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Roman Zippel80daa562008-01-14 04:51:16 +01001config ARCH
2 string
3 option env="ARCH"
4
5config KERNELVERSION
6 string
7 option env="KERNELVERSION"
8
Roman Zippelface4372006-06-08 22:12:45 -07009config DEFCONFIG_LIST
10 string
Paolo 'Blaisorblade' Giarrussob2670ea2006-10-19 23:28:23 -070011 depends on !UML
Roman Zippelface4372006-06-08 22:12:45 -070012 option defconfig_list
13 default "/lib/modules/$UNAME_RELEASE/.config"
14 default "/etc/kernel-config"
15 default "/boot/config-$UNAME_RELEASE"
Sam Ravnborg73531902008-05-25 23:03:18 +020016 default "$ARCH_DEFCONFIG"
Roman Zippelface4372006-06-08 22:12:45 -070017 default "arch/$ARCH/defconfig"
18
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54 drivers that have been replaced by something else, and/or are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
Lasse Collin3ebe1242011-01-12 17:01:23 -0800133config HAVE_KERNEL_XZ
134 bool
135
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800136config HAVE_KERNEL_LZO
137 bool
138
Alain Knaff30d65db2009-01-04 22:46:17 +0100139choice
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800140 prompt "Kernel compression mode"
141 default KERNEL_GZIP
Lasse Collin3ebe1242011-01-12 17:01:23 -0800142 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 -0800143 help
Alain Knaff30d65db2009-01-04 22:46:17 +0100144 The linux kernel is a kind of self-extracting executable.
145 Several compression algorithms are available, which differ
146 in efficiency, compression and decompression speed.
147 Compression speed is only relevant when building a kernel.
148 Decompression speed is relevant at each boot.
149
150 If you have any problems with bzip2 or lzma compressed
151 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
152 version of this functionality (bzip2 only), for 2.4, was
153 supplied by Christian Ludwig)
154
155 High compression options are mostly useful for users, who
156 are low on disk space (embedded systems), but for whom ram
157 size matters less.
158
159 If in doubt, select 'gzip'
160
161config KERNEL_GZIP
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800162 bool "Gzip"
163 depends on HAVE_KERNEL_GZIP
164 help
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800165 The old and tried gzip compression. It provides a good balance
166 between compression ratio and decompression speed.
Alain Knaff30d65db2009-01-04 22:46:17 +0100167
168config KERNEL_BZIP2
169 bool "Bzip2"
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800170 depends on HAVE_KERNEL_BZIP2
Alain Knaff30d65db2009-01-04 22:46:17 +0100171 help
172 Its compression ratio and speed is intermediate.
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800173 Decompression speed is slowest among the three. The kernel
174 size is about 10% smaller with bzip2, in comparison to gzip.
175 Bzip2 uses a large amount of memory. For modern kernels you
176 will need at least 8MB RAM or more for booting.
Alain Knaff30d65db2009-01-04 22:46:17 +0100177
178config KERNEL_LZMA
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800179 bool "LZMA"
180 depends on HAVE_KERNEL_LZMA
181 help
182 The most recent compression algorithm.
183 Its ratio is best, decompression speed is between the other
184 two. Compression is slowest. The kernel size is about 33%
185 smaller with LZMA in comparison to gzip.
Alain Knaff30d65db2009-01-04 22:46:17 +0100186
Lasse Collin3ebe1242011-01-12 17:01:23 -0800187config KERNEL_XZ
188 bool "XZ"
189 depends on HAVE_KERNEL_XZ
190 help
191 XZ uses the LZMA2 algorithm and instruction set specific
192 BCJ filters which can improve compression ratio of executable
193 code. The size of the kernel is about 30% smaller with XZ in
194 comparison to gzip. On architectures for which there is a BCJ
195 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
196 will create a few percent smaller kernel than plain LZMA.
197
198 The speed is about the same as with LZMA: The decompression
199 speed of XZ is better than that of bzip2 but worse than gzip
200 and LZO. Compression is slow.
201
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800202config KERNEL_LZO
203 bool "LZO"
204 depends on HAVE_KERNEL_LZO
205 help
206 Its compression ratio is the poorest among the 4. The kernel
Stephan Sperber681b3042010-07-14 11:23:08 +0200207 size is about 10% bigger than gzip; however its speed
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800208 (both compression and decompression) is the fastest.
209
Alain Knaff30d65db2009-01-04 22:46:17 +0100210endchoice
211
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212config SWAP
213 bool "Support for paging of anonymous memory (swap)"
David Howells93614012006-09-30 20:45:40 +0200214 depends on MMU && BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215 default y
216 help
217 This option allows you to choose whether you want to have support
Jesper Juhl92c35042006-01-15 02:40:08 +0100218 for so called swap devices or swap files in your kernel that are
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219 used to provide more virtual memory than the actual RAM present
220 in your computer. If unsure say Y.
221
222config SYSVIPC
223 bool "System V IPC"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224 ---help---
225 Inter Process Communication is a suite of library functions and
226 system calls which let processes (running programs) synchronize and
227 exchange information. It is generally considered to be a good thing,
228 and some programs won't run unless you say Y here. In particular, if
229 you want to run the DOS emulator dosemu under Linux (read the
230 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
231 you'll need to say Y here.
232
233 You can find documentation about IPC with "info ipc" and also in
234 section 6.4 of the Linux Programmer's Guide, available from
235 <http://www.tldp.org/guides.html>.
236
Eric W. Biedermana5494dc2007-02-14 00:34:06 -0800237config SYSVIPC_SYSCTL
238 bool
239 depends on SYSVIPC
240 depends on SYSCTL
241 default y
242
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243config POSIX_MQUEUE
244 bool "POSIX Message Queues"
245 depends on NET && EXPERIMENTAL
246 ---help---
247 POSIX variant of message queues is a part of IPC. In POSIX message
248 queues every message has a priority which decides about succession
249 of receiving it by a process. If you want to compile and run
250 programs written e.g. for Solaris with use of its POSIX message
Robert P. J. Dayb0e37652007-05-09 07:25:13 +0200251 queues (functions mq_*) say Y here.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700252
253 POSIX message queues are visible as a filesystem called 'mqueue'
254 and can be mounted somewhere if you want to do filesystem
255 operations on message queues.
256
257 If unsure, say Y.
258
Serge E. Hallynbdc8e5f2009-04-06 19:01:11 -0700259config POSIX_MQUEUE_SYSCTL
260 bool
261 depends on POSIX_MQUEUE
262 depends on SYSCTL
263 default y
264
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265config BSD_PROCESS_ACCT
266 bool "BSD Process Accounting"
267 help
268 If you say Y here, a user level program will be able to instruct the
269 kernel (via a special system call) to write process accounting
270 information to a file: whenever a process exits, information about
271 that process will be appended to the file by the kernel. The
272 information includes things such as creation time, owning user,
273 command name, memory usage, controlling terminal etc. (the complete
274 list is in the struct acct in <file:include/linux/acct.h>). It is
275 up to the user level program to do useful things with this
276 information. This is generally a good idea, so say Y.
277
278config BSD_PROCESS_ACCT_V3
279 bool "BSD Process Accounting version 3 file format"
280 depends on BSD_PROCESS_ACCT
281 default n
282 help
283 If you say Y here, the process accounting information is written
284 in a new file format that also logs the process IDs of each
285 process and it's parent. Note that this file format is incompatible
286 with previous v0/v1/v2 file formats, so you will need updated tools
287 for processing it. A preliminary version of these tools is available
S.Çağlar Onur37a4c942008-06-18 11:45:13 +0300288 at <http://www.gnu.org/software/acct/>.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289
Shailabh Nagarc7572492006-07-14 00:24:40 -0700290config TASKSTATS
291 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
292 depends on NET
293 default n
294 help
295 Export selected statistics for tasks/processes through the
296 generic netlink interface. Unlike BSD process accounting, the
297 statistics are available during the lifetime of tasks/processes as
298 responses to commands. Like BSD accounting, they are sent to user
299 space on task exit.
300
301 Say N if unsure.
302
Shailabh Nagarca74e922006-07-14 00:24:36 -0700303config TASK_DELAY_ACCT
304 bool "Enable per-task delay accounting (EXPERIMENTAL)"
Shailabh Nagar6f449932006-07-14 00:24:41 -0700305 depends on TASKSTATS
Shailabh Nagarca74e922006-07-14 00:24:36 -0700306 help
307 Collect information on time spent by a task waiting for system
308 resources like cpu, synchronous block I/O completion and swapping
309 in pages. Such statistics can help in setting a task's priorities
310 relative to other tasks for cpu, io, rss limits etc.
311
312 Say N if unsure.
313
Alexey Dobriyan18f705f2007-02-10 01:46:44 -0800314config TASK_XACCT
315 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
316 depends on TASKSTATS
317 help
318 Collect extended task accounting data and send the data
319 to userland for processing over the taskstats interface.
320
321 Say N if unsure.
322
323config TASK_IO_ACCOUNTING
324 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
325 depends on TASK_XACCT
326 help
327 Collect information on the number of bytes of storage I/O which this
328 task has caused.
329
330 Say N if unsure.
331
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332config AUDIT
333 bool "Auditing support"
Chris Wright804a6a42005-05-11 10:52:45 +0100334 depends on NET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335 help
336 Enable auditing infrastructure that can be used with another
337 kernel subsystem, such as SELinux (which requires this for
338 logging of avc messages output). Does not do system-call
339 auditing without CONFIG_AUDITSYSCALL.
340
341config AUDITSYSCALL
342 bool "Enable system-call auditing support"
Kumar Gala022382a2009-10-16 07:21:37 +0000343 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344 default y if SECURITY_SELINUX
345 help
346 Enable low-overhead system-call auditing infrastructure that
347 can be used independently or with another kernel subsystem,
Eric Paris67640b62009-12-17 20:12:06 -0500348 such as SELinux.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349
Eric Paris939a67f2009-12-17 20:12:06 -0500350config AUDIT_WATCH
351 def_bool y
352 depends on AUDITSYSCALL
353 select FSNOTIFY
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354
Al Viro74c3cbe2007-07-22 08:04:18 -0400355config AUDIT_TREE
356 def_bool y
Eric Paris63c882a2009-05-21 17:02:01 -0400357 depends on AUDITSYSCALL
Eric Paris28a3a7e2009-12-17 20:12:05 -0500358 select FSNOTIFY
Al Viro74c3cbe2007-07-22 08:04:18 -0400359
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000360source "kernel/irq/Kconfig"
361
Mike Travisc903ff82009-01-15 12:28:29 -0800362menu "RCU Subsystem"
363
364choice
365 prompt "RCU Implementation"
Paul E. McKenney31c9a242009-04-02 21:06:25 -0700366 default TREE_RCU
Mike Travisc903ff82009-01-15 12:28:29 -0800367
Mike Travisc903ff82009-01-15 12:28:29 -0800368config TREE_RCU
369 bool "Tree-based hierarchical RCU"
Paul E. McKenney687d7a92010-07-21 06:52:40 -0700370 depends on !PREEMPT && SMP
Mike Travisc903ff82009-01-15 12:28:29 -0800371 help
372 This option selects the RCU implementation that is
373 designed for very large SMP system with hundreds or
Paul E. McKenneyc17ef452009-06-23 17:12:47 -0700374 thousands of CPUs. It also scales down nicely to
375 smaller systems.
Mike Travisc903ff82009-01-15 12:28:29 -0800376
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700377config TREE_PREEMPT_RCU
Paul E. McKenneya57eb942010-06-29 16:49:16 -0700378 bool "Preemptible tree-based hierarchical RCU"
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700379 depends on PREEMPT
380 help
381 This option selects the RCU implementation that is
382 designed for very large SMP systems with hundreds or
383 thousands of CPUs, but for which real-time response
Paul E. McKenneybbe3eae2009-09-13 09:15:08 -0700384 is also required. It also scales down nicely to
385 smaller systems.
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700386
Paul E. McKenney9b1d82f2009-10-25 19:03:50 -0700387config TINY_RCU
388 bool "UP-only small-memory-footprint RCU"
389 depends on !SMP
390 help
391 This option selects the RCU implementation that is
392 designed for UP systems from which real-time response
393 is not required. This option greatly reduces the
394 memory footprint of RCU.
395
Paul E. McKenneya57eb942010-06-29 16:49:16 -0700396config TINY_PREEMPT_RCU
397 bool "Preemptible UP-only small-memory-footprint RCU"
398 depends on !SMP && PREEMPT
399 help
400 This option selects the RCU implementation that is designed
401 for real-time UP systems. This option greatly reduces the
402 memory footprint of RCU.
403
Mike Travisc903ff82009-01-15 12:28:29 -0800404endchoice
405
Paul E. McKenneya57eb942010-06-29 16:49:16 -0700406config PREEMPT_RCU
407 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
408 help
409 This option enables preemptible-RCU code that is common between
410 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
411
Mike Travisc903ff82009-01-15 12:28:29 -0800412config RCU_TRACE
413 bool "Enable tracing for RCU"
Mike Travisc903ff82009-01-15 12:28:29 -0800414 help
415 This option provides tracing in RCU which presents stats
416 in debugfs for debugging RCU implementation.
417
418 Say Y here if you want to enable RCU tracing
419 Say N if you are unsure.
420
421config RCU_FANOUT
422 int "Tree-based hierarchical RCU fanout value"
423 range 2 64 if 64BIT
424 range 2 32 if !64BIT
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 64 if 64BIT
427 default 32 if !64BIT
428 help
429 This option controls the fanout of hierarchical implementations
430 of RCU, allowing RCU to work efficiently on machines with
Paul E. McKenney4d87ffa2010-08-04 17:31:12 -0700431 large numbers of CPUs. This value must be at least the fourth
432 root of NR_CPUS, which allows NR_CPUS to be insanely large.
433 The default value of RCU_FANOUT should be used for production
434 systems, but if you are stress-testing the RCU implementation
435 itself, small RCU_FANOUT values allow you to test large-system
436 code paths on small(er) systems.
Mike Travisc903ff82009-01-15 12:28:29 -0800437
438 Select a specific number if testing RCU itself.
439 Take the default if unsure.
440
441config RCU_FANOUT_EXACT
442 bool "Disable tree-based hierarchical RCU auto-balancing"
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700443 depends on TREE_RCU || TREE_PREEMPT_RCU
Mike Travisc903ff82009-01-15 12:28:29 -0800444 default n
445 help
446 This option forces use of the exact RCU_FANOUT value specified,
447 regardless of imbalances in the hierarchy. This is useful for
448 testing RCU itself, and might one day be useful on systems with
449 strong NUMA behavior.
450
451 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
452
453 Say N if unsure.
454
Paul E. McKenney8bd93a22010-02-22 17:04:59 -0800455config RCU_FAST_NO_HZ
456 bool "Accelerate last non-dyntick-idle CPU's grace periods"
457 depends on TREE_RCU && NO_HZ && SMP
458 default n
459 help
460 This option causes RCU to attempt to accelerate grace periods
461 in order to allow the final CPU to enter dynticks-idle state
462 more quickly. On the other hand, this option increases the
463 overhead of the dynticks-idle checking, particularly on systems
464 with large numbers of CPUs.
465
466 Say Y if energy efficiency is critically important, particularly
467 if you have relatively few CPUs.
468
469 Say N if you are unsure.
470
Mike Travisc903ff82009-01-15 12:28:29 -0800471config TREE_RCU_TRACE
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700472 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
Mike Travisc903ff82009-01-15 12:28:29 -0800473 select DEBUG_FS
474 help
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700475 This option provides tracing for the TREE_RCU and
476 TREE_PREEMPT_RCU implementations, permitting Makefile to
477 trivially select kernel/rcutree_trace.c.
Mike Travisc903ff82009-01-15 12:28:29 -0800478
Paul E. McKenney24278d12010-09-27 17:25:23 -0700479config RCU_BOOST
480 bool "Enable RCU priority boosting"
481 depends on RT_MUTEXES && TINY_PREEMPT_RCU
482 default n
483 help
484 This option boosts the priority of preempted RCU readers that
485 block the current preemptible RCU grace period for too long.
486 This option also prevents heavy loads from blocking RCU
487 callback invocation for all flavors of RCU.
488
489 Say Y here if you are working with real-time apps or heavy loads
490 Say N here if you are unsure.
491
492config RCU_BOOST_PRIO
493 int "Real-time priority to boost RCU readers to"
494 range 1 99
495 depends on RCU_BOOST
496 default 1
497 help
498 This option specifies the real-time priority to which preempted
499 RCU readers are to be boosted. If you are working with CPU-bound
500 real-time applications, you should specify a priority higher then
501 the highest-priority CPU-bound application.
502
503 Specify the real-time priority, or take the default if unsure.
504
505config RCU_BOOST_DELAY
506 int "Milliseconds to delay boosting after RCU grace-period start"
507 range 0 3000
508 depends on RCU_BOOST
509 default 500
510 help
511 This option specifies the time to wait after the beginning of
512 a given grace period before priority-boosting preempted RCU
513 readers blocking that grace period. Note that any RCU reader
514 blocking an expedited RCU grace period is boosted immediately.
515
516 Accept the default if unsure.
517
Paul E. McKenney46fdb092010-10-26 02:11:40 -0700518config SRCU_SYNCHRONIZE_DELAY
519 int "Microseconds to delay before waiting for readers"
520 range 0 20
521 default 10
522 help
523 This option controls how long SRCU delays before entering its
524 loop waiting on SRCU readers. The purpose of this loop is
525 to avoid the unconditional context-switch penalty that would
526 otherwise be incurred if there was an active SRCU reader,
527 in a manner similar to adaptive locking schemes. This should
528 be set to be a bit longer than the common-case SRCU read-side
529 critical-section overhead.
530
531 Accept the default if unsure.
532
Mike Travisc903ff82009-01-15 12:28:29 -0800533endmenu # "RCU Subsystem"
534
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535config IKCONFIG
Ross Birof2443ab2006-09-30 23:27:25 -0700536 tristate "Kernel .config support"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700537 ---help---
538 This option enables the complete Linux kernel ".config" file
539 contents to be saved in the kernel. It provides documentation
540 of which kernel options are used in a running kernel or in an
541 on-disk kernel. This information can be extracted from the kernel
542 image file with the script scripts/extract-ikconfig and used as
543 input to rebuild the current kernel or to build another kernel.
544 It can also be extracted from a running kernel by reading
545 /proc/config.gz if enabled (below).
546
547config IKCONFIG_PROC
548 bool "Enable access to .config through /proc/config.gz"
549 depends on IKCONFIG && PROC_FS
550 ---help---
551 This option enables access to the kernel configuration file
552 through /proc/config.gz.
553
Alistair John Strachan794543a2007-05-08 00:31:15 -0700554config LOG_BUF_SHIFT
555 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
556 range 12 21
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700557 default 17
Alistair John Strachan794543a2007-05-08 00:31:15 -0700558 help
559 Select kernel log buffer size as a power of 2.
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700560 Examples:
561 17 => 128 KB
562 16 => 64 KB
563 15 => 32 KB
564 14 => 16 KB
Alistair John Strachan794543a2007-05-08 00:31:15 -0700565 13 => 8 KB
566 12 => 4 KB
567
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800568#
569# Architectures with an unreliable sched_clock() should select this:
570#
571config HAVE_UNSTABLE_SCHED_CLOCK
572 bool
573
Li Zefan23964d22009-01-15 13:50:58 -0800574menuconfig CGROUPS
575 boolean "Control Group support"
Kirill A. Shutemov0dea1162010-03-10 15:22:20 -0800576 depends on EVENTFD
Paul Menageddbcc7e2007-10-18 23:39:30 -0700577 help
Li Zefan23964d22009-01-15 13:50:58 -0800578 This option adds support for grouping sets of processes together, for
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800579 use with process control subsystems such as Cpusets, CFS, memory
580 controls or device isolation.
581 See
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800582 - Documentation/scheduler/sched-design-CFS.txt (CFS)
Li Zefan45ce80f2009-01-15 13:50:59 -0800583 - Documentation/cgroups/ (features for grouping, isolation
584 and resource control)
Paul Menageddbcc7e2007-10-18 23:39:30 -0700585
586 Say N if unsure.
587
Li Zefan23964d22009-01-15 13:50:58 -0800588if CGROUPS
589
Paul Menage006cb992007-10-18 23:39:43 -0700590config CGROUP_DEBUG
591 bool "Example debug cgroup subsystem"
Paul Menage418d7d82008-04-29 01:00:05 -0700592 default n
Paul Menage006cb992007-10-18 23:39:43 -0700593 help
594 This option enables a simple cgroup subsystem that
595 exports useful debugging information about the cgroups
Li Zefan23964d22009-01-15 13:50:58 -0800596 framework.
Paul Menage006cb992007-10-18 23:39:43 -0700597
Li Zefan23964d22009-01-15 13:50:58 -0800598 Say N if unsure.
Paul Menage006cb992007-10-18 23:39:43 -0700599
Serge E. Hallyn858d72e2007-10-18 23:39:45 -0700600config CGROUP_NS
Li Zefan23964d22009-01-15 13:50:58 -0800601 bool "Namespace cgroup subsystem"
Li Zefan23964d22009-01-15 13:50:58 -0800602 help
603 Provides a simple namespace cgroup subsystem to
604 provide hierarchical naming of sets of namespaces,
605 for instance virtual servers and checkpoint/restart
606 jobs.
Serge E. Hallyn858d72e2007-10-18 23:39:45 -0700607
Matt Helsleydc52ddc2008-10-18 20:27:21 -0700608config CGROUP_FREEZER
Li Zefan23964d22009-01-15 13:50:58 -0800609 bool "Freezer cgroup subsystem"
Li Zefan23964d22009-01-15 13:50:58 -0800610 help
611 Provides a way to freeze and unfreeze all tasks in a
Matt Helsleydc52ddc2008-10-18 20:27:21 -0700612 cgroup.
613
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700614config CGROUP_DEVICE
615 bool "Device controller for cgroups"
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700616 help
617 Provides a cgroup implementing whitelists for devices which
618 a process in the cgroup can mknod or open.
619
Linus Torvalds1da177e2005-04-16 15:20:36 -0700620config CPUSETS
621 bool "Cpuset support"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700622 help
Randy Dunlapd9fd8a62005-07-27 11:45:11 -0700623 This option will let you create and manage CPUSETs which
Linus Torvalds1da177e2005-04-16 15:20:36 -0700624 allow dynamically partitioning a system into sets of CPUs and
625 Memory Nodes and assigning tasks to run only within those sets.
626 This is primarily useful on large SMP or NUMA systems.
627
628 Say N if unsure.
629
Li Zefan23964d22009-01-15 13:50:58 -0800630config PROC_PID_CPUSET
631 bool "Include legacy /proc/<pid>/cpuset file"
632 depends on CPUSETS
633 default y
634
Srivatsa Vaddagirid842de82007-12-02 20:04:49 +0100635config CGROUP_CPUACCT
636 bool "Simple CPU accounting cgroup subsystem"
Srivatsa Vaddagirid842de82007-12-02 20:04:49 +0100637 help
638 Provides a simple Resource Controller for monitoring the
Li Zefan23964d22009-01-15 13:50:58 -0800639 total CPU consumed by the tasks in a cgroup.
Srivatsa Vaddagirid842de82007-12-02 20:04:49 +0100640
Pavel Emelianove552b662008-02-07 00:13:49 -0800641config RESOURCE_COUNTERS
642 bool "Resource counters"
643 help
644 This option enables controller independent resource accounting
Li Zefan23964d22009-01-15 13:50:58 -0800645 infrastructure that works with cgroups.
Pavel Emelianove552b662008-02-07 00:13:49 -0800646
Balbir Singh00f0b822008-03-04 14:28:39 -0800647config CGROUP_MEM_RES_CTLR
648 bool "Memory Resource Controller for Control Groups"
Daniel Lezcano79ae9c22010-10-27 15:34:39 -0700649 depends on RESOURCE_COUNTERS
Balbir Singhcf475ad2008-04-29 01:00:16 -0700650 select MM_OWNER
Balbir Singh00f0b822008-03-04 14:28:39 -0800651 help
KAMEZAWA Hiroyuki84ad6d72008-10-29 14:01:06 -0700652 Provides a memory resource controller that manages both anonymous
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +0100653 memory and page cache. (See Documentation/cgroups/memory.txt)
Balbir Singh00f0b822008-03-04 14:28:39 -0800654
655 Note that setting this option increases fixed memory overhead
KAMEZAWA Hiroyuki84ad6d72008-10-29 14:01:06 -0700656 associated with each page of memory in the system. By this,
657 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
658 usage tracking struct at boot. Total amount of this is printed out
659 at boot.
Balbir Singh00f0b822008-03-04 14:28:39 -0800660
661 Only enable when you're ok with these trade offs and really
KAMEZAWA Hiroyuki84ad6d72008-10-29 14:01:06 -0700662 sure you need the memory resource controller. Even when you enable
663 this, you can set "cgroup_disable=memory" at your boot option to
664 disable memory resource controller and you can avoid overheads.
Li Zefanc9d54092009-01-07 18:07:35 -0800665 (and lose benefits of memory resource controller)
Balbir Singh00f0b822008-03-04 14:28:39 -0800666
Balbir Singhcf475ad2008-04-29 01:00:16 -0700667 This config option also selects MM_OWNER config option, which
668 could in turn add some fork/exit overhead.
669
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800670config CGROUP_MEM_RES_CTLR_SWAP
KAMEZAWA Hiroyuki65e0e812010-08-10 18:02:56 -0700671 bool "Memory Resource Controller Swap Extension"
672 depends on CGROUP_MEM_RES_CTLR && SWAP
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800673 help
674 Add swap management feature to memory resource controller. When you
675 enable this, you can limit mem+swap usage per cgroup. In other words,
676 when you disable this, memory resource controller has no cares to
677 usage of swap...a process can exhaust all of the swap. This extension
678 is useful when you want to avoid exhaustion swap but this itself
679 adds more overheads and consumes memory for remembering information.
680 Especially if you use 32bit system or small memory system, please
681 be careful about enabling this. When memory resource controller
682 is disabled by boot option, this will be automatically disabled and
683 there will be no overhead from this. Even when you set this config=y,
684 if boot option "noswapaccount" is set, swap will not be accounted.
KAMEZAWA Hiroyuki627991a2009-04-02 16:57:47 -0700685 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
686 size is 4096bytes, 512k per 1Gbytes of swap.
Michal Hockoa42c3902010-11-24 12:57:08 -0800687config CGROUP_MEM_RES_CTLR_SWAP_ENABLED
688 bool "Memory Resource Controller Swap Extension enabled by default"
689 depends on CGROUP_MEM_RES_CTLR_SWAP
690 default y
691 help
692 Memory Resource Controller Swap Extension comes with its price in
693 a bigger memory consumption. General purpose distribution kernels
Jim Cromie43d547f2010-12-17 14:32:36 -0700694 which want to enable the feature but keep it disabled by default
Michal Hockoa42c3902010-11-24 12:57:08 -0800695 and let the user enable it by swapaccount boot command line
696 parameter should have this option unselected.
697 For those who want to have the feature enabled by default should
698 select this option (if, for some reason, they need to disable it
699 then noswapaccount does the trick).
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800700
Dhaval Giani7c941432010-01-20 13:26:18 +0100701menuconfig CGROUP_SCHED
702 bool "Group CPU scheduler"
Daniel Lezcano79ae9c22010-10-27 15:34:39 -0700703 depends on EXPERIMENTAL
Dhaval Giani7c941432010-01-20 13:26:18 +0100704 default n
705 help
706 This feature lets CPU scheduler recognize task groups and control CPU
707 bandwidth allocation to such task groups. It uses cgroups to group
708 tasks.
709
710if CGROUP_SCHED
711config FAIR_GROUP_SCHED
712 bool "Group scheduling for SCHED_OTHER"
713 depends on CGROUP_SCHED
714 default CGROUP_SCHED
715
716config RT_GROUP_SCHED
717 bool "Group scheduling for SCHED_RR/FIFO"
718 depends on EXPERIMENTAL
719 depends on CGROUP_SCHED
720 default n
721 help
722 This feature lets you explicitly allocate real CPU bandwidth
Li Zefan32bd7eb2010-03-24 13:17:19 +0800723 to task groups. If enabled, it will also make it impossible to
Dhaval Giani7c941432010-01-20 13:26:18 +0100724 schedule realtime tasks for non-root users until you allocate
725 realtime bandwidth for them.
726 See Documentation/scheduler/sched-rt-group.txt for more information.
727
728endif #CGROUP_SCHED
729
Vivek Goyalafc24d42010-04-26 19:27:56 +0200730config BLK_CGROUP
731 tristate "Block IO controller"
Daniel Lezcano79ae9c22010-10-27 15:34:39 -0700732 depends on BLOCK
Vivek Goyalafc24d42010-04-26 19:27:56 +0200733 default n
734 ---help---
735 Generic block IO controller cgroup interface. This is the common
736 cgroup interface which should be used by various IO controlling
737 policies.
738
739 Currently, CFQ IO scheduler uses it to recognize task groups and
740 control disk bandwidth allocation (proportional time slice allocation)
Vivek Goyale43473b2010-09-15 17:06:35 -0400741 to such task groups. It is also used by bio throttling logic in
742 block layer to implement upper limit in IO rates on a device.
Vivek Goyalafc24d42010-04-26 19:27:56 +0200743
744 This option only enables generic Block IO controller infrastructure.
Vivek Goyale43473b2010-09-15 17:06:35 -0400745 One needs to also enable actual IO controlling logic/policy. For
746 enabling proportional weight division of disk bandwidth in CFQ seti
747 CONFIG_CFQ_GROUP_IOSCHED=y and for enabling throttling policy set
748 CONFIG_BLK_THROTTLE=y.
Vivek Goyalafc24d42010-04-26 19:27:56 +0200749
750 See Documentation/cgroups/blkio-controller.txt for more information.
751
752config DEBUG_BLK_CGROUP
753 bool "Enable Block IO controller debugging"
754 depends on BLK_CGROUP
755 default n
756 ---help---
757 Enable some debugging help. Currently it exports additional stat
758 files in a cgroup which can be useful for debugging.
759
Li Zefan23964d22009-01-15 13:50:58 -0800760endif # CGROUPS
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800761
Daniel Lezcano8dd2a822010-10-27 15:34:38 -0700762menuconfig NAMESPACES
Pavel Emelyanovc5289a62008-02-08 04:18:19 -0800763 bool "Namespaces support" if EMBEDDED
764 default !EMBEDDED
765 help
766 Provides the way to make tasks work with different objects using
767 the same id. For example same IPC id may refer to different objects
768 or same user id or pid may refer to different tasks when used in
769 different namespaces.
770
Daniel Lezcano8dd2a822010-10-27 15:34:38 -0700771if NAMESPACES
772
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -0800773config UTS_NS
774 bool "UTS namespace"
Daniel Lezcano17a6d442010-10-27 15:34:37 -0700775 default y
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -0800776 help
777 In this namespace tasks see different info provided with the
778 uname() system call
779
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -0800780config IPC_NS
781 bool "IPC namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -0700782 depends on (SYSVIPC || POSIX_MQUEUE)
Daniel Lezcano17a6d442010-10-27 15:34:37 -0700783 default y
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -0800784 help
785 In this namespace tasks work with IPC ids which correspond to
Serge E. Hallyn614b84c2009-04-06 19:01:08 -0700786 different IPC objects in different namespaces.
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -0800787
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -0800788config USER_NS
789 bool "User namespace (EXPERIMENTAL)"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -0700790 depends on EXPERIMENTAL
Daniel Lezcano17a6d442010-10-27 15:34:37 -0700791 default y
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -0800792 help
793 This allows containers, i.e. vservers, to use user namespaces
794 to provide different user info for different servers.
795 If unsure, say N.
796
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -0800797config PID_NS
Daniel Lezcano9bd38c22010-10-27 15:34:37 -0700798 bool "PID Namespaces"
Daniel Lezcano17a6d442010-10-27 15:34:37 -0700799 default y
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -0800800 help
Heikki Orsila12d2b8f2008-07-06 15:48:02 +0300801 Support process id namespaces. This allows having multiple
Matt LaPlante692105b2009-01-26 11:12:25 +0100802 processes with the same pid as long as they are in different
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -0800803 pid namespaces. This is a building block of containers.
804
Matt Helsleyd6eb6332009-01-26 12:25:55 -0800805config NET_NS
806 bool "Network namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -0700807 depends on NET
Daniel Lezcano17a6d442010-10-27 15:34:37 -0700808 default y
Matt Helsleyd6eb6332009-01-26 12:25:55 -0800809 help
810 Allow user space to create what appear to be multiple instances
811 of the network stack.
812
Daniel Lezcano8dd2a822010-10-27 15:34:38 -0700813endif # NAMESPACES
814
Mike Galbraith5091faa2010-11-30 14:18:03 +0100815config SCHED_AUTOGROUP
816 bool "Automatic process group scheduling"
817 select EVENTFD
818 select CGROUPS
819 select CGROUP_SCHED
820 select FAIR_GROUP_SCHED
821 help
822 This option optimizes the scheduler for common desktop workloads by
823 automatically creating and populating task groups. This separation
824 of workloads isolates aggressive CPU burners (like build jobs) from
825 desktop applications. Task group autogeneration is currently based
826 upon task session.
827
Daniel Lezcano7af37be2010-10-27 15:34:41 -0700828config MM_OWNER
829 bool
830
831config SYSFS_DEPRECATED
832 bool "enable deprecated sysfs features to support old userspace tools"
833 depends on SYSFS
834 default n
835 help
836 This option adds code that switches the layout of the "block" class
837 devices, to not show up in /sys/class/block/, but only in
838 /sys/block/.
839
840 This switch is only active when the sysfs.deprecated=1 boot option is
841 passed or the SYSFS_DEPRECATED_V2 option is set.
842
843 This option allows new kernels to run on old distributions and tools,
844 which might get confused by /sys/class/block/. Since 2007/2008 all
845 major distributions and tools handle this just fine.
846
847 Recent distributions and userspace tools after 2009/2010 depend on
848 the existence of /sys/class/block/, and will not work with this
849 option enabled.
850
851 Only if you are using a new kernel on an old distribution, you might
852 need to say Y here.
853
854config SYSFS_DEPRECATED_V2
855 bool "enabled deprecated sysfs features by default"
856 default n
857 depends on SYSFS
858 depends on SYSFS_DEPRECATED
859 help
860 Enable deprecated sysfs by default.
861
862 See the CONFIG_SYSFS_DEPRECATED option for more details about this
863 option.
864
865 Only if you are using a new kernel on an old distribution, you might
866 need to say Y here. Even then, odds are you would not need it
867 enabled, you can always pass the boot option if absolutely necessary.
868
869config RELAY
870 bool "Kernel->user space relay support (formerly relayfs)"
871 help
872 This option enables support for relay interface support in
873 certain file systems (such as debugfs).
874 It is designed to provide an efficient mechanism for tools and
875 facilities to relay large amounts of data from kernel space to
876 user space.
877
878 If unsure, say N.
879
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -0800880config BLK_DEV_INITRD
881 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
882 depends on BROKEN || !FRV
883 help
884 The initial RAM filesystem is a ramfs which is loaded by the
885 boot loader (loadlin or lilo) and that is mounted as root
886 before the normal boot procedure. It is typically used to
887 load modules needed to mount the "real" root file system,
888 etc. See <file:Documentation/initrd.txt> for details.
889
890 If RAM disk support (BLK_DEV_RAM) is also included, this
891 also enables initial RAM disk (initrd) support and adds
892 15 Kbytes (more on some other architectures) to the kernel size.
893
894 If unsure say Y.
895
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -0800896if BLK_DEV_INITRD
897
Sam Ravnborgdbec4862005-08-10 20:44:50 +0200898source "usr/Kconfig"
899
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -0800900endif
901
Linus Torvaldsc45b4f12005-12-14 18:52:21 -0800902config CC_OPTIMIZE_FOR_SIZE
Ingo Molnar96fffeb2008-04-28 01:39:43 +0200903 bool "Optimize for size"
Linus Torvaldsc45b4f12005-12-14 18:52:21 -0800904 default y
Linus Torvaldsc45b4f12005-12-14 18:52:21 -0800905 help
906 Enabling this option will pass "-Os" instead of "-O2" to gcc
907 resulting in a smaller kernel.
908
jkacur775a7222008-07-16 00:31:16 +0200909 If unsure, say Y.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -0800910
Randy Dunlap08470622006-09-30 23:28:13 -0700911config SYSCTL
912 bool
913
Randy Dunlapb943c462009-03-10 12:55:46 -0700914config ANON_INODES
915 bool
916
Linus Torvalds1da177e2005-04-16 15:20:36 -0700917menuconfig EMBEDDED
918 bool "Configure standard kernel features (for small systems)"
919 help
920 This option allows certain base kernel options and settings
921 to be disabled or tweaked. This is for specialized
922 environments which can tolerate a "non-standard" kernel.
923 Only use this if you really know what you are doing.
924
Chuck Ebbertae81f9e2006-09-16 12:15:53 -0700925config UID16
926 bool "Enable 16-bit UID system calls" if EMBEDDED
David S. Miller09337f52008-04-26 03:17:12 -0700927 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 -0700928 default y
929 help
930 This enables the legacy 16-bit UID syscall wrappers.
931
Eric W. Biedermanb89a8172006-09-27 01:51:04 -0700932config SYSCTL_SYSCALL
Randy Dunlap08470622006-09-30 23:28:13 -0700933 bool "Sysctl syscall support" if EMBEDDED
Eric W. Biederman26a70342009-11-05 05:26:41 -0800934 depends on PROC_SYSCTL
Eric W. Biederman13bb7e32006-11-08 17:44:51 -0800935 default y
Eric W. Biedermanb89a8172006-09-27 01:51:04 -0700936 select SYSCTL
937 ---help---
Eric W. Biederman13bb7e32006-11-08 17:44:51 -0800938 sys_sysctl uses binary paths that have been found challenging
939 to properly maintain and use. The interface in /proc/sys
940 using paths with ascii names is now the primary path to this
941 information.
Eric W. Biedermanb89a8172006-09-27 01:51:04 -0700942
Eric W. Biederman13bb7e32006-11-08 17:44:51 -0800943 Almost nothing using the binary sysctl interface so if you are
944 trying to save some space it is probably safe to disable this,
945 making your kernel marginally smaller.
Eric W. Biedermanb89a8172006-09-27 01:51:04 -0700946
Eric W. Biederman13bb7e32006-11-08 17:44:51 -0800947 If unsure say Y here.
Chuck Ebbertae81f9e2006-09-16 12:15:53 -0700948
Linus Torvalds1da177e2005-04-16 15:20:36 -0700949config KALLSYMS
Jesper Juhl979c6a12006-12-12 19:25:11 +0100950 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
Linus Torvalds1da177e2005-04-16 15:20:36 -0700951 default y
952 help
953 Say Y here to let the kernel print out symbolic crash information and
954 symbolic stack backtraces. This increases the size of the kernel
955 somewhat, as all symbols have to be loaded into the kernel image.
956
957config KALLSYMS_ALL
958 bool "Include all symbols in kallsyms"
959 depends on DEBUG_KERNEL && KALLSYMS
960 help
961 Normally kallsyms only contains the symbols of functions, for nicer
962 OOPS messages. Some debuggers can use kallsyms for other
Jesper Juhlf9f97bc2005-07-20 05:43:05 +0200963 symbols too: say Y here to include all symbols, if you need them
964 and you don't care about adding 300k to the size of your kernel.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700965
966 Say N.
967
968config KALLSYMS_EXTRA_PASS
969 bool "Do an extra kallsyms pass"
970 depends on KALLSYMS
971 help
972 If kallsyms is not working correctly, the build will fail with
973 inconsistent kallsyms data. If that occurs, log a bug report and
974 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
975 Always say N here unless you find a bug in kallsyms, which must be
976 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
977 you wait for kallsyms to be fixed.
978
Matt Mackalld59745c2005-05-01 08:59:02 -0700979
Greg Kroah-Hartman712f47c2005-11-16 11:27:07 -0800980config HOTPLUG
981 bool "Support for hot-pluggable devices" if EMBEDDED
982 default y
983 help
984 This option is provided for the case where no hotplug or uevent
985 capabilities is wanted by the kernel. You should only consider
986 disabling this option for embedded systems that do not use modules, a
987 dynamic /dev tree, or dynamic device discovery. Just say Y.
988
Matt Mackalld59745c2005-05-01 08:59:02 -0700989config PRINTK
990 default y
991 bool "Enable support for printk" if EMBEDDED
992 help
993 This option enables normal printk support. Removing it
994 eliminates most of the message strings from the kernel image
995 and makes the kernel more or less silent. As this makes it
996 very difficult to diagnose system problems, saying N here is
997 strongly discouraged.
998
Matt Mackallc8538a72005-05-01 08:59:01 -0700999config BUG
1000 bool "BUG() support" if EMBEDDED
1001 default y
1002 help
1003 Disabling this option eliminates support for BUG and WARN, reducing
1004 the size of your kernel image and potentially quietly ignoring
1005 numerous fatal conditions. You should only consider disabling this
1006 option for embedded systems with no facilities for reporting errors.
1007 Just say Y.
1008
Matt Mackall708e9a72006-01-08 01:05:25 -08001009config ELF_CORE
1010 default y
1011 bool "Enable ELF core dumps" if EMBEDDED
1012 help
1013 Enable support for generating core dumps. Disabling saves about 4k.
1014
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001015config PCSPKR_PLATFORM
1016 bool "Enable PC-Speaker support" if EMBEDDED
1017 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
1018 default y
1019 help
1020 This option allows to disable the internal PC-Speaker
1021 support, saving some memory.
1022
Linus Torvalds1da177e2005-04-16 15:20:36 -07001023config BASE_FULL
1024 default y
1025 bool "Enable full-sized data structures for core" if EMBEDDED
1026 help
1027 Disabling this option reduces the size of miscellaneous core
1028 kernel data structures. This saves memory on small machines,
1029 but may reduce performance.
1030
1031config FUTEX
1032 bool "Enable futex support" if EMBEDDED
1033 default y
Ingo Molnar23f78d42006-06-27 02:54:53 -07001034 select RT_MUTEXES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001035 help
1036 Disabling this option will cause the kernel to be built without
1037 support for "fast userspace mutexes". The resulting kernel may not
1038 run glibc-based applications correctly.
1039
1040config EPOLL
1041 bool "Enable eventpoll support" if EMBEDDED
1042 default y
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001043 select ANON_INODES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001044 help
1045 Disabling this option will cause the kernel to be built without
1046 support for epoll family of system calls.
1047
Davide Libenzifba2afa2007-05-10 22:23:13 -07001048config SIGNALFD
1049 bool "Enable signalfd() system call" if EMBEDDED
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001050 select ANON_INODES
Davide Libenzifba2afa2007-05-10 22:23:13 -07001051 default y
1052 help
1053 Enable the signalfd() system call that allows to receive signals
1054 on a file descriptor.
1055
1056 If unsure, say Y.
1057
Davide Libenzib215e282007-05-10 22:23:16 -07001058config TIMERFD
1059 bool "Enable timerfd() system call" if EMBEDDED
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001060 select ANON_INODES
Davide Libenzib215e282007-05-10 22:23:16 -07001061 default y
1062 help
1063 Enable the timerfd() system call that allows to receive timer
1064 events on a file descriptor.
1065
1066 If unsure, say Y.
1067
Davide Libenzie1ad7462007-05-10 22:23:19 -07001068config EVENTFD
1069 bool "Enable eventfd() system call" if EMBEDDED
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001070 select ANON_INODES
Davide Libenzie1ad7462007-05-10 22:23:19 -07001071 default y
1072 help
1073 Enable the eventfd() system call that allows to receive both
1074 kernel notification (ie. KAIO) or userspace notifications.
1075
1076 If unsure, say Y.
1077
Linus Torvalds1da177e2005-04-16 15:20:36 -07001078config SHMEM
1079 bool "Use full shmem filesystem" if EMBEDDED
1080 default y
1081 depends on MMU
1082 help
1083 The shmem is an internal filesystem used to manage shared memory.
1084 It is backed by swap and manages resource limits. It is also exported
1085 to userspace as tmpfs if TMPFS is enabled. Disabling this
1086 option replaces shmem and tmpfs with the much simpler ramfs code,
1087 which may be appropriate on small systems without swap.
1088
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001089config AIO
1090 bool "Enable AIO support" if EMBEDDED
1091 default y
1092 help
1093 This option enables POSIX asynchronous I/O which may by used
1094 by some high performance threaded applications. Disabling
1095 this option saves about 7k.
1096
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001097config HAVE_PERF_EVENTS
Thomas Gleixner0793a612008-12-04 20:12:29 +01001098 bool
Mike Frysinger018df722009-06-12 13:17:43 -04001099 help
1100 See tools/perf/design.txt for details.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001101
Peter Zijlstra906010b2009-09-21 16:08:49 +02001102config PERF_USE_VMALLOC
1103 bool
1104 help
1105 See tools/perf/design.txt for details
1106
Ingo Molnar57c0c152009-09-21 12:20:38 +02001107menu "Kernel Performance Events And Counters"
Thomas Gleixner0793a612008-12-04 20:12:29 +01001108
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001109config PERF_EVENTS
Ingo Molnar57c0c152009-09-21 12:20:38 +02001110 bool "Kernel performance events and counters"
1111 default y if (PROFILING || PERF_COUNTERS)
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001112 depends on HAVE_PERF_EVENTS
Ingo Molnar4c59e462008-12-08 19:38:33 +01001113 select ANON_INODES
Peter Zijlstrae360adb2010-10-14 14:01:34 +08001114 select IRQ_WORK
Thomas Gleixner0793a612008-12-04 20:12:29 +01001115 help
Ingo Molnar57c0c152009-09-21 12:20:38 +02001116 Enable kernel support for various performance events provided
1117 by software and hardware.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001118
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001119 Software events are supported either built-in or via the
Ingo Molnar57c0c152009-09-21 12:20:38 +02001120 use of generic tracepoints.
1121
1122 Most modern CPUs support performance events via performance
1123 counter registers. These registers count the number of certain
Thomas Gleixner0793a612008-12-04 20:12:29 +01001124 types of hw events: such as instructions executed, cachemisses
1125 suffered, or branches mis-predicted - without slowing down the
1126 kernel or applications. These registers can also trigger interrupts
1127 when a threshold number of events have passed - and can thus be
1128 used to profile the code that runs on that CPU.
1129
Ingo Molnar57c0c152009-09-21 12:20:38 +02001130 The Linux Performance Event subsystem provides an abstraction of
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001131 these software and hardware event capabilities, available via a
Ingo Molnar57c0c152009-09-21 12:20:38 +02001132 system call and used by the "perf" utility in tools/perf/. It
Thomas Gleixner0793a612008-12-04 20:12:29 +01001133 provides per task and per CPU counters, and it provides event
1134 capabilities on top of those.
1135
1136 Say Y if unsure.
1137
Ingo Molnar57c0c152009-09-21 12:20:38 +02001138config PERF_COUNTERS
1139 bool "Kernel performance counters (old config option)"
1140 depends on HAVE_PERF_EVENTS
1141 help
1142 This config has been obsoleted by the PERF_EVENTS
1143 config option - please see that one for details.
1144
1145 It has no effect on the kernel whether you enable
1146 it or not, it is a compatibility placeholder.
1147
1148 Say N if unsure.
1149
Peter Zijlstra906010b2009-09-21 16:08:49 +02001150config DEBUG_PERF_USE_VMALLOC
1151 default n
1152 bool "Debug: use vmalloc to back perf mmap() buffers"
1153 depends on PERF_EVENTS && DEBUG_KERNEL
1154 select PERF_USE_VMALLOC
1155 help
1156 Use vmalloc memory to back perf mmap() buffers.
1157
1158 Mostly useful for debugging the vmalloc code on platforms
1159 that don't require it.
1160
1161 Say N if unsure.
1162
Thomas Gleixner0793a612008-12-04 20:12:29 +01001163endmenu
1164
Christoph Lameterf8891e52006-06-30 01:55:45 -07001165config VM_EVENT_COUNTERS
1166 default y
1167 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
1168 help
Paul Jackson2aea4fb2006-12-22 01:06:10 -08001169 VM event counters are needed for event counts to be shown.
1170 This option allows the disabling of the VM event counters
1171 on EMBEDDED systems. /proc/vmstat will only show page counts
1172 if VM event counters are disabled.
Christoph Lameterf8891e52006-06-30 01:55:45 -07001173
Thomas Petazzoni3d137312008-08-19 10:28:24 +02001174config PCI_QUIRKS
1175 default y
Geert Uytterhoeven61cfc7e2008-10-22 08:53:25 +02001176 bool "Enable PCI quirk workarounds" if EMBEDDED
1177 depends on PCI
Thomas Petazzoni3d137312008-08-19 10:28:24 +02001178 help
1179 This enables workarounds for various PCI chipset
1180 bugs/quirks. Disable this only if your target machine is
1181 unaffected by PCI quirks.
1182
Christoph Lameter41ecc552007-05-09 02:32:44 -07001183config SLUB_DEBUG
1184 default y
1185 bool "Enable SLUB debugging support" if EMBEDDED
Christoph Lameterf6acb632008-04-29 16:16:06 -07001186 depends on SLUB && SYSFS
Christoph Lameter41ecc552007-05-09 02:32:44 -07001187 help
1188 SLUB has extensive debug support features. Disabling these can
1189 result in significant savings in code size. This also disables
1190 SLUB sysfs support. /sys/slab will not exist and there will be
1191 no support for cache validation etc.
1192
Randy Dunlapb943c462009-03-10 12:55:46 -07001193config COMPAT_BRK
1194 bool "Disable heap randomization"
1195 default y
1196 help
1197 Randomizing heap placement makes heap exploits harder, but it
1198 also breaks ancient binaries (including anything libc5 based).
1199 This option changes the bootup default to heap randomization
Matt LaPlante692105b2009-01-26 11:12:25 +01001200 disabled, and can be overridden at runtime by setting
Randy Dunlapb943c462009-03-10 12:55:46 -07001201 /proc/sys/kernel/randomize_va_space to 2.
1202
1203 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1204
Christoph Lameter81819f02007-05-06 14:49:36 -07001205choice
1206 prompt "Choose SLAB allocator"
Christoph Lametera0acd822007-07-17 04:03:32 -07001207 default SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -07001208 help
1209 This option allows to select a slab allocator.
1210
1211config SLAB
1212 bool "SLAB"
1213 help
1214 The regular slab allocator that is established and known to work
Christoph Lameter34013882007-05-09 02:32:47 -07001215 well in all environments. It organizes cache hot objects in
Simon Arlott02f56212008-11-05 22:18:19 +00001216 per cpu and per node queues.
Christoph Lameter81819f02007-05-06 14:49:36 -07001217
1218config SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -07001219 bool "SLUB (Unqueued Allocator)"
1220 help
1221 SLUB is a slab allocator that minimizes cache line usage
1222 instead of managing queues of cached objects (SLAB approach).
1223 Per cpu caching is realized using slabs of objects instead
1224 of queues of objects. SLUB can use memory efficiently
Simon Arlott02f56212008-11-05 22:18:19 +00001225 and has enhanced diagnostics. SLUB is the default choice for
1226 a slab allocator.
Christoph Lameter81819f02007-05-06 14:49:36 -07001227
1228config SLOB
Paul Mundt84a01c22007-07-15 23:38:24 -07001229 depends on EMBEDDED
Christoph Lameter81819f02007-05-06 14:49:36 -07001230 bool "SLOB (Simple Allocator)"
1231 help
Matt Mackall37291452008-02-04 22:29:38 -08001232 SLOB replaces the stock allocator with a drastically simpler
1233 allocator. SLOB is generally more space efficient but
1234 does not perform as well on large systems.
Christoph Lameter81819f02007-05-06 14:49:36 -07001235
1236endchoice
1237
Jie Zhangea637632009-12-14 18:00:02 -08001238config MMAP_ALLOW_UNINITIALIZED
1239 bool "Allow mmapped anonymous memory to be uninitialized"
1240 depends on EMBEDDED && !MMU
1241 default n
1242 help
1243 Normally, and according to the Linux spec, anonymous memory obtained
1244 from mmap() has it's contents cleared before it is passed to
1245 userspace. Enabling this config option allows you to request that
1246 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1247 providing a huge performance boost. If this option is not enabled,
1248 then the flag will be ignored.
1249
1250 This is taken advantage of by uClibc's malloc(), and also by
1251 ELF-FDPIC binfmt's brk and stack allocator.
1252
1253 Because of the obvious security issues, this option should only be
1254 enabled on embedded devices where you control what is run in
1255 userspace. Since that isn't generally a problem on no-MMU systems,
1256 it is normally safe to say Y here.
1257
1258 See Documentation/nommu-mmap.txt for more information.
1259
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001260config PROFILING
Robert Richterb309a292010-02-26 15:01:23 +01001261 bool "Profiling support"
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001262 help
1263 Say Y here to enable the extended profiling support mechanisms used
1264 by profilers such as OProfile.
1265
Ingo Molnar5f87f112008-07-23 14:15:22 +02001266#
1267# Place an empty function call at each tracepoint site. Can be
1268# dynamically changed for a probe function.
1269#
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001270config TRACEPOINTS
Ingo Molnar5f87f112008-07-23 14:15:22 +02001271 bool
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001272
Mathieu Desnoyersfb32e032008-02-02 15:10:33 -05001273source "arch/Kconfig"
1274
Linus Torvalds1da177e2005-04-16 15:20:36 -07001275endmenu # General setup
1276
Dmitry Baryshkovee7e5512008-06-29 14:18:46 +04001277config HAVE_GENERIC_DMA_COHERENT
1278 bool
1279 default n
1280
Linus Torvalds158a9622008-01-02 13:04:48 -08001281config SLABINFO
1282 bool
1283 depends on PROC_FS
Christoph Lameter0f389ec2008-04-14 18:53:02 +03001284 depends on SLAB || SLUB_DEBUG
Linus Torvalds158a9622008-01-02 13:04:48 -08001285 default y
1286
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001287config RT_MUTEXES
1288 boolean
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001289
Linus Torvalds1da177e2005-04-16 15:20:36 -07001290config BASE_SMALL
1291 int
1292 default 0 if BASE_FULL
1293 default 1 if !BASE_FULL
1294
Jan Engelhardt66da5732007-07-15 23:39:29 -07001295menuconfig MODULES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001296 bool "Enable loadable module support"
1297 help
1298 Kernel modules are small pieces of compiled code which can
1299 be inserted in the running kernel, rather than being
1300 permanently built into the kernel. You use the "modprobe"
1301 tool to add (and sometimes remove) them. If you say Y here,
1302 many parts of the kernel can be built as modules (by
1303 answering M instead of Y where indicated): this is most
1304 useful for infrequently used options which are not required
1305 for booting. For more information, see the man pages for
1306 modprobe, lsmod, modinfo, insmod and rmmod.
1307
1308 If you say Y here, you will need to run "make
1309 modules_install" to put the modules under /lib/modules/
1310 where modprobe can find them (you may need to be root to do
1311 this).
1312
1313 If unsure, say Y.
1314
Robert P. J. Day0b0de142008-08-04 13:31:32 -04001315if MODULES
1316
Linus Torvalds826e4502008-05-04 17:04:16 -07001317config MODULE_FORCE_LOAD
1318 bool "Forced module loading"
Linus Torvalds826e4502008-05-04 17:04:16 -07001319 default n
1320 help
Rusty Russell91e37a72008-05-09 16:25:28 +10001321 Allow loading of modules without version information (ie. modprobe
1322 --force). Forced module loading sets the 'F' (forced) taint flag and
1323 is usually a really bad idea.
Linus Torvalds826e4502008-05-04 17:04:16 -07001324
Linus Torvalds1da177e2005-04-16 15:20:36 -07001325config MODULE_UNLOAD
1326 bool "Module unloading"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001327 help
1328 Without this option you will not be able to unload any
1329 modules (note that some modules may not be unloadable
Denys Vlasenkof7f5b672008-07-22 19:24:26 -05001330 anyway), which makes your kernel smaller, faster
1331 and simpler. If unsure, say Y.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001332
1333config MODULE_FORCE_UNLOAD
1334 bool "Forced module unloading"
1335 depends on MODULE_UNLOAD && EXPERIMENTAL
1336 help
1337 This option allows you to force a module to unload, even if the
1338 kernel believes it is unsafe: the kernel will remove the module
1339 without waiting for anyone to stop using it (using the -f option to
1340 rmmod). This is mainly for kernel developers and desperate users.
1341 If unsure, say N.
1342
Linus Torvalds1da177e2005-04-16 15:20:36 -07001343config MODVERSIONS
Sam Ravnborg0d541642005-12-26 23:04:02 +01001344 bool "Module versioning support"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001345 help
1346 Usually, you have to use modules compiled with your kernel.
1347 Saying Y here makes it sometimes possible to use modules
1348 compiled for different kernels, by adding enough information
1349 to the modules to (hopefully) spot any changes which would
1350 make them incompatible with the kernel you are running. If
1351 unsure, say N.
1352
1353config MODULE_SRCVERSION_ALL
1354 bool "Source checksum for all modules"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001355 help
1356 Modules which contain a MODULE_VERSION get an extra "srcversion"
1357 field inserted into their modinfo section, which contains a
1358 sum of the source files which made it. This helps maintainers
1359 see exactly which source was used to build a module (since
1360 others sometimes change the module source without updating
1361 the version). With this option, such a "srcversion" field
1362 will be created for all modules. If unsure, say N.
1363
Robert P. J. Day0b0de142008-08-04 13:31:32 -04001364endif # MODULES
1365
Rusty Russell98a79d62008-12-13 21:19:41 +10301366config INIT_ALL_POSSIBLE
1367 bool
1368 help
1369 Back when each arch used to define their own cpu_online_map and
1370 cpu_possible_map, some of them chose to initialize cpu_possible_map
1371 with all 1s, and others with all 0s. When they were centralised,
1372 it was better to provide this option than to break all the archs
Matt LaPlante692105b2009-01-26 11:12:25 +01001373 and have several arch maintainers pursuing me down dark alleys.
Rusty Russell98a79d62008-12-13 21:19:41 +10301374
Linus Torvalds1da177e2005-04-16 15:20:36 -07001375config STOP_MACHINE
1376 bool
1377 default y
1378 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1379 help
1380 Need stop_machine() primitive.
Jens Axboe3a65dfe2005-11-04 08:43:35 +01001381
Jens Axboe3a65dfe2005-11-04 08:43:35 +01001382source "block/Kconfig"
Avi Kivitye98c3202007-10-16 23:27:31 -07001383
1384config PREEMPT_NOTIFIERS
1385 bool
Paul E. McKenneye260be62008-01-25 21:08:24 +01001386
Steffen Klassert16295be2010-01-06 19:47:10 +11001387config PADATA
1388 depends on SMP
1389 bool
1390
Thomas Gleixner6beb0002009-11-09 15:21:34 +00001391source "kernel/Kconfig.locks"