blob: a66cd1508cc58fbfb169a4047c4fa1f13d2b731f [file] [log] [blame]
lh9ed821d2023-04-07 01:36:19 -07001config ARCH
2 string
3 option env="ARCH"
4
5config KERNELVERSION
6 string
7 option env="KERNELVERSION"
8
9config DEFCONFIG_LIST
10 string
11 depends on !UML
12 option defconfig_list
13 default "/lib/modules/$UNAME_RELEASE/.config"
14 default "/etc/kernel-config"
15 default "/boot/config-$UNAME_RELEASE"
16 default "$ARCH_DEFCONFIG"
17 default "arch/$ARCH/defconfig"
18
19config CONSTRUCTORS
20 bool
21 depends on !UML
22
23config HAVE_IRQ_WORK
24 bool
25
26config IRQ_WORK
27 bool
28 depends on HAVE_IRQ_WORK
29
30menu "General setup"
31
32config EXPERIMENTAL
33 bool "Prompt for development and/or incomplete code/drivers"
34 ---help---
35 Some of the various things that Linux supports (such as network
36 drivers, file systems, network protocols, etc.) can be in a state
37 of development where the functionality, stability, or the level of
38 testing is not yet high enough for general use. This is usually
39 known as the "alpha-test" phase among developers. If a feature is
40 currently in alpha-test, then the developers usually discourage
41 uninformed widespread use of this feature by the general public to
42 avoid "Why doesn't this work?" type mail messages. However, active
43 testing and use of these systems is welcomed. Just be aware that it
44 may not meet the normal level of reliability or it may fail to work
45 in some special cases. Detailed bug reports from people familiar
46 with the kernel internals are usually welcomed by the developers
47 (before submitting bug reports, please read the documents
48 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
49 <file:Documentation/BUG-HUNTING>, and
50 <file:Documentation/oops-tracing.txt> in the kernel source).
51
52 This option will also make obsoleted drivers available. These are
53 drivers that have been replaced by something else, and/or are
54 scheduled to be removed in a future kernel release.
55
56 Unless you intend to help test and develop a feature or driver that
57 falls into this category, or you have a situation that requires
58 using these features, you should probably say N here, which will
59 cause the configurator to present you with fewer choices. If
60 you say Y here, you will be offered the choice of using features or
61 drivers that are currently considered to be in the alpha-test phase.
62
63config BROKEN
64 bool
65
66config BROKEN_ON_SMP
67 bool
68 depends on BROKEN || !SMP
69 default y
70
71config INIT_ENV_ARG_LIMIT
72 int
73 default 32 if !UML
74 default 128 if UML
75 help
76 Maximum of each of the number of arguments and environment
77 variables passed to init from the kernel command line.
78
79
80config CROSS_COMPILE
81 string "Cross-compiler tool prefix"
82 help
83 Same as running 'make CROSS_COMPILE=prefix-' but stored for
84 default make runs in this kernel build directory. You don't
85 need to set this unless you want the configured kernel build
86 directory to select the cross-compiler automatically.
87
88config LOCALVERSION
89 string "Local version - append to kernel release"
90 help
91 Append an extra string to the end of your kernel version.
92 This will show up when you type uname, for example.
93 The string you set here will be appended after the contents of
94 any files with a filename matching localversion* in your
95 object and source tree, in that order. Your total string can
96 be a maximum of 64 characters.
97
98config LOCALVERSION_AUTO
99 bool "Automatically append version information to the version string"
100 default y
101 help
102 This will try to automatically determine if the current tree is a
103 release tree by looking for git tags that belong to the current
104 top of tree revision.
105
106 A string of the format -gxxxxxxxx will be added to the localversion
107 if a git-based tree is found. The string generated by this will be
108 appended after any matching localversion* files, and after the value
109 set in CONFIG_LOCALVERSION.
110
111 (The actual string used here is the first eight characters produced
112 by running the command:
113
114 $ git rev-parse --verify HEAD
115
116 which is done within the script "scripts/setlocalversion".)
117
118config HAVE_KERNEL_GZIP
119 bool
120
121config HAVE_KERNEL_BZIP2
122 bool
123
124config HAVE_KERNEL_LZMA
125 bool
126
127config HAVE_KERNEL_XZ
128 bool
129
130config HAVE_KERNEL_LZO
131 bool
132
133choice
134 prompt "Kernel compression mode"
135 default KERNEL_GZIP
136 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
137 help
138 The linux kernel is a kind of self-extracting executable.
139 Several compression algorithms are available, which differ
140 in efficiency, compression and decompression speed.
141 Compression speed is only relevant when building a kernel.
142 Decompression speed is relevant at each boot.
143
144 If you have any problems with bzip2 or lzma compressed
145 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
146 version of this functionality (bzip2 only), for 2.4, was
147 supplied by Christian Ludwig)
148
149 High compression options are mostly useful for users, who
150 are low on disk space (embedded systems), but for whom ram
151 size matters less.
152
153 If in doubt, select 'gzip'
154
155config KERNEL_GZIP
156 bool "Gzip"
157 depends on HAVE_KERNEL_GZIP
158 help
159 The old and tried gzip compression. It provides a good balance
160 between compression ratio and decompression speed.
161
162config KERNEL_BZIP2
163 bool "Bzip2"
164 depends on HAVE_KERNEL_BZIP2
165 help
166 Its compression ratio and speed is intermediate.
167 Decompression speed is slowest among the three. The kernel
168 size is about 10% smaller with bzip2, in comparison to gzip.
169 Bzip2 uses a large amount of memory. For modern kernels you
170 will need at least 8MB RAM or more for booting.
171
172config KERNEL_LZMA
173 bool "LZMA"
174 depends on HAVE_KERNEL_LZMA
175 help
176 The most recent compression algorithm.
177 Its ratio is best, decompression speed is between the other
178 two. Compression is slowest. The kernel size is about 33%
179 smaller with LZMA in comparison to gzip.
180
181config KERNEL_XZ
182 bool "XZ"
183 depends on HAVE_KERNEL_XZ
184 help
185 XZ uses the LZMA2 algorithm and instruction set specific
186 BCJ filters which can improve compression ratio of executable
187 code. The size of the kernel is about 30% smaller with XZ in
188 comparison to gzip. On architectures for which there is a BCJ
189 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
190 will create a few percent smaller kernel than plain LZMA.
191
192 The speed is about the same as with LZMA: The decompression
193 speed of XZ is better than that of bzip2 but worse than gzip
194 and LZO. Compression is slow.
195
196config KERNEL_LZO
197 bool "LZO"
198 depends on HAVE_KERNEL_LZO
199 help
200 Its compression ratio is the poorest among the 4. The kernel
201 size is about 10% bigger than gzip; however its speed
202 (both compression and decompression) is the fastest.
203
204endchoice
205
206config DEFAULT_HOSTNAME
207 string "Default hostname"
208 default "(none)"
209 help
210 This option determines the default system hostname before userspace
211 calls sethostname(2). The kernel traditionally uses "(none)" here,
212 but you may wish to use a different default here to make a minimal
213 system more usable with less configuration.
214
215config SWAP
216 bool "Support for paging of anonymous memory (swap)"
217 depends on MMU && BLOCK
218 default y
219 help
220 This option allows you to choose whether you want to have support
221 for so called swap devices or swap files in your kernel that are
222 used to provide more virtual memory than the actual RAM present
223 in your computer. If unsure say Y.
224
225config SYSVIPC
226 bool "System V IPC"
227 ---help---
228 Inter Process Communication is a suite of library functions and
229 system calls which let processes (running programs) synchronize and
230 exchange information. It is generally considered to be a good thing,
231 and some programs won't run unless you say Y here. In particular, if
232 you want to run the DOS emulator dosemu under Linux (read the
233 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
234 you'll need to say Y here.
235
236 You can find documentation about IPC with "info ipc" and also in
237 section 6.4 of the Linux Programmer's Guide, available from
238 <http://www.tldp.org/guides.html>.
239
240config SYSVIPC_SYSCTL
241 bool
242 depends on SYSVIPC
243 depends on SYSCTL
244 default y
245
lh758261d2023-07-13 05:52:04 -0700246config SYSVIPC_CROSSMSG
247 bool "Cross Core Message by ZTE_RPMSG"
248 depends on SYSVIPC && !ARCH_ZX297520V3_CAP
249 default n
250
251config SYSVIPC_CROSS_SHM
252 bool "Cross Core SHM"
253 depends on SYSVIPC && !ARCH_ZX297520V3_CAP
254 default n
255
lh9ed821d2023-04-07 01:36:19 -0700256config POSIX_MQUEUE
257 bool "POSIX Message Queues"
258 depends on NET && EXPERIMENTAL
259 ---help---
260 POSIX variant of message queues is a part of IPC. In POSIX message
261 queues every message has a priority which decides about succession
262 of receiving it by a process. If you want to compile and run
263 programs written e.g. for Solaris with use of its POSIX message
264 queues (functions mq_*) say Y here.
265
266 POSIX message queues are visible as a filesystem called 'mqueue'
267 and can be mounted somewhere if you want to do filesystem
268 operations on message queues.
269
270 If unsure, say Y.
271
272config POSIX_MQUEUE_SYSCTL
273 bool
274 depends on POSIX_MQUEUE
275 depends on SYSCTL
276 default y
277
278config BSD_PROCESS_ACCT
279 bool "BSD Process Accounting"
280 help
281 If you say Y here, a user level program will be able to instruct the
282 kernel (via a special system call) to write process accounting
283 information to a file: whenever a process exits, information about
284 that process will be appended to the file by the kernel. The
285 information includes things such as creation time, owning user,
286 command name, memory usage, controlling terminal etc. (the complete
287 list is in the struct acct in <file:include/linux/acct.h>). It is
288 up to the user level program to do useful things with this
289 information. This is generally a good idea, so say Y.
290
291config BSD_PROCESS_ACCT_V3
292 bool "BSD Process Accounting version 3 file format"
293 depends on BSD_PROCESS_ACCT
294 default n
295 help
296 If you say Y here, the process accounting information is written
297 in a new file format that also logs the process IDs of each
298 process and it's parent. Note that this file format is incompatible
299 with previous v0/v1/v2 file formats, so you will need updated tools
300 for processing it. A preliminary version of these tools is available
301 at <http://www.gnu.org/software/acct/>.
302
303config FHANDLE
304 bool "open by fhandle syscalls"
305 select EXPORTFS
306 help
307 If you say Y here, a user level program will be able to map
308 file names to handle and then later use the handle for
309 different file system operations. This is useful in implementing
310 userspace file servers, which now track files using handles instead
311 of names. The handle would remain the same even if file names
312 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
313 syscalls.
314
315config TASKSTATS
316 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
317 depends on NET
318 default n
319 help
320 Export selected statistics for tasks/processes through the
321 generic netlink interface. Unlike BSD process accounting, the
322 statistics are available during the lifetime of tasks/processes as
323 responses to commands. Like BSD accounting, they are sent to user
324 space on task exit.
325
326 Say N if unsure.
327
328config TASK_DELAY_ACCT
329 bool "Enable per-task delay accounting (EXPERIMENTAL)"
330 depends on TASKSTATS
331 help
332 Collect information on time spent by a task waiting for system
333 resources like cpu, synchronous block I/O completion and swapping
334 in pages. Such statistics can help in setting a task's priorities
335 relative to other tasks for cpu, io, rss limits etc.
336
337 Say N if unsure.
338
339config TASK_XACCT
340 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
341 depends on TASKSTATS
342 help
343 Collect extended task accounting data and send the data
344 to userland for processing over the taskstats interface.
345
346 Say N if unsure.
347
348config TASK_IO_ACCOUNTING
349 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
350 depends on TASK_XACCT
351 help
352 Collect information on the number of bytes of storage I/O which this
353 task has caused.
354
355 Say N if unsure.
356
357config AUDIT
358 bool "Auditing support"
359 depends on NET
360 help
361 Enable auditing infrastructure that can be used with another
362 kernel subsystem, such as SELinux (which requires this for
363 logging of avc messages output). Does not do system-call
364 auditing without CONFIG_AUDITSYSCALL.
365
366config AUDITSYSCALL
367 bool "Enable system-call auditing support"
368 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || ARM)
369 default y if SECURITY_SELINUX
370 help
371 Enable low-overhead system-call auditing infrastructure that
372 can be used independently or with another kernel subsystem,
373 such as SELinux.
374
375config AUDIT_WATCH
376 def_bool y
377 depends on AUDITSYSCALL
378 select FSNOTIFY
379
380config AUDIT_TREE
381 def_bool y
382 depends on AUDITSYSCALL
383 select FSNOTIFY
384
385config AUDIT_LOGINUID_IMMUTABLE
386 bool "Make audit loginuid immutable"
387 depends on AUDIT
388 help
389 The config option toggles if a task setting its loginuid requires
390 CAP_SYS_AUDITCONTROL or if that task should require no special permissions
391 but should instead only allow setting its loginuid if it was never
392 previously set. On systems which use systemd or a similar central
393 process to restart login services this should be set to true. On older
394 systems in which an admin would typically have to directly stop and
395 start processes this should be set to false. Setting this to true allows
396 one to drop potentially dangerous capabilites from the login tasks,
397 but may not be backwards compatible with older init systems.
398
399source "kernel/irq/Kconfig"
400
401menu "RCU Subsystem"
402
403choice
404 prompt "RCU Implementation"
405 default TREE_RCU
406
407config TREE_RCU
408 bool "Tree-based hierarchical RCU"
409 depends on !PREEMPT && SMP
410 help
411 This option selects the RCU implementation that is
412 designed for very large SMP system with hundreds or
413 thousands of CPUs. It also scales down nicely to
414 smaller systems.
415
416config TREE_PREEMPT_RCU
417 bool "Preemptible tree-based hierarchical RCU"
418 depends on PREEMPT && SMP
419 help
420 This option selects the RCU implementation that is
421 designed for very large SMP systems with hundreds or
422 thousands of CPUs, but for which real-time response
423 is also required. It also scales down nicely to
424 smaller systems.
425
426config TINY_RCU
427 bool "UP-only small-memory-footprint RCU"
428 depends on !PREEMPT && !SMP
429 help
430 This option selects the RCU implementation that is
431 designed for UP systems from which real-time response
432 is not required. This option greatly reduces the
433 memory footprint of RCU.
434
435config TINY_PREEMPT_RCU
436 bool "Preemptible UP-only small-memory-footprint RCU"
437 depends on PREEMPT && !SMP
438 help
439 This option selects the RCU implementation that is designed
440 for real-time UP systems. This option greatly reduces the
441 memory footprint of RCU.
442
443endchoice
444
445config PREEMPT_RCU
446 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
447 help
448 This option enables preemptible-RCU code that is common between
449 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
450
451config RCU_FANOUT
452 int "Tree-based hierarchical RCU fanout value"
453 range 2 64 if 64BIT
454 range 2 32 if !64BIT
455 depends on TREE_RCU || TREE_PREEMPT_RCU
456 default 64 if 64BIT
457 default 32 if !64BIT
458 help
459 This option controls the fanout of hierarchical implementations
460 of RCU, allowing RCU to work efficiently on machines with
461 large numbers of CPUs. This value must be at least the fourth
462 root of NR_CPUS, which allows NR_CPUS to be insanely large.
463 The default value of RCU_FANOUT should be used for production
464 systems, but if you are stress-testing the RCU implementation
465 itself, small RCU_FANOUT values allow you to test large-system
466 code paths on small(er) systems.
467
468 Select a specific number if testing RCU itself.
469 Take the default if unsure.
470
471config RCU_FANOUT_EXACT
472 bool "Disable tree-based hierarchical RCU auto-balancing"
473 depends on TREE_RCU || TREE_PREEMPT_RCU
474 default n
475 help
476 This option forces use of the exact RCU_FANOUT value specified,
477 regardless of imbalances in the hierarchy. This is useful for
478 testing RCU itself, and might one day be useful on systems with
479 strong NUMA behavior.
480
481 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
482
483 Say N if unsure.
484
485config RCU_FAST_NO_HZ
486 bool "Accelerate last non-dyntick-idle CPU's grace periods"
487 depends on NO_HZ && SMP && !PREEMPT_RT_FULL
488 default n
489 help
490 This option causes RCU to attempt to accelerate grace periods
491 in order to allow CPUs to enter dynticks-idle state more
492 quickly. On the other hand, this option increases the overhead
493 of the dynticks-idle checking, particularly on systems with
494 large numbers of CPUs.
495
496 Say Y if energy efficiency is critically important, particularly
497 if you have relatively few CPUs.
498
499 Say N if you are unsure.
500
501config TREE_RCU_TRACE
502 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
503 select DEBUG_FS
504 help
505 This option provides tracing for the TREE_RCU and
506 TREE_PREEMPT_RCU implementations, permitting Makefile to
507 trivially select kernel/rcutree_trace.c.
508
509config RCU_BOOST
510 bool "Enable RCU priority boosting"
511 depends on RT_MUTEXES && PREEMPT_RCU
512 default y if PREEMPT_RT_FULL
513 help
514 This option boosts the priority of preempted RCU readers that
515 block the current preemptible RCU grace period for too long.
516 This option also prevents heavy loads from blocking RCU
517 callback invocation for all flavors of RCU.
518
519 Say Y here if you are working with real-time apps or heavy loads
520 Say N here if you are unsure.
521
522config RCU_BOOST_PRIO
523 int "Real-time priority to boost RCU readers to"
524 range 1 99
525 depends on RCU_BOOST
526 default 1
527 help
528 This option specifies the real-time priority to which preempted
529 RCU readers are to be boosted. If you are working with CPU-bound
530 real-time applications, you should specify a priority higher then
531 the highest-priority CPU-bound application.
532
533 Specify the real-time priority, or take the default if unsure.
534
535config RCU_BOOST_DELAY
536 int "Milliseconds to delay boosting after RCU grace-period start"
537 range 0 3000
538 depends on RCU_BOOST
539 default 500
540 help
541 This option specifies the time to wait after the beginning of
542 a given grace period before priority-boosting preempted RCU
543 readers blocking that grace period. Note that any RCU reader
544 blocking an expedited RCU grace period is boosted immediately.
545
546 Accept the default if unsure.
547
548endmenu # "RCU Subsystem"
549
550config IKCONFIG
551 tristate "Kernel .config support"
552 ---help---
553 This option enables the complete Linux kernel ".config" file
554 contents to be saved in the kernel. It provides documentation
555 of which kernel options are used in a running kernel or in an
556 on-disk kernel. This information can be extracted from the kernel
557 image file with the script scripts/extract-ikconfig and used as
558 input to rebuild the current kernel or to build another kernel.
559 It can also be extracted from a running kernel by reading
560 /proc/config.gz if enabled (below).
561
562config IKCONFIG_PROC
563 bool "Enable access to .config through /proc/config.gz"
564 depends on IKCONFIG && PROC_FS
565 ---help---
566 This option enables access to the kernel configuration file
567 through /proc/config.gz.
568
569config LOG_BUF_SHIFT
570 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
571 range 12 21
572 default 17
573 depends on PRINTK
574 help
575 Select kernel log buffer size as a power of 2.
576 Examples:
577 17 => 128 KB
578 16 => 64 KB
579 15 => 32 KB
580 14 => 16 KB
581 13 => 8 KB
582 12 => 4 KB
583
584#
585# Architectures with an unreliable sched_clock() should select this:
586#
587config HAVE_UNSTABLE_SCHED_CLOCK
588 bool
589
590menuconfig CGROUPS
591 boolean "Control Group support"
592 depends on EVENTFD
593 help
594 This option adds support for grouping sets of processes together, for
595 use with process control subsystems such as Cpusets, CFS, memory
596 controls or device isolation.
597 See
598 - Documentation/scheduler/sched-design-CFS.txt (CFS)
599 - Documentation/cgroups/ (features for grouping, isolation
600 and resource control)
601
602 Say N if unsure.
603
604if CGROUPS
605
606config CGROUP_DEBUG
607 bool "Example debug cgroup subsystem"
608 default n
609 help
610 This option enables a simple cgroup subsystem that
611 exports useful debugging information about the cgroups
612 framework.
613
614 Say N if unsure.
615
616config CGROUP_FREEZER
617 bool "Freezer cgroup subsystem"
618 help
619 Provides a way to freeze and unfreeze all tasks in a
620 cgroup.
621
622config CGROUP_DEVICE
623 bool "Device controller for cgroups"
624 help
625 Provides a cgroup implementing whitelists for devices which
626 a process in the cgroup can mknod or open.
627
628config CPUSETS
629 bool "Cpuset support"
630 help
631 This option will let you create and manage CPUSETs which
632 allow dynamically partitioning a system into sets of CPUs and
633 Memory Nodes and assigning tasks to run only within those sets.
634 This is primarily useful on large SMP or NUMA systems.
635
636 Say N if unsure.
637
638config PROC_PID_CPUSET
639 bool "Include legacy /proc/<pid>/cpuset file"
640 depends on CPUSETS
641 default y
642
643config CGROUP_CPUACCT
644 bool "Simple CPU accounting cgroup subsystem"
645 help
646 Provides a simple Resource Controller for monitoring the
647 total CPU consumed by the tasks in a cgroup.
648
649config RESOURCE_COUNTERS
650 bool "Resource counters"
651 help
652 This option enables controller independent resource accounting
653 infrastructure that works with cgroups.
654
655config CGROUP_MEM_RES_CTLR
656 bool "Memory Resource Controller for Control Groups"
657 depends on RESOURCE_COUNTERS
658 select MM_OWNER
659 help
660 Provides a memory resource controller that manages both anonymous
661 memory and page cache. (See Documentation/cgroups/memory.txt)
662
663 Note that setting this option increases fixed memory overhead
664 associated with each page of memory in the system. By this,
665 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
666 usage tracking struct at boot. Total amount of this is printed out
667 at boot.
668
669 Only enable when you're ok with these trade offs and really
670 sure you need the memory resource controller. Even when you enable
671 this, you can set "cgroup_disable=memory" at your boot option to
672 disable memory resource controller and you can avoid overheads.
673 (and lose benefits of memory resource controller)
674
675 This config option also selects MM_OWNER config option, which
676 could in turn add some fork/exit overhead.
677
678config CGROUP_MEM_RES_CTLR_SWAP
679 bool "Memory Resource Controller Swap Extension"
680 depends on CGROUP_MEM_RES_CTLR && SWAP
681 help
682 Add swap management feature to memory resource controller. When you
683 enable this, you can limit mem+swap usage per cgroup. In other words,
684 when you disable this, memory resource controller has no cares to
685 usage of swap...a process can exhaust all of the swap. This extension
686 is useful when you want to avoid exhaustion swap but this itself
687 adds more overheads and consumes memory for remembering information.
688 Especially if you use 32bit system or small memory system, please
689 be careful about enabling this. When memory resource controller
690 is disabled by boot option, this will be automatically disabled and
691 there will be no overhead from this. Even when you set this config=y,
692 if boot option "swapaccount=0" is set, swap will not be accounted.
693 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
694 size is 4096bytes, 512k per 1Gbytes of swap.
695config CGROUP_MEM_RES_CTLR_SWAP_ENABLED
696 bool "Memory Resource Controller Swap Extension enabled by default"
697 depends on CGROUP_MEM_RES_CTLR_SWAP
698 default y
699 help
700 Memory Resource Controller Swap Extension comes with its price in
701 a bigger memory consumption. General purpose distribution kernels
702 which want to enable the feature but keep it disabled by default
703 and let the user enable it by swapaccount boot command line
704 parameter should have this option unselected.
705 For those who want to have the feature enabled by default should
706 select this option (if, for some reason, they need to disable it
707 then swapaccount=0 does the trick).
708config CGROUP_MEM_RES_CTLR_KMEM
709 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
710 depends on CGROUP_MEM_RES_CTLR && EXPERIMENTAL
711 default n
712 help
713 The Kernel Memory extension for Memory Resource Controller can limit
714 the amount of memory used by kernel objects in the system. Those are
715 fundamentally different from the entities handled by the standard
716 Memory Controller, which are page-based, and can be swapped. Users of
717 the kmem extension can use it to guarantee that no group of processes
718 will ever exhaust kernel resources alone.
719
720config CGROUP_PERF
721 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
722 depends on PERF_EVENTS && CGROUPS
723 help
724 This option extends the per-cpu mode to restrict monitoring to
725 threads which belong to the cgroup specified and run on the
726 designated cpu.
727
728 Say N if unsure.
729
730menuconfig CGROUP_SCHED
731 bool "Group CPU scheduler"
732 default n
733 help
734 This feature lets CPU scheduler recognize task groups and control CPU
735 bandwidth allocation to such task groups. It uses cgroups to group
736 tasks.
737
738if CGROUP_SCHED
739config FAIR_GROUP_SCHED
740 bool "Group scheduling for SCHED_OTHER"
741 depends on CGROUP_SCHED
742 default CGROUP_SCHED
743
744config CFS_BANDWIDTH
745 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
746 depends on EXPERIMENTAL
747 depends on FAIR_GROUP_SCHED
748 default n
749 help
750 This option allows users to define CPU bandwidth rates (limits) for
751 tasks running within the fair group scheduler. Groups with no limit
752 set are considered to be unconstrained and will run with no
753 restriction.
754 See tip/Documentation/scheduler/sched-bwc.txt for more information.
755
756config RT_GROUP_SCHED
757 bool "Group scheduling for SCHED_RR/FIFO"
758 depends on EXPERIMENTAL
759 depends on CGROUP_SCHED
760 depends on !PREEMPT_RT_FULL
761 default n
762 help
763 This feature lets you explicitly allocate real CPU bandwidth
764 to task groups. If enabled, it will also make it impossible to
765 schedule realtime tasks for non-root users until you allocate
766 realtime bandwidth for them.
767 See Documentation/scheduler/sched-rt-group.txt for more information.
768
769endif #CGROUP_SCHED
770
771config BLK_CGROUP
772 tristate "Block IO controller"
773 depends on BLOCK
774 default n
775 ---help---
776 Generic block IO controller cgroup interface. This is the common
777 cgroup interface which should be used by various IO controlling
778 policies.
779
780 Currently, CFQ IO scheduler uses it to recognize task groups and
781 control disk bandwidth allocation (proportional time slice allocation)
782 to such task groups. It is also used by bio throttling logic in
783 block layer to implement upper limit in IO rates on a device.
784
785 This option only enables generic Block IO controller infrastructure.
786 One needs to also enable actual IO controlling logic/policy. For
787 enabling proportional weight division of disk bandwidth in CFQ, set
788 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
789 CONFIG_BLK_DEV_THROTTLING=y.
790
791 See Documentation/cgroups/blkio-controller.txt for more information.
792
793config DEBUG_BLK_CGROUP
794 bool "Enable Block IO controller debugging"
795 depends on BLK_CGROUP
796 default n
797 ---help---
798 Enable some debugging help. Currently it exports additional stat
799 files in a cgroup which can be useful for debugging.
800
801endif # CGROUPS
802
803config CHECKPOINT_RESTORE
804 bool "Checkpoint/restore support" if EXPERT
805 default n
806 help
807 Enables additional kernel features in a sake of checkpoint/restore.
808 In particular it adds auxiliary prctl codes to setup process text,
809 data and heap segment sizes, and a few additional /proc filesystem
810 entries.
811
812 If unsure, say N here.
813
814menuconfig NAMESPACES
815 bool "Namespaces support" if EXPERT
816 default !EXPERT
817 help
818 Provides the way to make tasks work with different objects using
819 the same id. For example same IPC id may refer to different objects
820 or same user id or pid may refer to different tasks when used in
821 different namespaces.
822
823if NAMESPACES
824
825config UTS_NS
826 bool "UTS namespace"
827 default y
828 help
829 In this namespace tasks see different info provided with the
830 uname() system call
831
832config IPC_NS
833 bool "IPC namespace"
834 depends on (SYSVIPC || POSIX_MQUEUE)
835 default y
836 help
837 In this namespace tasks work with IPC ids which correspond to
838 different IPC objects in different namespaces.
839
840config USER_NS
841 bool "User namespace (EXPERIMENTAL)"
842 depends on EXPERIMENTAL
843 default y
844 help
845 This allows containers, i.e. vservers, to use user namespaces
846 to provide different user info for different servers.
847 If unsure, say N.
848
849config PID_NS
850 bool "PID Namespaces"
851 default y
852 help
853 Support process id namespaces. This allows having multiple
854 processes with the same pid as long as they are in different
855 pid namespaces. This is a building block of containers.
856
857config NET_NS
858 bool "Network namespace"
859 depends on NET
860 default y
861 help
862 Allow user space to create what appear to be multiple instances
863 of the network stack.
864
865endif # NAMESPACES
866
867config SCHED_AUTOGROUP
868 bool "Automatic process group scheduling"
869 select EVENTFD
870 select CGROUPS
871 select CGROUP_SCHED
872 select FAIR_GROUP_SCHED
873 help
874 This option optimizes the scheduler for common desktop workloads by
875 automatically creating and populating task groups. This separation
876 of workloads isolates aggressive CPU burners (like build jobs) from
877 desktop applications. Task group autogeneration is currently based
878 upon task session.
879
880config MM_OWNER
881 bool
882
883config SYSFS_DEPRECATED
884 bool "Enable deprecated sysfs features to support old userspace tools"
885 depends on SYSFS
886 default n
887 help
888 This option adds code that switches the layout of the "block" class
889 devices, to not show up in /sys/class/block/, but only in
890 /sys/block/.
891
892 This switch is only active when the sysfs.deprecated=1 boot option is
893 passed or the SYSFS_DEPRECATED_V2 option is set.
894
895 This option allows new kernels to run on old distributions and tools,
896 which might get confused by /sys/class/block/. Since 2007/2008 all
897 major distributions and tools handle this just fine.
898
899 Recent distributions and userspace tools after 2009/2010 depend on
900 the existence of /sys/class/block/, and will not work with this
901 option enabled.
902
903 Only if you are using a new kernel on an old distribution, you might
904 need to say Y here.
905
906config SYSFS_DEPRECATED_V2
907 bool "Enable deprecated sysfs features by default"
908 default n
909 depends on SYSFS
910 depends on SYSFS_DEPRECATED
911 help
912 Enable deprecated sysfs by default.
913
914 See the CONFIG_SYSFS_DEPRECATED option for more details about this
915 option.
916
917 Only if you are using a new kernel on an old distribution, you might
918 need to say Y here. Even then, odds are you would not need it
919 enabled, you can always pass the boot option if absolutely necessary.
920
921config RELAY
922 bool "Kernel->user space relay support (formerly relayfs)"
923 help
924 This option enables support for relay interface support in
925 certain file systems (such as debugfs).
926 It is designed to provide an efficient mechanism for tools and
927 facilities to relay large amounts of data from kernel space to
928 user space.
929
930 If unsure, say N.
931
932config BLK_DEV_INITRD
933 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
934 depends on BROKEN || !FRV
935 help
936 The initial RAM filesystem is a ramfs which is loaded by the
937 boot loader (loadlin or lilo) and that is mounted as root
938 before the normal boot procedure. It is typically used to
939 load modules needed to mount the "real" root file system,
940 etc. See <file:Documentation/initrd.txt> for details.
941
942 If RAM disk support (BLK_DEV_RAM) is also included, this
943 also enables initial RAM disk (initrd) support and adds
944 15 Kbytes (more on some other architectures) to the kernel size.
945
946 If unsure say Y.
947
948if BLK_DEV_INITRD
949
950source "usr/Kconfig"
951
952endif
953
954config CC_OPTIMIZE_FOR_SIZE
955 bool "Optimize for size"
956 help
957 Enabling this option will pass "-Os" instead of "-O2" to gcc
958 resulting in a smaller kernel.
959
960 If unsure, say Y.
961
962config SYSCTL
963 bool
964
965config ANON_INODES
966 bool
967
968config PANIC_TIMEOUT
969 int "Default panic timeout"
970 default 0
971 help
972 Set default panic timeout.
973
974menuconfig EXPERT
975 bool "Configure standard kernel features (expert users)"
976 # Unhide debug options, to make the on-by-default options visible
977 select DEBUG_KERNEL
978 help
979 This option allows certain base kernel options and settings
980 to be disabled or tweaked. This is for specialized
981 environments which can tolerate a "non-standard" kernel.
982 Only use this if you really know what you are doing.
983
984config UID16
985 bool "Enable 16-bit UID system calls" if EXPERT
986 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
987 default y
988 help
989 This enables the legacy 16-bit UID syscall wrappers.
990
991config SYSCTL_SYSCALL
992 bool "Sysctl syscall support" if EXPERT
993 depends on PROC_SYSCTL
994 default n
995 select SYSCTL
996 ---help---
997 sys_sysctl uses binary paths that have been found challenging
998 to properly maintain and use. The interface in /proc/sys
999 using paths with ascii names is now the primary path to this
1000 information.
1001
1002 Almost nothing using the binary sysctl interface so if you are
1003 trying to save some space it is probably safe to disable this,
1004 making your kernel marginally smaller.
1005
1006 If unsure say N here.
1007
1008config KALLSYMS
1009 bool "Load all symbols for debugging/ksymoops" if EXPERT
1010 default y
1011 help
1012 Say Y here to let the kernel print out symbolic crash information and
1013 symbolic stack backtraces. This increases the size of the kernel
1014 somewhat, as all symbols have to be loaded into the kernel image.
1015
1016config KALLSYMS_ALL
1017 bool "Include all symbols in kallsyms"
1018 depends on DEBUG_KERNEL && KALLSYMS
1019 help
1020 Normally kallsyms only contains the symbols of functions for nicer
1021 OOPS messages and backtraces (i.e., symbols from the text and inittext
1022 sections). This is sufficient for most cases. And only in very rare
1023 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1024 names of variables from the data sections, etc).
1025
1026 This option makes sure that all symbols are loaded into the kernel
1027 image (i.e., symbols from all sections) in cost of increased kernel
1028 size (depending on the kernel configuration, it may be 300KiB or
1029 something like this).
1030
1031 Say N unless you really need all symbols.
1032
1033config HOTPLUG
1034 bool "Support for hot-pluggable devices" if EXPERT
1035 default y
1036 help
1037 This option is provided for the case where no hotplug or uevent
1038 capabilities is wanted by the kernel. You should only consider
1039 disabling this option for embedded systems that do not use modules, a
1040 dynamic /dev tree, or dynamic device discovery. Just say Y.
1041
1042config PRINTK
1043 default y
1044 bool "Enable support for printk" if EXPERT
1045 help
1046 This option enables normal printk support. Removing it
1047 eliminates most of the message strings from the kernel image
1048 and makes the kernel more or less silent. As this makes it
1049 very difficult to diagnose system problems, saying N here is
1050 strongly discouraged.
1051
1052config BUG
1053 bool "BUG() support" if EXPERT
1054 default y
1055 help
1056 Disabling this option eliminates support for BUG and WARN, reducing
1057 the size of your kernel image and potentially quietly ignoring
1058 numerous fatal conditions. You should only consider disabling this
1059 option for embedded systems with no facilities for reporting errors.
1060 Just say Y.
1061
1062config ELF_CORE
1063 default y
1064 bool "Enable ELF core dumps" if EXPERT
1065 help
1066 Enable support for generating core dumps. Disabling saves about 4k.
1067
1068
1069config PCSPKR_PLATFORM
1070 bool "Enable PC-Speaker support" if EXPERT
1071 depends on HAVE_PCSPKR_PLATFORM
1072 select I8253_LOCK
1073 default y
1074 help
1075 This option allows to disable the internal PC-Speaker
1076 support, saving some memory.
1077
1078config HAVE_PCSPKR_PLATFORM
1079 bool
1080
1081config BASE_FULL
1082 default y
1083 bool "Enable full-sized data structures for core" if EXPERT
1084 help
1085 Disabling this option reduces the size of miscellaneous core
1086 kernel data structures. This saves memory on small machines,
1087 but may reduce performance.
1088
1089config FUTEX
1090 bool "Enable futex support" if EXPERT
1091 default y
1092 select RT_MUTEXES
1093 help
1094 Disabling this option will cause the kernel to be built without
1095 support for "fast userspace mutexes". The resulting kernel may not
1096 run glibc-based applications correctly.
1097
1098config EPOLL
1099 bool "Enable eventpoll support" if EXPERT
1100 default y
1101 select ANON_INODES
1102 help
1103 Disabling this option will cause the kernel to be built without
1104 support for epoll family of system calls.
1105
1106config SIGNALFD
1107 bool "Enable signalfd() system call" if EXPERT
1108 select ANON_INODES
1109 default y
1110 help
1111 Enable the signalfd() system call that allows to receive signals
1112 on a file descriptor.
1113
1114 If unsure, say Y.
1115
1116config TIMERFD
1117 bool "Enable timerfd() system call" if EXPERT
1118 select ANON_INODES
1119 default y
1120 help
1121 Enable the timerfd() system call that allows to receive timer
1122 events on a file descriptor.
1123
1124 If unsure, say Y.
1125
1126config EVENTFD
1127 bool "Enable eventfd() system call" if EXPERT
1128 select ANON_INODES
1129 default y
1130 help
1131 Enable the eventfd() system call that allows to receive both
1132 kernel notification (ie. KAIO) or userspace notifications.
1133
1134 If unsure, say Y.
1135
1136config SHMEM
1137 bool "Use full shmem filesystem" if EXPERT
1138 default y
1139 depends on MMU
1140 help
1141 The shmem is an internal filesystem used to manage shared memory.
1142 It is backed by swap and manages resource limits. It is also exported
1143 to userspace as tmpfs if TMPFS is enabled. Disabling this
1144 option replaces shmem and tmpfs with the much simpler ramfs code,
1145 which may be appropriate on small systems without swap.
1146
1147config AIO
1148 bool "Enable AIO support" if EXPERT
1149 default y
1150 help
1151 This option enables POSIX asynchronous I/O which may by used
1152 by some high performance threaded applications. Disabling
1153 this option saves about 7k.
1154
1155config EMBEDDED
1156 bool "Embedded system"
1157 select EXPERT
1158 help
1159 This option should be enabled if compiling the kernel for
1160 an embedded system so certain expert options are available
1161 for configuration.
1162
1163config HAVE_PERF_EVENTS
1164 bool
1165 help
1166 See tools/perf/design.txt for details.
1167
1168config PERF_USE_VMALLOC
1169 bool
1170 help
1171 See tools/perf/design.txt for details
1172
1173menu "Kernel Performance Events And Counters"
1174
1175config PERF_EVENTS
1176 bool "Kernel performance events and counters"
1177 default y if (PROFILING || PERF_COUNTERS)
1178 depends on HAVE_PERF_EVENTS
1179 select ANON_INODES
1180 select IRQ_WORK
1181 help
1182 Enable kernel support for various performance events provided
1183 by software and hardware.
1184
1185 Software events are supported either built-in or via the
1186 use of generic tracepoints.
1187
1188 Most modern CPUs support performance events via performance
1189 counter registers. These registers count the number of certain
1190 types of hw events: such as instructions executed, cachemisses
1191 suffered, or branches mis-predicted - without slowing down the
1192 kernel or applications. These registers can also trigger interrupts
1193 when a threshold number of events have passed - and can thus be
1194 used to profile the code that runs on that CPU.
1195
1196 The Linux Performance Event subsystem provides an abstraction of
1197 these software and hardware event capabilities, available via a
1198 system call and used by the "perf" utility in tools/perf/. It
1199 provides per task and per CPU counters, and it provides event
1200 capabilities on top of those.
1201
1202 Say Y if unsure.
1203
1204config PERF_COUNTERS
1205 bool "Kernel performance counters (old config option)"
1206 depends on HAVE_PERF_EVENTS
1207 help
1208 This config has been obsoleted by the PERF_EVENTS
1209 config option - please see that one for details.
1210
1211 It has no effect on the kernel whether you enable
1212 it or not, it is a compatibility placeholder.
1213
1214 Say N if unsure.
1215
1216config DEBUG_PERF_USE_VMALLOC
1217 default n
1218 bool "Debug: use vmalloc to back perf mmap() buffers"
1219 depends on PERF_EVENTS && DEBUG_KERNEL
1220 select PERF_USE_VMALLOC
1221 help
1222 Use vmalloc memory to back perf mmap() buffers.
1223
1224 Mostly useful for debugging the vmalloc code on platforms
1225 that don't require it.
1226
1227 Say N if unsure.
1228
1229endmenu
1230
1231config VM_EVENT_COUNTERS
1232 default y
1233 bool "Enable VM event counters for /proc/vmstat" if EXPERT
1234 help
1235 VM event counters are needed for event counts to be shown.
1236 This option allows the disabling of the VM event counters
1237 on EXPERT systems. /proc/vmstat will only show page counts
1238 if VM event counters are disabled.
1239
1240config PCI_QUIRKS
1241 default y
1242 bool "Enable PCI quirk workarounds" if EXPERT
1243 depends on PCI
1244 help
1245 This enables workarounds for various PCI chipset
1246 bugs/quirks. Disable this only if your target machine is
1247 unaffected by PCI quirks.
1248
1249config SLUB_DEBUG
1250 default y
1251 bool "Enable SLUB debugging support" if EXPERT
1252 depends on SLUB && SYSFS
1253 help
1254 SLUB has extensive debug support features. Disabling these can
1255 result in significant savings in code size. This also disables
1256 SLUB sysfs support. /sys/slab will not exist and there will be
1257 no support for cache validation etc.
1258
1259config COMPAT_BRK
1260 bool "Disable heap randomization"
1261 default y
1262 help
1263 Randomizing heap placement makes heap exploits harder, but it
1264 also breaks ancient binaries (including anything libc5 based).
1265 This option changes the bootup default to heap randomization
1266 disabled, and can be overridden at runtime by setting
1267 /proc/sys/kernel/randomize_va_space to 2.
1268
1269 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1270
1271choice
1272 prompt "Choose SLAB allocator"
1273 default SLUB
1274 help
1275 This option allows to select a slab allocator.
1276
1277config SLAB
1278 bool "SLAB"
1279 help
1280 The regular slab allocator that is established and known to work
1281 well in all environments. It organizes cache hot objects in
1282 per cpu and per node queues.
1283
1284config SLUB
1285 bool "SLUB (Unqueued Allocator)"
1286 depends on !PREEMPT_RT_FULL
1287 help
1288 SLUB is a slab allocator that minimizes cache line usage
1289 instead of managing queues of cached objects (SLAB approach).
1290 Per cpu caching is realized using slabs of objects instead
1291 of queues of objects. SLUB can use memory efficiently
1292 and has enhanced diagnostics. SLUB is the default choice for
1293 a slab allocator.
1294
1295config SLOB
1296 #depends on EXPERT
1297 bool "SLOB (Simple Allocator)"
1298 #depends on !PREEMPT_RT_FULL
1299 help
1300 SLOB replaces the stock allocator with a drastically simpler
1301 allocator. SLOB is generally more space efficient but
1302 does not perform as well on large systems.
1303
1304config SLOB_OPT
1305 bool
1306 depends on SLOB
1307 default y
1308
1309endchoice
1310
1311config MMAP_ALLOW_UNINITIALIZED
1312 bool "Allow mmapped anonymous memory to be uninitialized"
1313 depends on EXPERT && !MMU
1314 default n
1315 help
1316 Normally, and according to the Linux spec, anonymous memory obtained
1317 from mmap() has it's contents cleared before it is passed to
1318 userspace. Enabling this config option allows you to request that
1319 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1320 providing a huge performance boost. If this option is not enabled,
1321 then the flag will be ignored.
1322
1323 This is taken advantage of by uClibc's malloc(), and also by
1324 ELF-FDPIC binfmt's brk and stack allocator.
1325
1326 Because of the obvious security issues, this option should only be
1327 enabled on embedded devices where you control what is run in
1328 userspace. Since that isn't generally a problem on no-MMU systems,
1329 it is normally safe to say Y here.
1330
1331 See Documentation/nommu-mmap.txt for more information.
1332
1333config PROFILING
1334 bool "Profiling support"
1335 help
1336 Say Y here to enable the extended profiling support mechanisms used
1337 by profilers such as OProfile.
1338
1339#
1340# Place an empty function call at each tracepoint site. Can be
1341# dynamically changed for a probe function.
1342#
1343config TRACEPOINTS
1344 bool
1345
1346source "arch/Kconfig"
1347
1348endmenu # General setup
1349
1350config HAVE_GENERIC_DMA_COHERENT
1351 bool
1352 default n
1353
1354config SLABINFO
1355 bool
1356 depends on PROC_FS
1357 depends on SLAB || SLUB_DEBUG
1358 default y
1359
1360config RT_MUTEXES
1361 boolean
1362
1363config BASE_SMALL
1364 int
1365 default 0 if BASE_FULL
1366 default 1 if !BASE_FULL
1367
1368menuconfig MODULES
1369 bool "Enable loadable module support"
1370 help
1371 Kernel modules are small pieces of compiled code which can
1372 be inserted in the running kernel, rather than being
1373 permanently built into the kernel. You use the "modprobe"
1374 tool to add (and sometimes remove) them. If you say Y here,
1375 many parts of the kernel can be built as modules (by
1376 answering M instead of Y where indicated): this is most
1377 useful for infrequently used options which are not required
1378 for booting. For more information, see the man pages for
1379 modprobe, lsmod, modinfo, insmod and rmmod.
1380
1381 If you say Y here, you will need to run "make
1382 modules_install" to put the modules under /lib/modules/
1383 where modprobe can find them (you may need to be root to do
1384 this).
1385
1386 If unsure, say Y.
1387
1388if MODULES
1389
1390config MODULE_FORCE_LOAD
1391 bool "Forced module loading"
1392 default n
1393 help
1394 Allow loading of modules without version information (ie. modprobe
1395 --force). Forced module loading sets the 'F' (forced) taint flag and
1396 is usually a really bad idea.
1397
1398config MODULE_UNLOAD
1399 bool "Module unloading"
1400 help
1401 Without this option you will not be able to unload any
1402 modules (note that some modules may not be unloadable
1403 anyway), which makes your kernel smaller, faster
1404 and simpler. If unsure, say Y.
1405
1406config MODULE_FORCE_UNLOAD
1407 bool "Forced module unloading"
1408 depends on MODULE_UNLOAD && EXPERIMENTAL
1409 help
1410 This option allows you to force a module to unload, even if the
1411 kernel believes it is unsafe: the kernel will remove the module
1412 without waiting for anyone to stop using it (using the -f option to
1413 rmmod). This is mainly for kernel developers and desperate users.
1414 If unsure, say N.
1415
1416config MODVERSIONS
1417 bool "Module versioning support"
1418 help
1419 Usually, you have to use modules compiled with your kernel.
1420 Saying Y here makes it sometimes possible to use modules
1421 compiled for different kernels, by adding enough information
1422 to the modules to (hopefully) spot any changes which would
1423 make them incompatible with the kernel you are running. If
1424 unsure, say N.
1425
1426config MODULE_SRCVERSION_ALL
1427 bool "Source checksum for all modules"
1428 help
1429 Modules which contain a MODULE_VERSION get an extra "srcversion"
1430 field inserted into their modinfo section, which contains a
1431 sum of the source files which made it. This helps maintainers
1432 see exactly which source was used to build a module (since
1433 others sometimes change the module source without updating
1434 the version). With this option, such a "srcversion" field
1435 will be created for all modules. If unsure, say N.
1436
1437endif # MODULES
1438
1439config INIT_ALL_POSSIBLE
1440 bool
1441 help
1442 Back when each arch used to define their own cpu_online_mask and
1443 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
1444 with all 1s, and others with all 0s. When they were centralised,
1445 it was better to provide this option than to break all the archs
1446 and have several arch maintainers pursuing me down dark alleys.
1447
1448config STOP_MACHINE
1449 bool
1450 default y
1451 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1452 help
1453 Need stop_machine() primitive.
1454
1455source "block/Kconfig"
1456
1457config PREEMPT_NOTIFIERS
1458 bool
1459
1460config PADATA
1461 depends on SMP
1462 bool
1463
1464source "kernel/Kconfig.locks"