 bool "Enable deprecated sysfs features to support old userspace tools"
949 This option adds code that switches the layout of the "block" class
950 devices, to not show up in /sys/class/block/, but only in
953 This switch is only active when the sysfs.deprecated=1 boot option is
954 passed or the SYSFS_DEPRECATED_V2 option is set.
956 This option allows new kernels to run on old distributions and tools,
957 which might get confused by /sys/class/block/. Since 2007/2008 all
958 major distributions and tools handle this just fine.
960 Recent distributions and userspace tools after 2009/2010 depend on
961 the existence of /sys/class/block/, and will not work with this
964 Only if you are using a new kernel on an old distribution, you might
967 config SYSFS_DEPRECATED_V2
968 bool "Enable deprecated sysfs features by default"
971 depends on SYSFS_DEPRECATED
973 Enable deprecated sysfs by default.
975 See the CONFIG_SYSFS_DEPRECATED option for more details about this
978 Only if you are using a new kernel on an old distribution, you might
979 need to say Y here. Even then, odds are you would not need it
980 enabled, you can always pass the boot option if absolutely necessary.
983 bool "Kernel->user space relay support (formerly relayfs)"
986 This option enables support for relay interface support in
987 certain file systems (such as debugfs).
988 It is designed to provide an efficient mechanism for tools and
989 facilities to relay large amounts of data from kernel space to
994 config BLK_DEV_INITRD
995 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
996 depends on BROKEN || !FRV
998 The initial RAM filesystem is a ramfs which is loaded by the
999 boot loader (loadlin or lilo) and that is mounted as root
1000 before the normal boot procedure. It is typically used to
1001 load modules needed to mount the "real" root file system,
1002 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1004 If RAM disk support (BLK_DEV_RAM) is also included, this
1005 also enables initial RAM disk (initrd) support and adds
1006 15 Kbytes (more on some other architectures) to the kernel size.
1012 source "usr/Kconfig"
1017 prompt "Compiler optimization level"
1018 default CC_OPTIMIZE_FOR_PERFORMANCE
1020 config CC_OPTIMIZE_FOR_PERFORMANCE
1021 bool "Optimize for performance"
1023 This is the default optimization level for the kernel, building
1024 with the "-O2" compiler flag for best performance and most
1025 helpful compile-time warnings.
1027 config CC_OPTIMIZE_FOR_SIZE
1028 bool "Optimize for size"
1030 Enabling this option will pass "-Os" instead of "-O2" to
1031 your compiler resulting in a smaller kernel.
1046 config SYSCTL_EXCEPTION_TRACE
1049 Enable support for /proc/sys/debug/exception-trace.
1051 config SYSCTL_ARCH_UNALIGN_NO_WARN
1054 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1055 Allows arch to define/use @no_unaligned_warning to possibly warn
1056 about unaligned access emulation going on under the hood.
1058 config SYSCTL_ARCH_UNALIGN_ALLOW
1061 Enable support for /proc/sys/kernel/unaligned-trap
1062 Allows arches to define/use @unaligned_enabled to runtime toggle
1063 the unaligned access emulation.
1064 see arch/parisc/kernel/unaligned.c for reference
1066 config HAVE_PCSPKR_PLATFORM
1069 # interpreter that classic socket filters depend on
1074 bool "Configure standard kernel features (expert users)"
1075 # Unhide debug options, to make the on-by-default options visible
1078 This option allows certain base kernel options and settings
1079 to be disabled or tweaked. This is for specialized
1080 environments which can tolerate a "non-standard" kernel.
1081 Only use this if you really know what you are doing.
1084 bool "Enable 16-bit UID system calls" if EXPERT
1085 depends on HAVE_UID16 && MULTIUSER
1088 This enables the legacy 16-bit UID syscall wrappers.
1091 bool "Multiple users, groups and capabilities support" if EXPERT
1094 This option enables support for non-root users, groups and
1097 If you say N here, all processes will run with UID 0, GID 0, and all
1098 possible capabilities. Saying N here also compiles out support for
1099 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1102 If unsure, say Y here.
1104 config SGETMASK_SYSCALL
1105 bool "sgetmask/ssetmask syscalls support" if EXPERT
1106 def_bool PARISC || MN10300 || BLACKFIN || M68K || PPC || MIPS || X86 || SPARC || CRIS || MICROBLAZE || SUPERH
1108 sys_sgetmask and sys_ssetmask are obsolete system calls
1109 no longer supported in libc but still enabled by default in some
1112 If unsure, leave the default option here.
1114 config SYSFS_SYSCALL
1115 bool "Sysfs syscall support" if EXPERT
1118 sys_sysfs is an obsolete system call no longer supported in libc.
1119 Note that disabling this option is more secure but might break
1120 compatibility with some systems.
1122 If unsure say Y here.
1124 config SYSCTL_SYSCALL
1125 bool "Sysctl syscall support" if EXPERT
1126 depends on PROC_SYSCTL
1130 sys_sysctl uses binary paths that have been found challenging
1131 to properly maintain and use. The interface in /proc/sys
1132 using paths with ascii names is now the primary path to this
1135 Almost nothing using the binary sysctl interface so if you are
1136 trying to save some space it is probably safe to disable this,
1137 making your kernel marginally smaller.
1139 If unsure say N here.
1142 bool "open by fhandle syscalls" if EXPERT
1146 If you say Y here, a user level program will be able to map
1147 file names to handle and then later use the handle for
1148 different file system operations. This is useful in implementing
1149 userspace file servers, which now track files using handles instead
1150 of names. The handle would remain the same even if file names
1151 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1155 bool "Posix Clocks & timers" if EXPERT
1158 This includes native support for POSIX timers to the kernel.
1159 Some embedded systems have no use for them and therefore they
1160 can be configured out to reduce the size of the kernel image.
1162 When this option is disabled, the following syscalls won't be
1163 available: timer_create, timer_gettime: timer_getoverrun,
1164 timer_settime, timer_delete, clock_adjtime, getitimer,
1165 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1166 clock_getres and clock_nanosleep syscalls will be limited to
1167 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1173 bool "Enable support for printk" if EXPERT
1176 This option enables normal printk support. Removing it
1177 eliminates most of the message strings from the kernel image
1178 and makes the kernel more or less silent. As this makes it
1179 very difficult to diagnose system problems, saying N here is
1180 strongly discouraged.
1188 bool "BUG() support" if EXPERT
1191 Disabling this option eliminates support for BUG and WARN, reducing
1192 the size of your kernel image and potentially quietly ignoring
1193 numerous fatal conditions. You should only consider disabling this
1194 option for embedded systems with no facilities for reporting errors.
1200 bool "Enable ELF core dumps" if EXPERT
1202 Enable support for generating core dumps. Disabling saves about 4k.
1205 config PCSPKR_PLATFORM
1206 bool "Enable PC-Speaker support" if EXPERT
1207 depends on HAVE_PCSPKR_PLATFORM
1211 This option allows to disable the internal PC-Speaker
1212 support, saving some memory.
1216 bool "Enable full-sized data structures for core" if EXPERT
1218 Disabling this option reduces the size of miscellaneous core
1219 kernel data structures. This saves memory on small machines,
1220 but may reduce performance.
1223 bool "Enable futex support" if EXPERT
1227 Disabling this option will cause the kernel to be built without
1228 support for "fast userspace mutexes". The resulting kernel may not
1229 run glibc-based applications correctly.
1233 depends on FUTEX && RT_MUTEXES
1236 config HAVE_FUTEX_CMPXCHG
1240 Architectures should select this if futex_atomic_cmpxchg_inatomic()
1241 is implemented and always working. This removes a couple of runtime
1245 bool "Enable eventpoll support" if EXPERT
1249 Disabling this option will cause the kernel to be built without
1250 support for epoll family of system calls.
1253 bool "Enable signalfd() system call" if EXPERT
1257 Enable the signalfd() system call that allows to receive signals
1258 on a file descriptor.
1263 bool "Enable timerfd() system call" if EXPERT
1267 Enable the timerfd() system call that allows to receive timer
1268 events on a file descriptor.
1273 bool "Enable eventfd() system call" if EXPERT
1277 Enable the eventfd() system call that allows to receive both
1278 kernel notification (ie. KAIO) or userspace notifications.
1283 bool "Use full shmem filesystem" if EXPERT
1287 The shmem is an internal filesystem used to manage shared memory.
1288 It is backed by swap and manages resource limits. It is also exported
1289 to userspace as tmpfs if TMPFS is enabled. Disabling this
1290 option replaces shmem and tmpfs with the much simpler ramfs code,
1291 which may be appropriate on small systems without swap.
1294 bool "Enable AIO support" if EXPERT
1297 This option enables POSIX asynchronous I/O which may by used
1298 by some high performance threaded applications. Disabling
1299 this option saves about 7k.
1301 config ADVISE_SYSCALLS
1302 bool "Enable madvise/fadvise syscalls" if EXPERT
1305 This option enables the madvise and fadvise syscalls, used by
1306 applications to advise the kernel about their future memory or file
1307 usage, improving performance. If building an embedded system where no
1308 applications use these syscalls, you can disable this option to save
1312 bool "Enable membarrier() system call" if EXPERT
1315 Enable the membarrier() system call that allows issuing memory
1316 barriers across all running threads, which can be used to distribute
1317 the cost of user-space memory barriers asymmetrically by transforming
1318 pairs of memory barriers into pairs consisting of membarrier() and a
1323 config CHECKPOINT_RESTORE
1324 bool "Checkpoint/restore support" if EXPERT
1325 select PROC_CHILDREN
1328 Enables additional kernel features in a sake of checkpoint/restore.
1329 In particular it adds auxiliary prctl codes to setup process text,
1330 data and heap segment sizes, and a few additional /proc filesystem
1333 If unsure, say N here.
1336 bool "Load all symbols for debugging/ksymoops" if EXPERT
1339 Say Y here to let the kernel print out symbolic crash information and
1340 symbolic stack backtraces. This increases the size of the kernel
1341 somewhat, as all symbols have to be loaded into the kernel image.
1344 bool "Include all symbols in kallsyms"
1345 depends on DEBUG_KERNEL && KALLSYMS
1347 Normally kallsyms only contains the symbols of functions for nicer
1348 OOPS messages and backtraces (i.e., symbols from the text and inittext
1349 sections). This is sufficient for most cases. And only in very rare
1350 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1351 names of variables from the data sections, etc).
1353 This option makes sure that all symbols are loaded into the kernel
1354 image (i.e., symbols from all sections) in cost of increased kernel
1355 size (depending on the kernel configuration, it may be 300KiB or
1356 something like this).
1358 Say N unless you really need all symbols.
1360 config KALLSYMS_ABSOLUTE_PERCPU
1363 default X86_64 && SMP
1365 config KALLSYMS_BASE_RELATIVE
1368 default !IA64 && !(TILE && 64BIT)
1370 Instead of emitting them as absolute values in the native word size,
1371 emit the symbol references in the kallsyms table as 32-bit entries,
1372 each containing a relative value in the range [base, base + U32_MAX]
1373 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1374 an absolute value in the range [0, S32_MAX] or a relative value in the
1375 range [base, base + S32_MAX], where base is the lowest relative symbol
1376 address encountered in the image.
1378 On 64-bit builds, this reduces the size of the address table by 50%,
1379 but more importantly, it results in entries whose values are build
1380 time constants, and no relocation pass is required at runtime to fix
1381 up the entries based on the runtime load address of the kernel.
1383 # end of the "standard kernel features (expert users)" menu
1385 # syscall, maps, verifier
1387 bool "Enable bpf() system call"
1392 Enable the bpf() system call that allows to manipulate eBPF
1393 programs and maps via file descriptors.
1395 config BPF_JIT_ALWAYS_ON
1396 bool "Permanently enable BPF JIT and remove BPF interpreter"
1397 depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
1399 Enables BPF JIT and removes BPF interpreter to avoid
1400 speculative execution of BPF instructions by the interpreter
1403 bool "Enable userfaultfd() system call"
1407 Enable the userfaultfd() system call that allows to intercept and
1408 handle page faults in userland.
1411 bool "Embedded system"
1412 option allnoconfig_y
1415 This option should be enabled if compiling the kernel for
1416 an embedded system so certain expert options are available
1419 config HAVE_PERF_EVENTS
1422 See tools/perf/design.txt for details.
1424 config PERF_USE_VMALLOC
1427 See tools/perf/design.txt for details
1430 bool "PC/104 support"
1432 Expose PC/104 form factor device drivers and options available for
1433 selection and configuration. Enable this option if your target
1434 machine has a PC/104 bus.
1436 menu "Kernel Performance Events And Counters"
1439 bool "Kernel performance events and counters"
1440 default y if PROFILING
1441 depends on HAVE_PERF_EVENTS
1446 Enable kernel support for various performance events provided
1447 by software and hardware.
1449 Software events are supported either built-in or via the
1450 use of generic tracepoints.
1452 Most modern CPUs support performance events via performance
1453 counter registers. These registers count the number of certain
1454 types of hw events: such as instructions executed, cachemisses
1455 suffered, or branches mis-predicted - without slowing down the
1456 kernel or applications. These registers can also trigger interrupts
1457 when a threshold number of events have passed - and can thus be
1458 used to profile the code that runs on that CPU.
1460 The Linux Performance Event subsystem provides an abstraction of
1461 these software and hardware event capabilities, available via a
1462 system call and used by the "perf" utility in tools/perf/. It
1463 provides per task and per CPU counters, and it provides event
1464 capabilities on top of those.
1468 config DEBUG_PERF_USE_VMALLOC
1470 bool "Debug: use vmalloc to back perf mmap() buffers"
1471 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1472 select PERF_USE_VMALLOC
1474 Use vmalloc memory to back perf mmap() buffers.
1476 Mostly useful for debugging the vmalloc code on platforms
1477 that don't require it.
1483 config VM_EVENT_COUNTERS
1485 bool "Enable VM event counters for /proc/vmstat" if EXPERT
1487 VM event counters are needed for event counts to be shown.
1488 This option allows the disabling of the VM event counters
1489 on EXPERT systems. /proc/vmstat will only show page counts
1490 if VM event counters are disabled.
1494 bool "Enable SLUB debugging support" if EXPERT
1495 depends on SLUB && SYSFS
1497 SLUB has extensive debug support features. Disabling these can
1498 result in significant savings in code size. This also disables
1499 SLUB sysfs support. /sys/slab will not exist and there will be
1500 no support for cache validation etc.
1502 config SLUB_MEMCG_SYSFS_ON
1504 bool "Enable memcg SLUB sysfs support by default" if EXPERT
1505 depends on SLUB && SYSFS && MEMCG
1507 SLUB creates a directory under /sys/kernel/slab for each
1508 allocation cache to host info and debug files. If memory
1509 cgroup is enabled, each cache can have per memory cgroup
1510 caches. SLUB can create the same sysfs directories for these
1511 caches under /sys/kernel/slab/CACHE/cgroup but it can lead
1512 to a very high number of debug files being created. This is
1513 controlled by slub_memcg_sysfs boot parameter and this
1514 config option determines the parameter's default value.
1517 bool "Disable heap randomization"
1520 Randomizing heap placement makes heap exploits harder, but it
1521 also breaks ancient binaries (including anything libc5 based).
1522 This option changes the bootup default to heap randomization
1523 disabled, and can be overridden at runtime by setting
1524 /proc/sys/kernel/randomize_va_space to 2.
1526 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1529 prompt "Choose SLAB allocator"
1532 This option allows to select a slab allocator.
1536 select HAVE_HARDENED_USERCOPY_ALLOCATOR
1538 The regular slab allocator that is established and known to work
1539 well in all environments. It organizes cache hot objects in
1540 per cpu and per node queues.
1543 bool "SLUB (Unqueued Allocator)"
1544 select HAVE_HARDENED_USERCOPY_ALLOCATOR
1546 SLUB is a slab allocator that minimizes cache line usage
1547 instead of managing queues of cached objects (SLAB approach).
1548 Per cpu caching is realized using slabs of objects instead
1549 of queues of objects. SLUB can use memory efficiently
1550 and has enhanced diagnostics. SLUB is the default choice for
1555 bool "SLOB (Simple Allocator)"
1557 SLOB replaces the stock allocator with a drastically simpler
1558 allocator. SLOB is generally more space efficient but
1559 does not perform as well on large systems.
1563 config SLAB_MERGE_DEFAULT
1564 bool "Allow slab caches to be merged"
1567 For reduced kernel memory fragmentation, slab caches can be
1568 merged when they share the same size and other characteristics.
1569 This carries a risk of kernel heap overflows being able to
1570 overwrite objects from merged caches (and more easily control
1571 cache layout), which makes such heap attacks easier to exploit
1572 by attackers. By keeping caches unmerged, these kinds of exploits
1573 can usually only damage objects in the same cache. To disable
1574 merging at runtime, "slab_nomerge" can be passed on the kernel
1577 config SLAB_FREELIST_RANDOM
1579 depends on SLAB || SLUB
1580 bool "SLAB freelist randomization"
1582 Randomizes the freelist order used on creating new pages. This
1583 security feature reduces the predictability of the kernel slab
1584 allocator against heap overflows.
1586 config SLAB_FREELIST_HARDENED
1587 bool "Harden slab freelist metadata"
1590 Many kernel heap attacks try to target slab cache metadata and
1591 other infrastructure. This options makes minor performance
1592 sacrifies to harden the kernel slab allocator against common
1593 freelist exploit methods.
1595 config SLUB_CPU_PARTIAL
1597 depends on SLUB && SMP
1598 bool "SLUB per cpu partial cache"
1600 Per cpu partial caches accellerate objects allocation and freeing
1601 that is local to a processor at the price of more indeterminism
1602 in the latency of the free. On overflow these caches will be cleared
1603 which requires the taking of locks that may cause latency spikes.
1604 Typically one would choose no for a realtime system.
1606 config MMAP_ALLOW_UNINITIALIZED
1607 bool "Allow mmapped anonymous memory to be uninitialized"
1608 depends on EXPERT && !MMU
1611 Normally, and according to the Linux spec, anonymous memory obtained
1612 from mmap() has it's contents cleared before it is passed to
1613 userspace. Enabling this config option allows you to request that
1614 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1615 providing a huge performance boost. If this option is not enabled,
1616 then the flag will be ignored.
1618 This is taken advantage of by uClibc's malloc(), and also by
1619 ELF-FDPIC binfmt's brk and stack allocator.
1621 Because of the obvious security issues, this option should only be
1622 enabled on embedded devices where you control what is run in
1623 userspace. Since that isn't generally a problem on no-MMU systems,
1624 it is normally safe to say Y here.
1626 See Documentation/nommu-mmap.txt for more information.
1628 config SYSTEM_DATA_VERIFICATION
1630 select SYSTEM_TRUSTED_KEYRING
1634 select ASYMMETRIC_KEY_TYPE
1635 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1638 select X509_CERTIFICATE_PARSER
1639 select PKCS7_MESSAGE_PARSER
1641 Provide PKCS#7 message verification using the contents of the system
1642 trusted keyring to provide public keys. This then can be used for
1643 module verification, kexec image verification and firmware blob
1647 bool "Profiling support"
1649 Say Y here to enable the extended profiling support mechanisms used
1650 by profilers such as OProfile.
1653 # Place an empty function call at each tracepoint site. Can be
1654 # dynamically changed for a probe function.
1659 source "arch/Kconfig"
1661 endmenu # General setup
1663 config HAVE_GENERIC_DMA_COHERENT
1672 default 0 if BASE_FULL
1673 default 1 if !BASE_FULL
1676 bool "Enable loadable module support"
1679 Kernel modules are small pieces of compiled code which can
1680 be inserted in the running kernel, rather than being
1681 permanently built into the kernel. You use the "modprobe"
1682 tool to add (and sometimes remove) them. If you say Y here,
1683 many parts of the kernel can be built as modules (by
1684 answering M instead of Y where indicated): this is most
1685 useful for infrequently used options which are not required
1686 for booting. For more information, see the man pages for
1687 modprobe, lsmod, modinfo, insmod and rmmod.
1689 If you say Y here, you will need to run "make
1690 modules_install" to put the modules under /lib/modules/
1691 where modprobe can find them (you may need to be root to do
1698 config MODULE_FORCE_LOAD
1699 bool "Forced module loading"
1702 Allow loading of modules without version information (ie. modprobe
1703 --force). Forced module loading sets the 'F' (forced) taint flag and
1704 is usually a really bad idea.
1706 config MODULE_UNLOAD
1707 bool "Module unloading"
1709 Without this option you will not be able to unload any
1710 modules (note that some modules may not be unloadable
1711 anyway), which makes your kernel smaller, faster
1712 and simpler. If unsure, say Y.
1714 config MODULE_FORCE_UNLOAD
1715 bool "Forced module unloading"
1716 depends on MODULE_UNLOAD
1718 This option allows you to force a module to unload, even if the
1719 kernel believes it is unsafe: the kernel will remove the module
1720 without waiting for anyone to stop using it (using the -f option to
1721 rmmod). This is mainly for kernel developers and desperate users.
1725 bool "Module versioning support"
1727 Usually, you have to use modules compiled with your kernel.
1728 Saying Y here makes it sometimes possible to use modules
1729 compiled for different kernels, by adding enough information
1730 to the modules to (hopefully) spot any changes which would
1731 make them incompatible with the kernel you are running. If
1734 config MODULE_REL_CRCS
1736 depends on MODVERSIONS
1738 config MODULE_SRCVERSION_ALL
1739 bool "Source checksum for all modules"
1741 Modules which contain a MODULE_VERSION get an extra "srcversion"
1742 field inserted into their modinfo section, which contains a
1743 sum of the source files which made it. This helps maintainers
1744 see exactly which source was used to build a module (since
1745 others sometimes change the module source without updating
1746 the version). With this option, such a "srcversion" field
1747 will be created for all modules. If unsure, say N.
1750 bool "Module signature verification"
1752 select SYSTEM_DATA_VERIFICATION
1754 Check modules for valid signatures upon load: the signature
1755 is simply appended to the module. For more information see
1756 <file:Documentation/admin-guide/module-signing.rst>.
1758 Note that this option adds the OpenSSL development packages as a
1759 kernel build dependency so that the signing tool can use its crypto
1762 !!!WARNING!!! If you enable this option, you MUST make sure that the
1763 module DOES NOT get stripped after being signed. This includes the
1764 debuginfo strip done by some packagers (such as rpmbuild) and
1765 inclusion into an initramfs that wants the module size reduced.
1767 config MODULE_SIG_FORCE
1768 bool "Require modules to be validly signed"
1769 depends on MODULE_SIG
1771 Reject unsigned modules or signed modules for which we don't have a
1772 key. Without this, such modules will simply taint the kernel.
1774 config MODULE_SIG_ALL
1775 bool "Automatically sign all modules"
1777 depends on MODULE_SIG
1779 Sign all modules during make modules_install. Without this option,
1780 modules must be signed manually, using the scripts/sign-file tool.
1782 comment "Do not forget to sign required modules with scripts/sign-file"
1783 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
1786 prompt "Which hash algorithm should modules be signed with?"
1787 depends on MODULE_SIG
1789 This determines which sort of hashing algorithm will be used during
1790 signature generation. This algorithm _must_ be built into the kernel
1791 directly so that signature verification can take place. It is not
1792 possible to load a signed module containing the algorithm to check
1793 the signature on that module.
1795 config MODULE_SIG_SHA1
1796 bool "Sign modules with SHA-1"
1799 config MODULE_SIG_SHA224
1800 bool "Sign modules with SHA-224"
1801 select CRYPTO_SHA256
1803 config MODULE_SIG_SHA256
1804 bool "Sign modules with SHA-256"
1805 select CRYPTO_SHA256
1807 config MODULE_SIG_SHA384
1808 bool "Sign modules with SHA-384"
1809 select CRYPTO_SHA512
1811 config MODULE_SIG_SHA512
1812 bool "Sign modules with SHA-512"
1813 select CRYPTO_SHA512
1817 config MODULE_SIG_HASH
1819 depends on MODULE_SIG
1820 default "sha1" if MODULE_SIG_SHA1
1821 default "sha224" if MODULE_SIG_SHA224
1822 default "sha256" if MODULE_SIG_SHA256
1823 default "sha384" if MODULE_SIG_SHA384
1824 default "sha512" if MODULE_SIG_SHA512
1826 config MODULE_COMPRESS
1827 bool "Compress modules on installation"
1831 Compresses kernel modules when 'make modules_install' is run; gzip or
1832 xz depending on "Compression algorithm" below.
1834 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
1836 Out-of-tree kernel modules installed using Kbuild will also be
1837 compressed upon installation.
1839 Note: for modules inside an initrd or initramfs, it's more efficient
1840 to compress the whole initrd or initramfs instead.
1842 Note: This is fully compatible with signed modules.
1847 prompt "Compression algorithm"
1848 depends on MODULE_COMPRESS
1849 default MODULE_COMPRESS_GZIP
1851 This determines which sort of compression will be used during
1852 'make modules_install'.
1854 GZIP (default) and XZ are supported.
1856 config MODULE_COMPRESS_GZIP
1859 config MODULE_COMPRESS_XZ
1864 config TRIM_UNUSED_KSYMS
1865 bool "Trim unused exported kernel symbols"
1866 depends on MODULES && !UNUSED_SYMBOLS
1868 The kernel and some modules make many symbols available for
1869 other modules to use via EXPORT_SYMBOL() and variants. Depending
1870 on the set of modules being selected in your kernel configuration,
1871 many of those exported symbols might never be used.
1873 This option allows for unused exported symbols to be dropped from
1874 the build. In turn, this provides the compiler more opportunities
1875 (especially when using LTO) for optimizing the code and reducing
1876 binary size. This might have some security advantages as well.
1878 If unsure, or if you need to build out-of-tree modules, say N.
1882 config MODULES_TREE_LOOKUP
1884 depends on PERF_EVENTS || TRACING
1886 config INIT_ALL_POSSIBLE
1889 Back when each arch used to define their own cpu_online_mask and
1890 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
1891 with all 1s, and others with all 0s. When they were centralised,
1892 it was better to provide this option than to break all the archs
1893 and have several arch maintainers pursuing me down dark alleys.
1895 source "block/Kconfig"
1897 config PREEMPT_NOTIFIERS
1907 Build a simple ASN.1 grammar compiler that produces a bytecode output
1908 that can be interpreted by the ASN.1 stream decoder and used to
1909 inform it as to what tags are to be expected in a stream and what
1910 functions to call on what tags.
1912 source "kernel/Kconfig.locks"
projects / linux.git / blob