userns: Convert squashfs to use kuid/kgid where appropriate
[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
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56 drivers that have been replaced by something else, and/or are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"
8f827a14 360 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || (ARM && AEABI && !OABI_COMPAT))
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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
LZ
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
c255a458 689config MEMCG
00f0b825 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
BS
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
c255a458 712config MEMCG_SWAP
65e0e811 713 bool "Memory Resource Controller Swap Extension"
c255a458 714 depends on MEMCG && 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.
c255a458 729config MEMCG_SWAP_ENABLED
a42c390c 730 bool "Memory Resource Controller Swap Extension enabled by default"
c255a458 731 depends on MEMCG_SWAP
a42c390c
MH
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).
c255a458 742config MEMCG_KMEM
e5671dfa 743 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
c255a458 744 depends on MEMCG && EXPERIMENTAL
e5671dfa
GC
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
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AK
754config CGROUP_HUGETLB
755 bool "HugeTLB Resource Controller for Control Groups"
756 depends on RESOURCE_COUNTERS && HUGETLB_PAGE && EXPERIMENTAL
757 default n
758 help
759 Provides a cgroup Resource Controller for HugeTLB pages.
760 When you enable this, you can put a per cgroup limit on HugeTLB usage.
761 The limit is enforced during page fault. Since HugeTLB doesn't
762 support page reclaim, enforcing the limit at page fault time implies
763 that, the application will get SIGBUS signal if it tries to access
764 HugeTLB pages beyond its limit. This requires the application to know
765 beforehand how much HugeTLB pages it would require for its use. The
766 control group is tracked in the third page lru pointer. This means
767 that we cannot use the controller with huge page less than 3 pages.
768
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SE
769config CGROUP_PERF
770 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
771 depends on PERF_EVENTS && CGROUPS
772 help
773 This option extends the per-cpu mode to restrict monitoring to
2d0f2520 774 threads which belong to the cgroup specified and run on the
e5d1367f
SE
775 designated cpu.
776
777 Say N if unsure.
778
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DG
779menuconfig CGROUP_SCHED
780 bool "Group CPU scheduler"
7c941438
DG
781 default n
782 help
783 This feature lets CPU scheduler recognize task groups and control CPU
784 bandwidth allocation to such task groups. It uses cgroups to group
785 tasks.
786
787if CGROUP_SCHED
788config FAIR_GROUP_SCHED
789 bool "Group scheduling for SCHED_OTHER"
790 depends on CGROUP_SCHED
791 default CGROUP_SCHED
792
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PT
793config CFS_BANDWIDTH
794 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
795 depends on EXPERIMENTAL
796 depends on FAIR_GROUP_SCHED
797 default n
798 help
799 This option allows users to define CPU bandwidth rates (limits) for
800 tasks running within the fair group scheduler. Groups with no limit
801 set are considered to be unconstrained and will run with no
802 restriction.
803 See tip/Documentation/scheduler/sched-bwc.txt for more information.
804
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DG
805config RT_GROUP_SCHED
806 bool "Group scheduling for SCHED_RR/FIFO"
807 depends on EXPERIMENTAL
808 depends on CGROUP_SCHED
809 default n
810 help
811 This feature lets you explicitly allocate real CPU bandwidth
32bd7eb5 812 to task groups. If enabled, it will also make it impossible to
7c941438
DG
813 schedule realtime tasks for non-root users until you allocate
814 realtime bandwidth for them.
815 See Documentation/scheduler/sched-rt-group.txt for more information.
816
817endif #CGROUP_SCHED
818
afc24d49 819config BLK_CGROUP
32e380ae 820 bool "Block IO controller"
79ae9c29 821 depends on BLOCK
afc24d49
VG
822 default n
823 ---help---
824 Generic block IO controller cgroup interface. This is the common
825 cgroup interface which should be used by various IO controlling
826 policies.
827
828 Currently, CFQ IO scheduler uses it to recognize task groups and
829 control disk bandwidth allocation (proportional time slice allocation)
e43473b7
VG
830 to such task groups. It is also used by bio throttling logic in
831 block layer to implement upper limit in IO rates on a device.
afc24d49
VG
832
833 This option only enables generic Block IO controller infrastructure.
e43473b7 834 One needs to also enable actual IO controlling logic/policy. For
79e2e759
MW
835 enabling proportional weight division of disk bandwidth in CFQ, set
836 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
c5e0591a 837 CONFIG_BLK_DEV_THROTTLING=y.
afc24d49
VG
838
839 See Documentation/cgroups/blkio-controller.txt for more information.
840
841config DEBUG_BLK_CGROUP
842 bool "Enable Block IO controller debugging"
843 depends on BLK_CGROUP
844 default n
845 ---help---
846 Enable some debugging help. Currently it exports additional stat
847 files in a cgroup which can be useful for debugging.
848
23964d2d 849endif # CGROUPS
c077719b 850
067bce1a
CG
851config CHECKPOINT_RESTORE
852 bool "Checkpoint/restore support" if EXPERT
853 default n
854 help
855 Enables additional kernel features in a sake of checkpoint/restore.
856 In particular it adds auxiliary prctl codes to setup process text,
857 data and heap segment sizes, and a few additional /proc filesystem
858 entries.
859
860 If unsure, say N here.
861
8dd2a82c 862menuconfig NAMESPACES
6a108a14
DR
863 bool "Namespaces support" if EXPERT
864 default !EXPERT
c5289a69
PE
865 help
866 Provides the way to make tasks work with different objects using
867 the same id. For example same IPC id may refer to different objects
868 or same user id or pid may refer to different tasks when used in
869 different namespaces.
870
8dd2a82c
DL
871if NAMESPACES
872
58bfdd6d
PE
873config UTS_NS
874 bool "UTS namespace"
17a6d441 875 default y
58bfdd6d
PE
876 help
877 In this namespace tasks see different info provided with the
878 uname() system call
879
ae5e1b22
PE
880config IPC_NS
881 bool "IPC namespace"
8dd2a82c 882 depends on (SYSVIPC || POSIX_MQUEUE)
17a6d441 883 default y
ae5e1b22
PE
884 help
885 In this namespace tasks work with IPC ids which correspond to
614b84cf 886 different IPC objects in different namespaces.
ae5e1b22 887
aee16ce7
PE
888config USER_NS
889 bool "User namespace (EXPERIMENTAL)"
8dd2a82c 890 depends on EXPERIMENTAL
e1c972b6 891 depends on UIDGID_CONVERTED
5673a94c 892 select UIDGID_STRICT_TYPE_CHECKS
e1c972b6 893
5673a94c 894 default n
aee16ce7
PE
895 help
896 This allows containers, i.e. vservers, to use user namespaces
897 to provide different user info for different servers.
898 If unsure, say N.
899
74bd59bb 900config PID_NS
9bd38c2c 901 bool "PID Namespaces"
17a6d441 902 default y
74bd59bb 903 help
12d2b8f9 904 Support process id namespaces. This allows having multiple
692105b8 905 processes with the same pid as long as they are in different
74bd59bb
PE
906 pid namespaces. This is a building block of containers.
907
d6eb633f
MH
908config NET_NS
909 bool "Network namespace"
8dd2a82c 910 depends on NET
17a6d441 911 default y
d6eb633f
MH
912 help
913 Allow user space to create what appear to be multiple instances
914 of the network stack.
915
8dd2a82c
DL
916endif # NAMESPACES
917
e1c972b6
EB
918config UIDGID_CONVERTED
919 # True if all of the selected software conmponents are known
920 # to have uid_t and gid_t converted to kuid_t and kgid_t
921 # where appropriate and are otherwise safe to use with
922 # the user namespace.
923 bool
924 default y
925
e1c972b6 926 # Networking
e1c972b6 927 depends on NET_9P = n
e1c972b6
EB
928
929 # Filesystems
e1c972b6 930 depends on 9P_FS = n
e1c972b6
EB
931 depends on AFS_FS = n
932 depends on AUTOFS4_FS = n
e1c972b6
EB
933 depends on CEPH_FS = n
934 depends on CIFS = n
935 depends on CODA_FS = n
e1c972b6
EB
936 depends on FUSE_FS = n
937 depends on GFS2_FS = n
e1c972b6
EB
938 depends on NCP_FS = n
939 depends on NFSD = n
940 depends on NFS_FS = n
e1c972b6 941 depends on OCFS2_FS = n
e1c972b6
EB
942 depends on UBIFS_FS = n
943 depends on UDF_FS = n
944 depends on UFS_FS = n
e1c972b6
EB
945 depends on XFS_FS = n
946
5673a94c
EB
947config UIDGID_STRICT_TYPE_CHECKS
948 bool "Require conversions between uid/gids and their internal representation"
e1c972b6 949 depends on UIDGID_CONVERTED
5673a94c
EB
950 default n
951 help
952 While the nececessary conversions are being added to all subsystems this option allows
953 the code to continue to build for unconverted subsystems.
954
955 Say Y here if you want the strict type checking enabled
956
5091faa4
MG
957config SCHED_AUTOGROUP
958 bool "Automatic process group scheduling"
959 select EVENTFD
960 select CGROUPS
961 select CGROUP_SCHED
962 select FAIR_GROUP_SCHED
963 help
964 This option optimizes the scheduler for common desktop workloads by
965 automatically creating and populating task groups. This separation
966 of workloads isolates aggressive CPU burners (like build jobs) from
967 desktop applications. Task group autogeneration is currently based
968 upon task session.
969
7af37bec
DL
970config MM_OWNER
971 bool
972
973config SYSFS_DEPRECATED
5d6a4ea5 974 bool "Enable deprecated sysfs features to support old userspace tools"
7af37bec
DL
975 depends on SYSFS
976 default n
977 help
978 This option adds code that switches the layout of the "block" class
979 devices, to not show up in /sys/class/block/, but only in
980 /sys/block/.
981
982 This switch is only active when the sysfs.deprecated=1 boot option is
983 passed or the SYSFS_DEPRECATED_V2 option is set.
984
985 This option allows new kernels to run on old distributions and tools,
986 which might get confused by /sys/class/block/. Since 2007/2008 all
987 major distributions and tools handle this just fine.
988
989 Recent distributions and userspace tools after 2009/2010 depend on
990 the existence of /sys/class/block/, and will not work with this
991 option enabled.
992
993 Only if you are using a new kernel on an old distribution, you might
994 need to say Y here.
995
996config SYSFS_DEPRECATED_V2
5d6a4ea5 997 bool "Enable deprecated sysfs features by default"
7af37bec
DL
998 default n
999 depends on SYSFS
1000 depends on SYSFS_DEPRECATED
1001 help
1002 Enable deprecated sysfs by default.
1003
1004 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1005 option.
1006
1007 Only if you are using a new kernel on an old distribution, you might
1008 need to say Y here. Even then, odds are you would not need it
1009 enabled, you can always pass the boot option if absolutely necessary.
1010
1011config RELAY
1012 bool "Kernel->user space relay support (formerly relayfs)"
1013 help
1014 This option enables support for relay interface support in
1015 certain file systems (such as debugfs).
1016 It is designed to provide an efficient mechanism for tools and
1017 facilities to relay large amounts of data from kernel space to
1018 user space.
1019
1020 If unsure, say N.
1021
f991633d
DG
1022config BLK_DEV_INITRD
1023 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1024 depends on BROKEN || !FRV
1025 help
1026 The initial RAM filesystem is a ramfs which is loaded by the
1027 boot loader (loadlin or lilo) and that is mounted as root
1028 before the normal boot procedure. It is typically used to
1029 load modules needed to mount the "real" root file system,
1030 etc. See <file:Documentation/initrd.txt> for details.
1031
1032 If RAM disk support (BLK_DEV_RAM) is also included, this
1033 also enables initial RAM disk (initrd) support and adds
1034 15 Kbytes (more on some other architectures) to the kernel size.
1035
1036 If unsure say Y.
1037
c33df4ea
JPS
1038if BLK_DEV_INITRD
1039
dbec4866
SR
1040source "usr/Kconfig"
1041
c33df4ea
JPS
1042endif
1043
c45b4f1f 1044config CC_OPTIMIZE_FOR_SIZE
96fffeb4 1045 bool "Optimize for size"
c45b4f1f
LT
1046 help
1047 Enabling this option will pass "-Os" instead of "-O2" to gcc
1048 resulting in a smaller kernel.
1049
775a7229 1050 If unsure, say Y.
c45b4f1f 1051
0847062a
RD
1052config SYSCTL
1053 bool
1054
b943c460
RD
1055config ANON_INODES
1056 bool
1057
6a108a14
DR
1058menuconfig EXPERT
1059 bool "Configure standard kernel features (expert users)"
f505c553
JT
1060 # Unhide debug options, to make the on-by-default options visible
1061 select DEBUG_KERNEL
1da177e4
LT
1062 help
1063 This option allows certain base kernel options and settings
1064 to be disabled or tweaked. This is for specialized
1065 environments which can tolerate a "non-standard" kernel.
1066 Only use this if you really know what you are doing.
1067
ae81f9e3 1068config UID16
6a108a14 1069 bool "Enable 16-bit UID system calls" if EXPERT
09337f50 1070 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
ae81f9e3
CE
1071 default y
1072 help
1073 This enables the legacy 16-bit UID syscall wrappers.
1074
b89a8171 1075config SYSCTL_SYSCALL
6a108a14 1076 bool "Sysctl syscall support" if EXPERT
26a7034b 1077 depends on PROC_SYSCTL
c736de60 1078 default n
b89a8171 1079 select SYSCTL
ae81f9e3 1080 ---help---
13bb7e37
EB
1081 sys_sysctl uses binary paths that have been found challenging
1082 to properly maintain and use. The interface in /proc/sys
1083 using paths with ascii names is now the primary path to this
1084 information.
b89a8171 1085
13bb7e37
EB
1086 Almost nothing using the binary sysctl interface so if you are
1087 trying to save some space it is probably safe to disable this,
1088 making your kernel marginally smaller.
b89a8171 1089
c736de60 1090 If unsure say N here.
ae81f9e3 1091
1da177e4 1092config KALLSYMS
6a108a14 1093 bool "Load all symbols for debugging/ksymoops" if EXPERT
1da177e4
LT
1094 default y
1095 help
1096 Say Y here to let the kernel print out symbolic crash information and
1097 symbolic stack backtraces. This increases the size of the kernel
1098 somewhat, as all symbols have to be loaded into the kernel image.
1099
1100config KALLSYMS_ALL
1101 bool "Include all symbols in kallsyms"
1102 depends on DEBUG_KERNEL && KALLSYMS
1103 help
71a83ec7
AB
1104 Normally kallsyms only contains the symbols of functions for nicer
1105 OOPS messages and backtraces (i.e., symbols from the text and inittext
1106 sections). This is sufficient for most cases. And only in very rare
1107 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1108 names of variables from the data sections, etc).
1109
1110 This option makes sure that all symbols are loaded into the kernel
1111 image (i.e., symbols from all sections) in cost of increased kernel
1112 size (depending on the kernel configuration, it may be 300KiB or
1113 something like this).
1114
1115 Say N unless you really need all symbols.
d59745ce 1116
712f47ce 1117config HOTPLUG
6a108a14 1118 bool "Support for hot-pluggable devices" if EXPERT
712f47ce
GKH
1119 default y
1120 help
1121 This option is provided for the case where no hotplug or uevent
1122 capabilities is wanted by the kernel. You should only consider
1123 disabling this option for embedded systems that do not use modules, a
1124 dynamic /dev tree, or dynamic device discovery. Just say Y.
1125
d59745ce
MM
1126config PRINTK
1127 default y
6a108a14 1128 bool "Enable support for printk" if EXPERT
d59745ce
MM
1129 help
1130 This option enables normal printk support. Removing it
1131 eliminates most of the message strings from the kernel image
1132 and makes the kernel more or less silent. As this makes it
1133 very difficult to diagnose system problems, saying N here is
1134 strongly discouraged.
1135
c8538a7a 1136config BUG
6a108a14 1137 bool "BUG() support" if EXPERT
c8538a7a
MM
1138 default y
1139 help
1140 Disabling this option eliminates support for BUG and WARN, reducing
1141 the size of your kernel image and potentially quietly ignoring
1142 numerous fatal conditions. You should only consider disabling this
1143 option for embedded systems with no facilities for reporting errors.
1144 Just say Y.
1145
708e9a79
MM
1146config ELF_CORE
1147 default y
6a108a14 1148 bool "Enable ELF core dumps" if EXPERT
708e9a79
MM
1149 help
1150 Enable support for generating core dumps. Disabling saves about 4k.
1151
8761f1ab 1152
e5e1d3cb 1153config PCSPKR_PLATFORM
6a108a14 1154 bool "Enable PC-Speaker support" if EXPERT
8761f1ab 1155 depends on HAVE_PCSPKR_PLATFORM
15f304b6 1156 select I8253_LOCK
e5e1d3cb
SS
1157 default y
1158 help
1159 This option allows to disable the internal PC-Speaker
1160 support, saving some memory.
1161
8761f1ab
RB
1162config HAVE_PCSPKR_PLATFORM
1163 bool
1164
1da177e4
LT
1165config BASE_FULL
1166 default y
6a108a14 1167 bool "Enable full-sized data structures for core" if EXPERT
1da177e4
LT
1168 help
1169 Disabling this option reduces the size of miscellaneous core
1170 kernel data structures. This saves memory on small machines,
1171 but may reduce performance.
1172
1173config FUTEX
6a108a14 1174 bool "Enable futex support" if EXPERT
1da177e4 1175 default y
23f78d4a 1176 select RT_MUTEXES
1da177e4
LT
1177 help
1178 Disabling this option will cause the kernel to be built without
1179 support for "fast userspace mutexes". The resulting kernel may not
1180 run glibc-based applications correctly.
1181
1182config EPOLL
6a108a14 1183 bool "Enable eventpoll support" if EXPERT
1da177e4 1184 default y
448e3cee 1185 select ANON_INODES
1da177e4
LT
1186 help
1187 Disabling this option will cause the kernel to be built without
1188 support for epoll family of system calls.
1189
fba2afaa 1190config SIGNALFD
6a108a14 1191 bool "Enable signalfd() system call" if EXPERT
448e3cee 1192 select ANON_INODES
fba2afaa
DL
1193 default y
1194 help
1195 Enable the signalfd() system call that allows to receive signals
1196 on a file descriptor.
1197
1198 If unsure, say Y.
1199
b215e283 1200config TIMERFD
6a108a14 1201 bool "Enable timerfd() system call" if EXPERT
448e3cee 1202 select ANON_INODES
b215e283
DL
1203 default y
1204 help
1205 Enable the timerfd() system call that allows to receive timer
1206 events on a file descriptor.
1207
1208 If unsure, say Y.
1209
e1ad7468 1210config EVENTFD
6a108a14 1211 bool "Enable eventfd() system call" if EXPERT
448e3cee 1212 select ANON_INODES
e1ad7468
DL
1213 default y
1214 help
1215 Enable the eventfd() system call that allows to receive both
1216 kernel notification (ie. KAIO) or userspace notifications.
1217
1218 If unsure, say Y.
1219
1da177e4 1220config SHMEM
6a108a14 1221 bool "Use full shmem filesystem" if EXPERT
1da177e4
LT
1222 default y
1223 depends on MMU
1224 help
1225 The shmem is an internal filesystem used to manage shared memory.
1226 It is backed by swap and manages resource limits. It is also exported
1227 to userspace as tmpfs if TMPFS is enabled. Disabling this
1228 option replaces shmem and tmpfs with the much simpler ramfs code,
1229 which may be appropriate on small systems without swap.
1230
ebf3f09c 1231config AIO
6a108a14 1232 bool "Enable AIO support" if EXPERT
ebf3f09c
TP
1233 default y
1234 help
1235 This option enables POSIX asynchronous I/O which may by used
1236 by some high performance threaded applications. Disabling
1237 this option saves about 7k.
1238
6befe5f6
RD
1239config EMBEDDED
1240 bool "Embedded system"
1241 select EXPERT
1242 help
1243 This option should be enabled if compiling the kernel for
1244 an embedded system so certain expert options are available
1245 for configuration.
1246
cdd6c482 1247config HAVE_PERF_EVENTS
0793a61d 1248 bool
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MF
1249 help
1250 See tools/perf/design.txt for details.
0793a61d 1251
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PZ
1252config PERF_USE_VMALLOC
1253 bool
1254 help
1255 See tools/perf/design.txt for details
1256
57c0c15b 1257menu "Kernel Performance Events And Counters"
0793a61d 1258
cdd6c482 1259config PERF_EVENTS
57c0c15b 1260 bool "Kernel performance events and counters"
392d65a9 1261 default y if PROFILING
cdd6c482 1262 depends on HAVE_PERF_EVENTS
4c59e467 1263 select ANON_INODES
e360adbe 1264 select IRQ_WORK
0793a61d 1265 help
57c0c15b
IM
1266 Enable kernel support for various performance events provided
1267 by software and hardware.
0793a61d 1268
dd77038d 1269 Software events are supported either built-in or via the
57c0c15b 1270 use of generic tracepoints.
0793a61d 1271
57c0c15b
IM
1272 Most modern CPUs support performance events via performance
1273 counter registers. These registers count the number of certain
0793a61d
TG
1274 types of hw events: such as instructions executed, cachemisses
1275 suffered, or branches mis-predicted - without slowing down the
1276 kernel or applications. These registers can also trigger interrupts
1277 when a threshold number of events have passed - and can thus be
1278 used to profile the code that runs on that CPU.
1279
57c0c15b 1280 The Linux Performance Event subsystem provides an abstraction of
dd77038d 1281 these software and hardware event capabilities, available via a
57c0c15b 1282 system call and used by the "perf" utility in tools/perf/. It
0793a61d
TG
1283 provides per task and per CPU counters, and it provides event
1284 capabilities on top of those.
1285
1286 Say Y if unsure.
1287
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PZ
1288config DEBUG_PERF_USE_VMALLOC
1289 default n
1290 bool "Debug: use vmalloc to back perf mmap() buffers"
1291 depends on PERF_EVENTS && DEBUG_KERNEL
1292 select PERF_USE_VMALLOC
1293 help
1294 Use vmalloc memory to back perf mmap() buffers.
1295
1296 Mostly useful for debugging the vmalloc code on platforms
1297 that don't require it.
1298
1299 Say N if unsure.
1300
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TG
1301endmenu
1302
f8891e5e
CL
1303config VM_EVENT_COUNTERS
1304 default y
6a108a14 1305 bool "Enable VM event counters for /proc/vmstat" if EXPERT
f8891e5e 1306 help
2aea4fb6
PJ
1307 VM event counters are needed for event counts to be shown.
1308 This option allows the disabling of the VM event counters
6a108a14 1309 on EXPERT systems. /proc/vmstat will only show page counts
2aea4fb6 1310 if VM event counters are disabled.
f8891e5e 1311
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TP
1312config PCI_QUIRKS
1313 default y
6a108a14 1314 bool "Enable PCI quirk workarounds" if EXPERT
61cfc7e4 1315 depends on PCI
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TP
1316 help
1317 This enables workarounds for various PCI chipset
1318 bugs/quirks. Disable this only if your target machine is
1319 unaffected by PCI quirks.
1320
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CL
1321config SLUB_DEBUG
1322 default y
6a108a14 1323 bool "Enable SLUB debugging support" if EXPERT
f6acb635 1324 depends on SLUB && SYSFS
41ecc55b
CL
1325 help
1326 SLUB has extensive debug support features. Disabling these can
1327 result in significant savings in code size. This also disables
1328 SLUB sysfs support. /sys/slab will not exist and there will be
1329 no support for cache validation etc.
1330
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RD
1331config COMPAT_BRK
1332 bool "Disable heap randomization"
1333 default y
1334 help
1335 Randomizing heap placement makes heap exploits harder, but it
1336 also breaks ancient binaries (including anything libc5 based).
1337 This option changes the bootup default to heap randomization
692105b8 1338 disabled, and can be overridden at runtime by setting
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RD
1339 /proc/sys/kernel/randomize_va_space to 2.
1340
1341 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1342
81819f0f
CL
1343choice
1344 prompt "Choose SLAB allocator"
a0acd820 1345 default SLUB
81819f0f
CL
1346 help
1347 This option allows to select a slab allocator.
1348
1349config SLAB
1350 bool "SLAB"
1351 help
1352 The regular slab allocator that is established and known to work
34013886 1353 well in all environments. It organizes cache hot objects in
02f56210 1354 per cpu and per node queues.
81819f0f
CL
1355
1356config SLUB
81819f0f
CL
1357 bool "SLUB (Unqueued Allocator)"
1358 help
1359 SLUB is a slab allocator that minimizes cache line usage
1360 instead of managing queues of cached objects (SLAB approach).
1361 Per cpu caching is realized using slabs of objects instead
1362 of queues of objects. SLUB can use memory efficiently
02f56210
SA
1363 and has enhanced diagnostics. SLUB is the default choice for
1364 a slab allocator.
81819f0f
CL
1365
1366config SLOB
6a108a14 1367 depends on EXPERT
81819f0f
CL
1368 bool "SLOB (Simple Allocator)"
1369 help
37291458
MM
1370 SLOB replaces the stock allocator with a drastically simpler
1371 allocator. SLOB is generally more space efficient but
1372 does not perform as well on large systems.
81819f0f
CL
1373
1374endchoice
1375
ea637639
JZ
1376config MMAP_ALLOW_UNINITIALIZED
1377 bool "Allow mmapped anonymous memory to be uninitialized"
6a108a14 1378 depends on EXPERT && !MMU
ea637639
JZ
1379 default n
1380 help
1381 Normally, and according to the Linux spec, anonymous memory obtained
1382 from mmap() has it's contents cleared before it is passed to
1383 userspace. Enabling this config option allows you to request that
1384 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1385 providing a huge performance boost. If this option is not enabled,
1386 then the flag will be ignored.
1387
1388 This is taken advantage of by uClibc's malloc(), and also by
1389 ELF-FDPIC binfmt's brk and stack allocator.
1390
1391 Because of the obvious security issues, this option should only be
1392 enabled on embedded devices where you control what is run in
1393 userspace. Since that isn't generally a problem on no-MMU systems,
1394 it is normally safe to say Y here.
1395
1396 See Documentation/nommu-mmap.txt for more information.
1397
125e5645 1398config PROFILING
b309a294 1399 bool "Profiling support"
125e5645
MD
1400 help
1401 Say Y here to enable the extended profiling support mechanisms used
1402 by profilers such as OProfile.
1403
5f87f112
IM
1404#
1405# Place an empty function call at each tracepoint site. Can be
1406# dynamically changed for a probe function.
1407#
97e1c18e 1408config TRACEPOINTS
5f87f112 1409 bool
97e1c18e 1410
fb32e03f
MD
1411source "arch/Kconfig"
1412
1da177e4
LT
1413endmenu # General setup
1414
ee7e5516
DB
1415config HAVE_GENERIC_DMA_COHERENT
1416 bool
1417 default n
1418
158a9624
LT
1419config SLABINFO
1420 bool
1421 depends on PROC_FS
0f389ec6 1422 depends on SLAB || SLUB_DEBUG
158a9624
LT
1423 default y
1424
ae81f9e3
CE
1425config RT_MUTEXES
1426 boolean
ae81f9e3 1427
1da177e4
LT
1428config BASE_SMALL
1429 int
1430 default 0 if BASE_FULL
1431 default 1 if !BASE_FULL
1432
66da5733 1433menuconfig MODULES
1da177e4
LT
1434 bool "Enable loadable module support"
1435 help
1436 Kernel modules are small pieces of compiled code which can
1437 be inserted in the running kernel, rather than being
1438 permanently built into the kernel. You use the "modprobe"
1439 tool to add (and sometimes remove) them. If you say Y here,
1440 many parts of the kernel can be built as modules (by
1441 answering M instead of Y where indicated): this is most
1442 useful for infrequently used options which are not required
1443 for booting. For more information, see the man pages for
1444 modprobe, lsmod, modinfo, insmod and rmmod.
1445
1446 If you say Y here, you will need to run "make
1447 modules_install" to put the modules under /lib/modules/
1448 where modprobe can find them (you may need to be root to do
1449 this).
1450
1451 If unsure, say Y.
1452
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RD
1453if MODULES
1454
826e4506
LT
1455config MODULE_FORCE_LOAD
1456 bool "Forced module loading"
826e4506
LT
1457 default n
1458 help
91e37a79
RR
1459 Allow loading of modules without version information (ie. modprobe
1460 --force). Forced module loading sets the 'F' (forced) taint flag and
1461 is usually a really bad idea.
826e4506 1462
1da177e4
LT
1463config MODULE_UNLOAD
1464 bool "Module unloading"
1da177e4
LT
1465 help
1466 Without this option you will not be able to unload any
1467 modules (note that some modules may not be unloadable
f7f5b675
DV
1468 anyway), which makes your kernel smaller, faster
1469 and simpler. If unsure, say Y.
1da177e4
LT
1470
1471config MODULE_FORCE_UNLOAD
1472 bool "Forced module unloading"
1473 depends on MODULE_UNLOAD && EXPERIMENTAL
1474 help
1475 This option allows you to force a module to unload, even if the
1476 kernel believes it is unsafe: the kernel will remove the module
1477 without waiting for anyone to stop using it (using the -f option to
1478 rmmod). This is mainly for kernel developers and desperate users.
1479 If unsure, say N.
1480
1da177e4 1481config MODVERSIONS
0d541643 1482 bool "Module versioning support"
1da177e4
LT
1483 help
1484 Usually, you have to use modules compiled with your kernel.
1485 Saying Y here makes it sometimes possible to use modules
1486 compiled for different kernels, by adding enough information
1487 to the modules to (hopefully) spot any changes which would
1488 make them incompatible with the kernel you are running. If
1489 unsure, say N.
1490
1491config MODULE_SRCVERSION_ALL
1492 bool "Source checksum for all modules"
1da177e4
LT
1493 help
1494 Modules which contain a MODULE_VERSION get an extra "srcversion"
1495 field inserted into their modinfo section, which contains a
1496 sum of the source files which made it. This helps maintainers
1497 see exactly which source was used to build a module (since
1498 others sometimes change the module source without updating
1499 the version). With this option, such a "srcversion" field
1500 will be created for all modules. If unsure, say N.
1501
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RD
1502endif # MODULES
1503
98a79d6a
RR
1504config INIT_ALL_POSSIBLE
1505 bool
1506 help
5f054e31
RR
1507 Back when each arch used to define their own cpu_online_mask and
1508 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
98a79d6a
RR
1509 with all 1s, and others with all 0s. When they were centralised,
1510 it was better to provide this option than to break all the archs
692105b8 1511 and have several arch maintainers pursuing me down dark alleys.
98a79d6a 1512
1da177e4
LT
1513config STOP_MACHINE
1514 bool
1515 default y
1516 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1517 help
1518 Need stop_machine() primitive.
3a65dfe8 1519
3a65dfe8 1520source "block/Kconfig"
e98c3202
AK
1521
1522config PREEMPT_NOTIFIERS
1523 bool
e260be67 1524
16295bec
SK
1525config PADATA
1526 depends on SMP
1527 bool
1528
6beb0009 1529source "kernel/Kconfig.locks"
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