1 # SPDX-License-Identifier: GPL-2.0-only
3 # Copyright (C) 2006-2014 OpenWrt.org
5 config KERNEL_BUILD_USER
6 string "Custom Kernel Build User Name"
7 default "builder" if BUILDBOT
10 Sets the Kernel build user string, which for example will be returned
11 by 'uname -a' on running systems.
12 If not set, uses system user at build time.
14 config KERNEL_BUILD_DOMAIN
15 string "Custom Kernel Build Domain Name"
16 default "buildhost" if BUILDBOT
19 Sets the Kernel build domain string, which for example will be
20 returned by 'uname -a' on running systems.
21 If not set, uses system hostname at build time.
24 bool "Enable support for printk"
28 bool "Support for paging of anonymous memory (swap)"
29 default y if !SMALL_FLASH
31 config KERNEL_PROC_STRIPPED
32 bool "Strip non-essential /proc functionality to reduce code size"
33 default y if SMALL_FLASH
35 config KERNEL_DEBUG_FS
36 bool "Compile the kernel with debug filesystem enabled"
39 debugfs is a virtual file system that kernel developers use to put
40 debugging files into. Enable this option to be able to read and
41 write to these files. Many common debugging facilities, such as
42 ftrace, require the existence of debugfs.
44 config KERNEL_MIPS_FP_SUPPORT
46 default y if TARGET_pistachio
51 depends on (arm || aarch64)
53 config KERNEL_X86_VSYSCALL_EMULATION
54 bool "Enable vsyscall emulation"
58 This enables emulation of the legacy vsyscall page. Disabling
59 it is roughly equivalent to booting with vsyscall=none, except
60 that it will also disable the helpful warning if a program
61 tries to use a vsyscall. With this option set to N, offending
62 programs will just segfault, citing addresses of the form
65 This option is required by many programs built before 2013, and
66 care should be used even with newer programs if set to N.
68 Disabling this option saves about 7K of kernel size and
69 possibly 4K of additional runtime pagetable memory.
71 config KERNEL_PERF_EVENTS
72 bool "Compile the kernel with performance events and counters"
74 select KERNEL_ARM_PMU if (arm || aarch64)
76 config KERNEL_PROFILING
77 bool "Compile the kernel with profiling enabled"
79 select KERNEL_PERF_EVENTS
81 Enable the extended profiling support mechanisms used by profilers such
84 config KERNEL_RPI_AXIPERF
85 bool "Compile the kernel with RaspberryPi AXI Performance monitors"
87 depends on KERNEL_PERF_EVENTS && TARGET_bcm27xx
90 bool "Compile the kernel with undefined behaviour sanity checker"
92 This option enables undefined behaviour sanity checker
93 Compile-time instrumentation is used to detect various undefined
94 behaviours in runtime. Various types of checks may be enabled
95 via boot parameter ubsan_handle
96 (see: Documentation/dev-tools/ubsan.rst).
98 config KERNEL_UBSAN_SANITIZE_ALL
99 bool "Enable instrumentation for the entire kernel"
100 depends on KERNEL_UBSAN
103 This option activates instrumentation for the entire kernel.
104 If you don't enable this option, you have to explicitly specify
105 UBSAN_SANITIZE := y for the files/directories you want to check for UB.
106 Enabling this option will get kernel image size increased
109 config KERNEL_UBSAN_ALIGNMENT
110 bool "Enable checking of pointers alignment"
111 depends on KERNEL_UBSAN
113 This option enables detection of unaligned memory accesses.
114 Enabling this option on architectures that support unaligned
115 accesses may produce a lot of false positives.
117 config KERNEL_UBSAN_BOUNDS
118 bool "Perform array index bounds checking"
119 depends on KERNEL_UBSAN
121 This option enables detection of directly indexed out of bounds array
122 accesses, where the array size is known at compile time. Note that
123 this does not protect array overflows via bad calls to the
124 {str,mem}*cpy() family of functions (that is addressed by
127 config KERNEL_UBSAN_NULL
128 bool "Enable checking of null pointers"
129 depends on KERNEL_UBSAN
131 This option enables detection of memory accesses via a
134 config KERNEL_UBSAN_TRAP
135 bool "On Sanitizer warnings, abort the running kernel code"
136 depends on KERNEL_UBSAN
138 Building kernels with Sanitizer features enabled tends to grow the
139 kernel size by around 5%, due to adding all the debugging text on
140 failure paths. To avoid this, Sanitizer instrumentation can just
141 issue a trap. This reduces the kernel size overhead but turns all
142 warnings (including potentially harmless conditions) into full
143 exceptions that abort the running kernel code (regardless of context,
144 locks held, etc), which may destabilize the system. For some system
145 builders this is an acceptable trade-off.
148 bool "Compile the kernel with KASan: runtime memory debugger"
149 select KERNEL_SLUB_DEBUG
150 depends on (x86_64 || aarch64)
152 Enables kernel address sanitizer - runtime memory debugger,
153 designed to find out-of-bounds accesses and use-after-free bugs.
154 This is strictly a debugging feature and it requires a gcc version
155 of 4.9.2 or later. Detection of out of bounds accesses to stack or
156 global variables requires gcc 5.0 or later.
157 This feature consumes about 1/8 of available memory and brings about
158 ~x3 performance slowdown.
159 For better error detection enable CONFIG_STACKTRACE.
160 Currently CONFIG_KASAN doesn't work with CONFIG_DEBUG_SLAB
161 (the resulting kernel does not boot).
163 config KERNEL_KASAN_EXTRA
164 bool "KAsan: extra checks"
165 depends on KERNEL_KASAN && KERNEL_DEBUG_KERNEL
167 This enables further checks in the kernel address sanitizer, for now
168 it only includes the address-use-after-scope check that can lead
169 to excessive kernel stack usage, frame size warnings and longer
171 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715 has more
173 config KERNEL_KASAN_VMALLOC
174 bool "Back mappings in vmalloc space with real shadow memory"
175 depends on KERNEL_KASAN
177 By default, the shadow region for vmalloc space is the read-only
178 zero page. This means that KASAN cannot detect errors involving
181 Enabling this option will hook in to vmap/vmalloc and back those
182 mappings with real shadow memory allocated on demand. This allows
183 for KASAN to detect more sorts of errors (and to support vmapped
184 stacks), but at the cost of higher memory usage.
186 This option depends on HAVE_ARCH_KASAN_VMALLOC, but we can't
187 depend on that in here, so it is possible that enabling this
191 config KERNEL_KASAN_GENERIC
194 config KERNEL_KASAN_SW_TAGS
199 prompt "Instrumentation type"
200 depends on KERNEL_KASAN
201 default KERNEL_KASAN_OUTLINE
203 config KERNEL_KASAN_OUTLINE
204 bool "Outline instrumentation"
206 Before every memory access compiler insert function call
207 __asan_load*/__asan_store*. These functions performs check
208 of shadow memory. This is slower than inline instrumentation,
209 however it doesn't bloat size of kernel's .text section so
212 config KERNEL_KASAN_INLINE
213 bool "Inline instrumentation"
215 Compiler directly inserts code checking shadow memory before
216 memory accesses. This is faster than outline (in some workloads
217 it gives about x2 boost over outline instrumentation), but
218 make kernel's .text size much bigger.
219 This requires a gcc version of 5.0 or later.
224 bool "Compile the kernel with code coverage for fuzzing"
225 select KERNEL_DEBUG_FS
227 KCOV exposes kernel code coverage information in a form suitable
228 for coverage-guided fuzzing (randomized testing).
230 If RANDOMIZE_BASE is enabled, PC values will not be stable across
231 different machines and across reboots. If you need stable PC values,
232 disable RANDOMIZE_BASE.
234 For more details, see Documentation/kcov.txt.
236 config KERNEL_KCOV_ENABLE_COMPARISONS
237 bool "Enable comparison operands collection by KCOV"
238 depends on KERNEL_KCOV
240 KCOV also exposes operands of every comparison in the instrumented
241 code along with operand sizes and PCs of the comparison instructions.
242 These operands can be used by fuzzing engines to improve the quality
245 config KERNEL_KCOV_INSTRUMENT_ALL
246 bool "Instrument all code by default"
247 depends on KERNEL_KCOV
248 default y if KERNEL_KCOV
250 If you are doing generic system call fuzzing (like e.g. syzkaller),
251 then you will want to instrument the whole kernel and you should
252 say y here. If you are doing more targeted fuzzing (like e.g.
253 filesystem fuzzing with AFL) then you will want to enable coverage
254 for more specific subsets of files, and should say n here.
256 config KERNEL_TASKSTATS
257 bool "Compile the kernel with task resource/io statistics and accounting"
260 Enable the collection and publishing of task/io statistics and
261 accounting. Enable this option to enable i/o monitoring in system
266 config KERNEL_TASK_DELAY_ACCT
269 config KERNEL_TASK_IO_ACCOUNTING
272 config KERNEL_TASK_XACCT
277 config KERNEL_KALLSYMS
278 bool "Compile the kernel with symbol table information"
279 default y if !SMALL_FLASH
281 This will give you more information in stack traces from kernel oopses.
284 bool "Compile the kernel with tracing support"
285 depends on !TARGET_uml
288 config KERNEL_FTRACE_SYSCALLS
289 bool "Trace system calls"
290 depends on KERNEL_FTRACE
293 config KERNEL_ENABLE_DEFAULT_TRACERS
294 bool "Trace process context switches and events"
295 depends on KERNEL_FTRACE
298 config KERNEL_FUNCTION_TRACER
299 bool "Function tracer"
300 depends on KERNEL_FTRACE
303 config KERNEL_FUNCTION_GRAPH_TRACER
304 bool "Function graph tracer"
305 depends on KERNEL_FUNCTION_TRACER
308 config KERNEL_DYNAMIC_FTRACE
309 bool "Enable/disable function tracing dynamically"
310 depends on KERNEL_FUNCTION_TRACER
313 config KERNEL_FUNCTION_PROFILER
314 bool "Function profiler"
315 depends on KERNEL_FUNCTION_TRACER
318 config KERNEL_IRQSOFF_TRACER
319 bool "Interrupts-off Latency Tracer"
320 depends on KERNEL_FTRACE
322 This option measures the time spent in irqs-off critical
323 sections, with microsecond accuracy.
325 The default measurement method is a maximum search, which is
326 disabled by default and can be runtime (re-)started
329 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
331 (Note that kernel size and overhead increase with this option
332 enabled. This option and the preempt-off timing option can be
333 used together or separately.)
335 config KERNEL_PREEMPT_TRACER
336 bool "Preemption-off Latency Tracer"
337 depends on KERNEL_FTRACE
339 This option measures the time spent in preemption-off critical
340 sections, with microsecond accuracy.
342 The default measurement method is a maximum search, which is
343 disabled by default and can be runtime (re-)started
346 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
348 (Note that kernel size and overhead increase with this option
349 enabled. This option and the irqs-off timing option can be
350 used together or separately.)
352 config KERNEL_HIST_TRIGGERS
353 bool "Histogram triggers"
354 depends on KERNEL_FTRACE
356 Hist triggers allow one or more arbitrary trace event fields to be
357 aggregated into hash tables and dumped to stdout by reading a
358 debugfs/tracefs file. They're useful for gathering quick and dirty
359 (though precise) summaries of event activity as an initial guide for
360 further investigation using more advanced tools.
362 Inter-event tracing of quantities such as latencies is also
363 supported using hist triggers under this option.
365 config KERNEL_DEBUG_KERNEL
369 config KERNEL_DEBUG_INFO
370 bool "Compile the kernel with debug information"
371 default y if !SMALL_FLASH
372 select KERNEL_DEBUG_KERNEL
374 This will compile your kernel and modules with debug information.
376 config KERNEL_DEBUG_INFO_BTF
378 bool "Enable additional BTF type information"
380 depends on !HOST_OS_MACOS
381 depends on KERNEL_DEBUG_INFO && !KERNEL_DEBUG_INFO_REDUCED
384 Generate BPF Type Format (BTF) information from DWARF debug info.
385 Turning this on expects presence of pahole tool, which will convert
386 DWARF type info into equivalent deduplicated BTF type info.
388 Required to run BPF CO-RE applications.
390 config KERNEL_DEBUG_INFO_REDUCED
391 bool "Reduce debugging information"
393 depends on KERNEL_DEBUG_INFO
395 If you say Y here gcc is instructed to generate less debugging
396 information for structure types. This means that tools that
397 need full debugging information (like kgdb or systemtap) won't
398 be happy. But if you merely need debugging information to
399 resolve line numbers there is no loss. Advantage is that
400 build directory object sizes shrink dramatically over a full
401 DEBUG_INFO build and compile times are reduced too.
402 Only works with newer gcc versions.
404 config KERNEL_DEBUG_LL_UART_NONE
409 config KERNEL_DEBUG_LL
413 select KERNEL_DEBUG_LL_UART_NONE
415 ARM low level debugging.
417 config KERNEL_DYNAMIC_DEBUG
418 bool "Compile the kernel with dynamic printk"
419 select KERNEL_DEBUG_FS
422 Compiles debug level messages into the kernel, which would not
423 otherwise be available at runtime. These messages can then be
424 enabled/disabled based on various levels of scope - per source file,
425 function, module, format string, and line number. This mechanism
426 implicitly compiles in all pr_debug() and dev_dbg() calls, which
427 enlarges the kernel text size by about 2%.
429 config KERNEL_EARLY_PRINTK
430 bool "Compile the kernel with early printk"
431 default y if TARGET_bcm53xx
434 select KERNEL_DEBUG_KERNEL
435 select KERNEL_DEBUG_LL if arm
437 Compile the kernel with early printk support. This is only useful for
438 debugging purposes to send messages over the serial console in early boot.
439 Enable this to debug early boot problems.
441 config KERNEL_KPROBES
442 bool "Compile the kernel with kprobes support"
445 select KERNEL_PERF_EVENTS
447 Compiles the kernel with KPROBES support, which allows you to trap
448 at almost any kernel address and execute a callback function.
449 register_kprobe() establishes a probepoint and specifies the
450 callback. Kprobes is useful for kernel debugging, non-intrusive
451 instrumentation and testing.
452 If in doubt, say "N".
454 config KERNEL_KPROBE_EVENTS
456 default y if KERNEL_KPROBES
458 config KERNEL_BPF_KPROBE_OVERRIDE
460 depends on KERNEL_KPROBES
464 bool "Compile the kernel with asynchronous IO support"
465 default y if !SMALL_FLASH
467 config KERNEL_IO_URING
468 bool "Compile the kernel with io_uring support"
469 default y if !SMALL_FLASH
471 config KERNEL_FHANDLE
472 bool "Compile the kernel with support for fhandle syscalls"
473 default y if !SMALL_FLASH
475 config KERNEL_FANOTIFY
476 bool "Compile the kernel with modern file notification support"
477 default y if !SMALL_FLASH
479 config KERNEL_BLK_DEV_BSG
480 bool "Compile the kernel with SCSI generic v4 support for any block device"
483 config KERNEL_TRANSPARENT_HUGEPAGE
487 prompt "Transparent Hugepage Support sysfs defaults"
488 depends on KERNEL_TRANSPARENT_HUGEPAGE
489 default KERNEL_TRANSPARENT_HUGEPAGE_ALWAYS
491 config KERNEL_TRANSPARENT_HUGEPAGE_ALWAYS
494 config KERNEL_TRANSPARENT_HUGEPAGE_MADVISE
498 config KERNEL_HUGETLBFS
501 config KERNEL_HUGETLB_PAGE
502 bool "Compile the kernel with HugeTLB support"
503 select KERNEL_TRANSPARENT_HUGEPAGE
504 select KERNEL_HUGETLBFS
507 config KERNEL_MAGIC_SYSRQ
508 bool "Compile the kernel with SysRq support"
511 config KERNEL_DEBUG_PINCTRL
512 bool "Compile the kernel with pinctrl debugging"
513 select KERNEL_DEBUG_KERNEL
515 config KERNEL_DEBUG_GPIO
516 bool "Compile the kernel with gpio debugging"
517 select KERNEL_DEBUG_KERNEL
519 config KERNEL_COREDUMP
522 config KERNEL_ELF_CORE
523 bool "Enable process core dump support"
524 select KERNEL_COREDUMP
525 default y if !SMALL_FLASH
527 config KERNEL_PROVE_LOCKING
528 bool "Enable kernel lock checking"
529 select KERNEL_DEBUG_KERNEL
532 config KERNEL_SOFTLOCKUP_DETECTOR
533 bool "Compile the kernel with detect Soft Lockups"
534 depends on KERNEL_DEBUG_KERNEL
536 Say Y here to enable the kernel to act as a watchdog to detect
539 Softlockups are bugs that cause the kernel to loop in kernel
540 mode for more than 20 seconds, without giving other tasks a
541 chance to run. The current stack trace is displayed upon
542 detection and the system will stay locked up.
544 config KERNEL_DETECT_HUNG_TASK
545 bool "Compile the kernel with detect Hung Tasks"
546 depends on KERNEL_DEBUG_KERNEL
547 default KERNEL_SOFTLOCKUP_DETECTOR
549 Say Y here to enable the kernel to detect "hung tasks",
550 which are bugs that cause the task to be stuck in
551 uninterruptible "D" state indefinitely.
553 When a hung task is detected, the kernel will print the
554 current stack trace (which you should report), but the
555 task will stay in uninterruptible state. If lockdep is
556 enabled then all held locks will also be reported. This
557 feature has negligible overhead.
559 config KERNEL_WQ_WATCHDOG
560 bool "Compile the kernel with detect Workqueue Stalls"
561 depends on KERNEL_DEBUG_KERNEL
563 Say Y here to enable stall detection on workqueues. If a
564 worker pool doesn't make forward progress on a pending work
565 item for over a given amount of time, 30s by default, a
566 warning message is printed along with dump of workqueue
567 state. This can be configured through kernel parameter
568 "workqueue.watchdog_thresh" and its sysfs counterpart.
570 config KERNEL_DEBUG_ATOMIC_SLEEP
571 bool "Compile the kernel with sleep inside atomic section checking"
572 depends on KERNEL_DEBUG_KERNEL
574 If you say Y here, various routines which may sleep will become very
575 noisy if they are called inside atomic sections: when a spinlock is
576 held, inside an rcu read side critical section, inside preempt disabled
577 sections, inside an interrupt, etc...
579 config KERNEL_DEBUG_VM
580 bool "Compile the kernel with debug VM"
581 depends on KERNEL_DEBUG_KERNEL
583 Enable this to turn on extended checks in the virtual-memory system
584 that may impact performance.
588 config KERNEL_PRINTK_TIME
589 bool "Enable printk timestamps"
592 config KERNEL_SLUB_DEBUG
595 config KERNEL_SLUB_DEBUG_ON
598 config KERNEL_SLABINFO
599 select KERNEL_SLUB_DEBUG
600 select KERNEL_SLUB_DEBUG_ON
601 bool "Enable /proc slab debug info"
603 config KERNEL_PROC_PAGE_MONITOR
604 bool "Enable /proc page monitoring"
610 bool "Enable kexec support"
612 config KERNEL_PROC_VMCORE
615 config KERNEL_PROC_KCORE
618 config KERNEL_CRASH_DUMP
619 depends on i386 || x86_64 || arm || armeb
621 select KERNEL_PROC_VMCORE
622 select KERNEL_PROC_KCORE
623 bool "Enable support for kexec crashdump"
627 bool "Enable rfkill support"
628 default RFKILL_SUPPORT
631 bool "Enable sparse check during kernel build"
634 config KERNEL_DEVTMPFS
635 bool "Compile the kernel with device tmpfs enabled"
638 devtmpfs is a simple, kernel-managed /dev filesystem. The kernel creates
639 devices nodes for all registered devices to simplify boot, but leaves more
640 complex tasks to userspace (e.g. udev).
644 config KERNEL_DEVTMPFS_MOUNT
645 bool "Automatically mount devtmpfs after root filesystem is mounted"
651 bool "Enable kernel access key retention support"
654 config KERNEL_PERSISTENT_KEYRINGS
655 bool "Enable kernel persistent keyrings"
656 depends on KERNEL_KEYS
659 config KERNEL_KEYS_REQUEST_CACHE
660 bool "Enable temporary caching of the last request_key() result"
661 depends on KERNEL_KEYS
664 config KERNEL_BIG_KEYS
665 bool "Enable large payload keys on kernel keyrings"
666 depends on KERNEL_KEYS
670 # CGROUP support symbols
673 config KERNEL_CGROUPS
674 bool "Enable kernel cgroups"
675 default y if !SMALL_FLASH
679 config KERNEL_CGROUP_DEBUG
680 bool "Example debug cgroup subsystem"
683 This option enables a simple cgroup subsystem that
684 exports useful debugging information about the cgroups
687 config KERNEL_FREEZER
690 config KERNEL_CGROUP_FREEZER
691 bool "legacy Freezer cgroup subsystem"
693 select KERNEL_FREEZER
695 Provides a way to freeze and unfreeze all tasks in a
697 (legacy cgroup1-only controller, in cgroup2 freezer
698 is integrated in the Memory controller)
700 config KERNEL_CGROUP_DEVICE
701 bool "legacy Device controller for cgroups"
704 Provides a cgroup implementing whitelists for devices which
705 a process in the cgroup can mknod or open.
706 (legacy cgroup1-only controller)
708 config KERNEL_CGROUP_HUGETLB
709 bool "HugeTLB controller"
711 select KERNEL_HUGETLB_PAGE
713 config KERNEL_CGROUP_PIDS
714 bool "PIDs cgroup subsystem"
717 Provides enforcement of process number limits in the scope of a
720 config KERNEL_CGROUP_RDMA
721 bool "RDMA controller for cgroups"
724 config KERNEL_CGROUP_BPF
725 bool "Support for eBPF programs attached to cgroups"
728 config KERNEL_CPUSETS
729 bool "Cpuset support"
732 This option will let you create and manage CPUSETs which
733 allow dynamically partitioning a system into sets of CPUs and
734 Memory Nodes and assigning tasks to run only within those sets.
735 This is primarily useful on large SMP or NUMA systems.
737 config KERNEL_PROC_PID_CPUSET
738 bool "Include legacy /proc/<pid>/cpuset file"
740 depends on KERNEL_CPUSETS
742 config KERNEL_CGROUP_CPUACCT
743 bool "Simple CPU accounting cgroup subsystem"
746 Provides a simple Resource Controller for monitoring the
747 total CPU consumed by the tasks in a cgroup.
749 config KERNEL_RESOURCE_COUNTERS
750 bool "Resource counters"
753 This option enables controller independent resource accounting
754 infrastructure that works with cgroups.
756 config KERNEL_MM_OWNER
758 default y if KERNEL_MEMCG
761 bool "Memory Resource Controller for Control Groups"
763 select KERNEL_FREEZER
764 depends on KERNEL_RESOURCE_COUNTERS || !LINUX_3_18
766 Provides a memory resource controller that manages both anonymous
767 memory and page cache. (See Documentation/cgroups/memory.txt)
769 Note that setting this option increases fixed memory overhead
770 associated with each page of memory in the system. By this,
771 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
772 usage tracking struct at boot. Total amount of this is printed out
775 Only enable when you're ok with these tradeoffs and really
776 sure you need the memory resource controller. Even when you enable
777 this, you can set "cgroup_disable=memory" at your boot option to
778 disable memory resource controller and you can avoid overheads
779 (but lose benefits of memory resource controller).
781 This config option also selects MM_OWNER config option, which
782 could in turn add some fork/exit overhead.
784 config KERNEL_MEMCG_SWAP
785 bool "Memory Resource Controller Swap Extension"
787 depends on KERNEL_MEMCG
789 Add swap management feature to memory resource controller. When you
790 enable this, you can limit mem+swap usage per cgroup. In other words,
791 when you disable this, memory resource controller has no cares to
792 usage of swap...a process can exhaust all of the swap. This extension
793 is useful when you want to avoid exhaustion swap but this itself
794 adds more overheads and consumes memory for remembering information.
795 Especially if you use 32bit system or small memory system, please
796 be careful about enabling this. When memory resource controller
797 is disabled by boot option, this will be automatically disabled and
798 there will be no overhead from this. Even when you set this config=y,
799 if boot option "swapaccount=0" is set, swap will not be accounted.
800 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
801 size is 4096bytes, 512k per 1Gbytes of swap.
803 config KERNEL_MEMCG_SWAP_ENABLED
804 bool "Memory Resource Controller Swap Extension enabled by default"
806 depends on KERNEL_MEMCG_SWAP
808 Memory Resource Controller Swap Extension comes with its price in
809 a bigger memory consumption. General purpose distribution kernels
810 which want to enable the feature but keep it disabled by default
811 and let the user enable it by swapaccount boot command line
812 parameter should have this option unselected.
814 Those who want to have the feature enabled by default should
815 select this option (if, for some reason, they need to disable it,
816 then swapaccount=0 does the trick).
819 config KERNEL_MEMCG_KMEM
820 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
822 depends on KERNEL_MEMCG
824 The Kernel Memory extension for Memory Resource Controller can limit
825 the amount of memory used by kernel objects in the system. Those are
826 fundamentally different from the entities handled by the standard
827 Memory Controller, which are page-based, and can be swapped. Users of
828 the kmem extension can use it to guarantee that no group of processes
829 will ever exhaust kernel resources alone.
831 config KERNEL_CGROUP_PERF
832 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
833 select KERNEL_PERF_EVENTS
836 This option extends the per-cpu mode to restrict monitoring to
837 threads which belong to the cgroup specified and run on the
840 menuconfig KERNEL_CGROUP_SCHED
841 bool "Group CPU scheduler"
844 This feature lets CPU scheduler recognize task groups and control CPU
845 bandwidth allocation to such task groups. It uses cgroups to group
848 if KERNEL_CGROUP_SCHED
850 config KERNEL_FAIR_GROUP_SCHED
851 bool "Group scheduling for SCHED_OTHER"
854 config KERNEL_CFS_BANDWIDTH
855 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
857 depends on KERNEL_FAIR_GROUP_SCHED
859 This option allows users to define CPU bandwidth rates (limits) for
860 tasks running within the fair group scheduler. Groups with no limit
861 set are considered to be unconstrained and will run with no
863 See tip/Documentation/scheduler/sched-bwc.txt for more information.
865 config KERNEL_RT_GROUP_SCHED
866 bool "Group scheduling for SCHED_RR/FIFO"
869 This feature lets you explicitly allocate real CPU bandwidth
870 to task groups. If enabled, it will also make it impossible to
871 schedule realtime tasks for non-root users until you allocate
872 realtime bandwidth for them.
876 config KERNEL_BLK_CGROUP
877 bool "Block IO controller"
880 Generic block IO controller cgroup interface. This is the common
881 cgroup interface which should be used by various IO controlling
884 Currently, CFQ IO scheduler uses it to recognize task groups and
885 control disk bandwidth allocation (proportional time slice allocation)
886 to such task groups. It is also used by bio throttling logic in
887 block layer to implement upper limit in IO rates on a device.
889 This option only enables generic Block IO controller infrastructure.
890 One needs to also enable actual IO controlling logic/policy. For
891 enabling proportional weight division of disk bandwidth in CFQ, set
892 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
893 CONFIG_BLK_DEV_THROTTLING=y.
897 config KERNEL_CFQ_GROUP_IOSCHED
898 bool "Proportional weight of disk bandwidth in CFQ"
900 config KERNEL_BLK_DEV_THROTTLING
901 bool "Enable throttling policy"
904 config KERNEL_BLK_DEV_THROTTLING_LOW
905 bool "Block throttling .low limit interface support (EXPERIMENTAL)"
906 depends on KERNEL_BLK_DEV_THROTTLING
909 config KERNEL_DEBUG_BLK_CGROUP
910 bool "Enable Block IO controller debugging"
912 depends on KERNEL_BLK_CGROUP
914 Enable some debugging help. Currently it exports additional stat
915 files in a cgroup which can be useful for debugging.
917 config KERNEL_NET_CLS_CGROUP
918 bool "legacy Control Group Classifier"
921 config KERNEL_CGROUP_NET_CLASSID
922 bool "legacy Network classid cgroup"
925 config KERNEL_CGROUP_NET_PRIO
926 bool "legacy Network priority cgroup"
932 # Namespace support symbols
935 config KERNEL_NAMESPACES
936 bool "Enable kernel namespaces"
937 default y if !SMALL_FLASH
945 In this namespace, tasks see different info provided
946 with the uname() system call.
952 In this namespace, tasks work with IPC ids which correspond to
953 different IPC objects in different namespaces.
955 config KERNEL_USER_NS
956 bool "User namespace (EXPERIMENTAL)"
959 This allows containers, i.e. vservers, to use user namespaces
960 to provide different user info for different servers.
963 bool "PID Namespaces"
966 Support process id namespaces. This allows having multiple
967 processes with the same pid as long as they are in different
968 pid namespaces. This is a building block of containers.
971 bool "Network namespace"
974 Allow user space to create what appear to be multiple instances
975 of the network stack.
979 config KERNEL_DEVPTS_MULTIPLE_INSTANCES
980 bool "Support multiple instances of devpts"
981 default y if !SMALL_FLASH
983 Enable support for multiple instances of devpts filesystem.
984 If you want to have isolated PTY namespaces (eg: in containers),
985 say Y here. Otherwise, say N. If enabled, each mount of devpts
986 filesystem with the '-o newinstance' option will create an
987 independent PTY namespace.
989 config KERNEL_POSIX_MQUEUE
990 bool "POSIX Message Queues"
991 default y if !SMALL_FLASH
993 POSIX variant of message queues is a part of IPC. In POSIX message
994 queues every message has a priority which decides about succession
995 of receiving it by a process. If you want to compile and run
996 programs written e.g. for Solaris with use of its POSIX message
997 queues (functions mq_*) say Y here.
999 POSIX message queues are visible as a filesystem called 'mqueue'
1000 and can be mounted somewhere if you want to do filesystem
1001 operations on message queues.
1004 config KERNEL_SECCOMP_FILTER
1006 default y if !SMALL_FLASH
1008 config KERNEL_SECCOMP
1009 bool "Enable seccomp support"
1010 depends on !(TARGET_uml)
1011 select KERNEL_SECCOMP_FILTER
1012 default y if !SMALL_FLASH
1014 Build kernel with support for seccomp.
1017 # IPv4 configuration
1020 config KERNEL_IP_MROUTE
1021 bool "Enable IPv4 multicast routing"
1024 Multicast routing requires a multicast routing daemon in
1025 addition to kernel support.
1029 config KERNEL_IP_MROUTE_MULTIPLE_TABLES
1032 config KERNEL_IP_PIMSM_V1
1035 config KERNEL_IP_PIMSM_V2
1041 # IPv6 configuration
1049 config KERNEL_IPV6_MULTIPLE_TABLES
1052 config KERNEL_IPV6_SUBTREES
1055 config KERNEL_IPV6_MROUTE
1056 bool "Enable IPv6 multicast routing"
1059 Multicast routing requires a multicast routing daemon in
1060 addition to kernel support.
1062 if KERNEL_IPV6_MROUTE
1064 config KERNEL_IPV6_MROUTE_MULTIPLE_TABLES
1067 config KERNEL_IPV6_PIMSM_V2
1072 config KERNEL_IPV6_SEG6_LWTUNNEL
1073 bool "Enable support for lightweight tunnels"
1074 default y if !SMALL_FLASH
1076 Using lwtunnel (needed for IPv6 segment routing) requires ip-full package.
1078 config KERNEL_LWTUNNEL_BPF
1084 # Miscellaneous network configuration
1087 config KERNEL_NET_L3_MASTER_DEV
1088 bool "L3 Master device support"
1090 This module provides glue between core networking code and device
1091 drivers to support L3 master devices like VRF.
1094 # NFS related symbols
1096 config KERNEL_IP_PNP
1097 bool "Compile the kernel with rootfs on NFS"
1099 If you want to make your kernel boot off a NFS server as root
1100 filesystem, select Y here.
1104 config KERNEL_IP_PNP_DHCP
1107 config KERNEL_IP_PNP_BOOTP
1110 config KERNEL_IP_PNP_RARP
1113 config KERNEL_NFS_FS
1116 config KERNEL_NFS_V2
1119 config KERNEL_NFS_V3
1122 config KERNEL_ROOT_NFS
1127 menu "Filesystem ACL and attr support options"
1128 config USE_FS_ACL_ATTR
1129 bool "Use filesystem ACL and attr support by default"
1132 Make using ACLs (e.g. POSIX ACL, NFSv4 ACL) the default
1133 for kernel and packages, except tmpfs, flash filesystems,
1134 and old NFS. Also enable userspace extended attribute support
1135 by default. (OpenWrt already has an expection it will be
1136 present in the kernel).
1138 config KERNEL_FS_POSIX_ACL
1139 bool "Enable POSIX ACL support"
1140 default y if USE_FS_ACL_ATTR
1142 config KERNEL_BTRFS_FS_POSIX_ACL
1143 bool "Enable POSIX ACL for BtrFS Filesystems"
1144 select KERNEL_FS_POSIX_ACL
1145 default y if USE_FS_ACL_ATTR
1147 config KERNEL_EXT4_FS_POSIX_ACL
1148 bool "Enable POSIX ACL for Ext4 Filesystems"
1149 select KERNEL_FS_POSIX_ACL
1150 default y if USE_FS_ACL_ATTR
1152 config KERNEL_F2FS_FS_POSIX_ACL
1153 bool "Enable POSIX ACL for F2FS Filesystems"
1154 select KERNEL_FS_POSIX_ACL
1157 config KERNEL_JFFS2_FS_POSIX_ACL
1158 bool "Enable POSIX ACL for JFFS2 Filesystems"
1159 select KERNEL_FS_POSIX_ACL
1162 config KERNEL_TMPFS_POSIX_ACL
1163 bool "Enable POSIX ACL for TMPFS Filesystems"
1164 select KERNEL_FS_POSIX_ACL
1167 config KERNEL_CIFS_ACL
1168 bool "Enable CIFS ACLs"
1169 select KERNEL_FS_POSIX_ACL
1170 default y if USE_FS_ACL_ATTR
1172 config KERNEL_HFS_FS_POSIX_ACL
1173 bool "Enable POSIX ACL for HFS Filesystems"
1174 select KERNEL_FS_POSIX_ACL
1175 default y if USE_FS_ACL_ATTR
1177 config KERNEL_HFSPLUS_FS_POSIX_ACL
1178 bool "Enable POSIX ACL for HFS+ Filesystems"
1179 select KERNEL_FS_POSIX_ACL
1180 default y if USE_FS_ACL_ATTR
1182 config KERNEL_NFS_ACL_SUPPORT
1183 bool "Enable ACLs for NFS"
1184 default y if USE_FS_ACL_ATTR
1186 config KERNEL_NFS_V3_ACL_SUPPORT
1187 bool "Enable ACLs for NFSv3"
1190 config KERNEL_NFSD_V2_ACL_SUPPORT
1191 bool "Enable ACLs for NFSDv2"
1194 config KERNEL_NFSD_V3_ACL_SUPPORT
1195 bool "Enable ACLs for NFSDv3"
1198 config KERNEL_REISER_FS_POSIX_ACL
1199 bool "Enable POSIX ACLs for ReiserFS"
1200 select KERNEL_FS_POSIX_ACL
1201 default y if USE_FS_ACL_ATTR
1203 config KERNEL_XFS_POSIX_ACL
1204 bool "Enable POSIX ACLs for XFS"
1205 select KERNEL_FS_POSIX_ACL
1206 default y if USE_FS_ACL_ATTR
1208 config KERNEL_JFS_POSIX_ACL
1209 bool "Enable POSIX ACLs for JFS"
1210 select KERNEL_FS_POSIX_ACL
1211 default y if USE_FS_ACL_ATTR
1215 config KERNEL_DEVMEM
1216 bool "/dev/mem virtual device support"
1218 Say Y here if you want to support the /dev/mem device.
1219 The /dev/mem device is used to access areas of physical
1222 config KERNEL_DEVKMEM
1223 bool "/dev/kmem virtual device support"
1225 Say Y here if you want to support the /dev/kmem device. The
1226 /dev/kmem device is rarely used, but can be used for certain
1227 kind of kernel debugging operations.
1229 config KERNEL_SQUASHFS_FRAGMENT_CACHE_SIZE
1230 int "Number of squashfs fragments cached"
1231 default 2 if (SMALL_FLASH && !LOW_MEMORY_FOOTPRINT)
1234 config KERNEL_SQUASHFS_XATTR
1235 bool "Squashfs XATTR support"
1238 # compile optimization setting
1241 prompt "Compiler optimization level"
1242 default KERNEL_CC_OPTIMIZE_FOR_SIZE if SMALL_FLASH
1244 config KERNEL_CC_OPTIMIZE_FOR_PERFORMANCE
1245 bool "Optimize for performance"
1247 This is the default optimization level for the kernel, building
1248 with the "-O2" compiler flag for best performance and most
1249 helpful compile-time warnings.
1251 config KERNEL_CC_OPTIMIZE_FOR_SIZE
1252 bool "Optimize for size"
1254 Enabling this option will pass "-Os" instead of "-O2" to
1255 your compiler resulting in a smaller kernel.
1260 bool "Auditing support"
1262 config KERNEL_SECURITY
1263 bool "Enable different security models"
1265 config KERNEL_SECURITY_NETWORK
1266 bool "Socket and Networking Security Hooks"
1267 select KERNEL_SECURITY
1269 config KERNEL_SECURITY_SELINUX
1270 bool "NSA SELinux Support"
1271 select KERNEL_SECURITY_NETWORK
1274 config KERNEL_SECURITY_SELINUX_BOOTPARAM
1275 bool "NSA SELinux boot parameter"
1276 depends on KERNEL_SECURITY_SELINUX
1279 config KERNEL_SECURITY_SELINUX_DISABLE
1280 bool "NSA SELinux runtime disable"
1281 depends on KERNEL_SECURITY_SELINUX
1283 config KERNEL_SECURITY_SELINUX_DEVELOP
1284 bool "NSA SELinux Development Support"
1285 depends on KERNEL_SECURITY_SELINUX
1288 config KERNEL_SECURITY_SELINUX_SIDTAB_HASH_BITS
1290 depends on KERNEL_SECURITY_SELINUX
1293 config KERNEL_SECURITY_SELINUX_SID2STR_CACHE_SIZE
1295 depends on KERNEL_SECURITY_SELINUX
1300 default "lockdown,yama,loadpin,safesetid,integrity,selinux"
1301 depends on KERNEL_SECURITY_SELINUX
1303 config KERNEL_EXT4_FS_SECURITY
1304 bool "Ext4 Security Labels"
1306 config KERNEL_F2FS_FS_SECURITY
1307 bool "F2FS Security Labels"
1309 config KERNEL_UBIFS_FS_SECURITY
1310 bool "UBIFS Security Labels"
1312 config KERNEL_JFFS2_FS_SECURITY
1313 bool "JFFS2 Security Labels"