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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42 drivers that have been replaced by something else, and/or are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
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211config POSIX_MQUEUE_SYSCTL
212 bool
213 depends on POSIX_MQUEUE
214 depends on SYSCTL
215 default y
216
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217config BSD_PROCESS_ACCT
218 bool "BSD Process Accounting"
219 help
220 If you say Y here, a user level program will be able to instruct the
221 kernel (via a special system call) to write process accounting
222 information to a file: whenever a process exits, information about
223 that process will be appended to the file by the kernel. The
224 information includes things such as creation time, owning user,
225 command name, memory usage, controlling terminal etc. (the complete
226 list is in the struct acct in <file:include/linux/acct.h>). It is
227 up to the user level program to do useful things with this
228 information. This is generally a good idea, so say Y.
229
230config BSD_PROCESS_ACCT_V3
231 bool "BSD Process Accounting version 3 file format"
232 depends on BSD_PROCESS_ACCT
233 default n
234 help
235 If you say Y here, the process accounting information is written
236 in a new file format that also logs the process IDs of each
237 process and it's parent. Note that this file format is incompatible
238 with previous v0/v1/v2 file formats, so you will need updated tools
239 for processing it. A preliminary version of these tools is available
37a4c940 240 at <http://www.gnu.org/software/acct/>.
1da177e4 241
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242config TASKSTATS
243 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
244 depends on NET
245 default n
246 help
247 Export selected statistics for tasks/processes through the
248 generic netlink interface. Unlike BSD process accounting, the
249 statistics are available during the lifetime of tasks/processes as
250 responses to commands. Like BSD accounting, they are sent to user
251 space on task exit.
252
253 Say N if unsure.
254
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255config TASK_DELAY_ACCT
256 bool "Enable per-task delay accounting (EXPERIMENTAL)"
6f44993f 257 depends on TASKSTATS
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258 help
259 Collect information on time spent by a task waiting for system
260 resources like cpu, synchronous block I/O completion and swapping
261 in pages. Such statistics can help in setting a task's priorities
262 relative to other tasks for cpu, io, rss limits etc.
263
264 Say N if unsure.
265
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266config TASK_XACCT
267 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
268 depends on TASKSTATS
269 help
270 Collect extended task accounting data and send the data
271 to userland for processing over the taskstats interface.
272
273 Say N if unsure.
274
275config TASK_IO_ACCOUNTING
276 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
277 depends on TASK_XACCT
278 help
279 Collect information on the number of bytes of storage I/O which this
280 task has caused.
281
282 Say N if unsure.
283
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284config AUDIT
285 bool "Auditing support"
804a6a49 286 depends on NET
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287 help
288 Enable auditing infrastructure that can be used with another
289 kernel subsystem, such as SELinux (which requires this for
290 logging of avc messages output). Does not do system-call
291 auditing without CONFIG_AUDITSYSCALL.
292
293config AUDITSYSCALL
294 bool "Enable system-call auditing support"
1322b9de 295 depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64|| SUPERH)
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296 default y if SECURITY_SELINUX
297 help
298 Enable low-overhead system-call auditing infrastructure that
299 can be used independently or with another kernel subsystem,
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300 such as SELinux. To use audit's filesystem watch feature, please
301 ensure that INOTIFY is configured.
1da177e4 302
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303config AUDIT_TREE
304 def_bool y
305 depends on AUDITSYSCALL && INOTIFY
306
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307menu "RCU Subsystem"
308
309choice
310 prompt "RCU Implementation"
311 default CLASSIC_RCU
312
313config CLASSIC_RCU
314 bool "Classic RCU"
315 help
316 This option selects the classic RCU implementation that is
317 designed for best read-side performance on non-realtime
318 systems.
319
320 Select this option if you are unsure.
321
322config TREE_RCU
323 bool "Tree-based hierarchical RCU"
324 help
325 This option selects the RCU implementation that is
326 designed for very large SMP system with hundreds or
327 thousands of CPUs.
328
329config PREEMPT_RCU
330 bool "Preemptible RCU"
331 depends on PREEMPT
332 help
333 This option reduces the latency of the kernel by making certain
334 RCU sections preemptible. Normally RCU code is non-preemptible, if
335 this option is selected then read-only RCU sections become
336 preemptible. This helps latency, but may expose bugs due to
337 now-naive assumptions about each RCU read-side critical section
338 remaining on a given CPU through its execution.
339
340endchoice
341
342config RCU_TRACE
343 bool "Enable tracing for RCU"
344 depends on TREE_RCU || PREEMPT_RCU
345 help
346 This option provides tracing in RCU which presents stats
347 in debugfs for debugging RCU implementation.
348
349 Say Y here if you want to enable RCU tracing
350 Say N if you are unsure.
351
352config RCU_FANOUT
353 int "Tree-based hierarchical RCU fanout value"
354 range 2 64 if 64BIT
355 range 2 32 if !64BIT
356 depends on TREE_RCU
357 default 64 if 64BIT
358 default 32 if !64BIT
359 help
360 This option controls the fanout of hierarchical implementations
361 of RCU, allowing RCU to work efficiently on machines with
362 large numbers of CPUs. This value must be at least the cube
363 root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
364 systems and up to 262,144 for 64-bit systems.
365
366 Select a specific number if testing RCU itself.
367 Take the default if unsure.
368
369config RCU_FANOUT_EXACT
370 bool "Disable tree-based hierarchical RCU auto-balancing"
371 depends on TREE_RCU
372 default n
373 help
374 This option forces use of the exact RCU_FANOUT value specified,
375 regardless of imbalances in the hierarchy. This is useful for
376 testing RCU itself, and might one day be useful on systems with
377 strong NUMA behavior.
378
379 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
380
381 Say N if unsure.
382
383config TREE_RCU_TRACE
384 def_bool RCU_TRACE && TREE_RCU
385 select DEBUG_FS
386 help
387 This option provides tracing for the TREE_RCU implementation,
388 permitting Makefile to trivially select kernel/rcutree_trace.c.
389
390config PREEMPT_RCU_TRACE
391 def_bool RCU_TRACE && PREEMPT_RCU
392 select DEBUG_FS
393 help
394 This option provides tracing for the PREEMPT_RCU implementation,
395 permitting Makefile to trivially select kernel/rcupreempt_trace.c.
396
397endmenu # "RCU Subsystem"
398
1da177e4 399config IKCONFIG
f2443ab6 400 tristate "Kernel .config support"
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401 ---help---
402 This option enables the complete Linux kernel ".config" file
403 contents to be saved in the kernel. It provides documentation
404 of which kernel options are used in a running kernel or in an
405 on-disk kernel. This information can be extracted from the kernel
406 image file with the script scripts/extract-ikconfig and used as
407 input to rebuild the current kernel or to build another kernel.
408 It can also be extracted from a running kernel by reading
409 /proc/config.gz if enabled (below).
410
411config IKCONFIG_PROC
412 bool "Enable access to .config through /proc/config.gz"
413 depends on IKCONFIG && PROC_FS
414 ---help---
415 This option enables access to the kernel configuration file
416 through /proc/config.gz.
417
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418config LOG_BUF_SHIFT
419 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
420 range 12 21
f17a32e9 421 default 17
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422 help
423 Select kernel log buffer size as a power of 2.
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424 Examples:
425 17 => 128 KB
426 16 => 64 KB
427 15 => 32 KB
428 14 => 16 KB
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429 13 => 8 KB
430 12 => 4 KB
431
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432#
433# Architectures with an unreliable sched_clock() should select this:
434#
435config HAVE_UNSTABLE_SCHED_CLOCK
436 bool
437
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438config GROUP_SCHED
439 bool "Group CPU scheduler"
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440 depends on EXPERIMENTAL
441 default n
29f59db3 442 help
fb615581 443 This feature lets CPU scheduler recognize task groups and control CPU
9b5b7751 444 bandwidth allocation to such task groups.
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445 In order to create a group from arbitrary set of processes, use
446 CONFIG_CGROUPS. (See Control Group support.)
29f59db3 447
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448config FAIR_GROUP_SCHED
449 bool "Group scheduling for SCHED_OTHER"
450 depends on GROUP_SCHED
aac6abca 451 default GROUP_SCHED
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452
453config RT_GROUP_SCHED
454 bool "Group scheduling for SCHED_RR/FIFO"
455 depends on EXPERIMENTAL
456 depends on GROUP_SCHED
457 default n
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458 help
459 This feature lets you explicitly allocate real CPU bandwidth
460 to users or control groups (depending on the "Basis for grouping tasks"
461 setting below. If enabled, it will also make it impossible to
462 schedule realtime tasks for non-root users until you allocate
463 realtime bandwidth for them.
2fe401e3 464 See Documentation/scheduler/sched-rt-group.txt for more information.
052f1dc7 465
24e377a8 466choice
052f1dc7 467 depends on GROUP_SCHED
24e377a8 468 prompt "Basis for grouping tasks"
052f1dc7 469 default USER_SCHED
24e377a8 470
052f1dc7 471config USER_SCHED
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472 bool "user id"
473 help
474 This option will choose userid as the basis for grouping
475 tasks, thus providing equal CPU bandwidth to each user.
24e377a8 476
052f1dc7 477config CGROUP_SCHED
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478 bool "Control groups"
479 depends on CGROUPS
480 help
481 This option allows you to create arbitrary task groups
482 using the "cgroup" pseudo filesystem and control
483 the cpu bandwidth allocated to each such task group.
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484 Refer to Documentation/cgroups/cgroups.txt for more
485 information on "cgroup" pseudo filesystem.
68318b8e 486
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487endchoice
488
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489menuconfig CGROUPS
490 boolean "Control Group support"
5cdc38f9 491 help
23964d2d 492 This option adds support for grouping sets of processes together, for
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493 use with process control subsystems such as Cpusets, CFS, memory
494 controls or device isolation.
495 See
5cdc38f9 496 - Documentation/scheduler/sched-design-CFS.txt (CFS)
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497 - Documentation/cgroups/ (features for grouping, isolation
498 and resource control)
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499
500 Say N if unsure.
501
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502if CGROUPS
503
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504config CGROUP_DEBUG
505 bool "Example debug cgroup subsystem"
506 depends on CGROUPS
507 default n
508 help
509 This option enables a simple cgroup subsystem that
510 exports useful debugging information about the cgroups
23964d2d 511 framework.
5cdc38f9 512
23964d2d 513 Say N if unsure.
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514
515config CGROUP_NS
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516 bool "Namespace cgroup subsystem"
517 depends on CGROUPS
518 help
519 Provides a simple namespace cgroup subsystem to
520 provide hierarchical naming of sets of namespaces,
521 for instance virtual servers and checkpoint/restart
522 jobs.
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523
524config CGROUP_FREEZER
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525 bool "Freezer cgroup subsystem"
526 depends on CGROUPS
527 help
528 Provides a way to freeze and unfreeze all tasks in a
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529 cgroup.
530
531config CGROUP_DEVICE
532 bool "Device controller for cgroups"
533 depends on CGROUPS && EXPERIMENTAL
534 help
535 Provides a cgroup implementing whitelists for devices which
536 a process in the cgroup can mknod or open.
537
538config CPUSETS
539 bool "Cpuset support"
db7f47cf 540 depends on CGROUPS
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541 help
542 This option will let you create and manage CPUSETs which
543 allow dynamically partitioning a system into sets of CPUs and
544 Memory Nodes and assigning tasks to run only within those sets.
545 This is primarily useful on large SMP or NUMA systems.
546
547 Say N if unsure.
548
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549config PROC_PID_CPUSET
550 bool "Include legacy /proc/<pid>/cpuset file"
551 depends on CPUSETS
552 default y
553
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554config CGROUP_CPUACCT
555 bool "Simple CPU accounting cgroup subsystem"
556 depends on CGROUPS
557 help
558 Provides a simple Resource Controller for monitoring the
23964d2d 559 total CPU consumed by the tasks in a cgroup.
d842de87 560
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561config RESOURCE_COUNTERS
562 bool "Resource counters"
563 help
564 This option enables controller independent resource accounting
23964d2d 565 infrastructure that works with cgroups.
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566 depends on CGROUPS
567
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568config CGROUP_MEM_RES_CTLR
569 bool "Memory Resource Controller for Control Groups"
570 depends on CGROUPS && RESOURCE_COUNTERS
cf475ad2 571 select MM_OWNER
00f0b825 572 help
84ad6d70 573 Provides a memory resource controller that manages both anonymous
21acb9ca 574 memory and page cache. (See Documentation/cgroups/memory.txt)
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575
576 Note that setting this option increases fixed memory overhead
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577 associated with each page of memory in the system. By this,
578 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
579 usage tracking struct at boot. Total amount of this is printed out
580 at boot.
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581
582 Only enable when you're ok with these trade offs and really
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583 sure you need the memory resource controller. Even when you enable
584 this, you can set "cgroup_disable=memory" at your boot option to
585 disable memory resource controller and you can avoid overheads.
c9d5409f 586 (and lose benefits of memory resource controller)
00f0b825 587
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588 This config option also selects MM_OWNER config option, which
589 could in turn add some fork/exit overhead.
590
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591config CGROUP_MEM_RES_CTLR_SWAP
592 bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)"
593 depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL
594 help
595 Add swap management feature to memory resource controller. When you
596 enable this, you can limit mem+swap usage per cgroup. In other words,
597 when you disable this, memory resource controller has no cares to
598 usage of swap...a process can exhaust all of the swap. This extension
599 is useful when you want to avoid exhaustion swap but this itself
600 adds more overheads and consumes memory for remembering information.
601 Especially if you use 32bit system or small memory system, please
602 be careful about enabling this. When memory resource controller
603 is disabled by boot option, this will be automatically disabled and
604 there will be no overhead from this. Even when you set this config=y,
605 if boot option "noswapaccount" is set, swap will not be accounted.
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606 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
607 size is 4096bytes, 512k per 1Gbytes of swap.
c077719b 608
23964d2d 609endif # CGROUPS
c077719b 610
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611config MM_OWNER
612 bool
5cdc38f9 613
88a22c98 614config SYSFS_DEPRECATED
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615 bool
616
617config SYSFS_DEPRECATED_V2
fce3e804 618 bool "Create deprecated sysfs layout for older userspace tools"
9148fe87 619 depends on SYSFS
88a22c98 620 default y
d47846c5 621 select SYSFS_DEPRECATED
88a22c98 622 help
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623 This option switches the layout of sysfs to the deprecated
624 version.
625
626 The current sysfs layout features a unified device tree at
627 /sys/devices/, which is able to express a hierarchy between
628 class devices. If the deprecated option is set to Y, the
629 unified device tree is split into a bus device tree at
630 /sys/devices/ and several individual class device trees at
631 /sys/class/. The class and bus devices will be connected by
632 "<subsystem>:<name>" and the "device" links. The "block"
633 class devices, will not show up in /sys/class/block/. Some
634 subsystems will suppress the creation of some devices which
635 depend on the unified device tree.
636
637 This option is not a pure compatibility option that can
638 be safely enabled on newer distributions. It will change the
639 layout of sysfs to the non-extensible deprecated version,
640 and disable some features, which can not be exported without
641 confusing older userspace tools. Since 2007/2008 all major
642 distributions do not enable this option, and ship no tools which
643 depend on the deprecated layout or this option.
644
645 If you are using a new kernel on an older distribution, or use
646 older userspace tools, you might need to say Y here. Do not say Y,
647 if the original kernel, that came with your distribution, has
648 this option set to N.
88a22c98 649
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650config RELAY
651 bool "Kernel->user space relay support (formerly relayfs)"
652 help
653 This option enables support for relay interface support in
654 certain file systems (such as debugfs).
655 It is designed to provide an efficient mechanism for tools and
656 facilities to relay large amounts of data from kernel space to
657 user space.
658
659 If unsure, say N.
660
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661config NAMESPACES
662 bool "Namespaces support" if EMBEDDED
663 default !EMBEDDED
664 help
665 Provides the way to make tasks work with different objects using
666 the same id. For example same IPC id may refer to different objects
667 or same user id or pid may refer to different tasks when used in
668 different namespaces.
669
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670config UTS_NS
671 bool "UTS namespace"
672 depends on NAMESPACES
673 help
674 In this namespace tasks see different info provided with the
675 uname() system call
676
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677config IPC_NS
678 bool "IPC namespace"
614b84cf 679 depends on NAMESPACES && (SYSVIPC || POSIX_MQUEUE)
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680 help
681 In this namespace tasks work with IPC ids which correspond to
614b84cf 682 different IPC objects in different namespaces.
ae5e1b22 683
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684config USER_NS
685 bool "User namespace (EXPERIMENTAL)"
686 depends on NAMESPACES && EXPERIMENTAL
687 help
688 This allows containers, i.e. vservers, to use user namespaces
689 to provide different user info for different servers.
690 If unsure, say N.
691
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692config PID_NS
693 bool "PID Namespaces (EXPERIMENTAL)"
694 default n
695 depends on NAMESPACES && EXPERIMENTAL
696 help
12d2b8f9 697 Support process id namespaces. This allows having multiple
692105b8 698 processes with the same pid as long as they are in different
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699 pid namespaces. This is a building block of containers.
700
701 Unless you want to work with an experimental feature
702 say N here.
703
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704config NET_NS
705 bool "Network namespace"
706 default n
707 depends on NAMESPACES && EXPERIMENTAL && NET
708 help
709 Allow user space to create what appear to be multiple instances
710 of the network stack.
711
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712config BLK_DEV_INITRD
713 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
714 depends on BROKEN || !FRV
715 help
716 The initial RAM filesystem is a ramfs which is loaded by the
717 boot loader (loadlin or lilo) and that is mounted as root
718 before the normal boot procedure. It is typically used to
719 load modules needed to mount the "real" root file system,
720 etc. See <file:Documentation/initrd.txt> for details.
721
722 If RAM disk support (BLK_DEV_RAM) is also included, this
723 also enables initial RAM disk (initrd) support and adds
724 15 Kbytes (more on some other architectures) to the kernel size.
725
726 If unsure say Y.
727
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728if BLK_DEV_INITRD
729
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730source "usr/Kconfig"
731
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732endif
733
c45b4f1f 734config CC_OPTIMIZE_FOR_SIZE
96fffeb4 735 bool "Optimize for size"
c45b4f1f 736 default y
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737 help
738 Enabling this option will pass "-Os" instead of "-O2" to gcc
739 resulting in a smaller kernel.
740
775a7229 741 If unsure, say Y.
c45b4f1f 742
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743config SYSCTL
744 bool
745
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746config ANON_INODES
747 bool
748
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749menuconfig EMBEDDED
750 bool "Configure standard kernel features (for small systems)"
751 help
752 This option allows certain base kernel options and settings
753 to be disabled or tweaked. This is for specialized
754 environments which can tolerate a "non-standard" kernel.
755 Only use this if you really know what you are doing.
756
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757config UID16
758 bool "Enable 16-bit UID system calls" if EMBEDDED
09337f50 759 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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760 default y
761 help
762 This enables the legacy 16-bit UID syscall wrappers.
763
b89a8171 764config SYSCTL_SYSCALL
0847062a 765 bool "Sysctl syscall support" if EMBEDDED
13bb7e37 766 default y
b89a8171 767 select SYSCTL
ae81f9e3 768 ---help---
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EB
769 sys_sysctl uses binary paths that have been found challenging
770 to properly maintain and use. The interface in /proc/sys
771 using paths with ascii names is now the primary path to this
772 information.
b89a8171 773
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774 Almost nothing using the binary sysctl interface so if you are
775 trying to save some space it is probably safe to disable this,
776 making your kernel marginally smaller.
b89a8171 777
13bb7e37 778 If unsure say Y here.
ae81f9e3 779
1da177e4 780config KALLSYMS
979c6a1e 781 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
1da177e4
LT
782 default y
783 help
784 Say Y here to let the kernel print out symbolic crash information and
785 symbolic stack backtraces. This increases the size of the kernel
786 somewhat, as all symbols have to be loaded into the kernel image.
787
788config KALLSYMS_ALL
789 bool "Include all symbols in kallsyms"
790 depends on DEBUG_KERNEL && KALLSYMS
791 help
792 Normally kallsyms only contains the symbols of functions, for nicer
793 OOPS messages. Some debuggers can use kallsyms for other
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JJ
794 symbols too: say Y here to include all symbols, if you need them
795 and you don't care about adding 300k to the size of your kernel.
1da177e4
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796
797 Say N.
798
799config KALLSYMS_EXTRA_PASS
800 bool "Do an extra kallsyms pass"
801 depends on KALLSYMS
802 help
803 If kallsyms is not working correctly, the build will fail with
804 inconsistent kallsyms data. If that occurs, log a bug report and
805 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
806 Always say N here unless you find a bug in kallsyms, which must be
807 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
808 you wait for kallsyms to be fixed.
809
d59745ce 810
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811config STRIP_ASM_SYMS
812 bool "Strip assembler-generated symbols during link"
813 default n
814 help
815 Strip internal assembler-generated symbols during a link (symbols
816 that look like '.Lxxx') so they don't pollute the output of
817 get_wchan() and suchlike.
818
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819config HOTPLUG
820 bool "Support for hot-pluggable devices" if EMBEDDED
821 default y
822 help
823 This option is provided for the case where no hotplug or uevent
824 capabilities is wanted by the kernel. You should only consider
825 disabling this option for embedded systems that do not use modules, a
826 dynamic /dev tree, or dynamic device discovery. Just say Y.
827
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MM
828config PRINTK
829 default y
830 bool "Enable support for printk" if EMBEDDED
831 help
832 This option enables normal printk support. Removing it
833 eliminates most of the message strings from the kernel image
834 and makes the kernel more or less silent. As this makes it
835 very difficult to diagnose system problems, saying N here is
836 strongly discouraged.
837
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838config BUG
839 bool "BUG() support" if EMBEDDED
840 default y
841 help
842 Disabling this option eliminates support for BUG and WARN, reducing
843 the size of your kernel image and potentially quietly ignoring
844 numerous fatal conditions. You should only consider disabling this
845 option for embedded systems with no facilities for reporting errors.
846 Just say Y.
847
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MM
848config ELF_CORE
849 default y
850 bool "Enable ELF core dumps" if EMBEDDED
851 help
852 Enable support for generating core dumps. Disabling saves about 4k.
853
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SS
854config PCSPKR_PLATFORM
855 bool "Enable PC-Speaker support" if EMBEDDED
856 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
857 default y
858 help
859 This option allows to disable the internal PC-Speaker
860 support, saving some memory.
861
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LT
862config BASE_FULL
863 default y
864 bool "Enable full-sized data structures for core" if EMBEDDED
865 help
866 Disabling this option reduces the size of miscellaneous core
867 kernel data structures. This saves memory on small machines,
868 but may reduce performance.
869
870config FUTEX
871 bool "Enable futex support" if EMBEDDED
872 default y
23f78d4a 873 select RT_MUTEXES
1da177e4
LT
874 help
875 Disabling this option will cause the kernel to be built without
876 support for "fast userspace mutexes". The resulting kernel may not
877 run glibc-based applications correctly.
878
879config EPOLL
880 bool "Enable eventpoll support" if EMBEDDED
881 default y
448e3cee 882 select ANON_INODES
1da177e4
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883 help
884 Disabling this option will cause the kernel to be built without
885 support for epoll family of system calls.
886
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DL
887config SIGNALFD
888 bool "Enable signalfd() system call" if EMBEDDED
448e3cee 889 select ANON_INODES
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DL
890 default y
891 help
892 Enable the signalfd() system call that allows to receive signals
893 on a file descriptor.
894
895 If unsure, say Y.
896
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897config TIMERFD
898 bool "Enable timerfd() system call" if EMBEDDED
448e3cee 899 select ANON_INODES
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900 default y
901 help
902 Enable the timerfd() system call that allows to receive timer
903 events on a file descriptor.
904
905 If unsure, say Y.
906
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907config EVENTFD
908 bool "Enable eventfd() system call" if EMBEDDED
448e3cee 909 select ANON_INODES
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910 default y
911 help
912 Enable the eventfd() system call that allows to receive both
913 kernel notification (ie. KAIO) or userspace notifications.
914
915 If unsure, say Y.
916
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LT
917config SHMEM
918 bool "Use full shmem filesystem" if EMBEDDED
919 default y
920 depends on MMU
921 help
922 The shmem is an internal filesystem used to manage shared memory.
923 It is backed by swap and manages resource limits. It is also exported
924 to userspace as tmpfs if TMPFS is enabled. Disabling this
925 option replaces shmem and tmpfs with the much simpler ramfs code,
926 which may be appropriate on small systems without swap.
927
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928config AIO
929 bool "Enable AIO support" if EMBEDDED
930 default y
931 help
932 This option enables POSIX asynchronous I/O which may by used
933 by some high performance threaded applications. Disabling
934 this option saves about 7k.
935
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936config VM_EVENT_COUNTERS
937 default y
938 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
939 help
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PJ
940 VM event counters are needed for event counts to be shown.
941 This option allows the disabling of the VM event counters
942 on EMBEDDED systems. /proc/vmstat will only show page counts
943 if VM event counters are disabled.
f8891e5e 944
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TP
945config PCI_QUIRKS
946 default y
61cfc7e4
GU
947 bool "Enable PCI quirk workarounds" if EMBEDDED
948 depends on PCI
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TP
949 help
950 This enables workarounds for various PCI chipset
951 bugs/quirks. Disable this only if your target machine is
952 unaffected by PCI quirks.
953
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CL
954config SLUB_DEBUG
955 default y
956 bool "Enable SLUB debugging support" if EMBEDDED
f6acb635 957 depends on SLUB && SYSFS
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CL
958 help
959 SLUB has extensive debug support features. Disabling these can
960 result in significant savings in code size. This also disables
961 SLUB sysfs support. /sys/slab will not exist and there will be
962 no support for cache validation etc.
963
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964config COMPAT_BRK
965 bool "Disable heap randomization"
966 default y
967 help
968 Randomizing heap placement makes heap exploits harder, but it
969 also breaks ancient binaries (including anything libc5 based).
970 This option changes the bootup default to heap randomization
692105b8 971 disabled, and can be overridden at runtime by setting
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RD
972 /proc/sys/kernel/randomize_va_space to 2.
973
974 On non-ancient distros (post-2000 ones) N is usually a safe choice.
975
81819f0f
CL
976choice
977 prompt "Choose SLAB allocator"
a0acd820 978 default SLUB
81819f0f
CL
979 help
980 This option allows to select a slab allocator.
981
982config SLAB
983 bool "SLAB"
984 help
985 The regular slab allocator that is established and known to work
34013886 986 well in all environments. It organizes cache hot objects in
02f56210 987 per cpu and per node queues.
81819f0f
CL
988
989config SLUB
81819f0f
CL
990 bool "SLUB (Unqueued Allocator)"
991 help
992 SLUB is a slab allocator that minimizes cache line usage
993 instead of managing queues of cached objects (SLAB approach).
994 Per cpu caching is realized using slabs of objects instead
995 of queues of objects. SLUB can use memory efficiently
02f56210
SA
996 and has enhanced diagnostics. SLUB is the default choice for
997 a slab allocator.
81819f0f
CL
998
999config SLOB
84a01c2f 1000 depends on EMBEDDED
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CL
1001 bool "SLOB (Simple Allocator)"
1002 help
37291458
MM
1003 SLOB replaces the stock allocator with a drastically simpler
1004 allocator. SLOB is generally more space efficient but
1005 does not perform as well on large systems.
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CL
1006
1007endchoice
1008
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MD
1009config PROFILING
1010 bool "Profiling support (EXPERIMENTAL)"
1011 help
1012 Say Y here to enable the extended profiling support mechanisms used
1013 by profilers such as OProfile.
1014
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IM
1015#
1016# Place an empty function call at each tracepoint site. Can be
1017# dynamically changed for a probe function.
1018#
97e1c18e 1019config TRACEPOINTS
5f87f112 1020 bool
97e1c18e 1021
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MD
1022config MARKERS
1023 bool "Activate markers"
91f73f90 1024 select TRACEPOINTS
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MD
1025 help
1026 Place an empty function call at each marker site. Can be
1027 dynamically changed for a probe function.
1028
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MD
1029source "arch/Kconfig"
1030
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DH
1031config SLOW_WORK
1032 default n
1c2d008c 1033 bool
07fe7cb7
DH
1034 help
1035 The slow work thread pool provides a number of dynamically allocated
1036 threads that can be used by the kernel to perform operations that
1037 take a relatively long time.
1038
1039 An example of this would be CacheFiles doing a path lookup followed
1040 by a series of mkdirs and a create call, all of which have to touch
1041 disk.
1042
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DH
1043 See Documentation/slow-work.txt.
1044
1da177e4
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1045endmenu # General setup
1046
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DES
1047config HAVE_GENERIC_DMA_COHERENT
1048 bool
1049 default n
1050
158a9624
LT
1051config SLABINFO
1052 bool
1053 depends on PROC_FS
0f389ec6 1054 depends on SLAB || SLUB_DEBUG
158a9624
LT
1055 default y
1056
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CE
1057config RT_MUTEXES
1058 boolean
ae81f9e3 1059
1da177e4
LT
1060config BASE_SMALL
1061 int
1062 default 0 if BASE_FULL
1063 default 1 if !BASE_FULL
1064
66da5733 1065menuconfig MODULES
1da177e4
LT
1066 bool "Enable loadable module support"
1067 help
1068 Kernel modules are small pieces of compiled code which can
1069 be inserted in the running kernel, rather than being
1070 permanently built into the kernel. You use the "modprobe"
1071 tool to add (and sometimes remove) them. If you say Y here,
1072 many parts of the kernel can be built as modules (by
1073 answering M instead of Y where indicated): this is most
1074 useful for infrequently used options which are not required
1075 for booting. For more information, see the man pages for
1076 modprobe, lsmod, modinfo, insmod and rmmod.
1077
1078 If you say Y here, you will need to run "make
1079 modules_install" to put the modules under /lib/modules/
1080 where modprobe can find them (you may need to be root to do
1081 this).
1082
1083 If unsure, say Y.
1084
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RD
1085if MODULES
1086
826e4506
LT
1087config MODULE_FORCE_LOAD
1088 bool "Forced module loading"
826e4506
LT
1089 default n
1090 help
91e37a79
RR
1091 Allow loading of modules without version information (ie. modprobe
1092 --force). Forced module loading sets the 'F' (forced) taint flag and
1093 is usually a really bad idea.
826e4506 1094
1da177e4
LT
1095config MODULE_UNLOAD
1096 bool "Module unloading"
1da177e4
LT
1097 help
1098 Without this option you will not be able to unload any
1099 modules (note that some modules may not be unloadable
f7f5b675
DV
1100 anyway), which makes your kernel smaller, faster
1101 and simpler. If unsure, say Y.
1da177e4
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1102
1103config MODULE_FORCE_UNLOAD
1104 bool "Forced module unloading"
1105 depends on MODULE_UNLOAD && EXPERIMENTAL
1106 help
1107 This option allows you to force a module to unload, even if the
1108 kernel believes it is unsafe: the kernel will remove the module
1109 without waiting for anyone to stop using it (using the -f option to
1110 rmmod). This is mainly for kernel developers and desperate users.
1111 If unsure, say N.
1112
1da177e4 1113config MODVERSIONS
0d541643 1114 bool "Module versioning support"
1da177e4
LT
1115 help
1116 Usually, you have to use modules compiled with your kernel.
1117 Saying Y here makes it sometimes possible to use modules
1118 compiled for different kernels, by adding enough information
1119 to the modules to (hopefully) spot any changes which would
1120 make them incompatible with the kernel you are running. If
1121 unsure, say N.
1122
1123config MODULE_SRCVERSION_ALL
1124 bool "Source checksum for all modules"
1da177e4
LT
1125 help
1126 Modules which contain a MODULE_VERSION get an extra "srcversion"
1127 field inserted into their modinfo section, which contains a
1128 sum of the source files which made it. This helps maintainers
1129 see exactly which source was used to build a module (since
1130 others sometimes change the module source without updating
1131 the version). With this option, such a "srcversion" field
1132 will be created for all modules. If unsure, say N.
1133
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RD
1134endif # MODULES
1135
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RR
1136config INIT_ALL_POSSIBLE
1137 bool
1138 help
1139 Back when each arch used to define their own cpu_online_map and
1140 cpu_possible_map, some of them chose to initialize cpu_possible_map
1141 with all 1s, and others with all 0s. When they were centralised,
1142 it was better to provide this option than to break all the archs
692105b8 1143 and have several arch maintainers pursuing me down dark alleys.
98a79d6a 1144
1da177e4
LT
1145config STOP_MACHINE
1146 bool
1147 default y
1148 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1149 help
1150 Need stop_machine() primitive.
3a65dfe8 1151
3a65dfe8 1152source "block/Kconfig"
e98c3202
AK
1153
1154config PREEMPT_NOTIFIERS
1155 bool
e260be67 1156