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
50 depends on (arm || aarch64)
52 config KERNEL_X86_VSYSCALL_EMULATION
53 bool "Enable vsyscall emulation"
56 This enables emulation of the legacy vsyscall page. Disabling
57 it is roughly equivalent to booting with vsyscall=none, except
58 that it will also disable the helpful warning if a program
59 tries to use a vsyscall. With this option set to N, offending
60 programs will just segfault, citing addresses of the form
63 This option is required by many programs built before 2013, and
64 care should be used even with newer programs if set to N.
66 Disabling this option saves about 7K of kernel size and
67 possibly 4K of additional runtime pagetable memory.
69 config KERNEL_PERF_EVENTS
70 bool "Compile the kernel with performance events and counters"
71 select KERNEL_ARM_PMU if (arm || aarch64)
73 config KERNEL_PROFILING
74 bool "Compile the kernel with profiling enabled"
75 select KERNEL_PERF_EVENTS
77 Enable the extended profiling support mechanisms used by profilers such
80 config KERNEL_RPI_AXIPERF
81 bool "Compile the kernel with RaspberryPi AXI Performance monitors"
83 depends on KERNEL_PERF_EVENTS && TARGET_bcm27xx
86 bool "Compile the kernel with undefined behaviour sanity checker"
88 This option enables undefined behaviour sanity checker
89 Compile-time instrumentation is used to detect various undefined
90 behaviours in runtime. Various types of checks may be enabled
91 via boot parameter ubsan_handle
92 (see: Documentation/dev-tools/ubsan.rst).
94 config KERNEL_UBSAN_SANITIZE_ALL
95 bool "Enable instrumentation for the entire kernel"
96 depends on KERNEL_UBSAN
99 This option activates instrumentation for the entire kernel.
100 If you don't enable this option, you have to explicitly specify
101 UBSAN_SANITIZE := y for the files/directories you want to check for UB.
102 Enabling this option will get kernel image size increased
105 config KERNEL_UBSAN_ALIGNMENT
106 bool "Enable checking of pointers alignment"
107 depends on KERNEL_UBSAN
109 This option enables detection of unaligned memory accesses.
110 Enabling this option on architectures that support unaligned
111 accesses may produce a lot of false positives.
113 config KERNEL_UBSAN_BOUNDS
114 bool "Perform array index bounds checking"
115 depends on KERNEL_UBSAN
117 This option enables detection of directly indexed out of bounds array
118 accesses, where the array size is known at compile time. Note that
119 this does not protect array overflows via bad calls to the
120 {str,mem}*cpy() family of functions (that is addressed by
123 config KERNEL_UBSAN_NULL
124 bool "Enable checking of null pointers"
125 depends on KERNEL_UBSAN
127 This option enables detection of memory accesses via a
130 config KERNEL_UBSAN_TRAP
131 bool "On Sanitizer warnings, abort the running kernel code"
132 depends on KERNEL_UBSAN
134 Building kernels with Sanitizer features enabled tends to grow the
135 kernel size by around 5%, due to adding all the debugging text on
136 failure paths. To avoid this, Sanitizer instrumentation can just
137 issue a trap. This reduces the kernel size overhead but turns all
138 warnings (including potentially harmless conditions) into full
139 exceptions that abort the running kernel code (regardless of context,
140 locks held, etc), which may destabilize the system. For some system
141 builders this is an acceptable trade-off.
144 bool "Compile the kernel with KASan: runtime memory debugger"
145 select KERNEL_SLUB_DEBUG
146 depends on (x86_64 || aarch64)
148 Enables kernel address sanitizer - runtime memory debugger,
149 designed to find out-of-bounds accesses and use-after-free bugs.
150 This is strictly a debugging feature and it requires a gcc version
151 of 4.9.2 or later. Detection of out of bounds accesses to stack or
152 global variables requires gcc 5.0 or later.
153 This feature consumes about 1/8 of available memory and brings about
154 ~x3 performance slowdown.
155 For better error detection enable CONFIG_STACKTRACE.
156 Currently CONFIG_KASAN doesn't work with CONFIG_DEBUG_SLAB
157 (the resulting kernel does not boot).
159 config KERNEL_KASAN_EXTRA
160 bool "KAsan: extra checks"
161 depends on KERNEL_KASAN && KERNEL_DEBUG_KERNEL
163 This enables further checks in the kernel address sanitizer, for now
164 it only includes the address-use-after-scope check that can lead
165 to excessive kernel stack usage, frame size warnings and longer
167 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715 has more
169 config KERNEL_KASAN_VMALLOC
170 bool "Back mappings in vmalloc space with real shadow memory"
171 depends on KERNEL_KASAN
173 By default, the shadow region for vmalloc space is the read-only
174 zero page. This means that KASAN cannot detect errors involving
177 Enabling this option will hook in to vmap/vmalloc and back those
178 mappings with real shadow memory allocated on demand. This allows
179 for KASAN to detect more sorts of errors (and to support vmapped
180 stacks), but at the cost of higher memory usage.
182 This option depends on HAVE_ARCH_KASAN_VMALLOC, but we can't
183 depend on that in here, so it is possible that enabling this
187 config KERNEL_KASAN_GENERIC
190 config KERNEL_KASAN_SW_TAGS
195 prompt "Instrumentation type"
196 depends on KERNEL_KASAN
197 default KERNEL_KASAN_OUTLINE
199 config KERNEL_KASAN_OUTLINE
200 bool "Outline instrumentation"
202 Before every memory access compiler insert function call
203 __asan_load*/__asan_store*. These functions performs check
204 of shadow memory. This is slower than inline instrumentation,
205 however it doesn't bloat size of kernel's .text section so
208 config KERNEL_KASAN_INLINE
209 bool "Inline instrumentation"
211 Compiler directly inserts code checking shadow memory before
212 memory accesses. This is faster than outline (in some workloads
213 it gives about x2 boost over outline instrumentation), but
214 make kernel's .text size much bigger.
215 This requires a gcc version of 5.0 or later.
220 bool "Compile the kernel with code coverage for fuzzing"
221 select KERNEL_DEBUG_FS
223 KCOV exposes kernel code coverage information in a form suitable
224 for coverage-guided fuzzing (randomized testing).
226 If RANDOMIZE_BASE is enabled, PC values will not be stable across
227 different machines and across reboots. If you need stable PC values,
228 disable RANDOMIZE_BASE.
230 For more details, see Documentation/kcov.txt.
232 config KERNEL_KCOV_ENABLE_COMPARISONS
233 bool "Enable comparison operands collection by KCOV"
234 depends on KERNEL_KCOV
236 KCOV also exposes operands of every comparison in the instrumented
237 code along with operand sizes and PCs of the comparison instructions.
238 These operands can be used by fuzzing engines to improve the quality
241 config KERNEL_KCOV_INSTRUMENT_ALL
242 bool "Instrument all code by default"
243 depends on KERNEL_KCOV
244 default y if KERNEL_KCOV
246 If you are doing generic system call fuzzing (like e.g. syzkaller),
247 then you will want to instrument the whole kernel and you should
248 say y here. If you are doing more targeted fuzzing (like e.g.
249 filesystem fuzzing with AFL) then you will want to enable coverage
250 for more specific subsets of files, and should say n here.
252 config KERNEL_TASKSTATS
253 bool "Compile the kernel with task resource/io statistics and accounting"
255 Enable the collection and publishing of task/io statistics and
256 accounting. Enable this option to enable i/o monitoring in system
261 config KERNEL_TASK_DELAY_ACCT
264 config KERNEL_TASK_IO_ACCOUNTING
267 config KERNEL_TASK_XACCT
272 config KERNEL_KALLSYMS
273 bool "Compile the kernel with symbol table information"
274 default y if !SMALL_FLASH
276 This will give you more information in stack traces from kernel oopses.
279 bool "Compile the kernel with tracing support"
280 depends on !TARGET_uml
282 config KERNEL_FTRACE_SYSCALLS
283 bool "Trace system calls"
284 depends on KERNEL_FTRACE
286 config KERNEL_ENABLE_DEFAULT_TRACERS
287 bool "Trace process context switches and events"
288 depends on KERNEL_FTRACE
290 config KERNEL_FUNCTION_TRACER
291 bool "Function tracer"
292 depends on KERNEL_FTRACE
294 config KERNEL_FUNCTION_GRAPH_TRACER
295 bool "Function graph tracer"
296 depends on KERNEL_FUNCTION_TRACER
298 config KERNEL_DYNAMIC_FTRACE
299 bool "Enable/disable function tracing dynamically"
300 depends on KERNEL_FUNCTION_TRACER
302 config KERNEL_FUNCTION_PROFILER
303 bool "Function profiler"
304 depends on KERNEL_FUNCTION_TRACER
306 config KERNEL_IRQSOFF_TRACER
307 bool "Interrupts-off Latency Tracer"
308 depends on KERNEL_FTRACE
310 This option measures the time spent in irqs-off critical
311 sections, with microsecond accuracy.
313 The default measurement method is a maximum search, which is
314 disabled by default and can be runtime (re-)started
317 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
319 (Note that kernel size and overhead increase with this option
320 enabled. This option and the preempt-off timing option can be
321 used together or separately.)
323 config KERNEL_PREEMPT_TRACER
324 bool "Preemption-off Latency Tracer"
325 depends on KERNEL_FTRACE
327 This option measures the time spent in preemption-off critical
328 sections, with microsecond accuracy.
330 The default measurement method is a maximum search, which is
331 disabled by default and can be runtime (re-)started
334 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
336 (Note that kernel size and overhead increase with this option
337 enabled. This option and the irqs-off timing option can be
338 used together or separately.)
340 config KERNEL_HIST_TRIGGERS
341 bool "Histogram triggers"
342 depends on KERNEL_FTRACE
344 Hist triggers allow one or more arbitrary trace event fields to be
345 aggregated into hash tables and dumped to stdout by reading a
346 debugfs/tracefs file. They're useful for gathering quick and dirty
347 (though precise) summaries of event activity as an initial guide for
348 further investigation using more advanced tools.
350 Inter-event tracing of quantities such as latencies is also
351 supported using hist triggers under this option.
353 config KERNEL_DEBUG_KERNEL
356 config KERNEL_DEBUG_INFO
357 bool "Compile the kernel with debug information"
358 default y if !SMALL_FLASH
359 select KERNEL_DEBUG_KERNEL
361 This will compile your kernel and modules with debug information.
363 config KERNEL_DEBUG_INFO_BTF
365 bool "Enable additional BTF type information"
366 depends on !HOST_OS_MACOS
367 depends on KERNEL_DEBUG_INFO && !KERNEL_DEBUG_INFO_REDUCED
370 Generate BPF Type Format (BTF) information from DWARF debug info.
371 Turning this on expects presence of pahole tool, which will convert
372 DWARF type info into equivalent deduplicated BTF type info.
374 Required to run BPF CO-RE applications.
376 config KERNEL_MODULE_ALLOW_BTF_MISMATCH
377 bool "Allow loading modules with non-matching BTF type info"
378 depends on KERNEL_DEBUG_INFO_BTF
380 For modules whose split BTF does not match vmlinux, load without
381 BTF rather than refusing to load. The default behavior with
382 module BTF enabled is to reject modules with such mismatches;
383 this option will still load module BTF where possible but ignore
384 it when a mismatch is found.
386 config KERNEL_DEBUG_INFO_REDUCED
387 bool "Reduce debugging information"
389 depends on KERNEL_DEBUG_INFO
391 If you say Y here gcc is instructed to generate less debugging
392 information for structure types. This means that tools that
393 need full debugging information (like kgdb or systemtap) won't
394 be happy. But if you merely need debugging information to
395 resolve line numbers there is no loss. Advantage is that
396 build directory object sizes shrink dramatically over a full
397 DEBUG_INFO build and compile times are reduced too.
398 Only works with newer gcc versions.
400 config KERNEL_FRAME_WARN
403 default 1280 if KERNEL_KASAN && !ARCH_64BIT
404 default 1024 if !ARCH_64BIT
405 default 2048 if ARCH_64BIT
407 Tell the compiler to warn at build time for stack frames larger than this.
408 Setting this too low will cause a lot of warnings.
409 Setting it to 0 disables the warning.
411 # KERNEL_DEBUG_LL symbols must have the default value set as otherwise
412 # KConfig wont evaluate them unless KERNEL_EARLY_PRINTK is selected
413 # which means that buildroot wont override the DEBUG_LL symbols in target
414 # kernel configurations and lead to devices that dont have working console
415 config KERNEL_DEBUG_LL_UART_NONE
420 config KERNEL_DEBUG_LL
424 select KERNEL_DEBUG_LL_UART_NONE
426 ARM low level debugging.
428 config KERNEL_DEBUG_VIRTUAL
429 bool "Compile the kernel with VM translations debugging"
430 select KERNEL_DEBUG_KERNEL
432 Enable checks sanity checks to catch invalid uses of
433 virt_to_phys()/phys_to_virt() against the non-linear address space.
435 config KERNEL_DYNAMIC_DEBUG
436 bool "Compile the kernel with dynamic printk"
437 select KERNEL_DEBUG_FS
439 Compiles debug level messages into the kernel, which would not
440 otherwise be available at runtime. These messages can then be
441 enabled/disabled based on various levels of scope - per source file,
442 function, module, format string, and line number. This mechanism
443 implicitly compiles in all pr_debug() and dev_dbg() calls, which
444 enlarges the kernel text size by about 2%.
446 config KERNEL_EARLY_PRINTK
447 bool "Compile the kernel with early printk"
448 default y if TARGET_bcm53xx
450 select KERNEL_DEBUG_KERNEL
451 select KERNEL_DEBUG_LL if arm
453 Compile the kernel with early printk support. This is only useful for
454 debugging purposes to send messages over the serial console in early boot.
455 Enable this to debug early boot problems.
457 config KERNEL_KPROBES
458 bool "Compile the kernel with kprobes support"
460 select KERNEL_PERF_EVENTS
462 Compiles the kernel with KPROBES support, which allows you to trap
463 at almost any kernel address and execute a callback function.
464 register_kprobe() establishes a probepoint and specifies the
465 callback. Kprobes is useful for kernel debugging, non-intrusive
466 instrumentation and testing.
467 If in doubt, say "N".
469 config KERNEL_KPROBE_EVENTS
471 default y if KERNEL_KPROBES
473 config KERNEL_BPF_EVENTS
474 bool "Compile the kernel with BPF event support"
475 select KERNEL_KPROBES
477 Allows to attach BPF programs to kprobe, uprobe and tracepoint events.
478 This is required to use BPF maps of type BPF_MAP_TYPE_PERF_EVENT_ARRAY
479 for sending data from BPF programs to user-space for post-processing
482 config KERNEL_BPF_KPROBE_OVERRIDE
484 depends on KERNEL_KPROBES
488 bool "Compile the kernel with asynchronous IO support"
489 default y if !SMALL_FLASH
491 config KERNEL_IO_URING
492 bool "Compile the kernel with io_uring support"
493 depends on !SMALL_FLASH
494 default y if (x86_64 || aarch64)
496 config KERNEL_FHANDLE
497 bool "Compile the kernel with support for fhandle syscalls"
498 default y if !SMALL_FLASH
500 config KERNEL_FANOTIFY
501 bool "Compile the kernel with modern file notification support"
502 default y if !SMALL_FLASH
504 config KERNEL_BLK_DEV_BSG
505 bool "Compile the kernel with SCSI generic v4 support for any block device"
507 config KERNEL_TRANSPARENT_HUGEPAGE
511 prompt "Transparent Hugepage Support sysfs defaults"
512 depends on KERNEL_TRANSPARENT_HUGEPAGE
513 default KERNEL_TRANSPARENT_HUGEPAGE_ALWAYS
515 config KERNEL_TRANSPARENT_HUGEPAGE_ALWAYS
518 config KERNEL_TRANSPARENT_HUGEPAGE_MADVISE
522 config KERNEL_HUGETLBFS
525 config KERNEL_HUGETLB_PAGE
526 bool "Compile the kernel with HugeTLB support"
527 select KERNEL_TRANSPARENT_HUGEPAGE
528 select KERNEL_HUGETLBFS
530 config KERNEL_MAGIC_SYSRQ
531 bool "Compile the kernel with SysRq support"
534 config KERNEL_DEBUG_PINCTRL
535 bool "Compile the kernel with pinctrl debugging"
536 select KERNEL_DEBUG_KERNEL
538 config KERNEL_DEBUG_GPIO
539 bool "Compile the kernel with gpio debugging"
540 select KERNEL_DEBUG_KERNEL
542 config KERNEL_COREDUMP
545 config KERNEL_ELF_CORE
546 bool "Enable process core dump support"
547 select KERNEL_COREDUMP
548 default y if !SMALL_FLASH
550 config KERNEL_PROVE_LOCKING
551 bool "Enable kernel lock checking"
552 select KERNEL_DEBUG_KERNEL
554 config KERNEL_SOFTLOCKUP_DETECTOR
555 bool "Compile the kernel with detect Soft Lockups"
556 depends on KERNEL_DEBUG_KERNEL
558 Say Y here to enable the kernel to act as a watchdog to detect
561 Softlockups are bugs that cause the kernel to loop in kernel
562 mode for more than 20 seconds, without giving other tasks a
563 chance to run. The current stack trace is displayed upon
564 detection and the system will stay locked up.
566 config KERNEL_HARDLOCKUP_DETECTOR
567 bool "Compile the kernel with detect Hard Lockups"
568 depends on KERNEL_DEBUG_KERNEL
570 Say Y here to enable the kernel to act as a watchdog to detect
573 Hardlockups are bugs that cause the CPU to loop in kernel mode
574 for more than 10 seconds, without letting other interrupts have a
575 chance to run. The current stack trace is displayed upon detection
576 and the system will stay locked up.
578 config KERNEL_DETECT_HUNG_TASK
579 bool "Compile the kernel with detect Hung Tasks"
580 depends on KERNEL_DEBUG_KERNEL
581 default KERNEL_SOFTLOCKUP_DETECTOR
583 Say Y here to enable the kernel to detect "hung tasks",
584 which are bugs that cause the task to be stuck in
585 uninterruptible "D" state indefinitely.
587 When a hung task is detected, the kernel will print the
588 current stack trace (which you should report), but the
589 task will stay in uninterruptible state. If lockdep is
590 enabled then all held locks will also be reported. This
591 feature has negligible overhead.
593 config KERNEL_WQ_WATCHDOG
594 bool "Compile the kernel with detect Workqueue Stalls"
595 depends on KERNEL_DEBUG_KERNEL
597 Say Y here to enable stall detection on workqueues. If a
598 worker pool doesn't make forward progress on a pending work
599 item for over a given amount of time, 30s by default, a
600 warning message is printed along with dump of workqueue
601 state. This can be configured through kernel parameter
602 "workqueue.watchdog_thresh" and its sysfs counterpart.
604 config KERNEL_DEBUG_ATOMIC_SLEEP
605 bool "Compile the kernel with sleep inside atomic section checking"
606 depends on KERNEL_DEBUG_KERNEL
608 If you say Y here, various routines which may sleep will become very
609 noisy if they are called inside atomic sections: when a spinlock is
610 held, inside an rcu read side critical section, inside preempt disabled
611 sections, inside an interrupt, etc...
613 config KERNEL_DEBUG_VM
614 bool "Compile the kernel with debug VM"
615 depends on KERNEL_DEBUG_KERNEL
617 Enable this to turn on extended checks in the virtual-memory system
618 that may impact performance.
622 config KERNEL_PRINTK_TIME
623 bool "Enable printk timestamps"
626 config KERNEL_SLUB_DEBUG
629 config KERNEL_SLUB_DEBUG_ON
632 config KERNEL_SLABINFO
633 select KERNEL_SLUB_DEBUG
634 select KERNEL_SLUB_DEBUG_ON
635 bool "Enable /proc slab debug info"
637 config KERNEL_PROC_PAGE_MONITOR
638 bool "Enable /proc page monitoring"
644 bool "Enable kexec support"
646 config KERNEL_PROC_VMCORE
649 config KERNEL_PROC_KCORE
652 config KERNEL_CRASH_DUMP
653 depends on i386 || x86_64 || arm || armeb
655 select KERNEL_PROC_VMCORE
656 select KERNEL_PROC_KCORE
657 bool "Enable support for kexec crashdump"
661 bool "Enable rfkill support"
662 default RFKILL_SUPPORT
665 bool "Enable sparse check during kernel build"
667 config KERNEL_DEVTMPFS
668 bool "Compile the kernel with device tmpfs enabled"
670 devtmpfs is a simple, kernel-managed /dev filesystem. The kernel creates
671 devices nodes for all registered devices to simplify boot, but leaves more
672 complex tasks to userspace (e.g. udev).
676 config KERNEL_DEVTMPFS_MOUNT
677 bool "Automatically mount devtmpfs after root filesystem is mounted"
682 bool "Enable kernel access key retention support"
685 config KERNEL_PERSISTENT_KEYRINGS
686 bool "Enable kernel persistent keyrings"
687 depends on KERNEL_KEYS
689 config KERNEL_KEYS_REQUEST_CACHE
690 bool "Enable temporary caching of the last request_key() result"
691 depends on KERNEL_KEYS
693 config KERNEL_BIG_KEYS
694 bool "Enable large payload keys on kernel keyrings"
695 depends on KERNEL_KEYS
698 # CGROUP support symbols
701 config KERNEL_CGROUPS
702 bool "Enable kernel cgroups"
703 default y if !SMALL_FLASH
707 config KERNEL_CGROUP_DEBUG
708 bool "Example debug cgroup subsystem"
710 This option enables a simple cgroup subsystem that
711 exports useful debugging information about the cgroups
714 config KERNEL_FREEZER
717 config KERNEL_CGROUP_FREEZER
718 bool "legacy Freezer cgroup subsystem"
719 select KERNEL_FREEZER
721 Provides a way to freeze and unfreeze all tasks in a
723 (legacy cgroup1-only controller, in cgroup2 freezer
724 is integrated in the Memory controller)
726 config KERNEL_CGROUP_DEVICE
727 bool "legacy Device controller for cgroups"
729 Provides a cgroup implementing whitelists for devices which
730 a process in the cgroup can mknod or open.
731 (legacy cgroup1-only controller)
733 config KERNEL_CGROUP_HUGETLB
734 bool "HugeTLB controller"
735 select KERNEL_HUGETLB_PAGE
737 config KERNEL_CGROUP_PIDS
738 bool "PIDs cgroup subsystem"
741 Provides enforcement of process number limits in the scope of a
744 config KERNEL_CGROUP_RDMA
745 bool "RDMA controller for cgroups"
748 config KERNEL_CGROUP_BPF
749 bool "Support for eBPF programs attached to cgroups"
752 config KERNEL_CPUSETS
753 bool "Cpuset support"
756 This option will let you create and manage CPUSETs which
757 allow dynamically partitioning a system into sets of CPUs and
758 Memory Nodes and assigning tasks to run only within those sets.
759 This is primarily useful on large SMP or NUMA systems.
761 config KERNEL_PROC_PID_CPUSET
762 bool "Include legacy /proc/<pid>/cpuset file"
763 depends on KERNEL_CPUSETS
765 config KERNEL_CGROUP_CPUACCT
766 bool "Simple CPU accounting cgroup subsystem"
769 Provides a simple Resource Controller for monitoring the
770 total CPU consumed by the tasks in a cgroup.
772 config KERNEL_RESOURCE_COUNTERS
773 bool "Resource counters"
776 This option enables controller independent resource accounting
777 infrastructure that works with cgroups.
779 config KERNEL_MM_OWNER
781 default y if KERNEL_MEMCG
784 bool "Memory Resource Controller for Control Groups"
786 select KERNEL_FREEZER
787 depends on KERNEL_RESOURCE_COUNTERS
789 Provides a memory resource controller that manages both anonymous
790 memory and page cache. (See Documentation/cgroups/memory.txt)
792 Note that setting this option increases fixed memory overhead
793 associated with each page of memory in the system. By this,
794 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
795 usage tracking struct at boot. Total amount of this is printed out
798 Only enable when you're ok with these tradeoffs and really
799 sure you need the memory resource controller. Even when you enable
800 this, you can set "cgroup_disable=memory" at your boot option to
801 disable memory resource controller and you can avoid overheads
802 (but lose benefits of memory resource controller).
804 This config option also selects MM_OWNER config option, which
805 could in turn add some fork/exit overhead.
807 config KERNEL_MEMCG_SWAP
808 bool "Memory Resource Controller Swap Extension"
810 depends on KERNEL_MEMCG
812 Add swap management feature to memory resource controller. When you
813 enable this, you can limit mem+swap usage per cgroup. In other words,
814 when you disable this, memory resource controller has no cares to
815 usage of swap...a process can exhaust all of the swap. This extension
816 is useful when you want to avoid exhaustion swap but this itself
817 adds more overheads and consumes memory for remembering information.
818 Especially if you use 32bit system or small memory system, please
819 be careful about enabling this. When memory resource controller
820 is disabled by boot option, this will be automatically disabled and
821 there will be no overhead from this. Even when you set this config=y,
822 if boot option "swapaccount=0" is set, swap will not be accounted.
823 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
824 size is 4096bytes, 512k per 1Gbytes of swap.
826 config KERNEL_MEMCG_SWAP_ENABLED
827 bool "Memory Resource Controller Swap Extension enabled by default"
828 depends on KERNEL_MEMCG_SWAP
830 Memory Resource Controller Swap Extension comes with its price in
831 a bigger memory consumption. General purpose distribution kernels
832 which want to enable the feature but keep it disabled by default
833 and let the user enable it by swapaccount boot command line
834 parameter should have this option unselected.
836 Those who want to have the feature enabled by default should
837 select this option (if, for some reason, they need to disable it,
838 then swapaccount=0 does the trick).
841 config KERNEL_MEMCG_KMEM
842 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
844 depends on KERNEL_MEMCG
846 The Kernel Memory extension for Memory Resource Controller can limit
847 the amount of memory used by kernel objects in the system. Those are
848 fundamentally different from the entities handled by the standard
849 Memory Controller, which are page-based, and can be swapped. Users of
850 the kmem extension can use it to guarantee that no group of processes
851 will ever exhaust kernel resources alone.
853 config KERNEL_CGROUP_PERF
854 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
855 select KERNEL_PERF_EVENTS
857 This option extends the per-cpu mode to restrict monitoring to
858 threads which belong to the cgroup specified and run on the
861 menuconfig KERNEL_CGROUP_SCHED
862 bool "Group CPU scheduler"
865 This feature lets CPU scheduler recognize task groups and control CPU
866 bandwidth allocation to such task groups. It uses cgroups to group
869 if KERNEL_CGROUP_SCHED
871 config KERNEL_FAIR_GROUP_SCHED
872 bool "Group scheduling for SCHED_OTHER"
875 config KERNEL_CFS_BANDWIDTH
876 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
878 depends on KERNEL_FAIR_GROUP_SCHED
880 This option allows users to define CPU bandwidth rates (limits) for
881 tasks running within the fair group scheduler. Groups with no limit
882 set are considered to be unconstrained and will run with no
884 See tip/Documentation/scheduler/sched-bwc.txt for more information.
886 config KERNEL_RT_GROUP_SCHED
887 bool "Group scheduling for SCHED_RR/FIFO"
890 This feature lets you explicitly allocate real CPU bandwidth
891 to task groups. If enabled, it will also make it impossible to
892 schedule realtime tasks for non-root users until you allocate
893 realtime bandwidth for them.
897 config KERNEL_BLK_CGROUP
898 bool "Block IO controller"
901 Generic block IO controller cgroup interface. This is the common
902 cgroup interface which should be used by various IO controlling
905 Currently, CFQ IO scheduler uses it to recognize task groups and
906 control disk bandwidth allocation (proportional time slice allocation)
907 to such task groups. It is also used by bio throttling logic in
908 block layer to implement upper limit in IO rates on a device.
910 This option only enables generic Block IO controller infrastructure.
911 One needs to also enable actual IO controlling logic/policy. For
912 enabling proportional weight division of disk bandwidth in CFQ, set
913 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
914 CONFIG_BLK_DEV_THROTTLING=y.
918 config KERNEL_CFQ_GROUP_IOSCHED
919 bool "Proportional weight of disk bandwidth in CFQ"
921 config KERNEL_BLK_DEV_THROTTLING
922 bool "Enable throttling policy"
925 config KERNEL_BLK_DEV_THROTTLING_LOW
926 bool "Block throttling .low limit interface support (EXPERIMENTAL)"
927 depends on KERNEL_BLK_DEV_THROTTLING
930 config KERNEL_DEBUG_BLK_CGROUP
931 bool "Enable Block IO controller debugging"
932 depends on KERNEL_BLK_CGROUP
934 Enable some debugging help. Currently it exports additional stat
935 files in a cgroup which can be useful for debugging.
937 config KERNEL_NET_CLS_CGROUP
938 bool "legacy Control Group Classifier"
940 config KERNEL_CGROUP_NET_CLASSID
941 bool "legacy Network classid cgroup"
943 config KERNEL_CGROUP_NET_PRIO
944 bool "legacy Network priority cgroup"
949 # Namespace support symbols
952 config KERNEL_NAMESPACES
953 bool "Enable kernel namespaces"
954 default y if !SMALL_FLASH
962 In this namespace, tasks see different info provided
963 with the uname() system call.
969 In this namespace, tasks work with IPC ids which correspond to
970 different IPC objects in different namespaces.
972 config KERNEL_USER_NS
973 bool "User namespace (EXPERIMENTAL)"
976 This allows containers, i.e. vservers, to use user namespaces
977 to provide different user info for different servers.
980 bool "PID Namespaces"
983 Support process id namespaces. This allows having multiple
984 processes with the same pid as long as they are in different
985 pid namespaces. This is a building block of containers.
988 bool "Network namespace"
991 Allow user space to create what appear to be multiple instances
992 of the network stack.
996 config KERNEL_DEVPTS_MULTIPLE_INSTANCES
997 bool "Support multiple instances of devpts"
998 default y if !SMALL_FLASH
1000 Enable support for multiple instances of devpts filesystem.
1001 If you want to have isolated PTY namespaces (eg: in containers),
1002 say Y here. Otherwise, say N. If enabled, each mount of devpts
1003 filesystem with the '-o newinstance' option will create an
1004 independent PTY namespace.
1006 config KERNEL_POSIX_MQUEUE
1007 bool "POSIX Message Queues"
1008 default y if !SMALL_FLASH
1010 POSIX variant of message queues is a part of IPC. In POSIX message
1011 queues every message has a priority which decides about succession
1012 of receiving it by a process. If you want to compile and run
1013 programs written e.g. for Solaris with use of its POSIX message
1014 queues (functions mq_*) say Y here.
1016 POSIX message queues are visible as a filesystem called 'mqueue'
1017 and can be mounted somewhere if you want to do filesystem
1018 operations on message queues.
1021 config KERNEL_SECCOMP_FILTER
1023 default y if !SMALL_FLASH
1025 config KERNEL_SECCOMP
1026 bool "Enable seccomp support"
1027 depends on !(TARGET_uml)
1028 select KERNEL_SECCOMP_FILTER
1029 default y if !SMALL_FLASH
1031 Build kernel with support for seccomp.
1034 # IPv4 configuration
1037 config KERNEL_IP_MROUTE
1038 bool "Enable IPv4 multicast routing"
1041 Multicast routing requires a multicast routing daemon in
1042 addition to kernel support.
1046 config KERNEL_IP_MROUTE_MULTIPLE_TABLES
1049 config KERNEL_IP_PIMSM_V1
1052 config KERNEL_IP_PIMSM_V2
1058 # IPv6 configuration
1066 config KERNEL_IPV6_MULTIPLE_TABLES
1069 config KERNEL_IPV6_SUBTREES
1072 config KERNEL_IPV6_MROUTE
1073 bool "Enable IPv6 multicast routing"
1076 Multicast routing requires a multicast routing daemon in
1077 addition to kernel support.
1079 if KERNEL_IPV6_MROUTE
1081 config KERNEL_IPV6_MROUTE_MULTIPLE_TABLES
1084 config KERNEL_IPV6_PIMSM_V2
1089 config KERNEL_IPV6_SEG6_LWTUNNEL
1090 bool "Enable support for lightweight tunnels"
1091 default y if !SMALL_FLASH
1093 Using lwtunnel (needed for IPv6 segment routing) requires ip-full package.
1095 config KERNEL_LWTUNNEL_BPF
1101 # Miscellaneous network configuration
1104 config KERNEL_NET_L3_MASTER_DEV
1105 bool "L3 Master device support"
1107 This module provides glue between core networking code and device
1108 drivers to support L3 master devices like VRF.
1110 config KERNEL_XDP_SOCKETS
1111 bool "XDP sockets support"
1113 XDP sockets allows a channel between XDP programs and
1114 userspace applications.
1116 config KERNEL_WIRELESS_EXT
1119 config KERNEL_WEXT_CORE
1120 def_bool KERNEL_WIRELESS_EXT
1122 config KERNEL_WEXT_PRIV
1123 def_bool KERNEL_WIRELESS_EXT
1125 config KERNEL_WEXT_PROC
1126 def_bool KERNEL_WIRELESS_EXT
1128 config KERNEL_WEXT_SPY
1129 def_bool KERNEL_WIRELESS_EXT
1131 config KERNEL_PAGE_POOL
1134 config KERNEL_PAGE_POOL_STATS
1135 bool "Page pool stats support"
1136 depends on KERNEL_PAGE_POOL
1139 # NFS related symbols
1141 config KERNEL_IP_PNP
1142 bool "Compile the kernel with rootfs on NFS"
1144 If you want to make your kernel boot off a NFS server as root
1145 filesystem, select Y here.
1149 config KERNEL_IP_PNP_DHCP
1152 config KERNEL_IP_PNP_BOOTP
1155 config KERNEL_IP_PNP_RARP
1158 config KERNEL_NFS_FS
1161 config KERNEL_NFS_V2
1164 config KERNEL_NFS_V3
1167 config KERNEL_ROOT_NFS
1172 menu "Filesystem ACL and attr support options"
1173 config USE_FS_ACL_ATTR
1174 bool "Use filesystem ACL and attr support by default"
1176 Make using ACLs (e.g. POSIX ACL, NFSv4 ACL) the default
1177 for kernel and packages, except tmpfs, flash filesystems,
1178 and old NFS. Also enable userspace extended attribute support
1179 by default. (OpenWrt already has an expection it will be
1180 present in the kernel).
1182 config KERNEL_FS_POSIX_ACL
1183 bool "Enable POSIX ACL support"
1184 default y if USE_FS_ACL_ATTR
1186 config KERNEL_BTRFS_FS_POSIX_ACL
1187 bool "Enable POSIX ACL for BtrFS Filesystems"
1188 select KERNEL_FS_POSIX_ACL
1189 default y if USE_FS_ACL_ATTR
1191 config KERNEL_EXT4_FS_POSIX_ACL
1192 bool "Enable POSIX ACL for Ext4 Filesystems"
1193 select KERNEL_FS_POSIX_ACL
1194 default y if USE_FS_ACL_ATTR
1196 config KERNEL_F2FS_FS_POSIX_ACL
1197 bool "Enable POSIX ACL for F2FS Filesystems"
1198 select KERNEL_FS_POSIX_ACL
1200 config KERNEL_JFFS2_FS_POSIX_ACL
1201 bool "Enable POSIX ACL for JFFS2 Filesystems"
1202 select KERNEL_FS_POSIX_ACL
1204 config KERNEL_TMPFS_POSIX_ACL
1205 bool "Enable POSIX ACL for TMPFS Filesystems"
1206 select KERNEL_FS_POSIX_ACL
1208 config KERNEL_CIFS_ACL
1209 bool "Enable CIFS ACLs"
1210 select KERNEL_FS_POSIX_ACL
1211 default y if USE_FS_ACL_ATTR
1213 config KERNEL_HFS_FS_POSIX_ACL
1214 bool "Enable POSIX ACL for HFS Filesystems"
1215 select KERNEL_FS_POSIX_ACL
1216 default y if USE_FS_ACL_ATTR
1218 config KERNEL_HFSPLUS_FS_POSIX_ACL
1219 bool "Enable POSIX ACL for HFS+ Filesystems"
1220 select KERNEL_FS_POSIX_ACL
1221 default y if USE_FS_ACL_ATTR
1223 config KERNEL_NFS_ACL_SUPPORT
1224 bool "Enable ACLs for NFS"
1225 default y if USE_FS_ACL_ATTR
1227 config KERNEL_NFS_V3_ACL_SUPPORT
1228 bool "Enable ACLs for NFSv3"
1230 config KERNEL_NFSD_V2_ACL_SUPPORT
1231 bool "Enable ACLs for NFSDv2"
1233 config KERNEL_NFSD_V3_ACL_SUPPORT
1234 bool "Enable ACLs for NFSDv3"
1236 config KERNEL_REISER_FS_POSIX_ACL
1237 bool "Enable POSIX ACLs for ReiserFS"
1238 select KERNEL_FS_POSIX_ACL
1239 default y if USE_FS_ACL_ATTR
1241 config KERNEL_XFS_POSIX_ACL
1242 bool "Enable POSIX ACLs for XFS"
1243 select KERNEL_FS_POSIX_ACL
1244 default y if USE_FS_ACL_ATTR
1246 config KERNEL_JFS_POSIX_ACL
1247 bool "Enable POSIX ACLs for JFS"
1248 select KERNEL_FS_POSIX_ACL
1249 default y if USE_FS_ACL_ATTR
1253 config KERNEL_DEVMEM
1254 bool "/dev/mem virtual device support"
1256 Say Y here if you want to support the /dev/mem device.
1257 The /dev/mem device is used to access areas of physical
1260 config KERNEL_DEVKMEM
1261 bool "/dev/kmem virtual device support"
1263 Say Y here if you want to support the /dev/kmem device. The
1264 /dev/kmem device is rarely used, but can be used for certain
1265 kind of kernel debugging operations.
1267 config KERNEL_SQUASHFS_FRAGMENT_CACHE_SIZE
1268 int "Number of squashfs fragments cached"
1269 default 2 if (SMALL_FLASH && !LOW_MEMORY_FOOTPRINT)
1272 config KERNEL_SQUASHFS_XATTR
1273 bool "Squashfs XATTR support"
1276 # compile optimization setting
1279 prompt "Compiler optimization level"
1280 default KERNEL_CC_OPTIMIZE_FOR_SIZE if SMALL_FLASH
1282 config KERNEL_CC_OPTIMIZE_FOR_PERFORMANCE
1283 bool "Optimize for performance"
1285 This is the default optimization level for the kernel, building
1286 with the "-O2" compiler flag for best performance and most
1287 helpful compile-time warnings.
1289 config KERNEL_CC_OPTIMIZE_FOR_SIZE
1290 bool "Optimize for size"
1292 Enabling this option will pass "-Os" instead of "-O2" to
1293 your compiler resulting in a smaller kernel.
1298 bool "Auditing support"
1300 config KERNEL_SECURITY
1301 bool "Enable different security models"
1303 config KERNEL_SECURITY_NETWORK
1304 bool "Socket and Networking Security Hooks"
1305 select KERNEL_SECURITY
1307 config KERNEL_SECURITY_SELINUX
1308 bool "NSA SELinux Support"
1309 select KERNEL_SECURITY_NETWORK
1312 config KERNEL_SECURITY_SELINUX_BOOTPARAM
1313 bool "NSA SELinux boot parameter"
1314 depends on KERNEL_SECURITY_SELINUX
1317 config KERNEL_SECURITY_SELINUX_DISABLE
1318 bool "NSA SELinux runtime disable"
1319 depends on KERNEL_SECURITY_SELINUX
1321 config KERNEL_SECURITY_SELINUX_DEVELOP
1322 bool "NSA SELinux Development Support"
1323 depends on KERNEL_SECURITY_SELINUX
1326 config KERNEL_SECURITY_SELINUX_SIDTAB_HASH_BITS
1328 depends on KERNEL_SECURITY_SELINUX
1331 config KERNEL_SECURITY_SELINUX_SID2STR_CACHE_SIZE
1333 depends on KERNEL_SECURITY_SELINUX
1338 default "lockdown,yama,loadpin,safesetid,integrity,selinux"
1339 depends on KERNEL_SECURITY_SELINUX
1341 config KERNEL_EXT4_FS_SECURITY
1342 bool "Ext4 Security Labels"
1344 config KERNEL_F2FS_FS_SECURITY
1345 bool "F2FS Security Labels"
1347 config KERNEL_UBIFS_FS_SECURITY
1348 bool "UBIFS Security Labels"
1350 config KERNEL_JFFS2_FS_SECURITY
1351 bool "JFFS2 Security Labels"
1353 config KERNEL_WERROR
1354 bool "Compile the kernel with warnings as errors"
1356 default y if GCC_USE_VERSION_12
1358 A kernel build should not cause any compiler warnings, and this
1359 enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags
1360 to enforce that rule by default. Certain warnings from other tools
1361 such as the linker may be upgraded to errors with this option as
1364 However, if you have a new (or very old) compiler or linker with odd
1365 and unusual warnings, or you have some architecture with problems,
1366 you may need to disable this config option in order to
1367 successfully build the kernel.