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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' Giarrussob2670eac2006-10-19 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42 drivers that have been replaced by something else, and/or are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
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800104config HAVE_KERNEL_GZIP
105 bool
106
107config HAVE_KERNEL_BZIP2
108 bool
109
110config HAVE_KERNEL_LZMA
111 bool
112
Alain Knaff30d65db2009-01-04 22:46:17 +0100113choice
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800114 prompt "Kernel compression mode"
115 default KERNEL_GZIP
116 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA
117 help
Alain Knaff30d65db2009-01-04 22:46:17 +0100118 The linux kernel is a kind of self-extracting executable.
119 Several compression algorithms are available, which differ
120 in efficiency, compression and decompression speed.
121 Compression speed is only relevant when building a kernel.
122 Decompression speed is relevant at each boot.
123
124 If you have any problems with bzip2 or lzma compressed
125 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
126 version of this functionality (bzip2 only), for 2.4, was
127 supplied by Christian Ludwig)
128
129 High compression options are mostly useful for users, who
130 are low on disk space (embedded systems), but for whom ram
131 size matters less.
132
133 If in doubt, select 'gzip'
134
135config KERNEL_GZIP
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800136 bool "Gzip"
137 depends on HAVE_KERNEL_GZIP
138 help
139 The old and tried gzip compression. Its compression ratio is
140 the poorest among the 3 choices; however its speed (both
141 compression and decompression) is the fastest.
Alain Knaff30d65db2009-01-04 22:46:17 +0100142
143config KERNEL_BZIP2
144 bool "Bzip2"
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800145 depends on HAVE_KERNEL_BZIP2
Alain Knaff30d65db2009-01-04 22:46:17 +0100146 help
147 Its compression ratio and speed is intermediate.
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800148 Decompression speed is slowest among the three. The kernel
149 size is about 10% smaller with bzip2, in comparison to gzip.
150 Bzip2 uses a large amount of memory. For modern kernels you
151 will need at least 8MB RAM or more for booting.
Alain Knaff30d65db2009-01-04 22:46:17 +0100152
153config KERNEL_LZMA
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800154 bool "LZMA"
155 depends on HAVE_KERNEL_LZMA
156 help
157 The most recent compression algorithm.
158 Its ratio is best, decompression speed is between the other
159 two. Compression is slowest. The kernel size is about 33%
160 smaller with LZMA in comparison to gzip.
Alain Knaff30d65db2009-01-04 22:46:17 +0100161
162endchoice
163
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164config SWAP
165 bool "Support for paging of anonymous memory (swap)"
David Howells93614012006-09-30 20:45:40 +0200166 depends on MMU && BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167 default y
168 help
169 This option allows you to choose whether you want to have support
Jesper Juhl92c35042006-01-15 02:40:08 +0100170 for so called swap devices or swap files in your kernel that are
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171 used to provide more virtual memory than the actual RAM present
172 in your computer. If unsure say Y.
173
174config SYSVIPC
175 bool "System V IPC"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176 ---help---
177 Inter Process Communication is a suite of library functions and
178 system calls which let processes (running programs) synchronize and
179 exchange information. It is generally considered to be a good thing,
180 and some programs won't run unless you say Y here. In particular, if
181 you want to run the DOS emulator dosemu under Linux (read the
182 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
183 you'll need to say Y here.
184
185 You can find documentation about IPC with "info ipc" and also in
186 section 6.4 of the Linux Programmer's Guide, available from
187 <http://www.tldp.org/guides.html>.
188
Eric W. Biedermana5494dc2007-02-14 00:34:06 -0800189config SYSVIPC_SYSCTL
190 bool
191 depends on SYSVIPC
192 depends on SYSCTL
193 default y
194
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195config POSIX_MQUEUE
196 bool "POSIX Message Queues"
197 depends on NET && EXPERIMENTAL
198 ---help---
199 POSIX variant of message queues is a part of IPC. In POSIX message
200 queues every message has a priority which decides about succession
201 of receiving it by a process. If you want to compile and run
202 programs written e.g. for Solaris with use of its POSIX message
Robert P. J. Dayb0e37652007-05-09 07:25:13 +0200203 queues (functions mq_*) say Y here.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204
205 POSIX message queues are visible as a filesystem called 'mqueue'
206 and can be mounted somewhere if you want to do filesystem
207 operations on message queues.
208
209 If unsure, say Y.
210
211config BSD_PROCESS_ACCT
212 bool "BSD Process Accounting"
213 help
214 If you say Y here, a user level program will be able to instruct the
215 kernel (via a special system call) to write process accounting
216 information to a file: whenever a process exits, information about
217 that process will be appended to the file by the kernel. The
218 information includes things such as creation time, owning user,
219 command name, memory usage, controlling terminal etc. (the complete
220 list is in the struct acct in <file:include/linux/acct.h>). It is
221 up to the user level program to do useful things with this
222 information. This is generally a good idea, so say Y.
223
224config BSD_PROCESS_ACCT_V3
225 bool "BSD Process Accounting version 3 file format"
226 depends on BSD_PROCESS_ACCT
227 default n
228 help
229 If you say Y here, the process accounting information is written
230 in a new file format that also logs the process IDs of each
231 process and it's parent. Note that this file format is incompatible
232 with previous v0/v1/v2 file formats, so you will need updated tools
233 for processing it. A preliminary version of these tools is available
S.Çağlar Onur37a4c942008-06-18 11:45:13 +0300234 at <http://www.gnu.org/software/acct/>.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235
Shailabh Nagarc7572492006-07-14 00:24:40 -0700236config TASKSTATS
237 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
238 depends on NET
239 default n
240 help
241 Export selected statistics for tasks/processes through the
242 generic netlink interface. Unlike BSD process accounting, the
243 statistics are available during the lifetime of tasks/processes as
244 responses to commands. Like BSD accounting, they are sent to user
245 space on task exit.
246
247 Say N if unsure.
248
Shailabh Nagarca74e922006-07-14 00:24:36 -0700249config TASK_DELAY_ACCT
250 bool "Enable per-task delay accounting (EXPERIMENTAL)"
Shailabh Nagar6f449932006-07-14 00:24:41 -0700251 depends on TASKSTATS
Shailabh Nagarca74e922006-07-14 00:24:36 -0700252 help
253 Collect information on time spent by a task waiting for system
254 resources like cpu, synchronous block I/O completion and swapping
255 in pages. Such statistics can help in setting a task's priorities
256 relative to other tasks for cpu, io, rss limits etc.
257
258 Say N if unsure.
259
Alexey Dobriyan18f705f2007-02-10 01:46:44 -0800260config TASK_XACCT
261 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
262 depends on TASKSTATS
263 help
264 Collect extended task accounting data and send the data
265 to userland for processing over the taskstats interface.
266
267 Say N if unsure.
268
269config TASK_IO_ACCOUNTING
270 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
271 depends on TASK_XACCT
272 help
273 Collect information on the number of bytes of storage I/O which this
274 task has caused.
275
276 Say N if unsure.
277
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278config AUDIT
279 bool "Auditing support"
Chris Wright804a6a492005-05-11 10:52:45 +0100280 depends on NET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281 help
282 Enable auditing infrastructure that can be used with another
283 kernel subsystem, such as SELinux (which requires this for
284 logging of avc messages output). Does not do system-call
285 auditing without CONFIG_AUDITSYSCALL.
286
287config AUDITSYSCALL
288 bool "Enable system-call auditing support"
Yuichi Nakamura1322b9d2007-11-10 19:21:34 +0900289 depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64|| SUPERH)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290 default y if SECURITY_SELINUX
291 help
292 Enable low-overhead system-call auditing infrastructure that
293 can be used independently or with another kernel subsystem,
Amy Griffisf368c07d2006-04-07 16:55:56 -0400294 such as SELinux. To use audit's filesystem watch feature, please
295 ensure that INOTIFY is configured.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296
Al Viro74c3cbe2007-07-22 08:04:18 -0400297config AUDIT_TREE
298 def_bool y
299 depends on AUDITSYSCALL && INOTIFY
300
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301config IKCONFIG
Ross Birof2443ab2006-09-30 23:27:25 -0700302 tristate "Kernel .config support"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303 ---help---
304 This option enables the complete Linux kernel ".config" file
305 contents to be saved in the kernel. It provides documentation
306 of which kernel options are used in a running kernel or in an
307 on-disk kernel. This information can be extracted from the kernel
308 image file with the script scripts/extract-ikconfig and used as
309 input to rebuild the current kernel or to build another kernel.
310 It can also be extracted from a running kernel by reading
311 /proc/config.gz if enabled (below).
312
313config IKCONFIG_PROC
314 bool "Enable access to .config through /proc/config.gz"
315 depends on IKCONFIG && PROC_FS
316 ---help---
317 This option enables access to the kernel configuration file
318 through /proc/config.gz.
319
Alistair John Strachan794543a2007-05-08 00:31:15 -0700320config LOG_BUF_SHIFT
321 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
322 range 12 21
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700323 default 17
Alistair John Strachan794543a2007-05-08 00:31:15 -0700324 help
325 Select kernel log buffer size as a power of 2.
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700326 Examples:
327 17 => 128 KB
328 16 => 64 KB
329 15 => 32 KB
330 14 => 16 KB
Alistair John Strachan794543a2007-05-08 00:31:15 -0700331 13 => 8 KB
332 12 => 4 KB
333
Paul Menageddbcc7e2007-10-18 23:39:30 -0700334config CGROUPS
335 bool "Control Group support"
336 help
337 This option will let you use process cgroup subsystems
338 such as Cpusets
339
340 Say N if unsure.
341
Paul Menage006cb992007-10-18 23:39:43 -0700342config CGROUP_DEBUG
343 bool "Example debug cgroup subsystem"
344 depends on CGROUPS
Paul Menage418d7d82008-04-29 01:00:05 -0700345 default n
Paul Menage006cb992007-10-18 23:39:43 -0700346 help
347 This option enables a simple cgroup subsystem that
348 exports useful debugging information about the cgroups
349 framework
350
351 Say N if unsure
352
Serge E. Hallyn858d72e2007-10-18 23:39:45 -0700353config CGROUP_NS
354 bool "Namespace cgroup subsystem"
355 depends on CGROUPS
356 help
357 Provides a simple namespace cgroup subsystem to
358 provide hierarchical naming of sets of namespaces,
359 for instance virtual servers and checkpoint/restart
360 jobs.
361
Matt Helsleydc52ddc2008-10-18 20:27:21 -0700362config CGROUP_FREEZER
363 bool "control group freezer subsystem"
364 depends on CGROUPS
365 help
366 Provides a way to freeze and unfreeze all tasks in a
367 cgroup.
368
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700369config CGROUP_DEVICE
370 bool "Device controller for cgroups"
371 depends on CGROUPS && EXPERIMENTAL
372 help
373 Provides a cgroup implementing whitelists for devices which
374 a process in the cgroup can mknod or open.
375
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376config CPUSETS
377 bool "Cpuset support"
Paul Menage8793d852007-10-18 23:39:39 -0700378 depends on SMP && CGROUPS
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 help
Randy Dunlapd9fd8a62005-07-27 11:45:11 -0700380 This option will let you create and manage CPUSETs which
Linus Torvalds1da177e2005-04-16 15:20:36 -0700381 allow dynamically partitioning a system into sets of CPUs and
382 Memory Nodes and assigning tasks to run only within those sets.
383 This is primarily useful on large SMP or NUMA systems.
384
385 Say N if unsure.
386
Ingo Molnara5574cf2008-05-05 23:19:50 +0200387#
388# Architectures with an unreliable sched_clock() should select this:
389#
390config HAVE_UNSTABLE_SCHED_CLOCK
391 bool
392
Peter Zijlstra052f1dc2008-02-13 15:45:40 +0100393config GROUP_SCHED
394 bool "Group CPU scheduler"
Parag Warudkaraac6abc2008-05-03 20:42:34 -0400395 depends on EXPERIMENTAL
396 default n
Srivatsa Vaddagiri29f59db2007-10-15 17:00:07 +0200397 help
Srivatsa Vaddagirifb615582007-10-15 17:00:12 +0200398 This feature lets CPU scheduler recognize task groups and control CPU
Srivatsa Vaddagiri9b5b7752007-10-15 17:00:09 +0200399 bandwidth allocation to such task groups.
Srivatsa Vaddagiri29f59db2007-10-15 17:00:07 +0200400
Peter Zijlstra052f1dc2008-02-13 15:45:40 +0100401config FAIR_GROUP_SCHED
402 bool "Group scheduling for SCHED_OTHER"
403 depends on GROUP_SCHED
Parag Warudkaraac6abc2008-05-03 20:42:34 -0400404 default GROUP_SCHED
Srivatsa Vaddagiri24e377a2007-10-15 17:00:09 +0200405
Peter Zijlstra052f1dc2008-02-13 15:45:40 +0100406config RT_GROUP_SCHED
407 bool "Group scheduling for SCHED_RR/FIFO"
408 depends on EXPERIMENTAL
409 depends on GROUP_SCHED
410 default n
Viktor Radnaib9b158f2008-04-19 19:45:01 +0200411 help
412 This feature lets you explicitly allocate real CPU bandwidth
413 to users or control groups (depending on the "Basis for grouping tasks"
414 setting below. If enabled, it will also make it impossible to
415 schedule realtime tasks for non-root users until you allocate
416 realtime bandwidth for them.
Adrian Knoth2fe401e2008-11-12 16:23:55 -0800417 See Documentation/scheduler/sched-rt-group.txt for more information.
Peter Zijlstra052f1dc2008-02-13 15:45:40 +0100418
419choice
420 depends on GROUP_SCHED
421 prompt "Basis for grouping tasks"
422 default USER_SCHED
423
424config USER_SCHED
Srivatsa Vaddagirifb615582007-10-15 17:00:12 +0200425 bool "user id"
426 help
427 This option will choose userid as the basis for grouping
428 tasks, thus providing equal CPU bandwidth to each user.
Srivatsa Vaddagiri24e377a2007-10-15 17:00:09 +0200429
Peter Zijlstra052f1dc2008-02-13 15:45:40 +0100430config CGROUP_SCHED
Srivatsa Vaddagiri68318b82007-10-18 23:41:03 -0700431 bool "Control groups"
432 depends on CGROUPS
433 help
434 This option allows you to create arbitrary task groups
435 using the "cgroup" pseudo filesystem and control
436 the cpu bandwidth allocated to each such task group.
437 Refer to Documentation/cgroups.txt for more information
438 on "cgroup" pseudo filesystem.
439
Srivatsa Vaddagiri24e377a2007-10-15 17:00:09 +0200440endchoice
441
Srivatsa Vaddagirid842de82007-12-02 20:04:49 +0100442config CGROUP_CPUACCT
443 bool "Simple CPU accounting cgroup subsystem"
444 depends on CGROUPS
445 help
446 Provides a simple Resource Controller for monitoring the
447 total CPU consumed by the tasks in a cgroup
448
Pavel Emelianove552b662008-02-07 00:13:49 -0800449config RESOURCE_COUNTERS
450 bool "Resource counters"
451 help
452 This option enables controller independent resource accounting
453 infrastructure that works with cgroups
454 depends on CGROUPS
455
Balbir Singhcf475ad2008-04-29 01:00:16 -0700456config MM_OWNER
457 bool
458
Balbir Singh00f0b822008-03-04 14:28:39 -0800459config CGROUP_MEM_RES_CTLR
460 bool "Memory Resource Controller for Control Groups"
461 depends on CGROUPS && RESOURCE_COUNTERS
Balbir Singhcf475ad2008-04-29 01:00:16 -0700462 select MM_OWNER
Balbir Singh00f0b822008-03-04 14:28:39 -0800463 help
KAMEZAWA Hiroyuki84ad6d72008-10-29 14:01:06 -0700464 Provides a memory resource controller that manages both anonymous
465 memory and page cache. (See Documentation/controllers/memory.txt)
Balbir Singh00f0b822008-03-04 14:28:39 -0800466
467 Note that setting this option increases fixed memory overhead
KAMEZAWA Hiroyuki84ad6d72008-10-29 14:01:06 -0700468 associated with each page of memory in the system. By this,
469 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
470 usage tracking struct at boot. Total amount of this is printed out
471 at boot.
Balbir Singh00f0b822008-03-04 14:28:39 -0800472
473 Only enable when you're ok with these trade offs and really
KAMEZAWA Hiroyuki84ad6d72008-10-29 14:01:06 -0700474 sure you need the memory resource controller. Even when you enable
475 this, you can set "cgroup_disable=memory" at your boot option to
476 disable memory resource controller and you can avoid overheads.
477 (and lose benefits of memory resource contoller)
Balbir Singh00f0b822008-03-04 14:28:39 -0800478
Balbir Singhcf475ad2008-04-29 01:00:16 -0700479 This config option also selects MM_OWNER config option, which
480 could in turn add some fork/exit overhead.
481
Kay Sievers88a22c92006-09-14 11:23:28 +0200482config SYSFS_DEPRECATED
Ingo Molnard47846c2008-03-04 14:54:47 +0100483 bool
484
485config SYSFS_DEPRECATED_V2
Kay Sievers88a22c92006-09-14 11:23:28 +0200486 bool "Create deprecated sysfs files"
Randy Dunlap9148fe82007-12-31 10:05:34 -0800487 depends on SYSFS
Kay Sievers88a22c92006-09-14 11:23:28 +0200488 default y
Ingo Molnard47846c2008-03-04 14:54:47 +0100489 select SYSFS_DEPRECATED
Kay Sievers88a22c92006-09-14 11:23:28 +0200490 help
491 This option creates deprecated symlinks such as the
492 "device"-link, the <subsystem>:<name>-link, and the
493 "bus"-link. It may also add deprecated key in the
494 uevent environment.
495 None of these features or values should be used today, as
496 they export driver core implementation details to userspace
497 or export properties which can't be kept stable across kernel
498 releases.
499
500 If enabled, this option will also move any device structures
David Sterba3dde6ad2007-05-09 07:12:20 +0200501 that belong to a class, back into the /sys/class hierarchy, in
Greg Kroah-Hartman024440d2008-03-03 14:47:13 -0800502 order to support older versions of udev and some userspace
503 programs.
Kay Sievers88a22c92006-09-14 11:23:28 +0200504
Greg Kroah-Hartman024440d2008-03-03 14:47:13 -0800505 If you are using a distro with the most recent userspace
506 packages, it should be safe to say N here.
Kay Sievers88a22c92006-09-14 11:23:28 +0200507
Paul Menage8793d852007-10-18 23:39:39 -0700508config PROC_PID_CPUSET
509 bool "Include legacy /proc/<pid>/cpuset file"
510 depends on CPUSETS
511 default y
512
Jens Axboeb86ff9812006-03-23 19:56:55 +0100513config RELAY
514 bool "Kernel->user space relay support (formerly relayfs)"
515 help
516 This option enables support for relay interface support in
517 certain file systems (such as debugfs).
518 It is designed to provide an efficient mechanism for tools and
519 facilities to relay large amounts of data from kernel space to
520 user space.
521
522 If unsure, say N.
523
Pavel Emelyanovc5289a62008-02-08 04:18:19 -0800524config NAMESPACES
525 bool "Namespaces support" if EMBEDDED
526 default !EMBEDDED
527 help
528 Provides the way to make tasks work with different objects using
529 the same id. For example same IPC id may refer to different objects
530 or same user id or pid may refer to different tasks when used in
531 different namespaces.
532
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -0800533config UTS_NS
534 bool "UTS namespace"
535 depends on NAMESPACES
536 help
537 In this namespace tasks see different info provided with the
538 uname() system call
539
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -0800540config IPC_NS
541 bool "IPC namespace"
542 depends on NAMESPACES && SYSVIPC
543 help
544 In this namespace tasks work with IPC ids which correspond to
545 different IPC objects in different namespaces
546
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -0800547config USER_NS
548 bool "User namespace (EXPERIMENTAL)"
549 depends on NAMESPACES && EXPERIMENTAL
550 help
551 This allows containers, i.e. vservers, to use user namespaces
552 to provide different user info for different servers.
553 If unsure, say N.
554
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -0800555config PID_NS
556 bool "PID Namespaces (EXPERIMENTAL)"
557 default n
558 depends on NAMESPACES && EXPERIMENTAL
559 help
Heikki Orsila12d2b8f2008-07-06 15:48:02 +0300560 Support process id namespaces. This allows having multiple
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -0800561 process with the same pid as long as they are in different
562 pid namespaces. This is a building block of containers.
563
564 Unless you want to work with an experimental feature
565 say N here.
566
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -0800567config BLK_DEV_INITRD
568 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
569 depends on BROKEN || !FRV
570 help
571 The initial RAM filesystem is a ramfs which is loaded by the
572 boot loader (loadlin or lilo) and that is mounted as root
573 before the normal boot procedure. It is typically used to
574 load modules needed to mount the "real" root file system,
575 etc. See <file:Documentation/initrd.txt> for details.
576
577 If RAM disk support (BLK_DEV_RAM) is also included, this
578 also enables initial RAM disk (initrd) support and adds
579 15 Kbytes (more on some other architectures) to the kernel size.
580
581 If unsure say Y.
582
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -0800583if BLK_DEV_INITRD
584
Sam Ravnborgdbec4862005-08-10 20:44:50 +0200585source "usr/Kconfig"
586
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -0800587endif
588
Linus Torvaldsc45b4f12005-12-14 18:52:21 -0800589config CC_OPTIMIZE_FOR_SIZE
Ingo Molnar96fffeb2008-04-28 01:39:43 +0200590 bool "Optimize for size"
Linus Torvaldsc45b4f12005-12-14 18:52:21 -0800591 default y
Linus Torvaldsc45b4f12005-12-14 18:52:21 -0800592 help
593 Enabling this option will pass "-Os" instead of "-O2" to gcc
594 resulting in a smaller kernel.
595
jkacur775a7222008-07-16 00:31:16 +0200596 If unsure, say Y.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -0800597
Randy Dunlap08470622006-09-30 23:28:13 -0700598config SYSCTL
599 bool
600
Linus Torvalds1da177e2005-04-16 15:20:36 -0700601menuconfig EMBEDDED
602 bool "Configure standard kernel features (for small systems)"
603 help
604 This option allows certain base kernel options and settings
605 to be disabled or tweaked. This is for specialized
606 environments which can tolerate a "non-standard" kernel.
607 Only use this if you really know what you are doing.
608
Chuck Ebbertae81f9e2006-09-16 12:15:53 -0700609config UID16
610 bool "Enable 16-bit UID system calls" if EMBEDDED
David S. Miller09337f52008-04-26 03:17:12 -0700611 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 -0700612 default y
613 help
614 This enables the legacy 16-bit UID syscall wrappers.
615
Eric W. Biedermanb89a8172006-09-27 01:51:04 -0700616config SYSCTL_SYSCALL
Randy Dunlap08470622006-09-30 23:28:13 -0700617 bool "Sysctl syscall support" if EMBEDDED
Eric W. Biederman13bb7e32006-11-08 17:44:51 -0800618 default y
Eric W. Biedermanb89a8172006-09-27 01:51:04 -0700619 select SYSCTL
620 ---help---
Eric W. Biederman13bb7e32006-11-08 17:44:51 -0800621 sys_sysctl uses binary paths that have been found challenging
622 to properly maintain and use. The interface in /proc/sys
623 using paths with ascii names is now the primary path to this
624 information.
Eric W. Biedermanb89a8172006-09-27 01:51:04 -0700625
Eric W. Biederman13bb7e32006-11-08 17:44:51 -0800626 Almost nothing using the binary sysctl interface so if you are
627 trying to save some space it is probably safe to disable this,
628 making your kernel marginally smaller.
Eric W. Biedermanb89a8172006-09-27 01:51:04 -0700629
Eric W. Biederman13bb7e32006-11-08 17:44:51 -0800630 If unsure say Y here.
Chuck Ebbertae81f9e2006-09-16 12:15:53 -0700631
Linus Torvalds1da177e2005-04-16 15:20:36 -0700632config KALLSYMS
Jesper Juhl979c6a12006-12-12 19:25:11 +0100633 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
Linus Torvalds1da177e2005-04-16 15:20:36 -0700634 default y
635 help
636 Say Y here to let the kernel print out symbolic crash information and
637 symbolic stack backtraces. This increases the size of the kernel
638 somewhat, as all symbols have to be loaded into the kernel image.
639
640config KALLSYMS_ALL
641 bool "Include all symbols in kallsyms"
642 depends on DEBUG_KERNEL && KALLSYMS
643 help
644 Normally kallsyms only contains the symbols of functions, for nicer
645 OOPS messages. Some debuggers can use kallsyms for other
Jesper Juhlf9f97bc2005-07-20 05:43:05 +0200646 symbols too: say Y here to include all symbols, if you need them
647 and you don't care about adding 300k to the size of your kernel.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700648
649 Say N.
650
Jan Beulich9bb48242008-12-16 11:30:08 +0000651config KALLSYMS_STRIP_GENERATED
652 bool "Strip machine generated symbols from kallsyms"
653 depends on KALLSYMS_ALL
654 default y
655 help
656 Say N if you want kallsyms to retain even machine generated symbols.
657
Linus Torvalds1da177e2005-04-16 15:20:36 -0700658config KALLSYMS_EXTRA_PASS
659 bool "Do an extra kallsyms pass"
660 depends on KALLSYMS
661 help
662 If kallsyms is not working correctly, the build will fail with
663 inconsistent kallsyms data. If that occurs, log a bug report and
664 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
665 Always say N here unless you find a bug in kallsyms, which must be
666 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
667 you wait for kallsyms to be fixed.
668
Matt Mackalld59745c2005-05-01 08:59:02 -0700669
Greg Kroah-Hartman712f47c2005-11-16 11:27:07 -0800670config HOTPLUG
671 bool "Support for hot-pluggable devices" if EMBEDDED
672 default y
673 help
674 This option is provided for the case where no hotplug or uevent
675 capabilities is wanted by the kernel. You should only consider
676 disabling this option for embedded systems that do not use modules, a
677 dynamic /dev tree, or dynamic device discovery. Just say Y.
678
Matt Mackalld59745c2005-05-01 08:59:02 -0700679config PRINTK
680 default y
681 bool "Enable support for printk" if EMBEDDED
682 help
683 This option enables normal printk support. Removing it
684 eliminates most of the message strings from the kernel image
685 and makes the kernel more or less silent. As this makes it
686 very difficult to diagnose system problems, saying N here is
687 strongly discouraged.
688
Matt Mackallc8538a72005-05-01 08:59:01 -0700689config BUG
690 bool "BUG() support" if EMBEDDED
691 default y
692 help
693 Disabling this option eliminates support for BUG and WARN, reducing
694 the size of your kernel image and potentially quietly ignoring
695 numerous fatal conditions. You should only consider disabling this
696 option for embedded systems with no facilities for reporting errors.
697 Just say Y.
698
Matt Mackall708e9a72006-01-08 01:05:25 -0800699config ELF_CORE
700 default y
701 bool "Enable ELF core dumps" if EMBEDDED
702 help
703 Enable support for generating core dumps. Disabling saves about 4k.
704
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +0200705config PCSPKR_PLATFORM
706 bool "Enable PC-Speaker support" if EMBEDDED
707 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
708 default y
709 help
710 This option allows to disable the internal PC-Speaker
711 support, saving some memory.
712
Ingo Molnar32a93232008-02-06 22:39:44 +0100713config COMPAT_BRK
714 bool "Disable heap randomization"
715 default y
716 help
717 Randomizing heap placement makes heap exploits harder, but it
718 also breaks ancient binaries (including anything libc5 based).
719 This option changes the bootup default to heap randomization
720 disabled, and can be overriden runtime by setting
721 /proc/sys/kernel/randomize_va_space to 2.
722
Ingo Molnar166124f2008-02-09 23:24:09 +0100723 On non-ancient distros (post-2000 ones) N is usually a safe choice.
Ingo Molnar32a93232008-02-06 22:39:44 +0100724
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725config BASE_FULL
726 default y
727 bool "Enable full-sized data structures for core" if EMBEDDED
728 help
729 Disabling this option reduces the size of miscellaneous core
730 kernel data structures. This saves memory on small machines,
731 but may reduce performance.
732
733config FUTEX
734 bool "Enable futex support" if EMBEDDED
735 default y
Ingo Molnar23f78d4a2006-06-27 02:54:53 -0700736 select RT_MUTEXES
Linus Torvalds1da177e2005-04-16 15:20:36 -0700737 help
738 Disabling this option will cause the kernel to be built without
739 support for "fast userspace mutexes". The resulting kernel may not
740 run glibc-based applications correctly.
741
Davide Libenzi5dc8bf82007-05-10 22:23:11 -0700742config ANON_INODES
Adrian Bunk448e3ce2007-07-31 00:39:10 -0700743 bool
Davide Libenzi5dc8bf82007-05-10 22:23:11 -0700744
Linus Torvalds1da177e2005-04-16 15:20:36 -0700745config EPOLL
746 bool "Enable eventpoll support" if EMBEDDED
747 default y
Adrian Bunk448e3ce2007-07-31 00:39:10 -0700748 select ANON_INODES
Linus Torvalds1da177e2005-04-16 15:20:36 -0700749 help
750 Disabling this option will cause the kernel to be built without
751 support for epoll family of system calls.
752
Davide Libenzifba2afa2007-05-10 22:23:13 -0700753config SIGNALFD
754 bool "Enable signalfd() system call" if EMBEDDED
Adrian Bunk448e3ce2007-07-31 00:39:10 -0700755 select ANON_INODES
Davide Libenzifba2afa2007-05-10 22:23:13 -0700756 default y
757 help
758 Enable the signalfd() system call that allows to receive signals
759 on a file descriptor.
760
761 If unsure, say Y.
762
Davide Libenzib215e282007-05-10 22:23:16 -0700763config TIMERFD
764 bool "Enable timerfd() system call" if EMBEDDED
Adrian Bunk448e3ce2007-07-31 00:39:10 -0700765 select ANON_INODES
Davide Libenzib215e282007-05-10 22:23:16 -0700766 default y
767 help
768 Enable the timerfd() system call that allows to receive timer
769 events on a file descriptor.
770
771 If unsure, say Y.
772
Davide Libenzie1ad7462007-05-10 22:23:19 -0700773config EVENTFD
774 bool "Enable eventfd() system call" if EMBEDDED
Adrian Bunk448e3ce2007-07-31 00:39:10 -0700775 select ANON_INODES
Davide Libenzie1ad7462007-05-10 22:23:19 -0700776 default y
777 help
778 Enable the eventfd() system call that allows to receive both
779 kernel notification (ie. KAIO) or userspace notifications.
780
781 If unsure, say Y.
782
Linus Torvalds1da177e2005-04-16 15:20:36 -0700783config SHMEM
784 bool "Use full shmem filesystem" if EMBEDDED
785 default y
786 depends on MMU
787 help
788 The shmem is an internal filesystem used to manage shared memory.
789 It is backed by swap and manages resource limits. It is also exported
790 to userspace as tmpfs if TMPFS is enabled. Disabling this
791 option replaces shmem and tmpfs with the much simpler ramfs code,
792 which may be appropriate on small systems without swap.
793
Thomas Petazzoniebf3f092008-10-15 22:05:12 -0700794config AIO
795 bool "Enable AIO support" if EMBEDDED
796 default y
797 help
798 This option enables POSIX asynchronous I/O which may by used
799 by some high performance threaded applications. Disabling
800 this option saves about 7k.
801
Christoph Lameterf8891e52006-06-30 01:55:45 -0700802config VM_EVENT_COUNTERS
803 default y
804 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
805 help
Paul Jackson2aea4fb2006-12-22 01:06:10 -0800806 VM event counters are needed for event counts to be shown.
807 This option allows the disabling of the VM event counters
808 on EMBEDDED systems. /proc/vmstat will only show page counts
809 if VM event counters are disabled.
Christoph Lameterf8891e52006-06-30 01:55:45 -0700810
Thomas Petazzoni3d137312008-08-19 10:28:24 +0200811config PCI_QUIRKS
812 default y
Geert Uytterhoeven61cfc7e2008-10-22 08:53:25 +0200813 bool "Enable PCI quirk workarounds" if EMBEDDED
814 depends on PCI
Thomas Petazzoni3d137312008-08-19 10:28:24 +0200815 help
816 This enables workarounds for various PCI chipset
817 bugs/quirks. Disable this only if your target machine is
818 unaffected by PCI quirks.
819
Christoph Lameter41ecc552007-05-09 02:32:44 -0700820config SLUB_DEBUG
821 default y
822 bool "Enable SLUB debugging support" if EMBEDDED
Christoph Lameterf6acb632008-04-29 16:16:06 -0700823 depends on SLUB && SYSFS
Christoph Lameter41ecc552007-05-09 02:32:44 -0700824 help
825 SLUB has extensive debug support features. Disabling these can
826 result in significant savings in code size. This also disables
827 SLUB sysfs support. /sys/slab will not exist and there will be
828 no support for cache validation etc.
829
Christoph Lameter81819f02007-05-06 14:49:36 -0700830choice
831 prompt "Choose SLAB allocator"
Christoph Lametera0acd822007-07-17 04:03:32 -0700832 default SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -0700833 help
834 This option allows to select a slab allocator.
835
836config SLAB
837 bool "SLAB"
838 help
839 The regular slab allocator that is established and known to work
Christoph Lameter34013882007-05-09 02:32:47 -0700840 well in all environments. It organizes cache hot objects in
Simon Arlott02f56212008-11-05 22:18:19 +0000841 per cpu and per node queues.
Christoph Lameter81819f02007-05-06 14:49:36 -0700842
843config SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -0700844 bool "SLUB (Unqueued Allocator)"
845 help
846 SLUB is a slab allocator that minimizes cache line usage
847 instead of managing queues of cached objects (SLAB approach).
848 Per cpu caching is realized using slabs of objects instead
849 of queues of objects. SLUB can use memory efficiently
Simon Arlott02f56212008-11-05 22:18:19 +0000850 and has enhanced diagnostics. SLUB is the default choice for
851 a slab allocator.
Christoph Lameter81819f02007-05-06 14:49:36 -0700852
853config SLOB
Paul Mundt84a01c22007-07-15 23:38:24 -0700854 depends on EMBEDDED
Christoph Lameter81819f02007-05-06 14:49:36 -0700855 bool "SLOB (Simple Allocator)"
856 help
Matt Mackall37291452008-02-04 22:29:38 -0800857 SLOB replaces the stock allocator with a drastically simpler
858 allocator. SLOB is generally more space efficient but
859 does not perform as well on large systems.
Christoph Lameter81819f02007-05-06 14:49:36 -0700860
861endchoice
862
Mathieu Desnoyers125e5642008-02-02 15:10:36 -0500863config PROFILING
864 bool "Profiling support (EXPERIMENTAL)"
865 help
866 Say Y here to enable the extended profiling support mechanisms used
867 by profilers such as OProfile.
868
Ingo Molnar5f87f112008-07-23 14:15:22 +0200869#
870# Place an empty function call at each tracepoint site. Can be
871# dynamically changed for a probe function.
872#
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400873config TRACEPOINTS
Ingo Molnar5f87f112008-07-23 14:15:22 +0200874 bool
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400875
Mathieu Desnoyers125e5642008-02-02 15:10:36 -0500876config MARKERS
877 bool "Activate markers"
Mathieu Desnoyersc1df1bd2008-11-14 17:47:39 -0500878 depends on TRACEPOINTS
Mathieu Desnoyers125e5642008-02-02 15:10:36 -0500879 help
880 Place an empty function call at each marker site. Can be
881 dynamically changed for a probe function.
882
Mathieu Desnoyersfb32e032008-02-02 15:10:33 -0500883source "arch/Kconfig"
884
Linus Torvalds1da177e2005-04-16 15:20:36 -0700885endmenu # General setup
886
Dmitry Baryshkovee7e5512008-06-29 14:18:46 +0400887config HAVE_GENERIC_DMA_COHERENT
888 bool
889 default n
890
Linus Torvalds158a9622008-01-02 13:04:48 -0800891config SLABINFO
892 bool
893 depends on PROC_FS
Christoph Lameter0f389ec2008-04-14 18:53:02 +0300894 depends on SLAB || SLUB_DEBUG
Linus Torvalds158a9622008-01-02 13:04:48 -0800895 default y
896
Chuck Ebbertae81f9e2006-09-16 12:15:53 -0700897config RT_MUTEXES
898 boolean
899 select PLIST
900
Linus Torvalds1da177e2005-04-16 15:20:36 -0700901config TINY_SHMEM
902 default !SHMEM
903 bool
904
905config BASE_SMALL
906 int
907 default 0 if BASE_FULL
908 default 1 if !BASE_FULL
909
Jan Engelhardt66da5732007-07-15 23:39:29 -0700910menuconfig MODULES
Linus Torvalds1da177e2005-04-16 15:20:36 -0700911 bool "Enable loadable module support"
912 help
913 Kernel modules are small pieces of compiled code which can
914 be inserted in the running kernel, rather than being
915 permanently built into the kernel. You use the "modprobe"
916 tool to add (and sometimes remove) them. If you say Y here,
917 many parts of the kernel can be built as modules (by
918 answering M instead of Y where indicated): this is most
919 useful for infrequently used options which are not required
920 for booting. For more information, see the man pages for
921 modprobe, lsmod, modinfo, insmod and rmmod.
922
923 If you say Y here, you will need to run "make
924 modules_install" to put the modules under /lib/modules/
925 where modprobe can find them (you may need to be root to do
926 this).
927
928 If unsure, say Y.
929
Robert P. J. Day0b0de142008-08-04 13:31:32 -0400930if MODULES
931
Linus Torvalds826e4502008-05-04 17:04:16 -0700932config MODULE_FORCE_LOAD
933 bool "Forced module loading"
Linus Torvalds826e4502008-05-04 17:04:16 -0700934 default n
935 help
Rusty Russell91e37a72008-05-09 16:25:28 +1000936 Allow loading of modules without version information (ie. modprobe
937 --force). Forced module loading sets the 'F' (forced) taint flag and
938 is usually a really bad idea.
Linus Torvalds826e4502008-05-04 17:04:16 -0700939
Linus Torvalds1da177e2005-04-16 15:20:36 -0700940config MODULE_UNLOAD
941 bool "Module unloading"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700942 help
943 Without this option you will not be able to unload any
944 modules (note that some modules may not be unloadable
Denys Vlasenkof7f5b672008-07-22 19:24:26 -0500945 anyway), which makes your kernel smaller, faster
946 and simpler. If unsure, say Y.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700947
948config MODULE_FORCE_UNLOAD
949 bool "Forced module unloading"
950 depends on MODULE_UNLOAD && EXPERIMENTAL
951 help
952 This option allows you to force a module to unload, even if the
953 kernel believes it is unsafe: the kernel will remove the module
954 without waiting for anyone to stop using it (using the -f option to
955 rmmod). This is mainly for kernel developers and desperate users.
956 If unsure, say N.
957
Linus Torvalds1da177e2005-04-16 15:20:36 -0700958config MODVERSIONS
Sam Ravnborg0d541642005-12-26 23:04:02 +0100959 bool "Module versioning support"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700960 help
961 Usually, you have to use modules compiled with your kernel.
962 Saying Y here makes it sometimes possible to use modules
963 compiled for different kernels, by adding enough information
964 to the modules to (hopefully) spot any changes which would
965 make them incompatible with the kernel you are running. If
966 unsure, say N.
967
968config MODULE_SRCVERSION_ALL
969 bool "Source checksum for all modules"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700970 help
971 Modules which contain a MODULE_VERSION get an extra "srcversion"
972 field inserted into their modinfo section, which contains a
973 sum of the source files which made it. This helps maintainers
974 see exactly which source was used to build a module (since
975 others sometimes change the module source without updating
976 the version). With this option, such a "srcversion" field
977 will be created for all modules. If unsure, say N.
978
979config KMOD
Johannes Bergbaabaae2008-07-08 19:00:16 +0200980 def_bool y
Linus Torvalds1da177e2005-04-16 15:20:36 -0700981 help
Johannes Bergbaabaae2008-07-08 19:00:16 +0200982 This is being removed soon. These days, CONFIG_MODULES
983 implies CONFIG_KMOD, so use that instead.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700984
Robert P. J. Day0b0de142008-08-04 13:31:32 -0400985endif # MODULES
986
Rusty Russell98a79d62008-12-13 21:19:41 +1030987config INIT_ALL_POSSIBLE
988 bool
989 help
990 Back when each arch used to define their own cpu_online_map and
991 cpu_possible_map, some of them chose to initialize cpu_possible_map
992 with all 1s, and others with all 0s. When they were centralised,
993 it was better to provide this option than to break all the archs
994 and have several arch maintainers persuing me down dark alleys.
995
Linus Torvalds1da177e2005-04-16 15:20:36 -0700996config STOP_MACHINE
997 bool
998 default y
999 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1000 help
1001 Need stop_machine() primitive.
Jens Axboe3a65dfe2005-11-04 08:43:35 +01001002
Jens Axboe3a65dfe2005-11-04 08:43:35 +01001003source "block/Kconfig"
Avi Kivitye98c3202007-10-16 23:27:31 -07001004
1005config PREEMPT_NOTIFIERS
1006 bool
Paul E. McKenneye260be62008-01-25 21:08:24 +01001007
Ingo Molnar12d79ba2008-12-25 09:31:28 +01001008choice
1009 prompt "RCU Implementation"
1010 default CLASSIC_RCU
1011
Paul E. McKenneye260be62008-01-25 21:08:24 +01001012config CLASSIC_RCU
Ingo Molnar12d79ba2008-12-25 09:31:28 +01001013 bool "Classic RCU"
Paul E. McKenneye260be62008-01-25 21:08:24 +01001014 help
1015 This option selects the classic RCU implementation that is
1016 designed for best read-side performance on non-realtime
Ingo Molnar12d79ba2008-12-25 09:31:28 +01001017 systems.
1018
1019 Select this option if you are unsure.
1020
1021config TREE_RCU
1022 bool "Tree-based hierarchical RCU"
1023 help
1024 This option selects the RCU implementation that is
1025 designed for very large SMP system with hundreds or
1026 thousands of CPUs.
1027
1028config PREEMPT_RCU
1029 bool "Preemptible RCU"
1030 depends on PREEMPT
1031 help
1032 This option reduces the latency of the kernel by making certain
1033 RCU sections preemptible. Normally RCU code is non-preemptible, if
1034 this option is selected then read-only RCU sections become
1035 preemptible. This helps latency, but may expose bugs due to
1036 now-naive assumptions about each RCU read-side critical section
1037 remaining on a given CPU through its execution.
1038
1039endchoice
1040
1041config RCU_TRACE
1042 bool "Enable tracing for RCU"
1043 depends on TREE_RCU || PREEMPT_RCU
1044 help
1045 This option provides tracing in RCU which presents stats
1046 in debugfs for debugging RCU implementation.
1047
1048 Say Y here if you want to enable RCU tracing
1049 Say N if you are unsure.
1050
1051config RCU_FANOUT
1052 int "Tree-based hierarchical RCU fanout value"
1053 range 2 64 if 64BIT
1054 range 2 32 if !64BIT
1055 depends on TREE_RCU
1056 default 64 if 64BIT
1057 default 32 if !64BIT
1058 help
1059 This option controls the fanout of hierarchical implementations
1060 of RCU, allowing RCU to work efficiently on machines with
1061 large numbers of CPUs. This value must be at least the cube
1062 root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
1063 systems and up to 262,144 for 64-bit systems.
1064
1065 Select a specific number if testing RCU itself.
1066 Take the default if unsure.
1067
1068config RCU_FANOUT_EXACT
1069 bool "Disable tree-based hierarchical RCU auto-balancing"
1070 depends on TREE_RCU
1071 default n
1072 help
1073 This option forces use of the exact RCU_FANOUT value specified,
1074 regardless of imbalances in the hierarchy. This is useful for
1075 testing RCU itself, and might one day be useful on systems with
1076 strong NUMA behavior.
1077
1078 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
1079
1080 Say N if unsure.
1081
Paul E. McKenney64db4cf2008-12-18 21:55:32 +01001082config TREE_RCU_TRACE
1083 def_bool RCU_TRACE && TREE_RCU
1084 select DEBUG_FS
Paul E. McKenneye260be62008-01-25 21:08:24 +01001085 help
Paul E. McKenney64db4cf2008-12-18 21:55:32 +01001086 This option provides tracing for the TREE_RCU implementation,
1087 permitting Makefile to trivially select kernel/rcutree_trace.c.
1088
1089config PREEMPT_RCU_TRACE
1090 def_bool RCU_TRACE && PREEMPT_RCU
1091 select DEBUG_FS
1092 help
1093 This option provides tracing for the PREEMPT_RCU implementation,
1094 permitting Makefile to trivially select kernel/rcupreempt_trace.c.