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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 Oberparleiterb99b87f2009-06-17 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54 drivers that have been replaced by something else, and/or are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
72config LOCK_KERNEL
73 bool
Arnd Bergmann6de5bd12010-09-11 18:00:57 +020074 depends on (SMP || PREEMPT) && BKL
Linus Torvalds1da177e2005-04-16 15:20:36 -070075 default y
76
77config INIT_ENV_ARG_LIMIT
78 int
Adrian Bunkdd673bc2006-06-30 01:55:51 -070079 default 32 if !UML
80 default 128 if UML
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 help
Randy Dunlap34ad92c2005-10-30 15:01:46 -080082 Maximum of each of the number of arguments and environment
83 variables passed to init from the kernel command line.
Linus Torvalds1da177e2005-04-16 15:20:36 -070084
Linus Torvalds1da177e2005-04-16 15:20:36 -070085
Roland McGrath84336462009-12-21 16:24:06 -080086config CROSS_COMPILE
87 string "Cross-compiler tool prefix"
88 help
89 Same as running 'make CROSS_COMPILE=prefix-' but stored for
90 default make runs in this kernel build directory. You don't
91 need to set this unless you want the configured kernel build
92 directory to select the cross-compiler automatically.
93
Linus Torvalds1da177e2005-04-16 15:20:36 -070094config LOCALVERSION
95 string "Local version - append to kernel release"
96 help
97 Append an extra string to the end of your kernel version.
98 This will show up when you type uname, for example.
99 The string you set here will be appended after the contents of
100 any files with a filename matching localversion* in your
101 object and source tree, in that order. Your total string can
102 be a maximum of 64 characters.
103
Ryan Andersonaaebf432005-07-31 04:57:49 -0400104config LOCALVERSION_AUTO
105 bool "Automatically append version information to the version string"
106 default y
107 help
108 This will try to automatically determine if the current tree is a
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200109 release tree by looking for git tags that belong to the current
110 top of tree revision.
Ryan Andersonaaebf432005-07-31 04:57:49 -0400111
112 A string of the format -gxxxxxxxx will be added to the localversion
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200113 if a git-based tree is found. The string generated by this will be
Ryan Andersonaaebf432005-07-31 04:57:49 -0400114 appended after any matching localversion* files, and after the value
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200115 set in CONFIG_LOCALVERSION.
Ryan Andersonaaebf432005-07-31 04:57:49 -0400116
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200117 (The actual string used here is the first eight characters produced
118 by running the command:
119
120 $ git rev-parse --verify HEAD
121
122 which is done within the script "scripts/setlocalversion".)
Ryan Andersonaaebf432005-07-31 04:57:49 -0400123
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800124config HAVE_KERNEL_GZIP
125 bool
126
127config HAVE_KERNEL_BZIP2
128 bool
129
130config HAVE_KERNEL_LZMA
131 bool
132
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800133config HAVE_KERNEL_LZO
134 bool
135
Alain Knaff30d65db2009-01-04 22:46:17 +0100136choice
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800137 prompt "Kernel compression mode"
138 default KERNEL_GZIP
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800139 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_LZO
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800140 help
Alain Knaff30d65db2009-01-04 22:46:17 +0100141 The linux kernel is a kind of self-extracting executable.
142 Several compression algorithms are available, which differ
143 in efficiency, compression and decompression speed.
144 Compression speed is only relevant when building a kernel.
145 Decompression speed is relevant at each boot.
146
147 If you have any problems with bzip2 or lzma compressed
148 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
149 version of this functionality (bzip2 only), for 2.4, was
150 supplied by Christian Ludwig)
151
152 High compression options are mostly useful for users, who
153 are low on disk space (embedded systems), but for whom ram
154 size matters less.
155
156 If in doubt, select 'gzip'
157
158config KERNEL_GZIP
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800159 bool "Gzip"
160 depends on HAVE_KERNEL_GZIP
161 help
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800162 The old and tried gzip compression. It provides a good balance
163 between compression ratio and decompression speed.
Alain Knaff30d65db2009-01-04 22:46:17 +0100164
165config KERNEL_BZIP2
166 bool "Bzip2"
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800167 depends on HAVE_KERNEL_BZIP2
Alain Knaff30d65db2009-01-04 22:46:17 +0100168 help
169 Its compression ratio and speed is intermediate.
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800170 Decompression speed is slowest among the three. The kernel
171 size is about 10% smaller with bzip2, in comparison to gzip.
172 Bzip2 uses a large amount of memory. For modern kernels you
173 will need at least 8MB RAM or more for booting.
Alain Knaff30d65db2009-01-04 22:46:17 +0100174
175config KERNEL_LZMA
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800176 bool "LZMA"
177 depends on HAVE_KERNEL_LZMA
178 help
179 The most recent compression algorithm.
180 Its ratio is best, decompression speed is between the other
181 two. Compression is slowest. The kernel size is about 33%
182 smaller with LZMA in comparison to gzip.
Alain Knaff30d65db2009-01-04 22:46:17 +0100183
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800184config KERNEL_LZO
185 bool "LZO"
186 depends on HAVE_KERNEL_LZO
187 help
188 Its compression ratio is the poorest among the 4. The kernel
Stephan Sperber681b3042010-07-14 11:23:08 +0200189 size is about 10% bigger than gzip; however its speed
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800190 (both compression and decompression) is the fastest.
191
Alain Knaff30d65db2009-01-04 22:46:17 +0100192endchoice
193
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194config SWAP
195 bool "Support for paging of anonymous memory (swap)"
David Howells93614012006-09-30 20:45:40 +0200196 depends on MMU && BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197 default y
198 help
199 This option allows you to choose whether you want to have support
Jesper Juhl92c35042006-01-15 02:40:08 +0100200 for so called swap devices or swap files in your kernel that are
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201 used to provide more virtual memory than the actual RAM present
202 in your computer. If unsure say Y.
203
204config SYSVIPC
205 bool "System V IPC"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206 ---help---
207 Inter Process Communication is a suite of library functions and
208 system calls which let processes (running programs) synchronize and
209 exchange information. It is generally considered to be a good thing,
210 and some programs won't run unless you say Y here. In particular, if
211 you want to run the DOS emulator dosemu under Linux (read the
212 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
213 you'll need to say Y here.
214
215 You can find documentation about IPC with "info ipc" and also in
216 section 6.4 of the Linux Programmer's Guide, available from
217 <http://www.tldp.org/guides.html>.
218
Eric W. Biedermana5494dc2007-02-14 00:34:06 -0800219config SYSVIPC_SYSCTL
220 bool
221 depends on SYSVIPC
222 depends on SYSCTL
223 default y
224
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225config POSIX_MQUEUE
226 bool "POSIX Message Queues"
227 depends on NET && EXPERIMENTAL
228 ---help---
229 POSIX variant of message queues is a part of IPC. In POSIX message
230 queues every message has a priority which decides about succession
231 of receiving it by a process. If you want to compile and run
232 programs written e.g. for Solaris with use of its POSIX message
Robert P. J. Dayb0e37652007-05-09 07:25:13 +0200233 queues (functions mq_*) say Y here.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234
235 POSIX message queues are visible as a filesystem called 'mqueue'
236 and can be mounted somewhere if you want to do filesystem
237 operations on message queues.
238
239 If unsure, say Y.
240
Serge E. Hallynbdc8e5f2009-04-06 19:01:11 -0700241config POSIX_MQUEUE_SYSCTL
242 bool
243 depends on POSIX_MQUEUE
244 depends on SYSCTL
245 default y
246
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247config BSD_PROCESS_ACCT
248 bool "BSD Process Accounting"
249 help
250 If you say Y here, a user level program will be able to instruct the
251 kernel (via a special system call) to write process accounting
252 information to a file: whenever a process exits, information about
253 that process will be appended to the file by the kernel. The
254 information includes things such as creation time, owning user,
255 command name, memory usage, controlling terminal etc. (the complete
256 list is in the struct acct in <file:include/linux/acct.h>). It is
257 up to the user level program to do useful things with this
258 information. This is generally a good idea, so say Y.
259
260config BSD_PROCESS_ACCT_V3
261 bool "BSD Process Accounting version 3 file format"
262 depends on BSD_PROCESS_ACCT
263 default n
264 help
265 If you say Y here, the process accounting information is written
266 in a new file format that also logs the process IDs of each
267 process and it's parent. Note that this file format is incompatible
268 with previous v0/v1/v2 file formats, so you will need updated tools
269 for processing it. A preliminary version of these tools is available
S.Çağlar Onur37a4c942008-06-18 11:45:13 +0300270 at <http://www.gnu.org/software/acct/>.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271
Shailabh Nagarc7572492006-07-14 00:24:40 -0700272config TASKSTATS
273 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
274 depends on NET
275 default n
276 help
277 Export selected statistics for tasks/processes through the
278 generic netlink interface. Unlike BSD process accounting, the
279 statistics are available during the lifetime of tasks/processes as
280 responses to commands. Like BSD accounting, they are sent to user
281 space on task exit.
282
283 Say N if unsure.
284
Shailabh Nagarca74e922006-07-14 00:24:36 -0700285config TASK_DELAY_ACCT
286 bool "Enable per-task delay accounting (EXPERIMENTAL)"
Shailabh Nagar6f449932006-07-14 00:24:41 -0700287 depends on TASKSTATS
Shailabh Nagarca74e922006-07-14 00:24:36 -0700288 help
289 Collect information on time spent by a task waiting for system
290 resources like cpu, synchronous block I/O completion and swapping
291 in pages. Such statistics can help in setting a task's priorities
292 relative to other tasks for cpu, io, rss limits etc.
293
294 Say N if unsure.
295
Alexey Dobriyan18f705f2007-02-10 01:46:44 -0800296config TASK_XACCT
297 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
298 depends on TASKSTATS
299 help
300 Collect extended task accounting data and send the data
301 to userland for processing over the taskstats interface.
302
303 Say N if unsure.
304
305config TASK_IO_ACCOUNTING
306 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
307 depends on TASK_XACCT
308 help
309 Collect information on the number of bytes of storage I/O which this
310 task has caused.
311
312 Say N if unsure.
313
Linus Torvalds1da177e2005-04-16 15:20:36 -0700314config AUDIT
315 bool "Auditing support"
Chris Wright804a6a492005-05-11 10:52:45 +0100316 depends on NET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317 help
318 Enable auditing infrastructure that can be used with another
319 kernel subsystem, such as SELinux (which requires this for
320 logging of avc messages output). Does not do system-call
321 auditing without CONFIG_AUDITSYSCALL.
322
323config AUDITSYSCALL
324 bool "Enable system-call auditing support"
Kumar Gala022382a2009-10-16 07:21:37 +0000325 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326 default y if SECURITY_SELINUX
327 help
328 Enable low-overhead system-call auditing infrastructure that
329 can be used independently or with another kernel subsystem,
Eric Paris67640b62009-12-17 20:12:06 -0500330 such as SELinux.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331
Eric Paris939a67f2009-12-17 20:12:06 -0500332config AUDIT_WATCH
333 def_bool y
334 depends on AUDITSYSCALL
335 select FSNOTIFY
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336
Al Viro74c3cbe2007-07-22 08:04:18 -0400337config AUDIT_TREE
338 def_bool y
Eric Paris63c882a2009-05-21 17:02:01 -0400339 depends on AUDITSYSCALL
Eric Paris28a3a7e2009-12-17 20:12:05 -0500340 select FSNOTIFY
Al Viro74c3cbe2007-07-22 08:04:18 -0400341
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000342source "kernel/irq/Kconfig"
343
Mike Travisc903ff82009-01-15 12:28:29 -0800344menu "RCU Subsystem"
345
346choice
347 prompt "RCU Implementation"
Paul E. McKenney31c9a242009-04-02 21:06:25 -0700348 default TREE_RCU
Mike Travisc903ff82009-01-15 12:28:29 -0800349
Mike Travisc903ff82009-01-15 12:28:29 -0800350config TREE_RCU
351 bool "Tree-based hierarchical RCU"
Paul E. McKenney687d7a92010-07-21 06:52:40 -0700352 depends on !PREEMPT && SMP
Mike Travisc903ff82009-01-15 12:28:29 -0800353 help
354 This option selects the RCU implementation that is
355 designed for very large SMP system with hundreds or
Paul E. McKenneyc17ef452009-06-23 17:12:47 -0700356 thousands of CPUs. It also scales down nicely to
357 smaller systems.
Mike Travisc903ff82009-01-15 12:28:29 -0800358
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700359config TREE_PREEMPT_RCU
Paul E. McKenneya57eb942010-06-29 16:49:16 -0700360 bool "Preemptible tree-based hierarchical RCU"
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700361 depends on PREEMPT
362 help
363 This option selects the RCU implementation that is
364 designed for very large SMP systems with hundreds or
365 thousands of CPUs, but for which real-time response
Paul E. McKenneybbe3eae2009-09-13 09:15:08 -0700366 is also required. It also scales down nicely to
367 smaller systems.
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700368
Paul E. McKenney9b1d82f2009-10-25 19:03:50 -0700369config TINY_RCU
370 bool "UP-only small-memory-footprint RCU"
371 depends on !SMP
372 help
373 This option selects the RCU implementation that is
374 designed for UP systems from which real-time response
375 is not required. This option greatly reduces the
376 memory footprint of RCU.
377
Paul E. McKenneya57eb942010-06-29 16:49:16 -0700378config TINY_PREEMPT_RCU
379 bool "Preemptible UP-only small-memory-footprint RCU"
380 depends on !SMP && PREEMPT
381 help
382 This option selects the RCU implementation that is designed
383 for real-time UP systems. This option greatly reduces the
384 memory footprint of RCU.
385
Mike Travisc903ff82009-01-15 12:28:29 -0800386endchoice
387
Paul E. McKenneya57eb942010-06-29 16:49:16 -0700388config PREEMPT_RCU
389 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
390 help
391 This option enables preemptible-RCU code that is common between
392 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
393
Mike Travisc903ff82009-01-15 12:28:29 -0800394config RCU_TRACE
395 bool "Enable tracing for RCU"
Mike Travisc903ff82009-01-15 12:28:29 -0800396 help
397 This option provides tracing in RCU which presents stats
398 in debugfs for debugging RCU implementation.
399
400 Say Y here if you want to enable RCU tracing
401 Say N if you are unsure.
402
403config RCU_FANOUT
404 int "Tree-based hierarchical RCU fanout value"
405 range 2 64 if 64BIT
406 range 2 32 if !64BIT
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700407 depends on TREE_RCU || TREE_PREEMPT_RCU
Mike Travisc903ff82009-01-15 12:28:29 -0800408 default 64 if 64BIT
409 default 32 if !64BIT
410 help
411 This option controls the fanout of hierarchical implementations
412 of RCU, allowing RCU to work efficiently on machines with
Paul E. McKenney4d87ffa2010-08-04 17:31:12 -0700413 large numbers of CPUs. This value must be at least the fourth
414 root of NR_CPUS, which allows NR_CPUS to be insanely large.
415 The default value of RCU_FANOUT should be used for production
416 systems, but if you are stress-testing the RCU implementation
417 itself, small RCU_FANOUT values allow you to test large-system
418 code paths on small(er) systems.
Mike Travisc903ff82009-01-15 12:28:29 -0800419
420 Select a specific number if testing RCU itself.
421 Take the default if unsure.
422
423config RCU_FANOUT_EXACT
424 bool "Disable tree-based hierarchical RCU auto-balancing"
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700425 depends on TREE_RCU || TREE_PREEMPT_RCU
Mike Travisc903ff82009-01-15 12:28:29 -0800426 default n
427 help
428 This option forces use of the exact RCU_FANOUT value specified,
429 regardless of imbalances in the hierarchy. This is useful for
430 testing RCU itself, and might one day be useful on systems with
431 strong NUMA behavior.
432
433 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
434
435 Say N if unsure.
436
Paul E. McKenney8bd93a22010-02-22 17:04:59 -0800437config RCU_FAST_NO_HZ
438 bool "Accelerate last non-dyntick-idle CPU's grace periods"
439 depends on TREE_RCU && NO_HZ && SMP
440 default n
441 help
442 This option causes RCU to attempt to accelerate grace periods
443 in order to allow the final CPU to enter dynticks-idle state
444 more quickly. On the other hand, this option increases the
445 overhead of the dynticks-idle checking, particularly on systems
446 with large numbers of CPUs.
447
448 Say Y if energy efficiency is critically important, particularly
449 if you have relatively few CPUs.
450
451 Say N if you are unsure.
452
Mike Travisc903ff82009-01-15 12:28:29 -0800453config TREE_RCU_TRACE
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700454 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
Mike Travisc903ff82009-01-15 12:28:29 -0800455 select DEBUG_FS
456 help
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700457 This option provides tracing for the TREE_RCU and
458 TREE_PREEMPT_RCU implementations, permitting Makefile to
459 trivially select kernel/rcutree_trace.c.
Mike Travisc903ff82009-01-15 12:28:29 -0800460
Paul E. McKenney24278d12010-09-27 17:25:23 -0700461config RCU_BOOST
462 bool "Enable RCU priority boosting"
463 depends on RT_MUTEXES && TINY_PREEMPT_RCU
464 default n
465 help
466 This option boosts the priority of preempted RCU readers that
467 block the current preemptible RCU grace period for too long.
468 This option also prevents heavy loads from blocking RCU
469 callback invocation for all flavors of RCU.
470
471 Say Y here if you are working with real-time apps or heavy loads
472 Say N here if you are unsure.
473
474config RCU_BOOST_PRIO
475 int "Real-time priority to boost RCU readers to"
476 range 1 99
477 depends on RCU_BOOST
478 default 1
479 help
480 This option specifies the real-time priority to which preempted
481 RCU readers are to be boosted. If you are working with CPU-bound
482 real-time applications, you should specify a priority higher then
483 the highest-priority CPU-bound application.
484
485 Specify the real-time priority, or take the default if unsure.
486
487config RCU_BOOST_DELAY
488 int "Milliseconds to delay boosting after RCU grace-period start"
489 range 0 3000
490 depends on RCU_BOOST
491 default 500
492 help
493 This option specifies the time to wait after the beginning of
494 a given grace period before priority-boosting preempted RCU
495 readers blocking that grace period. Note that any RCU reader
496 blocking an expedited RCU grace period is boosted immediately.
497
498 Accept the default if unsure.
499
Paul E. McKenney46fdb092010-10-26 02:11:40 -0700500config SRCU_SYNCHRONIZE_DELAY
501 int "Microseconds to delay before waiting for readers"
502 range 0 20
503 default 10
504 help
505 This option controls how long SRCU delays before entering its
506 loop waiting on SRCU readers. The purpose of this loop is
507 to avoid the unconditional context-switch penalty that would
508 otherwise be incurred if there was an active SRCU reader,
509 in a manner similar to adaptive locking schemes. This should
510 be set to be a bit longer than the common-case SRCU read-side
511 critical-section overhead.
512
513 Accept the default if unsure.
514
Mike Travisc903ff82009-01-15 12:28:29 -0800515endmenu # "RCU Subsystem"
516
Linus Torvalds1da177e2005-04-16 15:20:36 -0700517config IKCONFIG
Ross Birof2443ab2006-09-30 23:27:25 -0700518 tristate "Kernel .config support"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700519 ---help---
520 This option enables the complete Linux kernel ".config" file
521 contents to be saved in the kernel. It provides documentation
522 of which kernel options are used in a running kernel or in an
523 on-disk kernel. This information can be extracted from the kernel
524 image file with the script scripts/extract-ikconfig and used as
525 input to rebuild the current kernel or to build another kernel.
526 It can also be extracted from a running kernel by reading
527 /proc/config.gz if enabled (below).
528
529config IKCONFIG_PROC
530 bool "Enable access to .config through /proc/config.gz"
531 depends on IKCONFIG && PROC_FS
532 ---help---
533 This option enables access to the kernel configuration file
534 through /proc/config.gz.
535
Alistair John Strachan794543a2007-05-08 00:31:15 -0700536config LOG_BUF_SHIFT
537 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
538 range 12 21
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700539 default 17
Alistair John Strachan794543a2007-05-08 00:31:15 -0700540 help
541 Select kernel log buffer size as a power of 2.
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700542 Examples:
543 17 => 128 KB
544 16 => 64 KB
545 15 => 32 KB
546 14 => 16 KB
Alistair John Strachan794543a2007-05-08 00:31:15 -0700547 13 => 8 KB
548 12 => 4 KB
549
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800550#
551# Architectures with an unreliable sched_clock() should select this:
552#
553config HAVE_UNSTABLE_SCHED_CLOCK
554 bool
555
Li Zefan23964d22009-01-15 13:50:58 -0800556menuconfig CGROUPS
557 boolean "Control Group support"
Kirill A. Shutemov0dea1162010-03-10 15:22:20 -0800558 depends on EVENTFD
Paul Menageddbcc7e2007-10-18 23:39:30 -0700559 help
Li Zefan23964d22009-01-15 13:50:58 -0800560 This option adds support for grouping sets of processes together, for
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800561 use with process control subsystems such as Cpusets, CFS, memory
562 controls or device isolation.
563 See
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800564 - Documentation/scheduler/sched-design-CFS.txt (CFS)
Li Zefan45ce80f2009-01-15 13:50:59 -0800565 - Documentation/cgroups/ (features for grouping, isolation
566 and resource control)
Paul Menageddbcc7e2007-10-18 23:39:30 -0700567
568 Say N if unsure.
569
Li Zefan23964d22009-01-15 13:50:58 -0800570if CGROUPS
571
Paul Menage006cb992007-10-18 23:39:43 -0700572config CGROUP_DEBUG
573 bool "Example debug cgroup subsystem"
Paul Menage418d7d82008-04-29 01:00:05 -0700574 default n
Paul Menage006cb992007-10-18 23:39:43 -0700575 help
576 This option enables a simple cgroup subsystem that
577 exports useful debugging information about the cgroups
Li Zefan23964d22009-01-15 13:50:58 -0800578 framework.
Paul Menage006cb992007-10-18 23:39:43 -0700579
Li Zefan23964d22009-01-15 13:50:58 -0800580 Say N if unsure.
Paul Menage006cb992007-10-18 23:39:43 -0700581
Serge E. Hallyn858d72e2007-10-18 23:39:45 -0700582config CGROUP_NS
Li Zefan23964d22009-01-15 13:50:58 -0800583 bool "Namespace cgroup subsystem"
Li Zefan23964d22009-01-15 13:50:58 -0800584 help
585 Provides a simple namespace cgroup subsystem to
586 provide hierarchical naming of sets of namespaces,
587 for instance virtual servers and checkpoint/restart
588 jobs.
Serge E. Hallyn858d72e2007-10-18 23:39:45 -0700589
Matt Helsleydc52ddc2008-10-18 20:27:21 -0700590config CGROUP_FREEZER
Li Zefan23964d22009-01-15 13:50:58 -0800591 bool "Freezer cgroup subsystem"
Li Zefan23964d22009-01-15 13:50:58 -0800592 help
593 Provides a way to freeze and unfreeze all tasks in a
Matt Helsleydc52ddc2008-10-18 20:27:21 -0700594 cgroup.
595
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700596config CGROUP_DEVICE
597 bool "Device controller for cgroups"
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700598 help
599 Provides a cgroup implementing whitelists for devices which
600 a process in the cgroup can mknod or open.
601
Linus Torvalds1da177e2005-04-16 15:20:36 -0700602config CPUSETS
603 bool "Cpuset support"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700604 help
Randy Dunlapd9fd8a62005-07-27 11:45:11 -0700605 This option will let you create and manage CPUSETs which
Linus Torvalds1da177e2005-04-16 15:20:36 -0700606 allow dynamically partitioning a system into sets of CPUs and
607 Memory Nodes and assigning tasks to run only within those sets.
608 This is primarily useful on large SMP or NUMA systems.
609
610 Say N if unsure.
611
Li Zefan23964d22009-01-15 13:50:58 -0800612config PROC_PID_CPUSET
613 bool "Include legacy /proc/<pid>/cpuset file"
614 depends on CPUSETS
615 default y
616
Srivatsa Vaddagirid842de82007-12-02 20:04:49 +0100617config CGROUP_CPUACCT
618 bool "Simple CPU accounting cgroup subsystem"
Srivatsa Vaddagirid842de82007-12-02 20:04:49 +0100619 help
620 Provides a simple Resource Controller for monitoring the
Li Zefan23964d22009-01-15 13:50:58 -0800621 total CPU consumed by the tasks in a cgroup.
Srivatsa Vaddagirid842de82007-12-02 20:04:49 +0100622
Pavel Emelianove552b662008-02-07 00:13:49 -0800623config RESOURCE_COUNTERS
624 bool "Resource counters"
625 help
626 This option enables controller independent resource accounting
Li Zefan23964d22009-01-15 13:50:58 -0800627 infrastructure that works with cgroups.
Pavel Emelianove552b662008-02-07 00:13:49 -0800628
Balbir Singh00f0b822008-03-04 14:28:39 -0800629config CGROUP_MEM_RES_CTLR
630 bool "Memory Resource Controller for Control Groups"
Daniel Lezcano79ae9c22010-10-27 15:34:39 -0700631 depends on RESOURCE_COUNTERS
Balbir Singhcf475ad2008-04-29 01:00:16 -0700632 select MM_OWNER
Balbir Singh00f0b822008-03-04 14:28:39 -0800633 help
KAMEZAWA Hiroyuki84ad6d72008-10-29 14:01:06 -0700634 Provides a memory resource controller that manages both anonymous
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +0100635 memory and page cache. (See Documentation/cgroups/memory.txt)
Balbir Singh00f0b822008-03-04 14:28:39 -0800636
637 Note that setting this option increases fixed memory overhead
KAMEZAWA Hiroyuki84ad6d72008-10-29 14:01:06 -0700638 associated with each page of memory in the system. By this,
639 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
640 usage tracking struct at boot. Total amount of this is printed out
641 at boot.
Balbir Singh00f0b822008-03-04 14:28:39 -0800642
643 Only enable when you're ok with these trade offs and really
KAMEZAWA Hiroyuki84ad6d72008-10-29 14:01:06 -0700644 sure you need the memory resource controller. Even when you enable
645 this, you can set "cgroup_disable=memory" at your boot option to
646 disable memory resource controller and you can avoid overheads.
Li Zefanc9d54092009-01-07 18:07:35 -0800647 (and lose benefits of memory resource controller)
Balbir Singh00f0b822008-03-04 14:28:39 -0800648
Balbir Singhcf475ad2008-04-29 01:00:16 -0700649 This config option also selects MM_OWNER config option, which
650 could in turn add some fork/exit overhead.
651
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800652config CGROUP_MEM_RES_CTLR_SWAP
KAMEZAWA Hiroyuki65e0e812010-08-10 18:02:56 -0700653 bool "Memory Resource Controller Swap Extension"
654 depends on CGROUP_MEM_RES_CTLR && SWAP
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800655 help
656 Add swap management feature to memory resource controller. When you
657 enable this, you can limit mem+swap usage per cgroup. In other words,
658 when you disable this, memory resource controller has no cares to
659 usage of swap...a process can exhaust all of the swap. This extension
660 is useful when you want to avoid exhaustion swap but this itself
661 adds more overheads and consumes memory for remembering information.
662 Especially if you use 32bit system or small memory system, please
663 be careful about enabling this. When memory resource controller
664 is disabled by boot option, this will be automatically disabled and
665 there will be no overhead from this. Even when you set this config=y,
666 if boot option "noswapaccount" is set, swap will not be accounted.
KAMEZAWA Hiroyuki627991a2009-04-02 16:57:47 -0700667 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
668 size is 4096bytes, 512k per 1Gbytes of swap.
Michal Hockoa42c3902010-11-24 12:57:08 -0800669config CGROUP_MEM_RES_CTLR_SWAP_ENABLED
670 bool "Memory Resource Controller Swap Extension enabled by default"
671 depends on CGROUP_MEM_RES_CTLR_SWAP
672 default y
673 help
674 Memory Resource Controller Swap Extension comes with its price in
675 a bigger memory consumption. General purpose distribution kernels
676 which want to enable the feautre but keep it disabled by default
677 and let the user enable it by swapaccount boot command line
678 parameter should have this option unselected.
679 For those who want to have the feature enabled by default should
680 select this option (if, for some reason, they need to disable it
681 then noswapaccount does the trick).
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800682
Dhaval Giani7c941432010-01-20 13:26:18 +0100683menuconfig CGROUP_SCHED
684 bool "Group CPU scheduler"
Daniel Lezcano79ae9c22010-10-27 15:34:39 -0700685 depends on EXPERIMENTAL
Dhaval Giani7c941432010-01-20 13:26:18 +0100686 default n
687 help
688 This feature lets CPU scheduler recognize task groups and control CPU
689 bandwidth allocation to such task groups. It uses cgroups to group
690 tasks.
691
692if CGROUP_SCHED
693config FAIR_GROUP_SCHED
694 bool "Group scheduling for SCHED_OTHER"
695 depends on CGROUP_SCHED
696 default CGROUP_SCHED
697
698config RT_GROUP_SCHED
699 bool "Group scheduling for SCHED_RR/FIFO"
700 depends on EXPERIMENTAL
701 depends on CGROUP_SCHED
702 default n
703 help
704 This feature lets you explicitly allocate real CPU bandwidth
Li Zefan32bd7eb2010-03-24 13:17:19 +0800705 to task groups. If enabled, it will also make it impossible to
Dhaval Giani7c941432010-01-20 13:26:18 +0100706 schedule realtime tasks for non-root users until you allocate
707 realtime bandwidth for them.
708 See Documentation/scheduler/sched-rt-group.txt for more information.
709
710endif #CGROUP_SCHED
711
Vivek Goyalafc24d42010-04-26 19:27:56 +0200712config BLK_CGROUP
713 tristate "Block IO controller"
Daniel Lezcano79ae9c22010-10-27 15:34:39 -0700714 depends on BLOCK
Vivek Goyalafc24d42010-04-26 19:27:56 +0200715 default n
716 ---help---
717 Generic block IO controller cgroup interface. This is the common
718 cgroup interface which should be used by various IO controlling
719 policies.
720
721 Currently, CFQ IO scheduler uses it to recognize task groups and
722 control disk bandwidth allocation (proportional time slice allocation)
Vivek Goyale43473b2010-09-15 17:06:35 -0400723 to such task groups. It is also used by bio throttling logic in
724 block layer to implement upper limit in IO rates on a device.
Vivek Goyalafc24d42010-04-26 19:27:56 +0200725
726 This option only enables generic Block IO controller infrastructure.
Vivek Goyale43473b2010-09-15 17:06:35 -0400727 One needs to also enable actual IO controlling logic/policy. For
728 enabling proportional weight division of disk bandwidth in CFQ seti
729 CONFIG_CFQ_GROUP_IOSCHED=y and for enabling throttling policy set
730 CONFIG_BLK_THROTTLE=y.
Vivek Goyalafc24d42010-04-26 19:27:56 +0200731
732 See Documentation/cgroups/blkio-controller.txt for more information.
733
734config DEBUG_BLK_CGROUP
735 bool "Enable Block IO controller debugging"
736 depends on BLK_CGROUP
737 default n
738 ---help---
739 Enable some debugging help. Currently it exports additional stat
740 files in a cgroup which can be useful for debugging.
741
Li Zefan23964d22009-01-15 13:50:58 -0800742endif # CGROUPS
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800743
Daniel Lezcano8dd2a822010-10-27 15:34:38 -0700744menuconfig NAMESPACES
Pavel Emelyanovc5289a62008-02-08 04:18:19 -0800745 bool "Namespaces support" if EMBEDDED
746 default !EMBEDDED
747 help
748 Provides the way to make tasks work with different objects using
749 the same id. For example same IPC id may refer to different objects
750 or same user id or pid may refer to different tasks when used in
751 different namespaces.
752
Daniel Lezcano8dd2a822010-10-27 15:34:38 -0700753if NAMESPACES
754
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -0800755config UTS_NS
756 bool "UTS namespace"
Daniel Lezcano17a6d442010-10-27 15:34:37 -0700757 default y
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -0800758 help
759 In this namespace tasks see different info provided with the
760 uname() system call
761
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -0800762config IPC_NS
763 bool "IPC namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -0700764 depends on (SYSVIPC || POSIX_MQUEUE)
Daniel Lezcano17a6d442010-10-27 15:34:37 -0700765 default y
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -0800766 help
767 In this namespace tasks work with IPC ids which correspond to
Serge E. Hallyn614b84c2009-04-06 19:01:08 -0700768 different IPC objects in different namespaces.
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -0800769
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -0800770config USER_NS
771 bool "User namespace (EXPERIMENTAL)"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -0700772 depends on EXPERIMENTAL
Daniel Lezcano17a6d442010-10-27 15:34:37 -0700773 default y
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -0800774 help
775 This allows containers, i.e. vservers, to use user namespaces
776 to provide different user info for different servers.
777 If unsure, say N.
778
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -0800779config PID_NS
Daniel Lezcano9bd38c22010-10-27 15:34:37 -0700780 bool "PID Namespaces"
Daniel Lezcano17a6d442010-10-27 15:34:37 -0700781 default y
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -0800782 help
Heikki Orsila12d2b8f2008-07-06 15:48:02 +0300783 Support process id namespaces. This allows having multiple
Matt LaPlante692105b2009-01-26 11:12:25 +0100784 processes with the same pid as long as they are in different
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -0800785 pid namespaces. This is a building block of containers.
786
Matt Helsleyd6eb6332009-01-26 12:25:55 -0800787config NET_NS
788 bool "Network namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -0700789 depends on NET
Daniel Lezcano17a6d442010-10-27 15:34:37 -0700790 default y
Matt Helsleyd6eb6332009-01-26 12:25:55 -0800791 help
792 Allow user space to create what appear to be multiple instances
793 of the network stack.
794
Daniel Lezcano8dd2a822010-10-27 15:34:38 -0700795endif # NAMESPACES
796
Mike Galbraith5091faa2010-11-30 14:18:03 +0100797config SCHED_AUTOGROUP
798 bool "Automatic process group scheduling"
799 select EVENTFD
800 select CGROUPS
801 select CGROUP_SCHED
802 select FAIR_GROUP_SCHED
803 help
804 This option optimizes the scheduler for common desktop workloads by
805 automatically creating and populating task groups. This separation
806 of workloads isolates aggressive CPU burners (like build jobs) from
807 desktop applications. Task group autogeneration is currently based
808 upon task session.
809
Daniel Lezcano7af37be2010-10-27 15:34:41 -0700810config MM_OWNER
811 bool
812
813config SYSFS_DEPRECATED
814 bool "enable deprecated sysfs features to support old userspace tools"
815 depends on SYSFS
816 default n
817 help
818 This option adds code that switches the layout of the "block" class
819 devices, to not show up in /sys/class/block/, but only in
820 /sys/block/.
821
822 This switch is only active when the sysfs.deprecated=1 boot option is
823 passed or the SYSFS_DEPRECATED_V2 option is set.
824
825 This option allows new kernels to run on old distributions and tools,
826 which might get confused by /sys/class/block/. Since 2007/2008 all
827 major distributions and tools handle this just fine.
828
829 Recent distributions and userspace tools after 2009/2010 depend on
830 the existence of /sys/class/block/, and will not work with this
831 option enabled.
832
833 Only if you are using a new kernel on an old distribution, you might
834 need to say Y here.
835
836config SYSFS_DEPRECATED_V2
837 bool "enabled deprecated sysfs features by default"
838 default n
839 depends on SYSFS
840 depends on SYSFS_DEPRECATED
841 help
842 Enable deprecated sysfs by default.
843
844 See the CONFIG_SYSFS_DEPRECATED option for more details about this
845 option.
846
847 Only if you are using a new kernel on an old distribution, you might
848 need to say Y here. Even then, odds are you would not need it
849 enabled, you can always pass the boot option if absolutely necessary.
850
851config RELAY
852 bool "Kernel->user space relay support (formerly relayfs)"
853 help
854 This option enables support for relay interface support in
855 certain file systems (such as debugfs).
856 It is designed to provide an efficient mechanism for tools and
857 facilities to relay large amounts of data from kernel space to
858 user space.
859
860 If unsure, say N.
861
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -0800862config BLK_DEV_INITRD
863 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
864 depends on BROKEN || !FRV
865 help
866 The initial RAM filesystem is a ramfs which is loaded by the
867 boot loader (loadlin or lilo) and that is mounted as root
868 before the normal boot procedure. It is typically used to
869 load modules needed to mount the "real" root file system,
870 etc. See <file:Documentation/initrd.txt> for details.
871
872 If RAM disk support (BLK_DEV_RAM) is also included, this
873 also enables initial RAM disk (initrd) support and adds
874 15 Kbytes (more on some other architectures) to the kernel size.
875
876 If unsure say Y.
877
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -0800878if BLK_DEV_INITRD
879
Sam Ravnborgdbec4862005-08-10 20:44:50 +0200880source "usr/Kconfig"
881
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -0800882endif
883
Linus Torvaldsc45b4f12005-12-14 18:52:21 -0800884config CC_OPTIMIZE_FOR_SIZE
Ingo Molnar96fffeb2008-04-28 01:39:43 +0200885 bool "Optimize for size"
Linus Torvaldsc45b4f12005-12-14 18:52:21 -0800886 default y
Linus Torvaldsc45b4f12005-12-14 18:52:21 -0800887 help
888 Enabling this option will pass "-Os" instead of "-O2" to gcc
889 resulting in a smaller kernel.
890
jkacur775a7222008-07-16 00:31:16 +0200891 If unsure, say Y.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -0800892
Randy Dunlap08470622006-09-30 23:28:13 -0700893config SYSCTL
894 bool
895
Randy Dunlapb943c462009-03-10 12:55:46 -0700896config ANON_INODES
897 bool
898
Linus Torvalds1da177e2005-04-16 15:20:36 -0700899menuconfig EMBEDDED
900 bool "Configure standard kernel features (for small systems)"
901 help
902 This option allows certain base kernel options and settings
903 to be disabled or tweaked. This is for specialized
904 environments which can tolerate a "non-standard" kernel.
905 Only use this if you really know what you are doing.
906
Chuck Ebbertae81f9e2006-09-16 12:15:53 -0700907config UID16
908 bool "Enable 16-bit UID system calls" if EMBEDDED
David S. Miller09337f52008-04-26 03:17:12 -0700909 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 -0700910 default y
911 help
912 This enables the legacy 16-bit UID syscall wrappers.
913
Eric W. Biedermanb89a8172006-09-27 01:51:04 -0700914config SYSCTL_SYSCALL
Randy Dunlap08470622006-09-30 23:28:13 -0700915 bool "Sysctl syscall support" if EMBEDDED
Eric W. Biederman26a70342009-11-05 05:26:41 -0800916 depends on PROC_SYSCTL
Eric W. Biederman13bb7e32006-11-08 17:44:51 -0800917 default y
Eric W. Biedermanb89a8172006-09-27 01:51:04 -0700918 select SYSCTL
919 ---help---
Eric W. Biederman13bb7e32006-11-08 17:44:51 -0800920 sys_sysctl uses binary paths that have been found challenging
921 to properly maintain and use. The interface in /proc/sys
922 using paths with ascii names is now the primary path to this
923 information.
Eric W. Biedermanb89a8172006-09-27 01:51:04 -0700924
Eric W. Biederman13bb7e32006-11-08 17:44:51 -0800925 Almost nothing using the binary sysctl interface so if you are
926 trying to save some space it is probably safe to disable this,
927 making your kernel marginally smaller.
Eric W. Biedermanb89a8172006-09-27 01:51:04 -0700928
Eric W. Biederman13bb7e32006-11-08 17:44:51 -0800929 If unsure say Y here.
Chuck Ebbertae81f9e2006-09-16 12:15:53 -0700930
Linus Torvalds1da177e2005-04-16 15:20:36 -0700931config KALLSYMS
Jesper Juhl979c6a12006-12-12 19:25:11 +0100932 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
Linus Torvalds1da177e2005-04-16 15:20:36 -0700933 default y
934 help
935 Say Y here to let the kernel print out symbolic crash information and
936 symbolic stack backtraces. This increases the size of the kernel
937 somewhat, as all symbols have to be loaded into the kernel image.
938
939config KALLSYMS_ALL
940 bool "Include all symbols in kallsyms"
941 depends on DEBUG_KERNEL && KALLSYMS
942 help
943 Normally kallsyms only contains the symbols of functions, for nicer
944 OOPS messages. Some debuggers can use kallsyms for other
Jesper Juhlf9f97bc2005-07-20 05:43:05 +0200945 symbols too: say Y here to include all symbols, if you need them
946 and you don't care about adding 300k to the size of your kernel.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700947
948 Say N.
949
950config KALLSYMS_EXTRA_PASS
951 bool "Do an extra kallsyms pass"
952 depends on KALLSYMS
953 help
954 If kallsyms is not working correctly, the build will fail with
955 inconsistent kallsyms data. If that occurs, log a bug report and
956 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
957 Always say N here unless you find a bug in kallsyms, which must be
958 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
959 you wait for kallsyms to be fixed.
960
Matt Mackalld59745c2005-05-01 08:59:02 -0700961
Greg Kroah-Hartman712f47c2005-11-16 11:27:07 -0800962config HOTPLUG
963 bool "Support for hot-pluggable devices" if EMBEDDED
964 default y
965 help
966 This option is provided for the case where no hotplug or uevent
967 capabilities is wanted by the kernel. You should only consider
968 disabling this option for embedded systems that do not use modules, a
969 dynamic /dev tree, or dynamic device discovery. Just say Y.
970
Matt Mackalld59745c2005-05-01 08:59:02 -0700971config PRINTK
972 default y
973 bool "Enable support for printk" if EMBEDDED
974 help
975 This option enables normal printk support. Removing it
976 eliminates most of the message strings from the kernel image
977 and makes the kernel more or less silent. As this makes it
978 very difficult to diagnose system problems, saying N here is
979 strongly discouraged.
980
Matt Mackallc8538a72005-05-01 08:59:01 -0700981config BUG
982 bool "BUG() support" if EMBEDDED
983 default y
984 help
985 Disabling this option eliminates support for BUG and WARN, reducing
986 the size of your kernel image and potentially quietly ignoring
987 numerous fatal conditions. You should only consider disabling this
988 option for embedded systems with no facilities for reporting errors.
989 Just say Y.
990
Matt Mackall708e9a72006-01-08 01:05:25 -0800991config ELF_CORE
992 default y
993 bool "Enable ELF core dumps" if EMBEDDED
994 help
995 Enable support for generating core dumps. Disabling saves about 4k.
996
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +0200997config PCSPKR_PLATFORM
998 bool "Enable PC-Speaker support" if EMBEDDED
999 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
1000 default y
1001 help
1002 This option allows to disable the internal PC-Speaker
1003 support, saving some memory.
1004
Linus Torvalds1da177e2005-04-16 15:20:36 -07001005config BASE_FULL
1006 default y
1007 bool "Enable full-sized data structures for core" if EMBEDDED
1008 help
1009 Disabling this option reduces the size of miscellaneous core
1010 kernel data structures. This saves memory on small machines,
1011 but may reduce performance.
1012
1013config FUTEX
1014 bool "Enable futex support" if EMBEDDED
1015 default y
Ingo Molnar23f78d4a2006-06-27 02:54:53 -07001016 select RT_MUTEXES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001017 help
1018 Disabling this option will cause the kernel to be built without
1019 support for "fast userspace mutexes". The resulting kernel may not
1020 run glibc-based applications correctly.
1021
1022config EPOLL
1023 bool "Enable eventpoll support" if EMBEDDED
1024 default y
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001025 select ANON_INODES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001026 help
1027 Disabling this option will cause the kernel to be built without
1028 support for epoll family of system calls.
1029
Davide Libenzifba2afa2007-05-10 22:23:13 -07001030config SIGNALFD
1031 bool "Enable signalfd() system call" if EMBEDDED
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001032 select ANON_INODES
Davide Libenzifba2afa2007-05-10 22:23:13 -07001033 default y
1034 help
1035 Enable the signalfd() system call that allows to receive signals
1036 on a file descriptor.
1037
1038 If unsure, say Y.
1039
Davide Libenzib215e282007-05-10 22:23:16 -07001040config TIMERFD
1041 bool "Enable timerfd() system call" if EMBEDDED
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001042 select ANON_INODES
Davide Libenzib215e282007-05-10 22:23:16 -07001043 default y
1044 help
1045 Enable the timerfd() system call that allows to receive timer
1046 events on a file descriptor.
1047
1048 If unsure, say Y.
1049
Davide Libenzie1ad7462007-05-10 22:23:19 -07001050config EVENTFD
1051 bool "Enable eventfd() system call" if EMBEDDED
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001052 select ANON_INODES
Davide Libenzie1ad7462007-05-10 22:23:19 -07001053 default y
1054 help
1055 Enable the eventfd() system call that allows to receive both
1056 kernel notification (ie. KAIO) or userspace notifications.
1057
1058 If unsure, say Y.
1059
Linus Torvalds1da177e2005-04-16 15:20:36 -07001060config SHMEM
1061 bool "Use full shmem filesystem" if EMBEDDED
1062 default y
1063 depends on MMU
1064 help
1065 The shmem is an internal filesystem used to manage shared memory.
1066 It is backed by swap and manages resource limits. It is also exported
1067 to userspace as tmpfs if TMPFS is enabled. Disabling this
1068 option replaces shmem and tmpfs with the much simpler ramfs code,
1069 which may be appropriate on small systems without swap.
1070
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001071config AIO
1072 bool "Enable AIO support" if EMBEDDED
1073 default y
1074 help
1075 This option enables POSIX asynchronous I/O which may by used
1076 by some high performance threaded applications. Disabling
1077 this option saves about 7k.
1078
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001079config HAVE_PERF_EVENTS
Thomas Gleixner0793a612008-12-04 20:12:29 +01001080 bool
Mike Frysinger018df722009-06-12 13:17:43 -04001081 help
1082 See tools/perf/design.txt for details.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001083
Peter Zijlstra906010b2009-09-21 16:08:49 +02001084config PERF_USE_VMALLOC
1085 bool
1086 help
1087 See tools/perf/design.txt for details
1088
Ingo Molnar57c0c152009-09-21 12:20:38 +02001089menu "Kernel Performance Events And Counters"
Thomas Gleixner0793a612008-12-04 20:12:29 +01001090
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001091config PERF_EVENTS
Ingo Molnar57c0c152009-09-21 12:20:38 +02001092 bool "Kernel performance events and counters"
1093 default y if (PROFILING || PERF_COUNTERS)
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001094 depends on HAVE_PERF_EVENTS
Ingo Molnar4c59e462008-12-08 19:38:33 +01001095 select ANON_INODES
Peter Zijlstrae360adb2010-10-14 14:01:34 +08001096 select IRQ_WORK
Thomas Gleixner0793a612008-12-04 20:12:29 +01001097 help
Ingo Molnar57c0c152009-09-21 12:20:38 +02001098 Enable kernel support for various performance events provided
1099 by software and hardware.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001100
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001101 Software events are supported either built-in or via the
Ingo Molnar57c0c152009-09-21 12:20:38 +02001102 use of generic tracepoints.
1103
1104 Most modern CPUs support performance events via performance
1105 counter registers. These registers count the number of certain
Thomas Gleixner0793a612008-12-04 20:12:29 +01001106 types of hw events: such as instructions executed, cachemisses
1107 suffered, or branches mis-predicted - without slowing down the
1108 kernel or applications. These registers can also trigger interrupts
1109 when a threshold number of events have passed - and can thus be
1110 used to profile the code that runs on that CPU.
1111
Ingo Molnar57c0c152009-09-21 12:20:38 +02001112 The Linux Performance Event subsystem provides an abstraction of
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001113 these software and hardware event capabilities, available via a
Ingo Molnar57c0c152009-09-21 12:20:38 +02001114 system call and used by the "perf" utility in tools/perf/. It
Thomas Gleixner0793a612008-12-04 20:12:29 +01001115 provides per task and per CPU counters, and it provides event
1116 capabilities on top of those.
1117
1118 Say Y if unsure.
1119
Ingo Molnar57c0c152009-09-21 12:20:38 +02001120config PERF_COUNTERS
1121 bool "Kernel performance counters (old config option)"
1122 depends on HAVE_PERF_EVENTS
1123 help
1124 This config has been obsoleted by the PERF_EVENTS
1125 config option - please see that one for details.
1126
1127 It has no effect on the kernel whether you enable
1128 it or not, it is a compatibility placeholder.
1129
1130 Say N if unsure.
1131
Peter Zijlstra906010b2009-09-21 16:08:49 +02001132config DEBUG_PERF_USE_VMALLOC
1133 default n
1134 bool "Debug: use vmalloc to back perf mmap() buffers"
1135 depends on PERF_EVENTS && DEBUG_KERNEL
1136 select PERF_USE_VMALLOC
1137 help
1138 Use vmalloc memory to back perf mmap() buffers.
1139
1140 Mostly useful for debugging the vmalloc code on platforms
1141 that don't require it.
1142
1143 Say N if unsure.
1144
Thomas Gleixner0793a612008-12-04 20:12:29 +01001145endmenu
1146
Christoph Lameterf8891e52006-06-30 01:55:45 -07001147config VM_EVENT_COUNTERS
1148 default y
1149 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
1150 help
Paul Jackson2aea4fb2006-12-22 01:06:10 -08001151 VM event counters are needed for event counts to be shown.
1152 This option allows the disabling of the VM event counters
1153 on EMBEDDED systems. /proc/vmstat will only show page counts
1154 if VM event counters are disabled.
Christoph Lameterf8891e52006-06-30 01:55:45 -07001155
Thomas Petazzoni3d137312008-08-19 10:28:24 +02001156config PCI_QUIRKS
1157 default y
Geert Uytterhoeven61cfc7e2008-10-22 08:53:25 +02001158 bool "Enable PCI quirk workarounds" if EMBEDDED
1159 depends on PCI
Thomas Petazzoni3d137312008-08-19 10:28:24 +02001160 help
1161 This enables workarounds for various PCI chipset
1162 bugs/quirks. Disable this only if your target machine is
1163 unaffected by PCI quirks.
1164
Christoph Lameter41ecc552007-05-09 02:32:44 -07001165config SLUB_DEBUG
1166 default y
1167 bool "Enable SLUB debugging support" if EMBEDDED
Christoph Lameterf6acb632008-04-29 16:16:06 -07001168 depends on SLUB && SYSFS
Christoph Lameter41ecc552007-05-09 02:32:44 -07001169 help
1170 SLUB has extensive debug support features. Disabling these can
1171 result in significant savings in code size. This also disables
1172 SLUB sysfs support. /sys/slab will not exist and there will be
1173 no support for cache validation etc.
1174
Randy Dunlapb943c462009-03-10 12:55:46 -07001175config COMPAT_BRK
1176 bool "Disable heap randomization"
1177 default y
1178 help
1179 Randomizing heap placement makes heap exploits harder, but it
1180 also breaks ancient binaries (including anything libc5 based).
1181 This option changes the bootup default to heap randomization
Matt LaPlante692105b2009-01-26 11:12:25 +01001182 disabled, and can be overridden at runtime by setting
Randy Dunlapb943c462009-03-10 12:55:46 -07001183 /proc/sys/kernel/randomize_va_space to 2.
1184
1185 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1186
Christoph Lameter81819f02007-05-06 14:49:36 -07001187choice
1188 prompt "Choose SLAB allocator"
Christoph Lametera0acd822007-07-17 04:03:32 -07001189 default SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -07001190 help
1191 This option allows to select a slab allocator.
1192
1193config SLAB
1194 bool "SLAB"
1195 help
1196 The regular slab allocator that is established and known to work
Christoph Lameter34013882007-05-09 02:32:47 -07001197 well in all environments. It organizes cache hot objects in
Simon Arlott02f56212008-11-05 22:18:19 +00001198 per cpu and per node queues.
Christoph Lameter81819f02007-05-06 14:49:36 -07001199
1200config SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -07001201 bool "SLUB (Unqueued Allocator)"
1202 help
1203 SLUB is a slab allocator that minimizes cache line usage
1204 instead of managing queues of cached objects (SLAB approach).
1205 Per cpu caching is realized using slabs of objects instead
1206 of queues of objects. SLUB can use memory efficiently
Simon Arlott02f56212008-11-05 22:18:19 +00001207 and has enhanced diagnostics. SLUB is the default choice for
1208 a slab allocator.
Christoph Lameter81819f02007-05-06 14:49:36 -07001209
1210config SLOB
Paul Mundt84a01c22007-07-15 23:38:24 -07001211 depends on EMBEDDED
Christoph Lameter81819f02007-05-06 14:49:36 -07001212 bool "SLOB (Simple Allocator)"
1213 help
Matt Mackall37291452008-02-04 22:29:38 -08001214 SLOB replaces the stock allocator with a drastically simpler
1215 allocator. SLOB is generally more space efficient but
1216 does not perform as well on large systems.
Christoph Lameter81819f02007-05-06 14:49:36 -07001217
1218endchoice
1219
Jie Zhangea637632009-12-14 18:00:02 -08001220config MMAP_ALLOW_UNINITIALIZED
1221 bool "Allow mmapped anonymous memory to be uninitialized"
1222 depends on EMBEDDED && !MMU
1223 default n
1224 help
1225 Normally, and according to the Linux spec, anonymous memory obtained
1226 from mmap() has it's contents cleared before it is passed to
1227 userspace. Enabling this config option allows you to request that
1228 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1229 providing a huge performance boost. If this option is not enabled,
1230 then the flag will be ignored.
1231
1232 This is taken advantage of by uClibc's malloc(), and also by
1233 ELF-FDPIC binfmt's brk and stack allocator.
1234
1235 Because of the obvious security issues, this option should only be
1236 enabled on embedded devices where you control what is run in
1237 userspace. Since that isn't generally a problem on no-MMU systems,
1238 it is normally safe to say Y here.
1239
1240 See Documentation/nommu-mmap.txt for more information.
1241
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001242config PROFILING
Robert Richterb309a292010-02-26 15:01:23 +01001243 bool "Profiling support"
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001244 help
1245 Say Y here to enable the extended profiling support mechanisms used
1246 by profilers such as OProfile.
1247
Ingo Molnar5f87f112008-07-23 14:15:22 +02001248#
1249# Place an empty function call at each tracepoint site. Can be
1250# dynamically changed for a probe function.
1251#
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001252config TRACEPOINTS
Ingo Molnar5f87f112008-07-23 14:15:22 +02001253 bool
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001254
Mathieu Desnoyersfb32e032008-02-02 15:10:33 -05001255source "arch/Kconfig"
1256
Linus Torvalds1da177e2005-04-16 15:20:36 -07001257endmenu # General setup
1258
Dmitry Baryshkovee7e5512008-06-29 14:18:46 +04001259config HAVE_GENERIC_DMA_COHERENT
1260 bool
1261 default n
1262
Linus Torvalds158a9622008-01-02 13:04:48 -08001263config SLABINFO
1264 bool
1265 depends on PROC_FS
Christoph Lameter0f389ec2008-04-14 18:53:02 +03001266 depends on SLAB || SLUB_DEBUG
Linus Torvalds158a9622008-01-02 13:04:48 -08001267 default y
1268
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001269config RT_MUTEXES
1270 boolean
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001271
Linus Torvalds1da177e2005-04-16 15:20:36 -07001272config BASE_SMALL
1273 int
1274 default 0 if BASE_FULL
1275 default 1 if !BASE_FULL
1276
Jan Engelhardt66da5732007-07-15 23:39:29 -07001277menuconfig MODULES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001278 bool "Enable loadable module support"
1279 help
1280 Kernel modules are small pieces of compiled code which can
1281 be inserted in the running kernel, rather than being
1282 permanently built into the kernel. You use the "modprobe"
1283 tool to add (and sometimes remove) them. If you say Y here,
1284 many parts of the kernel can be built as modules (by
1285 answering M instead of Y where indicated): this is most
1286 useful for infrequently used options which are not required
1287 for booting. For more information, see the man pages for
1288 modprobe, lsmod, modinfo, insmod and rmmod.
1289
1290 If you say Y here, you will need to run "make
1291 modules_install" to put the modules under /lib/modules/
1292 where modprobe can find them (you may need to be root to do
1293 this).
1294
1295 If unsure, say Y.
1296
Robert P. J. Day0b0de142008-08-04 13:31:32 -04001297if MODULES
1298
Linus Torvalds826e4502008-05-04 17:04:16 -07001299config MODULE_FORCE_LOAD
1300 bool "Forced module loading"
Linus Torvalds826e4502008-05-04 17:04:16 -07001301 default n
1302 help
Rusty Russell91e37a72008-05-09 16:25:28 +10001303 Allow loading of modules without version information (ie. modprobe
1304 --force). Forced module loading sets the 'F' (forced) taint flag and
1305 is usually a really bad idea.
Linus Torvalds826e4502008-05-04 17:04:16 -07001306
Linus Torvalds1da177e2005-04-16 15:20:36 -07001307config MODULE_UNLOAD
1308 bool "Module unloading"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001309 help
1310 Without this option you will not be able to unload any
1311 modules (note that some modules may not be unloadable
Denys Vlasenkof7f5b672008-07-22 19:24:26 -05001312 anyway), which makes your kernel smaller, faster
1313 and simpler. If unsure, say Y.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001314
1315config MODULE_FORCE_UNLOAD
1316 bool "Forced module unloading"
1317 depends on MODULE_UNLOAD && EXPERIMENTAL
1318 help
1319 This option allows you to force a module to unload, even if the
1320 kernel believes it is unsafe: the kernel will remove the module
1321 without waiting for anyone to stop using it (using the -f option to
1322 rmmod). This is mainly for kernel developers and desperate users.
1323 If unsure, say N.
1324
Linus Torvalds1da177e2005-04-16 15:20:36 -07001325config MODVERSIONS
Sam Ravnborg0d541642005-12-26 23:04:02 +01001326 bool "Module versioning support"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001327 help
1328 Usually, you have to use modules compiled with your kernel.
1329 Saying Y here makes it sometimes possible to use modules
1330 compiled for different kernels, by adding enough information
1331 to the modules to (hopefully) spot any changes which would
1332 make them incompatible with the kernel you are running. If
1333 unsure, say N.
1334
1335config MODULE_SRCVERSION_ALL
1336 bool "Source checksum for all modules"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001337 help
1338 Modules which contain a MODULE_VERSION get an extra "srcversion"
1339 field inserted into their modinfo section, which contains a
1340 sum of the source files which made it. This helps maintainers
1341 see exactly which source was used to build a module (since
1342 others sometimes change the module source without updating
1343 the version). With this option, such a "srcversion" field
1344 will be created for all modules. If unsure, say N.
1345
Robert P. J. Day0b0de142008-08-04 13:31:32 -04001346endif # MODULES
1347
Rusty Russell98a79d62008-12-13 21:19:41 +10301348config INIT_ALL_POSSIBLE
1349 bool
1350 help
1351 Back when each arch used to define their own cpu_online_map and
1352 cpu_possible_map, some of them chose to initialize cpu_possible_map
1353 with all 1s, and others with all 0s. When they were centralised,
1354 it was better to provide this option than to break all the archs
Matt LaPlante692105b2009-01-26 11:12:25 +01001355 and have several arch maintainers pursuing me down dark alleys.
Rusty Russell98a79d62008-12-13 21:19:41 +10301356
Linus Torvalds1da177e2005-04-16 15:20:36 -07001357config STOP_MACHINE
1358 bool
1359 default y
1360 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1361 help
1362 Need stop_machine() primitive.
Jens Axboe3a65dfe2005-11-04 08:43:35 +01001363
Jens Axboe3a65dfe2005-11-04 08:43:35 +01001364source "block/Kconfig"
Avi Kivitye98c3202007-10-16 23:27:31 -07001365
1366config PREEMPT_NOTIFIERS
1367 bool
Paul E. McKenneye260be62008-01-25 21:08:24 +01001368
Steffen Klassert16295be2010-01-06 19:47:10 +11001369config PADATA
1370 depends on SMP
1371 bool
1372
Thomas Gleixner6beb0002009-11-09 15:21:34 +00001373source "kernel/Kconfig.locks"