rcu: rcu_barrier VS cpu_hotplug: Ensure callbacks in dead cpu are migrated to online cpu
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / init / Kconfig
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1config ARCH
2 string
3 option env="ARCH"
4
5config KERNELVERSION
6 string
7 option env="KERNELVERSION"
8
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9config DEFCONFIG_LIST
10 string
b2670eac 11 depends on !UML
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12 option defconfig_list
13 default "/lib/modules/$UNAME_RELEASE/.config"
14 default "/etc/kernel-config"
15 default "/boot/config-$UNAME_RELEASE"
73531905 16 default "$ARCH_DEFCONFIG"
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17 default "arch/$ARCH/defconfig"
18
ff0cfc66 19menu "General setup"
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20
21config EXPERIMENTAL
22 bool "Prompt for development and/or incomplete code/drivers"
23 ---help---
24 Some of the various things that Linux supports (such as network
25 drivers, file systems, network protocols, etc.) can be in a state
26 of development where the functionality, stability, or the level of
27 testing is not yet high enough for general use. This is usually
28 known as the "alpha-test" phase among developers. If a feature is
29 currently in alpha-test, then the developers usually discourage
30 uninformed widespread use of this feature by the general public to
31 avoid "Why doesn't this work?" type mail messages. However, active
32 testing and use of these systems is welcomed. Just be aware that it
33 may not meet the normal level of reliability or it may fail to work
34 in some special cases. Detailed bug reports from people familiar
35 with the kernel internals are usually welcomed by the developers
36 (before submitting bug reports, please read the documents
37 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
38 <file:Documentation/BUG-HUNTING>, and
39 <file:Documentation/oops-tracing.txt> in the kernel source).
40
41 This option will also make obsoleted drivers available. These are
42 drivers that have been replaced by something else, and/or are
43 scheduled to be removed in a future kernel release.
44
45 Unless you intend to help test and develop a feature or driver that
46 falls into this category, or you have a situation that requires
47 using these features, you should probably say N here, which will
48 cause the configurator to present you with fewer choices. If
49 you say Y here, you will be offered the choice of using features or
50 drivers that are currently considered to be in the alpha-test phase.
51
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52config BROKEN
53 bool
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54
55config BROKEN_ON_SMP
56 bool
57 depends on BROKEN || !SMP
58 default y
59
60config LOCK_KERNEL
61 bool
62 depends on SMP || PREEMPT
63 default y
64
65config INIT_ENV_ARG_LIMIT
66 int
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67 default 32 if !UML
68 default 128 if UML
1da177e4 69 help
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70 Maximum of each of the number of arguments and environment
71 variables passed to init from the kernel command line.
1da177e4 72
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73
74config LOCALVERSION
75 string "Local version - append to kernel release"
76 help
77 Append an extra string to the end of your kernel version.
78 This will show up when you type uname, for example.
79 The string you set here will be appended after the contents of
80 any files with a filename matching localversion* in your
81 object and source tree, in that order. Your total string can
82 be a maximum of 64 characters.
83
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84config LOCALVERSION_AUTO
85 bool "Automatically append version information to the version string"
86 default y
87 help
88 This will try to automatically determine if the current tree is a
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89 release tree by looking for git tags that belong to the current
90 top of tree revision.
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91
92 A string of the format -gxxxxxxxx will be added to the localversion
6e5a5420 93 if a git-based tree is found. The string generated by this will be
aaebf433 94 appended after any matching localversion* files, and after the value
6e5a5420 95 set in CONFIG_LOCALVERSION.
aaebf433 96
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97 (The actual string used here is the first eight characters produced
98 by running the command:
99
100 $ git rev-parse --verify HEAD
101
102 which is done within the script "scripts/setlocalversion".)
aaebf433 103
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104config HAVE_KERNEL_GZIP
105 bool
106
107config HAVE_KERNEL_BZIP2
108 bool
109
110config HAVE_KERNEL_LZMA
111 bool
112
30d65dbf 113choice
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114 prompt "Kernel compression mode"
115 default KERNEL_GZIP
116 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA
117 help
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118 The linux kernel is a kind of self-extracting executable.
119 Several compression algorithms are available, which differ
120 in efficiency, compression and decompression speed.
121 Compression speed is only relevant when building a kernel.
122 Decompression speed is relevant at each boot.
123
124 If you have any problems with bzip2 or lzma compressed
125 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
126 version of this functionality (bzip2 only), for 2.4, was
127 supplied by Christian Ludwig)
128
129 High compression options are mostly useful for users, who
130 are low on disk space (embedded systems), but for whom ram
131 size matters less.
132
133 If in doubt, select 'gzip'
134
135config KERNEL_GZIP
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136 bool "Gzip"
137 depends on HAVE_KERNEL_GZIP
138 help
139 The old and tried gzip compression. Its compression ratio is
140 the poorest among the 3 choices; however its speed (both
141 compression and decompression) is the fastest.
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142
143config KERNEL_BZIP2
144 bool "Bzip2"
2e9f3bdd 145 depends on HAVE_KERNEL_BZIP2
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146 help
147 Its compression ratio and speed is intermediate.
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148 Decompression speed is slowest among the three. The kernel
149 size is about 10% smaller with bzip2, in comparison to gzip.
150 Bzip2 uses a large amount of memory. For modern kernels you
151 will need at least 8MB RAM or more for booting.
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152
153config KERNEL_LZMA
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154 bool "LZMA"
155 depends on HAVE_KERNEL_LZMA
156 help
157 The most recent compression algorithm.
158 Its ratio is best, decompression speed is between the other
159 two. Compression is slowest. The kernel size is about 33%
160 smaller with LZMA in comparison to gzip.
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161
162endchoice
163
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164config SWAP
165 bool "Support for paging of anonymous memory (swap)"
9361401e 166 depends on MMU && BLOCK
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167 default y
168 help
169 This option allows you to choose whether you want to have support
92c3504e 170 for so called swap devices or swap files in your kernel that are
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171 used to provide more virtual memory than the actual RAM present
172 in your computer. If unsure say Y.
173
174config SYSVIPC
175 bool "System V IPC"
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176 ---help---
177 Inter Process Communication is a suite of library functions and
178 system calls which let processes (running programs) synchronize and
179 exchange information. It is generally considered to be a good thing,
180 and some programs won't run unless you say Y here. In particular, if
181 you want to run the DOS emulator dosemu under Linux (read the
182 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
183 you'll need to say Y here.
184
185 You can find documentation about IPC with "info ipc" and also in
186 section 6.4 of the Linux Programmer's Guide, available from
187 <http://www.tldp.org/guides.html>.
188
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189config SYSVIPC_SYSCTL
190 bool
191 depends on SYSVIPC
192 depends on SYSCTL
193 default y
194
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195config POSIX_MQUEUE
196 bool "POSIX Message Queues"
197 depends on NET && EXPERIMENTAL
198 ---help---
199 POSIX variant of message queues is a part of IPC. In POSIX message
200 queues every message has a priority which decides about succession
201 of receiving it by a process. If you want to compile and run
202 programs written e.g. for Solaris with use of its POSIX message
b0e37650 203 queues (functions mq_*) say Y here.
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204
205 POSIX message queues are visible as a filesystem called 'mqueue'
206 and can be mounted somewhere if you want to do filesystem
207 operations on message queues.
208
209 If unsure, say Y.
210
211config BSD_PROCESS_ACCT
212 bool "BSD Process Accounting"
213 help
214 If you say Y here, a user level program will be able to instruct the
215 kernel (via a special system call) to write process accounting
216 information to a file: whenever a process exits, information about
217 that process will be appended to the file by the kernel. The
218 information includes things such as creation time, owning user,
219 command name, memory usage, controlling terminal etc. (the complete
220 list is in the struct acct in <file:include/linux/acct.h>). It is
221 up to the user level program to do useful things with this
222 information. This is generally a good idea, so say Y.
223
224config BSD_PROCESS_ACCT_V3
225 bool "BSD Process Accounting version 3 file format"
226 depends on BSD_PROCESS_ACCT
227 default n
228 help
229 If you say Y here, the process accounting information is written
230 in a new file format that also logs the process IDs of each
231 process and it's parent. Note that this file format is incompatible
232 with previous v0/v1/v2 file formats, so you will need updated tools
233 for processing it. A preliminary version of these tools is available
37a4c940 234 at <http://www.gnu.org/software/acct/>.
1da177e4 235
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236config TASKSTATS
237 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
238 depends on NET
239 default n
240 help
241 Export selected statistics for tasks/processes through the
242 generic netlink interface. Unlike BSD process accounting, the
243 statistics are available during the lifetime of tasks/processes as
244 responses to commands. Like BSD accounting, they are sent to user
245 space on task exit.
246
247 Say N if unsure.
248
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249config TASK_DELAY_ACCT
250 bool "Enable per-task delay accounting (EXPERIMENTAL)"
6f44993f 251 depends on TASKSTATS
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252 help
253 Collect information on time spent by a task waiting for system
254 resources like cpu, synchronous block I/O completion and swapping
255 in pages. Such statistics can help in setting a task's priorities
256 relative to other tasks for cpu, io, rss limits etc.
257
258 Say N if unsure.
259
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260config TASK_XACCT
261 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
262 depends on TASKSTATS
263 help
264 Collect extended task accounting data and send the data
265 to userland for processing over the taskstats interface.
266
267 Say N if unsure.
268
269config TASK_IO_ACCOUNTING
270 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
271 depends on TASK_XACCT
272 help
273 Collect information on the number of bytes of storage I/O which this
274 task has caused.
275
276 Say N if unsure.
277
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278config AUDIT
279 bool "Auditing support"
804a6a49 280 depends on NET
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281 help
282 Enable auditing infrastructure that can be used with another
283 kernel subsystem, such as SELinux (which requires this for
284 logging of avc messages output). Does not do system-call
285 auditing without CONFIG_AUDITSYSCALL.
286
287config AUDITSYSCALL
288 bool "Enable system-call auditing support"
1322b9de 289 depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64|| SUPERH)
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290 default y if SECURITY_SELINUX
291 help
292 Enable low-overhead system-call auditing infrastructure that
293 can be used independently or with another kernel subsystem,
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294 such as SELinux. To use audit's filesystem watch feature, please
295 ensure that INOTIFY is configured.
1da177e4 296
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297config AUDIT_TREE
298 def_bool y
299 depends on AUDITSYSCALL && INOTIFY
300
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301menu "RCU Subsystem"
302
303choice
304 prompt "RCU Implementation"
305 default CLASSIC_RCU
306
307config CLASSIC_RCU
308 bool "Classic RCU"
309 help
310 This option selects the classic RCU implementation that is
311 designed for best read-side performance on non-realtime
312 systems.
313
314 Select this option if you are unsure.
315
316config TREE_RCU
317 bool "Tree-based hierarchical RCU"
318 help
319 This option selects the RCU implementation that is
320 designed for very large SMP system with hundreds or
321 thousands of CPUs.
322
323config PREEMPT_RCU
324 bool "Preemptible RCU"
325 depends on PREEMPT
326 help
327 This option reduces the latency of the kernel by making certain
328 RCU sections preemptible. Normally RCU code is non-preemptible, if
329 this option is selected then read-only RCU sections become
330 preemptible. This helps latency, but may expose bugs due to
331 now-naive assumptions about each RCU read-side critical section
332 remaining on a given CPU through its execution.
333
334endchoice
335
336config RCU_TRACE
337 bool "Enable tracing for RCU"
338 depends on TREE_RCU || PREEMPT_RCU
339 help
340 This option provides tracing in RCU which presents stats
341 in debugfs for debugging RCU implementation.
342
343 Say Y here if you want to enable RCU tracing
344 Say N if you are unsure.
345
346config RCU_FANOUT
347 int "Tree-based hierarchical RCU fanout value"
348 range 2 64 if 64BIT
349 range 2 32 if !64BIT
350 depends on TREE_RCU
351 default 64 if 64BIT
352 default 32 if !64BIT
353 help
354 This option controls the fanout of hierarchical implementations
355 of RCU, allowing RCU to work efficiently on machines with
356 large numbers of CPUs. This value must be at least the cube
357 root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
358 systems and up to 262,144 for 64-bit systems.
359
360 Select a specific number if testing RCU itself.
361 Take the default if unsure.
362
363config RCU_FANOUT_EXACT
364 bool "Disable tree-based hierarchical RCU auto-balancing"
365 depends on TREE_RCU
366 default n
367 help
368 This option forces use of the exact RCU_FANOUT value specified,
369 regardless of imbalances in the hierarchy. This is useful for
370 testing RCU itself, and might one day be useful on systems with
371 strong NUMA behavior.
372
373 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
374
375 Say N if unsure.
376
377config TREE_RCU_TRACE
378 def_bool RCU_TRACE && TREE_RCU
379 select DEBUG_FS
380 help
381 This option provides tracing for the TREE_RCU implementation,
382 permitting Makefile to trivially select kernel/rcutree_trace.c.
383
384config PREEMPT_RCU_TRACE
385 def_bool RCU_TRACE && PREEMPT_RCU
386 select DEBUG_FS
387 help
388 This option provides tracing for the PREEMPT_RCU implementation,
389 permitting Makefile to trivially select kernel/rcupreempt_trace.c.
390
391endmenu # "RCU Subsystem"
392
1da177e4 393config IKCONFIG
f2443ab6 394 tristate "Kernel .config support"
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395 ---help---
396 This option enables the complete Linux kernel ".config" file
397 contents to be saved in the kernel. It provides documentation
398 of which kernel options are used in a running kernel or in an
399 on-disk kernel. This information can be extracted from the kernel
400 image file with the script scripts/extract-ikconfig and used as
401 input to rebuild the current kernel or to build another kernel.
402 It can also be extracted from a running kernel by reading
403 /proc/config.gz if enabled (below).
404
405config IKCONFIG_PROC
406 bool "Enable access to .config through /proc/config.gz"
407 depends on IKCONFIG && PROC_FS
408 ---help---
409 This option enables access to the kernel configuration file
410 through /proc/config.gz.
411
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412config LOG_BUF_SHIFT
413 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
414 range 12 21
f17a32e9 415 default 17
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416 help
417 Select kernel log buffer size as a power of 2.
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418 Examples:
419 17 => 128 KB
420 16 => 64 KB
421 15 => 32 KB
422 14 => 16 KB
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423 13 => 8 KB
424 12 => 4 KB
425
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426#
427# Architectures with an unreliable sched_clock() should select this:
428#
429config HAVE_UNSTABLE_SCHED_CLOCK
430 bool
431
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432config GROUP_SCHED
433 bool "Group CPU scheduler"
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434 depends on EXPERIMENTAL
435 default n
29f59db3 436 help
fb615581 437 This feature lets CPU scheduler recognize task groups and control CPU
9b5b7751 438 bandwidth allocation to such task groups.
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439 In order to create a group from arbitrary set of processes, use
440 CONFIG_CGROUPS. (See Control Group support.)
29f59db3 441
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442config FAIR_GROUP_SCHED
443 bool "Group scheduling for SCHED_OTHER"
444 depends on GROUP_SCHED
aac6abca 445 default GROUP_SCHED
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446
447config RT_GROUP_SCHED
448 bool "Group scheduling for SCHED_RR/FIFO"
449 depends on EXPERIMENTAL
450 depends on GROUP_SCHED
451 default n
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452 help
453 This feature lets you explicitly allocate real CPU bandwidth
454 to users or control groups (depending on the "Basis for grouping tasks"
455 setting below. If enabled, it will also make it impossible to
456 schedule realtime tasks for non-root users until you allocate
457 realtime bandwidth for them.
2fe401e3 458 See Documentation/scheduler/sched-rt-group.txt for more information.
052f1dc7 459
24e377a8 460choice
052f1dc7 461 depends on GROUP_SCHED
24e377a8 462 prompt "Basis for grouping tasks"
052f1dc7 463 default USER_SCHED
24e377a8 464
052f1dc7 465config USER_SCHED
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466 bool "user id"
467 help
468 This option will choose userid as the basis for grouping
469 tasks, thus providing equal CPU bandwidth to each user.
24e377a8 470
052f1dc7 471config CGROUP_SCHED
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472 bool "Control groups"
473 depends on CGROUPS
474 help
475 This option allows you to create arbitrary task groups
476 using the "cgroup" pseudo filesystem and control
477 the cpu bandwidth allocated to each such task group.
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478 Refer to Documentation/cgroups/cgroups.txt for more
479 information on "cgroup" pseudo filesystem.
68318b8e 480
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481endchoice
482
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483menuconfig CGROUPS
484 boolean "Control Group support"
5cdc38f9 485 help
23964d2d 486 This option adds support for grouping sets of processes together, for
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487 use with process control subsystems such as Cpusets, CFS, memory
488 controls or device isolation.
489 See
5cdc38f9 490 - Documentation/scheduler/sched-design-CFS.txt (CFS)
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491 - Documentation/cgroups/ (features for grouping, isolation
492 and resource control)
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493
494 Say N if unsure.
495
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496if CGROUPS
497
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498config CGROUP_DEBUG
499 bool "Example debug cgroup subsystem"
500 depends on CGROUPS
501 default n
502 help
503 This option enables a simple cgroup subsystem that
504 exports useful debugging information about the cgroups
23964d2d 505 framework.
5cdc38f9 506
23964d2d 507 Say N if unsure.
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508
509config CGROUP_NS
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510 bool "Namespace cgroup subsystem"
511 depends on CGROUPS
512 help
513 Provides a simple namespace cgroup subsystem to
514 provide hierarchical naming of sets of namespaces,
515 for instance virtual servers and checkpoint/restart
516 jobs.
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517
518config CGROUP_FREEZER
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519 bool "Freezer cgroup subsystem"
520 depends on CGROUPS
521 help
522 Provides a way to freeze and unfreeze all tasks in a
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523 cgroup.
524
525config CGROUP_DEVICE
526 bool "Device controller for cgroups"
527 depends on CGROUPS && EXPERIMENTAL
528 help
529 Provides a cgroup implementing whitelists for devices which
530 a process in the cgroup can mknod or open.
531
532config CPUSETS
533 bool "Cpuset support"
534 depends on SMP && CGROUPS
535 help
536 This option will let you create and manage CPUSETs which
537 allow dynamically partitioning a system into sets of CPUs and
538 Memory Nodes and assigning tasks to run only within those sets.
539 This is primarily useful on large SMP or NUMA systems.
540
541 Say N if unsure.
542
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543config PROC_PID_CPUSET
544 bool "Include legacy /proc/<pid>/cpuset file"
545 depends on CPUSETS
546 default y
547
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548config CGROUP_CPUACCT
549 bool "Simple CPU accounting cgroup subsystem"
550 depends on CGROUPS
551 help
552 Provides a simple Resource Controller for monitoring the
23964d2d 553 total CPU consumed by the tasks in a cgroup.
d842de87 554
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555config RESOURCE_COUNTERS
556 bool "Resource counters"
557 help
558 This option enables controller independent resource accounting
23964d2d 559 infrastructure that works with cgroups.
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560 depends on CGROUPS
561
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562config CGROUP_MEM_RES_CTLR
563 bool "Memory Resource Controller for Control Groups"
564 depends on CGROUPS && RESOURCE_COUNTERS
cf475ad2 565 select MM_OWNER
00f0b825 566 help
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567 Provides a memory resource controller that manages both anonymous
568 memory and page cache. (See Documentation/controllers/memory.txt)
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569
570 Note that setting this option increases fixed memory overhead
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571 associated with each page of memory in the system. By this,
572 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
573 usage tracking struct at boot. Total amount of this is printed out
574 at boot.
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575
576 Only enable when you're ok with these trade offs and really
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577 sure you need the memory resource controller. Even when you enable
578 this, you can set "cgroup_disable=memory" at your boot option to
579 disable memory resource controller and you can avoid overheads.
c9d5409f 580 (and lose benefits of memory resource controller)
00f0b825 581
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582 This config option also selects MM_OWNER config option, which
583 could in turn add some fork/exit overhead.
584
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585config CGROUP_MEM_RES_CTLR_SWAP
586 bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)"
587 depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL
588 help
589 Add swap management feature to memory resource controller. When you
590 enable this, you can limit mem+swap usage per cgroup. In other words,
591 when you disable this, memory resource controller has no cares to
592 usage of swap...a process can exhaust all of the swap. This extension
593 is useful when you want to avoid exhaustion swap but this itself
594 adds more overheads and consumes memory for remembering information.
595 Especially if you use 32bit system or small memory system, please
596 be careful about enabling this. When memory resource controller
597 is disabled by boot option, this will be automatically disabled and
598 there will be no overhead from this. Even when you set this config=y,
599 if boot option "noswapaccount" is set, swap will not be accounted.
600
23964d2d 601endif # CGROUPS
c077719b 602
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603config MM_OWNER
604 bool
5cdc38f9 605
88a22c98 606config SYSFS_DEPRECATED
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607 bool
608
609config SYSFS_DEPRECATED_V2
fce3e804 610 bool "Create deprecated sysfs layout for older userspace tools"
9148fe87 611 depends on SYSFS
88a22c98 612 default y
d47846c5 613 select SYSFS_DEPRECATED
88a22c98 614 help
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615 This option switches the layout of sysfs to the deprecated
616 version.
617
618 The current sysfs layout features a unified device tree at
619 /sys/devices/, which is able to express a hierarchy between
620 class devices. If the deprecated option is set to Y, the
621 unified device tree is split into a bus device tree at
622 /sys/devices/ and several individual class device trees at
623 /sys/class/. The class and bus devices will be connected by
624 "<subsystem>:<name>" and the "device" links. The "block"
625 class devices, will not show up in /sys/class/block/. Some
626 subsystems will suppress the creation of some devices which
627 depend on the unified device tree.
628
629 This option is not a pure compatibility option that can
630 be safely enabled on newer distributions. It will change the
631 layout of sysfs to the non-extensible deprecated version,
632 and disable some features, which can not be exported without
633 confusing older userspace tools. Since 2007/2008 all major
634 distributions do not enable this option, and ship no tools which
635 depend on the deprecated layout or this option.
636
637 If you are using a new kernel on an older distribution, or use
638 older userspace tools, you might need to say Y here. Do not say Y,
639 if the original kernel, that came with your distribution, has
640 this option set to N.
88a22c98 641
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642config RELAY
643 bool "Kernel->user space relay support (formerly relayfs)"
644 help
645 This option enables support for relay interface support in
646 certain file systems (such as debugfs).
647 It is designed to provide an efficient mechanism for tools and
648 facilities to relay large amounts of data from kernel space to
649 user space.
650
651 If unsure, say N.
652
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653config NAMESPACES
654 bool "Namespaces support" if EMBEDDED
655 default !EMBEDDED
656 help
657 Provides the way to make tasks work with different objects using
658 the same id. For example same IPC id may refer to different objects
659 or same user id or pid may refer to different tasks when used in
660 different namespaces.
661
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662config UTS_NS
663 bool "UTS namespace"
664 depends on NAMESPACES
665 help
666 In this namespace tasks see different info provided with the
667 uname() system call
668
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669config IPC_NS
670 bool "IPC namespace"
671 depends on NAMESPACES && SYSVIPC
672 help
673 In this namespace tasks work with IPC ids which correspond to
674 different IPC objects in different namespaces
675
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676config USER_NS
677 bool "User namespace (EXPERIMENTAL)"
678 depends on NAMESPACES && EXPERIMENTAL
679 help
680 This allows containers, i.e. vservers, to use user namespaces
681 to provide different user info for different servers.
682 If unsure, say N.
683
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684config PID_NS
685 bool "PID Namespaces (EXPERIMENTAL)"
686 default n
687 depends on NAMESPACES && EXPERIMENTAL
688 help
12d2b8f9 689 Support process id namespaces. This allows having multiple
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690 process with the same pid as long as they are in different
691 pid namespaces. This is a building block of containers.
692
693 Unless you want to work with an experimental feature
694 say N here.
695
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696config NET_NS
697 bool "Network namespace"
698 default n
699 depends on NAMESPACES && EXPERIMENTAL && NET
700 help
701 Allow user space to create what appear to be multiple instances
702 of the network stack.
703
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704config BLK_DEV_INITRD
705 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
706 depends on BROKEN || !FRV
707 help
708 The initial RAM filesystem is a ramfs which is loaded by the
709 boot loader (loadlin or lilo) and that is mounted as root
710 before the normal boot procedure. It is typically used to
711 load modules needed to mount the "real" root file system,
712 etc. See <file:Documentation/initrd.txt> for details.
713
714 If RAM disk support (BLK_DEV_RAM) is also included, this
715 also enables initial RAM disk (initrd) support and adds
716 15 Kbytes (more on some other architectures) to the kernel size.
717
718 If unsure say Y.
719
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720if BLK_DEV_INITRD
721
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722source "usr/Kconfig"
723
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724endif
725
c45b4f1f 726config CC_OPTIMIZE_FOR_SIZE
96fffeb4 727 bool "Optimize for size"
c45b4f1f 728 default y
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729 help
730 Enabling this option will pass "-Os" instead of "-O2" to gcc
731 resulting in a smaller kernel.
732
775a7229 733 If unsure, say Y.
c45b4f1f 734
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735config SYSCTL
736 bool
737
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738config ANON_INODES
739 bool
740
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741menuconfig EMBEDDED
742 bool "Configure standard kernel features (for small systems)"
743 help
744 This option allows certain base kernel options and settings
745 to be disabled or tweaked. This is for specialized
746 environments which can tolerate a "non-standard" kernel.
747 Only use this if you really know what you are doing.
748
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749config UID16
750 bool "Enable 16-bit UID system calls" if EMBEDDED
09337f50 751 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
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752 default y
753 help
754 This enables the legacy 16-bit UID syscall wrappers.
755
b89a8171 756config SYSCTL_SYSCALL
0847062a 757 bool "Sysctl syscall support" if EMBEDDED
13bb7e37 758 default y
b89a8171 759 select SYSCTL
ae81f9e3 760 ---help---
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EB
761 sys_sysctl uses binary paths that have been found challenging
762 to properly maintain and use. The interface in /proc/sys
763 using paths with ascii names is now the primary path to this
764 information.
b89a8171 765
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EB
766 Almost nothing using the binary sysctl interface so if you are
767 trying to save some space it is probably safe to disable this,
768 making your kernel marginally smaller.
b89a8171 769
13bb7e37 770 If unsure say Y here.
ae81f9e3 771
1da177e4 772config KALLSYMS
979c6a1e 773 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
1da177e4
LT
774 default y
775 help
776 Say Y here to let the kernel print out symbolic crash information and
777 symbolic stack backtraces. This increases the size of the kernel
778 somewhat, as all symbols have to be loaded into the kernel image.
779
780config KALLSYMS_ALL
781 bool "Include all symbols in kallsyms"
782 depends on DEBUG_KERNEL && KALLSYMS
783 help
784 Normally kallsyms only contains the symbols of functions, for nicer
785 OOPS messages. Some debuggers can use kallsyms for other
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JJ
786 symbols too: say Y here to include all symbols, if you need them
787 and you don't care about adding 300k to the size of your kernel.
1da177e4
LT
788
789 Say N.
790
791config KALLSYMS_EXTRA_PASS
792 bool "Do an extra kallsyms pass"
793 depends on KALLSYMS
794 help
795 If kallsyms is not working correctly, the build will fail with
796 inconsistent kallsyms data. If that occurs, log a bug report and
797 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
798 Always say N here unless you find a bug in kallsyms, which must be
799 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
800 you wait for kallsyms to be fixed.
801
d59745ce 802
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803config HOTPLUG
804 bool "Support for hot-pluggable devices" if EMBEDDED
805 default y
806 help
807 This option is provided for the case where no hotplug or uevent
808 capabilities is wanted by the kernel. You should only consider
809 disabling this option for embedded systems that do not use modules, a
810 dynamic /dev tree, or dynamic device discovery. Just say Y.
811
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812config PRINTK
813 default y
814 bool "Enable support for printk" if EMBEDDED
815 help
816 This option enables normal printk support. Removing it
817 eliminates most of the message strings from the kernel image
818 and makes the kernel more or less silent. As this makes it
819 very difficult to diagnose system problems, saying N here is
820 strongly discouraged.
821
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MM
822config BUG
823 bool "BUG() support" if EMBEDDED
824 default y
825 help
826 Disabling this option eliminates support for BUG and WARN, reducing
827 the size of your kernel image and potentially quietly ignoring
828 numerous fatal conditions. You should only consider disabling this
829 option for embedded systems with no facilities for reporting errors.
830 Just say Y.
831
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MM
832config ELF_CORE
833 default y
834 bool "Enable ELF core dumps" if EMBEDDED
835 help
836 Enable support for generating core dumps. Disabling saves about 4k.
837
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SS
838config PCSPKR_PLATFORM
839 bool "Enable PC-Speaker support" if EMBEDDED
840 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
841 default y
842 help
843 This option allows to disable the internal PC-Speaker
844 support, saving some memory.
845
1da177e4
LT
846config BASE_FULL
847 default y
848 bool "Enable full-sized data structures for core" if EMBEDDED
849 help
850 Disabling this option reduces the size of miscellaneous core
851 kernel data structures. This saves memory on small machines,
852 but may reduce performance.
853
854config FUTEX
855 bool "Enable futex support" if EMBEDDED
856 default y
23f78d4a 857 select RT_MUTEXES
1da177e4
LT
858 help
859 Disabling this option will cause the kernel to be built without
860 support for "fast userspace mutexes". The resulting kernel may not
861 run glibc-based applications correctly.
862
863config EPOLL
864 bool "Enable eventpoll support" if EMBEDDED
865 default y
448e3cee 866 select ANON_INODES
1da177e4
LT
867 help
868 Disabling this option will cause the kernel to be built without
869 support for epoll family of system calls.
870
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DL
871config SIGNALFD
872 bool "Enable signalfd() system call" if EMBEDDED
448e3cee 873 select ANON_INODES
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DL
874 default y
875 help
876 Enable the signalfd() system call that allows to receive signals
877 on a file descriptor.
878
879 If unsure, say Y.
880
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881config TIMERFD
882 bool "Enable timerfd() system call" if EMBEDDED
448e3cee 883 select ANON_INODES
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884 default y
885 help
886 Enable the timerfd() system call that allows to receive timer
887 events on a file descriptor.
888
889 If unsure, say Y.
890
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891config EVENTFD
892 bool "Enable eventfd() system call" if EMBEDDED
448e3cee 893 select ANON_INODES
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DL
894 default y
895 help
896 Enable the eventfd() system call that allows to receive both
897 kernel notification (ie. KAIO) or userspace notifications.
898
899 If unsure, say Y.
900
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LT
901config SHMEM
902 bool "Use full shmem filesystem" if EMBEDDED
903 default y
904 depends on MMU
905 help
906 The shmem is an internal filesystem used to manage shared memory.
907 It is backed by swap and manages resource limits. It is also exported
908 to userspace as tmpfs if TMPFS is enabled. Disabling this
909 option replaces shmem and tmpfs with the much simpler ramfs code,
910 which may be appropriate on small systems without swap.
911
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912config AIO
913 bool "Enable AIO support" if EMBEDDED
914 default y
915 help
916 This option enables POSIX asynchronous I/O which may by used
917 by some high performance threaded applications. Disabling
918 this option saves about 7k.
919
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920config VM_EVENT_COUNTERS
921 default y
922 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
923 help
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PJ
924 VM event counters are needed for event counts to be shown.
925 This option allows the disabling of the VM event counters
926 on EMBEDDED systems. /proc/vmstat will only show page counts
927 if VM event counters are disabled.
f8891e5e 928
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929config PCI_QUIRKS
930 default y
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GU
931 bool "Enable PCI quirk workarounds" if EMBEDDED
932 depends on PCI
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TP
933 help
934 This enables workarounds for various PCI chipset
935 bugs/quirks. Disable this only if your target machine is
936 unaffected by PCI quirks.
937
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CL
938config SLUB_DEBUG
939 default y
940 bool "Enable SLUB debugging support" if EMBEDDED
f6acb635 941 depends on SLUB && SYSFS
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CL
942 help
943 SLUB has extensive debug support features. Disabling these can
944 result in significant savings in code size. This also disables
945 SLUB sysfs support. /sys/slab will not exist and there will be
946 no support for cache validation etc.
947
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948config COMPAT_BRK
949 bool "Disable heap randomization"
950 default y
951 help
952 Randomizing heap placement makes heap exploits harder, but it
953 also breaks ancient binaries (including anything libc5 based).
954 This option changes the bootup default to heap randomization
955 disabled, and can be overriden runtime by setting
956 /proc/sys/kernel/randomize_va_space to 2.
957
958 On non-ancient distros (post-2000 ones) N is usually a safe choice.
959
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CL
960choice
961 prompt "Choose SLAB allocator"
a0acd820 962 default SLUB
81819f0f
CL
963 help
964 This option allows to select a slab allocator.
965
966config SLAB
967 bool "SLAB"
968 help
969 The regular slab allocator that is established and known to work
34013886 970 well in all environments. It organizes cache hot objects in
02f56210 971 per cpu and per node queues.
81819f0f
CL
972
973config SLUB
81819f0f
CL
974 bool "SLUB (Unqueued Allocator)"
975 help
976 SLUB is a slab allocator that minimizes cache line usage
977 instead of managing queues of cached objects (SLAB approach).
978 Per cpu caching is realized using slabs of objects instead
979 of queues of objects. SLUB can use memory efficiently
02f56210
SA
980 and has enhanced diagnostics. SLUB is the default choice for
981 a slab allocator.
81819f0f
CL
982
983config SLOB
84a01c2f 984 depends on EMBEDDED
81819f0f
CL
985 bool "SLOB (Simple Allocator)"
986 help
37291458
MM
987 SLOB replaces the stock allocator with a drastically simpler
988 allocator. SLOB is generally more space efficient but
989 does not perform as well on large systems.
81819f0f
CL
990
991endchoice
992
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MD
993config PROFILING
994 bool "Profiling support (EXPERIMENTAL)"
995 help
996 Say Y here to enable the extended profiling support mechanisms used
997 by profilers such as OProfile.
998
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IM
999#
1000# Place an empty function call at each tracepoint site. Can be
1001# dynamically changed for a probe function.
1002#
97e1c18e 1003config TRACEPOINTS
5f87f112 1004 bool
97e1c18e 1005
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MD
1006config MARKERS
1007 bool "Activate markers"
c1df1bd2 1008 depends on TRACEPOINTS
125e5645
MD
1009 help
1010 Place an empty function call at each marker site. Can be
1011 dynamically changed for a probe function.
1012
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MD
1013source "arch/Kconfig"
1014
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LT
1015endmenu # General setup
1016
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DES
1017config HAVE_GENERIC_DMA_COHERENT
1018 bool
1019 default n
1020
158a9624
LT
1021config SLABINFO
1022 bool
1023 depends on PROC_FS
0f389ec6 1024 depends on SLAB || SLUB_DEBUG
158a9624
LT
1025 default y
1026
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CE
1027config RT_MUTEXES
1028 boolean
ae81f9e3 1029
1da177e4
LT
1030config BASE_SMALL
1031 int
1032 default 0 if BASE_FULL
1033 default 1 if !BASE_FULL
1034
66da5733 1035menuconfig MODULES
1da177e4
LT
1036 bool "Enable loadable module support"
1037 help
1038 Kernel modules are small pieces of compiled code which can
1039 be inserted in the running kernel, rather than being
1040 permanently built into the kernel. You use the "modprobe"
1041 tool to add (and sometimes remove) them. If you say Y here,
1042 many parts of the kernel can be built as modules (by
1043 answering M instead of Y where indicated): this is most
1044 useful for infrequently used options which are not required
1045 for booting. For more information, see the man pages for
1046 modprobe, lsmod, modinfo, insmod and rmmod.
1047
1048 If you say Y here, you will need to run "make
1049 modules_install" to put the modules under /lib/modules/
1050 where modprobe can find them (you may need to be root to do
1051 this).
1052
1053 If unsure, say Y.
1054
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RD
1055if MODULES
1056
826e4506
LT
1057config MODULE_FORCE_LOAD
1058 bool "Forced module loading"
826e4506
LT
1059 default n
1060 help
91e37a79
RR
1061 Allow loading of modules without version information (ie. modprobe
1062 --force). Forced module loading sets the 'F' (forced) taint flag and
1063 is usually a really bad idea.
826e4506 1064
1da177e4
LT
1065config MODULE_UNLOAD
1066 bool "Module unloading"
1da177e4
LT
1067 help
1068 Without this option you will not be able to unload any
1069 modules (note that some modules may not be unloadable
f7f5b675
DV
1070 anyway), which makes your kernel smaller, faster
1071 and simpler. If unsure, say Y.
1da177e4
LT
1072
1073config MODULE_FORCE_UNLOAD
1074 bool "Forced module unloading"
1075 depends on MODULE_UNLOAD && EXPERIMENTAL
1076 help
1077 This option allows you to force a module to unload, even if the
1078 kernel believes it is unsafe: the kernel will remove the module
1079 without waiting for anyone to stop using it (using the -f option to
1080 rmmod). This is mainly for kernel developers and desperate users.
1081 If unsure, say N.
1082
1da177e4 1083config MODVERSIONS
0d541643 1084 bool "Module versioning support"
1da177e4
LT
1085 help
1086 Usually, you have to use modules compiled with your kernel.
1087 Saying Y here makes it sometimes possible to use modules
1088 compiled for different kernels, by adding enough information
1089 to the modules to (hopefully) spot any changes which would
1090 make them incompatible with the kernel you are running. If
1091 unsure, say N.
1092
1093config MODULE_SRCVERSION_ALL
1094 bool "Source checksum for all modules"
1da177e4
LT
1095 help
1096 Modules which contain a MODULE_VERSION get an extra "srcversion"
1097 field inserted into their modinfo section, which contains a
1098 sum of the source files which made it. This helps maintainers
1099 see exactly which source was used to build a module (since
1100 others sometimes change the module source without updating
1101 the version). With this option, such a "srcversion" field
1102 will be created for all modules. If unsure, say N.
1103
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1104endif # MODULES
1105
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RR
1106config INIT_ALL_POSSIBLE
1107 bool
1108 help
1109 Back when each arch used to define their own cpu_online_map and
1110 cpu_possible_map, some of them chose to initialize cpu_possible_map
1111 with all 1s, and others with all 0s. When they were centralised,
1112 it was better to provide this option than to break all the archs
1113 and have several arch maintainers persuing me down dark alleys.
1114
1da177e4
LT
1115config STOP_MACHINE
1116 bool
1117 default y
1118 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1119 help
1120 Need stop_machine() primitive.
3a65dfe8 1121
3a65dfe8 1122source "block/Kconfig"
e98c3202
AK
1123
1124config PREEMPT_NOTIFIERS
1125 bool
e260be67 1126