1config 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 default y
23
24config HAVE_IRQ_WORK
25 bool
26
27config IRQ_WORK
28 bool
29 depends on HAVE_IRQ_WORK
30
31menu "General setup"
32
33config EXPERIMENTAL
34 bool "Prompt for development and/or incomplete code/drivers"
35 ---help---
36 Some of the various things that Linux supports (such as network
37 drivers, file systems, network protocols, etc.) can be in a state
38 of development where the functionality, stability, or the level of
39 testing is not yet high enough for general use. This is usually
40 known as the "alpha-test" phase among developers. If a feature is
41 currently in alpha-test, then the developers usually discourage
42 uninformed widespread use of this feature by the general public to
43 avoid "Why doesn't this work?" type mail messages. However, active
44 testing and use of these systems is welcomed. Just be aware that it
45 may not meet the normal level of reliability or it may fail to work
46 in some special cases. Detailed bug reports from people familiar
47 with the kernel internals are usually welcomed by the developers
48 (before submitting bug reports, please read the documents
49 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
50 <file:Documentation/BUG-HUNTING>, and
51 <file:Documentation/oops-tracing.txt> in the kernel source).
52
53 This option will also make obsoleted drivers available. These are
54 drivers that have been replaced by something else, and/or are
55 scheduled to be removed in a future kernel release.
56
57 Unless you intend to help test and develop a feature or driver that
58 falls into this category, or you have a situation that requires
59 using these features, you should probably say N here, which will
60 cause the configurator to present you with fewer choices. If
61 you say Y here, you will be offered the choice of using features or
62 drivers that are currently considered to be in the alpha-test phase.
63
64config BROKEN
65 bool
66
67config BROKEN_ON_SMP
68 bool
69 depends on BROKEN || !SMP
70 default y
71
72config LOCK_KERNEL
73 bool
74 depends on (SMP || PREEMPT) && BKL
75 default y
76
77config INIT_ENV_ARG_LIMIT
78 int
79 default 32 if !UML
80 default 128 if UML
81 help
82 Maximum of each of the number of arguments and environment
83 variables passed to init from the kernel command line.
84
85
86config CROSS_COMPILE
87 string "Cross-compiler tool prefix"
88 help
89 Same as running 'make CROSS_COMPILE=prefix-' but stored for
90 default make runs in this kernel build directory. You don't
91 need to set this unless you want the configured kernel build
92 directory to select the cross-compiler automatically.
93
94config LOCALVERSION
95 string "Local version - append to kernel release"
96 help
97 Append an extra string to the end of your kernel version.
98 This will show up when you type uname, for example.
99 The string you set here will be appended after the contents of
100 any files with a filename matching localversion* in your
101 object and source tree, in that order. Your total string can
102 be a maximum of 64 characters.
103
104config LOCALVERSION_AUTO
105 bool "Automatically append version information to the version string"
106 default y
107 help
108 This will try to automatically determine if the current tree is a
109 release tree by looking for git tags that belong to the current
110 top of tree revision.
111
112 A string of the format -gxxxxxxxx will be added to the localversion
113 if a git-based tree is found. The string generated by this will be
114 appended after any matching localversion* files, and after the value
115 set in CONFIG_LOCALVERSION.
116
117 (The actual string used here is the first eight characters produced
118 by running the command:
119
120 $ git rev-parse --verify HEAD
121
122 which is done within the script "scripts/setlocalversion".)
123
124config HAVE_KERNEL_GZIP
125 bool
126
127config HAVE_KERNEL_BZIP2
128 bool
129
130config HAVE_KERNEL_LZMA
131 bool
132
133config HAVE_KERNEL_XZ
134 bool
135
136config HAVE_KERNEL_LZO
137 bool
138
139choice
140 prompt "Kernel compression mode"
141 default KERNEL_GZIP
142 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
143 help
144 The linux kernel is a kind of self-extracting executable.
145 Several compression algorithms are available, which differ
146 in efficiency, compression and decompression speed.
147 Compression speed is only relevant when building a kernel.
148 Decompression speed is relevant at each boot.
149
150 If you have any problems with bzip2 or lzma compressed
151 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
152 version of this functionality (bzip2 only), for 2.4, was
153 supplied by Christian Ludwig)
154
155 High compression options are mostly useful for users, who
156 are low on disk space (embedded systems), but for whom ram
157 size matters less.
158
159 If in doubt, select 'gzip'
160
161config KERNEL_GZIP
162 bool "Gzip"
163 depends on HAVE_KERNEL_GZIP
164 help
165 The old and tried gzip compression. It provides a good balance
166 between compression ratio and decompression speed.
167
168config KERNEL_BZIP2
169 bool "Bzip2"
170 depends on HAVE_KERNEL_BZIP2
171 help
172 Its compression ratio and speed is intermediate.
173 Decompression speed is slowest among the three. The kernel
174 size is about 10% smaller with bzip2, in comparison to gzip.
175 Bzip2 uses a large amount of memory. For modern kernels you
176 will need at least 8MB RAM or more for booting.
177
178config KERNEL_LZMA
179 bool "LZMA"
180 depends on HAVE_KERNEL_LZMA
181 help
182 The most recent compression algorithm.
183 Its ratio is best, decompression speed is between the other
184 two. Compression is slowest. The kernel size is about 33%
185 smaller with LZMA in comparison to gzip.
186
187config KERNEL_XZ
188 bool "XZ"
189 depends on HAVE_KERNEL_XZ
190 help
191 XZ uses the LZMA2 algorithm and instruction set specific
192 BCJ filters which can improve compression ratio of executable
193 code. The size of the kernel is about 30% smaller with XZ in
194 comparison to gzip. On architectures for which there is a BCJ
195 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
196 will create a few percent smaller kernel than plain LZMA.
197
198 The speed is about the same as with LZMA: The decompression
199 speed of XZ is better than that of bzip2 but worse than gzip
200 and LZO. Compression is slow.
201
202config KERNEL_LZO
203 bool "LZO"
204 depends on HAVE_KERNEL_LZO
205 help
206 Its compression ratio is the poorest among the 4. The kernel
207 size is about 10% bigger than gzip; however its speed
208 (both compression and decompression) is the fastest.
209
210endchoice
211
212config SWAP
213 bool "Support for paging of anonymous memory (swap)"
214 depends on MMU && BLOCK
215 default y
216 help
217 This option allows you to choose whether you want to have support
218 for so called swap devices or swap files in your kernel that are
219 used to provide more virtual memory than the actual RAM present
220 in your computer. If unsure say Y.
221
222config SYSVIPC
223 bool "System V IPC"
224 ---help---
225 Inter Process Communication is a suite of library functions and
226 system calls which let processes (running programs) synchronize and
227 exchange information. It is generally considered to be a good thing,
228 and some programs won't run unless you say Y here. In particular, if
229 you want to run the DOS emulator dosemu under Linux (read the
230 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html
231 you'll need to say Y here.
232
233 You can find documentation about IPC with "info ipc" and also in
234 section 6.4 of the Linux Programmer's Guide, available from
235 <http://www.tldp.org/guides.html>.
236
237config SYSVIPC_SYSCTL
238 bool
239 depends on SYSVIPC
240 depends on SYSCTL
241 default y
242
243config POSIX_MQUEUE
244 bool "POSIX Message Queues"
245 depends on NET && EXPERIMENTAL
246 ---help---
247 POSIX variant of message queues is a part of IPC. In POSIX message
248 queues every message has a priority which decides about succession
249 of receiving it by a process. If you want to compile and run
250 programs written e.g. for Solaris with use of its POSIX message
251 queues (functions mq_*) say Y here.
252
253 POSIX message queues are visible as a filesystem called 'mqueue'
254 and can be mounted somewhere if you want to do filesystem
255 operations on message queues.
256
257 If unsure, say Y.
258
259config POSIX_MQUEUE_SYSCTL
260 bool
261 depends on POSIX_MQUEUE
262 depends on SYSCTL
263 default y
264
265config BSD_PROCESS_ACCT
266 bool "BSD Process Accounting"
267 help
268 If you say Y here, a user level program will be able to instruct the
269 kernel (via a special system call) to write process accounting
270 information to a file: whenever a process exits, information about
271 that process will be appended to the file by the kernel. The
272 information includes things such as creation time, owning user,
273 command name, memory usage, controlling terminal etc. (the complete
274 list is in the struct acct in <file:include/linux/acct.h>). It is
275 up to the user level program to do useful things with this
276 information. This is generally a good idea, so say Y.
277
278config BSD_PROCESS_ACCT_V3
279 bool "BSD Process Accounting version 3 file format"
280 depends on BSD_PROCESS_ACCT
281 default n
282 help
283 If you say Y here, the process accounting information is written
284 in a new file format that also logs the process IDs of each
285 process and it's parent. Note that this file format is incompatible
286 with previous v0/v1/v2 file formats, so you will need updated tools
287 for processing it. A preliminary version of these tools is available
288 at <http://www.gnu.org/software/acct/>.
289
290config TASKSTATS
291 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
292 depends on NET
293 default n
294 help
295 Export selected statistics for tasks/processes through the
296 generic netlink interface. Unlike BSD process accounting, the
297 statistics are available during the lifetime of tasks/processes as
298 responses to commands. Like BSD accounting, they are sent to user
299 space on task exit.
300
301 Say N if unsure.
302
303config TASK_DELAY_ACCT
304 bool "Enable per-task delay accounting (EXPERIMENTAL)"
305 depends on TASKSTATS
306 help
307 Collect information on time spent by a task waiting for system
308 resources like cpu, synchronous block I/O completion and swapping
309 in pages. Such statistics can help in setting a task's priorities
310 relative to other tasks for cpu, io, rss limits etc.
311
312 Say N if unsure.
313
314config TASK_XACCT
315 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
316 depends on TASKSTATS
317 help
318 Collect extended task accounting data and send the data
319 to userland for processing over the taskstats interface.
320
321 Say N if unsure.
322
323config TASK_IO_ACCOUNTING
324 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
325 depends on TASK_XACCT
326 help
327 Collect information on the number of bytes of storage I/O which this
328 task has caused.
329
330 Say N if unsure.
331
332config AUDIT
333 bool "Auditing support"
334 depends on NET
335 help
336 Enable auditing infrastructure that can be used with another
337 kernel subsystem, such as SELinux (which requires this for
338 logging of avc messages output). Does not do system-call
339 auditing without CONFIG_AUDITSYSCALL.
340
341config AUDITSYSCALL
342 bool "Enable system-call auditing support"
343 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
344 default y if SECURITY_SELINUX
345 help
346 Enable low-overhead system-call auditing infrastructure that
347 can be used independently or with another kernel subsystem,
348 such as SELinux.
349
350config AUDIT_WATCH
351 def_bool y
352 depends on AUDITSYSCALL
353 select FSNOTIFY
354
355config AUDIT_TREE
356 def_bool y
357 depends on AUDITSYSCALL
358 select FSNOTIFY
359
360source "kernel/irq/Kconfig"
361
362menu "RCU Subsystem"
363
364choice
365 prompt "RCU Implementation"
366 default TREE_RCU
367
368config TREE_RCU
369 bool "Tree-based hierarchical RCU"
370 depends on !PREEMPT && SMP
371 help
372 This option selects the RCU implementation that is
373 designed for very large SMP system with hundreds or
374 thousands of CPUs. It also scales down nicely to
375 smaller systems.
376
377config TREE_PREEMPT_RCU
378 bool "Preemptible tree-based hierarchical RCU"
379 depends on PREEMPT
380 help
381 This option selects the RCU implementation that is
382 designed for very large SMP systems with hundreds or
383 thousands of CPUs, but for which real-time response
384 is also required. It also scales down nicely to
385 smaller systems.
386
387config TINY_RCU
388 bool "UP-only small-memory-footprint RCU"
389 depends on !SMP
390 help
391 This option selects the RCU implementation that is
392 designed for UP systems from which real-time response
393 is not required. This option greatly reduces the
394 memory footprint of RCU.
395
396config TINY_PREEMPT_RCU
397 bool "Preemptible UP-only small-memory-footprint RCU"
398 depends on !SMP && PREEMPT
399 help
400 This option selects the RCU implementation that is designed
401 for real-time UP systems. This option greatly reduces the
402 memory footprint of RCU.
403
404endchoice
405
406config PREEMPT_RCU
407 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
408 help
409 This option enables preemptible-RCU code that is common between
410 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
411
412config RCU_TRACE
413 bool "Enable tracing for RCU"
414 help
415 This option provides tracing in RCU which presents stats
416 in debugfs for debugging RCU implementation.
417
418 Say Y here if you want to enable RCU tracing
419 Say N if you are unsure.
420
421config RCU_FANOUT
422 int "Tree-based hierarchical RCU fanout value"
423 range 2 64 if 64BIT
424 range 2 32 if !64BIT
425 depends on TREE_RCU || TREE_PREEMPT_RCU
426 default 64 if 64BIT
427 default 32 if !64BIT
428 help
429 This option controls the fanout of hierarchical implementations
430 of RCU, allowing RCU to work efficiently on machines with
431 large numbers of CPUs. This value must be at least the fourth
432 root of NR_CPUS, which allows NR_CPUS to be insanely large.
433 The default value of RCU_FANOUT should be used for production
434 systems, but if you are stress-testing the RCU implementation
435 itself, small RCU_FANOUT values allow you to test large-system
436 code paths on small(er) systems.
437
438 Select a specific number if testing RCU itself.
439 Take the default if unsure.
440
441config RCU_FANOUT_EXACT
442 bool "Disable tree-based hierarchical RCU auto-balancing"
443 depends on TREE_RCU || TREE_PREEMPT_RCU
444 default n
445 help
446 This option forces use of the exact RCU_FANOUT value specified,
447 regardless of imbalances in the hierarchy. This is useful for
448 testing RCU itself, and might one day be useful on systems with
449 strong NUMA behavior.
450
451 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
452
453 Say N if unsure.
454
455config RCU_FAST_NO_HZ
456 bool "Accelerate last non-dyntick-idle CPU's grace periods"
457 depends on TREE_RCU && NO_HZ && SMP
458 default n
459 help
460 This option causes RCU to attempt to accelerate grace periods
461 in order to allow the final CPU to enter dynticks-idle state
462 more quickly. On the other hand, this option increases the
463 overhead of the dynticks-idle checking, particularly on systems
464 with large numbers of CPUs.
465
466 Say Y if energy efficiency is critically important, particularly
467 if you have relatively few CPUs.
468
469 Say N if you are unsure.
470
471config TREE_RCU_TRACE
472 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
473 select DEBUG_FS
474 help
475 This option provides tracing for the TREE_RCU and
476 TREE_PREEMPT_RCU implementations, permitting Makefile to
477 trivially select kernel/rcutree_trace.c.
478
479config RCU_BOOST
480 bool "Enable RCU priority boosting"
481 depends on RT_MUTEXES && TINY_PREEMPT_RCU
482 default n
483 help
484 This option boosts the priority of preempted RCU readers that
485 block the current preemptible RCU grace period for too long.
486 This option also prevents heavy loads from blocking RCU
487 callback invocation for all flavors of RCU.
488
489 Say Y here if you are working with real-time apps or heavy loads
490 Say N here if you are unsure.
491
492config RCU_BOOST_PRIO
493 int "Real-time priority to boost RCU readers to"
494 range 1 99
495 depends on RCU_BOOST
496 default 1
497 help
498 This option specifies the real-time priority to which preempted
499 RCU readers are to be boosted. If you are working with CPU-bound
500 real-time applications, you should specify a priority higher then
501 the highest-priority CPU-bound application.
502
503 Specify the real-time priority, or take the default if unsure.
504
505config RCU_BOOST_DELAY
506 int "Milliseconds to delay boosting after RCU grace-period start"
507 range 0 3000
508 depends on RCU_BOOST
509 default 500
510 help
511 This option specifies the time to wait after the beginning of
512 a given grace period before priority-boosting preempted RCU
513 readers blocking that grace period. Note that any RCU reader
514 blocking an expedited RCU grace period is boosted immediately.
515
516 Accept the default if unsure.
517
518endmenu
519
520config IKCONFIG
521 tristate "Kernel .config support"
522 ---help---
523 This option enables the complete Linux kernel ".config" file
524 contents to be saved in the kernel. It provides documentation
525 of which kernel options are used in a running kernel or in an
526 on-disk kernel. This information can be extracted from the kernel
527 image file with the script scripts/extract-ikconfig and used as
528 input to rebuild the current kernel or to build another kernel.
529 It can also be extracted from a running kernel by reading
530 /proc/config.gz if enabled (below).
531
532config IKCONFIG_PROC
533 bool "Enable access to .config through /proc/config.gz"
534 depends on IKCONFIG && PROC_FS
535 ---help---
536 This option enables access to the kernel configuration file
537 through /proc/config.gz.
538
539config LOG_BUF_SHIFT
540 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
541 range 12 21
542 default 17
543 help
544 Select kernel log buffer size as a power of 2.
545 Examples:
546 17 => 128 KB
547 16 => 64 KB
548 15 => 32 KB
549 14 => 16 KB
550 13 => 8 KB
551 12 => 4 KB
552
553
554
555
556config HAVE_UNSTABLE_SCHED_CLOCK
557 bool
558
559menuconfig CGROUPS
560 boolean "Control Group support"
561 depends on EVENTFD
562 help
563 This option adds support for grouping sets of processes together, for
564 use with process control subsystems such as Cpusets, CFS, memory
565 controls or device isolation.
566 See
567 - Documentation/scheduler/sched-design-CFS.txt (CFS)
568 - Documentation/cgroups/ (features for grouping, isolation
569 and resource control)
570
571 Say N if unsure.
572
573if CGROUPS
574
575config CGROUP_DEBUG
576 bool "Example debug cgroup subsystem"
577 default n
578 help
579 This option enables a simple cgroup subsystem that
580 exports useful debugging information about the cgroups
581 framework.
582
583 Say N if unsure.
584
585config CGROUP_NS
586 bool "Namespace cgroup subsystem"
587 help
588 Provides a simple namespace cgroup subsystem to
589 provide hierarchical naming of sets of namespaces,
590 for instance virtual servers and checkpoint/restart
591 jobs.
592
593config CGROUP_FREEZER
594 bool "Freezer cgroup subsystem"
595 help
596 Provides a way to freeze and unfreeze all tasks in a
597 cgroup.
598
599config CGROUP_DEVICE
600 bool "Device controller for cgroups"
601 help
602 Provides a cgroup implementing whitelists for devices which
603 a process in the cgroup can mknod or open.
604
605config CPUSETS
606 bool "Cpuset support"
607 help
608 This option will let you create and manage CPUSETs which
609 allow dynamically partitioning a system into sets of CPUs and
610 Memory Nodes and assigning tasks to run only within those sets.
611 This is primarily useful on large SMP or NUMA systems.
612
613 Say N if unsure.
614
615config PROC_PID_CPUSET
616 bool "Include legacy /proc/<pid>/cpuset file"
617 depends on CPUSETS
618 default y
619
620config CGROUP_CPUACCT
621 bool "Simple CPU accounting cgroup subsystem"
622 help
623 Provides a simple Resource Controller for monitoring the
624 total CPU consumed by the tasks in a cgroup.
625
626config RESOURCE_COUNTERS
627 bool "Resource counters"
628 help
629 This option enables controller independent resource accounting
630 infrastructure that works with cgroups.
631
632config CGROUP_MEM_RES_CTLR
633 bool "Memory Resource Controller for Control Groups"
634 depends on RESOURCE_COUNTERS
635 select MM_OWNER
636 help
637 Provides a memory resource controller that manages both anonymous
638 memory and page cache. (See Documentation/cgroups/memory.txt)
639
640 Note that setting this option increases fixed memory overhead
641 associated with each page of memory in the system. By this,
642 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
643 usage tracking struct at boot. Total amount of this is printed out
644 at boot.
645
646 Only enable when you're ok with these trade offs and really
647 sure you need the memory resource controller. Even when you enable
648 this, you can set "cgroup_disable=memory" at your boot option to
649 disable memory resource controller and you can avoid overheads.
650 (and lose benefits of memory resource controller)
651
652 This config option also selects MM_OWNER config option, which
653 could in turn add some fork/exit overhead.
654
655config CGROUP_MEM_RES_CTLR_SWAP
656 bool "Memory Resource Controller Swap Extension"
657 depends on CGROUP_MEM_RES_CTLR && SWAP
658 help
659 Add swap management feature to memory resource controller. When you
660 enable this, you can limit mem+swap usage per cgroup. In other words,
661 when you disable this, memory resource controller has no cares to
662 usage of swap...a process can exhaust all of the swap. This extension
663 is useful when you want to avoid exhaustion swap but this itself
664 adds more overheads and consumes memory for remembering information.
665 Especially if you use 32bit system or small memory system, please
666 be careful about enabling this. When memory resource controller
667 is disabled by boot option, this will be automatically disabled and
668 there will be no overhead from this. Even when you set this config=y,
669 if boot option "noswapaccount" is set, swap will not be accounted.
670 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
671 size is 4096bytes, 512k per 1Gbytes of swap.
672config CGROUP_MEM_RES_CTLR_SWAP_ENABLED
673 bool "Memory Resource Controller Swap Extension enabled by default"
674 depends on CGROUP_MEM_RES_CTLR_SWAP
675 default y
676 help
677 Memory Resource Controller Swap Extension comes with its price in
678 a bigger memory consumption. General purpose distribution kernels
679 which want to enable the feature but keep it disabled by default
680 and let the user enable it by swapaccount boot command line
681 parameter should have this option unselected.
682 For those who want to have the feature enabled by default should
683 select this option (if, for some reason, they need to disable it
684 then noswapaccount does the trick).
685
686menuconfig CGROUP_SCHED
687 bool "Group CPU scheduler"
688 depends on EXPERIMENTAL
689 default n
690 help
691 This feature lets CPU scheduler recognize task groups and control CPU
692 bandwidth allocation to such task groups. It uses cgroups to group
693 tasks.
694
695if CGROUP_SCHED
696config FAIR_GROUP_SCHED
697 bool "Group scheduling for SCHED_OTHER"
698 depends on CGROUP_SCHED
699 default CGROUP_SCHED
700
701config RT_GROUP_SCHED
702 bool "Group scheduling for SCHED_RR/FIFO"
703 depends on EXPERIMENTAL
704 depends on CGROUP_SCHED
705 default n
706 help
707 This feature lets you explicitly allocate real CPU bandwidth
708 to task groups. If enabled, it will also make it impossible to
709 schedule realtime tasks for non-root users until you allocate
710 realtime bandwidth for them.
711 See Documentation/scheduler/sched-rt-group.txt for more information.
712
713endif
714
715config BLK_CGROUP
716 tristate "Block IO controller"
717 depends on BLOCK
718 default n
719 ---help---
720 Generic block IO controller cgroup interface. This is the common
721 cgroup interface which should be used by various IO controlling
722 policies.
723
724 Currently, CFQ IO scheduler uses it to recognize task groups and
725 control disk bandwidth allocation (proportional time slice allocation)
726 to such task groups. It is also used by bio throttling logic in
727 block layer to implement upper limit in IO rates on a device.
728
729 This option only enables generic Block IO controller infrastructure.
730 One needs to also enable actual IO controlling logic/policy. For
731 enabling proportional weight division of disk bandwidth in CFQ seti
732 CONFIG_CFQ_GROUP_IOSCHED=y and for enabling throttling policy set
733 CONFIG_BLK_THROTTLE=y.
734
735 See Documentation/cgroups/blkio-controller.txt for more information.
736
737config DEBUG_BLK_CGROUP
738 bool "Enable Block IO controller debugging"
739 depends on BLK_CGROUP
740 default n
741 ---help---
742 Enable some debugging help. Currently it exports additional stat
743 files in a cgroup which can be useful for debugging.
744
745endif
746
747menuconfig NAMESPACES
748 bool "Namespaces support" if EXPERT
749 default !EXPERT
750 help
751 Provides the way to make tasks work with different objects using
752 the same id. For example same IPC id may refer to different objects
753 or same user id or pid may refer to different tasks when used in
754 different namespaces.
755
756if NAMESPACES
757
758config UTS_NS
759 bool "UTS namespace"
760 default y
761 help
762 In this namespace tasks see different info provided with the
763 uname() system call
764
765config IPC_NS
766 bool "IPC namespace"
767 depends on (SYSVIPC || POSIX_MQUEUE)
768 default y
769 help
770 In this namespace tasks work with IPC ids which correspond to
771 different IPC objects in different namespaces.
772
773config USER_NS
774 bool "User namespace (EXPERIMENTAL)"
775 depends on EXPERIMENTAL
776 default y
777 help
778 This allows containers, i.e. vservers, to use user namespaces
779 to provide different user info for different servers.
780 If unsure, say N.
781
782config PID_NS
783 bool "PID Namespaces"
784 default y
785 help
786 Support process id namespaces. This allows having multiple
787 processes with the same pid as long as they are in different
788 pid namespaces. This is a building block of containers.
789
790config NET_NS
791 bool "Network namespace"
792 depends on NET
793 default y
794 help
795 Allow user space to create what appear to be multiple instances
796 of the network stack.
797
798endif
799
800config SCHED_AUTOGROUP
801 bool "Automatic process group scheduling"
802 select EVENTFD
803 select CGROUPS
804 select CGROUP_SCHED
805 select FAIR_GROUP_SCHED
806 help
807 This option optimizes the scheduler for common desktop workloads by
808 automatically creating and populating task groups. This separation
809 of workloads isolates aggressive CPU burners (like build jobs) from
810 desktop applications. Task group autogeneration is currently based
811 upon task session.
812
813config MM_OWNER
814 bool
815
816config SYSFS_DEPRECATED
817 bool "enable deprecated sysfs features to support old userspace tools"
818 depends on SYSFS
819 default n
820 help
821 This option adds code that switches the layout of the "block" class
822 devices, to not show up in /sys/class/block/, but only in
823 /sys/block/.
824
825 This switch is only active when the sysfs.deprecated=1 boot option is
826 passed or the SYSFS_DEPRECATED_V2 option is set.
827
828 This option allows new kernels to run on old distributions and tools,
829 which might get confused by /sys/class/block/. Since 2007/2008 all
830 major distributions and tools handle this just fine.
831
832 Recent distributions and userspace tools after 2009/2010 depend on
833 the existence of /sys/class/block/, and will not work with this
834 option enabled.
835
836 Only if you are using a new kernel on an old distribution, you might
837 need to say Y here.
838
839config SYSFS_DEPRECATED_V2
840 bool "enabled deprecated sysfs features by default"
841 default n
842 depends on SYSFS
843 depends on SYSFS_DEPRECATED
844 help
845 Enable deprecated sysfs by default.
846
847 See the CONFIG_SYSFS_DEPRECATED option for more details about this
848 option.
849
850 Only if you are using a new kernel on an old distribution, you might
851 need to say Y here. Even then, odds are you would not need it
852 enabled, you can always pass the boot option if absolutely necessary.
853
854config RELAY
855 bool "Kernel->user space relay support (formerly relayfs)"
856 help
857 This option enables support for relay interface support in
858 certain file systems (such as debugfs).
859 It is designed to provide an efficient mechanism for tools and
860 facilities to relay large amounts of data from kernel space to
861 user space.
862
863 If unsure, say N.
864
865config BLK_DEV_INITRD
866 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
867 depends on BROKEN || !FRV
868 help
869 The initial RAM filesystem is a ramfs which is loaded by the
870 boot loader (loadlin or lilo) and that is mounted as root
871 before the normal boot procedure. It is typically used to
872 load modules needed to mount the "real" root file system,
873 etc. See <file:Documentation/initrd.txt> for details.
874
875 If RAM disk support (BLK_DEV_RAM) is also included, this
876 also enables initial RAM disk (initrd) support and adds
877 15 Kbytes (more on some other architectures) to the kernel size.
878
879 If unsure say Y.
880
881if BLK_DEV_INITRD
882
883source "usr/Kconfig"
884
885endif
886
887config CC_OPTIMIZE_FOR_SIZE
888 bool "Optimize for size"
889 default y
890 help
891 Enabling this option will pass "-Os" instead of "-O2" to gcc
892 resulting in a smaller kernel.
893
894 If unsure, say Y.
895
896config SYSCTL
897 bool
898
899config ANON_INODES
900 bool
901
902menuconfig EXPERT
903 bool "Configure standard kernel features (expert users)"
904 help
905 This option allows certain base kernel options and settings
906 to be disabled or tweaked. This is for specialized
907 environments which can tolerate a "non-standard" kernel.
908 Only use this if you really know what you are doing.
909
910config EMBEDDED
911 bool "Embedded system"
912 select EXPERT
913 help
914 This option should be enabled if compiling the kernel for
915 an embedded system so certain expert options are available
916 for configuration.
917
918config UID16
919 bool "Enable 16-bit UID system calls" if EXPERT
920 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
921 default y
922 help
923 This enables the legacy 16-bit UID syscall wrappers.
924
925config SYSCTL_SYSCALL
926 bool "Sysctl syscall support" if EXPERT
927 depends on PROC_SYSCTL
928 default y
929 select SYSCTL
930 ---help---
931 sys_sysctl uses binary paths that have been found challenging
932 to properly maintain and use. The interface in /proc/sys
933 using paths with ascii names is now the primary path to this
934 information.
935
936 Almost nothing using the binary sysctl interface so if you are
937 trying to save some space it is probably safe to disable this,
938 making your kernel marginally smaller.
939
940 If unsure say Y here.
941
942config KALLSYMS
943 bool "Load all symbols for debugging/ksymoops" if EXPERT
944 default y
945 help
946 Say Y here to let the kernel print out symbolic crash information and
947 symbolic stack backtraces. This increases the size of the kernel
948 somewhat, as all symbols have to be loaded into the kernel image.
949
950config KALLSYMS_ALL
951 bool "Include all symbols in kallsyms"
952 depends on DEBUG_KERNEL && KALLSYMS
953 help
954 Normally kallsyms only contains the symbols of functions, for nicer
955 OOPS messages. Some debuggers can use kallsyms for other
956 symbols too: say Y here to include all symbols, if you need them
957 and you don't care about adding 300k to the size of your kernel.
958
959 Say N.
960
961config KALLSYMS_EXTRA_PASS
962 bool "Do an extra kallsyms pass"
963 depends on KALLSYMS
964 help
965 If kallsyms is not working correctly, the build will fail with
966 inconsistent kallsyms data. If that occurs, log a bug report and
967 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
968 Always say N here unless you find a bug in kallsyms, which must be
969 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
970 you wait for kallsyms to be fixed.
971
972
973config HOTPLUG
974 bool "Support for hot-pluggable devices" if EXPERT
975 default y
976 help
977 This option is provided for the case where no hotplug or uevent
978 capabilities is wanted by the kernel. You should only consider
979 disabling this option for embedded systems that do not use modules, a
980 dynamic /dev tree, or dynamic device discovery. Just say Y.
981
982config PRINTK
983 default y
984 bool "Enable support for printk" if EXPERT
985 help
986 This option enables normal printk support. Removing it
987 eliminates most of the message strings from the kernel image
988 and makes the kernel more or less silent. As this makes it
989 very difficult to diagnose system problems, saying N here is
990 strongly discouraged.
991
992config BUG
993 bool "BUG() support" if EXPERT
994 default y
995 help
996 Disabling this option eliminates support for BUG and WARN, reducing
997 the size of your kernel image and potentially quietly ignoring
998 numerous fatal conditions. You should only consider disabling this
999 option for embedded systems with no facilities for reporting errors.
1000 Just say Y.
1001
1002config ELF_CORE
1003 default y
1004 bool "Enable ELF core dumps" if EXPERT
1005 help
1006 Enable support for generating core dumps. Disabling saves about 4k.
1007
1008config PCSPKR_PLATFORM
1009 bool "Enable PC-Speaker support" if EXPERT
1010 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
1011 default y
1012 help
1013 This option allows to disable the internal PC-Speaker
1014 support, saving some memory.
1015
1016config BASE_FULL
1017 default y
1018 bool "Enable full-sized data structures for core" if EXPERT
1019 help
1020 Disabling this option reduces the size of miscellaneous core
1021 kernel data structures. This saves memory on small machines,
1022 but may reduce performance.
1023
1024config FUTEX
1025 bool "Enable futex support" if EXPERT
1026 default y
1027 select RT_MUTEXES
1028 help
1029 Disabling this option will cause the kernel to be built without
1030 support for "fast userspace mutexes". The resulting kernel may not
1031 run glibc-based applications correctly.
1032
1033config EPOLL
1034 bool "Enable eventpoll support" if EXPERT
1035 default y
1036 select ANON_INODES
1037 help
1038 Disabling this option will cause the kernel to be built without
1039 support for epoll family of system calls.
1040
1041config SIGNALFD
1042 bool "Enable signalfd() system call" if EXPERT
1043 select ANON_INODES
1044 default y
1045 help
1046 Enable the signalfd() system call that allows to receive signals
1047 on a file descriptor.
1048
1049 If unsure, say Y.
1050
1051config TIMERFD
1052 bool "Enable timerfd() system call" if EXPERT
1053 select ANON_INODES
1054 default y
1055 help
1056 Enable the timerfd() system call that allows to receive timer
1057 events on a file descriptor.
1058
1059 If unsure, say Y.
1060
1061config EVENTFD
1062 bool "Enable eventfd() system call" if EXPERT
1063 select ANON_INODES
1064 default y
1065 help
1066 Enable the eventfd() system call that allows to receive both
1067 kernel notification (ie. KAIO) or userspace notifications.
1068
1069 If unsure, say Y.
1070
1071config SHMEM
1072 bool "Use full shmem filesystem" if EXPERT
1073 default y
1074 depends on MMU
1075 help
1076 The shmem is an internal filesystem used to manage shared memory.
1077 It is backed by swap and manages resource limits. It is also exported
1078 to userspace as tmpfs if TMPFS is enabled. Disabling this
1079 option replaces shmem and tmpfs with the much simpler ramfs code,
1080 which may be appropriate on small systems without swap.
1081
1082config AIO
1083 bool "Enable AIO support" if EXPERT
1084 default y
1085 help
1086 This option enables POSIX asynchronous I/O which may by used
1087 by some high performance threaded applications. Disabling
1088 this option saves about 7k.
1089
1090config HAVE_PERF_EVENTS
1091 bool
1092 help
1093 See tools/perf/design.txt for details.
1094
1095config PERF_USE_VMALLOC
1096 bool
1097 help
1098 See tools/perf/design.txt for details
1099
1100menu "Kernel Performance Events And Counters"
1101
1102config PERF_EVENTS
1103 bool "Kernel performance events and counters"
1104 default y if (PROFILING || PERF_COUNTERS)
1105 depends on HAVE_PERF_EVENTS
1106 select ANON_INODES
1107 select IRQ_WORK
1108 help
1109 Enable kernel support for various performance events provided
1110 by software and hardware.
1111
1112 Software events are supported either built-in or via the
1113 use of generic tracepoints.
1114
1115 Most modern CPUs support performance events via performance
1116 counter registers. These registers count the number of certain
1117 types of hw events: such as instructions executed, cachemisses
1118 suffered, or branches mis-predicted - without slowing down the
1119 kernel or applications. These registers can also trigger interrupts
1120 when a threshold number of events have passed - and can thus be
1121 used to profile the code that runs on that CPU.
1122
1123 The Linux Performance Event subsystem provides an abstraction of
1124 these software and hardware event capabilities, available via a
1125 system call and used by the "perf" utility in tools/perf/. It
1126 provides per task and per CPU counters, and it provides event
1127 capabilities on top of those.
1128
1129 Say Y if unsure.
1130
1131config PERF_COUNTERS
1132 bool "Kernel performance counters (old config option)"
1133 depends on HAVE_PERF_EVENTS
1134 help
1135 This config has been obsoleted by the PERF_EVENTS
1136 config option - please see that one for details.
1137
1138 It has no effect on the kernel whether you enable
1139 it or not, it is a compatibility placeholder.
1140
1141 Say N if unsure.
1142
1143config DEBUG_PERF_USE_VMALLOC
1144 default n
1145 bool "Debug: use vmalloc to back perf mmap() buffers"
1146 depends on PERF_EVENTS && DEBUG_KERNEL
1147 select PERF_USE_VMALLOC
1148 help
1149 Use vmalloc memory to back perf mmap() buffers.
1150
1151 Mostly useful for debugging the vmalloc code on platforms
1152 that don't require it.
1153
1154 Say N if unsure.
1155
1156endmenu
1157
1158config VM_EVENT_COUNTERS
1159 default y
1160 bool "Enable VM event counters for /proc/vmstat" if EXPERT
1161 help
1162 VM event counters are needed for event counts to be shown.
1163 This option allows the disabling of the VM event counters
1164 on EXPERT systems. /proc/vmstat will only show page counts
1165 if VM event counters are disabled.
1166
1167config PCI_QUIRKS
1168 default y
1169 bool "Enable PCI quirk workarounds" if EXPERT
1170 depends on PCI
1171 help
1172 This enables workarounds for various PCI chipset
1173 bugs/quirks. Disable this only if your target machine is
1174 unaffected by PCI quirks.
1175
1176config SLUB_DEBUG
1177 default y
1178 bool "Enable SLUB debugging support" if EXPERT
1179 depends on SLUB && SYSFS
1180 help
1181 SLUB has extensive debug support features. Disabling these can
1182 result in significant savings in code size. This also disables
1183 SLUB sysfs support. /sys/slab will not exist and there will be
1184 no support for cache validation etc.
1185
1186config COMPAT_BRK
1187 bool "Disable heap randomization"
1188 default y
1189 help
1190 Randomizing heap placement makes heap exploits harder, but it
1191 also breaks ancient binaries (including anything libc5 based).
1192 This option changes the bootup default to heap randomization
1193 disabled, and can be overridden at runtime by setting
1194 /proc/sys/kernel/randomize_va_space to 2.
1195
1196 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1197
1198choice
1199 prompt "Choose SLAB allocator"
1200 default SLUB
1201 help
1202 This option allows to select a slab allocator.
1203
1204config SLAB
1205 bool "SLAB"
1206 help
1207 The regular slab allocator that is established and known to work
1208 well in all environments. It organizes cache hot objects in
1209 per cpu and per node queues.
1210
1211config SLUB
1212 bool "SLUB (Unqueued Allocator)"
1213 help
1214 SLUB is a slab allocator that minimizes cache line usage
1215 instead of managing queues of cached objects (SLAB approach).
1216 Per cpu caching is realized using slabs of objects instead
1217 of queues of objects. SLUB can use memory efficiently
1218 and has enhanced diagnostics. SLUB is the default choice for
1219 a slab allocator.
1220
1221config SLOB
1222 depends on EXPERT
1223 bool "SLOB (Simple Allocator)"
1224 help
1225 SLOB replaces the stock allocator with a drastically simpler
1226 allocator. SLOB is generally more space efficient but
1227 does not perform as well on large systems.
1228
1229endchoice
1230
1231config MMAP_ALLOW_UNINITIALIZED
1232 bool "Allow mmapped anonymous memory to be uninitialized"
1233 depends on EXPERT && !MMU
1234 default n
1235 help
1236 Normally, and according to the Linux spec, anonymous memory obtained
1237 from mmap() has it's contents cleared before it is passed to
1238 userspace. Enabling this config option allows you to request that
1239 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1240 providing a huge performance boost. If this option is not enabled,
1241 then the flag will be ignored.
1242
1243 This is taken advantage of by uClibc's malloc(), and also by
1244 ELF-FDPIC binfmt's brk and stack allocator.
1245
1246 Because of the obvious security issues, this option should only be
1247 enabled on embedded devices where you control what is run in
1248 userspace. Since that isn't generally a problem on no-MMU systems,
1249 it is normally safe to say Y here.
1250
1251 See Documentation/nommu-mmap.txt for more information.
1252
1253config PROFILING
1254 bool "Profiling support"
1255 help
1256 Say Y here to enable the extended profiling support mechanisms used
1257 by profilers such as OProfile.
1258
1259
1260
1261
1262
1263config TRACEPOINTS
1264 bool
1265
1266source "arch/Kconfig"
1267
1268endmenu
1269
1270config HAVE_GENERIC_DMA_COHERENT
1271 bool
1272 default n
1273
1274config SLABINFO
1275 bool
1276 depends on PROC_FS
1277 depends on SLAB || SLUB_DEBUG
1278 default y
1279
1280config RT_MUTEXES
1281 boolean
1282
1283config BASE_SMALL
1284 int
1285 default 0 if BASE_FULL
1286 default 1 if !BASE_FULL
1287
1288menuconfig MODULES
1289 bool "Enable loadable module support"
1290 help
1291 Kernel modules are small pieces of compiled code which can
1292 be inserted in the running kernel, rather than being
1293 permanently built into the kernel. You use the "modprobe"
1294 tool to add (and sometimes remove) them. If you say Y here,
1295 many parts of the kernel can be built as modules (by
1296 answering M instead of Y where indicated): this is most
1297 useful for infrequently used options which are not required
1298 for booting. For more information, see the man pages for
1299 modprobe, lsmod, modinfo, insmod and rmmod.
1300
1301 If you say Y here, you will need to run "make
1302 modules_install" to put the modules under /lib/modules/
1303 where modprobe can find them (you may need to be root to do
1304 this).
1305
1306 If unsure, say Y.
1307
1308if MODULES
1309
1310config MODULE_FORCE_LOAD
1311 bool "Forced module loading"
1312 default n
1313 help
1314 Allow loading of modules without version information (ie. modprobe
1315 --force). Forced module loading sets the 'F' (forced) taint flag and
1316 is usually a really bad idea.
1317
1318config MODULE_UNLOAD
1319 bool "Module unloading"
1320 help
1321 Without this option you will not be able to unload any
1322 modules (note that some modules may not be unloadable
1323 anyway), which makes your kernel smaller, faster
1324 and simpler. If unsure, say Y.
1325
1326config MODULE_FORCE_UNLOAD
1327 bool "Forced module unloading"
1328 depends on MODULE_UNLOAD && EXPERIMENTAL
1329 help
1330 This option allows you to force a module to unload, even if the
1331 kernel believes it is unsafe: the kernel will remove the module
1332 without waiting for anyone to stop using it (using the -f option to
1333 rmmod). This is mainly for kernel developers and desperate users.
1334 If unsure, say N.
1335
1336config MODVERSIONS
1337 bool "Module versioning support"
1338 help
1339 Usually, you have to use modules compiled with your kernel.
1340 Saying Y here makes it sometimes possible to use modules
1341 compiled for different kernels, by adding enough information
1342 to the modules to (hopefully) spot any changes which would
1343 make them incompatible with the kernel you are running. If
1344 unsure, say N.
1345
1346config MODULE_SRCVERSION_ALL
1347 bool "Source checksum for all modules"
1348 help
1349 Modules which contain a MODULE_VERSION get an extra "srcversion"
1350 field inserted into their modinfo section, which contains a
1351 sum of the source files which made it. This helps maintainers
1352 see exactly which source was used to build a module (since
1353 others sometimes change the module source without updating
1354 the version). With this option, such a "srcversion" field
1355 will be created for all modules. If unsure, say N.
1356
1357endif
1358
1359config INIT_ALL_POSSIBLE
1360 bool
1361 help
1362 Back when each arch used to define their own cpu_online_map and
1363 cpu_possible_map, some of them chose to initialize cpu_possible_map
1364 with all 1s, and others with all 0s. When they were centralised,
1365 it was better to provide this option than to break all the archs
1366 and have several arch maintainers pursuing me down dark alleys.
1367
1368config STOP_MACHINE
1369 bool
1370 default y
1371 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1372 help
1373 Need stop_machine() primitive.
1374
1375source "block/Kconfig"
1376
1377config PREEMPT_NOTIFIERS
1378 bool
1379
1380config PADATA
1381 depends on SMP
1382 bool
1383
1384source "kernel/Kconfig.locks"
1385
