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_DEBUG_INFO_REDUCED
377 bool "Reduce debugging information"
379 depends on KERNEL_DEBUG_INFO
381 If you say Y here gcc is instructed to generate less debugging
382 information for structure types. This means that tools that
383 need full debugging information (like kgdb or systemtap) won't
384 be happy. But if you merely need debugging information to
385 resolve line numbers there is no loss. Advantage is that
386 build directory object sizes shrink dramatically over a full
387 DEBUG_INFO build and compile times are reduced too.
388 Only works with newer gcc versions.
390 # KERNEL_DEBUG_LL symbols must have the default value set as otherwise
391 # KConfig wont evaluate them unless KERNEL_EARLY_PRINTK is selected
392 # which means that buildroot wont override the DEBUG_LL symbols in target
393 # kernel configurations and lead to devices that dont have working console
394 config KERNEL_DEBUG_LL_UART_NONE
399 config KERNEL_DEBUG_LL
403 select KERNEL_DEBUG_LL_UART_NONE
405 ARM low level debugging.
407 config KERNEL_DEBUG_VIRTUAL
408 bool "Compile the kernel with VM translations debugging"
409 select KERNEL_DEBUG_KERNEL
411 Enable checks sanity checks to catch invalid uses of
412 virt_to_phys()/phys_to_virt() against the non-linear address space.
414 config KERNEL_DYNAMIC_DEBUG
415 bool "Compile the kernel with dynamic printk"
416 select KERNEL_DEBUG_FS
418 Compiles debug level messages into the kernel, which would not
419 otherwise be available at runtime. These messages can then be
420 enabled/disabled based on various levels of scope - per source file,
421 function, module, format string, and line number. This mechanism
422 implicitly compiles in all pr_debug() and dev_dbg() calls, which
423 enlarges the kernel text size by about 2%.
425 config KERNEL_EARLY_PRINTK
426 bool "Compile the kernel with early printk"
427 default y if TARGET_bcm53xx
429 select KERNEL_DEBUG_KERNEL
430 select KERNEL_DEBUG_LL if arm
432 Compile the kernel with early printk support. This is only useful for
433 debugging purposes to send messages over the serial console in early boot.
434 Enable this to debug early boot problems.
436 config KERNEL_KPROBES
437 bool "Compile the kernel with kprobes support"
439 select KERNEL_PERF_EVENTS
441 Compiles the kernel with KPROBES support, which allows you to trap
442 at almost any kernel address and execute a callback function.
443 register_kprobe() establishes a probepoint and specifies the
444 callback. Kprobes is useful for kernel debugging, non-intrusive
445 instrumentation and testing.
446 If in doubt, say "N".
448 config KERNEL_KPROBE_EVENTS
450 default y if KERNEL_KPROBES
452 config KERNEL_BPF_EVENTS
453 bool "Compile the kernel with BPF event support"
454 select KERNEL_KPROBES
456 Allows to attach BPF programs to kprobe, uprobe and tracepoint events.
457 This is required to use BPF maps of type BPF_MAP_TYPE_PERF_EVENT_ARRAY
458 for sending data from BPF programs to user-space for post-processing
461 config KERNEL_BPF_KPROBE_OVERRIDE
463 depends on KERNEL_KPROBES
467 bool "Compile the kernel with asynchronous IO support"
468 default y if !SMALL_FLASH
470 config KERNEL_IO_URING
471 bool "Compile the kernel with io_uring support"
472 default y if !SMALL_FLASH
474 config KERNEL_FHANDLE
475 bool "Compile the kernel with support for fhandle syscalls"
476 default y if !SMALL_FLASH
478 config KERNEL_FANOTIFY
479 bool "Compile the kernel with modern file notification support"
480 default y if !SMALL_FLASH
482 config KERNEL_BLK_DEV_BSG
483 bool "Compile the kernel with SCSI generic v4 support for any block device"
485 config KERNEL_TRANSPARENT_HUGEPAGE
489 prompt "Transparent Hugepage Support sysfs defaults"
490 depends on KERNEL_TRANSPARENT_HUGEPAGE
491 default KERNEL_TRANSPARENT_HUGEPAGE_ALWAYS
493 config KERNEL_TRANSPARENT_HUGEPAGE_ALWAYS
496 config KERNEL_TRANSPARENT_HUGEPAGE_MADVISE
500 config KERNEL_HUGETLBFS
503 config KERNEL_HUGETLB_PAGE
504 bool "Compile the kernel with HugeTLB support"
505 select KERNEL_TRANSPARENT_HUGEPAGE
506 select KERNEL_HUGETLBFS
508 config KERNEL_MAGIC_SYSRQ
509 bool "Compile the kernel with SysRq support"
512 config KERNEL_DEBUG_PINCTRL
513 bool "Compile the kernel with pinctrl debugging"
514 select KERNEL_DEBUG_KERNEL
516 config KERNEL_DEBUG_GPIO
517 bool "Compile the kernel with gpio debugging"
518 select KERNEL_DEBUG_KERNEL
520 config KERNEL_COREDUMP
523 config KERNEL_ELF_CORE
524 bool "Enable process core dump support"
525 select KERNEL_COREDUMP
526 default y if !SMALL_FLASH
528 config KERNEL_PROVE_LOCKING
529 bool "Enable kernel lock checking"
530 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"
633 config KERNEL_DEVTMPFS
634 bool "Compile the kernel with device tmpfs enabled"
636 devtmpfs is a simple, kernel-managed /dev filesystem. The kernel creates
637 devices nodes for all registered devices to simplify boot, but leaves more
638 complex tasks to userspace (e.g. udev).
642 config KERNEL_DEVTMPFS_MOUNT
643 bool "Automatically mount devtmpfs after root filesystem is mounted"
648 bool "Enable kernel access key retention support"
651 config KERNEL_PERSISTENT_KEYRINGS
652 bool "Enable kernel persistent keyrings"
653 depends on KERNEL_KEYS
655 config KERNEL_KEYS_REQUEST_CACHE
656 bool "Enable temporary caching of the last request_key() result"
657 depends on KERNEL_KEYS
659 config KERNEL_BIG_KEYS
660 bool "Enable large payload keys on kernel keyrings"
661 depends on KERNEL_KEYS
664 # CGROUP support symbols
667 config KERNEL_CGROUPS
668 bool "Enable kernel cgroups"
669 default y if !SMALL_FLASH
673 config KERNEL_CGROUP_DEBUG
674 bool "Example debug cgroup subsystem"
676 This option enables a simple cgroup subsystem that
677 exports useful debugging information about the cgroups
680 config KERNEL_FREEZER
683 config KERNEL_CGROUP_FREEZER
684 bool "legacy Freezer cgroup subsystem"
685 select KERNEL_FREEZER
687 Provides a way to freeze and unfreeze all tasks in a
689 (legacy cgroup1-only controller, in cgroup2 freezer
690 is integrated in the Memory controller)
692 config KERNEL_CGROUP_DEVICE
693 bool "legacy Device controller for cgroups"
695 Provides a cgroup implementing whitelists for devices which
696 a process in the cgroup can mknod or open.
697 (legacy cgroup1-only controller)
699 config KERNEL_CGROUP_HUGETLB
700 bool "HugeTLB controller"
701 select KERNEL_HUGETLB_PAGE
703 config KERNEL_CGROUP_PIDS
704 bool "PIDs cgroup subsystem"
707 Provides enforcement of process number limits in the scope of a
710 config KERNEL_CGROUP_RDMA
711 bool "RDMA controller for cgroups"
714 config KERNEL_CGROUP_BPF
715 bool "Support for eBPF programs attached to cgroups"
718 config KERNEL_CPUSETS
719 bool "Cpuset support"
722 This option will let you create and manage CPUSETs which
723 allow dynamically partitioning a system into sets of CPUs and
724 Memory Nodes and assigning tasks to run only within those sets.
725 This is primarily useful on large SMP or NUMA systems.
727 config KERNEL_PROC_PID_CPUSET
728 bool "Include legacy /proc/<pid>/cpuset file"
729 depends on KERNEL_CPUSETS
731 config KERNEL_CGROUP_CPUACCT
732 bool "Simple CPU accounting cgroup subsystem"
735 Provides a simple Resource Controller for monitoring the
736 total CPU consumed by the tasks in a cgroup.
738 config KERNEL_RESOURCE_COUNTERS
739 bool "Resource counters"
742 This option enables controller independent resource accounting
743 infrastructure that works with cgroups.
745 config KERNEL_MM_OWNER
747 default y if KERNEL_MEMCG
750 bool "Memory Resource Controller for Control Groups"
752 select KERNEL_FREEZER
753 depends on KERNEL_RESOURCE_COUNTERS
755 Provides a memory resource controller that manages both anonymous
756 memory and page cache. (See Documentation/cgroups/memory.txt)
758 Note that setting this option increases fixed memory overhead
759 associated with each page of memory in the system. By this,
760 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
761 usage tracking struct at boot. Total amount of this is printed out
764 Only enable when you're ok with these tradeoffs and really
765 sure you need the memory resource controller. Even when you enable
766 this, you can set "cgroup_disable=memory" at your boot option to
767 disable memory resource controller and you can avoid overheads
768 (but lose benefits of memory resource controller).
770 This config option also selects MM_OWNER config option, which
771 could in turn add some fork/exit overhead.
773 config KERNEL_MEMCG_SWAP
774 bool "Memory Resource Controller Swap Extension"
776 depends on KERNEL_MEMCG
778 Add swap management feature to memory resource controller. When you
779 enable this, you can limit mem+swap usage per cgroup. In other words,
780 when you disable this, memory resource controller has no cares to
781 usage of swap...a process can exhaust all of the swap. This extension
782 is useful when you want to avoid exhaustion swap but this itself
783 adds more overheads and consumes memory for remembering information.
784 Especially if you use 32bit system or small memory system, please
785 be careful about enabling this. When memory resource controller
786 is disabled by boot option, this will be automatically disabled and
787 there will be no overhead from this. Even when you set this config=y,
788 if boot option "swapaccount=0" is set, swap will not be accounted.
789 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
790 size is 4096bytes, 512k per 1Gbytes of swap.
792 config KERNEL_MEMCG_SWAP_ENABLED
793 bool "Memory Resource Controller Swap Extension enabled by default"
794 depends on KERNEL_MEMCG_SWAP
796 Memory Resource Controller Swap Extension comes with its price in
797 a bigger memory consumption. General purpose distribution kernels
798 which want to enable the feature but keep it disabled by default
799 and let the user enable it by swapaccount boot command line
800 parameter should have this option unselected.
802 Those who want to have the feature enabled by default should
803 select this option (if, for some reason, they need to disable it,
804 then swapaccount=0 does the trick).
807 config KERNEL_MEMCG_KMEM
808 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
810 depends on KERNEL_MEMCG
812 The Kernel Memory extension for Memory Resource Controller can limit
813 the amount of memory used by kernel objects in the system. Those are
814 fundamentally different from the entities handled by the standard
815 Memory Controller, which are page-based, and can be swapped. Users of
816 the kmem extension can use it to guarantee that no group of processes
817 will ever exhaust kernel resources alone.
819 config KERNEL_CGROUP_PERF
820 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
821 select KERNEL_PERF_EVENTS
823 This option extends the per-cpu mode to restrict monitoring to
824 threads which belong to the cgroup specified and run on the
827 menuconfig KERNEL_CGROUP_SCHED
828 bool "Group CPU scheduler"
831 This feature lets CPU scheduler recognize task groups and control CPU
832 bandwidth allocation to such task groups. It uses cgroups to group
835 if KERNEL_CGROUP_SCHED
837 config KERNEL_FAIR_GROUP_SCHED
838 bool "Group scheduling for SCHED_OTHER"
841 config KERNEL_CFS_BANDWIDTH
842 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
844 depends on KERNEL_FAIR_GROUP_SCHED
846 This option allows users to define CPU bandwidth rates (limits) for
847 tasks running within the fair group scheduler. Groups with no limit
848 set are considered to be unconstrained and will run with no
850 See tip/Documentation/scheduler/sched-bwc.txt for more information.
852 config KERNEL_RT_GROUP_SCHED
853 bool "Group scheduling for SCHED_RR/FIFO"
856 This feature lets you explicitly allocate real CPU bandwidth
857 to task groups. If enabled, it will also make it impossible to
858 schedule realtime tasks for non-root users until you allocate
859 realtime bandwidth for them.
863 config KERNEL_BLK_CGROUP
864 bool "Block IO controller"
867 Generic block IO controller cgroup interface. This is the common
868 cgroup interface which should be used by various IO controlling
871 Currently, CFQ IO scheduler uses it to recognize task groups and
872 control disk bandwidth allocation (proportional time slice allocation)
873 to such task groups. It is also used by bio throttling logic in
874 block layer to implement upper limit in IO rates on a device.
876 This option only enables generic Block IO controller infrastructure.
877 One needs to also enable actual IO controlling logic/policy. For
878 enabling proportional weight division of disk bandwidth in CFQ, set
879 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
880 CONFIG_BLK_DEV_THROTTLING=y.
884 config KERNEL_CFQ_GROUP_IOSCHED
885 bool "Proportional weight of disk bandwidth in CFQ"
887 config KERNEL_BLK_DEV_THROTTLING
888 bool "Enable throttling policy"
891 config KERNEL_BLK_DEV_THROTTLING_LOW
892 bool "Block throttling .low limit interface support (EXPERIMENTAL)"
893 depends on KERNEL_BLK_DEV_THROTTLING
896 config KERNEL_DEBUG_BLK_CGROUP
897 bool "Enable Block IO controller debugging"
898 depends on KERNEL_BLK_CGROUP
900 Enable some debugging help. Currently it exports additional stat
901 files in a cgroup which can be useful for debugging.
903 config KERNEL_NET_CLS_CGROUP
904 bool "legacy Control Group Classifier"
906 config KERNEL_CGROUP_NET_CLASSID
907 bool "legacy Network classid cgroup"
909 config KERNEL_CGROUP_NET_PRIO
910 bool "legacy Network priority cgroup"
915 # Namespace support symbols
918 config KERNEL_NAMESPACES
919 bool "Enable kernel namespaces"
920 default y if !SMALL_FLASH
928 In this namespace, tasks see different info provided
929 with the uname() system call.
935 In this namespace, tasks work with IPC ids which correspond to
936 different IPC objects in different namespaces.
938 config KERNEL_USER_NS
939 bool "User namespace (EXPERIMENTAL)"
942 This allows containers, i.e. vservers, to use user namespaces
943 to provide different user info for different servers.
946 bool "PID Namespaces"
949 Support process id namespaces. This allows having multiple
950 processes with the same pid as long as they are in different
951 pid namespaces. This is a building block of containers.
954 bool "Network namespace"
957 Allow user space to create what appear to be multiple instances
958 of the network stack.
962 config KERNEL_DEVPTS_MULTIPLE_INSTANCES
963 bool "Support multiple instances of devpts"
964 default y if !SMALL_FLASH
966 Enable support for multiple instances of devpts filesystem.
967 If you want to have isolated PTY namespaces (eg: in containers),
968 say Y here. Otherwise, say N. If enabled, each mount of devpts
969 filesystem with the '-o newinstance' option will create an
970 independent PTY namespace.
972 config KERNEL_POSIX_MQUEUE
973 bool "POSIX Message Queues"
974 default y if !SMALL_FLASH
976 POSIX variant of message queues is a part of IPC. In POSIX message
977 queues every message has a priority which decides about succession
978 of receiving it by a process. If you want to compile and run
979 programs written e.g. for Solaris with use of its POSIX message
980 queues (functions mq_*) say Y here.
982 POSIX message queues are visible as a filesystem called 'mqueue'
983 and can be mounted somewhere if you want to do filesystem
984 operations on message queues.
987 config KERNEL_SECCOMP_FILTER
989 default y if !SMALL_FLASH
991 config KERNEL_SECCOMP
992 bool "Enable seccomp support"
993 depends on !(TARGET_uml)
994 select KERNEL_SECCOMP_FILTER
995 default y if !SMALL_FLASH
997 Build kernel with support for seccomp.
1000 # IPv4 configuration
1003 config KERNEL_IP_MROUTE
1004 bool "Enable IPv4 multicast routing"
1007 Multicast routing requires a multicast routing daemon in
1008 addition to kernel support.
1012 config KERNEL_IP_MROUTE_MULTIPLE_TABLES
1015 config KERNEL_IP_PIMSM_V1
1018 config KERNEL_IP_PIMSM_V2
1024 # IPv6 configuration
1032 config KERNEL_IPV6_MULTIPLE_TABLES
1035 config KERNEL_IPV6_SUBTREES
1038 config KERNEL_IPV6_MROUTE
1039 bool "Enable IPv6 multicast routing"
1042 Multicast routing requires a multicast routing daemon in
1043 addition to kernel support.
1045 if KERNEL_IPV6_MROUTE
1047 config KERNEL_IPV6_MROUTE_MULTIPLE_TABLES
1050 config KERNEL_IPV6_PIMSM_V2
1055 config KERNEL_IPV6_SEG6_LWTUNNEL
1056 bool "Enable support for lightweight tunnels"
1057 default y if !SMALL_FLASH
1059 Using lwtunnel (needed for IPv6 segment routing) requires ip-full package.
1061 config KERNEL_LWTUNNEL_BPF
1067 # Miscellaneous network configuration
1070 config KERNEL_NET_L3_MASTER_DEV
1071 bool "L3 Master device support"
1073 This module provides glue between core networking code and device
1074 drivers to support L3 master devices like VRF.
1076 config KERNEL_WIRELESS_EXT
1079 config KERNEL_WEXT_CORE
1080 def_bool KERNEL_WIRELESS_EXT
1082 config KERNEL_WEXT_PRIV
1083 def_bool KERNEL_WIRELESS_EXT
1085 config KERNEL_WEXT_PROC
1086 def_bool KERNEL_WIRELESS_EXT
1088 config KERNEL_WEXT_SPY
1089 def_bool KERNEL_WIRELESS_EXT
1091 config KERNEL_PAGE_POOL
1094 config KERNEL_PAGE_POOL_STATS
1095 bool "Page pool stats support"
1096 depends on KERNEL_PAGE_POOL
1097 depends on !LINUX_5_10
1100 # NFS related symbols
1102 config KERNEL_IP_PNP
1103 bool "Compile the kernel with rootfs on NFS"
1105 If you want to make your kernel boot off a NFS server as root
1106 filesystem, select Y here.
1110 config KERNEL_IP_PNP_DHCP
1113 config KERNEL_IP_PNP_BOOTP
1116 config KERNEL_IP_PNP_RARP
1119 config KERNEL_NFS_FS
1122 config KERNEL_NFS_V2
1125 config KERNEL_NFS_V3
1128 config KERNEL_ROOT_NFS
1133 menu "Filesystem ACL and attr support options"
1134 config USE_FS_ACL_ATTR
1135 bool "Use filesystem ACL and attr support by default"
1137 Make using ACLs (e.g. POSIX ACL, NFSv4 ACL) the default
1138 for kernel and packages, except tmpfs, flash filesystems,
1139 and old NFS. Also enable userspace extended attribute support
1140 by default. (OpenWrt already has an expection it will be
1141 present in the kernel).
1143 config KERNEL_FS_POSIX_ACL
1144 bool "Enable POSIX ACL support"
1145 default y if USE_FS_ACL_ATTR
1147 config KERNEL_BTRFS_FS_POSIX_ACL
1148 bool "Enable POSIX ACL for BtrFS Filesystems"
1149 select KERNEL_FS_POSIX_ACL
1150 default y if USE_FS_ACL_ATTR
1152 config KERNEL_EXT4_FS_POSIX_ACL
1153 bool "Enable POSIX ACL for Ext4 Filesystems"
1154 select KERNEL_FS_POSIX_ACL
1155 default y if USE_FS_ACL_ATTR
1157 config KERNEL_F2FS_FS_POSIX_ACL
1158 bool "Enable POSIX ACL for F2FS Filesystems"
1159 select KERNEL_FS_POSIX_ACL
1161 config KERNEL_JFFS2_FS_POSIX_ACL
1162 bool "Enable POSIX ACL for JFFS2 Filesystems"
1163 select KERNEL_FS_POSIX_ACL
1165 config KERNEL_TMPFS_POSIX_ACL
1166 bool "Enable POSIX ACL for TMPFS Filesystems"
1167 select KERNEL_FS_POSIX_ACL
1169 config KERNEL_CIFS_ACL
1170 bool "Enable CIFS ACLs"
1171 select KERNEL_FS_POSIX_ACL
1172 default y if USE_FS_ACL_ATTR
1174 config KERNEL_HFS_FS_POSIX_ACL
1175 bool "Enable POSIX ACL for HFS Filesystems"
1176 select KERNEL_FS_POSIX_ACL
1177 default y if USE_FS_ACL_ATTR
1179 config KERNEL_HFSPLUS_FS_POSIX_ACL
1180 bool "Enable POSIX ACL for HFS+ Filesystems"
1181 select KERNEL_FS_POSIX_ACL
1182 default y if USE_FS_ACL_ATTR
1184 config KERNEL_NFS_ACL_SUPPORT
1185 bool "Enable ACLs for NFS"
1186 default y if USE_FS_ACL_ATTR
1188 config KERNEL_NFS_V3_ACL_SUPPORT
1189 bool "Enable ACLs for NFSv3"
1191 config KERNEL_NFSD_V2_ACL_SUPPORT
1192 bool "Enable ACLs for NFSDv2"
1194 config KERNEL_NFSD_V3_ACL_SUPPORT
1195 bool "Enable ACLs for NFSDv3"
1197 config KERNEL_REISER_FS_POSIX_ACL
1198 bool "Enable POSIX ACLs for ReiserFS"
1199 select KERNEL_FS_POSIX_ACL
1200 default y if USE_FS_ACL_ATTR
1202 config KERNEL_XFS_POSIX_ACL
1203 bool "Enable POSIX ACLs for XFS"
1204 select KERNEL_FS_POSIX_ACL
1205 default y if USE_FS_ACL_ATTR
1207 config KERNEL_JFS_POSIX_ACL
1208 bool "Enable POSIX ACLs for JFS"
1209 select KERNEL_FS_POSIX_ACL
1210 default y if USE_FS_ACL_ATTR
1214 config KERNEL_DEVMEM
1215 bool "/dev/mem virtual device support"
1217 Say Y here if you want to support the /dev/mem device.
1218 The /dev/mem device is used to access areas of physical
1221 config KERNEL_DEVKMEM
1222 bool "/dev/kmem virtual device support"
1224 Say Y here if you want to support the /dev/kmem device. The
1225 /dev/kmem device is rarely used, but can be used for certain
1226 kind of kernel debugging operations.
1228 config KERNEL_SQUASHFS_FRAGMENT_CACHE_SIZE
1229 int "Number of squashfs fragments cached"
1230 default 2 if (SMALL_FLASH && !LOW_MEMORY_FOOTPRINT)
1233 config KERNEL_SQUASHFS_XATTR
1234 bool "Squashfs XATTR support"
1237 # compile optimization setting
1240 prompt "Compiler optimization level"
1241 default KERNEL_CC_OPTIMIZE_FOR_SIZE if SMALL_FLASH
1243 config KERNEL_CC_OPTIMIZE_FOR_PERFORMANCE
1244 bool "Optimize for performance"
1246 This is the default optimization level for the kernel, building
1247 with the "-O2" compiler flag for best performance and most
1248 helpful compile-time warnings.
1250 config KERNEL_CC_OPTIMIZE_FOR_SIZE
1251 bool "Optimize for size"
1253 Enabling this option will pass "-Os" instead of "-O2" to
1254 your compiler resulting in a smaller kernel.
1259 bool "Auditing support"
1261 config KERNEL_SECURITY
1262 bool "Enable different security models"
1264 config KERNEL_SECURITY_NETWORK
1265 bool "Socket and Networking Security Hooks"
1266 select KERNEL_SECURITY
1268 config KERNEL_SECURITY_SELINUX
1269 bool "NSA SELinux Support"
1270 select KERNEL_SECURITY_NETWORK
1273 config KERNEL_SECURITY_SELINUX_BOOTPARAM
1274 bool "NSA SELinux boot parameter"
1275 depends on KERNEL_SECURITY_SELINUX
1278 config KERNEL_SECURITY_SELINUX_DISABLE
1279 bool "NSA SELinux runtime disable"
1280 depends on KERNEL_SECURITY_SELINUX
1282 config KERNEL_SECURITY_SELINUX_DEVELOP
1283 bool "NSA SELinux Development Support"
1284 depends on KERNEL_SECURITY_SELINUX
1287 config KERNEL_SECURITY_SELINUX_SIDTAB_HASH_BITS
1289 depends on KERNEL_SECURITY_SELINUX
1292 config KERNEL_SECURITY_SELINUX_SID2STR_CACHE_SIZE
1294 depends on KERNEL_SECURITY_SELINUX
1299 default "lockdown,yama,loadpin,safesetid,integrity,selinux"
1300 depends on KERNEL_SECURITY_SELINUX
1302 config KERNEL_EXT4_FS_SECURITY
1303 bool "Ext4 Security Labels"
1305 config KERNEL_F2FS_FS_SECURITY
1306 bool "F2FS Security Labels"
1308 config KERNEL_UBIFS_FS_SECURITY
1309 bool "UBIFS Security Labels"
1311 config KERNEL_JFFS2_FS_SECURITY
1312 bool "JFFS2 Security Labels"