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80daa560 RZ |
1 | config ARCH |
2 | string | |
3 | option env="ARCH" | |
4 | ||
5 | config KERNELVERSION | |
6 | string | |
7 | option env="KERNELVERSION" | |
8 | ||
face4374 RZ |
9 | config DEFCONFIG_LIST |
10 | string | |
b2670eac | 11 | depends on !UML |
face4374 RZ |
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 "$ARCH_DEFCONFIG" |
face4374 RZ |
17 | default "arch/$ARCH/defconfig" |
18 | ||
b99b87f7 PO |
19 | config CONSTRUCTORS |
20 | bool | |
21 | depends on !UML | |
b99b87f7 | 22 | |
e360adbe PZ |
23 | config HAVE_IRQ_WORK |
24 | bool | |
25 | ||
26 | config IRQ_WORK | |
27 | bool | |
28 | depends on HAVE_IRQ_WORK | |
29 | ||
ff0cfc66 | 30 | menu "General setup" |
1da177e4 LT |
31 | |
32 | config EXPERIMENTAL | |
33 | bool "Prompt for development and/or incomplete code/drivers" | |
34 | ---help--- | |
35 | Some of the various things that Linux supports (such as network | |
36 | drivers, file systems, network protocols, etc.) can be in a state | |
37 | of development where the functionality, stability, or the level of | |
38 | testing is not yet high enough for general use. This is usually | |
39 | known as the "alpha-test" phase among developers. If a feature is | |
40 | currently in alpha-test, then the developers usually discourage | |
41 | uninformed widespread use of this feature by the general public to | |
42 | avoid "Why doesn't this work?" type mail messages. However, active | |
43 | testing and use of these systems is welcomed. Just be aware that it | |
44 | may not meet the normal level of reliability or it may fail to work | |
45 | in some special cases. Detailed bug reports from people familiar | |
46 | with the kernel internals are usually welcomed by the developers | |
47 | (before submitting bug reports, please read the documents | |
48 | <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>, | |
49 | <file:Documentation/BUG-HUNTING>, and | |
50 | <file:Documentation/oops-tracing.txt> in the kernel source). | |
51 | ||
52 | This option will also make obsoleted drivers available. These are | |
53 | drivers that have been replaced by something else, and/or are | |
54 | scheduled to be removed in a future kernel release. | |
55 | ||
56 | Unless you intend to help test and develop a feature or driver that | |
57 | falls into this category, or you have a situation that requires | |
58 | using these features, you should probably say N here, which will | |
59 | cause the configurator to present you with fewer choices. If | |
60 | you say Y here, you will be offered the choice of using features or | |
61 | drivers that are currently considered to be in the alpha-test phase. | |
62 | ||
1da177e4 LT |
63 | config BROKEN |
64 | bool | |
1da177e4 LT |
65 | |
66 | config BROKEN_ON_SMP | |
67 | bool | |
68 | depends on BROKEN || !SMP | |
69 | default y | |
70 | ||
1da177e4 LT |
71 | config INIT_ENV_ARG_LIMIT |
72 | int | |
dd673bca AB |
73 | default 32 if !UML |
74 | default 128 if UML | |
1da177e4 | 75 | help |
34ad92c2 RD |
76 | Maximum of each of the number of arguments and environment |
77 | variables passed to init from the kernel command line. | |
1da177e4 | 78 | |
1da177e4 | 79 | |
84336466 RM |
80 | config CROSS_COMPILE |
81 | string "Cross-compiler tool prefix" | |
82 | help | |
83 | Same as running 'make CROSS_COMPILE=prefix-' but stored for | |
84 | default make runs in this kernel build directory. You don't | |
85 | need to set this unless you want the configured kernel build | |
86 | directory to select the cross-compiler automatically. | |
87 | ||
1da177e4 LT |
88 | config LOCALVERSION |
89 | string "Local version - append to kernel release" | |
90 | help | |
91 | Append an extra string to the end of your kernel version. | |
92 | This will show up when you type uname, for example. | |
93 | The string you set here will be appended after the contents of | |
94 | any files with a filename matching localversion* in your | |
95 | object and source tree, in that order. Your total string can | |
96 | be a maximum of 64 characters. | |
97 | ||
aaebf433 RA |
98 | config LOCALVERSION_AUTO |
99 | bool "Automatically append version information to the version string" | |
100 | default y | |
101 | help | |
102 | This will try to automatically determine if the current tree is a | |
6e5a5420 RD |
103 | release tree by looking for git tags that belong to the current |
104 | top of tree revision. | |
aaebf433 RA |
105 | |
106 | A string of the format -gxxxxxxxx will be added to the localversion | |
6e5a5420 | 107 | if a git-based tree is found. The string generated by this will be |
aaebf433 | 108 | appended after any matching localversion* files, and after the value |
6e5a5420 | 109 | set in CONFIG_LOCALVERSION. |
aaebf433 | 110 | |
6e5a5420 RD |
111 | (The actual string used here is the first eight characters produced |
112 | by running the command: | |
113 | ||
114 | $ git rev-parse --verify HEAD | |
115 | ||
116 | which is done within the script "scripts/setlocalversion".) | |
aaebf433 | 117 | |
2e9f3bdd PA |
118 | config HAVE_KERNEL_GZIP |
119 | bool | |
120 | ||
121 | config HAVE_KERNEL_BZIP2 | |
122 | bool | |
123 | ||
124 | config HAVE_KERNEL_LZMA | |
125 | bool | |
126 | ||
3ebe1243 LC |
127 | config HAVE_KERNEL_XZ |
128 | bool | |
129 | ||
7dd65feb AT |
130 | config HAVE_KERNEL_LZO |
131 | bool | |
132 | ||
30d65dbf | 133 | choice |
2e9f3bdd PA |
134 | prompt "Kernel compression mode" |
135 | default KERNEL_GZIP | |
3ebe1243 | 136 | depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO |
2e9f3bdd | 137 | help |
30d65dbf AK |
138 | The linux kernel is a kind of self-extracting executable. |
139 | Several compression algorithms are available, which differ | |
140 | in efficiency, compression and decompression speed. | |
141 | Compression speed is only relevant when building a kernel. | |
142 | Decompression speed is relevant at each boot. | |
143 | ||
144 | If you have any problems with bzip2 or lzma compressed | |
145 | kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older | |
146 | version of this functionality (bzip2 only), for 2.4, was | |
147 | supplied by Christian Ludwig) | |
148 | ||
149 | High compression options are mostly useful for users, who | |
150 | are low on disk space (embedded systems), but for whom ram | |
151 | size matters less. | |
152 | ||
153 | If in doubt, select 'gzip' | |
154 | ||
155 | config KERNEL_GZIP | |
2e9f3bdd PA |
156 | bool "Gzip" |
157 | depends on HAVE_KERNEL_GZIP | |
158 | help | |
7dd65feb AT |
159 | The old and tried gzip compression. It provides a good balance |
160 | between compression ratio and decompression speed. | |
30d65dbf AK |
161 | |
162 | config KERNEL_BZIP2 | |
163 | bool "Bzip2" | |
2e9f3bdd | 164 | depends on HAVE_KERNEL_BZIP2 |
30d65dbf AK |
165 | help |
166 | Its compression ratio and speed is intermediate. | |
2e9f3bdd PA |
167 | Decompression speed is slowest among the three. The kernel |
168 | size is about 10% smaller with bzip2, in comparison to gzip. | |
169 | Bzip2 uses a large amount of memory. For modern kernels you | |
170 | will need at least 8MB RAM or more for booting. | |
30d65dbf AK |
171 | |
172 | config KERNEL_LZMA | |
2e9f3bdd PA |
173 | bool "LZMA" |
174 | depends on HAVE_KERNEL_LZMA | |
175 | help | |
176 | The most recent compression algorithm. | |
177 | Its ratio is best, decompression speed is between the other | |
178 | two. Compression is slowest. The kernel size is about 33% | |
179 | smaller with LZMA in comparison to gzip. | |
30d65dbf | 180 | |
3ebe1243 LC |
181 | config KERNEL_XZ |
182 | bool "XZ" | |
183 | depends on HAVE_KERNEL_XZ | |
184 | help | |
185 | XZ uses the LZMA2 algorithm and instruction set specific | |
186 | BCJ filters which can improve compression ratio of executable | |
187 | code. The size of the kernel is about 30% smaller with XZ in | |
188 | comparison to gzip. On architectures for which there is a BCJ | |
189 | filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ | |
190 | will create a few percent smaller kernel than plain LZMA. | |
191 | ||
192 | The speed is about the same as with LZMA: The decompression | |
193 | speed of XZ is better than that of bzip2 but worse than gzip | |
194 | and LZO. Compression is slow. | |
195 | ||
7dd65feb AT |
196 | config KERNEL_LZO |
197 | bool "LZO" | |
198 | depends on HAVE_KERNEL_LZO | |
199 | help | |
200 | Its compression ratio is the poorest among the 4. The kernel | |
681b3049 | 201 | size is about 10% bigger than gzip; however its speed |
7dd65feb AT |
202 | (both compression and decompression) is the fastest. |
203 | ||
30d65dbf AK |
204 | endchoice |
205 | ||
bd5dc17b JT |
206 | config DEFAULT_HOSTNAME |
207 | string "Default hostname" | |
208 | default "(none)" | |
209 | help | |
210 | This option determines the default system hostname before userspace | |
211 | calls sethostname(2). The kernel traditionally uses "(none)" here, | |
212 | but you may wish to use a different default here to make a minimal | |
213 | system more usable with less configuration. | |
214 | ||
1da177e4 LT |
215 | config SWAP |
216 | bool "Support for paging of anonymous memory (swap)" | |
9361401e | 217 | depends on MMU && BLOCK |
1da177e4 LT |
218 | default y |
219 | help | |
220 | This option allows you to choose whether you want to have support | |
92c3504e | 221 | for so called swap devices or swap files in your kernel that are |
1da177e4 LT |
222 | used to provide more virtual memory than the actual RAM present |
223 | in your computer. If unsure say Y. | |
224 | ||
225 | config SYSVIPC | |
226 | bool "System V IPC" | |
1da177e4 LT |
227 | ---help--- |
228 | Inter Process Communication is a suite of library functions and | |
229 | system calls which let processes (running programs) synchronize and | |
230 | exchange information. It is generally considered to be a good thing, | |
231 | and some programs won't run unless you say Y here. In particular, if | |
232 | you want to run the DOS emulator dosemu under Linux (read the | |
233 | DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), | |
234 | you'll need to say Y here. | |
235 | ||
236 | You can find documentation about IPC with "info ipc" and also in | |
237 | section 6.4 of the Linux Programmer's Guide, available from | |
238 | <http://www.tldp.org/guides.html>. | |
239 | ||
a5494dcd EB |
240 | config SYSVIPC_SYSCTL |
241 | bool | |
242 | depends on SYSVIPC | |
243 | depends on SYSCTL | |
244 | default y | |
245 | ||
1da177e4 LT |
246 | config POSIX_MQUEUE |
247 | bool "POSIX Message Queues" | |
248 | depends on NET && EXPERIMENTAL | |
249 | ---help--- | |
250 | POSIX variant of message queues is a part of IPC. In POSIX message | |
251 | queues every message has a priority which decides about succession | |
252 | of receiving it by a process. If you want to compile and run | |
253 | programs written e.g. for Solaris with use of its POSIX message | |
b0e37650 | 254 | queues (functions mq_*) say Y here. |
1da177e4 LT |
255 | |
256 | POSIX message queues are visible as a filesystem called 'mqueue' | |
257 | and can be mounted somewhere if you want to do filesystem | |
258 | operations on message queues. | |
259 | ||
260 | If unsure, say Y. | |
261 | ||
bdc8e5f8 SH |
262 | config POSIX_MQUEUE_SYSCTL |
263 | bool | |
264 | depends on POSIX_MQUEUE | |
265 | depends on SYSCTL | |
266 | default y | |
267 | ||
1da177e4 LT |
268 | config BSD_PROCESS_ACCT |
269 | bool "BSD Process Accounting" | |
270 | help | |
271 | If you say Y here, a user level program will be able to instruct the | |
272 | kernel (via a special system call) to write process accounting | |
273 | information to a file: whenever a process exits, information about | |
274 | that process will be appended to the file by the kernel. The | |
275 | information includes things such as creation time, owning user, | |
276 | command name, memory usage, controlling terminal etc. (the complete | |
277 | list is in the struct acct in <file:include/linux/acct.h>). It is | |
278 | up to the user level program to do useful things with this | |
279 | information. This is generally a good idea, so say Y. | |
280 | ||
281 | config BSD_PROCESS_ACCT_V3 | |
282 | bool "BSD Process Accounting version 3 file format" | |
283 | depends on BSD_PROCESS_ACCT | |
284 | default n | |
285 | help | |
286 | If you say Y here, the process accounting information is written | |
287 | in a new file format that also logs the process IDs of each | |
288 | process and it's parent. Note that this file format is incompatible | |
289 | with previous v0/v1/v2 file formats, so you will need updated tools | |
290 | for processing it. A preliminary version of these tools is available | |
37a4c940 | 291 | at <http://www.gnu.org/software/acct/>. |
1da177e4 | 292 | |
990d6c2d AK |
293 | config FHANDLE |
294 | bool "open by fhandle syscalls" | |
295 | select EXPORTFS | |
296 | help | |
297 | If you say Y here, a user level program will be able to map | |
298 | file names to handle and then later use the handle for | |
299 | different file system operations. This is useful in implementing | |
300 | userspace file servers, which now track files using handles instead | |
301 | of names. The handle would remain the same even if file names | |
302 | get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) | |
303 | syscalls. | |
304 | ||
c757249a SN |
305 | config TASKSTATS |
306 | bool "Export task/process statistics through netlink (EXPERIMENTAL)" | |
307 | depends on NET | |
308 | default n | |
309 | help | |
310 | Export selected statistics for tasks/processes through the | |
311 | generic netlink interface. Unlike BSD process accounting, the | |
312 | statistics are available during the lifetime of tasks/processes as | |
313 | responses to commands. Like BSD accounting, they are sent to user | |
314 | space on task exit. | |
315 | ||
316 | Say N if unsure. | |
317 | ||
ca74e92b SN |
318 | config TASK_DELAY_ACCT |
319 | bool "Enable per-task delay accounting (EXPERIMENTAL)" | |
6f44993f | 320 | depends on TASKSTATS |
ca74e92b SN |
321 | help |
322 | Collect information on time spent by a task waiting for system | |
323 | resources like cpu, synchronous block I/O completion and swapping | |
324 | in pages. Such statistics can help in setting a task's priorities | |
325 | relative to other tasks for cpu, io, rss limits etc. | |
326 | ||
327 | Say N if unsure. | |
328 | ||
18f705f4 AD |
329 | config TASK_XACCT |
330 | bool "Enable extended accounting over taskstats (EXPERIMENTAL)" | |
331 | depends on TASKSTATS | |
332 | help | |
333 | Collect extended task accounting data and send the data | |
334 | to userland for processing over the taskstats interface. | |
335 | ||
336 | Say N if unsure. | |
337 | ||
338 | config TASK_IO_ACCOUNTING | |
339 | bool "Enable per-task storage I/O accounting (EXPERIMENTAL)" | |
340 | depends on TASK_XACCT | |
341 | help | |
342 | Collect information on the number of bytes of storage I/O which this | |
343 | task has caused. | |
344 | ||
345 | Say N if unsure. | |
346 | ||
1da177e4 LT |
347 | config AUDIT |
348 | bool "Auditing support" | |
804a6a49 | 349 | depends on NET |
1da177e4 LT |
350 | help |
351 | Enable auditing infrastructure that can be used with another | |
352 | kernel subsystem, such as SELinux (which requires this for | |
353 | logging of avc messages output). Does not do system-call | |
354 | auditing without CONFIG_AUDITSYSCALL. | |
355 | ||
356 | config AUDITSYSCALL | |
357 | bool "Enable system-call auditing support" | |
29ef73b7 | 358 | depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || ARM) |
1da177e4 LT |
359 | default y if SECURITY_SELINUX |
360 | help | |
361 | Enable low-overhead system-call auditing infrastructure that | |
362 | can be used independently or with another kernel subsystem, | |
67640b60 | 363 | such as SELinux. |
1da177e4 | 364 | |
939a67fc EP |
365 | config AUDIT_WATCH |
366 | def_bool y | |
367 | depends on AUDITSYSCALL | |
368 | select FSNOTIFY | |
1da177e4 | 369 | |
74c3cbe3 AV |
370 | config AUDIT_TREE |
371 | def_bool y | |
63c882a0 | 372 | depends on AUDITSYSCALL |
28a3a7eb | 373 | select FSNOTIFY |
74c3cbe3 | 374 | |
633b4545 EP |
375 | config AUDIT_LOGINUID_IMMUTABLE |
376 | bool "Make audit loginuid immutable" | |
377 | depends on AUDIT | |
378 | help | |
f429ee3b | 379 | The config option toggles if a task setting its loginuid requires |
633b4545 EP |
380 | CAP_SYS_AUDITCONTROL or if that task should require no special permissions |
381 | but should instead only allow setting its loginuid if it was never | |
382 | previously set. On systems which use systemd or a similar central | |
383 | process to restart login services this should be set to true. On older | |
384 | systems in which an admin would typically have to directly stop and | |
385 | start processes this should be set to false. Setting this to true allows | |
386 | one to drop potentially dangerous capabilites from the login tasks, | |
387 | but may not be backwards compatible with older init systems. | |
388 | ||
d9817ebe TG |
389 | source "kernel/irq/Kconfig" |
390 | ||
c903ff83 MT |
391 | menu "RCU Subsystem" |
392 | ||
393 | choice | |
394 | prompt "RCU Implementation" | |
31c9a24e | 395 | default TREE_RCU |
c903ff83 | 396 | |
c903ff83 MT |
397 | config TREE_RCU |
398 | bool "Tree-based hierarchical RCU" | |
687d7a96 | 399 | depends on !PREEMPT && SMP |
c903ff83 MT |
400 | help |
401 | This option selects the RCU implementation that is | |
402 | designed for very large SMP system with hundreds or | |
c17ef453 PM |
403 | thousands of CPUs. It also scales down nicely to |
404 | smaller systems. | |
c903ff83 | 405 | |
f41d911f | 406 | config TREE_PREEMPT_RCU |
a57eb940 | 407 | bool "Preemptible tree-based hierarchical RCU" |
8008e129 | 408 | depends on PREEMPT && SMP |
f41d911f PM |
409 | help |
410 | This option selects the RCU implementation that is | |
411 | designed for very large SMP systems with hundreds or | |
412 | thousands of CPUs, but for which real-time response | |
bbe3eae8 PM |
413 | is also required. It also scales down nicely to |
414 | smaller systems. | |
f41d911f | 415 | |
9b1d82fa PM |
416 | config TINY_RCU |
417 | bool "UP-only small-memory-footprint RCU" | |
8008e129 | 418 | depends on !PREEMPT && !SMP |
9b1d82fa PM |
419 | help |
420 | This option selects the RCU implementation that is | |
421 | designed for UP systems from which real-time response | |
422 | is not required. This option greatly reduces the | |
423 | memory footprint of RCU. | |
424 | ||
a57eb940 PM |
425 | config TINY_PREEMPT_RCU |
426 | bool "Preemptible UP-only small-memory-footprint RCU" | |
8008e129 | 427 | depends on PREEMPT && !SMP |
a57eb940 PM |
428 | help |
429 | This option selects the RCU implementation that is designed | |
430 | for real-time UP systems. This option greatly reduces the | |
431 | memory footprint of RCU. | |
432 | ||
c903ff83 MT |
433 | endchoice |
434 | ||
a57eb940 PM |
435 | config PREEMPT_RCU |
436 | def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU ) | |
437 | help | |
438 | This option enables preemptible-RCU code that is common between | |
439 | the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations. | |
440 | ||
c903ff83 MT |
441 | config RCU_FANOUT |
442 | int "Tree-based hierarchical RCU fanout value" | |
443 | range 2 64 if 64BIT | |
444 | range 2 32 if !64BIT | |
f41d911f | 445 | depends on TREE_RCU || TREE_PREEMPT_RCU |
c903ff83 MT |
446 | default 64 if 64BIT |
447 | default 32 if !64BIT | |
448 | help | |
449 | This option controls the fanout of hierarchical implementations | |
450 | of RCU, allowing RCU to work efficiently on machines with | |
4d87ffad PM |
451 | large numbers of CPUs. This value must be at least the fourth |
452 | root of NR_CPUS, which allows NR_CPUS to be insanely large. | |
453 | The default value of RCU_FANOUT should be used for production | |
454 | systems, but if you are stress-testing the RCU implementation | |
455 | itself, small RCU_FANOUT values allow you to test large-system | |
456 | code paths on small(er) systems. | |
c903ff83 MT |
457 | |
458 | Select a specific number if testing RCU itself. | |
459 | Take the default if unsure. | |
460 | ||
461 | config RCU_FANOUT_EXACT | |
462 | bool "Disable tree-based hierarchical RCU auto-balancing" | |
f41d911f | 463 | depends on TREE_RCU || TREE_PREEMPT_RCU |
c903ff83 MT |
464 | default n |
465 | help | |
466 | This option forces use of the exact RCU_FANOUT value specified, | |
467 | regardless of imbalances in the hierarchy. This is useful for | |
468 | testing RCU itself, and might one day be useful on systems with | |
469 | strong NUMA behavior. | |
470 | ||
471 | Without RCU_FANOUT_EXACT, the code will balance the hierarchy. | |
472 | ||
473 | Say N if unsure. | |
474 | ||
8bd93a2c PM |
475 | config RCU_FAST_NO_HZ |
476 | bool "Accelerate last non-dyntick-idle CPU's grace periods" | |
b807fbff | 477 | depends on NO_HZ && SMP |
8bd93a2c PM |
478 | default n |
479 | help | |
480 | This option causes RCU to attempt to accelerate grace periods | |
b807fbff PM |
481 | in order to allow CPUs to enter dynticks-idle state more |
482 | quickly. On the other hand, this option increases the overhead | |
483 | of the dynticks-idle checking, particularly on systems with | |
484 | large numbers of CPUs. | |
8bd93a2c PM |
485 | |
486 | Say Y if energy efficiency is critically important, particularly | |
487 | if you have relatively few CPUs. | |
488 | ||
489 | Say N if you are unsure. | |
490 | ||
c903ff83 | 491 | config TREE_RCU_TRACE |
f41d911f | 492 | def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU ) |
c903ff83 MT |
493 | select DEBUG_FS |
494 | help | |
f41d911f PM |
495 | This option provides tracing for the TREE_RCU and |
496 | TREE_PREEMPT_RCU implementations, permitting Makefile to | |
497 | trivially select kernel/rcutree_trace.c. | |
c903ff83 | 498 | |
24278d14 PM |
499 | config RCU_BOOST |
500 | bool "Enable RCU priority boosting" | |
27f4d280 | 501 | depends on RT_MUTEXES && PREEMPT_RCU |
24278d14 PM |
502 | default n |
503 | help | |
504 | This option boosts the priority of preempted RCU readers that | |
505 | block the current preemptible RCU grace period for too long. | |
506 | This option also prevents heavy loads from blocking RCU | |
507 | callback invocation for all flavors of RCU. | |
508 | ||
509 | Say Y here if you are working with real-time apps or heavy loads | |
510 | Say N here if you are unsure. | |
511 | ||
512 | config RCU_BOOST_PRIO | |
513 | int "Real-time priority to boost RCU readers to" | |
514 | range 1 99 | |
515 | depends on RCU_BOOST | |
516 | default 1 | |
517 | help | |
518 | This option specifies the real-time priority to which preempted | |
519 | RCU readers are to be boosted. If you are working with CPU-bound | |
520 | real-time applications, you should specify a priority higher then | |
521 | the highest-priority CPU-bound application. | |
522 | ||
523 | Specify the real-time priority, or take the default if unsure. | |
524 | ||
525 | config RCU_BOOST_DELAY | |
526 | int "Milliseconds to delay boosting after RCU grace-period start" | |
527 | range 0 3000 | |
528 | depends on RCU_BOOST | |
529 | default 500 | |
530 | help | |
531 | This option specifies the time to wait after the beginning of | |
532 | a given grace period before priority-boosting preempted RCU | |
533 | readers blocking that grace period. Note that any RCU reader | |
534 | blocking an expedited RCU grace period is boosted immediately. | |
535 | ||
536 | Accept the default if unsure. | |
537 | ||
c903ff83 MT |
538 | endmenu # "RCU Subsystem" |
539 | ||
1da177e4 | 540 | config IKCONFIG |
f2443ab6 | 541 | tristate "Kernel .config support" |
1da177e4 LT |
542 | ---help--- |
543 | This option enables the complete Linux kernel ".config" file | |
544 | contents to be saved in the kernel. It provides documentation | |
545 | of which kernel options are used in a running kernel or in an | |
546 | on-disk kernel. This information can be extracted from the kernel | |
547 | image file with the script scripts/extract-ikconfig and used as | |
548 | input to rebuild the current kernel or to build another kernel. | |
549 | It can also be extracted from a running kernel by reading | |
550 | /proc/config.gz if enabled (below). | |
551 | ||
552 | config IKCONFIG_PROC | |
553 | bool "Enable access to .config through /proc/config.gz" | |
554 | depends on IKCONFIG && PROC_FS | |
555 | ---help--- | |
556 | This option enables access to the kernel configuration file | |
557 | through /proc/config.gz. | |
558 | ||
794543a2 AJS |
559 | config LOG_BUF_SHIFT |
560 | int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" | |
561 | range 12 21 | |
f17a32e9 | 562 | default 17 |
794543a2 AJS |
563 | help |
564 | Select kernel log buffer size as a power of 2. | |
f17a32e9 AB |
565 | Examples: |
566 | 17 => 128 KB | |
567 | 16 => 64 KB | |
568 | 15 => 32 KB | |
569 | 14 => 16 KB | |
794543a2 AJS |
570 | 13 => 8 KB |
571 | 12 => 4 KB | |
572 | ||
a5574cf6 IM |
573 | # |
574 | # Architectures with an unreliable sched_clock() should select this: | |
575 | # | |
576 | config HAVE_UNSTABLE_SCHED_CLOCK | |
577 | bool | |
578 | ||
23964d2d LZ |
579 | menuconfig CGROUPS |
580 | boolean "Control Group support" | |
0dea1168 | 581 | depends on EVENTFD |
5cdc38f9 | 582 | help |
23964d2d | 583 | This option adds support for grouping sets of processes together, for |
5cdc38f9 KH |
584 | use with process control subsystems such as Cpusets, CFS, memory |
585 | controls or device isolation. | |
586 | See | |
5cdc38f9 | 587 | - Documentation/scheduler/sched-design-CFS.txt (CFS) |
45ce80fb LZ |
588 | - Documentation/cgroups/ (features for grouping, isolation |
589 | and resource control) | |
5cdc38f9 KH |
590 | |
591 | Say N if unsure. | |
592 | ||
23964d2d LZ |
593 | if CGROUPS |
594 | ||
5cdc38f9 KH |
595 | config CGROUP_DEBUG |
596 | bool "Example debug cgroup subsystem" | |
5cdc38f9 KH |
597 | default n |
598 | help | |
599 | This option enables a simple cgroup subsystem that | |
600 | exports useful debugging information about the cgroups | |
23964d2d | 601 | framework. |
5cdc38f9 | 602 | |
23964d2d | 603 | Say N if unsure. |
5cdc38f9 | 604 | |
5cdc38f9 | 605 | config CGROUP_FREEZER |
23964d2d | 606 | bool "Freezer cgroup subsystem" |
23964d2d LZ |
607 | help |
608 | Provides a way to freeze and unfreeze all tasks in a | |
5cdc38f9 KH |
609 | cgroup. |
610 | ||
611 | config CGROUP_DEVICE | |
612 | bool "Device controller for cgroups" | |
5cdc38f9 KH |
613 | help |
614 | Provides a cgroup implementing whitelists for devices which | |
615 | a process in the cgroup can mknod or open. | |
616 | ||
617 | config CPUSETS | |
618 | bool "Cpuset support" | |
5cdc38f9 KH |
619 | help |
620 | This option will let you create and manage CPUSETs which | |
621 | allow dynamically partitioning a system into sets of CPUs and | |
622 | Memory Nodes and assigning tasks to run only within those sets. | |
623 | This is primarily useful on large SMP or NUMA systems. | |
624 | ||
625 | Say N if unsure. | |
626 | ||
23964d2d LZ |
627 | config PROC_PID_CPUSET |
628 | bool "Include legacy /proc/<pid>/cpuset file" | |
629 | depends on CPUSETS | |
630 | default y | |
631 | ||
d842de87 SV |
632 | config CGROUP_CPUACCT |
633 | bool "Simple CPU accounting cgroup subsystem" | |
d842de87 SV |
634 | help |
635 | Provides a simple Resource Controller for monitoring the | |
23964d2d | 636 | total CPU consumed by the tasks in a cgroup. |
d842de87 | 637 | |
e552b661 PE |
638 | config RESOURCE_COUNTERS |
639 | bool "Resource counters" | |
640 | help | |
641 | This option enables controller independent resource accounting | |
23964d2d | 642 | infrastructure that works with cgroups. |
e552b661 | 643 | |
00f0b825 BS |
644 | config CGROUP_MEM_RES_CTLR |
645 | bool "Memory Resource Controller for Control Groups" | |
79ae9c29 | 646 | depends on RESOURCE_COUNTERS |
cf475ad2 | 647 | select MM_OWNER |
00f0b825 | 648 | help |
84ad6d70 | 649 | Provides a memory resource controller that manages both anonymous |
21acb9ca | 650 | memory and page cache. (See Documentation/cgroups/memory.txt) |
00f0b825 BS |
651 | |
652 | Note that setting this option increases fixed memory overhead | |
84ad6d70 KH |
653 | associated with each page of memory in the system. By this, |
654 | 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory | |
655 | usage tracking struct at boot. Total amount of this is printed out | |
656 | at boot. | |
00f0b825 BS |
657 | |
658 | Only enable when you're ok with these trade offs and really | |
84ad6d70 KH |
659 | sure you need the memory resource controller. Even when you enable |
660 | this, you can set "cgroup_disable=memory" at your boot option to | |
661 | disable memory resource controller and you can avoid overheads. | |
c9d5409f | 662 | (and lose benefits of memory resource controller) |
00f0b825 | 663 | |
cf475ad2 BS |
664 | This config option also selects MM_OWNER config option, which |
665 | could in turn add some fork/exit overhead. | |
666 | ||
c077719b | 667 | config CGROUP_MEM_RES_CTLR_SWAP |
65e0e811 KH |
668 | bool "Memory Resource Controller Swap Extension" |
669 | depends on CGROUP_MEM_RES_CTLR && SWAP | |
c077719b KH |
670 | help |
671 | Add swap management feature to memory resource controller. When you | |
672 | enable this, you can limit mem+swap usage per cgroup. In other words, | |
673 | when you disable this, memory resource controller has no cares to | |
674 | usage of swap...a process can exhaust all of the swap. This extension | |
675 | is useful when you want to avoid exhaustion swap but this itself | |
676 | adds more overheads and consumes memory for remembering information. | |
677 | Especially if you use 32bit system or small memory system, please | |
678 | be careful about enabling this. When memory resource controller | |
679 | is disabled by boot option, this will be automatically disabled and | |
680 | there will be no overhead from this. Even when you set this config=y, | |
00a66d29 | 681 | if boot option "swapaccount=0" is set, swap will not be accounted. |
627991a2 KH |
682 | Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page |
683 | size is 4096bytes, 512k per 1Gbytes of swap. | |
a42c390c MH |
684 | config CGROUP_MEM_RES_CTLR_SWAP_ENABLED |
685 | bool "Memory Resource Controller Swap Extension enabled by default" | |
686 | depends on CGROUP_MEM_RES_CTLR_SWAP | |
687 | default y | |
688 | help | |
689 | Memory Resource Controller Swap Extension comes with its price in | |
690 | a bigger memory consumption. General purpose distribution kernels | |
43d547f9 | 691 | which want to enable the feature but keep it disabled by default |
a42c390c MH |
692 | and let the user enable it by swapaccount boot command line |
693 | parameter should have this option unselected. | |
694 | For those who want to have the feature enabled by default should | |
695 | select this option (if, for some reason, they need to disable it | |
00a66d29 | 696 | then swapaccount=0 does the trick). |
e5671dfa GC |
697 | config CGROUP_MEM_RES_CTLR_KMEM |
698 | bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)" | |
699 | depends on CGROUP_MEM_RES_CTLR && EXPERIMENTAL | |
700 | default n | |
701 | help | |
702 | The Kernel Memory extension for Memory Resource Controller can limit | |
703 | the amount of memory used by kernel objects in the system. Those are | |
704 | fundamentally different from the entities handled by the standard | |
705 | Memory Controller, which are page-based, and can be swapped. Users of | |
706 | the kmem extension can use it to guarantee that no group of processes | |
707 | will ever exhaust kernel resources alone. | |
c077719b | 708 | |
e5d1367f SE |
709 | config CGROUP_PERF |
710 | bool "Enable perf_event per-cpu per-container group (cgroup) monitoring" | |
711 | depends on PERF_EVENTS && CGROUPS | |
712 | help | |
713 | This option extends the per-cpu mode to restrict monitoring to | |
2d0f2520 | 714 | threads which belong to the cgroup specified and run on the |
e5d1367f SE |
715 | designated cpu. |
716 | ||
717 | Say N if unsure. | |
718 | ||
7c941438 DG |
719 | menuconfig CGROUP_SCHED |
720 | bool "Group CPU scheduler" | |
7c941438 DG |
721 | default n |
722 | help | |
723 | This feature lets CPU scheduler recognize task groups and control CPU | |
724 | bandwidth allocation to such task groups. It uses cgroups to group | |
725 | tasks. | |
726 | ||
727 | if CGROUP_SCHED | |
728 | config FAIR_GROUP_SCHED | |
729 | bool "Group scheduling for SCHED_OTHER" | |
730 | depends on CGROUP_SCHED | |
731 | default CGROUP_SCHED | |
732 | ||
ab84d31e PT |
733 | config CFS_BANDWIDTH |
734 | bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" | |
735 | depends on EXPERIMENTAL | |
736 | depends on FAIR_GROUP_SCHED | |
737 | default n | |
738 | help | |
739 | This option allows users to define CPU bandwidth rates (limits) for | |
740 | tasks running within the fair group scheduler. Groups with no limit | |
741 | set are considered to be unconstrained and will run with no | |
742 | restriction. | |
743 | See tip/Documentation/scheduler/sched-bwc.txt for more information. | |
744 | ||
7c941438 DG |
745 | config RT_GROUP_SCHED |
746 | bool "Group scheduling for SCHED_RR/FIFO" | |
747 | depends on EXPERIMENTAL | |
748 | depends on CGROUP_SCHED | |
749 | default n | |
750 | help | |
751 | This feature lets you explicitly allocate real CPU bandwidth | |
32bd7eb5 | 752 | to task groups. If enabled, it will also make it impossible to |
7c941438 DG |
753 | schedule realtime tasks for non-root users until you allocate |
754 | realtime bandwidth for them. | |
755 | See Documentation/scheduler/sched-rt-group.txt for more information. | |
756 | ||
757 | endif #CGROUP_SCHED | |
758 | ||
afc24d49 VG |
759 | config BLK_CGROUP |
760 | tristate "Block IO controller" | |
79ae9c29 | 761 | depends on BLOCK |
afc24d49 VG |
762 | default n |
763 | ---help--- | |
764 | Generic block IO controller cgroup interface. This is the common | |
765 | cgroup interface which should be used by various IO controlling | |
766 | policies. | |
767 | ||
768 | Currently, CFQ IO scheduler uses it to recognize task groups and | |
769 | control disk bandwidth allocation (proportional time slice allocation) | |
e43473b7 VG |
770 | to such task groups. It is also used by bio throttling logic in |
771 | block layer to implement upper limit in IO rates on a device. | |
afc24d49 VG |
772 | |
773 | This option only enables generic Block IO controller infrastructure. | |
e43473b7 | 774 | One needs to also enable actual IO controlling logic/policy. For |
79e2e759 MW |
775 | enabling proportional weight division of disk bandwidth in CFQ, set |
776 | CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set | |
c5e0591a | 777 | CONFIG_BLK_DEV_THROTTLING=y. |
afc24d49 VG |
778 | |
779 | See Documentation/cgroups/blkio-controller.txt for more information. | |
780 | ||
781 | config DEBUG_BLK_CGROUP | |
782 | bool "Enable Block IO controller debugging" | |
783 | depends on BLK_CGROUP | |
784 | default n | |
785 | ---help--- | |
786 | Enable some debugging help. Currently it exports additional stat | |
787 | files in a cgroup which can be useful for debugging. | |
788 | ||
23964d2d | 789 | endif # CGROUPS |
c077719b | 790 | |
067bce1a CG |
791 | config CHECKPOINT_RESTORE |
792 | bool "Checkpoint/restore support" if EXPERT | |
793 | default n | |
794 | help | |
795 | Enables additional kernel features in a sake of checkpoint/restore. | |
796 | In particular it adds auxiliary prctl codes to setup process text, | |
797 | data and heap segment sizes, and a few additional /proc filesystem | |
798 | entries. | |
799 | ||
800 | If unsure, say N here. | |
801 | ||
8dd2a82c | 802 | menuconfig NAMESPACES |
6a108a14 DR |
803 | bool "Namespaces support" if EXPERT |
804 | default !EXPERT | |
c5289a69 PE |
805 | help |
806 | Provides the way to make tasks work with different objects using | |
807 | the same id. For example same IPC id may refer to different objects | |
808 | or same user id or pid may refer to different tasks when used in | |
809 | different namespaces. | |
810 | ||
8dd2a82c DL |
811 | if NAMESPACES |
812 | ||
58bfdd6d PE |
813 | config UTS_NS |
814 | bool "UTS namespace" | |
17a6d441 | 815 | default y |
58bfdd6d PE |
816 | help |
817 | In this namespace tasks see different info provided with the | |
818 | uname() system call | |
819 | ||
ae5e1b22 PE |
820 | config IPC_NS |
821 | bool "IPC namespace" | |
8dd2a82c | 822 | depends on (SYSVIPC || POSIX_MQUEUE) |
17a6d441 | 823 | default y |
ae5e1b22 PE |
824 | help |
825 | In this namespace tasks work with IPC ids which correspond to | |
614b84cf | 826 | different IPC objects in different namespaces. |
ae5e1b22 | 827 | |
aee16ce7 PE |
828 | config USER_NS |
829 | bool "User namespace (EXPERIMENTAL)" | |
8dd2a82c | 830 | depends on EXPERIMENTAL |
17a6d441 | 831 | default y |
aee16ce7 PE |
832 | help |
833 | This allows containers, i.e. vservers, to use user namespaces | |
834 | to provide different user info for different servers. | |
835 | If unsure, say N. | |
836 | ||
74bd59bb | 837 | config PID_NS |
9bd38c2c | 838 | bool "PID Namespaces" |
17a6d441 | 839 | default y |
74bd59bb | 840 | help |
12d2b8f9 | 841 | Support process id namespaces. This allows having multiple |
692105b8 | 842 | processes with the same pid as long as they are in different |
74bd59bb PE |
843 | pid namespaces. This is a building block of containers. |
844 | ||
d6eb633f MH |
845 | config NET_NS |
846 | bool "Network namespace" | |
8dd2a82c | 847 | depends on NET |
17a6d441 | 848 | default y |
d6eb633f MH |
849 | help |
850 | Allow user space to create what appear to be multiple instances | |
851 | of the network stack. | |
852 | ||
8dd2a82c DL |
853 | endif # NAMESPACES |
854 | ||
5091faa4 MG |
855 | config SCHED_AUTOGROUP |
856 | bool "Automatic process group scheduling" | |
857 | select EVENTFD | |
858 | select CGROUPS | |
859 | select CGROUP_SCHED | |
860 | select FAIR_GROUP_SCHED | |
861 | help | |
862 | This option optimizes the scheduler for common desktop workloads by | |
863 | automatically creating and populating task groups. This separation | |
864 | of workloads isolates aggressive CPU burners (like build jobs) from | |
865 | desktop applications. Task group autogeneration is currently based | |
866 | upon task session. | |
867 | ||
7af37bec DL |
868 | config MM_OWNER |
869 | bool | |
870 | ||
871 | config SYSFS_DEPRECATED | |
5d6a4ea5 | 872 | bool "Enable deprecated sysfs features to support old userspace tools" |
7af37bec DL |
873 | depends on SYSFS |
874 | default n | |
875 | help | |
876 | This option adds code that switches the layout of the "block" class | |
877 | devices, to not show up in /sys/class/block/, but only in | |
878 | /sys/block/. | |
879 | ||
880 | This switch is only active when the sysfs.deprecated=1 boot option is | |
881 | passed or the SYSFS_DEPRECATED_V2 option is set. | |
882 | ||
883 | This option allows new kernels to run on old distributions and tools, | |
884 | which might get confused by /sys/class/block/. Since 2007/2008 all | |
885 | major distributions and tools handle this just fine. | |
886 | ||
887 | Recent distributions and userspace tools after 2009/2010 depend on | |
888 | the existence of /sys/class/block/, and will not work with this | |
889 | option enabled. | |
890 | ||
891 | Only if you are using a new kernel on an old distribution, you might | |
892 | need to say Y here. | |
893 | ||
894 | config SYSFS_DEPRECATED_V2 | |
5d6a4ea5 | 895 | bool "Enable deprecated sysfs features by default" |
7af37bec DL |
896 | default n |
897 | depends on SYSFS | |
898 | depends on SYSFS_DEPRECATED | |
899 | help | |
900 | Enable deprecated sysfs by default. | |
901 | ||
902 | See the CONFIG_SYSFS_DEPRECATED option for more details about this | |
903 | option. | |
904 | ||
905 | Only if you are using a new kernel on an old distribution, you might | |
906 | need to say Y here. Even then, odds are you would not need it | |
907 | enabled, you can always pass the boot option if absolutely necessary. | |
908 | ||
909 | config RELAY | |
910 | bool "Kernel->user space relay support (formerly relayfs)" | |
911 | help | |
912 | This option enables support for relay interface support in | |
913 | certain file systems (such as debugfs). | |
914 | It is designed to provide an efficient mechanism for tools and | |
915 | facilities to relay large amounts of data from kernel space to | |
916 | user space. | |
917 | ||
918 | If unsure, say N. | |
919 | ||
f991633d DG |
920 | config BLK_DEV_INITRD |
921 | bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" | |
922 | depends on BROKEN || !FRV | |
923 | help | |
924 | The initial RAM filesystem is a ramfs which is loaded by the | |
925 | boot loader (loadlin or lilo) and that is mounted as root | |
926 | before the normal boot procedure. It is typically used to | |
927 | load modules needed to mount the "real" root file system, | |
928 | etc. See <file:Documentation/initrd.txt> for details. | |
929 | ||
930 | If RAM disk support (BLK_DEV_RAM) is also included, this | |
931 | also enables initial RAM disk (initrd) support and adds | |
932 | 15 Kbytes (more on some other architectures) to the kernel size. | |
933 | ||
934 | If unsure say Y. | |
935 | ||
c33df4ea JPS |
936 | if BLK_DEV_INITRD |
937 | ||
dbec4866 SR |
938 | source "usr/Kconfig" |
939 | ||
c33df4ea JPS |
940 | endif |
941 | ||
c45b4f1f | 942 | config CC_OPTIMIZE_FOR_SIZE |
96fffeb4 | 943 | bool "Optimize for size" |
c45b4f1f LT |
944 | help |
945 | Enabling this option will pass "-Os" instead of "-O2" to gcc | |
946 | resulting in a smaller kernel. | |
947 | ||
775a7229 | 948 | If unsure, say Y. |
c45b4f1f | 949 | |
0847062a RD |
950 | config SYSCTL |
951 | bool | |
952 | ||
b943c460 RD |
953 | config ANON_INODES |
954 | bool | |
955 | ||
6a108a14 DR |
956 | menuconfig EXPERT |
957 | bool "Configure standard kernel features (expert users)" | |
f505c553 JT |
958 | # Unhide debug options, to make the on-by-default options visible |
959 | select DEBUG_KERNEL | |
1da177e4 LT |
960 | help |
961 | This option allows certain base kernel options and settings | |
962 | to be disabled or tweaked. This is for specialized | |
963 | environments which can tolerate a "non-standard" kernel. | |
964 | Only use this if you really know what you are doing. | |
965 | ||
ae81f9e3 | 966 | config UID16 |
6a108a14 | 967 | bool "Enable 16-bit UID system calls" if EXPERT |
09337f50 | 968 | depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION) |
ae81f9e3 CE |
969 | default y |
970 | help | |
971 | This enables the legacy 16-bit UID syscall wrappers. | |
972 | ||
b89a8171 | 973 | config SYSCTL_SYSCALL |
6a108a14 | 974 | bool "Sysctl syscall support" if EXPERT |
26a7034b | 975 | depends on PROC_SYSCTL |
c736de60 | 976 | default n |
b89a8171 | 977 | select SYSCTL |
ae81f9e3 | 978 | ---help--- |
13bb7e37 EB |
979 | sys_sysctl uses binary paths that have been found challenging |
980 | to properly maintain and use. The interface in /proc/sys | |
981 | using paths with ascii names is now the primary path to this | |
982 | information. | |
b89a8171 | 983 | |
13bb7e37 EB |
984 | Almost nothing using the binary sysctl interface so if you are |
985 | trying to save some space it is probably safe to disable this, | |
986 | making your kernel marginally smaller. | |
b89a8171 | 987 | |
c736de60 | 988 | If unsure say N here. |
ae81f9e3 | 989 | |
1da177e4 | 990 | config KALLSYMS |
6a108a14 | 991 | bool "Load all symbols for debugging/ksymoops" if EXPERT |
1da177e4 LT |
992 | default y |
993 | help | |
994 | Say Y here to let the kernel print out symbolic crash information and | |
995 | symbolic stack backtraces. This increases the size of the kernel | |
996 | somewhat, as all symbols have to be loaded into the kernel image. | |
997 | ||
998 | config KALLSYMS_ALL | |
999 | bool "Include all symbols in kallsyms" | |
1000 | depends on DEBUG_KERNEL && KALLSYMS | |
1001 | help | |
71a83ec7 AB |
1002 | Normally kallsyms only contains the symbols of functions for nicer |
1003 | OOPS messages and backtraces (i.e., symbols from the text and inittext | |
1004 | sections). This is sufficient for most cases. And only in very rare | |
1005 | cases (e.g., when a debugger is used) all symbols are required (e.g., | |
1006 | names of variables from the data sections, etc). | |
1007 | ||
1008 | This option makes sure that all symbols are loaded into the kernel | |
1009 | image (i.e., symbols from all sections) in cost of increased kernel | |
1010 | size (depending on the kernel configuration, it may be 300KiB or | |
1011 | something like this). | |
1012 | ||
1013 | Say N unless you really need all symbols. | |
d59745ce | 1014 | |
712f47ce | 1015 | config HOTPLUG |
6a108a14 | 1016 | bool "Support for hot-pluggable devices" if EXPERT |
712f47ce GKH |
1017 | default y |
1018 | help | |
1019 | This option is provided for the case where no hotplug or uevent | |
1020 | capabilities is wanted by the kernel. You should only consider | |
1021 | disabling this option for embedded systems that do not use modules, a | |
1022 | dynamic /dev tree, or dynamic device discovery. Just say Y. | |
1023 | ||
d59745ce MM |
1024 | config PRINTK |
1025 | default y | |
6a108a14 | 1026 | bool "Enable support for printk" if EXPERT |
d59745ce MM |
1027 | help |
1028 | This option enables normal printk support. Removing it | |
1029 | eliminates most of the message strings from the kernel image | |
1030 | and makes the kernel more or less silent. As this makes it | |
1031 | very difficult to diagnose system problems, saying N here is | |
1032 | strongly discouraged. | |
1033 | ||
c8538a7a | 1034 | config BUG |
6a108a14 | 1035 | bool "BUG() support" if EXPERT |
c8538a7a MM |
1036 | default y |
1037 | help | |
1038 | Disabling this option eliminates support for BUG and WARN, reducing | |
1039 | the size of your kernel image and potentially quietly ignoring | |
1040 | numerous fatal conditions. You should only consider disabling this | |
1041 | option for embedded systems with no facilities for reporting errors. | |
1042 | Just say Y. | |
1043 | ||
708e9a79 MM |
1044 | config ELF_CORE |
1045 | default y | |
6a108a14 | 1046 | bool "Enable ELF core dumps" if EXPERT |
708e9a79 MM |
1047 | help |
1048 | Enable support for generating core dumps. Disabling saves about 4k. | |
1049 | ||
8761f1ab | 1050 | |
e5e1d3cb | 1051 | config PCSPKR_PLATFORM |
6a108a14 | 1052 | bool "Enable PC-Speaker support" if EXPERT |
8761f1ab | 1053 | depends on HAVE_PCSPKR_PLATFORM |
15f304b6 | 1054 | select I8253_LOCK |
e5e1d3cb SS |
1055 | default y |
1056 | help | |
1057 | This option allows to disable the internal PC-Speaker | |
1058 | support, saving some memory. | |
1059 | ||
8761f1ab RB |
1060 | config HAVE_PCSPKR_PLATFORM |
1061 | bool | |
1062 | ||
1da177e4 LT |
1063 | config BASE_FULL |
1064 | default y | |
6a108a14 | 1065 | bool "Enable full-sized data structures for core" if EXPERT |
1da177e4 LT |
1066 | help |
1067 | Disabling this option reduces the size of miscellaneous core | |
1068 | kernel data structures. This saves memory on small machines, | |
1069 | but may reduce performance. | |
1070 | ||
1071 | config FUTEX | |
6a108a14 | 1072 | bool "Enable futex support" if EXPERT |
1da177e4 | 1073 | default y |
23f78d4a | 1074 | select RT_MUTEXES |
1da177e4 LT |
1075 | help |
1076 | Disabling this option will cause the kernel to be built without | |
1077 | support for "fast userspace mutexes". The resulting kernel may not | |
1078 | run glibc-based applications correctly. | |
1079 | ||
1080 | config EPOLL | |
6a108a14 | 1081 | bool "Enable eventpoll support" if EXPERT |
1da177e4 | 1082 | default y |
448e3cee | 1083 | select ANON_INODES |
1da177e4 LT |
1084 | help |
1085 | Disabling this option will cause the kernel to be built without | |
1086 | support for epoll family of system calls. | |
1087 | ||
fba2afaa | 1088 | config SIGNALFD |
6a108a14 | 1089 | bool "Enable signalfd() system call" if EXPERT |
448e3cee | 1090 | select ANON_INODES |
fba2afaa DL |
1091 | default y |
1092 | help | |
1093 | Enable the signalfd() system call that allows to receive signals | |
1094 | on a file descriptor. | |
1095 | ||
1096 | If unsure, say Y. | |
1097 | ||
b215e283 | 1098 | config TIMERFD |
6a108a14 | 1099 | bool "Enable timerfd() system call" if EXPERT |
448e3cee | 1100 | select ANON_INODES |
b215e283 DL |
1101 | default y |
1102 | help | |
1103 | Enable the timerfd() system call that allows to receive timer | |
1104 | events on a file descriptor. | |
1105 | ||
1106 | If unsure, say Y. | |
1107 | ||
e1ad7468 | 1108 | config EVENTFD |
6a108a14 | 1109 | bool "Enable eventfd() system call" if EXPERT |
448e3cee | 1110 | select ANON_INODES |
e1ad7468 DL |
1111 | default y |
1112 | help | |
1113 | Enable the eventfd() system call that allows to receive both | |
1114 | kernel notification (ie. KAIO) or userspace notifications. | |
1115 | ||
1116 | If unsure, say Y. | |
1117 | ||
1da177e4 | 1118 | config SHMEM |
6a108a14 | 1119 | bool "Use full shmem filesystem" if EXPERT |
1da177e4 LT |
1120 | default y |
1121 | depends on MMU | |
1122 | help | |
1123 | The shmem is an internal filesystem used to manage shared memory. | |
1124 | It is backed by swap and manages resource limits. It is also exported | |
1125 | to userspace as tmpfs if TMPFS is enabled. Disabling this | |
1126 | option replaces shmem and tmpfs with the much simpler ramfs code, | |
1127 | which may be appropriate on small systems without swap. | |
1128 | ||
ebf3f09c | 1129 | config AIO |
6a108a14 | 1130 | bool "Enable AIO support" if EXPERT |
ebf3f09c TP |
1131 | default y |
1132 | help | |
1133 | This option enables POSIX asynchronous I/O which may by used | |
1134 | by some high performance threaded applications. Disabling | |
1135 | this option saves about 7k. | |
1136 | ||
6befe5f6 RD |
1137 | config EMBEDDED |
1138 | bool "Embedded system" | |
1139 | select EXPERT | |
1140 | help | |
1141 | This option should be enabled if compiling the kernel for | |
1142 | an embedded system so certain expert options are available | |
1143 | for configuration. | |
1144 | ||
cdd6c482 | 1145 | config HAVE_PERF_EVENTS |
0793a61d | 1146 | bool |
018df72d MF |
1147 | help |
1148 | See tools/perf/design.txt for details. | |
0793a61d | 1149 | |
906010b2 PZ |
1150 | config PERF_USE_VMALLOC |
1151 | bool | |
1152 | help | |
1153 | See tools/perf/design.txt for details | |
1154 | ||
57c0c15b | 1155 | menu "Kernel Performance Events And Counters" |
0793a61d | 1156 | |
cdd6c482 | 1157 | config PERF_EVENTS |
57c0c15b IM |
1158 | bool "Kernel performance events and counters" |
1159 | default y if (PROFILING || PERF_COUNTERS) | |
cdd6c482 | 1160 | depends on HAVE_PERF_EVENTS |
4c59e467 | 1161 | select ANON_INODES |
e360adbe | 1162 | select IRQ_WORK |
0793a61d | 1163 | help |
57c0c15b IM |
1164 | Enable kernel support for various performance events provided |
1165 | by software and hardware. | |
0793a61d | 1166 | |
dd77038d | 1167 | Software events are supported either built-in or via the |
57c0c15b | 1168 | use of generic tracepoints. |
0793a61d | 1169 | |
57c0c15b IM |
1170 | Most modern CPUs support performance events via performance |
1171 | counter registers. These registers count the number of certain | |
0793a61d TG |
1172 | types of hw events: such as instructions executed, cachemisses |
1173 | suffered, or branches mis-predicted - without slowing down the | |
1174 | kernel or applications. These registers can also trigger interrupts | |
1175 | when a threshold number of events have passed - and can thus be | |
1176 | used to profile the code that runs on that CPU. | |
1177 | ||
57c0c15b | 1178 | The Linux Performance Event subsystem provides an abstraction of |
dd77038d | 1179 | these software and hardware event capabilities, available via a |
57c0c15b | 1180 | system call and used by the "perf" utility in tools/perf/. It |
0793a61d TG |
1181 | provides per task and per CPU counters, and it provides event |
1182 | capabilities on top of those. | |
1183 | ||
1184 | Say Y if unsure. | |
1185 | ||
57c0c15b IM |
1186 | config PERF_COUNTERS |
1187 | bool "Kernel performance counters (old config option)" | |
1188 | depends on HAVE_PERF_EVENTS | |
1189 | help | |
1190 | This config has been obsoleted by the PERF_EVENTS | |
1191 | config option - please see that one for details. | |
1192 | ||
1193 | It has no effect on the kernel whether you enable | |
1194 | it or not, it is a compatibility placeholder. | |
1195 | ||
1196 | Say N if unsure. | |
1197 | ||
906010b2 PZ |
1198 | config DEBUG_PERF_USE_VMALLOC |
1199 | default n | |
1200 | bool "Debug: use vmalloc to back perf mmap() buffers" | |
1201 | depends on PERF_EVENTS && DEBUG_KERNEL | |
1202 | select PERF_USE_VMALLOC | |
1203 | help | |
1204 | Use vmalloc memory to back perf mmap() buffers. | |
1205 | ||
1206 | Mostly useful for debugging the vmalloc code on platforms | |
1207 | that don't require it. | |
1208 | ||
1209 | Say N if unsure. | |
1210 | ||
0793a61d TG |
1211 | endmenu |
1212 | ||
f8891e5e CL |
1213 | config VM_EVENT_COUNTERS |
1214 | default y | |
6a108a14 | 1215 | bool "Enable VM event counters for /proc/vmstat" if EXPERT |
f8891e5e | 1216 | help |
2aea4fb6 PJ |
1217 | VM event counters are needed for event counts to be shown. |
1218 | This option allows the disabling of the VM event counters | |
6a108a14 | 1219 | on EXPERT systems. /proc/vmstat will only show page counts |
2aea4fb6 | 1220 | if VM event counters are disabled. |
f8891e5e | 1221 | |
3d137310 TP |
1222 | config PCI_QUIRKS |
1223 | default y | |
6a108a14 | 1224 | bool "Enable PCI quirk workarounds" if EXPERT |
61cfc7e4 | 1225 | depends on PCI |
3d137310 TP |
1226 | help |
1227 | This enables workarounds for various PCI chipset | |
1228 | bugs/quirks. Disable this only if your target machine is | |
1229 | unaffected by PCI quirks. | |
1230 | ||
41ecc55b CL |
1231 | config SLUB_DEBUG |
1232 | default y | |
6a108a14 | 1233 | bool "Enable SLUB debugging support" if EXPERT |
f6acb635 | 1234 | depends on SLUB && SYSFS |
41ecc55b CL |
1235 | help |
1236 | SLUB has extensive debug support features. Disabling these can | |
1237 | result in significant savings in code size. This also disables | |
1238 | SLUB sysfs support. /sys/slab will not exist and there will be | |
1239 | no support for cache validation etc. | |
1240 | ||
b943c460 RD |
1241 | config COMPAT_BRK |
1242 | bool "Disable heap randomization" | |
1243 | default y | |
1244 | help | |
1245 | Randomizing heap placement makes heap exploits harder, but it | |
1246 | also breaks ancient binaries (including anything libc5 based). | |
1247 | This option changes the bootup default to heap randomization | |
692105b8 | 1248 | disabled, and can be overridden at runtime by setting |
b943c460 RD |
1249 | /proc/sys/kernel/randomize_va_space to 2. |
1250 | ||
1251 | On non-ancient distros (post-2000 ones) N is usually a safe choice. | |
1252 | ||
81819f0f CL |
1253 | choice |
1254 | prompt "Choose SLAB allocator" | |
a0acd820 | 1255 | default SLUB |
81819f0f CL |
1256 | help |
1257 | This option allows to select a slab allocator. | |
1258 | ||
1259 | config SLAB | |
1260 | bool "SLAB" | |
1261 | help | |
1262 | The regular slab allocator that is established and known to work | |
34013886 | 1263 | well in all environments. It organizes cache hot objects in |
02f56210 | 1264 | per cpu and per node queues. |
81819f0f CL |
1265 | |
1266 | config SLUB | |
81819f0f CL |
1267 | bool "SLUB (Unqueued Allocator)" |
1268 | help | |
1269 | SLUB is a slab allocator that minimizes cache line usage | |
1270 | instead of managing queues of cached objects (SLAB approach). | |
1271 | Per cpu caching is realized using slabs of objects instead | |
1272 | of queues of objects. SLUB can use memory efficiently | |
02f56210 SA |
1273 | and has enhanced diagnostics. SLUB is the default choice for |
1274 | a slab allocator. | |
81819f0f CL |
1275 | |
1276 | config SLOB | |
6a108a14 | 1277 | depends on EXPERT |
81819f0f CL |
1278 | bool "SLOB (Simple Allocator)" |
1279 | help | |
37291458 MM |
1280 | SLOB replaces the stock allocator with a drastically simpler |
1281 | allocator. SLOB is generally more space efficient but | |
1282 | does not perform as well on large systems. | |
81819f0f CL |
1283 | |
1284 | endchoice | |
1285 | ||
ea637639 JZ |
1286 | config MMAP_ALLOW_UNINITIALIZED |
1287 | bool "Allow mmapped anonymous memory to be uninitialized" | |
6a108a14 | 1288 | depends on EXPERT && !MMU |
ea637639 JZ |
1289 | default n |
1290 | help | |
1291 | Normally, and according to the Linux spec, anonymous memory obtained | |
1292 | from mmap() has it's contents cleared before it is passed to | |
1293 | userspace. Enabling this config option allows you to request that | |
1294 | mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus | |
1295 | providing a huge performance boost. If this option is not enabled, | |
1296 | then the flag will be ignored. | |
1297 | ||
1298 | This is taken advantage of by uClibc's malloc(), and also by | |
1299 | ELF-FDPIC binfmt's brk and stack allocator. | |
1300 | ||
1301 | Because of the obvious security issues, this option should only be | |
1302 | enabled on embedded devices where you control what is run in | |
1303 | userspace. Since that isn't generally a problem on no-MMU systems, | |
1304 | it is normally safe to say Y here. | |
1305 | ||
1306 | See Documentation/nommu-mmap.txt for more information. | |
1307 | ||
125e5645 | 1308 | config PROFILING |
b309a294 | 1309 | bool "Profiling support" |
125e5645 MD |
1310 | help |
1311 | Say Y here to enable the extended profiling support mechanisms used | |
1312 | by profilers such as OProfile. | |
1313 | ||
5f87f112 IM |
1314 | # |
1315 | # Place an empty function call at each tracepoint site. Can be | |
1316 | # dynamically changed for a probe function. | |
1317 | # | |
97e1c18e | 1318 | config TRACEPOINTS |
5f87f112 | 1319 | bool |
97e1c18e | 1320 | |
fb32e03f MD |
1321 | source "arch/Kconfig" |
1322 | ||
1da177e4 LT |
1323 | endmenu # General setup |
1324 | ||
ee7e5516 DB |
1325 | config HAVE_GENERIC_DMA_COHERENT |
1326 | bool | |
1327 | default n | |
1328 | ||
158a9624 LT |
1329 | config SLABINFO |
1330 | bool | |
1331 | depends on PROC_FS | |
0f389ec6 | 1332 | depends on SLAB || SLUB_DEBUG |
158a9624 LT |
1333 | default y |
1334 | ||
ae81f9e3 CE |
1335 | config RT_MUTEXES |
1336 | boolean | |
ae81f9e3 | 1337 | |
1da177e4 LT |
1338 | config BASE_SMALL |
1339 | int | |
1340 | default 0 if BASE_FULL | |
1341 | default 1 if !BASE_FULL | |
1342 | ||
66da5733 | 1343 | menuconfig MODULES |
1da177e4 LT |
1344 | bool "Enable loadable module support" |
1345 | help | |
1346 | Kernel modules are small pieces of compiled code which can | |
1347 | be inserted in the running kernel, rather than being | |
1348 | permanently built into the kernel. You use the "modprobe" | |
1349 | tool to add (and sometimes remove) them. If you say Y here, | |
1350 | many parts of the kernel can be built as modules (by | |
1351 | answering M instead of Y where indicated): this is most | |
1352 | useful for infrequently used options which are not required | |
1353 | for booting. For more information, see the man pages for | |
1354 | modprobe, lsmod, modinfo, insmod and rmmod. | |
1355 | ||
1356 | If you say Y here, you will need to run "make | |
1357 | modules_install" to put the modules under /lib/modules/ | |
1358 | where modprobe can find them (you may need to be root to do | |
1359 | this). | |
1360 | ||
1361 | If unsure, say Y. | |
1362 | ||
0b0de144 RD |
1363 | if MODULES |
1364 | ||
826e4506 LT |
1365 | config MODULE_FORCE_LOAD |
1366 | bool "Forced module loading" | |
826e4506 LT |
1367 | default n |
1368 | help | |
91e37a79 RR |
1369 | Allow loading of modules without version information (ie. modprobe |
1370 | --force). Forced module loading sets the 'F' (forced) taint flag and | |
1371 | is usually a really bad idea. | |
826e4506 | 1372 | |
1da177e4 LT |
1373 | config MODULE_UNLOAD |
1374 | bool "Module unloading" | |
1da177e4 LT |
1375 | help |
1376 | Without this option you will not be able to unload any | |
1377 | modules (note that some modules may not be unloadable | |
f7f5b675 DV |
1378 | anyway), which makes your kernel smaller, faster |
1379 | and simpler. If unsure, say Y. | |
1da177e4 LT |
1380 | |
1381 | config MODULE_FORCE_UNLOAD | |
1382 | bool "Forced module unloading" | |
1383 | depends on MODULE_UNLOAD && EXPERIMENTAL | |
1384 | help | |
1385 | This option allows you to force a module to unload, even if the | |
1386 | kernel believes it is unsafe: the kernel will remove the module | |
1387 | without waiting for anyone to stop using it (using the -f option to | |
1388 | rmmod). This is mainly for kernel developers and desperate users. | |
1389 | If unsure, say N. | |
1390 | ||
1da177e4 | 1391 | config MODVERSIONS |
0d541643 | 1392 | bool "Module versioning support" |
1da177e4 LT |
1393 | help |
1394 | Usually, you have to use modules compiled with your kernel. | |
1395 | Saying Y here makes it sometimes possible to use modules | |
1396 | compiled for different kernels, by adding enough information | |
1397 | to the modules to (hopefully) spot any changes which would | |
1398 | make them incompatible with the kernel you are running. If | |
1399 | unsure, say N. | |
1400 | ||
1401 | config MODULE_SRCVERSION_ALL | |
1402 | bool "Source checksum for all modules" | |
1da177e4 LT |
1403 | help |
1404 | Modules which contain a MODULE_VERSION get an extra "srcversion" | |
1405 | field inserted into their modinfo section, which contains a | |
1406 | sum of the source files which made it. This helps maintainers | |
1407 | see exactly which source was used to build a module (since | |
1408 | others sometimes change the module source without updating | |
1409 | the version). With this option, such a "srcversion" field | |
1410 | will be created for all modules. If unsure, say N. | |
1411 | ||
0b0de144 RD |
1412 | endif # MODULES |
1413 | ||
98a79d6a RR |
1414 | config INIT_ALL_POSSIBLE |
1415 | bool | |
1416 | help | |
5f054e31 RR |
1417 | Back when each arch used to define their own cpu_online_mask and |
1418 | cpu_possible_mask, some of them chose to initialize cpu_possible_mask | |
98a79d6a RR |
1419 | with all 1s, and others with all 0s. When they were centralised, |
1420 | it was better to provide this option than to break all the archs | |
692105b8 | 1421 | and have several arch maintainers pursuing me down dark alleys. |
98a79d6a | 1422 | |
1da177e4 LT |
1423 | config STOP_MACHINE |
1424 | bool | |
1425 | default y | |
1426 | depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU | |
1427 | help | |
1428 | Need stop_machine() primitive. | |
3a65dfe8 | 1429 | |
3a65dfe8 | 1430 | source "block/Kconfig" |
e98c3202 AK |
1431 | |
1432 | config PREEMPT_NOTIFIERS | |
1433 | bool | |
e260be67 | 1434 | |
16295bec SK |
1435 | config PADATA |
1436 | depends on SMP | |
1437 | bool | |
1438 | ||
6beb0009 | 1439 | source "kernel/Kconfig.locks" |