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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54 drivers that have been replaced by something else, and/or are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"
521 depends on CGROUPS
522 default n
523 help
524 This option enables a simple cgroup subsystem that
525 exports useful debugging information about the cgroups
23964d2d 526 framework.
5cdc38f9 527
23964d2d 528 Say N if unsure.
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529
530config CGROUP_NS
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531 bool "Namespace cgroup subsystem"
532 depends on CGROUPS
533 help
534 Provides a simple namespace cgroup subsystem to
535 provide hierarchical naming of sets of namespaces,
536 for instance virtual servers and checkpoint/restart
537 jobs.
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538
539config CGROUP_FREEZER
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540 bool "Freezer cgroup subsystem"
541 depends on CGROUPS
542 help
543 Provides a way to freeze and unfreeze all tasks in a
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544 cgroup.
545
546config CGROUP_DEVICE
547 bool "Device controller for cgroups"
548 depends on CGROUPS && EXPERIMENTAL
549 help
550 Provides a cgroup implementing whitelists for devices which
551 a process in the cgroup can mknod or open.
552
553config CPUSETS
554 bool "Cpuset support"
db7f47cf 555 depends on CGROUPS
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556 help
557 This option will let you create and manage CPUSETs which
558 allow dynamically partitioning a system into sets of CPUs and
559 Memory Nodes and assigning tasks to run only within those sets.
560 This is primarily useful on large SMP or NUMA systems.
561
562 Say N if unsure.
563
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564config PROC_PID_CPUSET
565 bool "Include legacy /proc/<pid>/cpuset file"
566 depends on CPUSETS
567 default y
568
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569config CGROUP_CPUACCT
570 bool "Simple CPU accounting cgroup subsystem"
571 depends on CGROUPS
572 help
573 Provides a simple Resource Controller for monitoring the
23964d2d 574 total CPU consumed by the tasks in a cgroup.
d842de87 575
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576config RESOURCE_COUNTERS
577 bool "Resource counters"
578 help
579 This option enables controller independent resource accounting
23964d2d 580 infrastructure that works with cgroups.
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581 depends on CGROUPS
582
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583config CGROUP_MEM_RES_CTLR
584 bool "Memory Resource Controller for Control Groups"
585 depends on CGROUPS && RESOURCE_COUNTERS
cf475ad2 586 select MM_OWNER
00f0b825 587 help
84ad6d70 588 Provides a memory resource controller that manages both anonymous
21acb9ca 589 memory and page cache. (See Documentation/cgroups/memory.txt)
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590
591 Note that setting this option increases fixed memory overhead
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592 associated with each page of memory in the system. By this,
593 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
594 usage tracking struct at boot. Total amount of this is printed out
595 at boot.
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596
597 Only enable when you're ok with these trade offs and really
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598 sure you need the memory resource controller. Even when you enable
599 this, you can set "cgroup_disable=memory" at your boot option to
600 disable memory resource controller and you can avoid overheads.
c9d5409f 601 (and lose benefits of memory resource controller)
00f0b825 602
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603 This config option also selects MM_OWNER config option, which
604 could in turn add some fork/exit overhead.
605
c077719b 606config CGROUP_MEM_RES_CTLR_SWAP
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607 bool "Memory Resource Controller Swap Extension"
608 depends on CGROUP_MEM_RES_CTLR && SWAP
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609 help
610 Add swap management feature to memory resource controller. When you
611 enable this, you can limit mem+swap usage per cgroup. In other words,
612 when you disable this, memory resource controller has no cares to
613 usage of swap...a process can exhaust all of the swap. This extension
614 is useful when you want to avoid exhaustion swap but this itself
615 adds more overheads and consumes memory for remembering information.
616 Especially if you use 32bit system or small memory system, please
617 be careful about enabling this. When memory resource controller
618 is disabled by boot option, this will be automatically disabled and
619 there will be no overhead from this. Even when you set this config=y,
620 if boot option "noswapaccount" is set, swap will not be accounted.
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621 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
622 size is 4096bytes, 512k per 1Gbytes of swap.
c077719b 623
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624menuconfig CGROUP_SCHED
625 bool "Group CPU scheduler"
626 depends on EXPERIMENTAL && CGROUPS
627 default n
628 help
629 This feature lets CPU scheduler recognize task groups and control CPU
630 bandwidth allocation to such task groups. It uses cgroups to group
631 tasks.
632
633if CGROUP_SCHED
634config FAIR_GROUP_SCHED
635 bool "Group scheduling for SCHED_OTHER"
636 depends on CGROUP_SCHED
637 default CGROUP_SCHED
638
639config RT_GROUP_SCHED
640 bool "Group scheduling for SCHED_RR/FIFO"
641 depends on EXPERIMENTAL
642 depends on CGROUP_SCHED
643 default n
644 help
645 This feature lets you explicitly allocate real CPU bandwidth
32bd7eb5 646 to task groups. If enabled, it will also make it impossible to
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647 schedule realtime tasks for non-root users until you allocate
648 realtime bandwidth for them.
649 See Documentation/scheduler/sched-rt-group.txt for more information.
650
651endif #CGROUP_SCHED
652
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653config BLK_CGROUP
654 tristate "Block IO controller"
655 depends on CGROUPS && BLOCK
656 default n
657 ---help---
658 Generic block IO controller cgroup interface. This is the common
659 cgroup interface which should be used by various IO controlling
660 policies.
661
662 Currently, CFQ IO scheduler uses it to recognize task groups and
663 control disk bandwidth allocation (proportional time slice allocation)
e43473b7
VG
664 to such task groups. It is also used by bio throttling logic in
665 block layer to implement upper limit in IO rates on a device.
afc24d49
VG
666
667 This option only enables generic Block IO controller infrastructure.
e43473b7
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668 One needs to also enable actual IO controlling logic/policy. For
669 enabling proportional weight division of disk bandwidth in CFQ seti
670 CONFIG_CFQ_GROUP_IOSCHED=y and for enabling throttling policy set
671 CONFIG_BLK_THROTTLE=y.
afc24d49
VG
672
673 See Documentation/cgroups/blkio-controller.txt for more information.
674
675config DEBUG_BLK_CGROUP
676 bool "Enable Block IO controller debugging"
677 depends on BLK_CGROUP
678 default n
679 ---help---
680 Enable some debugging help. Currently it exports additional stat
681 files in a cgroup which can be useful for debugging.
682
23964d2d 683endif # CGROUPS
c077719b 684
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685config MM_OWNER
686 bool
5cdc38f9 687
88a22c98 688config SYSFS_DEPRECATED
9e9868a7 689 bool "enable deprecated sysfs features to support old userspace tools"
9148fe87 690 depends on SYSFS
f6ee649f 691 default n
39aba963 692 help
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693 This option adds code that switches the layout of the "block" class
694 devices, to not show up in /sys/class/block/, but only in
695 /sys/block/.
696
697 This switch is only active when the sysfs.deprecated=1 boot option is
698 passed or the SYSFS_DEPRECATED_V2 option is set.
39aba963
KS
699
700 This option allows new kernels to run on old distributions and tools,
701 which might get confused by /sys/class/block/. Since 2007/2008 all
702 major distributions and tools handle this just fine.
703
704 Recent distributions and userspace tools after 2009/2010 depend on
705 the existence of /sys/class/block/, and will not work with this
706 option enabled.
707
708 Only if you are using a new kernel on an old distribution, you might
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709 need to say Y here.
710
711config SYSFS_DEPRECATED_V2
712 bool "enabled deprecated sysfs features by default"
713 default n
714 depends on SYSFS
715 depends on SYSFS_DEPRECATED
716 help
717 Enable deprecated sysfs by default.
718
719 See the CONFIG_SYSFS_DEPRECATED option for more details about this
720 option.
721
722 Only if you are using a new kernel on an old distribution, you might
723 need to say Y here. Even then, odds are you would not need it
724 enabled, you can always pass the boot option if absolutely necessary.
88a22c98 725
b86ff981
JA
726config RELAY
727 bool "Kernel->user space relay support (formerly relayfs)"
728 help
729 This option enables support for relay interface support in
730 certain file systems (such as debugfs).
731 It is designed to provide an efficient mechanism for tools and
732 facilities to relay large amounts of data from kernel space to
733 user space.
734
735 If unsure, say N.
736
8dd2a82c 737menuconfig NAMESPACES
c5289a69
PE
738 bool "Namespaces support" if EMBEDDED
739 default !EMBEDDED
740 help
741 Provides the way to make tasks work with different objects using
742 the same id. For example same IPC id may refer to different objects
743 or same user id or pid may refer to different tasks when used in
744 different namespaces.
745
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DL
746if NAMESPACES
747
58bfdd6d
PE
748config UTS_NS
749 bool "UTS namespace"
17a6d441 750 default y
58bfdd6d
PE
751 help
752 In this namespace tasks see different info provided with the
753 uname() system call
754
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PE
755config IPC_NS
756 bool "IPC namespace"
8dd2a82c 757 depends on (SYSVIPC || POSIX_MQUEUE)
17a6d441 758 default y
ae5e1b22
PE
759 help
760 In this namespace tasks work with IPC ids which correspond to
614b84cf 761 different IPC objects in different namespaces.
ae5e1b22 762
aee16ce7
PE
763config USER_NS
764 bool "User namespace (EXPERIMENTAL)"
8dd2a82c 765 depends on EXPERIMENTAL
17a6d441 766 default y
aee16ce7
PE
767 help
768 This allows containers, i.e. vservers, to use user namespaces
769 to provide different user info for different servers.
770 If unsure, say N.
771
74bd59bb 772config PID_NS
9bd38c2c 773 bool "PID Namespaces"
17a6d441 774 default y
74bd59bb 775 help
12d2b8f9 776 Support process id namespaces. This allows having multiple
692105b8 777 processes with the same pid as long as they are in different
74bd59bb
PE
778 pid namespaces. This is a building block of containers.
779
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MH
780config NET_NS
781 bool "Network namespace"
8dd2a82c 782 depends on NET
17a6d441 783 default y
d6eb633f
MH
784 help
785 Allow user space to create what appear to be multiple instances
786 of the network stack.
787
8dd2a82c
DL
788endif # NAMESPACES
789
f991633d
DG
790config BLK_DEV_INITRD
791 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
792 depends on BROKEN || !FRV
793 help
794 The initial RAM filesystem is a ramfs which is loaded by the
795 boot loader (loadlin or lilo) and that is mounted as root
796 before the normal boot procedure. It is typically used to
797 load modules needed to mount the "real" root file system,
798 etc. See <file:Documentation/initrd.txt> for details.
799
800 If RAM disk support (BLK_DEV_RAM) is also included, this
801 also enables initial RAM disk (initrd) support and adds
802 15 Kbytes (more on some other architectures) to the kernel size.
803
804 If unsure say Y.
805
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JPS
806if BLK_DEV_INITRD
807
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SR
808source "usr/Kconfig"
809
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JPS
810endif
811
c45b4f1f 812config CC_OPTIMIZE_FOR_SIZE
96fffeb4 813 bool "Optimize for size"
c45b4f1f 814 default y
c45b4f1f
LT
815 help
816 Enabling this option will pass "-Os" instead of "-O2" to gcc
817 resulting in a smaller kernel.
818
775a7229 819 If unsure, say Y.
c45b4f1f 820
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RD
821config SYSCTL
822 bool
823
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RD
824config ANON_INODES
825 bool
826
1da177e4
LT
827menuconfig EMBEDDED
828 bool "Configure standard kernel features (for small systems)"
829 help
830 This option allows certain base kernel options and settings
831 to be disabled or tweaked. This is for specialized
832 environments which can tolerate a "non-standard" kernel.
833 Only use this if you really know what you are doing.
834
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CE
835config UID16
836 bool "Enable 16-bit UID system calls" if EMBEDDED
09337f50 837 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
ae81f9e3
CE
838 default y
839 help
840 This enables the legacy 16-bit UID syscall wrappers.
841
b89a8171 842config SYSCTL_SYSCALL
0847062a 843 bool "Sysctl syscall support" if EMBEDDED
26a7034b 844 depends on PROC_SYSCTL
13bb7e37 845 default y
b89a8171 846 select SYSCTL
ae81f9e3 847 ---help---
13bb7e37
EB
848 sys_sysctl uses binary paths that have been found challenging
849 to properly maintain and use. The interface in /proc/sys
850 using paths with ascii names is now the primary path to this
851 information.
b89a8171 852
13bb7e37
EB
853 Almost nothing using the binary sysctl interface so if you are
854 trying to save some space it is probably safe to disable this,
855 making your kernel marginally smaller.
b89a8171 856
13bb7e37 857 If unsure say Y here.
ae81f9e3 858
1da177e4 859config KALLSYMS
979c6a1e 860 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
1da177e4
LT
861 default y
862 help
863 Say Y here to let the kernel print out symbolic crash information and
864 symbolic stack backtraces. This increases the size of the kernel
865 somewhat, as all symbols have to be loaded into the kernel image.
866
867config KALLSYMS_ALL
868 bool "Include all symbols in kallsyms"
869 depends on DEBUG_KERNEL && KALLSYMS
870 help
871 Normally kallsyms only contains the symbols of functions, for nicer
872 OOPS messages. Some debuggers can use kallsyms for other
f9f97bc0
JJ
873 symbols too: say Y here to include all symbols, if you need them
874 and you don't care about adding 300k to the size of your kernel.
1da177e4
LT
875
876 Say N.
877
878config KALLSYMS_EXTRA_PASS
879 bool "Do an extra kallsyms pass"
880 depends on KALLSYMS
881 help
882 If kallsyms is not working correctly, the build will fail with
883 inconsistent kallsyms data. If that occurs, log a bug report and
884 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
885 Always say N here unless you find a bug in kallsyms, which must be
886 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
887 you wait for kallsyms to be fixed.
888
d59745ce 889
712f47ce
GKH
890config HOTPLUG
891 bool "Support for hot-pluggable devices" if EMBEDDED
892 default y
893 help
894 This option is provided for the case where no hotplug or uevent
895 capabilities is wanted by the kernel. You should only consider
896 disabling this option for embedded systems that do not use modules, a
897 dynamic /dev tree, or dynamic device discovery. Just say Y.
898
d59745ce
MM
899config PRINTK
900 default y
901 bool "Enable support for printk" if EMBEDDED
902 help
903 This option enables normal printk support. Removing it
904 eliminates most of the message strings from the kernel image
905 and makes the kernel more or less silent. As this makes it
906 very difficult to diagnose system problems, saying N here is
907 strongly discouraged.
908
c8538a7a
MM
909config BUG
910 bool "BUG() support" if EMBEDDED
911 default y
912 help
913 Disabling this option eliminates support for BUG and WARN, reducing
914 the size of your kernel image and potentially quietly ignoring
915 numerous fatal conditions. You should only consider disabling this
916 option for embedded systems with no facilities for reporting errors.
917 Just say Y.
918
708e9a79
MM
919config ELF_CORE
920 default y
921 bool "Enable ELF core dumps" if EMBEDDED
922 help
923 Enable support for generating core dumps. Disabling saves about 4k.
924
e5e1d3cb
SS
925config PCSPKR_PLATFORM
926 bool "Enable PC-Speaker support" if EMBEDDED
927 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
928 default y
929 help
930 This option allows to disable the internal PC-Speaker
931 support, saving some memory.
932
1da177e4
LT
933config BASE_FULL
934 default y
935 bool "Enable full-sized data structures for core" if EMBEDDED
936 help
937 Disabling this option reduces the size of miscellaneous core
938 kernel data structures. This saves memory on small machines,
939 but may reduce performance.
940
941config FUTEX
942 bool "Enable futex support" if EMBEDDED
943 default y
23f78d4a 944 select RT_MUTEXES
1da177e4
LT
945 help
946 Disabling this option will cause the kernel to be built without
947 support for "fast userspace mutexes". The resulting kernel may not
948 run glibc-based applications correctly.
949
950config EPOLL
951 bool "Enable eventpoll support" if EMBEDDED
952 default y
448e3cee 953 select ANON_INODES
1da177e4
LT
954 help
955 Disabling this option will cause the kernel to be built without
956 support for epoll family of system calls.
957
fba2afaa
DL
958config SIGNALFD
959 bool "Enable signalfd() system call" if EMBEDDED
448e3cee 960 select ANON_INODES
fba2afaa
DL
961 default y
962 help
963 Enable the signalfd() system call that allows to receive signals
964 on a file descriptor.
965
966 If unsure, say Y.
967
b215e283
DL
968config TIMERFD
969 bool "Enable timerfd() system call" if EMBEDDED
448e3cee 970 select ANON_INODES
b215e283
DL
971 default y
972 help
973 Enable the timerfd() system call that allows to receive timer
974 events on a file descriptor.
975
976 If unsure, say Y.
977
e1ad7468
DL
978config EVENTFD
979 bool "Enable eventfd() system call" if EMBEDDED
448e3cee 980 select ANON_INODES
e1ad7468
DL
981 default y
982 help
983 Enable the eventfd() system call that allows to receive both
984 kernel notification (ie. KAIO) or userspace notifications.
985
986 If unsure, say Y.
987
1da177e4
LT
988config SHMEM
989 bool "Use full shmem filesystem" if EMBEDDED
990 default y
991 depends on MMU
992 help
993 The shmem is an internal filesystem used to manage shared memory.
994 It is backed by swap and manages resource limits. It is also exported
995 to userspace as tmpfs if TMPFS is enabled. Disabling this
996 option replaces shmem and tmpfs with the much simpler ramfs code,
997 which may be appropriate on small systems without swap.
998
ebf3f09c
TP
999config AIO
1000 bool "Enable AIO support" if EMBEDDED
1001 default y
1002 help
1003 This option enables POSIX asynchronous I/O which may by used
1004 by some high performance threaded applications. Disabling
1005 this option saves about 7k.
1006
cdd6c482 1007config HAVE_PERF_EVENTS
0793a61d 1008 bool
018df72d
MF
1009 help
1010 See tools/perf/design.txt for details.
0793a61d 1011
906010b2
PZ
1012config PERF_USE_VMALLOC
1013 bool
1014 help
1015 See tools/perf/design.txt for details
1016
57c0c15b 1017menu "Kernel Performance Events And Counters"
0793a61d 1018
cdd6c482 1019config PERF_EVENTS
57c0c15b
IM
1020 bool "Kernel performance events and counters"
1021 default y if (PROFILING || PERF_COUNTERS)
cdd6c482 1022 depends on HAVE_PERF_EVENTS
4c59e467 1023 select ANON_INODES
e360adbe 1024 select IRQ_WORK
0793a61d 1025 help
57c0c15b
IM
1026 Enable kernel support for various performance events provided
1027 by software and hardware.
0793a61d 1028
dd77038d 1029 Software events are supported either built-in or via the
57c0c15b 1030 use of generic tracepoints.
0793a61d 1031
57c0c15b
IM
1032 Most modern CPUs support performance events via performance
1033 counter registers. These registers count the number of certain
0793a61d
TG
1034 types of hw events: such as instructions executed, cachemisses
1035 suffered, or branches mis-predicted - without slowing down the
1036 kernel or applications. These registers can also trigger interrupts
1037 when a threshold number of events have passed - and can thus be
1038 used to profile the code that runs on that CPU.
1039
57c0c15b 1040 The Linux Performance Event subsystem provides an abstraction of
dd77038d 1041 these software and hardware event capabilities, available via a
57c0c15b 1042 system call and used by the "perf" utility in tools/perf/. It
0793a61d
TG
1043 provides per task and per CPU counters, and it provides event
1044 capabilities on top of those.
1045
1046 Say Y if unsure.
1047
57c0c15b
IM
1048config PERF_COUNTERS
1049 bool "Kernel performance counters (old config option)"
1050 depends on HAVE_PERF_EVENTS
1051 help
1052 This config has been obsoleted by the PERF_EVENTS
1053 config option - please see that one for details.
1054
1055 It has no effect on the kernel whether you enable
1056 it or not, it is a compatibility placeholder.
1057
1058 Say N if unsure.
1059
906010b2
PZ
1060config DEBUG_PERF_USE_VMALLOC
1061 default n
1062 bool "Debug: use vmalloc to back perf mmap() buffers"
1063 depends on PERF_EVENTS && DEBUG_KERNEL
1064 select PERF_USE_VMALLOC
1065 help
1066 Use vmalloc memory to back perf mmap() buffers.
1067
1068 Mostly useful for debugging the vmalloc code on platforms
1069 that don't require it.
1070
1071 Say N if unsure.
1072
0793a61d
TG
1073endmenu
1074
f8891e5e
CL
1075config VM_EVENT_COUNTERS
1076 default y
1077 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
1078 help
2aea4fb6
PJ
1079 VM event counters are needed for event counts to be shown.
1080 This option allows the disabling of the VM event counters
1081 on EMBEDDED systems. /proc/vmstat will only show page counts
1082 if VM event counters are disabled.
f8891e5e 1083
3d137310
TP
1084config PCI_QUIRKS
1085 default y
61cfc7e4
GU
1086 bool "Enable PCI quirk workarounds" if EMBEDDED
1087 depends on PCI
3d137310
TP
1088 help
1089 This enables workarounds for various PCI chipset
1090 bugs/quirks. Disable this only if your target machine is
1091 unaffected by PCI quirks.
1092
41ecc55b
CL
1093config SLUB_DEBUG
1094 default y
1095 bool "Enable SLUB debugging support" if EMBEDDED
f6acb635 1096 depends on SLUB && SYSFS
41ecc55b
CL
1097 help
1098 SLUB has extensive debug support features. Disabling these can
1099 result in significant savings in code size. This also disables
1100 SLUB sysfs support. /sys/slab will not exist and there will be
1101 no support for cache validation etc.
1102
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RD
1103config COMPAT_BRK
1104 bool "Disable heap randomization"
1105 default y
1106 help
1107 Randomizing heap placement makes heap exploits harder, but it
1108 also breaks ancient binaries (including anything libc5 based).
1109 This option changes the bootup default to heap randomization
692105b8 1110 disabled, and can be overridden at runtime by setting
b943c460
RD
1111 /proc/sys/kernel/randomize_va_space to 2.
1112
1113 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1114
81819f0f
CL
1115choice
1116 prompt "Choose SLAB allocator"
a0acd820 1117 default SLUB
81819f0f
CL
1118 help
1119 This option allows to select a slab allocator.
1120
1121config SLAB
1122 bool "SLAB"
1123 help
1124 The regular slab allocator that is established and known to work
34013886 1125 well in all environments. It organizes cache hot objects in
02f56210 1126 per cpu and per node queues.
81819f0f
CL
1127
1128config SLUB
81819f0f
CL
1129 bool "SLUB (Unqueued Allocator)"
1130 help
1131 SLUB is a slab allocator that minimizes cache line usage
1132 instead of managing queues of cached objects (SLAB approach).
1133 Per cpu caching is realized using slabs of objects instead
1134 of queues of objects. SLUB can use memory efficiently
02f56210
SA
1135 and has enhanced diagnostics. SLUB is the default choice for
1136 a slab allocator.
81819f0f
CL
1137
1138config SLOB
84a01c2f 1139 depends on EMBEDDED
81819f0f
CL
1140 bool "SLOB (Simple Allocator)"
1141 help
37291458
MM
1142 SLOB replaces the stock allocator with a drastically simpler
1143 allocator. SLOB is generally more space efficient but
1144 does not perform as well on large systems.
81819f0f
CL
1145
1146endchoice
1147
ea637639
JZ
1148config MMAP_ALLOW_UNINITIALIZED
1149 bool "Allow mmapped anonymous memory to be uninitialized"
1150 depends on EMBEDDED && !MMU
1151 default n
1152 help
1153 Normally, and according to the Linux spec, anonymous memory obtained
1154 from mmap() has it's contents cleared before it is passed to
1155 userspace. Enabling this config option allows you to request that
1156 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1157 providing a huge performance boost. If this option is not enabled,
1158 then the flag will be ignored.
1159
1160 This is taken advantage of by uClibc's malloc(), and also by
1161 ELF-FDPIC binfmt's brk and stack allocator.
1162
1163 Because of the obvious security issues, this option should only be
1164 enabled on embedded devices where you control what is run in
1165 userspace. Since that isn't generally a problem on no-MMU systems,
1166 it is normally safe to say Y here.
1167
1168 See Documentation/nommu-mmap.txt for more information.
1169
125e5645 1170config PROFILING
b309a294 1171 bool "Profiling support"
125e5645
MD
1172 help
1173 Say Y here to enable the extended profiling support mechanisms used
1174 by profilers such as OProfile.
1175
5f87f112
IM
1176#
1177# Place an empty function call at each tracepoint site. Can be
1178# dynamically changed for a probe function.
1179#
97e1c18e 1180config TRACEPOINTS
5f87f112 1181 bool
97e1c18e 1182
fb32e03f
MD
1183source "arch/Kconfig"
1184
1da177e4
LT
1185endmenu # General setup
1186
ee7e5516
DES
1187config HAVE_GENERIC_DMA_COHERENT
1188 bool
1189 default n
1190
158a9624
LT
1191config SLABINFO
1192 bool
1193 depends on PROC_FS
0f389ec6 1194 depends on SLAB || SLUB_DEBUG
158a9624
LT
1195 default y
1196
ae81f9e3
CE
1197config RT_MUTEXES
1198 boolean
ae81f9e3 1199
1da177e4
LT
1200config BASE_SMALL
1201 int
1202 default 0 if BASE_FULL
1203 default 1 if !BASE_FULL
1204
66da5733 1205menuconfig MODULES
1da177e4
LT
1206 bool "Enable loadable module support"
1207 help
1208 Kernel modules are small pieces of compiled code which can
1209 be inserted in the running kernel, rather than being
1210 permanently built into the kernel. You use the "modprobe"
1211 tool to add (and sometimes remove) them. If you say Y here,
1212 many parts of the kernel can be built as modules (by
1213 answering M instead of Y where indicated): this is most
1214 useful for infrequently used options which are not required
1215 for booting. For more information, see the man pages for
1216 modprobe, lsmod, modinfo, insmod and rmmod.
1217
1218 If you say Y here, you will need to run "make
1219 modules_install" to put the modules under /lib/modules/
1220 where modprobe can find them (you may need to be root to do
1221 this).
1222
1223 If unsure, say Y.
1224
0b0de144
RD
1225if MODULES
1226
826e4506
LT
1227config MODULE_FORCE_LOAD
1228 bool "Forced module loading"
826e4506
LT
1229 default n
1230 help
91e37a79
RR
1231 Allow loading of modules without version information (ie. modprobe
1232 --force). Forced module loading sets the 'F' (forced) taint flag and
1233 is usually a really bad idea.
826e4506 1234
1da177e4
LT
1235config MODULE_UNLOAD
1236 bool "Module unloading"
1da177e4
LT
1237 help
1238 Without this option you will not be able to unload any
1239 modules (note that some modules may not be unloadable
f7f5b675
DV
1240 anyway), which makes your kernel smaller, faster
1241 and simpler. If unsure, say Y.
1da177e4
LT
1242
1243config MODULE_FORCE_UNLOAD
1244 bool "Forced module unloading"
1245 depends on MODULE_UNLOAD && EXPERIMENTAL
1246 help
1247 This option allows you to force a module to unload, even if the
1248 kernel believes it is unsafe: the kernel will remove the module
1249 without waiting for anyone to stop using it (using the -f option to
1250 rmmod). This is mainly for kernel developers and desperate users.
1251 If unsure, say N.
1252
1da177e4 1253config MODVERSIONS
0d541643 1254 bool "Module versioning support"
1da177e4
LT
1255 help
1256 Usually, you have to use modules compiled with your kernel.
1257 Saying Y here makes it sometimes possible to use modules
1258 compiled for different kernels, by adding enough information
1259 to the modules to (hopefully) spot any changes which would
1260 make them incompatible with the kernel you are running. If
1261 unsure, say N.
1262
1263config MODULE_SRCVERSION_ALL
1264 bool "Source checksum for all modules"
1da177e4
LT
1265 help
1266 Modules which contain a MODULE_VERSION get an extra "srcversion"
1267 field inserted into their modinfo section, which contains a
1268 sum of the source files which made it. This helps maintainers
1269 see exactly which source was used to build a module (since
1270 others sometimes change the module source without updating
1271 the version). With this option, such a "srcversion" field
1272 will be created for all modules. If unsure, say N.
1273
0b0de144
RD
1274endif # MODULES
1275
98a79d6a
RR
1276config INIT_ALL_POSSIBLE
1277 bool
1278 help
1279 Back when each arch used to define their own cpu_online_map and
1280 cpu_possible_map, some of them chose to initialize cpu_possible_map
1281 with all 1s, and others with all 0s. When they were centralised,
1282 it was better to provide this option than to break all the archs
692105b8 1283 and have several arch maintainers pursuing me down dark alleys.
98a79d6a 1284
1da177e4
LT
1285config STOP_MACHINE
1286 bool
1287 default y
1288 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1289 help
1290 Need stop_machine() primitive.
3a65dfe8 1291
3a65dfe8 1292source "block/Kconfig"
e98c3202
AK
1293
1294config PREEMPT_NOTIFIERS
1295 bool
e260be67 1296
16295bec
SK
1297config PADATA
1298 depends on SMP
1299 bool
1300
6beb0009 1301source "kernel/Kconfig.locks"