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Roman Zippel80daa562008-01-14 04:51:16 +01001config ARCH
2 string
3 option env="ARCH"
4
5config KERNELVERSION
6 string
7 option env="KERNELVERSION"
8
Roman Zippelface4372006-06-08 22:12:45 -07009config DEFCONFIG_LIST
10 string
Paolo 'Blaisorblade' Giarrussob2670ea2006-10-19 23:28:23 -070011 depends on !UML
Roman Zippelface4372006-06-08 22:12:45 -070012 option defconfig_list
13 default "/lib/modules/$UNAME_RELEASE/.config"
14 default "/etc/kernel-config"
15 default "/boot/config-$UNAME_RELEASE"
Sam Ravnborg73531902008-05-25 23:03:18 +020016 default "$ARCH_DEFCONFIG"
Roman Zippelface4372006-06-08 22:12:45 -070017 default "arch/$ARCH/defconfig"
18
Al Boldiff0cfc62007-07-31 00:39:23 -070019menu "General setup"
Linus Torvalds1da177e2005-04-16 15:20:36 -070020
21config EXPERIMENTAL
22 bool "Prompt for development and/or incomplete code/drivers"
23 ---help---
24 Some of the various things that Linux supports (such as network
25 drivers, file systems, network protocols, etc.) can be in a state
26 of development where the functionality, stability, or the level of
27 testing is not yet high enough for general use. This is usually
28 known as the "alpha-test" phase among developers. If a feature is
29 currently in alpha-test, then the developers usually discourage
30 uninformed widespread use of this feature by the general public to
31 avoid "Why doesn't this work?" type mail messages. However, active
32 testing and use of these systems is welcomed. Just be aware that it
33 may not meet the normal level of reliability or it may fail to work
34 in some special cases. Detailed bug reports from people familiar
35 with the kernel internals are usually welcomed by the developers
36 (before submitting bug reports, please read the documents
37 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
38 <file:Documentation/BUG-HUNTING>, and
39 <file:Documentation/oops-tracing.txt> in the kernel source).
40
41 This option will also make obsoleted drivers available. These are
42 drivers that have been replaced by something else, and/or are
43 scheduled to be removed in a future kernel release.
44
45 Unless you intend to help test and develop a feature or driver that
46 falls into this category, or you have a situation that requires
47 using these features, you should probably say N here, which will
48 cause the configurator to present you with fewer choices. If
49 you say Y here, you will be offered the choice of using features or
50 drivers that are currently considered to be in the alpha-test phase.
51
Linus Torvalds1da177e2005-04-16 15:20:36 -070052config BROKEN
53 bool
Linus Torvalds1da177e2005-04-16 15:20:36 -070054
55config BROKEN_ON_SMP
56 bool
57 depends on BROKEN || !SMP
58 default y
59
60config LOCK_KERNEL
61 bool
62 depends on SMP || PREEMPT
63 default y
64
65config INIT_ENV_ARG_LIMIT
66 int
Adrian Bunkdd673bc2006-06-30 01:55:51 -070067 default 32 if !UML
68 default 128 if UML
Linus Torvalds1da177e2005-04-16 15:20:36 -070069 help
Randy Dunlap34ad92c2005-10-30 15:01:46 -080070 Maximum of each of the number of arguments and environment
71 variables passed to init from the kernel command line.
Linus Torvalds1da177e2005-04-16 15:20:36 -070072
Linus Torvalds1da177e2005-04-16 15:20:36 -070073
74config LOCALVERSION
75 string "Local version - append to kernel release"
76 help
77 Append an extra string to the end of your kernel version.
78 This will show up when you type uname, for example.
79 The string you set here will be appended after the contents of
80 any files with a filename matching localversion* in your
81 object and source tree, in that order. Your total string can
82 be a maximum of 64 characters.
83
Ryan Andersonaaebf432005-07-31 04:57:49 -040084config LOCALVERSION_AUTO
85 bool "Automatically append version information to the version string"
86 default y
87 help
88 This will try to automatically determine if the current tree is a
Robert P. J. Day6e5a5422007-05-01 23:08:11 +020089 release tree by looking for git tags that belong to the current
90 top of tree revision.
Ryan Andersonaaebf432005-07-31 04:57:49 -040091
92 A string of the format -gxxxxxxxx will be added to the localversion
Robert P. J. Day6e5a5422007-05-01 23:08:11 +020093 if a git-based tree is found. The string generated by this will be
Ryan Andersonaaebf432005-07-31 04:57:49 -040094 appended after any matching localversion* files, and after the value
Robert P. J. Day6e5a5422007-05-01 23:08:11 +020095 set in CONFIG_LOCALVERSION.
Ryan Andersonaaebf432005-07-31 04:57:49 -040096
Robert P. J. Day6e5a5422007-05-01 23:08:11 +020097 (The actual string used here is the first eight characters produced
98 by running the command:
99
100 $ git rev-parse --verify HEAD
101
102 which is done within the script "scripts/setlocalversion".)
Ryan Andersonaaebf432005-07-31 04:57:49 -0400103
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104config SWAP
105 bool "Support for paging of anonymous memory (swap)"
David Howells93614012006-09-30 20:45:40 +0200106 depends on MMU && BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107 default y
108 help
109 This option allows you to choose whether you want to have support
Jesper Juhl92c35042006-01-15 02:40:08 +0100110 for so called swap devices or swap files in your kernel that are
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111 used to provide more virtual memory than the actual RAM present
112 in your computer. If unsure say Y.
113
114config SYSVIPC
115 bool "System V IPC"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116 ---help---
117 Inter Process Communication is a suite of library functions and
118 system calls which let processes (running programs) synchronize and
119 exchange information. It is generally considered to be a good thing,
120 and some programs won't run unless you say Y here. In particular, if
121 you want to run the DOS emulator dosemu under Linux (read the
122 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
123 you'll need to say Y here.
124
125 You can find documentation about IPC with "info ipc" and also in
126 section 6.4 of the Linux Programmer's Guide, available from
127 <http://www.tldp.org/guides.html>.
128
Eric W. Biedermana5494dc2007-02-14 00:34:06 -0800129config SYSVIPC_SYSCTL
130 bool
131 depends on SYSVIPC
132 depends on SYSCTL
133 default y
134
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135config POSIX_MQUEUE
136 bool "POSIX Message Queues"
137 depends on NET && EXPERIMENTAL
138 ---help---
139 POSIX variant of message queues is a part of IPC. In POSIX message
140 queues every message has a priority which decides about succession
141 of receiving it by a process. If you want to compile and run
142 programs written e.g. for Solaris with use of its POSIX message
Robert P. J. Dayb0e37652007-05-09 07:25:13 +0200143 queues (functions mq_*) say Y here.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144
145 POSIX message queues are visible as a filesystem called 'mqueue'
146 and can be mounted somewhere if you want to do filesystem
147 operations on message queues.
148
149 If unsure, say Y.
150
151config BSD_PROCESS_ACCT
152 bool "BSD Process Accounting"
153 help
154 If you say Y here, a user level program will be able to instruct the
155 kernel (via a special system call) to write process accounting
156 information to a file: whenever a process exits, information about
157 that process will be appended to the file by the kernel. The
158 information includes things such as creation time, owning user,
159 command name, memory usage, controlling terminal etc. (the complete
160 list is in the struct acct in <file:include/linux/acct.h>). It is
161 up to the user level program to do useful things with this
162 information. This is generally a good idea, so say Y.
163
164config BSD_PROCESS_ACCT_V3
165 bool "BSD Process Accounting version 3 file format"
166 depends on BSD_PROCESS_ACCT
167 default n
168 help
169 If you say Y here, the process accounting information is written
170 in a new file format that also logs the process IDs of each
171 process and it's parent. Note that this file format is incompatible
172 with previous v0/v1/v2 file formats, so you will need updated tools
173 for processing it. A preliminary version of these tools is available
S.Çağlar Onur37a4c942008-06-18 11:45:13 +0300174 at <http://www.gnu.org/software/acct/>.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175
Shailabh Nagarc7572492006-07-14 00:24:40 -0700176config TASKSTATS
177 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
178 depends on NET
179 default n
180 help
181 Export selected statistics for tasks/processes through the
182 generic netlink interface. Unlike BSD process accounting, the
183 statistics are available during the lifetime of tasks/processes as
184 responses to commands. Like BSD accounting, they are sent to user
185 space on task exit.
186
187 Say N if unsure.
188
Shailabh Nagarca74e922006-07-14 00:24:36 -0700189config TASK_DELAY_ACCT
190 bool "Enable per-task delay accounting (EXPERIMENTAL)"
Shailabh Nagar6f449932006-07-14 00:24:41 -0700191 depends on TASKSTATS
Shailabh Nagarca74e922006-07-14 00:24:36 -0700192 help
193 Collect information on time spent by a task waiting for system
194 resources like cpu, synchronous block I/O completion and swapping
195 in pages. Such statistics can help in setting a task's priorities
196 relative to other tasks for cpu, io, rss limits etc.
197
198 Say N if unsure.
199
Alexey Dobriyan18f705f2007-02-10 01:46:44 -0800200config TASK_XACCT
201 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
202 depends on TASKSTATS
203 help
204 Collect extended task accounting data and send the data
205 to userland for processing over the taskstats interface.
206
207 Say N if unsure.
208
209config TASK_IO_ACCOUNTING
210 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
211 depends on TASK_XACCT
212 help
213 Collect information on the number of bytes of storage I/O which this
214 task has caused.
215
216 Say N if unsure.
217
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218config AUDIT
219 bool "Auditing support"
Chris Wright804a6a42005-05-11 10:52:45 +0100220 depends on NET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221 help
222 Enable auditing infrastructure that can be used with another
223 kernel subsystem, such as SELinux (which requires this for
224 logging of avc messages output). Does not do system-call
225 auditing without CONFIG_AUDITSYSCALL.
226
227config AUDITSYSCALL
228 bool "Enable system-call auditing support"
Yuichi Nakamura1322b9d2007-11-10 19:21:34 +0900229 depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64|| SUPERH)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230 default y if SECURITY_SELINUX
231 help
232 Enable low-overhead system-call auditing infrastructure that
233 can be used independently or with another kernel subsystem,
Amy Griffisf368c07d2006-04-07 16:55:56 -0400234 such as SELinux. To use audit's filesystem watch feature, please
235 ensure that INOTIFY is configured.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236
Al Viro74c3cbe2007-07-22 08:04:18 -0400237config AUDIT_TREE
238 def_bool y
239 depends on AUDITSYSCALL && INOTIFY
240
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241config IKCONFIG
Ross Birof2443ab2006-09-30 23:27:25 -0700242 tristate "Kernel .config support"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243 ---help---
244 This option enables the complete Linux kernel ".config" file
245 contents to be saved in the kernel. It provides documentation
246 of which kernel options are used in a running kernel or in an
247 on-disk kernel. This information can be extracted from the kernel
248 image file with the script scripts/extract-ikconfig and used as
249 input to rebuild the current kernel or to build another kernel.
250 It can also be extracted from a running kernel by reading
251 /proc/config.gz if enabled (below).
252
253config IKCONFIG_PROC
254 bool "Enable access to .config through /proc/config.gz"
255 depends on IKCONFIG && PROC_FS
256 ---help---
257 This option enables access to the kernel configuration file
258 through /proc/config.gz.
259
Alistair John Strachan794543a2007-05-08 00:31:15 -0700260config LOG_BUF_SHIFT
261 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
262 range 12 21
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700263 default 17
Alistair John Strachan794543a2007-05-08 00:31:15 -0700264 help
265 Select kernel log buffer size as a power of 2.
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700266 Examples:
267 17 => 128 KB
268 16 => 64 KB
269 15 => 32 KB
270 14 => 16 KB
Alistair John Strachan794543a2007-05-08 00:31:15 -0700271 13 => 8 KB
272 12 => 4 KB
273
Paul Menageddbcc7e2007-10-18 23:39:30 -0700274config CGROUPS
275 bool "Control Group support"
276 help
277 This option will let you use process cgroup subsystems
278 such as Cpusets
279
280 Say N if unsure.
281
Paul Menage006cb992007-10-18 23:39:43 -0700282config CGROUP_DEBUG
283 bool "Example debug cgroup subsystem"
284 depends on CGROUPS
Paul Menage418d7d82008-04-29 01:00:05 -0700285 default n
Paul Menage006cb992007-10-18 23:39:43 -0700286 help
287 This option enables a simple cgroup subsystem that
288 exports useful debugging information about the cgroups
289 framework
290
291 Say N if unsure
292
Serge E. Hallyn858d72e2007-10-18 23:39:45 -0700293config CGROUP_NS
294 bool "Namespace cgroup subsystem"
295 depends on CGROUPS
296 help
297 Provides a simple namespace cgroup subsystem to
298 provide hierarchical naming of sets of namespaces,
299 for instance virtual servers and checkpoint/restart
300 jobs.
301
Matt Helsleydc52ddc2008-10-18 20:27:21 -0700302config CGROUP_FREEZER
303 bool "control group freezer subsystem"
304 depends on CGROUPS
305 help
306 Provides a way to freeze and unfreeze all tasks in a
307 cgroup.
308
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700309config CGROUP_DEVICE
310 bool "Device controller for cgroups"
311 depends on CGROUPS && EXPERIMENTAL
312 help
313 Provides a cgroup implementing whitelists for devices which
314 a process in the cgroup can mknod or open.
315
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316config CPUSETS
317 bool "Cpuset support"
Paul Menage8793d852007-10-18 23:39:39 -0700318 depends on SMP && CGROUPS
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319 help
Randy Dunlapd9fd8a62005-07-27 11:45:11 -0700320 This option will let you create and manage CPUSETs which
Linus Torvalds1da177e2005-04-16 15:20:36 -0700321 allow dynamically partitioning a system into sets of CPUs and
322 Memory Nodes and assigning tasks to run only within those sets.
323 This is primarily useful on large SMP or NUMA systems.
324
325 Say N if unsure.
326
Ingo Molnara5574cf2008-05-05 23:19:50 +0200327#
328# Architectures with an unreliable sched_clock() should select this:
329#
330config HAVE_UNSTABLE_SCHED_CLOCK
331 bool
332
Peter Zijlstra052f1dc2008-02-13 15:45:40 +0100333config GROUP_SCHED
334 bool "Group CPU scheduler"
Parag Warudkaraac6abc2008-05-03 20:42:34 -0400335 depends on EXPERIMENTAL
336 default n
Srivatsa Vaddagiri29f59db2007-10-15 17:00:07 +0200337 help
Srivatsa Vaddagirifb615582007-10-15 17:00:12 +0200338 This feature lets CPU scheduler recognize task groups and control CPU
Srivatsa Vaddagiri9b5b7752007-10-15 17:00:09 +0200339 bandwidth allocation to such task groups.
Srivatsa Vaddagiri29f59db2007-10-15 17:00:07 +0200340
Peter Zijlstra052f1dc2008-02-13 15:45:40 +0100341config FAIR_GROUP_SCHED
342 bool "Group scheduling for SCHED_OTHER"
343 depends on GROUP_SCHED
Parag Warudkaraac6abc2008-05-03 20:42:34 -0400344 default GROUP_SCHED
Srivatsa Vaddagiri24e377a2007-10-15 17:00:09 +0200345
Peter Zijlstra052f1dc2008-02-13 15:45:40 +0100346config RT_GROUP_SCHED
347 bool "Group scheduling for SCHED_RR/FIFO"
348 depends on EXPERIMENTAL
349 depends on GROUP_SCHED
350 default n
Viktor Radnaib9b158f2008-04-19 19:45:01 +0200351 help
352 This feature lets you explicitly allocate real CPU bandwidth
353 to users or control groups (depending on the "Basis for grouping tasks"
354 setting below. If enabled, it will also make it impossible to
355 schedule realtime tasks for non-root users until you allocate
356 realtime bandwidth for them.
Adrian Knoth2fe401e2008-11-12 16:23:55 -0800357 See Documentation/scheduler/sched-rt-group.txt for more information.
Peter Zijlstra052f1dc2008-02-13 15:45:40 +0100358
359choice
360 depends on GROUP_SCHED
361 prompt "Basis for grouping tasks"
362 default USER_SCHED
363
364config USER_SCHED
Srivatsa Vaddagirifb615582007-10-15 17:00:12 +0200365 bool "user id"
366 help
367 This option will choose userid as the basis for grouping
368 tasks, thus providing equal CPU bandwidth to each user.
Srivatsa Vaddagiri24e377a2007-10-15 17:00:09 +0200369
Peter Zijlstra052f1dc2008-02-13 15:45:40 +0100370config CGROUP_SCHED
Srivatsa Vaddagiri68318b82007-10-18 23:41:03 -0700371 bool "Control groups"
372 depends on CGROUPS
373 help
374 This option allows you to create arbitrary task groups
375 using the "cgroup" pseudo filesystem and control
376 the cpu bandwidth allocated to each such task group.
377 Refer to Documentation/cgroups.txt for more information
378 on "cgroup" pseudo filesystem.
379
Srivatsa Vaddagiri24e377a2007-10-15 17:00:09 +0200380endchoice
381
Srivatsa Vaddagirid842de82007-12-02 20:04:49 +0100382config CGROUP_CPUACCT
383 bool "Simple CPU accounting cgroup subsystem"
384 depends on CGROUPS
385 help
386 Provides a simple Resource Controller for monitoring the
387 total CPU consumed by the tasks in a cgroup
388
Pavel Emelianove552b662008-02-07 00:13:49 -0800389config RESOURCE_COUNTERS
390 bool "Resource counters"
391 help
392 This option enables controller independent resource accounting
393 infrastructure that works with cgroups
394 depends on CGROUPS
395
Balbir Singhcf475ad2008-04-29 01:00:16 -0700396config MM_OWNER
397 bool
398
Balbir Singh00f0b822008-03-04 14:28:39 -0800399config CGROUP_MEM_RES_CTLR
400 bool "Memory Resource Controller for Control Groups"
401 depends on CGROUPS && RESOURCE_COUNTERS
Balbir Singhcf475ad2008-04-29 01:00:16 -0700402 select MM_OWNER
Balbir Singh00f0b822008-03-04 14:28:39 -0800403 help
KAMEZAWA Hiroyuki84ad6d72008-10-29 14:01:06 -0700404 Provides a memory resource controller that manages both anonymous
405 memory and page cache. (See Documentation/controllers/memory.txt)
Balbir Singh00f0b822008-03-04 14:28:39 -0800406
407 Note that setting this option increases fixed memory overhead
KAMEZAWA Hiroyuki84ad6d72008-10-29 14:01:06 -0700408 associated with each page of memory in the system. By this,
409 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
410 usage tracking struct at boot. Total amount of this is printed out
411 at boot.
Balbir Singh00f0b822008-03-04 14:28:39 -0800412
413 Only enable when you're ok with these trade offs and really
KAMEZAWA Hiroyuki84ad6d72008-10-29 14:01:06 -0700414 sure you need the memory resource controller. Even when you enable
415 this, you can set "cgroup_disable=memory" at your boot option to
416 disable memory resource controller and you can avoid overheads.
417 (and lose benefits of memory resource contoller)
Balbir Singh00f0b822008-03-04 14:28:39 -0800418
Balbir Singhcf475ad2008-04-29 01:00:16 -0700419 This config option also selects MM_OWNER config option, which
420 could in turn add some fork/exit overhead.
421
Kay Sievers88a22c92006-09-14 11:23:28 +0200422config SYSFS_DEPRECATED
Ingo Molnard47846c2008-03-04 14:54:47 +0100423 bool
424
425config SYSFS_DEPRECATED_V2
Kay Sieversfce3e802008-11-01 14:03:00 +0100426 bool "Create deprecated sysfs layout for older userspace tools"
Randy Dunlap9148fe82007-12-31 10:05:34 -0800427 depends on SYSFS
Kay Sievers88a22c92006-09-14 11:23:28 +0200428 default y
Ingo Molnard47846c2008-03-04 14:54:47 +0100429 select SYSFS_DEPRECATED
Kay Sievers88a22c92006-09-14 11:23:28 +0200430 help
Kay Sieversfce3e802008-11-01 14:03:00 +0100431 This option switches the layout of sysfs to the deprecated
432 version.
Kay Sievers88a22c92006-09-14 11:23:28 +0200433
Kay Sieversfce3e802008-11-01 14:03:00 +0100434 The current sysfs layout features a unified device tree at
435 /sys/devices/, which is able to express a hierarchy between
436 class devices. If the deprecated option is set to Y, the
437 unified device tree is split into a bus device tree at
438 /sys/devices/ and several individual class device trees at
439 /sys/class/. The class and bus devices will be connected by
440 "<subsystem>:<name>" and the "device" links. The "block"
441 class devices, will not show up in /sys/class/block/. Some
442 subsystems will suppress the creation of some devices which
443 depend on the unified device tree.
Kay Sievers88a22c92006-09-14 11:23:28 +0200444
Kay Sieversfce3e802008-11-01 14:03:00 +0100445 This option is not a pure compatibility option that can
446 be safely enabled on newer distributions. It will change the
447 layout of sysfs to the non-extensible deprecated version,
448 and disable some features, which can not be exported without
449 confusing older userspace tools. Since 2007/2008 all major
450 distributions do not enable this option, and ship no tools which
451 depend on the deprecated layout or this option.
452
453 If you are using a new kernel on an older distribution, or use
454 older userspace tools, you might need to say Y here. Do not say Y,
455 if the original kernel, that came with your distribution, has
456 this option set to N.
Kay Sievers88a22c92006-09-14 11:23:28 +0200457
Paul Menage8793d852007-10-18 23:39:39 -0700458config PROC_PID_CPUSET
459 bool "Include legacy /proc/<pid>/cpuset file"
460 depends on CPUSETS
461 default y
462
Jens Axboeb86ff982006-03-23 19:56:55 +0100463config RELAY
464 bool "Kernel->user space relay support (formerly relayfs)"
465 help
466 This option enables support for relay interface support in
467 certain file systems (such as debugfs).
468 It is designed to provide an efficient mechanism for tools and
469 facilities to relay large amounts of data from kernel space to
470 user space.
471
472 If unsure, say N.
473
Pavel Emelyanovc5289a62008-02-08 04:18:19 -0800474config NAMESPACES
475 bool "Namespaces support" if EMBEDDED
476 default !EMBEDDED
477 help
478 Provides the way to make tasks work with different objects using
479 the same id. For example same IPC id may refer to different objects
480 or same user id or pid may refer to different tasks when used in
481 different namespaces.
482
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -0800483config UTS_NS
484 bool "UTS namespace"
485 depends on NAMESPACES
486 help
487 In this namespace tasks see different info provided with the
488 uname() system call
489
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -0800490config IPC_NS
491 bool "IPC namespace"
492 depends on NAMESPACES && SYSVIPC
493 help
494 In this namespace tasks work with IPC ids which correspond to
495 different IPC objects in different namespaces
496
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -0800497config USER_NS
498 bool "User namespace (EXPERIMENTAL)"
499 depends on NAMESPACES && EXPERIMENTAL
500 help
501 This allows containers, i.e. vservers, to use user namespaces
502 to provide different user info for different servers.
503 If unsure, say N.
504
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -0800505config PID_NS
506 bool "PID Namespaces (EXPERIMENTAL)"
507 default n
508 depends on NAMESPACES && EXPERIMENTAL
509 help
Heikki Orsila12d2b8f2008-07-06 15:48:02 +0300510 Support process id namespaces. This allows having multiple
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -0800511 process with the same pid as long as they are in different
512 pid namespaces. This is a building block of containers.
513
514 Unless you want to work with an experimental feature
515 say N here.
516
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -0800517config BLK_DEV_INITRD
518 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
519 depends on BROKEN || !FRV
520 help
521 The initial RAM filesystem is a ramfs which is loaded by the
522 boot loader (loadlin or lilo) and that is mounted as root
523 before the normal boot procedure. It is typically used to
524 load modules needed to mount the "real" root file system,
525 etc. See <file:Documentation/initrd.txt> for details.
526
527 If RAM disk support (BLK_DEV_RAM) is also included, this
528 also enables initial RAM disk (initrd) support and adds
529 15 Kbytes (more on some other architectures) to the kernel size.
530
531 If unsure say Y.
532
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -0800533if BLK_DEV_INITRD
534
Sam Ravnborgdbec4862005-08-10 20:44:50 +0200535source "usr/Kconfig"
536
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -0800537endif
538
Linus Torvaldsc45b4f12005-12-14 18:52:21 -0800539config CC_OPTIMIZE_FOR_SIZE
Ingo Molnar96fffeb2008-04-28 01:39:43 +0200540 bool "Optimize for size"
Linus Torvaldsc45b4f12005-12-14 18:52:21 -0800541 default y
Linus Torvaldsc45b4f12005-12-14 18:52:21 -0800542 help
543 Enabling this option will pass "-Os" instead of "-O2" to gcc
544 resulting in a smaller kernel.
545
jkacur775a7222008-07-16 00:31:16 +0200546 If unsure, say Y.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -0800547
Randy Dunlap08470622006-09-30 23:28:13 -0700548config SYSCTL
549 bool
550
Linus Torvalds1da177e2005-04-16 15:20:36 -0700551menuconfig EMBEDDED
552 bool "Configure standard kernel features (for small systems)"
553 help
554 This option allows certain base kernel options and settings
555 to be disabled or tweaked. This is for specialized
556 environments which can tolerate a "non-standard" kernel.
557 Only use this if you really know what you are doing.
558
Chuck Ebbertae81f9e2006-09-16 12:15:53 -0700559config UID16
560 bool "Enable 16-bit UID system calls" if EMBEDDED
David S. Miller09337f52008-04-26 03:17:12 -0700561 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
Chuck Ebbertae81f9e2006-09-16 12:15:53 -0700562 default y
563 help
564 This enables the legacy 16-bit UID syscall wrappers.
565
Eric W. Biedermanb89a8172006-09-27 01:51:04 -0700566config SYSCTL_SYSCALL
Randy Dunlap08470622006-09-30 23:28:13 -0700567 bool "Sysctl syscall support" if EMBEDDED
Eric W. Biederman13bb7e32006-11-08 17:44:51 -0800568 default y
Eric W. Biedermanb89a8172006-09-27 01:51:04 -0700569 select SYSCTL
570 ---help---
Eric W. Biederman13bb7e32006-11-08 17:44:51 -0800571 sys_sysctl uses binary paths that have been found challenging
572 to properly maintain and use. The interface in /proc/sys
573 using paths with ascii names is now the primary path to this
574 information.
Eric W. Biedermanb89a8172006-09-27 01:51:04 -0700575
Eric W. Biederman13bb7e32006-11-08 17:44:51 -0800576 Almost nothing using the binary sysctl interface so if you are
577 trying to save some space it is probably safe to disable this,
578 making your kernel marginally smaller.
Eric W. Biedermanb89a8172006-09-27 01:51:04 -0700579
Eric W. Biederman13bb7e32006-11-08 17:44:51 -0800580 If unsure say Y here.
Chuck Ebbertae81f9e2006-09-16 12:15:53 -0700581
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582config KALLSYMS
Jesper Juhl979c6a12006-12-12 19:25:11 +0100583 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584 default y
585 help
586 Say Y here to let the kernel print out symbolic crash information and
587 symbolic stack backtraces. This increases the size of the kernel
588 somewhat, as all symbols have to be loaded into the kernel image.
589
590config KALLSYMS_ALL
591 bool "Include all symbols in kallsyms"
592 depends on DEBUG_KERNEL && KALLSYMS
593 help
594 Normally kallsyms only contains the symbols of functions, for nicer
595 OOPS messages. Some debuggers can use kallsyms for other
Jesper Juhlf9f97bc2005-07-20 05:43:05 +0200596 symbols too: say Y here to include all symbols, if you need them
597 and you don't care about adding 300k to the size of your kernel.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700598
599 Say N.
600
Jan Beulich9bb48242008-12-16 11:30:08 +0000601config KALLSYMS_STRIP_GENERATED
602 bool "Strip machine generated symbols from kallsyms"
603 depends on KALLSYMS_ALL
604 default y
605 help
606 Say N if you want kallsyms to retain even machine generated symbols.
607
Linus Torvalds1da177e2005-04-16 15:20:36 -0700608config KALLSYMS_EXTRA_PASS
609 bool "Do an extra kallsyms pass"
610 depends on KALLSYMS
611 help
612 If kallsyms is not working correctly, the build will fail with
613 inconsistent kallsyms data. If that occurs, log a bug report and
614 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
615 Always say N here unless you find a bug in kallsyms, which must be
616 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
617 you wait for kallsyms to be fixed.
618
Matt Mackalld59745c2005-05-01 08:59:02 -0700619
Greg Kroah-Hartman712f47c2005-11-16 11:27:07 -0800620config HOTPLUG
621 bool "Support for hot-pluggable devices" if EMBEDDED
622 default y
623 help
624 This option is provided for the case where no hotplug or uevent
625 capabilities is wanted by the kernel. You should only consider
626 disabling this option for embedded systems that do not use modules, a
627 dynamic /dev tree, or dynamic device discovery. Just say Y.
628
Matt Mackalld59745c2005-05-01 08:59:02 -0700629config PRINTK
630 default y
631 bool "Enable support for printk" if EMBEDDED
632 help
633 This option enables normal printk support. Removing it
634 eliminates most of the message strings from the kernel image
635 and makes the kernel more or less silent. As this makes it
636 very difficult to diagnose system problems, saying N here is
637 strongly discouraged.
638
Matt Mackallc8538a72005-05-01 08:59:01 -0700639config BUG
640 bool "BUG() support" if EMBEDDED
641 default y
642 help
643 Disabling this option eliminates support for BUG and WARN, reducing
644 the size of your kernel image and potentially quietly ignoring
645 numerous fatal conditions. You should only consider disabling this
646 option for embedded systems with no facilities for reporting errors.
647 Just say Y.
648
Matt Mackall708e9a72006-01-08 01:05:25 -0800649config ELF_CORE
650 default y
651 bool "Enable ELF core dumps" if EMBEDDED
652 help
653 Enable support for generating core dumps. Disabling saves about 4k.
654
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +0200655config PCSPKR_PLATFORM
656 bool "Enable PC-Speaker support" if EMBEDDED
657 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
658 default y
659 help
660 This option allows to disable the internal PC-Speaker
661 support, saving some memory.
662
Ingo Molnar32a93232008-02-06 22:39:44 +0100663config COMPAT_BRK
664 bool "Disable heap randomization"
665 default y
666 help
667 Randomizing heap placement makes heap exploits harder, but it
668 also breaks ancient binaries (including anything libc5 based).
669 This option changes the bootup default to heap randomization
670 disabled, and can be overriden runtime by setting
671 /proc/sys/kernel/randomize_va_space to 2.
672
Ingo Molnar166124f2008-02-09 23:24:09 +0100673 On non-ancient distros (post-2000 ones) N is usually a safe choice.
Ingo Molnar32a93232008-02-06 22:39:44 +0100674
Linus Torvalds1da177e2005-04-16 15:20:36 -0700675config BASE_FULL
676 default y
677 bool "Enable full-sized data structures for core" if EMBEDDED
678 help
679 Disabling this option reduces the size of miscellaneous core
680 kernel data structures. This saves memory on small machines,
681 but may reduce performance.
682
683config FUTEX
684 bool "Enable futex support" if EMBEDDED
685 default y
Ingo Molnar23f78d42006-06-27 02:54:53 -0700686 select RT_MUTEXES
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687 help
688 Disabling this option will cause the kernel to be built without
689 support for "fast userspace mutexes". The resulting kernel may not
690 run glibc-based applications correctly.
691
Davide Libenzi5dc8bf82007-05-10 22:23:11 -0700692config ANON_INODES
Adrian Bunk448e3ce2007-07-31 00:39:10 -0700693 bool
Davide Libenzi5dc8bf82007-05-10 22:23:11 -0700694
Linus Torvalds1da177e2005-04-16 15:20:36 -0700695config EPOLL
696 bool "Enable eventpoll support" if EMBEDDED
697 default y
Adrian Bunk448e3ce2007-07-31 00:39:10 -0700698 select ANON_INODES
Linus Torvalds1da177e2005-04-16 15:20:36 -0700699 help
700 Disabling this option will cause the kernel to be built without
701 support for epoll family of system calls.
702
Davide Libenzifba2afa2007-05-10 22:23:13 -0700703config SIGNALFD
704 bool "Enable signalfd() system call" if EMBEDDED
Adrian Bunk448e3ce2007-07-31 00:39:10 -0700705 select ANON_INODES
Davide Libenzifba2afa2007-05-10 22:23:13 -0700706 default y
707 help
708 Enable the signalfd() system call that allows to receive signals
709 on a file descriptor.
710
711 If unsure, say Y.
712
Davide Libenzib215e282007-05-10 22:23:16 -0700713config TIMERFD
714 bool "Enable timerfd() system call" if EMBEDDED
Adrian Bunk448e3ce2007-07-31 00:39:10 -0700715 select ANON_INODES
Davide Libenzib215e282007-05-10 22:23:16 -0700716 default y
717 help
718 Enable the timerfd() system call that allows to receive timer
719 events on a file descriptor.
720
721 If unsure, say Y.
722
Davide Libenzie1ad7462007-05-10 22:23:19 -0700723config EVENTFD
724 bool "Enable eventfd() system call" if EMBEDDED
Adrian Bunk448e3ce2007-07-31 00:39:10 -0700725 select ANON_INODES
Davide Libenzie1ad7462007-05-10 22:23:19 -0700726 default y
727 help
728 Enable the eventfd() system call that allows to receive both
729 kernel notification (ie. KAIO) or userspace notifications.
730
731 If unsure, say Y.
732
Linus Torvalds1da177e2005-04-16 15:20:36 -0700733config SHMEM
734 bool "Use full shmem filesystem" if EMBEDDED
735 default y
736 depends on MMU
737 help
738 The shmem is an internal filesystem used to manage shared memory.
739 It is backed by swap and manages resource limits. It is also exported
740 to userspace as tmpfs if TMPFS is enabled. Disabling this
741 option replaces shmem and tmpfs with the much simpler ramfs code,
742 which may be appropriate on small systems without swap.
743
Thomas Petazzoniebf3f092008-10-15 22:05:12 -0700744config AIO
745 bool "Enable AIO support" if EMBEDDED
746 default y
747 help
748 This option enables POSIX asynchronous I/O which may by used
749 by some high performance threaded applications. Disabling
750 this option saves about 7k.
751
Christoph Lameterf8891e52006-06-30 01:55:45 -0700752config VM_EVENT_COUNTERS
753 default y
754 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
755 help
Paul Jackson2aea4fb2006-12-22 01:06:10 -0800756 VM event counters are needed for event counts to be shown.
757 This option allows the disabling of the VM event counters
758 on EMBEDDED systems. /proc/vmstat will only show page counts
759 if VM event counters are disabled.
Christoph Lameterf8891e52006-06-30 01:55:45 -0700760
Thomas Petazzoni3d137312008-08-19 10:28:24 +0200761config PCI_QUIRKS
762 default y
Geert Uytterhoeven61cfc7e2008-10-22 08:53:25 +0200763 bool "Enable PCI quirk workarounds" if EMBEDDED
764 depends on PCI
Thomas Petazzoni3d137312008-08-19 10:28:24 +0200765 help
766 This enables workarounds for various PCI chipset
767 bugs/quirks. Disable this only if your target machine is
768 unaffected by PCI quirks.
769
Christoph Lameter41ecc552007-05-09 02:32:44 -0700770config SLUB_DEBUG
771 default y
772 bool "Enable SLUB debugging support" if EMBEDDED
Christoph Lameterf6acb632008-04-29 16:16:06 -0700773 depends on SLUB && SYSFS
Christoph Lameter41ecc552007-05-09 02:32:44 -0700774 help
775 SLUB has extensive debug support features. Disabling these can
776 result in significant savings in code size. This also disables
777 SLUB sysfs support. /sys/slab will not exist and there will be
778 no support for cache validation etc.
779
Christoph Lameter81819f02007-05-06 14:49:36 -0700780choice
781 prompt "Choose SLAB allocator"
Christoph Lametera0acd822007-07-17 04:03:32 -0700782 default SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -0700783 help
784 This option allows to select a slab allocator.
785
786config SLAB
787 bool "SLAB"
788 help
789 The regular slab allocator that is established and known to work
Christoph Lameter34013882007-05-09 02:32:47 -0700790 well in all environments. It organizes cache hot objects in
Simon Arlott02f56212008-11-05 22:18:19 +0000791 per cpu and per node queues.
Christoph Lameter81819f02007-05-06 14:49:36 -0700792
793config SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -0700794 bool "SLUB (Unqueued Allocator)"
795 help
796 SLUB is a slab allocator that minimizes cache line usage
797 instead of managing queues of cached objects (SLAB approach).
798 Per cpu caching is realized using slabs of objects instead
799 of queues of objects. SLUB can use memory efficiently
Simon Arlott02f56212008-11-05 22:18:19 +0000800 and has enhanced diagnostics. SLUB is the default choice for
801 a slab allocator.
Christoph Lameter81819f02007-05-06 14:49:36 -0700802
803config SLOB
Paul Mundt84a01c22007-07-15 23:38:24 -0700804 depends on EMBEDDED
Christoph Lameter81819f02007-05-06 14:49:36 -0700805 bool "SLOB (Simple Allocator)"
806 help
Matt Mackall37291452008-02-04 22:29:38 -0800807 SLOB replaces the stock allocator with a drastically simpler
808 allocator. SLOB is generally more space efficient but
809 does not perform as well on large systems.
Christoph Lameter81819f02007-05-06 14:49:36 -0700810
811endchoice
812
Mathieu Desnoyers125e5642008-02-02 15:10:36 -0500813config PROFILING
814 bool "Profiling support (EXPERIMENTAL)"
815 help
816 Say Y here to enable the extended profiling support mechanisms used
817 by profilers such as OProfile.
818
Ingo Molnar5f87f112008-07-23 14:15:22 +0200819#
820# Place an empty function call at each tracepoint site. Can be
821# dynamically changed for a probe function.
822#
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400823config TRACEPOINTS
Ingo Molnar5f87f112008-07-23 14:15:22 +0200824 bool
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400825
Mathieu Desnoyers125e5642008-02-02 15:10:36 -0500826config MARKERS
827 bool "Activate markers"
Mathieu Desnoyersc1df1bd2008-11-14 17:47:39 -0500828 depends on TRACEPOINTS
Mathieu Desnoyers125e5642008-02-02 15:10:36 -0500829 help
830 Place an empty function call at each marker site. Can be
831 dynamically changed for a probe function.
832
Mathieu Desnoyersfb32e032008-02-02 15:10:33 -0500833source "arch/Kconfig"
834
Linus Torvalds1da177e2005-04-16 15:20:36 -0700835endmenu # General setup
836
Dmitry Baryshkovee7e5512008-06-29 14:18:46 +0400837config HAVE_GENERIC_DMA_COHERENT
838 bool
839 default n
840
Linus Torvalds158a9622008-01-02 13:04:48 -0800841config SLABINFO
842 bool
843 depends on PROC_FS
Christoph Lameter0f389ec2008-04-14 18:53:02 +0300844 depends on SLAB || SLUB_DEBUG
Linus Torvalds158a9622008-01-02 13:04:48 -0800845 default y
846
Chuck Ebbertae81f9e2006-09-16 12:15:53 -0700847config RT_MUTEXES
848 boolean
849 select PLIST
850
Linus Torvalds1da177e2005-04-16 15:20:36 -0700851config TINY_SHMEM
852 default !SHMEM
853 bool
854
855config BASE_SMALL
856 int
857 default 0 if BASE_FULL
858 default 1 if !BASE_FULL
859
Jan Engelhardt66da5732007-07-15 23:39:29 -0700860menuconfig MODULES
Linus Torvalds1da177e2005-04-16 15:20:36 -0700861 bool "Enable loadable module support"
862 help
863 Kernel modules are small pieces of compiled code which can
864 be inserted in the running kernel, rather than being
865 permanently built into the kernel. You use the "modprobe"
866 tool to add (and sometimes remove) them. If you say Y here,
867 many parts of the kernel can be built as modules (by
868 answering M instead of Y where indicated): this is most
869 useful for infrequently used options which are not required
870 for booting. For more information, see the man pages for
871 modprobe, lsmod, modinfo, insmod and rmmod.
872
873 If you say Y here, you will need to run "make
874 modules_install" to put the modules under /lib/modules/
875 where modprobe can find them (you may need to be root to do
876 this).
877
878 If unsure, say Y.
879
Robert P. J. Day0b0de142008-08-04 13:31:32 -0400880if MODULES
881
Linus Torvalds826e4502008-05-04 17:04:16 -0700882config MODULE_FORCE_LOAD
883 bool "Forced module loading"
Linus Torvalds826e4502008-05-04 17:04:16 -0700884 default n
885 help
Rusty Russell91e37a72008-05-09 16:25:28 +1000886 Allow loading of modules without version information (ie. modprobe
887 --force). Forced module loading sets the 'F' (forced) taint flag and
888 is usually a really bad idea.
Linus Torvalds826e4502008-05-04 17:04:16 -0700889
Linus Torvalds1da177e2005-04-16 15:20:36 -0700890config MODULE_UNLOAD
891 bool "Module unloading"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700892 help
893 Without this option you will not be able to unload any
894 modules (note that some modules may not be unloadable
Denys Vlasenkof7f5b672008-07-22 19:24:26 -0500895 anyway), which makes your kernel smaller, faster
896 and simpler. If unsure, say Y.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700897
898config MODULE_FORCE_UNLOAD
899 bool "Forced module unloading"
900 depends on MODULE_UNLOAD && EXPERIMENTAL
901 help
902 This option allows you to force a module to unload, even if the
903 kernel believes it is unsafe: the kernel will remove the module
904 without waiting for anyone to stop using it (using the -f option to
905 rmmod). This is mainly for kernel developers and desperate users.
906 If unsure, say N.
907
Linus Torvalds1da177e2005-04-16 15:20:36 -0700908config MODVERSIONS
Sam Ravnborg0d541642005-12-26 23:04:02 +0100909 bool "Module versioning support"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700910 help
911 Usually, you have to use modules compiled with your kernel.
912 Saying Y here makes it sometimes possible to use modules
913 compiled for different kernels, by adding enough information
914 to the modules to (hopefully) spot any changes which would
915 make them incompatible with the kernel you are running. If
916 unsure, say N.
917
918config MODULE_SRCVERSION_ALL
919 bool "Source checksum for all modules"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700920 help
921 Modules which contain a MODULE_VERSION get an extra "srcversion"
922 field inserted into their modinfo section, which contains a
923 sum of the source files which made it. This helps maintainers
924 see exactly which source was used to build a module (since
925 others sometimes change the module source without updating
926 the version). With this option, such a "srcversion" field
927 will be created for all modules. If unsure, say N.
928
Robert P. J. Day0b0de142008-08-04 13:31:32 -0400929endif # MODULES
930
Rusty Russell98a79d62008-12-13 21:19:41 +1030931config INIT_ALL_POSSIBLE
932 bool
933 help
934 Back when each arch used to define their own cpu_online_map and
935 cpu_possible_map, some of them chose to initialize cpu_possible_map
936 with all 1s, and others with all 0s. When they were centralised,
937 it was better to provide this option than to break all the archs
938 and have several arch maintainers persuing me down dark alleys.
939
Linus Torvalds1da177e2005-04-16 15:20:36 -0700940config STOP_MACHINE
941 bool
942 default y
943 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
944 help
945 Need stop_machine() primitive.
Jens Axboe3a65dfe2005-11-04 08:43:35 +0100946
Jens Axboe3a65dfe2005-11-04 08:43:35 +0100947source "block/Kconfig"
Avi Kivitye98c3202007-10-16 23:27:31 -0700948
949config PREEMPT_NOTIFIERS
950 bool
Paul E. McKenneye260be62008-01-25 21:08:24 +0100951
Ingo Molnar12d79ba2008-12-25 09:31:28 +0100952choice
953 prompt "RCU Implementation"
954 default CLASSIC_RCU
955
Paul E. McKenneye260be62008-01-25 21:08:24 +0100956config CLASSIC_RCU
Ingo Molnar12d79ba2008-12-25 09:31:28 +0100957 bool "Classic RCU"
Paul E. McKenneye260be62008-01-25 21:08:24 +0100958 help
959 This option selects the classic RCU implementation that is
960 designed for best read-side performance on non-realtime
Ingo Molnar12d79ba2008-12-25 09:31:28 +0100961 systems.
962
963 Select this option if you are unsure.
964
965config TREE_RCU
966 bool "Tree-based hierarchical RCU"
967 help
968 This option selects the RCU implementation that is
969 designed for very large SMP system with hundreds or
970 thousands of CPUs.
971
972config PREEMPT_RCU
973 bool "Preemptible RCU"
974 depends on PREEMPT
975 help
976 This option reduces the latency of the kernel by making certain
977 RCU sections preemptible. Normally RCU code is non-preemptible, if
978 this option is selected then read-only RCU sections become
979 preemptible. This helps latency, but may expose bugs due to
980 now-naive assumptions about each RCU read-side critical section
981 remaining on a given CPU through its execution.
982
983endchoice
984
985config RCU_TRACE
986 bool "Enable tracing for RCU"
987 depends on TREE_RCU || PREEMPT_RCU
988 help
989 This option provides tracing in RCU which presents stats
990 in debugfs for debugging RCU implementation.
991
992 Say Y here if you want to enable RCU tracing
993 Say N if you are unsure.
994
995config RCU_FANOUT
996 int "Tree-based hierarchical RCU fanout value"
997 range 2 64 if 64BIT
998 range 2 32 if !64BIT
999 depends on TREE_RCU
1000 default 64 if 64BIT
1001 default 32 if !64BIT
1002 help
1003 This option controls the fanout of hierarchical implementations
1004 of RCU, allowing RCU to work efficiently on machines with
1005 large numbers of CPUs. This value must be at least the cube
1006 root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
1007 systems and up to 262,144 for 64-bit systems.
1008
1009 Select a specific number if testing RCU itself.
1010 Take the default if unsure.
1011
1012config RCU_FANOUT_EXACT
1013 bool "Disable tree-based hierarchical RCU auto-balancing"
1014 depends on TREE_RCU
1015 default n
1016 help
1017 This option forces use of the exact RCU_FANOUT value specified,
1018 regardless of imbalances in the hierarchy. This is useful for
1019 testing RCU itself, and might one day be useful on systems with
1020 strong NUMA behavior.
1021
1022 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
1023
1024 Say N if unsure.
1025
Paul E. McKenney64db4cf2008-12-18 21:55:32 +01001026config TREE_RCU_TRACE
1027 def_bool RCU_TRACE && TREE_RCU
1028 select DEBUG_FS
Paul E. McKenneye260be62008-01-25 21:08:24 +01001029 help
Paul E. McKenney64db4cf2008-12-18 21:55:32 +01001030 This option provides tracing for the TREE_RCU implementation,
1031 permitting Makefile to trivially select kernel/rcutree_trace.c.
1032
1033config PREEMPT_RCU_TRACE
1034 def_bool RCU_TRACE && PREEMPT_RCU
1035 select DEBUG_FS
1036 help
1037 This option provides tracing for the PREEMPT_RCU implementation,
1038 permitting Makefile to trivially select kernel/rcupreempt_trace.c.