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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56 drivers that have been replaced by something else, and/or are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
585 This option causes RCU to attempt to accelerate grace periods
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586 in order to allow CPUs to enter dynticks-idle state more
587 quickly. On the other hand, this option increases the overhead
588 of the dynticks-idle checking, particularly on systems with
589 large numbers of CPUs.
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590
591 Say Y if energy efficiency is critically important, particularly
592 if you have relatively few CPUs.
593
594 Say N if you are unsure.
595
c903ff83 596config TREE_RCU_TRACE
f41d911f 597 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
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598 select DEBUG_FS
599 help
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600 This option provides tracing for the TREE_RCU and
601 TREE_PREEMPT_RCU implementations, permitting Makefile to
602 trivially select kernel/rcutree_trace.c.
c903ff83 603
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604config RCU_BOOST
605 bool "Enable RCU priority boosting"
27f4d280 606 depends on RT_MUTEXES && PREEMPT_RCU
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607 default n
608 help
609 This option boosts the priority of preempted RCU readers that
610 block the current preemptible RCU grace period for too long.
611 This option also prevents heavy loads from blocking RCU
612 callback invocation for all flavors of RCU.
613
614 Say Y here if you are working with real-time apps or heavy loads
615 Say N here if you are unsure.
616
617config RCU_BOOST_PRIO
618 int "Real-time priority to boost RCU readers to"
619 range 1 99
620 depends on RCU_BOOST
621 default 1
622 help
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623 This option specifies the real-time priority to which long-term
624 preempted RCU readers are to be boosted. If you are working
625 with a real-time application that has one or more CPU-bound
626 threads running at a real-time priority level, you should set
627 RCU_BOOST_PRIO to a priority higher then the highest-priority
628 real-time CPU-bound thread. The default RCU_BOOST_PRIO value
629 of 1 is appropriate in the common case, which is real-time
630 applications that do not have any CPU-bound threads.
631
632 Some real-time applications might not have a single real-time
633 thread that saturates a given CPU, but instead might have
634 multiple real-time threads that, taken together, fully utilize
635 that CPU. In this case, you should set RCU_BOOST_PRIO to
636 a priority higher than the lowest-priority thread that is
637 conspiring to prevent the CPU from running any non-real-time
638 tasks. For example, if one thread at priority 10 and another
639 thread at priority 5 are between themselves fully consuming
640 the CPU time on a given CPU, then RCU_BOOST_PRIO should be
641 set to priority 6 or higher.
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642
643 Specify the real-time priority, or take the default if unsure.
644
645config RCU_BOOST_DELAY
646 int "Milliseconds to delay boosting after RCU grace-period start"
647 range 0 3000
648 depends on RCU_BOOST
649 default 500
650 help
651 This option specifies the time to wait after the beginning of
652 a given grace period before priority-boosting preempted RCU
653 readers blocking that grace period. Note that any RCU reader
654 blocking an expedited RCU grace period is boosted immediately.
655
656 Accept the default if unsure.
657
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MT
658endmenu # "RCU Subsystem"
659
1da177e4 660config IKCONFIG
f2443ab6 661 tristate "Kernel .config support"
1da177e4
LT
662 ---help---
663 This option enables the complete Linux kernel ".config" file
664 contents to be saved in the kernel. It provides documentation
665 of which kernel options are used in a running kernel or in an
666 on-disk kernel. This information can be extracted from the kernel
667 image file with the script scripts/extract-ikconfig and used as
668 input to rebuild the current kernel or to build another kernel.
669 It can also be extracted from a running kernel by reading
670 /proc/config.gz if enabled (below).
671
672config IKCONFIG_PROC
673 bool "Enable access to .config through /proc/config.gz"
674 depends on IKCONFIG && PROC_FS
675 ---help---
676 This option enables access to the kernel configuration file
677 through /proc/config.gz.
678
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AJS
679config LOG_BUF_SHIFT
680 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
681 range 12 21
f17a32e9 682 default 17
794543a2
AJS
683 help
684 Select kernel log buffer size as a power of 2.
f17a32e9
AB
685 Examples:
686 17 => 128 KB
687 16 => 64 KB
688 15 => 32 KB
689 14 => 16 KB
794543a2
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690 13 => 8 KB
691 12 => 4 KB
692
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IM
693#
694# Architectures with an unreliable sched_clock() should select this:
695#
696config HAVE_UNSTABLE_SCHED_CLOCK
697 bool
698
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699menuconfig CGROUPS
700 boolean "Control Group support"
0dea1168 701 depends on EVENTFD
5cdc38f9 702 help
23964d2d 703 This option adds support for grouping sets of processes together, for
5cdc38f9
KH
704 use with process control subsystems such as Cpusets, CFS, memory
705 controls or device isolation.
706 See
5cdc38f9 707 - Documentation/scheduler/sched-design-CFS.txt (CFS)
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708 - Documentation/cgroups/ (features for grouping, isolation
709 and resource control)
5cdc38f9
KH
710
711 Say N if unsure.
712
23964d2d
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713if CGROUPS
714
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715config CGROUP_DEBUG
716 bool "Example debug cgroup subsystem"
5cdc38f9
KH
717 default n
718 help
719 This option enables a simple cgroup subsystem that
720 exports useful debugging information about the cgroups
23964d2d 721 framework.
5cdc38f9 722
23964d2d 723 Say N if unsure.
5cdc38f9 724
5cdc38f9 725config CGROUP_FREEZER
23964d2d 726 bool "Freezer cgroup subsystem"
23964d2d
LZ
727 help
728 Provides a way to freeze and unfreeze all tasks in a
5cdc38f9
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729 cgroup.
730
731config CGROUP_DEVICE
732 bool "Device controller for cgroups"
5cdc38f9
KH
733 help
734 Provides a cgroup implementing whitelists for devices which
735 a process in the cgroup can mknod or open.
736
737config CPUSETS
738 bool "Cpuset support"
5cdc38f9
KH
739 help
740 This option will let you create and manage CPUSETs which
741 allow dynamically partitioning a system into sets of CPUs and
742 Memory Nodes and assigning tasks to run only within those sets.
743 This is primarily useful on large SMP or NUMA systems.
744
745 Say N if unsure.
746
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747config PROC_PID_CPUSET
748 bool "Include legacy /proc/<pid>/cpuset file"
749 depends on CPUSETS
750 default y
751
d842de87
SV
752config CGROUP_CPUACCT
753 bool "Simple CPU accounting cgroup subsystem"
d842de87
SV
754 help
755 Provides a simple Resource Controller for monitoring the
23964d2d 756 total CPU consumed by the tasks in a cgroup.
d842de87 757
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758config RESOURCE_COUNTERS
759 bool "Resource counters"
760 help
761 This option enables controller independent resource accounting
23964d2d 762 infrastructure that works with cgroups.
e552b661 763
c255a458 764config MEMCG
00f0b825 765 bool "Memory Resource Controller for Control Groups"
79ae9c29 766 depends on RESOURCE_COUNTERS
cf475ad2 767 select MM_OWNER
00f0b825 768 help
84ad6d70 769 Provides a memory resource controller that manages both anonymous
21acb9ca 770 memory and page cache. (See Documentation/cgroups/memory.txt)
00f0b825
BS
771
772 Note that setting this option increases fixed memory overhead
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773 associated with each page of memory in the system. By this,
774 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
775 usage tracking struct at boot. Total amount of this is printed out
776 at boot.
00f0b825
BS
777
778 Only enable when you're ok with these trade offs and really
84ad6d70
KH
779 sure you need the memory resource controller. Even when you enable
780 this, you can set "cgroup_disable=memory" at your boot option to
781 disable memory resource controller and you can avoid overheads.
c9d5409f 782 (and lose benefits of memory resource controller)
00f0b825 783
cf475ad2
BS
784 This config option also selects MM_OWNER config option, which
785 could in turn add some fork/exit overhead.
786
c255a458 787config MEMCG_SWAP
65e0e811 788 bool "Memory Resource Controller Swap Extension"
c255a458 789 depends on MEMCG && SWAP
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790 help
791 Add swap management feature to memory resource controller. When you
792 enable this, you can limit mem+swap usage per cgroup. In other words,
793 when you disable this, memory resource controller has no cares to
794 usage of swap...a process can exhaust all of the swap. This extension
795 is useful when you want to avoid exhaustion swap but this itself
796 adds more overheads and consumes memory for remembering information.
797 Especially if you use 32bit system or small memory system, please
798 be careful about enabling this. When memory resource controller
799 is disabled by boot option, this will be automatically disabled and
800 there will be no overhead from this. Even when you set this config=y,
00a66d29 801 if boot option "swapaccount=0" is set, swap will not be accounted.
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802 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
803 size is 4096bytes, 512k per 1Gbytes of swap.
c255a458 804config MEMCG_SWAP_ENABLED
a42c390c 805 bool "Memory Resource Controller Swap Extension enabled by default"
c255a458 806 depends on MEMCG_SWAP
a42c390c
MH
807 default y
808 help
809 Memory Resource Controller Swap Extension comes with its price in
810 a bigger memory consumption. General purpose distribution kernels
43d547f9 811 which want to enable the feature but keep it disabled by default
a42c390c
MH
812 and let the user enable it by swapaccount boot command line
813 parameter should have this option unselected.
814 For those who want to have the feature enabled by default should
815 select this option (if, for some reason, they need to disable it
00a66d29 816 then swapaccount=0 does the trick).
c255a458 817config MEMCG_KMEM
e5671dfa 818 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
c255a458 819 depends on MEMCG && EXPERIMENTAL
e5671dfa
GC
820 default n
821 help
822 The Kernel Memory extension for Memory Resource Controller can limit
823 the amount of memory used by kernel objects in the system. Those are
824 fundamentally different from the entities handled by the standard
825 Memory Controller, which are page-based, and can be swapped. Users of
826 the kmem extension can use it to guarantee that no group of processes
827 will ever exhaust kernel resources alone.
c077719b 828
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AK
829config CGROUP_HUGETLB
830 bool "HugeTLB Resource Controller for Control Groups"
831 depends on RESOURCE_COUNTERS && HUGETLB_PAGE && EXPERIMENTAL
832 default n
833 help
834 Provides a cgroup Resource Controller for HugeTLB pages.
835 When you enable this, you can put a per cgroup limit on HugeTLB usage.
836 The limit is enforced during page fault. Since HugeTLB doesn't
837 support page reclaim, enforcing the limit at page fault time implies
838 that, the application will get SIGBUS signal if it tries to access
839 HugeTLB pages beyond its limit. This requires the application to know
840 beforehand how much HugeTLB pages it would require for its use. The
841 control group is tracked in the third page lru pointer. This means
842 that we cannot use the controller with huge page less than 3 pages.
843
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SE
844config CGROUP_PERF
845 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
846 depends on PERF_EVENTS && CGROUPS
847 help
848 This option extends the per-cpu mode to restrict monitoring to
2d0f2520 849 threads which belong to the cgroup specified and run on the
e5d1367f
SE
850 designated cpu.
851
852 Say N if unsure.
853
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DG
854menuconfig CGROUP_SCHED
855 bool "Group CPU scheduler"
7c941438
DG
856 default n
857 help
858 This feature lets CPU scheduler recognize task groups and control CPU
859 bandwidth allocation to such task groups. It uses cgroups to group
860 tasks.
861
862if CGROUP_SCHED
863config FAIR_GROUP_SCHED
864 bool "Group scheduling for SCHED_OTHER"
865 depends on CGROUP_SCHED
866 default CGROUP_SCHED
867
ab84d31e
PT
868config CFS_BANDWIDTH
869 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
870 depends on EXPERIMENTAL
871 depends on FAIR_GROUP_SCHED
872 default n
873 help
874 This option allows users to define CPU bandwidth rates (limits) for
875 tasks running within the fair group scheduler. Groups with no limit
876 set are considered to be unconstrained and will run with no
877 restriction.
878 See tip/Documentation/scheduler/sched-bwc.txt for more information.
879
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DG
880config RT_GROUP_SCHED
881 bool "Group scheduling for SCHED_RR/FIFO"
882 depends on EXPERIMENTAL
883 depends on CGROUP_SCHED
884 default n
885 help
886 This feature lets you explicitly allocate real CPU bandwidth
32bd7eb5 887 to task groups. If enabled, it will also make it impossible to
7c941438
DG
888 schedule realtime tasks for non-root users until you allocate
889 realtime bandwidth for them.
890 See Documentation/scheduler/sched-rt-group.txt for more information.
891
892endif #CGROUP_SCHED
893
afc24d49 894config BLK_CGROUP
32e380ae 895 bool "Block IO controller"
79ae9c29 896 depends on BLOCK
afc24d49
VG
897 default n
898 ---help---
899 Generic block IO controller cgroup interface. This is the common
900 cgroup interface which should be used by various IO controlling
901 policies.
902
903 Currently, CFQ IO scheduler uses it to recognize task groups and
904 control disk bandwidth allocation (proportional time slice allocation)
e43473b7
VG
905 to such task groups. It is also used by bio throttling logic in
906 block layer to implement upper limit in IO rates on a device.
afc24d49
VG
907
908 This option only enables generic Block IO controller infrastructure.
e43473b7 909 One needs to also enable actual IO controlling logic/policy. For
79e2e759
MW
910 enabling proportional weight division of disk bandwidth in CFQ, set
911 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
c5e0591a 912 CONFIG_BLK_DEV_THROTTLING=y.
afc24d49
VG
913
914 See Documentation/cgroups/blkio-controller.txt for more information.
915
916config DEBUG_BLK_CGROUP
917 bool "Enable Block IO controller debugging"
918 depends on BLK_CGROUP
919 default n
920 ---help---
921 Enable some debugging help. Currently it exports additional stat
922 files in a cgroup which can be useful for debugging.
923
23964d2d 924endif # CGROUPS
c077719b 925
067bce1a
CG
926config CHECKPOINT_RESTORE
927 bool "Checkpoint/restore support" if EXPERT
928 default n
929 help
930 Enables additional kernel features in a sake of checkpoint/restore.
931 In particular it adds auxiliary prctl codes to setup process text,
932 data and heap segment sizes, and a few additional /proc filesystem
933 entries.
934
935 If unsure, say N here.
936
8dd2a82c 937menuconfig NAMESPACES
6a108a14
DR
938 bool "Namespaces support" if EXPERT
939 default !EXPERT
c5289a69
PE
940 help
941 Provides the way to make tasks work with different objects using
942 the same id. For example same IPC id may refer to different objects
943 or same user id or pid may refer to different tasks when used in
944 different namespaces.
945
8dd2a82c
DL
946if NAMESPACES
947
58bfdd6d
PE
948config UTS_NS
949 bool "UTS namespace"
17a6d441 950 default y
58bfdd6d
PE
951 help
952 In this namespace tasks see different info provided with the
953 uname() system call
954
ae5e1b22
PE
955config IPC_NS
956 bool "IPC namespace"
8dd2a82c 957 depends on (SYSVIPC || POSIX_MQUEUE)
17a6d441 958 default y
ae5e1b22
PE
959 help
960 In this namespace tasks work with IPC ids which correspond to
614b84cf 961 different IPC objects in different namespaces.
ae5e1b22 962
aee16ce7
PE
963config USER_NS
964 bool "User namespace (EXPERIMENTAL)"
8dd2a82c 965 depends on EXPERIMENTAL
e1c972b6 966 depends on UIDGID_CONVERTED
5673a94c 967 select UIDGID_STRICT_TYPE_CHECKS
e1c972b6 968
5673a94c 969 default n
aee16ce7
PE
970 help
971 This allows containers, i.e. vservers, to use user namespaces
972 to provide different user info for different servers.
973 If unsure, say N.
974
74bd59bb 975config PID_NS
9bd38c2c 976 bool "PID Namespaces"
17a6d441 977 default y
74bd59bb 978 help
12d2b8f9 979 Support process id namespaces. This allows having multiple
692105b8 980 processes with the same pid as long as they are in different
74bd59bb
PE
981 pid namespaces. This is a building block of containers.
982
d6eb633f
MH
983config NET_NS
984 bool "Network namespace"
8dd2a82c 985 depends on NET
17a6d441 986 default y
d6eb633f
MH
987 help
988 Allow user space to create what appear to be multiple instances
989 of the network stack.
990
8dd2a82c
DL
991endif # NAMESPACES
992
e1c972b6
EB
993config UIDGID_CONVERTED
994 # True if all of the selected software conmponents are known
995 # to have uid_t and gid_t converted to kuid_t and kgid_t
996 # where appropriate and are otherwise safe to use with
997 # the user namespace.
998 bool
999 default y
1000
e1c972b6 1001 # Networking
e1c972b6 1002 depends on NET_9P = n
e1c972b6
EB
1003
1004 # Filesystems
e1c972b6 1005 depends on 9P_FS = n
e1c972b6
EB
1006 depends on AFS_FS = n
1007 depends on AUTOFS4_FS = n
e1c972b6
EB
1008 depends on CEPH_FS = n
1009 depends on CIFS = n
1010 depends on CODA_FS = n
e1c972b6
EB
1011 depends on FUSE_FS = n
1012 depends on GFS2_FS = n
e1c972b6
EB
1013 depends on NCP_FS = n
1014 depends on NFSD = n
1015 depends on NFS_FS = n
e1c972b6 1016 depends on OCFS2_FS = n
e1c972b6
EB
1017 depends on XFS_FS = n
1018
5673a94c
EB
1019config UIDGID_STRICT_TYPE_CHECKS
1020 bool "Require conversions between uid/gids and their internal representation"
e1c972b6 1021 depends on UIDGID_CONVERTED
5673a94c
EB
1022 default n
1023 help
1024 While the nececessary conversions are being added to all subsystems this option allows
1025 the code to continue to build for unconverted subsystems.
1026
1027 Say Y here if you want the strict type checking enabled
1028
5091faa4
MG
1029config SCHED_AUTOGROUP
1030 bool "Automatic process group scheduling"
1031 select EVENTFD
1032 select CGROUPS
1033 select CGROUP_SCHED
1034 select FAIR_GROUP_SCHED
1035 help
1036 This option optimizes the scheduler for common desktop workloads by
1037 automatically creating and populating task groups. This separation
1038 of workloads isolates aggressive CPU burners (like build jobs) from
1039 desktop applications. Task group autogeneration is currently based
1040 upon task session.
1041
7af37bec
DL
1042config MM_OWNER
1043 bool
1044
1045config SYSFS_DEPRECATED
5d6a4ea5 1046 bool "Enable deprecated sysfs features to support old userspace tools"
7af37bec
DL
1047 depends on SYSFS
1048 default n
1049 help
1050 This option adds code that switches the layout of the "block" class
1051 devices, to not show up in /sys/class/block/, but only in
1052 /sys/block/.
1053
1054 This switch is only active when the sysfs.deprecated=1 boot option is
1055 passed or the SYSFS_DEPRECATED_V2 option is set.
1056
1057 This option allows new kernels to run on old distributions and tools,
1058 which might get confused by /sys/class/block/. Since 2007/2008 all
1059 major distributions and tools handle this just fine.
1060
1061 Recent distributions and userspace tools after 2009/2010 depend on
1062 the existence of /sys/class/block/, and will not work with this
1063 option enabled.
1064
1065 Only if you are using a new kernel on an old distribution, you might
1066 need to say Y here.
1067
1068config SYSFS_DEPRECATED_V2
5d6a4ea5 1069 bool "Enable deprecated sysfs features by default"
7af37bec
DL
1070 default n
1071 depends on SYSFS
1072 depends on SYSFS_DEPRECATED
1073 help
1074 Enable deprecated sysfs by default.
1075
1076 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1077 option.
1078
1079 Only if you are using a new kernel on an old distribution, you might
1080 need to say Y here. Even then, odds are you would not need it
1081 enabled, you can always pass the boot option if absolutely necessary.
1082
1083config RELAY
1084 bool "Kernel->user space relay support (formerly relayfs)"
1085 help
1086 This option enables support for relay interface support in
1087 certain file systems (such as debugfs).
1088 It is designed to provide an efficient mechanism for tools and
1089 facilities to relay large amounts of data from kernel space to
1090 user space.
1091
1092 If unsure, say N.
1093
f991633d
DG
1094config BLK_DEV_INITRD
1095 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1096 depends on BROKEN || !FRV
1097 help
1098 The initial RAM filesystem is a ramfs which is loaded by the
1099 boot loader (loadlin or lilo) and that is mounted as root
1100 before the normal boot procedure. It is typically used to
1101 load modules needed to mount the "real" root file system,
1102 etc. See <file:Documentation/initrd.txt> for details.
1103
1104 If RAM disk support (BLK_DEV_RAM) is also included, this
1105 also enables initial RAM disk (initrd) support and adds
1106 15 Kbytes (more on some other architectures) to the kernel size.
1107
1108 If unsure say Y.
1109
c33df4ea
JPS
1110if BLK_DEV_INITRD
1111
dbec4866
SR
1112source "usr/Kconfig"
1113
c33df4ea
JPS
1114endif
1115
c45b4f1f 1116config CC_OPTIMIZE_FOR_SIZE
96fffeb4 1117 bool "Optimize for size"
c45b4f1f
LT
1118 help
1119 Enabling this option will pass "-Os" instead of "-O2" to gcc
1120 resulting in a smaller kernel.
1121
775a7229 1122 If unsure, say Y.
c45b4f1f 1123
0847062a
RD
1124config SYSCTL
1125 bool
1126
b943c460
RD
1127config ANON_INODES
1128 bool
1129
6a108a14
DR
1130menuconfig EXPERT
1131 bool "Configure standard kernel features (expert users)"
f505c553
JT
1132 # Unhide debug options, to make the on-by-default options visible
1133 select DEBUG_KERNEL
1da177e4
LT
1134 help
1135 This option allows certain base kernel options and settings
1136 to be disabled or tweaked. This is for specialized
1137 environments which can tolerate a "non-standard" kernel.
1138 Only use this if you really know what you are doing.
1139
af1839eb
CM
1140config HAVE_UID16
1141 bool
1142
ae81f9e3 1143config UID16
6a108a14 1144 bool "Enable 16-bit UID system calls" if EXPERT
af1839eb 1145 depends on HAVE_UID16
ae81f9e3
CE
1146 default y
1147 help
1148 This enables the legacy 16-bit UID syscall wrappers.
1149
b89a8171 1150config SYSCTL_SYSCALL
6a108a14 1151 bool "Sysctl syscall support" if EXPERT
26a7034b 1152 depends on PROC_SYSCTL
c736de60 1153 default n
b89a8171 1154 select SYSCTL
ae81f9e3 1155 ---help---
13bb7e37
EB
1156 sys_sysctl uses binary paths that have been found challenging
1157 to properly maintain and use. The interface in /proc/sys
1158 using paths with ascii names is now the primary path to this
1159 information.
b89a8171 1160
13bb7e37
EB
1161 Almost nothing using the binary sysctl interface so if you are
1162 trying to save some space it is probably safe to disable this,
1163 making your kernel marginally smaller.
b89a8171 1164
c736de60 1165 If unsure say N here.
ae81f9e3 1166
7ac57a89
CM
1167config SYSCTL_EXCEPTION_TRACE
1168 bool
1169 help
1170 Enable support for /proc/sys/debug/exception-trace.
1171
1da177e4 1172config KALLSYMS
6a108a14 1173 bool "Load all symbols for debugging/ksymoops" if EXPERT
1da177e4
LT
1174 default y
1175 help
1176 Say Y here to let the kernel print out symbolic crash information and
1177 symbolic stack backtraces. This increases the size of the kernel
1178 somewhat, as all symbols have to be loaded into the kernel image.
1179
1180config KALLSYMS_ALL
1181 bool "Include all symbols in kallsyms"
1182 depends on DEBUG_KERNEL && KALLSYMS
1183 help
71a83ec7
AB
1184 Normally kallsyms only contains the symbols of functions for nicer
1185 OOPS messages and backtraces (i.e., symbols from the text and inittext
1186 sections). This is sufficient for most cases. And only in very rare
1187 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1188 names of variables from the data sections, etc).
1189
1190 This option makes sure that all symbols are loaded into the kernel
1191 image (i.e., symbols from all sections) in cost of increased kernel
1192 size (depending on the kernel configuration, it may be 300KiB or
1193 something like this).
1194
1195 Say N unless you really need all symbols.
d59745ce 1196
712f47ce 1197config HOTPLUG
45f035ab 1198 def_bool y
712f47ce 1199
d59745ce
MM
1200config PRINTK
1201 default y
6a108a14 1202 bool "Enable support for printk" if EXPERT
d59745ce
MM
1203 help
1204 This option enables normal printk support. Removing it
1205 eliminates most of the message strings from the kernel image
1206 and makes the kernel more or less silent. As this makes it
1207 very difficult to diagnose system problems, saying N here is
1208 strongly discouraged.
1209
c8538a7a 1210config BUG
6a108a14 1211 bool "BUG() support" if EXPERT
c8538a7a
MM
1212 default y
1213 help
1214 Disabling this option eliminates support for BUG and WARN, reducing
1215 the size of your kernel image and potentially quietly ignoring
1216 numerous fatal conditions. You should only consider disabling this
1217 option for embedded systems with no facilities for reporting errors.
1218 Just say Y.
1219
708e9a79 1220config ELF_CORE
046d662f 1221 depends on COREDUMP
708e9a79 1222 default y
6a108a14 1223 bool "Enable ELF core dumps" if EXPERT
708e9a79
MM
1224 help
1225 Enable support for generating core dumps. Disabling saves about 4k.
1226
8761f1ab 1227
e5e1d3cb 1228config PCSPKR_PLATFORM
6a108a14 1229 bool "Enable PC-Speaker support" if EXPERT
8761f1ab 1230 depends on HAVE_PCSPKR_PLATFORM
15f304b6 1231 select I8253_LOCK
e5e1d3cb
SS
1232 default y
1233 help
1234 This option allows to disable the internal PC-Speaker
1235 support, saving some memory.
1236
8761f1ab
RB
1237config HAVE_PCSPKR_PLATFORM
1238 bool
1239
1da177e4
LT
1240config BASE_FULL
1241 default y
6a108a14 1242 bool "Enable full-sized data structures for core" if EXPERT
1da177e4
LT
1243 help
1244 Disabling this option reduces the size of miscellaneous core
1245 kernel data structures. This saves memory on small machines,
1246 but may reduce performance.
1247
1248config FUTEX
6a108a14 1249 bool "Enable futex support" if EXPERT
1da177e4 1250 default y
23f78d4a 1251 select RT_MUTEXES
1da177e4
LT
1252 help
1253 Disabling this option will cause the kernel to be built without
1254 support for "fast userspace mutexes". The resulting kernel may not
1255 run glibc-based applications correctly.
1256
1257config EPOLL
6a108a14 1258 bool "Enable eventpoll support" if EXPERT
1da177e4 1259 default y
448e3cee 1260 select ANON_INODES
1da177e4
LT
1261 help
1262 Disabling this option will cause the kernel to be built without
1263 support for epoll family of system calls.
1264
fba2afaa 1265config SIGNALFD
6a108a14 1266 bool "Enable signalfd() system call" if EXPERT
448e3cee 1267 select ANON_INODES
fba2afaa
DL
1268 default y
1269 help
1270 Enable the signalfd() system call that allows to receive signals
1271 on a file descriptor.
1272
1273 If unsure, say Y.
1274
b215e283 1275config TIMERFD
6a108a14 1276 bool "Enable timerfd() system call" if EXPERT
448e3cee 1277 select ANON_INODES
b215e283
DL
1278 default y
1279 help
1280 Enable the timerfd() system call that allows to receive timer
1281 events on a file descriptor.
1282
1283 If unsure, say Y.
1284
e1ad7468 1285config EVENTFD
6a108a14 1286 bool "Enable eventfd() system call" if EXPERT
448e3cee 1287 select ANON_INODES
e1ad7468
DL
1288 default y
1289 help
1290 Enable the eventfd() system call that allows to receive both
1291 kernel notification (ie. KAIO) or userspace notifications.
1292
1293 If unsure, say Y.
1294
1da177e4 1295config SHMEM
6a108a14 1296 bool "Use full shmem filesystem" if EXPERT
1da177e4
LT
1297 default y
1298 depends on MMU
1299 help
1300 The shmem is an internal filesystem used to manage shared memory.
1301 It is backed by swap and manages resource limits. It is also exported
1302 to userspace as tmpfs if TMPFS is enabled. Disabling this
1303 option replaces shmem and tmpfs with the much simpler ramfs code,
1304 which may be appropriate on small systems without swap.
1305
ebf3f09c 1306config AIO
6a108a14 1307 bool "Enable AIO support" if EXPERT
ebf3f09c
TP
1308 default y
1309 help
1310 This option enables POSIX asynchronous I/O which may by used
1311 by some high performance threaded applications. Disabling
1312 this option saves about 7k.
1313
6befe5f6
RD
1314config EMBEDDED
1315 bool "Embedded system"
1316 select EXPERT
1317 help
1318 This option should be enabled if compiling the kernel for
1319 an embedded system so certain expert options are available
1320 for configuration.
1321
cdd6c482 1322config HAVE_PERF_EVENTS
0793a61d 1323 bool
018df72d
MF
1324 help
1325 See tools/perf/design.txt for details.
0793a61d 1326
906010b2
PZ
1327config PERF_USE_VMALLOC
1328 bool
1329 help
1330 See tools/perf/design.txt for details
1331
57c0c15b 1332menu "Kernel Performance Events And Counters"
0793a61d 1333
cdd6c482 1334config PERF_EVENTS
57c0c15b 1335 bool "Kernel performance events and counters"
392d65a9 1336 default y if PROFILING
cdd6c482 1337 depends on HAVE_PERF_EVENTS
4c59e467 1338 select ANON_INODES
e360adbe 1339 select IRQ_WORK
0793a61d 1340 help
57c0c15b
IM
1341 Enable kernel support for various performance events provided
1342 by software and hardware.
0793a61d 1343
dd77038d 1344 Software events are supported either built-in or via the
57c0c15b 1345 use of generic tracepoints.
0793a61d 1346
57c0c15b
IM
1347 Most modern CPUs support performance events via performance
1348 counter registers. These registers count the number of certain
0793a61d
TG
1349 types of hw events: such as instructions executed, cachemisses
1350 suffered, or branches mis-predicted - without slowing down the
1351 kernel or applications. These registers can also trigger interrupts
1352 when a threshold number of events have passed - and can thus be
1353 used to profile the code that runs on that CPU.
1354
57c0c15b 1355 The Linux Performance Event subsystem provides an abstraction of
dd77038d 1356 these software and hardware event capabilities, available via a
57c0c15b 1357 system call and used by the "perf" utility in tools/perf/. It
0793a61d
TG
1358 provides per task and per CPU counters, and it provides event
1359 capabilities on top of those.
1360
1361 Say Y if unsure.
1362
906010b2
PZ
1363config DEBUG_PERF_USE_VMALLOC
1364 default n
1365 bool "Debug: use vmalloc to back perf mmap() buffers"
1366 depends on PERF_EVENTS && DEBUG_KERNEL
1367 select PERF_USE_VMALLOC
1368 help
1369 Use vmalloc memory to back perf mmap() buffers.
1370
1371 Mostly useful for debugging the vmalloc code on platforms
1372 that don't require it.
1373
1374 Say N if unsure.
1375
0793a61d
TG
1376endmenu
1377
f8891e5e
CL
1378config VM_EVENT_COUNTERS
1379 default y
6a108a14 1380 bool "Enable VM event counters for /proc/vmstat" if EXPERT
f8891e5e 1381 help
2aea4fb6
PJ
1382 VM event counters are needed for event counts to be shown.
1383 This option allows the disabling of the VM event counters
6a108a14 1384 on EXPERT systems. /proc/vmstat will only show page counts
2aea4fb6 1385 if VM event counters are disabled.
f8891e5e 1386
3d137310
TP
1387config PCI_QUIRKS
1388 default y
6a108a14 1389 bool "Enable PCI quirk workarounds" if EXPERT
61cfc7e4 1390 depends on PCI
3d137310
TP
1391 help
1392 This enables workarounds for various PCI chipset
1393 bugs/quirks. Disable this only if your target machine is
1394 unaffected by PCI quirks.
1395
41ecc55b
CL
1396config SLUB_DEBUG
1397 default y
6a108a14 1398 bool "Enable SLUB debugging support" if EXPERT
f6acb635 1399 depends on SLUB && SYSFS
41ecc55b
CL
1400 help
1401 SLUB has extensive debug support features. Disabling these can
1402 result in significant savings in code size. This also disables
1403 SLUB sysfs support. /sys/slab will not exist and there will be
1404 no support for cache validation etc.
1405
b943c460
RD
1406config COMPAT_BRK
1407 bool "Disable heap randomization"
1408 default y
1409 help
1410 Randomizing heap placement makes heap exploits harder, but it
1411 also breaks ancient binaries (including anything libc5 based).
1412 This option changes the bootup default to heap randomization
692105b8 1413 disabled, and can be overridden at runtime by setting
b943c460
RD
1414 /proc/sys/kernel/randomize_va_space to 2.
1415
1416 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1417
81819f0f
CL
1418choice
1419 prompt "Choose SLAB allocator"
a0acd820 1420 default SLUB
81819f0f
CL
1421 help
1422 This option allows to select a slab allocator.
1423
1424config SLAB
1425 bool "SLAB"
1426 help
1427 The regular slab allocator that is established and known to work
34013886 1428 well in all environments. It organizes cache hot objects in
02f56210 1429 per cpu and per node queues.
81819f0f
CL
1430
1431config SLUB
81819f0f
CL
1432 bool "SLUB (Unqueued Allocator)"
1433 help
1434 SLUB is a slab allocator that minimizes cache line usage
1435 instead of managing queues of cached objects (SLAB approach).
1436 Per cpu caching is realized using slabs of objects instead
1437 of queues of objects. SLUB can use memory efficiently
02f56210
SA
1438 and has enhanced diagnostics. SLUB is the default choice for
1439 a slab allocator.
81819f0f
CL
1440
1441config SLOB
6a108a14 1442 depends on EXPERT
81819f0f
CL
1443 bool "SLOB (Simple Allocator)"
1444 help
37291458
MM
1445 SLOB replaces the stock allocator with a drastically simpler
1446 allocator. SLOB is generally more space efficient but
1447 does not perform as well on large systems.
81819f0f
CL
1448
1449endchoice
1450
ea637639
JZ
1451config MMAP_ALLOW_UNINITIALIZED
1452 bool "Allow mmapped anonymous memory to be uninitialized"
6a108a14 1453 depends on EXPERT && !MMU
ea637639
JZ
1454 default n
1455 help
1456 Normally, and according to the Linux spec, anonymous memory obtained
1457 from mmap() has it's contents cleared before it is passed to
1458 userspace. Enabling this config option allows you to request that
1459 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1460 providing a huge performance boost. If this option is not enabled,
1461 then the flag will be ignored.
1462
1463 This is taken advantage of by uClibc's malloc(), and also by
1464 ELF-FDPIC binfmt's brk and stack allocator.
1465
1466 Because of the obvious security issues, this option should only be
1467 enabled on embedded devices where you control what is run in
1468 userspace. Since that isn't generally a problem on no-MMU systems,
1469 it is normally safe to say Y here.
1470
1471 See Documentation/nommu-mmap.txt for more information.
1472
125e5645 1473config PROFILING
b309a294 1474 bool "Profiling support"
125e5645
MD
1475 help
1476 Say Y here to enable the extended profiling support mechanisms used
1477 by profilers such as OProfile.
1478
5f87f112
IM
1479#
1480# Place an empty function call at each tracepoint site. Can be
1481# dynamically changed for a probe function.
1482#
97e1c18e 1483config TRACEPOINTS
5f87f112 1484 bool
97e1c18e 1485
fb32e03f
MD
1486source "arch/Kconfig"
1487
1da177e4
LT
1488endmenu # General setup
1489
ee7e5516
DES
1490config HAVE_GENERIC_DMA_COHERENT
1491 bool
1492 default n
1493
158a9624
LT
1494config SLABINFO
1495 bool
1496 depends on PROC_FS
0f389ec6 1497 depends on SLAB || SLUB_DEBUG
158a9624
LT
1498 default y
1499
ae81f9e3
CE
1500config RT_MUTEXES
1501 boolean
ae81f9e3 1502
1da177e4
LT
1503config BASE_SMALL
1504 int
1505 default 0 if BASE_FULL
1506 default 1 if !BASE_FULL
1507
66da5733 1508menuconfig MODULES
1da177e4
LT
1509 bool "Enable loadable module support"
1510 help
1511 Kernel modules are small pieces of compiled code which can
1512 be inserted in the running kernel, rather than being
1513 permanently built into the kernel. You use the "modprobe"
1514 tool to add (and sometimes remove) them. If you say Y here,
1515 many parts of the kernel can be built as modules (by
1516 answering M instead of Y where indicated): this is most
1517 useful for infrequently used options which are not required
1518 for booting. For more information, see the man pages for
1519 modprobe, lsmod, modinfo, insmod and rmmod.
1520
1521 If you say Y here, you will need to run "make
1522 modules_install" to put the modules under /lib/modules/
1523 where modprobe can find them (you may need to be root to do
1524 this).
1525
1526 If unsure, say Y.
1527
0b0de144
RD
1528if MODULES
1529
826e4506
LT
1530config MODULE_FORCE_LOAD
1531 bool "Forced module loading"
826e4506
LT
1532 default n
1533 help
91e37a79
RR
1534 Allow loading of modules without version information (ie. modprobe
1535 --force). Forced module loading sets the 'F' (forced) taint flag and
1536 is usually a really bad idea.
826e4506 1537
1da177e4
LT
1538config MODULE_UNLOAD
1539 bool "Module unloading"
1da177e4
LT
1540 help
1541 Without this option you will not be able to unload any
1542 modules (note that some modules may not be unloadable
f7f5b675
DV
1543 anyway), which makes your kernel smaller, faster
1544 and simpler. If unsure, say Y.
1da177e4
LT
1545
1546config MODULE_FORCE_UNLOAD
1547 bool "Forced module unloading"
1548 depends on MODULE_UNLOAD && EXPERIMENTAL
1549 help
1550 This option allows you to force a module to unload, even if the
1551 kernel believes it is unsafe: the kernel will remove the module
1552 without waiting for anyone to stop using it (using the -f option to
1553 rmmod). This is mainly for kernel developers and desperate users.
1554 If unsure, say N.
1555
1da177e4 1556config MODVERSIONS
0d541643 1557 bool "Module versioning support"
1da177e4
LT
1558 help
1559 Usually, you have to use modules compiled with your kernel.
1560 Saying Y here makes it sometimes possible to use modules
1561 compiled for different kernels, by adding enough information
1562 to the modules to (hopefully) spot any changes which would
1563 make them incompatible with the kernel you are running. If
1564 unsure, say N.
1565
1566config MODULE_SRCVERSION_ALL
1567 bool "Source checksum for all modules"
1da177e4
LT
1568 help
1569 Modules which contain a MODULE_VERSION get an extra "srcversion"
1570 field inserted into their modinfo section, which contains a
1571 sum of the source files which made it. This helps maintainers
1572 see exactly which source was used to build a module (since
1573 others sometimes change the module source without updating
1574 the version). With this option, such a "srcversion" field
1575 will be created for all modules. If unsure, say N.
1576
106a4ee2
RR
1577config MODULE_SIG
1578 bool "Module signature verification"
1579 depends on MODULES
48ba2462
DH
1580 select KEYS
1581 select CRYPTO
1582 select ASYMMETRIC_KEY_TYPE
1583 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1584 select PUBLIC_KEY_ALGO_RSA
1585 select ASN1
1586 select OID_REGISTRY
1587 select X509_CERTIFICATE_PARSER
106a4ee2
RR
1588 help
1589 Check modules for valid signatures upon load: the signature
1590 is simply appended to the module. For more information see
1591 Documentation/module-signing.txt.
1592
ea0b6dcf
DH
1593 !!!WARNING!!! If you enable this option, you MUST make sure that the
1594 module DOES NOT get stripped after being signed. This includes the
1595 debuginfo strip done by some packagers (such as rpmbuild) and
1596 inclusion into an initramfs that wants the module size reduced.
1597
106a4ee2
RR
1598config MODULE_SIG_FORCE
1599 bool "Require modules to be validly signed"
1600 depends on MODULE_SIG
1601 help
1602 Reject unsigned modules or signed modules for which we don't have a
1603 key. Without this, such modules will simply taint the kernel.
ea0b6dcf
DH
1604
1605choice
1606 prompt "Which hash algorithm should modules be signed with?"
1607 depends on MODULE_SIG
1608 help
1609 This determines which sort of hashing algorithm will be used during
1610 signature generation. This algorithm _must_ be built into the kernel
1611 directly so that signature verification can take place. It is not
1612 possible to load a signed module containing the algorithm to check
1613 the signature on that module.
1614
1615config MODULE_SIG_SHA1
1616 bool "Sign modules with SHA-1"
1617 select CRYPTO_SHA1
1618
1619config MODULE_SIG_SHA224
1620 bool "Sign modules with SHA-224"
1621 select CRYPTO_SHA256
1622
1623config MODULE_SIG_SHA256
1624 bool "Sign modules with SHA-256"
1625 select CRYPTO_SHA256
1626
1627config MODULE_SIG_SHA384
1628 bool "Sign modules with SHA-384"
1629 select CRYPTO_SHA512
1630
1631config MODULE_SIG_SHA512
1632 bool "Sign modules with SHA-512"
1633 select CRYPTO_SHA512
1634
1635endchoice
1636
0b0de144
RD
1637endif # MODULES
1638
98a79d6a
RR
1639config INIT_ALL_POSSIBLE
1640 bool
1641 help
5f054e31
RR
1642 Back when each arch used to define their own cpu_online_mask and
1643 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
98a79d6a
RR
1644 with all 1s, and others with all 0s. When they were centralised,
1645 it was better to provide this option than to break all the archs
692105b8 1646 and have several arch maintainers pursuing me down dark alleys.
98a79d6a 1647
1da177e4
LT
1648config STOP_MACHINE
1649 bool
1650 default y
1651 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1652 help
1653 Need stop_machine() primitive.
3a65dfe8 1654
3a65dfe8 1655source "block/Kconfig"
e98c3202
AK
1656
1657config PREEMPT_NOTIFIERS
1658 bool
e260be67 1659
16295bec
SK
1660config PADATA
1661 depends on SMP
1662 bool
1663
754b7b63
AK
1664# Can be selected by architectures with broken toolchains
1665# that get confused by correct const<->read_only section
1666# mappings
1667config BROKEN_RODATA
1668 bool
1669
4520c6a4
DH
1670config ASN1
1671 tristate
1672 help
1673 Build a simple ASN.1 grammar compiler that produces a bytecode output
1674 that can be interpreted by the ASN.1 stream decoder and used to
1675 inform it as to what tags are to be expected in a stream and what
1676 functions to call on what tags.
1677
6beb0009 1678source "kernel/Kconfig.locks"