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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
b99b87f7 22
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23config HAVE_IRQ_WORK
24 bool
25
26config IRQ_WORK
27 bool
28 depends on HAVE_IRQ_WORK
29
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30config BUILDTIME_EXTABLE_SORT
31 bool
32
ff0cfc66 33menu "General setup"
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34
35config EXPERIMENTAL
36 bool "Prompt for development and/or incomplete code/drivers"
37 ---help---
38 Some of the various things that Linux supports (such as network
39 drivers, file systems, network protocols, etc.) can be in a state
40 of development where the functionality, stability, or the level of
41 testing is not yet high enough for general use. This is usually
42 known as the "alpha-test" phase among developers. If a feature is
43 currently in alpha-test, then the developers usually discourage
44 uninformed widespread use of this feature by the general public to
45 avoid "Why doesn't this work?" type mail messages. However, active
46 testing and use of these systems is welcomed. Just be aware that it
47 may not meet the normal level of reliability or it may fail to work
48 in some special cases. Detailed bug reports from people familiar
49 with the kernel internals are usually welcomed by the developers
50 (before submitting bug reports, please read the documents
51 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
52 <file:Documentation/BUG-HUNTING>, and
53 <file:Documentation/oops-tracing.txt> in the kernel source).
54
55 This option will also make obsoleted drivers available. These are
56 drivers that have been replaced by something else, and/or are
57 scheduled to be removed in a future kernel release.
58
59 Unless you intend to help test and develop a feature or driver that
60 falls into this category, or you have a situation that requires
61 using these features, you should probably say N here, which will
62 cause the configurator to present you with fewer choices. If
63 you say Y here, you will be offered the choice of using features or
64 drivers that are currently considered to be in the alpha-test phase.
65
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66config BROKEN
67 bool
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68
69config BROKEN_ON_SMP
70 bool
71 depends on BROKEN || !SMP
72 default y
73
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74config INIT_ENV_ARG_LIMIT
75 int
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76 default 32 if !UML
77 default 128 if UML
1da177e4 78 help
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79 Maximum of each of the number of arguments and environment
80 variables passed to init from the kernel command line.
1da177e4 81
1da177e4 82
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83config CROSS_COMPILE
84 string "Cross-compiler tool prefix"
85 help
86 Same as running 'make CROSS_COMPILE=prefix-' but stored for
87 default make runs in this kernel build directory. You don't
88 need to set this unless you want the configured kernel build
89 directory to select the cross-compiler automatically.
90
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91config LOCALVERSION
92 string "Local version - append to kernel release"
93 help
94 Append an extra string to the end of your kernel version.
95 This will show up when you type uname, for example.
96 The string you set here will be appended after the contents of
97 any files with a filename matching localversion* in your
98 object and source tree, in that order. Your total string can
99 be a maximum of 64 characters.
100
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101config LOCALVERSION_AUTO
102 bool "Automatically append version information to the version string"
103 default y
104 help
105 This will try to automatically determine if the current tree is a
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106 release tree by looking for git tags that belong to the current
107 top of tree revision.
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108
109 A string of the format -gxxxxxxxx will be added to the localversion
6e5a5420 110 if a git-based tree is found. The string generated by this will be
aaebf433 111 appended after any matching localversion* files, and after the value
6e5a5420 112 set in CONFIG_LOCALVERSION.
aaebf433 113
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114 (The actual string used here is the first eight characters produced
115 by running the command:
116
117 $ git rev-parse --verify HEAD
118
119 which is done within the script "scripts/setlocalversion".)
aaebf433 120
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121config HAVE_KERNEL_GZIP
122 bool
123
124config HAVE_KERNEL_BZIP2
125 bool
126
127config HAVE_KERNEL_LZMA
128 bool
129
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130config HAVE_KERNEL_XZ
131 bool
132
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133config HAVE_KERNEL_LZO
134 bool
135
30d65dbf 136choice
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137 prompt "Kernel compression mode"
138 default KERNEL_GZIP
3ebe1243 139 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
2e9f3bdd 140 help
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141 The linux kernel is a kind of self-extracting executable.
142 Several compression algorithms are available, which differ
143 in efficiency, compression and decompression speed.
144 Compression speed is only relevant when building a kernel.
145 Decompression speed is relevant at each boot.
146
147 If you have any problems with bzip2 or lzma compressed
148 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
149 version of this functionality (bzip2 only), for 2.4, was
150 supplied by Christian Ludwig)
151
152 High compression options are mostly useful for users, who
153 are low on disk space (embedded systems), but for whom ram
154 size matters less.
155
156 If in doubt, select 'gzip'
157
158config KERNEL_GZIP
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159 bool "Gzip"
160 depends on HAVE_KERNEL_GZIP
161 help
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162 The old and tried gzip compression. It provides a good balance
163 between compression ratio and decompression speed.
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164
165config KERNEL_BZIP2
166 bool "Bzip2"
2e9f3bdd 167 depends on HAVE_KERNEL_BZIP2
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168 help
169 Its compression ratio and speed is intermediate.
0a4dd35c 170 Decompression speed is slowest among the choices. The kernel
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171 size is about 10% smaller with bzip2, in comparison to gzip.
172 Bzip2 uses a large amount of memory. For modern kernels you
173 will need at least 8MB RAM or more for booting.
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174
175config KERNEL_LZMA
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176 bool "LZMA"
177 depends on HAVE_KERNEL_LZMA
178 help
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179 This compression algorithm's ratio is best. Decompression speed
180 is between gzip and bzip2. Compression is slowest.
181 The kernel size is about 33% smaller with LZMA in comparison to gzip.
30d65dbf 182
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183config KERNEL_XZ
184 bool "XZ"
185 depends on HAVE_KERNEL_XZ
186 help
187 XZ uses the LZMA2 algorithm and instruction set specific
188 BCJ filters which can improve compression ratio of executable
189 code. The size of the kernel is about 30% smaller with XZ in
190 comparison to gzip. On architectures for which there is a BCJ
191 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
192 will create a few percent smaller kernel than plain LZMA.
193
194 The speed is about the same as with LZMA: The decompression
195 speed of XZ is better than that of bzip2 but worse than gzip
196 and LZO. Compression is slow.
197
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198config KERNEL_LZO
199 bool "LZO"
200 depends on HAVE_KERNEL_LZO
201 help
0a4dd35c 202 Its compression ratio is the poorest among the choices. The kernel
681b3049 203 size is about 10% bigger than gzip; however its speed
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204 (both compression and decompression) is the fastest.
205
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206endchoice
207
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208config DEFAULT_HOSTNAME
209 string "Default hostname"
210 default "(none)"
211 help
212 This option determines the default system hostname before userspace
213 calls sethostname(2). The kernel traditionally uses "(none)" here,
214 but you may wish to use a different default here to make a minimal
215 system more usable with less configuration.
216
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217config SWAP
218 bool "Support for paging of anonymous memory (swap)"
9361401e 219 depends on MMU && BLOCK
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220 default y
221 help
222 This option allows you to choose whether you want to have support
92c3504e 223 for so called swap devices or swap files in your kernel that are
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224 used to provide more virtual memory than the actual RAM present
225 in your computer. If unsure say Y.
226
227config SYSVIPC
228 bool "System V IPC"
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229 ---help---
230 Inter Process Communication is a suite of library functions and
231 system calls which let processes (running programs) synchronize and
232 exchange information. It is generally considered to be a good thing,
233 and some programs won't run unless you say Y here. In particular, if
234 you want to run the DOS emulator dosemu under Linux (read the
235 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
236 you'll need to say Y here.
237
238 You can find documentation about IPC with "info ipc" and also in
239 section 6.4 of the Linux Programmer's Guide, available from
240 <http://www.tldp.org/guides.html>.
241
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242config SYSVIPC_SYSCTL
243 bool
244 depends on SYSVIPC
245 depends on SYSCTL
246 default y
247
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248config POSIX_MQUEUE
249 bool "POSIX Message Queues"
250 depends on NET && EXPERIMENTAL
251 ---help---
252 POSIX variant of message queues is a part of IPC. In POSIX message
253 queues every message has a priority which decides about succession
254 of receiving it by a process. If you want to compile and run
255 programs written e.g. for Solaris with use of its POSIX message
b0e37650 256 queues (functions mq_*) say Y here.
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257
258 POSIX message queues are visible as a filesystem called 'mqueue'
259 and can be mounted somewhere if you want to do filesystem
260 operations on message queues.
261
262 If unsure, say Y.
263
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264config POSIX_MQUEUE_SYSCTL
265 bool
266 depends on POSIX_MQUEUE
267 depends on SYSCTL
268 default y
269
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270config BSD_PROCESS_ACCT
271 bool "BSD Process Accounting"
272 help
273 If you say Y here, a user level program will be able to instruct the
274 kernel (via a special system call) to write process accounting
275 information to a file: whenever a process exits, information about
276 that process will be appended to the file by the kernel. The
277 information includes things such as creation time, owning user,
278 command name, memory usage, controlling terminal etc. (the complete
279 list is in the struct acct in <file:include/linux/acct.h>). It is
280 up to the user level program to do useful things with this
281 information. This is generally a good idea, so say Y.
282
283config BSD_PROCESS_ACCT_V3
284 bool "BSD Process Accounting version 3 file format"
285 depends on BSD_PROCESS_ACCT
286 default n
287 help
288 If you say Y here, the process accounting information is written
289 in a new file format that also logs the process IDs of each
290 process and it's parent. Note that this file format is incompatible
291 with previous v0/v1/v2 file formats, so you will need updated tools
292 for processing it. A preliminary version of these tools is available
37a4c940 293 at <http://www.gnu.org/software/acct/>.
1da177e4 294
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295config FHANDLE
296 bool "open by fhandle syscalls"
297 select EXPORTFS
298 help
299 If you say Y here, a user level program will be able to map
300 file names to handle and then later use the handle for
301 different file system operations. This is useful in implementing
302 userspace file servers, which now track files using handles instead
303 of names. The handle would remain the same even if file names
304 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
305 syscalls.
306
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307config TASKSTATS
308 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
309 depends on NET
310 default n
311 help
312 Export selected statistics for tasks/processes through the
313 generic netlink interface. Unlike BSD process accounting, the
314 statistics are available during the lifetime of tasks/processes as
315 responses to commands. Like BSD accounting, they are sent to user
316 space on task exit.
317
318 Say N if unsure.
319
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320config TASK_DELAY_ACCT
321 bool "Enable per-task delay accounting (EXPERIMENTAL)"
6f44993f 322 depends on TASKSTATS
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323 help
324 Collect information on time spent by a task waiting for system
325 resources like cpu, synchronous block I/O completion and swapping
326 in pages. Such statistics can help in setting a task's priorities
327 relative to other tasks for cpu, io, rss limits etc.
328
329 Say N if unsure.
330
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331config TASK_XACCT
332 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
333 depends on TASKSTATS
334 help
335 Collect extended task accounting data and send the data
336 to userland for processing over the taskstats interface.
337
338 Say N if unsure.
339
340config TASK_IO_ACCOUNTING
341 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
342 depends on TASK_XACCT
343 help
344 Collect information on the number of bytes of storage I/O which this
345 task has caused.
346
347 Say N if unsure.
348
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349config AUDIT
350 bool "Auditing support"
804a6a49 351 depends on NET
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352 help
353 Enable auditing infrastructure that can be used with another
354 kernel subsystem, such as SELinux (which requires this for
355 logging of avc messages output). Does not do system-call
356 auditing without CONFIG_AUDITSYSCALL.
357
358config AUDITSYSCALL
359 bool "Enable system-call auditing support"
29ef73b7 360 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || ARM)
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361 default y if SECURITY_SELINUX
362 help
363 Enable low-overhead system-call auditing infrastructure that
364 can be used independently or with another kernel subsystem,
67640b60 365 such as SELinux.
1da177e4 366
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367config AUDIT_WATCH
368 def_bool y
369 depends on AUDITSYSCALL
370 select FSNOTIFY
1da177e4 371
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372config AUDIT_TREE
373 def_bool y
63c882a0 374 depends on AUDITSYSCALL
28a3a7eb 375 select FSNOTIFY
74c3cbe3 376
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377config AUDIT_LOGINUID_IMMUTABLE
378 bool "Make audit loginuid immutable"
379 depends on AUDIT
380 help
f429ee3b 381 The config option toggles if a task setting its loginuid requires
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382 CAP_SYS_AUDITCONTROL or if that task should require no special permissions
383 but should instead only allow setting its loginuid if it was never
384 previously set. On systems which use systemd or a similar central
385 process to restart login services this should be set to true. On older
386 systems in which an admin would typically have to directly stop and
387 start processes this should be set to false. Setting this to true allows
388 one to drop potentially dangerous capabilites from the login tasks,
389 but may not be backwards compatible with older init systems.
390
d9817ebe 391source "kernel/irq/Kconfig"
764e0da1 392source "kernel/time/Kconfig"
d9817ebe 393
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394menu "RCU Subsystem"
395
396choice
397 prompt "RCU Implementation"
31c9a24e 398 default TREE_RCU
c903ff83 399
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400config TREE_RCU
401 bool "Tree-based hierarchical RCU"
687d7a96 402 depends on !PREEMPT && SMP
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403 help
404 This option selects the RCU implementation that is
405 designed for very large SMP system with hundreds or
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406 thousands of CPUs. It also scales down nicely to
407 smaller systems.
c903ff83 408
f41d911f 409config TREE_PREEMPT_RCU
a57eb940 410 bool "Preemptible tree-based hierarchical RCU"
8008e129 411 depends on PREEMPT && SMP
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412 help
413 This option selects the RCU implementation that is
414 designed for very large SMP systems with hundreds or
415 thousands of CPUs, but for which real-time response
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416 is also required. It also scales down nicely to
417 smaller systems.
f41d911f 418
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419config TINY_RCU
420 bool "UP-only small-memory-footprint RCU"
8008e129 421 depends on !PREEMPT && !SMP
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422 help
423 This option selects the RCU implementation that is
424 designed for UP systems from which real-time response
425 is not required. This option greatly reduces the
426 memory footprint of RCU.
427
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428config TINY_PREEMPT_RCU
429 bool "Preemptible UP-only small-memory-footprint RCU"
8008e129 430 depends on PREEMPT && !SMP
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431 help
432 This option selects the RCU implementation that is designed
433 for real-time UP systems. This option greatly reduces the
434 memory footprint of RCU.
435
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436endchoice
437
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438config PREEMPT_RCU
439 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
440 help
441 This option enables preemptible-RCU code that is common between
442 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
443
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444config RCU_FANOUT
445 int "Tree-based hierarchical RCU fanout value"
446 range 2 64 if 64BIT
447 range 2 32 if !64BIT
f41d911f 448 depends on TREE_RCU || TREE_PREEMPT_RCU
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449 default 64 if 64BIT
450 default 32 if !64BIT
451 help
452 This option controls the fanout of hierarchical implementations
453 of RCU, allowing RCU to work efficiently on machines with
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454 large numbers of CPUs. This value must be at least the fourth
455 root of NR_CPUS, which allows NR_CPUS to be insanely large.
456 The default value of RCU_FANOUT should be used for production
457 systems, but if you are stress-testing the RCU implementation
458 itself, small RCU_FANOUT values allow you to test large-system
459 code paths on small(er) systems.
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460
461 Select a specific number if testing RCU itself.
462 Take the default if unsure.
463
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464config RCU_FANOUT_LEAF
465 int "Tree-based hierarchical RCU leaf-level fanout value"
466 range 2 RCU_FANOUT if 64BIT
467 range 2 RCU_FANOUT if !64BIT
468 depends on TREE_RCU || TREE_PREEMPT_RCU
469 default 16
470 help
471 This option controls the leaf-level fanout of hierarchical
472 implementations of RCU, and allows trading off cache misses
473 against lock contention. Systems that synchronize their
474 scheduling-clock interrupts for energy-efficiency reasons will
475 want the default because the smaller leaf-level fanout keeps
476 lock contention levels acceptably low. Very large systems
477 (hundreds or thousands of CPUs) will instead want to set this
478 value to the maximum value possible in order to reduce the
479 number of cache misses incurred during RCU's grace-period
480 initialization. These systems tend to run CPU-bound, and thus
481 are not helped by synchronized interrupts, and thus tend to
482 skew them, which reduces lock contention enough that large
483 leaf-level fanouts work well.
484
485 Select a specific number if testing RCU itself.
486
487 Select the maximum permissible value for large systems.
488
489 Take the default if unsure.
490
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491config RCU_FANOUT_EXACT
492 bool "Disable tree-based hierarchical RCU auto-balancing"
f41d911f 493 depends on TREE_RCU || TREE_PREEMPT_RCU
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494 default n
495 help
496 This option forces use of the exact RCU_FANOUT value specified,
497 regardless of imbalances in the hierarchy. This is useful for
498 testing RCU itself, and might one day be useful on systems with
499 strong NUMA behavior.
500
501 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
502
503 Say N if unsure.
504
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505config RCU_FAST_NO_HZ
506 bool "Accelerate last non-dyntick-idle CPU's grace periods"
b807fbff 507 depends on NO_HZ && SMP
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508 default n
509 help
510 This option causes RCU to attempt to accelerate grace periods
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511 in order to allow CPUs to enter dynticks-idle state more
512 quickly. On the other hand, this option increases the overhead
513 of the dynticks-idle checking, particularly on systems with
514 large numbers of CPUs.
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515
516 Say Y if energy efficiency is critically important, particularly
517 if you have relatively few CPUs.
518
519 Say N if you are unsure.
520
c903ff83 521config TREE_RCU_TRACE
f41d911f 522 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
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523 select DEBUG_FS
524 help
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525 This option provides tracing for the TREE_RCU and
526 TREE_PREEMPT_RCU implementations, permitting Makefile to
527 trivially select kernel/rcutree_trace.c.
c903ff83 528
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529config RCU_BOOST
530 bool "Enable RCU priority boosting"
27f4d280 531 depends on RT_MUTEXES && PREEMPT_RCU
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532 default n
533 help
534 This option boosts the priority of preempted RCU readers that
535 block the current preemptible RCU grace period for too long.
536 This option also prevents heavy loads from blocking RCU
537 callback invocation for all flavors of RCU.
538
539 Say Y here if you are working with real-time apps or heavy loads
540 Say N here if you are unsure.
541
542config RCU_BOOST_PRIO
543 int "Real-time priority to boost RCU readers to"
544 range 1 99
545 depends on RCU_BOOST
546 default 1
547 help
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548 This option specifies the real-time priority to which long-term
549 preempted RCU readers are to be boosted. If you are working
550 with a real-time application that has one or more CPU-bound
551 threads running at a real-time priority level, you should set
552 RCU_BOOST_PRIO to a priority higher then the highest-priority
553 real-time CPU-bound thread. The default RCU_BOOST_PRIO value
554 of 1 is appropriate in the common case, which is real-time
555 applications that do not have any CPU-bound threads.
556
557 Some real-time applications might not have a single real-time
558 thread that saturates a given CPU, but instead might have
559 multiple real-time threads that, taken together, fully utilize
560 that CPU. In this case, you should set RCU_BOOST_PRIO to
561 a priority higher than the lowest-priority thread that is
562 conspiring to prevent the CPU from running any non-real-time
563 tasks. For example, if one thread at priority 10 and another
564 thread at priority 5 are between themselves fully consuming
565 the CPU time on a given CPU, then RCU_BOOST_PRIO should be
566 set to priority 6 or higher.
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567
568 Specify the real-time priority, or take the default if unsure.
569
570config RCU_BOOST_DELAY
571 int "Milliseconds to delay boosting after RCU grace-period start"
572 range 0 3000
573 depends on RCU_BOOST
574 default 500
575 help
576 This option specifies the time to wait after the beginning of
577 a given grace period before priority-boosting preempted RCU
578 readers blocking that grace period. Note that any RCU reader
579 blocking an expedited RCU grace period is boosted immediately.
580
581 Accept the default if unsure.
582
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583endmenu # "RCU Subsystem"
584
1da177e4 585config IKCONFIG
f2443ab6 586 tristate "Kernel .config support"
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587 ---help---
588 This option enables the complete Linux kernel ".config" file
589 contents to be saved in the kernel. It provides documentation
590 of which kernel options are used in a running kernel or in an
591 on-disk kernel. This information can be extracted from the kernel
592 image file with the script scripts/extract-ikconfig and used as
593 input to rebuild the current kernel or to build another kernel.
594 It can also be extracted from a running kernel by reading
595 /proc/config.gz if enabled (below).
596
597config IKCONFIG_PROC
598 bool "Enable access to .config through /proc/config.gz"
599 depends on IKCONFIG && PROC_FS
600 ---help---
601 This option enables access to the kernel configuration file
602 through /proc/config.gz.
603
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604config LOG_BUF_SHIFT
605 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
606 range 12 21
f17a32e9 607 default 17
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608 help
609 Select kernel log buffer size as a power of 2.
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610 Examples:
611 17 => 128 KB
612 16 => 64 KB
613 15 => 32 KB
614 14 => 16 KB
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615 13 => 8 KB
616 12 => 4 KB
617
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618#
619# Architectures with an unreliable sched_clock() should select this:
620#
621config HAVE_UNSTABLE_SCHED_CLOCK
622 bool
623
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624menuconfig CGROUPS
625 boolean "Control Group support"
0dea1168 626 depends on EVENTFD
5cdc38f9 627 help
23964d2d 628 This option adds support for grouping sets of processes together, for
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629 use with process control subsystems such as Cpusets, CFS, memory
630 controls or device isolation.
631 See
5cdc38f9 632 - Documentation/scheduler/sched-design-CFS.txt (CFS)
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633 - Documentation/cgroups/ (features for grouping, isolation
634 and resource control)
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635
636 Say N if unsure.
637
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638if CGROUPS
639
5cdc38f9
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640config CGROUP_DEBUG
641 bool "Example debug cgroup subsystem"
5cdc38f9
KH
642 default n
643 help
644 This option enables a simple cgroup subsystem that
645 exports useful debugging information about the cgroups
23964d2d 646 framework.
5cdc38f9 647
23964d2d 648 Say N if unsure.
5cdc38f9 649
5cdc38f9 650config CGROUP_FREEZER
23964d2d 651 bool "Freezer cgroup subsystem"
23964d2d
LZ
652 help
653 Provides a way to freeze and unfreeze all tasks in a
5cdc38f9
KH
654 cgroup.
655
656config CGROUP_DEVICE
657 bool "Device controller for cgroups"
5cdc38f9
KH
658 help
659 Provides a cgroup implementing whitelists for devices which
660 a process in the cgroup can mknod or open.
661
662config CPUSETS
663 bool "Cpuset support"
5cdc38f9
KH
664 help
665 This option will let you create and manage CPUSETs which
666 allow dynamically partitioning a system into sets of CPUs and
667 Memory Nodes and assigning tasks to run only within those sets.
668 This is primarily useful on large SMP or NUMA systems.
669
670 Say N if unsure.
671
23964d2d
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672config PROC_PID_CPUSET
673 bool "Include legacy /proc/<pid>/cpuset file"
674 depends on CPUSETS
675 default y
676
d842de87
SV
677config CGROUP_CPUACCT
678 bool "Simple CPU accounting cgroup subsystem"
d842de87
SV
679 help
680 Provides a simple Resource Controller for monitoring the
23964d2d 681 total CPU consumed by the tasks in a cgroup.
d842de87 682
e552b661
PE
683config RESOURCE_COUNTERS
684 bool "Resource counters"
685 help
686 This option enables controller independent resource accounting
23964d2d 687 infrastructure that works with cgroups.
e552b661 688
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BS
689config CGROUP_MEM_RES_CTLR
690 bool "Memory Resource Controller for Control Groups"
79ae9c29 691 depends on RESOURCE_COUNTERS
cf475ad2 692 select MM_OWNER
00f0b825 693 help
84ad6d70 694 Provides a memory resource controller that manages both anonymous
21acb9ca 695 memory and page cache. (See Documentation/cgroups/memory.txt)
00f0b825
BS
696
697 Note that setting this option increases fixed memory overhead
84ad6d70
KH
698 associated with each page of memory in the system. By this,
699 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
700 usage tracking struct at boot. Total amount of this is printed out
701 at boot.
00f0b825
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702
703 Only enable when you're ok with these trade offs and really
84ad6d70
KH
704 sure you need the memory resource controller. Even when you enable
705 this, you can set "cgroup_disable=memory" at your boot option to
706 disable memory resource controller and you can avoid overheads.
c9d5409f 707 (and lose benefits of memory resource controller)
00f0b825 708
cf475ad2
BS
709 This config option also selects MM_OWNER config option, which
710 could in turn add some fork/exit overhead.
711
c077719b 712config CGROUP_MEM_RES_CTLR_SWAP
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KH
713 bool "Memory Resource Controller Swap Extension"
714 depends on CGROUP_MEM_RES_CTLR && SWAP
c077719b
KH
715 help
716 Add swap management feature to memory resource controller. When you
717 enable this, you can limit mem+swap usage per cgroup. In other words,
718 when you disable this, memory resource controller has no cares to
719 usage of swap...a process can exhaust all of the swap. This extension
720 is useful when you want to avoid exhaustion swap but this itself
721 adds more overheads and consumes memory for remembering information.
722 Especially if you use 32bit system or small memory system, please
723 be careful about enabling this. When memory resource controller
724 is disabled by boot option, this will be automatically disabled and
725 there will be no overhead from this. Even when you set this config=y,
00a66d29 726 if boot option "swapaccount=0" is set, swap will not be accounted.
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727 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
728 size is 4096bytes, 512k per 1Gbytes of swap.
a42c390c
MH
729config CGROUP_MEM_RES_CTLR_SWAP_ENABLED
730 bool "Memory Resource Controller Swap Extension enabled by default"
731 depends on CGROUP_MEM_RES_CTLR_SWAP
732 default y
733 help
734 Memory Resource Controller Swap Extension comes with its price in
735 a bigger memory consumption. General purpose distribution kernels
43d547f9 736 which want to enable the feature but keep it disabled by default
a42c390c
MH
737 and let the user enable it by swapaccount boot command line
738 parameter should have this option unselected.
739 For those who want to have the feature enabled by default should
740 select this option (if, for some reason, they need to disable it
00a66d29 741 then swapaccount=0 does the trick).
e5671dfa
GC
742config CGROUP_MEM_RES_CTLR_KMEM
743 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
744 depends on CGROUP_MEM_RES_CTLR && EXPERIMENTAL
745 default n
746 help
747 The Kernel Memory extension for Memory Resource Controller can limit
748 the amount of memory used by kernel objects in the system. Those are
749 fundamentally different from the entities handled by the standard
750 Memory Controller, which are page-based, and can be swapped. Users of
751 the kmem extension can use it to guarantee that no group of processes
752 will ever exhaust kernel resources alone.
c077719b 753
e5d1367f
SE
754config CGROUP_PERF
755 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
756 depends on PERF_EVENTS && CGROUPS
757 help
758 This option extends the per-cpu mode to restrict monitoring to
2d0f2520 759 threads which belong to the cgroup specified and run on the
e5d1367f
SE
760 designated cpu.
761
762 Say N if unsure.
763
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DG
764menuconfig CGROUP_SCHED
765 bool "Group CPU scheduler"
7c941438
DG
766 default n
767 help
768 This feature lets CPU scheduler recognize task groups and control CPU
769 bandwidth allocation to such task groups. It uses cgroups to group
770 tasks.
771
772if CGROUP_SCHED
773config FAIR_GROUP_SCHED
774 bool "Group scheduling for SCHED_OTHER"
775 depends on CGROUP_SCHED
776 default CGROUP_SCHED
777
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PT
778config CFS_BANDWIDTH
779 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
780 depends on EXPERIMENTAL
781 depends on FAIR_GROUP_SCHED
782 default n
783 help
784 This option allows users to define CPU bandwidth rates (limits) for
785 tasks running within the fair group scheduler. Groups with no limit
786 set are considered to be unconstrained and will run with no
787 restriction.
788 See tip/Documentation/scheduler/sched-bwc.txt for more information.
789
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DG
790config RT_GROUP_SCHED
791 bool "Group scheduling for SCHED_RR/FIFO"
792 depends on EXPERIMENTAL
793 depends on CGROUP_SCHED
794 default n
795 help
796 This feature lets you explicitly allocate real CPU bandwidth
32bd7eb5 797 to task groups. If enabled, it will also make it impossible to
7c941438
DG
798 schedule realtime tasks for non-root users until you allocate
799 realtime bandwidth for them.
800 See Documentation/scheduler/sched-rt-group.txt for more information.
801
802endif #CGROUP_SCHED
803
afc24d49 804config BLK_CGROUP
32e380ae 805 bool "Block IO controller"
79ae9c29 806 depends on BLOCK
afc24d49
VG
807 default n
808 ---help---
809 Generic block IO controller cgroup interface. This is the common
810 cgroup interface which should be used by various IO controlling
811 policies.
812
813 Currently, CFQ IO scheduler uses it to recognize task groups and
814 control disk bandwidth allocation (proportional time slice allocation)
e43473b7
VG
815 to such task groups. It is also used by bio throttling logic in
816 block layer to implement upper limit in IO rates on a device.
afc24d49
VG
817
818 This option only enables generic Block IO controller infrastructure.
e43473b7 819 One needs to also enable actual IO controlling logic/policy. For
79e2e759
MW
820 enabling proportional weight division of disk bandwidth in CFQ, set
821 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
c5e0591a 822 CONFIG_BLK_DEV_THROTTLING=y.
afc24d49
VG
823
824 See Documentation/cgroups/blkio-controller.txt for more information.
825
826config DEBUG_BLK_CGROUP
827 bool "Enable Block IO controller debugging"
828 depends on BLK_CGROUP
829 default n
830 ---help---
831 Enable some debugging help. Currently it exports additional stat
832 files in a cgroup which can be useful for debugging.
833
23964d2d 834endif # CGROUPS
c077719b 835
067bce1a
CG
836config CHECKPOINT_RESTORE
837 bool "Checkpoint/restore support" if EXPERT
838 default n
839 help
840 Enables additional kernel features in a sake of checkpoint/restore.
841 In particular it adds auxiliary prctl codes to setup process text,
842 data and heap segment sizes, and a few additional /proc filesystem
843 entries.
844
845 If unsure, say N here.
846
8dd2a82c 847menuconfig NAMESPACES
6a108a14
DR
848 bool "Namespaces support" if EXPERT
849 default !EXPERT
c5289a69
PE
850 help
851 Provides the way to make tasks work with different objects using
852 the same id. For example same IPC id may refer to different objects
853 or same user id or pid may refer to different tasks when used in
854 different namespaces.
855
8dd2a82c
DL
856if NAMESPACES
857
58bfdd6d
PE
858config UTS_NS
859 bool "UTS namespace"
17a6d441 860 default y
58bfdd6d
PE
861 help
862 In this namespace tasks see different info provided with the
863 uname() system call
864
ae5e1b22
PE
865config IPC_NS
866 bool "IPC namespace"
8dd2a82c 867 depends on (SYSVIPC || POSIX_MQUEUE)
17a6d441 868 default y
ae5e1b22
PE
869 help
870 In this namespace tasks work with IPC ids which correspond to
614b84cf 871 different IPC objects in different namespaces.
ae5e1b22 872
aee16ce7
PE
873config USER_NS
874 bool "User namespace (EXPERIMENTAL)"
8dd2a82c 875 depends on EXPERIMENTAL
e1c972b6 876 depends on UIDGID_CONVERTED
5673a94c 877 select UIDGID_STRICT_TYPE_CHECKS
e1c972b6 878
5673a94c 879 default n
aee16ce7
PE
880 help
881 This allows containers, i.e. vservers, to use user namespaces
882 to provide different user info for different servers.
883 If unsure, say N.
884
74bd59bb 885config PID_NS
9bd38c2c 886 bool "PID Namespaces"
17a6d441 887 default y
74bd59bb 888 help
12d2b8f9 889 Support process id namespaces. This allows having multiple
692105b8 890 processes with the same pid as long as they are in different
74bd59bb
PE
891 pid namespaces. This is a building block of containers.
892
d6eb633f
MH
893config NET_NS
894 bool "Network namespace"
8dd2a82c 895 depends on NET
17a6d441 896 default y
d6eb633f
MH
897 help
898 Allow user space to create what appear to be multiple instances
899 of the network stack.
900
8dd2a82c
DL
901endif # NAMESPACES
902
e1c972b6
EB
903config UIDGID_CONVERTED
904 # True if all of the selected software conmponents are known
905 # to have uid_t and gid_t converted to kuid_t and kgid_t
906 # where appropriate and are otherwise safe to use with
907 # the user namespace.
908 bool
909 default y
910
911 # List of kernel pieces that need user namespace work
912 # Features
e1c972b6
EB
913 depends on SYSVIPC = n
914 depends on IMA = n
915 depends on EVM = n
916 depends on KEYS = n
917 depends on AUDIT = n
918 depends on AUDITSYSCALL = n
919 depends on TASKSTATS = n
920 depends on TRACING = n
921 depends on FS_POSIX_ACL = n
922 depends on QUOTA = n
923 depends on QUOTACTL = n
924 depends on DEBUG_CREDENTIALS = n
925 depends on BSD_PROCESS_ACCT = n
926 depends on DRM = n
927 depends on PROC_EVENTS = n
928
929 # Networking
930 depends on NET = n
931 depends on NET_9P = n
932 depends on IPX = n
933 depends on PHONET = n
934 depends on NET_CLS_FLOW = n
935 depends on NETFILTER_XT_MATCH_OWNER = n
936 depends on NETFILTER_XT_MATCH_RECENT = n
937 depends on NETFILTER_XT_TARGET_LOG = n
938 depends on NETFILTER_NETLINK_LOG = n
939 depends on INET = n
940 depends on IPV6 = n
941 depends on IP_SCTP = n
942 depends on AF_RXRPC = n
943 depends on LLC2 = n
944 depends on NET_KEY = n
945 depends on INET_DIAG = n
946 depends on DNS_RESOLVER = n
947 depends on AX25 = n
948 depends on ATALK = n
949
950 # Filesystems
951 depends on USB_DEVICEFS = n
952 depends on USB_GADGETFS = n
953 depends on USB_FUNCTIONFS = n
954 depends on DEVTMPFS = n
955 depends on XENFS = n
956
957 depends on 9P_FS = n
958 depends on ADFS_FS = n
959 depends on AFFS_FS = n
960 depends on AFS_FS = n
961 depends on AUTOFS4_FS = n
962 depends on BEFS_FS = n
963 depends on BFS_FS = n
964 depends on BTRFS_FS = n
965 depends on CEPH_FS = n
966 depends on CIFS = n
967 depends on CODA_FS = n
968 depends on CONFIGFS_FS = n
969 depends on CRAMFS = n
970 depends on DEBUG_FS = n
971 depends on ECRYPT_FS = n
972 depends on EFS_FS = n
973 depends on EXOFS_FS = n
e1c972b6
EB
974 depends on FAT_FS = n
975 depends on FUSE_FS = n
976 depends on GFS2_FS = n
977 depends on HFS_FS = n
978 depends on HFSPLUS_FS = n
979 depends on HPFS_FS = n
980 depends on HUGETLBFS = n
981 depends on ISO9660_FS = n
982 depends on JFFS2_FS = n
983 depends on JFS_FS = n
984 depends on LOGFS = n
985 depends on MINIX_FS = n
986 depends on NCP_FS = n
987 depends on NFSD = n
988 depends on NFS_FS = n
989 depends on NILFS2_FS = n
990 depends on NTFS_FS = n
991 depends on OCFS2_FS = n
992 depends on OMFS_FS = n
e1c972b6
EB
993 depends on QNX4FS_FS = n
994 depends on QNX6FS_FS = n
995 depends on REISERFS_FS = n
996 depends on SQUASHFS = n
e1c972b6 997 depends on SYSV_FS = n
e1c972b6
EB
998 depends on UBIFS_FS = n
999 depends on UDF_FS = n
1000 depends on UFS_FS = n
1001 depends on VXFS_FS = n
1002 depends on XFS_FS = n
1003
1004 depends on !UML || HOSTFS = n
1005
1006 # The rare drivers that won't build
1007 depends on AIRO = n
1008 depends on AIRO_CS = n
1009 depends on TUN = n
1010 depends on INFINIBAND_QIB = n
1011 depends on BLK_DEV_LOOP = n
1012 depends on ANDROID_BINDER_IPC = n
1013
1014 # Security modules
1015 depends on SECURITY_TOMOYO = n
1016 depends on SECURITY_APPARMOR = n
1017
5673a94c
EB
1018config UIDGID_STRICT_TYPE_CHECKS
1019 bool "Require conversions between uid/gids and their internal representation"
e1c972b6 1020 depends on UIDGID_CONVERTED
5673a94c
EB
1021 default n
1022 help
1023 While the nececessary conversions are being added to all subsystems this option allows
1024 the code to continue to build for unconverted subsystems.
1025
1026 Say Y here if you want the strict type checking enabled
1027
5091faa4
MG
1028config SCHED_AUTOGROUP
1029 bool "Automatic process group scheduling"
1030 select EVENTFD
1031 select CGROUPS
1032 select CGROUP_SCHED
1033 select FAIR_GROUP_SCHED
1034 help
1035 This option optimizes the scheduler for common desktop workloads by
1036 automatically creating and populating task groups. This separation
1037 of workloads isolates aggressive CPU burners (like build jobs) from
1038 desktop applications. Task group autogeneration is currently based
1039 upon task session.
1040
7af37bec
DL
1041config MM_OWNER
1042 bool
1043
1044config SYSFS_DEPRECATED
5d6a4ea5 1045 bool "Enable deprecated sysfs features to support old userspace tools"
7af37bec
DL
1046 depends on SYSFS
1047 default n
1048 help
1049 This option adds code that switches the layout of the "block" class
1050 devices, to not show up in /sys/class/block/, but only in
1051 /sys/block/.
1052
1053 This switch is only active when the sysfs.deprecated=1 boot option is
1054 passed or the SYSFS_DEPRECATED_V2 option is set.
1055
1056 This option allows new kernels to run on old distributions and tools,
1057 which might get confused by /sys/class/block/. Since 2007/2008 all
1058 major distributions and tools handle this just fine.
1059
1060 Recent distributions and userspace tools after 2009/2010 depend on
1061 the existence of /sys/class/block/, and will not work with this
1062 option enabled.
1063
1064 Only if you are using a new kernel on an old distribution, you might
1065 need to say Y here.
1066
1067config SYSFS_DEPRECATED_V2
5d6a4ea5 1068 bool "Enable deprecated sysfs features by default"
7af37bec
DL
1069 default n
1070 depends on SYSFS
1071 depends on SYSFS_DEPRECATED
1072 help
1073 Enable deprecated sysfs by default.
1074
1075 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1076 option.
1077
1078 Only if you are using a new kernel on an old distribution, you might
1079 need to say Y here. Even then, odds are you would not need it
1080 enabled, you can always pass the boot option if absolutely necessary.
1081
1082config RELAY
1083 bool "Kernel->user space relay support (formerly relayfs)"
1084 help
1085 This option enables support for relay interface support in
1086 certain file systems (such as debugfs).
1087 It is designed to provide an efficient mechanism for tools and
1088 facilities to relay large amounts of data from kernel space to
1089 user space.
1090
1091 If unsure, say N.
1092
f991633d
DG
1093config BLK_DEV_INITRD
1094 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1095 depends on BROKEN || !FRV
1096 help
1097 The initial RAM filesystem is a ramfs which is loaded by the
1098 boot loader (loadlin or lilo) and that is mounted as root
1099 before the normal boot procedure. It is typically used to
1100 load modules needed to mount the "real" root file system,
1101 etc. See <file:Documentation/initrd.txt> for details.
1102
1103 If RAM disk support (BLK_DEV_RAM) is also included, this
1104 also enables initial RAM disk (initrd) support and adds
1105 15 Kbytes (more on some other architectures) to the kernel size.
1106
1107 If unsure say Y.
1108
c33df4ea
JPS
1109if BLK_DEV_INITRD
1110
dbec4866
SR
1111source "usr/Kconfig"
1112
c33df4ea
JPS
1113endif
1114
c45b4f1f 1115config CC_OPTIMIZE_FOR_SIZE
96fffeb4 1116 bool "Optimize for size"
c45b4f1f
LT
1117 help
1118 Enabling this option will pass "-Os" instead of "-O2" to gcc
1119 resulting in a smaller kernel.
1120
775a7229 1121 If unsure, say Y.
c45b4f1f 1122
0847062a
RD
1123config SYSCTL
1124 bool
1125
b943c460
RD
1126config ANON_INODES
1127 bool
1128
6a108a14
DR
1129menuconfig EXPERT
1130 bool "Configure standard kernel features (expert users)"
f505c553
JT
1131 # Unhide debug options, to make the on-by-default options visible
1132 select DEBUG_KERNEL
1da177e4
LT
1133 help
1134 This option allows certain base kernel options and settings
1135 to be disabled or tweaked. This is for specialized
1136 environments which can tolerate a "non-standard" kernel.
1137 Only use this if you really know what you are doing.
1138
ae81f9e3 1139config UID16
6a108a14 1140 bool "Enable 16-bit UID system calls" if EXPERT
09337f50 1141 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
ae81f9e3
CE
1142 default y
1143 help
1144 This enables the legacy 16-bit UID syscall wrappers.
1145
b89a8171 1146config SYSCTL_SYSCALL
6a108a14 1147 bool "Sysctl syscall support" if EXPERT
26a7034b 1148 depends on PROC_SYSCTL
c736de60 1149 default n
b89a8171 1150 select SYSCTL
ae81f9e3 1151 ---help---
13bb7e37
EB
1152 sys_sysctl uses binary paths that have been found challenging
1153 to properly maintain and use. The interface in /proc/sys
1154 using paths with ascii names is now the primary path to this
1155 information.
b89a8171 1156
13bb7e37
EB
1157 Almost nothing using the binary sysctl interface so if you are
1158 trying to save some space it is probably safe to disable this,
1159 making your kernel marginally smaller.
b89a8171 1160
c736de60 1161 If unsure say N here.
ae81f9e3 1162
1da177e4 1163config KALLSYMS
6a108a14 1164 bool "Load all symbols for debugging/ksymoops" if EXPERT
1da177e4
LT
1165 default y
1166 help
1167 Say Y here to let the kernel print out symbolic crash information and
1168 symbolic stack backtraces. This increases the size of the kernel
1169 somewhat, as all symbols have to be loaded into the kernel image.
1170
1171config KALLSYMS_ALL
1172 bool "Include all symbols in kallsyms"
1173 depends on DEBUG_KERNEL && KALLSYMS
1174 help
71a83ec7
AB
1175 Normally kallsyms only contains the symbols of functions for nicer
1176 OOPS messages and backtraces (i.e., symbols from the text and inittext
1177 sections). This is sufficient for most cases. And only in very rare
1178 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1179 names of variables from the data sections, etc).
1180
1181 This option makes sure that all symbols are loaded into the kernel
1182 image (i.e., symbols from all sections) in cost of increased kernel
1183 size (depending on the kernel configuration, it may be 300KiB or
1184 something like this).
1185
1186 Say N unless you really need all symbols.
d59745ce 1187
712f47ce 1188config HOTPLUG
6a108a14 1189 bool "Support for hot-pluggable devices" if EXPERT
712f47ce
GKH
1190 default y
1191 help
1192 This option is provided for the case where no hotplug or uevent
1193 capabilities is wanted by the kernel. You should only consider
1194 disabling this option for embedded systems that do not use modules, a
1195 dynamic /dev tree, or dynamic device discovery. Just say Y.
1196
d59745ce
MM
1197config PRINTK
1198 default y
6a108a14 1199 bool "Enable support for printk" if EXPERT
d59745ce
MM
1200 help
1201 This option enables normal printk support. Removing it
1202 eliminates most of the message strings from the kernel image
1203 and makes the kernel more or less silent. As this makes it
1204 very difficult to diagnose system problems, saying N here is
1205 strongly discouraged.
1206
c8538a7a 1207config BUG
6a108a14 1208 bool "BUG() support" if EXPERT
c8538a7a
MM
1209 default y
1210 help
1211 Disabling this option eliminates support for BUG and WARN, reducing
1212 the size of your kernel image and potentially quietly ignoring
1213 numerous fatal conditions. You should only consider disabling this
1214 option for embedded systems with no facilities for reporting errors.
1215 Just say Y.
1216
708e9a79
MM
1217config ELF_CORE
1218 default y
6a108a14 1219 bool "Enable ELF core dumps" if EXPERT
708e9a79
MM
1220 help
1221 Enable support for generating core dumps. Disabling saves about 4k.
1222
8761f1ab 1223
e5e1d3cb 1224config PCSPKR_PLATFORM
6a108a14 1225 bool "Enable PC-Speaker support" if EXPERT
8761f1ab 1226 depends on HAVE_PCSPKR_PLATFORM
15f304b6 1227 select I8253_LOCK
e5e1d3cb
SS
1228 default y
1229 help
1230 This option allows to disable the internal PC-Speaker
1231 support, saving some memory.
1232
8761f1ab
RB
1233config HAVE_PCSPKR_PLATFORM
1234 bool
1235
1da177e4
LT
1236config BASE_FULL
1237 default y
6a108a14 1238 bool "Enable full-sized data structures for core" if EXPERT
1da177e4
LT
1239 help
1240 Disabling this option reduces the size of miscellaneous core
1241 kernel data structures. This saves memory on small machines,
1242 but may reduce performance.
1243
1244config FUTEX
6a108a14 1245 bool "Enable futex support" if EXPERT
1da177e4 1246 default y
23f78d4a 1247 select RT_MUTEXES
1da177e4
LT
1248 help
1249 Disabling this option will cause the kernel to be built without
1250 support for "fast userspace mutexes". The resulting kernel may not
1251 run glibc-based applications correctly.
1252
1253config EPOLL
6a108a14 1254 bool "Enable eventpoll support" if EXPERT
1da177e4 1255 default y
448e3cee 1256 select ANON_INODES
1da177e4
LT
1257 help
1258 Disabling this option will cause the kernel to be built without
1259 support for epoll family of system calls.
1260
fba2afaa 1261config SIGNALFD
6a108a14 1262 bool "Enable signalfd() system call" if EXPERT
448e3cee 1263 select ANON_INODES
fba2afaa
DL
1264 default y
1265 help
1266 Enable the signalfd() system call that allows to receive signals
1267 on a file descriptor.
1268
1269 If unsure, say Y.
1270
b215e283 1271config TIMERFD
6a108a14 1272 bool "Enable timerfd() system call" if EXPERT
448e3cee 1273 select ANON_INODES
b215e283
DL
1274 default y
1275 help
1276 Enable the timerfd() system call that allows to receive timer
1277 events on a file descriptor.
1278
1279 If unsure, say Y.
1280
e1ad7468 1281config EVENTFD
6a108a14 1282 bool "Enable eventfd() system call" if EXPERT
448e3cee 1283 select ANON_INODES
e1ad7468
DL
1284 default y
1285 help
1286 Enable the eventfd() system call that allows to receive both
1287 kernel notification (ie. KAIO) or userspace notifications.
1288
1289 If unsure, say Y.
1290
1da177e4 1291config SHMEM
6a108a14 1292 bool "Use full shmem filesystem" if EXPERT
1da177e4
LT
1293 default y
1294 depends on MMU
1295 help
1296 The shmem is an internal filesystem used to manage shared memory.
1297 It is backed by swap and manages resource limits. It is also exported
1298 to userspace as tmpfs if TMPFS is enabled. Disabling this
1299 option replaces shmem and tmpfs with the much simpler ramfs code,
1300 which may be appropriate on small systems without swap.
1301
ebf3f09c 1302config AIO
6a108a14 1303 bool "Enable AIO support" if EXPERT
ebf3f09c
TP
1304 default y
1305 help
1306 This option enables POSIX asynchronous I/O which may by used
1307 by some high performance threaded applications. Disabling
1308 this option saves about 7k.
1309
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RD
1310config EMBEDDED
1311 bool "Embedded system"
1312 select EXPERT
1313 help
1314 This option should be enabled if compiling the kernel for
1315 an embedded system so certain expert options are available
1316 for configuration.
1317
cdd6c482 1318config HAVE_PERF_EVENTS
0793a61d 1319 bool
018df72d
MF
1320 help
1321 See tools/perf/design.txt for details.
0793a61d 1322
906010b2
PZ
1323config PERF_USE_VMALLOC
1324 bool
1325 help
1326 See tools/perf/design.txt for details
1327
57c0c15b 1328menu "Kernel Performance Events And Counters"
0793a61d 1329
cdd6c482 1330config PERF_EVENTS
57c0c15b 1331 bool "Kernel performance events and counters"
392d65a9 1332 default y if PROFILING
cdd6c482 1333 depends on HAVE_PERF_EVENTS
4c59e467 1334 select ANON_INODES
e360adbe 1335 select IRQ_WORK
0793a61d 1336 help
57c0c15b
IM
1337 Enable kernel support for various performance events provided
1338 by software and hardware.
0793a61d 1339
dd77038d 1340 Software events are supported either built-in or via the
57c0c15b 1341 use of generic tracepoints.
0793a61d 1342
57c0c15b
IM
1343 Most modern CPUs support performance events via performance
1344 counter registers. These registers count the number of certain
0793a61d
TG
1345 types of hw events: such as instructions executed, cachemisses
1346 suffered, or branches mis-predicted - without slowing down the
1347 kernel or applications. These registers can also trigger interrupts
1348 when a threshold number of events have passed - and can thus be
1349 used to profile the code that runs on that CPU.
1350
57c0c15b 1351 The Linux Performance Event subsystem provides an abstraction of
dd77038d 1352 these software and hardware event capabilities, available via a
57c0c15b 1353 system call and used by the "perf" utility in tools/perf/. It
0793a61d
TG
1354 provides per task and per CPU counters, and it provides event
1355 capabilities on top of those.
1356
1357 Say Y if unsure.
1358
906010b2
PZ
1359config DEBUG_PERF_USE_VMALLOC
1360 default n
1361 bool "Debug: use vmalloc to back perf mmap() buffers"
1362 depends on PERF_EVENTS && DEBUG_KERNEL
1363 select PERF_USE_VMALLOC
1364 help
1365 Use vmalloc memory to back perf mmap() buffers.
1366
1367 Mostly useful for debugging the vmalloc code on platforms
1368 that don't require it.
1369
1370 Say N if unsure.
1371
0793a61d
TG
1372endmenu
1373
f8891e5e
CL
1374config VM_EVENT_COUNTERS
1375 default y
6a108a14 1376 bool "Enable VM event counters for /proc/vmstat" if EXPERT
f8891e5e 1377 help
2aea4fb6
PJ
1378 VM event counters are needed for event counts to be shown.
1379 This option allows the disabling of the VM event counters
6a108a14 1380 on EXPERT systems. /proc/vmstat will only show page counts
2aea4fb6 1381 if VM event counters are disabled.
f8891e5e 1382
3d137310
TP
1383config PCI_QUIRKS
1384 default y
6a108a14 1385 bool "Enable PCI quirk workarounds" if EXPERT
61cfc7e4 1386 depends on PCI
3d137310
TP
1387 help
1388 This enables workarounds for various PCI chipset
1389 bugs/quirks. Disable this only if your target machine is
1390 unaffected by PCI quirks.
1391
41ecc55b
CL
1392config SLUB_DEBUG
1393 default y
6a108a14 1394 bool "Enable SLUB debugging support" if EXPERT
f6acb635 1395 depends on SLUB && SYSFS
41ecc55b
CL
1396 help
1397 SLUB has extensive debug support features. Disabling these can
1398 result in significant savings in code size. This also disables
1399 SLUB sysfs support. /sys/slab will not exist and there will be
1400 no support for cache validation etc.
1401
b943c460
RD
1402config COMPAT_BRK
1403 bool "Disable heap randomization"
1404 default y
1405 help
1406 Randomizing heap placement makes heap exploits harder, but it
1407 also breaks ancient binaries (including anything libc5 based).
1408 This option changes the bootup default to heap randomization
692105b8 1409 disabled, and can be overridden at runtime by setting
b943c460
RD
1410 /proc/sys/kernel/randomize_va_space to 2.
1411
1412 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1413
81819f0f
CL
1414choice
1415 prompt "Choose SLAB allocator"
a0acd820 1416 default SLUB
81819f0f
CL
1417 help
1418 This option allows to select a slab allocator.
1419
1420config SLAB
1421 bool "SLAB"
1422 help
1423 The regular slab allocator that is established and known to work
34013886 1424 well in all environments. It organizes cache hot objects in
02f56210 1425 per cpu and per node queues.
81819f0f
CL
1426
1427config SLUB
81819f0f
CL
1428 bool "SLUB (Unqueued Allocator)"
1429 help
1430 SLUB is a slab allocator that minimizes cache line usage
1431 instead of managing queues of cached objects (SLAB approach).
1432 Per cpu caching is realized using slabs of objects instead
1433 of queues of objects. SLUB can use memory efficiently
02f56210
SA
1434 and has enhanced diagnostics. SLUB is the default choice for
1435 a slab allocator.
81819f0f
CL
1436
1437config SLOB
6a108a14 1438 depends on EXPERT
81819f0f
CL
1439 bool "SLOB (Simple Allocator)"
1440 help
37291458
MM
1441 SLOB replaces the stock allocator with a drastically simpler
1442 allocator. SLOB is generally more space efficient but
1443 does not perform as well on large systems.
81819f0f
CL
1444
1445endchoice
1446
ea637639
JZ
1447config MMAP_ALLOW_UNINITIALIZED
1448 bool "Allow mmapped anonymous memory to be uninitialized"
6a108a14 1449 depends on EXPERT && !MMU
ea637639
JZ
1450 default n
1451 help
1452 Normally, and according to the Linux spec, anonymous memory obtained
1453 from mmap() has it's contents cleared before it is passed to
1454 userspace. Enabling this config option allows you to request that
1455 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1456 providing a huge performance boost. If this option is not enabled,
1457 then the flag will be ignored.
1458
1459 This is taken advantage of by uClibc's malloc(), and also by
1460 ELF-FDPIC binfmt's brk and stack allocator.
1461
1462 Because of the obvious security issues, this option should only be
1463 enabled on embedded devices where you control what is run in
1464 userspace. Since that isn't generally a problem on no-MMU systems,
1465 it is normally safe to say Y here.
1466
1467 See Documentation/nommu-mmap.txt for more information.
1468
125e5645 1469config PROFILING
b309a294 1470 bool "Profiling support"
125e5645
MD
1471 help
1472 Say Y here to enable the extended profiling support mechanisms used
1473 by profilers such as OProfile.
1474
5f87f112
IM
1475#
1476# Place an empty function call at each tracepoint site. Can be
1477# dynamically changed for a probe function.
1478#
97e1c18e 1479config TRACEPOINTS
5f87f112 1480 bool
97e1c18e 1481
fb32e03f
MD
1482source "arch/Kconfig"
1483
1da177e4
LT
1484endmenu # General setup
1485
ee7e5516
DB
1486config HAVE_GENERIC_DMA_COHERENT
1487 bool
1488 default n
1489
158a9624
LT
1490config SLABINFO
1491 bool
1492 depends on PROC_FS
0f389ec6 1493 depends on SLAB || SLUB_DEBUG
158a9624
LT
1494 default y
1495
ae81f9e3
CE
1496config RT_MUTEXES
1497 boolean
ae81f9e3 1498
1da177e4
LT
1499config BASE_SMALL
1500 int
1501 default 0 if BASE_FULL
1502 default 1 if !BASE_FULL
1503
66da5733 1504menuconfig MODULES
1da177e4
LT
1505 bool "Enable loadable module support"
1506 help
1507 Kernel modules are small pieces of compiled code which can
1508 be inserted in the running kernel, rather than being
1509 permanently built into the kernel. You use the "modprobe"
1510 tool to add (and sometimes remove) them. If you say Y here,
1511 many parts of the kernel can be built as modules (by
1512 answering M instead of Y where indicated): this is most
1513 useful for infrequently used options which are not required
1514 for booting. For more information, see the man pages for
1515 modprobe, lsmod, modinfo, insmod and rmmod.
1516
1517 If you say Y here, you will need to run "make
1518 modules_install" to put the modules under /lib/modules/
1519 where modprobe can find them (you may need to be root to do
1520 this).
1521
1522 If unsure, say Y.
1523
0b0de144
RD
1524if MODULES
1525
826e4506
LT
1526config MODULE_FORCE_LOAD
1527 bool "Forced module loading"
826e4506
LT
1528 default n
1529 help
91e37a79
RR
1530 Allow loading of modules without version information (ie. modprobe
1531 --force). Forced module loading sets the 'F' (forced) taint flag and
1532 is usually a really bad idea.
826e4506 1533
1da177e4
LT
1534config MODULE_UNLOAD
1535 bool "Module unloading"
1da177e4
LT
1536 help
1537 Without this option you will not be able to unload any
1538 modules (note that some modules may not be unloadable
f7f5b675
DV
1539 anyway), which makes your kernel smaller, faster
1540 and simpler. If unsure, say Y.
1da177e4
LT
1541
1542config MODULE_FORCE_UNLOAD
1543 bool "Forced module unloading"
1544 depends on MODULE_UNLOAD && EXPERIMENTAL
1545 help
1546 This option allows you to force a module to unload, even if the
1547 kernel believes it is unsafe: the kernel will remove the module
1548 without waiting for anyone to stop using it (using the -f option to
1549 rmmod). This is mainly for kernel developers and desperate users.
1550 If unsure, say N.
1551
1da177e4 1552config MODVERSIONS
0d541643 1553 bool "Module versioning support"
1da177e4
LT
1554 help
1555 Usually, you have to use modules compiled with your kernel.
1556 Saying Y here makes it sometimes possible to use modules
1557 compiled for different kernels, by adding enough information
1558 to the modules to (hopefully) spot any changes which would
1559 make them incompatible with the kernel you are running. If
1560 unsure, say N.
1561
1562config MODULE_SRCVERSION_ALL
1563 bool "Source checksum for all modules"
1da177e4
LT
1564 help
1565 Modules which contain a MODULE_VERSION get an extra "srcversion"
1566 field inserted into their modinfo section, which contains a
1567 sum of the source files which made it. This helps maintainers
1568 see exactly which source was used to build a module (since
1569 others sometimes change the module source without updating
1570 the version). With this option, such a "srcversion" field
1571 will be created for all modules. If unsure, say N.
1572
0b0de144
RD
1573endif # MODULES
1574
98a79d6a
RR
1575config INIT_ALL_POSSIBLE
1576 bool
1577 help
5f054e31
RR
1578 Back when each arch used to define their own cpu_online_mask and
1579 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
98a79d6a
RR
1580 with all 1s, and others with all 0s. When they were centralised,
1581 it was better to provide this option than to break all the archs
692105b8 1582 and have several arch maintainers pursuing me down dark alleys.
98a79d6a 1583
1da177e4
LT
1584config STOP_MACHINE
1585 bool
1586 default y
1587 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1588 help
1589 Need stop_machine() primitive.
3a65dfe8 1590
3a65dfe8 1591source "block/Kconfig"
e98c3202
AK
1592
1593config PREEMPT_NOTIFIERS
1594 bool
e260be67 1595
16295bec
SK
1596config PADATA
1597 depends on SMP
1598 bool
1599
6beb0009 1600source "kernel/Kconfig.locks"