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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47 drivers that have been replaced by something else, and/or are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
1da177e4 78
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79config CROSS_COMPILE
80 string "Cross-compiler tool prefix"
81 help
82 Same as running 'make CROSS_COMPILE=prefix-' but stored for
83 default make runs in this kernel build directory. You don't
84 need to set this unless you want the configured kernel build
85 directory to select the cross-compiler automatically.
86
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87config LOCALVERSION
88 string "Local version - append to kernel release"
89 help
90 Append an extra string to the end of your kernel version.
91 This will show up when you type uname, for example.
92 The string you set here will be appended after the contents of
93 any files with a filename matching localversion* in your
94 object and source tree, in that order. Your total string can
95 be a maximum of 64 characters.
96
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97config LOCALVERSION_AUTO
98 bool "Automatically append version information to the version string"
99 default y
100 help
101 This will try to automatically determine if the current tree is a
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102 release tree by looking for git tags that belong to the current
103 top of tree revision.
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104
105 A string of the format -gxxxxxxxx will be added to the localversion
6e5a5420 106 if a git-based tree is found. The string generated by this will be
aaebf433 107 appended after any matching localversion* files, and after the value
6e5a5420 108 set in CONFIG_LOCALVERSION.
aaebf433 109
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110 (The actual string used here is the first eight characters produced
111 by running the command:
112
113 $ git rev-parse --verify HEAD
114
115 which is done within the script "scripts/setlocalversion".)
aaebf433 116
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117config HAVE_KERNEL_GZIP
118 bool
119
120config HAVE_KERNEL_BZIP2
121 bool
122
123config HAVE_KERNEL_LZMA
124 bool
125
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126config HAVE_KERNEL_LZO
127 bool
128
30d65dbf 129choice
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130 prompt "Kernel compression mode"
131 default KERNEL_GZIP
7dd65feb 132 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_LZO
2e9f3bdd 133 help
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134 The linux kernel is a kind of self-extracting executable.
135 Several compression algorithms are available, which differ
136 in efficiency, compression and decompression speed.
137 Compression speed is only relevant when building a kernel.
138 Decompression speed is relevant at each boot.
139
140 If you have any problems with bzip2 or lzma compressed
141 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
142 version of this functionality (bzip2 only), for 2.4, was
143 supplied by Christian Ludwig)
144
145 High compression options are mostly useful for users, who
146 are low on disk space (embedded systems), but for whom ram
147 size matters less.
148
149 If in doubt, select 'gzip'
150
151config KERNEL_GZIP
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152 bool "Gzip"
153 depends on HAVE_KERNEL_GZIP
154 help
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155 The old and tried gzip compression. It provides a good balance
156 between compression ratio and decompression speed.
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157
158config KERNEL_BZIP2
159 bool "Bzip2"
2e9f3bdd 160 depends on HAVE_KERNEL_BZIP2
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161 help
162 Its compression ratio and speed is intermediate.
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163 Decompression speed is slowest among the three. The kernel
164 size is about 10% smaller with bzip2, in comparison to gzip.
165 Bzip2 uses a large amount of memory. For modern kernels you
166 will need at least 8MB RAM or more for booting.
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167
168config KERNEL_LZMA
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169 bool "LZMA"
170 depends on HAVE_KERNEL_LZMA
171 help
172 The most recent compression algorithm.
173 Its ratio is best, decompression speed is between the other
174 two. Compression is slowest. The kernel size is about 33%
175 smaller with LZMA in comparison to gzip.
30d65dbf 176
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177config KERNEL_LZO
178 bool "LZO"
179 depends on HAVE_KERNEL_LZO
180 help
181 Its compression ratio is the poorest among the 4. The kernel
182 size is about about 10% bigger than gzip; however its speed
183 (both compression and decompression) is the fastest.
184
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185endchoice
186
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187config SWAP
188 bool "Support for paging of anonymous memory (swap)"
9361401e 189 depends on MMU && BLOCK
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190 default y
191 help
192 This option allows you to choose whether you want to have support
92c3504e 193 for so called swap devices or swap files in your kernel that are
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194 used to provide more virtual memory than the actual RAM present
195 in your computer. If unsure say Y.
196
197config SYSVIPC
198 bool "System V IPC"
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199 ---help---
200 Inter Process Communication is a suite of library functions and
201 system calls which let processes (running programs) synchronize and
202 exchange information. It is generally considered to be a good thing,
203 and some programs won't run unless you say Y here. In particular, if
204 you want to run the DOS emulator dosemu under Linux (read the
205 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
206 you'll need to say Y here.
207
208 You can find documentation about IPC with "info ipc" and also in
209 section 6.4 of the Linux Programmer's Guide, available from
210 <http://www.tldp.org/guides.html>.
211
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212config SYSVIPC_SYSCTL
213 bool
214 depends on SYSVIPC
215 depends on SYSCTL
216 default y
217
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218config POSIX_MQUEUE
219 bool "POSIX Message Queues"
220 depends on NET && EXPERIMENTAL
221 ---help---
222 POSIX variant of message queues is a part of IPC. In POSIX message
223 queues every message has a priority which decides about succession
224 of receiving it by a process. If you want to compile and run
225 programs written e.g. for Solaris with use of its POSIX message
b0e37650 226 queues (functions mq_*) say Y here.
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227
228 POSIX message queues are visible as a filesystem called 'mqueue'
229 and can be mounted somewhere if you want to do filesystem
230 operations on message queues.
231
232 If unsure, say Y.
233
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234config POSIX_MQUEUE_SYSCTL
235 bool
236 depends on POSIX_MQUEUE
237 depends on SYSCTL
238 default y
239
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240config BSD_PROCESS_ACCT
241 bool "BSD Process Accounting"
242 help
243 If you say Y here, a user level program will be able to instruct the
244 kernel (via a special system call) to write process accounting
245 information to a file: whenever a process exits, information about
246 that process will be appended to the file by the kernel. The
247 information includes things such as creation time, owning user,
248 command name, memory usage, controlling terminal etc. (the complete
249 list is in the struct acct in <file:include/linux/acct.h>). It is
250 up to the user level program to do useful things with this
251 information. This is generally a good idea, so say Y.
252
253config BSD_PROCESS_ACCT_V3
254 bool "BSD Process Accounting version 3 file format"
255 depends on BSD_PROCESS_ACCT
256 default n
257 help
258 If you say Y here, the process accounting information is written
259 in a new file format that also logs the process IDs of each
260 process and it's parent. Note that this file format is incompatible
261 with previous v0/v1/v2 file formats, so you will need updated tools
262 for processing it. A preliminary version of these tools is available
37a4c940 263 at <http://www.gnu.org/software/acct/>.
1da177e4 264
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265config TASKSTATS
266 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
267 depends on NET
268 default n
269 help
270 Export selected statistics for tasks/processes through the
271 generic netlink interface. Unlike BSD process accounting, the
272 statistics are available during the lifetime of tasks/processes as
273 responses to commands. Like BSD accounting, they are sent to user
274 space on task exit.
275
276 Say N if unsure.
277
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278config TASK_DELAY_ACCT
279 bool "Enable per-task delay accounting (EXPERIMENTAL)"
6f44993f 280 depends on TASKSTATS
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281 help
282 Collect information on time spent by a task waiting for system
283 resources like cpu, synchronous block I/O completion and swapping
284 in pages. Such statistics can help in setting a task's priorities
285 relative to other tasks for cpu, io, rss limits etc.
286
287 Say N if unsure.
288
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289config TASK_XACCT
290 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
291 depends on TASKSTATS
292 help
293 Collect extended task accounting data and send the data
294 to userland for processing over the taskstats interface.
295
296 Say N if unsure.
297
298config TASK_IO_ACCOUNTING
299 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
300 depends on TASK_XACCT
301 help
302 Collect information on the number of bytes of storage I/O which this
303 task has caused.
304
305 Say N if unsure.
306
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307config AUDIT
308 bool "Auditing support"
804a6a49 309 depends on NET
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310 help
311 Enable auditing infrastructure that can be used with another
312 kernel subsystem, such as SELinux (which requires this for
313 logging of avc messages output). Does not do system-call
314 auditing without CONFIG_AUDITSYSCALL.
315
316config AUDITSYSCALL
317 bool "Enable system-call auditing support"
022382a5 318 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
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319 default y if SECURITY_SELINUX
320 help
321 Enable low-overhead system-call auditing infrastructure that
322 can be used independently or with another kernel subsystem,
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323 such as SELinux. To use audit's filesystem watch feature, please
324 ensure that INOTIFY is configured.
1da177e4 325
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326config AUDIT_TREE
327 def_bool y
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328 depends on AUDITSYSCALL
329 select INOTIFY
74c3cbe3 330
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331menu "RCU Subsystem"
332
333choice
334 prompt "RCU Implementation"
31c9a24e 335 default TREE_RCU
c903ff83 336
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337config TREE_RCU
338 bool "Tree-based hierarchical RCU"
339 help
340 This option selects the RCU implementation that is
341 designed for very large SMP system with hundreds or
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342 thousands of CPUs. It also scales down nicely to
343 smaller systems.
c903ff83 344
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345config TREE_PREEMPT_RCU
346 bool "Preemptable tree-based hierarchical RCU"
347 depends on PREEMPT
348 help
349 This option selects the RCU implementation that is
350 designed for very large SMP systems with hundreds or
351 thousands of CPUs, but for which real-time response
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352 is also required. It also scales down nicely to
353 smaller systems.
f41d911f 354
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355config TINY_RCU
356 bool "UP-only small-memory-footprint RCU"
357 depends on !SMP
358 help
359 This option selects the RCU implementation that is
360 designed for UP systems from which real-time response
361 is not required. This option greatly reduces the
362 memory footprint of RCU.
363
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364endchoice
365
366config RCU_TRACE
367 bool "Enable tracing for RCU"
6b3ef48a 368 depends on TREE_RCU || TREE_PREEMPT_RCU
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369 help
370 This option provides tracing in RCU which presents stats
371 in debugfs for debugging RCU implementation.
372
373 Say Y here if you want to enable RCU tracing
374 Say N if you are unsure.
375
376config RCU_FANOUT
377 int "Tree-based hierarchical RCU fanout value"
378 range 2 64 if 64BIT
379 range 2 32 if !64BIT
f41d911f 380 depends on TREE_RCU || TREE_PREEMPT_RCU
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381 default 64 if 64BIT
382 default 32 if !64BIT
383 help
384 This option controls the fanout of hierarchical implementations
385 of RCU, allowing RCU to work efficiently on machines with
386 large numbers of CPUs. This value must be at least the cube
387 root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
388 systems and up to 262,144 for 64-bit systems.
389
390 Select a specific number if testing RCU itself.
391 Take the default if unsure.
392
393config RCU_FANOUT_EXACT
394 bool "Disable tree-based hierarchical RCU auto-balancing"
f41d911f 395 depends on TREE_RCU || TREE_PREEMPT_RCU
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396 default n
397 help
398 This option forces use of the exact RCU_FANOUT value specified,
399 regardless of imbalances in the hierarchy. This is useful for
400 testing RCU itself, and might one day be useful on systems with
401 strong NUMA behavior.
402
403 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
404
405 Say N if unsure.
406
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407config RCU_FAST_NO_HZ
408 bool "Accelerate last non-dyntick-idle CPU's grace periods"
409 depends on TREE_RCU && NO_HZ && SMP
410 default n
411 help
412 This option causes RCU to attempt to accelerate grace periods
413 in order to allow the final CPU to enter dynticks-idle state
414 more quickly. On the other hand, this option increases the
415 overhead of the dynticks-idle checking, particularly on systems
416 with large numbers of CPUs.
417
418 Say Y if energy efficiency is critically important, particularly
419 if you have relatively few CPUs.
420
421 Say N if you are unsure.
422
c903ff83 423config TREE_RCU_TRACE
f41d911f 424 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
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425 select DEBUG_FS
426 help
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427 This option provides tracing for the TREE_RCU and
428 TREE_PREEMPT_RCU implementations, permitting Makefile to
429 trivially select kernel/rcutree_trace.c.
c903ff83 430
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431endmenu # "RCU Subsystem"
432
1da177e4 433config IKCONFIG
f2443ab6 434 tristate "Kernel .config support"
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435 ---help---
436 This option enables the complete Linux kernel ".config" file
437 contents to be saved in the kernel. It provides documentation
438 of which kernel options are used in a running kernel or in an
439 on-disk kernel. This information can be extracted from the kernel
440 image file with the script scripts/extract-ikconfig and used as
441 input to rebuild the current kernel or to build another kernel.
442 It can also be extracted from a running kernel by reading
443 /proc/config.gz if enabled (below).
444
445config IKCONFIG_PROC
446 bool "Enable access to .config through /proc/config.gz"
447 depends on IKCONFIG && PROC_FS
448 ---help---
449 This option enables access to the kernel configuration file
450 through /proc/config.gz.
451
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452config LOG_BUF_SHIFT
453 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
454 range 12 21
f17a32e9 455 default 17
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456 help
457 Select kernel log buffer size as a power of 2.
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458 Examples:
459 17 => 128 KB
460 16 => 64 KB
461 15 => 32 KB
462 14 => 16 KB
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463 13 => 8 KB
464 12 => 4 KB
465
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466#
467# Architectures with an unreliable sched_clock() should select this:
468#
469config HAVE_UNSTABLE_SCHED_CLOCK
470 bool
471
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472menuconfig CGROUPS
473 boolean "Control Group support"
0dea1168 474 depends on EVENTFD
5cdc38f9 475 help
23964d2d 476 This option adds support for grouping sets of processes together, for
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477 use with process control subsystems such as Cpusets, CFS, memory
478 controls or device isolation.
479 See
5cdc38f9 480 - Documentation/scheduler/sched-design-CFS.txt (CFS)
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481 - Documentation/cgroups/ (features for grouping, isolation
482 and resource control)
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483
484 Say N if unsure.
485
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486if CGROUPS
487
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488config CGROUP_DEBUG
489 bool "Example debug cgroup subsystem"
490 depends on CGROUPS
491 default n
492 help
493 This option enables a simple cgroup subsystem that
494 exports useful debugging information about the cgroups
23964d2d 495 framework.
5cdc38f9 496
23964d2d 497 Say N if unsure.
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498
499config CGROUP_NS
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500 bool "Namespace cgroup subsystem"
501 depends on CGROUPS
502 help
503 Provides a simple namespace cgroup subsystem to
504 provide hierarchical naming of sets of namespaces,
505 for instance virtual servers and checkpoint/restart
506 jobs.
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507
508config CGROUP_FREEZER
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509 bool "Freezer cgroup subsystem"
510 depends on CGROUPS
511 help
512 Provides a way to freeze and unfreeze all tasks in a
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513 cgroup.
514
515config CGROUP_DEVICE
516 bool "Device controller for cgroups"
517 depends on CGROUPS && EXPERIMENTAL
518 help
519 Provides a cgroup implementing whitelists for devices which
520 a process in the cgroup can mknod or open.
521
522config CPUSETS
523 bool "Cpuset support"
db7f47cf 524 depends on CGROUPS
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525 help
526 This option will let you create and manage CPUSETs which
527 allow dynamically partitioning a system into sets of CPUs and
528 Memory Nodes and assigning tasks to run only within those sets.
529 This is primarily useful on large SMP or NUMA systems.
530
531 Say N if unsure.
532
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533config PROC_PID_CPUSET
534 bool "Include legacy /proc/<pid>/cpuset file"
535 depends on CPUSETS
536 default y
537
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538config CGROUP_CPUACCT
539 bool "Simple CPU accounting cgroup subsystem"
540 depends on CGROUPS
541 help
542 Provides a simple Resource Controller for monitoring the
23964d2d 543 total CPU consumed by the tasks in a cgroup.
d842de87 544
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545config RESOURCE_COUNTERS
546 bool "Resource counters"
547 help
548 This option enables controller independent resource accounting
23964d2d 549 infrastructure that works with cgroups.
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550 depends on CGROUPS
551
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552config CGROUP_MEM_RES_CTLR
553 bool "Memory Resource Controller for Control Groups"
554 depends on CGROUPS && RESOURCE_COUNTERS
cf475ad2 555 select MM_OWNER
00f0b825 556 help
84ad6d70 557 Provides a memory resource controller that manages both anonymous
21acb9ca 558 memory and page cache. (See Documentation/cgroups/memory.txt)
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559
560 Note that setting this option increases fixed memory overhead
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561 associated with each page of memory in the system. By this,
562 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
563 usage tracking struct at boot. Total amount of this is printed out
564 at boot.
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565
566 Only enable when you're ok with these trade offs and really
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567 sure you need the memory resource controller. Even when you enable
568 this, you can set "cgroup_disable=memory" at your boot option to
569 disable memory resource controller and you can avoid overheads.
c9d5409f 570 (and lose benefits of memory resource controller)
00f0b825 571
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572 This config option also selects MM_OWNER config option, which
573 could in turn add some fork/exit overhead.
574
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575config CGROUP_MEM_RES_CTLR_SWAP
576 bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)"
577 depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL
578 help
579 Add swap management feature to memory resource controller. When you
580 enable this, you can limit mem+swap usage per cgroup. In other words,
581 when you disable this, memory resource controller has no cares to
582 usage of swap...a process can exhaust all of the swap. This extension
583 is useful when you want to avoid exhaustion swap but this itself
584 adds more overheads and consumes memory for remembering information.
585 Especially if you use 32bit system or small memory system, please
586 be careful about enabling this. When memory resource controller
587 is disabled by boot option, this will be automatically disabled and
588 there will be no overhead from this. Even when you set this config=y,
589 if boot option "noswapaccount" is set, swap will not be accounted.
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590 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
591 size is 4096bytes, 512k per 1Gbytes of swap.
c077719b 592
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593menuconfig CGROUP_SCHED
594 bool "Group CPU scheduler"
595 depends on EXPERIMENTAL && CGROUPS
596 default n
597 help
598 This feature lets CPU scheduler recognize task groups and control CPU
599 bandwidth allocation to such task groups. It uses cgroups to group
600 tasks.
601
602if CGROUP_SCHED
603config FAIR_GROUP_SCHED
604 bool "Group scheduling for SCHED_OTHER"
605 depends on CGROUP_SCHED
606 default CGROUP_SCHED
607
608config RT_GROUP_SCHED
609 bool "Group scheduling for SCHED_RR/FIFO"
610 depends on EXPERIMENTAL
611 depends on CGROUP_SCHED
612 default n
613 help
614 This feature lets you explicitly allocate real CPU bandwidth
32bd7eb5 615 to task groups. If enabled, it will also make it impossible to
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616 schedule realtime tasks for non-root users until you allocate
617 realtime bandwidth for them.
618 See Documentation/scheduler/sched-rt-group.txt for more information.
619
620endif #CGROUP_SCHED
621
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622config BLK_CGROUP
623 tristate "Block IO controller"
624 depends on CGROUPS && BLOCK
625 default n
626 ---help---
627 Generic block IO controller cgroup interface. This is the common
628 cgroup interface which should be used by various IO controlling
629 policies.
630
631 Currently, CFQ IO scheduler uses it to recognize task groups and
632 control disk bandwidth allocation (proportional time slice allocation)
633 to such task groups.
634
635 This option only enables generic Block IO controller infrastructure.
636 One needs to also enable actual IO controlling logic in CFQ for it
637 to take effect. (CONFIG_CFQ_GROUP_IOSCHED=y).
638
639 See Documentation/cgroups/blkio-controller.txt for more information.
640
641config DEBUG_BLK_CGROUP
642 bool "Enable Block IO controller debugging"
643 depends on BLK_CGROUP
644 default n
645 ---help---
646 Enable some debugging help. Currently it exports additional stat
647 files in a cgroup which can be useful for debugging.
648
23964d2d 649endif # CGROUPS
c077719b 650
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651config MM_OWNER
652 bool
5cdc38f9 653
88a22c98 654config SYSFS_DEPRECATED
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655 bool
656
657config SYSFS_DEPRECATED_V2
9e9868a7 658 bool "enable deprecated sysfs features to support old userspace tools"
9148fe87 659 depends on SYSFS
f6ee649f 660 default n
d47846c5 661 select SYSFS_DEPRECATED
88a22c98 662 help
fce3e804 663 This option switches the layout of sysfs to the deprecated
f6ee649f 664 version. Do not use it on recent distributions.
fce3e804
KS
665
666 The current sysfs layout features a unified device tree at
667 /sys/devices/, which is able to express a hierarchy between
668 class devices. If the deprecated option is set to Y, the
669 unified device tree is split into a bus device tree at
670 /sys/devices/ and several individual class device trees at
671 /sys/class/. The class and bus devices will be connected by
672 "<subsystem>:<name>" and the "device" links. The "block"
673 class devices, will not show up in /sys/class/block/. Some
674 subsystems will suppress the creation of some devices which
675 depend on the unified device tree.
676
677 This option is not a pure compatibility option that can
678 be safely enabled on newer distributions. It will change the
679 layout of sysfs to the non-extensible deprecated version,
680 and disable some features, which can not be exported without
681 confusing older userspace tools. Since 2007/2008 all major
682 distributions do not enable this option, and ship no tools which
683 depend on the deprecated layout or this option.
684
685 If you are using a new kernel on an older distribution, or use
686 older userspace tools, you might need to say Y here. Do not say Y,
687 if the original kernel, that came with your distribution, has
688 this option set to N.
88a22c98 689
b86ff981
JA
690config RELAY
691 bool "Kernel->user space relay support (formerly relayfs)"
692 help
693 This option enables support for relay interface support in
694 certain file systems (such as debugfs).
695 It is designed to provide an efficient mechanism for tools and
696 facilities to relay large amounts of data from kernel space to
697 user space.
698
699 If unsure, say N.
700
c5289a69
PE
701config NAMESPACES
702 bool "Namespaces support" if EMBEDDED
703 default !EMBEDDED
704 help
705 Provides the way to make tasks work with different objects using
706 the same id. For example same IPC id may refer to different objects
707 or same user id or pid may refer to different tasks when used in
708 different namespaces.
709
58bfdd6d
PE
710config UTS_NS
711 bool "UTS namespace"
712 depends on NAMESPACES
713 help
714 In this namespace tasks see different info provided with the
715 uname() system call
716
ae5e1b22
PE
717config IPC_NS
718 bool "IPC namespace"
614b84cf 719 depends on NAMESPACES && (SYSVIPC || POSIX_MQUEUE)
ae5e1b22
PE
720 help
721 In this namespace tasks work with IPC ids which correspond to
614b84cf 722 different IPC objects in different namespaces.
ae5e1b22 723
aee16ce7
PE
724config USER_NS
725 bool "User namespace (EXPERIMENTAL)"
726 depends on NAMESPACES && EXPERIMENTAL
727 help
728 This allows containers, i.e. vservers, to use user namespaces
729 to provide different user info for different servers.
730 If unsure, say N.
731
74bd59bb
PE
732config PID_NS
733 bool "PID Namespaces (EXPERIMENTAL)"
734 default n
735 depends on NAMESPACES && EXPERIMENTAL
736 help
12d2b8f9 737 Support process id namespaces. This allows having multiple
692105b8 738 processes with the same pid as long as they are in different
74bd59bb
PE
739 pid namespaces. This is a building block of containers.
740
741 Unless you want to work with an experimental feature
742 say N here.
743
d6eb633f
MH
744config NET_NS
745 bool "Network namespace"
746 default n
747 depends on NAMESPACES && EXPERIMENTAL && NET
748 help
749 Allow user space to create what appear to be multiple instances
750 of the network stack.
751
f991633d
DG
752config BLK_DEV_INITRD
753 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
754 depends on BROKEN || !FRV
755 help
756 The initial RAM filesystem is a ramfs which is loaded by the
757 boot loader (loadlin or lilo) and that is mounted as root
758 before the normal boot procedure. It is typically used to
759 load modules needed to mount the "real" root file system,
760 etc. See <file:Documentation/initrd.txt> for details.
761
762 If RAM disk support (BLK_DEV_RAM) is also included, this
763 also enables initial RAM disk (initrd) support and adds
764 15 Kbytes (more on some other architectures) to the kernel size.
765
766 If unsure say Y.
767
c33df4ea
JPS
768if BLK_DEV_INITRD
769
dbec4866
SR
770source "usr/Kconfig"
771
c33df4ea
JPS
772endif
773
c45b4f1f 774config CC_OPTIMIZE_FOR_SIZE
96fffeb4 775 bool "Optimize for size"
c45b4f1f 776 default y
c45b4f1f
LT
777 help
778 Enabling this option will pass "-Os" instead of "-O2" to gcc
779 resulting in a smaller kernel.
780
775a7229 781 If unsure, say Y.
c45b4f1f 782
0847062a
RD
783config SYSCTL
784 bool
785
b943c460
RD
786config ANON_INODES
787 bool
788
1da177e4
LT
789menuconfig EMBEDDED
790 bool "Configure standard kernel features (for small systems)"
791 help
792 This option allows certain base kernel options and settings
793 to be disabled or tweaked. This is for specialized
794 environments which can tolerate a "non-standard" kernel.
795 Only use this if you really know what you are doing.
796
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CE
797config UID16
798 bool "Enable 16-bit UID system calls" if EMBEDDED
09337f50 799 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
ae81f9e3
CE
800 default y
801 help
802 This enables the legacy 16-bit UID syscall wrappers.
803
b89a8171 804config SYSCTL_SYSCALL
0847062a 805 bool "Sysctl syscall support" if EMBEDDED
26a7034b 806 depends on PROC_SYSCTL
13bb7e37 807 default y
b89a8171 808 select SYSCTL
ae81f9e3 809 ---help---
13bb7e37
EB
810 sys_sysctl uses binary paths that have been found challenging
811 to properly maintain and use. The interface in /proc/sys
812 using paths with ascii names is now the primary path to this
813 information.
b89a8171 814
13bb7e37
EB
815 Almost nothing using the binary sysctl interface so if you are
816 trying to save some space it is probably safe to disable this,
817 making your kernel marginally smaller.
b89a8171 818
13bb7e37 819 If unsure say Y here.
ae81f9e3 820
1da177e4 821config KALLSYMS
979c6a1e 822 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
1da177e4
LT
823 default y
824 help
825 Say Y here to let the kernel print out symbolic crash information and
826 symbolic stack backtraces. This increases the size of the kernel
827 somewhat, as all symbols have to be loaded into the kernel image.
828
829config KALLSYMS_ALL
830 bool "Include all symbols in kallsyms"
831 depends on DEBUG_KERNEL && KALLSYMS
832 help
833 Normally kallsyms only contains the symbols of functions, for nicer
834 OOPS messages. Some debuggers can use kallsyms for other
f9f97bc0
JJ
835 symbols too: say Y here to include all symbols, if you need them
836 and you don't care about adding 300k to the size of your kernel.
1da177e4
LT
837
838 Say N.
839
840config KALLSYMS_EXTRA_PASS
841 bool "Do an extra kallsyms pass"
842 depends on KALLSYMS
843 help
844 If kallsyms is not working correctly, the build will fail with
845 inconsistent kallsyms data. If that occurs, log a bug report and
846 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
847 Always say N here unless you find a bug in kallsyms, which must be
848 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
849 you wait for kallsyms to be fixed.
850
d59745ce 851
712f47ce
GKH
852config HOTPLUG
853 bool "Support for hot-pluggable devices" if EMBEDDED
854 default y
855 help
856 This option is provided for the case where no hotplug or uevent
857 capabilities is wanted by the kernel. You should only consider
858 disabling this option for embedded systems that do not use modules, a
859 dynamic /dev tree, or dynamic device discovery. Just say Y.
860
d59745ce
MM
861config PRINTK
862 default y
863 bool "Enable support for printk" if EMBEDDED
864 help
865 This option enables normal printk support. Removing it
866 eliminates most of the message strings from the kernel image
867 and makes the kernel more or less silent. As this makes it
868 very difficult to diagnose system problems, saying N here is
869 strongly discouraged.
870
c8538a7a
MM
871config BUG
872 bool "BUG() support" if EMBEDDED
873 default y
874 help
875 Disabling this option eliminates support for BUG and WARN, reducing
876 the size of your kernel image and potentially quietly ignoring
877 numerous fatal conditions. You should only consider disabling this
878 option for embedded systems with no facilities for reporting errors.
879 Just say Y.
880
708e9a79
MM
881config ELF_CORE
882 default y
883 bool "Enable ELF core dumps" if EMBEDDED
884 help
885 Enable support for generating core dumps. Disabling saves about 4k.
886
e5e1d3cb
SS
887config PCSPKR_PLATFORM
888 bool "Enable PC-Speaker support" if EMBEDDED
889 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
890 default y
891 help
892 This option allows to disable the internal PC-Speaker
893 support, saving some memory.
894
1da177e4
LT
895config BASE_FULL
896 default y
897 bool "Enable full-sized data structures for core" if EMBEDDED
898 help
899 Disabling this option reduces the size of miscellaneous core
900 kernel data structures. This saves memory on small machines,
901 but may reduce performance.
902
903config FUTEX
904 bool "Enable futex support" if EMBEDDED
905 default y
23f78d4a 906 select RT_MUTEXES
1da177e4
LT
907 help
908 Disabling this option will cause the kernel to be built without
909 support for "fast userspace mutexes". The resulting kernel may not
910 run glibc-based applications correctly.
911
912config EPOLL
913 bool "Enable eventpoll support" if EMBEDDED
914 default y
448e3cee 915 select ANON_INODES
1da177e4
LT
916 help
917 Disabling this option will cause the kernel to be built without
918 support for epoll family of system calls.
919
fba2afaa
DL
920config SIGNALFD
921 bool "Enable signalfd() system call" if EMBEDDED
448e3cee 922 select ANON_INODES
fba2afaa
DL
923 default y
924 help
925 Enable the signalfd() system call that allows to receive signals
926 on a file descriptor.
927
928 If unsure, say Y.
929
b215e283
DL
930config TIMERFD
931 bool "Enable timerfd() system call" if EMBEDDED
448e3cee 932 select ANON_INODES
b215e283
DL
933 default y
934 help
935 Enable the timerfd() system call that allows to receive timer
936 events on a file descriptor.
937
938 If unsure, say Y.
939
e1ad7468
DL
940config EVENTFD
941 bool "Enable eventfd() system call" if EMBEDDED
448e3cee 942 select ANON_INODES
e1ad7468
DL
943 default y
944 help
945 Enable the eventfd() system call that allows to receive both
946 kernel notification (ie. KAIO) or userspace notifications.
947
948 If unsure, say Y.
949
1da177e4
LT
950config SHMEM
951 bool "Use full shmem filesystem" if EMBEDDED
952 default y
953 depends on MMU
954 help
955 The shmem is an internal filesystem used to manage shared memory.
956 It is backed by swap and manages resource limits. It is also exported
957 to userspace as tmpfs if TMPFS is enabled. Disabling this
958 option replaces shmem and tmpfs with the much simpler ramfs code,
959 which may be appropriate on small systems without swap.
960
ebf3f09c
TP
961config AIO
962 bool "Enable AIO support" if EMBEDDED
963 default y
964 help
965 This option enables POSIX asynchronous I/O which may by used
966 by some high performance threaded applications. Disabling
967 this option saves about 7k.
968
cdd6c482 969config HAVE_PERF_EVENTS
0793a61d 970 bool
018df72d
MF
971 help
972 See tools/perf/design.txt for details.
0793a61d 973
906010b2
PZ
974config PERF_USE_VMALLOC
975 bool
976 help
977 See tools/perf/design.txt for details
978
57c0c15b 979menu "Kernel Performance Events And Counters"
0793a61d 980
cdd6c482 981config PERF_EVENTS
57c0c15b
IM
982 bool "Kernel performance events and counters"
983 default y if (PROFILING || PERF_COUNTERS)
cdd6c482 984 depends on HAVE_PERF_EVENTS
4c59e467 985 select ANON_INODES
0793a61d 986 help
57c0c15b
IM
987 Enable kernel support for various performance events provided
988 by software and hardware.
0793a61d 989
dd77038d 990 Software events are supported either built-in or via the
57c0c15b 991 use of generic tracepoints.
0793a61d 992
57c0c15b
IM
993 Most modern CPUs support performance events via performance
994 counter registers. These registers count the number of certain
0793a61d
TG
995 types of hw events: such as instructions executed, cachemisses
996 suffered, or branches mis-predicted - without slowing down the
997 kernel or applications. These registers can also trigger interrupts
998 when a threshold number of events have passed - and can thus be
999 used to profile the code that runs on that CPU.
1000
57c0c15b 1001 The Linux Performance Event subsystem provides an abstraction of
dd77038d 1002 these software and hardware event capabilities, available via a
57c0c15b 1003 system call and used by the "perf" utility in tools/perf/. It
0793a61d
TG
1004 provides per task and per CPU counters, and it provides event
1005 capabilities on top of those.
1006
1007 Say Y if unsure.
1008
57c0c15b
IM
1009config PERF_COUNTERS
1010 bool "Kernel performance counters (old config option)"
1011 depends on HAVE_PERF_EVENTS
1012 help
1013 This config has been obsoleted by the PERF_EVENTS
1014 config option - please see that one for details.
1015
1016 It has no effect on the kernel whether you enable
1017 it or not, it is a compatibility placeholder.
1018
1019 Say N if unsure.
1020
906010b2
PZ
1021config DEBUG_PERF_USE_VMALLOC
1022 default n
1023 bool "Debug: use vmalloc to back perf mmap() buffers"
1024 depends on PERF_EVENTS && DEBUG_KERNEL
1025 select PERF_USE_VMALLOC
1026 help
1027 Use vmalloc memory to back perf mmap() buffers.
1028
1029 Mostly useful for debugging the vmalloc code on platforms
1030 that don't require it.
1031
1032 Say N if unsure.
1033
0793a61d
TG
1034endmenu
1035
f8891e5e
CL
1036config VM_EVENT_COUNTERS
1037 default y
1038 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
1039 help
2aea4fb6
PJ
1040 VM event counters are needed for event counts to be shown.
1041 This option allows the disabling of the VM event counters
1042 on EMBEDDED systems. /proc/vmstat will only show page counts
1043 if VM event counters are disabled.
f8891e5e 1044
3d137310
TP
1045config PCI_QUIRKS
1046 default y
61cfc7e4
GU
1047 bool "Enable PCI quirk workarounds" if EMBEDDED
1048 depends on PCI
3d137310
TP
1049 help
1050 This enables workarounds for various PCI chipset
1051 bugs/quirks. Disable this only if your target machine is
1052 unaffected by PCI quirks.
1053
41ecc55b
CL
1054config SLUB_DEBUG
1055 default y
1056 bool "Enable SLUB debugging support" if EMBEDDED
f6acb635 1057 depends on SLUB && SYSFS
41ecc55b
CL
1058 help
1059 SLUB has extensive debug support features. Disabling these can
1060 result in significant savings in code size. This also disables
1061 SLUB sysfs support. /sys/slab will not exist and there will be
1062 no support for cache validation etc.
1063
b943c460
RD
1064config COMPAT_BRK
1065 bool "Disable heap randomization"
1066 default y
1067 help
1068 Randomizing heap placement makes heap exploits harder, but it
1069 also breaks ancient binaries (including anything libc5 based).
1070 This option changes the bootup default to heap randomization
692105b8 1071 disabled, and can be overridden at runtime by setting
b943c460
RD
1072 /proc/sys/kernel/randomize_va_space to 2.
1073
1074 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1075
81819f0f
CL
1076choice
1077 prompt "Choose SLAB allocator"
a0acd820 1078 default SLUB
81819f0f
CL
1079 help
1080 This option allows to select a slab allocator.
1081
1082config SLAB
1083 bool "SLAB"
1084 help
1085 The regular slab allocator that is established and known to work
34013886 1086 well in all environments. It organizes cache hot objects in
02f56210 1087 per cpu and per node queues.
81819f0f
CL
1088
1089config SLUB
81819f0f
CL
1090 bool "SLUB (Unqueued Allocator)"
1091 help
1092 SLUB is a slab allocator that minimizes cache line usage
1093 instead of managing queues of cached objects (SLAB approach).
1094 Per cpu caching is realized using slabs of objects instead
1095 of queues of objects. SLUB can use memory efficiently
02f56210
SA
1096 and has enhanced diagnostics. SLUB is the default choice for
1097 a slab allocator.
81819f0f
CL
1098
1099config SLOB
84a01c2f 1100 depends on EMBEDDED
81819f0f
CL
1101 bool "SLOB (Simple Allocator)"
1102 help
37291458
MM
1103 SLOB replaces the stock allocator with a drastically simpler
1104 allocator. SLOB is generally more space efficient but
1105 does not perform as well on large systems.
81819f0f
CL
1106
1107endchoice
1108
ea637639
JZ
1109config MMAP_ALLOW_UNINITIALIZED
1110 bool "Allow mmapped anonymous memory to be uninitialized"
1111 depends on EMBEDDED && !MMU
1112 default n
1113 help
1114 Normally, and according to the Linux spec, anonymous memory obtained
1115 from mmap() has it's contents cleared before it is passed to
1116 userspace. Enabling this config option allows you to request that
1117 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1118 providing a huge performance boost. If this option is not enabled,
1119 then the flag will be ignored.
1120
1121 This is taken advantage of by uClibc's malloc(), and also by
1122 ELF-FDPIC binfmt's brk and stack allocator.
1123
1124 Because of the obvious security issues, this option should only be
1125 enabled on embedded devices where you control what is run in
1126 userspace. Since that isn't generally a problem on no-MMU systems,
1127 it is normally safe to say Y here.
1128
1129 See Documentation/nommu-mmap.txt for more information.
1130
125e5645 1131config PROFILING
b309a294 1132 bool "Profiling support"
125e5645
MD
1133 help
1134 Say Y here to enable the extended profiling support mechanisms used
1135 by profilers such as OProfile.
1136
5f87f112
IM
1137#
1138# Place an empty function call at each tracepoint site. Can be
1139# dynamically changed for a probe function.
1140#
97e1c18e 1141config TRACEPOINTS
5f87f112 1142 bool
97e1c18e 1143
fb32e03f
MD
1144source "arch/Kconfig"
1145
07fe7cb7
DH
1146config SLOW_WORK
1147 default n
1c2d008c 1148 bool
07fe7cb7
DH
1149 help
1150 The slow work thread pool provides a number of dynamically allocated
1151 threads that can be used by the kernel to perform operations that
1152 take a relatively long time.
1153
1154 An example of this would be CacheFiles doing a path lookup followed
1155 by a series of mkdirs and a create call, all of which have to touch
1156 disk.
1157
1c2d008c
DH
1158 See Documentation/slow-work.txt.
1159
f13a48bd
DH
1160config SLOW_WORK_DEBUG
1161 bool "Slow work debugging through debugfs"
8fba10a4 1162 default n
f13a48bd 1163 depends on SLOW_WORK && DEBUG_FS
8fba10a4 1164 help
f13a48bd 1165 Display the contents of the slow work run queue through debugfs,
8fba10a4
DH
1166 including items currently executing.
1167
1168 See Documentation/slow-work.txt.
1169
1da177e4
LT
1170endmenu # General setup
1171
ee7e5516
DES
1172config HAVE_GENERIC_DMA_COHERENT
1173 bool
1174 default n
1175
158a9624
LT
1176config SLABINFO
1177 bool
1178 depends on PROC_FS
0f389ec6 1179 depends on SLAB || SLUB_DEBUG
158a9624
LT
1180 default y
1181
ae81f9e3
CE
1182config RT_MUTEXES
1183 boolean
ae81f9e3 1184
1da177e4
LT
1185config BASE_SMALL
1186 int
1187 default 0 if BASE_FULL
1188 default 1 if !BASE_FULL
1189
66da5733 1190menuconfig MODULES
1da177e4
LT
1191 bool "Enable loadable module support"
1192 help
1193 Kernel modules are small pieces of compiled code which can
1194 be inserted in the running kernel, rather than being
1195 permanently built into the kernel. You use the "modprobe"
1196 tool to add (and sometimes remove) them. If you say Y here,
1197 many parts of the kernel can be built as modules (by
1198 answering M instead of Y where indicated): this is most
1199 useful for infrequently used options which are not required
1200 for booting. For more information, see the man pages for
1201 modprobe, lsmod, modinfo, insmod and rmmod.
1202
1203 If you say Y here, you will need to run "make
1204 modules_install" to put the modules under /lib/modules/
1205 where modprobe can find them (you may need to be root to do
1206 this).
1207
1208 If unsure, say Y.
1209
0b0de144
RD
1210if MODULES
1211
826e4506
LT
1212config MODULE_FORCE_LOAD
1213 bool "Forced module loading"
826e4506
LT
1214 default n
1215 help
91e37a79
RR
1216 Allow loading of modules without version information (ie. modprobe
1217 --force). Forced module loading sets the 'F' (forced) taint flag and
1218 is usually a really bad idea.
826e4506 1219
1da177e4
LT
1220config MODULE_UNLOAD
1221 bool "Module unloading"
1da177e4
LT
1222 help
1223 Without this option you will not be able to unload any
1224 modules (note that some modules may not be unloadable
f7f5b675
DV
1225 anyway), which makes your kernel smaller, faster
1226 and simpler. If unsure, say Y.
1da177e4
LT
1227
1228config MODULE_FORCE_UNLOAD
1229 bool "Forced module unloading"
1230 depends on MODULE_UNLOAD && EXPERIMENTAL
1231 help
1232 This option allows you to force a module to unload, even if the
1233 kernel believes it is unsafe: the kernel will remove the module
1234 without waiting for anyone to stop using it (using the -f option to
1235 rmmod). This is mainly for kernel developers and desperate users.
1236 If unsure, say N.
1237
1da177e4 1238config MODVERSIONS
0d541643 1239 bool "Module versioning support"
1da177e4
LT
1240 help
1241 Usually, you have to use modules compiled with your kernel.
1242 Saying Y here makes it sometimes possible to use modules
1243 compiled for different kernels, by adding enough information
1244 to the modules to (hopefully) spot any changes which would
1245 make them incompatible with the kernel you are running. If
1246 unsure, say N.
1247
1248config MODULE_SRCVERSION_ALL
1249 bool "Source checksum for all modules"
1da177e4
LT
1250 help
1251 Modules which contain a MODULE_VERSION get an extra "srcversion"
1252 field inserted into their modinfo section, which contains a
1253 sum of the source files which made it. This helps maintainers
1254 see exactly which source was used to build a module (since
1255 others sometimes change the module source without updating
1256 the version). With this option, such a "srcversion" field
1257 will be created for all modules. If unsure, say N.
1258
0b0de144
RD
1259endif # MODULES
1260
98a79d6a
RR
1261config INIT_ALL_POSSIBLE
1262 bool
1263 help
1264 Back when each arch used to define their own cpu_online_map and
1265 cpu_possible_map, some of them chose to initialize cpu_possible_map
1266 with all 1s, and others with all 0s. When they were centralised,
1267 it was better to provide this option than to break all the archs
692105b8 1268 and have several arch maintainers pursuing me down dark alleys.
98a79d6a 1269
1da177e4
LT
1270config STOP_MACHINE
1271 bool
1272 default y
1273 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1274 help
1275 Need stop_machine() primitive.
3a65dfe8 1276
3a65dfe8 1277source "block/Kconfig"
e98c3202
AK
1278
1279config PREEMPT_NOTIFIERS
1280 bool
e260be67 1281
16295bec
SK
1282config PADATA
1283 depends on SMP
1284 bool
1285
6beb0009 1286source "kernel/Kconfig.locks"