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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56 drivers that have been replaced by something else, and/or are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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499 Unless you want to hack and help the development of the full
500 tickless feature, you shouldn't enable this option. It adds
501 unnecessary overhead.
502
503 If unsure say N
504
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505config RCU_USER_QS_FORCE
506 bool "Force userspace extended QS by default"
507 depends on RCU_USER_QS
508 help
509 Set the hooks in user/kernel boundaries by default in order to
510 test this feature that treats userspace as an extended quiescent
511 state until we have a real user like a full adaptive nohz option.
512
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513 Unless you want to hack and help the development of the full
514 tickless feature, you shouldn't enable this option. It adds
515 unnecessary overhead.
516
517 If unsure say N
518
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519config RCU_FANOUT
520 int "Tree-based hierarchical RCU fanout value"
521 range 2 64 if 64BIT
522 range 2 32 if !64BIT
f41d911f 523 depends on TREE_RCU || TREE_PREEMPT_RCU
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524 default 64 if 64BIT
525 default 32 if !64BIT
526 help
527 This option controls the fanout of hierarchical implementations
528 of RCU, allowing RCU to work efficiently on machines with
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529 large numbers of CPUs. This value must be at least the fourth
530 root of NR_CPUS, which allows NR_CPUS to be insanely large.
531 The default value of RCU_FANOUT should be used for production
532 systems, but if you are stress-testing the RCU implementation
533 itself, small RCU_FANOUT values allow you to test large-system
534 code paths on small(er) systems.
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535
536 Select a specific number if testing RCU itself.
537 Take the default if unsure.
538
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539config RCU_FANOUT_LEAF
540 int "Tree-based hierarchical RCU leaf-level fanout value"
541 range 2 RCU_FANOUT if 64BIT
542 range 2 RCU_FANOUT if !64BIT
543 depends on TREE_RCU || TREE_PREEMPT_RCU
544 default 16
545 help
546 This option controls the leaf-level fanout of hierarchical
547 implementations of RCU, and allows trading off cache misses
548 against lock contention. Systems that synchronize their
549 scheduling-clock interrupts for energy-efficiency reasons will
550 want the default because the smaller leaf-level fanout keeps
551 lock contention levels acceptably low. Very large systems
552 (hundreds or thousands of CPUs) will instead want to set this
553 value to the maximum value possible in order to reduce the
554 number of cache misses incurred during RCU's grace-period
555 initialization. These systems tend to run CPU-bound, and thus
556 are not helped by synchronized interrupts, and thus tend to
557 skew them, which reduces lock contention enough that large
558 leaf-level fanouts work well.
559
560 Select a specific number if testing RCU itself.
561
562 Select the maximum permissible value for large systems.
563
564 Take the default if unsure.
565
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566config RCU_FANOUT_EXACT
567 bool "Disable tree-based hierarchical RCU auto-balancing"
f41d911f 568 depends on TREE_RCU || TREE_PREEMPT_RCU
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569 default n
570 help
571 This option forces use of the exact RCU_FANOUT value specified,
572 regardless of imbalances in the hierarchy. This is useful for
573 testing RCU itself, and might one day be useful on systems with
574 strong NUMA behavior.
575
576 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
577
578 Say N if unsure.
579
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580config RCU_FAST_NO_HZ
581 bool "Accelerate last non-dyntick-idle CPU's grace periods"
b807fbff 582 depends on NO_HZ && SMP
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583 default n
584 help
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585 This option causes RCU to attempt to accelerate grace periods in
586 order to allow CPUs to enter dynticks-idle state more quickly.
587 On the other hand, this option increases the overhead of the
588 dynticks-idle checking, thus degrading scheduling latency.
589
590 Say Y if energy efficiency is critically important, and you don't
591 care about real-time response.
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592
593 Say N if you are unsure.
594
c903ff83 595config TREE_RCU_TRACE
f41d911f 596 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
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597 select DEBUG_FS
598 help
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599 This option provides tracing for the TREE_RCU and
600 TREE_PREEMPT_RCU implementations, permitting Makefile to
601 trivially select kernel/rcutree_trace.c.
c903ff83 602
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603config RCU_BOOST
604 bool "Enable RCU priority boosting"
27f4d280 605 depends on RT_MUTEXES && PREEMPT_RCU
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606 default n
607 help
608 This option boosts the priority of preempted RCU readers that
609 block the current preemptible RCU grace period for too long.
610 This option also prevents heavy loads from blocking RCU
611 callback invocation for all flavors of RCU.
612
613 Say Y here if you are working with real-time apps or heavy loads
614 Say N here if you are unsure.
615
616config RCU_BOOST_PRIO
617 int "Real-time priority to boost RCU readers to"
618 range 1 99
619 depends on RCU_BOOST
620 default 1
621 help
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622 This option specifies the real-time priority to which long-term
623 preempted RCU readers are to be boosted. If you are working
624 with a real-time application that has one or more CPU-bound
625 threads running at a real-time priority level, you should set
626 RCU_BOOST_PRIO to a priority higher then the highest-priority
627 real-time CPU-bound thread. The default RCU_BOOST_PRIO value
628 of 1 is appropriate in the common case, which is real-time
629 applications that do not have any CPU-bound threads.
630
631 Some real-time applications might not have a single real-time
632 thread that saturates a given CPU, but instead might have
633 multiple real-time threads that, taken together, fully utilize
634 that CPU. In this case, you should set RCU_BOOST_PRIO to
635 a priority higher than the lowest-priority thread that is
636 conspiring to prevent the CPU from running any non-real-time
637 tasks. For example, if one thread at priority 10 and another
638 thread at priority 5 are between themselves fully consuming
639 the CPU time on a given CPU, then RCU_BOOST_PRIO should be
640 set to priority 6 or higher.
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641
642 Specify the real-time priority, or take the default if unsure.
643
644config RCU_BOOST_DELAY
645 int "Milliseconds to delay boosting after RCU grace-period start"
646 range 0 3000
647 depends on RCU_BOOST
648 default 500
649 help
650 This option specifies the time to wait after the beginning of
651 a given grace period before priority-boosting preempted RCU
652 readers blocking that grace period. Note that any RCU reader
653 blocking an expedited RCU grace period is boosted immediately.
654
655 Accept the default if unsure.
656
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MT
657endmenu # "RCU Subsystem"
658
1da177e4 659config IKCONFIG
f2443ab6 660 tristate "Kernel .config support"
1da177e4
LT
661 ---help---
662 This option enables the complete Linux kernel ".config" file
663 contents to be saved in the kernel. It provides documentation
664 of which kernel options are used in a running kernel or in an
665 on-disk kernel. This information can be extracted from the kernel
666 image file with the script scripts/extract-ikconfig and used as
667 input to rebuild the current kernel or to build another kernel.
668 It can also be extracted from a running kernel by reading
669 /proc/config.gz if enabled (below).
670
671config IKCONFIG_PROC
672 bool "Enable access to .config through /proc/config.gz"
673 depends on IKCONFIG && PROC_FS
674 ---help---
675 This option enables access to the kernel configuration file
676 through /proc/config.gz.
677
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AJS
678config LOG_BUF_SHIFT
679 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
680 range 12 21
f17a32e9 681 default 17
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AJS
682 help
683 Select kernel log buffer size as a power of 2.
f17a32e9
AB
684 Examples:
685 17 => 128 KB
686 16 => 64 KB
687 15 => 32 KB
688 14 => 16 KB
794543a2
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689 13 => 8 KB
690 12 => 4 KB
691
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IM
692#
693# Architectures with an unreliable sched_clock() should select this:
694#
695config HAVE_UNSTABLE_SCHED_CLOCK
696 bool
697
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698menuconfig CGROUPS
699 boolean "Control Group support"
0dea1168 700 depends on EVENTFD
5cdc38f9 701 help
23964d2d 702 This option adds support for grouping sets of processes together, for
5cdc38f9
KH
703 use with process control subsystems such as Cpusets, CFS, memory
704 controls or device isolation.
705 See
5cdc38f9 706 - Documentation/scheduler/sched-design-CFS.txt (CFS)
45ce80fb
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707 - Documentation/cgroups/ (features for grouping, isolation
708 and resource control)
5cdc38f9
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709
710 Say N if unsure.
711
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712if CGROUPS
713
5cdc38f9
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714config CGROUP_DEBUG
715 bool "Example debug cgroup subsystem"
5cdc38f9
KH
716 default n
717 help
718 This option enables a simple cgroup subsystem that
719 exports useful debugging information about the cgroups
23964d2d 720 framework.
5cdc38f9 721
23964d2d 722 Say N if unsure.
5cdc38f9 723
5cdc38f9 724config CGROUP_FREEZER
23964d2d 725 bool "Freezer cgroup subsystem"
23964d2d
LZ
726 help
727 Provides a way to freeze and unfreeze all tasks in a
5cdc38f9
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728 cgroup.
729
730config CGROUP_DEVICE
731 bool "Device controller for cgroups"
5cdc38f9
KH
732 help
733 Provides a cgroup implementing whitelists for devices which
734 a process in the cgroup can mknod or open.
735
736config CPUSETS
737 bool "Cpuset support"
5cdc38f9
KH
738 help
739 This option will let you create and manage CPUSETs which
740 allow dynamically partitioning a system into sets of CPUs and
741 Memory Nodes and assigning tasks to run only within those sets.
742 This is primarily useful on large SMP or NUMA systems.
743
744 Say N if unsure.
745
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746config PROC_PID_CPUSET
747 bool "Include legacy /proc/<pid>/cpuset file"
748 depends on CPUSETS
749 default y
750
d842de87
SV
751config CGROUP_CPUACCT
752 bool "Simple CPU accounting cgroup subsystem"
d842de87
SV
753 help
754 Provides a simple Resource Controller for monitoring the
23964d2d 755 total CPU consumed by the tasks in a cgroup.
d842de87 756
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757config RESOURCE_COUNTERS
758 bool "Resource counters"
759 help
760 This option enables controller independent resource accounting
23964d2d 761 infrastructure that works with cgroups.
e552b661 762
c255a458 763config MEMCG
00f0b825 764 bool "Memory Resource Controller for Control Groups"
79ae9c29 765 depends on RESOURCE_COUNTERS
cf475ad2 766 select MM_OWNER
00f0b825 767 help
84ad6d70 768 Provides a memory resource controller that manages both anonymous
21acb9ca 769 memory and page cache. (See Documentation/cgroups/memory.txt)
00f0b825
BS
770
771 Note that setting this option increases fixed memory overhead
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KH
772 associated with each page of memory in the system. By this,
773 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
774 usage tracking struct at boot. Total amount of this is printed out
775 at boot.
00f0b825
BS
776
777 Only enable when you're ok with these trade offs and really
84ad6d70
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778 sure you need the memory resource controller. Even when you enable
779 this, you can set "cgroup_disable=memory" at your boot option to
780 disable memory resource controller and you can avoid overheads.
c9d5409f 781 (and lose benefits of memory resource controller)
00f0b825 782
cf475ad2
BS
783 This config option also selects MM_OWNER config option, which
784 could in turn add some fork/exit overhead.
785
c255a458 786config MEMCG_SWAP
65e0e811 787 bool "Memory Resource Controller Swap Extension"
c255a458 788 depends on MEMCG && SWAP
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789 help
790 Add swap management feature to memory resource controller. When you
791 enable this, you can limit mem+swap usage per cgroup. In other words,
792 when you disable this, memory resource controller has no cares to
793 usage of swap...a process can exhaust all of the swap. This extension
794 is useful when you want to avoid exhaustion swap but this itself
795 adds more overheads and consumes memory for remembering information.
796 Especially if you use 32bit system or small memory system, please
797 be careful about enabling this. When memory resource controller
798 is disabled by boot option, this will be automatically disabled and
799 there will be no overhead from this. Even when you set this config=y,
00a66d29 800 if boot option "swapaccount=0" is set, swap will not be accounted.
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801 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
802 size is 4096bytes, 512k per 1Gbytes of swap.
c255a458 803config MEMCG_SWAP_ENABLED
a42c390c 804 bool "Memory Resource Controller Swap Extension enabled by default"
c255a458 805 depends on MEMCG_SWAP
a42c390c
MH
806 default y
807 help
808 Memory Resource Controller Swap Extension comes with its price in
809 a bigger memory consumption. General purpose distribution kernels
43d547f9 810 which want to enable the feature but keep it disabled by default
a42c390c
MH
811 and let the user enable it by swapaccount boot command line
812 parameter should have this option unselected.
813 For those who want to have the feature enabled by default should
814 select this option (if, for some reason, they need to disable it
00a66d29 815 then swapaccount=0 does the trick).
c255a458 816config MEMCG_KMEM
e5671dfa 817 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
c255a458 818 depends on MEMCG && EXPERIMENTAL
e5671dfa
GC
819 default n
820 help
821 The Kernel Memory extension for Memory Resource Controller can limit
822 the amount of memory used by kernel objects in the system. Those are
823 fundamentally different from the entities handled by the standard
824 Memory Controller, which are page-based, and can be swapped. Users of
825 the kmem extension can use it to guarantee that no group of processes
826 will ever exhaust kernel resources alone.
c077719b 827
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AK
828config CGROUP_HUGETLB
829 bool "HugeTLB Resource Controller for Control Groups"
830 depends on RESOURCE_COUNTERS && HUGETLB_PAGE && EXPERIMENTAL
831 default n
832 help
833 Provides a cgroup Resource Controller for HugeTLB pages.
834 When you enable this, you can put a per cgroup limit on HugeTLB usage.
835 The limit is enforced during page fault. Since HugeTLB doesn't
836 support page reclaim, enforcing the limit at page fault time implies
837 that, the application will get SIGBUS signal if it tries to access
838 HugeTLB pages beyond its limit. This requires the application to know
839 beforehand how much HugeTLB pages it would require for its use. The
840 control group is tracked in the third page lru pointer. This means
841 that we cannot use the controller with huge page less than 3 pages.
842
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SE
843config CGROUP_PERF
844 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
845 depends on PERF_EVENTS && CGROUPS
846 help
847 This option extends the per-cpu mode to restrict monitoring to
2d0f2520 848 threads which belong to the cgroup specified and run on the
e5d1367f
SE
849 designated cpu.
850
851 Say N if unsure.
852
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DG
853menuconfig CGROUP_SCHED
854 bool "Group CPU scheduler"
7c941438
DG
855 default n
856 help
857 This feature lets CPU scheduler recognize task groups and control CPU
858 bandwidth allocation to such task groups. It uses cgroups to group
859 tasks.
860
861if CGROUP_SCHED
862config FAIR_GROUP_SCHED
863 bool "Group scheduling for SCHED_OTHER"
864 depends on CGROUP_SCHED
865 default CGROUP_SCHED
866
ab84d31e
PT
867config CFS_BANDWIDTH
868 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
869 depends on EXPERIMENTAL
870 depends on FAIR_GROUP_SCHED
871 default n
872 help
873 This option allows users to define CPU bandwidth rates (limits) for
874 tasks running within the fair group scheduler. Groups with no limit
875 set are considered to be unconstrained and will run with no
876 restriction.
877 See tip/Documentation/scheduler/sched-bwc.txt for more information.
878
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DG
879config RT_GROUP_SCHED
880 bool "Group scheduling for SCHED_RR/FIFO"
881 depends on EXPERIMENTAL
882 depends on CGROUP_SCHED
883 default n
884 help
885 This feature lets you explicitly allocate real CPU bandwidth
32bd7eb5 886 to task groups. If enabled, it will also make it impossible to
7c941438
DG
887 schedule realtime tasks for non-root users until you allocate
888 realtime bandwidth for them.
889 See Documentation/scheduler/sched-rt-group.txt for more information.
890
891endif #CGROUP_SCHED
892
afc24d49 893config BLK_CGROUP
32e380ae 894 bool "Block IO controller"
79ae9c29 895 depends on BLOCK
afc24d49
VG
896 default n
897 ---help---
898 Generic block IO controller cgroup interface. This is the common
899 cgroup interface which should be used by various IO controlling
900 policies.
901
902 Currently, CFQ IO scheduler uses it to recognize task groups and
903 control disk bandwidth allocation (proportional time slice allocation)
e43473b7
VG
904 to such task groups. It is also used by bio throttling logic in
905 block layer to implement upper limit in IO rates on a device.
afc24d49
VG
906
907 This option only enables generic Block IO controller infrastructure.
e43473b7 908 One needs to also enable actual IO controlling logic/policy. For
79e2e759
MW
909 enabling proportional weight division of disk bandwidth in CFQ, set
910 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
c5e0591a 911 CONFIG_BLK_DEV_THROTTLING=y.
afc24d49
VG
912
913 See Documentation/cgroups/blkio-controller.txt for more information.
914
915config DEBUG_BLK_CGROUP
916 bool "Enable Block IO controller debugging"
917 depends on BLK_CGROUP
918 default n
919 ---help---
920 Enable some debugging help. Currently it exports additional stat
921 files in a cgroup which can be useful for debugging.
922
23964d2d 923endif # CGROUPS
c077719b 924
067bce1a
CG
925config CHECKPOINT_RESTORE
926 bool "Checkpoint/restore support" if EXPERT
927 default n
928 help
929 Enables additional kernel features in a sake of checkpoint/restore.
930 In particular it adds auxiliary prctl codes to setup process text,
931 data and heap segment sizes, and a few additional /proc filesystem
932 entries.
933
934 If unsure, say N here.
935
8dd2a82c 936menuconfig NAMESPACES
6a108a14
DR
937 bool "Namespaces support" if EXPERT
938 default !EXPERT
c5289a69
PE
939 help
940 Provides the way to make tasks work with different objects using
941 the same id. For example same IPC id may refer to different objects
942 or same user id or pid may refer to different tasks when used in
943 different namespaces.
944
8dd2a82c
DL
945if NAMESPACES
946
58bfdd6d
PE
947config UTS_NS
948 bool "UTS namespace"
17a6d441 949 default y
58bfdd6d
PE
950 help
951 In this namespace tasks see different info provided with the
952 uname() system call
953
ae5e1b22
PE
954config IPC_NS
955 bool "IPC namespace"
8dd2a82c 956 depends on (SYSVIPC || POSIX_MQUEUE)
17a6d441 957 default y
ae5e1b22
PE
958 help
959 In this namespace tasks work with IPC ids which correspond to
614b84cf 960 different IPC objects in different namespaces.
ae5e1b22 961
aee16ce7
PE
962config USER_NS
963 bool "User namespace (EXPERIMENTAL)"
8dd2a82c 964 depends on EXPERIMENTAL
e1c972b6 965 depends on UIDGID_CONVERTED
5673a94c 966 select UIDGID_STRICT_TYPE_CHECKS
e1c972b6 967
5673a94c 968 default n
aee16ce7
PE
969 help
970 This allows containers, i.e. vservers, to use user namespaces
971 to provide different user info for different servers.
972 If unsure, say N.
973
74bd59bb 974config PID_NS
9bd38c2c 975 bool "PID Namespaces"
17a6d441 976 default y
74bd59bb 977 help
12d2b8f9 978 Support process id namespaces. This allows having multiple
692105b8 979 processes with the same pid as long as they are in different
74bd59bb
PE
980 pid namespaces. This is a building block of containers.
981
d6eb633f
MH
982config NET_NS
983 bool "Network namespace"
8dd2a82c 984 depends on NET
17a6d441 985 default y
d6eb633f
MH
986 help
987 Allow user space to create what appear to be multiple instances
988 of the network stack.
989
8dd2a82c
DL
990endif # NAMESPACES
991
e1c972b6
EB
992config UIDGID_CONVERTED
993 # True if all of the selected software conmponents are known
994 # to have uid_t and gid_t converted to kuid_t and kgid_t
995 # where appropriate and are otherwise safe to use with
996 # the user namespace.
997 bool
998 default y
999
e1c972b6 1000 # Networking
e1c972b6 1001 depends on NET_9P = n
e1c972b6
EB
1002
1003 # Filesystems
e1c972b6 1004 depends on 9P_FS = n
e1c972b6
EB
1005 depends on AFS_FS = n
1006 depends on AUTOFS4_FS = n
e1c972b6
EB
1007 depends on CEPH_FS = n
1008 depends on CIFS = n
1009 depends on CODA_FS = n
e1c972b6
EB
1010 depends on FUSE_FS = n
1011 depends on GFS2_FS = n
e1c972b6
EB
1012 depends on NCP_FS = n
1013 depends on NFSD = n
1014 depends on NFS_FS = n
e1c972b6 1015 depends on OCFS2_FS = n
e1c972b6
EB
1016 depends on XFS_FS = n
1017
5673a94c
EB
1018config UIDGID_STRICT_TYPE_CHECKS
1019 bool "Require conversions between uid/gids and their internal representation"
e1c972b6 1020 depends on UIDGID_CONVERTED
5673a94c
EB
1021 default n
1022 help
1023 While the nececessary conversions are being added to all subsystems this option allows
1024 the code to continue to build for unconverted subsystems.
1025
1026 Say Y here if you want the strict type checking enabled
1027
5091faa4
MG
1028config SCHED_AUTOGROUP
1029 bool "Automatic process group scheduling"
1030 select EVENTFD
1031 select CGROUPS
1032 select CGROUP_SCHED
1033 select FAIR_GROUP_SCHED
1034 help
1035 This option optimizes the scheduler for common desktop workloads by
1036 automatically creating and populating task groups. This separation
1037 of workloads isolates aggressive CPU burners (like build jobs) from
1038 desktop applications. Task group autogeneration is currently based
1039 upon task session.
1040
7af37bec
DL
1041config MM_OWNER
1042 bool
1043
1044config SYSFS_DEPRECATED
5d6a4ea5 1045 bool "Enable deprecated sysfs features to support old userspace tools"
7af37bec
DL
1046 depends on SYSFS
1047 default n
1048 help
1049 This option adds code that switches the layout of the "block" class
1050 devices, to not show up in /sys/class/block/, but only in
1051 /sys/block/.
1052
1053 This switch is only active when the sysfs.deprecated=1 boot option is
1054 passed or the SYSFS_DEPRECATED_V2 option is set.
1055
1056 This option allows new kernels to run on old distributions and tools,
1057 which might get confused by /sys/class/block/. Since 2007/2008 all
1058 major distributions and tools handle this just fine.
1059
1060 Recent distributions and userspace tools after 2009/2010 depend on
1061 the existence of /sys/class/block/, and will not work with this
1062 option enabled.
1063
1064 Only if you are using a new kernel on an old distribution, you might
1065 need to say Y here.
1066
1067config SYSFS_DEPRECATED_V2
5d6a4ea5 1068 bool "Enable deprecated sysfs features by default"
7af37bec
DL
1069 default n
1070 depends on SYSFS
1071 depends on SYSFS_DEPRECATED
1072 help
1073 Enable deprecated sysfs by default.
1074
1075 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1076 option.
1077
1078 Only if you are using a new kernel on an old distribution, you might
1079 need to say Y here. Even then, odds are you would not need it
1080 enabled, you can always pass the boot option if absolutely necessary.
1081
1082config RELAY
1083 bool "Kernel->user space relay support (formerly relayfs)"
1084 help
1085 This option enables support for relay interface support in
1086 certain file systems (such as debugfs).
1087 It is designed to provide an efficient mechanism for tools and
1088 facilities to relay large amounts of data from kernel space to
1089 user space.
1090
1091 If unsure, say N.
1092
f991633d
DG
1093config BLK_DEV_INITRD
1094 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1095 depends on BROKEN || !FRV
1096 help
1097 The initial RAM filesystem is a ramfs which is loaded by the
1098 boot loader (loadlin or lilo) and that is mounted as root
1099 before the normal boot procedure. It is typically used to
1100 load modules needed to mount the "real" root file system,
1101 etc. See <file:Documentation/initrd.txt> for details.
1102
1103 If RAM disk support (BLK_DEV_RAM) is also included, this
1104 also enables initial RAM disk (initrd) support and adds
1105 15 Kbytes (more on some other architectures) to the kernel size.
1106
1107 If unsure say Y.
1108
c33df4ea
JPS
1109if BLK_DEV_INITRD
1110
dbec4866
SR
1111source "usr/Kconfig"
1112
c33df4ea
JPS
1113endif
1114
c45b4f1f 1115config CC_OPTIMIZE_FOR_SIZE
96fffeb4 1116 bool "Optimize for size"
c45b4f1f
LT
1117 help
1118 Enabling this option will pass "-Os" instead of "-O2" to gcc
1119 resulting in a smaller kernel.
1120
775a7229 1121 If unsure, say Y.
c45b4f1f 1122
0847062a
RD
1123config SYSCTL
1124 bool
1125
b943c460
RD
1126config ANON_INODES
1127 bool
1128
6a108a14
DR
1129menuconfig EXPERT
1130 bool "Configure standard kernel features (expert users)"
f505c553
JT
1131 # Unhide debug options, to make the on-by-default options visible
1132 select DEBUG_KERNEL
1da177e4
LT
1133 help
1134 This option allows certain base kernel options and settings
1135 to be disabled or tweaked. This is for specialized
1136 environments which can tolerate a "non-standard" kernel.
1137 Only use this if you really know what you are doing.
1138
af1839eb
CM
1139config HAVE_UID16
1140 bool
1141
ae81f9e3 1142config UID16
6a108a14 1143 bool "Enable 16-bit UID system calls" if EXPERT
af1839eb 1144 depends on HAVE_UID16
ae81f9e3
CE
1145 default y
1146 help
1147 This enables the legacy 16-bit UID syscall wrappers.
1148
b89a8171 1149config SYSCTL_SYSCALL
6a108a14 1150 bool "Sysctl syscall support" if EXPERT
26a7034b 1151 depends on PROC_SYSCTL
c736de60 1152 default n
b89a8171 1153 select SYSCTL
ae81f9e3 1154 ---help---
13bb7e37
EB
1155 sys_sysctl uses binary paths that have been found challenging
1156 to properly maintain and use. The interface in /proc/sys
1157 using paths with ascii names is now the primary path to this
1158 information.
b89a8171 1159
13bb7e37
EB
1160 Almost nothing using the binary sysctl interface so if you are
1161 trying to save some space it is probably safe to disable this,
1162 making your kernel marginally smaller.
b89a8171 1163
c736de60 1164 If unsure say N here.
ae81f9e3 1165
7ac57a89
CM
1166config SYSCTL_EXCEPTION_TRACE
1167 bool
1168 help
1169 Enable support for /proc/sys/debug/exception-trace.
1170
1da177e4 1171config KALLSYMS
6a108a14 1172 bool "Load all symbols for debugging/ksymoops" if EXPERT
1da177e4
LT
1173 default y
1174 help
1175 Say Y here to let the kernel print out symbolic crash information and
1176 symbolic stack backtraces. This increases the size of the kernel
1177 somewhat, as all symbols have to be loaded into the kernel image.
1178
1179config KALLSYMS_ALL
1180 bool "Include all symbols in kallsyms"
1181 depends on DEBUG_KERNEL && KALLSYMS
1182 help
71a83ec7
AB
1183 Normally kallsyms only contains the symbols of functions for nicer
1184 OOPS messages and backtraces (i.e., symbols from the text and inittext
1185 sections). This is sufficient for most cases. And only in very rare
1186 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1187 names of variables from the data sections, etc).
1188
1189 This option makes sure that all symbols are loaded into the kernel
1190 image (i.e., symbols from all sections) in cost of increased kernel
1191 size (depending on the kernel configuration, it may be 300KiB or
1192 something like this).
1193
1194 Say N unless you really need all symbols.
d59745ce 1195
712f47ce 1196config HOTPLUG
45f035ab 1197 def_bool y
712f47ce 1198
d59745ce
MM
1199config PRINTK
1200 default y
6a108a14 1201 bool "Enable support for printk" if EXPERT
d59745ce
MM
1202 help
1203 This option enables normal printk support. Removing it
1204 eliminates most of the message strings from the kernel image
1205 and makes the kernel more or less silent. As this makes it
1206 very difficult to diagnose system problems, saying N here is
1207 strongly discouraged.
1208
c8538a7a 1209config BUG
6a108a14 1210 bool "BUG() support" if EXPERT
c8538a7a
MM
1211 default y
1212 help
1213 Disabling this option eliminates support for BUG and WARN, reducing
1214 the size of your kernel image and potentially quietly ignoring
1215 numerous fatal conditions. You should only consider disabling this
1216 option for embedded systems with no facilities for reporting errors.
1217 Just say Y.
1218
708e9a79 1219config ELF_CORE
046d662f 1220 depends on COREDUMP
708e9a79 1221 default y
6a108a14 1222 bool "Enable ELF core dumps" if EXPERT
708e9a79
MM
1223 help
1224 Enable support for generating core dumps. Disabling saves about 4k.
1225
8761f1ab 1226
e5e1d3cb 1227config PCSPKR_PLATFORM
6a108a14 1228 bool "Enable PC-Speaker support" if EXPERT
8761f1ab 1229 depends on HAVE_PCSPKR_PLATFORM
15f304b6 1230 select I8253_LOCK
e5e1d3cb
SS
1231 default y
1232 help
1233 This option allows to disable the internal PC-Speaker
1234 support, saving some memory.
1235
8761f1ab
RB
1236config HAVE_PCSPKR_PLATFORM
1237 bool
1238
1da177e4
LT
1239config BASE_FULL
1240 default y
6a108a14 1241 bool "Enable full-sized data structures for core" if EXPERT
1da177e4
LT
1242 help
1243 Disabling this option reduces the size of miscellaneous core
1244 kernel data structures. This saves memory on small machines,
1245 but may reduce performance.
1246
1247config FUTEX
6a108a14 1248 bool "Enable futex support" if EXPERT
1da177e4 1249 default y
23f78d4a 1250 select RT_MUTEXES
1da177e4
LT
1251 help
1252 Disabling this option will cause the kernel to be built without
1253 support for "fast userspace mutexes". The resulting kernel may not
1254 run glibc-based applications correctly.
1255
1256config EPOLL
6a108a14 1257 bool "Enable eventpoll support" if EXPERT
1da177e4 1258 default y
448e3cee 1259 select ANON_INODES
1da177e4
LT
1260 help
1261 Disabling this option will cause the kernel to be built without
1262 support for epoll family of system calls.
1263
fba2afaa 1264config SIGNALFD
6a108a14 1265 bool "Enable signalfd() system call" if EXPERT
448e3cee 1266 select ANON_INODES
fba2afaa
DL
1267 default y
1268 help
1269 Enable the signalfd() system call that allows to receive signals
1270 on a file descriptor.
1271
1272 If unsure, say Y.
1273
b215e283 1274config TIMERFD
6a108a14 1275 bool "Enable timerfd() system call" if EXPERT
448e3cee 1276 select ANON_INODES
b215e283
DL
1277 default y
1278 help
1279 Enable the timerfd() system call that allows to receive timer
1280 events on a file descriptor.
1281
1282 If unsure, say Y.
1283
e1ad7468 1284config EVENTFD
6a108a14 1285 bool "Enable eventfd() system call" if EXPERT
448e3cee 1286 select ANON_INODES
e1ad7468
DL
1287 default y
1288 help
1289 Enable the eventfd() system call that allows to receive both
1290 kernel notification (ie. KAIO) or userspace notifications.
1291
1292 If unsure, say Y.
1293
1da177e4 1294config SHMEM
6a108a14 1295 bool "Use full shmem filesystem" if EXPERT
1da177e4
LT
1296 default y
1297 depends on MMU
1298 help
1299 The shmem is an internal filesystem used to manage shared memory.
1300 It is backed by swap and manages resource limits. It is also exported
1301 to userspace as tmpfs if TMPFS is enabled. Disabling this
1302 option replaces shmem and tmpfs with the much simpler ramfs code,
1303 which may be appropriate on small systems without swap.
1304
ebf3f09c 1305config AIO
6a108a14 1306 bool "Enable AIO support" if EXPERT
ebf3f09c
TP
1307 default y
1308 help
1309 This option enables POSIX asynchronous I/O which may by used
1310 by some high performance threaded applications. Disabling
1311 this option saves about 7k.
1312
6befe5f6
RD
1313config EMBEDDED
1314 bool "Embedded system"
1315 select EXPERT
1316 help
1317 This option should be enabled if compiling the kernel for
1318 an embedded system so certain expert options are available
1319 for configuration.
1320
cdd6c482 1321config HAVE_PERF_EVENTS
0793a61d 1322 bool
018df72d
MF
1323 help
1324 See tools/perf/design.txt for details.
0793a61d 1325
906010b2
PZ
1326config PERF_USE_VMALLOC
1327 bool
1328 help
1329 See tools/perf/design.txt for details
1330
57c0c15b 1331menu "Kernel Performance Events And Counters"
0793a61d 1332
cdd6c482 1333config PERF_EVENTS
57c0c15b 1334 bool "Kernel performance events and counters"
392d65a9 1335 default y if PROFILING
cdd6c482 1336 depends on HAVE_PERF_EVENTS
4c59e467 1337 select ANON_INODES
e360adbe 1338 select IRQ_WORK
0793a61d 1339 help
57c0c15b
IM
1340 Enable kernel support for various performance events provided
1341 by software and hardware.
0793a61d 1342
dd77038d 1343 Software events are supported either built-in or via the
57c0c15b 1344 use of generic tracepoints.
0793a61d 1345
57c0c15b
IM
1346 Most modern CPUs support performance events via performance
1347 counter registers. These registers count the number of certain
0793a61d
TG
1348 types of hw events: such as instructions executed, cachemisses
1349 suffered, or branches mis-predicted - without slowing down the
1350 kernel or applications. These registers can also trigger interrupts
1351 when a threshold number of events have passed - and can thus be
1352 used to profile the code that runs on that CPU.
1353
57c0c15b 1354 The Linux Performance Event subsystem provides an abstraction of
dd77038d 1355 these software and hardware event capabilities, available via a
57c0c15b 1356 system call and used by the "perf" utility in tools/perf/. It
0793a61d
TG
1357 provides per task and per CPU counters, and it provides event
1358 capabilities on top of those.
1359
1360 Say Y if unsure.
1361
906010b2
PZ
1362config DEBUG_PERF_USE_VMALLOC
1363 default n
1364 bool "Debug: use vmalloc to back perf mmap() buffers"
1365 depends on PERF_EVENTS && DEBUG_KERNEL
1366 select PERF_USE_VMALLOC
1367 help
1368 Use vmalloc memory to back perf mmap() buffers.
1369
1370 Mostly useful for debugging the vmalloc code on platforms
1371 that don't require it.
1372
1373 Say N if unsure.
1374
0793a61d
TG
1375endmenu
1376
f8891e5e
CL
1377config VM_EVENT_COUNTERS
1378 default y
6a108a14 1379 bool "Enable VM event counters for /proc/vmstat" if EXPERT
f8891e5e 1380 help
2aea4fb6
PJ
1381 VM event counters are needed for event counts to be shown.
1382 This option allows the disabling of the VM event counters
6a108a14 1383 on EXPERT systems. /proc/vmstat will only show page counts
2aea4fb6 1384 if VM event counters are disabled.
f8891e5e 1385
3d137310
TP
1386config PCI_QUIRKS
1387 default y
6a108a14 1388 bool "Enable PCI quirk workarounds" if EXPERT
61cfc7e4 1389 depends on PCI
3d137310
TP
1390 help
1391 This enables workarounds for various PCI chipset
1392 bugs/quirks. Disable this only if your target machine is
1393 unaffected by PCI quirks.
1394
41ecc55b
CL
1395config SLUB_DEBUG
1396 default y
6a108a14 1397 bool "Enable SLUB debugging support" if EXPERT
f6acb635 1398 depends on SLUB && SYSFS
41ecc55b
CL
1399 help
1400 SLUB has extensive debug support features. Disabling these can
1401 result in significant savings in code size. This also disables
1402 SLUB sysfs support. /sys/slab will not exist and there will be
1403 no support for cache validation etc.
1404
b943c460
RD
1405config COMPAT_BRK
1406 bool "Disable heap randomization"
1407 default y
1408 help
1409 Randomizing heap placement makes heap exploits harder, but it
1410 also breaks ancient binaries (including anything libc5 based).
1411 This option changes the bootup default to heap randomization
692105b8 1412 disabled, and can be overridden at runtime by setting
b943c460
RD
1413 /proc/sys/kernel/randomize_va_space to 2.
1414
1415 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1416
81819f0f
CL
1417choice
1418 prompt "Choose SLAB allocator"
a0acd820 1419 default SLUB
81819f0f
CL
1420 help
1421 This option allows to select a slab allocator.
1422
1423config SLAB
1424 bool "SLAB"
1425 help
1426 The regular slab allocator that is established and known to work
34013886 1427 well in all environments. It organizes cache hot objects in
02f56210 1428 per cpu and per node queues.
81819f0f
CL
1429
1430config SLUB
81819f0f
CL
1431 bool "SLUB (Unqueued Allocator)"
1432 help
1433 SLUB is a slab allocator that minimizes cache line usage
1434 instead of managing queues of cached objects (SLAB approach).
1435 Per cpu caching is realized using slabs of objects instead
1436 of queues of objects. SLUB can use memory efficiently
02f56210
SA
1437 and has enhanced diagnostics. SLUB is the default choice for
1438 a slab allocator.
81819f0f
CL
1439
1440config SLOB
6a108a14 1441 depends on EXPERT
81819f0f
CL
1442 bool "SLOB (Simple Allocator)"
1443 help
37291458
MM
1444 SLOB replaces the stock allocator with a drastically simpler
1445 allocator. SLOB is generally more space efficient but
1446 does not perform as well on large systems.
81819f0f
CL
1447
1448endchoice
1449
ea637639
JZ
1450config MMAP_ALLOW_UNINITIALIZED
1451 bool "Allow mmapped anonymous memory to be uninitialized"
6a108a14 1452 depends on EXPERT && !MMU
ea637639
JZ
1453 default n
1454 help
1455 Normally, and according to the Linux spec, anonymous memory obtained
1456 from mmap() has it's contents cleared before it is passed to
1457 userspace. Enabling this config option allows you to request that
1458 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1459 providing a huge performance boost. If this option is not enabled,
1460 then the flag will be ignored.
1461
1462 This is taken advantage of by uClibc's malloc(), and also by
1463 ELF-FDPIC binfmt's brk and stack allocator.
1464
1465 Because of the obvious security issues, this option should only be
1466 enabled on embedded devices where you control what is run in
1467 userspace. Since that isn't generally a problem on no-MMU systems,
1468 it is normally safe to say Y here.
1469
1470 See Documentation/nommu-mmap.txt for more information.
1471
125e5645 1472config PROFILING
b309a294 1473 bool "Profiling support"
125e5645
MD
1474 help
1475 Say Y here to enable the extended profiling support mechanisms used
1476 by profilers such as OProfile.
1477
5f87f112
IM
1478#
1479# Place an empty function call at each tracepoint site. Can be
1480# dynamically changed for a probe function.
1481#
97e1c18e 1482config TRACEPOINTS
5f87f112 1483 bool
97e1c18e 1484
fb32e03f
MD
1485source "arch/Kconfig"
1486
1da177e4
LT
1487endmenu # General setup
1488
ee7e5516
DES
1489config HAVE_GENERIC_DMA_COHERENT
1490 bool
1491 default n
1492
158a9624
LT
1493config SLABINFO
1494 bool
1495 depends on PROC_FS
0f389ec6 1496 depends on SLAB || SLUB_DEBUG
158a9624
LT
1497 default y
1498
ae81f9e3
CE
1499config RT_MUTEXES
1500 boolean
ae81f9e3 1501
1da177e4
LT
1502config BASE_SMALL
1503 int
1504 default 0 if BASE_FULL
1505 default 1 if !BASE_FULL
1506
66da5733 1507menuconfig MODULES
1da177e4
LT
1508 bool "Enable loadable module support"
1509 help
1510 Kernel modules are small pieces of compiled code which can
1511 be inserted in the running kernel, rather than being
1512 permanently built into the kernel. You use the "modprobe"
1513 tool to add (and sometimes remove) them. If you say Y here,
1514 many parts of the kernel can be built as modules (by
1515 answering M instead of Y where indicated): this is most
1516 useful for infrequently used options which are not required
1517 for booting. For more information, see the man pages for
1518 modprobe, lsmod, modinfo, insmod and rmmod.
1519
1520 If you say Y here, you will need to run "make
1521 modules_install" to put the modules under /lib/modules/
1522 where modprobe can find them (you may need to be root to do
1523 this).
1524
1525 If unsure, say Y.
1526
0b0de144
RD
1527if MODULES
1528
826e4506
LT
1529config MODULE_FORCE_LOAD
1530 bool "Forced module loading"
826e4506
LT
1531 default n
1532 help
91e37a79
RR
1533 Allow loading of modules without version information (ie. modprobe
1534 --force). Forced module loading sets the 'F' (forced) taint flag and
1535 is usually a really bad idea.
826e4506 1536
1da177e4
LT
1537config MODULE_UNLOAD
1538 bool "Module unloading"
1da177e4
LT
1539 help
1540 Without this option you will not be able to unload any
1541 modules (note that some modules may not be unloadable
f7f5b675
DV
1542 anyway), which makes your kernel smaller, faster
1543 and simpler. If unsure, say Y.
1da177e4
LT
1544
1545config MODULE_FORCE_UNLOAD
1546 bool "Forced module unloading"
1547 depends on MODULE_UNLOAD && EXPERIMENTAL
1548 help
1549 This option allows you to force a module to unload, even if the
1550 kernel believes it is unsafe: the kernel will remove the module
1551 without waiting for anyone to stop using it (using the -f option to
1552 rmmod). This is mainly for kernel developers and desperate users.
1553 If unsure, say N.
1554
1da177e4 1555config MODVERSIONS
0d541643 1556 bool "Module versioning support"
1da177e4
LT
1557 help
1558 Usually, you have to use modules compiled with your kernel.
1559 Saying Y here makes it sometimes possible to use modules
1560 compiled for different kernels, by adding enough information
1561 to the modules to (hopefully) spot any changes which would
1562 make them incompatible with the kernel you are running. If
1563 unsure, say N.
1564
1565config MODULE_SRCVERSION_ALL
1566 bool "Source checksum for all modules"
1da177e4
LT
1567 help
1568 Modules which contain a MODULE_VERSION get an extra "srcversion"
1569 field inserted into their modinfo section, which contains a
1570 sum of the source files which made it. This helps maintainers
1571 see exactly which source was used to build a module (since
1572 others sometimes change the module source without updating
1573 the version). With this option, such a "srcversion" field
1574 will be created for all modules. If unsure, say N.
1575
106a4ee2
RR
1576config MODULE_SIG
1577 bool "Module signature verification"
1578 depends on MODULES
48ba2462
DH
1579 select KEYS
1580 select CRYPTO
1581 select ASYMMETRIC_KEY_TYPE
1582 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1583 select PUBLIC_KEY_ALGO_RSA
1584 select ASN1
1585 select OID_REGISTRY
1586 select X509_CERTIFICATE_PARSER
106a4ee2
RR
1587 help
1588 Check modules for valid signatures upon load: the signature
1589 is simply appended to the module. For more information see
1590 Documentation/module-signing.txt.
1591
ea0b6dcf
DH
1592 !!!WARNING!!! If you enable this option, you MUST make sure that the
1593 module DOES NOT get stripped after being signed. This includes the
1594 debuginfo strip done by some packagers (such as rpmbuild) and
1595 inclusion into an initramfs that wants the module size reduced.
1596
106a4ee2
RR
1597config MODULE_SIG_FORCE
1598 bool "Require modules to be validly signed"
1599 depends on MODULE_SIG
1600 help
1601 Reject unsigned modules or signed modules for which we don't have a
1602 key. Without this, such modules will simply taint the kernel.
ea0b6dcf
DH
1603
1604choice
1605 prompt "Which hash algorithm should modules be signed with?"
1606 depends on MODULE_SIG
1607 help
1608 This determines which sort of hashing algorithm will be used during
1609 signature generation. This algorithm _must_ be built into the kernel
1610 directly so that signature verification can take place. It is not
1611 possible to load a signed module containing the algorithm to check
1612 the signature on that module.
1613
1614config MODULE_SIG_SHA1
1615 bool "Sign modules with SHA-1"
1616 select CRYPTO_SHA1
1617
1618config MODULE_SIG_SHA224
1619 bool "Sign modules with SHA-224"
1620 select CRYPTO_SHA256
1621
1622config MODULE_SIG_SHA256
1623 bool "Sign modules with SHA-256"
1624 select CRYPTO_SHA256
1625
1626config MODULE_SIG_SHA384
1627 bool "Sign modules with SHA-384"
1628 select CRYPTO_SHA512
1629
1630config MODULE_SIG_SHA512
1631 bool "Sign modules with SHA-512"
1632 select CRYPTO_SHA512
1633
1634endchoice
1635
0b0de144
RD
1636endif # MODULES
1637
98a79d6a
RR
1638config INIT_ALL_POSSIBLE
1639 bool
1640 help
5f054e31
RR
1641 Back when each arch used to define their own cpu_online_mask and
1642 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
98a79d6a
RR
1643 with all 1s, and others with all 0s. When they were centralised,
1644 it was better to provide this option than to break all the archs
692105b8 1645 and have several arch maintainers pursuing me down dark alleys.
98a79d6a 1646
1da177e4
LT
1647config STOP_MACHINE
1648 bool
1649 default y
1650 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1651 help
1652 Need stop_machine() primitive.
3a65dfe8 1653
3a65dfe8 1654source "block/Kconfig"
e98c3202
AK
1655
1656config PREEMPT_NOTIFIERS
1657 bool
e260be67 1658
16295bec
SK
1659config PADATA
1660 depends on SMP
1661 bool
1662
754b7b63
AK
1663# Can be selected by architectures with broken toolchains
1664# that get confused by correct const<->read_only section
1665# mappings
1666config BROKEN_RODATA
1667 bool
1668
4520c6a4
DH
1669config ASN1
1670 tristate
1671 help
1672 Build a simple ASN.1 grammar compiler that produces a bytecode output
1673 that can be interpreted by the ASN.1 stream decoder and used to
1674 inform it as to what tags are to be expected in a stream and what
1675 functions to call on what tags.
1676
6beb0009 1677source "kernel/Kconfig.locks"