Merge branches 'sched-core-for-linus' and 'sched-urgent-for-linus' of git://git.kerne...
[deliverable/linux.git] / init / Kconfig
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1config ARCH
2 string
3 option env="ARCH"
4
5config KERNELVERSION
6 string
7 option env="KERNELVERSION"
8
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9config DEFCONFIG_LIST
10 string
b2670eac 11 depends on !UML
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12 option defconfig_list
13 default "/lib/modules/$UNAME_RELEASE/.config"
14 default "/etc/kernel-config"
15 default "/boot/config-$UNAME_RELEASE"
73531905 16 default "$ARCH_DEFCONFIG"
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17 default "arch/$ARCH/defconfig"
18
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19config CONSTRUCTORS
20 bool
21 depends on !UML
22 default y
23
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24config HAVE_IRQ_WORK
25 bool
26
27config IRQ_WORK
28 bool
29 depends on HAVE_IRQ_WORK
30
ff0cfc66 31menu "General setup"
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32
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54 drivers that have been replaced by something else, and/or are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
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64config BROKEN
65 bool
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66
67config BROKEN_ON_SMP
68 bool
69 depends on BROKEN || !SMP
70 default y
71
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72config INIT_ENV_ARG_LIMIT
73 int
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74 default 32 if !UML
75 default 128 if UML
1da177e4 76 help
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77 Maximum of each of the number of arguments and environment
78 variables passed to init from the kernel command line.
1da177e4 79
1da177e4 80
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81config CROSS_COMPILE
82 string "Cross-compiler tool prefix"
83 help
84 Same as running 'make CROSS_COMPILE=prefix-' but stored for
85 default make runs in this kernel build directory. You don't
86 need to set this unless you want the configured kernel build
87 directory to select the cross-compiler automatically.
88
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89config LOCALVERSION
90 string "Local version - append to kernel release"
91 help
92 Append an extra string to the end of your kernel version.
93 This will show up when you type uname, for example.
94 The string you set here will be appended after the contents of
95 any files with a filename matching localversion* in your
96 object and source tree, in that order. Your total string can
97 be a maximum of 64 characters.
98
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99config LOCALVERSION_AUTO
100 bool "Automatically append version information to the version string"
101 default y
102 help
103 This will try to automatically determine if the current tree is a
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104 release tree by looking for git tags that belong to the current
105 top of tree revision.
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106
107 A string of the format -gxxxxxxxx will be added to the localversion
6e5a5420 108 if a git-based tree is found. The string generated by this will be
aaebf433 109 appended after any matching localversion* files, and after the value
6e5a5420 110 set in CONFIG_LOCALVERSION.
aaebf433 111
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112 (The actual string used here is the first eight characters produced
113 by running the command:
114
115 $ git rev-parse --verify HEAD
116
117 which is done within the script "scripts/setlocalversion".)
aaebf433 118
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119config HAVE_KERNEL_GZIP
120 bool
121
122config HAVE_KERNEL_BZIP2
123 bool
124
125config HAVE_KERNEL_LZMA
126 bool
127
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128config HAVE_KERNEL_XZ
129 bool
130
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131config HAVE_KERNEL_LZO
132 bool
133
30d65dbf 134choice
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135 prompt "Kernel compression mode"
136 default KERNEL_GZIP
3ebe1243 137 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
2e9f3bdd 138 help
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139 The linux kernel is a kind of self-extracting executable.
140 Several compression algorithms are available, which differ
141 in efficiency, compression and decompression speed.
142 Compression speed is only relevant when building a kernel.
143 Decompression speed is relevant at each boot.
144
145 If you have any problems with bzip2 or lzma compressed
146 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
147 version of this functionality (bzip2 only), for 2.4, was
148 supplied by Christian Ludwig)
149
150 High compression options are mostly useful for users, who
151 are low on disk space (embedded systems), but for whom ram
152 size matters less.
153
154 If in doubt, select 'gzip'
155
156config KERNEL_GZIP
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157 bool "Gzip"
158 depends on HAVE_KERNEL_GZIP
159 help
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160 The old and tried gzip compression. It provides a good balance
161 between compression ratio and decompression speed.
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162
163config KERNEL_BZIP2
164 bool "Bzip2"
2e9f3bdd 165 depends on HAVE_KERNEL_BZIP2
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166 help
167 Its compression ratio and speed is intermediate.
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168 Decompression speed is slowest among the three. The kernel
169 size is about 10% smaller with bzip2, in comparison to gzip.
170 Bzip2 uses a large amount of memory. For modern kernels you
171 will need at least 8MB RAM or more for booting.
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172
173config KERNEL_LZMA
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174 bool "LZMA"
175 depends on HAVE_KERNEL_LZMA
176 help
177 The most recent compression algorithm.
178 Its ratio is best, decompression speed is between the other
179 two. Compression is slowest. The kernel size is about 33%
180 smaller with LZMA in comparison to gzip.
30d65dbf 181
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182config KERNEL_XZ
183 bool "XZ"
184 depends on HAVE_KERNEL_XZ
185 help
186 XZ uses the LZMA2 algorithm and instruction set specific
187 BCJ filters which can improve compression ratio of executable
188 code. The size of the kernel is about 30% smaller with XZ in
189 comparison to gzip. On architectures for which there is a BCJ
190 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
191 will create a few percent smaller kernel than plain LZMA.
192
193 The speed is about the same as with LZMA: The decompression
194 speed of XZ is better than that of bzip2 but worse than gzip
195 and LZO. Compression is slow.
196
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197config KERNEL_LZO
198 bool "LZO"
199 depends on HAVE_KERNEL_LZO
200 help
201 Its compression ratio is the poorest among the 4. The kernel
681b3049 202 size is about 10% bigger than gzip; however its speed
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203 (both compression and decompression) is the fastest.
204
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205endchoice
206
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207config SWAP
208 bool "Support for paging of anonymous memory (swap)"
9361401e 209 depends on MMU && BLOCK
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210 default y
211 help
212 This option allows you to choose whether you want to have support
92c3504e 213 for so called swap devices or swap files in your kernel that are
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214 used to provide more virtual memory than the actual RAM present
215 in your computer. If unsure say Y.
216
217config SYSVIPC
218 bool "System V IPC"
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219 ---help---
220 Inter Process Communication is a suite of library functions and
221 system calls which let processes (running programs) synchronize and
222 exchange information. It is generally considered to be a good thing,
223 and some programs won't run unless you say Y here. In particular, if
224 you want to run the DOS emulator dosemu under Linux (read the
225 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
226 you'll need to say Y here.
227
228 You can find documentation about IPC with "info ipc" and also in
229 section 6.4 of the Linux Programmer's Guide, available from
230 <http://www.tldp.org/guides.html>.
231
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232config SYSVIPC_SYSCTL
233 bool
234 depends on SYSVIPC
235 depends on SYSCTL
236 default y
237
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238config POSIX_MQUEUE
239 bool "POSIX Message Queues"
240 depends on NET && EXPERIMENTAL
241 ---help---
242 POSIX variant of message queues is a part of IPC. In POSIX message
243 queues every message has a priority which decides about succession
244 of receiving it by a process. If you want to compile and run
245 programs written e.g. for Solaris with use of its POSIX message
b0e37650 246 queues (functions mq_*) say Y here.
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247
248 POSIX message queues are visible as a filesystem called 'mqueue'
249 and can be mounted somewhere if you want to do filesystem
250 operations on message queues.
251
252 If unsure, say Y.
253
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254config POSIX_MQUEUE_SYSCTL
255 bool
256 depends on POSIX_MQUEUE
257 depends on SYSCTL
258 default y
259
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260config BSD_PROCESS_ACCT
261 bool "BSD Process Accounting"
262 help
263 If you say Y here, a user level program will be able to instruct the
264 kernel (via a special system call) to write process accounting
265 information to a file: whenever a process exits, information about
266 that process will be appended to the file by the kernel. The
267 information includes things such as creation time, owning user,
268 command name, memory usage, controlling terminal etc. (the complete
269 list is in the struct acct in <file:include/linux/acct.h>). It is
270 up to the user level program to do useful things with this
271 information. This is generally a good idea, so say Y.
272
273config BSD_PROCESS_ACCT_V3
274 bool "BSD Process Accounting version 3 file format"
275 depends on BSD_PROCESS_ACCT
276 default n
277 help
278 If you say Y here, the process accounting information is written
279 in a new file format that also logs the process IDs of each
280 process and it's parent. Note that this file format is incompatible
281 with previous v0/v1/v2 file formats, so you will need updated tools
282 for processing it. A preliminary version of these tools is available
37a4c940 283 at <http://www.gnu.org/software/acct/>.
1da177e4 284
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285config FHANDLE
286 bool "open by fhandle syscalls"
287 select EXPORTFS
288 help
289 If you say Y here, a user level program will be able to map
290 file names to handle and then later use the handle for
291 different file system operations. This is useful in implementing
292 userspace file servers, which now track files using handles instead
293 of names. The handle would remain the same even if file names
294 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
295 syscalls.
296
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297config TASKSTATS
298 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
299 depends on NET
300 default n
301 help
302 Export selected statistics for tasks/processes through the
303 generic netlink interface. Unlike BSD process accounting, the
304 statistics are available during the lifetime of tasks/processes as
305 responses to commands. Like BSD accounting, they are sent to user
306 space on task exit.
307
308 Say N if unsure.
309
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310config TASK_DELAY_ACCT
311 bool "Enable per-task delay accounting (EXPERIMENTAL)"
6f44993f 312 depends on TASKSTATS
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313 help
314 Collect information on time spent by a task waiting for system
315 resources like cpu, synchronous block I/O completion and swapping
316 in pages. Such statistics can help in setting a task's priorities
317 relative to other tasks for cpu, io, rss limits etc.
318
319 Say N if unsure.
320
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321config TASK_XACCT
322 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
323 depends on TASKSTATS
324 help
325 Collect extended task accounting data and send the data
326 to userland for processing over the taskstats interface.
327
328 Say N if unsure.
329
330config TASK_IO_ACCOUNTING
331 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
332 depends on TASK_XACCT
333 help
334 Collect information on the number of bytes of storage I/O which this
335 task has caused.
336
337 Say N if unsure.
338
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339config AUDIT
340 bool "Auditing support"
804a6a49 341 depends on NET
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342 help
343 Enable auditing infrastructure that can be used with another
344 kernel subsystem, such as SELinux (which requires this for
345 logging of avc messages output). Does not do system-call
346 auditing without CONFIG_AUDITSYSCALL.
347
348config AUDITSYSCALL
349 bool "Enable system-call auditing support"
022382a5 350 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
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351 default y if SECURITY_SELINUX
352 help
353 Enable low-overhead system-call auditing infrastructure that
354 can be used independently or with another kernel subsystem,
67640b60 355 such as SELinux.
1da177e4 356
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357config AUDIT_WATCH
358 def_bool y
359 depends on AUDITSYSCALL
360 select FSNOTIFY
1da177e4 361
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362config AUDIT_TREE
363 def_bool y
63c882a0 364 depends on AUDITSYSCALL
28a3a7eb 365 select FSNOTIFY
74c3cbe3 366
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367source "kernel/irq/Kconfig"
368
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369menu "RCU Subsystem"
370
371choice
372 prompt "RCU Implementation"
31c9a24e 373 default TREE_RCU
c903ff83 374
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375config TREE_RCU
376 bool "Tree-based hierarchical RCU"
687d7a96 377 depends on !PREEMPT && SMP
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378 help
379 This option selects the RCU implementation that is
380 designed for very large SMP system with hundreds or
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381 thousands of CPUs. It also scales down nicely to
382 smaller systems.
c903ff83 383
f41d911f 384config TREE_PREEMPT_RCU
a57eb940 385 bool "Preemptible tree-based hierarchical RCU"
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386 depends on PREEMPT
387 help
388 This option selects the RCU implementation that is
389 designed for very large SMP systems with hundreds or
390 thousands of CPUs, but for which real-time response
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391 is also required. It also scales down nicely to
392 smaller systems.
f41d911f 393
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394config TINY_RCU
395 bool "UP-only small-memory-footprint RCU"
396 depends on !SMP
397 help
398 This option selects the RCU implementation that is
399 designed for UP systems from which real-time response
400 is not required. This option greatly reduces the
401 memory footprint of RCU.
402
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403config TINY_PREEMPT_RCU
404 bool "Preemptible UP-only small-memory-footprint RCU"
405 depends on !SMP && PREEMPT
406 help
407 This option selects the RCU implementation that is designed
408 for real-time UP systems. This option greatly reduces the
409 memory footprint of RCU.
410
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411endchoice
412
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413config PREEMPT_RCU
414 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
415 help
416 This option enables preemptible-RCU code that is common between
417 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
418
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419config RCU_TRACE
420 bool "Enable tracing for RCU"
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421 help
422 This option provides tracing in RCU which presents stats
423 in debugfs for debugging RCU implementation.
424
425 Say Y here if you want to enable RCU tracing
426 Say N if you are unsure.
427
428config RCU_FANOUT
429 int "Tree-based hierarchical RCU fanout value"
430 range 2 64 if 64BIT
431 range 2 32 if !64BIT
f41d911f 432 depends on TREE_RCU || TREE_PREEMPT_RCU
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433 default 64 if 64BIT
434 default 32 if !64BIT
435 help
436 This option controls the fanout of hierarchical implementations
437 of RCU, allowing RCU to work efficiently on machines with
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438 large numbers of CPUs. This value must be at least the fourth
439 root of NR_CPUS, which allows NR_CPUS to be insanely large.
440 The default value of RCU_FANOUT should be used for production
441 systems, but if you are stress-testing the RCU implementation
442 itself, small RCU_FANOUT values allow you to test large-system
443 code paths on small(er) systems.
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444
445 Select a specific number if testing RCU itself.
446 Take the default if unsure.
447
448config RCU_FANOUT_EXACT
449 bool "Disable tree-based hierarchical RCU auto-balancing"
f41d911f 450 depends on TREE_RCU || TREE_PREEMPT_RCU
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451 default n
452 help
453 This option forces use of the exact RCU_FANOUT value specified,
454 regardless of imbalances in the hierarchy. This is useful for
455 testing RCU itself, and might one day be useful on systems with
456 strong NUMA behavior.
457
458 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
459
460 Say N if unsure.
461
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462config RCU_FAST_NO_HZ
463 bool "Accelerate last non-dyntick-idle CPU's grace periods"
464 depends on TREE_RCU && NO_HZ && SMP
465 default n
466 help
467 This option causes RCU to attempt to accelerate grace periods
468 in order to allow the final CPU to enter dynticks-idle state
469 more quickly. On the other hand, this option increases the
470 overhead of the dynticks-idle checking, particularly on systems
471 with large numbers of CPUs.
472
473 Say Y if energy efficiency is critically important, particularly
474 if you have relatively few CPUs.
475
476 Say N if you are unsure.
477
c903ff83 478config TREE_RCU_TRACE
f41d911f 479 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
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480 select DEBUG_FS
481 help
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482 This option provides tracing for the TREE_RCU and
483 TREE_PREEMPT_RCU implementations, permitting Makefile to
484 trivially select kernel/rcutree_trace.c.
c903ff83 485
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486config RCU_BOOST
487 bool "Enable RCU priority boosting"
488 depends on RT_MUTEXES && TINY_PREEMPT_RCU
489 default n
490 help
491 This option boosts the priority of preempted RCU readers that
492 block the current preemptible RCU grace period for too long.
493 This option also prevents heavy loads from blocking RCU
494 callback invocation for all flavors of RCU.
495
496 Say Y here if you are working with real-time apps or heavy loads
497 Say N here if you are unsure.
498
499config RCU_BOOST_PRIO
500 int "Real-time priority to boost RCU readers to"
501 range 1 99
502 depends on RCU_BOOST
503 default 1
504 help
505 This option specifies the real-time priority to which preempted
506 RCU readers are to be boosted. If you are working with CPU-bound
507 real-time applications, you should specify a priority higher then
508 the highest-priority CPU-bound application.
509
510 Specify the real-time priority, or take the default if unsure.
511
512config RCU_BOOST_DELAY
513 int "Milliseconds to delay boosting after RCU grace-period start"
514 range 0 3000
515 depends on RCU_BOOST
516 default 500
517 help
518 This option specifies the time to wait after the beginning of
519 a given grace period before priority-boosting preempted RCU
520 readers blocking that grace period. Note that any RCU reader
521 blocking an expedited RCU grace period is boosted immediately.
522
523 Accept the default if unsure.
524
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525endmenu # "RCU Subsystem"
526
1da177e4 527config IKCONFIG
f2443ab6 528 tristate "Kernel .config support"
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529 ---help---
530 This option enables the complete Linux kernel ".config" file
531 contents to be saved in the kernel. It provides documentation
532 of which kernel options are used in a running kernel or in an
533 on-disk kernel. This information can be extracted from the kernel
534 image file with the script scripts/extract-ikconfig and used as
535 input to rebuild the current kernel or to build another kernel.
536 It can also be extracted from a running kernel by reading
537 /proc/config.gz if enabled (below).
538
539config IKCONFIG_PROC
540 bool "Enable access to .config through /proc/config.gz"
541 depends on IKCONFIG && PROC_FS
542 ---help---
543 This option enables access to the kernel configuration file
544 through /proc/config.gz.
545
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546config LOG_BUF_SHIFT
547 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
548 range 12 21
f17a32e9 549 default 17
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550 help
551 Select kernel log buffer size as a power of 2.
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552 Examples:
553 17 => 128 KB
554 16 => 64 KB
555 15 => 32 KB
556 14 => 16 KB
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557 13 => 8 KB
558 12 => 4 KB
559
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560#
561# Architectures with an unreliable sched_clock() should select this:
562#
563config HAVE_UNSTABLE_SCHED_CLOCK
564 bool
565
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566menuconfig CGROUPS
567 boolean "Control Group support"
0dea1168 568 depends on EVENTFD
5cdc38f9 569 help
23964d2d 570 This option adds support for grouping sets of processes together, for
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571 use with process control subsystems such as Cpusets, CFS, memory
572 controls or device isolation.
573 See
5cdc38f9 574 - Documentation/scheduler/sched-design-CFS.txt (CFS)
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575 - Documentation/cgroups/ (features for grouping, isolation
576 and resource control)
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577
578 Say N if unsure.
579
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580if CGROUPS
581
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582config CGROUP_DEBUG
583 bool "Example debug cgroup subsystem"
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584 default n
585 help
586 This option enables a simple cgroup subsystem that
587 exports useful debugging information about the cgroups
23964d2d 588 framework.
5cdc38f9 589
23964d2d 590 Say N if unsure.
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591
592config CGROUP_NS
23964d2d 593 bool "Namespace cgroup subsystem"
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594 help
595 Provides a simple namespace cgroup subsystem to
596 provide hierarchical naming of sets of namespaces,
597 for instance virtual servers and checkpoint/restart
598 jobs.
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599
600config CGROUP_FREEZER
23964d2d 601 bool "Freezer cgroup subsystem"
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602 help
603 Provides a way to freeze and unfreeze all tasks in a
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604 cgroup.
605
606config CGROUP_DEVICE
607 bool "Device controller for cgroups"
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608 help
609 Provides a cgroup implementing whitelists for devices which
610 a process in the cgroup can mknod or open.
611
612config CPUSETS
613 bool "Cpuset support"
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614 help
615 This option will let you create and manage CPUSETs which
616 allow dynamically partitioning a system into sets of CPUs and
617 Memory Nodes and assigning tasks to run only within those sets.
618 This is primarily useful on large SMP or NUMA systems.
619
620 Say N if unsure.
621
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622config PROC_PID_CPUSET
623 bool "Include legacy /proc/<pid>/cpuset file"
624 depends on CPUSETS
625 default y
626
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627config CGROUP_CPUACCT
628 bool "Simple CPU accounting cgroup subsystem"
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629 help
630 Provides a simple Resource Controller for monitoring the
23964d2d 631 total CPU consumed by the tasks in a cgroup.
d842de87 632
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633config RESOURCE_COUNTERS
634 bool "Resource counters"
635 help
636 This option enables controller independent resource accounting
23964d2d 637 infrastructure that works with cgroups.
e552b661 638
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639config CGROUP_MEM_RES_CTLR
640 bool "Memory Resource Controller for Control Groups"
79ae9c29 641 depends on RESOURCE_COUNTERS
cf475ad2 642 select MM_OWNER
00f0b825 643 help
84ad6d70 644 Provides a memory resource controller that manages both anonymous
21acb9ca 645 memory and page cache. (See Documentation/cgroups/memory.txt)
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646
647 Note that setting this option increases fixed memory overhead
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648 associated with each page of memory in the system. By this,
649 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
650 usage tracking struct at boot. Total amount of this is printed out
651 at boot.
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652
653 Only enable when you're ok with these trade offs and really
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654 sure you need the memory resource controller. Even when you enable
655 this, you can set "cgroup_disable=memory" at your boot option to
656 disable memory resource controller and you can avoid overheads.
c9d5409f 657 (and lose benefits of memory resource controller)
00f0b825 658
cf475ad2
BS
659 This config option also selects MM_OWNER config option, which
660 could in turn add some fork/exit overhead.
661
c077719b 662config CGROUP_MEM_RES_CTLR_SWAP
65e0e811
KH
663 bool "Memory Resource Controller Swap Extension"
664 depends on CGROUP_MEM_RES_CTLR && SWAP
c077719b
KH
665 help
666 Add swap management feature to memory resource controller. When you
667 enable this, you can limit mem+swap usage per cgroup. In other words,
668 when you disable this, memory resource controller has no cares to
669 usage of swap...a process can exhaust all of the swap. This extension
670 is useful when you want to avoid exhaustion swap but this itself
671 adds more overheads and consumes memory for remembering information.
672 Especially if you use 32bit system or small memory system, please
673 be careful about enabling this. When memory resource controller
674 is disabled by boot option, this will be automatically disabled and
675 there will be no overhead from this. Even when you set this config=y,
676 if boot option "noswapaccount" is set, swap will not be accounted.
627991a2
KH
677 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
678 size is 4096bytes, 512k per 1Gbytes of swap.
a42c390c
MH
679config CGROUP_MEM_RES_CTLR_SWAP_ENABLED
680 bool "Memory Resource Controller Swap Extension enabled by default"
681 depends on CGROUP_MEM_RES_CTLR_SWAP
682 default y
683 help
684 Memory Resource Controller Swap Extension comes with its price in
685 a bigger memory consumption. General purpose distribution kernels
43d547f9 686 which want to enable the feature but keep it disabled by default
a42c390c
MH
687 and let the user enable it by swapaccount boot command line
688 parameter should have this option unselected.
689 For those who want to have the feature enabled by default should
690 select this option (if, for some reason, they need to disable it
691 then noswapaccount does the trick).
c077719b 692
e5d1367f
SE
693config CGROUP_PERF
694 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
695 depends on PERF_EVENTS && CGROUPS
696 help
697 This option extends the per-cpu mode to restrict monitoring to
2d0f2520 698 threads which belong to the cgroup specified and run on the
e5d1367f
SE
699 designated cpu.
700
701 Say N if unsure.
702
7c941438
DG
703menuconfig CGROUP_SCHED
704 bool "Group CPU scheduler"
79ae9c29 705 depends on EXPERIMENTAL
7c941438
DG
706 default n
707 help
708 This feature lets CPU scheduler recognize task groups and control CPU
709 bandwidth allocation to such task groups. It uses cgroups to group
710 tasks.
711
712if CGROUP_SCHED
713config FAIR_GROUP_SCHED
714 bool "Group scheduling for SCHED_OTHER"
715 depends on CGROUP_SCHED
716 default CGROUP_SCHED
717
718config RT_GROUP_SCHED
719 bool "Group scheduling for SCHED_RR/FIFO"
720 depends on EXPERIMENTAL
721 depends on CGROUP_SCHED
722 default n
723 help
724 This feature lets you explicitly allocate real CPU bandwidth
32bd7eb5 725 to task groups. If enabled, it will also make it impossible to
7c941438
DG
726 schedule realtime tasks for non-root users until you allocate
727 realtime bandwidth for them.
728 See Documentation/scheduler/sched-rt-group.txt for more information.
729
730endif #CGROUP_SCHED
731
afc24d49
VG
732config BLK_CGROUP
733 tristate "Block IO controller"
79ae9c29 734 depends on BLOCK
afc24d49
VG
735 default n
736 ---help---
737 Generic block IO controller cgroup interface. This is the common
738 cgroup interface which should be used by various IO controlling
739 policies.
740
741 Currently, CFQ IO scheduler uses it to recognize task groups and
742 control disk bandwidth allocation (proportional time slice allocation)
e43473b7
VG
743 to such task groups. It is also used by bio throttling logic in
744 block layer to implement upper limit in IO rates on a device.
afc24d49
VG
745
746 This option only enables generic Block IO controller infrastructure.
e43473b7 747 One needs to also enable actual IO controlling logic/policy. For
79e2e759
MW
748 enabling proportional weight division of disk bandwidth in CFQ, set
749 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
c5e0591a 750 CONFIG_BLK_DEV_THROTTLING=y.
afc24d49
VG
751
752 See Documentation/cgroups/blkio-controller.txt for more information.
753
754config DEBUG_BLK_CGROUP
755 bool "Enable Block IO controller debugging"
756 depends on BLK_CGROUP
757 default n
758 ---help---
759 Enable some debugging help. Currently it exports additional stat
760 files in a cgroup which can be useful for debugging.
761
23964d2d 762endif # CGROUPS
c077719b 763
8dd2a82c 764menuconfig NAMESPACES
6a108a14
DR
765 bool "Namespaces support" if EXPERT
766 default !EXPERT
c5289a69
PE
767 help
768 Provides the way to make tasks work with different objects using
769 the same id. For example same IPC id may refer to different objects
770 or same user id or pid may refer to different tasks when used in
771 different namespaces.
772
8dd2a82c
DL
773if NAMESPACES
774
58bfdd6d
PE
775config UTS_NS
776 bool "UTS namespace"
17a6d441 777 default y
58bfdd6d
PE
778 help
779 In this namespace tasks see different info provided with the
780 uname() system call
781
ae5e1b22
PE
782config IPC_NS
783 bool "IPC namespace"
8dd2a82c 784 depends on (SYSVIPC || POSIX_MQUEUE)
17a6d441 785 default y
ae5e1b22
PE
786 help
787 In this namespace tasks work with IPC ids which correspond to
614b84cf 788 different IPC objects in different namespaces.
ae5e1b22 789
aee16ce7
PE
790config USER_NS
791 bool "User namespace (EXPERIMENTAL)"
8dd2a82c 792 depends on EXPERIMENTAL
17a6d441 793 default y
aee16ce7
PE
794 help
795 This allows containers, i.e. vservers, to use user namespaces
796 to provide different user info for different servers.
797 If unsure, say N.
798
74bd59bb 799config PID_NS
9bd38c2c 800 bool "PID Namespaces"
17a6d441 801 default y
74bd59bb 802 help
12d2b8f9 803 Support process id namespaces. This allows having multiple
692105b8 804 processes with the same pid as long as they are in different
74bd59bb
PE
805 pid namespaces. This is a building block of containers.
806
d6eb633f
MH
807config NET_NS
808 bool "Network namespace"
8dd2a82c 809 depends on NET
17a6d441 810 default y
d6eb633f
MH
811 help
812 Allow user space to create what appear to be multiple instances
813 of the network stack.
814
8dd2a82c
DL
815endif # NAMESPACES
816
5091faa4
MG
817config SCHED_AUTOGROUP
818 bool "Automatic process group scheduling"
819 select EVENTFD
820 select CGROUPS
821 select CGROUP_SCHED
822 select FAIR_GROUP_SCHED
823 help
824 This option optimizes the scheduler for common desktop workloads by
825 automatically creating and populating task groups. This separation
826 of workloads isolates aggressive CPU burners (like build jobs) from
827 desktop applications. Task group autogeneration is currently based
828 upon task session.
829
317f3941
PZ
830config SCHED_TTWU_QUEUE
831 bool
832 depends on !SPARC32
833 default y
834
7af37bec
DL
835config MM_OWNER
836 bool
837
838config SYSFS_DEPRECATED
5d6a4ea5 839 bool "Enable deprecated sysfs features to support old userspace tools"
7af37bec
DL
840 depends on SYSFS
841 default n
842 help
843 This option adds code that switches the layout of the "block" class
844 devices, to not show up in /sys/class/block/, but only in
845 /sys/block/.
846
847 This switch is only active when the sysfs.deprecated=1 boot option is
848 passed or the SYSFS_DEPRECATED_V2 option is set.
849
850 This option allows new kernels to run on old distributions and tools,
851 which might get confused by /sys/class/block/. Since 2007/2008 all
852 major distributions and tools handle this just fine.
853
854 Recent distributions and userspace tools after 2009/2010 depend on
855 the existence of /sys/class/block/, and will not work with this
856 option enabled.
857
858 Only if you are using a new kernel on an old distribution, you might
859 need to say Y here.
860
861config SYSFS_DEPRECATED_V2
5d6a4ea5 862 bool "Enable deprecated sysfs features by default"
7af37bec
DL
863 default n
864 depends on SYSFS
865 depends on SYSFS_DEPRECATED
866 help
867 Enable deprecated sysfs by default.
868
869 See the CONFIG_SYSFS_DEPRECATED option for more details about this
870 option.
871
872 Only if you are using a new kernel on an old distribution, you might
873 need to say Y here. Even then, odds are you would not need it
874 enabled, you can always pass the boot option if absolutely necessary.
875
876config RELAY
877 bool "Kernel->user space relay support (formerly relayfs)"
878 help
879 This option enables support for relay interface support in
880 certain file systems (such as debugfs).
881 It is designed to provide an efficient mechanism for tools and
882 facilities to relay large amounts of data from kernel space to
883 user space.
884
885 If unsure, say N.
886
f991633d
DG
887config BLK_DEV_INITRD
888 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
889 depends on BROKEN || !FRV
890 help
891 The initial RAM filesystem is a ramfs which is loaded by the
892 boot loader (loadlin or lilo) and that is mounted as root
893 before the normal boot procedure. It is typically used to
894 load modules needed to mount the "real" root file system,
895 etc. See <file:Documentation/initrd.txt> for details.
896
897 If RAM disk support (BLK_DEV_RAM) is also included, this
898 also enables initial RAM disk (initrd) support and adds
899 15 Kbytes (more on some other architectures) to the kernel size.
900
901 If unsure say Y.
902
c33df4ea
JPS
903if BLK_DEV_INITRD
904
dbec4866
SR
905source "usr/Kconfig"
906
c33df4ea
JPS
907endif
908
c45b4f1f 909config CC_OPTIMIZE_FOR_SIZE
96fffeb4 910 bool "Optimize for size"
c45b4f1f 911 default y
c45b4f1f
LT
912 help
913 Enabling this option will pass "-Os" instead of "-O2" to gcc
914 resulting in a smaller kernel.
915
775a7229 916 If unsure, say Y.
c45b4f1f 917
0847062a
RD
918config SYSCTL
919 bool
920
b943c460
RD
921config ANON_INODES
922 bool
923
6a108a14
DR
924menuconfig EXPERT
925 bool "Configure standard kernel features (expert users)"
1da177e4
LT
926 help
927 This option allows certain base kernel options and settings
928 to be disabled or tweaked. This is for specialized
929 environments which can tolerate a "non-standard" kernel.
930 Only use this if you really know what you are doing.
931
ae81f9e3 932config UID16
6a108a14 933 bool "Enable 16-bit UID system calls" if EXPERT
09337f50 934 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
ae81f9e3
CE
935 default y
936 help
937 This enables the legacy 16-bit UID syscall wrappers.
938
b89a8171 939config SYSCTL_SYSCALL
6a108a14 940 bool "Sysctl syscall support" if EXPERT
26a7034b 941 depends on PROC_SYSCTL
13bb7e37 942 default y
b89a8171 943 select SYSCTL
ae81f9e3 944 ---help---
13bb7e37
EB
945 sys_sysctl uses binary paths that have been found challenging
946 to properly maintain and use. The interface in /proc/sys
947 using paths with ascii names is now the primary path to this
948 information.
b89a8171 949
13bb7e37
EB
950 Almost nothing using the binary sysctl interface so if you are
951 trying to save some space it is probably safe to disable this,
952 making your kernel marginally smaller.
b89a8171 953
13bb7e37 954 If unsure say Y here.
ae81f9e3 955
1da177e4 956config KALLSYMS
6a108a14 957 bool "Load all symbols for debugging/ksymoops" if EXPERT
1da177e4
LT
958 default y
959 help
960 Say Y here to let the kernel print out symbolic crash information and
961 symbolic stack backtraces. This increases the size of the kernel
962 somewhat, as all symbols have to be loaded into the kernel image.
963
964config KALLSYMS_ALL
965 bool "Include all symbols in kallsyms"
966 depends on DEBUG_KERNEL && KALLSYMS
967 help
968 Normally kallsyms only contains the symbols of functions, for nicer
969 OOPS messages. Some debuggers can use kallsyms for other
f9f97bc0
JJ
970 symbols too: say Y here to include all symbols, if you need them
971 and you don't care about adding 300k to the size of your kernel.
1da177e4
LT
972
973 Say N.
974
975config KALLSYMS_EXTRA_PASS
976 bool "Do an extra kallsyms pass"
977 depends on KALLSYMS
978 help
979 If kallsyms is not working correctly, the build will fail with
980 inconsistent kallsyms data. If that occurs, log a bug report and
981 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
982 Always say N here unless you find a bug in kallsyms, which must be
983 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
984 you wait for kallsyms to be fixed.
985
d59745ce 986
712f47ce 987config HOTPLUG
6a108a14 988 bool "Support for hot-pluggable devices" if EXPERT
712f47ce
GKH
989 default y
990 help
991 This option is provided for the case where no hotplug or uevent
992 capabilities is wanted by the kernel. You should only consider
993 disabling this option for embedded systems that do not use modules, a
994 dynamic /dev tree, or dynamic device discovery. Just say Y.
995
d59745ce
MM
996config PRINTK
997 default y
6a108a14 998 bool "Enable support for printk" if EXPERT
d59745ce
MM
999 help
1000 This option enables normal printk support. Removing it
1001 eliminates most of the message strings from the kernel image
1002 and makes the kernel more or less silent. As this makes it
1003 very difficult to diagnose system problems, saying N here is
1004 strongly discouraged.
1005
c8538a7a 1006config BUG
6a108a14 1007 bool "BUG() support" if EXPERT
c8538a7a
MM
1008 default y
1009 help
1010 Disabling this option eliminates support for BUG and WARN, reducing
1011 the size of your kernel image and potentially quietly ignoring
1012 numerous fatal conditions. You should only consider disabling this
1013 option for embedded systems with no facilities for reporting errors.
1014 Just say Y.
1015
708e9a79
MM
1016config ELF_CORE
1017 default y
6a108a14 1018 bool "Enable ELF core dumps" if EXPERT
708e9a79
MM
1019 help
1020 Enable support for generating core dumps. Disabling saves about 4k.
1021
e5e1d3cb 1022config PCSPKR_PLATFORM
6a108a14 1023 bool "Enable PC-Speaker support" if EXPERT
e5e1d3cb
SS
1024 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
1025 default y
1026 help
1027 This option allows to disable the internal PC-Speaker
1028 support, saving some memory.
1029
1da177e4
LT
1030config BASE_FULL
1031 default y
6a108a14 1032 bool "Enable full-sized data structures for core" if EXPERT
1da177e4
LT
1033 help
1034 Disabling this option reduces the size of miscellaneous core
1035 kernel data structures. This saves memory on small machines,
1036 but may reduce performance.
1037
1038config FUTEX
6a108a14 1039 bool "Enable futex support" if EXPERT
1da177e4 1040 default y
23f78d4a 1041 select RT_MUTEXES
1da177e4
LT
1042 help
1043 Disabling this option will cause the kernel to be built without
1044 support for "fast userspace mutexes". The resulting kernel may not
1045 run glibc-based applications correctly.
1046
1047config EPOLL
6a108a14 1048 bool "Enable eventpoll support" if EXPERT
1da177e4 1049 default y
448e3cee 1050 select ANON_INODES
1da177e4
LT
1051 help
1052 Disabling this option will cause the kernel to be built without
1053 support for epoll family of system calls.
1054
fba2afaa 1055config SIGNALFD
6a108a14 1056 bool "Enable signalfd() system call" if EXPERT
448e3cee 1057 select ANON_INODES
fba2afaa
DL
1058 default y
1059 help
1060 Enable the signalfd() system call that allows to receive signals
1061 on a file descriptor.
1062
1063 If unsure, say Y.
1064
b215e283 1065config TIMERFD
6a108a14 1066 bool "Enable timerfd() system call" if EXPERT
448e3cee 1067 select ANON_INODES
b215e283
DL
1068 default y
1069 help
1070 Enable the timerfd() system call that allows to receive timer
1071 events on a file descriptor.
1072
1073 If unsure, say Y.
1074
e1ad7468 1075config EVENTFD
6a108a14 1076 bool "Enable eventfd() system call" if EXPERT
448e3cee 1077 select ANON_INODES
e1ad7468
DL
1078 default y
1079 help
1080 Enable the eventfd() system call that allows to receive both
1081 kernel notification (ie. KAIO) or userspace notifications.
1082
1083 If unsure, say Y.
1084
1da177e4 1085config SHMEM
6a108a14 1086 bool "Use full shmem filesystem" if EXPERT
1da177e4
LT
1087 default y
1088 depends on MMU
1089 help
1090 The shmem is an internal filesystem used to manage shared memory.
1091 It is backed by swap and manages resource limits. It is also exported
1092 to userspace as tmpfs if TMPFS is enabled. Disabling this
1093 option replaces shmem and tmpfs with the much simpler ramfs code,
1094 which may be appropriate on small systems without swap.
1095
ebf3f09c 1096config AIO
6a108a14 1097 bool "Enable AIO support" if EXPERT
ebf3f09c
TP
1098 default y
1099 help
1100 This option enables POSIX asynchronous I/O which may by used
1101 by some high performance threaded applications. Disabling
1102 this option saves about 7k.
1103
6befe5f6
RD
1104config EMBEDDED
1105 bool "Embedded system"
1106 select EXPERT
1107 help
1108 This option should be enabled if compiling the kernel for
1109 an embedded system so certain expert options are available
1110 for configuration.
1111
cdd6c482 1112config HAVE_PERF_EVENTS
0793a61d 1113 bool
018df72d
MF
1114 help
1115 See tools/perf/design.txt for details.
0793a61d 1116
906010b2
PZ
1117config PERF_USE_VMALLOC
1118 bool
1119 help
1120 See tools/perf/design.txt for details
1121
57c0c15b 1122menu "Kernel Performance Events And Counters"
0793a61d 1123
cdd6c482 1124config PERF_EVENTS
57c0c15b
IM
1125 bool "Kernel performance events and counters"
1126 default y if (PROFILING || PERF_COUNTERS)
cdd6c482 1127 depends on HAVE_PERF_EVENTS
4c59e467 1128 select ANON_INODES
e360adbe 1129 select IRQ_WORK
0793a61d 1130 help
57c0c15b
IM
1131 Enable kernel support for various performance events provided
1132 by software and hardware.
0793a61d 1133
dd77038d 1134 Software events are supported either built-in or via the
57c0c15b 1135 use of generic tracepoints.
0793a61d 1136
57c0c15b
IM
1137 Most modern CPUs support performance events via performance
1138 counter registers. These registers count the number of certain
0793a61d
TG
1139 types of hw events: such as instructions executed, cachemisses
1140 suffered, or branches mis-predicted - without slowing down the
1141 kernel or applications. These registers can also trigger interrupts
1142 when a threshold number of events have passed - and can thus be
1143 used to profile the code that runs on that CPU.
1144
57c0c15b 1145 The Linux Performance Event subsystem provides an abstraction of
dd77038d 1146 these software and hardware event capabilities, available via a
57c0c15b 1147 system call and used by the "perf" utility in tools/perf/. It
0793a61d
TG
1148 provides per task and per CPU counters, and it provides event
1149 capabilities on top of those.
1150
1151 Say Y if unsure.
1152
57c0c15b
IM
1153config PERF_COUNTERS
1154 bool "Kernel performance counters (old config option)"
1155 depends on HAVE_PERF_EVENTS
1156 help
1157 This config has been obsoleted by the PERF_EVENTS
1158 config option - please see that one for details.
1159
1160 It has no effect on the kernel whether you enable
1161 it or not, it is a compatibility placeholder.
1162
1163 Say N if unsure.
1164
906010b2
PZ
1165config DEBUG_PERF_USE_VMALLOC
1166 default n
1167 bool "Debug: use vmalloc to back perf mmap() buffers"
1168 depends on PERF_EVENTS && DEBUG_KERNEL
1169 select PERF_USE_VMALLOC
1170 help
1171 Use vmalloc memory to back perf mmap() buffers.
1172
1173 Mostly useful for debugging the vmalloc code on platforms
1174 that don't require it.
1175
1176 Say N if unsure.
1177
0793a61d
TG
1178endmenu
1179
f8891e5e
CL
1180config VM_EVENT_COUNTERS
1181 default y
6a108a14 1182 bool "Enable VM event counters for /proc/vmstat" if EXPERT
f8891e5e 1183 help
2aea4fb6
PJ
1184 VM event counters are needed for event counts to be shown.
1185 This option allows the disabling of the VM event counters
6a108a14 1186 on EXPERT systems. /proc/vmstat will only show page counts
2aea4fb6 1187 if VM event counters are disabled.
f8891e5e 1188
3d137310
TP
1189config PCI_QUIRKS
1190 default y
6a108a14 1191 bool "Enable PCI quirk workarounds" if EXPERT
61cfc7e4 1192 depends on PCI
3d137310
TP
1193 help
1194 This enables workarounds for various PCI chipset
1195 bugs/quirks. Disable this only if your target machine is
1196 unaffected by PCI quirks.
1197
41ecc55b
CL
1198config SLUB_DEBUG
1199 default y
6a108a14 1200 bool "Enable SLUB debugging support" if EXPERT
f6acb635 1201 depends on SLUB && SYSFS
41ecc55b
CL
1202 help
1203 SLUB has extensive debug support features. Disabling these can
1204 result in significant savings in code size. This also disables
1205 SLUB sysfs support. /sys/slab will not exist and there will be
1206 no support for cache validation etc.
1207
b943c460
RD
1208config COMPAT_BRK
1209 bool "Disable heap randomization"
1210 default y
1211 help
1212 Randomizing heap placement makes heap exploits harder, but it
1213 also breaks ancient binaries (including anything libc5 based).
1214 This option changes the bootup default to heap randomization
692105b8 1215 disabled, and can be overridden at runtime by setting
b943c460
RD
1216 /proc/sys/kernel/randomize_va_space to 2.
1217
1218 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1219
81819f0f
CL
1220choice
1221 prompt "Choose SLAB allocator"
a0acd820 1222 default SLUB
81819f0f
CL
1223 help
1224 This option allows to select a slab allocator.
1225
1226config SLAB
1227 bool "SLAB"
1228 help
1229 The regular slab allocator that is established and known to work
34013886 1230 well in all environments. It organizes cache hot objects in
02f56210 1231 per cpu and per node queues.
81819f0f
CL
1232
1233config SLUB
81819f0f
CL
1234 bool "SLUB (Unqueued Allocator)"
1235 help
1236 SLUB is a slab allocator that minimizes cache line usage
1237 instead of managing queues of cached objects (SLAB approach).
1238 Per cpu caching is realized using slabs of objects instead
1239 of queues of objects. SLUB can use memory efficiently
02f56210
SA
1240 and has enhanced diagnostics. SLUB is the default choice for
1241 a slab allocator.
81819f0f
CL
1242
1243config SLOB
6a108a14 1244 depends on EXPERT
81819f0f
CL
1245 bool "SLOB (Simple Allocator)"
1246 help
37291458
MM
1247 SLOB replaces the stock allocator with a drastically simpler
1248 allocator. SLOB is generally more space efficient but
1249 does not perform as well on large systems.
81819f0f
CL
1250
1251endchoice
1252
ea637639
JZ
1253config MMAP_ALLOW_UNINITIALIZED
1254 bool "Allow mmapped anonymous memory to be uninitialized"
6a108a14 1255 depends on EXPERT && !MMU
ea637639
JZ
1256 default n
1257 help
1258 Normally, and according to the Linux spec, anonymous memory obtained
1259 from mmap() has it's contents cleared before it is passed to
1260 userspace. Enabling this config option allows you to request that
1261 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1262 providing a huge performance boost. If this option is not enabled,
1263 then the flag will be ignored.
1264
1265 This is taken advantage of by uClibc's malloc(), and also by
1266 ELF-FDPIC binfmt's brk and stack allocator.
1267
1268 Because of the obvious security issues, this option should only be
1269 enabled on embedded devices where you control what is run in
1270 userspace. Since that isn't generally a problem on no-MMU systems,
1271 it is normally safe to say Y here.
1272
1273 See Documentation/nommu-mmap.txt for more information.
1274
125e5645 1275config PROFILING
b309a294 1276 bool "Profiling support"
125e5645
MD
1277 help
1278 Say Y here to enable the extended profiling support mechanisms used
1279 by profilers such as OProfile.
1280
5f87f112
IM
1281#
1282# Place an empty function call at each tracepoint site. Can be
1283# dynamically changed for a probe function.
1284#
97e1c18e 1285config TRACEPOINTS
5f87f112 1286 bool
97e1c18e 1287
fb32e03f
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1288source "arch/Kconfig"
1289
1da177e4
LT
1290endmenu # General setup
1291
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DB
1292config HAVE_GENERIC_DMA_COHERENT
1293 bool
1294 default n
1295
158a9624
LT
1296config SLABINFO
1297 bool
1298 depends on PROC_FS
0f389ec6 1299 depends on SLAB || SLUB_DEBUG
158a9624
LT
1300 default y
1301
ae81f9e3
CE
1302config RT_MUTEXES
1303 boolean
ae81f9e3 1304
1da177e4
LT
1305config BASE_SMALL
1306 int
1307 default 0 if BASE_FULL
1308 default 1 if !BASE_FULL
1309
66da5733 1310menuconfig MODULES
1da177e4
LT
1311 bool "Enable loadable module support"
1312 help
1313 Kernel modules are small pieces of compiled code which can
1314 be inserted in the running kernel, rather than being
1315 permanently built into the kernel. You use the "modprobe"
1316 tool to add (and sometimes remove) them. If you say Y here,
1317 many parts of the kernel can be built as modules (by
1318 answering M instead of Y where indicated): this is most
1319 useful for infrequently used options which are not required
1320 for booting. For more information, see the man pages for
1321 modprobe, lsmod, modinfo, insmod and rmmod.
1322
1323 If you say Y here, you will need to run "make
1324 modules_install" to put the modules under /lib/modules/
1325 where modprobe can find them (you may need to be root to do
1326 this).
1327
1328 If unsure, say Y.
1329
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RD
1330if MODULES
1331
826e4506
LT
1332config MODULE_FORCE_LOAD
1333 bool "Forced module loading"
826e4506
LT
1334 default n
1335 help
91e37a79
RR
1336 Allow loading of modules without version information (ie. modprobe
1337 --force). Forced module loading sets the 'F' (forced) taint flag and
1338 is usually a really bad idea.
826e4506 1339
1da177e4
LT
1340config MODULE_UNLOAD
1341 bool "Module unloading"
1da177e4
LT
1342 help
1343 Without this option you will not be able to unload any
1344 modules (note that some modules may not be unloadable
f7f5b675
DV
1345 anyway), which makes your kernel smaller, faster
1346 and simpler. If unsure, say Y.
1da177e4
LT
1347
1348config MODULE_FORCE_UNLOAD
1349 bool "Forced module unloading"
1350 depends on MODULE_UNLOAD && EXPERIMENTAL
1351 help
1352 This option allows you to force a module to unload, even if the
1353 kernel believes it is unsafe: the kernel will remove the module
1354 without waiting for anyone to stop using it (using the -f option to
1355 rmmod). This is mainly for kernel developers and desperate users.
1356 If unsure, say N.
1357
1da177e4 1358config MODVERSIONS
0d541643 1359 bool "Module versioning support"
1da177e4
LT
1360 help
1361 Usually, you have to use modules compiled with your kernel.
1362 Saying Y here makes it sometimes possible to use modules
1363 compiled for different kernels, by adding enough information
1364 to the modules to (hopefully) spot any changes which would
1365 make them incompatible with the kernel you are running. If
1366 unsure, say N.
1367
1368config MODULE_SRCVERSION_ALL
1369 bool "Source checksum for all modules"
1da177e4
LT
1370 help
1371 Modules which contain a MODULE_VERSION get an extra "srcversion"
1372 field inserted into their modinfo section, which contains a
1373 sum of the source files which made it. This helps maintainers
1374 see exactly which source was used to build a module (since
1375 others sometimes change the module source without updating
1376 the version). With this option, such a "srcversion" field
1377 will be created for all modules. If unsure, say N.
1378
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RD
1379endif # MODULES
1380
98a79d6a
RR
1381config INIT_ALL_POSSIBLE
1382 bool
1383 help
1384 Back when each arch used to define their own cpu_online_map and
1385 cpu_possible_map, some of them chose to initialize cpu_possible_map
1386 with all 1s, and others with all 0s. When they were centralised,
1387 it was better to provide this option than to break all the archs
692105b8 1388 and have several arch maintainers pursuing me down dark alleys.
98a79d6a 1389
1da177e4
LT
1390config STOP_MACHINE
1391 bool
1392 default y
1393 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1394 help
1395 Need stop_machine() primitive.
3a65dfe8 1396
3a65dfe8 1397source "block/Kconfig"
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1398
1399config PREEMPT_NOTIFIERS
1400 bool
e260be67 1401
16295bec
SK
1402config PADATA
1403 depends on SMP
1404 bool
1405
6beb0009 1406source "kernel/Kconfig.locks"
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