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1config ARCH
2 string
3 option env="ARCH"
4
5config KERNELVERSION
6 string
7 option env="KERNELVERSION"
8
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9config DEFCONFIG_LIST
10 string
b2670eac 11 depends on !UML
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12 option defconfig_list
13 default "/lib/modules/$UNAME_RELEASE/.config"
14 default "/etc/kernel-config"
15 default "/boot/config-$UNAME_RELEASE"
73531905 16 default "$ARCH_DEFCONFIG"
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17 default "arch/$ARCH/defconfig"
18
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19config CONSTRUCTORS
20 bool
21 depends on !UML
22 default y
23
ff0cfc66 24menu "General setup"
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25
26config EXPERIMENTAL
27 bool "Prompt for development and/or incomplete code/drivers"
28 ---help---
29 Some of the various things that Linux supports (such as network
30 drivers, file systems, network protocols, etc.) can be in a state
31 of development where the functionality, stability, or the level of
32 testing is not yet high enough for general use. This is usually
33 known as the "alpha-test" phase among developers. If a feature is
34 currently in alpha-test, then the developers usually discourage
35 uninformed widespread use of this feature by the general public to
36 avoid "Why doesn't this work?" type mail messages. However, active
37 testing and use of these systems is welcomed. Just be aware that it
38 may not meet the normal level of reliability or it may fail to work
39 in some special cases. Detailed bug reports from people familiar
40 with the kernel internals are usually welcomed by the developers
41 (before submitting bug reports, please read the documents
42 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
43 <file:Documentation/BUG-HUNTING>, and
44 <file:Documentation/oops-tracing.txt> in the kernel source).
45
46 This option will also make obsoleted drivers available. These are
47 drivers that have been replaced by something else, and/or are
48 scheduled to be removed in a future kernel release.
49
50 Unless you intend to help test and develop a feature or driver that
51 falls into this category, or you have a situation that requires
52 using these features, you should probably say N here, which will
53 cause the configurator to present you with fewer choices. If
54 you say Y here, you will be offered the choice of using features or
55 drivers that are currently considered to be in the alpha-test phase.
56
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57config BROKEN
58 bool
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59
60config BROKEN_ON_SMP
61 bool
62 depends on BROKEN || !SMP
63 default y
64
65config LOCK_KERNEL
66 bool
67 depends on SMP || PREEMPT
68 default y
69
70config INIT_ENV_ARG_LIMIT
71 int
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72 default 32 if !UML
73 default 128 if UML
1da177e4 74 help
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75 Maximum of each of the number of arguments and environment
76 variables passed to init from the kernel command line.
1da177e4 77
1da177e4 78
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79config CROSS_COMPILE
80 string "Cross-compiler tool prefix"
81 help
82 Same as running 'make CROSS_COMPILE=prefix-' but stored for
83 default make runs in this kernel build directory. You don't
84 need to set this unless you want the configured kernel build
85 directory to select the cross-compiler automatically.
86
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87config LOCALVERSION
88 string "Local version - append to kernel release"
89 help
90 Append an extra string to the end of your kernel version.
91 This will show up when you type uname, for example.
92 The string you set here will be appended after the contents of
93 any files with a filename matching localversion* in your
94 object and source tree, in that order. Your total string can
95 be a maximum of 64 characters.
96
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97config LOCALVERSION_AUTO
98 bool "Automatically append version information to the version string"
99 default y
100 help
101 This will try to automatically determine if the current tree is a
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102 release tree by looking for git tags that belong to the current
103 top of tree revision.
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104
105 A string of the format -gxxxxxxxx will be added to the localversion
6e5a5420 106 if a git-based tree is found. The string generated by this will be
aaebf433 107 appended after any matching localversion* files, and after the value
6e5a5420 108 set in CONFIG_LOCALVERSION.
aaebf433 109
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110 (The actual string used here is the first eight characters produced
111 by running the command:
112
113 $ git rev-parse --verify HEAD
114
115 which is done within the script "scripts/setlocalversion".)
aaebf433 116
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117config HAVE_KERNEL_GZIP
118 bool
119
120config HAVE_KERNEL_BZIP2
121 bool
122
123config HAVE_KERNEL_LZMA
124 bool
125
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126config HAVE_KERNEL_LZO
127 bool
128
30d65dbf 129choice
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130 prompt "Kernel compression mode"
131 default KERNEL_GZIP
7dd65feb 132 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_LZO
2e9f3bdd 133 help
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134 The linux kernel is a kind of self-extracting executable.
135 Several compression algorithms are available, which differ
136 in efficiency, compression and decompression speed.
137 Compression speed is only relevant when building a kernel.
138 Decompression speed is relevant at each boot.
139
140 If you have any problems with bzip2 or lzma compressed
141 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
142 version of this functionality (bzip2 only), for 2.4, was
143 supplied by Christian Ludwig)
144
145 High compression options are mostly useful for users, who
146 are low on disk space (embedded systems), but for whom ram
147 size matters less.
148
149 If in doubt, select 'gzip'
150
151config KERNEL_GZIP
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152 bool "Gzip"
153 depends on HAVE_KERNEL_GZIP
154 help
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155 The old and tried gzip compression. It provides a good balance
156 between compression ratio and decompression speed.
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157
158config KERNEL_BZIP2
159 bool "Bzip2"
2e9f3bdd 160 depends on HAVE_KERNEL_BZIP2
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161 help
162 Its compression ratio and speed is intermediate.
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163 Decompression speed is slowest among the three. The kernel
164 size is about 10% smaller with bzip2, in comparison to gzip.
165 Bzip2 uses a large amount of memory. For modern kernels you
166 will need at least 8MB RAM or more for booting.
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167
168config KERNEL_LZMA
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169 bool "LZMA"
170 depends on HAVE_KERNEL_LZMA
171 help
172 The most recent compression algorithm.
173 Its ratio is best, decompression speed is between the other
174 two. Compression is slowest. The kernel size is about 33%
175 smaller with LZMA in comparison to gzip.
30d65dbf 176
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177config KERNEL_LZO
178 bool "LZO"
179 depends on HAVE_KERNEL_LZO
180 help
181 Its compression ratio is the poorest among the 4. The kernel
182 size is about about 10% bigger than gzip; however its speed
183 (both compression and decompression) is the fastest.
184
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185endchoice
186
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187config SWAP
188 bool "Support for paging of anonymous memory (swap)"
9361401e 189 depends on MMU && BLOCK
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190 default y
191 help
192 This option allows you to choose whether you want to have support
92c3504e 193 for so called swap devices or swap files in your kernel that are
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194 used to provide more virtual memory than the actual RAM present
195 in your computer. If unsure say Y.
196
197config SYSVIPC
198 bool "System V IPC"
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199 ---help---
200 Inter Process Communication is a suite of library functions and
201 system calls which let processes (running programs) synchronize and
202 exchange information. It is generally considered to be a good thing,
203 and some programs won't run unless you say Y here. In particular, if
204 you want to run the DOS emulator dosemu under Linux (read the
205 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
206 you'll need to say Y here.
207
208 You can find documentation about IPC with "info ipc" and also in
209 section 6.4 of the Linux Programmer's Guide, available from
210 <http://www.tldp.org/guides.html>.
211
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212config SYSVIPC_SYSCTL
213 bool
214 depends on SYSVIPC
215 depends on SYSCTL
216 default y
217
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218config POSIX_MQUEUE
219 bool "POSIX Message Queues"
220 depends on NET && EXPERIMENTAL
221 ---help---
222 POSIX variant of message queues is a part of IPC. In POSIX message
223 queues every message has a priority which decides about succession
224 of receiving it by a process. If you want to compile and run
225 programs written e.g. for Solaris with use of its POSIX message
b0e37650 226 queues (functions mq_*) say Y here.
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227
228 POSIX message queues are visible as a filesystem called 'mqueue'
229 and can be mounted somewhere if you want to do filesystem
230 operations on message queues.
231
232 If unsure, say Y.
233
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234config POSIX_MQUEUE_SYSCTL
235 bool
236 depends on POSIX_MQUEUE
237 depends on SYSCTL
238 default y
239
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240config BSD_PROCESS_ACCT
241 bool "BSD Process Accounting"
242 help
243 If you say Y here, a user level program will be able to instruct the
244 kernel (via a special system call) to write process accounting
245 information to a file: whenever a process exits, information about
246 that process will be appended to the file by the kernel. The
247 information includes things such as creation time, owning user,
248 command name, memory usage, controlling terminal etc. (the complete
249 list is in the struct acct in <file:include/linux/acct.h>). It is
250 up to the user level program to do useful things with this
251 information. This is generally a good idea, so say Y.
252
253config BSD_PROCESS_ACCT_V3
254 bool "BSD Process Accounting version 3 file format"
255 depends on BSD_PROCESS_ACCT
256 default n
257 help
258 If you say Y here, the process accounting information is written
259 in a new file format that also logs the process IDs of each
260 process and it's parent. Note that this file format is incompatible
261 with previous v0/v1/v2 file formats, so you will need updated tools
262 for processing it. A preliminary version of these tools is available
37a4c940 263 at <http://www.gnu.org/software/acct/>.
1da177e4 264
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265config TASKSTATS
266 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
267 depends on NET
268 default n
269 help
270 Export selected statistics for tasks/processes through the
271 generic netlink interface. Unlike BSD process accounting, the
272 statistics are available during the lifetime of tasks/processes as
273 responses to commands. Like BSD accounting, they are sent to user
274 space on task exit.
275
276 Say N if unsure.
277
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278config TASK_DELAY_ACCT
279 bool "Enable per-task delay accounting (EXPERIMENTAL)"
6f44993f 280 depends on TASKSTATS
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281 help
282 Collect information on time spent by a task waiting for system
283 resources like cpu, synchronous block I/O completion and swapping
284 in pages. Such statistics can help in setting a task's priorities
285 relative to other tasks for cpu, io, rss limits etc.
286
287 Say N if unsure.
288
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289config TASK_XACCT
290 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
291 depends on TASKSTATS
292 help
293 Collect extended task accounting data and send the data
294 to userland for processing over the taskstats interface.
295
296 Say N if unsure.
297
298config TASK_IO_ACCOUNTING
299 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
300 depends on TASK_XACCT
301 help
302 Collect information on the number of bytes of storage I/O which this
303 task has caused.
304
305 Say N if unsure.
306
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307config AUDIT
308 bool "Auditing support"
804a6a49 309 depends on NET
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310 help
311 Enable auditing infrastructure that can be used with another
312 kernel subsystem, such as SELinux (which requires this for
313 logging of avc messages output). Does not do system-call
314 auditing without CONFIG_AUDITSYSCALL.
315
316config AUDITSYSCALL
317 bool "Enable system-call auditing support"
022382a5 318 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
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319 default y if SECURITY_SELINUX
320 help
321 Enable low-overhead system-call auditing infrastructure that
322 can be used independently or with another kernel subsystem,
67640b60 323 such as SELinux.
1da177e4 324
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325config AUDIT_WATCH
326 def_bool y
327 depends on AUDITSYSCALL
328 select FSNOTIFY
1da177e4 329
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330config AUDIT_TREE
331 def_bool y
63c882a0 332 depends on AUDITSYSCALL
28a3a7eb 333 select FSNOTIFY
74c3cbe3 334
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335menu "RCU Subsystem"
336
337choice
338 prompt "RCU Implementation"
31c9a24e 339 default TREE_RCU
c903ff83 340
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341config TREE_RCU
342 bool "Tree-based hierarchical RCU"
687d7a96 343 depends on !PREEMPT && SMP
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344 help
345 This option selects the RCU implementation that is
346 designed for very large SMP system with hundreds or
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347 thousands of CPUs. It also scales down nicely to
348 smaller systems.
c903ff83 349
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350config TREE_PREEMPT_RCU
351 bool "Preemptable tree-based hierarchical RCU"
352 depends on PREEMPT
353 help
354 This option selects the RCU implementation that is
355 designed for very large SMP systems with hundreds or
356 thousands of CPUs, but for which real-time response
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357 is also required. It also scales down nicely to
358 smaller systems.
f41d911f 359
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360config TINY_RCU
361 bool "UP-only small-memory-footprint RCU"
362 depends on !SMP
363 help
364 This option selects the RCU implementation that is
365 designed for UP systems from which real-time response
366 is not required. This option greatly reduces the
367 memory footprint of RCU.
368
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369endchoice
370
371config RCU_TRACE
372 bool "Enable tracing for RCU"
6b3ef48a 373 depends on TREE_RCU || TREE_PREEMPT_RCU
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374 help
375 This option provides tracing in RCU which presents stats
376 in debugfs for debugging RCU implementation.
377
378 Say Y here if you want to enable RCU tracing
379 Say N if you are unsure.
380
381config RCU_FANOUT
382 int "Tree-based hierarchical RCU fanout value"
383 range 2 64 if 64BIT
384 range 2 32 if !64BIT
f41d911f 385 depends on TREE_RCU || TREE_PREEMPT_RCU
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386 default 64 if 64BIT
387 default 32 if !64BIT
388 help
389 This option controls the fanout of hierarchical implementations
390 of RCU, allowing RCU to work efficiently on machines with
391 large numbers of CPUs. This value must be at least the cube
392 root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
393 systems and up to 262,144 for 64-bit systems.
394
395 Select a specific number if testing RCU itself.
396 Take the default if unsure.
397
398config RCU_FANOUT_EXACT
399 bool "Disable tree-based hierarchical RCU auto-balancing"
f41d911f 400 depends on TREE_RCU || TREE_PREEMPT_RCU
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401 default n
402 help
403 This option forces use of the exact RCU_FANOUT value specified,
404 regardless of imbalances in the hierarchy. This is useful for
405 testing RCU itself, and might one day be useful on systems with
406 strong NUMA behavior.
407
408 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
409
410 Say N if unsure.
411
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412config RCU_FAST_NO_HZ
413 bool "Accelerate last non-dyntick-idle CPU's grace periods"
414 depends on TREE_RCU && NO_HZ && SMP
415 default n
416 help
417 This option causes RCU to attempt to accelerate grace periods
418 in order to allow the final CPU to enter dynticks-idle state
419 more quickly. On the other hand, this option increases the
420 overhead of the dynticks-idle checking, particularly on systems
421 with large numbers of CPUs.
422
423 Say Y if energy efficiency is critically important, particularly
424 if you have relatively few CPUs.
425
426 Say N if you are unsure.
427
c903ff83 428config TREE_RCU_TRACE
f41d911f 429 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
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430 select DEBUG_FS
431 help
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432 This option provides tracing for the TREE_RCU and
433 TREE_PREEMPT_RCU implementations, permitting Makefile to
434 trivially select kernel/rcutree_trace.c.
c903ff83 435
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436endmenu # "RCU Subsystem"
437
1da177e4 438config IKCONFIG
f2443ab6 439 tristate "Kernel .config support"
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440 ---help---
441 This option enables the complete Linux kernel ".config" file
442 contents to be saved in the kernel. It provides documentation
443 of which kernel options are used in a running kernel or in an
444 on-disk kernel. This information can be extracted from the kernel
445 image file with the script scripts/extract-ikconfig and used as
446 input to rebuild the current kernel or to build another kernel.
447 It can also be extracted from a running kernel by reading
448 /proc/config.gz if enabled (below).
449
450config IKCONFIG_PROC
451 bool "Enable access to .config through /proc/config.gz"
452 depends on IKCONFIG && PROC_FS
453 ---help---
454 This option enables access to the kernel configuration file
455 through /proc/config.gz.
456
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457config LOG_BUF_SHIFT
458 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
459 range 12 21
f17a32e9 460 default 17
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461 help
462 Select kernel log buffer size as a power of 2.
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463 Examples:
464 17 => 128 KB
465 16 => 64 KB
466 15 => 32 KB
467 14 => 16 KB
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468 13 => 8 KB
469 12 => 4 KB
470
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471#
472# Architectures with an unreliable sched_clock() should select this:
473#
474config HAVE_UNSTABLE_SCHED_CLOCK
475 bool
476
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477menuconfig CGROUPS
478 boolean "Control Group support"
0dea1168 479 depends on EVENTFD
5cdc38f9 480 help
23964d2d 481 This option adds support for grouping sets of processes together, for
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482 use with process control subsystems such as Cpusets, CFS, memory
483 controls or device isolation.
484 See
5cdc38f9 485 - Documentation/scheduler/sched-design-CFS.txt (CFS)
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486 - Documentation/cgroups/ (features for grouping, isolation
487 and resource control)
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488
489 Say N if unsure.
490
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491if CGROUPS
492
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493config CGROUP_DEBUG
494 bool "Example debug cgroup subsystem"
495 depends on CGROUPS
496 default n
497 help
498 This option enables a simple cgroup subsystem that
499 exports useful debugging information about the cgroups
23964d2d 500 framework.
5cdc38f9 501
23964d2d 502 Say N if unsure.
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503
504config CGROUP_NS
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505 bool "Namespace cgroup subsystem"
506 depends on CGROUPS
507 help
508 Provides a simple namespace cgroup subsystem to
509 provide hierarchical naming of sets of namespaces,
510 for instance virtual servers and checkpoint/restart
511 jobs.
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512
513config CGROUP_FREEZER
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514 bool "Freezer cgroup subsystem"
515 depends on CGROUPS
516 help
517 Provides a way to freeze and unfreeze all tasks in a
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518 cgroup.
519
520config CGROUP_DEVICE
521 bool "Device controller for cgroups"
522 depends on CGROUPS && EXPERIMENTAL
523 help
524 Provides a cgroup implementing whitelists for devices which
525 a process in the cgroup can mknod or open.
526
527config CPUSETS
528 bool "Cpuset support"
db7f47cf 529 depends on CGROUPS
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530 help
531 This option will let you create and manage CPUSETs which
532 allow dynamically partitioning a system into sets of CPUs and
533 Memory Nodes and assigning tasks to run only within those sets.
534 This is primarily useful on large SMP or NUMA systems.
535
536 Say N if unsure.
537
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538config PROC_PID_CPUSET
539 bool "Include legacy /proc/<pid>/cpuset file"
540 depends on CPUSETS
541 default y
542
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543config CGROUP_CPUACCT
544 bool "Simple CPU accounting cgroup subsystem"
545 depends on CGROUPS
546 help
547 Provides a simple Resource Controller for monitoring the
23964d2d 548 total CPU consumed by the tasks in a cgroup.
d842de87 549
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550config RESOURCE_COUNTERS
551 bool "Resource counters"
552 help
553 This option enables controller independent resource accounting
23964d2d 554 infrastructure that works with cgroups.
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555 depends on CGROUPS
556
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557config CGROUP_MEM_RES_CTLR
558 bool "Memory Resource Controller for Control Groups"
559 depends on CGROUPS && RESOURCE_COUNTERS
cf475ad2 560 select MM_OWNER
00f0b825 561 help
84ad6d70 562 Provides a memory resource controller that manages both anonymous
21acb9ca 563 memory and page cache. (See Documentation/cgroups/memory.txt)
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564
565 Note that setting this option increases fixed memory overhead
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566 associated with each page of memory in the system. By this,
567 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
568 usage tracking struct at boot. Total amount of this is printed out
569 at boot.
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570
571 Only enable when you're ok with these trade offs and really
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572 sure you need the memory resource controller. Even when you enable
573 this, you can set "cgroup_disable=memory" at your boot option to
574 disable memory resource controller and you can avoid overheads.
c9d5409f 575 (and lose benefits of memory resource controller)
00f0b825 576
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577 This config option also selects MM_OWNER config option, which
578 could in turn add some fork/exit overhead.
579
c077719b 580config CGROUP_MEM_RES_CTLR_SWAP
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581 bool "Memory Resource Controller Swap Extension"
582 depends on CGROUP_MEM_RES_CTLR && SWAP
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583 help
584 Add swap management feature to memory resource controller. When you
585 enable this, you can limit mem+swap usage per cgroup. In other words,
586 when you disable this, memory resource controller has no cares to
587 usage of swap...a process can exhaust all of the swap. This extension
588 is useful when you want to avoid exhaustion swap but this itself
589 adds more overheads and consumes memory for remembering information.
590 Especially if you use 32bit system or small memory system, please
591 be careful about enabling this. When memory resource controller
592 is disabled by boot option, this will be automatically disabled and
593 there will be no overhead from this. Even when you set this config=y,
594 if boot option "noswapaccount" is set, swap will not be accounted.
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595 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
596 size is 4096bytes, 512k per 1Gbytes of swap.
c077719b 597
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598menuconfig CGROUP_SCHED
599 bool "Group CPU scheduler"
600 depends on EXPERIMENTAL && CGROUPS
601 default n
602 help
603 This feature lets CPU scheduler recognize task groups and control CPU
604 bandwidth allocation to such task groups. It uses cgroups to group
605 tasks.
606
607if CGROUP_SCHED
608config FAIR_GROUP_SCHED
609 bool "Group scheduling for SCHED_OTHER"
610 depends on CGROUP_SCHED
611 default CGROUP_SCHED
612
613config RT_GROUP_SCHED
614 bool "Group scheduling for SCHED_RR/FIFO"
615 depends on EXPERIMENTAL
616 depends on CGROUP_SCHED
617 default n
618 help
619 This feature lets you explicitly allocate real CPU bandwidth
32bd7eb5 620 to task groups. If enabled, it will also make it impossible to
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621 schedule realtime tasks for non-root users until you allocate
622 realtime bandwidth for them.
623 See Documentation/scheduler/sched-rt-group.txt for more information.
624
625endif #CGROUP_SCHED
626
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627config BLK_CGROUP
628 tristate "Block IO controller"
629 depends on CGROUPS && BLOCK
630 default n
631 ---help---
632 Generic block IO controller cgroup interface. This is the common
633 cgroup interface which should be used by various IO controlling
634 policies.
635
636 Currently, CFQ IO scheduler uses it to recognize task groups and
637 control disk bandwidth allocation (proportional time slice allocation)
638 to such task groups.
639
640 This option only enables generic Block IO controller infrastructure.
641 One needs to also enable actual IO controlling logic in CFQ for it
642 to take effect. (CONFIG_CFQ_GROUP_IOSCHED=y).
643
644 See Documentation/cgroups/blkio-controller.txt for more information.
645
646config DEBUG_BLK_CGROUP
647 bool "Enable Block IO controller debugging"
648 depends on BLK_CGROUP
649 default n
650 ---help---
651 Enable some debugging help. Currently it exports additional stat
652 files in a cgroup which can be useful for debugging.
653
23964d2d 654endif # CGROUPS
c077719b 655
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656config MM_OWNER
657 bool
5cdc38f9 658
88a22c98 659config SYSFS_DEPRECATED
d47846c5
IM
660 bool
661
662config SYSFS_DEPRECATED_V2
9e9868a7 663 bool "enable deprecated sysfs features to support old userspace tools"
9148fe87 664 depends on SYSFS
f6ee649f 665 default n
d47846c5 666 select SYSFS_DEPRECATED
88a22c98 667 help
fce3e804 668 This option switches the layout of sysfs to the deprecated
f6ee649f 669 version. Do not use it on recent distributions.
fce3e804
KS
670
671 The current sysfs layout features a unified device tree at
672 /sys/devices/, which is able to express a hierarchy between
673 class devices. If the deprecated option is set to Y, the
674 unified device tree is split into a bus device tree at
675 /sys/devices/ and several individual class device trees at
676 /sys/class/. The class and bus devices will be connected by
677 "<subsystem>:<name>" and the "device" links. The "block"
678 class devices, will not show up in /sys/class/block/. Some
679 subsystems will suppress the creation of some devices which
680 depend on the unified device tree.
681
682 This option is not a pure compatibility option that can
683 be safely enabled on newer distributions. It will change the
684 layout of sysfs to the non-extensible deprecated version,
685 and disable some features, which can not be exported without
686 confusing older userspace tools. Since 2007/2008 all major
687 distributions do not enable this option, and ship no tools which
688 depend on the deprecated layout or this option.
689
690 If you are using a new kernel on an older distribution, or use
691 older userspace tools, you might need to say Y here. Do not say Y,
692 if the original kernel, that came with your distribution, has
693 this option set to N.
88a22c98 694
b86ff981
JA
695config RELAY
696 bool "Kernel->user space relay support (formerly relayfs)"
697 help
698 This option enables support for relay interface support in
699 certain file systems (such as debugfs).
700 It is designed to provide an efficient mechanism for tools and
701 facilities to relay large amounts of data from kernel space to
702 user space.
703
704 If unsure, say N.
705
c5289a69
PE
706config NAMESPACES
707 bool "Namespaces support" if EMBEDDED
708 default !EMBEDDED
709 help
710 Provides the way to make tasks work with different objects using
711 the same id. For example same IPC id may refer to different objects
712 or same user id or pid may refer to different tasks when used in
713 different namespaces.
714
58bfdd6d
PE
715config UTS_NS
716 bool "UTS namespace"
717 depends on NAMESPACES
718 help
719 In this namespace tasks see different info provided with the
720 uname() system call
721
ae5e1b22
PE
722config IPC_NS
723 bool "IPC namespace"
614b84cf 724 depends on NAMESPACES && (SYSVIPC || POSIX_MQUEUE)
ae5e1b22
PE
725 help
726 In this namespace tasks work with IPC ids which correspond to
614b84cf 727 different IPC objects in different namespaces.
ae5e1b22 728
aee16ce7
PE
729config USER_NS
730 bool "User namespace (EXPERIMENTAL)"
731 depends on NAMESPACES && EXPERIMENTAL
732 help
733 This allows containers, i.e. vservers, to use user namespaces
734 to provide different user info for different servers.
735 If unsure, say N.
736
74bd59bb
PE
737config PID_NS
738 bool "PID Namespaces (EXPERIMENTAL)"
739 default n
740 depends on NAMESPACES && EXPERIMENTAL
741 help
12d2b8f9 742 Support process id namespaces. This allows having multiple
692105b8 743 processes with the same pid as long as they are in different
74bd59bb
PE
744 pid namespaces. This is a building block of containers.
745
746 Unless you want to work with an experimental feature
747 say N here.
748
d6eb633f
MH
749config NET_NS
750 bool "Network namespace"
751 default n
752 depends on NAMESPACES && EXPERIMENTAL && NET
753 help
754 Allow user space to create what appear to be multiple instances
755 of the network stack.
756
f991633d
DG
757config BLK_DEV_INITRD
758 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
759 depends on BROKEN || !FRV
760 help
761 The initial RAM filesystem is a ramfs which is loaded by the
762 boot loader (loadlin or lilo) and that is mounted as root
763 before the normal boot procedure. It is typically used to
764 load modules needed to mount the "real" root file system,
765 etc. See <file:Documentation/initrd.txt> for details.
766
767 If RAM disk support (BLK_DEV_RAM) is also included, this
768 also enables initial RAM disk (initrd) support and adds
769 15 Kbytes (more on some other architectures) to the kernel size.
770
771 If unsure say Y.
772
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JPS
773if BLK_DEV_INITRD
774
dbec4866
SR
775source "usr/Kconfig"
776
c33df4ea
JPS
777endif
778
c45b4f1f 779config CC_OPTIMIZE_FOR_SIZE
96fffeb4 780 bool "Optimize for size"
c45b4f1f 781 default y
c45b4f1f
LT
782 help
783 Enabling this option will pass "-Os" instead of "-O2" to gcc
784 resulting in a smaller kernel.
785
775a7229 786 If unsure, say Y.
c45b4f1f 787
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RD
788config SYSCTL
789 bool
790
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RD
791config ANON_INODES
792 bool
793
1da177e4
LT
794menuconfig EMBEDDED
795 bool "Configure standard kernel features (for small systems)"
796 help
797 This option allows certain base kernel options and settings
798 to be disabled or tweaked. This is for specialized
799 environments which can tolerate a "non-standard" kernel.
800 Only use this if you really know what you are doing.
801
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CE
802config UID16
803 bool "Enable 16-bit UID system calls" if EMBEDDED
09337f50 804 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
ae81f9e3
CE
805 default y
806 help
807 This enables the legacy 16-bit UID syscall wrappers.
808
b89a8171 809config SYSCTL_SYSCALL
0847062a 810 bool "Sysctl syscall support" if EMBEDDED
26a7034b 811 depends on PROC_SYSCTL
13bb7e37 812 default y
b89a8171 813 select SYSCTL
ae81f9e3 814 ---help---
13bb7e37
EB
815 sys_sysctl uses binary paths that have been found challenging
816 to properly maintain and use. The interface in /proc/sys
817 using paths with ascii names is now the primary path to this
818 information.
b89a8171 819
13bb7e37
EB
820 Almost nothing using the binary sysctl interface so if you are
821 trying to save some space it is probably safe to disable this,
822 making your kernel marginally smaller.
b89a8171 823
13bb7e37 824 If unsure say Y here.
ae81f9e3 825
1da177e4 826config KALLSYMS
979c6a1e 827 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
1da177e4
LT
828 default y
829 help
830 Say Y here to let the kernel print out symbolic crash information and
831 symbolic stack backtraces. This increases the size of the kernel
832 somewhat, as all symbols have to be loaded into the kernel image.
833
834config KALLSYMS_ALL
835 bool "Include all symbols in kallsyms"
836 depends on DEBUG_KERNEL && KALLSYMS
837 help
838 Normally kallsyms only contains the symbols of functions, for nicer
839 OOPS messages. Some debuggers can use kallsyms for other
f9f97bc0
JJ
840 symbols too: say Y here to include all symbols, if you need them
841 and you don't care about adding 300k to the size of your kernel.
1da177e4
LT
842
843 Say N.
844
845config KALLSYMS_EXTRA_PASS
846 bool "Do an extra kallsyms pass"
847 depends on KALLSYMS
848 help
849 If kallsyms is not working correctly, the build will fail with
850 inconsistent kallsyms data. If that occurs, log a bug report and
851 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
852 Always say N here unless you find a bug in kallsyms, which must be
853 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
854 you wait for kallsyms to be fixed.
855
d59745ce 856
712f47ce
GKH
857config HOTPLUG
858 bool "Support for hot-pluggable devices" if EMBEDDED
859 default y
860 help
861 This option is provided for the case where no hotplug or uevent
862 capabilities is wanted by the kernel. You should only consider
863 disabling this option for embedded systems that do not use modules, a
864 dynamic /dev tree, or dynamic device discovery. Just say Y.
865
d59745ce
MM
866config PRINTK
867 default y
868 bool "Enable support for printk" if EMBEDDED
869 help
870 This option enables normal printk support. Removing it
871 eliminates most of the message strings from the kernel image
872 and makes the kernel more or less silent. As this makes it
873 very difficult to diagnose system problems, saying N here is
874 strongly discouraged.
875
c8538a7a
MM
876config BUG
877 bool "BUG() support" if EMBEDDED
878 default y
879 help
880 Disabling this option eliminates support for BUG and WARN, reducing
881 the size of your kernel image and potentially quietly ignoring
882 numerous fatal conditions. You should only consider disabling this
883 option for embedded systems with no facilities for reporting errors.
884 Just say Y.
885
708e9a79
MM
886config ELF_CORE
887 default y
888 bool "Enable ELF core dumps" if EMBEDDED
889 help
890 Enable support for generating core dumps. Disabling saves about 4k.
891
e5e1d3cb
SS
892config PCSPKR_PLATFORM
893 bool "Enable PC-Speaker support" if EMBEDDED
894 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
895 default y
896 help
897 This option allows to disable the internal PC-Speaker
898 support, saving some memory.
899
1da177e4
LT
900config BASE_FULL
901 default y
902 bool "Enable full-sized data structures for core" if EMBEDDED
903 help
904 Disabling this option reduces the size of miscellaneous core
905 kernel data structures. This saves memory on small machines,
906 but may reduce performance.
907
908config FUTEX
909 bool "Enable futex support" if EMBEDDED
910 default y
23f78d4a 911 select RT_MUTEXES
1da177e4
LT
912 help
913 Disabling this option will cause the kernel to be built without
914 support for "fast userspace mutexes". The resulting kernel may not
915 run glibc-based applications correctly.
916
917config EPOLL
918 bool "Enable eventpoll support" if EMBEDDED
919 default y
448e3cee 920 select ANON_INODES
1da177e4
LT
921 help
922 Disabling this option will cause the kernel to be built without
923 support for epoll family of system calls.
924
fba2afaa
DL
925config SIGNALFD
926 bool "Enable signalfd() system call" if EMBEDDED
448e3cee 927 select ANON_INODES
fba2afaa
DL
928 default y
929 help
930 Enable the signalfd() system call that allows to receive signals
931 on a file descriptor.
932
933 If unsure, say Y.
934
b215e283
DL
935config TIMERFD
936 bool "Enable timerfd() system call" if EMBEDDED
448e3cee 937 select ANON_INODES
b215e283
DL
938 default y
939 help
940 Enable the timerfd() system call that allows to receive timer
941 events on a file descriptor.
942
943 If unsure, say Y.
944
e1ad7468
DL
945config EVENTFD
946 bool "Enable eventfd() system call" if EMBEDDED
448e3cee 947 select ANON_INODES
e1ad7468
DL
948 default y
949 help
950 Enable the eventfd() system call that allows to receive both
951 kernel notification (ie. KAIO) or userspace notifications.
952
953 If unsure, say Y.
954
1da177e4
LT
955config SHMEM
956 bool "Use full shmem filesystem" if EMBEDDED
957 default y
958 depends on MMU
959 help
960 The shmem is an internal filesystem used to manage shared memory.
961 It is backed by swap and manages resource limits. It is also exported
962 to userspace as tmpfs if TMPFS is enabled. Disabling this
963 option replaces shmem and tmpfs with the much simpler ramfs code,
964 which may be appropriate on small systems without swap.
965
ebf3f09c
TP
966config AIO
967 bool "Enable AIO support" if EMBEDDED
968 default y
969 help
970 This option enables POSIX asynchronous I/O which may by used
971 by some high performance threaded applications. Disabling
972 this option saves about 7k.
973
cdd6c482 974config HAVE_PERF_EVENTS
0793a61d 975 bool
018df72d
MF
976 help
977 See tools/perf/design.txt for details.
0793a61d 978
906010b2
PZ
979config PERF_USE_VMALLOC
980 bool
981 help
982 See tools/perf/design.txt for details
983
57c0c15b 984menu "Kernel Performance Events And Counters"
0793a61d 985
cdd6c482 986config PERF_EVENTS
57c0c15b
IM
987 bool "Kernel performance events and counters"
988 default y if (PROFILING || PERF_COUNTERS)
cdd6c482 989 depends on HAVE_PERF_EVENTS
4c59e467 990 select ANON_INODES
0793a61d 991 help
57c0c15b
IM
992 Enable kernel support for various performance events provided
993 by software and hardware.
0793a61d 994
dd77038d 995 Software events are supported either built-in or via the
57c0c15b 996 use of generic tracepoints.
0793a61d 997
57c0c15b
IM
998 Most modern CPUs support performance events via performance
999 counter registers. These registers count the number of certain
0793a61d
TG
1000 types of hw events: such as instructions executed, cachemisses
1001 suffered, or branches mis-predicted - without slowing down the
1002 kernel or applications. These registers can also trigger interrupts
1003 when a threshold number of events have passed - and can thus be
1004 used to profile the code that runs on that CPU.
1005
57c0c15b 1006 The Linux Performance Event subsystem provides an abstraction of
dd77038d 1007 these software and hardware event capabilities, available via a
57c0c15b 1008 system call and used by the "perf" utility in tools/perf/. It
0793a61d
TG
1009 provides per task and per CPU counters, and it provides event
1010 capabilities on top of those.
1011
1012 Say Y if unsure.
1013
57c0c15b
IM
1014config PERF_COUNTERS
1015 bool "Kernel performance counters (old config option)"
1016 depends on HAVE_PERF_EVENTS
1017 help
1018 This config has been obsoleted by the PERF_EVENTS
1019 config option - please see that one for details.
1020
1021 It has no effect on the kernel whether you enable
1022 it or not, it is a compatibility placeholder.
1023
1024 Say N if unsure.
1025
906010b2
PZ
1026config DEBUG_PERF_USE_VMALLOC
1027 default n
1028 bool "Debug: use vmalloc to back perf mmap() buffers"
1029 depends on PERF_EVENTS && DEBUG_KERNEL
1030 select PERF_USE_VMALLOC
1031 help
1032 Use vmalloc memory to back perf mmap() buffers.
1033
1034 Mostly useful for debugging the vmalloc code on platforms
1035 that don't require it.
1036
1037 Say N if unsure.
1038
0793a61d
TG
1039endmenu
1040
f8891e5e
CL
1041config VM_EVENT_COUNTERS
1042 default y
1043 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
1044 help
2aea4fb6
PJ
1045 VM event counters are needed for event counts to be shown.
1046 This option allows the disabling of the VM event counters
1047 on EMBEDDED systems. /proc/vmstat will only show page counts
1048 if VM event counters are disabled.
f8891e5e 1049
3d137310
TP
1050config PCI_QUIRKS
1051 default y
61cfc7e4
GU
1052 bool "Enable PCI quirk workarounds" if EMBEDDED
1053 depends on PCI
3d137310
TP
1054 help
1055 This enables workarounds for various PCI chipset
1056 bugs/quirks. Disable this only if your target machine is
1057 unaffected by PCI quirks.
1058
41ecc55b
CL
1059config SLUB_DEBUG
1060 default y
1061 bool "Enable SLUB debugging support" if EMBEDDED
f6acb635 1062 depends on SLUB && SYSFS
41ecc55b
CL
1063 help
1064 SLUB has extensive debug support features. Disabling these can
1065 result in significant savings in code size. This also disables
1066 SLUB sysfs support. /sys/slab will not exist and there will be
1067 no support for cache validation etc.
1068
b943c460
RD
1069config COMPAT_BRK
1070 bool "Disable heap randomization"
1071 default y
1072 help
1073 Randomizing heap placement makes heap exploits harder, but it
1074 also breaks ancient binaries (including anything libc5 based).
1075 This option changes the bootup default to heap randomization
692105b8 1076 disabled, and can be overridden at runtime by setting
b943c460
RD
1077 /proc/sys/kernel/randomize_va_space to 2.
1078
1079 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1080
81819f0f
CL
1081choice
1082 prompt "Choose SLAB allocator"
a0acd820 1083 default SLUB
81819f0f
CL
1084 help
1085 This option allows to select a slab allocator.
1086
1087config SLAB
1088 bool "SLAB"
1089 help
1090 The regular slab allocator that is established and known to work
34013886 1091 well in all environments. It organizes cache hot objects in
02f56210 1092 per cpu and per node queues.
81819f0f
CL
1093
1094config SLUB
81819f0f
CL
1095 bool "SLUB (Unqueued Allocator)"
1096 help
1097 SLUB is a slab allocator that minimizes cache line usage
1098 instead of managing queues of cached objects (SLAB approach).
1099 Per cpu caching is realized using slabs of objects instead
1100 of queues of objects. SLUB can use memory efficiently
02f56210
SA
1101 and has enhanced diagnostics. SLUB is the default choice for
1102 a slab allocator.
81819f0f
CL
1103
1104config SLOB
84a01c2f 1105 depends on EMBEDDED
81819f0f
CL
1106 bool "SLOB (Simple Allocator)"
1107 help
37291458
MM
1108 SLOB replaces the stock allocator with a drastically simpler
1109 allocator. SLOB is generally more space efficient but
1110 does not perform as well on large systems.
81819f0f
CL
1111
1112endchoice
1113
ea637639
JZ
1114config MMAP_ALLOW_UNINITIALIZED
1115 bool "Allow mmapped anonymous memory to be uninitialized"
1116 depends on EMBEDDED && !MMU
1117 default n
1118 help
1119 Normally, and according to the Linux spec, anonymous memory obtained
1120 from mmap() has it's contents cleared before it is passed to
1121 userspace. Enabling this config option allows you to request that
1122 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1123 providing a huge performance boost. If this option is not enabled,
1124 then the flag will be ignored.
1125
1126 This is taken advantage of by uClibc's malloc(), and also by
1127 ELF-FDPIC binfmt's brk and stack allocator.
1128
1129 Because of the obvious security issues, this option should only be
1130 enabled on embedded devices where you control what is run in
1131 userspace. Since that isn't generally a problem on no-MMU systems,
1132 it is normally safe to say Y here.
1133
1134 See Documentation/nommu-mmap.txt for more information.
1135
125e5645 1136config PROFILING
b309a294 1137 bool "Profiling support"
125e5645
MD
1138 help
1139 Say Y here to enable the extended profiling support mechanisms used
1140 by profilers such as OProfile.
1141
5f87f112
IM
1142#
1143# Place an empty function call at each tracepoint site. Can be
1144# dynamically changed for a probe function.
1145#
97e1c18e 1146config TRACEPOINTS
5f87f112 1147 bool
97e1c18e 1148
fb32e03f
MD
1149source "arch/Kconfig"
1150
1da177e4
LT
1151endmenu # General setup
1152
ee7e5516
DES
1153config HAVE_GENERIC_DMA_COHERENT
1154 bool
1155 default n
1156
158a9624
LT
1157config SLABINFO
1158 bool
1159 depends on PROC_FS
0f389ec6 1160 depends on SLAB || SLUB_DEBUG
158a9624
LT
1161 default y
1162
ae81f9e3
CE
1163config RT_MUTEXES
1164 boolean
ae81f9e3 1165
1da177e4
LT
1166config BASE_SMALL
1167 int
1168 default 0 if BASE_FULL
1169 default 1 if !BASE_FULL
1170
66da5733 1171menuconfig MODULES
1da177e4
LT
1172 bool "Enable loadable module support"
1173 help
1174 Kernel modules are small pieces of compiled code which can
1175 be inserted in the running kernel, rather than being
1176 permanently built into the kernel. You use the "modprobe"
1177 tool to add (and sometimes remove) them. If you say Y here,
1178 many parts of the kernel can be built as modules (by
1179 answering M instead of Y where indicated): this is most
1180 useful for infrequently used options which are not required
1181 for booting. For more information, see the man pages for
1182 modprobe, lsmod, modinfo, insmod and rmmod.
1183
1184 If you say Y here, you will need to run "make
1185 modules_install" to put the modules under /lib/modules/
1186 where modprobe can find them (you may need to be root to do
1187 this).
1188
1189 If unsure, say Y.
1190
0b0de144
RD
1191if MODULES
1192
826e4506
LT
1193config MODULE_FORCE_LOAD
1194 bool "Forced module loading"
826e4506
LT
1195 default n
1196 help
91e37a79
RR
1197 Allow loading of modules without version information (ie. modprobe
1198 --force). Forced module loading sets the 'F' (forced) taint flag and
1199 is usually a really bad idea.
826e4506 1200
1da177e4
LT
1201config MODULE_UNLOAD
1202 bool "Module unloading"
1da177e4
LT
1203 help
1204 Without this option you will not be able to unload any
1205 modules (note that some modules may not be unloadable
f7f5b675
DV
1206 anyway), which makes your kernel smaller, faster
1207 and simpler. If unsure, say Y.
1da177e4
LT
1208
1209config MODULE_FORCE_UNLOAD
1210 bool "Forced module unloading"
1211 depends on MODULE_UNLOAD && EXPERIMENTAL
1212 help
1213 This option allows you to force a module to unload, even if the
1214 kernel believes it is unsafe: the kernel will remove the module
1215 without waiting for anyone to stop using it (using the -f option to
1216 rmmod). This is mainly for kernel developers and desperate users.
1217 If unsure, say N.
1218
1da177e4 1219config MODVERSIONS
0d541643 1220 bool "Module versioning support"
1da177e4
LT
1221 help
1222 Usually, you have to use modules compiled with your kernel.
1223 Saying Y here makes it sometimes possible to use modules
1224 compiled for different kernels, by adding enough information
1225 to the modules to (hopefully) spot any changes which would
1226 make them incompatible with the kernel you are running. If
1227 unsure, say N.
1228
1229config MODULE_SRCVERSION_ALL
1230 bool "Source checksum for all modules"
1da177e4
LT
1231 help
1232 Modules which contain a MODULE_VERSION get an extra "srcversion"
1233 field inserted into their modinfo section, which contains a
1234 sum of the source files which made it. This helps maintainers
1235 see exactly which source was used to build a module (since
1236 others sometimes change the module source without updating
1237 the version). With this option, such a "srcversion" field
1238 will be created for all modules. If unsure, say N.
1239
0b0de144
RD
1240endif # MODULES
1241
98a79d6a
RR
1242config INIT_ALL_POSSIBLE
1243 bool
1244 help
1245 Back when each arch used to define their own cpu_online_map and
1246 cpu_possible_map, some of them chose to initialize cpu_possible_map
1247 with all 1s, and others with all 0s. When they were centralised,
1248 it was better to provide this option than to break all the archs
692105b8 1249 and have several arch maintainers pursuing me down dark alleys.
98a79d6a 1250
1da177e4
LT
1251config STOP_MACHINE
1252 bool
1253 default y
1254 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1255 help
1256 Need stop_machine() primitive.
3a65dfe8 1257
3a65dfe8 1258source "block/Kconfig"
e98c3202
AK
1259
1260config PREEMPT_NOTIFIERS
1261 bool
e260be67 1262
16295bec
SK
1263config PADATA
1264 depends on SMP
1265 bool
1266
6beb0009 1267source "kernel/Kconfig.locks"