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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
b99b87f7 22
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23config HAVE_IRQ_WORK
24 bool
25
26config IRQ_WORK
27 bool
28 depends on HAVE_IRQ_WORK
29
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30config BUILDTIME_EXTABLE_SORT
31 bool
32
ff0cfc66 33menu "General setup"
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34
35config EXPERIMENTAL
36 bool "Prompt for development and/or incomplete code/drivers"
37 ---help---
38 Some of the various things that Linux supports (such as network
39 drivers, file systems, network protocols, etc.) can be in a state
40 of development where the functionality, stability, or the level of
41 testing is not yet high enough for general use. This is usually
42 known as the "alpha-test" phase among developers. If a feature is
43 currently in alpha-test, then the developers usually discourage
44 uninformed widespread use of this feature by the general public to
45 avoid "Why doesn't this work?" type mail messages. However, active
46 testing and use of these systems is welcomed. Just be aware that it
47 may not meet the normal level of reliability or it may fail to work
48 in some special cases. Detailed bug reports from people familiar
49 with the kernel internals are usually welcomed by the developers
50 (before submitting bug reports, please read the documents
51 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
52 <file:Documentation/BUG-HUNTING>, and
53 <file:Documentation/oops-tracing.txt> in the kernel source).
54
55 This option will also make obsoleted drivers available. These are
56 drivers that have been replaced by something else, and/or are
57 scheduled to be removed in a future kernel release.
58
59 Unless you intend to help test and develop a feature or driver that
60 falls into this category, or you have a situation that requires
61 using these features, you should probably say N here, which will
62 cause the configurator to present you with fewer choices. If
63 you say Y here, you will be offered the choice of using features or
64 drivers that are currently considered to be in the alpha-test phase.
65
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66config BROKEN
67 bool
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68
69config BROKEN_ON_SMP
70 bool
71 depends on BROKEN || !SMP
72 default y
73
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74config INIT_ENV_ARG_LIMIT
75 int
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76 default 32 if !UML
77 default 128 if UML
1da177e4 78 help
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79 Maximum of each of the number of arguments and environment
80 variables passed to init from the kernel command line.
1da177e4 81
1da177e4 82
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83config CROSS_COMPILE
84 string "Cross-compiler tool prefix"
85 help
86 Same as running 'make CROSS_COMPILE=prefix-' but stored for
87 default make runs in this kernel build directory. You don't
88 need to set this unless you want the configured kernel build
89 directory to select the cross-compiler automatically.
90
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91config LOCALVERSION
92 string "Local version - append to kernel release"
93 help
94 Append an extra string to the end of your kernel version.
95 This will show up when you type uname, for example.
96 The string you set here will be appended after the contents of
97 any files with a filename matching localversion* in your
98 object and source tree, in that order. Your total string can
99 be a maximum of 64 characters.
100
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101config LOCALVERSION_AUTO
102 bool "Automatically append version information to the version string"
103 default y
104 help
105 This will try to automatically determine if the current tree is a
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106 release tree by looking for git tags that belong to the current
107 top of tree revision.
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108
109 A string of the format -gxxxxxxxx will be added to the localversion
6e5a5420 110 if a git-based tree is found. The string generated by this will be
aaebf433 111 appended after any matching localversion* files, and after the value
6e5a5420 112 set in CONFIG_LOCALVERSION.
aaebf433 113
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114 (The actual string used here is the first eight characters produced
115 by running the command:
116
117 $ git rev-parse --verify HEAD
118
119 which is done within the script "scripts/setlocalversion".)
aaebf433 120
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121config HAVE_KERNEL_GZIP
122 bool
123
124config HAVE_KERNEL_BZIP2
125 bool
126
127config HAVE_KERNEL_LZMA
128 bool
129
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130config HAVE_KERNEL_XZ
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
3ebe1243 139 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || 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_XZ
185 bool "XZ"
186 depends on HAVE_KERNEL_XZ
187 help
188 XZ uses the LZMA2 algorithm and instruction set specific
189 BCJ filters which can improve compression ratio of executable
190 code. The size of the kernel is about 30% smaller with XZ in
191 comparison to gzip. On architectures for which there is a BCJ
192 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
193 will create a few percent smaller kernel than plain LZMA.
194
195 The speed is about the same as with LZMA: The decompression
196 speed of XZ is better than that of bzip2 but worse than gzip
197 and LZO. Compression is slow.
198
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199config KERNEL_LZO
200 bool "LZO"
201 depends on HAVE_KERNEL_LZO
202 help
203 Its compression ratio is the poorest among the 4. The kernel
681b3049 204 size is about 10% bigger than gzip; however its speed
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205 (both compression and decompression) is the fastest.
206
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207endchoice
208
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209config DEFAULT_HOSTNAME
210 string "Default hostname"
211 default "(none)"
212 help
213 This option determines the default system hostname before userspace
214 calls sethostname(2). The kernel traditionally uses "(none)" here,
215 but you may wish to use a different default here to make a minimal
216 system more usable with less configuration.
217
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218config SWAP
219 bool "Support for paging of anonymous memory (swap)"
9361401e 220 depends on MMU && BLOCK
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221 default y
222 help
223 This option allows you to choose whether you want to have support
92c3504e 224 for so called swap devices or swap files in your kernel that are
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225 used to provide more virtual memory than the actual RAM present
226 in your computer. If unsure say Y.
227
228config SYSVIPC
229 bool "System V IPC"
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230 ---help---
231 Inter Process Communication is a suite of library functions and
232 system calls which let processes (running programs) synchronize and
233 exchange information. It is generally considered to be a good thing,
234 and some programs won't run unless you say Y here. In particular, if
235 you want to run the DOS emulator dosemu under Linux (read the
236 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
237 you'll need to say Y here.
238
239 You can find documentation about IPC with "info ipc" and also in
240 section 6.4 of the Linux Programmer's Guide, available from
241 <http://www.tldp.org/guides.html>.
242
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243config SYSVIPC_SYSCTL
244 bool
245 depends on SYSVIPC
246 depends on SYSCTL
247 default y
248
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249config POSIX_MQUEUE
250 bool "POSIX Message Queues"
251 depends on NET && EXPERIMENTAL
252 ---help---
253 POSIX variant of message queues is a part of IPC. In POSIX message
254 queues every message has a priority which decides about succession
255 of receiving it by a process. If you want to compile and run
256 programs written e.g. for Solaris with use of its POSIX message
b0e37650 257 queues (functions mq_*) say Y here.
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258
259 POSIX message queues are visible as a filesystem called 'mqueue'
260 and can be mounted somewhere if you want to do filesystem
261 operations on message queues.
262
263 If unsure, say Y.
264
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265config POSIX_MQUEUE_SYSCTL
266 bool
267 depends on POSIX_MQUEUE
268 depends on SYSCTL
269 default y
270
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271config BSD_PROCESS_ACCT
272 bool "BSD Process Accounting"
273 help
274 If you say Y here, a user level program will be able to instruct the
275 kernel (via a special system call) to write process accounting
276 information to a file: whenever a process exits, information about
277 that process will be appended to the file by the kernel. The
278 information includes things such as creation time, owning user,
279 command name, memory usage, controlling terminal etc. (the complete
280 list is in the struct acct in <file:include/linux/acct.h>). It is
281 up to the user level program to do useful things with this
282 information. This is generally a good idea, so say Y.
283
284config BSD_PROCESS_ACCT_V3
285 bool "BSD Process Accounting version 3 file format"
286 depends on BSD_PROCESS_ACCT
287 default n
288 help
289 If you say Y here, the process accounting information is written
290 in a new file format that also logs the process IDs of each
291 process and it's parent. Note that this file format is incompatible
292 with previous v0/v1/v2 file formats, so you will need updated tools
293 for processing it. A preliminary version of these tools is available
37a4c940 294 at <http://www.gnu.org/software/acct/>.
1da177e4 295
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296config FHANDLE
297 bool "open by fhandle syscalls"
298 select EXPORTFS
299 help
300 If you say Y here, a user level program will be able to map
301 file names to handle and then later use the handle for
302 different file system operations. This is useful in implementing
303 userspace file servers, which now track files using handles instead
304 of names. The handle would remain the same even if file names
305 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
306 syscalls.
307
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308config TASKSTATS
309 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
310 depends on NET
311 default n
312 help
313 Export selected statistics for tasks/processes through the
314 generic netlink interface. Unlike BSD process accounting, the
315 statistics are available during the lifetime of tasks/processes as
316 responses to commands. Like BSD accounting, they are sent to user
317 space on task exit.
318
319 Say N if unsure.
320
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321config TASK_DELAY_ACCT
322 bool "Enable per-task delay accounting (EXPERIMENTAL)"
6f44993f 323 depends on TASKSTATS
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324 help
325 Collect information on time spent by a task waiting for system
326 resources like cpu, synchronous block I/O completion and swapping
327 in pages. Such statistics can help in setting a task's priorities
328 relative to other tasks for cpu, io, rss limits etc.
329
330 Say N if unsure.
331
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332config TASK_XACCT
333 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
334 depends on TASKSTATS
335 help
336 Collect extended task accounting data and send the data
337 to userland for processing over the taskstats interface.
338
339 Say N if unsure.
340
341config TASK_IO_ACCOUNTING
342 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
343 depends on TASK_XACCT
344 help
345 Collect information on the number of bytes of storage I/O which this
346 task has caused.
347
348 Say N if unsure.
349
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350config AUDIT
351 bool "Auditing support"
804a6a49 352 depends on NET
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353 help
354 Enable auditing infrastructure that can be used with another
355 kernel subsystem, such as SELinux (which requires this for
356 logging of avc messages output). Does not do system-call
357 auditing without CONFIG_AUDITSYSCALL.
358
359config AUDITSYSCALL
360 bool "Enable system-call auditing support"
29ef73b7 361 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || ARM)
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362 default y if SECURITY_SELINUX
363 help
364 Enable low-overhead system-call auditing infrastructure that
365 can be used independently or with another kernel subsystem,
67640b60 366 such as SELinux.
1da177e4 367
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368config AUDIT_WATCH
369 def_bool y
370 depends on AUDITSYSCALL
371 select FSNOTIFY
1da177e4 372
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373config AUDIT_TREE
374 def_bool y
63c882a0 375 depends on AUDITSYSCALL
28a3a7eb 376 select FSNOTIFY
74c3cbe3 377
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378config AUDIT_LOGINUID_IMMUTABLE
379 bool "Make audit loginuid immutable"
380 depends on AUDIT
381 help
f429ee3b 382 The config option toggles if a task setting its loginuid requires
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383 CAP_SYS_AUDITCONTROL or if that task should require no special permissions
384 but should instead only allow setting its loginuid if it was never
385 previously set. On systems which use systemd or a similar central
386 process to restart login services this should be set to true. On older
387 systems in which an admin would typically have to directly stop and
388 start processes this should be set to false. Setting this to true allows
389 one to drop potentially dangerous capabilites from the login tasks,
390 but may not be backwards compatible with older init systems.
391
d9817ebe 392source "kernel/irq/Kconfig"
764e0da1 393source "kernel/time/Kconfig"
d9817ebe 394
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395menu "RCU Subsystem"
396
397choice
398 prompt "RCU Implementation"
31c9a24e 399 default TREE_RCU
c903ff83 400
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401config TREE_RCU
402 bool "Tree-based hierarchical RCU"
687d7a96 403 depends on !PREEMPT && SMP
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404 help
405 This option selects the RCU implementation that is
406 designed for very large SMP system with hundreds or
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407 thousands of CPUs. It also scales down nicely to
408 smaller systems.
c903ff83 409
f41d911f 410config TREE_PREEMPT_RCU
a57eb940 411 bool "Preemptible tree-based hierarchical RCU"
8008e129 412 depends on PREEMPT && SMP
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413 help
414 This option selects the RCU implementation that is
415 designed for very large SMP systems with hundreds or
416 thousands of CPUs, but for which real-time response
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417 is also required. It also scales down nicely to
418 smaller systems.
f41d911f 419
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420config TINY_RCU
421 bool "UP-only small-memory-footprint RCU"
8008e129 422 depends on !PREEMPT && !SMP
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423 help
424 This option selects the RCU implementation that is
425 designed for UP systems from which real-time response
426 is not required. This option greatly reduces the
427 memory footprint of RCU.
428
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429config TINY_PREEMPT_RCU
430 bool "Preemptible UP-only small-memory-footprint RCU"
8008e129 431 depends on PREEMPT && !SMP
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432 help
433 This option selects the RCU implementation that is designed
434 for real-time UP systems. This option greatly reduces the
435 memory footprint of RCU.
436
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437endchoice
438
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439config PREEMPT_RCU
440 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
441 help
442 This option enables preemptible-RCU code that is common between
443 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
444
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445config RCU_FANOUT
446 int "Tree-based hierarchical RCU fanout value"
447 range 2 64 if 64BIT
448 range 2 32 if !64BIT
f41d911f 449 depends on TREE_RCU || TREE_PREEMPT_RCU
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450 default 64 if 64BIT
451 default 32 if !64BIT
452 help
453 This option controls the fanout of hierarchical implementations
454 of RCU, allowing RCU to work efficiently on machines with
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455 large numbers of CPUs. This value must be at least the fourth
456 root of NR_CPUS, which allows NR_CPUS to be insanely large.
457 The default value of RCU_FANOUT should be used for production
458 systems, but if you are stress-testing the RCU implementation
459 itself, small RCU_FANOUT values allow you to test large-system
460 code paths on small(er) systems.
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461
462 Select a specific number if testing RCU itself.
463 Take the default if unsure.
464
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465config RCU_FANOUT_LEAF
466 int "Tree-based hierarchical RCU leaf-level fanout value"
467 range 2 RCU_FANOUT if 64BIT
468 range 2 RCU_FANOUT if !64BIT
469 depends on TREE_RCU || TREE_PREEMPT_RCU
470 default 16
471 help
472 This option controls the leaf-level fanout of hierarchical
473 implementations of RCU, and allows trading off cache misses
474 against lock contention. Systems that synchronize their
475 scheduling-clock interrupts for energy-efficiency reasons will
476 want the default because the smaller leaf-level fanout keeps
477 lock contention levels acceptably low. Very large systems
478 (hundreds or thousands of CPUs) will instead want to set this
479 value to the maximum value possible in order to reduce the
480 number of cache misses incurred during RCU's grace-period
481 initialization. These systems tend to run CPU-bound, and thus
482 are not helped by synchronized interrupts, and thus tend to
483 skew them, which reduces lock contention enough that large
484 leaf-level fanouts work well.
485
486 Select a specific number if testing RCU itself.
487
488 Select the maximum permissible value for large systems.
489
490 Take the default if unsure.
491
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492config RCU_FANOUT_EXACT
493 bool "Disable tree-based hierarchical RCU auto-balancing"
f41d911f 494 depends on TREE_RCU || TREE_PREEMPT_RCU
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495 default n
496 help
497 This option forces use of the exact RCU_FANOUT value specified,
498 regardless of imbalances in the hierarchy. This is useful for
499 testing RCU itself, and might one day be useful on systems with
500 strong NUMA behavior.
501
502 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
503
504 Say N if unsure.
505
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506config RCU_FAST_NO_HZ
507 bool "Accelerate last non-dyntick-idle CPU's grace periods"
b807fbff 508 depends on NO_HZ && SMP
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509 default n
510 help
511 This option causes RCU to attempt to accelerate grace periods
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512 in order to allow CPUs to enter dynticks-idle state more
513 quickly. On the other hand, this option increases the overhead
514 of the dynticks-idle checking, particularly on systems with
515 large numbers of CPUs.
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516
517 Say Y if energy efficiency is critically important, particularly
518 if you have relatively few CPUs.
519
520 Say N if you are unsure.
521
c903ff83 522config TREE_RCU_TRACE
f41d911f 523 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
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524 select DEBUG_FS
525 help
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526 This option provides tracing for the TREE_RCU and
527 TREE_PREEMPT_RCU implementations, permitting Makefile to
528 trivially select kernel/rcutree_trace.c.
c903ff83 529
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530config RCU_BOOST
531 bool "Enable RCU priority boosting"
27f4d280 532 depends on RT_MUTEXES && PREEMPT_RCU
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533 default n
534 help
535 This option boosts the priority of preempted RCU readers that
536 block the current preemptible RCU grace period for too long.
537 This option also prevents heavy loads from blocking RCU
538 callback invocation for all flavors of RCU.
539
540 Say Y here if you are working with real-time apps or heavy loads
541 Say N here if you are unsure.
542
543config RCU_BOOST_PRIO
544 int "Real-time priority to boost RCU readers to"
545 range 1 99
546 depends on RCU_BOOST
547 default 1
548 help
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549 This option specifies the real-time priority to which long-term
550 preempted RCU readers are to be boosted. If you are working
551 with a real-time application that has one or more CPU-bound
552 threads running at a real-time priority level, you should set
553 RCU_BOOST_PRIO to a priority higher then the highest-priority
554 real-time CPU-bound thread. The default RCU_BOOST_PRIO value
555 of 1 is appropriate in the common case, which is real-time
556 applications that do not have any CPU-bound threads.
557
558 Some real-time applications might not have a single real-time
559 thread that saturates a given CPU, but instead might have
560 multiple real-time threads that, taken together, fully utilize
561 that CPU. In this case, you should set RCU_BOOST_PRIO to
562 a priority higher than the lowest-priority thread that is
563 conspiring to prevent the CPU from running any non-real-time
564 tasks. For example, if one thread at priority 10 and another
565 thread at priority 5 are between themselves fully consuming
566 the CPU time on a given CPU, then RCU_BOOST_PRIO should be
567 set to priority 6 or higher.
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568
569 Specify the real-time priority, or take the default if unsure.
570
571config RCU_BOOST_DELAY
572 int "Milliseconds to delay boosting after RCU grace-period start"
573 range 0 3000
574 depends on RCU_BOOST
575 default 500
576 help
577 This option specifies the time to wait after the beginning of
578 a given grace period before priority-boosting preempted RCU
579 readers blocking that grace period. Note that any RCU reader
580 blocking an expedited RCU grace period is boosted immediately.
581
582 Accept the default if unsure.
583
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584endmenu # "RCU Subsystem"
585
1da177e4 586config IKCONFIG
f2443ab6 587 tristate "Kernel .config support"
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588 ---help---
589 This option enables the complete Linux kernel ".config" file
590 contents to be saved in the kernel. It provides documentation
591 of which kernel options are used in a running kernel or in an
592 on-disk kernel. This information can be extracted from the kernel
593 image file with the script scripts/extract-ikconfig and used as
594 input to rebuild the current kernel or to build another kernel.
595 It can also be extracted from a running kernel by reading
596 /proc/config.gz if enabled (below).
597
598config IKCONFIG_PROC
599 bool "Enable access to .config through /proc/config.gz"
600 depends on IKCONFIG && PROC_FS
601 ---help---
602 This option enables access to the kernel configuration file
603 through /proc/config.gz.
604
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605config LOG_BUF_SHIFT
606 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
607 range 12 21
f17a32e9 608 default 17
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609 help
610 Select kernel log buffer size as a power of 2.
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611 Examples:
612 17 => 128 KB
613 16 => 64 KB
614 15 => 32 KB
615 14 => 16 KB
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616 13 => 8 KB
617 12 => 4 KB
618
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619#
620# Architectures with an unreliable sched_clock() should select this:
621#
622config HAVE_UNSTABLE_SCHED_CLOCK
623 bool
624
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625menuconfig CGROUPS
626 boolean "Control Group support"
0dea1168 627 depends on EVENTFD
5cdc38f9 628 help
23964d2d 629 This option adds support for grouping sets of processes together, for
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630 use with process control subsystems such as Cpusets, CFS, memory
631 controls or device isolation.
632 See
5cdc38f9 633 - Documentation/scheduler/sched-design-CFS.txt (CFS)
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634 - Documentation/cgroups/ (features for grouping, isolation
635 and resource control)
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636
637 Say N if unsure.
638
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639if CGROUPS
640
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641config CGROUP_DEBUG
642 bool "Example debug cgroup subsystem"
5cdc38f9
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643 default n
644 help
645 This option enables a simple cgroup subsystem that
646 exports useful debugging information about the cgroups
23964d2d 647 framework.
5cdc38f9 648
23964d2d 649 Say N if unsure.
5cdc38f9 650
5cdc38f9 651config CGROUP_FREEZER
23964d2d 652 bool "Freezer cgroup subsystem"
23964d2d
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653 help
654 Provides a way to freeze and unfreeze all tasks in a
5cdc38f9
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655 cgroup.
656
657config CGROUP_DEVICE
658 bool "Device controller for cgroups"
5cdc38f9
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659 help
660 Provides a cgroup implementing whitelists for devices which
661 a process in the cgroup can mknod or open.
662
663config CPUSETS
664 bool "Cpuset support"
5cdc38f9
KH
665 help
666 This option will let you create and manage CPUSETs which
667 allow dynamically partitioning a system into sets of CPUs and
668 Memory Nodes and assigning tasks to run only within those sets.
669 This is primarily useful on large SMP or NUMA systems.
670
671 Say N if unsure.
672
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673config PROC_PID_CPUSET
674 bool "Include legacy /proc/<pid>/cpuset file"
675 depends on CPUSETS
676 default y
677
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SV
678config CGROUP_CPUACCT
679 bool "Simple CPU accounting cgroup subsystem"
d842de87
SV
680 help
681 Provides a simple Resource Controller for monitoring the
23964d2d 682 total CPU consumed by the tasks in a cgroup.
d842de87 683
e552b661
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684config RESOURCE_COUNTERS
685 bool "Resource counters"
686 help
687 This option enables controller independent resource accounting
23964d2d 688 infrastructure that works with cgroups.
e552b661 689
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690config CGROUP_MEM_RES_CTLR
691 bool "Memory Resource Controller for Control Groups"
79ae9c29 692 depends on RESOURCE_COUNTERS
cf475ad2 693 select MM_OWNER
00f0b825 694 help
84ad6d70 695 Provides a memory resource controller that manages both anonymous
21acb9ca 696 memory and page cache. (See Documentation/cgroups/memory.txt)
00f0b825
BS
697
698 Note that setting this option increases fixed memory overhead
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KH
699 associated with each page of memory in the system. By this,
700 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
701 usage tracking struct at boot. Total amount of this is printed out
702 at boot.
00f0b825
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703
704 Only enable when you're ok with these trade offs and really
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705 sure you need the memory resource controller. Even when you enable
706 this, you can set "cgroup_disable=memory" at your boot option to
707 disable memory resource controller and you can avoid overheads.
c9d5409f 708 (and lose benefits of memory resource controller)
00f0b825 709
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710 This config option also selects MM_OWNER config option, which
711 could in turn add some fork/exit overhead.
712
c077719b 713config CGROUP_MEM_RES_CTLR_SWAP
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714 bool "Memory Resource Controller Swap Extension"
715 depends on CGROUP_MEM_RES_CTLR && SWAP
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KH
716 help
717 Add swap management feature to memory resource controller. When you
718 enable this, you can limit mem+swap usage per cgroup. In other words,
719 when you disable this, memory resource controller has no cares to
720 usage of swap...a process can exhaust all of the swap. This extension
721 is useful when you want to avoid exhaustion swap but this itself
722 adds more overheads and consumes memory for remembering information.
723 Especially if you use 32bit system or small memory system, please
724 be careful about enabling this. When memory resource controller
725 is disabled by boot option, this will be automatically disabled and
726 there will be no overhead from this. Even when you set this config=y,
00a66d29 727 if boot option "swapaccount=0" is set, swap will not be accounted.
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728 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
729 size is 4096bytes, 512k per 1Gbytes of swap.
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MH
730config CGROUP_MEM_RES_CTLR_SWAP_ENABLED
731 bool "Memory Resource Controller Swap Extension enabled by default"
732 depends on CGROUP_MEM_RES_CTLR_SWAP
733 default y
734 help
735 Memory Resource Controller Swap Extension comes with its price in
736 a bigger memory consumption. General purpose distribution kernels
43d547f9 737 which want to enable the feature but keep it disabled by default
a42c390c
MH
738 and let the user enable it by swapaccount boot command line
739 parameter should have this option unselected.
740 For those who want to have the feature enabled by default should
741 select this option (if, for some reason, they need to disable it
00a66d29 742 then swapaccount=0 does the trick).
e5671dfa
GC
743config CGROUP_MEM_RES_CTLR_KMEM
744 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
745 depends on CGROUP_MEM_RES_CTLR && EXPERIMENTAL
746 default n
747 help
748 The Kernel Memory extension for Memory Resource Controller can limit
749 the amount of memory used by kernel objects in the system. Those are
750 fundamentally different from the entities handled by the standard
751 Memory Controller, which are page-based, and can be swapped. Users of
752 the kmem extension can use it to guarantee that no group of processes
753 will ever exhaust kernel resources alone.
c077719b 754
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SE
755config CGROUP_PERF
756 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
757 depends on PERF_EVENTS && CGROUPS
758 help
759 This option extends the per-cpu mode to restrict monitoring to
2d0f2520 760 threads which belong to the cgroup specified and run on the
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SE
761 designated cpu.
762
763 Say N if unsure.
764
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DG
765menuconfig CGROUP_SCHED
766 bool "Group CPU scheduler"
7c941438
DG
767 default n
768 help
769 This feature lets CPU scheduler recognize task groups and control CPU
770 bandwidth allocation to such task groups. It uses cgroups to group
771 tasks.
772
773if CGROUP_SCHED
774config FAIR_GROUP_SCHED
775 bool "Group scheduling for SCHED_OTHER"
776 depends on CGROUP_SCHED
777 default CGROUP_SCHED
778
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779config CFS_BANDWIDTH
780 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
781 depends on EXPERIMENTAL
782 depends on FAIR_GROUP_SCHED
783 default n
784 help
785 This option allows users to define CPU bandwidth rates (limits) for
786 tasks running within the fair group scheduler. Groups with no limit
787 set are considered to be unconstrained and will run with no
788 restriction.
789 See tip/Documentation/scheduler/sched-bwc.txt for more information.
790
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DG
791config RT_GROUP_SCHED
792 bool "Group scheduling for SCHED_RR/FIFO"
793 depends on EXPERIMENTAL
794 depends on CGROUP_SCHED
795 default n
796 help
797 This feature lets you explicitly allocate real CPU bandwidth
32bd7eb5 798 to task groups. If enabled, it will also make it impossible to
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DG
799 schedule realtime tasks for non-root users until you allocate
800 realtime bandwidth for them.
801 See Documentation/scheduler/sched-rt-group.txt for more information.
802
803endif #CGROUP_SCHED
804
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VG
805config BLK_CGROUP
806 tristate "Block IO controller"
79ae9c29 807 depends on BLOCK
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VG
808 default n
809 ---help---
810 Generic block IO controller cgroup interface. This is the common
811 cgroup interface which should be used by various IO controlling
812 policies.
813
814 Currently, CFQ IO scheduler uses it to recognize task groups and
815 control disk bandwidth allocation (proportional time slice allocation)
e43473b7
VG
816 to such task groups. It is also used by bio throttling logic in
817 block layer to implement upper limit in IO rates on a device.
afc24d49
VG
818
819 This option only enables generic Block IO controller infrastructure.
e43473b7 820 One needs to also enable actual IO controlling logic/policy. For
79e2e759
MW
821 enabling proportional weight division of disk bandwidth in CFQ, set
822 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
c5e0591a 823 CONFIG_BLK_DEV_THROTTLING=y.
afc24d49
VG
824
825 See Documentation/cgroups/blkio-controller.txt for more information.
826
827config DEBUG_BLK_CGROUP
828 bool "Enable Block IO controller debugging"
829 depends on BLK_CGROUP
830 default n
831 ---help---
832 Enable some debugging help. Currently it exports additional stat
833 files in a cgroup which can be useful for debugging.
834
23964d2d 835endif # CGROUPS
c077719b 836
067bce1a
CG
837config CHECKPOINT_RESTORE
838 bool "Checkpoint/restore support" if EXPERT
839 default n
840 help
841 Enables additional kernel features in a sake of checkpoint/restore.
842 In particular it adds auxiliary prctl codes to setup process text,
843 data and heap segment sizes, and a few additional /proc filesystem
844 entries.
845
846 If unsure, say N here.
847
8dd2a82c 848menuconfig NAMESPACES
6a108a14
DR
849 bool "Namespaces support" if EXPERT
850 default !EXPERT
c5289a69
PE
851 help
852 Provides the way to make tasks work with different objects using
853 the same id. For example same IPC id may refer to different objects
854 or same user id or pid may refer to different tasks when used in
855 different namespaces.
856
8dd2a82c
DL
857if NAMESPACES
858
58bfdd6d
PE
859config UTS_NS
860 bool "UTS namespace"
17a6d441 861 default y
58bfdd6d
PE
862 help
863 In this namespace tasks see different info provided with the
864 uname() system call
865
ae5e1b22
PE
866config IPC_NS
867 bool "IPC namespace"
8dd2a82c 868 depends on (SYSVIPC || POSIX_MQUEUE)
17a6d441 869 default y
ae5e1b22
PE
870 help
871 In this namespace tasks work with IPC ids which correspond to
614b84cf 872 different IPC objects in different namespaces.
ae5e1b22 873
aee16ce7
PE
874config USER_NS
875 bool "User namespace (EXPERIMENTAL)"
8dd2a82c 876 depends on EXPERIMENTAL
e1c972b6 877 depends on UIDGID_CONVERTED
5673a94c 878 select UIDGID_STRICT_TYPE_CHECKS
e1c972b6 879
5673a94c 880 default n
aee16ce7
PE
881 help
882 This allows containers, i.e. vservers, to use user namespaces
883 to provide different user info for different servers.
884 If unsure, say N.
885
74bd59bb 886config PID_NS
9bd38c2c 887 bool "PID Namespaces"
17a6d441 888 default y
74bd59bb 889 help
12d2b8f9 890 Support process id namespaces. This allows having multiple
692105b8 891 processes with the same pid as long as they are in different
74bd59bb
PE
892 pid namespaces. This is a building block of containers.
893
d6eb633f
MH
894config NET_NS
895 bool "Network namespace"
8dd2a82c 896 depends on NET
17a6d441 897 default y
d6eb633f
MH
898 help
899 Allow user space to create what appear to be multiple instances
900 of the network stack.
901
8dd2a82c
DL
902endif # NAMESPACES
903
e1c972b6
EB
904config UIDGID_CONVERTED
905 # True if all of the selected software conmponents are known
906 # to have uid_t and gid_t converted to kuid_t and kgid_t
907 # where appropriate and are otherwise safe to use with
908 # the user namespace.
909 bool
910 default y
911
912 # List of kernel pieces that need user namespace work
913 # Features
e1c972b6
EB
914 depends on SYSVIPC = n
915 depends on IMA = n
916 depends on EVM = n
917 depends on KEYS = n
918 depends on AUDIT = n
919 depends on AUDITSYSCALL = n
920 depends on TASKSTATS = n
921 depends on TRACING = n
922 depends on FS_POSIX_ACL = n
923 depends on QUOTA = n
924 depends on QUOTACTL = n
925 depends on DEBUG_CREDENTIALS = n
926 depends on BSD_PROCESS_ACCT = n
927 depends on DRM = n
928 depends on PROC_EVENTS = n
929
930 # Networking
931 depends on NET = n
932 depends on NET_9P = n
933 depends on IPX = n
934 depends on PHONET = n
935 depends on NET_CLS_FLOW = n
936 depends on NETFILTER_XT_MATCH_OWNER = n
937 depends on NETFILTER_XT_MATCH_RECENT = n
938 depends on NETFILTER_XT_TARGET_LOG = n
939 depends on NETFILTER_NETLINK_LOG = n
940 depends on INET = n
941 depends on IPV6 = n
942 depends on IP_SCTP = n
943 depends on AF_RXRPC = n
944 depends on LLC2 = n
945 depends on NET_KEY = n
946 depends on INET_DIAG = n
947 depends on DNS_RESOLVER = n
948 depends on AX25 = n
949 depends on ATALK = n
950
951 # Filesystems
952 depends on USB_DEVICEFS = n
953 depends on USB_GADGETFS = n
954 depends on USB_FUNCTIONFS = n
955 depends on DEVTMPFS = n
956 depends on XENFS = n
957
958 depends on 9P_FS = n
959 depends on ADFS_FS = n
960 depends on AFFS_FS = n
961 depends on AFS_FS = n
962 depends on AUTOFS4_FS = n
963 depends on BEFS_FS = n
964 depends on BFS_FS = n
965 depends on BTRFS_FS = n
966 depends on CEPH_FS = n
967 depends on CIFS = n
968 depends on CODA_FS = n
969 depends on CONFIGFS_FS = n
970 depends on CRAMFS = n
971 depends on DEBUG_FS = n
972 depends on ECRYPT_FS = n
973 depends on EFS_FS = n
974 depends on EXOFS_FS = n
e1c972b6
EB
975 depends on FAT_FS = n
976 depends on FUSE_FS = n
977 depends on GFS2_FS = n
978 depends on HFS_FS = n
979 depends on HFSPLUS_FS = n
980 depends on HPFS_FS = n
981 depends on HUGETLBFS = n
982 depends on ISO9660_FS = n
983 depends on JFFS2_FS = n
984 depends on JFS_FS = n
985 depends on LOGFS = n
986 depends on MINIX_FS = n
987 depends on NCP_FS = n
988 depends on NFSD = n
989 depends on NFS_FS = n
990 depends on NILFS2_FS = n
991 depends on NTFS_FS = n
992 depends on OCFS2_FS = n
993 depends on OMFS_FS = n
e1c972b6
EB
994 depends on QNX4FS_FS = n
995 depends on QNX6FS_FS = n
996 depends on REISERFS_FS = n
997 depends on SQUASHFS = n
e1c972b6 998 depends on SYSV_FS = n
e1c972b6
EB
999 depends on UBIFS_FS = n
1000 depends on UDF_FS = n
1001 depends on UFS_FS = n
1002 depends on VXFS_FS = n
1003 depends on XFS_FS = n
1004
1005 depends on !UML || HOSTFS = n
1006
1007 # The rare drivers that won't build
1008 depends on AIRO = n
1009 depends on AIRO_CS = n
1010 depends on TUN = n
1011 depends on INFINIBAND_QIB = n
1012 depends on BLK_DEV_LOOP = n
1013 depends on ANDROID_BINDER_IPC = n
1014
1015 # Security modules
1016 depends on SECURITY_TOMOYO = n
1017 depends on SECURITY_APPARMOR = n
1018
5673a94c
EB
1019config UIDGID_STRICT_TYPE_CHECKS
1020 bool "Require conversions between uid/gids and their internal representation"
e1c972b6 1021 depends on UIDGID_CONVERTED
5673a94c
EB
1022 default n
1023 help
1024 While the nececessary conversions are being added to all subsystems this option allows
1025 the code to continue to build for unconverted subsystems.
1026
1027 Say Y here if you want the strict type checking enabled
1028
5091faa4
MG
1029config SCHED_AUTOGROUP
1030 bool "Automatic process group scheduling"
1031 select EVENTFD
1032 select CGROUPS
1033 select CGROUP_SCHED
1034 select FAIR_GROUP_SCHED
1035 help
1036 This option optimizes the scheduler for common desktop workloads by
1037 automatically creating and populating task groups. This separation
1038 of workloads isolates aggressive CPU burners (like build jobs) from
1039 desktop applications. Task group autogeneration is currently based
1040 upon task session.
1041
7af37bec
DL
1042config MM_OWNER
1043 bool
1044
1045config SYSFS_DEPRECATED
5d6a4ea5 1046 bool "Enable deprecated sysfs features to support old userspace tools"
7af37bec
DL
1047 depends on SYSFS
1048 default n
1049 help
1050 This option adds code that switches the layout of the "block" class
1051 devices, to not show up in /sys/class/block/, but only in
1052 /sys/block/.
1053
1054 This switch is only active when the sysfs.deprecated=1 boot option is
1055 passed or the SYSFS_DEPRECATED_V2 option is set.
1056
1057 This option allows new kernels to run on old distributions and tools,
1058 which might get confused by /sys/class/block/. Since 2007/2008 all
1059 major distributions and tools handle this just fine.
1060
1061 Recent distributions and userspace tools after 2009/2010 depend on
1062 the existence of /sys/class/block/, and will not work with this
1063 option enabled.
1064
1065 Only if you are using a new kernel on an old distribution, you might
1066 need to say Y here.
1067
1068config SYSFS_DEPRECATED_V2
5d6a4ea5 1069 bool "Enable deprecated sysfs features by default"
7af37bec
DL
1070 default n
1071 depends on SYSFS
1072 depends on SYSFS_DEPRECATED
1073 help
1074 Enable deprecated sysfs by default.
1075
1076 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1077 option.
1078
1079 Only if you are using a new kernel on an old distribution, you might
1080 need to say Y here. Even then, odds are you would not need it
1081 enabled, you can always pass the boot option if absolutely necessary.
1082
1083config RELAY
1084 bool "Kernel->user space relay support (formerly relayfs)"
1085 help
1086 This option enables support for relay interface support in
1087 certain file systems (such as debugfs).
1088 It is designed to provide an efficient mechanism for tools and
1089 facilities to relay large amounts of data from kernel space to
1090 user space.
1091
1092 If unsure, say N.
1093
f991633d
DG
1094config BLK_DEV_INITRD
1095 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1096 depends on BROKEN || !FRV
1097 help
1098 The initial RAM filesystem is a ramfs which is loaded by the
1099 boot loader (loadlin or lilo) and that is mounted as root
1100 before the normal boot procedure. It is typically used to
1101 load modules needed to mount the "real" root file system,
1102 etc. See <file:Documentation/initrd.txt> for details.
1103
1104 If RAM disk support (BLK_DEV_RAM) is also included, this
1105 also enables initial RAM disk (initrd) support and adds
1106 15 Kbytes (more on some other architectures) to the kernel size.
1107
1108 If unsure say Y.
1109
c33df4ea
JPS
1110if BLK_DEV_INITRD
1111
dbec4866
SR
1112source "usr/Kconfig"
1113
c33df4ea
JPS
1114endif
1115
c45b4f1f 1116config CC_OPTIMIZE_FOR_SIZE
96fffeb4 1117 bool "Optimize for size"
c45b4f1f
LT
1118 help
1119 Enabling this option will pass "-Os" instead of "-O2" to gcc
1120 resulting in a smaller kernel.
1121
775a7229 1122 If unsure, say Y.
c45b4f1f 1123
0847062a
RD
1124config SYSCTL
1125 bool
1126
b943c460
RD
1127config ANON_INODES
1128 bool
1129
6a108a14
DR
1130menuconfig EXPERT
1131 bool "Configure standard kernel features (expert users)"
f505c553
JT
1132 # Unhide debug options, to make the on-by-default options visible
1133 select DEBUG_KERNEL
1da177e4
LT
1134 help
1135 This option allows certain base kernel options and settings
1136 to be disabled or tweaked. This is for specialized
1137 environments which can tolerate a "non-standard" kernel.
1138 Only use this if you really know what you are doing.
1139
ae81f9e3 1140config UID16
6a108a14 1141 bool "Enable 16-bit UID system calls" if EXPERT
09337f50 1142 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
ae81f9e3
CE
1143 default y
1144 help
1145 This enables the legacy 16-bit UID syscall wrappers.
1146
b89a8171 1147config SYSCTL_SYSCALL
6a108a14 1148 bool "Sysctl syscall support" if EXPERT
26a7034b 1149 depends on PROC_SYSCTL
c736de60 1150 default n
b89a8171 1151 select SYSCTL
ae81f9e3 1152 ---help---
13bb7e37
EB
1153 sys_sysctl uses binary paths that have been found challenging
1154 to properly maintain and use. The interface in /proc/sys
1155 using paths with ascii names is now the primary path to this
1156 information.
b89a8171 1157
13bb7e37
EB
1158 Almost nothing using the binary sysctl interface so if you are
1159 trying to save some space it is probably safe to disable this,
1160 making your kernel marginally smaller.
b89a8171 1161
c736de60 1162 If unsure say N here.
ae81f9e3 1163
1da177e4 1164config KALLSYMS
6a108a14 1165 bool "Load all symbols for debugging/ksymoops" if EXPERT
1da177e4
LT
1166 default y
1167 help
1168 Say Y here to let the kernel print out symbolic crash information and
1169 symbolic stack backtraces. This increases the size of the kernel
1170 somewhat, as all symbols have to be loaded into the kernel image.
1171
1172config KALLSYMS_ALL
1173 bool "Include all symbols in kallsyms"
1174 depends on DEBUG_KERNEL && KALLSYMS
1175 help
71a83ec7
AB
1176 Normally kallsyms only contains the symbols of functions for nicer
1177 OOPS messages and backtraces (i.e., symbols from the text and inittext
1178 sections). This is sufficient for most cases. And only in very rare
1179 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1180 names of variables from the data sections, etc).
1181
1182 This option makes sure that all symbols are loaded into the kernel
1183 image (i.e., symbols from all sections) in cost of increased kernel
1184 size (depending on the kernel configuration, it may be 300KiB or
1185 something like this).
1186
1187 Say N unless you really need all symbols.
d59745ce 1188
712f47ce 1189config HOTPLUG
6a108a14 1190 bool "Support for hot-pluggable devices" if EXPERT
712f47ce
GKH
1191 default y
1192 help
1193 This option is provided for the case where no hotplug or uevent
1194 capabilities is wanted by the kernel. You should only consider
1195 disabling this option for embedded systems that do not use modules, a
1196 dynamic /dev tree, or dynamic device discovery. Just say Y.
1197
d59745ce
MM
1198config PRINTK
1199 default y
6a108a14 1200 bool "Enable support for printk" if EXPERT
d59745ce
MM
1201 help
1202 This option enables normal printk support. Removing it
1203 eliminates most of the message strings from the kernel image
1204 and makes the kernel more or less silent. As this makes it
1205 very difficult to diagnose system problems, saying N here is
1206 strongly discouraged.
1207
c8538a7a 1208config BUG
6a108a14 1209 bool "BUG() support" if EXPERT
c8538a7a
MM
1210 default y
1211 help
1212 Disabling this option eliminates support for BUG and WARN, reducing
1213 the size of your kernel image and potentially quietly ignoring
1214 numerous fatal conditions. You should only consider disabling this
1215 option for embedded systems with no facilities for reporting errors.
1216 Just say Y.
1217
708e9a79
MM
1218config ELF_CORE
1219 default y
6a108a14 1220 bool "Enable ELF core dumps" if EXPERT
708e9a79
MM
1221 help
1222 Enable support for generating core dumps. Disabling saves about 4k.
1223
8761f1ab 1224
e5e1d3cb 1225config PCSPKR_PLATFORM
6a108a14 1226 bool "Enable PC-Speaker support" if EXPERT
8761f1ab 1227 depends on HAVE_PCSPKR_PLATFORM
15f304b6 1228 select I8253_LOCK
e5e1d3cb
SS
1229 default y
1230 help
1231 This option allows to disable the internal PC-Speaker
1232 support, saving some memory.
1233
8761f1ab
RB
1234config HAVE_PCSPKR_PLATFORM
1235 bool
1236
1da177e4
LT
1237config BASE_FULL
1238 default y
6a108a14 1239 bool "Enable full-sized data structures for core" if EXPERT
1da177e4
LT
1240 help
1241 Disabling this option reduces the size of miscellaneous core
1242 kernel data structures. This saves memory on small machines,
1243 but may reduce performance.
1244
1245config FUTEX
6a108a14 1246 bool "Enable futex support" if EXPERT
1da177e4 1247 default y
23f78d4a 1248 select RT_MUTEXES
1da177e4
LT
1249 help
1250 Disabling this option will cause the kernel to be built without
1251 support for "fast userspace mutexes". The resulting kernel may not
1252 run glibc-based applications correctly.
1253
1254config EPOLL
6a108a14 1255 bool "Enable eventpoll support" if EXPERT
1da177e4 1256 default y
448e3cee 1257 select ANON_INODES
1da177e4
LT
1258 help
1259 Disabling this option will cause the kernel to be built without
1260 support for epoll family of system calls.
1261
fba2afaa 1262config SIGNALFD
6a108a14 1263 bool "Enable signalfd() system call" if EXPERT
448e3cee 1264 select ANON_INODES
fba2afaa
DL
1265 default y
1266 help
1267 Enable the signalfd() system call that allows to receive signals
1268 on a file descriptor.
1269
1270 If unsure, say Y.
1271
b215e283 1272config TIMERFD
6a108a14 1273 bool "Enable timerfd() system call" if EXPERT
448e3cee 1274 select ANON_INODES
b215e283
DL
1275 default y
1276 help
1277 Enable the timerfd() system call that allows to receive timer
1278 events on a file descriptor.
1279
1280 If unsure, say Y.
1281
e1ad7468 1282config EVENTFD
6a108a14 1283 bool "Enable eventfd() system call" if EXPERT
448e3cee 1284 select ANON_INODES
e1ad7468
DL
1285 default y
1286 help
1287 Enable the eventfd() system call that allows to receive both
1288 kernel notification (ie. KAIO) or userspace notifications.
1289
1290 If unsure, say Y.
1291
1da177e4 1292config SHMEM
6a108a14 1293 bool "Use full shmem filesystem" if EXPERT
1da177e4
LT
1294 default y
1295 depends on MMU
1296 help
1297 The shmem is an internal filesystem used to manage shared memory.
1298 It is backed by swap and manages resource limits. It is also exported
1299 to userspace as tmpfs if TMPFS is enabled. Disabling this
1300 option replaces shmem and tmpfs with the much simpler ramfs code,
1301 which may be appropriate on small systems without swap.
1302
ebf3f09c 1303config AIO
6a108a14 1304 bool "Enable AIO support" if EXPERT
ebf3f09c
TP
1305 default y
1306 help
1307 This option enables POSIX asynchronous I/O which may by used
1308 by some high performance threaded applications. Disabling
1309 this option saves about 7k.
1310
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RD
1311config EMBEDDED
1312 bool "Embedded system"
1313 select EXPERT
1314 help
1315 This option should be enabled if compiling the kernel for
1316 an embedded system so certain expert options are available
1317 for configuration.
1318
cdd6c482 1319config HAVE_PERF_EVENTS
0793a61d 1320 bool
018df72d
MF
1321 help
1322 See tools/perf/design.txt for details.
0793a61d 1323
906010b2
PZ
1324config PERF_USE_VMALLOC
1325 bool
1326 help
1327 See tools/perf/design.txt for details
1328
57c0c15b 1329menu "Kernel Performance Events And Counters"
0793a61d 1330
cdd6c482 1331config PERF_EVENTS
57c0c15b 1332 bool "Kernel performance events and counters"
392d65a9 1333 default y if PROFILING
cdd6c482 1334 depends on HAVE_PERF_EVENTS
4c59e467 1335 select ANON_INODES
e360adbe 1336 select IRQ_WORK
0793a61d 1337 help
57c0c15b
IM
1338 Enable kernel support for various performance events provided
1339 by software and hardware.
0793a61d 1340
dd77038d 1341 Software events are supported either built-in or via the
57c0c15b 1342 use of generic tracepoints.
0793a61d 1343
57c0c15b
IM
1344 Most modern CPUs support performance events via performance
1345 counter registers. These registers count the number of certain
0793a61d
TG
1346 types of hw events: such as instructions executed, cachemisses
1347 suffered, or branches mis-predicted - without slowing down the
1348 kernel or applications. These registers can also trigger interrupts
1349 when a threshold number of events have passed - and can thus be
1350 used to profile the code that runs on that CPU.
1351
57c0c15b 1352 The Linux Performance Event subsystem provides an abstraction of
dd77038d 1353 these software and hardware event capabilities, available via a
57c0c15b 1354 system call and used by the "perf" utility in tools/perf/. It
0793a61d
TG
1355 provides per task and per CPU counters, and it provides event
1356 capabilities on top of those.
1357
1358 Say Y if unsure.
1359
906010b2
PZ
1360config DEBUG_PERF_USE_VMALLOC
1361 default n
1362 bool "Debug: use vmalloc to back perf mmap() buffers"
1363 depends on PERF_EVENTS && DEBUG_KERNEL
1364 select PERF_USE_VMALLOC
1365 help
1366 Use vmalloc memory to back perf mmap() buffers.
1367
1368 Mostly useful for debugging the vmalloc code on platforms
1369 that don't require it.
1370
1371 Say N if unsure.
1372
0793a61d
TG
1373endmenu
1374
f8891e5e
CL
1375config VM_EVENT_COUNTERS
1376 default y
6a108a14 1377 bool "Enable VM event counters for /proc/vmstat" if EXPERT
f8891e5e 1378 help
2aea4fb6
PJ
1379 VM event counters are needed for event counts to be shown.
1380 This option allows the disabling of the VM event counters
6a108a14 1381 on EXPERT systems. /proc/vmstat will only show page counts
2aea4fb6 1382 if VM event counters are disabled.
f8891e5e 1383
3d137310
TP
1384config PCI_QUIRKS
1385 default y
6a108a14 1386 bool "Enable PCI quirk workarounds" if EXPERT
61cfc7e4 1387 depends on PCI
3d137310
TP
1388 help
1389 This enables workarounds for various PCI chipset
1390 bugs/quirks. Disable this only if your target machine is
1391 unaffected by PCI quirks.
1392
41ecc55b
CL
1393config SLUB_DEBUG
1394 default y
6a108a14 1395 bool "Enable SLUB debugging support" if EXPERT
f6acb635 1396 depends on SLUB && SYSFS
41ecc55b
CL
1397 help
1398 SLUB has extensive debug support features. Disabling these can
1399 result in significant savings in code size. This also disables
1400 SLUB sysfs support. /sys/slab will not exist and there will be
1401 no support for cache validation etc.
1402
b943c460
RD
1403config COMPAT_BRK
1404 bool "Disable heap randomization"
1405 default y
1406 help
1407 Randomizing heap placement makes heap exploits harder, but it
1408 also breaks ancient binaries (including anything libc5 based).
1409 This option changes the bootup default to heap randomization
692105b8 1410 disabled, and can be overridden at runtime by setting
b943c460
RD
1411 /proc/sys/kernel/randomize_va_space to 2.
1412
1413 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1414
81819f0f
CL
1415choice
1416 prompt "Choose SLAB allocator"
a0acd820 1417 default SLUB
81819f0f
CL
1418 help
1419 This option allows to select a slab allocator.
1420
1421config SLAB
1422 bool "SLAB"
1423 help
1424 The regular slab allocator that is established and known to work
34013886 1425 well in all environments. It organizes cache hot objects in
02f56210 1426 per cpu and per node queues.
81819f0f
CL
1427
1428config SLUB
81819f0f
CL
1429 bool "SLUB (Unqueued Allocator)"
1430 help
1431 SLUB is a slab allocator that minimizes cache line usage
1432 instead of managing queues of cached objects (SLAB approach).
1433 Per cpu caching is realized using slabs of objects instead
1434 of queues of objects. SLUB can use memory efficiently
02f56210
SA
1435 and has enhanced diagnostics. SLUB is the default choice for
1436 a slab allocator.
81819f0f
CL
1437
1438config SLOB
6a108a14 1439 depends on EXPERT
81819f0f
CL
1440 bool "SLOB (Simple Allocator)"
1441 help
37291458
MM
1442 SLOB replaces the stock allocator with a drastically simpler
1443 allocator. SLOB is generally more space efficient but
1444 does not perform as well on large systems.
81819f0f
CL
1445
1446endchoice
1447
ea637639
JZ
1448config MMAP_ALLOW_UNINITIALIZED
1449 bool "Allow mmapped anonymous memory to be uninitialized"
6a108a14 1450 depends on EXPERT && !MMU
ea637639
JZ
1451 default n
1452 help
1453 Normally, and according to the Linux spec, anonymous memory obtained
1454 from mmap() has it's contents cleared before it is passed to
1455 userspace. Enabling this config option allows you to request that
1456 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1457 providing a huge performance boost. If this option is not enabled,
1458 then the flag will be ignored.
1459
1460 This is taken advantage of by uClibc's malloc(), and also by
1461 ELF-FDPIC binfmt's brk and stack allocator.
1462
1463 Because of the obvious security issues, this option should only be
1464 enabled on embedded devices where you control what is run in
1465 userspace. Since that isn't generally a problem on no-MMU systems,
1466 it is normally safe to say Y here.
1467
1468 See Documentation/nommu-mmap.txt for more information.
1469
125e5645 1470config PROFILING
b309a294 1471 bool "Profiling support"
125e5645
MD
1472 help
1473 Say Y here to enable the extended profiling support mechanisms used
1474 by profilers such as OProfile.
1475
5f87f112
IM
1476#
1477# Place an empty function call at each tracepoint site. Can be
1478# dynamically changed for a probe function.
1479#
97e1c18e 1480config TRACEPOINTS
5f87f112 1481 bool
97e1c18e 1482
fb32e03f
MD
1483source "arch/Kconfig"
1484
1da177e4
LT
1485endmenu # General setup
1486
ee7e5516
DES
1487config HAVE_GENERIC_DMA_COHERENT
1488 bool
1489 default n
1490
158a9624
LT
1491config SLABINFO
1492 bool
1493 depends on PROC_FS
0f389ec6 1494 depends on SLAB || SLUB_DEBUG
158a9624
LT
1495 default y
1496
ae81f9e3
CE
1497config RT_MUTEXES
1498 boolean
ae81f9e3 1499
1da177e4
LT
1500config BASE_SMALL
1501 int
1502 default 0 if BASE_FULL
1503 default 1 if !BASE_FULL
1504
66da5733 1505menuconfig MODULES
1da177e4
LT
1506 bool "Enable loadable module support"
1507 help
1508 Kernel modules are small pieces of compiled code which can
1509 be inserted in the running kernel, rather than being
1510 permanently built into the kernel. You use the "modprobe"
1511 tool to add (and sometimes remove) them. If you say Y here,
1512 many parts of the kernel can be built as modules (by
1513 answering M instead of Y where indicated): this is most
1514 useful for infrequently used options which are not required
1515 for booting. For more information, see the man pages for
1516 modprobe, lsmod, modinfo, insmod and rmmod.
1517
1518 If you say Y here, you will need to run "make
1519 modules_install" to put the modules under /lib/modules/
1520 where modprobe can find them (you may need to be root to do
1521 this).
1522
1523 If unsure, say Y.
1524
0b0de144
RD
1525if MODULES
1526
826e4506
LT
1527config MODULE_FORCE_LOAD
1528 bool "Forced module loading"
826e4506
LT
1529 default n
1530 help
91e37a79
RR
1531 Allow loading of modules without version information (ie. modprobe
1532 --force). Forced module loading sets the 'F' (forced) taint flag and
1533 is usually a really bad idea.
826e4506 1534
1da177e4
LT
1535config MODULE_UNLOAD
1536 bool "Module unloading"
1da177e4
LT
1537 help
1538 Without this option you will not be able to unload any
1539 modules (note that some modules may not be unloadable
f7f5b675
DV
1540 anyway), which makes your kernel smaller, faster
1541 and simpler. If unsure, say Y.
1da177e4
LT
1542
1543config MODULE_FORCE_UNLOAD
1544 bool "Forced module unloading"
1545 depends on MODULE_UNLOAD && EXPERIMENTAL
1546 help
1547 This option allows you to force a module to unload, even if the
1548 kernel believes it is unsafe: the kernel will remove the module
1549 without waiting for anyone to stop using it (using the -f option to
1550 rmmod). This is mainly for kernel developers and desperate users.
1551 If unsure, say N.
1552
1da177e4 1553config MODVERSIONS
0d541643 1554 bool "Module versioning support"
1da177e4
LT
1555 help
1556 Usually, you have to use modules compiled with your kernel.
1557 Saying Y here makes it sometimes possible to use modules
1558 compiled for different kernels, by adding enough information
1559 to the modules to (hopefully) spot any changes which would
1560 make them incompatible with the kernel you are running. If
1561 unsure, say N.
1562
1563config MODULE_SRCVERSION_ALL
1564 bool "Source checksum for all modules"
1da177e4
LT
1565 help
1566 Modules which contain a MODULE_VERSION get an extra "srcversion"
1567 field inserted into their modinfo section, which contains a
1568 sum of the source files which made it. This helps maintainers
1569 see exactly which source was used to build a module (since
1570 others sometimes change the module source without updating
1571 the version). With this option, such a "srcversion" field
1572 will be created for all modules. If unsure, say N.
1573
0b0de144
RD
1574endif # MODULES
1575
98a79d6a
RR
1576config INIT_ALL_POSSIBLE
1577 bool
1578 help
5f054e31
RR
1579 Back when each arch used to define their own cpu_online_mask and
1580 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
98a79d6a
RR
1581 with all 1s, and others with all 0s. When they were centralised,
1582 it was better to provide this option than to break all the archs
692105b8 1583 and have several arch maintainers pursuing me down dark alleys.
98a79d6a 1584
1da177e4
LT
1585config STOP_MACHINE
1586 bool
1587 default y
1588 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1589 help
1590 Need stop_machine() primitive.
3a65dfe8 1591
3a65dfe8 1592source "block/Kconfig"
e98c3202
AK
1593
1594config PREEMPT_NOTIFIERS
1595 bool
e260be67 1596
16295bec
SK
1597config PADATA
1598 depends on SMP
1599 bool
1600
6beb0009 1601source "kernel/Kconfig.locks"