rcu: Grace-period initialization excludes only RCU notifier
[GitHub/mt8127/android_kernel_alcatel_ttab.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56 drivers that have been replaced by something else, and/or are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_USER_QS
445 bool "Consider userspace as in RCU extended quiescent state"
446 depends on HAVE_RCU_USER_QS && SMP
447 help
448 This option sets hooks on kernel / userspace boundaries and
449 puts RCU in extended quiescent state when the CPU runs in
450 userspace. It means that when a CPU runs in userspace, it is
451 excluded from the global RCU state machine and thus doesn't
452 to keep the timer tick on for RCU.
453
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454config RCU_USER_QS_FORCE
455 bool "Force userspace extended QS by default"
456 depends on RCU_USER_QS
457 help
458 Set the hooks in user/kernel boundaries by default in order to
459 test this feature that treats userspace as an extended quiescent
460 state until we have a real user like a full adaptive nohz option.
461
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462config RCU_FANOUT
463 int "Tree-based hierarchical RCU fanout value"
464 range 2 64 if 64BIT
465 range 2 32 if !64BIT
f41d911f 466 depends on TREE_RCU || TREE_PREEMPT_RCU
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467 default 64 if 64BIT
468 default 32 if !64BIT
469 help
470 This option controls the fanout of hierarchical implementations
471 of RCU, allowing RCU to work efficiently on machines with
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472 large numbers of CPUs. This value must be at least the fourth
473 root of NR_CPUS, which allows NR_CPUS to be insanely large.
474 The default value of RCU_FANOUT should be used for production
475 systems, but if you are stress-testing the RCU implementation
476 itself, small RCU_FANOUT values allow you to test large-system
477 code paths on small(er) systems.
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478
479 Select a specific number if testing RCU itself.
480 Take the default if unsure.
481
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482config RCU_FANOUT_LEAF
483 int "Tree-based hierarchical RCU leaf-level fanout value"
484 range 2 RCU_FANOUT if 64BIT
485 range 2 RCU_FANOUT if !64BIT
486 depends on TREE_RCU || TREE_PREEMPT_RCU
487 default 16
488 help
489 This option controls the leaf-level fanout of hierarchical
490 implementations of RCU, and allows trading off cache misses
491 against lock contention. Systems that synchronize their
492 scheduling-clock interrupts for energy-efficiency reasons will
493 want the default because the smaller leaf-level fanout keeps
494 lock contention levels acceptably low. Very large systems
495 (hundreds or thousands of CPUs) will instead want to set this
496 value to the maximum value possible in order to reduce the
497 number of cache misses incurred during RCU's grace-period
498 initialization. These systems tend to run CPU-bound, and thus
499 are not helped by synchronized interrupts, and thus tend to
500 skew them, which reduces lock contention enough that large
501 leaf-level fanouts work well.
502
503 Select a specific number if testing RCU itself.
504
505 Select the maximum permissible value for large systems.
506
507 Take the default if unsure.
508
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509config RCU_FANOUT_EXACT
510 bool "Disable tree-based hierarchical RCU auto-balancing"
f41d911f 511 depends on TREE_RCU || TREE_PREEMPT_RCU
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512 default n
513 help
514 This option forces use of the exact RCU_FANOUT value specified,
515 regardless of imbalances in the hierarchy. This is useful for
516 testing RCU itself, and might one day be useful on systems with
517 strong NUMA behavior.
518
519 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
520
521 Say N if unsure.
522
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523config RCU_FAST_NO_HZ
524 bool "Accelerate last non-dyntick-idle CPU's grace periods"
b807fbff 525 depends on NO_HZ && SMP
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526 default n
527 help
528 This option causes RCU to attempt to accelerate grace periods
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529 in order to allow CPUs to enter dynticks-idle state more
530 quickly. On the other hand, this option increases the overhead
531 of the dynticks-idle checking, particularly on systems with
532 large numbers of CPUs.
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533
534 Say Y if energy efficiency is critically important, particularly
535 if you have relatively few CPUs.
536
537 Say N if you are unsure.
538
c903ff83 539config TREE_RCU_TRACE
f41d911f 540 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
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541 select DEBUG_FS
542 help
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543 This option provides tracing for the TREE_RCU and
544 TREE_PREEMPT_RCU implementations, permitting Makefile to
545 trivially select kernel/rcutree_trace.c.
c903ff83 546
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547config RCU_BOOST
548 bool "Enable RCU priority boosting"
27f4d280 549 depends on RT_MUTEXES && PREEMPT_RCU
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550 default n
551 help
552 This option boosts the priority of preempted RCU readers that
553 block the current preemptible RCU grace period for too long.
554 This option also prevents heavy loads from blocking RCU
555 callback invocation for all flavors of RCU.
556
557 Say Y here if you are working with real-time apps or heavy loads
558 Say N here if you are unsure.
559
560config RCU_BOOST_PRIO
561 int "Real-time priority to boost RCU readers to"
562 range 1 99
563 depends on RCU_BOOST
564 default 1
565 help
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566 This option specifies the real-time priority to which long-term
567 preempted RCU readers are to be boosted. If you are working
568 with a real-time application that has one or more CPU-bound
569 threads running at a real-time priority level, you should set
570 RCU_BOOST_PRIO to a priority higher then the highest-priority
571 real-time CPU-bound thread. The default RCU_BOOST_PRIO value
572 of 1 is appropriate in the common case, which is real-time
573 applications that do not have any CPU-bound threads.
574
575 Some real-time applications might not have a single real-time
576 thread that saturates a given CPU, but instead might have
577 multiple real-time threads that, taken together, fully utilize
578 that CPU. In this case, you should set RCU_BOOST_PRIO to
579 a priority higher than the lowest-priority thread that is
580 conspiring to prevent the CPU from running any non-real-time
581 tasks. For example, if one thread at priority 10 and another
582 thread at priority 5 are between themselves fully consuming
583 the CPU time on a given CPU, then RCU_BOOST_PRIO should be
584 set to priority 6 or higher.
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585
586 Specify the real-time priority, or take the default if unsure.
587
588config RCU_BOOST_DELAY
589 int "Milliseconds to delay boosting after RCU grace-period start"
590 range 0 3000
591 depends on RCU_BOOST
592 default 500
593 help
594 This option specifies the time to wait after the beginning of
595 a given grace period before priority-boosting preempted RCU
596 readers blocking that grace period. Note that any RCU reader
597 blocking an expedited RCU grace period is boosted immediately.
598
599 Accept the default if unsure.
600
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601endmenu # "RCU Subsystem"
602
1da177e4 603config IKCONFIG
f2443ab6 604 tristate "Kernel .config support"
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605 ---help---
606 This option enables the complete Linux kernel ".config" file
607 contents to be saved in the kernel. It provides documentation
608 of which kernel options are used in a running kernel or in an
609 on-disk kernel. This information can be extracted from the kernel
610 image file with the script scripts/extract-ikconfig and used as
611 input to rebuild the current kernel or to build another kernel.
612 It can also be extracted from a running kernel by reading
613 /proc/config.gz if enabled (below).
614
615config IKCONFIG_PROC
616 bool "Enable access to .config through /proc/config.gz"
617 depends on IKCONFIG && PROC_FS
618 ---help---
619 This option enables access to the kernel configuration file
620 through /proc/config.gz.
621
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622config LOG_BUF_SHIFT
623 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
624 range 12 21
f17a32e9 625 default 17
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626 help
627 Select kernel log buffer size as a power of 2.
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628 Examples:
629 17 => 128 KB
630 16 => 64 KB
631 15 => 32 KB
632 14 => 16 KB
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633 13 => 8 KB
634 12 => 4 KB
635
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636#
637# Architectures with an unreliable sched_clock() should select this:
638#
639config HAVE_UNSTABLE_SCHED_CLOCK
640 bool
641
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642menuconfig CGROUPS
643 boolean "Control Group support"
0dea1168 644 depends on EVENTFD
5cdc38f9 645 help
23964d2d 646 This option adds support for grouping sets of processes together, for
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647 use with process control subsystems such as Cpusets, CFS, memory
648 controls or device isolation.
649 See
5cdc38f9 650 - Documentation/scheduler/sched-design-CFS.txt (CFS)
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651 - Documentation/cgroups/ (features for grouping, isolation
652 and resource control)
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653
654 Say N if unsure.
655
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656if CGROUPS
657
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658config CGROUP_DEBUG
659 bool "Example debug cgroup subsystem"
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660 default n
661 help
662 This option enables a simple cgroup subsystem that
663 exports useful debugging information about the cgroups
23964d2d 664 framework.
5cdc38f9 665
23964d2d 666 Say N if unsure.
5cdc38f9 667
5cdc38f9 668config CGROUP_FREEZER
23964d2d 669 bool "Freezer cgroup subsystem"
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670 help
671 Provides a way to freeze and unfreeze all tasks in a
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672 cgroup.
673
674config CGROUP_DEVICE
675 bool "Device controller for cgroups"
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676 help
677 Provides a cgroup implementing whitelists for devices which
678 a process in the cgroup can mknod or open.
679
680config CPUSETS
681 bool "Cpuset support"
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682 help
683 This option will let you create and manage CPUSETs which
684 allow dynamically partitioning a system into sets of CPUs and
685 Memory Nodes and assigning tasks to run only within those sets.
686 This is primarily useful on large SMP or NUMA systems.
687
688 Say N if unsure.
689
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690config PROC_PID_CPUSET
691 bool "Include legacy /proc/<pid>/cpuset file"
692 depends on CPUSETS
693 default y
694
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695config CGROUP_CPUACCT
696 bool "Simple CPU accounting cgroup subsystem"
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697 help
698 Provides a simple Resource Controller for monitoring the
23964d2d 699 total CPU consumed by the tasks in a cgroup.
d842de87 700
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701config RESOURCE_COUNTERS
702 bool "Resource counters"
703 help
704 This option enables controller independent resource accounting
23964d2d 705 infrastructure that works with cgroups.
e552b661 706
c255a458 707config MEMCG
00f0b825 708 bool "Memory Resource Controller for Control Groups"
79ae9c29 709 depends on RESOURCE_COUNTERS
cf475ad2 710 select MM_OWNER
00f0b825 711 help
84ad6d70 712 Provides a memory resource controller that manages both anonymous
21acb9ca 713 memory and page cache. (See Documentation/cgroups/memory.txt)
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714
715 Note that setting this option increases fixed memory overhead
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716 associated with each page of memory in the system. By this,
717 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
718 usage tracking struct at boot. Total amount of this is printed out
719 at boot.
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720
721 Only enable when you're ok with these trade offs and really
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722 sure you need the memory resource controller. Even when you enable
723 this, you can set "cgroup_disable=memory" at your boot option to
724 disable memory resource controller and you can avoid overheads.
c9d5409f 725 (and lose benefits of memory resource controller)
00f0b825 726
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727 This config option also selects MM_OWNER config option, which
728 could in turn add some fork/exit overhead.
729
c255a458 730config MEMCG_SWAP
65e0e811 731 bool "Memory Resource Controller Swap Extension"
c255a458 732 depends on MEMCG && SWAP
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733 help
734 Add swap management feature to memory resource controller. When you
735 enable this, you can limit mem+swap usage per cgroup. In other words,
736 when you disable this, memory resource controller has no cares to
737 usage of swap...a process can exhaust all of the swap. This extension
738 is useful when you want to avoid exhaustion swap but this itself
739 adds more overheads and consumes memory for remembering information.
740 Especially if you use 32bit system or small memory system, please
741 be careful about enabling this. When memory resource controller
742 is disabled by boot option, this will be automatically disabled and
743 there will be no overhead from this. Even when you set this config=y,
00a66d29 744 if boot option "swapaccount=0" is set, swap will not be accounted.
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745 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
746 size is 4096bytes, 512k per 1Gbytes of swap.
c255a458 747config MEMCG_SWAP_ENABLED
a42c390c 748 bool "Memory Resource Controller Swap Extension enabled by default"
c255a458 749 depends on MEMCG_SWAP
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750 default y
751 help
752 Memory Resource Controller Swap Extension comes with its price in
753 a bigger memory consumption. General purpose distribution kernels
43d547f9 754 which want to enable the feature but keep it disabled by default
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755 and let the user enable it by swapaccount boot command line
756 parameter should have this option unselected.
757 For those who want to have the feature enabled by default should
758 select this option (if, for some reason, they need to disable it
00a66d29 759 then swapaccount=0 does the trick).
c255a458 760config MEMCG_KMEM
e5671dfa 761 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
c255a458 762 depends on MEMCG && EXPERIMENTAL
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763 default n
764 help
765 The Kernel Memory extension for Memory Resource Controller can limit
766 the amount of memory used by kernel objects in the system. Those are
767 fundamentally different from the entities handled by the standard
768 Memory Controller, which are page-based, and can be swapped. Users of
769 the kmem extension can use it to guarantee that no group of processes
770 will ever exhaust kernel resources alone.
c077719b 771
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772config CGROUP_HUGETLB
773 bool "HugeTLB Resource Controller for Control Groups"
774 depends on RESOURCE_COUNTERS && HUGETLB_PAGE && EXPERIMENTAL
775 default n
776 help
777 Provides a cgroup Resource Controller for HugeTLB pages.
778 When you enable this, you can put a per cgroup limit on HugeTLB usage.
779 The limit is enforced during page fault. Since HugeTLB doesn't
780 support page reclaim, enforcing the limit at page fault time implies
781 that, the application will get SIGBUS signal if it tries to access
782 HugeTLB pages beyond its limit. This requires the application to know
783 beforehand how much HugeTLB pages it would require for its use. The
784 control group is tracked in the third page lru pointer. This means
785 that we cannot use the controller with huge page less than 3 pages.
786
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787config CGROUP_PERF
788 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
789 depends on PERF_EVENTS && CGROUPS
790 help
791 This option extends the per-cpu mode to restrict monitoring to
2d0f2520 792 threads which belong to the cgroup specified and run on the
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793 designated cpu.
794
795 Say N if unsure.
796
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797menuconfig CGROUP_SCHED
798 bool "Group CPU scheduler"
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799 default n
800 help
801 This feature lets CPU scheduler recognize task groups and control CPU
802 bandwidth allocation to such task groups. It uses cgroups to group
803 tasks.
804
805if CGROUP_SCHED
806config FAIR_GROUP_SCHED
807 bool "Group scheduling for SCHED_OTHER"
808 depends on CGROUP_SCHED
809 default CGROUP_SCHED
810
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811config CFS_BANDWIDTH
812 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
813 depends on EXPERIMENTAL
814 depends on FAIR_GROUP_SCHED
815 default n
816 help
817 This option allows users to define CPU bandwidth rates (limits) for
818 tasks running within the fair group scheduler. Groups with no limit
819 set are considered to be unconstrained and will run with no
820 restriction.
821 See tip/Documentation/scheduler/sched-bwc.txt for more information.
822
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823config RT_GROUP_SCHED
824 bool "Group scheduling for SCHED_RR/FIFO"
825 depends on EXPERIMENTAL
826 depends on CGROUP_SCHED
827 default n
828 help
829 This feature lets you explicitly allocate real CPU bandwidth
32bd7eb5 830 to task groups. If enabled, it will also make it impossible to
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831 schedule realtime tasks for non-root users until you allocate
832 realtime bandwidth for them.
833 See Documentation/scheduler/sched-rt-group.txt for more information.
834
835endif #CGROUP_SCHED
836
afc24d49 837config BLK_CGROUP
32e380ae 838 bool "Block IO controller"
79ae9c29 839 depends on BLOCK
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840 default n
841 ---help---
842 Generic block IO controller cgroup interface. This is the common
843 cgroup interface which should be used by various IO controlling
844 policies.
845
846 Currently, CFQ IO scheduler uses it to recognize task groups and
847 control disk bandwidth allocation (proportional time slice allocation)
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848 to such task groups. It is also used by bio throttling logic in
849 block layer to implement upper limit in IO rates on a device.
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850
851 This option only enables generic Block IO controller infrastructure.
e43473b7 852 One needs to also enable actual IO controlling logic/policy. For
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853 enabling proportional weight division of disk bandwidth in CFQ, set
854 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
c5e0591a 855 CONFIG_BLK_DEV_THROTTLING=y.
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856
857 See Documentation/cgroups/blkio-controller.txt for more information.
858
859config DEBUG_BLK_CGROUP
860 bool "Enable Block IO controller debugging"
861 depends on BLK_CGROUP
862 default n
863 ---help---
864 Enable some debugging help. Currently it exports additional stat
865 files in a cgroup which can be useful for debugging.
866
23964d2d 867endif # CGROUPS
c077719b 868
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CG
869config CHECKPOINT_RESTORE
870 bool "Checkpoint/restore support" if EXPERT
871 default n
872 help
873 Enables additional kernel features in a sake of checkpoint/restore.
874 In particular it adds auxiliary prctl codes to setup process text,
875 data and heap segment sizes, and a few additional /proc filesystem
876 entries.
877
878 If unsure, say N here.
879
8dd2a82c 880menuconfig NAMESPACES
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881 bool "Namespaces support" if EXPERT
882 default !EXPERT
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883 help
884 Provides the way to make tasks work with different objects using
885 the same id. For example same IPC id may refer to different objects
886 or same user id or pid may refer to different tasks when used in
887 different namespaces.
888
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889if NAMESPACES
890
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891config UTS_NS
892 bool "UTS namespace"
17a6d441 893 default y
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894 help
895 In this namespace tasks see different info provided with the
896 uname() system call
897
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898config IPC_NS
899 bool "IPC namespace"
8dd2a82c 900 depends on (SYSVIPC || POSIX_MQUEUE)
17a6d441 901 default y
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902 help
903 In this namespace tasks work with IPC ids which correspond to
614b84cf 904 different IPC objects in different namespaces.
ae5e1b22 905
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906config USER_NS
907 bool "User namespace (EXPERIMENTAL)"
8dd2a82c 908 depends on EXPERIMENTAL
e1c972b6 909 depends on UIDGID_CONVERTED
5673a94c 910 select UIDGID_STRICT_TYPE_CHECKS
e1c972b6 911
5673a94c 912 default n
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913 help
914 This allows containers, i.e. vservers, to use user namespaces
915 to provide different user info for different servers.
916 If unsure, say N.
917
74bd59bb 918config PID_NS
9bd38c2c 919 bool "PID Namespaces"
17a6d441 920 default y
74bd59bb 921 help
12d2b8f9 922 Support process id namespaces. This allows having multiple
692105b8 923 processes with the same pid as long as they are in different
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924 pid namespaces. This is a building block of containers.
925
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MH
926config NET_NS
927 bool "Network namespace"
8dd2a82c 928 depends on NET
17a6d441 929 default y
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MH
930 help
931 Allow user space to create what appear to be multiple instances
932 of the network stack.
933
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DL
934endif # NAMESPACES
935
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EB
936config UIDGID_CONVERTED
937 # True if all of the selected software conmponents are known
938 # to have uid_t and gid_t converted to kuid_t and kgid_t
939 # where appropriate and are otherwise safe to use with
940 # the user namespace.
941 bool
942 default y
943
944 # List of kernel pieces that need user namespace work
945 # Features
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EB
946 depends on SYSVIPC = n
947 depends on IMA = n
948 depends on EVM = n
949 depends on KEYS = n
950 depends on AUDIT = n
951 depends on AUDITSYSCALL = n
952 depends on TASKSTATS = n
953 depends on TRACING = n
954 depends on FS_POSIX_ACL = n
955 depends on QUOTA = n
956 depends on QUOTACTL = n
957 depends on DEBUG_CREDENTIALS = n
958 depends on BSD_PROCESS_ACCT = n
959 depends on DRM = n
960 depends on PROC_EVENTS = n
961
962 # Networking
963 depends on NET = n
964 depends on NET_9P = n
965 depends on IPX = n
966 depends on PHONET = n
967 depends on NET_CLS_FLOW = n
968 depends on NETFILTER_XT_MATCH_OWNER = n
969 depends on NETFILTER_XT_MATCH_RECENT = n
970 depends on NETFILTER_XT_TARGET_LOG = n
971 depends on NETFILTER_NETLINK_LOG = n
972 depends on INET = n
973 depends on IPV6 = n
974 depends on IP_SCTP = n
975 depends on AF_RXRPC = n
976 depends on LLC2 = n
977 depends on NET_KEY = n
978 depends on INET_DIAG = n
979 depends on DNS_RESOLVER = n
980 depends on AX25 = n
981 depends on ATALK = n
982
983 # Filesystems
984 depends on USB_DEVICEFS = n
985 depends on USB_GADGETFS = n
986 depends on USB_FUNCTIONFS = n
987 depends on DEVTMPFS = n
988 depends on XENFS = n
989
990 depends on 9P_FS = n
991 depends on ADFS_FS = n
992 depends on AFFS_FS = n
993 depends on AFS_FS = n
994 depends on AUTOFS4_FS = n
995 depends on BEFS_FS = n
996 depends on BFS_FS = n
997 depends on BTRFS_FS = n
998 depends on CEPH_FS = n
999 depends on CIFS = n
1000 depends on CODA_FS = n
1001 depends on CONFIGFS_FS = n
1002 depends on CRAMFS = n
1003 depends on DEBUG_FS = n
1004 depends on ECRYPT_FS = n
1005 depends on EFS_FS = n
1006 depends on EXOFS_FS = n
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EB
1007 depends on FAT_FS = n
1008 depends on FUSE_FS = n
1009 depends on GFS2_FS = n
1010 depends on HFS_FS = n
1011 depends on HFSPLUS_FS = n
1012 depends on HPFS_FS = n
1013 depends on HUGETLBFS = n
1014 depends on ISO9660_FS = n
1015 depends on JFFS2_FS = n
1016 depends on JFS_FS = n
1017 depends on LOGFS = n
1018 depends on MINIX_FS = n
1019 depends on NCP_FS = n
1020 depends on NFSD = n
1021 depends on NFS_FS = n
1022 depends on NILFS2_FS = n
1023 depends on NTFS_FS = n
1024 depends on OCFS2_FS = n
1025 depends on OMFS_FS = n
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EB
1026 depends on QNX4FS_FS = n
1027 depends on QNX6FS_FS = n
1028 depends on REISERFS_FS = n
1029 depends on SQUASHFS = n
e1c972b6 1030 depends on SYSV_FS = n
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EB
1031 depends on UBIFS_FS = n
1032 depends on UDF_FS = n
1033 depends on UFS_FS = n
1034 depends on VXFS_FS = n
1035 depends on XFS_FS = n
1036
1037 depends on !UML || HOSTFS = n
1038
1039 # The rare drivers that won't build
1040 depends on AIRO = n
1041 depends on AIRO_CS = n
1042 depends on TUN = n
1043 depends on INFINIBAND_QIB = n
1044 depends on BLK_DEV_LOOP = n
1045 depends on ANDROID_BINDER_IPC = n
1046
1047 # Security modules
1048 depends on SECURITY_TOMOYO = n
1049 depends on SECURITY_APPARMOR = n
1050
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EB
1051config UIDGID_STRICT_TYPE_CHECKS
1052 bool "Require conversions between uid/gids and their internal representation"
e1c972b6 1053 depends on UIDGID_CONVERTED
5673a94c
EB
1054 default n
1055 help
1056 While the nececessary conversions are being added to all subsystems this option allows
1057 the code to continue to build for unconverted subsystems.
1058
1059 Say Y here if you want the strict type checking enabled
1060
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MG
1061config SCHED_AUTOGROUP
1062 bool "Automatic process group scheduling"
1063 select EVENTFD
1064 select CGROUPS
1065 select CGROUP_SCHED
1066 select FAIR_GROUP_SCHED
1067 help
1068 This option optimizes the scheduler for common desktop workloads by
1069 automatically creating and populating task groups. This separation
1070 of workloads isolates aggressive CPU burners (like build jobs) from
1071 desktop applications. Task group autogeneration is currently based
1072 upon task session.
1073
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DL
1074config MM_OWNER
1075 bool
1076
1077config SYSFS_DEPRECATED
5d6a4ea5 1078 bool "Enable deprecated sysfs features to support old userspace tools"
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DL
1079 depends on SYSFS
1080 default n
1081 help
1082 This option adds code that switches the layout of the "block" class
1083 devices, to not show up in /sys/class/block/, but only in
1084 /sys/block/.
1085
1086 This switch is only active when the sysfs.deprecated=1 boot option is
1087 passed or the SYSFS_DEPRECATED_V2 option is set.
1088
1089 This option allows new kernels to run on old distributions and tools,
1090 which might get confused by /sys/class/block/. Since 2007/2008 all
1091 major distributions and tools handle this just fine.
1092
1093 Recent distributions and userspace tools after 2009/2010 depend on
1094 the existence of /sys/class/block/, and will not work with this
1095 option enabled.
1096
1097 Only if you are using a new kernel on an old distribution, you might
1098 need to say Y here.
1099
1100config SYSFS_DEPRECATED_V2
5d6a4ea5 1101 bool "Enable deprecated sysfs features by default"
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DL
1102 default n
1103 depends on SYSFS
1104 depends on SYSFS_DEPRECATED
1105 help
1106 Enable deprecated sysfs by default.
1107
1108 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1109 option.
1110
1111 Only if you are using a new kernel on an old distribution, you might
1112 need to say Y here. Even then, odds are you would not need it
1113 enabled, you can always pass the boot option if absolutely necessary.
1114
1115config RELAY
1116 bool "Kernel->user space relay support (formerly relayfs)"
1117 help
1118 This option enables support for relay interface support in
1119 certain file systems (such as debugfs).
1120 It is designed to provide an efficient mechanism for tools and
1121 facilities to relay large amounts of data from kernel space to
1122 user space.
1123
1124 If unsure, say N.
1125
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1126config BLK_DEV_INITRD
1127 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1128 depends on BROKEN || !FRV
1129 help
1130 The initial RAM filesystem is a ramfs which is loaded by the
1131 boot loader (loadlin or lilo) and that is mounted as root
1132 before the normal boot procedure. It is typically used to
1133 load modules needed to mount the "real" root file system,
1134 etc. See <file:Documentation/initrd.txt> for details.
1135
1136 If RAM disk support (BLK_DEV_RAM) is also included, this
1137 also enables initial RAM disk (initrd) support and adds
1138 15 Kbytes (more on some other architectures) to the kernel size.
1139
1140 If unsure say Y.
1141
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JPS
1142if BLK_DEV_INITRD
1143
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SR
1144source "usr/Kconfig"
1145
c33df4ea
JPS
1146endif
1147
c45b4f1f 1148config CC_OPTIMIZE_FOR_SIZE
96fffeb4 1149 bool "Optimize for size"
c45b4f1f
LT
1150 help
1151 Enabling this option will pass "-Os" instead of "-O2" to gcc
1152 resulting in a smaller kernel.
1153
775a7229 1154 If unsure, say Y.
c45b4f1f 1155
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RD
1156config SYSCTL
1157 bool
1158
b943c460
RD
1159config ANON_INODES
1160 bool
1161
6a108a14
DR
1162menuconfig EXPERT
1163 bool "Configure standard kernel features (expert users)"
f505c553
JT
1164 # Unhide debug options, to make the on-by-default options visible
1165 select DEBUG_KERNEL
1da177e4
LT
1166 help
1167 This option allows certain base kernel options and settings
1168 to be disabled or tweaked. This is for specialized
1169 environments which can tolerate a "non-standard" kernel.
1170 Only use this if you really know what you are doing.
1171
ae81f9e3 1172config UID16
6a108a14 1173 bool "Enable 16-bit UID system calls" if EXPERT
09337f50 1174 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
ae81f9e3
CE
1175 default y
1176 help
1177 This enables the legacy 16-bit UID syscall wrappers.
1178
b89a8171 1179config SYSCTL_SYSCALL
6a108a14 1180 bool "Sysctl syscall support" if EXPERT
26a7034b 1181 depends on PROC_SYSCTL
c736de60 1182 default n
b89a8171 1183 select SYSCTL
ae81f9e3 1184 ---help---
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EB
1185 sys_sysctl uses binary paths that have been found challenging
1186 to properly maintain and use. The interface in /proc/sys
1187 using paths with ascii names is now the primary path to this
1188 information.
b89a8171 1189
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1190 Almost nothing using the binary sysctl interface so if you are
1191 trying to save some space it is probably safe to disable this,
1192 making your kernel marginally smaller.
b89a8171 1193
c736de60 1194 If unsure say N here.
ae81f9e3 1195
1da177e4 1196config KALLSYMS
6a108a14 1197 bool "Load all symbols for debugging/ksymoops" if EXPERT
1da177e4
LT
1198 default y
1199 help
1200 Say Y here to let the kernel print out symbolic crash information and
1201 symbolic stack backtraces. This increases the size of the kernel
1202 somewhat, as all symbols have to be loaded into the kernel image.
1203
1204config KALLSYMS_ALL
1205 bool "Include all symbols in kallsyms"
1206 depends on DEBUG_KERNEL && KALLSYMS
1207 help
71a83ec7
AB
1208 Normally kallsyms only contains the symbols of functions for nicer
1209 OOPS messages and backtraces (i.e., symbols from the text and inittext
1210 sections). This is sufficient for most cases. And only in very rare
1211 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1212 names of variables from the data sections, etc).
1213
1214 This option makes sure that all symbols are loaded into the kernel
1215 image (i.e., symbols from all sections) in cost of increased kernel
1216 size (depending on the kernel configuration, it may be 300KiB or
1217 something like this).
1218
1219 Say N unless you really need all symbols.
d59745ce 1220
712f47ce 1221config HOTPLUG
6a108a14 1222 bool "Support for hot-pluggable devices" if EXPERT
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GKH
1223 default y
1224 help
1225 This option is provided for the case where no hotplug or uevent
1226 capabilities is wanted by the kernel. You should only consider
1227 disabling this option for embedded systems that do not use modules, a
1228 dynamic /dev tree, or dynamic device discovery. Just say Y.
1229
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1230config PRINTK
1231 default y
6a108a14 1232 bool "Enable support for printk" if EXPERT
d59745ce
MM
1233 help
1234 This option enables normal printk support. Removing it
1235 eliminates most of the message strings from the kernel image
1236 and makes the kernel more or less silent. As this makes it
1237 very difficult to diagnose system problems, saying N here is
1238 strongly discouraged.
1239
c8538a7a 1240config BUG
6a108a14 1241 bool "BUG() support" if EXPERT
c8538a7a
MM
1242 default y
1243 help
1244 Disabling this option eliminates support for BUG and WARN, reducing
1245 the size of your kernel image and potentially quietly ignoring
1246 numerous fatal conditions. You should only consider disabling this
1247 option for embedded systems with no facilities for reporting errors.
1248 Just say Y.
1249
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MM
1250config ELF_CORE
1251 default y
6a108a14 1252 bool "Enable ELF core dumps" if EXPERT
708e9a79
MM
1253 help
1254 Enable support for generating core dumps. Disabling saves about 4k.
1255
8761f1ab 1256
e5e1d3cb 1257config PCSPKR_PLATFORM
6a108a14 1258 bool "Enable PC-Speaker support" if EXPERT
8761f1ab 1259 depends on HAVE_PCSPKR_PLATFORM
15f304b6 1260 select I8253_LOCK
e5e1d3cb
SS
1261 default y
1262 help
1263 This option allows to disable the internal PC-Speaker
1264 support, saving some memory.
1265
8761f1ab
RB
1266config HAVE_PCSPKR_PLATFORM
1267 bool
1268
1da177e4
LT
1269config BASE_FULL
1270 default y
6a108a14 1271 bool "Enable full-sized data structures for core" if EXPERT
1da177e4
LT
1272 help
1273 Disabling this option reduces the size of miscellaneous core
1274 kernel data structures. This saves memory on small machines,
1275 but may reduce performance.
1276
1277config FUTEX
6a108a14 1278 bool "Enable futex support" if EXPERT
1da177e4 1279 default y
23f78d4a 1280 select RT_MUTEXES
1da177e4
LT
1281 help
1282 Disabling this option will cause the kernel to be built without
1283 support for "fast userspace mutexes". The resulting kernel may not
1284 run glibc-based applications correctly.
1285
1286config EPOLL
6a108a14 1287 bool "Enable eventpoll support" if EXPERT
1da177e4 1288 default y
448e3cee 1289 select ANON_INODES
1da177e4
LT
1290 help
1291 Disabling this option will cause the kernel to be built without
1292 support for epoll family of system calls.
1293
fba2afaa 1294config SIGNALFD
6a108a14 1295 bool "Enable signalfd() system call" if EXPERT
448e3cee 1296 select ANON_INODES
fba2afaa
DL
1297 default y
1298 help
1299 Enable the signalfd() system call that allows to receive signals
1300 on a file descriptor.
1301
1302 If unsure, say Y.
1303
b215e283 1304config TIMERFD
6a108a14 1305 bool "Enable timerfd() system call" if EXPERT
448e3cee 1306 select ANON_INODES
b215e283
DL
1307 default y
1308 help
1309 Enable the timerfd() system call that allows to receive timer
1310 events on a file descriptor.
1311
1312 If unsure, say Y.
1313
e1ad7468 1314config EVENTFD
6a108a14 1315 bool "Enable eventfd() system call" if EXPERT
448e3cee 1316 select ANON_INODES
e1ad7468
DL
1317 default y
1318 help
1319 Enable the eventfd() system call that allows to receive both
1320 kernel notification (ie. KAIO) or userspace notifications.
1321
1322 If unsure, say Y.
1323
1da177e4 1324config SHMEM
6a108a14 1325 bool "Use full shmem filesystem" if EXPERT
1da177e4
LT
1326 default y
1327 depends on MMU
1328 help
1329 The shmem is an internal filesystem used to manage shared memory.
1330 It is backed by swap and manages resource limits. It is also exported
1331 to userspace as tmpfs if TMPFS is enabled. Disabling this
1332 option replaces shmem and tmpfs with the much simpler ramfs code,
1333 which may be appropriate on small systems without swap.
1334
ebf3f09c 1335config AIO
6a108a14 1336 bool "Enable AIO support" if EXPERT
ebf3f09c
TP
1337 default y
1338 help
1339 This option enables POSIX asynchronous I/O which may by used
1340 by some high performance threaded applications. Disabling
1341 this option saves about 7k.
1342
6befe5f6
RD
1343config EMBEDDED
1344 bool "Embedded system"
1345 select EXPERT
1346 help
1347 This option should be enabled if compiling the kernel for
1348 an embedded system so certain expert options are available
1349 for configuration.
1350
cdd6c482 1351config HAVE_PERF_EVENTS
0793a61d 1352 bool
018df72d
MF
1353 help
1354 See tools/perf/design.txt for details.
0793a61d 1355
906010b2
PZ
1356config PERF_USE_VMALLOC
1357 bool
1358 help
1359 See tools/perf/design.txt for details
1360
57c0c15b 1361menu "Kernel Performance Events And Counters"
0793a61d 1362
cdd6c482 1363config PERF_EVENTS
57c0c15b 1364 bool "Kernel performance events and counters"
392d65a9 1365 default y if PROFILING
cdd6c482 1366 depends on HAVE_PERF_EVENTS
4c59e467 1367 select ANON_INODES
e360adbe 1368 select IRQ_WORK
0793a61d 1369 help
57c0c15b
IM
1370 Enable kernel support for various performance events provided
1371 by software and hardware.
0793a61d 1372
dd77038d 1373 Software events are supported either built-in or via the
57c0c15b 1374 use of generic tracepoints.
0793a61d 1375
57c0c15b
IM
1376 Most modern CPUs support performance events via performance
1377 counter registers. These registers count the number of certain
0793a61d
TG
1378 types of hw events: such as instructions executed, cachemisses
1379 suffered, or branches mis-predicted - without slowing down the
1380 kernel or applications. These registers can also trigger interrupts
1381 when a threshold number of events have passed - and can thus be
1382 used to profile the code that runs on that CPU.
1383
57c0c15b 1384 The Linux Performance Event subsystem provides an abstraction of
dd77038d 1385 these software and hardware event capabilities, available via a
57c0c15b 1386 system call and used by the "perf" utility in tools/perf/. It
0793a61d
TG
1387 provides per task and per CPU counters, and it provides event
1388 capabilities on top of those.
1389
1390 Say Y if unsure.
1391
906010b2
PZ
1392config DEBUG_PERF_USE_VMALLOC
1393 default n
1394 bool "Debug: use vmalloc to back perf mmap() buffers"
1395 depends on PERF_EVENTS && DEBUG_KERNEL
1396 select PERF_USE_VMALLOC
1397 help
1398 Use vmalloc memory to back perf mmap() buffers.
1399
1400 Mostly useful for debugging the vmalloc code on platforms
1401 that don't require it.
1402
1403 Say N if unsure.
1404
0793a61d
TG
1405endmenu
1406
f8891e5e
CL
1407config VM_EVENT_COUNTERS
1408 default y
6a108a14 1409 bool "Enable VM event counters for /proc/vmstat" if EXPERT
f8891e5e 1410 help
2aea4fb6
PJ
1411 VM event counters are needed for event counts to be shown.
1412 This option allows the disabling of the VM event counters
6a108a14 1413 on EXPERT systems. /proc/vmstat will only show page counts
2aea4fb6 1414 if VM event counters are disabled.
f8891e5e 1415
3d137310
TP
1416config PCI_QUIRKS
1417 default y
6a108a14 1418 bool "Enable PCI quirk workarounds" if EXPERT
61cfc7e4 1419 depends on PCI
3d137310
TP
1420 help
1421 This enables workarounds for various PCI chipset
1422 bugs/quirks. Disable this only if your target machine is
1423 unaffected by PCI quirks.
1424
41ecc55b
CL
1425config SLUB_DEBUG
1426 default y
6a108a14 1427 bool "Enable SLUB debugging support" if EXPERT
f6acb635 1428 depends on SLUB && SYSFS
41ecc55b
CL
1429 help
1430 SLUB has extensive debug support features. Disabling these can
1431 result in significant savings in code size. This also disables
1432 SLUB sysfs support. /sys/slab will not exist and there will be
1433 no support for cache validation etc.
1434
b943c460
RD
1435config COMPAT_BRK
1436 bool "Disable heap randomization"
1437 default y
1438 help
1439 Randomizing heap placement makes heap exploits harder, but it
1440 also breaks ancient binaries (including anything libc5 based).
1441 This option changes the bootup default to heap randomization
692105b8 1442 disabled, and can be overridden at runtime by setting
b943c460
RD
1443 /proc/sys/kernel/randomize_va_space to 2.
1444
1445 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1446
81819f0f
CL
1447choice
1448 prompt "Choose SLAB allocator"
a0acd820 1449 default SLUB
81819f0f
CL
1450 help
1451 This option allows to select a slab allocator.
1452
1453config SLAB
1454 bool "SLAB"
1455 help
1456 The regular slab allocator that is established and known to work
34013886 1457 well in all environments. It organizes cache hot objects in
02f56210 1458 per cpu and per node queues.
81819f0f
CL
1459
1460config SLUB
81819f0f
CL
1461 bool "SLUB (Unqueued Allocator)"
1462 help
1463 SLUB is a slab allocator that minimizes cache line usage
1464 instead of managing queues of cached objects (SLAB approach).
1465 Per cpu caching is realized using slabs of objects instead
1466 of queues of objects. SLUB can use memory efficiently
02f56210
SA
1467 and has enhanced diagnostics. SLUB is the default choice for
1468 a slab allocator.
81819f0f
CL
1469
1470config SLOB
6a108a14 1471 depends on EXPERT
81819f0f
CL
1472 bool "SLOB (Simple Allocator)"
1473 help
37291458
MM
1474 SLOB replaces the stock allocator with a drastically simpler
1475 allocator. SLOB is generally more space efficient but
1476 does not perform as well on large systems.
81819f0f
CL
1477
1478endchoice
1479
ea637639
JZ
1480config MMAP_ALLOW_UNINITIALIZED
1481 bool "Allow mmapped anonymous memory to be uninitialized"
6a108a14 1482 depends on EXPERT && !MMU
ea637639
JZ
1483 default n
1484 help
1485 Normally, and according to the Linux spec, anonymous memory obtained
1486 from mmap() has it's contents cleared before it is passed to
1487 userspace. Enabling this config option allows you to request that
1488 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1489 providing a huge performance boost. If this option is not enabled,
1490 then the flag will be ignored.
1491
1492 This is taken advantage of by uClibc's malloc(), and also by
1493 ELF-FDPIC binfmt's brk and stack allocator.
1494
1495 Because of the obvious security issues, this option should only be
1496 enabled on embedded devices where you control what is run in
1497 userspace. Since that isn't generally a problem on no-MMU systems,
1498 it is normally safe to say Y here.
1499
1500 See Documentation/nommu-mmap.txt for more information.
1501
125e5645 1502config PROFILING
b309a294 1503 bool "Profiling support"
125e5645
MD
1504 help
1505 Say Y here to enable the extended profiling support mechanisms used
1506 by profilers such as OProfile.
1507
5f87f112
IM
1508#
1509# Place an empty function call at each tracepoint site. Can be
1510# dynamically changed for a probe function.
1511#
97e1c18e 1512config TRACEPOINTS
5f87f112 1513 bool
97e1c18e 1514
fb32e03f
MD
1515source "arch/Kconfig"
1516
1da177e4
LT
1517endmenu # General setup
1518
ee7e5516
DES
1519config HAVE_GENERIC_DMA_COHERENT
1520 bool
1521 default n
1522
158a9624
LT
1523config SLABINFO
1524 bool
1525 depends on PROC_FS
0f389ec6 1526 depends on SLAB || SLUB_DEBUG
158a9624
LT
1527 default y
1528
ae81f9e3
CE
1529config RT_MUTEXES
1530 boolean
ae81f9e3 1531
1da177e4
LT
1532config BASE_SMALL
1533 int
1534 default 0 if BASE_FULL
1535 default 1 if !BASE_FULL
1536
66da5733 1537menuconfig MODULES
1da177e4
LT
1538 bool "Enable loadable module support"
1539 help
1540 Kernel modules are small pieces of compiled code which can
1541 be inserted in the running kernel, rather than being
1542 permanently built into the kernel. You use the "modprobe"
1543 tool to add (and sometimes remove) them. If you say Y here,
1544 many parts of the kernel can be built as modules (by
1545 answering M instead of Y where indicated): this is most
1546 useful for infrequently used options which are not required
1547 for booting. For more information, see the man pages for
1548 modprobe, lsmod, modinfo, insmod and rmmod.
1549
1550 If you say Y here, you will need to run "make
1551 modules_install" to put the modules under /lib/modules/
1552 where modprobe can find them (you may need to be root to do
1553 this).
1554
1555 If unsure, say Y.
1556
0b0de144
RD
1557if MODULES
1558
826e4506
LT
1559config MODULE_FORCE_LOAD
1560 bool "Forced module loading"
826e4506
LT
1561 default n
1562 help
91e37a79
RR
1563 Allow loading of modules without version information (ie. modprobe
1564 --force). Forced module loading sets the 'F' (forced) taint flag and
1565 is usually a really bad idea.
826e4506 1566
1da177e4
LT
1567config MODULE_UNLOAD
1568 bool "Module unloading"
1da177e4
LT
1569 help
1570 Without this option you will not be able to unload any
1571 modules (note that some modules may not be unloadable
f7f5b675
DV
1572 anyway), which makes your kernel smaller, faster
1573 and simpler. If unsure, say Y.
1da177e4
LT
1574
1575config MODULE_FORCE_UNLOAD
1576 bool "Forced module unloading"
1577 depends on MODULE_UNLOAD && EXPERIMENTAL
1578 help
1579 This option allows you to force a module to unload, even if the
1580 kernel believes it is unsafe: the kernel will remove the module
1581 without waiting for anyone to stop using it (using the -f option to
1582 rmmod). This is mainly for kernel developers and desperate users.
1583 If unsure, say N.
1584
1da177e4 1585config MODVERSIONS
0d541643 1586 bool "Module versioning support"
1da177e4
LT
1587 help
1588 Usually, you have to use modules compiled with your kernel.
1589 Saying Y here makes it sometimes possible to use modules
1590 compiled for different kernels, by adding enough information
1591 to the modules to (hopefully) spot any changes which would
1592 make them incompatible with the kernel you are running. If
1593 unsure, say N.
1594
1595config MODULE_SRCVERSION_ALL
1596 bool "Source checksum for all modules"
1da177e4
LT
1597 help
1598 Modules which contain a MODULE_VERSION get an extra "srcversion"
1599 field inserted into their modinfo section, which contains a
1600 sum of the source files which made it. This helps maintainers
1601 see exactly which source was used to build a module (since
1602 others sometimes change the module source without updating
1603 the version). With this option, such a "srcversion" field
1604 will be created for all modules. If unsure, say N.
1605
0b0de144
RD
1606endif # MODULES
1607
98a79d6a
RR
1608config INIT_ALL_POSSIBLE
1609 bool
1610 help
5f054e31
RR
1611 Back when each arch used to define their own cpu_online_mask and
1612 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
98a79d6a
RR
1613 with all 1s, and others with all 0s. When they were centralised,
1614 it was better to provide this option than to break all the archs
692105b8 1615 and have several arch maintainers pursuing me down dark alleys.
98a79d6a 1616
1da177e4
LT
1617config STOP_MACHINE
1618 bool
1619 default y
1620 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1621 help
1622 Need stop_machine() primitive.
3a65dfe8 1623
3a65dfe8 1624source "block/Kconfig"
e98c3202
AK
1625
1626config PREEMPT_NOTIFIERS
1627 bool
e260be67 1628
16295bec
SK
1629config PADATA
1630 depends on SMP
1631 bool
1632
6beb0009 1633source "kernel/Kconfig.locks"