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 depends on !SMALL_FLASH
473 default y if (x86_64 || aarch64)
475 config KERNEL_FHANDLE
476 bool "Compile the kernel with support for fhandle syscalls"
477 default y if !SMALL_FLASH
479 config KERNEL_FANOTIFY
480 bool "Compile the kernel with modern file notification support"
481 default y if !SMALL_FLASH
483 config KERNEL_BLK_DEV_BSG
484 bool "Compile the kernel with SCSI generic v4 support for any block device"
486 config KERNEL_TRANSPARENT_HUGEPAGE
490 prompt "Transparent Hugepage Support sysfs defaults"
491 depends on KERNEL_TRANSPARENT_HUGEPAGE
492 default KERNEL_TRANSPARENT_HUGEPAGE_ALWAYS
494 config KERNEL_TRANSPARENT_HUGEPAGE_ALWAYS
497 config KERNEL_TRANSPARENT_HUGEPAGE_MADVISE
501 config KERNEL_HUGETLBFS
504 config KERNEL_HUGETLB_PAGE
505 bool "Compile the kernel with HugeTLB support"
506 select KERNEL_TRANSPARENT_HUGEPAGE
507 select KERNEL_HUGETLBFS
509 config KERNEL_MAGIC_SYSRQ
510 bool "Compile the kernel with SysRq support"
513 config KERNEL_DEBUG_PINCTRL
514 bool "Compile the kernel with pinctrl debugging"
515 select KERNEL_DEBUG_KERNEL
517 config KERNEL_DEBUG_GPIO
518 bool "Compile the kernel with gpio debugging"
519 select KERNEL_DEBUG_KERNEL
521 config KERNEL_COREDUMP
524 config KERNEL_ELF_CORE
525 bool "Enable process core dump support"
526 select KERNEL_COREDUMP
527 default y if !SMALL_FLASH
529 config KERNEL_PROVE_LOCKING
530 bool "Enable kernel lock checking"
531 select KERNEL_DEBUG_KERNEL
533 config KERNEL_SOFTLOCKUP_DETECTOR
534 bool "Compile the kernel with detect Soft Lockups"
535 depends on KERNEL_DEBUG_KERNEL
537 Say Y here to enable the kernel to act as a watchdog to detect
540 Softlockups are bugs that cause the kernel to loop in kernel
541 mode for more than 20 seconds, without giving other tasks a
542 chance to run. The current stack trace is displayed upon
543 detection and the system will stay locked up.
545 config KERNEL_HARDLOCKUP_DETECTOR
546 bool "Compile the kernel with detect Hard Lockups"
547 depends on KERNEL_DEBUG_KERNEL
549 Say Y here to enable the kernel to act as a watchdog to detect
552 Hardlockups are bugs that cause the CPU to loop in kernel mode
553 for more than 10 seconds, without letting other interrupts have a
554 chance to run. The current stack trace is displayed upon detection
555 and the system will stay locked up.
557 config KERNEL_DETECT_HUNG_TASK
558 bool "Compile the kernel with detect Hung Tasks"
559 depends on KERNEL_DEBUG_KERNEL
560 default KERNEL_SOFTLOCKUP_DETECTOR
562 Say Y here to enable the kernel to detect "hung tasks",
563 which are bugs that cause the task to be stuck in
564 uninterruptible "D" state indefinitely.
566 When a hung task is detected, the kernel will print the
567 current stack trace (which you should report), but the
568 task will stay in uninterruptible state. If lockdep is
569 enabled then all held locks will also be reported. This
570 feature has negligible overhead.
572 config KERNEL_WQ_WATCHDOG
573 bool "Compile the kernel with detect Workqueue Stalls"
574 depends on KERNEL_DEBUG_KERNEL
576 Say Y here to enable stall detection on workqueues. If a
577 worker pool doesn't make forward progress on a pending work
578 item for over a given amount of time, 30s by default, a
579 warning message is printed along with dump of workqueue
580 state. This can be configured through kernel parameter
581 "workqueue.watchdog_thresh" and its sysfs counterpart.
583 config KERNEL_DEBUG_ATOMIC_SLEEP
584 bool "Compile the kernel with sleep inside atomic section checking"
585 depends on KERNEL_DEBUG_KERNEL
587 If you say Y here, various routines which may sleep will become very
588 noisy if they are called inside atomic sections: when a spinlock is
589 held, inside an rcu read side critical section, inside preempt disabled
590 sections, inside an interrupt, etc...
592 config KERNEL_DEBUG_VM
593 bool "Compile the kernel with debug VM"
594 depends on KERNEL_DEBUG_KERNEL
596 Enable this to turn on extended checks in the virtual-memory system
597 that may impact performance.
601 config KERNEL_PRINTK_TIME
602 bool "Enable printk timestamps"
605 config KERNEL_SLUB_DEBUG
608 config KERNEL_SLUB_DEBUG_ON
611 config KERNEL_SLABINFO
612 select KERNEL_SLUB_DEBUG
613 select KERNEL_SLUB_DEBUG_ON
614 bool "Enable /proc slab debug info"
616 config KERNEL_PROC_PAGE_MONITOR
617 bool "Enable /proc page monitoring"
623 bool "Enable kexec support"
625 config KERNEL_PROC_VMCORE
628 config KERNEL_PROC_KCORE
631 config KERNEL_CRASH_DUMP
632 depends on i386 || x86_64 || arm || armeb
634 select KERNEL_PROC_VMCORE
635 select KERNEL_PROC_KCORE
636 bool "Enable support for kexec crashdump"
640 bool "Enable rfkill support"
641 default RFKILL_SUPPORT
644 bool "Enable sparse check during kernel build"
646 config KERNEL_DEVTMPFS
647 bool "Compile the kernel with device tmpfs enabled"
649 devtmpfs is a simple, kernel-managed /dev filesystem. The kernel creates
650 devices nodes for all registered devices to simplify boot, but leaves more
651 complex tasks to userspace (e.g. udev).
655 config KERNEL_DEVTMPFS_MOUNT
656 bool "Automatically mount devtmpfs after root filesystem is mounted"
661 bool "Enable kernel access key retention support"
664 config KERNEL_PERSISTENT_KEYRINGS
665 bool "Enable kernel persistent keyrings"
666 depends on KERNEL_KEYS
668 config KERNEL_KEYS_REQUEST_CACHE
669 bool "Enable temporary caching of the last request_key() result"
670 depends on KERNEL_KEYS
672 config KERNEL_BIG_KEYS
673 bool "Enable large payload keys on kernel keyrings"
674 depends on KERNEL_KEYS
677 # CGROUP support symbols
680 config KERNEL_CGROUPS
681 bool "Enable kernel cgroups"
682 default y if !SMALL_FLASH
686 config KERNEL_CGROUP_DEBUG
687 bool "Example debug cgroup subsystem"
689 This option enables a simple cgroup subsystem that
690 exports useful debugging information about the cgroups
693 config KERNEL_FREEZER
696 config KERNEL_CGROUP_FREEZER
697 bool "legacy Freezer cgroup subsystem"
698 select KERNEL_FREEZER
700 Provides a way to freeze and unfreeze all tasks in a
702 (legacy cgroup1-only controller, in cgroup2 freezer
703 is integrated in the Memory controller)
705 config KERNEL_CGROUP_DEVICE
706 bool "legacy Device controller for cgroups"
708 Provides a cgroup implementing whitelists for devices which
709 a process in the cgroup can mknod or open.
710 (legacy cgroup1-only controller)
712 config KERNEL_CGROUP_HUGETLB
713 bool "HugeTLB controller"
714 select KERNEL_HUGETLB_PAGE
716 config KERNEL_CGROUP_PIDS
717 bool "PIDs cgroup subsystem"
720 Provides enforcement of process number limits in the scope of a
723 config KERNEL_CGROUP_RDMA
724 bool "RDMA controller for cgroups"
727 config KERNEL_CGROUP_BPF
728 bool "Support for eBPF programs attached to cgroups"
731 config KERNEL_CPUSETS
732 bool "Cpuset support"
735 This option will let you create and manage CPUSETs which
736 allow dynamically partitioning a system into sets of CPUs and
737 Memory Nodes and assigning tasks to run only within those sets.
738 This is primarily useful on large SMP or NUMA systems.
740 config KERNEL_PROC_PID_CPUSET
741 bool "Include legacy /proc/<pid>/cpuset file"
742 depends on KERNEL_CPUSETS
744 config KERNEL_CGROUP_CPUACCT
745 bool "Simple CPU accounting cgroup subsystem"
748 Provides a simple Resource Controller for monitoring the
749 total CPU consumed by the tasks in a cgroup.
751 config KERNEL_RESOURCE_COUNTERS
752 bool "Resource counters"
755 This option enables controller independent resource accounting
756 infrastructure that works with cgroups.
758 config KERNEL_MM_OWNER
760 default y if KERNEL_MEMCG
763 bool "Memory Resource Controller for Control Groups"
765 select KERNEL_FREEZER
766 depends on KERNEL_RESOURCE_COUNTERS
768 Provides a memory resource controller that manages both anonymous
769 memory and page cache. (See Documentation/cgroups/memory.txt)
771 Note that setting this option increases fixed memory overhead
772 associated with each page of memory in the system. By this,
773 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
774 usage tracking struct at boot. Total amount of this is printed out
777 Only enable when you're ok with these tradeoffs and really
778 sure you need the memory resource controller. Even when you enable
779 this, you can set "cgroup_disable=memory" at your boot option to
780 disable memory resource controller and you can avoid overheads
781 (but lose benefits of memory resource controller).
783 This config option also selects MM_OWNER config option, which
784 could in turn add some fork/exit overhead.
786 config KERNEL_MEMCG_SWAP
787 bool "Memory Resource Controller Swap Extension"
789 depends on KERNEL_MEMCG
791 Add swap management feature to memory resource controller. When you
792 enable this, you can limit mem+swap usage per cgroup. In other words,
793 when you disable this, memory resource controller has no cares to
794 usage of swap...a process can exhaust all of the swap. This extension
795 is useful when you want to avoid exhaustion swap but this itself
796 adds more overheads and consumes memory for remembering information.
797 Especially if you use 32bit system or small memory system, please
798 be careful about enabling this. When memory resource controller
799 is disabled by boot option, this will be automatically disabled and
800 there will be no overhead from this. Even when you set this config=y,
801 if boot option "swapaccount=0" is set, swap will not be accounted.
802 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
803 size is 4096bytes, 512k per 1Gbytes of swap.
805 config KERNEL_MEMCG_SWAP_ENABLED
806 bool "Memory Resource Controller Swap Extension enabled by default"
807 depends on KERNEL_MEMCG_SWAP
809 Memory Resource Controller Swap Extension comes with its price in
810 a bigger memory consumption. General purpose distribution kernels
811 which want to enable the feature but keep it disabled by default
812 and let the user enable it by swapaccount boot command line
813 parameter should have this option unselected.
815 Those who want to have the feature enabled by default should
816 select this option (if, for some reason, they need to disable it,
817 then swapaccount=0 does the trick).
820 config KERNEL_MEMCG_KMEM
821 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
823 depends on KERNEL_MEMCG
825 The Kernel Memory extension for Memory Resource Controller can limit
826 the amount of memory used by kernel objects in the system. Those are
827 fundamentally different from the entities handled by the standard
828 Memory Controller, which are page-based, and can be swapped. Users of
829 the kmem extension can use it to guarantee that no group of processes
830 will ever exhaust kernel resources alone.
832 config KERNEL_CGROUP_PERF
833 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
834 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"
911 depends on KERNEL_BLK_CGROUP
913 Enable some debugging help. Currently it exports additional stat
914 files in a cgroup which can be useful for debugging.
916 config KERNEL_NET_CLS_CGROUP
917 bool "legacy Control Group Classifier"
919 config KERNEL_CGROUP_NET_CLASSID
920 bool "legacy Network classid cgroup"
922 config KERNEL_CGROUP_NET_PRIO
923 bool "legacy Network priority cgroup"
928 # Namespace support symbols
931 config KERNEL_NAMESPACES
932 bool "Enable kernel namespaces"
933 default y if !SMALL_FLASH
941 In this namespace, tasks see different info provided
942 with the uname() system call.
948 In this namespace, tasks work with IPC ids which correspond to
949 different IPC objects in different namespaces.
951 config KERNEL_USER_NS
952 bool "User namespace (EXPERIMENTAL)"
955 This allows containers, i.e. vservers, to use user namespaces
956 to provide different user info for different servers.
959 bool "PID Namespaces"
962 Support process id namespaces. This allows having multiple
963 processes with the same pid as long as they are in different
964 pid namespaces. This is a building block of containers.
967 bool "Network namespace"
970 Allow user space to create what appear to be multiple instances
971 of the network stack.
975 config KERNEL_DEVPTS_MULTIPLE_INSTANCES
976 bool "Support multiple instances of devpts"
977 default y if !SMALL_FLASH
979 Enable support for multiple instances of devpts filesystem.
980 If you want to have isolated PTY namespaces (eg: in containers),
981 say Y here. Otherwise, say N. If enabled, each mount of devpts
982 filesystem with the '-o newinstance' option will create an
983 independent PTY namespace.
985 config KERNEL_POSIX_MQUEUE
986 bool "POSIX Message Queues"
987 default y if !SMALL_FLASH
989 POSIX variant of message queues is a part of IPC. In POSIX message
990 queues every message has a priority which decides about succession
991 of receiving it by a process. If you want to compile and run
992 programs written e.g. for Solaris with use of its POSIX message
993 queues (functions mq_*) say Y here.
995 POSIX message queues are visible as a filesystem called 'mqueue'
996 and can be mounted somewhere if you want to do filesystem
997 operations on message queues.
1000 config KERNEL_SECCOMP_FILTER
1002 default y if !SMALL_FLASH
1004 config KERNEL_SECCOMP
1005 bool "Enable seccomp support"
1006 depends on !(TARGET_uml)
1007 select KERNEL_SECCOMP_FILTER
1008 default y if !SMALL_FLASH
1010 Build kernel with support for seccomp.
1013 # IPv4 configuration
1016 config KERNEL_IP_MROUTE
1017 bool "Enable IPv4 multicast routing"
1020 Multicast routing requires a multicast routing daemon in
1021 addition to kernel support.
1025 config KERNEL_IP_MROUTE_MULTIPLE_TABLES
1028 config KERNEL_IP_PIMSM_V1
1031 config KERNEL_IP_PIMSM_V2
1037 # IPv6 configuration
1045 config KERNEL_IPV6_MULTIPLE_TABLES
1048 config KERNEL_IPV6_SUBTREES
1051 config KERNEL_IPV6_MROUTE
1052 bool "Enable IPv6 multicast routing"
1055 Multicast routing requires a multicast routing daemon in
1056 addition to kernel support.
1058 if KERNEL_IPV6_MROUTE
1060 config KERNEL_IPV6_MROUTE_MULTIPLE_TABLES
1063 config KERNEL_IPV6_PIMSM_V2
1068 config KERNEL_IPV6_SEG6_LWTUNNEL
1069 bool "Enable support for lightweight tunnels"
1070 default y if !SMALL_FLASH
1072 Using lwtunnel (needed for IPv6 segment routing) requires ip-full package.
1074 config KERNEL_LWTUNNEL_BPF
1080 # Miscellaneous network configuration
1083 config KERNEL_NET_L3_MASTER_DEV
1084 bool "L3 Master device support"
1086 This module provides glue between core networking code and device
1087 drivers to support L3 master devices like VRF.
1089 config KERNEL_WIRELESS_EXT
1092 config KERNEL_WEXT_CORE
1093 def_bool KERNEL_WIRELESS_EXT
1095 config KERNEL_WEXT_PRIV
1096 def_bool KERNEL_WIRELESS_EXT
1098 config KERNEL_WEXT_PROC
1099 def_bool KERNEL_WIRELESS_EXT
1101 config KERNEL_WEXT_SPY
1102 def_bool KERNEL_WIRELESS_EXT
1104 config KERNEL_PAGE_POOL
1107 config KERNEL_PAGE_POOL_STATS
1108 bool "Page pool stats support"
1109 depends on KERNEL_PAGE_POOL
1110 depends on !LINUX_5_10
1113 # NFS related symbols
1115 config KERNEL_IP_PNP
1116 bool "Compile the kernel with rootfs on NFS"
1118 If you want to make your kernel boot off a NFS server as root
1119 filesystem, select Y here.
1123 config KERNEL_IP_PNP_DHCP
1126 config KERNEL_IP_PNP_BOOTP
1129 config KERNEL_IP_PNP_RARP
1132 config KERNEL_NFS_FS
1135 config KERNEL_NFS_V2
1138 config KERNEL_NFS_V3
1141 config KERNEL_ROOT_NFS
1146 menu "Filesystem ACL and attr support options"
1147 config USE_FS_ACL_ATTR
1148 bool "Use filesystem ACL and attr support by default"
1150 Make using ACLs (e.g. POSIX ACL, NFSv4 ACL) the default
1151 for kernel and packages, except tmpfs, flash filesystems,
1152 and old NFS. Also enable userspace extended attribute support
1153 by default. (OpenWrt already has an expection it will be
1154 present in the kernel).
1156 config KERNEL_FS_POSIX_ACL
1157 bool "Enable POSIX ACL support"
1158 default y if USE_FS_ACL_ATTR
1160 config KERNEL_BTRFS_FS_POSIX_ACL
1161 bool "Enable POSIX ACL for BtrFS Filesystems"
1162 select KERNEL_FS_POSIX_ACL
1163 default y if USE_FS_ACL_ATTR
1165 config KERNEL_EXT4_FS_POSIX_ACL
1166 bool "Enable POSIX ACL for Ext4 Filesystems"
1167 select KERNEL_FS_POSIX_ACL
1168 default y if USE_FS_ACL_ATTR
1170 config KERNEL_F2FS_FS_POSIX_ACL
1171 bool "Enable POSIX ACL for F2FS Filesystems"
1172 select KERNEL_FS_POSIX_ACL
1174 config KERNEL_JFFS2_FS_POSIX_ACL
1175 bool "Enable POSIX ACL for JFFS2 Filesystems"
1176 select KERNEL_FS_POSIX_ACL
1178 config KERNEL_TMPFS_POSIX_ACL
1179 bool "Enable POSIX ACL for TMPFS Filesystems"
1180 select KERNEL_FS_POSIX_ACL
1182 config KERNEL_CIFS_ACL
1183 bool "Enable CIFS ACLs"
1184 select KERNEL_FS_POSIX_ACL
1185 default y if USE_FS_ACL_ATTR
1187 config KERNEL_HFS_FS_POSIX_ACL
1188 bool "Enable POSIX ACL for HFS Filesystems"
1189 select KERNEL_FS_POSIX_ACL
1190 default y if USE_FS_ACL_ATTR
1192 config KERNEL_HFSPLUS_FS_POSIX_ACL
1193 bool "Enable POSIX ACL for HFS+ Filesystems"
1194 select KERNEL_FS_POSIX_ACL
1195 default y if USE_FS_ACL_ATTR
1197 config KERNEL_NFS_ACL_SUPPORT
1198 bool "Enable ACLs for NFS"
1199 default y if USE_FS_ACL_ATTR
1201 config KERNEL_NFS_V3_ACL_SUPPORT
1202 bool "Enable ACLs for NFSv3"
1204 config KERNEL_NFSD_V2_ACL_SUPPORT
1205 bool "Enable ACLs for NFSDv2"
1207 config KERNEL_NFSD_V3_ACL_SUPPORT
1208 bool "Enable ACLs for NFSDv3"
1210 config KERNEL_REISER_FS_POSIX_ACL
1211 bool "Enable POSIX ACLs for ReiserFS"
1212 select KERNEL_FS_POSIX_ACL
1213 default y if USE_FS_ACL_ATTR
1215 config KERNEL_XFS_POSIX_ACL
1216 bool "Enable POSIX ACLs for XFS"
1217 select KERNEL_FS_POSIX_ACL
1218 default y if USE_FS_ACL_ATTR
1220 config KERNEL_JFS_POSIX_ACL
1221 bool "Enable POSIX ACLs for JFS"
1222 select KERNEL_FS_POSIX_ACL
1223 default y if USE_FS_ACL_ATTR
1227 config KERNEL_DEVMEM
1228 bool "/dev/mem virtual device support"
1230 Say Y here if you want to support the /dev/mem device.
1231 The /dev/mem device is used to access areas of physical
1234 config KERNEL_DEVKMEM
1235 bool "/dev/kmem virtual device support"
1237 Say Y here if you want to support the /dev/kmem device. The
1238 /dev/kmem device is rarely used, but can be used for certain
1239 kind of kernel debugging operations.
1241 config KERNEL_SQUASHFS_FRAGMENT_CACHE_SIZE
1242 int "Number of squashfs fragments cached"
1243 default 2 if (SMALL_FLASH && !LOW_MEMORY_FOOTPRINT)
1246 config KERNEL_SQUASHFS_XATTR
1247 bool "Squashfs XATTR support"
1250 # compile optimization setting
1253 prompt "Compiler optimization level"
1254 default KERNEL_CC_OPTIMIZE_FOR_SIZE if SMALL_FLASH
1256 config KERNEL_CC_OPTIMIZE_FOR_PERFORMANCE
1257 bool "Optimize for performance"
1259 This is the default optimization level for the kernel, building
1260 with the "-O2" compiler flag for best performance and most
1261 helpful compile-time warnings.
1263 config KERNEL_CC_OPTIMIZE_FOR_SIZE
1264 bool "Optimize for size"
1266 Enabling this option will pass "-Os" instead of "-O2" to
1267 your compiler resulting in a smaller kernel.
1272 bool "Auditing support"
1274 config KERNEL_SECURITY
1275 bool "Enable different security models"
1277 config KERNEL_SECURITY_NETWORK
1278 bool "Socket and Networking Security Hooks"
1279 select KERNEL_SECURITY
1281 config KERNEL_SECURITY_SELINUX
1282 bool "NSA SELinux Support"
1283 select KERNEL_SECURITY_NETWORK
1286 config KERNEL_SECURITY_SELINUX_BOOTPARAM
1287 bool "NSA SELinux boot parameter"
1288 depends on KERNEL_SECURITY_SELINUX
1291 config KERNEL_SECURITY_SELINUX_DISABLE
1292 bool "NSA SELinux runtime disable"
1293 depends on KERNEL_SECURITY_SELINUX
1295 config KERNEL_SECURITY_SELINUX_DEVELOP
1296 bool "NSA SELinux Development Support"
1297 depends on KERNEL_SECURITY_SELINUX
1300 config KERNEL_SECURITY_SELINUX_SIDTAB_HASH_BITS
1302 depends on KERNEL_SECURITY_SELINUX
1305 config KERNEL_SECURITY_SELINUX_SID2STR_CACHE_SIZE
1307 depends on KERNEL_SECURITY_SELINUX
1312 default "lockdown,yama,loadpin,safesetid,integrity,selinux"
1313 depends on KERNEL_SECURITY_SELINUX
1315 config KERNEL_EXT4_FS_SECURITY
1316 bool "Ext4 Security Labels"
1318 config KERNEL_F2FS_FS_SECURITY
1319 bool "F2FS Security Labels"
1321 config KERNEL_UBIFS_FS_SECURITY
1322 bool "UBIFS Security Labels"
1324 config KERNEL_JFFS2_FS_SECURITY
1325 bool "JFFS2 Security Labels"