perf_counter: Rename 'event' to event_id/hw_event
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / init / Kconfig
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1config ARCH
2 string
3 option env="ARCH"
4
5config KERNELVERSION
6 string
7 option env="KERNELVERSION"
8
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9config DEFCONFIG_LIST
10 string
b2670eac 11 depends on !UML
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12 option defconfig_list
13 default "/lib/modules/$UNAME_RELEASE/.config"
14 default "/etc/kernel-config"
15 default "/boot/config-$UNAME_RELEASE"
73531905 16 default "$ARCH_DEFCONFIG"
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17 default "arch/$ARCH/defconfig"
18
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19config CONSTRUCTORS
20 bool
21 depends on !UML
22 default y
23
ff0cfc66 24menu "General setup"
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25
26config EXPERIMENTAL
27 bool "Prompt for development and/or incomplete code/drivers"
28 ---help---
29 Some of the various things that Linux supports (such as network
30 drivers, file systems, network protocols, etc.) can be in a state
31 of development where the functionality, stability, or the level of
32 testing is not yet high enough for general use. This is usually
33 known as the "alpha-test" phase among developers. If a feature is
34 currently in alpha-test, then the developers usually discourage
35 uninformed widespread use of this feature by the general public to
36 avoid "Why doesn't this work?" type mail messages. However, active
37 testing and use of these systems is welcomed. Just be aware that it
38 may not meet the normal level of reliability or it may fail to work
39 in some special cases. Detailed bug reports from people familiar
40 with the kernel internals are usually welcomed by the developers
41 (before submitting bug reports, please read the documents
42 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
43 <file:Documentation/BUG-HUNTING>, and
44 <file:Documentation/oops-tracing.txt> in the kernel source).
45
46 This option will also make obsoleted drivers available. These are
47 drivers that have been replaced by something else, and/or are
48 scheduled to be removed in a future kernel release.
49
50 Unless you intend to help test and develop a feature or driver that
51 falls into this category, or you have a situation that requires
52 using these features, you should probably say N here, which will
53 cause the configurator to present you with fewer choices. If
54 you say Y here, you will be offered the choice of using features or
55 drivers that are currently considered to be in the alpha-test phase.
56
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57config BROKEN
58 bool
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59
60config BROKEN_ON_SMP
61 bool
62 depends on BROKEN || !SMP
63 default y
64
65config LOCK_KERNEL
66 bool
67 depends on SMP || PREEMPT
68 default y
69
70config INIT_ENV_ARG_LIMIT
71 int
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72 default 32 if !UML
73 default 128 if UML
1da177e4 74 help
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75 Maximum of each of the number of arguments and environment
76 variables passed to init from the kernel command line.
1da177e4 77
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78
79config LOCALVERSION
80 string "Local version - append to kernel release"
81 help
82 Append an extra string to the end of your kernel version.
83 This will show up when you type uname, for example.
84 The string you set here will be appended after the contents of
85 any files with a filename matching localversion* in your
86 object and source tree, in that order. Your total string can
87 be a maximum of 64 characters.
88
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89config LOCALVERSION_AUTO
90 bool "Automatically append version information to the version string"
91 default y
92 help
93 This will try to automatically determine if the current tree is a
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94 release tree by looking for git tags that belong to the current
95 top of tree revision.
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96
97 A string of the format -gxxxxxxxx will be added to the localversion
6e5a5420 98 if a git-based tree is found. The string generated by this will be
aaebf433 99 appended after any matching localversion* files, and after the value
6e5a5420 100 set in CONFIG_LOCALVERSION.
aaebf433 101
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102 (The actual string used here is the first eight characters produced
103 by running the command:
104
105 $ git rev-parse --verify HEAD
106
107 which is done within the script "scripts/setlocalversion".)
aaebf433 108
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109config HAVE_KERNEL_GZIP
110 bool
111
112config HAVE_KERNEL_BZIP2
113 bool
114
115config HAVE_KERNEL_LZMA
116 bool
117
30d65dbf 118choice
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119 prompt "Kernel compression mode"
120 default KERNEL_GZIP
121 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA
122 help
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123 The linux kernel is a kind of self-extracting executable.
124 Several compression algorithms are available, which differ
125 in efficiency, compression and decompression speed.
126 Compression speed is only relevant when building a kernel.
127 Decompression speed is relevant at each boot.
128
129 If you have any problems with bzip2 or lzma compressed
130 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
131 version of this functionality (bzip2 only), for 2.4, was
132 supplied by Christian Ludwig)
133
134 High compression options are mostly useful for users, who
135 are low on disk space (embedded systems), but for whom ram
136 size matters less.
137
138 If in doubt, select 'gzip'
139
140config KERNEL_GZIP
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141 bool "Gzip"
142 depends on HAVE_KERNEL_GZIP
143 help
144 The old and tried gzip compression. Its compression ratio is
145 the poorest among the 3 choices; however its speed (both
146 compression and decompression) is the fastest.
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147
148config KERNEL_BZIP2
149 bool "Bzip2"
2e9f3bdd 150 depends on HAVE_KERNEL_BZIP2
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151 help
152 Its compression ratio and speed is intermediate.
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153 Decompression speed is slowest among the three. The kernel
154 size is about 10% smaller with bzip2, in comparison to gzip.
155 Bzip2 uses a large amount of memory. For modern kernels you
156 will need at least 8MB RAM or more for booting.
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157
158config KERNEL_LZMA
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159 bool "LZMA"
160 depends on HAVE_KERNEL_LZMA
161 help
162 The most recent compression algorithm.
163 Its ratio is best, decompression speed is between the other
164 two. Compression is slowest. The kernel size is about 33%
165 smaller with LZMA in comparison to gzip.
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166
167endchoice
168
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169config SWAP
170 bool "Support for paging of anonymous memory (swap)"
9361401e 171 depends on MMU && BLOCK
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172 default y
173 help
174 This option allows you to choose whether you want to have support
92c3504e 175 for so called swap devices or swap files in your kernel that are
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176 used to provide more virtual memory than the actual RAM present
177 in your computer. If unsure say Y.
178
179config SYSVIPC
180 bool "System V IPC"
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181 ---help---
182 Inter Process Communication is a suite of library functions and
183 system calls which let processes (running programs) synchronize and
184 exchange information. It is generally considered to be a good thing,
185 and some programs won't run unless you say Y here. In particular, if
186 you want to run the DOS emulator dosemu under Linux (read the
187 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
188 you'll need to say Y here.
189
190 You can find documentation about IPC with "info ipc" and also in
191 section 6.4 of the Linux Programmer's Guide, available from
192 <http://www.tldp.org/guides.html>.
193
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194config SYSVIPC_SYSCTL
195 bool
196 depends on SYSVIPC
197 depends on SYSCTL
198 default y
199
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200config POSIX_MQUEUE
201 bool "POSIX Message Queues"
202 depends on NET && EXPERIMENTAL
203 ---help---
204 POSIX variant of message queues is a part of IPC. In POSIX message
205 queues every message has a priority which decides about succession
206 of receiving it by a process. If you want to compile and run
207 programs written e.g. for Solaris with use of its POSIX message
b0e37650 208 queues (functions mq_*) say Y here.
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209
210 POSIX message queues are visible as a filesystem called 'mqueue'
211 and can be mounted somewhere if you want to do filesystem
212 operations on message queues.
213
214 If unsure, say Y.
215
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216config POSIX_MQUEUE_SYSCTL
217 bool
218 depends on POSIX_MQUEUE
219 depends on SYSCTL
220 default y
221
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222config BSD_PROCESS_ACCT
223 bool "BSD Process Accounting"
224 help
225 If you say Y here, a user level program will be able to instruct the
226 kernel (via a special system call) to write process accounting
227 information to a file: whenever a process exits, information about
228 that process will be appended to the file by the kernel. The
229 information includes things such as creation time, owning user,
230 command name, memory usage, controlling terminal etc. (the complete
231 list is in the struct acct in <file:include/linux/acct.h>). It is
232 up to the user level program to do useful things with this
233 information. This is generally a good idea, so say Y.
234
235config BSD_PROCESS_ACCT_V3
236 bool "BSD Process Accounting version 3 file format"
237 depends on BSD_PROCESS_ACCT
238 default n
239 help
240 If you say Y here, the process accounting information is written
241 in a new file format that also logs the process IDs of each
242 process and it's parent. Note that this file format is incompatible
243 with previous v0/v1/v2 file formats, so you will need updated tools
244 for processing it. A preliminary version of these tools is available
37a4c940 245 at <http://www.gnu.org/software/acct/>.
1da177e4 246
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247config TASKSTATS
248 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
249 depends on NET
250 default n
251 help
252 Export selected statistics for tasks/processes through the
253 generic netlink interface. Unlike BSD process accounting, the
254 statistics are available during the lifetime of tasks/processes as
255 responses to commands. Like BSD accounting, they are sent to user
256 space on task exit.
257
258 Say N if unsure.
259
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260config TASK_DELAY_ACCT
261 bool "Enable per-task delay accounting (EXPERIMENTAL)"
6f44993f 262 depends on TASKSTATS
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263 help
264 Collect information on time spent by a task waiting for system
265 resources like cpu, synchronous block I/O completion and swapping
266 in pages. Such statistics can help in setting a task's priorities
267 relative to other tasks for cpu, io, rss limits etc.
268
269 Say N if unsure.
270
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271config TASK_XACCT
272 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
273 depends on TASKSTATS
274 help
275 Collect extended task accounting data and send the data
276 to userland for processing over the taskstats interface.
277
278 Say N if unsure.
279
280config TASK_IO_ACCOUNTING
281 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
282 depends on TASK_XACCT
283 help
284 Collect information on the number of bytes of storage I/O which this
285 task has caused.
286
287 Say N if unsure.
288
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289config AUDIT
290 bool "Auditing support"
804a6a49 291 depends on NET
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292 help
293 Enable auditing infrastructure that can be used with another
294 kernel subsystem, such as SELinux (which requires this for
295 logging of avc messages output). Does not do system-call
296 auditing without CONFIG_AUDITSYSCALL.
297
298config AUDITSYSCALL
299 bool "Enable system-call auditing support"
1322b9de 300 depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64|| SUPERH)
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301 default y if SECURITY_SELINUX
302 help
303 Enable low-overhead system-call auditing infrastructure that
304 can be used independently or with another kernel subsystem,
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305 such as SELinux. To use audit's filesystem watch feature, please
306 ensure that INOTIFY is configured.
1da177e4 307
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308config AUDIT_TREE
309 def_bool y
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310 depends on AUDITSYSCALL
311 select INOTIFY
74c3cbe3 312
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313menu "RCU Subsystem"
314
315choice
316 prompt "RCU Implementation"
31c9a24e 317 default TREE_RCU
c903ff83 318
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319config TREE_RCU
320 bool "Tree-based hierarchical RCU"
321 help
322 This option selects the RCU implementation that is
323 designed for very large SMP system with hundreds or
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324 thousands of CPUs. It also scales down nicely to
325 smaller systems.
c903ff83 326
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327config TREE_PREEMPT_RCU
328 bool "Preemptable tree-based hierarchical RCU"
329 depends on PREEMPT
330 help
331 This option selects the RCU implementation that is
332 designed for very large SMP systems with hundreds or
333 thousands of CPUs, but for which real-time response
334 is also required.
335
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336endchoice
337
338config RCU_TRACE
339 bool "Enable tracing for RCU"
6b3ef48a 340 depends on TREE_RCU || TREE_PREEMPT_RCU
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341 help
342 This option provides tracing in RCU which presents stats
343 in debugfs for debugging RCU implementation.
344
345 Say Y here if you want to enable RCU tracing
346 Say N if you are unsure.
347
348config RCU_FANOUT
349 int "Tree-based hierarchical RCU fanout value"
350 range 2 64 if 64BIT
351 range 2 32 if !64BIT
f41d911f 352 depends on TREE_RCU || TREE_PREEMPT_RCU
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353 default 64 if 64BIT
354 default 32 if !64BIT
355 help
356 This option controls the fanout of hierarchical implementations
357 of RCU, allowing RCU to work efficiently on machines with
358 large numbers of CPUs. This value must be at least the cube
359 root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
360 systems and up to 262,144 for 64-bit systems.
361
362 Select a specific number if testing RCU itself.
363 Take the default if unsure.
364
365config RCU_FANOUT_EXACT
366 bool "Disable tree-based hierarchical RCU auto-balancing"
f41d911f 367 depends on TREE_RCU || TREE_PREEMPT_RCU
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368 default n
369 help
370 This option forces use of the exact RCU_FANOUT value specified,
371 regardless of imbalances in the hierarchy. This is useful for
372 testing RCU itself, and might one day be useful on systems with
373 strong NUMA behavior.
374
375 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
376
377 Say N if unsure.
378
379config TREE_RCU_TRACE
f41d911f 380 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
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381 select DEBUG_FS
382 help
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383 This option provides tracing for the TREE_RCU and
384 TREE_PREEMPT_RCU implementations, permitting Makefile to
385 trivially select kernel/rcutree_trace.c.
c903ff83 386
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387endmenu # "RCU Subsystem"
388
1da177e4 389config IKCONFIG
f2443ab6 390 tristate "Kernel .config support"
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391 ---help---
392 This option enables the complete Linux kernel ".config" file
393 contents to be saved in the kernel. It provides documentation
394 of which kernel options are used in a running kernel or in an
395 on-disk kernel. This information can be extracted from the kernel
396 image file with the script scripts/extract-ikconfig and used as
397 input to rebuild the current kernel or to build another kernel.
398 It can also be extracted from a running kernel by reading
399 /proc/config.gz if enabled (below).
400
401config IKCONFIG_PROC
402 bool "Enable access to .config through /proc/config.gz"
403 depends on IKCONFIG && PROC_FS
404 ---help---
405 This option enables access to the kernel configuration file
406 through /proc/config.gz.
407
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408config LOG_BUF_SHIFT
409 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
410 range 12 21
f17a32e9 411 default 17
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412 help
413 Select kernel log buffer size as a power of 2.
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414 Examples:
415 17 => 128 KB
416 16 => 64 KB
417 15 => 32 KB
418 14 => 16 KB
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419 13 => 8 KB
420 12 => 4 KB
421
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422#
423# Architectures with an unreliable sched_clock() should select this:
424#
425config HAVE_UNSTABLE_SCHED_CLOCK
426 bool
427
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428config GROUP_SCHED
429 bool "Group CPU scheduler"
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430 depends on EXPERIMENTAL
431 default n
29f59db3 432 help
fb615581 433 This feature lets CPU scheduler recognize task groups and control CPU
9b5b7751 434 bandwidth allocation to such task groups.
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435 In order to create a group from arbitrary set of processes, use
436 CONFIG_CGROUPS. (See Control Group support.)
29f59db3 437
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438config FAIR_GROUP_SCHED
439 bool "Group scheduling for SCHED_OTHER"
440 depends on GROUP_SCHED
aac6abca 441 default GROUP_SCHED
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442
443config RT_GROUP_SCHED
444 bool "Group scheduling for SCHED_RR/FIFO"
445 depends on EXPERIMENTAL
446 depends on GROUP_SCHED
447 default n
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448 help
449 This feature lets you explicitly allocate real CPU bandwidth
450 to users or control groups (depending on the "Basis for grouping tasks"
451 setting below. If enabled, it will also make it impossible to
452 schedule realtime tasks for non-root users until you allocate
453 realtime bandwidth for them.
2fe401e3 454 See Documentation/scheduler/sched-rt-group.txt for more information.
052f1dc7 455
24e377a8 456choice
052f1dc7 457 depends on GROUP_SCHED
24e377a8 458 prompt "Basis for grouping tasks"
052f1dc7 459 default USER_SCHED
24e377a8 460
052f1dc7 461config USER_SCHED
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462 bool "user id"
463 help
464 This option will choose userid as the basis for grouping
465 tasks, thus providing equal CPU bandwidth to each user.
24e377a8 466
052f1dc7 467config CGROUP_SCHED
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468 bool "Control groups"
469 depends on CGROUPS
470 help
471 This option allows you to create arbitrary task groups
472 using the "cgroup" pseudo filesystem and control
473 the cpu bandwidth allocated to each such task group.
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474 Refer to Documentation/cgroups/cgroups.txt for more
475 information on "cgroup" pseudo filesystem.
68318b8e 476
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477endchoice
478
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479menuconfig CGROUPS
480 boolean "Control Group support"
5cdc38f9 481 help
23964d2d 482 This option adds support for grouping sets of processes together, for
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483 use with process control subsystems such as Cpusets, CFS, memory
484 controls or device isolation.
485 See
5cdc38f9 486 - Documentation/scheduler/sched-design-CFS.txt (CFS)
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487 - Documentation/cgroups/ (features for grouping, isolation
488 and resource control)
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489
490 Say N if unsure.
491
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492if CGROUPS
493
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494config CGROUP_DEBUG
495 bool "Example debug cgroup subsystem"
496 depends on CGROUPS
497 default n
498 help
499 This option enables a simple cgroup subsystem that
500 exports useful debugging information about the cgroups
23964d2d 501 framework.
5cdc38f9 502
23964d2d 503 Say N if unsure.
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504
505config CGROUP_NS
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506 bool "Namespace cgroup subsystem"
507 depends on CGROUPS
508 help
509 Provides a simple namespace cgroup subsystem to
510 provide hierarchical naming of sets of namespaces,
511 for instance virtual servers and checkpoint/restart
512 jobs.
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513
514config CGROUP_FREEZER
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515 bool "Freezer cgroup subsystem"
516 depends on CGROUPS
517 help
518 Provides a way to freeze and unfreeze all tasks in a
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519 cgroup.
520
521config CGROUP_DEVICE
522 bool "Device controller for cgroups"
523 depends on CGROUPS && EXPERIMENTAL
524 help
525 Provides a cgroup implementing whitelists for devices which
526 a process in the cgroup can mknod or open.
527
528config CPUSETS
529 bool "Cpuset support"
db7f47cf 530 depends on CGROUPS
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531 help
532 This option will let you create and manage CPUSETs which
533 allow dynamically partitioning a system into sets of CPUs and
534 Memory Nodes and assigning tasks to run only within those sets.
535 This is primarily useful on large SMP or NUMA systems.
536
537 Say N if unsure.
538
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539config PROC_PID_CPUSET
540 bool "Include legacy /proc/<pid>/cpuset file"
541 depends on CPUSETS
542 default y
543
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544config CGROUP_CPUACCT
545 bool "Simple CPU accounting cgroup subsystem"
546 depends on CGROUPS
547 help
548 Provides a simple Resource Controller for monitoring the
23964d2d 549 total CPU consumed by the tasks in a cgroup.
d842de87 550
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551config RESOURCE_COUNTERS
552 bool "Resource counters"
553 help
554 This option enables controller independent resource accounting
23964d2d 555 infrastructure that works with cgroups.
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556 depends on CGROUPS
557
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558config CGROUP_MEM_RES_CTLR
559 bool "Memory Resource Controller for Control Groups"
560 depends on CGROUPS && RESOURCE_COUNTERS
cf475ad2 561 select MM_OWNER
00f0b825 562 help
84ad6d70 563 Provides a memory resource controller that manages both anonymous
21acb9ca 564 memory and page cache. (See Documentation/cgroups/memory.txt)
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565
566 Note that setting this option increases fixed memory overhead
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567 associated with each page of memory in the system. By this,
568 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
569 usage tracking struct at boot. Total amount of this is printed out
570 at boot.
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571
572 Only enable when you're ok with these trade offs and really
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573 sure you need the memory resource controller. Even when you enable
574 this, you can set "cgroup_disable=memory" at your boot option to
575 disable memory resource controller and you can avoid overheads.
c9d5409f 576 (and lose benefits of memory resource controller)
00f0b825 577
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578 This config option also selects MM_OWNER config option, which
579 could in turn add some fork/exit overhead.
580
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581config CGROUP_MEM_RES_CTLR_SWAP
582 bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)"
583 depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL
584 help
585 Add swap management feature to memory resource controller. When you
586 enable this, you can limit mem+swap usage per cgroup. In other words,
587 when you disable this, memory resource controller has no cares to
588 usage of swap...a process can exhaust all of the swap. This extension
589 is useful when you want to avoid exhaustion swap but this itself
590 adds more overheads and consumes memory for remembering information.
591 Especially if you use 32bit system or small memory system, please
592 be careful about enabling this. When memory resource controller
593 is disabled by boot option, this will be automatically disabled and
594 there will be no overhead from this. Even when you set this config=y,
595 if boot option "noswapaccount" is set, swap will not be accounted.
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596 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
597 size is 4096bytes, 512k per 1Gbytes of swap.
c077719b 598
23964d2d 599endif # CGROUPS
c077719b 600
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601config MM_OWNER
602 bool
5cdc38f9 603
88a22c98 604config SYSFS_DEPRECATED
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605 bool
606
607config SYSFS_DEPRECATED_V2
f6ee649f 608 bool "remove sysfs features which may confuse old userspace tools"
9148fe87 609 depends on SYSFS
f6ee649f 610 default n
d47846c5 611 select SYSFS_DEPRECATED
88a22c98 612 help
fce3e804 613 This option switches the layout of sysfs to the deprecated
f6ee649f 614 version. Do not use it on recent distributions.
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615
616 The current sysfs layout features a unified device tree at
617 /sys/devices/, which is able to express a hierarchy between
618 class devices. If the deprecated option is set to Y, the
619 unified device tree is split into a bus device tree at
620 /sys/devices/ and several individual class device trees at
621 /sys/class/. The class and bus devices will be connected by
622 "<subsystem>:<name>" and the "device" links. The "block"
623 class devices, will not show up in /sys/class/block/. Some
624 subsystems will suppress the creation of some devices which
625 depend on the unified device tree.
626
627 This option is not a pure compatibility option that can
628 be safely enabled on newer distributions. It will change the
629 layout of sysfs to the non-extensible deprecated version,
630 and disable some features, which can not be exported without
631 confusing older userspace tools. Since 2007/2008 all major
632 distributions do not enable this option, and ship no tools which
633 depend on the deprecated layout or this option.
634
635 If you are using a new kernel on an older distribution, or use
636 older userspace tools, you might need to say Y here. Do not say Y,
637 if the original kernel, that came with your distribution, has
638 this option set to N.
88a22c98 639
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640config RELAY
641 bool "Kernel->user space relay support (formerly relayfs)"
642 help
643 This option enables support for relay interface support in
644 certain file systems (such as debugfs).
645 It is designed to provide an efficient mechanism for tools and
646 facilities to relay large amounts of data from kernel space to
647 user space.
648
649 If unsure, say N.
650
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PE
651config NAMESPACES
652 bool "Namespaces support" if EMBEDDED
653 default !EMBEDDED
654 help
655 Provides the way to make tasks work with different objects using
656 the same id. For example same IPC id may refer to different objects
657 or same user id or pid may refer to different tasks when used in
658 different namespaces.
659
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PE
660config UTS_NS
661 bool "UTS namespace"
662 depends on NAMESPACES
663 help
664 In this namespace tasks see different info provided with the
665 uname() system call
666
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PE
667config IPC_NS
668 bool "IPC namespace"
614b84cf 669 depends on NAMESPACES && (SYSVIPC || POSIX_MQUEUE)
ae5e1b22
PE
670 help
671 In this namespace tasks work with IPC ids which correspond to
614b84cf 672 different IPC objects in different namespaces.
ae5e1b22 673
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PE
674config USER_NS
675 bool "User namespace (EXPERIMENTAL)"
676 depends on NAMESPACES && EXPERIMENTAL
677 help
678 This allows containers, i.e. vservers, to use user namespaces
679 to provide different user info for different servers.
680 If unsure, say N.
681
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PE
682config PID_NS
683 bool "PID Namespaces (EXPERIMENTAL)"
684 default n
685 depends on NAMESPACES && EXPERIMENTAL
686 help
12d2b8f9 687 Support process id namespaces. This allows having multiple
692105b8 688 processes with the same pid as long as they are in different
74bd59bb
PE
689 pid namespaces. This is a building block of containers.
690
691 Unless you want to work with an experimental feature
692 say N here.
693
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MH
694config NET_NS
695 bool "Network namespace"
696 default n
697 depends on NAMESPACES && EXPERIMENTAL && NET
698 help
699 Allow user space to create what appear to be multiple instances
700 of the network stack.
701
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DG
702config BLK_DEV_INITRD
703 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
704 depends on BROKEN || !FRV
705 help
706 The initial RAM filesystem is a ramfs which is loaded by the
707 boot loader (loadlin or lilo) and that is mounted as root
708 before the normal boot procedure. It is typically used to
709 load modules needed to mount the "real" root file system,
710 etc. See <file:Documentation/initrd.txt> for details.
711
712 If RAM disk support (BLK_DEV_RAM) is also included, this
713 also enables initial RAM disk (initrd) support and adds
714 15 Kbytes (more on some other architectures) to the kernel size.
715
716 If unsure say Y.
717
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718if BLK_DEV_INITRD
719
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SR
720source "usr/Kconfig"
721
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JPS
722endif
723
c45b4f1f 724config CC_OPTIMIZE_FOR_SIZE
96fffeb4 725 bool "Optimize for size"
c45b4f1f 726 default y
c45b4f1f
LT
727 help
728 Enabling this option will pass "-Os" instead of "-O2" to gcc
729 resulting in a smaller kernel.
730
775a7229 731 If unsure, say Y.
c45b4f1f 732
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733config SYSCTL
734 bool
735
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736config ANON_INODES
737 bool
738
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739menuconfig EMBEDDED
740 bool "Configure standard kernel features (for small systems)"
741 help
742 This option allows certain base kernel options and settings
743 to be disabled or tweaked. This is for specialized
744 environments which can tolerate a "non-standard" kernel.
745 Only use this if you really know what you are doing.
746
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CE
747config UID16
748 bool "Enable 16-bit UID system calls" if EMBEDDED
09337f50 749 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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750 default y
751 help
752 This enables the legacy 16-bit UID syscall wrappers.
753
b89a8171 754config SYSCTL_SYSCALL
0847062a 755 bool "Sysctl syscall support" if EMBEDDED
13bb7e37 756 default y
b89a8171 757 select SYSCTL
ae81f9e3 758 ---help---
13bb7e37
EB
759 sys_sysctl uses binary paths that have been found challenging
760 to properly maintain and use. The interface in /proc/sys
761 using paths with ascii names is now the primary path to this
762 information.
b89a8171 763
13bb7e37
EB
764 Almost nothing using the binary sysctl interface so if you are
765 trying to save some space it is probably safe to disable this,
766 making your kernel marginally smaller.
b89a8171 767
13bb7e37 768 If unsure say Y here.
ae81f9e3 769
1da177e4 770config KALLSYMS
979c6a1e 771 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
1da177e4
LT
772 default y
773 help
774 Say Y here to let the kernel print out symbolic crash information and
775 symbolic stack backtraces. This increases the size of the kernel
776 somewhat, as all symbols have to be loaded into the kernel image.
777
778config KALLSYMS_ALL
779 bool "Include all symbols in kallsyms"
780 depends on DEBUG_KERNEL && KALLSYMS
781 help
782 Normally kallsyms only contains the symbols of functions, for nicer
783 OOPS messages. Some debuggers can use kallsyms for other
f9f97bc0
JJ
784 symbols too: say Y here to include all symbols, if you need them
785 and you don't care about adding 300k to the size of your kernel.
1da177e4
LT
786
787 Say N.
788
789config KALLSYMS_EXTRA_PASS
790 bool "Do an extra kallsyms pass"
791 depends on KALLSYMS
792 help
793 If kallsyms is not working correctly, the build will fail with
794 inconsistent kallsyms data. If that occurs, log a bug report and
795 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
796 Always say N here unless you find a bug in kallsyms, which must be
797 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
798 you wait for kallsyms to be fixed.
799
d59745ce 800
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GKH
801config HOTPLUG
802 bool "Support for hot-pluggable devices" if EMBEDDED
803 default y
804 help
805 This option is provided for the case where no hotplug or uevent
806 capabilities is wanted by the kernel. You should only consider
807 disabling this option for embedded systems that do not use modules, a
808 dynamic /dev tree, or dynamic device discovery. Just say Y.
809
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MM
810config PRINTK
811 default y
812 bool "Enable support for printk" if EMBEDDED
813 help
814 This option enables normal printk support. Removing it
815 eliminates most of the message strings from the kernel image
816 and makes the kernel more or less silent. As this makes it
817 very difficult to diagnose system problems, saying N here is
818 strongly discouraged.
819
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MM
820config BUG
821 bool "BUG() support" if EMBEDDED
822 default y
823 help
824 Disabling this option eliminates support for BUG and WARN, reducing
825 the size of your kernel image and potentially quietly ignoring
826 numerous fatal conditions. You should only consider disabling this
827 option for embedded systems with no facilities for reporting errors.
828 Just say Y.
829
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MM
830config ELF_CORE
831 default y
832 bool "Enable ELF core dumps" if EMBEDDED
833 help
834 Enable support for generating core dumps. Disabling saves about 4k.
835
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SS
836config PCSPKR_PLATFORM
837 bool "Enable PC-Speaker support" if EMBEDDED
838 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
839 default y
840 help
841 This option allows to disable the internal PC-Speaker
842 support, saving some memory.
843
1da177e4
LT
844config BASE_FULL
845 default y
846 bool "Enable full-sized data structures for core" if EMBEDDED
847 help
848 Disabling this option reduces the size of miscellaneous core
849 kernel data structures. This saves memory on small machines,
850 but may reduce performance.
851
852config FUTEX
853 bool "Enable futex support" if EMBEDDED
854 default y
23f78d4a 855 select RT_MUTEXES
1da177e4
LT
856 help
857 Disabling this option will cause the kernel to be built without
858 support for "fast userspace mutexes". The resulting kernel may not
859 run glibc-based applications correctly.
860
861config EPOLL
862 bool "Enable eventpoll support" if EMBEDDED
863 default y
448e3cee 864 select ANON_INODES
1da177e4
LT
865 help
866 Disabling this option will cause the kernel to be built without
867 support for epoll family of system calls.
868
fba2afaa
DL
869config SIGNALFD
870 bool "Enable signalfd() system call" if EMBEDDED
448e3cee 871 select ANON_INODES
fba2afaa
DL
872 default y
873 help
874 Enable the signalfd() system call that allows to receive signals
875 on a file descriptor.
876
877 If unsure, say Y.
878
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DL
879config TIMERFD
880 bool "Enable timerfd() system call" if EMBEDDED
448e3cee 881 select ANON_INODES
b215e283
DL
882 default y
883 help
884 Enable the timerfd() system call that allows to receive timer
885 events on a file descriptor.
886
887 If unsure, say Y.
888
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DL
889config EVENTFD
890 bool "Enable eventfd() system call" if EMBEDDED
448e3cee 891 select ANON_INODES
e1ad7468
DL
892 default y
893 help
894 Enable the eventfd() system call that allows to receive both
895 kernel notification (ie. KAIO) or userspace notifications.
896
897 If unsure, say Y.
898
1da177e4
LT
899config SHMEM
900 bool "Use full shmem filesystem" if EMBEDDED
901 default y
902 depends on MMU
903 help
904 The shmem is an internal filesystem used to manage shared memory.
905 It is backed by swap and manages resource limits. It is also exported
906 to userspace as tmpfs if TMPFS is enabled. Disabling this
907 option replaces shmem and tmpfs with the much simpler ramfs code,
908 which may be appropriate on small systems without swap.
909
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TP
910config AIO
911 bool "Enable AIO support" if EMBEDDED
912 default y
913 help
914 This option enables POSIX asynchronous I/O which may by used
915 by some high performance threaded applications. Disabling
916 this option saves about 7k.
917
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TG
918config HAVE_PERF_COUNTERS
919 bool
018df72d
MF
920 help
921 See tools/perf/design.txt for details.
0793a61d
TG
922
923menu "Performance Counters"
924
925config PERF_COUNTERS
926 bool "Kernel Performance Counters"
f2654260 927 default y if PROFILING
0793a61d 928 depends on HAVE_PERF_COUNTERS
4c59e467 929 select ANON_INODES
0793a61d
TG
930 help
931 Enable kernel support for performance counter hardware.
932
933 Performance counters are special hardware registers available
934 on most modern CPUs. These registers count the number of certain
935 types of hw events: such as instructions executed, cachemisses
936 suffered, or branches mis-predicted - without slowing down the
937 kernel or applications. These registers can also trigger interrupts
938 when a threshold number of events have passed - and can thus be
939 used to profile the code that runs on that CPU.
940
941 The Linux Performance Counter subsystem provides an abstraction of
942 these hardware capabilities, available via a system call. It
943 provides per task and per CPU counters, and it provides event
944 capabilities on top of those.
945
946 Say Y if unsure.
947
e077df4f 948config EVENT_PROFILE
470a1396 949 bool "Tracepoint profiling sources"
d4d7d0b9 950 depends on PERF_COUNTERS && EVENT_TRACING
e077df4f 951 default y
470a1396
PZ
952 help
953 Allow the use of tracepoints as software performance counters.
954
955 When this is enabled, you can create perf counters based on
956 tracepoints using PERF_TYPE_TRACEPOINT and the tracepoint ID
957 found in debugfs://tracing/events/*/*/id. (The -e/--events
958 option to the perf tool can parse and interpret symbolic
959 tracepoints, in the subsystem:tracepoint_name format.)
e077df4f 960
0793a61d
TG
961endmenu
962
f8891e5e
CL
963config VM_EVENT_COUNTERS
964 default y
965 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
966 help
2aea4fb6
PJ
967 VM event counters are needed for event counts to be shown.
968 This option allows the disabling of the VM event counters
969 on EMBEDDED systems. /proc/vmstat will only show page counts
970 if VM event counters are disabled.
f8891e5e 971
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TP
972config PCI_QUIRKS
973 default y
61cfc7e4
GU
974 bool "Enable PCI quirk workarounds" if EMBEDDED
975 depends on PCI
3d137310
TP
976 help
977 This enables workarounds for various PCI chipset
978 bugs/quirks. Disable this only if your target machine is
979 unaffected by PCI quirks.
980
41ecc55b
CL
981config SLUB_DEBUG
982 default y
983 bool "Enable SLUB debugging support" if EMBEDDED
f6acb635 984 depends on SLUB && SYSFS
41ecc55b
CL
985 help
986 SLUB has extensive debug support features. Disabling these can
987 result in significant savings in code size. This also disables
988 SLUB sysfs support. /sys/slab will not exist and there will be
989 no support for cache validation etc.
990
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RD
991config STRIP_ASM_SYMS
992 bool "Strip assembler-generated symbols during link"
993 default n
994 help
995 Strip internal assembler-generated symbols during a link (symbols
996 that look like '.Lxxx') so they don't pollute the output of
997 get_wchan() and suchlike.
998
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RD
999config COMPAT_BRK
1000 bool "Disable heap randomization"
1001 default y
1002 help
1003 Randomizing heap placement makes heap exploits harder, but it
1004 also breaks ancient binaries (including anything libc5 based).
1005 This option changes the bootup default to heap randomization
692105b8 1006 disabled, and can be overridden at runtime by setting
b943c460
RD
1007 /proc/sys/kernel/randomize_va_space to 2.
1008
1009 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1010
81819f0f
CL
1011choice
1012 prompt "Choose SLAB allocator"
a0acd820 1013 default SLUB
81819f0f
CL
1014 help
1015 This option allows to select a slab allocator.
1016
1017config SLAB
1018 bool "SLAB"
1019 help
1020 The regular slab allocator that is established and known to work
34013886 1021 well in all environments. It organizes cache hot objects in
02f56210 1022 per cpu and per node queues.
81819f0f
CL
1023
1024config SLUB
81819f0f
CL
1025 bool "SLUB (Unqueued Allocator)"
1026 help
1027 SLUB is a slab allocator that minimizes cache line usage
1028 instead of managing queues of cached objects (SLAB approach).
1029 Per cpu caching is realized using slabs of objects instead
1030 of queues of objects. SLUB can use memory efficiently
02f56210
SA
1031 and has enhanced diagnostics. SLUB is the default choice for
1032 a slab allocator.
81819f0f
CL
1033
1034config SLOB
84a01c2f 1035 depends on EMBEDDED
81819f0f
CL
1036 bool "SLOB (Simple Allocator)"
1037 help
37291458
MM
1038 SLOB replaces the stock allocator with a drastically simpler
1039 allocator. SLOB is generally more space efficient but
1040 does not perform as well on large systems.
81819f0f
CL
1041
1042endchoice
1043
125e5645
MD
1044config PROFILING
1045 bool "Profiling support (EXPERIMENTAL)"
1046 help
1047 Say Y here to enable the extended profiling support mechanisms used
1048 by profilers such as OProfile.
1049
5f87f112
IM
1050#
1051# Place an empty function call at each tracepoint site. Can be
1052# dynamically changed for a probe function.
1053#
97e1c18e 1054config TRACEPOINTS
5f87f112 1055 bool
97e1c18e 1056
125e5645
MD
1057config MARKERS
1058 bool "Activate markers"
91f73f90 1059 select TRACEPOINTS
125e5645
MD
1060 help
1061 Place an empty function call at each marker site. Can be
1062 dynamically changed for a probe function.
1063
fb32e03f
MD
1064source "arch/Kconfig"
1065
07fe7cb7
DH
1066config SLOW_WORK
1067 default n
1c2d008c 1068 bool
07fe7cb7
DH
1069 help
1070 The slow work thread pool provides a number of dynamically allocated
1071 threads that can be used by the kernel to perform operations that
1072 take a relatively long time.
1073
1074 An example of this would be CacheFiles doing a path lookup followed
1075 by a series of mkdirs and a create call, all of which have to touch
1076 disk.
1077
1c2d008c
DH
1078 See Documentation/slow-work.txt.
1079
1da177e4
LT
1080endmenu # General setup
1081
ee7e5516
DES
1082config HAVE_GENERIC_DMA_COHERENT
1083 bool
1084 default n
1085
158a9624
LT
1086config SLABINFO
1087 bool
1088 depends on PROC_FS
0f389ec6 1089 depends on SLAB || SLUB_DEBUG
158a9624
LT
1090 default y
1091
ae81f9e3
CE
1092config RT_MUTEXES
1093 boolean
ae81f9e3 1094
1da177e4
LT
1095config BASE_SMALL
1096 int
1097 default 0 if BASE_FULL
1098 default 1 if !BASE_FULL
1099
66da5733 1100menuconfig MODULES
1da177e4
LT
1101 bool "Enable loadable module support"
1102 help
1103 Kernel modules are small pieces of compiled code which can
1104 be inserted in the running kernel, rather than being
1105 permanently built into the kernel. You use the "modprobe"
1106 tool to add (and sometimes remove) them. If you say Y here,
1107 many parts of the kernel can be built as modules (by
1108 answering M instead of Y where indicated): this is most
1109 useful for infrequently used options which are not required
1110 for booting. For more information, see the man pages for
1111 modprobe, lsmod, modinfo, insmod and rmmod.
1112
1113 If you say Y here, you will need to run "make
1114 modules_install" to put the modules under /lib/modules/
1115 where modprobe can find them (you may need to be root to do
1116 this).
1117
1118 If unsure, say Y.
1119
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RD
1120if MODULES
1121
826e4506
LT
1122config MODULE_FORCE_LOAD
1123 bool "Forced module loading"
826e4506
LT
1124 default n
1125 help
91e37a79
RR
1126 Allow loading of modules without version information (ie. modprobe
1127 --force). Forced module loading sets the 'F' (forced) taint flag and
1128 is usually a really bad idea.
826e4506 1129
1da177e4
LT
1130config MODULE_UNLOAD
1131 bool "Module unloading"
1da177e4
LT
1132 help
1133 Without this option you will not be able to unload any
1134 modules (note that some modules may not be unloadable
f7f5b675
DV
1135 anyway), which makes your kernel smaller, faster
1136 and simpler. If unsure, say Y.
1da177e4
LT
1137
1138config MODULE_FORCE_UNLOAD
1139 bool "Forced module unloading"
1140 depends on MODULE_UNLOAD && EXPERIMENTAL
1141 help
1142 This option allows you to force a module to unload, even if the
1143 kernel believes it is unsafe: the kernel will remove the module
1144 without waiting for anyone to stop using it (using the -f option to
1145 rmmod). This is mainly for kernel developers and desperate users.
1146 If unsure, say N.
1147
1da177e4 1148config MODVERSIONS
0d541643 1149 bool "Module versioning support"
1da177e4
LT
1150 help
1151 Usually, you have to use modules compiled with your kernel.
1152 Saying Y here makes it sometimes possible to use modules
1153 compiled for different kernels, by adding enough information
1154 to the modules to (hopefully) spot any changes which would
1155 make them incompatible with the kernel you are running. If
1156 unsure, say N.
1157
1158config MODULE_SRCVERSION_ALL
1159 bool "Source checksum for all modules"
1da177e4
LT
1160 help
1161 Modules which contain a MODULE_VERSION get an extra "srcversion"
1162 field inserted into their modinfo section, which contains a
1163 sum of the source files which made it. This helps maintainers
1164 see exactly which source was used to build a module (since
1165 others sometimes change the module source without updating
1166 the version). With this option, such a "srcversion" field
1167 will be created for all modules. If unsure, say N.
1168
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RD
1169endif # MODULES
1170
98a79d6a
RR
1171config INIT_ALL_POSSIBLE
1172 bool
1173 help
1174 Back when each arch used to define their own cpu_online_map and
1175 cpu_possible_map, some of them chose to initialize cpu_possible_map
1176 with all 1s, and others with all 0s. When they were centralised,
1177 it was better to provide this option than to break all the archs
692105b8 1178 and have several arch maintainers pursuing me down dark alleys.
98a79d6a 1179
1da177e4
LT
1180config STOP_MACHINE
1181 bool
1182 default y
1183 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1184 help
1185 Need stop_machine() primitive.
3a65dfe8 1186
3a65dfe8 1187source "block/Kconfig"
e98c3202
AK
1188
1189config PREEMPT_NOTIFIERS
1190 bool
e260be67 1191