build: Add additional kernel debug options
[openwrt/staging/wigyori.git] / config / Config-kernel.in
1 # Copyright (C) 2006-2014 OpenWrt.org
2 #
3 # This is free software, licensed under the GNU General Public License v2.
4 # See /LICENSE for more information.
5 #
6
7 config KERNEL_BUILD_USER
8 string "Custom Kernel Build User Name"
9 default "builder" if BUILDBOT
10 default ""
11 help
12 Sets the Kernel build user string, which for example will be returned
13 by 'uname -a' on running systems.
14 If not set, uses system user at build time.
15
16 config KERNEL_BUILD_DOMAIN
17 string "Custom Kernel Build Domain Name"
18 default "buildhost" if BUILDBOT
19 default ""
20 help
21 Sets the Kernel build domain string, which for example will be
22 returned by 'uname -a' on running systems.
23 If not set, uses system hostname at build time.
24
25 config KERNEL_PRINTK
26 bool "Enable support for printk"
27 default y
28
29 config KERNEL_CRASHLOG
30 bool "Crash logging"
31 depends on !(arm || powerpc || sparc || TARGET_uml || i386 || x86_64)
32 default y
33
34 config KERNEL_SWAP
35 bool "Support for paging of anonymous memory (swap)"
36 default y if !SMALL_FLASH
37
38 config KERNEL_DEBUG_FS
39 bool "Compile the kernel with debug filesystem enabled"
40 default y
41 help
42 debugfs is a virtual file system that kernel developers use to put
43 debugging files into. Enable this option to be able to read and
44 write to these files. Many common debugging facilities, such as
45 ftrace, require the existence of debugfs.
46
47 config KERNEL_MIPS_FPU_EMULATOR
48 bool "Compile the kernel with MIPS FPU Emulator"
49 default y if TARGET_pistachio
50 depends on (mips || mipsel || mips64 || mips64el)
51
52 config KERNEL_ARM_PMU
53 bool
54 default n
55 depends on (arm || aarch64)
56
57 config KERNEL_X86_VSYSCALL_EMULATION
58 bool "Enable vsyscall emulation"
59 default n
60 depends on x86_64
61 help
62 This enables emulation of the legacy vsyscall page. Disabling
63 it is roughly equivalent to booting with vsyscall=none, except
64 that it will also disable the helpful warning if a program
65 tries to use a vsyscall. With this option set to N, offending
66 programs will just segfault, citing addresses of the form
67 0xffffffffff600?00.
68
69 This option is required by many programs built before 2013, and
70 care should be used even with newer programs if set to N.
71
72 Disabling this option saves about 7K of kernel size and
73 possibly 4K of additional runtime pagetable memory.
74
75 config KERNEL_PERF_EVENTS
76 bool "Compile the kernel with performance events and counters"
77 default n
78 select KERNEL_ARM_PMU if (arm || aarch64)
79
80 config KERNEL_PROFILING
81 bool "Compile the kernel with profiling enabled"
82 default n
83 select KERNEL_PERF_EVENTS
84 help
85 Enable the extended profiling support mechanisms used by profilers such
86 as OProfile.
87
88 config KERNEL_UBSAN
89 bool "Compile the kernel with undefined behaviour sanity checker"
90 help
91 This option enables undefined behaviour sanity checker
92 Compile-time instrumentation is used to detect various undefined
93 behaviours in runtime. Various types of checks may be enabled
94 via boot parameter ubsan_handle
95 (see: Documentation/dev-tools/ubsan.rst).
96
97 config KERNEL_UBSAN_SANITIZE_ALL
98 bool "Enable instrumentation for the entire kernel"
99 depends on KERNEL_UBSAN
100 default y
101 help
102 This option activates instrumentation for the entire kernel.
103 If you don't enable this option, you have to explicitly specify
104 UBSAN_SANITIZE := y for the files/directories you want to check for UB.
105 Enabling this option will get kernel image size increased
106 significantly.
107
108 config KERNEL_UBSAN_ALIGNMENT
109 bool "Enable checking of pointers alignment"
110 depends on KERNEL_UBSAN
111 help
112 This option enables detection of unaligned memory accesses.
113 Enabling this option on architectures that support unaligned
114 accesses may produce a lot of false positives.
115
116 config KERNEL_UBSAN_NULL
117 bool "Enable checking of null pointers"
118 depends on KERNEL_UBSAN
119 help
120 This option enables detection of memory accesses via a
121 null pointer.
122
123 config KERNEL_KASAN
124 bool "Compile the kernel with KASan: runtime memory debugger"
125 select KERNEL_SLUB_DEBUG
126 depends on (x86_64 || aarch64)
127 help
128 Enables kernel address sanitizer - runtime memory debugger,
129 designed to find out-of-bounds accesses and use-after-free bugs.
130 This is strictly a debugging feature and it requires a gcc version
131 of 4.9.2 or later. Detection of out of bounds accesses to stack or
132 global variables requires gcc 5.0 or later.
133 This feature consumes about 1/8 of available memory and brings about
134 ~x3 performance slowdown.
135 For better error detection enable CONFIG_STACKTRACE.
136 Currently CONFIG_KASAN doesn't work with CONFIG_DEBUG_SLAB
137 (the resulting kernel does not boot).
138
139 config KERNEL_KASAN_EXTRA
140 bool "KAsan: extra checks"
141 depends on KERNEL_KASAN && KERNEL_DEBUG_KERNEL
142 help
143 This enables further checks in the kernel address sanitizer, for now
144 it only includes the address-use-after-scope check that can lead
145 to excessive kernel stack usage, frame size warnings and longer
146 compile time.
147 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715 has more
148
149
150 choice
151 prompt "Instrumentation type"
152 depends on KERNEL_KASAN
153 default KERNEL_KASAN_OUTLINE
154
155 config KERNEL_KASAN_OUTLINE
156 bool "Outline instrumentation"
157 help
158 Before every memory access compiler insert function call
159 __asan_load*/__asan_store*. These functions performs check
160 of shadow memory. This is slower than inline instrumentation,
161 however it doesn't bloat size of kernel's .text section so
162 much as inline does.
163
164 config KERNEL_KASAN_INLINE
165 bool "Inline instrumentation"
166 help
167 Compiler directly inserts code checking shadow memory before
168 memory accesses. This is faster than outline (in some workloads
169 it gives about x2 boost over outline instrumentation), but
170 make kernel's .text size much bigger.
171 This requires a gcc version of 5.0 or later.
172
173 endchoice
174
175 config KERNEL_KCOV
176 bool "Compile the kernel with code coverage for fuzzing"
177 select KERNEL_DEBUG_FS
178 help
179 KCOV exposes kernel code coverage information in a form suitable
180 for coverage-guided fuzzing (randomized testing).
181
182 If RANDOMIZE_BASE is enabled, PC values will not be stable across
183 different machines and across reboots. If you need stable PC values,
184 disable RANDOMIZE_BASE.
185
186 For more details, see Documentation/kcov.txt.
187
188 config KERNEL_KCOV_ENABLE_COMPARISONS
189 bool "Enable comparison operands collection by KCOV"
190 depends on KERNEL_KCOV
191 help
192 KCOV also exposes operands of every comparison in the instrumented
193 code along with operand sizes and PCs of the comparison instructions.
194 These operands can be used by fuzzing engines to improve the quality
195 of fuzzing coverage.
196
197 config KERNEL_KCOV_INSTRUMENT_ALL
198 bool "Instrument all code by default"
199 depends on KERNEL_KCOV
200 default y if KERNEL_KCOV
201 help
202 If you are doing generic system call fuzzing (like e.g. syzkaller),
203 then you will want to instrument the whole kernel and you should
204 say y here. If you are doing more targeted fuzzing (like e.g.
205 filesystem fuzzing with AFL) then you will want to enable coverage
206 for more specific subsets of files, and should say n here.
207
208 config KERNEL_TASKSTATS
209 bool "Compile the kernel with task resource/io statistics and accounting"
210 default n
211 help
212 Enable the collection and publishing of task/io statistics and
213 accounting. Enable this option to enable i/o monitoring in system
214 monitors.
215
216 if KERNEL_TASKSTATS
217
218 config KERNEL_TASK_DELAY_ACCT
219 def_bool y
220
221 config KERNEL_TASK_IO_ACCOUNTING
222 def_bool y
223
224 config KERNEL_TASK_XACCT
225 def_bool y
226
227 endif
228
229 config KERNEL_KALLSYMS
230 bool "Compile the kernel with symbol table information"
231 default y if !SMALL_FLASH
232 help
233 This will give you more information in stack traces from kernel oopses.
234
235 config KERNEL_FTRACE
236 bool "Compile the kernel with tracing support"
237 depends on !TARGET_uml
238 default n
239
240 config KERNEL_FTRACE_SYSCALLS
241 bool "Trace system calls"
242 depends on KERNEL_FTRACE
243 default n
244
245 config KERNEL_ENABLE_DEFAULT_TRACERS
246 bool "Trace process context switches and events"
247 depends on KERNEL_FTRACE
248 default n
249
250 config KERNEL_FUNCTION_TRACER
251 bool "Function tracer"
252 depends on KERNEL_FTRACE
253 default n
254
255 config KERNEL_FUNCTION_GRAPH_TRACER
256 bool "Function graph tracer"
257 depends on KERNEL_FUNCTION_TRACER
258 default n
259
260 config KERNEL_DYNAMIC_FTRACE
261 bool "Enable/disable function tracing dynamically"
262 depends on KERNEL_FUNCTION_TRACER
263 default n
264
265 config KERNEL_FUNCTION_PROFILER
266 bool "Function profiler"
267 depends on KERNEL_FUNCTION_TRACER
268 default n
269
270 config KERNEL_DEBUG_KERNEL
271 bool
272 default n
273
274 config KERNEL_DEBUG_INFO
275 bool "Compile the kernel with debug information"
276 default y if !SMALL_FLASH
277 select KERNEL_DEBUG_KERNEL
278 help
279 This will compile your kernel and modules with debug information.
280
281 config KERNEL_DEBUG_LL_UART_NONE
282 bool
283 default n
284 depends on arm
285
286 config KERNEL_DEBUG_LL
287 bool
288 default n
289 depends on arm
290 select KERNEL_DEBUG_LL_UART_NONE
291 help
292 ARM low level debugging.
293
294 config KERNEL_DYNAMIC_DEBUG
295 bool "Compile the kernel with dynamic printk"
296 select KERNEL_DEBUG_FS
297 default n
298 help
299 Compiles debug level messages into the kernel, which would not
300 otherwise be available at runtime. These messages can then be
301 enabled/disabled based on various levels of scope - per source file,
302 function, module, format string, and line number. This mechanism
303 implicitly compiles in all pr_debug() and dev_dbg() calls, which
304 enlarges the kernel text size by about 2%.
305
306 config KERNEL_EARLY_PRINTK
307 bool "Compile the kernel with early printk"
308 default y if TARGET_bcm53xx
309 default n
310 depends on arm
311 select KERNEL_DEBUG_KERNEL
312 select KERNEL_DEBUG_LL if arm
313 help
314 Compile the kernel with early printk support. This is only useful for
315 debugging purposes to send messages over the serial console in early boot.
316 Enable this to debug early boot problems.
317
318 config KERNEL_KPROBES
319 bool "Compile the kernel with kprobes support"
320 default n
321 select KERNEL_FTRACE
322 select KERNEL_PERF_EVENTS
323 help
324 Compiles the kernel with KPROBES support, which allows you to trap
325 at almost any kernel address and execute a callback function.
326 register_kprobe() establishes a probepoint and specifies the
327 callback. Kprobes is useful for kernel debugging, non-intrusive
328 instrumentation and testing.
329 If in doubt, say "N".
330
331 config KERNEL_KPROBE_EVENT
332 bool
333 default y if KERNEL_KPROBES
334
335 config KERNEL_KPROBE_EVENTS
336 bool
337 default y if KERNEL_KPROBES
338
339 config KERNEL_AIO
340 bool "Compile the kernel with asynchronous IO support"
341 default y if !SMALL_FLASH
342
343 config KERNEL_FHANDLE
344 bool "Compile the kernel with support for fhandle syscalls"
345 default y if !SMALL_FLASH
346
347 config KERNEL_FANOTIFY
348 bool "Compile the kernel with modern file notification support"
349 default y if !SMALL_FLASH
350
351 config KERNEL_BLK_DEV_BSG
352 bool "Compile the kernel with SCSI generic v4 support for any block device"
353 default n
354
355 config KERNEL_MAGIC_SYSRQ
356 bool "Compile the kernel with SysRq support"
357 default y
358
359 config KERNEL_DEBUG_PINCTRL
360 bool "Compile the kernel with pinctrl debugging"
361 select KERNEL_DEBUG_KERNEL
362
363 config KERNEL_DEBUG_GPIO
364 bool "Compile the kernel with gpio debugging"
365 select KERNEL_DEBUG_KERNEL
366
367 config KERNEL_COREDUMP
368 bool
369
370 config KERNEL_ELF_CORE
371 bool "Enable process core dump support"
372 select KERNEL_COREDUMP
373 default y if !SMALL_FLASH
374
375 config KERNEL_PROVE_LOCKING
376 bool "Enable kernel lock checking"
377 select KERNEL_DEBUG_KERNEL
378 default n
379
380 config KERNEL_LOCKUP_DETECTOR
381 bool "Compile the kernel with detect Hard and Soft Lockups"
382 depends on KERNEL_DEBUG_KERNEL
383 help
384 Say Y here to enable the kernel to act as a watchdog to detect
385 hard and soft lockups.
386
387 Softlockups are bugs that cause the kernel to loop in kernel
388 mode for more than 20 seconds, without giving other tasks a
389 chance to run. The current stack trace is displayed upon
390 detection and the system will stay locked up.
391
392 Hardlockups are bugs that cause the CPU to loop in kernel mode
393 for more than 10 seconds, without letting other interrupts have a
394 chance to run. The current stack trace is displayed upon detection
395 and the system will stay locked up.
396
397 The overhead should be minimal. A periodic hrtimer runs to
398 generate interrupts and kick the watchdog task every 4 seconds.
399 An NMI is generated every 10 seconds or so to check for hardlockups.
400
401 The frequency of hrtimer and NMI events and the soft and hard lockup
402 thresholds can be controlled through the sysctl watchdog_thresh.
403
404 config KERNEL_DETECT_HUNG_TASK
405 bool "Compile the kernel with detect Hung Tasks"
406 depends on KERNEL_DEBUG_KERNEL
407 default KERNEL_LOCKUP_DETECTOR
408 help
409 Say Y here to enable the kernel to detect "hung tasks",
410 which are bugs that cause the task to be stuck in
411 uninterruptible "D" state indefinitely.
412
413 When a hung task is detected, the kernel will print the
414 current stack trace (which you should report), but the
415 task will stay in uninterruptible state. If lockdep is
416 enabled then all held locks will also be reported. This
417 feature has negligible overhead.
418
419 config KERNEL_WQ_WATCHDOG
420 bool "Compile the kernel with detect Workqueue Stalls"
421 depends on KERNEL_DEBUG_KERNEL
422 help
423 Say Y here to enable stall detection on workqueues. If a
424 worker pool doesn't make forward progress on a pending work
425 item for over a given amount of time, 30s by default, a
426 warning message is printed along with dump of workqueue
427 state. This can be configured through kernel parameter
428 "workqueue.watchdog_thresh" and its sysfs counterpart.
429
430 config KERNEL_DEBUG_ATOMIC_SLEEP
431 bool "Compile the kernel with sleep inside atomic section checking"
432 depends on KERNEL_DEBUG_KERNEL
433 help
434 If you say Y here, various routines which may sleep will become very
435 noisy if they are called inside atomic sections: when a spinlock is
436 held, inside an rcu read side critical section, inside preempt disabled
437 sections, inside an interrupt, etc...
438
439 config KERNEL_DEBUG_VM
440 bool "Compile the kernel with debug VM"
441 depends on KERNEL_DEBUG_KERNEL
442 help
443 Enable this to turn on extended checks in the virtual-memory system
444 that may impact performance.
445
446 If unsure, say N.
447
448 config KERNEL_PRINTK_TIME
449 bool "Enable printk timestamps"
450 default y
451
452 config KERNEL_SLUB_DEBUG
453 bool
454
455 config KERNEL_SLUB_DEBUG_ON
456 bool
457
458 config KERNEL_SLABINFO
459 select KERNEL_SLUB_DEBUG
460 select KERNEL_SLUB_DEBUG_ON
461 bool "Enable /proc slab debug info"
462
463 config KERNEL_PROC_PAGE_MONITOR
464 bool "Enable /proc page monitoring"
465
466 config KERNEL_RELAY
467 bool
468
469 config KERNEL_KEXEC
470 bool "Enable kexec support"
471
472 config KERNEL_PROC_VMCORE
473 bool
474
475 config KERNEL_CRASH_DUMP
476 depends on i386 || x86_64 || arm || armeb
477 select KERNEL_KEXEC
478 select KERNEL_PROC_VMCORE
479 bool "Enable support for kexec crashdump"
480 default y
481
482 config USE_RFKILL
483 bool "Enable rfkill support"
484 default RFKILL_SUPPORT
485
486 config USE_SPARSE
487 bool "Enable sparse check during kernel build"
488 default n
489
490 config KERNEL_DEVTMPFS
491 bool "Compile the kernel with device tmpfs enabled"
492 default n
493 help
494 devtmpfs is a simple, kernel-managed /dev filesystem. The kernel creates
495 devices nodes for all registered devices to simplify boot, but leaves more
496 complex tasks to userspace (e.g. udev).
497
498 if KERNEL_DEVTMPFS
499
500 config KERNEL_DEVTMPFS_MOUNT
501 bool "Automatically mount devtmpfs after root filesystem is mounted"
502 default n
503
504 endif
505
506 config KERNEL_KEYS
507 bool "Enable kernel access key retention support"
508 default n
509
510 config KERNEL_PERSISTENT_KEYRINGS
511 bool "Enable kernel persistent keyrings"
512 depends on KERNEL_KEYS
513 default n
514
515 config KERNEL_BIG_KEYS
516 bool "Enable large payload keys on kernel keyrings"
517 depends on KERNEL_KEYS
518 default n
519
520 config KERNEL_ENCRYPTED_KEYS
521 tristate "Enable keys with encrypted payloads on kernel keyrings"
522 depends on KERNEL_KEYS
523 default n
524
525 #
526 # CGROUP support symbols
527 #
528
529 config KERNEL_CGROUPS
530 bool "Enable kernel cgroups"
531 default y if !SMALL_FLASH
532
533 if KERNEL_CGROUPS
534
535 config KERNEL_CGROUP_DEBUG
536 bool "Example debug cgroup subsystem"
537 default n
538 help
539 This option enables a simple cgroup subsystem that
540 exports useful debugging information about the cgroups
541 framework.
542
543 config KERNEL_FREEZER
544 bool
545 default y if KERNEL_CGROUP_FREEZER
546
547 config KERNEL_CGROUP_FREEZER
548 bool "Freezer cgroup subsystem"
549 default y
550 help
551 Provides a way to freeze and unfreeze all tasks in a
552 cgroup.
553
554 config KERNEL_CGROUP_DEVICE
555 bool "Device controller for cgroups"
556 default y
557 help
558 Provides a cgroup implementing whitelists for devices which
559 a process in the cgroup can mknod or open.
560
561 config KERNEL_CGROUP_PIDS
562 bool "PIDs cgroup subsystem"
563 default y
564 help
565 Provides enforcement of process number limits in the scope of a
566 cgroup.
567
568 config KERNEL_CPUSETS
569 bool "Cpuset support"
570 default y if !SMALL_FLASH
571 help
572 This option will let you create and manage CPUSETs which
573 allow dynamically partitioning a system into sets of CPUs and
574 Memory Nodes and assigning tasks to run only within those sets.
575 This is primarily useful on large SMP or NUMA systems.
576
577 config KERNEL_PROC_PID_CPUSET
578 bool "Include legacy /proc/<pid>/cpuset file"
579 default n
580 depends on KERNEL_CPUSETS
581
582 config KERNEL_CGROUP_CPUACCT
583 bool "Simple CPU accounting cgroup subsystem"
584 default y if !SMALL_FLASH
585 help
586 Provides a simple Resource Controller for monitoring the
587 total CPU consumed by the tasks in a cgroup.
588
589 config KERNEL_RESOURCE_COUNTERS
590 bool "Resource counters"
591 default y if !SMALL_FLASH
592 help
593 This option enables controller independent resource accounting
594 infrastructure that works with cgroups.
595
596 config KERNEL_MM_OWNER
597 bool
598 default y if KERNEL_MEMCG
599
600 config KERNEL_MEMCG
601 bool "Memory Resource Controller for Control Groups"
602 default y if !SMALL_FLASH
603 depends on KERNEL_RESOURCE_COUNTERS || !LINUX_3_18
604 help
605 Provides a memory resource controller that manages both anonymous
606 memory and page cache. (See Documentation/cgroups/memory.txt)
607
608 Note that setting this option increases fixed memory overhead
609 associated with each page of memory in the system. By this,
610 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
611 usage tracking struct at boot. Total amount of this is printed out
612 at boot.
613
614 Only enable when you're ok with these tradeoffs and really
615 sure you need the memory resource controller. Even when you enable
616 this, you can set "cgroup_disable=memory" at your boot option to
617 disable memory resource controller and you can avoid overheads
618 (but lose benefits of memory resource controller).
619
620 This config option also selects MM_OWNER config option, which
621 could in turn add some fork/exit overhead.
622
623 config KERNEL_MEMCG_SWAP
624 bool "Memory Resource Controller Swap Extension"
625 default n
626 depends on KERNEL_MEMCG
627 help
628 Add swap management feature to memory resource controller. When you
629 enable this, you can limit mem+swap usage per cgroup. In other words,
630 when you disable this, memory resource controller has no cares to
631 usage of swap...a process can exhaust all of the swap. This extension
632 is useful when you want to avoid exhaustion swap but this itself
633 adds more overheads and consumes memory for remembering information.
634 Especially if you use 32bit system or small memory system, please
635 be careful about enabling this. When memory resource controller
636 is disabled by boot option, this will be automatically disabled and
637 there will be no overhead from this. Even when you set this config=y,
638 if boot option "swapaccount=0" is set, swap will not be accounted.
639 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
640 size is 4096bytes, 512k per 1Gbytes of swap.
641
642 config KERNEL_MEMCG_SWAP_ENABLED
643 bool "Memory Resource Controller Swap Extension enabled by default"
644 default n
645 depends on KERNEL_MEMCG_SWAP
646 help
647 Memory Resource Controller Swap Extension comes with its price in
648 a bigger memory consumption. General purpose distribution kernels
649 which want to enable the feature but keep it disabled by default
650 and let the user enable it by swapaccount boot command line
651 parameter should have this option unselected.
652
653 Those who want to have the feature enabled by default should
654 select this option (if, for some reason, they need to disable it,
655 then swapaccount=0 does the trick).
656
657
658 config KERNEL_MEMCG_KMEM
659 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
660 default y if !SMALL_FLASH
661 depends on KERNEL_MEMCG
662 help
663 The Kernel Memory extension for Memory Resource Controller can limit
664 the amount of memory used by kernel objects in the system. Those are
665 fundamentally different from the entities handled by the standard
666 Memory Controller, which are page-based, and can be swapped. Users of
667 the kmem extension can use it to guarantee that no group of processes
668 will ever exhaust kernel resources alone.
669
670 config KERNEL_CGROUP_PERF
671 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
672 select KERNEL_PERF_EVENTS
673 default n
674 help
675 This option extends the per-cpu mode to restrict monitoring to
676 threads which belong to the cgroup specified and run on the
677 designated cpu.
678
679 menuconfig KERNEL_CGROUP_SCHED
680 bool "Group CPU scheduler"
681 default y if !SMALL_FLASH
682 help
683 This feature lets CPU scheduler recognize task groups and control CPU
684 bandwidth allocation to such task groups. It uses cgroups to group
685 tasks.
686
687 if KERNEL_CGROUP_SCHED
688
689 config KERNEL_FAIR_GROUP_SCHED
690 bool "Group scheduling for SCHED_OTHER"
691 default y if !SMALL_FLASH
692
693 config KERNEL_CFS_BANDWIDTH
694 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
695 default n
696 depends on KERNEL_FAIR_GROUP_SCHED
697 help
698 This option allows users to define CPU bandwidth rates (limits) for
699 tasks running within the fair group scheduler. Groups with no limit
700 set are considered to be unconstrained and will run with no
701 restriction.
702 See tip/Documentation/scheduler/sched-bwc.txt for more information.
703
704 config KERNEL_RT_GROUP_SCHED
705 bool "Group scheduling for SCHED_RR/FIFO"
706 default y if !SMALL_FLASH
707 help
708 This feature lets you explicitly allocate real CPU bandwidth
709 to task groups. If enabled, it will also make it impossible to
710 schedule realtime tasks for non-root users until you allocate
711 realtime bandwidth for them.
712
713 endif
714
715 config KERNEL_BLK_CGROUP
716 bool "Block IO controller"
717 default y
718 help
719 Generic block IO controller cgroup interface. This is the common
720 cgroup interface which should be used by various IO controlling
721 policies.
722
723 Currently, CFQ IO scheduler uses it to recognize task groups and
724 control disk bandwidth allocation (proportional time slice allocation)
725 to such task groups. It is also used by bio throttling logic in
726 block layer to implement upper limit in IO rates on a device.
727
728 This option only enables generic Block IO controller infrastructure.
729 One needs to also enable actual IO controlling logic/policy. For
730 enabling proportional weight division of disk bandwidth in CFQ, set
731 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
732 CONFIG_BLK_DEV_THROTTLING=y.
733
734 if KERNEL_BLK_CGROUP
735
736 config KERNEL_CFQ_GROUP_IOSCHED
737 bool "Proportional weight of disk bandwidth in CFQ"
738
739 config KERNEL_BLK_DEV_THROTTLING
740 bool "Enable throttling policy"
741 default y if TARGET_bcm27xx
742
743 config KERNEL_BLK_DEV_THROTTLING_LOW
744 bool "Block throttling .low limit interface support (EXPERIMENTAL)"
745 depends on KERNEL_BLK_DEV_THROTTLING
746 endif
747
748 config KERNEL_DEBUG_BLK_CGROUP
749 bool "Enable Block IO controller debugging"
750 default n
751 depends on KERNEL_BLK_CGROUP
752 help
753 Enable some debugging help. Currently it exports additional stat
754 files in a cgroup which can be useful for debugging.
755
756 config KERNEL_NET_CLS_CGROUP
757 bool "Control Group Classifier"
758 default y
759
760 config KERNEL_NETPRIO_CGROUP
761 bool "Network priority cgroup"
762 default y
763
764 endif
765
766 #
767 # Namespace support symbols
768 #
769
770 config KERNEL_NAMESPACES
771 bool "Enable kernel namespaces"
772 default y if !SMALL_FLASH
773
774 if KERNEL_NAMESPACES
775
776 config KERNEL_UTS_NS
777 bool "UTS namespace"
778 default y
779 help
780 In this namespace, tasks see different info provided
781 with the uname() system call.
782
783 config KERNEL_IPC_NS
784 bool "IPC namespace"
785 default y
786 help
787 In this namespace, tasks work with IPC ids which correspond to
788 different IPC objects in different namespaces.
789
790 config KERNEL_USER_NS
791 bool "User namespace (EXPERIMENTAL)"
792 default y
793 help
794 This allows containers, i.e. vservers, to use user namespaces
795 to provide different user info for different servers.
796
797 config KERNEL_PID_NS
798 bool "PID Namespaces"
799 default y
800 help
801 Support process id namespaces. This allows having multiple
802 processes with the same pid as long as they are in different
803 pid namespaces. This is a building block of containers.
804
805 config KERNEL_NET_NS
806 bool "Network namespace"
807 default y
808 help
809 Allow user space to create what appear to be multiple instances
810 of the network stack.
811
812 endif
813
814 config KERNEL_DEVPTS_MULTIPLE_INSTANCES
815 bool "Support multiple instances of devpts"
816 default y if !SMALL_FLASH
817 help
818 Enable support for multiple instances of devpts filesystem.
819 If you want to have isolated PTY namespaces (eg: in containers),
820 say Y here. Otherwise, say N. If enabled, each mount of devpts
821 filesystem with the '-o newinstance' option will create an
822 independent PTY namespace.
823
824 config KERNEL_POSIX_MQUEUE
825 bool "POSIX Message Queues"
826 default y if !SMALL_FLASH
827 help
828 POSIX variant of message queues is a part of IPC. In POSIX message
829 queues every message has a priority which decides about succession
830 of receiving it by a process. If you want to compile and run
831 programs written e.g. for Solaris with use of its POSIX message
832 queues (functions mq_*) say Y here.
833
834 POSIX message queues are visible as a filesystem called 'mqueue'
835 and can be mounted somewhere if you want to do filesystem
836 operations on message queues.
837
838
839 config KERNEL_SECCOMP_FILTER
840 bool
841 default y if !SMALL_FLASH
842
843 config KERNEL_SECCOMP
844 bool "Enable seccomp support"
845 depends on !(TARGET_uml)
846 select KERNEL_SECCOMP_FILTER
847 default y if !SMALL_FLASH
848 help
849 Build kernel with support for seccomp.
850
851 #
852 # IPv4 configuration
853 #
854
855 config KERNEL_IP_MROUTE
856 bool "Enable IPv4 multicast routing"
857 default y
858 help
859 Multicast routing requires a multicast routing daemon in
860 addition to kernel support.
861
862 #
863 # IPv6 configuration
864 #
865
866 config KERNEL_IPV6
867 def_bool IPV6
868
869 if KERNEL_IPV6
870
871 config KERNEL_IPV6_MULTIPLE_TABLES
872 def_bool y
873
874 config KERNEL_IPV6_SUBTREES
875 def_bool y
876
877 config KERNEL_IPV6_MROUTE
878 bool "Enable IPv6 multicast routing"
879 default y
880 help
881 Multicast routing requires a multicast routing daemon in
882 addition to kernel support.
883
884 config KERNEL_IPV6_PIMSM_V2
885 def_bool n
886
887 endif
888
889 #
890 # NFS related symbols
891 #
892 config KERNEL_IP_PNP
893 bool "Compile the kernel with rootfs on NFS"
894 help
895 If you want to make your kernel boot off a NFS server as root
896 filesystem, select Y here.
897
898 if KERNEL_IP_PNP
899
900 config KERNEL_IP_PNP_DHCP
901 def_bool y
902
903 config KERNEL_IP_PNP_BOOTP
904 def_bool n
905
906 config KERNEL_IP_PNP_RARP
907 def_bool n
908
909 config KERNEL_NFS_FS
910 def_bool y
911
912 config KERNEL_NFS_V2
913 def_bool y
914
915 config KERNEL_NFS_V3
916 def_bool y
917
918 config KERNEL_ROOT_NFS
919 def_bool y
920
921 endif
922
923 menu "Filesystem ACL and attr support options"
924 config USE_FS_ACL_ATTR
925 bool "Use filesystem ACL and attr support by default"
926 default n
927 help
928 Make using ACLs (e.g. POSIX ACL, NFSv4 ACL) the default
929 for kernel and packages, except tmpfs, flash filesystems,
930 and old NFS. Also enable userspace extended attribute support
931 by default. (OpenWrt already has an expection it will be
932 present in the kernel).
933
934 config KERNEL_FS_POSIX_ACL
935 bool "Enable POSIX ACL support"
936 default y if USE_FS_ACL_ATTR
937
938 config KERNEL_BTRFS_FS_POSIX_ACL
939 bool "Enable POSIX ACL for BtrFS Filesystems"
940 select KERNEL_FS_POSIX_ACL
941 default y if USE_FS_ACL_ATTR
942
943 config KERNEL_EXT4_FS_POSIX_ACL
944 bool "Enable POSIX ACL for Ext4 Filesystems"
945 select KERNEL_FS_POSIX_ACL
946 default y if USE_FS_ACL_ATTR
947
948 config KERNEL_F2FS_FS_POSIX_ACL
949 bool "Enable POSIX ACL for F2FS Filesystems"
950 select KERNEL_FS_POSIX_ACL
951 default n
952
953 config KERNEL_JFFS2_FS_POSIX_ACL
954 bool "Enable POSIX ACL for JFFS2 Filesystems"
955 select KERNEL_FS_POSIX_ACL
956 default n
957
958 config KERNEL_TMPFS_POSIX_ACL
959 bool "Enable POSIX ACL for TMPFS Filesystems"
960 select KERNEL_FS_POSIX_ACL
961 default n
962
963 config KERNEL_CIFS_ACL
964 bool "Enable CIFS ACLs"
965 select KERNEL_FS_POSIX_ACL
966 default y if USE_FS_ACL_ATTR
967
968 config KERNEL_HFS_FS_POSIX_ACL
969 bool "Enable POSIX ACL for HFS Filesystems"
970 select KERNEL_FS_POSIX_ACL
971 default y if USE_FS_ACL_ATTR
972
973 config KERNEL_HFSPLUS_FS_POSIX_ACL
974 bool "Enable POSIX ACL for HFS+ Filesystems"
975 select KERNEL_FS_POSIX_ACL
976 default y if USE_FS_ACL_ATTR
977
978 config KERNEL_NFS_ACL_SUPPORT
979 bool "Enable ACLs for NFS"
980 default y if USE_FS_ACL_ATTR
981
982 config KERNEL_NFS_V3_ACL_SUPPORT
983 bool "Enable ACLs for NFSv3"
984 default n
985
986 config KERNEL_NFSD_V2_ACL_SUPPORT
987 bool "Enable ACLs for NFSDv2"
988 default n
989
990 config KERNEL_NFSD_V3_ACL_SUPPORT
991 bool "Enable ACLs for NFSDv3"
992 default n
993
994 config KERNEL_REISER_FS_POSIX_ACL
995 bool "Enable POSIX ACLs for ReiserFS"
996 select KERNEL_FS_POSIX_ACL
997 default y if USE_FS_ACL_ATTR
998
999 config KERNEL_XFS_POSIX_ACL
1000 bool "Enable POSIX ACLs for XFS"
1001 select KERNEL_FS_POSIX_ACL
1002 default y if USE_FS_ACL_ATTR
1003
1004 config KERNEL_JFS_POSIX_ACL
1005 bool "Enable POSIX ACLs for JFS"
1006 select KERNEL_FS_POSIX_ACL
1007 default y if USE_FS_ACL_ATTR
1008
1009 endmenu
1010
1011 config KERNEL_DEVMEM
1012 bool "/dev/mem virtual device support"
1013 help
1014 Say Y here if you want to support the /dev/mem device.
1015 The /dev/mem device is used to access areas of physical
1016 memory.
1017
1018 config KERNEL_DEVKMEM
1019 bool "/dev/kmem virtual device support"
1020 help
1021 Say Y here if you want to support the /dev/kmem device. The
1022 /dev/kmem device is rarely used, but can be used for certain
1023 kind of kernel debugging operations.
1024
1025 config KERNEL_SQUASHFS_FRAGMENT_CACHE_SIZE
1026 int "Number of squashfs fragments cached"
1027 default 2 if (SMALL_FLASH && !LOW_MEMORY_FOOTPRINT)
1028 default 3
1029
1030 #
1031 # compile optimiziation setting
1032 #
1033 choice
1034 prompt "Compiler optimization level"
1035 default KERNEL_CC_OPTIMIZE_FOR_SIZE if SMALL_FLASH
1036
1037 config KERNEL_CC_OPTIMIZE_FOR_PERFORMANCE
1038 bool "Optimize for performance"
1039 help
1040 This is the default optimization level for the kernel, building
1041 with the "-O2" compiler flag for best performance and most
1042 helpful compile-time warnings.
1043
1044 config KERNEL_CC_OPTIMIZE_FOR_SIZE
1045 bool "Optimize for size"
1046 help
1047 Enabling this option will pass "-Os" instead of "-O2" to
1048 your compiler resulting in a smaller kernel.
1049
1050 endchoice