1 # SPDX-License-Identifier: GPL-2.0-only
3 # Copyright (C) 2006-2014 OpenWrt.org
5 config KERNEL_BUILD_USER
6 string "Custom Kernel Build User Name"
7 default "builder" if BUILDBOT
10 Sets the Kernel build user string, which for example will be returned
11 by 'uname -a' on running systems.
12 If not set, uses system user at build time.
14 config KERNEL_BUILD_DOMAIN
15 string "Custom Kernel Build Domain Name"
16 default "buildhost" if BUILDBOT
19 Sets the Kernel build domain string, which for example will be
20 returned by 'uname -a' on running systems.
21 If not set, uses system hostname at build time.
24 bool "Enable support for printk"
28 bool "Support for paging of anonymous memory (swap)"
29 default y if !SMALL_FLASH
31 config KERNEL_PROC_STRIPPED
32 bool "Strip non-essential /proc functionality to reduce code size"
33 default y if SMALL_FLASH
35 config KERNEL_DEBUG_FS
36 bool "Compile the kernel with debug filesystem enabled"
39 debugfs is a virtual file system that kernel developers use to put
40 debugging files into. Enable this option to be able to read and
41 write to these files. Many common debugging facilities, such as
42 ftrace, require the existence of debugfs.
44 config KERNEL_MIPS_FP_SUPPORT
46 default y if TARGET_pistachio
51 depends on (arm || aarch64)
53 config KERNEL_X86_VSYSCALL_EMULATION
54 bool "Enable vsyscall emulation"
58 This enables emulation of the legacy vsyscall page. Disabling
59 it is roughly equivalent to booting with vsyscall=none, except
60 that it will also disable the helpful warning if a program
61 tries to use a vsyscall. With this option set to N, offending
62 programs will just segfault, citing addresses of the form
65 This option is required by many programs built before 2013, and
66 care should be used even with newer programs if set to N.
68 Disabling this option saves about 7K of kernel size and
69 possibly 4K of additional runtime pagetable memory.
71 config KERNEL_PERF_EVENTS
72 bool "Compile the kernel with performance events and counters"
74 select KERNEL_ARM_PMU if (arm || aarch64)
76 config KERNEL_PROFILING
77 bool "Compile the kernel with profiling enabled"
79 select KERNEL_PERF_EVENTS
81 Enable the extended profiling support mechanisms used by profilers such
84 config KERNEL_RPI_AXIPERF
85 bool "Compile the kernel with RaspberryPi AXI Performance monitors"
87 depends on KERNEL_PERF_EVENTS && TARGET_bcm27xx
90 bool "Compile the kernel with undefined behaviour sanity checker"
92 This option enables undefined behaviour sanity checker
93 Compile-time instrumentation is used to detect various undefined
94 behaviours in runtime. Various types of checks may be enabled
95 via boot parameter ubsan_handle
96 (see: Documentation/dev-tools/ubsan.rst).
98 config KERNEL_UBSAN_SANITIZE_ALL
99 bool "Enable instrumentation for the entire kernel"
100 depends on KERNEL_UBSAN
103 This option activates instrumentation for the entire kernel.
104 If you don't enable this option, you have to explicitly specify
105 UBSAN_SANITIZE := y for the files/directories you want to check for UB.
106 Enabling this option will get kernel image size increased
109 config KERNEL_UBSAN_ALIGNMENT
110 bool "Enable checking of pointers alignment"
111 depends on KERNEL_UBSAN
113 This option enables detection of unaligned memory accesses.
114 Enabling this option on architectures that support unaligned
115 accesses may produce a lot of false positives.
117 config KERNEL_UBSAN_BOUNDS
118 bool "Perform array index bounds checking"
119 depends on KERNEL_UBSAN
121 This option enables detection of directly indexed out of bounds array
122 accesses, where the array size is known at compile time. Note that
123 this does not protect array overflows via bad calls to the
124 {str,mem}*cpy() family of functions (that is addressed by
127 config KERNEL_UBSAN_NULL
128 bool "Enable checking of null pointers"
129 depends on KERNEL_UBSAN
131 This option enables detection of memory accesses via a
134 config KERNEL_UBSAN_TRAP
135 bool "On Sanitizer warnings, abort the running kernel code"
136 depends on KERNEL_UBSAN
138 Building kernels with Sanitizer features enabled tends to grow the
139 kernel size by around 5%, due to adding all the debugging text on
140 failure paths. To avoid this, Sanitizer instrumentation can just
141 issue a trap. This reduces the kernel size overhead but turns all
142 warnings (including potentially harmless conditions) into full
143 exceptions that abort the running kernel code (regardless of context,
144 locks held, etc), which may destabilize the system. For some system
145 builders this is an acceptable trade-off.
148 bool "Compile the kernel with KASan: runtime memory debugger"
149 select KERNEL_SLUB_DEBUG
150 depends on (x86_64 || aarch64)
152 Enables kernel address sanitizer - runtime memory debugger,
153 designed to find out-of-bounds accesses and use-after-free bugs.
154 This is strictly a debugging feature and it requires a gcc version
155 of 4.9.2 or later. Detection of out of bounds accesses to stack or
156 global variables requires gcc 5.0 or later.
157 This feature consumes about 1/8 of available memory and brings about
158 ~x3 performance slowdown.
159 For better error detection enable CONFIG_STACKTRACE.
160 Currently CONFIG_KASAN doesn't work with CONFIG_DEBUG_SLAB
161 (the resulting kernel does not boot).
163 config KERNEL_KASAN_EXTRA
164 bool "KAsan: extra checks"
165 depends on KERNEL_KASAN && KERNEL_DEBUG_KERNEL
167 This enables further checks in the kernel address sanitizer, for now
168 it only includes the address-use-after-scope check that can lead
169 to excessive kernel stack usage, frame size warnings and longer
171 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715 has more
173 config KERNEL_KASAN_VMALLOC
174 bool "Back mappings in vmalloc space with real shadow memory"
175 depends on KERNEL_KASAN
177 By default, the shadow region for vmalloc space is the read-only
178 zero page. This means that KASAN cannot detect errors involving
181 Enabling this option will hook in to vmap/vmalloc and back those
182 mappings with real shadow memory allocated on demand. This allows
183 for KASAN to detect more sorts of errors (and to support vmapped
184 stacks), but at the cost of higher memory usage.
186 This option depends on HAVE_ARCH_KASAN_VMALLOC, but we can't
187 depend on that in here, so it is possible that enabling this
191 config KERNEL_KASAN_GENERIC
194 config KERNEL_KASAN_SW_TAGS
199 prompt "Instrumentation type"
200 depends on KERNEL_KASAN
201 default KERNEL_KASAN_OUTLINE
203 config KERNEL_KASAN_OUTLINE
204 bool "Outline instrumentation"
206 Before every memory access compiler insert function call
207 __asan_load*/__asan_store*. These functions performs check
208 of shadow memory. This is slower than inline instrumentation,
209 however it doesn't bloat size of kernel's .text section so
212 config KERNEL_KASAN_INLINE
213 bool "Inline instrumentation"
215 Compiler directly inserts code checking shadow memory before
216 memory accesses. This is faster than outline (in some workloads
217 it gives about x2 boost over outline instrumentation), but
218 make kernel's .text size much bigger.
219 This requires a gcc version of 5.0 or later.
224 bool "Compile the kernel with code coverage for fuzzing"
225 select KERNEL_DEBUG_FS
227 KCOV exposes kernel code coverage information in a form suitable
228 for coverage-guided fuzzing (randomized testing).
230 If RANDOMIZE_BASE is enabled, PC values will not be stable across
231 different machines and across reboots. If you need stable PC values,
232 disable RANDOMIZE_BASE.
234 For more details, see Documentation/kcov.txt.
236 config KERNEL_KCOV_ENABLE_COMPARISONS
237 bool "Enable comparison operands collection by KCOV"
238 depends on KERNEL_KCOV
240 KCOV also exposes operands of every comparison in the instrumented
241 code along with operand sizes and PCs of the comparison instructions.
242 These operands can be used by fuzzing engines to improve the quality
245 config KERNEL_KCOV_INSTRUMENT_ALL
246 bool "Instrument all code by default"
247 depends on KERNEL_KCOV
248 default y if KERNEL_KCOV
250 If you are doing generic system call fuzzing (like e.g. syzkaller),
251 then you will want to instrument the whole kernel and you should
252 say y here. If you are doing more targeted fuzzing (like e.g.
253 filesystem fuzzing with AFL) then you will want to enable coverage
254 for more specific subsets of files, and should say n here.
256 config KERNEL_TASKSTATS
257 bool "Compile the kernel with task resource/io statistics and accounting"
260 Enable the collection and publishing of task/io statistics and
261 accounting. Enable this option to enable i/o monitoring in system
266 config KERNEL_TASK_DELAY_ACCT
269 config KERNEL_TASK_IO_ACCOUNTING
272 config KERNEL_TASK_XACCT
277 config KERNEL_KALLSYMS
278 bool "Compile the kernel with symbol table information"
279 default y if !SMALL_FLASH
281 This will give you more information in stack traces from kernel oopses.
284 bool "Compile the kernel with tracing support"
285 depends on !TARGET_uml
288 config KERNEL_FTRACE_SYSCALLS
289 bool "Trace system calls"
290 depends on KERNEL_FTRACE
293 config KERNEL_ENABLE_DEFAULT_TRACERS
294 bool "Trace process context switches and events"
295 depends on KERNEL_FTRACE
298 config KERNEL_FUNCTION_TRACER
299 bool "Function tracer"
300 depends on KERNEL_FTRACE
303 config KERNEL_FUNCTION_GRAPH_TRACER
304 bool "Function graph tracer"
305 depends on KERNEL_FUNCTION_TRACER
308 config KERNEL_DYNAMIC_FTRACE
309 bool "Enable/disable function tracing dynamically"
310 depends on KERNEL_FUNCTION_TRACER
313 config KERNEL_FUNCTION_PROFILER
314 bool "Function profiler"
315 depends on KERNEL_FUNCTION_TRACER
318 config KERNEL_IRQSOFF_TRACER
319 bool "Interrupts-off Latency Tracer"
320 depends on KERNEL_FTRACE
322 This option measures the time spent in irqs-off critical
323 sections, with microsecond accuracy.
325 The default measurement method is a maximum search, which is
326 disabled by default and can be runtime (re-)started
329 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
331 (Note that kernel size and overhead increase with this option
332 enabled. This option and the preempt-off timing option can be
333 used together or separately.)
335 config KERNEL_PREEMPT_TRACER
336 bool "Preemption-off Latency Tracer"
337 depends on KERNEL_FTRACE
339 This option measures the time spent in preemption-off critical
340 sections, with microsecond accuracy.
342 The default measurement method is a maximum search, which is
343 disabled by default and can be runtime (re-)started
346 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
348 (Note that kernel size and overhead increase with this option
349 enabled. This option and the irqs-off timing option can be
350 used together or separately.)
352 config KERNEL_HIST_TRIGGERS
353 bool "Histogram triggers"
354 depends on KERNEL_FTRACE
356 Hist triggers allow one or more arbitrary trace event fields to be
357 aggregated into hash tables and dumped to stdout by reading a
358 debugfs/tracefs file. They're useful for gathering quick and dirty
359 (though precise) summaries of event activity as an initial guide for
360 further investigation using more advanced tools.
362 Inter-event tracing of quantities such as latencies is also
363 supported using hist triggers under this option.
365 config KERNEL_DEBUG_KERNEL
369 config KERNEL_DEBUG_INFO
370 bool "Compile the kernel with debug information"
371 default y if !SMALL_FLASH
372 select KERNEL_DEBUG_KERNEL
374 This will compile your kernel and modules with debug information.
376 config KERNEL_DEBUG_INFO_BTF
378 bool "Enable additional BTF type information"
380 depends on !HOST_OS_MACOS
381 depends on KERNEL_DEBUG_INFO && !KERNEL_DEBUG_INFO_REDUCED
384 Generate BPF Type Format (BTF) information from DWARF debug info.
385 Turning this on expects presence of pahole tool, which will convert
386 DWARF type info into equivalent deduplicated BTF type info.
388 Required to run BPF CO-RE applications.
390 config KERNEL_DEBUG_INFO_REDUCED
391 bool "Reduce debugging information"
393 depends on KERNEL_DEBUG_INFO
395 If you say Y here gcc is instructed to generate less debugging
396 information for structure types. This means that tools that
397 need full debugging information (like kgdb or systemtap) won't
398 be happy. But if you merely need debugging information to
399 resolve line numbers there is no loss. Advantage is that
400 build directory object sizes shrink dramatically over a full
401 DEBUG_INFO build and compile times are reduced too.
402 Only works with newer gcc versions.
404 config KERNEL_DEBUG_LL_UART_NONE
409 config KERNEL_DEBUG_LL
413 select KERNEL_DEBUG_LL_UART_NONE
415 ARM low level debugging.
417 config KERNEL_DEBUG_VIRTUAL
418 bool "Compile the kernel with VM translations debugging"
419 select KERNEL_DEBUG_KERNEL
422 Enable checks sanity checks to catch invalid uses of
423 virt_to_phys()/phys_to_virt() against the non-linear address space.
425 config KERNEL_DYNAMIC_DEBUG
426 bool "Compile the kernel with dynamic printk"
427 select KERNEL_DEBUG_FS
430 Compiles debug level messages into the kernel, which would not
431 otherwise be available at runtime. These messages can then be
432 enabled/disabled based on various levels of scope - per source file,
433 function, module, format string, and line number. This mechanism
434 implicitly compiles in all pr_debug() and dev_dbg() calls, which
435 enlarges the kernel text size by about 2%.
437 config KERNEL_EARLY_PRINTK
438 bool "Compile the kernel with early printk"
439 default y if TARGET_bcm53xx
442 select KERNEL_DEBUG_KERNEL
443 select KERNEL_DEBUG_LL if arm
445 Compile the kernel with early printk support. This is only useful for
446 debugging purposes to send messages over the serial console in early boot.
447 Enable this to debug early boot problems.
449 config KERNEL_KPROBES
450 bool "Compile the kernel with kprobes support"
453 select KERNEL_PERF_EVENTS
455 Compiles the kernel with KPROBES support, which allows you to trap
456 at almost any kernel address and execute a callback function.
457 register_kprobe() establishes a probepoint and specifies the
458 callback. Kprobes is useful for kernel debugging, non-intrusive
459 instrumentation and testing.
460 If in doubt, say "N".
462 config KERNEL_KPROBE_EVENTS
464 default y if KERNEL_KPROBES
466 config KERNEL_BPF_EVENTS
467 bool "Compile the kernel with BPF event support"
469 select KERNEL_KPROBES
471 Allows to attach BPF programs to kprobe, uprobe and tracepoint events.
472 This is required to use BPF maps of type BPF_MAP_TYPE_PERF_EVENT_ARRAY
473 for sending data from BPF programs to user-space for post-processing
476 config KERNEL_BPF_KPROBE_OVERRIDE
479 depends on KERNEL_KPROBES
482 bool "Compile the kernel with asynchronous IO support"
483 default y if !SMALL_FLASH
485 config KERNEL_IO_URING
486 bool "Compile the kernel with io_uring support"
487 default y if !SMALL_FLASH
489 config KERNEL_FHANDLE
490 bool "Compile the kernel with support for fhandle syscalls"
491 default y if !SMALL_FLASH
493 config KERNEL_FANOTIFY
494 bool "Compile the kernel with modern file notification support"
495 default y if !SMALL_FLASH
497 config KERNEL_BLK_DEV_BSG
498 bool "Compile the kernel with SCSI generic v4 support for any block device"
501 config KERNEL_TRANSPARENT_HUGEPAGE
505 prompt "Transparent Hugepage Support sysfs defaults"
506 depends on KERNEL_TRANSPARENT_HUGEPAGE
507 default KERNEL_TRANSPARENT_HUGEPAGE_ALWAYS
509 config KERNEL_TRANSPARENT_HUGEPAGE_ALWAYS
512 config KERNEL_TRANSPARENT_HUGEPAGE_MADVISE
516 config KERNEL_HUGETLBFS
519 config KERNEL_HUGETLB_PAGE
520 bool "Compile the kernel with HugeTLB support"
521 select KERNEL_TRANSPARENT_HUGEPAGE
522 select KERNEL_HUGETLBFS
525 config KERNEL_MAGIC_SYSRQ
526 bool "Compile the kernel with SysRq support"
529 config KERNEL_DEBUG_PINCTRL
530 bool "Compile the kernel with pinctrl debugging"
531 select KERNEL_DEBUG_KERNEL
533 config KERNEL_DEBUG_GPIO
534 bool "Compile the kernel with gpio debugging"
535 select KERNEL_DEBUG_KERNEL
537 config KERNEL_COREDUMP
540 config KERNEL_ELF_CORE
541 bool "Enable process core dump support"
542 select KERNEL_COREDUMP
543 default y if !SMALL_FLASH
545 config KERNEL_PROVE_LOCKING
546 bool "Enable kernel lock checking"
547 select KERNEL_DEBUG_KERNEL
550 config KERNEL_SOFTLOCKUP_DETECTOR
551 bool "Compile the kernel with detect Soft Lockups"
552 depends on KERNEL_DEBUG_KERNEL
554 Say Y here to enable the kernel to act as a watchdog to detect
557 Softlockups are bugs that cause the kernel to loop in kernel
558 mode for more than 20 seconds, without giving other tasks a
559 chance to run. The current stack trace is displayed upon
560 detection and the system will stay locked up.
562 config KERNEL_DETECT_HUNG_TASK
563 bool "Compile the kernel with detect Hung Tasks"
564 depends on KERNEL_DEBUG_KERNEL
565 default KERNEL_SOFTLOCKUP_DETECTOR
567 Say Y here to enable the kernel to detect "hung tasks",
568 which are bugs that cause the task to be stuck in
569 uninterruptible "D" state indefinitely.
571 When a hung task is detected, the kernel will print the
572 current stack trace (which you should report), but the
573 task will stay in uninterruptible state. If lockdep is
574 enabled then all held locks will also be reported. This
575 feature has negligible overhead.
577 config KERNEL_WQ_WATCHDOG
578 bool "Compile the kernel with detect Workqueue Stalls"
579 depends on KERNEL_DEBUG_KERNEL
581 Say Y here to enable stall detection on workqueues. If a
582 worker pool doesn't make forward progress on a pending work
583 item for over a given amount of time, 30s by default, a
584 warning message is printed along with dump of workqueue
585 state. This can be configured through kernel parameter
586 "workqueue.watchdog_thresh" and its sysfs counterpart.
588 config KERNEL_DEBUG_ATOMIC_SLEEP
589 bool "Compile the kernel with sleep inside atomic section checking"
590 depends on KERNEL_DEBUG_KERNEL
592 If you say Y here, various routines which may sleep will become very
593 noisy if they are called inside atomic sections: when a spinlock is
594 held, inside an rcu read side critical section, inside preempt disabled
595 sections, inside an interrupt, etc...
597 config KERNEL_DEBUG_VM
598 bool "Compile the kernel with debug VM"
599 depends on KERNEL_DEBUG_KERNEL
601 Enable this to turn on extended checks in the virtual-memory system
602 that may impact performance.
606 config KERNEL_PRINTK_TIME
607 bool "Enable printk timestamps"
610 config KERNEL_SLUB_DEBUG
613 config KERNEL_SLUB_DEBUG_ON
616 config KERNEL_SLABINFO
617 select KERNEL_SLUB_DEBUG
618 select KERNEL_SLUB_DEBUG_ON
619 bool "Enable /proc slab debug info"
621 config KERNEL_PROC_PAGE_MONITOR
622 bool "Enable /proc page monitoring"
628 bool "Enable kexec support"
630 config KERNEL_PROC_VMCORE
633 config KERNEL_PROC_KCORE
636 config KERNEL_CRASH_DUMP
637 depends on i386 || x86_64 || arm || armeb
639 select KERNEL_PROC_VMCORE
640 select KERNEL_PROC_KCORE
641 bool "Enable support for kexec crashdump"
645 bool "Enable rfkill support"
646 default RFKILL_SUPPORT
649 bool "Enable sparse check during kernel build"
652 config KERNEL_DEVTMPFS
653 bool "Compile the kernel with device tmpfs enabled"
656 devtmpfs is a simple, kernel-managed /dev filesystem. The kernel creates
657 devices nodes for all registered devices to simplify boot, but leaves more
658 complex tasks to userspace (e.g. udev).
662 config KERNEL_DEVTMPFS_MOUNT
663 bool "Automatically mount devtmpfs after root filesystem is mounted"
669 bool "Enable kernel access key retention support"
672 config KERNEL_PERSISTENT_KEYRINGS
673 bool "Enable kernel persistent keyrings"
674 depends on KERNEL_KEYS
677 config KERNEL_KEYS_REQUEST_CACHE
678 bool "Enable temporary caching of the last request_key() result"
679 depends on KERNEL_KEYS
682 config KERNEL_BIG_KEYS
683 bool "Enable large payload keys on kernel keyrings"
684 depends on KERNEL_KEYS
688 # CGROUP support symbols
691 config KERNEL_CGROUPS
692 bool "Enable kernel cgroups"
693 default y if !SMALL_FLASH
697 config KERNEL_CGROUP_DEBUG
698 bool "Example debug cgroup subsystem"
701 This option enables a simple cgroup subsystem that
702 exports useful debugging information about the cgroups
705 config KERNEL_FREEZER
708 config KERNEL_CGROUP_FREEZER
709 bool "legacy Freezer cgroup subsystem"
711 select KERNEL_FREEZER
713 Provides a way to freeze and unfreeze all tasks in a
715 (legacy cgroup1-only controller, in cgroup2 freezer
716 is integrated in the Memory controller)
718 config KERNEL_CGROUP_DEVICE
719 bool "legacy Device controller for cgroups"
722 Provides a cgroup implementing whitelists for devices which
723 a process in the cgroup can mknod or open.
724 (legacy cgroup1-only controller)
726 config KERNEL_CGROUP_HUGETLB
727 bool "HugeTLB controller"
729 select KERNEL_HUGETLB_PAGE
731 config KERNEL_CGROUP_PIDS
732 bool "PIDs cgroup subsystem"
735 Provides enforcement of process number limits in the scope of a
738 config KERNEL_CGROUP_RDMA
739 bool "RDMA controller for cgroups"
742 config KERNEL_CGROUP_BPF
743 bool "Support for eBPF programs attached to cgroups"
746 config KERNEL_CPUSETS
747 bool "Cpuset support"
750 This option will let you create and manage CPUSETs which
751 allow dynamically partitioning a system into sets of CPUs and
752 Memory Nodes and assigning tasks to run only within those sets.
753 This is primarily useful on large SMP or NUMA systems.
755 config KERNEL_PROC_PID_CPUSET
756 bool "Include legacy /proc/<pid>/cpuset file"
758 depends on KERNEL_CPUSETS
760 config KERNEL_CGROUP_CPUACCT
761 bool "Simple CPU accounting cgroup subsystem"
764 Provides a simple Resource Controller for monitoring the
765 total CPU consumed by the tasks in a cgroup.
767 config KERNEL_RESOURCE_COUNTERS
768 bool "Resource counters"
771 This option enables controller independent resource accounting
772 infrastructure that works with cgroups.
774 config KERNEL_MM_OWNER
776 default y if KERNEL_MEMCG
779 bool "Memory Resource Controller for Control Groups"
781 select KERNEL_FREEZER
782 depends on KERNEL_RESOURCE_COUNTERS || !LINUX_3_18
784 Provides a memory resource controller that manages both anonymous
785 memory and page cache. (See Documentation/cgroups/memory.txt)
787 Note that setting this option increases fixed memory overhead
788 associated with each page of memory in the system. By this,
789 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
790 usage tracking struct at boot. Total amount of this is printed out
793 Only enable when you're ok with these tradeoffs and really
794 sure you need the memory resource controller. Even when you enable
795 this, you can set "cgroup_disable=memory" at your boot option to
796 disable memory resource controller and you can avoid overheads
797 (but lose benefits of memory resource controller).
799 This config option also selects MM_OWNER config option, which
800 could in turn add some fork/exit overhead.
802 config KERNEL_MEMCG_SWAP
803 bool "Memory Resource Controller Swap Extension"
805 depends on KERNEL_MEMCG
807 Add swap management feature to memory resource controller. When you
808 enable this, you can limit mem+swap usage per cgroup. In other words,
809 when you disable this, memory resource controller has no cares to
810 usage of swap...a process can exhaust all of the swap. This extension
811 is useful when you want to avoid exhaustion swap but this itself
812 adds more overheads and consumes memory for remembering information.
813 Especially if you use 32bit system or small memory system, please
814 be careful about enabling this. When memory resource controller
815 is disabled by boot option, this will be automatically disabled and
816 there will be no overhead from this. Even when you set this config=y,
817 if boot option "swapaccount=0" is set, swap will not be accounted.
818 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
819 size is 4096bytes, 512k per 1Gbytes of swap.
821 config KERNEL_MEMCG_SWAP_ENABLED
822 bool "Memory Resource Controller Swap Extension enabled by default"
824 depends on KERNEL_MEMCG_SWAP
826 Memory Resource Controller Swap Extension comes with its price in
827 a bigger memory consumption. General purpose distribution kernels
828 which want to enable the feature but keep it disabled by default
829 and let the user enable it by swapaccount boot command line
830 parameter should have this option unselected.
832 Those who want to have the feature enabled by default should
833 select this option (if, for some reason, they need to disable it,
834 then swapaccount=0 does the trick).
837 config KERNEL_MEMCG_KMEM
838 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
840 depends on KERNEL_MEMCG
842 The Kernel Memory extension for Memory Resource Controller can limit
843 the amount of memory used by kernel objects in the system. Those are
844 fundamentally different from the entities handled by the standard
845 Memory Controller, which are page-based, and can be swapped. Users of
846 the kmem extension can use it to guarantee that no group of processes
847 will ever exhaust kernel resources alone.
849 config KERNEL_CGROUP_PERF
850 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
851 select KERNEL_PERF_EVENTS
854 This option extends the per-cpu mode to restrict monitoring to
855 threads which belong to the cgroup specified and run on the
858 menuconfig KERNEL_CGROUP_SCHED
859 bool "Group CPU scheduler"
862 This feature lets CPU scheduler recognize task groups and control CPU
863 bandwidth allocation to such task groups. It uses cgroups to group
866 if KERNEL_CGROUP_SCHED
868 config KERNEL_FAIR_GROUP_SCHED
869 bool "Group scheduling for SCHED_OTHER"
872 config KERNEL_CFS_BANDWIDTH
873 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
875 depends on KERNEL_FAIR_GROUP_SCHED
877 This option allows users to define CPU bandwidth rates (limits) for
878 tasks running within the fair group scheduler. Groups with no limit
879 set are considered to be unconstrained and will run with no
881 See tip/Documentation/scheduler/sched-bwc.txt for more information.
883 config KERNEL_RT_GROUP_SCHED
884 bool "Group scheduling for SCHED_RR/FIFO"
887 This feature lets you explicitly allocate real CPU bandwidth
888 to task groups. If enabled, it will also make it impossible to
889 schedule realtime tasks for non-root users until you allocate
890 realtime bandwidth for them.
894 config KERNEL_BLK_CGROUP
895 bool "Block IO controller"
898 Generic block IO controller cgroup interface. This is the common
899 cgroup interface which should be used by various IO controlling
902 Currently, CFQ IO scheduler uses it to recognize task groups and
903 control disk bandwidth allocation (proportional time slice allocation)
904 to such task groups. It is also used by bio throttling logic in
905 block layer to implement upper limit in IO rates on a device.
907 This option only enables generic Block IO controller infrastructure.
908 One needs to also enable actual IO controlling logic/policy. For
909 enabling proportional weight division of disk bandwidth in CFQ, set
910 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
911 CONFIG_BLK_DEV_THROTTLING=y.
915 config KERNEL_CFQ_GROUP_IOSCHED
916 bool "Proportional weight of disk bandwidth in CFQ"
918 config KERNEL_BLK_DEV_THROTTLING
919 bool "Enable throttling policy"
922 config KERNEL_BLK_DEV_THROTTLING_LOW
923 bool "Block throttling .low limit interface support (EXPERIMENTAL)"
924 depends on KERNEL_BLK_DEV_THROTTLING
927 config KERNEL_DEBUG_BLK_CGROUP
928 bool "Enable Block IO controller debugging"
930 depends on KERNEL_BLK_CGROUP
932 Enable some debugging help. Currently it exports additional stat
933 files in a cgroup which can be useful for debugging.
935 config KERNEL_NET_CLS_CGROUP
936 bool "legacy Control Group Classifier"
939 config KERNEL_CGROUP_NET_CLASSID
940 bool "legacy Network classid cgroup"
943 config KERNEL_CGROUP_NET_PRIO
944 bool "legacy Network priority cgroup"
950 # Namespace support symbols
953 config KERNEL_NAMESPACES
954 bool "Enable kernel namespaces"
955 default y if !SMALL_FLASH
963 In this namespace, tasks see different info provided
964 with the uname() system call.
970 In this namespace, tasks work with IPC ids which correspond to
971 different IPC objects in different namespaces.
973 config KERNEL_USER_NS
974 bool "User namespace (EXPERIMENTAL)"
977 This allows containers, i.e. vservers, to use user namespaces
978 to provide different user info for different servers.
981 bool "PID Namespaces"
984 Support process id namespaces. This allows having multiple
985 processes with the same pid as long as they are in different
986 pid namespaces. This is a building block of containers.
989 bool "Network namespace"
992 Allow user space to create what appear to be multiple instances
993 of the network stack.
997 config KERNEL_DEVPTS_MULTIPLE_INSTANCES
998 bool "Support multiple instances of devpts"
999 default y if !SMALL_FLASH
1001 Enable support for multiple instances of devpts filesystem.
1002 If you want to have isolated PTY namespaces (eg: in containers),
1003 say Y here. Otherwise, say N. If enabled, each mount of devpts
1004 filesystem with the '-o newinstance' option will create an
1005 independent PTY namespace.
1007 config KERNEL_POSIX_MQUEUE
1008 bool "POSIX Message Queues"
1009 default y if !SMALL_FLASH
1011 POSIX variant of message queues is a part of IPC. In POSIX message
1012 queues every message has a priority which decides about succession
1013 of receiving it by a process. If you want to compile and run
1014 programs written e.g. for Solaris with use of its POSIX message
1015 queues (functions mq_*) say Y here.
1017 POSIX message queues are visible as a filesystem called 'mqueue'
1018 and can be mounted somewhere if you want to do filesystem
1019 operations on message queues.
1022 config KERNEL_SECCOMP_FILTER
1024 default y if !SMALL_FLASH
1026 config KERNEL_SECCOMP
1027 bool "Enable seccomp support"
1028 depends on !(TARGET_uml)
1029 select KERNEL_SECCOMP_FILTER
1030 default y if !SMALL_FLASH
1032 Build kernel with support for seccomp.
1035 # IPv4 configuration
1038 config KERNEL_IP_MROUTE
1039 bool "Enable IPv4 multicast routing"
1042 Multicast routing requires a multicast routing daemon in
1043 addition to kernel support.
1047 config KERNEL_IP_MROUTE_MULTIPLE_TABLES
1050 config KERNEL_IP_PIMSM_V1
1053 config KERNEL_IP_PIMSM_V2
1059 # IPv6 configuration
1067 config KERNEL_IPV6_MULTIPLE_TABLES
1070 config KERNEL_IPV6_SUBTREES
1073 config KERNEL_IPV6_MROUTE
1074 bool "Enable IPv6 multicast routing"
1077 Multicast routing requires a multicast routing daemon in
1078 addition to kernel support.
1080 if KERNEL_IPV6_MROUTE
1082 config KERNEL_IPV6_MROUTE_MULTIPLE_TABLES
1085 config KERNEL_IPV6_PIMSM_V2
1090 config KERNEL_IPV6_SEG6_LWTUNNEL
1091 bool "Enable support for lightweight tunnels"
1092 default y if !SMALL_FLASH
1094 Using lwtunnel (needed for IPv6 segment routing) requires ip-full package.
1096 config KERNEL_LWTUNNEL_BPF
1102 # Miscellaneous network configuration
1105 config KERNEL_NET_L3_MASTER_DEV
1106 bool "L3 Master device support"
1108 This module provides glue between core networking code and device
1109 drivers to support L3 master devices like VRF.
1111 config KERNEL_WIRELESS_EXT
1114 config KERNEL_WEXT_CORE
1115 def_bool KERNEL_WIRELESS_EXT
1117 config KERNEL_WEXT_PRIV
1118 def_bool KERNEL_WIRELESS_EXT
1120 config KERNEL_WEXT_PROC
1121 def_bool KERNEL_WIRELESS_EXT
1123 config KERNEL_WEXT_SPY
1124 def_bool KERNEL_WIRELESS_EXT
1128 # NFS related symbols
1130 config KERNEL_IP_PNP
1131 bool "Compile the kernel with rootfs on NFS"
1133 If you want to make your kernel boot off a NFS server as root
1134 filesystem, select Y here.
1138 config KERNEL_IP_PNP_DHCP
1141 config KERNEL_IP_PNP_BOOTP
1144 config KERNEL_IP_PNP_RARP
1147 config KERNEL_NFS_FS
1150 config KERNEL_NFS_V2
1153 config KERNEL_NFS_V3
1156 config KERNEL_ROOT_NFS
1161 menu "Filesystem ACL and attr support options"
1162 config USE_FS_ACL_ATTR
1163 bool "Use filesystem ACL and attr support by default"
1166 Make using ACLs (e.g. POSIX ACL, NFSv4 ACL) the default
1167 for kernel and packages, except tmpfs, flash filesystems,
1168 and old NFS. Also enable userspace extended attribute support
1169 by default. (OpenWrt already has an expection it will be
1170 present in the kernel).
1172 config KERNEL_FS_POSIX_ACL
1173 bool "Enable POSIX ACL support"
1174 default y if USE_FS_ACL_ATTR
1176 config KERNEL_BTRFS_FS_POSIX_ACL
1177 bool "Enable POSIX ACL for BtrFS Filesystems"
1178 select KERNEL_FS_POSIX_ACL
1179 default y if USE_FS_ACL_ATTR
1181 config KERNEL_EXT4_FS_POSIX_ACL
1182 bool "Enable POSIX ACL for Ext4 Filesystems"
1183 select KERNEL_FS_POSIX_ACL
1184 default y if USE_FS_ACL_ATTR
1186 config KERNEL_F2FS_FS_POSIX_ACL
1187 bool "Enable POSIX ACL for F2FS Filesystems"
1188 select KERNEL_FS_POSIX_ACL
1191 config KERNEL_JFFS2_FS_POSIX_ACL
1192 bool "Enable POSIX ACL for JFFS2 Filesystems"
1193 select KERNEL_FS_POSIX_ACL
1196 config KERNEL_TMPFS_POSIX_ACL
1197 bool "Enable POSIX ACL for TMPFS Filesystems"
1198 select KERNEL_FS_POSIX_ACL
1201 config KERNEL_CIFS_ACL
1202 bool "Enable CIFS ACLs"
1203 select KERNEL_FS_POSIX_ACL
1204 default y if USE_FS_ACL_ATTR
1206 config KERNEL_HFS_FS_POSIX_ACL
1207 bool "Enable POSIX ACL for HFS Filesystems"
1208 select KERNEL_FS_POSIX_ACL
1209 default y if USE_FS_ACL_ATTR
1211 config KERNEL_HFSPLUS_FS_POSIX_ACL
1212 bool "Enable POSIX ACL for HFS+ Filesystems"
1213 select KERNEL_FS_POSIX_ACL
1214 default y if USE_FS_ACL_ATTR
1216 config KERNEL_NFS_ACL_SUPPORT
1217 bool "Enable ACLs for NFS"
1218 default y if USE_FS_ACL_ATTR
1220 config KERNEL_NFS_V3_ACL_SUPPORT
1221 bool "Enable ACLs for NFSv3"
1224 config KERNEL_NFSD_V2_ACL_SUPPORT
1225 bool "Enable ACLs for NFSDv2"
1228 config KERNEL_NFSD_V3_ACL_SUPPORT
1229 bool "Enable ACLs for NFSDv3"
1232 config KERNEL_REISER_FS_POSIX_ACL
1233 bool "Enable POSIX ACLs for ReiserFS"
1234 select KERNEL_FS_POSIX_ACL
1235 default y if USE_FS_ACL_ATTR
1237 config KERNEL_XFS_POSIX_ACL
1238 bool "Enable POSIX ACLs for XFS"
1239 select KERNEL_FS_POSIX_ACL
1240 default y if USE_FS_ACL_ATTR
1242 config KERNEL_JFS_POSIX_ACL
1243 bool "Enable POSIX ACLs for JFS"
1244 select KERNEL_FS_POSIX_ACL
1245 default y if USE_FS_ACL_ATTR
1249 config KERNEL_DEVMEM
1250 bool "/dev/mem virtual device support"
1252 Say Y here if you want to support the /dev/mem device.
1253 The /dev/mem device is used to access areas of physical
1256 config KERNEL_DEVKMEM
1257 bool "/dev/kmem virtual device support"
1259 Say Y here if you want to support the /dev/kmem device. The
1260 /dev/kmem device is rarely used, but can be used for certain
1261 kind of kernel debugging operations.
1263 config KERNEL_SQUASHFS_FRAGMENT_CACHE_SIZE
1264 int "Number of squashfs fragments cached"
1265 default 2 if (SMALL_FLASH && !LOW_MEMORY_FOOTPRINT)
1268 config KERNEL_SQUASHFS_XATTR
1269 bool "Squashfs XATTR support"
1272 # compile optimization setting
1275 prompt "Compiler optimization level"
1276 default KERNEL_CC_OPTIMIZE_FOR_SIZE if SMALL_FLASH
1278 config KERNEL_CC_OPTIMIZE_FOR_PERFORMANCE
1279 bool "Optimize for performance"
1281 This is the default optimization level for the kernel, building
1282 with the "-O2" compiler flag for best performance and most
1283 helpful compile-time warnings.
1285 config KERNEL_CC_OPTIMIZE_FOR_SIZE
1286 bool "Optimize for size"
1288 Enabling this option will pass "-Os" instead of "-O2" to
1289 your compiler resulting in a smaller kernel.
1294 bool "Auditing support"
1296 config KERNEL_SECURITY
1297 bool "Enable different security models"
1299 config KERNEL_SECURITY_NETWORK
1300 bool "Socket and Networking Security Hooks"
1301 select KERNEL_SECURITY
1303 config KERNEL_SECURITY_SELINUX
1304 bool "NSA SELinux Support"
1305 select KERNEL_SECURITY_NETWORK
1308 config KERNEL_SECURITY_SELINUX_BOOTPARAM
1309 bool "NSA SELinux boot parameter"
1310 depends on KERNEL_SECURITY_SELINUX
1313 config KERNEL_SECURITY_SELINUX_DISABLE
1314 bool "NSA SELinux runtime disable"
1315 depends on KERNEL_SECURITY_SELINUX
1317 config KERNEL_SECURITY_SELINUX_DEVELOP
1318 bool "NSA SELinux Development Support"
1319 depends on KERNEL_SECURITY_SELINUX
1322 config KERNEL_SECURITY_SELINUX_SIDTAB_HASH_BITS
1324 depends on KERNEL_SECURITY_SELINUX
1327 config KERNEL_SECURITY_SELINUX_SID2STR_CACHE_SIZE
1329 depends on KERNEL_SECURITY_SELINUX
1334 default "lockdown,yama,loadpin,safesetid,integrity,selinux"
1335 depends on KERNEL_SECURITY_SELINUX
1337 config KERNEL_EXT4_FS_SECURITY
1338 bool "Ext4 Security Labels"
1340 config KERNEL_F2FS_FS_SECURITY
1341 bool "F2FS Security Labels"
1343 config KERNEL_UBIFS_FS_SECURITY
1344 bool "UBIFS Security Labels"
1346 config KERNEL_JFFS2_FS_SECURITY
1347 bool "JFFS2 Security Labels"