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 config KERNEL_DEBUG_LL_UART_NONE
394 config KERNEL_DEBUG_LL
397 select KERNEL_DEBUG_LL_UART_NONE
399 ARM low level debugging.
401 config KERNEL_DEBUG_VIRTUAL
402 bool "Compile the kernel with VM translations debugging"
403 select KERNEL_DEBUG_KERNEL
405 Enable checks sanity checks to catch invalid uses of
406 virt_to_phys()/phys_to_virt() against the non-linear address space.
408 config KERNEL_DYNAMIC_DEBUG
409 bool "Compile the kernel with dynamic printk"
410 select KERNEL_DEBUG_FS
412 Compiles debug level messages into the kernel, which would not
413 otherwise be available at runtime. These messages can then be
414 enabled/disabled based on various levels of scope - per source file,
415 function, module, format string, and line number. This mechanism
416 implicitly compiles in all pr_debug() and dev_dbg() calls, which
417 enlarges the kernel text size by about 2%.
419 config KERNEL_EARLY_PRINTK
420 bool "Compile the kernel with early printk"
421 default y if TARGET_bcm53xx
423 select KERNEL_DEBUG_KERNEL
424 select KERNEL_DEBUG_LL if arm
426 Compile the kernel with early printk support. This is only useful for
427 debugging purposes to send messages over the serial console in early boot.
428 Enable this to debug early boot problems.
430 config KERNEL_KPROBES
431 bool "Compile the kernel with kprobes support"
433 select KERNEL_PERF_EVENTS
435 Compiles the kernel with KPROBES support, which allows you to trap
436 at almost any kernel address and execute a callback function.
437 register_kprobe() establishes a probepoint and specifies the
438 callback. Kprobes is useful for kernel debugging, non-intrusive
439 instrumentation and testing.
440 If in doubt, say "N".
442 config KERNEL_KPROBE_EVENTS
444 default y if KERNEL_KPROBES
446 config KERNEL_BPF_EVENTS
447 bool "Compile the kernel with BPF event support"
448 select KERNEL_KPROBES
450 Allows to attach BPF programs to kprobe, uprobe and tracepoint events.
451 This is required to use BPF maps of type BPF_MAP_TYPE_PERF_EVENT_ARRAY
452 for sending data from BPF programs to user-space for post-processing
455 config KERNEL_BPF_KPROBE_OVERRIDE
457 depends on KERNEL_KPROBES
460 bool "Compile the kernel with asynchronous IO support"
461 default y if !SMALL_FLASH
463 config KERNEL_IO_URING
464 bool "Compile the kernel with io_uring support"
465 default y if !SMALL_FLASH
467 config KERNEL_FHANDLE
468 bool "Compile the kernel with support for fhandle syscalls"
469 default y if !SMALL_FLASH
471 config KERNEL_FANOTIFY
472 bool "Compile the kernel with modern file notification support"
473 default y if !SMALL_FLASH
475 config KERNEL_BLK_DEV_BSG
476 bool "Compile the kernel with SCSI generic v4 support for any block device"
478 config KERNEL_TRANSPARENT_HUGEPAGE
482 prompt "Transparent Hugepage Support sysfs defaults"
483 depends on KERNEL_TRANSPARENT_HUGEPAGE
484 default KERNEL_TRANSPARENT_HUGEPAGE_ALWAYS
486 config KERNEL_TRANSPARENT_HUGEPAGE_ALWAYS
489 config KERNEL_TRANSPARENT_HUGEPAGE_MADVISE
493 config KERNEL_HUGETLBFS
496 config KERNEL_HUGETLB_PAGE
497 bool "Compile the kernel with HugeTLB support"
498 select KERNEL_TRANSPARENT_HUGEPAGE
499 select KERNEL_HUGETLBFS
501 config KERNEL_MAGIC_SYSRQ
502 bool "Compile the kernel with SysRq support"
505 config KERNEL_DEBUG_PINCTRL
506 bool "Compile the kernel with pinctrl debugging"
507 select KERNEL_DEBUG_KERNEL
509 config KERNEL_DEBUG_GPIO
510 bool "Compile the kernel with gpio debugging"
511 select KERNEL_DEBUG_KERNEL
513 config KERNEL_COREDUMP
516 config KERNEL_ELF_CORE
517 bool "Enable process core dump support"
518 select KERNEL_COREDUMP
519 default y if !SMALL_FLASH
521 config KERNEL_PROVE_LOCKING
522 bool "Enable kernel lock checking"
523 select KERNEL_DEBUG_KERNEL
525 config KERNEL_SOFTLOCKUP_DETECTOR
526 bool "Compile the kernel with detect Soft Lockups"
527 depends on KERNEL_DEBUG_KERNEL
529 Say Y here to enable the kernel to act as a watchdog to detect
532 Softlockups are bugs that cause the kernel to loop in kernel
533 mode for more than 20 seconds, without giving other tasks a
534 chance to run. The current stack trace is displayed upon
535 detection and the system will stay locked up.
537 config KERNEL_DETECT_HUNG_TASK
538 bool "Compile the kernel with detect Hung Tasks"
539 depends on KERNEL_DEBUG_KERNEL
540 default KERNEL_SOFTLOCKUP_DETECTOR
542 Say Y here to enable the kernel to detect "hung tasks",
543 which are bugs that cause the task to be stuck in
544 uninterruptible "D" state indefinitely.
546 When a hung task is detected, the kernel will print the
547 current stack trace (which you should report), but the
548 task will stay in uninterruptible state. If lockdep is
549 enabled then all held locks will also be reported. This
550 feature has negligible overhead.
552 config KERNEL_WQ_WATCHDOG
553 bool "Compile the kernel with detect Workqueue Stalls"
554 depends on KERNEL_DEBUG_KERNEL
556 Say Y here to enable stall detection on workqueues. If a
557 worker pool doesn't make forward progress on a pending work
558 item for over a given amount of time, 30s by default, a
559 warning message is printed along with dump of workqueue
560 state. This can be configured through kernel parameter
561 "workqueue.watchdog_thresh" and its sysfs counterpart.
563 config KERNEL_DEBUG_ATOMIC_SLEEP
564 bool "Compile the kernel with sleep inside atomic section checking"
565 depends on KERNEL_DEBUG_KERNEL
567 If you say Y here, various routines which may sleep will become very
568 noisy if they are called inside atomic sections: when a spinlock is
569 held, inside an rcu read side critical section, inside preempt disabled
570 sections, inside an interrupt, etc...
572 config KERNEL_DEBUG_VM
573 bool "Compile the kernel with debug VM"
574 depends on KERNEL_DEBUG_KERNEL
576 Enable this to turn on extended checks in the virtual-memory system
577 that may impact performance.
581 config KERNEL_PRINTK_TIME
582 bool "Enable printk timestamps"
585 config KERNEL_SLUB_DEBUG
588 config KERNEL_SLUB_DEBUG_ON
591 config KERNEL_SLABINFO
592 select KERNEL_SLUB_DEBUG
593 select KERNEL_SLUB_DEBUG_ON
594 bool "Enable /proc slab debug info"
596 config KERNEL_PROC_PAGE_MONITOR
597 bool "Enable /proc page monitoring"
603 bool "Enable kexec support"
605 config KERNEL_PROC_VMCORE
608 config KERNEL_PROC_KCORE
611 config KERNEL_CRASH_DUMP
612 depends on i386 || x86_64 || arm || armeb
614 select KERNEL_PROC_VMCORE
615 select KERNEL_PROC_KCORE
616 bool "Enable support for kexec crashdump"
620 bool "Enable rfkill support"
621 default RFKILL_SUPPORT
624 bool "Enable sparse check during kernel build"
626 config KERNEL_DEVTMPFS
627 bool "Compile the kernel with device tmpfs enabled"
629 devtmpfs is a simple, kernel-managed /dev filesystem. The kernel creates
630 devices nodes for all registered devices to simplify boot, but leaves more
631 complex tasks to userspace (e.g. udev).
635 config KERNEL_DEVTMPFS_MOUNT
636 bool "Automatically mount devtmpfs after root filesystem is mounted"
641 bool "Enable kernel access key retention support"
644 config KERNEL_PERSISTENT_KEYRINGS
645 bool "Enable kernel persistent keyrings"
646 depends on KERNEL_KEYS
648 config KERNEL_KEYS_REQUEST_CACHE
649 bool "Enable temporary caching of the last request_key() result"
650 depends on KERNEL_KEYS
652 config KERNEL_BIG_KEYS
653 bool "Enable large payload keys on kernel keyrings"
654 depends on KERNEL_KEYS
657 # CGROUP support symbols
660 config KERNEL_CGROUPS
661 bool "Enable kernel cgroups"
662 default y if !SMALL_FLASH
666 config KERNEL_CGROUP_DEBUG
667 bool "Example debug cgroup subsystem"
669 This option enables a simple cgroup subsystem that
670 exports useful debugging information about the cgroups
673 config KERNEL_FREEZER
676 config KERNEL_CGROUP_FREEZER
677 bool "legacy Freezer cgroup subsystem"
678 select KERNEL_FREEZER
680 Provides a way to freeze and unfreeze all tasks in a
682 (legacy cgroup1-only controller, in cgroup2 freezer
683 is integrated in the Memory controller)
685 config KERNEL_CGROUP_DEVICE
686 bool "legacy Device controller for cgroups"
688 Provides a cgroup implementing whitelists for devices which
689 a process in the cgroup can mknod or open.
690 (legacy cgroup1-only controller)
692 config KERNEL_CGROUP_HUGETLB
693 bool "HugeTLB controller"
694 select KERNEL_HUGETLB_PAGE
696 config KERNEL_CGROUP_PIDS
697 bool "PIDs cgroup subsystem"
700 Provides enforcement of process number limits in the scope of a
703 config KERNEL_CGROUP_RDMA
704 bool "RDMA controller for cgroups"
707 config KERNEL_CGROUP_BPF
708 bool "Support for eBPF programs attached to cgroups"
711 config KERNEL_CPUSETS
712 bool "Cpuset support"
715 This option will let you create and manage CPUSETs which
716 allow dynamically partitioning a system into sets of CPUs and
717 Memory Nodes and assigning tasks to run only within those sets.
718 This is primarily useful on large SMP or NUMA systems.
720 config KERNEL_PROC_PID_CPUSET
721 bool "Include legacy /proc/<pid>/cpuset file"
722 depends on KERNEL_CPUSETS
724 config KERNEL_CGROUP_CPUACCT
725 bool "Simple CPU accounting cgroup subsystem"
728 Provides a simple Resource Controller for monitoring the
729 total CPU consumed by the tasks in a cgroup.
731 config KERNEL_RESOURCE_COUNTERS
732 bool "Resource counters"
735 This option enables controller independent resource accounting
736 infrastructure that works with cgroups.
738 config KERNEL_MM_OWNER
740 default y if KERNEL_MEMCG
743 bool "Memory Resource Controller for Control Groups"
745 select KERNEL_FREEZER
746 depends on KERNEL_RESOURCE_COUNTERS
748 Provides a memory resource controller that manages both anonymous
749 memory and page cache. (See Documentation/cgroups/memory.txt)
751 Note that setting this option increases fixed memory overhead
752 associated with each page of memory in the system. By this,
753 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
754 usage tracking struct at boot. Total amount of this is printed out
757 Only enable when you're ok with these tradeoffs and really
758 sure you need the memory resource controller. Even when you enable
759 this, you can set "cgroup_disable=memory" at your boot option to
760 disable memory resource controller and you can avoid overheads
761 (but lose benefits of memory resource controller).
763 This config option also selects MM_OWNER config option, which
764 could in turn add some fork/exit overhead.
766 config KERNEL_MEMCG_SWAP
767 bool "Memory Resource Controller Swap Extension"
769 depends on KERNEL_MEMCG
771 Add swap management feature to memory resource controller. When you
772 enable this, you can limit mem+swap usage per cgroup. In other words,
773 when you disable this, memory resource controller has no cares to
774 usage of swap...a process can exhaust all of the swap. This extension
775 is useful when you want to avoid exhaustion swap but this itself
776 adds more overheads and consumes memory for remembering information.
777 Especially if you use 32bit system or small memory system, please
778 be careful about enabling this. When memory resource controller
779 is disabled by boot option, this will be automatically disabled and
780 there will be no overhead from this. Even when you set this config=y,
781 if boot option "swapaccount=0" is set, swap will not be accounted.
782 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
783 size is 4096bytes, 512k per 1Gbytes of swap.
785 config KERNEL_MEMCG_SWAP_ENABLED
786 bool "Memory Resource Controller Swap Extension enabled by default"
787 depends on KERNEL_MEMCG_SWAP
789 Memory Resource Controller Swap Extension comes with its price in
790 a bigger memory consumption. General purpose distribution kernels
791 which want to enable the feature but keep it disabled by default
792 and let the user enable it by swapaccount boot command line
793 parameter should have this option unselected.
795 Those who want to have the feature enabled by default should
796 select this option (if, for some reason, they need to disable it,
797 then swapaccount=0 does the trick).
800 config KERNEL_MEMCG_KMEM
801 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
803 depends on KERNEL_MEMCG
805 The Kernel Memory extension for Memory Resource Controller can limit
806 the amount of memory used by kernel objects in the system. Those are
807 fundamentally different from the entities handled by the standard
808 Memory Controller, which are page-based, and can be swapped. Users of
809 the kmem extension can use it to guarantee that no group of processes
810 will ever exhaust kernel resources alone.
812 config KERNEL_CGROUP_PERF
813 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
814 select KERNEL_PERF_EVENTS
816 This option extends the per-cpu mode to restrict monitoring to
817 threads which belong to the cgroup specified and run on the
820 menuconfig KERNEL_CGROUP_SCHED
821 bool "Group CPU scheduler"
824 This feature lets CPU scheduler recognize task groups and control CPU
825 bandwidth allocation to such task groups. It uses cgroups to group
828 if KERNEL_CGROUP_SCHED
830 config KERNEL_FAIR_GROUP_SCHED
831 bool "Group scheduling for SCHED_OTHER"
834 config KERNEL_CFS_BANDWIDTH
835 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
837 depends on KERNEL_FAIR_GROUP_SCHED
839 This option allows users to define CPU bandwidth rates (limits) for
840 tasks running within the fair group scheduler. Groups with no limit
841 set are considered to be unconstrained and will run with no
843 See tip/Documentation/scheduler/sched-bwc.txt for more information.
845 config KERNEL_RT_GROUP_SCHED
846 bool "Group scheduling for SCHED_RR/FIFO"
849 This feature lets you explicitly allocate real CPU bandwidth
850 to task groups. If enabled, it will also make it impossible to
851 schedule realtime tasks for non-root users until you allocate
852 realtime bandwidth for them.
856 config KERNEL_BLK_CGROUP
857 bool "Block IO controller"
860 Generic block IO controller cgroup interface. This is the common
861 cgroup interface which should be used by various IO controlling
864 Currently, CFQ IO scheduler uses it to recognize task groups and
865 control disk bandwidth allocation (proportional time slice allocation)
866 to such task groups. It is also used by bio throttling logic in
867 block layer to implement upper limit in IO rates on a device.
869 This option only enables generic Block IO controller infrastructure.
870 One needs to also enable actual IO controlling logic/policy. For
871 enabling proportional weight division of disk bandwidth in CFQ, set
872 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
873 CONFIG_BLK_DEV_THROTTLING=y.
877 config KERNEL_CFQ_GROUP_IOSCHED
878 bool "Proportional weight of disk bandwidth in CFQ"
880 config KERNEL_BLK_DEV_THROTTLING
881 bool "Enable throttling policy"
884 config KERNEL_BLK_DEV_THROTTLING_LOW
885 bool "Block throttling .low limit interface support (EXPERIMENTAL)"
886 depends on KERNEL_BLK_DEV_THROTTLING
889 config KERNEL_DEBUG_BLK_CGROUP
890 bool "Enable Block IO controller debugging"
891 depends on KERNEL_BLK_CGROUP
893 Enable some debugging help. Currently it exports additional stat
894 files in a cgroup which can be useful for debugging.
896 config KERNEL_NET_CLS_CGROUP
897 bool "legacy Control Group Classifier"
899 config KERNEL_CGROUP_NET_CLASSID
900 bool "legacy Network classid cgroup"
902 config KERNEL_CGROUP_NET_PRIO
903 bool "legacy Network priority cgroup"
908 # Namespace support symbols
911 config KERNEL_NAMESPACES
912 bool "Enable kernel namespaces"
913 default y if !SMALL_FLASH
921 In this namespace, tasks see different info provided
922 with the uname() system call.
928 In this namespace, tasks work with IPC ids which correspond to
929 different IPC objects in different namespaces.
931 config KERNEL_USER_NS
932 bool "User namespace (EXPERIMENTAL)"
935 This allows containers, i.e. vservers, to use user namespaces
936 to provide different user info for different servers.
939 bool "PID Namespaces"
942 Support process id namespaces. This allows having multiple
943 processes with the same pid as long as they are in different
944 pid namespaces. This is a building block of containers.
947 bool "Network namespace"
950 Allow user space to create what appear to be multiple instances
951 of the network stack.
955 config KERNEL_DEVPTS_MULTIPLE_INSTANCES
956 bool "Support multiple instances of devpts"
957 default y if !SMALL_FLASH
959 Enable support for multiple instances of devpts filesystem.
960 If you want to have isolated PTY namespaces (eg: in containers),
961 say Y here. Otherwise, say N. If enabled, each mount of devpts
962 filesystem with the '-o newinstance' option will create an
963 independent PTY namespace.
965 config KERNEL_POSIX_MQUEUE
966 bool "POSIX Message Queues"
967 default y if !SMALL_FLASH
969 POSIX variant of message queues is a part of IPC. In POSIX message
970 queues every message has a priority which decides about succession
971 of receiving it by a process. If you want to compile and run
972 programs written e.g. for Solaris with use of its POSIX message
973 queues (functions mq_*) say Y here.
975 POSIX message queues are visible as a filesystem called 'mqueue'
976 and can be mounted somewhere if you want to do filesystem
977 operations on message queues.
980 config KERNEL_SECCOMP_FILTER
982 default y if !SMALL_FLASH
984 config KERNEL_SECCOMP
985 bool "Enable seccomp support"
986 depends on !(TARGET_uml)
987 select KERNEL_SECCOMP_FILTER
988 default y if !SMALL_FLASH
990 Build kernel with support for seccomp.
996 config KERNEL_IP_MROUTE
997 bool "Enable IPv4 multicast routing"
1000 Multicast routing requires a multicast routing daemon in
1001 addition to kernel support.
1005 config KERNEL_IP_MROUTE_MULTIPLE_TABLES
1008 config KERNEL_IP_PIMSM_V1
1011 config KERNEL_IP_PIMSM_V2
1017 # IPv6 configuration
1025 config KERNEL_IPV6_MULTIPLE_TABLES
1028 config KERNEL_IPV6_SUBTREES
1031 config KERNEL_IPV6_MROUTE
1032 bool "Enable IPv6 multicast routing"
1035 Multicast routing requires a multicast routing daemon in
1036 addition to kernel support.
1038 if KERNEL_IPV6_MROUTE
1040 config KERNEL_IPV6_MROUTE_MULTIPLE_TABLES
1043 config KERNEL_IPV6_PIMSM_V2
1048 config KERNEL_IPV6_SEG6_LWTUNNEL
1049 bool "Enable support for lightweight tunnels"
1050 default y if !SMALL_FLASH
1052 Using lwtunnel (needed for IPv6 segment routing) requires ip-full package.
1054 config KERNEL_LWTUNNEL_BPF
1060 # Miscellaneous network configuration
1063 config KERNEL_NET_L3_MASTER_DEV
1064 bool "L3 Master device support"
1066 This module provides glue between core networking code and device
1067 drivers to support L3 master devices like VRF.
1069 config KERNEL_WIRELESS_EXT
1072 config KERNEL_WEXT_CORE
1073 def_bool KERNEL_WIRELESS_EXT
1075 config KERNEL_WEXT_PRIV
1076 def_bool KERNEL_WIRELESS_EXT
1078 config KERNEL_WEXT_PROC
1079 def_bool KERNEL_WIRELESS_EXT
1081 config KERNEL_WEXT_SPY
1082 def_bool KERNEL_WIRELESS_EXT
1084 config KERNEL_PAGE_POOL
1087 config KERNEL_PAGE_POOL_STATS
1088 bool "Page pool stats support"
1089 depends on KERNEL_PAGE_POOL
1090 depends on !LINUX_5_10
1093 # NFS related symbols
1095 config KERNEL_IP_PNP
1096 bool "Compile the kernel with rootfs on NFS"
1098 If you want to make your kernel boot off a NFS server as root
1099 filesystem, select Y here.
1103 config KERNEL_IP_PNP_DHCP
1106 config KERNEL_IP_PNP_BOOTP
1109 config KERNEL_IP_PNP_RARP
1112 config KERNEL_NFS_FS
1115 config KERNEL_NFS_V2
1118 config KERNEL_NFS_V3
1121 config KERNEL_ROOT_NFS
1126 menu "Filesystem ACL and attr support options"
1127 config USE_FS_ACL_ATTR
1128 bool "Use filesystem ACL and attr support by default"
1130 Make using ACLs (e.g. POSIX ACL, NFSv4 ACL) the default
1131 for kernel and packages, except tmpfs, flash filesystems,
1132 and old NFS. Also enable userspace extended attribute support
1133 by default. (OpenWrt already has an expection it will be
1134 present in the kernel).
1136 config KERNEL_FS_POSIX_ACL
1137 bool "Enable POSIX ACL support"
1138 default y if USE_FS_ACL_ATTR
1140 config KERNEL_BTRFS_FS_POSIX_ACL
1141 bool "Enable POSIX ACL for BtrFS Filesystems"
1142 select KERNEL_FS_POSIX_ACL
1143 default y if USE_FS_ACL_ATTR
1145 config KERNEL_EXT4_FS_POSIX_ACL
1146 bool "Enable POSIX ACL for Ext4 Filesystems"
1147 select KERNEL_FS_POSIX_ACL
1148 default y if USE_FS_ACL_ATTR
1150 config KERNEL_F2FS_FS_POSIX_ACL
1151 bool "Enable POSIX ACL for F2FS Filesystems"
1152 select KERNEL_FS_POSIX_ACL
1154 config KERNEL_JFFS2_FS_POSIX_ACL
1155 bool "Enable POSIX ACL for JFFS2 Filesystems"
1156 select KERNEL_FS_POSIX_ACL
1158 config KERNEL_TMPFS_POSIX_ACL
1159 bool "Enable POSIX ACL for TMPFS Filesystems"
1160 select KERNEL_FS_POSIX_ACL
1162 config KERNEL_CIFS_ACL
1163 bool "Enable CIFS ACLs"
1164 select KERNEL_FS_POSIX_ACL
1165 default y if USE_FS_ACL_ATTR
1167 config KERNEL_HFS_FS_POSIX_ACL
1168 bool "Enable POSIX ACL for HFS Filesystems"
1169 select KERNEL_FS_POSIX_ACL
1170 default y if USE_FS_ACL_ATTR
1172 config KERNEL_HFSPLUS_FS_POSIX_ACL
1173 bool "Enable POSIX ACL for HFS+ Filesystems"
1174 select KERNEL_FS_POSIX_ACL
1175 default y if USE_FS_ACL_ATTR
1177 config KERNEL_NFS_ACL_SUPPORT
1178 bool "Enable ACLs for NFS"
1179 default y if USE_FS_ACL_ATTR
1181 config KERNEL_NFS_V3_ACL_SUPPORT
1182 bool "Enable ACLs for NFSv3"
1184 config KERNEL_NFSD_V2_ACL_SUPPORT
1185 bool "Enable ACLs for NFSDv2"
1187 config KERNEL_NFSD_V3_ACL_SUPPORT
1188 bool "Enable ACLs for NFSDv3"
1190 config KERNEL_REISER_FS_POSIX_ACL
1191 bool "Enable POSIX ACLs for ReiserFS"
1192 select KERNEL_FS_POSIX_ACL
1193 default y if USE_FS_ACL_ATTR
1195 config KERNEL_XFS_POSIX_ACL
1196 bool "Enable POSIX ACLs for XFS"
1197 select KERNEL_FS_POSIX_ACL
1198 default y if USE_FS_ACL_ATTR
1200 config KERNEL_JFS_POSIX_ACL
1201 bool "Enable POSIX ACLs for JFS"
1202 select KERNEL_FS_POSIX_ACL
1203 default y if USE_FS_ACL_ATTR
1207 config KERNEL_DEVMEM
1208 bool "/dev/mem virtual device support"
1210 Say Y here if you want to support the /dev/mem device.
1211 The /dev/mem device is used to access areas of physical
1214 config KERNEL_DEVKMEM
1215 bool "/dev/kmem virtual device support"
1217 Say Y here if you want to support the /dev/kmem device. The
1218 /dev/kmem device is rarely used, but can be used for certain
1219 kind of kernel debugging operations.
1221 config KERNEL_SQUASHFS_FRAGMENT_CACHE_SIZE
1222 int "Number of squashfs fragments cached"
1223 default 2 if (SMALL_FLASH && !LOW_MEMORY_FOOTPRINT)
1226 config KERNEL_SQUASHFS_XATTR
1227 bool "Squashfs XATTR support"
1230 # compile optimization setting
1233 prompt "Compiler optimization level"
1234 default KERNEL_CC_OPTIMIZE_FOR_SIZE if SMALL_FLASH
1236 config KERNEL_CC_OPTIMIZE_FOR_PERFORMANCE
1237 bool "Optimize for performance"
1239 This is the default optimization level for the kernel, building
1240 with the "-O2" compiler flag for best performance and most
1241 helpful compile-time warnings.
1243 config KERNEL_CC_OPTIMIZE_FOR_SIZE
1244 bool "Optimize for size"
1246 Enabling this option will pass "-Os" instead of "-O2" to
1247 your compiler resulting in a smaller kernel.
1252 bool "Auditing support"
1254 config KERNEL_SECURITY
1255 bool "Enable different security models"
1257 config KERNEL_SECURITY_NETWORK
1258 bool "Socket and Networking Security Hooks"
1259 select KERNEL_SECURITY
1261 config KERNEL_SECURITY_SELINUX
1262 bool "NSA SELinux Support"
1263 select KERNEL_SECURITY_NETWORK
1266 config KERNEL_SECURITY_SELINUX_BOOTPARAM
1267 bool "NSA SELinux boot parameter"
1268 depends on KERNEL_SECURITY_SELINUX
1271 config KERNEL_SECURITY_SELINUX_DISABLE
1272 bool "NSA SELinux runtime disable"
1273 depends on KERNEL_SECURITY_SELINUX
1275 config KERNEL_SECURITY_SELINUX_DEVELOP
1276 bool "NSA SELinux Development Support"
1277 depends on KERNEL_SECURITY_SELINUX
1280 config KERNEL_SECURITY_SELINUX_SIDTAB_HASH_BITS
1282 depends on KERNEL_SECURITY_SELINUX
1285 config KERNEL_SECURITY_SELINUX_SID2STR_CACHE_SIZE
1287 depends on KERNEL_SECURITY_SELINUX
1292 default "lockdown,yama,loadpin,safesetid,integrity,selinux"
1293 depends on KERNEL_SECURITY_SELINUX
1295 config KERNEL_EXT4_FS_SECURITY
1296 bool "Ext4 Security Labels"
1298 config KERNEL_F2FS_FS_SECURITY
1299 bool "F2FS Security Labels"
1301 config KERNEL_UBIFS_FS_SECURITY
1302 bool "UBIFS Security Labels"
1304 config KERNEL_JFFS2_FS_SECURITY
1305 bool "JFFS2 Security Labels"