device_cgroup: rename whitelist to exception list
[deliverable/linux.git] / init / Kconfig
CommitLineData
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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56 drivers that have been replaced by something else, and/or are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 FHANDLE
271 bool "open by fhandle syscalls"
272 select EXPORTFS
273 help
274 If you say Y here, a user level program will be able to map
275 file names to handle and then later use the handle for
276 different file system operations. This is useful in implementing
277 userspace file servers, which now track files using handles instead
278 of names. The handle would remain the same even if file names
279 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
280 syscalls.
281
282config AUDIT
283 bool "Auditing support"
284 depends on NET
285 help
286 Enable auditing infrastructure that can be used with another
287 kernel subsystem, such as SELinux (which requires this for
288 logging of avc messages output). Does not do system-call
289 auditing without CONFIG_AUDITSYSCALL.
290
291config AUDITSYSCALL
292 bool "Enable system-call auditing support"
293 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || (ARM && AEABI && !OABI_COMPAT))
294 default y if SECURITY_SELINUX
295 help
296 Enable low-overhead system-call auditing infrastructure that
297 can be used independently or with another kernel subsystem,
298 such as SELinux.
299
300config AUDIT_WATCH
301 def_bool y
302 depends on AUDITSYSCALL
303 select FSNOTIFY
304
305config AUDIT_TREE
306 def_bool y
307 depends on AUDITSYSCALL
308 select FSNOTIFY
309
310config AUDIT_LOGINUID_IMMUTABLE
311 bool "Make audit loginuid immutable"
312 depends on AUDIT
313 help
314 The config option toggles if a task setting its loginuid requires
315 CAP_SYS_AUDITCONTROL or if that task should require no special permissions
316 but should instead only allow setting its loginuid if it was never
317 previously set. On systems which use systemd or a similar central
318 process to restart login services this should be set to true. On older
319 systems in which an admin would typically have to directly stop and
320 start processes this should be set to false. Setting this to true allows
321 one to drop potentially dangerous capabilites from the login tasks,
322 but may not be backwards compatible with older init systems.
323
324source "kernel/irq/Kconfig"
325source "kernel/time/Kconfig"
326
327menu "CPU/Task time and stats accounting"
328
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329choice
330 prompt "Cputime accounting"
331 default TICK_CPU_ACCOUNTING if !PPC64
332 default VIRT_CPU_ACCOUNTING if PPC64
333
334# Kind of a stub config for the pure tick based cputime accounting
335config TICK_CPU_ACCOUNTING
336 bool "Simple tick based cputime accounting"
337 depends on !S390
338 help
339 This is the basic tick based cputime accounting that maintains
340 statistics about user, system and idle time spent on per jiffies
341 granularity.
342
343 If unsure, say Y.
344
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345config VIRT_CPU_ACCOUNTING
346 bool "Deterministic task and CPU time accounting"
347 depends on HAVE_VIRT_CPU_ACCOUNTING
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348 help
349 Select this option to enable more accurate task and CPU time
350 accounting. This is done by reading a CPU counter on each
351 kernel entry and exit and on transitions within the kernel
352 between system, softirq and hardirq state, so there is a
353 small performance impact. In the case of s390 or IBM POWER > 5,
354 this also enables accounting of stolen time on logically-partitioned
355 systems.
356
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357config IRQ_TIME_ACCOUNTING
358 bool "Fine granularity task level IRQ time accounting"
359 depends on HAVE_IRQ_TIME_ACCOUNTING
360 help
361 Select this option to enable fine granularity task irq time
362 accounting. This is done by reading a timestamp on each
363 transitions between softirq and hardirq state, so there can be a
364 small performance impact.
365
366 If in doubt, say N here.
367
368endchoice
369
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370config BSD_PROCESS_ACCT
371 bool "BSD Process Accounting"
372 help
373 If you say Y here, a user level program will be able to instruct the
374 kernel (via a special system call) to write process accounting
375 information to a file: whenever a process exits, information about
376 that process will be appended to the file by the kernel. The
377 information includes things such as creation time, owning user,
378 command name, memory usage, controlling terminal etc. (the complete
379 list is in the struct acct in <file:include/linux/acct.h>). It is
380 up to the user level program to do useful things with this
381 information. This is generally a good idea, so say Y.
382
383config BSD_PROCESS_ACCT_V3
384 bool "BSD Process Accounting version 3 file format"
385 depends on BSD_PROCESS_ACCT
386 default n
387 help
388 If you say Y here, the process accounting information is written
389 in a new file format that also logs the process IDs of each
390 process and it's parent. Note that this file format is incompatible
391 with previous v0/v1/v2 file formats, so you will need updated tools
392 for processing it. A preliminary version of these tools is available
37a4c940 393 at <http://www.gnu.org/software/acct/>.
1da177e4 394
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395config TASKSTATS
396 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
397 depends on NET
398 default n
399 help
400 Export selected statistics for tasks/processes through the
401 generic netlink interface. Unlike BSD process accounting, the
402 statistics are available during the lifetime of tasks/processes as
403 responses to commands. Like BSD accounting, they are sent to user
404 space on task exit.
405
406 Say N if unsure.
407
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408config TASK_DELAY_ACCT
409 bool "Enable per-task delay accounting (EXPERIMENTAL)"
6f44993f 410 depends on TASKSTATS
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411 help
412 Collect information on time spent by a task waiting for system
413 resources like cpu, synchronous block I/O completion and swapping
414 in pages. Such statistics can help in setting a task's priorities
415 relative to other tasks for cpu, io, rss limits etc.
416
417 Say N if unsure.
418
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419config TASK_XACCT
420 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
421 depends on TASKSTATS
422 help
423 Collect extended task accounting data and send the data
424 to userland for processing over the taskstats interface.
425
426 Say N if unsure.
427
428config TASK_IO_ACCOUNTING
429 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
430 depends on TASK_XACCT
431 help
432 Collect information on the number of bytes of storage I/O which this
433 task has caused.
434
435 Say N if unsure.
436
391dc69c 437endmenu # "CPU/Task time and stats accounting"
d9817ebe 438
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439menu "RCU Subsystem"
440
441choice
442 prompt "RCU Implementation"
31c9a24e 443 default TREE_RCU
c903ff83 444
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445config TREE_RCU
446 bool "Tree-based hierarchical RCU"
687d7a96 447 depends on !PREEMPT && SMP
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448 help
449 This option selects the RCU implementation that is
450 designed for very large SMP system with hundreds or
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451 thousands of CPUs. It also scales down nicely to
452 smaller systems.
c903ff83 453
f41d911f 454config TREE_PREEMPT_RCU
a57eb940 455 bool "Preemptible tree-based hierarchical RCU"
8008e129 456 depends on PREEMPT && SMP
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457 help
458 This option selects the RCU implementation that is
459 designed for very large SMP systems with hundreds or
460 thousands of CPUs, but for which real-time response
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461 is also required. It also scales down nicely to
462 smaller systems.
f41d911f 463
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464config TINY_RCU
465 bool "UP-only small-memory-footprint RCU"
8008e129 466 depends on !PREEMPT && !SMP
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467 help
468 This option selects the RCU implementation that is
469 designed for UP systems from which real-time response
470 is not required. This option greatly reduces the
471 memory footprint of RCU.
472
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473config TINY_PREEMPT_RCU
474 bool "Preemptible UP-only small-memory-footprint RCU"
8008e129 475 depends on PREEMPT && !SMP
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476 help
477 This option selects the RCU implementation that is designed
478 for real-time UP systems. This option greatly reduces the
479 memory footprint of RCU.
480
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481endchoice
482
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483config PREEMPT_RCU
484 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
485 help
486 This option enables preemptible-RCU code that is common between
487 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
488
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489config RCU_USER_QS
490 bool "Consider userspace as in RCU extended quiescent state"
491 depends on HAVE_RCU_USER_QS && SMP
492 help
493 This option sets hooks on kernel / userspace boundaries and
494 puts RCU in extended quiescent state when the CPU runs in
495 userspace. It means that when a CPU runs in userspace, it is
496 excluded from the global RCU state machine and thus doesn't
497 to keep the timer tick on for RCU.
498
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499config RCU_USER_QS_FORCE
500 bool "Force userspace extended QS by default"
501 depends on RCU_USER_QS
502 help
503 Set the hooks in user/kernel boundaries by default in order to
504 test this feature that treats userspace as an extended quiescent
505 state until we have a real user like a full adaptive nohz option.
506
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507config RCU_FANOUT
508 int "Tree-based hierarchical RCU fanout value"
509 range 2 64 if 64BIT
510 range 2 32 if !64BIT
f41d911f 511 depends on TREE_RCU || TREE_PREEMPT_RCU
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512 default 64 if 64BIT
513 default 32 if !64BIT
514 help
515 This option controls the fanout of hierarchical implementations
516 of RCU, allowing RCU to work efficiently on machines with
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517 large numbers of CPUs. This value must be at least the fourth
518 root of NR_CPUS, which allows NR_CPUS to be insanely large.
519 The default value of RCU_FANOUT should be used for production
520 systems, but if you are stress-testing the RCU implementation
521 itself, small RCU_FANOUT values allow you to test large-system
522 code paths on small(er) systems.
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523
524 Select a specific number if testing RCU itself.
525 Take the default if unsure.
526
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527config RCU_FANOUT_LEAF
528 int "Tree-based hierarchical RCU leaf-level fanout value"
529 range 2 RCU_FANOUT if 64BIT
530 range 2 RCU_FANOUT if !64BIT
531 depends on TREE_RCU || TREE_PREEMPT_RCU
532 default 16
533 help
534 This option controls the leaf-level fanout of hierarchical
535 implementations of RCU, and allows trading off cache misses
536 against lock contention. Systems that synchronize their
537 scheduling-clock interrupts for energy-efficiency reasons will
538 want the default because the smaller leaf-level fanout keeps
539 lock contention levels acceptably low. Very large systems
540 (hundreds or thousands of CPUs) will instead want to set this
541 value to the maximum value possible in order to reduce the
542 number of cache misses incurred during RCU's grace-period
543 initialization. These systems tend to run CPU-bound, and thus
544 are not helped by synchronized interrupts, and thus tend to
545 skew them, which reduces lock contention enough that large
546 leaf-level fanouts work well.
547
548 Select a specific number if testing RCU itself.
549
550 Select the maximum permissible value for large systems.
551
552 Take the default if unsure.
553
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554config RCU_FANOUT_EXACT
555 bool "Disable tree-based hierarchical RCU auto-balancing"
f41d911f 556 depends on TREE_RCU || TREE_PREEMPT_RCU
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557 default n
558 help
559 This option forces use of the exact RCU_FANOUT value specified,
560 regardless of imbalances in the hierarchy. This is useful for
561 testing RCU itself, and might one day be useful on systems with
562 strong NUMA behavior.
563
564 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
565
566 Say N if unsure.
567
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568config RCU_FAST_NO_HZ
569 bool "Accelerate last non-dyntick-idle CPU's grace periods"
b807fbff 570 depends on NO_HZ && SMP
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571 default n
572 help
573 This option causes RCU to attempt to accelerate grace periods
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574 in order to allow CPUs to enter dynticks-idle state more
575 quickly. On the other hand, this option increases the overhead
576 of the dynticks-idle checking, particularly on systems with
577 large numbers of CPUs.
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578
579 Say Y if energy efficiency is critically important, particularly
580 if you have relatively few CPUs.
581
582 Say N if you are unsure.
583
c903ff83 584config TREE_RCU_TRACE
f41d911f 585 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
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586 select DEBUG_FS
587 help
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588 This option provides tracing for the TREE_RCU and
589 TREE_PREEMPT_RCU implementations, permitting Makefile to
590 trivially select kernel/rcutree_trace.c.
c903ff83 591
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592config RCU_BOOST
593 bool "Enable RCU priority boosting"
27f4d280 594 depends on RT_MUTEXES && PREEMPT_RCU
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595 default n
596 help
597 This option boosts the priority of preempted RCU readers that
598 block the current preemptible RCU grace period for too long.
599 This option also prevents heavy loads from blocking RCU
600 callback invocation for all flavors of RCU.
601
602 Say Y here if you are working with real-time apps or heavy loads
603 Say N here if you are unsure.
604
605config RCU_BOOST_PRIO
606 int "Real-time priority to boost RCU readers to"
607 range 1 99
608 depends on RCU_BOOST
609 default 1
610 help
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611 This option specifies the real-time priority to which long-term
612 preempted RCU readers are to be boosted. If you are working
613 with a real-time application that has one or more CPU-bound
614 threads running at a real-time priority level, you should set
615 RCU_BOOST_PRIO to a priority higher then the highest-priority
616 real-time CPU-bound thread. The default RCU_BOOST_PRIO value
617 of 1 is appropriate in the common case, which is real-time
618 applications that do not have any CPU-bound threads.
619
620 Some real-time applications might not have a single real-time
621 thread that saturates a given CPU, but instead might have
622 multiple real-time threads that, taken together, fully utilize
623 that CPU. In this case, you should set RCU_BOOST_PRIO to
624 a priority higher than the lowest-priority thread that is
625 conspiring to prevent the CPU from running any non-real-time
626 tasks. For example, if one thread at priority 10 and another
627 thread at priority 5 are between themselves fully consuming
628 the CPU time on a given CPU, then RCU_BOOST_PRIO should be
629 set to priority 6 or higher.
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630
631 Specify the real-time priority, or take the default if unsure.
632
633config RCU_BOOST_DELAY
634 int "Milliseconds to delay boosting after RCU grace-period start"
635 range 0 3000
636 depends on RCU_BOOST
637 default 500
638 help
639 This option specifies the time to wait after the beginning of
640 a given grace period before priority-boosting preempted RCU
641 readers blocking that grace period. Note that any RCU reader
642 blocking an expedited RCU grace period is boosted immediately.
643
644 Accept the default if unsure.
645
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646endmenu # "RCU Subsystem"
647
1da177e4 648config IKCONFIG
f2443ab6 649 tristate "Kernel .config support"
1da177e4
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650 ---help---
651 This option enables the complete Linux kernel ".config" file
652 contents to be saved in the kernel. It provides documentation
653 of which kernel options are used in a running kernel or in an
654 on-disk kernel. This information can be extracted from the kernel
655 image file with the script scripts/extract-ikconfig and used as
656 input to rebuild the current kernel or to build another kernel.
657 It can also be extracted from a running kernel by reading
658 /proc/config.gz if enabled (below).
659
660config IKCONFIG_PROC
661 bool "Enable access to .config through /proc/config.gz"
662 depends on IKCONFIG && PROC_FS
663 ---help---
664 This option enables access to the kernel configuration file
665 through /proc/config.gz.
666
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667config LOG_BUF_SHIFT
668 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
669 range 12 21
f17a32e9 670 default 17
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671 help
672 Select kernel log buffer size as a power of 2.
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673 Examples:
674 17 => 128 KB
675 16 => 64 KB
676 15 => 32 KB
677 14 => 16 KB
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678 13 => 8 KB
679 12 => 4 KB
680
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681#
682# Architectures with an unreliable sched_clock() should select this:
683#
684config HAVE_UNSTABLE_SCHED_CLOCK
685 bool
686
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687menuconfig CGROUPS
688 boolean "Control Group support"
0dea1168 689 depends on EVENTFD
5cdc38f9 690 help
23964d2d 691 This option adds support for grouping sets of processes together, for
5cdc38f9
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692 use with process control subsystems such as Cpusets, CFS, memory
693 controls or device isolation.
694 See
5cdc38f9 695 - Documentation/scheduler/sched-design-CFS.txt (CFS)
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696 - Documentation/cgroups/ (features for grouping, isolation
697 and resource control)
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698
699 Say N if unsure.
700
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701if CGROUPS
702
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703config CGROUP_DEBUG
704 bool "Example debug cgroup subsystem"
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705 default n
706 help
707 This option enables a simple cgroup subsystem that
708 exports useful debugging information about the cgroups
23964d2d 709 framework.
5cdc38f9 710
23964d2d 711 Say N if unsure.
5cdc38f9 712
5cdc38f9 713config CGROUP_FREEZER
23964d2d 714 bool "Freezer cgroup subsystem"
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715 help
716 Provides a way to freeze and unfreeze all tasks in a
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717 cgroup.
718
719config CGROUP_DEVICE
720 bool "Device controller for cgroups"
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721 help
722 Provides a cgroup implementing whitelists for devices which
723 a process in the cgroup can mknod or open.
724
725config CPUSETS
726 bool "Cpuset support"
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727 help
728 This option will let you create and manage CPUSETs which
729 allow dynamically partitioning a system into sets of CPUs and
730 Memory Nodes and assigning tasks to run only within those sets.
731 This is primarily useful on large SMP or NUMA systems.
732
733 Say N if unsure.
734
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735config PROC_PID_CPUSET
736 bool "Include legacy /proc/<pid>/cpuset file"
737 depends on CPUSETS
738 default y
739
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740config CGROUP_CPUACCT
741 bool "Simple CPU accounting cgroup subsystem"
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SV
742 help
743 Provides a simple Resource Controller for monitoring the
23964d2d 744 total CPU consumed by the tasks in a cgroup.
d842de87 745
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746config RESOURCE_COUNTERS
747 bool "Resource counters"
748 help
749 This option enables controller independent resource accounting
23964d2d 750 infrastructure that works with cgroups.
e552b661 751
c255a458 752config MEMCG
00f0b825 753 bool "Memory Resource Controller for Control Groups"
79ae9c29 754 depends on RESOURCE_COUNTERS
cf475ad2 755 select MM_OWNER
00f0b825 756 help
84ad6d70 757 Provides a memory resource controller that manages both anonymous
21acb9ca 758 memory and page cache. (See Documentation/cgroups/memory.txt)
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759
760 Note that setting this option increases fixed memory overhead
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761 associated with each page of memory in the system. By this,
762 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
763 usage tracking struct at boot. Total amount of this is printed out
764 at boot.
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765
766 Only enable when you're ok with these trade offs and really
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767 sure you need the memory resource controller. Even when you enable
768 this, you can set "cgroup_disable=memory" at your boot option to
769 disable memory resource controller and you can avoid overheads.
c9d5409f 770 (and lose benefits of memory resource controller)
00f0b825 771
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772 This config option also selects MM_OWNER config option, which
773 could in turn add some fork/exit overhead.
774
c255a458 775config MEMCG_SWAP
65e0e811 776 bool "Memory Resource Controller Swap Extension"
c255a458 777 depends on MEMCG && SWAP
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778 help
779 Add swap management feature to memory resource controller. When you
780 enable this, you can limit mem+swap usage per cgroup. In other words,
781 when you disable this, memory resource controller has no cares to
782 usage of swap...a process can exhaust all of the swap. This extension
783 is useful when you want to avoid exhaustion swap but this itself
784 adds more overheads and consumes memory for remembering information.
785 Especially if you use 32bit system or small memory system, please
786 be careful about enabling this. When memory resource controller
787 is disabled by boot option, this will be automatically disabled and
788 there will be no overhead from this. Even when you set this config=y,
00a66d29 789 if boot option "swapaccount=0" is set, swap will not be accounted.
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790 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
791 size is 4096bytes, 512k per 1Gbytes of swap.
c255a458 792config MEMCG_SWAP_ENABLED
a42c390c 793 bool "Memory Resource Controller Swap Extension enabled by default"
c255a458 794 depends on MEMCG_SWAP
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795 default y
796 help
797 Memory Resource Controller Swap Extension comes with its price in
798 a bigger memory consumption. General purpose distribution kernels
43d547f9 799 which want to enable the feature but keep it disabled by default
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800 and let the user enable it by swapaccount boot command line
801 parameter should have this option unselected.
802 For those who want to have the feature enabled by default should
803 select this option (if, for some reason, they need to disable it
00a66d29 804 then swapaccount=0 does the trick).
c255a458 805config MEMCG_KMEM
e5671dfa 806 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
c255a458 807 depends on MEMCG && EXPERIMENTAL
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808 default n
809 help
810 The Kernel Memory extension for Memory Resource Controller can limit
811 the amount of memory used by kernel objects in the system. Those are
812 fundamentally different from the entities handled by the standard
813 Memory Controller, which are page-based, and can be swapped. Users of
814 the kmem extension can use it to guarantee that no group of processes
815 will ever exhaust kernel resources alone.
c077719b 816
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817config CGROUP_HUGETLB
818 bool "HugeTLB Resource Controller for Control Groups"
819 depends on RESOURCE_COUNTERS && HUGETLB_PAGE && EXPERIMENTAL
820 default n
821 help
822 Provides a cgroup Resource Controller for HugeTLB pages.
823 When you enable this, you can put a per cgroup limit on HugeTLB usage.
824 The limit is enforced during page fault. Since HugeTLB doesn't
825 support page reclaim, enforcing the limit at page fault time implies
826 that, the application will get SIGBUS signal if it tries to access
827 HugeTLB pages beyond its limit. This requires the application to know
828 beforehand how much HugeTLB pages it would require for its use. The
829 control group is tracked in the third page lru pointer. This means
830 that we cannot use the controller with huge page less than 3 pages.
831
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832config CGROUP_PERF
833 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
834 depends on PERF_EVENTS && CGROUPS
835 help
836 This option extends the per-cpu mode to restrict monitoring to
2d0f2520 837 threads which belong to the cgroup specified and run on the
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838 designated cpu.
839
840 Say N if unsure.
841
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842menuconfig CGROUP_SCHED
843 bool "Group CPU scheduler"
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844 default n
845 help
846 This feature lets CPU scheduler recognize task groups and control CPU
847 bandwidth allocation to such task groups. It uses cgroups to group
848 tasks.
849
850if CGROUP_SCHED
851config FAIR_GROUP_SCHED
852 bool "Group scheduling for SCHED_OTHER"
853 depends on CGROUP_SCHED
854 default CGROUP_SCHED
855
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856config CFS_BANDWIDTH
857 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
858 depends on EXPERIMENTAL
859 depends on FAIR_GROUP_SCHED
860 default n
861 help
862 This option allows users to define CPU bandwidth rates (limits) for
863 tasks running within the fair group scheduler. Groups with no limit
864 set are considered to be unconstrained and will run with no
865 restriction.
866 See tip/Documentation/scheduler/sched-bwc.txt for more information.
867
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868config RT_GROUP_SCHED
869 bool "Group scheduling for SCHED_RR/FIFO"
870 depends on EXPERIMENTAL
871 depends on CGROUP_SCHED
872 default n
873 help
874 This feature lets you explicitly allocate real CPU bandwidth
32bd7eb5 875 to task groups. If enabled, it will also make it impossible to
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876 schedule realtime tasks for non-root users until you allocate
877 realtime bandwidth for them.
878 See Documentation/scheduler/sched-rt-group.txt for more information.
879
880endif #CGROUP_SCHED
881
afc24d49 882config BLK_CGROUP
32e380ae 883 bool "Block IO controller"
79ae9c29 884 depends on BLOCK
afc24d49
VG
885 default n
886 ---help---
887 Generic block IO controller cgroup interface. This is the common
888 cgroup interface which should be used by various IO controlling
889 policies.
890
891 Currently, CFQ IO scheduler uses it to recognize task groups and
892 control disk bandwidth allocation (proportional time slice allocation)
e43473b7
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893 to such task groups. It is also used by bio throttling logic in
894 block layer to implement upper limit in IO rates on a device.
afc24d49
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895
896 This option only enables generic Block IO controller infrastructure.
e43473b7 897 One needs to also enable actual IO controlling logic/policy. For
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898 enabling proportional weight division of disk bandwidth in CFQ, set
899 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
c5e0591a 900 CONFIG_BLK_DEV_THROTTLING=y.
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VG
901
902 See Documentation/cgroups/blkio-controller.txt for more information.
903
904config DEBUG_BLK_CGROUP
905 bool "Enable Block IO controller debugging"
906 depends on BLK_CGROUP
907 default n
908 ---help---
909 Enable some debugging help. Currently it exports additional stat
910 files in a cgroup which can be useful for debugging.
911
23964d2d 912endif # CGROUPS
c077719b 913
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CG
914config CHECKPOINT_RESTORE
915 bool "Checkpoint/restore support" if EXPERT
916 default n
917 help
918 Enables additional kernel features in a sake of checkpoint/restore.
919 In particular it adds auxiliary prctl codes to setup process text,
920 data and heap segment sizes, and a few additional /proc filesystem
921 entries.
922
923 If unsure, say N here.
924
8dd2a82c 925menuconfig NAMESPACES
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DR
926 bool "Namespaces support" if EXPERT
927 default !EXPERT
c5289a69
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928 help
929 Provides the way to make tasks work with different objects using
930 the same id. For example same IPC id may refer to different objects
931 or same user id or pid may refer to different tasks when used in
932 different namespaces.
933
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DL
934if NAMESPACES
935
58bfdd6d
PE
936config UTS_NS
937 bool "UTS namespace"
17a6d441 938 default y
58bfdd6d
PE
939 help
940 In this namespace tasks see different info provided with the
941 uname() system call
942
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943config IPC_NS
944 bool "IPC namespace"
8dd2a82c 945 depends on (SYSVIPC || POSIX_MQUEUE)
17a6d441 946 default y
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PE
947 help
948 In this namespace tasks work with IPC ids which correspond to
614b84cf 949 different IPC objects in different namespaces.
ae5e1b22 950
aee16ce7
PE
951config USER_NS
952 bool "User namespace (EXPERIMENTAL)"
8dd2a82c 953 depends on EXPERIMENTAL
e1c972b6 954 depends on UIDGID_CONVERTED
5673a94c 955 select UIDGID_STRICT_TYPE_CHECKS
e1c972b6 956
5673a94c 957 default n
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PE
958 help
959 This allows containers, i.e. vservers, to use user namespaces
960 to provide different user info for different servers.
961 If unsure, say N.
962
74bd59bb 963config PID_NS
9bd38c2c 964 bool "PID Namespaces"
17a6d441 965 default y
74bd59bb 966 help
12d2b8f9 967 Support process id namespaces. This allows having multiple
692105b8 968 processes with the same pid as long as they are in different
74bd59bb
PE
969 pid namespaces. This is a building block of containers.
970
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MH
971config NET_NS
972 bool "Network namespace"
8dd2a82c 973 depends on NET
17a6d441 974 default y
d6eb633f
MH
975 help
976 Allow user space to create what appear to be multiple instances
977 of the network stack.
978
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DL
979endif # NAMESPACES
980
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EB
981config UIDGID_CONVERTED
982 # True if all of the selected software conmponents are known
983 # to have uid_t and gid_t converted to kuid_t and kgid_t
984 # where appropriate and are otherwise safe to use with
985 # the user namespace.
986 bool
987 default y
988
e1c972b6 989 # Networking
e1c972b6 990 depends on NET_9P = n
e1c972b6
EB
991
992 # Filesystems
e1c972b6 993 depends on 9P_FS = n
e1c972b6
EB
994 depends on AFS_FS = n
995 depends on AUTOFS4_FS = n
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EB
996 depends on CEPH_FS = n
997 depends on CIFS = n
998 depends on CODA_FS = n
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EB
999 depends on FUSE_FS = n
1000 depends on GFS2_FS = n
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EB
1001 depends on NCP_FS = n
1002 depends on NFSD = n
1003 depends on NFS_FS = n
e1c972b6 1004 depends on OCFS2_FS = n
e1c972b6
EB
1005 depends on XFS_FS = n
1006
5673a94c
EB
1007config UIDGID_STRICT_TYPE_CHECKS
1008 bool "Require conversions between uid/gids and their internal representation"
e1c972b6 1009 depends on UIDGID_CONVERTED
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EB
1010 default n
1011 help
1012 While the nececessary conversions are being added to all subsystems this option allows
1013 the code to continue to build for unconverted subsystems.
1014
1015 Say Y here if you want the strict type checking enabled
1016
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MG
1017config SCHED_AUTOGROUP
1018 bool "Automatic process group scheduling"
1019 select EVENTFD
1020 select CGROUPS
1021 select CGROUP_SCHED
1022 select FAIR_GROUP_SCHED
1023 help
1024 This option optimizes the scheduler for common desktop workloads by
1025 automatically creating and populating task groups. This separation
1026 of workloads isolates aggressive CPU burners (like build jobs) from
1027 desktop applications. Task group autogeneration is currently based
1028 upon task session.
1029
7af37bec
DL
1030config MM_OWNER
1031 bool
1032
1033config SYSFS_DEPRECATED
5d6a4ea5 1034 bool "Enable deprecated sysfs features to support old userspace tools"
7af37bec
DL
1035 depends on SYSFS
1036 default n
1037 help
1038 This option adds code that switches the layout of the "block" class
1039 devices, to not show up in /sys/class/block/, but only in
1040 /sys/block/.
1041
1042 This switch is only active when the sysfs.deprecated=1 boot option is
1043 passed or the SYSFS_DEPRECATED_V2 option is set.
1044
1045 This option allows new kernels to run on old distributions and tools,
1046 which might get confused by /sys/class/block/. Since 2007/2008 all
1047 major distributions and tools handle this just fine.
1048
1049 Recent distributions and userspace tools after 2009/2010 depend on
1050 the existence of /sys/class/block/, and will not work with this
1051 option enabled.
1052
1053 Only if you are using a new kernel on an old distribution, you might
1054 need to say Y here.
1055
1056config SYSFS_DEPRECATED_V2
5d6a4ea5 1057 bool "Enable deprecated sysfs features by default"
7af37bec
DL
1058 default n
1059 depends on SYSFS
1060 depends on SYSFS_DEPRECATED
1061 help
1062 Enable deprecated sysfs by default.
1063
1064 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1065 option.
1066
1067 Only if you are using a new kernel on an old distribution, you might
1068 need to say Y here. Even then, odds are you would not need it
1069 enabled, you can always pass the boot option if absolutely necessary.
1070
1071config RELAY
1072 bool "Kernel->user space relay support (formerly relayfs)"
1073 help
1074 This option enables support for relay interface support in
1075 certain file systems (such as debugfs).
1076 It is designed to provide an efficient mechanism for tools and
1077 facilities to relay large amounts of data from kernel space to
1078 user space.
1079
1080 If unsure, say N.
1081
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DG
1082config BLK_DEV_INITRD
1083 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1084 depends on BROKEN || !FRV
1085 help
1086 The initial RAM filesystem is a ramfs which is loaded by the
1087 boot loader (loadlin or lilo) and that is mounted as root
1088 before the normal boot procedure. It is typically used to
1089 load modules needed to mount the "real" root file system,
1090 etc. See <file:Documentation/initrd.txt> for details.
1091
1092 If RAM disk support (BLK_DEV_RAM) is also included, this
1093 also enables initial RAM disk (initrd) support and adds
1094 15 Kbytes (more on some other architectures) to the kernel size.
1095
1096 If unsure say Y.
1097
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JPS
1098if BLK_DEV_INITRD
1099
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SR
1100source "usr/Kconfig"
1101
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JPS
1102endif
1103
c45b4f1f 1104config CC_OPTIMIZE_FOR_SIZE
96fffeb4 1105 bool "Optimize for size"
c45b4f1f
LT
1106 help
1107 Enabling this option will pass "-Os" instead of "-O2" to gcc
1108 resulting in a smaller kernel.
1109
775a7229 1110 If unsure, say Y.
c45b4f1f 1111
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RD
1112config SYSCTL
1113 bool
1114
b943c460
RD
1115config ANON_INODES
1116 bool
1117
6a108a14
DR
1118menuconfig EXPERT
1119 bool "Configure standard kernel features (expert users)"
f505c553
JT
1120 # Unhide debug options, to make the on-by-default options visible
1121 select DEBUG_KERNEL
1da177e4
LT
1122 help
1123 This option allows certain base kernel options and settings
1124 to be disabled or tweaked. This is for specialized
1125 environments which can tolerate a "non-standard" kernel.
1126 Only use this if you really know what you are doing.
1127
ae81f9e3 1128config UID16
6a108a14 1129 bool "Enable 16-bit UID system calls" if EXPERT
8c2c3df3
CM
1130 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION) \
1131 || AARCH32_EMULATION
ae81f9e3
CE
1132 default y
1133 help
1134 This enables the legacy 16-bit UID syscall wrappers.
1135
b89a8171 1136config SYSCTL_SYSCALL
6a108a14 1137 bool "Sysctl syscall support" if EXPERT
26a7034b 1138 depends on PROC_SYSCTL
c736de60 1139 default n
b89a8171 1140 select SYSCTL
ae81f9e3 1141 ---help---
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EB
1142 sys_sysctl uses binary paths that have been found challenging
1143 to properly maintain and use. The interface in /proc/sys
1144 using paths with ascii names is now the primary path to this
1145 information.
b89a8171 1146
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EB
1147 Almost nothing using the binary sysctl interface so if you are
1148 trying to save some space it is probably safe to disable this,
1149 making your kernel marginally smaller.
b89a8171 1150
c736de60 1151 If unsure say N here.
ae81f9e3 1152
1da177e4 1153config KALLSYMS
6a108a14 1154 bool "Load all symbols for debugging/ksymoops" if EXPERT
1da177e4
LT
1155 default y
1156 help
1157 Say Y here to let the kernel print out symbolic crash information and
1158 symbolic stack backtraces. This increases the size of the kernel
1159 somewhat, as all symbols have to be loaded into the kernel image.
1160
1161config KALLSYMS_ALL
1162 bool "Include all symbols in kallsyms"
1163 depends on DEBUG_KERNEL && KALLSYMS
1164 help
71a83ec7
AB
1165 Normally kallsyms only contains the symbols of functions for nicer
1166 OOPS messages and backtraces (i.e., symbols from the text and inittext
1167 sections). This is sufficient for most cases. And only in very rare
1168 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1169 names of variables from the data sections, etc).
1170
1171 This option makes sure that all symbols are loaded into the kernel
1172 image (i.e., symbols from all sections) in cost of increased kernel
1173 size (depending on the kernel configuration, it may be 300KiB or
1174 something like this).
1175
1176 Say N unless you really need all symbols.
d59745ce 1177
712f47ce 1178config HOTPLUG
45f035ab 1179 def_bool y
712f47ce 1180
d59745ce
MM
1181config PRINTK
1182 default y
6a108a14 1183 bool "Enable support for printk" if EXPERT
d59745ce
MM
1184 help
1185 This option enables normal printk support. Removing it
1186 eliminates most of the message strings from the kernel image
1187 and makes the kernel more or less silent. As this makes it
1188 very difficult to diagnose system problems, saying N here is
1189 strongly discouraged.
1190
c8538a7a 1191config BUG
6a108a14 1192 bool "BUG() support" if EXPERT
c8538a7a
MM
1193 default y
1194 help
1195 Disabling this option eliminates support for BUG and WARN, reducing
1196 the size of your kernel image and potentially quietly ignoring
1197 numerous fatal conditions. You should only consider disabling this
1198 option for embedded systems with no facilities for reporting errors.
1199 Just say Y.
1200
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1201config ELF_CORE
1202 default y
6a108a14 1203 bool "Enable ELF core dumps" if EXPERT
708e9a79
MM
1204 help
1205 Enable support for generating core dumps. Disabling saves about 4k.
1206
8761f1ab 1207
e5e1d3cb 1208config PCSPKR_PLATFORM
6a108a14 1209 bool "Enable PC-Speaker support" if EXPERT
8761f1ab 1210 depends on HAVE_PCSPKR_PLATFORM
15f304b6 1211 select I8253_LOCK
e5e1d3cb
SS
1212 default y
1213 help
1214 This option allows to disable the internal PC-Speaker
1215 support, saving some memory.
1216
8761f1ab
RB
1217config HAVE_PCSPKR_PLATFORM
1218 bool
1219
1da177e4
LT
1220config BASE_FULL
1221 default y
6a108a14 1222 bool "Enable full-sized data structures for core" if EXPERT
1da177e4
LT
1223 help
1224 Disabling this option reduces the size of miscellaneous core
1225 kernel data structures. This saves memory on small machines,
1226 but may reduce performance.
1227
1228config FUTEX
6a108a14 1229 bool "Enable futex support" if EXPERT
1da177e4 1230 default y
23f78d4a 1231 select RT_MUTEXES
1da177e4
LT
1232 help
1233 Disabling this option will cause the kernel to be built without
1234 support for "fast userspace mutexes". The resulting kernel may not
1235 run glibc-based applications correctly.
1236
1237config EPOLL
6a108a14 1238 bool "Enable eventpoll support" if EXPERT
1da177e4 1239 default y
448e3cee 1240 select ANON_INODES
1da177e4
LT
1241 help
1242 Disabling this option will cause the kernel to be built without
1243 support for epoll family of system calls.
1244
fba2afaa 1245config SIGNALFD
6a108a14 1246 bool "Enable signalfd() system call" if EXPERT
448e3cee 1247 select ANON_INODES
fba2afaa
DL
1248 default y
1249 help
1250 Enable the signalfd() system call that allows to receive signals
1251 on a file descriptor.
1252
1253 If unsure, say Y.
1254
b215e283 1255config TIMERFD
6a108a14 1256 bool "Enable timerfd() system call" if EXPERT
448e3cee 1257 select ANON_INODES
b215e283
DL
1258 default y
1259 help
1260 Enable the timerfd() system call that allows to receive timer
1261 events on a file descriptor.
1262
1263 If unsure, say Y.
1264
e1ad7468 1265config EVENTFD
6a108a14 1266 bool "Enable eventfd() system call" if EXPERT
448e3cee 1267 select ANON_INODES
e1ad7468
DL
1268 default y
1269 help
1270 Enable the eventfd() system call that allows to receive both
1271 kernel notification (ie. KAIO) or userspace notifications.
1272
1273 If unsure, say Y.
1274
1da177e4 1275config SHMEM
6a108a14 1276 bool "Use full shmem filesystem" if EXPERT
1da177e4
LT
1277 default y
1278 depends on MMU
1279 help
1280 The shmem is an internal filesystem used to manage shared memory.
1281 It is backed by swap and manages resource limits. It is also exported
1282 to userspace as tmpfs if TMPFS is enabled. Disabling this
1283 option replaces shmem and tmpfs with the much simpler ramfs code,
1284 which may be appropriate on small systems without swap.
1285
ebf3f09c 1286config AIO
6a108a14 1287 bool "Enable AIO support" if EXPERT
ebf3f09c
TP
1288 default y
1289 help
1290 This option enables POSIX asynchronous I/O which may by used
1291 by some high performance threaded applications. Disabling
1292 this option saves about 7k.
1293
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RD
1294config EMBEDDED
1295 bool "Embedded system"
1296 select EXPERT
1297 help
1298 This option should be enabled if compiling the kernel for
1299 an embedded system so certain expert options are available
1300 for configuration.
1301
cdd6c482 1302config HAVE_PERF_EVENTS
0793a61d 1303 bool
018df72d
MF
1304 help
1305 See tools/perf/design.txt for details.
0793a61d 1306
906010b2
PZ
1307config PERF_USE_VMALLOC
1308 bool
1309 help
1310 See tools/perf/design.txt for details
1311
57c0c15b 1312menu "Kernel Performance Events And Counters"
0793a61d 1313
cdd6c482 1314config PERF_EVENTS
57c0c15b 1315 bool "Kernel performance events and counters"
392d65a9 1316 default y if PROFILING
cdd6c482 1317 depends on HAVE_PERF_EVENTS
4c59e467 1318 select ANON_INODES
e360adbe 1319 select IRQ_WORK
0793a61d 1320 help
57c0c15b
IM
1321 Enable kernel support for various performance events provided
1322 by software and hardware.
0793a61d 1323
dd77038d 1324 Software events are supported either built-in or via the
57c0c15b 1325 use of generic tracepoints.
0793a61d 1326
57c0c15b
IM
1327 Most modern CPUs support performance events via performance
1328 counter registers. These registers count the number of certain
0793a61d
TG
1329 types of hw events: such as instructions executed, cachemisses
1330 suffered, or branches mis-predicted - without slowing down the
1331 kernel or applications. These registers can also trigger interrupts
1332 when a threshold number of events have passed - and can thus be
1333 used to profile the code that runs on that CPU.
1334
57c0c15b 1335 The Linux Performance Event subsystem provides an abstraction of
dd77038d 1336 these software and hardware event capabilities, available via a
57c0c15b 1337 system call and used by the "perf" utility in tools/perf/. It
0793a61d
TG
1338 provides per task and per CPU counters, and it provides event
1339 capabilities on top of those.
1340
1341 Say Y if unsure.
1342
906010b2
PZ
1343config DEBUG_PERF_USE_VMALLOC
1344 default n
1345 bool "Debug: use vmalloc to back perf mmap() buffers"
1346 depends on PERF_EVENTS && DEBUG_KERNEL
1347 select PERF_USE_VMALLOC
1348 help
1349 Use vmalloc memory to back perf mmap() buffers.
1350
1351 Mostly useful for debugging the vmalloc code on platforms
1352 that don't require it.
1353
1354 Say N if unsure.
1355
0793a61d
TG
1356endmenu
1357
f8891e5e
CL
1358config VM_EVENT_COUNTERS
1359 default y
6a108a14 1360 bool "Enable VM event counters for /proc/vmstat" if EXPERT
f8891e5e 1361 help
2aea4fb6
PJ
1362 VM event counters are needed for event counts to be shown.
1363 This option allows the disabling of the VM event counters
6a108a14 1364 on EXPERT systems. /proc/vmstat will only show page counts
2aea4fb6 1365 if VM event counters are disabled.
f8891e5e 1366
3d137310
TP
1367config PCI_QUIRKS
1368 default y
6a108a14 1369 bool "Enable PCI quirk workarounds" if EXPERT
61cfc7e4 1370 depends on PCI
3d137310
TP
1371 help
1372 This enables workarounds for various PCI chipset
1373 bugs/quirks. Disable this only if your target machine is
1374 unaffected by PCI quirks.
1375
41ecc55b
CL
1376config SLUB_DEBUG
1377 default y
6a108a14 1378 bool "Enable SLUB debugging support" if EXPERT
f6acb635 1379 depends on SLUB && SYSFS
41ecc55b
CL
1380 help
1381 SLUB has extensive debug support features. Disabling these can
1382 result in significant savings in code size. This also disables
1383 SLUB sysfs support. /sys/slab will not exist and there will be
1384 no support for cache validation etc.
1385
b943c460
RD
1386config COMPAT_BRK
1387 bool "Disable heap randomization"
1388 default y
1389 help
1390 Randomizing heap placement makes heap exploits harder, but it
1391 also breaks ancient binaries (including anything libc5 based).
1392 This option changes the bootup default to heap randomization
692105b8 1393 disabled, and can be overridden at runtime by setting
b943c460
RD
1394 /proc/sys/kernel/randomize_va_space to 2.
1395
1396 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1397
81819f0f
CL
1398choice
1399 prompt "Choose SLAB allocator"
a0acd820 1400 default SLUB
81819f0f
CL
1401 help
1402 This option allows to select a slab allocator.
1403
1404config SLAB
1405 bool "SLAB"
1406 help
1407 The regular slab allocator that is established and known to work
34013886 1408 well in all environments. It organizes cache hot objects in
02f56210 1409 per cpu and per node queues.
81819f0f
CL
1410
1411config SLUB
81819f0f
CL
1412 bool "SLUB (Unqueued Allocator)"
1413 help
1414 SLUB is a slab allocator that minimizes cache line usage
1415 instead of managing queues of cached objects (SLAB approach).
1416 Per cpu caching is realized using slabs of objects instead
1417 of queues of objects. SLUB can use memory efficiently
02f56210
SA
1418 and has enhanced diagnostics. SLUB is the default choice for
1419 a slab allocator.
81819f0f
CL
1420
1421config SLOB
6a108a14 1422 depends on EXPERT
81819f0f
CL
1423 bool "SLOB (Simple Allocator)"
1424 help
37291458
MM
1425 SLOB replaces the stock allocator with a drastically simpler
1426 allocator. SLOB is generally more space efficient but
1427 does not perform as well on large systems.
81819f0f
CL
1428
1429endchoice
1430
ea637639
JZ
1431config MMAP_ALLOW_UNINITIALIZED
1432 bool "Allow mmapped anonymous memory to be uninitialized"
6a108a14 1433 depends on EXPERT && !MMU
ea637639
JZ
1434 default n
1435 help
1436 Normally, and according to the Linux spec, anonymous memory obtained
1437 from mmap() has it's contents cleared before it is passed to
1438 userspace. Enabling this config option allows you to request that
1439 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1440 providing a huge performance boost. If this option is not enabled,
1441 then the flag will be ignored.
1442
1443 This is taken advantage of by uClibc's malloc(), and also by
1444 ELF-FDPIC binfmt's brk and stack allocator.
1445
1446 Because of the obvious security issues, this option should only be
1447 enabled on embedded devices where you control what is run in
1448 userspace. Since that isn't generally a problem on no-MMU systems,
1449 it is normally safe to say Y here.
1450
1451 See Documentation/nommu-mmap.txt for more information.
1452
125e5645 1453config PROFILING
b309a294 1454 bool "Profiling support"
125e5645
MD
1455 help
1456 Say Y here to enable the extended profiling support mechanisms used
1457 by profilers such as OProfile.
1458
5f87f112
IM
1459#
1460# Place an empty function call at each tracepoint site. Can be
1461# dynamically changed for a probe function.
1462#
97e1c18e 1463config TRACEPOINTS
5f87f112 1464 bool
97e1c18e 1465
fb32e03f
MD
1466source "arch/Kconfig"
1467
1da177e4
LT
1468endmenu # General setup
1469
ee7e5516
DB
1470config HAVE_GENERIC_DMA_COHERENT
1471 bool
1472 default n
1473
158a9624
LT
1474config SLABINFO
1475 bool
1476 depends on PROC_FS
0f389ec6 1477 depends on SLAB || SLUB_DEBUG
158a9624
LT
1478 default y
1479
ae81f9e3
CE
1480config RT_MUTEXES
1481 boolean
ae81f9e3 1482
1da177e4
LT
1483config BASE_SMALL
1484 int
1485 default 0 if BASE_FULL
1486 default 1 if !BASE_FULL
1487
66da5733 1488menuconfig MODULES
1da177e4
LT
1489 bool "Enable loadable module support"
1490 help
1491 Kernel modules are small pieces of compiled code which can
1492 be inserted in the running kernel, rather than being
1493 permanently built into the kernel. You use the "modprobe"
1494 tool to add (and sometimes remove) them. If you say Y here,
1495 many parts of the kernel can be built as modules (by
1496 answering M instead of Y where indicated): this is most
1497 useful for infrequently used options which are not required
1498 for booting. For more information, see the man pages for
1499 modprobe, lsmod, modinfo, insmod and rmmod.
1500
1501 If you say Y here, you will need to run "make
1502 modules_install" to put the modules under /lib/modules/
1503 where modprobe can find them (you may need to be root to do
1504 this).
1505
1506 If unsure, say Y.
1507
0b0de144
RD
1508if MODULES
1509
826e4506
LT
1510config MODULE_FORCE_LOAD
1511 bool "Forced module loading"
826e4506
LT
1512 default n
1513 help
91e37a79
RR
1514 Allow loading of modules without version information (ie. modprobe
1515 --force). Forced module loading sets the 'F' (forced) taint flag and
1516 is usually a really bad idea.
826e4506 1517
1da177e4
LT
1518config MODULE_UNLOAD
1519 bool "Module unloading"
1da177e4
LT
1520 help
1521 Without this option you will not be able to unload any
1522 modules (note that some modules may not be unloadable
f7f5b675
DV
1523 anyway), which makes your kernel smaller, faster
1524 and simpler. If unsure, say Y.
1da177e4
LT
1525
1526config MODULE_FORCE_UNLOAD
1527 bool "Forced module unloading"
1528 depends on MODULE_UNLOAD && EXPERIMENTAL
1529 help
1530 This option allows you to force a module to unload, even if the
1531 kernel believes it is unsafe: the kernel will remove the module
1532 without waiting for anyone to stop using it (using the -f option to
1533 rmmod). This is mainly for kernel developers and desperate users.
1534 If unsure, say N.
1535
1da177e4 1536config MODVERSIONS
0d541643 1537 bool "Module versioning support"
1da177e4
LT
1538 help
1539 Usually, you have to use modules compiled with your kernel.
1540 Saying Y here makes it sometimes possible to use modules
1541 compiled for different kernels, by adding enough information
1542 to the modules to (hopefully) spot any changes which would
1543 make them incompatible with the kernel you are running. If
1544 unsure, say N.
1545
1546config MODULE_SRCVERSION_ALL
1547 bool "Source checksum for all modules"
1da177e4
LT
1548 help
1549 Modules which contain a MODULE_VERSION get an extra "srcversion"
1550 field inserted into their modinfo section, which contains a
1551 sum of the source files which made it. This helps maintainers
1552 see exactly which source was used to build a module (since
1553 others sometimes change the module source without updating
1554 the version). With this option, such a "srcversion" field
1555 will be created for all modules. If unsure, say N.
1556
0b0de144
RD
1557endif # MODULES
1558
98a79d6a
RR
1559config INIT_ALL_POSSIBLE
1560 bool
1561 help
5f054e31
RR
1562 Back when each arch used to define their own cpu_online_mask and
1563 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
98a79d6a
RR
1564 with all 1s, and others with all 0s. When they were centralised,
1565 it was better to provide this option than to break all the archs
692105b8 1566 and have several arch maintainers pursuing me down dark alleys.
98a79d6a 1567
1da177e4
LT
1568config STOP_MACHINE
1569 bool
1570 default y
1571 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1572 help
1573 Need stop_machine() primitive.
3a65dfe8 1574
3a65dfe8 1575source "block/Kconfig"
e98c3202
AK
1576
1577config PREEMPT_NOTIFIERS
1578 bool
e260be67 1579
16295bec
SK
1580config PADATA
1581 depends on SMP
1582 bool
1583
754b7b63
AK
1584# Can be selected by architectures with broken toolchains
1585# that get confused by correct const<->read_only section
1586# mappings
1587config BROKEN_RODATA
1588 bool
1589
6beb0009 1590source "kernel/Kconfig.locks"
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