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47 drivers that have been replaced by something else, and/or are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