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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
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24config HAVE_IRQ_WORK
25 bool
26
27config IRQ_WORK
28 bool
29 depends on HAVE_IRQ_WORK
30
ff0cfc66 31menu "General setup"
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32
33config EXPERIMENTAL
34 bool "Prompt for development and/or incomplete code/drivers"
35 ---help---
36 Some of the various things that Linux supports (such as network
37 drivers, file systems, network protocols, etc.) can be in a state
38 of development where the functionality, stability, or the level of
39 testing is not yet high enough for general use. This is usually
40 known as the "alpha-test" phase among developers. If a feature is
41 currently in alpha-test, then the developers usually discourage
42 uninformed widespread use of this feature by the general public to
43 avoid "Why doesn't this work?" type mail messages. However, active
44 testing and use of these systems is welcomed. Just be aware that it
45 may not meet the normal level of reliability or it may fail to work
46 in some special cases. Detailed bug reports from people familiar
47 with the kernel internals are usually welcomed by the developers
48 (before submitting bug reports, please read the documents
49 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
50 <file:Documentation/BUG-HUNTING>, and
51 <file:Documentation/oops-tracing.txt> in the kernel source).
52
53 This option will also make obsoleted drivers available. These are
54 drivers that have been replaced by something else, and/or are
55 scheduled to be removed in a future kernel release.
56
57 Unless you intend to help test and develop a feature or driver that
58 falls into this category, or you have a situation that requires
59 using these features, you should probably say N here, which will
60 cause the configurator to present you with fewer choices. If
61 you say Y here, you will be offered the choice of using features or
62 drivers that are currently considered to be in the alpha-test phase.
63
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64config BROKEN
65 bool
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66
67config BROKEN_ON_SMP
68 bool
69 depends on BROKEN || !SMP
70 default y
71
72config LOCK_KERNEL
73 bool
6de5bd12 74 depends on (SMP || PREEMPT) && BKL
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75 default y
76
77config INIT_ENV_ARG_LIMIT
78 int
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79 default 32 if !UML
80 default 128 if UML
1da177e4 81 help
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82 Maximum of each of the number of arguments and environment
83 variables passed to init from the kernel command line.
1da177e4 84
1da177e4 85
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86config CROSS_COMPILE
87 string "Cross-compiler tool prefix"
88 help
89 Same as running 'make CROSS_COMPILE=prefix-' but stored for
90 default make runs in this kernel build directory. You don't
91 need to set this unless you want the configured kernel build
92 directory to select the cross-compiler automatically.
93
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94config LOCALVERSION
95 string "Local version - append to kernel release"
96 help
97 Append an extra string to the end of your kernel version.
98 This will show up when you type uname, for example.
99 The string you set here will be appended after the contents of
100 any files with a filename matching localversion* in your
101 object and source tree, in that order. Your total string can
102 be a maximum of 64 characters.
103
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104config LOCALVERSION_AUTO
105 bool "Automatically append version information to the version string"
106 default y
107 help
108 This will try to automatically determine if the current tree is a
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109 release tree by looking for git tags that belong to the current
110 top of tree revision.
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111
112 A string of the format -gxxxxxxxx will be added to the localversion
6e5a5420 113 if a git-based tree is found. The string generated by this will be
aaebf433 114 appended after any matching localversion* files, and after the value
6e5a5420 115 set in CONFIG_LOCALVERSION.
aaebf433 116
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117 (The actual string used here is the first eight characters produced
118 by running the command:
119
120 $ git rev-parse --verify HEAD
121
122 which is done within the script "scripts/setlocalversion".)
aaebf433 123
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124config HAVE_KERNEL_GZIP
125 bool
126
127config HAVE_KERNEL_BZIP2
128 bool
129
130config HAVE_KERNEL_LZMA
131 bool
132
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133config HAVE_KERNEL_LZO
134 bool
135
30d65dbf 136choice
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137 prompt "Kernel compression mode"
138 default KERNEL_GZIP
7dd65feb 139 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_LZO
2e9f3bdd 140 help
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141 The linux kernel is a kind of self-extracting executable.
142 Several compression algorithms are available, which differ
143 in efficiency, compression and decompression speed.
144 Compression speed is only relevant when building a kernel.
145 Decompression speed is relevant at each boot.
146
147 If you have any problems with bzip2 or lzma compressed
148 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
149 version of this functionality (bzip2 only), for 2.4, was
150 supplied by Christian Ludwig)
151
152 High compression options are mostly useful for users, who
153 are low on disk space (embedded systems), but for whom ram
154 size matters less.
155
156 If in doubt, select 'gzip'
157
158config KERNEL_GZIP
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159 bool "Gzip"
160 depends on HAVE_KERNEL_GZIP
161 help
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162 The old and tried gzip compression. It provides a good balance
163 between compression ratio and decompression speed.
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164
165config KERNEL_BZIP2
166 bool "Bzip2"
2e9f3bdd 167 depends on HAVE_KERNEL_BZIP2
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168 help
169 Its compression ratio and speed is intermediate.
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170 Decompression speed is slowest among the three. The kernel
171 size is about 10% smaller with bzip2, in comparison to gzip.
172 Bzip2 uses a large amount of memory. For modern kernels you
173 will need at least 8MB RAM or more for booting.
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174
175config KERNEL_LZMA
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176 bool "LZMA"
177 depends on HAVE_KERNEL_LZMA
178 help
179 The most recent compression algorithm.
180 Its ratio is best, decompression speed is between the other
181 two. Compression is slowest. The kernel size is about 33%
182 smaller with LZMA in comparison to gzip.
30d65dbf 183
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184config KERNEL_LZO
185 bool "LZO"
186 depends on HAVE_KERNEL_LZO
187 help
188 Its compression ratio is the poorest among the 4. The kernel
681b3049 189 size is about 10% bigger than gzip; however its speed
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190 (both compression and decompression) is the fastest.
191
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192endchoice
193
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194config SWAP
195 bool "Support for paging of anonymous memory (swap)"
9361401e 196 depends on MMU && BLOCK
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197 default y
198 help
199 This option allows you to choose whether you want to have support
92c3504e 200 for so called swap devices or swap files in your kernel that are
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201 used to provide more virtual memory than the actual RAM present
202 in your computer. If unsure say Y.
203
204config SYSVIPC
205 bool "System V IPC"
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206 ---help---
207 Inter Process Communication is a suite of library functions and
208 system calls which let processes (running programs) synchronize and
209 exchange information. It is generally considered to be a good thing,
210 and some programs won't run unless you say Y here. In particular, if
211 you want to run the DOS emulator dosemu under Linux (read the
212 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
213 you'll need to say Y here.
214
215 You can find documentation about IPC with "info ipc" and also in
216 section 6.4 of the Linux Programmer's Guide, available from
217 <http://www.tldp.org/guides.html>.
218
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219config SYSVIPC_SYSCTL
220 bool
221 depends on SYSVIPC
222 depends on SYSCTL
223 default y
224
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225config POSIX_MQUEUE
226 bool "POSIX Message Queues"
227 depends on NET && EXPERIMENTAL
228 ---help---
229 POSIX variant of message queues is a part of IPC. In POSIX message
230 queues every message has a priority which decides about succession
231 of receiving it by a process. If you want to compile and run
232 programs written e.g. for Solaris with use of its POSIX message
b0e37650 233 queues (functions mq_*) say Y here.
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234
235 POSIX message queues are visible as a filesystem called 'mqueue'
236 and can be mounted somewhere if you want to do filesystem
237 operations on message queues.
238
239 If unsure, say Y.
240
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241config POSIX_MQUEUE_SYSCTL
242 bool
243 depends on POSIX_MQUEUE
244 depends on SYSCTL
245 default y
246
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247config BSD_PROCESS_ACCT
248 bool "BSD Process Accounting"
249 help
250 If you say Y here, a user level program will be able to instruct the
251 kernel (via a special system call) to write process accounting
252 information to a file: whenever a process exits, information about
253 that process will be appended to the file by the kernel. The
254 information includes things such as creation time, owning user,
255 command name, memory usage, controlling terminal etc. (the complete
256 list is in the struct acct in <file:include/linux/acct.h>). It is
257 up to the user level program to do useful things with this
258 information. This is generally a good idea, so say Y.
259
260config BSD_PROCESS_ACCT_V3
261 bool "BSD Process Accounting version 3 file format"
262 depends on BSD_PROCESS_ACCT
263 default n
264 help
265 If you say Y here, the process accounting information is written
266 in a new file format that also logs the process IDs of each
267 process and it's parent. Note that this file format is incompatible
268 with previous v0/v1/v2 file formats, so you will need updated tools
269 for processing it. A preliminary version of these tools is available
37a4c940 270 at <http://www.gnu.org/software/acct/>.
1da177e4 271
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272config TASKSTATS
273 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
274 depends on NET
275 default n
276 help
277 Export selected statistics for tasks/processes through the
278 generic netlink interface. Unlike BSD process accounting, the
279 statistics are available during the lifetime of tasks/processes as
280 responses to commands. Like BSD accounting, they are sent to user
281 space on task exit.
282
283 Say N if unsure.
284
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285config TASK_DELAY_ACCT
286 bool "Enable per-task delay accounting (EXPERIMENTAL)"
6f44993f 287 depends on TASKSTATS
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288 help
289 Collect information on time spent by a task waiting for system
290 resources like cpu, synchronous block I/O completion and swapping
291 in pages. Such statistics can help in setting a task's priorities
292 relative to other tasks for cpu, io, rss limits etc.
293
294 Say N if unsure.
295
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296config TASK_XACCT
297 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
298 depends on TASKSTATS
299 help
300 Collect extended task accounting data and send the data
301 to userland for processing over the taskstats interface.
302
303 Say N if unsure.
304
305config TASK_IO_ACCOUNTING
306 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
307 depends on TASK_XACCT
308 help
309 Collect information on the number of bytes of storage I/O which this
310 task has caused.
311
312 Say N if unsure.
313
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314config AUDIT
315 bool "Auditing support"
804a6a49 316 depends on NET
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317 help
318 Enable auditing infrastructure that can be used with another
319 kernel subsystem, such as SELinux (which requires this for
320 logging of avc messages output). Does not do system-call
321 auditing without CONFIG_AUDITSYSCALL.
322
323config AUDITSYSCALL
324 bool "Enable system-call auditing support"
022382a5 325 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
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326 default y if SECURITY_SELINUX
327 help
328 Enable low-overhead system-call auditing infrastructure that
329 can be used independently or with another kernel subsystem,
67640b60 330 such as SELinux.
1da177e4 331
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332config AUDIT_WATCH
333 def_bool y
334 depends on AUDITSYSCALL
335 select FSNOTIFY
1da177e4 336
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337config AUDIT_TREE
338 def_bool y
63c882a0 339 depends on AUDITSYSCALL
28a3a7eb 340 select FSNOTIFY
74c3cbe3 341
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342source "kernel/irq/Kconfig"
343
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344menu "RCU Subsystem"
345
346choice
347 prompt "RCU Implementation"
31c9a24e 348 default TREE_RCU
c903ff83 349
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350config TREE_RCU
351 bool "Tree-based hierarchical RCU"
687d7a96 352 depends on !PREEMPT && SMP
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353 help
354 This option selects the RCU implementation that is
355 designed for very large SMP system with hundreds or
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356 thousands of CPUs. It also scales down nicely to
357 smaller systems.
c903ff83 358
f41d911f 359config TREE_PREEMPT_RCU
a57eb940 360 bool "Preemptible tree-based hierarchical RCU"
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361 depends on PREEMPT
362 help
363 This option selects the RCU implementation that is
364 designed for very large SMP systems with hundreds or
365 thousands of CPUs, but for which real-time response
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366 is also required. It also scales down nicely to
367 smaller systems.
f41d911f 368
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369config TINY_RCU
370 bool "UP-only small-memory-footprint RCU"
371 depends on !SMP
372 help
373 This option selects the RCU implementation that is
374 designed for UP systems from which real-time response
375 is not required. This option greatly reduces the
376 memory footprint of RCU.
377
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378config TINY_PREEMPT_RCU
379 bool "Preemptible UP-only small-memory-footprint RCU"
380 depends on !SMP && PREEMPT
381 help
382 This option selects the RCU implementation that is designed
383 for real-time UP systems. This option greatly reduces the
384 memory footprint of RCU.
385
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386endchoice
387
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388config PREEMPT_RCU
389 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
390 help
391 This option enables preemptible-RCU code that is common between
392 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
393
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394config RCU_TRACE
395 bool "Enable tracing for RCU"
6b3ef48a 396 depends on TREE_RCU || TREE_PREEMPT_RCU
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397 help
398 This option provides tracing in RCU which presents stats
399 in debugfs for debugging RCU implementation.
400
401 Say Y here if you want to enable RCU tracing
402 Say N if you are unsure.
403
404config RCU_FANOUT
405 int "Tree-based hierarchical RCU fanout value"
406 range 2 64 if 64BIT
407 range 2 32 if !64BIT
f41d911f 408 depends on TREE_RCU || TREE_PREEMPT_RCU
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409 default 64 if 64BIT
410 default 32 if !64BIT
411 help
412 This option controls the fanout of hierarchical implementations
413 of RCU, allowing RCU to work efficiently on machines with
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414 large numbers of CPUs. This value must be at least the fourth
415 root of NR_CPUS, which allows NR_CPUS to be insanely large.
416 The default value of RCU_FANOUT should be used for production
417 systems, but if you are stress-testing the RCU implementation
418 itself, small RCU_FANOUT values allow you to test large-system
419 code paths on small(er) systems.
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420
421 Select a specific number if testing RCU itself.
422 Take the default if unsure.
423
424config RCU_FANOUT_EXACT
425 bool "Disable tree-based hierarchical RCU auto-balancing"
f41d911f 426 depends on TREE_RCU || TREE_PREEMPT_RCU
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427 default n
428 help
429 This option forces use of the exact RCU_FANOUT value specified,
430 regardless of imbalances in the hierarchy. This is useful for
431 testing RCU itself, and might one day be useful on systems with
432 strong NUMA behavior.
433
434 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
435
436 Say N if unsure.
437
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438config RCU_FAST_NO_HZ
439 bool "Accelerate last non-dyntick-idle CPU's grace periods"
440 depends on TREE_RCU && NO_HZ && SMP
441 default n
442 help
443 This option causes RCU to attempt to accelerate grace periods
444 in order to allow the final CPU to enter dynticks-idle state
445 more quickly. On the other hand, this option increases the
446 overhead of the dynticks-idle checking, particularly on systems
447 with large numbers of CPUs.
448
449 Say Y if energy efficiency is critically important, particularly
450 if you have relatively few CPUs.
451
452 Say N if you are unsure.
453
c903ff83 454config TREE_RCU_TRACE
f41d911f 455 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
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456 select DEBUG_FS
457 help
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458 This option provides tracing for the TREE_RCU and
459 TREE_PREEMPT_RCU implementations, permitting Makefile to
460 trivially select kernel/rcutree_trace.c.
c903ff83 461
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462endmenu # "RCU Subsystem"
463
1da177e4 464config IKCONFIG
f2443ab6 465 tristate "Kernel .config support"
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466 ---help---
467 This option enables the complete Linux kernel ".config" file
468 contents to be saved in the kernel. It provides documentation
469 of which kernel options are used in a running kernel or in an
470 on-disk kernel. This information can be extracted from the kernel
471 image file with the script scripts/extract-ikconfig and used as
472 input to rebuild the current kernel or to build another kernel.
473 It can also be extracted from a running kernel by reading
474 /proc/config.gz if enabled (below).
475
476config IKCONFIG_PROC
477 bool "Enable access to .config through /proc/config.gz"
478 depends on IKCONFIG && PROC_FS
479 ---help---
480 This option enables access to the kernel configuration file
481 through /proc/config.gz.
482
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483config LOG_BUF_SHIFT
484 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
485 range 12 21
f17a32e9 486 default 17
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487 help
488 Select kernel log buffer size as a power of 2.
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489 Examples:
490 17 => 128 KB
491 16 => 64 KB
492 15 => 32 KB
493 14 => 16 KB
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494 13 => 8 KB
495 12 => 4 KB
496
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497#
498# Architectures with an unreliable sched_clock() should select this:
499#
500config HAVE_UNSTABLE_SCHED_CLOCK
501 bool
502
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503menuconfig CGROUPS
504 boolean "Control Group support"
0dea1168 505 depends on EVENTFD
5cdc38f9 506 help
23964d2d 507 This option adds support for grouping sets of processes together, for
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508 use with process control subsystems such as Cpusets, CFS, memory
509 controls or device isolation.
510 See
5cdc38f9 511 - Documentation/scheduler/sched-design-CFS.txt (CFS)
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512 - Documentation/cgroups/ (features for grouping, isolation
513 and resource control)
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514
515 Say N if unsure.
516
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517if CGROUPS
518
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519config CGROUP_DEBUG
520 bool "Example debug cgroup subsystem"
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521 default n
522 help
523 This option enables a simple cgroup subsystem that
524 exports useful debugging information about the cgroups
23964d2d 525 framework.
5cdc38f9 526
23964d2d 527 Say N if unsure.
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528
529config CGROUP_NS
23964d2d 530 bool "Namespace cgroup subsystem"
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531 help
532 Provides a simple namespace cgroup subsystem to
533 provide hierarchical naming of sets of namespaces,
534 for instance virtual servers and checkpoint/restart
535 jobs.
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536
537config CGROUP_FREEZER
23964d2d 538 bool "Freezer cgroup subsystem"
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539 help
540 Provides a way to freeze and unfreeze all tasks in a
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541 cgroup.
542
543config CGROUP_DEVICE
544 bool "Device controller for cgroups"
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545 help
546 Provides a cgroup implementing whitelists for devices which
547 a process in the cgroup can mknod or open.
548
549config CPUSETS
550 bool "Cpuset support"
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551 help
552 This option will let you create and manage CPUSETs which
553 allow dynamically partitioning a system into sets of CPUs and
554 Memory Nodes and assigning tasks to run only within those sets.
555 This is primarily useful on large SMP or NUMA systems.
556
557 Say N if unsure.
558
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559config PROC_PID_CPUSET
560 bool "Include legacy /proc/<pid>/cpuset file"
561 depends on CPUSETS
562 default y
563
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564config CGROUP_CPUACCT
565 bool "Simple CPU accounting cgroup subsystem"
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566 help
567 Provides a simple Resource Controller for monitoring the
23964d2d 568 total CPU consumed by the tasks in a cgroup.
d842de87 569
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570config RESOURCE_COUNTERS
571 bool "Resource counters"
572 help
573 This option enables controller independent resource accounting
23964d2d 574 infrastructure that works with cgroups.
e552b661 575
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576config CGROUP_MEM_RES_CTLR
577 bool "Memory Resource Controller for Control Groups"
79ae9c29 578 depends on RESOURCE_COUNTERS
cf475ad2 579 select MM_OWNER
00f0b825 580 help
84ad6d70 581 Provides a memory resource controller that manages both anonymous
21acb9ca 582 memory and page cache. (See Documentation/cgroups/memory.txt)
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583
584 Note that setting this option increases fixed memory overhead
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585 associated with each page of memory in the system. By this,
586 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
587 usage tracking struct at boot. Total amount of this is printed out
588 at boot.
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589
590 Only enable when you're ok with these trade offs and really
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591 sure you need the memory resource controller. Even when you enable
592 this, you can set "cgroup_disable=memory" at your boot option to
593 disable memory resource controller and you can avoid overheads.
c9d5409f 594 (and lose benefits of memory resource controller)
00f0b825 595
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596 This config option also selects MM_OWNER config option, which
597 could in turn add some fork/exit overhead.
598
c077719b 599config CGROUP_MEM_RES_CTLR_SWAP
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600 bool "Memory Resource Controller Swap Extension"
601 depends on CGROUP_MEM_RES_CTLR && SWAP
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602 help
603 Add swap management feature to memory resource controller. When you
604 enable this, you can limit mem+swap usage per cgroup. In other words,
605 when you disable this, memory resource controller has no cares to
606 usage of swap...a process can exhaust all of the swap. This extension
607 is useful when you want to avoid exhaustion swap but this itself
608 adds more overheads and consumes memory for remembering information.
609 Especially if you use 32bit system or small memory system, please
610 be careful about enabling this. When memory resource controller
611 is disabled by boot option, this will be automatically disabled and
612 there will be no overhead from this. Even when you set this config=y,
613 if boot option "noswapaccount" is set, swap will not be accounted.
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614 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
615 size is 4096bytes, 512k per 1Gbytes of swap.
c077719b 616
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617menuconfig CGROUP_SCHED
618 bool "Group CPU scheduler"
79ae9c29 619 depends on EXPERIMENTAL
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620 default n
621 help
622 This feature lets CPU scheduler recognize task groups and control CPU
623 bandwidth allocation to such task groups. It uses cgroups to group
624 tasks.
625
626if CGROUP_SCHED
627config FAIR_GROUP_SCHED
628 bool "Group scheduling for SCHED_OTHER"
629 depends on CGROUP_SCHED
630 default CGROUP_SCHED
631
632config RT_GROUP_SCHED
633 bool "Group scheduling for SCHED_RR/FIFO"
634 depends on EXPERIMENTAL
635 depends on CGROUP_SCHED
636 default n
637 help
638 This feature lets you explicitly allocate real CPU bandwidth
32bd7eb5 639 to task groups. If enabled, it will also make it impossible to
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640 schedule realtime tasks for non-root users until you allocate
641 realtime bandwidth for them.
642 See Documentation/scheduler/sched-rt-group.txt for more information.
643
644endif #CGROUP_SCHED
645
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646config BLK_CGROUP
647 tristate "Block IO controller"
79ae9c29 648 depends on BLOCK
afc24d49
VG
649 default n
650 ---help---
651 Generic block IO controller cgroup interface. This is the common
652 cgroup interface which should be used by various IO controlling
653 policies.
654
655 Currently, CFQ IO scheduler uses it to recognize task groups and
656 control disk bandwidth allocation (proportional time slice allocation)
e43473b7
VG
657 to such task groups. It is also used by bio throttling logic in
658 block layer to implement upper limit in IO rates on a device.
afc24d49
VG
659
660 This option only enables generic Block IO controller infrastructure.
e43473b7
VG
661 One needs to also enable actual IO controlling logic/policy. For
662 enabling proportional weight division of disk bandwidth in CFQ seti
663 CONFIG_CFQ_GROUP_IOSCHED=y and for enabling throttling policy set
664 CONFIG_BLK_THROTTLE=y.
afc24d49
VG
665
666 See Documentation/cgroups/blkio-controller.txt for more information.
667
668config DEBUG_BLK_CGROUP
669 bool "Enable Block IO controller debugging"
670 depends on BLK_CGROUP
671 default n
672 ---help---
673 Enable some debugging help. Currently it exports additional stat
674 files in a cgroup which can be useful for debugging.
675
23964d2d 676endif # CGROUPS
c077719b 677
8dd2a82c 678menuconfig NAMESPACES
c5289a69
PE
679 bool "Namespaces support" if EMBEDDED
680 default !EMBEDDED
681 help
682 Provides the way to make tasks work with different objects using
683 the same id. For example same IPC id may refer to different objects
684 or same user id or pid may refer to different tasks when used in
685 different namespaces.
686
8dd2a82c
DL
687if NAMESPACES
688
58bfdd6d
PE
689config UTS_NS
690 bool "UTS namespace"
17a6d441 691 default y
58bfdd6d
PE
692 help
693 In this namespace tasks see different info provided with the
694 uname() system call
695
ae5e1b22
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696config IPC_NS
697 bool "IPC namespace"
8dd2a82c 698 depends on (SYSVIPC || POSIX_MQUEUE)
17a6d441 699 default y
ae5e1b22
PE
700 help
701 In this namespace tasks work with IPC ids which correspond to
614b84cf 702 different IPC objects in different namespaces.
ae5e1b22 703
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704config USER_NS
705 bool "User namespace (EXPERIMENTAL)"
8dd2a82c 706 depends on EXPERIMENTAL
17a6d441 707 default y
aee16ce7
PE
708 help
709 This allows containers, i.e. vservers, to use user namespaces
710 to provide different user info for different servers.
711 If unsure, say N.
712
74bd59bb 713config PID_NS
9bd38c2c 714 bool "PID Namespaces"
17a6d441 715 default y
74bd59bb 716 help
12d2b8f9 717 Support process id namespaces. This allows having multiple
692105b8 718 processes with the same pid as long as they are in different
74bd59bb
PE
719 pid namespaces. This is a building block of containers.
720
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MH
721config NET_NS
722 bool "Network namespace"
8dd2a82c 723 depends on NET
17a6d441 724 default y
d6eb633f
MH
725 help
726 Allow user space to create what appear to be multiple instances
727 of the network stack.
728
8dd2a82c
DL
729endif # NAMESPACES
730
7af37bec
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731config MM_OWNER
732 bool
733
734config SYSFS_DEPRECATED
735 bool "enable deprecated sysfs features to support old userspace tools"
736 depends on SYSFS
737 default n
738 help
739 This option adds code that switches the layout of the "block" class
740 devices, to not show up in /sys/class/block/, but only in
741 /sys/block/.
742
743 This switch is only active when the sysfs.deprecated=1 boot option is
744 passed or the SYSFS_DEPRECATED_V2 option is set.
745
746 This option allows new kernels to run on old distributions and tools,
747 which might get confused by /sys/class/block/. Since 2007/2008 all
748 major distributions and tools handle this just fine.
749
750 Recent distributions and userspace tools after 2009/2010 depend on
751 the existence of /sys/class/block/, and will not work with this
752 option enabled.
753
754 Only if you are using a new kernel on an old distribution, you might
755 need to say Y here.
756
757config SYSFS_DEPRECATED_V2
758 bool "enabled deprecated sysfs features by default"
759 default n
760 depends on SYSFS
761 depends on SYSFS_DEPRECATED
762 help
763 Enable deprecated sysfs by default.
764
765 See the CONFIG_SYSFS_DEPRECATED option for more details about this
766 option.
767
768 Only if you are using a new kernel on an old distribution, you might
769 need to say Y here. Even then, odds are you would not need it
770 enabled, you can always pass the boot option if absolutely necessary.
771
772config RELAY
773 bool "Kernel->user space relay support (formerly relayfs)"
774 help
775 This option enables support for relay interface support in
776 certain file systems (such as debugfs).
777 It is designed to provide an efficient mechanism for tools and
778 facilities to relay large amounts of data from kernel space to
779 user space.
780
781 If unsure, say N.
782
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DG
783config BLK_DEV_INITRD
784 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
785 depends on BROKEN || !FRV
786 help
787 The initial RAM filesystem is a ramfs which is loaded by the
788 boot loader (loadlin or lilo) and that is mounted as root
789 before the normal boot procedure. It is typically used to
790 load modules needed to mount the "real" root file system,
791 etc. See <file:Documentation/initrd.txt> for details.
792
793 If RAM disk support (BLK_DEV_RAM) is also included, this
794 also enables initial RAM disk (initrd) support and adds
795 15 Kbytes (more on some other architectures) to the kernel size.
796
797 If unsure say Y.
798
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JPS
799if BLK_DEV_INITRD
800
dbec4866
SR
801source "usr/Kconfig"
802
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JPS
803endif
804
c45b4f1f 805config CC_OPTIMIZE_FOR_SIZE
96fffeb4 806 bool "Optimize for size"
c45b4f1f 807 default y
c45b4f1f
LT
808 help
809 Enabling this option will pass "-Os" instead of "-O2" to gcc
810 resulting in a smaller kernel.
811
775a7229 812 If unsure, say Y.
c45b4f1f 813
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RD
814config SYSCTL
815 bool
816
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RD
817config ANON_INODES
818 bool
819
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820menuconfig EMBEDDED
821 bool "Configure standard kernel features (for small systems)"
822 help
823 This option allows certain base kernel options and settings
824 to be disabled or tweaked. This is for specialized
825 environments which can tolerate a "non-standard" kernel.
826 Only use this if you really know what you are doing.
827
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CE
828config UID16
829 bool "Enable 16-bit UID system calls" if EMBEDDED
09337f50 830 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
ae81f9e3
CE
831 default y
832 help
833 This enables the legacy 16-bit UID syscall wrappers.
834
b89a8171 835config SYSCTL_SYSCALL
0847062a 836 bool "Sysctl syscall support" if EMBEDDED
26a7034b 837 depends on PROC_SYSCTL
13bb7e37 838 default y
b89a8171 839 select SYSCTL
ae81f9e3 840 ---help---
13bb7e37
EB
841 sys_sysctl uses binary paths that have been found challenging
842 to properly maintain and use. The interface in /proc/sys
843 using paths with ascii names is now the primary path to this
844 information.
b89a8171 845
13bb7e37
EB
846 Almost nothing using the binary sysctl interface so if you are
847 trying to save some space it is probably safe to disable this,
848 making your kernel marginally smaller.
b89a8171 849
13bb7e37 850 If unsure say Y here.
ae81f9e3 851
1da177e4 852config KALLSYMS
979c6a1e 853 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
1da177e4
LT
854 default y
855 help
856 Say Y here to let the kernel print out symbolic crash information and
857 symbolic stack backtraces. This increases the size of the kernel
858 somewhat, as all symbols have to be loaded into the kernel image.
859
860config KALLSYMS_ALL
861 bool "Include all symbols in kallsyms"
862 depends on DEBUG_KERNEL && KALLSYMS
863 help
864 Normally kallsyms only contains the symbols of functions, for nicer
865 OOPS messages. Some debuggers can use kallsyms for other
f9f97bc0
JJ
866 symbols too: say Y here to include all symbols, if you need them
867 and you don't care about adding 300k to the size of your kernel.
1da177e4
LT
868
869 Say N.
870
871config KALLSYMS_EXTRA_PASS
872 bool "Do an extra kallsyms pass"
873 depends on KALLSYMS
874 help
875 If kallsyms is not working correctly, the build will fail with
876 inconsistent kallsyms data. If that occurs, log a bug report and
877 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
878 Always say N here unless you find a bug in kallsyms, which must be
879 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
880 you wait for kallsyms to be fixed.
881
d59745ce 882
712f47ce
GKH
883config HOTPLUG
884 bool "Support for hot-pluggable devices" if EMBEDDED
885 default y
886 help
887 This option is provided for the case where no hotplug or uevent
888 capabilities is wanted by the kernel. You should only consider
889 disabling this option for embedded systems that do not use modules, a
890 dynamic /dev tree, or dynamic device discovery. Just say Y.
891
d59745ce
MM
892config PRINTK
893 default y
894 bool "Enable support for printk" if EMBEDDED
895 help
896 This option enables normal printk support. Removing it
897 eliminates most of the message strings from the kernel image
898 and makes the kernel more or less silent. As this makes it
899 very difficult to diagnose system problems, saying N here is
900 strongly discouraged.
901
c8538a7a
MM
902config BUG
903 bool "BUG() support" if EMBEDDED
904 default y
905 help
906 Disabling this option eliminates support for BUG and WARN, reducing
907 the size of your kernel image and potentially quietly ignoring
908 numerous fatal conditions. You should only consider disabling this
909 option for embedded systems with no facilities for reporting errors.
910 Just say Y.
911
708e9a79
MM
912config ELF_CORE
913 default y
914 bool "Enable ELF core dumps" if EMBEDDED
915 help
916 Enable support for generating core dumps. Disabling saves about 4k.
917
e5e1d3cb
SS
918config PCSPKR_PLATFORM
919 bool "Enable PC-Speaker support" if EMBEDDED
920 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
921 default y
922 help
923 This option allows to disable the internal PC-Speaker
924 support, saving some memory.
925
1da177e4
LT
926config BASE_FULL
927 default y
928 bool "Enable full-sized data structures for core" if EMBEDDED
929 help
930 Disabling this option reduces the size of miscellaneous core
931 kernel data structures. This saves memory on small machines,
932 but may reduce performance.
933
934config FUTEX
935 bool "Enable futex support" if EMBEDDED
936 default y
23f78d4a 937 select RT_MUTEXES
1da177e4
LT
938 help
939 Disabling this option will cause the kernel to be built without
940 support for "fast userspace mutexes". The resulting kernel may not
941 run glibc-based applications correctly.
942
943config EPOLL
944 bool "Enable eventpoll support" if EMBEDDED
945 default y
448e3cee 946 select ANON_INODES
1da177e4
LT
947 help
948 Disabling this option will cause the kernel to be built without
949 support for epoll family of system calls.
950
fba2afaa
DL
951config SIGNALFD
952 bool "Enable signalfd() system call" if EMBEDDED
448e3cee 953 select ANON_INODES
fba2afaa
DL
954 default y
955 help
956 Enable the signalfd() system call that allows to receive signals
957 on a file descriptor.
958
959 If unsure, say Y.
960
b215e283
DL
961config TIMERFD
962 bool "Enable timerfd() system call" if EMBEDDED
448e3cee 963 select ANON_INODES
b215e283
DL
964 default y
965 help
966 Enable the timerfd() system call that allows to receive timer
967 events on a file descriptor.
968
969 If unsure, say Y.
970
e1ad7468
DL
971config EVENTFD
972 bool "Enable eventfd() system call" if EMBEDDED
448e3cee 973 select ANON_INODES
e1ad7468
DL
974 default y
975 help
976 Enable the eventfd() system call that allows to receive both
977 kernel notification (ie. KAIO) or userspace notifications.
978
979 If unsure, say Y.
980
1da177e4
LT
981config SHMEM
982 bool "Use full shmem filesystem" if EMBEDDED
983 default y
984 depends on MMU
985 help
986 The shmem is an internal filesystem used to manage shared memory.
987 It is backed by swap and manages resource limits. It is also exported
988 to userspace as tmpfs if TMPFS is enabled. Disabling this
989 option replaces shmem and tmpfs with the much simpler ramfs code,
990 which may be appropriate on small systems without swap.
991
ebf3f09c
TP
992config AIO
993 bool "Enable AIO support" if EMBEDDED
994 default y
995 help
996 This option enables POSIX asynchronous I/O which may by used
997 by some high performance threaded applications. Disabling
998 this option saves about 7k.
999
cdd6c482 1000config HAVE_PERF_EVENTS
0793a61d 1001 bool
018df72d
MF
1002 help
1003 See tools/perf/design.txt for details.
0793a61d 1004
906010b2
PZ
1005config PERF_USE_VMALLOC
1006 bool
1007 help
1008 See tools/perf/design.txt for details
1009
57c0c15b 1010menu "Kernel Performance Events And Counters"
0793a61d 1011
cdd6c482 1012config PERF_EVENTS
57c0c15b
IM
1013 bool "Kernel performance events and counters"
1014 default y if (PROFILING || PERF_COUNTERS)
cdd6c482 1015 depends on HAVE_PERF_EVENTS
4c59e467 1016 select ANON_INODES
e360adbe 1017 select IRQ_WORK
0793a61d 1018 help
57c0c15b
IM
1019 Enable kernel support for various performance events provided
1020 by software and hardware.
0793a61d 1021
dd77038d 1022 Software events are supported either built-in or via the
57c0c15b 1023 use of generic tracepoints.
0793a61d 1024
57c0c15b
IM
1025 Most modern CPUs support performance events via performance
1026 counter registers. These registers count the number of certain
0793a61d
TG
1027 types of hw events: such as instructions executed, cachemisses
1028 suffered, or branches mis-predicted - without slowing down the
1029 kernel or applications. These registers can also trigger interrupts
1030 when a threshold number of events have passed - and can thus be
1031 used to profile the code that runs on that CPU.
1032
57c0c15b 1033 The Linux Performance Event subsystem provides an abstraction of
dd77038d 1034 these software and hardware event capabilities, available via a
57c0c15b 1035 system call and used by the "perf" utility in tools/perf/. It
0793a61d
TG
1036 provides per task and per CPU counters, and it provides event
1037 capabilities on top of those.
1038
1039 Say Y if unsure.
1040
57c0c15b
IM
1041config PERF_COUNTERS
1042 bool "Kernel performance counters (old config option)"
1043 depends on HAVE_PERF_EVENTS
1044 help
1045 This config has been obsoleted by the PERF_EVENTS
1046 config option - please see that one for details.
1047
1048 It has no effect on the kernel whether you enable
1049 it or not, it is a compatibility placeholder.
1050
1051 Say N if unsure.
1052
906010b2
PZ
1053config DEBUG_PERF_USE_VMALLOC
1054 default n
1055 bool "Debug: use vmalloc to back perf mmap() buffers"
1056 depends on PERF_EVENTS && DEBUG_KERNEL
1057 select PERF_USE_VMALLOC
1058 help
1059 Use vmalloc memory to back perf mmap() buffers.
1060
1061 Mostly useful for debugging the vmalloc code on platforms
1062 that don't require it.
1063
1064 Say N if unsure.
1065
0793a61d
TG
1066endmenu
1067
f8891e5e
CL
1068config VM_EVENT_COUNTERS
1069 default y
1070 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
1071 help
2aea4fb6
PJ
1072 VM event counters are needed for event counts to be shown.
1073 This option allows the disabling of the VM event counters
1074 on EMBEDDED systems. /proc/vmstat will only show page counts
1075 if VM event counters are disabled.
f8891e5e 1076
3d137310
TP
1077config PCI_QUIRKS
1078 default y
61cfc7e4
GU
1079 bool "Enable PCI quirk workarounds" if EMBEDDED
1080 depends on PCI
3d137310
TP
1081 help
1082 This enables workarounds for various PCI chipset
1083 bugs/quirks. Disable this only if your target machine is
1084 unaffected by PCI quirks.
1085
41ecc55b
CL
1086config SLUB_DEBUG
1087 default y
1088 bool "Enable SLUB debugging support" if EMBEDDED
f6acb635 1089 depends on SLUB && SYSFS
41ecc55b
CL
1090 help
1091 SLUB has extensive debug support features. Disabling these can
1092 result in significant savings in code size. This also disables
1093 SLUB sysfs support. /sys/slab will not exist and there will be
1094 no support for cache validation etc.
1095
b943c460
RD
1096config COMPAT_BRK
1097 bool "Disable heap randomization"
1098 default y
1099 help
1100 Randomizing heap placement makes heap exploits harder, but it
1101 also breaks ancient binaries (including anything libc5 based).
1102 This option changes the bootup default to heap randomization
692105b8 1103 disabled, and can be overridden at runtime by setting
b943c460
RD
1104 /proc/sys/kernel/randomize_va_space to 2.
1105
1106 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1107
81819f0f
CL
1108choice
1109 prompt "Choose SLAB allocator"
a0acd820 1110 default SLUB
81819f0f
CL
1111 help
1112 This option allows to select a slab allocator.
1113
1114config SLAB
1115 bool "SLAB"
1116 help
1117 The regular slab allocator that is established and known to work
34013886 1118 well in all environments. It organizes cache hot objects in
02f56210 1119 per cpu and per node queues.
81819f0f
CL
1120
1121config SLUB
81819f0f
CL
1122 bool "SLUB (Unqueued Allocator)"
1123 help
1124 SLUB is a slab allocator that minimizes cache line usage
1125 instead of managing queues of cached objects (SLAB approach).
1126 Per cpu caching is realized using slabs of objects instead
1127 of queues of objects. SLUB can use memory efficiently
02f56210
SA
1128 and has enhanced diagnostics. SLUB is the default choice for
1129 a slab allocator.
81819f0f
CL
1130
1131config SLOB
84a01c2f 1132 depends on EMBEDDED
81819f0f
CL
1133 bool "SLOB (Simple Allocator)"
1134 help
37291458
MM
1135 SLOB replaces the stock allocator with a drastically simpler
1136 allocator. SLOB is generally more space efficient but
1137 does not perform as well on large systems.
81819f0f
CL
1138
1139endchoice
1140
ea637639
JZ
1141config MMAP_ALLOW_UNINITIALIZED
1142 bool "Allow mmapped anonymous memory to be uninitialized"
1143 depends on EMBEDDED && !MMU
1144 default n
1145 help
1146 Normally, and according to the Linux spec, anonymous memory obtained
1147 from mmap() has it's contents cleared before it is passed to
1148 userspace. Enabling this config option allows you to request that
1149 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1150 providing a huge performance boost. If this option is not enabled,
1151 then the flag will be ignored.
1152
1153 This is taken advantage of by uClibc's malloc(), and also by
1154 ELF-FDPIC binfmt's brk and stack allocator.
1155
1156 Because of the obvious security issues, this option should only be
1157 enabled on embedded devices where you control what is run in
1158 userspace. Since that isn't generally a problem on no-MMU systems,
1159 it is normally safe to say Y here.
1160
1161 See Documentation/nommu-mmap.txt for more information.
1162
125e5645 1163config PROFILING
b309a294 1164 bool "Profiling support"
125e5645
MD
1165 help
1166 Say Y here to enable the extended profiling support mechanisms used
1167 by profilers such as OProfile.
1168
5f87f112
IM
1169#
1170# Place an empty function call at each tracepoint site. Can be
1171# dynamically changed for a probe function.
1172#
97e1c18e 1173config TRACEPOINTS
5f87f112 1174 bool
97e1c18e 1175
fb32e03f
MD
1176source "arch/Kconfig"
1177
1da177e4
LT
1178endmenu # General setup
1179
ee7e5516
DES
1180config HAVE_GENERIC_DMA_COHERENT
1181 bool
1182 default n
1183
158a9624
LT
1184config SLABINFO
1185 bool
1186 depends on PROC_FS
0f389ec6 1187 depends on SLAB || SLUB_DEBUG
158a9624
LT
1188 default y
1189
ae81f9e3
CE
1190config RT_MUTEXES
1191 boolean
ae81f9e3 1192
1da177e4
LT
1193config BASE_SMALL
1194 int
1195 default 0 if BASE_FULL
1196 default 1 if !BASE_FULL
1197
66da5733 1198menuconfig MODULES
1da177e4
LT
1199 bool "Enable loadable module support"
1200 help
1201 Kernel modules are small pieces of compiled code which can
1202 be inserted in the running kernel, rather than being
1203 permanently built into the kernel. You use the "modprobe"
1204 tool to add (and sometimes remove) them. If you say Y here,
1205 many parts of the kernel can be built as modules (by
1206 answering M instead of Y where indicated): this is most
1207 useful for infrequently used options which are not required
1208 for booting. For more information, see the man pages for
1209 modprobe, lsmod, modinfo, insmod and rmmod.
1210
1211 If you say Y here, you will need to run "make
1212 modules_install" to put the modules under /lib/modules/
1213 where modprobe can find them (you may need to be root to do
1214 this).
1215
1216 If unsure, say Y.
1217
0b0de144
RD
1218if MODULES
1219
826e4506
LT
1220config MODULE_FORCE_LOAD
1221 bool "Forced module loading"
826e4506
LT
1222 default n
1223 help
91e37a79
RR
1224 Allow loading of modules without version information (ie. modprobe
1225 --force). Forced module loading sets the 'F' (forced) taint flag and
1226 is usually a really bad idea.
826e4506 1227
1da177e4
LT
1228config MODULE_UNLOAD
1229 bool "Module unloading"
1da177e4
LT
1230 help
1231 Without this option you will not be able to unload any
1232 modules (note that some modules may not be unloadable
f7f5b675
DV
1233 anyway), which makes your kernel smaller, faster
1234 and simpler. If unsure, say Y.
1da177e4
LT
1235
1236config MODULE_FORCE_UNLOAD
1237 bool "Forced module unloading"
1238 depends on MODULE_UNLOAD && EXPERIMENTAL
1239 help
1240 This option allows you to force a module to unload, even if the
1241 kernel believes it is unsafe: the kernel will remove the module
1242 without waiting for anyone to stop using it (using the -f option to
1243 rmmod). This is mainly for kernel developers and desperate users.
1244 If unsure, say N.
1245
1da177e4 1246config MODVERSIONS
0d541643 1247 bool "Module versioning support"
1da177e4
LT
1248 help
1249 Usually, you have to use modules compiled with your kernel.
1250 Saying Y here makes it sometimes possible to use modules
1251 compiled for different kernels, by adding enough information
1252 to the modules to (hopefully) spot any changes which would
1253 make them incompatible with the kernel you are running. If
1254 unsure, say N.
1255
1256config MODULE_SRCVERSION_ALL
1257 bool "Source checksum for all modules"
1da177e4
LT
1258 help
1259 Modules which contain a MODULE_VERSION get an extra "srcversion"
1260 field inserted into their modinfo section, which contains a
1261 sum of the source files which made it. This helps maintainers
1262 see exactly which source was used to build a module (since
1263 others sometimes change the module source without updating
1264 the version). With this option, such a "srcversion" field
1265 will be created for all modules. If unsure, say N.
1266
0b0de144
RD
1267endif # MODULES
1268
98a79d6a
RR
1269config INIT_ALL_POSSIBLE
1270 bool
1271 help
1272 Back when each arch used to define their own cpu_online_map and
1273 cpu_possible_map, some of them chose to initialize cpu_possible_map
1274 with all 1s, and others with all 0s. When they were centralised,
1275 it was better to provide this option than to break all the archs
692105b8 1276 and have several arch maintainers pursuing me down dark alleys.
98a79d6a 1277
1da177e4
LT
1278config STOP_MACHINE
1279 bool
1280 default y
1281 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1282 help
1283 Need stop_machine() primitive.
3a65dfe8 1284
3a65dfe8 1285source "block/Kconfig"
e98c3202
AK
1286
1287config PREEMPT_NOTIFIERS
1288 bool
e260be67 1289
16295bec
SK
1290config PADATA
1291 depends on SMP
1292 bool
1293
6beb0009 1294source "kernel/Kconfig.locks"