userns: Convert cramfs 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56 drivers that have been replaced by something else, and/or are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
926 # List of kernel pieces that need user namespace work
927 # Features
e1c972b6
EB
928 depends on IMA = n
929 depends on EVM = n
e1c972b6
EB
930
931 # Networking
e1c972b6 932 depends on NET_9P = n
e1c972b6
EB
933
934 # Filesystems
e1c972b6 935 depends on 9P_FS = n
e1c972b6
EB
936 depends on AFFS_FS = n
937 depends on AFS_FS = n
938 depends on AUTOFS4_FS = n
e1c972b6
EB
939 depends on BFS_FS = n
940 depends on BTRFS_FS = n
941 depends on CEPH_FS = n
942 depends on CIFS = n
943 depends on CODA_FS = n
e1c972b6
EB
944 depends on ECRYPT_FS = n
945 depends on EFS_FS = n
946 depends on EXOFS_FS = n
e1c972b6
EB
947 depends on FUSE_FS = n
948 depends on GFS2_FS = n
949 depends on HFS_FS = n
950 depends on HFSPLUS_FS = n
951 depends on HPFS_FS = n
e1c972b6
EB
952 depends on ISO9660_FS = n
953 depends on JFFS2_FS = n
954 depends on JFS_FS = n
955 depends on LOGFS = n
956 depends on MINIX_FS = n
957 depends on NCP_FS = n
958 depends on NFSD = n
959 depends on NFS_FS = n
960 depends on NILFS2_FS = n
961 depends on NTFS_FS = n
962 depends on OCFS2_FS = n
963 depends on OMFS_FS = n
e1c972b6
EB
964 depends on QNX4FS_FS = n
965 depends on QNX6FS_FS = n
966 depends on REISERFS_FS = n
967 depends on SQUASHFS = n
e1c972b6 968 depends on SYSV_FS = n
e1c972b6
EB
969 depends on UBIFS_FS = n
970 depends on UDF_FS = n
971 depends on UFS_FS = n
972 depends on VXFS_FS = n
973 depends on XFS_FS = n
974
975 depends on !UML || HOSTFS = n
976
977 # The rare drivers that won't build
e1c972b6
EB
978 depends on INFINIBAND_QIB = n
979 depends on BLK_DEV_LOOP = n
980 depends on ANDROID_BINDER_IPC = n
981
982 # Security modules
983 depends on SECURITY_TOMOYO = n
984 depends on SECURITY_APPARMOR = n
985
5673a94c
EB
986config UIDGID_STRICT_TYPE_CHECKS
987 bool "Require conversions between uid/gids and their internal representation"
e1c972b6 988 depends on UIDGID_CONVERTED
5673a94c
EB
989 default n
990 help
991 While the nececessary conversions are being added to all subsystems this option allows
992 the code to continue to build for unconverted subsystems.
993
994 Say Y here if you want the strict type checking enabled
995
5091faa4
MG
996config SCHED_AUTOGROUP
997 bool "Automatic process group scheduling"
998 select EVENTFD
999 select CGROUPS
1000 select CGROUP_SCHED
1001 select FAIR_GROUP_SCHED
1002 help
1003 This option optimizes the scheduler for common desktop workloads by
1004 automatically creating and populating task groups. This separation
1005 of workloads isolates aggressive CPU burners (like build jobs) from
1006 desktop applications. Task group autogeneration is currently based
1007 upon task session.
1008
7af37bec
DL
1009config MM_OWNER
1010 bool
1011
1012config SYSFS_DEPRECATED
5d6a4ea5 1013 bool "Enable deprecated sysfs features to support old userspace tools"
7af37bec
DL
1014 depends on SYSFS
1015 default n
1016 help
1017 This option adds code that switches the layout of the "block" class
1018 devices, to not show up in /sys/class/block/, but only in
1019 /sys/block/.
1020
1021 This switch is only active when the sysfs.deprecated=1 boot option is
1022 passed or the SYSFS_DEPRECATED_V2 option is set.
1023
1024 This option allows new kernels to run on old distributions and tools,
1025 which might get confused by /sys/class/block/. Since 2007/2008 all
1026 major distributions and tools handle this just fine.
1027
1028 Recent distributions and userspace tools after 2009/2010 depend on
1029 the existence of /sys/class/block/, and will not work with this
1030 option enabled.
1031
1032 Only if you are using a new kernel on an old distribution, you might
1033 need to say Y here.
1034
1035config SYSFS_DEPRECATED_V2
5d6a4ea5 1036 bool "Enable deprecated sysfs features by default"
7af37bec
DL
1037 default n
1038 depends on SYSFS
1039 depends on SYSFS_DEPRECATED
1040 help
1041 Enable deprecated sysfs by default.
1042
1043 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1044 option.
1045
1046 Only if you are using a new kernel on an old distribution, you might
1047 need to say Y here. Even then, odds are you would not need it
1048 enabled, you can always pass the boot option if absolutely necessary.
1049
1050config RELAY
1051 bool "Kernel->user space relay support (formerly relayfs)"
1052 help
1053 This option enables support for relay interface support in
1054 certain file systems (such as debugfs).
1055 It is designed to provide an efficient mechanism for tools and
1056 facilities to relay large amounts of data from kernel space to
1057 user space.
1058
1059 If unsure, say N.
1060
f991633d
DG
1061config BLK_DEV_INITRD
1062 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1063 depends on BROKEN || !FRV
1064 help
1065 The initial RAM filesystem is a ramfs which is loaded by the
1066 boot loader (loadlin or lilo) and that is mounted as root
1067 before the normal boot procedure. It is typically used to
1068 load modules needed to mount the "real" root file system,
1069 etc. See <file:Documentation/initrd.txt> for details.
1070
1071 If RAM disk support (BLK_DEV_RAM) is also included, this
1072 also enables initial RAM disk (initrd) support and adds
1073 15 Kbytes (more on some other architectures) to the kernel size.
1074
1075 If unsure say Y.
1076
c33df4ea
JPS
1077if BLK_DEV_INITRD
1078
dbec4866
SR
1079source "usr/Kconfig"
1080
c33df4ea
JPS
1081endif
1082
c45b4f1f 1083config CC_OPTIMIZE_FOR_SIZE
96fffeb4 1084 bool "Optimize for size"
c45b4f1f
LT
1085 help
1086 Enabling this option will pass "-Os" instead of "-O2" to gcc
1087 resulting in a smaller kernel.
1088
775a7229 1089 If unsure, say Y.
c45b4f1f 1090
0847062a
RD
1091config SYSCTL
1092 bool
1093
b943c460
RD
1094config ANON_INODES
1095 bool
1096
6a108a14
DR
1097menuconfig EXPERT
1098 bool "Configure standard kernel features (expert users)"
f505c553
JT
1099 # Unhide debug options, to make the on-by-default options visible
1100 select DEBUG_KERNEL
1da177e4
LT
1101 help
1102 This option allows certain base kernel options and settings
1103 to be disabled or tweaked. This is for specialized
1104 environments which can tolerate a "non-standard" kernel.
1105 Only use this if you really know what you are doing.
1106
ae81f9e3 1107config UID16
6a108a14 1108 bool "Enable 16-bit UID system calls" if EXPERT
09337f50 1109 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
ae81f9e3
CE
1110 default y
1111 help
1112 This enables the legacy 16-bit UID syscall wrappers.
1113
b89a8171 1114config SYSCTL_SYSCALL
6a108a14 1115 bool "Sysctl syscall support" if EXPERT
26a7034b 1116 depends on PROC_SYSCTL
c736de60 1117 default n
b89a8171 1118 select SYSCTL
ae81f9e3 1119 ---help---
13bb7e37
EB
1120 sys_sysctl uses binary paths that have been found challenging
1121 to properly maintain and use. The interface in /proc/sys
1122 using paths with ascii names is now the primary path to this
1123 information.
b89a8171 1124
13bb7e37
EB
1125 Almost nothing using the binary sysctl interface so if you are
1126 trying to save some space it is probably safe to disable this,
1127 making your kernel marginally smaller.
b89a8171 1128
c736de60 1129 If unsure say N here.
ae81f9e3 1130
1da177e4 1131config KALLSYMS
6a108a14 1132 bool "Load all symbols for debugging/ksymoops" if EXPERT
1da177e4
LT
1133 default y
1134 help
1135 Say Y here to let the kernel print out symbolic crash information and
1136 symbolic stack backtraces. This increases the size of the kernel
1137 somewhat, as all symbols have to be loaded into the kernel image.
1138
1139config KALLSYMS_ALL
1140 bool "Include all symbols in kallsyms"
1141 depends on DEBUG_KERNEL && KALLSYMS
1142 help
71a83ec7
AB
1143 Normally kallsyms only contains the symbols of functions for nicer
1144 OOPS messages and backtraces (i.e., symbols from the text and inittext
1145 sections). This is sufficient for most cases. And only in very rare
1146 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1147 names of variables from the data sections, etc).
1148
1149 This option makes sure that all symbols are loaded into the kernel
1150 image (i.e., symbols from all sections) in cost of increased kernel
1151 size (depending on the kernel configuration, it may be 300KiB or
1152 something like this).
1153
1154 Say N unless you really need all symbols.
d59745ce 1155
712f47ce 1156config HOTPLUG
6a108a14 1157 bool "Support for hot-pluggable devices" if EXPERT
712f47ce
GKH
1158 default y
1159 help
1160 This option is provided for the case where no hotplug or uevent
1161 capabilities is wanted by the kernel. You should only consider
1162 disabling this option for embedded systems that do not use modules, a
1163 dynamic /dev tree, or dynamic device discovery. Just say Y.
1164
d59745ce
MM
1165config PRINTK
1166 default y
6a108a14 1167 bool "Enable support for printk" if EXPERT
d59745ce
MM
1168 help
1169 This option enables normal printk support. Removing it
1170 eliminates most of the message strings from the kernel image
1171 and makes the kernel more or less silent. As this makes it
1172 very difficult to diagnose system problems, saying N here is
1173 strongly discouraged.
1174
c8538a7a 1175config BUG
6a108a14 1176 bool "BUG() support" if EXPERT
c8538a7a
MM
1177 default y
1178 help
1179 Disabling this option eliminates support for BUG and WARN, reducing
1180 the size of your kernel image and potentially quietly ignoring
1181 numerous fatal conditions. You should only consider disabling this
1182 option for embedded systems with no facilities for reporting errors.
1183 Just say Y.
1184
708e9a79
MM
1185config ELF_CORE
1186 default y
6a108a14 1187 bool "Enable ELF core dumps" if EXPERT
708e9a79
MM
1188 help
1189 Enable support for generating core dumps. Disabling saves about 4k.
1190
8761f1ab 1191
e5e1d3cb 1192config PCSPKR_PLATFORM
6a108a14 1193 bool "Enable PC-Speaker support" if EXPERT
8761f1ab 1194 depends on HAVE_PCSPKR_PLATFORM
15f304b6 1195 select I8253_LOCK
e5e1d3cb
SS
1196 default y
1197 help
1198 This option allows to disable the internal PC-Speaker
1199 support, saving some memory.
1200
8761f1ab
RB
1201config HAVE_PCSPKR_PLATFORM
1202 bool
1203
1da177e4
LT
1204config BASE_FULL
1205 default y
6a108a14 1206 bool "Enable full-sized data structures for core" if EXPERT
1da177e4
LT
1207 help
1208 Disabling this option reduces the size of miscellaneous core
1209 kernel data structures. This saves memory on small machines,
1210 but may reduce performance.
1211
1212config FUTEX
6a108a14 1213 bool "Enable futex support" if EXPERT
1da177e4 1214 default y
23f78d4a 1215 select RT_MUTEXES
1da177e4
LT
1216 help
1217 Disabling this option will cause the kernel to be built without
1218 support for "fast userspace mutexes". The resulting kernel may not
1219 run glibc-based applications correctly.
1220
1221config EPOLL
6a108a14 1222 bool "Enable eventpoll support" if EXPERT
1da177e4 1223 default y
448e3cee 1224 select ANON_INODES
1da177e4
LT
1225 help
1226 Disabling this option will cause the kernel to be built without
1227 support for epoll family of system calls.
1228
fba2afaa 1229config SIGNALFD
6a108a14 1230 bool "Enable signalfd() system call" if EXPERT
448e3cee 1231 select ANON_INODES
fba2afaa
DL
1232 default y
1233 help
1234 Enable the signalfd() system call that allows to receive signals
1235 on a file descriptor.
1236
1237 If unsure, say Y.
1238
b215e283 1239config TIMERFD
6a108a14 1240 bool "Enable timerfd() system call" if EXPERT
448e3cee 1241 select ANON_INODES
b215e283
DL
1242 default y
1243 help
1244 Enable the timerfd() system call that allows to receive timer
1245 events on a file descriptor.
1246
1247 If unsure, say Y.
1248
e1ad7468 1249config EVENTFD
6a108a14 1250 bool "Enable eventfd() system call" if EXPERT
448e3cee 1251 select ANON_INODES
e1ad7468
DL
1252 default y
1253 help
1254 Enable the eventfd() system call that allows to receive both
1255 kernel notification (ie. KAIO) or userspace notifications.
1256
1257 If unsure, say Y.
1258
1da177e4 1259config SHMEM
6a108a14 1260 bool "Use full shmem filesystem" if EXPERT
1da177e4
LT
1261 default y
1262 depends on MMU
1263 help
1264 The shmem is an internal filesystem used to manage shared memory.
1265 It is backed by swap and manages resource limits. It is also exported
1266 to userspace as tmpfs if TMPFS is enabled. Disabling this
1267 option replaces shmem and tmpfs with the much simpler ramfs code,
1268 which may be appropriate on small systems without swap.
1269
ebf3f09c 1270config AIO
6a108a14 1271 bool "Enable AIO support" if EXPERT
ebf3f09c
TP
1272 default y
1273 help
1274 This option enables POSIX asynchronous I/O which may by used
1275 by some high performance threaded applications. Disabling
1276 this option saves about 7k.
1277
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RD
1278config EMBEDDED
1279 bool "Embedded system"
1280 select EXPERT
1281 help
1282 This option should be enabled if compiling the kernel for
1283 an embedded system so certain expert options are available
1284 for configuration.
1285
cdd6c482 1286config HAVE_PERF_EVENTS
0793a61d 1287 bool
018df72d
MF
1288 help
1289 See tools/perf/design.txt for details.
0793a61d 1290
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PZ
1291config PERF_USE_VMALLOC
1292 bool
1293 help
1294 See tools/perf/design.txt for details
1295
57c0c15b 1296menu "Kernel Performance Events And Counters"
0793a61d 1297
cdd6c482 1298config PERF_EVENTS
57c0c15b 1299 bool "Kernel performance events and counters"
392d65a9 1300 default y if PROFILING
cdd6c482 1301 depends on HAVE_PERF_EVENTS
4c59e467 1302 select ANON_INODES
e360adbe 1303 select IRQ_WORK
0793a61d 1304 help
57c0c15b
IM
1305 Enable kernel support for various performance events provided
1306 by software and hardware.
0793a61d 1307
dd77038d 1308 Software events are supported either built-in or via the
57c0c15b 1309 use of generic tracepoints.
0793a61d 1310
57c0c15b
IM
1311 Most modern CPUs support performance events via performance
1312 counter registers. These registers count the number of certain
0793a61d
TG
1313 types of hw events: such as instructions executed, cachemisses
1314 suffered, or branches mis-predicted - without slowing down the
1315 kernel or applications. These registers can also trigger interrupts
1316 when a threshold number of events have passed - and can thus be
1317 used to profile the code that runs on that CPU.
1318
57c0c15b 1319 The Linux Performance Event subsystem provides an abstraction of
dd77038d 1320 these software and hardware event capabilities, available via a
57c0c15b 1321 system call and used by the "perf" utility in tools/perf/. It
0793a61d
TG
1322 provides per task and per CPU counters, and it provides event
1323 capabilities on top of those.
1324
1325 Say Y if unsure.
1326
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PZ
1327config DEBUG_PERF_USE_VMALLOC
1328 default n
1329 bool "Debug: use vmalloc to back perf mmap() buffers"
1330 depends on PERF_EVENTS && DEBUG_KERNEL
1331 select PERF_USE_VMALLOC
1332 help
1333 Use vmalloc memory to back perf mmap() buffers.
1334
1335 Mostly useful for debugging the vmalloc code on platforms
1336 that don't require it.
1337
1338 Say N if unsure.
1339
0793a61d
TG
1340endmenu
1341
f8891e5e
CL
1342config VM_EVENT_COUNTERS
1343 default y
6a108a14 1344 bool "Enable VM event counters for /proc/vmstat" if EXPERT
f8891e5e 1345 help
2aea4fb6
PJ
1346 VM event counters are needed for event counts to be shown.
1347 This option allows the disabling of the VM event counters
6a108a14 1348 on EXPERT systems. /proc/vmstat will only show page counts
2aea4fb6 1349 if VM event counters are disabled.
f8891e5e 1350
3d137310
TP
1351config PCI_QUIRKS
1352 default y
6a108a14 1353 bool "Enable PCI quirk workarounds" if EXPERT
61cfc7e4 1354 depends on PCI
3d137310
TP
1355 help
1356 This enables workarounds for various PCI chipset
1357 bugs/quirks. Disable this only if your target machine is
1358 unaffected by PCI quirks.
1359
41ecc55b
CL
1360config SLUB_DEBUG
1361 default y
6a108a14 1362 bool "Enable SLUB debugging support" if EXPERT
f6acb635 1363 depends on SLUB && SYSFS
41ecc55b
CL
1364 help
1365 SLUB has extensive debug support features. Disabling these can
1366 result in significant savings in code size. This also disables
1367 SLUB sysfs support. /sys/slab will not exist and there will be
1368 no support for cache validation etc.
1369
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RD
1370config COMPAT_BRK
1371 bool "Disable heap randomization"
1372 default y
1373 help
1374 Randomizing heap placement makes heap exploits harder, but it
1375 also breaks ancient binaries (including anything libc5 based).
1376 This option changes the bootup default to heap randomization
692105b8 1377 disabled, and can be overridden at runtime by setting
b943c460
RD
1378 /proc/sys/kernel/randomize_va_space to 2.
1379
1380 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1381
81819f0f
CL
1382choice
1383 prompt "Choose SLAB allocator"
a0acd820 1384 default SLUB
81819f0f
CL
1385 help
1386 This option allows to select a slab allocator.
1387
1388config SLAB
1389 bool "SLAB"
1390 help
1391 The regular slab allocator that is established and known to work
34013886 1392 well in all environments. It organizes cache hot objects in
02f56210 1393 per cpu and per node queues.
81819f0f
CL
1394
1395config SLUB
81819f0f
CL
1396 bool "SLUB (Unqueued Allocator)"
1397 help
1398 SLUB is a slab allocator that minimizes cache line usage
1399 instead of managing queues of cached objects (SLAB approach).
1400 Per cpu caching is realized using slabs of objects instead
1401 of queues of objects. SLUB can use memory efficiently
02f56210
SA
1402 and has enhanced diagnostics. SLUB is the default choice for
1403 a slab allocator.
81819f0f
CL
1404
1405config SLOB
6a108a14 1406 depends on EXPERT
81819f0f
CL
1407 bool "SLOB (Simple Allocator)"
1408 help
37291458
MM
1409 SLOB replaces the stock allocator with a drastically simpler
1410 allocator. SLOB is generally more space efficient but
1411 does not perform as well on large systems.
81819f0f
CL
1412
1413endchoice
1414
ea637639
JZ
1415config MMAP_ALLOW_UNINITIALIZED
1416 bool "Allow mmapped anonymous memory to be uninitialized"
6a108a14 1417 depends on EXPERT && !MMU
ea637639
JZ
1418 default n
1419 help
1420 Normally, and according to the Linux spec, anonymous memory obtained
1421 from mmap() has it's contents cleared before it is passed to
1422 userspace. Enabling this config option allows you to request that
1423 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1424 providing a huge performance boost. If this option is not enabled,
1425 then the flag will be ignored.
1426
1427 This is taken advantage of by uClibc's malloc(), and also by
1428 ELF-FDPIC binfmt's brk and stack allocator.
1429
1430 Because of the obvious security issues, this option should only be
1431 enabled on embedded devices where you control what is run in
1432 userspace. Since that isn't generally a problem on no-MMU systems,
1433 it is normally safe to say Y here.
1434
1435 See Documentation/nommu-mmap.txt for more information.
1436
125e5645 1437config PROFILING
b309a294 1438 bool "Profiling support"
125e5645
MD
1439 help
1440 Say Y here to enable the extended profiling support mechanisms used
1441 by profilers such as OProfile.
1442
5f87f112
IM
1443#
1444# Place an empty function call at each tracepoint site. Can be
1445# dynamically changed for a probe function.
1446#
97e1c18e 1447config TRACEPOINTS
5f87f112 1448 bool
97e1c18e 1449
fb32e03f
MD
1450source "arch/Kconfig"
1451
1da177e4
LT
1452endmenu # General setup
1453
ee7e5516
DB
1454config HAVE_GENERIC_DMA_COHERENT
1455 bool
1456 default n
1457
158a9624
LT
1458config SLABINFO
1459 bool
1460 depends on PROC_FS
0f389ec6 1461 depends on SLAB || SLUB_DEBUG
158a9624
LT
1462 default y
1463
ae81f9e3
CE
1464config RT_MUTEXES
1465 boolean
ae81f9e3 1466
1da177e4
LT
1467config BASE_SMALL
1468 int
1469 default 0 if BASE_FULL
1470 default 1 if !BASE_FULL
1471
66da5733 1472menuconfig MODULES
1da177e4
LT
1473 bool "Enable loadable module support"
1474 help
1475 Kernel modules are small pieces of compiled code which can
1476 be inserted in the running kernel, rather than being
1477 permanently built into the kernel. You use the "modprobe"
1478 tool to add (and sometimes remove) them. If you say Y here,
1479 many parts of the kernel can be built as modules (by
1480 answering M instead of Y where indicated): this is most
1481 useful for infrequently used options which are not required
1482 for booting. For more information, see the man pages for
1483 modprobe, lsmod, modinfo, insmod and rmmod.
1484
1485 If you say Y here, you will need to run "make
1486 modules_install" to put the modules under /lib/modules/
1487 where modprobe can find them (you may need to be root to do
1488 this).
1489
1490 If unsure, say Y.
1491
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RD
1492if MODULES
1493
826e4506
LT
1494config MODULE_FORCE_LOAD
1495 bool "Forced module loading"
826e4506
LT
1496 default n
1497 help
91e37a79
RR
1498 Allow loading of modules without version information (ie. modprobe
1499 --force). Forced module loading sets the 'F' (forced) taint flag and
1500 is usually a really bad idea.
826e4506 1501
1da177e4
LT
1502config MODULE_UNLOAD
1503 bool "Module unloading"
1da177e4
LT
1504 help
1505 Without this option you will not be able to unload any
1506 modules (note that some modules may not be unloadable
f7f5b675
DV
1507 anyway), which makes your kernel smaller, faster
1508 and simpler. If unsure, say Y.
1da177e4
LT
1509
1510config MODULE_FORCE_UNLOAD
1511 bool "Forced module unloading"
1512 depends on MODULE_UNLOAD && EXPERIMENTAL
1513 help
1514 This option allows you to force a module to unload, even if the
1515 kernel believes it is unsafe: the kernel will remove the module
1516 without waiting for anyone to stop using it (using the -f option to
1517 rmmod). This is mainly for kernel developers and desperate users.
1518 If unsure, say N.
1519
1da177e4 1520config MODVERSIONS
0d541643 1521 bool "Module versioning support"
1da177e4
LT
1522 help
1523 Usually, you have to use modules compiled with your kernel.
1524 Saying Y here makes it sometimes possible to use modules
1525 compiled for different kernels, by adding enough information
1526 to the modules to (hopefully) spot any changes which would
1527 make them incompatible with the kernel you are running. If
1528 unsure, say N.
1529
1530config MODULE_SRCVERSION_ALL
1531 bool "Source checksum for all modules"
1da177e4
LT
1532 help
1533 Modules which contain a MODULE_VERSION get an extra "srcversion"
1534 field inserted into their modinfo section, which contains a
1535 sum of the source files which made it. This helps maintainers
1536 see exactly which source was used to build a module (since
1537 others sometimes change the module source without updating
1538 the version). With this option, such a "srcversion" field
1539 will be created for all modules. If unsure, say N.
1540
0b0de144
RD
1541endif # MODULES
1542
98a79d6a
RR
1543config INIT_ALL_POSSIBLE
1544 bool
1545 help
5f054e31
RR
1546 Back when each arch used to define their own cpu_online_mask and
1547 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
98a79d6a
RR
1548 with all 1s, and others with all 0s. When they were centralised,
1549 it was better to provide this option than to break all the archs
692105b8 1550 and have several arch maintainers pursuing me down dark alleys.
98a79d6a 1551
1da177e4
LT
1552config STOP_MACHINE
1553 bool
1554 default y
1555 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1556 help
1557 Need stop_machine() primitive.
3a65dfe8 1558
3a65dfe8 1559source "block/Kconfig"
e98c3202
AK
1560
1561config PREEMPT_NOTIFIERS
1562 bool
e260be67 1563
16295bec
SK
1564config PADATA
1565 depends on SMP
1566 bool
1567
6beb0009 1568source "kernel/Kconfig.locks"
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