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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
Peter Oberparleiterb99b87f72009-06-17 16:28:03 -070019config CONSTRUCTORS
20 bool
21 depends on !UML
22 default y
23
Peter Zijlstrae360adb2010-10-14 14:01:34 +080024config HAVE_IRQ_WORK
25 bool
26
27config IRQ_WORK
28 bool
29 depends on HAVE_IRQ_WORK
30
Al Boldiff0cfc62007-07-31 00:39:23 -070031menu "General setup"
Linus Torvalds1da177e2005-04-16 15:20:36 -070032
33config EXPERIMENTAL
34 bool "Prompt for development and/or incomplete code/drivers"
35 ---help---
36 Some of the various things that Linux supports (such as network
37 drivers, file systems, network protocols, etc.) can be in a state
38 of development where the functionality, stability, or the level of
39 testing is not yet high enough for general use. This is usually
40 known as the "alpha-test" phase among developers. If a feature is
41 currently in alpha-test, then the developers usually discourage
42 uninformed widespread use of this feature by the general public to
43 avoid "Why doesn't this work?" type mail messages. However, active
44 testing and use of these systems is welcomed. Just be aware that it
45 may not meet the normal level of reliability or it may fail to work
46 in some special cases. Detailed bug reports from people familiar
47 with the kernel internals are usually welcomed by the developers
48 (before submitting bug reports, please read the documents
49 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
50 <file:Documentation/BUG-HUNTING>, and
51 <file:Documentation/oops-tracing.txt> in the kernel source).
52
53 This option will also make obsoleted drivers available. These are
54 drivers that have been replaced by something else, and/or are
55 scheduled to be removed in a future kernel release.
56
57 Unless you intend to help test and develop a feature or driver that
58 falls into this category, or you have a situation that requires
59 using these features, you should probably say N here, which will
60 cause the configurator to present you with fewer choices. If
61 you say Y here, you will be offered the choice of using features or
62 drivers that are currently considered to be in the alpha-test phase.
63
Linus Torvalds1da177e2005-04-16 15:20:36 -070064config BROKEN
65 bool
Linus Torvalds1da177e2005-04-16 15:20:36 -070066
67config BROKEN_ON_SMP
68 bool
69 depends on BROKEN || !SMP
70 default y
71
Linus Torvalds1da177e2005-04-16 15:20:36 -070072config INIT_ENV_ARG_LIMIT
73 int
Adrian Bunkdd673bc2006-06-30 01:55:51 -070074 default 32 if !UML
75 default 128 if UML
Linus Torvalds1da177e2005-04-16 15:20:36 -070076 help
Randy Dunlap34ad92c22005-10-30 15:01:46 -080077 Maximum of each of the number of arguments and environment
78 variables passed to init from the kernel command line.
Linus Torvalds1da177e2005-04-16 15:20:36 -070079
Linus Torvalds1da177e2005-04-16 15:20:36 -070080
Roland McGrath84336462009-12-21 16:24:06 -080081config CROSS_COMPILE
82 string "Cross-compiler tool prefix"
83 help
84 Same as running 'make CROSS_COMPILE=prefix-' but stored for
85 default make runs in this kernel build directory. You don't
86 need to set this unless you want the configured kernel build
87 directory to select the cross-compiler automatically.
88
Linus Torvalds1da177e2005-04-16 15:20:36 -070089config LOCALVERSION
90 string "Local version - append to kernel release"
91 help
92 Append an extra string to the end of your kernel version.
93 This will show up when you type uname, for example.
94 The string you set here will be appended after the contents of
95 any files with a filename matching localversion* in your
96 object and source tree, in that order. Your total string can
97 be a maximum of 64 characters.
98
Ryan Andersonaaebf432005-07-31 04:57:49 -040099config LOCALVERSION_AUTO
100 bool "Automatically append version information to the version string"
101 default y
102 help
103 This will try to automatically determine if the current tree is a
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200104 release tree by looking for git tags that belong to the current
105 top of tree revision.
Ryan Andersonaaebf432005-07-31 04:57:49 -0400106
107 A string of the format -gxxxxxxxx will be added to the localversion
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200108 if a git-based tree is found. The string generated by this will be
Ryan Andersonaaebf432005-07-31 04:57:49 -0400109 appended after any matching localversion* files, and after the value
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200110 set in CONFIG_LOCALVERSION.
Ryan Andersonaaebf432005-07-31 04:57:49 -0400111
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200112 (The actual string used here is the first eight characters produced
113 by running the command:
114
115 $ git rev-parse --verify HEAD
116
117 which is done within the script "scripts/setlocalversion".)
Ryan Andersonaaebf432005-07-31 04:57:49 -0400118
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800119config HAVE_KERNEL_GZIP
120 bool
121
122config HAVE_KERNEL_BZIP2
123 bool
124
125config HAVE_KERNEL_LZMA
126 bool
127
Lasse Collin3ebe1242011-01-12 17:01:23 -0800128config HAVE_KERNEL_XZ
129 bool
130
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800131config HAVE_KERNEL_LZO
132 bool
133
Alain Knaff30d65db2009-01-04 22:46:17 +0100134choice
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800135 prompt "Kernel compression mode"
136 default KERNEL_GZIP
Lasse Collin3ebe1242011-01-12 17:01:23 -0800137 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800138 help
Alain Knaff30d65db2009-01-04 22:46:17 +0100139 The linux kernel is a kind of self-extracting executable.
140 Several compression algorithms are available, which differ
141 in efficiency, compression and decompression speed.
142 Compression speed is only relevant when building a kernel.
143 Decompression speed is relevant at each boot.
144
145 If you have any problems with bzip2 or lzma compressed
146 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
147 version of this functionality (bzip2 only), for 2.4, was
148 supplied by Christian Ludwig)
149
150 High compression options are mostly useful for users, who
151 are low on disk space (embedded systems), but for whom ram
152 size matters less.
153
154 If in doubt, select 'gzip'
155
156config KERNEL_GZIP
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800157 bool "Gzip"
158 depends on HAVE_KERNEL_GZIP
159 help
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800160 The old and tried gzip compression. It provides a good balance
161 between compression ratio and decompression speed.
Alain Knaff30d65db2009-01-04 22:46:17 +0100162
163config KERNEL_BZIP2
164 bool "Bzip2"
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800165 depends on HAVE_KERNEL_BZIP2
Alain Knaff30d65db2009-01-04 22:46:17 +0100166 help
167 Its compression ratio and speed is intermediate.
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800168 Decompression speed is slowest among the three. The kernel
169 size is about 10% smaller with bzip2, in comparison to gzip.
170 Bzip2 uses a large amount of memory. For modern kernels you
171 will need at least 8MB RAM or more for booting.
Alain Knaff30d65db2009-01-04 22:46:17 +0100172
173config KERNEL_LZMA
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800174 bool "LZMA"
175 depends on HAVE_KERNEL_LZMA
176 help
177 The most recent compression algorithm.
178 Its ratio is best, decompression speed is between the other
179 two. Compression is slowest. The kernel size is about 33%
180 smaller with LZMA in comparison to gzip.
Alain Knaff30d65db2009-01-04 22:46:17 +0100181
Lasse Collin3ebe1242011-01-12 17:01:23 -0800182config KERNEL_XZ
183 bool "XZ"
184 depends on HAVE_KERNEL_XZ
185 help
186 XZ uses the LZMA2 algorithm and instruction set specific
187 BCJ filters which can improve compression ratio of executable
188 code. The size of the kernel is about 30% smaller with XZ in
189 comparison to gzip. On architectures for which there is a BCJ
190 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
191 will create a few percent smaller kernel than plain LZMA.
192
193 The speed is about the same as with LZMA: The decompression
194 speed of XZ is better than that of bzip2 but worse than gzip
195 and LZO. Compression is slow.
196
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800197config KERNEL_LZO
198 bool "LZO"
199 depends on HAVE_KERNEL_LZO
200 help
201 Its compression ratio is the poorest among the 4. The kernel
Stephan Sperber681b3042010-07-14 11:23:08 +0200202 size is about 10% bigger than gzip; however its speed
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800203 (both compression and decompression) is the fastest.
204
Alain Knaff30d65db2009-01-04 22:46:17 +0100205endchoice
206
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207config SWAP
208 bool "Support for paging of anonymous memory (swap)"
David Howells93614012006-09-30 20:45:40 +0200209 depends on MMU && BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210 default y
211 help
212 This option allows you to choose whether you want to have support
Jesper Juhl92c35042006-01-15 02:40:08 +0100213 for so called swap devices or swap files in your kernel that are
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214 used to provide more virtual memory than the actual RAM present
215 in your computer. If unsure say Y.
216
217config SYSVIPC
218 bool "System V IPC"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219 ---help---
220 Inter Process Communication is a suite of library functions and
221 system calls which let processes (running programs) synchronize and
222 exchange information. It is generally considered to be a good thing,
223 and some programs won't run unless you say Y here. In particular, if
224 you want to run the DOS emulator dosemu under Linux (read the
225 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
226 you'll need to say Y here.
227
228 You can find documentation about IPC with "info ipc" and also in
229 section 6.4 of the Linux Programmer's Guide, available from
230 <http://www.tldp.org/guides.html>.
231
Eric W. Biedermana5494dc2007-02-14 00:34:06 -0800232config SYSVIPC_SYSCTL
233 bool
234 depends on SYSVIPC
235 depends on SYSCTL
236 default y
237
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238config POSIX_MQUEUE
239 bool "POSIX Message Queues"
240 depends on NET && EXPERIMENTAL
241 ---help---
242 POSIX variant of message queues is a part of IPC. In POSIX message
243 queues every message has a priority which decides about succession
244 of receiving it by a process. If you want to compile and run
245 programs written e.g. for Solaris with use of its POSIX message
Robert P. J. Dayb0e37652007-05-09 07:25:13 +0200246 queues (functions mq_*) say Y here.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247
248 POSIX message queues are visible as a filesystem called 'mqueue'
249 and can be mounted somewhere if you want to do filesystem
250 operations on message queues.
251
252 If unsure, say Y.
253
Serge E. Hallynbdc8e5f2009-04-06 19:01:11 -0700254config POSIX_MQUEUE_SYSCTL
255 bool
256 depends on POSIX_MQUEUE
257 depends on SYSCTL
258 default y
259
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260config BSD_PROCESS_ACCT
261 bool "BSD Process Accounting"
262 help
263 If you say Y here, a user level program will be able to instruct the
264 kernel (via a special system call) to write process accounting
265 information to a file: whenever a process exits, information about
266 that process will be appended to the file by the kernel. The
267 information includes things such as creation time, owning user,
268 command name, memory usage, controlling terminal etc. (the complete
269 list is in the struct acct in <file:include/linux/acct.h>). It is
270 up to the user level program to do useful things with this
271 information. This is generally a good idea, so say Y.
272
273config BSD_PROCESS_ACCT_V3
274 bool "BSD Process Accounting version 3 file format"
275 depends on BSD_PROCESS_ACCT
276 default n
277 help
278 If you say Y here, the process accounting information is written
279 in a new file format that also logs the process IDs of each
280 process and it's parent. Note that this file format is incompatible
281 with previous v0/v1/v2 file formats, so you will need updated tools
282 for processing it. A preliminary version of these tools is available
S.Çağlar Onur37a4c942008-06-18 11:45:13 +0300283 at <http://www.gnu.org/software/acct/>.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284
Aneesh Kumar K.V990d6c22011-01-29 18:43:26 +0530285config FHANDLE
286 bool "open by fhandle syscalls"
287 select EXPORTFS
288 help
289 If you say Y here, a user level program will be able to map
290 file names to handle and then later use the handle for
291 different file system operations. This is useful in implementing
292 userspace file servers, which now track files using handles instead
293 of names. The handle would remain the same even if file names
294 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
295 syscalls.
296
Shailabh Nagarc7572492006-07-14 00:24:40 -0700297config TASKSTATS
298 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
299 depends on NET
300 default n
301 help
302 Export selected statistics for tasks/processes through the
303 generic netlink interface. Unlike BSD process accounting, the
304 statistics are available during the lifetime of tasks/processes as
305 responses to commands. Like BSD accounting, they are sent to user
306 space on task exit.
307
308 Say N if unsure.
309
Shailabh Nagarca74e922006-07-14 00:24:36 -0700310config TASK_DELAY_ACCT
311 bool "Enable per-task delay accounting (EXPERIMENTAL)"
Shailabh Nagar6f449932006-07-14 00:24:41 -0700312 depends on TASKSTATS
Shailabh Nagarca74e922006-07-14 00:24:36 -0700313 help
314 Collect information on time spent by a task waiting for system
315 resources like cpu, synchronous block I/O completion and swapping
316 in pages. Such statistics can help in setting a task's priorities
317 relative to other tasks for cpu, io, rss limits etc.
318
319 Say N if unsure.
320
Alexey Dobriyan18f705f2007-02-10 01:46:44 -0800321config TASK_XACCT
322 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
323 depends on TASKSTATS
324 help
325 Collect extended task accounting data and send the data
326 to userland for processing over the taskstats interface.
327
328 Say N if unsure.
329
330config TASK_IO_ACCOUNTING
331 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
332 depends on TASK_XACCT
333 help
334 Collect information on the number of bytes of storage I/O which this
335 task has caused.
336
337 Say N if unsure.
338
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339config AUDIT
340 bool "Auditing support"
Chris Wright804a6a492005-05-11 10:52:45 +0100341 depends on NET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342 help
343 Enable auditing infrastructure that can be used with another
344 kernel subsystem, such as SELinux (which requires this for
345 logging of avc messages output). Does not do system-call
346 auditing without CONFIG_AUDITSYSCALL.
347
348config AUDITSYSCALL
349 bool "Enable system-call auditing support"
Kumar Gala022382a2009-10-16 07:21:37 +0000350 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351 default y if SECURITY_SELINUX
352 help
353 Enable low-overhead system-call auditing infrastructure that
354 can be used independently or with another kernel subsystem,
Eric Paris67640b62009-12-17 20:12:06 -0500355 such as SELinux.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356
Eric Paris939a67f2009-12-17 20:12:06 -0500357config AUDIT_WATCH
358 def_bool y
359 depends on AUDITSYSCALL
360 select FSNOTIFY
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361
Al Viro74c3cbe2007-07-22 08:04:18 -0400362config AUDIT_TREE
363 def_bool y
Eric Paris63c882a2009-05-21 17:02:01 -0400364 depends on AUDITSYSCALL
Eric Paris28a3a7e2009-12-17 20:12:05 -0500365 select FSNOTIFY
Al Viro74c3cbe2007-07-22 08:04:18 -0400366
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000367source "kernel/irq/Kconfig"
368
Mike Travisc903ff82009-01-15 12:28:29 -0800369menu "RCU Subsystem"
370
371choice
372 prompt "RCU Implementation"
Paul E. McKenney31c9a242009-04-02 21:06:25 -0700373 default TREE_RCU
Mike Travisc903ff82009-01-15 12:28:29 -0800374
Mike Travisc903ff82009-01-15 12:28:29 -0800375config TREE_RCU
376 bool "Tree-based hierarchical RCU"
Paul E. McKenney687d7a92010-07-21 06:52:40 -0700377 depends on !PREEMPT && SMP
Mike Travisc903ff82009-01-15 12:28:29 -0800378 help
379 This option selects the RCU implementation that is
380 designed for very large SMP system with hundreds or
Paul E. McKenneyc17ef452009-06-23 17:12:47 -0700381 thousands of CPUs. It also scales down nicely to
382 smaller systems.
Mike Travisc903ff82009-01-15 12:28:29 -0800383
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700384config TREE_PREEMPT_RCU
Paul E. McKenneya57eb942010-06-29 16:49:16 -0700385 bool "Preemptible tree-based hierarchical RCU"
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700386 depends on PREEMPT
387 help
388 This option selects the RCU implementation that is
389 designed for very large SMP systems with hundreds or
390 thousands of CPUs, but for which real-time response
Paul E. McKenneybbe3eae2009-09-13 09:15:08 -0700391 is also required. It also scales down nicely to
392 smaller systems.
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700393
Paul E. McKenney9b1d82f2009-10-25 19:03:50 -0700394config TINY_RCU
395 bool "UP-only small-memory-footprint RCU"
396 depends on !SMP
397 help
398 This option selects the RCU implementation that is
399 designed for UP systems from which real-time response
400 is not required. This option greatly reduces the
401 memory footprint of RCU.
402
Paul E. McKenneya57eb942010-06-29 16:49:16 -0700403config TINY_PREEMPT_RCU
404 bool "Preemptible UP-only small-memory-footprint RCU"
405 depends on !SMP && PREEMPT
406 help
407 This option selects the RCU implementation that is designed
408 for real-time UP systems. This option greatly reduces the
409 memory footprint of RCU.
410
Mike Travisc903ff82009-01-15 12:28:29 -0800411endchoice
412
Paul E. McKenneya57eb942010-06-29 16:49:16 -0700413config PREEMPT_RCU
414 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
415 help
416 This option enables preemptible-RCU code that is common between
417 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
418
Mike Travisc903ff82009-01-15 12:28:29 -0800419config RCU_TRACE
420 bool "Enable tracing for RCU"
Mike Travisc903ff82009-01-15 12:28:29 -0800421 help
422 This option provides tracing in RCU which presents stats
423 in debugfs for debugging RCU implementation.
424
425 Say Y here if you want to enable RCU tracing
426 Say N if you are unsure.
427
428config RCU_FANOUT
429 int "Tree-based hierarchical RCU fanout value"
430 range 2 64 if 64BIT
431 range 2 32 if !64BIT
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700432 depends on TREE_RCU || TREE_PREEMPT_RCU
Mike Travisc903ff82009-01-15 12:28:29 -0800433 default 64 if 64BIT
434 default 32 if !64BIT
435 help
436 This option controls the fanout of hierarchical implementations
437 of RCU, allowing RCU to work efficiently on machines with
Paul E. McKenney4d87ffa2010-08-04 17:31:12 -0700438 large numbers of CPUs. This value must be at least the fourth
439 root of NR_CPUS, which allows NR_CPUS to be insanely large.
440 The default value of RCU_FANOUT should be used for production
441 systems, but if you are stress-testing the RCU implementation
442 itself, small RCU_FANOUT values allow you to test large-system
443 code paths on small(er) systems.
Mike Travisc903ff82009-01-15 12:28:29 -0800444
445 Select a specific number if testing RCU itself.
446 Take the default if unsure.
447
448config RCU_FANOUT_EXACT
449 bool "Disable tree-based hierarchical RCU auto-balancing"
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700450 depends on TREE_RCU || TREE_PREEMPT_RCU
Mike Travisc903ff82009-01-15 12:28:29 -0800451 default n
452 help
453 This option forces use of the exact RCU_FANOUT value specified,
454 regardless of imbalances in the hierarchy. This is useful for
455 testing RCU itself, and might one day be useful on systems with
456 strong NUMA behavior.
457
458 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
459
460 Say N if unsure.
461
Paul E. McKenney8bd93a22010-02-22 17:04:59 -0800462config RCU_FAST_NO_HZ
463 bool "Accelerate last non-dyntick-idle CPU's grace periods"
464 depends on TREE_RCU && NO_HZ && SMP
465 default n
466 help
467 This option causes RCU to attempt to accelerate grace periods
468 in order to allow the final CPU to enter dynticks-idle state
469 more quickly. On the other hand, this option increases the
470 overhead of the dynticks-idle checking, particularly on systems
471 with large numbers of CPUs.
472
473 Say Y if energy efficiency is critically important, particularly
474 if you have relatively few CPUs.
475
476 Say N if you are unsure.
477
Mike Travisc903ff82009-01-15 12:28:29 -0800478config TREE_RCU_TRACE
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700479 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
Mike Travisc903ff82009-01-15 12:28:29 -0800480 select DEBUG_FS
481 help
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700482 This option provides tracing for the TREE_RCU and
483 TREE_PREEMPT_RCU implementations, permitting Makefile to
484 trivially select kernel/rcutree_trace.c.
Mike Travisc903ff82009-01-15 12:28:29 -0800485
Paul E. McKenney24278d12010-09-27 17:25:23 -0700486config RCU_BOOST
487 bool "Enable RCU priority boosting"
Paul E. McKenney27f4d282011-02-07 12:47:15 -0800488 depends on RT_MUTEXES && PREEMPT_RCU
Paul E. McKenney24278d12010-09-27 17:25:23 -0700489 default n
490 help
491 This option boosts the priority of preempted RCU readers that
492 block the current preemptible RCU grace period for too long.
493 This option also prevents heavy loads from blocking RCU
494 callback invocation for all flavors of RCU.
495
496 Say Y here if you are working with real-time apps or heavy loads
497 Say N here if you are unsure.
498
499config RCU_BOOST_PRIO
500 int "Real-time priority to boost RCU readers to"
501 range 1 99
502 depends on RCU_BOOST
503 default 1
504 help
505 This option specifies the real-time priority to which preempted
506 RCU readers are to be boosted. If you are working with CPU-bound
507 real-time applications, you should specify a priority higher then
508 the highest-priority CPU-bound application.
509
510 Specify the real-time priority, or take the default if unsure.
511
512config RCU_BOOST_DELAY
513 int "Milliseconds to delay boosting after RCU grace-period start"
514 range 0 3000
515 depends on RCU_BOOST
516 default 500
517 help
518 This option specifies the time to wait after the beginning of
519 a given grace period before priority-boosting preempted RCU
520 readers blocking that grace period. Note that any RCU reader
521 blocking an expedited RCU grace period is boosted immediately.
522
523 Accept the default if unsure.
524
Mike Travisc903ff82009-01-15 12:28:29 -0800525endmenu # "RCU Subsystem"
526
Linus Torvalds1da177e2005-04-16 15:20:36 -0700527config IKCONFIG
Ross Birof2443ab2006-09-30 23:27:25 -0700528 tristate "Kernel .config support"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529 ---help---
530 This option enables the complete Linux kernel ".config" file
531 contents to be saved in the kernel. It provides documentation
532 of which kernel options are used in a running kernel or in an
533 on-disk kernel. This information can be extracted from the kernel
534 image file with the script scripts/extract-ikconfig and used as
535 input to rebuild the current kernel or to build another kernel.
536 It can also be extracted from a running kernel by reading
537 /proc/config.gz if enabled (below).
538
539config IKCONFIG_PROC
540 bool "Enable access to .config through /proc/config.gz"
541 depends on IKCONFIG && PROC_FS
542 ---help---
543 This option enables access to the kernel configuration file
544 through /proc/config.gz.
545
Alistair John Strachan794543a2007-05-08 00:31:15 -0700546config LOG_BUF_SHIFT
547 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
548 range 12 21
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700549 default 17
Alistair John Strachan794543a2007-05-08 00:31:15 -0700550 help
551 Select kernel log buffer size as a power of 2.
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700552 Examples:
553 17 => 128 KB
554 16 => 64 KB
555 15 => 32 KB
556 14 => 16 KB
Alistair John Strachan794543a2007-05-08 00:31:15 -0700557 13 => 8 KB
558 12 => 4 KB
559
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800560#
561# Architectures with an unreliable sched_clock() should select this:
562#
563config HAVE_UNSTABLE_SCHED_CLOCK
564 bool
565
Li Zefan23964d22009-01-15 13:50:58 -0800566menuconfig CGROUPS
567 boolean "Control Group support"
Kirill A. Shutemov0dea1162010-03-10 15:22:20 -0800568 depends on EVENTFD
Paul Menageddbcc7e2007-10-18 23:39:30 -0700569 help
Li Zefan23964d22009-01-15 13:50:58 -0800570 This option adds support for grouping sets of processes together, for
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800571 use with process control subsystems such as Cpusets, CFS, memory
572 controls or device isolation.
573 See
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800574 - Documentation/scheduler/sched-design-CFS.txt (CFS)
Li Zefan45ce80f2009-01-15 13:50:59 -0800575 - Documentation/cgroups/ (features for grouping, isolation
576 and resource control)
Paul Menageddbcc7e2007-10-18 23:39:30 -0700577
578 Say N if unsure.
579
Li Zefan23964d22009-01-15 13:50:58 -0800580if CGROUPS
581
Paul Menage006cb992007-10-18 23:39:43 -0700582config CGROUP_DEBUG
583 bool "Example debug cgroup subsystem"
Paul Menage418d7d82008-04-29 01:00:05 -0700584 default n
Paul Menage006cb992007-10-18 23:39:43 -0700585 help
586 This option enables a simple cgroup subsystem that
587 exports useful debugging information about the cgroups
Li Zefan23964d22009-01-15 13:50:58 -0800588 framework.
Paul Menage006cb992007-10-18 23:39:43 -0700589
Li Zefan23964d22009-01-15 13:50:58 -0800590 Say N if unsure.
Paul Menage006cb992007-10-18 23:39:43 -0700591
Matt Helsleydc52ddc2008-10-18 20:27:21 -0700592config CGROUP_FREEZER
Li Zefan23964d22009-01-15 13:50:58 -0800593 bool "Freezer cgroup subsystem"
Li Zefan23964d22009-01-15 13:50:58 -0800594 help
595 Provides a way to freeze and unfreeze all tasks in a
Matt Helsleydc52ddc2008-10-18 20:27:21 -0700596 cgroup.
597
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700598config CGROUP_DEVICE
599 bool "Device controller for cgroups"
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700600 help
601 Provides a cgroup implementing whitelists for devices which
602 a process in the cgroup can mknod or open.
603
Linus Torvalds1da177e2005-04-16 15:20:36 -0700604config CPUSETS
605 bool "Cpuset support"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700606 help
Randy Dunlapd9fd8a62005-07-27 11:45:11 -0700607 This option will let you create and manage CPUSETs which
Linus Torvalds1da177e2005-04-16 15:20:36 -0700608 allow dynamically partitioning a system into sets of CPUs and
609 Memory Nodes and assigning tasks to run only within those sets.
610 This is primarily useful on large SMP or NUMA systems.
611
612 Say N if unsure.
613
Li Zefan23964d22009-01-15 13:50:58 -0800614config PROC_PID_CPUSET
615 bool "Include legacy /proc/<pid>/cpuset file"
616 depends on CPUSETS
617 default y
618
Srivatsa Vaddagirid842de82007-12-02 20:04:49 +0100619config CGROUP_CPUACCT
620 bool "Simple CPU accounting cgroup subsystem"
Srivatsa Vaddagirid842de82007-12-02 20:04:49 +0100621 help
622 Provides a simple Resource Controller for monitoring the
Li Zefan23964d22009-01-15 13:50:58 -0800623 total CPU consumed by the tasks in a cgroup.
Srivatsa Vaddagirid842de82007-12-02 20:04:49 +0100624
Pavel Emelianove552b662008-02-07 00:13:49 -0800625config RESOURCE_COUNTERS
626 bool "Resource counters"
627 help
628 This option enables controller independent resource accounting
Li Zefan23964d22009-01-15 13:50:58 -0800629 infrastructure that works with cgroups.
Pavel Emelianove552b662008-02-07 00:13:49 -0800630
Balbir Singh00f0b822008-03-04 14:28:39 -0800631config CGROUP_MEM_RES_CTLR
632 bool "Memory Resource Controller for Control Groups"
Daniel Lezcano79ae9c22010-10-27 15:34:39 -0700633 depends on RESOURCE_COUNTERS
Balbir Singhcf475ad2008-04-29 01:00:16 -0700634 select MM_OWNER
Balbir Singh00f0b822008-03-04 14:28:39 -0800635 help
KAMEZAWA Hiroyuki84ad6d72008-10-29 14:01:06 -0700636 Provides a memory resource controller that manages both anonymous
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +0100637 memory and page cache. (See Documentation/cgroups/memory.txt)
Balbir Singh00f0b822008-03-04 14:28:39 -0800638
639 Note that setting this option increases fixed memory overhead
KAMEZAWA Hiroyuki84ad6d72008-10-29 14:01:06 -0700640 associated with each page of memory in the system. By this,
641 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
642 usage tracking struct at boot. Total amount of this is printed out
643 at boot.
Balbir Singh00f0b822008-03-04 14:28:39 -0800644
645 Only enable when you're ok with these trade offs and really
KAMEZAWA Hiroyuki84ad6d72008-10-29 14:01:06 -0700646 sure you need the memory resource controller. Even when you enable
647 this, you can set "cgroup_disable=memory" at your boot option to
648 disable memory resource controller and you can avoid overheads.
Li Zefanc9d54092009-01-07 18:07:35 -0800649 (and lose benefits of memory resource controller)
Balbir Singh00f0b822008-03-04 14:28:39 -0800650
Balbir Singhcf475ad2008-04-29 01:00:16 -0700651 This config option also selects MM_OWNER config option, which
652 could in turn add some fork/exit overhead.
653
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800654config CGROUP_MEM_RES_CTLR_SWAP
KAMEZAWA Hiroyuki65e0e812010-08-10 18:02:56 -0700655 bool "Memory Resource Controller Swap Extension"
656 depends on CGROUP_MEM_RES_CTLR && SWAP
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800657 help
658 Add swap management feature to memory resource controller. When you
659 enable this, you can limit mem+swap usage per cgroup. In other words,
660 when you disable this, memory resource controller has no cares to
661 usage of swap...a process can exhaust all of the swap. This extension
662 is useful when you want to avoid exhaustion swap but this itself
663 adds more overheads and consumes memory for remembering information.
664 Especially if you use 32bit system or small memory system, please
665 be careful about enabling this. When memory resource controller
666 is disabled by boot option, this will be automatically disabled and
667 there will be no overhead from this. Even when you set this config=y,
668 if boot option "noswapaccount" is set, swap will not be accounted.
KAMEZAWA Hiroyuki627991a2009-04-02 16:57:47 -0700669 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
670 size is 4096bytes, 512k per 1Gbytes of swap.
Michal Hockoa42c3902010-11-24 12:57:08 -0800671config CGROUP_MEM_RES_CTLR_SWAP_ENABLED
672 bool "Memory Resource Controller Swap Extension enabled by default"
673 depends on CGROUP_MEM_RES_CTLR_SWAP
674 default y
675 help
676 Memory Resource Controller Swap Extension comes with its price in
677 a bigger memory consumption. General purpose distribution kernels
Jim Cromie43d547f2010-12-17 14:32:36 -0700678 which want to enable the feature but keep it disabled by default
Michal Hockoa42c3902010-11-24 12:57:08 -0800679 and let the user enable it by swapaccount boot command line
680 parameter should have this option unselected.
681 For those who want to have the feature enabled by default should
682 select this option (if, for some reason, they need to disable it
683 then noswapaccount does the trick).
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800684
Stephane Eraniane5d13672011-02-14 11:20:01 +0200685config CGROUP_PERF
686 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
687 depends on PERF_EVENTS && CGROUPS
688 help
689 This option extends the per-cpu mode to restrict monitoring to
Li Zefan2d0f2522011-03-03 14:26:20 +0800690 threads which belong to the cgroup specified and run on the
Stephane Eraniane5d13672011-02-14 11:20:01 +0200691 designated cpu.
692
693 Say N if unsure.
694
Dhaval Giani7c941432010-01-20 13:26:18 +0100695menuconfig CGROUP_SCHED
696 bool "Group CPU scheduler"
Daniel Lezcano79ae9c22010-10-27 15:34:39 -0700697 depends on EXPERIMENTAL
Dhaval Giani7c941432010-01-20 13:26:18 +0100698 default n
699 help
700 This feature lets CPU scheduler recognize task groups and control CPU
701 bandwidth allocation to such task groups. It uses cgroups to group
702 tasks.
703
704if CGROUP_SCHED
705config FAIR_GROUP_SCHED
706 bool "Group scheduling for SCHED_OTHER"
707 depends on CGROUP_SCHED
708 default CGROUP_SCHED
709
710config RT_GROUP_SCHED
711 bool "Group scheduling for SCHED_RR/FIFO"
712 depends on EXPERIMENTAL
713 depends on CGROUP_SCHED
714 default n
715 help
716 This feature lets you explicitly allocate real CPU bandwidth
Li Zefan32bd7eb2010-03-24 13:17:19 +0800717 to task groups. If enabled, it will also make it impossible to
Dhaval Giani7c941432010-01-20 13:26:18 +0100718 schedule realtime tasks for non-root users until you allocate
719 realtime bandwidth for them.
720 See Documentation/scheduler/sched-rt-group.txt for more information.
721
722endif #CGROUP_SCHED
723
Vivek Goyalafc24d42010-04-26 19:27:56 +0200724config BLK_CGROUP
725 tristate "Block IO controller"
Daniel Lezcano79ae9c22010-10-27 15:34:39 -0700726 depends on BLOCK
Vivek Goyalafc24d42010-04-26 19:27:56 +0200727 default n
728 ---help---
729 Generic block IO controller cgroup interface. This is the common
730 cgroup interface which should be used by various IO controlling
731 policies.
732
733 Currently, CFQ IO scheduler uses it to recognize task groups and
734 control disk bandwidth allocation (proportional time slice allocation)
Vivek Goyale43473b2010-09-15 17:06:35 -0400735 to such task groups. It is also used by bio throttling logic in
736 block layer to implement upper limit in IO rates on a device.
Vivek Goyalafc24d42010-04-26 19:27:56 +0200737
738 This option only enables generic Block IO controller infrastructure.
Vivek Goyale43473b2010-09-15 17:06:35 -0400739 One needs to also enable actual IO controlling logic/policy. For
Michael Witten79e2e752011-01-16 21:43:10 +0000740 enabling proportional weight division of disk bandwidth in CFQ, set
741 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
Michael Wittenc5e05912011-01-17 00:08:41 +0000742 CONFIG_BLK_DEV_THROTTLING=y.
Vivek Goyalafc24d42010-04-26 19:27:56 +0200743
744 See Documentation/cgroups/blkio-controller.txt for more information.
745
746config DEBUG_BLK_CGROUP
747 bool "Enable Block IO controller debugging"
748 depends on BLK_CGROUP
749 default n
750 ---help---
751 Enable some debugging help. Currently it exports additional stat
752 files in a cgroup which can be useful for debugging.
753
Li Zefan23964d22009-01-15 13:50:58 -0800754endif # CGROUPS
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800755
Daniel Lezcano8dd2a822010-10-27 15:34:38 -0700756menuconfig NAMESPACES
David Rientjes6a108a12011-01-20 14:44:16 -0800757 bool "Namespaces support" if EXPERT
758 default !EXPERT
Pavel Emelyanovc5289a692008-02-08 04:18:19 -0800759 help
760 Provides the way to make tasks work with different objects using
761 the same id. For example same IPC id may refer to different objects
762 or same user id or pid may refer to different tasks when used in
763 different namespaces.
764
Daniel Lezcano8dd2a822010-10-27 15:34:38 -0700765if NAMESPACES
766
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -0800767config UTS_NS
768 bool "UTS namespace"
Daniel Lezcano17a6d442010-10-27 15:34:37 -0700769 default y
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -0800770 help
771 In this namespace tasks see different info provided with the
772 uname() system call
773
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -0800774config IPC_NS
775 bool "IPC namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -0700776 depends on (SYSVIPC || POSIX_MQUEUE)
Daniel Lezcano17a6d442010-10-27 15:34:37 -0700777 default y
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -0800778 help
779 In this namespace tasks work with IPC ids which correspond to
Serge E. Hallyn614b84c2009-04-06 19:01:08 -0700780 different IPC objects in different namespaces.
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -0800781
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -0800782config USER_NS
783 bool "User namespace (EXPERIMENTAL)"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -0700784 depends on EXPERIMENTAL
Daniel Lezcano17a6d442010-10-27 15:34:37 -0700785 default y
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -0800786 help
787 This allows containers, i.e. vservers, to use user namespaces
788 to provide different user info for different servers.
789 If unsure, say N.
790
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -0800791config PID_NS
Daniel Lezcano9bd38c22010-10-27 15:34:37 -0700792 bool "PID Namespaces"
Daniel Lezcano17a6d442010-10-27 15:34:37 -0700793 default y
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -0800794 help
Heikki Orsila12d2b8f2008-07-06 15:48:02 +0300795 Support process id namespaces. This allows having multiple
Matt LaPlante692105b2009-01-26 11:12:25 +0100796 processes with the same pid as long as they are in different
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -0800797 pid namespaces. This is a building block of containers.
798
Matt Helsleyd6eb6332009-01-26 12:25:55 -0800799config NET_NS
800 bool "Network namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -0700801 depends on NET
Daniel Lezcano17a6d442010-10-27 15:34:37 -0700802 default y
Matt Helsleyd6eb6332009-01-26 12:25:55 -0800803 help
804 Allow user space to create what appear to be multiple instances
805 of the network stack.
806
Daniel Lezcano8dd2a822010-10-27 15:34:38 -0700807endif # NAMESPACES
808
Mike Galbraith5091faa2010-11-30 14:18:03 +0100809config SCHED_AUTOGROUP
810 bool "Automatic process group scheduling"
811 select EVENTFD
812 select CGROUPS
813 select CGROUP_SCHED
814 select FAIR_GROUP_SCHED
815 help
816 This option optimizes the scheduler for common desktop workloads by
817 automatically creating and populating task groups. This separation
818 of workloads isolates aggressive CPU burners (like build jobs) from
819 desktop applications. Task group autogeneration is currently based
820 upon task session.
821
Daniel Lezcano7af37be2010-10-27 15:34:41 -0700822config MM_OWNER
823 bool
824
825config SYSFS_DEPRECATED
Ferenc Wagner5d6a4ea2011-01-10 19:04:22 +0100826 bool "Enable deprecated sysfs features to support old userspace tools"
Daniel Lezcano7af37be2010-10-27 15:34:41 -0700827 depends on SYSFS
828 default n
829 help
830 This option adds code that switches the layout of the "block" class
831 devices, to not show up in /sys/class/block/, but only in
832 /sys/block/.
833
834 This switch is only active when the sysfs.deprecated=1 boot option is
835 passed or the SYSFS_DEPRECATED_V2 option is set.
836
837 This option allows new kernels to run on old distributions and tools,
838 which might get confused by /sys/class/block/. Since 2007/2008 all
839 major distributions and tools handle this just fine.
840
841 Recent distributions and userspace tools after 2009/2010 depend on
842 the existence of /sys/class/block/, and will not work with this
843 option enabled.
844
845 Only if you are using a new kernel on an old distribution, you might
846 need to say Y here.
847
848config SYSFS_DEPRECATED_V2
Ferenc Wagner5d6a4ea2011-01-10 19:04:22 +0100849 bool "Enable deprecated sysfs features by default"
Daniel Lezcano7af37be2010-10-27 15:34:41 -0700850 default n
851 depends on SYSFS
852 depends on SYSFS_DEPRECATED
853 help
854 Enable deprecated sysfs by default.
855
856 See the CONFIG_SYSFS_DEPRECATED option for more details about this
857 option.
858
859 Only if you are using a new kernel on an old distribution, you might
860 need to say Y here. Even then, odds are you would not need it
861 enabled, you can always pass the boot option if absolutely necessary.
862
863config RELAY
864 bool "Kernel->user space relay support (formerly relayfs)"
865 help
866 This option enables support for relay interface support in
867 certain file systems (such as debugfs).
868 It is designed to provide an efficient mechanism for tools and
869 facilities to relay large amounts of data from kernel space to
870 user space.
871
872 If unsure, say N.
873
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -0800874config BLK_DEV_INITRD
875 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
876 depends on BROKEN || !FRV
877 help
878 The initial RAM filesystem is a ramfs which is loaded by the
879 boot loader (loadlin or lilo) and that is mounted as root
880 before the normal boot procedure. It is typically used to
881 load modules needed to mount the "real" root file system,
882 etc. See <file:Documentation/initrd.txt> for details.
883
884 If RAM disk support (BLK_DEV_RAM) is also included, this
885 also enables initial RAM disk (initrd) support and adds
886 15 Kbytes (more on some other architectures) to the kernel size.
887
888 If unsure say Y.
889
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -0800890if BLK_DEV_INITRD
891
Sam Ravnborgdbec4862005-08-10 20:44:50 +0200892source "usr/Kconfig"
893
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -0800894endif
895
Linus Torvaldsc45b4f12005-12-14 18:52:21 -0800896config CC_OPTIMIZE_FOR_SIZE
Ingo Molnar96fffeb2008-04-28 01:39:43 +0200897 bool "Optimize for size"
Linus Torvaldsc45b4f12005-12-14 18:52:21 -0800898 help
899 Enabling this option will pass "-Os" instead of "-O2" to gcc
900 resulting in a smaller kernel.
901
jkacur775a7222008-07-16 00:31:16 +0200902 If unsure, say Y.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -0800903
Randy Dunlap08470622006-09-30 23:28:13 -0700904config SYSCTL
905 bool
906
Randy Dunlapb943c462009-03-10 12:55:46 -0700907config ANON_INODES
908 bool
909
David Rientjes6a108a12011-01-20 14:44:16 -0800910menuconfig EXPERT
911 bool "Configure standard kernel features (expert users)"
Josh Triplettf505c552011-06-05 18:23:58 -0700912 # Unhide debug options, to make the on-by-default options visible
913 select DEBUG_KERNEL
Linus Torvalds1da177e2005-04-16 15:20:36 -0700914 help
915 This option allows certain base kernel options and settings
916 to be disabled or tweaked. This is for specialized
917 environments which can tolerate a "non-standard" kernel.
918 Only use this if you really know what you are doing.
919
Chuck Ebbertae81f9e2006-09-16 12:15:53 -0700920config UID16
David Rientjes6a108a12011-01-20 14:44:16 -0800921 bool "Enable 16-bit UID system calls" if EXPERT
David S. Miller09337f52008-04-26 03:17:12 -0700922 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 -0700923 default y
924 help
925 This enables the legacy 16-bit UID syscall wrappers.
926
Eric W. Biedermanb89a8172006-09-27 01:51:04 -0700927config SYSCTL_SYSCALL
David Rientjes6a108a12011-01-20 14:44:16 -0800928 bool "Sysctl syscall support" if EXPERT
Eric W. Biederman26a70342009-11-05 05:26:41 -0800929 depends on PROC_SYSCTL
Eric W. Biederman13bb7e32006-11-08 17:44:51 -0800930 default y
Eric W. Biedermanb89a8172006-09-27 01:51:04 -0700931 select SYSCTL
932 ---help---
Eric W. Biederman13bb7e32006-11-08 17:44:51 -0800933 sys_sysctl uses binary paths that have been found challenging
934 to properly maintain and use. The interface in /proc/sys
935 using paths with ascii names is now the primary path to this
936 information.
Eric W. Biedermanb89a8172006-09-27 01:51:04 -0700937
Eric W. Biederman13bb7e32006-11-08 17:44:51 -0800938 Almost nothing using the binary sysctl interface so if you are
939 trying to save some space it is probably safe to disable this,
940 making your kernel marginally smaller.
Eric W. Biedermanb89a8172006-09-27 01:51:04 -0700941
Eric W. Biederman13bb7e32006-11-08 17:44:51 -0800942 If unsure say Y here.
Chuck Ebbertae81f9e2006-09-16 12:15:53 -0700943
Linus Torvalds1da177e2005-04-16 15:20:36 -0700944config KALLSYMS
David Rientjes6a108a12011-01-20 14:44:16 -0800945 bool "Load all symbols for debugging/ksymoops" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -0700946 default y
947 help
948 Say Y here to let the kernel print out symbolic crash information and
949 symbolic stack backtraces. This increases the size of the kernel
950 somewhat, as all symbols have to be loaded into the kernel image.
951
952config KALLSYMS_ALL
953 bool "Include all symbols in kallsyms"
954 depends on DEBUG_KERNEL && KALLSYMS
955 help
Artem Bityutskiy71a83ec2011-04-05 13:24:57 +0300956 Normally kallsyms only contains the symbols of functions for nicer
957 OOPS messages and backtraces (i.e., symbols from the text and inittext
958 sections). This is sufficient for most cases. And only in very rare
959 cases (e.g., when a debugger is used) all symbols are required (e.g.,
960 names of variables from the data sections, etc).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700961
Artem Bityutskiy71a83ec2011-04-05 13:24:57 +0300962 This option makes sure that all symbols are loaded into the kernel
963 image (i.e., symbols from all sections) in cost of increased kernel
964 size (depending on the kernel configuration, it may be 300KiB or
965 something like this).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700966
Artem Bityutskiy71a83ec2011-04-05 13:24:57 +0300967 Say N unless you really need all symbols.
Matt Mackalld59745c2005-05-01 08:59:02 -0700968
Greg Kroah-Hartman712f47c2005-11-16 11:27:07 -0800969config HOTPLUG
David Rientjes6a108a12011-01-20 14:44:16 -0800970 bool "Support for hot-pluggable devices" if EXPERT
Greg Kroah-Hartman712f47c2005-11-16 11:27:07 -0800971 default y
972 help
973 This option is provided for the case where no hotplug or uevent
974 capabilities is wanted by the kernel. You should only consider
975 disabling this option for embedded systems that do not use modules, a
976 dynamic /dev tree, or dynamic device discovery. Just say Y.
977
Matt Mackalld59745c2005-05-01 08:59:02 -0700978config PRINTK
979 default y
David Rientjes6a108a12011-01-20 14:44:16 -0800980 bool "Enable support for printk" if EXPERT
Matt Mackalld59745c2005-05-01 08:59:02 -0700981 help
982 This option enables normal printk support. Removing it
983 eliminates most of the message strings from the kernel image
984 and makes the kernel more or less silent. As this makes it
985 very difficult to diagnose system problems, saying N here is
986 strongly discouraged.
987
Matt Mackallc8538a72005-05-01 08:59:01 -0700988config BUG
David Rientjes6a108a12011-01-20 14:44:16 -0800989 bool "BUG() support" if EXPERT
Matt Mackallc8538a72005-05-01 08:59:01 -0700990 default y
991 help
992 Disabling this option eliminates support for BUG and WARN, reducing
993 the size of your kernel image and potentially quietly ignoring
994 numerous fatal conditions. You should only consider disabling this
995 option for embedded systems with no facilities for reporting errors.
996 Just say Y.
997
Matt Mackall708e9a72006-01-08 01:05:25 -0800998config ELF_CORE
999 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001000 bool "Enable ELF core dumps" if EXPERT
Matt Mackall708e9a72006-01-08 01:05:25 -08001001 help
1002 Enable support for generating core dumps. Disabling saves about 4k.
1003
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001004config PCSPKR_PLATFORM
David Rientjes6a108a12011-01-20 14:44:16 -08001005 bool "Enable PC-Speaker support" if EXPERT
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001006 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
1007 default y
1008 help
1009 This option allows to disable the internal PC-Speaker
1010 support, saving some memory.
1011
Linus Torvalds1da177e2005-04-16 15:20:36 -07001012config BASE_FULL
1013 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001014 bool "Enable full-sized data structures for core" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001015 help
1016 Disabling this option reduces the size of miscellaneous core
1017 kernel data structures. This saves memory on small machines,
1018 but may reduce performance.
1019
1020config FUTEX
David Rientjes6a108a12011-01-20 14:44:16 -08001021 bool "Enable futex support" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001022 default y
Ingo Molnar23f78d4a2006-06-27 02:54:53 -07001023 select RT_MUTEXES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001024 help
1025 Disabling this option will cause the kernel to be built without
1026 support for "fast userspace mutexes". The resulting kernel may not
1027 run glibc-based applications correctly.
1028
1029config EPOLL
David Rientjes6a108a12011-01-20 14:44:16 -08001030 bool "Enable eventpoll support" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001031 default y
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001032 select ANON_INODES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001033 help
1034 Disabling this option will cause the kernel to be built without
1035 support for epoll family of system calls.
1036
Davide Libenzifba2afa2007-05-10 22:23:13 -07001037config SIGNALFD
David Rientjes6a108a12011-01-20 14:44:16 -08001038 bool "Enable signalfd() system call" if EXPERT
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001039 select ANON_INODES
Davide Libenzifba2afa2007-05-10 22:23:13 -07001040 default y
1041 help
1042 Enable the signalfd() system call that allows to receive signals
1043 on a file descriptor.
1044
1045 If unsure, say Y.
1046
Davide Libenzib215e282007-05-10 22:23:16 -07001047config TIMERFD
David Rientjes6a108a12011-01-20 14:44:16 -08001048 bool "Enable timerfd() system call" if EXPERT
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001049 select ANON_INODES
Davide Libenzib215e282007-05-10 22:23:16 -07001050 default y
1051 help
1052 Enable the timerfd() system call that allows to receive timer
1053 events on a file descriptor.
1054
1055 If unsure, say Y.
1056
Davide Libenzie1ad7462007-05-10 22:23:19 -07001057config EVENTFD
David Rientjes6a108a12011-01-20 14:44:16 -08001058 bool "Enable eventfd() system call" if EXPERT
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001059 select ANON_INODES
Davide Libenzie1ad7462007-05-10 22:23:19 -07001060 default y
1061 help
1062 Enable the eventfd() system call that allows to receive both
1063 kernel notification (ie. KAIO) or userspace notifications.
1064
1065 If unsure, say Y.
1066
Linus Torvalds1da177e2005-04-16 15:20:36 -07001067config SHMEM
David Rientjes6a108a12011-01-20 14:44:16 -08001068 bool "Use full shmem filesystem" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001069 default y
1070 depends on MMU
1071 help
1072 The shmem is an internal filesystem used to manage shared memory.
1073 It is backed by swap and manages resource limits. It is also exported
1074 to userspace as tmpfs if TMPFS is enabled. Disabling this
1075 option replaces shmem and tmpfs with the much simpler ramfs code,
1076 which may be appropriate on small systems without swap.
1077
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001078config AIO
David Rientjes6a108a12011-01-20 14:44:16 -08001079 bool "Enable AIO support" if EXPERT
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001080 default y
1081 help
1082 This option enables POSIX asynchronous I/O which may by used
1083 by some high performance threaded applications. Disabling
1084 this option saves about 7k.
1085
Randy Dunlap6befe5f2011-04-26 12:33:21 -07001086config EMBEDDED
1087 bool "Embedded system"
1088 select EXPERT
1089 help
1090 This option should be enabled if compiling the kernel for
1091 an embedded system so certain expert options are available
1092 for configuration.
1093
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001094config HAVE_PERF_EVENTS
Thomas Gleixner0793a612008-12-04 20:12:29 +01001095 bool
Mike Frysinger018df722009-06-12 13:17:43 -04001096 help
1097 See tools/perf/design.txt for details.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001098
Peter Zijlstra906010b2009-09-21 16:08:49 +02001099config PERF_USE_VMALLOC
1100 bool
1101 help
1102 See tools/perf/design.txt for details
1103
Ingo Molnar57c0c152009-09-21 12:20:38 +02001104menu "Kernel Performance Events And Counters"
Thomas Gleixner0793a612008-12-04 20:12:29 +01001105
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001106config PERF_EVENTS
Ingo Molnar57c0c152009-09-21 12:20:38 +02001107 bool "Kernel performance events and counters"
1108 default y if (PROFILING || PERF_COUNTERS)
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001109 depends on HAVE_PERF_EVENTS
Ingo Molnar4c59e462008-12-08 19:38:33 +01001110 select ANON_INODES
Peter Zijlstrae360adb2010-10-14 14:01:34 +08001111 select IRQ_WORK
Thomas Gleixner0793a612008-12-04 20:12:29 +01001112 help
Ingo Molnar57c0c152009-09-21 12:20:38 +02001113 Enable kernel support for various performance events provided
1114 by software and hardware.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001115
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001116 Software events are supported either built-in or via the
Ingo Molnar57c0c152009-09-21 12:20:38 +02001117 use of generic tracepoints.
1118
1119 Most modern CPUs support performance events via performance
1120 counter registers. These registers count the number of certain
Thomas Gleixner0793a612008-12-04 20:12:29 +01001121 types of hw events: such as instructions executed, cachemisses
1122 suffered, or branches mis-predicted - without slowing down the
1123 kernel or applications. These registers can also trigger interrupts
1124 when a threshold number of events have passed - and can thus be
1125 used to profile the code that runs on that CPU.
1126
Ingo Molnar57c0c152009-09-21 12:20:38 +02001127 The Linux Performance Event subsystem provides an abstraction of
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001128 these software and hardware event capabilities, available via a
Ingo Molnar57c0c152009-09-21 12:20:38 +02001129 system call and used by the "perf" utility in tools/perf/. It
Thomas Gleixner0793a612008-12-04 20:12:29 +01001130 provides per task and per CPU counters, and it provides event
1131 capabilities on top of those.
1132
1133 Say Y if unsure.
1134
Ingo Molnar57c0c152009-09-21 12:20:38 +02001135config PERF_COUNTERS
1136 bool "Kernel performance counters (old config option)"
1137 depends on HAVE_PERF_EVENTS
1138 help
1139 This config has been obsoleted by the PERF_EVENTS
1140 config option - please see that one for details.
1141
1142 It has no effect on the kernel whether you enable
1143 it or not, it is a compatibility placeholder.
1144
1145 Say N if unsure.
1146
Peter Zijlstra906010b2009-09-21 16:08:49 +02001147config DEBUG_PERF_USE_VMALLOC
1148 default n
1149 bool "Debug: use vmalloc to back perf mmap() buffers"
1150 depends on PERF_EVENTS && DEBUG_KERNEL
1151 select PERF_USE_VMALLOC
1152 help
1153 Use vmalloc memory to back perf mmap() buffers.
1154
1155 Mostly useful for debugging the vmalloc code on platforms
1156 that don't require it.
1157
1158 Say N if unsure.
1159
Thomas Gleixner0793a612008-12-04 20:12:29 +01001160endmenu
1161
Christoph Lameterf8891e52006-06-30 01:55:45 -07001162config VM_EVENT_COUNTERS
1163 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001164 bool "Enable VM event counters for /proc/vmstat" if EXPERT
Christoph Lameterf8891e52006-06-30 01:55:45 -07001165 help
Paul Jackson2aea4fb2006-12-22 01:06:10 -08001166 VM event counters are needed for event counts to be shown.
1167 This option allows the disabling of the VM event counters
David Rientjes6a108a12011-01-20 14:44:16 -08001168 on EXPERT systems. /proc/vmstat will only show page counts
Paul Jackson2aea4fb2006-12-22 01:06:10 -08001169 if VM event counters are disabled.
Christoph Lameterf8891e52006-06-30 01:55:45 -07001170
Thomas Petazzoni3d137312008-08-19 10:28:24 +02001171config PCI_QUIRKS
1172 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001173 bool "Enable PCI quirk workarounds" if EXPERT
Geert Uytterhoeven61cfc7e2008-10-22 08:53:25 +02001174 depends on PCI
Thomas Petazzoni3d137312008-08-19 10:28:24 +02001175 help
1176 This enables workarounds for various PCI chipset
1177 bugs/quirks. Disable this only if your target machine is
1178 unaffected by PCI quirks.
1179
Christoph Lameter41ecc552007-05-09 02:32:44 -07001180config SLUB_DEBUG
1181 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001182 bool "Enable SLUB debugging support" if EXPERT
Christoph Lameterf6acb632008-04-29 16:16:06 -07001183 depends on SLUB && SYSFS
Christoph Lameter41ecc552007-05-09 02:32:44 -07001184 help
1185 SLUB has extensive debug support features. Disabling these can
1186 result in significant savings in code size. This also disables
1187 SLUB sysfs support. /sys/slab will not exist and there will be
1188 no support for cache validation etc.
1189
Randy Dunlapb943c462009-03-10 12:55:46 -07001190config COMPAT_BRK
1191 bool "Disable heap randomization"
1192 default y
1193 help
1194 Randomizing heap placement makes heap exploits harder, but it
1195 also breaks ancient binaries (including anything libc5 based).
1196 This option changes the bootup default to heap randomization
Matt LaPlante692105b2009-01-26 11:12:25 +01001197 disabled, and can be overridden at runtime by setting
Randy Dunlapb943c462009-03-10 12:55:46 -07001198 /proc/sys/kernel/randomize_va_space to 2.
1199
1200 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1201
Christoph Lameter81819f02007-05-06 14:49:36 -07001202choice
1203 prompt "Choose SLAB allocator"
Christoph Lametera0acd822007-07-17 04:03:32 -07001204 default SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -07001205 help
1206 This option allows to select a slab allocator.
1207
1208config SLAB
1209 bool "SLAB"
1210 help
1211 The regular slab allocator that is established and known to work
Christoph Lameter34013882007-05-09 02:32:47 -07001212 well in all environments. It organizes cache hot objects in
Simon Arlott02f56212008-11-05 22:18:19 +00001213 per cpu and per node queues.
Christoph Lameter81819f02007-05-06 14:49:36 -07001214
1215config SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -07001216 bool "SLUB (Unqueued Allocator)"
1217 help
1218 SLUB is a slab allocator that minimizes cache line usage
1219 instead of managing queues of cached objects (SLAB approach).
1220 Per cpu caching is realized using slabs of objects instead
1221 of queues of objects. SLUB can use memory efficiently
Simon Arlott02f56212008-11-05 22:18:19 +00001222 and has enhanced diagnostics. SLUB is the default choice for
1223 a slab allocator.
Christoph Lameter81819f02007-05-06 14:49:36 -07001224
1225config SLOB
David Rientjes6a108a12011-01-20 14:44:16 -08001226 depends on EXPERT
Christoph Lameter81819f02007-05-06 14:49:36 -07001227 bool "SLOB (Simple Allocator)"
1228 help
Matt Mackall37291452008-02-04 22:29:38 -08001229 SLOB replaces the stock allocator with a drastically simpler
1230 allocator. SLOB is generally more space efficient but
1231 does not perform as well on large systems.
Christoph Lameter81819f02007-05-06 14:49:36 -07001232
1233endchoice
1234
Jie Zhangea637632009-12-14 18:00:02 -08001235config MMAP_ALLOW_UNINITIALIZED
1236 bool "Allow mmapped anonymous memory to be uninitialized"
David Rientjes6a108a12011-01-20 14:44:16 -08001237 depends on EXPERT && !MMU
Jie Zhangea637632009-12-14 18:00:02 -08001238 default n
1239 help
1240 Normally, and according to the Linux spec, anonymous memory obtained
1241 from mmap() has it's contents cleared before it is passed to
1242 userspace. Enabling this config option allows you to request that
1243 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1244 providing a huge performance boost. If this option is not enabled,
1245 then the flag will be ignored.
1246
1247 This is taken advantage of by uClibc's malloc(), and also by
1248 ELF-FDPIC binfmt's brk and stack allocator.
1249
1250 Because of the obvious security issues, this option should only be
1251 enabled on embedded devices where you control what is run in
1252 userspace. Since that isn't generally a problem on no-MMU systems,
1253 it is normally safe to say Y here.
1254
1255 See Documentation/nommu-mmap.txt for more information.
1256
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001257config PROFILING
Robert Richterb309a292010-02-26 15:01:23 +01001258 bool "Profiling support"
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001259 help
1260 Say Y here to enable the extended profiling support mechanisms used
1261 by profilers such as OProfile.
1262
Ingo Molnar5f87f112008-07-23 14:15:22 +02001263#
1264# Place an empty function call at each tracepoint site. Can be
1265# dynamically changed for a probe function.
1266#
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001267config TRACEPOINTS
Ingo Molnar5f87f112008-07-23 14:15:22 +02001268 bool
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001269
Mathieu Desnoyersfb32e032008-02-02 15:10:33 -05001270source "arch/Kconfig"
1271
Linus Torvalds1da177e2005-04-16 15:20:36 -07001272endmenu # General setup
1273
Dmitry Baryshkovee7e5512008-06-29 14:18:46 +04001274config HAVE_GENERIC_DMA_COHERENT
1275 bool
1276 default n
1277
Linus Torvalds158a9622008-01-02 13:04:48 -08001278config SLABINFO
1279 bool
1280 depends on PROC_FS
Christoph Lameter0f389ec2008-04-14 18:53:02 +03001281 depends on SLAB || SLUB_DEBUG
Linus Torvalds158a9622008-01-02 13:04:48 -08001282 default y
1283
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001284config RT_MUTEXES
1285 boolean
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001286
Linus Torvalds1da177e2005-04-16 15:20:36 -07001287config BASE_SMALL
1288 int
1289 default 0 if BASE_FULL
1290 default 1 if !BASE_FULL
1291
Jan Engelhardt66da5732007-07-15 23:39:29 -07001292menuconfig MODULES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001293 bool "Enable loadable module support"
1294 help
1295 Kernel modules are small pieces of compiled code which can
1296 be inserted in the running kernel, rather than being
1297 permanently built into the kernel. You use the "modprobe"
1298 tool to add (and sometimes remove) them. If you say Y here,
1299 many parts of the kernel can be built as modules (by
1300 answering M instead of Y where indicated): this is most
1301 useful for infrequently used options which are not required
1302 for booting. For more information, see the man pages for
1303 modprobe, lsmod, modinfo, insmod and rmmod.
1304
1305 If you say Y here, you will need to run "make
1306 modules_install" to put the modules under /lib/modules/
1307 where modprobe can find them (you may need to be root to do
1308 this).
1309
1310 If unsure, say Y.
1311
Robert P. J. Day0b0de142008-08-04 13:31:32 -04001312if MODULES
1313
Linus Torvalds826e4502008-05-04 17:04:16 -07001314config MODULE_FORCE_LOAD
1315 bool "Forced module loading"
Linus Torvalds826e4502008-05-04 17:04:16 -07001316 default n
1317 help
Rusty Russell91e37a72008-05-09 16:25:28 +10001318 Allow loading of modules without version information (ie. modprobe
1319 --force). Forced module loading sets the 'F' (forced) taint flag and
1320 is usually a really bad idea.
Linus Torvalds826e4502008-05-04 17:04:16 -07001321
Linus Torvalds1da177e2005-04-16 15:20:36 -07001322config MODULE_UNLOAD
1323 bool "Module unloading"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001324 help
1325 Without this option you will not be able to unload any
1326 modules (note that some modules may not be unloadable
Denys Vlasenkof7f5b672008-07-22 19:24:26 -05001327 anyway), which makes your kernel smaller, faster
1328 and simpler. If unsure, say Y.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001329
1330config MODULE_FORCE_UNLOAD
1331 bool "Forced module unloading"
1332 depends on MODULE_UNLOAD && EXPERIMENTAL
1333 help
1334 This option allows you to force a module to unload, even if the
1335 kernel believes it is unsafe: the kernel will remove the module
1336 without waiting for anyone to stop using it (using the -f option to
1337 rmmod). This is mainly for kernel developers and desperate users.
1338 If unsure, say N.
1339
Linus Torvalds1da177e2005-04-16 15:20:36 -07001340config MODVERSIONS
Sam Ravnborg0d541642005-12-26 23:04:02 +01001341 bool "Module versioning support"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001342 help
1343 Usually, you have to use modules compiled with your kernel.
1344 Saying Y here makes it sometimes possible to use modules
1345 compiled for different kernels, by adding enough information
1346 to the modules to (hopefully) spot any changes which would
1347 make them incompatible with the kernel you are running. If
1348 unsure, say N.
1349
1350config MODULE_SRCVERSION_ALL
1351 bool "Source checksum for all modules"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001352 help
1353 Modules which contain a MODULE_VERSION get an extra "srcversion"
1354 field inserted into their modinfo section, which contains a
1355 sum of the source files which made it. This helps maintainers
1356 see exactly which source was used to build a module (since
1357 others sometimes change the module source without updating
1358 the version). With this option, such a "srcversion" field
1359 will be created for all modules. If unsure, say N.
1360
Robert P. J. Day0b0de142008-08-04 13:31:32 -04001361endif # MODULES
1362
Rusty Russell98a79d62008-12-13 21:19:41 +10301363config INIT_ALL_POSSIBLE
1364 bool
1365 help
1366 Back when each arch used to define their own cpu_online_map and
1367 cpu_possible_map, some of them chose to initialize cpu_possible_map
1368 with all 1s, and others with all 0s. When they were centralised,
1369 it was better to provide this option than to break all the archs
Matt LaPlante692105b2009-01-26 11:12:25 +01001370 and have several arch maintainers pursuing me down dark alleys.
Rusty Russell98a79d62008-12-13 21:19:41 +10301371
Linus Torvalds1da177e2005-04-16 15:20:36 -07001372config STOP_MACHINE
1373 bool
1374 default y
1375 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1376 help
1377 Need stop_machine() primitive.
Jens Axboe3a65dfe2005-11-04 08:43:35 +01001378
Jens Axboe3a65dfe2005-11-04 08:43:35 +01001379source "block/Kconfig"
Avi Kivitye98c3202007-10-16 23:27:31 -07001380
1381config PREEMPT_NOTIFIERS
1382 bool
Paul E. McKenneye260be62008-01-25 21:08:24 +01001383
Steffen Klassert16295be2010-01-06 19:47:10 +11001384config PADATA
1385 depends on SMP
1386 bool
1387
Thomas Gleixner6beb0002009-11-09 15:21:34 +00001388source "kernel/Kconfig.locks"