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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53 | drivers that have been replaced by something else, and/or are | |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_TRACE |
442 | bool "Enable tracing for RCU" | |
c903ff83 MT |
443 | help |
444 | This option provides tracing in RCU which presents stats | |
445 | in debugfs for debugging RCU implementation. | |
446 | ||
447 | Say Y here if you want to enable RCU tracing | |
448 | Say N if you are unsure. | |
449 | ||
450 | config RCU_FANOUT | |
451 | int "Tree-based hierarchical RCU fanout value" | |
452 | range 2 64 if 64BIT | |
453 | range 2 32 if !64BIT | |
f41d911f | 454 | depends on TREE_RCU || TREE_PREEMPT_RCU |
c903ff83 MT |
455 | default 64 if 64BIT |
456 | default 32 if !64BIT | |
457 | help | |
458 | This option controls the fanout of hierarchical implementations | |
459 | of RCU, allowing RCU to work efficiently on machines with | |
4d87ffad PM |
460 | large numbers of CPUs. This value must be at least the fourth |
461 | root of NR_CPUS, which allows NR_CPUS to be insanely large. | |
462 | The default value of RCU_FANOUT should be used for production | |
463 | systems, but if you are stress-testing the RCU implementation | |
464 | itself, small RCU_FANOUT values allow you to test large-system | |
465 | code paths on small(er) systems. | |
c903ff83 MT |
466 | |
467 | Select a specific number if testing RCU itself. | |
468 | Take the default if unsure. | |
469 | ||
470 | config RCU_FANOUT_EXACT | |
471 | bool "Disable tree-based hierarchical RCU auto-balancing" | |
f41d911f | 472 | depends on TREE_RCU || TREE_PREEMPT_RCU |
c903ff83 MT |
473 | default n |
474 | help | |
475 | This option forces use of the exact RCU_FANOUT value specified, | |
476 | regardless of imbalances in the hierarchy. This is useful for | |
477 | testing RCU itself, and might one day be useful on systems with | |
478 | strong NUMA behavior. | |
479 | ||
480 | Without RCU_FANOUT_EXACT, the code will balance the hierarchy. | |
481 | ||
482 | Say N if unsure. | |
483 | ||
8bd93a2c PM |
484 | config RCU_FAST_NO_HZ |
485 | bool "Accelerate last non-dyntick-idle CPU's grace periods" | |
b807fbff | 486 | depends on NO_HZ && SMP |
8bd93a2c PM |
487 | default n |
488 | help | |
489 | This option causes RCU to attempt to accelerate grace periods | |
b807fbff PM |
490 | in order to allow CPUs to enter dynticks-idle state more |
491 | quickly. On the other hand, this option increases the overhead | |
492 | of the dynticks-idle checking, particularly on systems with | |
493 | large numbers of CPUs. | |
8bd93a2c PM |
494 | |
495 | Say Y if energy efficiency is critically important, particularly | |
496 | if you have relatively few CPUs. | |
497 | ||
498 | Say N if you are unsure. | |
499 | ||
c903ff83 | 500 | config TREE_RCU_TRACE |
f41d911f | 501 | def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU ) |
c903ff83 MT |
502 | select DEBUG_FS |
503 | help | |
f41d911f PM |
504 | This option provides tracing for the TREE_RCU and |
505 | TREE_PREEMPT_RCU implementations, permitting Makefile to | |
506 | trivially select kernel/rcutree_trace.c. | |
c903ff83 | 507 | |
24278d14 PM |
508 | config RCU_BOOST |
509 | bool "Enable RCU priority boosting" | |
27f4d280 | 510 | depends on RT_MUTEXES && PREEMPT_RCU |
24278d14 PM |
511 | default n |
512 | help | |
513 | This option boosts the priority of preempted RCU readers that | |
514 | block the current preemptible RCU grace period for too long. | |
515 | This option also prevents heavy loads from blocking RCU | |
516 | callback invocation for all flavors of RCU. | |
517 | ||
518 | Say Y here if you are working with real-time apps or heavy loads | |
519 | Say N here if you are unsure. | |
520 | ||
521 | config RCU_BOOST_PRIO | |
522 | int "Real-time priority to boost RCU readers to" | |
523 | range 1 99 | |
524 | depends on RCU_BOOST | |
525 | default 1 | |
526 | help | |
527 | This option specifies the real-time priority to which preempted | |
528 | RCU readers are to be boosted. If you are working with CPU-bound | |
529 | real-time applications, you should specify a priority higher then | |
530 | the highest-priority CPU-bound application. | |
531 | ||
532 | Specify the real-time priority, or take the default if unsure. | |
533 | ||
534 | config RCU_BOOST_DELAY | |
535 | int "Milliseconds to delay boosting after RCU grace-period start" | |
536 | range 0 3000 | |
537 | depends on RCU_BOOST | |
538 | default 500 | |
539 | help | |
540 | This option specifies the time to wait after the beginning of | |
541 | a given grace period before priority-boosting preempted RCU | |
542 | readers blocking that grace period. Note that any RCU reader | |
543 | blocking an expedited RCU grace period is boosted immediately. | |
544 | ||
545 | Accept the default if unsure. | |
546 | ||
c903ff83 MT |
547 | endmenu # "RCU Subsystem" |
548 | ||
1da177e4 | 549 | config IKCONFIG |
f2443ab6 | 550 | tristate "Kernel .config support" |
1da177e4 LT |
551 | ---help--- |
552 | This option enables the complete Linux kernel ".config" file | |
553 | contents to be saved in the kernel. It provides documentation | |
554 | of which kernel options are used in a running kernel or in an | |
555 | on-disk kernel. This information can be extracted from the kernel | |
556 | image file with the script scripts/extract-ikconfig and used as | |
557 | input to rebuild the current kernel or to build another kernel. | |
558 | It can also be extracted from a running kernel by reading | |
559 | /proc/config.gz if enabled (below). | |
560 | ||
561 | config IKCONFIG_PROC | |
562 | bool "Enable access to .config through /proc/config.gz" | |
563 | depends on IKCONFIG && PROC_FS | |
564 | ---help--- | |
565 | This option enables access to the kernel configuration file | |
566 | through /proc/config.gz. | |
567 | ||
794543a2 AJS |
568 | config LOG_BUF_SHIFT |
569 | int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" | |
570 | range 12 21 | |
f17a32e9 | 571 | default 17 |
794543a2 AJS |
572 | help |
573 | Select kernel log buffer size as a power of 2. | |
f17a32e9 AB |
574 | Examples: |
575 | 17 => 128 KB | |
576 | 16 => 64 KB | |
577 | 15 => 32 KB | |
578 | 14 => 16 KB | |
794543a2 AJS |
579 | 13 => 8 KB |
580 | 12 => 4 KB | |
581 | ||
a5574cf6 IM |
582 | # |
583 | # Architectures with an unreliable sched_clock() should select this: | |
584 | # | |
585 | config HAVE_UNSTABLE_SCHED_CLOCK | |
586 | bool | |
587 | ||
23964d2d LZ |
588 | menuconfig CGROUPS |
589 | boolean "Control Group support" | |
0dea1168 | 590 | depends on EVENTFD |
5cdc38f9 | 591 | help |
23964d2d | 592 | This option adds support for grouping sets of processes together, for |
5cdc38f9 KH |
593 | use with process control subsystems such as Cpusets, CFS, memory |
594 | controls or device isolation. | |
595 | See | |
5cdc38f9 | 596 | - Documentation/scheduler/sched-design-CFS.txt (CFS) |
45ce80fb LZ |
597 | - Documentation/cgroups/ (features for grouping, isolation |
598 | and resource control) | |
5cdc38f9 KH |
599 | |
600 | Say N if unsure. | |
601 | ||
23964d2d LZ |
602 | if CGROUPS |
603 | ||
5cdc38f9 KH |
604 | config CGROUP_DEBUG |
605 | bool "Example debug cgroup subsystem" | |
5cdc38f9 KH |
606 | default n |
607 | help | |
608 | This option enables a simple cgroup subsystem that | |
609 | exports useful debugging information about the cgroups | |
23964d2d | 610 | framework. |
5cdc38f9 | 611 | |
23964d2d | 612 | Say N if unsure. |
5cdc38f9 | 613 | |
5cdc38f9 | 614 | config CGROUP_FREEZER |
23964d2d | 615 | bool "Freezer cgroup subsystem" |
23964d2d LZ |
616 | help |
617 | Provides a way to freeze and unfreeze all tasks in a | |
5cdc38f9 KH |
618 | cgroup. |
619 | ||
620 | config CGROUP_DEVICE | |
621 | bool "Device controller for cgroups" | |
5cdc38f9 KH |
622 | help |
623 | Provides a cgroup implementing whitelists for devices which | |
624 | a process in the cgroup can mknod or open. | |
625 | ||
626 | config CPUSETS | |
627 | bool "Cpuset support" | |
5cdc38f9 KH |
628 | help |
629 | This option will let you create and manage CPUSETs which | |
630 | allow dynamically partitioning a system into sets of CPUs and | |
631 | Memory Nodes and assigning tasks to run only within those sets. | |
632 | This is primarily useful on large SMP or NUMA systems. | |
633 | ||
634 | Say N if unsure. | |
635 | ||
23964d2d LZ |
636 | config PROC_PID_CPUSET |
637 | bool "Include legacy /proc/<pid>/cpuset file" | |
638 | depends on CPUSETS | |
639 | default y | |
640 | ||
d842de87 SV |
641 | config CGROUP_CPUACCT |
642 | bool "Simple CPU accounting cgroup subsystem" | |
d842de87 SV |
643 | help |
644 | Provides a simple Resource Controller for monitoring the | |
23964d2d | 645 | total CPU consumed by the tasks in a cgroup. |
d842de87 | 646 | |
e552b661 PE |
647 | config RESOURCE_COUNTERS |
648 | bool "Resource counters" | |
649 | help | |
650 | This option enables controller independent resource accounting | |
23964d2d | 651 | infrastructure that works with cgroups. |
e552b661 | 652 | |
00f0b825 BS |
653 | config CGROUP_MEM_RES_CTLR |
654 | bool "Memory Resource Controller for Control Groups" | |
79ae9c29 | 655 | depends on RESOURCE_COUNTERS |
cf475ad2 | 656 | select MM_OWNER |
00f0b825 | 657 | help |
84ad6d70 | 658 | Provides a memory resource controller that manages both anonymous |
21acb9ca | 659 | memory and page cache. (See Documentation/cgroups/memory.txt) |
00f0b825 BS |
660 | |
661 | Note that setting this option increases fixed memory overhead | |
84ad6d70 KH |
662 | associated with each page of memory in the system. By this, |
663 | 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory | |
664 | usage tracking struct at boot. Total amount of this is printed out | |
665 | at boot. | |
00f0b825 BS |
666 | |
667 | Only enable when you're ok with these trade offs and really | |
84ad6d70 KH |
668 | sure you need the memory resource controller. Even when you enable |
669 | this, you can set "cgroup_disable=memory" at your boot option to | |
670 | disable memory resource controller and you can avoid overheads. | |
c9d5409f | 671 | (and lose benefits of memory resource controller) |
00f0b825 | 672 | |
cf475ad2 BS |
673 | This config option also selects MM_OWNER config option, which |
674 | could in turn add some fork/exit overhead. | |
675 | ||
c077719b | 676 | config CGROUP_MEM_RES_CTLR_SWAP |
65e0e811 KH |
677 | bool "Memory Resource Controller Swap Extension" |
678 | depends on CGROUP_MEM_RES_CTLR && SWAP | |
c077719b KH |
679 | help |
680 | Add swap management feature to memory resource controller. When you | |
681 | enable this, you can limit mem+swap usage per cgroup. In other words, | |
682 | when you disable this, memory resource controller has no cares to | |
683 | usage of swap...a process can exhaust all of the swap. This extension | |
684 | is useful when you want to avoid exhaustion swap but this itself | |
685 | adds more overheads and consumes memory for remembering information. | |
686 | Especially if you use 32bit system or small memory system, please | |
687 | be careful about enabling this. When memory resource controller | |
688 | is disabled by boot option, this will be automatically disabled and | |
689 | there will be no overhead from this. Even when you set this config=y, | |
00a66d29 | 690 | if boot option "swapaccount=0" is set, swap will not be accounted. |
627991a2 KH |
691 | Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page |
692 | size is 4096bytes, 512k per 1Gbytes of swap. | |
a42c390c MH |
693 | config CGROUP_MEM_RES_CTLR_SWAP_ENABLED |
694 | bool "Memory Resource Controller Swap Extension enabled by default" | |
695 | depends on CGROUP_MEM_RES_CTLR_SWAP | |
696 | default y | |
697 | help | |
698 | Memory Resource Controller Swap Extension comes with its price in | |
699 | a bigger memory consumption. General purpose distribution kernels | |
43d547f9 | 700 | which want to enable the feature but keep it disabled by default |
a42c390c MH |
701 | and let the user enable it by swapaccount boot command line |
702 | parameter should have this option unselected. | |
703 | For those who want to have the feature enabled by default should | |
704 | select this option (if, for some reason, they need to disable it | |
00a66d29 | 705 | then swapaccount=0 does the trick). |
e5671dfa GC |
706 | config CGROUP_MEM_RES_CTLR_KMEM |
707 | bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)" | |
708 | depends on CGROUP_MEM_RES_CTLR && EXPERIMENTAL | |
709 | default n | |
710 | help | |
711 | The Kernel Memory extension for Memory Resource Controller can limit | |
712 | the amount of memory used by kernel objects in the system. Those are | |
713 | fundamentally different from the entities handled by the standard | |
714 | Memory Controller, which are page-based, and can be swapped. Users of | |
715 | the kmem extension can use it to guarantee that no group of processes | |
716 | will ever exhaust kernel resources alone. | |
c077719b | 717 | |
e5d1367f SE |
718 | config CGROUP_PERF |
719 | bool "Enable perf_event per-cpu per-container group (cgroup) monitoring" | |
720 | depends on PERF_EVENTS && CGROUPS | |
721 | help | |
722 | This option extends the per-cpu mode to restrict monitoring to | |
2d0f2520 | 723 | threads which belong to the cgroup specified and run on the |
e5d1367f SE |
724 | designated cpu. |
725 | ||
726 | Say N if unsure. | |
727 | ||
7c941438 DG |
728 | menuconfig CGROUP_SCHED |
729 | bool "Group CPU scheduler" | |
7c941438 DG |
730 | default n |
731 | help | |
732 | This feature lets CPU scheduler recognize task groups and control CPU | |
733 | bandwidth allocation to such task groups. It uses cgroups to group | |
734 | tasks. | |
735 | ||
736 | if CGROUP_SCHED | |
737 | config FAIR_GROUP_SCHED | |
738 | bool "Group scheduling for SCHED_OTHER" | |
739 | depends on CGROUP_SCHED | |
740 | default CGROUP_SCHED | |
741 | ||
ab84d31e PT |
742 | config CFS_BANDWIDTH |
743 | bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" | |
744 | depends on EXPERIMENTAL | |
745 | depends on FAIR_GROUP_SCHED | |
746 | default n | |
747 | help | |
748 | This option allows users to define CPU bandwidth rates (limits) for | |
749 | tasks running within the fair group scheduler. Groups with no limit | |
750 | set are considered to be unconstrained and will run with no | |
751 | restriction. | |
752 | See tip/Documentation/scheduler/sched-bwc.txt for more information. | |
753 | ||
7c941438 DG |
754 | config RT_GROUP_SCHED |
755 | bool "Group scheduling for SCHED_RR/FIFO" | |
756 | depends on EXPERIMENTAL | |
757 | depends on CGROUP_SCHED | |
758 | default n | |
759 | help | |
760 | This feature lets you explicitly allocate real CPU bandwidth | |
32bd7eb5 | 761 | to task groups. If enabled, it will also make it impossible to |
7c941438 DG |
762 | schedule realtime tasks for non-root users until you allocate |
763 | realtime bandwidth for them. | |
764 | See Documentation/scheduler/sched-rt-group.txt for more information. | |
765 | ||
766 | endif #CGROUP_SCHED | |
767 | ||
afc24d49 VG |
768 | config BLK_CGROUP |
769 | tristate "Block IO controller" | |
79ae9c29 | 770 | depends on BLOCK |
afc24d49 VG |
771 | default n |
772 | ---help--- | |
773 | Generic block IO controller cgroup interface. This is the common | |
774 | cgroup interface which should be used by various IO controlling | |
775 | policies. | |
776 | ||
777 | Currently, CFQ IO scheduler uses it to recognize task groups and | |
778 | control disk bandwidth allocation (proportional time slice allocation) | |
e43473b7 VG |
779 | to such task groups. It is also used by bio throttling logic in |
780 | block layer to implement upper limit in IO rates on a device. | |
afc24d49 VG |
781 | |
782 | This option only enables generic Block IO controller infrastructure. | |
e43473b7 | 783 | One needs to also enable actual IO controlling logic/policy. For |
79e2e759 MW |
784 | enabling proportional weight division of disk bandwidth in CFQ, set |
785 | CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set | |
c5e0591a | 786 | CONFIG_BLK_DEV_THROTTLING=y. |
afc24d49 VG |
787 | |
788 | See Documentation/cgroups/blkio-controller.txt for more information. | |
789 | ||
790 | config DEBUG_BLK_CGROUP | |
791 | bool "Enable Block IO controller debugging" | |
792 | depends on BLK_CGROUP | |
793 | default n | |
794 | ---help--- | |
795 | Enable some debugging help. Currently it exports additional stat | |
796 | files in a cgroup which can be useful for debugging. | |
797 | ||
23964d2d | 798 | endif # CGROUPS |
c077719b | 799 | |
067bce1a CG |
800 | config CHECKPOINT_RESTORE |
801 | bool "Checkpoint/restore support" if EXPERT | |
802 | default n | |
803 | help | |
804 | Enables additional kernel features in a sake of checkpoint/restore. | |
805 | In particular it adds auxiliary prctl codes to setup process text, | |
806 | data and heap segment sizes, and a few additional /proc filesystem | |
807 | entries. | |
808 | ||
809 | If unsure, say N here. | |
810 | ||
8dd2a82c | 811 | menuconfig NAMESPACES |
6a108a14 DR |
812 | bool "Namespaces support" if EXPERT |
813 | default !EXPERT | |
c5289a69 PE |
814 | help |
815 | Provides the way to make tasks work with different objects using | |
816 | the same id. For example same IPC id may refer to different objects | |
817 | or same user id or pid may refer to different tasks when used in | |
818 | different namespaces. | |
819 | ||
8dd2a82c DL |
820 | if NAMESPACES |
821 | ||
58bfdd6d PE |
822 | config UTS_NS |
823 | bool "UTS namespace" | |
17a6d441 | 824 | default y |
58bfdd6d PE |
825 | help |
826 | In this namespace tasks see different info provided with the | |
827 | uname() system call | |
828 | ||
ae5e1b22 PE |
829 | config IPC_NS |
830 | bool "IPC namespace" | |
8dd2a82c | 831 | depends on (SYSVIPC || POSIX_MQUEUE) |
17a6d441 | 832 | default y |
ae5e1b22 PE |
833 | help |
834 | In this namespace tasks work with IPC ids which correspond to | |
614b84cf | 835 | different IPC objects in different namespaces. |
ae5e1b22 | 836 | |
aee16ce7 PE |
837 | config USER_NS |
838 | bool "User namespace (EXPERIMENTAL)" | |
8dd2a82c | 839 | depends on EXPERIMENTAL |
17a6d441 | 840 | default y |
aee16ce7 PE |
841 | help |
842 | This allows containers, i.e. vservers, to use user namespaces | |
843 | to provide different user info for different servers. | |
844 | If unsure, say N. | |
845 | ||
74bd59bb | 846 | config PID_NS |
9bd38c2c | 847 | bool "PID Namespaces" |
17a6d441 | 848 | default y |
74bd59bb | 849 | help |
12d2b8f9 | 850 | Support process id namespaces. This allows having multiple |
692105b8 | 851 | processes with the same pid as long as they are in different |
74bd59bb PE |
852 | pid namespaces. This is a building block of containers. |
853 | ||
d6eb633f MH |
854 | config NET_NS |
855 | bool "Network namespace" | |
8dd2a82c | 856 | depends on NET |
17a6d441 | 857 | default y |
d6eb633f MH |
858 | help |
859 | Allow user space to create what appear to be multiple instances | |
860 | of the network stack. | |
861 | ||
8dd2a82c DL |
862 | endif # NAMESPACES |
863 | ||
5091faa4 MG |
864 | config SCHED_AUTOGROUP |
865 | bool "Automatic process group scheduling" | |
866 | select EVENTFD | |
867 | select CGROUPS | |
868 | select CGROUP_SCHED | |
869 | select FAIR_GROUP_SCHED | |
870 | help | |
871 | This option optimizes the scheduler for common desktop workloads by | |
872 | automatically creating and populating task groups. This separation | |
873 | of workloads isolates aggressive CPU burners (like build jobs) from | |
874 | desktop applications. Task group autogeneration is currently based | |
875 | upon task session. | |
876 | ||
7af37bec DL |
877 | config MM_OWNER |
878 | bool | |
879 | ||
880 | config SYSFS_DEPRECATED | |
5d6a4ea5 | 881 | bool "Enable deprecated sysfs features to support old userspace tools" |
7af37bec DL |
882 | depends on SYSFS |
883 | default n | |
884 | help | |
885 | This option adds code that switches the layout of the "block" class | |
886 | devices, to not show up in /sys/class/block/, but only in | |
887 | /sys/block/. | |
888 | ||
889 | This switch is only active when the sysfs.deprecated=1 boot option is | |
890 | passed or the SYSFS_DEPRECATED_V2 option is set. | |
891 | ||
892 | This option allows new kernels to run on old distributions and tools, | |
893 | which might get confused by /sys/class/block/. Since 2007/2008 all | |
894 | major distributions and tools handle this just fine. | |
895 | ||
896 | Recent distributions and userspace tools after 2009/2010 depend on | |
897 | the existence of /sys/class/block/, and will not work with this | |
898 | option enabled. | |
899 | ||
900 | Only if you are using a new kernel on an old distribution, you might | |
901 | need to say Y here. | |
902 | ||
903 | config SYSFS_DEPRECATED_V2 | |
5d6a4ea5 | 904 | bool "Enable deprecated sysfs features by default" |
7af37bec DL |
905 | default n |
906 | depends on SYSFS | |
907 | depends on SYSFS_DEPRECATED | |
908 | help | |
909 | Enable deprecated sysfs by default. | |
910 | ||
911 | See the CONFIG_SYSFS_DEPRECATED option for more details about this | |
912 | option. | |
913 | ||
914 | Only if you are using a new kernel on an old distribution, you might | |
915 | need to say Y here. Even then, odds are you would not need it | |
916 | enabled, you can always pass the boot option if absolutely necessary. | |
917 | ||
918 | config RELAY | |
919 | bool "Kernel->user space relay support (formerly relayfs)" | |
920 | help | |
921 | This option enables support for relay interface support in | |
922 | certain file systems (such as debugfs). | |
923 | It is designed to provide an efficient mechanism for tools and | |
924 | facilities to relay large amounts of data from kernel space to | |
925 | user space. | |
926 | ||
927 | If unsure, say N. | |
928 | ||
f991633d DG |
929 | config BLK_DEV_INITRD |
930 | bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" | |
931 | depends on BROKEN || !FRV | |
932 | help | |
933 | The initial RAM filesystem is a ramfs which is loaded by the | |
934 | boot loader (loadlin or lilo) and that is mounted as root | |
935 | before the normal boot procedure. It is typically used to | |
936 | load modules needed to mount the "real" root file system, | |
937 | etc. See <file:Documentation/initrd.txt> for details. | |
938 | ||
939 | If RAM disk support (BLK_DEV_RAM) is also included, this | |
940 | also enables initial RAM disk (initrd) support and adds | |
941 | 15 Kbytes (more on some other architectures) to the kernel size. | |
942 | ||
943 | If unsure say Y. | |
944 | ||
c33df4ea JPS |
945 | if BLK_DEV_INITRD |
946 | ||
dbec4866 SR |
947 | source "usr/Kconfig" |
948 | ||
c33df4ea JPS |
949 | endif |
950 | ||
c45b4f1f | 951 | config CC_OPTIMIZE_FOR_SIZE |
96fffeb4 | 952 | bool "Optimize for size" |
c45b4f1f LT |
953 | help |
954 | Enabling this option will pass "-Os" instead of "-O2" to gcc | |
955 | resulting in a smaller kernel. | |
956 | ||
775a7229 | 957 | If unsure, say Y. |
c45b4f1f | 958 | |
0847062a RD |
959 | config SYSCTL |
960 | bool | |
961 | ||
b943c460 RD |
962 | config ANON_INODES |
963 | bool | |
964 | ||
6a108a14 DR |
965 | menuconfig EXPERT |
966 | bool "Configure standard kernel features (expert users)" | |
f505c553 JT |
967 | # Unhide debug options, to make the on-by-default options visible |
968 | select DEBUG_KERNEL | |
1da177e4 LT |
969 | help |
970 | This option allows certain base kernel options and settings | |
971 | to be disabled or tweaked. This is for specialized | |
972 | environments which can tolerate a "non-standard" kernel. | |
973 | Only use this if you really know what you are doing. | |
974 | ||
ae81f9e3 | 975 | config UID16 |
6a108a14 | 976 | bool "Enable 16-bit UID system calls" if EXPERT |
09337f50 | 977 | depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION) |
ae81f9e3 CE |
978 | default y |
979 | help | |
980 | This enables the legacy 16-bit UID syscall wrappers. | |
981 | ||
b89a8171 | 982 | config SYSCTL_SYSCALL |
6a108a14 | 983 | bool "Sysctl syscall support" if EXPERT |
26a7034b | 984 | depends on PROC_SYSCTL |
c736de60 | 985 | default n |
b89a8171 | 986 | select SYSCTL |
ae81f9e3 | 987 | ---help--- |
13bb7e37 EB |
988 | sys_sysctl uses binary paths that have been found challenging |
989 | to properly maintain and use. The interface in /proc/sys | |
990 | using paths with ascii names is now the primary path to this | |
991 | information. | |
b89a8171 | 992 | |
13bb7e37 EB |
993 | Almost nothing using the binary sysctl interface so if you are |
994 | trying to save some space it is probably safe to disable this, | |
995 | making your kernel marginally smaller. | |
b89a8171 | 996 | |
c736de60 | 997 | If unsure say N here. |
ae81f9e3 | 998 | |
1da177e4 | 999 | config KALLSYMS |
6a108a14 | 1000 | bool "Load all symbols for debugging/ksymoops" if EXPERT |
1da177e4 LT |
1001 | default y |
1002 | help | |
1003 | Say Y here to let the kernel print out symbolic crash information and | |
1004 | symbolic stack backtraces. This increases the size of the kernel | |
1005 | somewhat, as all symbols have to be loaded into the kernel image. | |
1006 | ||
1007 | config KALLSYMS_ALL | |
1008 | bool "Include all symbols in kallsyms" | |
1009 | depends on DEBUG_KERNEL && KALLSYMS | |
1010 | help | |
71a83ec7 AB |
1011 | Normally kallsyms only contains the symbols of functions for nicer |
1012 | OOPS messages and backtraces (i.e., symbols from the text and inittext | |
1013 | sections). This is sufficient for most cases. And only in very rare | |
1014 | cases (e.g., when a debugger is used) all symbols are required (e.g., | |
1015 | names of variables from the data sections, etc). | |
1016 | ||
1017 | This option makes sure that all symbols are loaded into the kernel | |
1018 | image (i.e., symbols from all sections) in cost of increased kernel | |
1019 | size (depending on the kernel configuration, it may be 300KiB or | |
1020 | something like this). | |
1021 | ||
1022 | Say N unless you really need all symbols. | |
d59745ce | 1023 | |
712f47ce | 1024 | config HOTPLUG |
6a108a14 | 1025 | bool "Support for hot-pluggable devices" if EXPERT |
712f47ce GKH |
1026 | default y |
1027 | help | |
1028 | This option is provided for the case where no hotplug or uevent | |
1029 | capabilities is wanted by the kernel. You should only consider | |
1030 | disabling this option for embedded systems that do not use modules, a | |
1031 | dynamic /dev tree, or dynamic device discovery. Just say Y. | |
1032 | ||
d59745ce MM |
1033 | config PRINTK |
1034 | default y | |
6a108a14 | 1035 | bool "Enable support for printk" if EXPERT |
d59745ce MM |
1036 | help |
1037 | This option enables normal printk support. Removing it | |
1038 | eliminates most of the message strings from the kernel image | |
1039 | and makes the kernel more or less silent. As this makes it | |
1040 | very difficult to diagnose system problems, saying N here is | |
1041 | strongly discouraged. | |
1042 | ||
c8538a7a | 1043 | config BUG |
6a108a14 | 1044 | bool "BUG() support" if EXPERT |
c8538a7a MM |
1045 | default y |
1046 | help | |
1047 | Disabling this option eliminates support for BUG and WARN, reducing | |
1048 | the size of your kernel image and potentially quietly ignoring | |
1049 | numerous fatal conditions. You should only consider disabling this | |
1050 | option for embedded systems with no facilities for reporting errors. | |
1051 | Just say Y. | |
1052 | ||
708e9a79 MM |
1053 | config ELF_CORE |
1054 | default y | |
6a108a14 | 1055 | bool "Enable ELF core dumps" if EXPERT |
708e9a79 MM |
1056 | help |
1057 | Enable support for generating core dumps. Disabling saves about 4k. | |
1058 | ||
8761f1ab | 1059 | |
e5e1d3cb | 1060 | config PCSPKR_PLATFORM |
6a108a14 | 1061 | bool "Enable PC-Speaker support" if EXPERT |
8761f1ab | 1062 | depends on HAVE_PCSPKR_PLATFORM |
15f304b6 | 1063 | select I8253_LOCK |
e5e1d3cb SS |
1064 | default y |
1065 | help | |
1066 | This option allows to disable the internal PC-Speaker | |
1067 | support, saving some memory. | |
1068 | ||
8761f1ab RB |
1069 | config HAVE_PCSPKR_PLATFORM |
1070 | bool | |
1071 | ||
1da177e4 LT |
1072 | config BASE_FULL |
1073 | default y | |
6a108a14 | 1074 | bool "Enable full-sized data structures for core" if EXPERT |
1da177e4 LT |
1075 | help |
1076 | Disabling this option reduces the size of miscellaneous core | |
1077 | kernel data structures. This saves memory on small machines, | |
1078 | but may reduce performance. | |
1079 | ||
1080 | config FUTEX | |
6a108a14 | 1081 | bool "Enable futex support" if EXPERT |
1da177e4 | 1082 | default y |
23f78d4a | 1083 | select RT_MUTEXES |
1da177e4 LT |
1084 | help |
1085 | Disabling this option will cause the kernel to be built without | |
1086 | support for "fast userspace mutexes". The resulting kernel may not | |
1087 | run glibc-based applications correctly. | |
1088 | ||
1089 | config EPOLL | |
6a108a14 | 1090 | bool "Enable eventpoll support" if EXPERT |
1da177e4 | 1091 | default y |
448e3cee | 1092 | select ANON_INODES |
1da177e4 LT |
1093 | help |
1094 | Disabling this option will cause the kernel to be built without | |
1095 | support for epoll family of system calls. | |
1096 | ||
fba2afaa | 1097 | config SIGNALFD |
6a108a14 | 1098 | bool "Enable signalfd() system call" if EXPERT |
448e3cee | 1099 | select ANON_INODES |
fba2afaa DL |
1100 | default y |
1101 | help | |
1102 | Enable the signalfd() system call that allows to receive signals | |
1103 | on a file descriptor. | |
1104 | ||
1105 | If unsure, say Y. | |
1106 | ||
b215e283 | 1107 | config TIMERFD |
6a108a14 | 1108 | bool "Enable timerfd() system call" if EXPERT |
448e3cee | 1109 | select ANON_INODES |
b215e283 DL |
1110 | default y |
1111 | help | |
1112 | Enable the timerfd() system call that allows to receive timer | |
1113 | events on a file descriptor. | |
1114 | ||
1115 | If unsure, say Y. | |
1116 | ||
e1ad7468 | 1117 | config EVENTFD |
6a108a14 | 1118 | bool "Enable eventfd() system call" if EXPERT |
448e3cee | 1119 | select ANON_INODES |
e1ad7468 DL |
1120 | default y |
1121 | help | |
1122 | Enable the eventfd() system call that allows to receive both | |
1123 | kernel notification (ie. KAIO) or userspace notifications. | |
1124 | ||
1125 | If unsure, say Y. | |
1126 | ||
1da177e4 | 1127 | config SHMEM |
6a108a14 | 1128 | bool "Use full shmem filesystem" if EXPERT |
1da177e4 LT |
1129 | default y |
1130 | depends on MMU | |
1131 | help | |
1132 | The shmem is an internal filesystem used to manage shared memory. | |
1133 | It is backed by swap and manages resource limits. It is also exported | |
1134 | to userspace as tmpfs if TMPFS is enabled. Disabling this | |
1135 | option replaces shmem and tmpfs with the much simpler ramfs code, | |
1136 | which may be appropriate on small systems without swap. | |
1137 | ||
ebf3f09c | 1138 | config AIO |
6a108a14 | 1139 | bool "Enable AIO support" if EXPERT |
ebf3f09c TP |
1140 | default y |
1141 | help | |
1142 | This option enables POSIX asynchronous I/O which may by used | |
1143 | by some high performance threaded applications. Disabling | |
1144 | this option saves about 7k. | |
1145 | ||
6befe5f6 RD |
1146 | config EMBEDDED |
1147 | bool "Embedded system" | |
1148 | select EXPERT | |
1149 | help | |
1150 | This option should be enabled if compiling the kernel for | |
1151 | an embedded system so certain expert options are available | |
1152 | for configuration. | |
1153 | ||
cdd6c482 | 1154 | config HAVE_PERF_EVENTS |
0793a61d | 1155 | bool |
018df72d MF |
1156 | help |
1157 | See tools/perf/design.txt for details. | |
0793a61d | 1158 | |
906010b2 PZ |
1159 | config PERF_USE_VMALLOC |
1160 | bool | |
1161 | help | |
1162 | See tools/perf/design.txt for details | |
1163 | ||
57c0c15b | 1164 | menu "Kernel Performance Events And Counters" |
0793a61d | 1165 | |
cdd6c482 | 1166 | config PERF_EVENTS |
57c0c15b IM |
1167 | bool "Kernel performance events and counters" |
1168 | default y if (PROFILING || PERF_COUNTERS) | |
cdd6c482 | 1169 | depends on HAVE_PERF_EVENTS |
4c59e467 | 1170 | select ANON_INODES |
e360adbe | 1171 | select IRQ_WORK |
0793a61d | 1172 | help |
57c0c15b IM |
1173 | Enable kernel support for various performance events provided |
1174 | by software and hardware. | |
0793a61d | 1175 | |
dd77038d | 1176 | Software events are supported either built-in or via the |
57c0c15b | 1177 | use of generic tracepoints. |
0793a61d | 1178 | |
57c0c15b IM |
1179 | Most modern CPUs support performance events via performance |
1180 | counter registers. These registers count the number of certain | |
0793a61d TG |
1181 | types of hw events: such as instructions executed, cachemisses |
1182 | suffered, or branches mis-predicted - without slowing down the | |
1183 | kernel or applications. These registers can also trigger interrupts | |
1184 | when a threshold number of events have passed - and can thus be | |
1185 | used to profile the code that runs on that CPU. | |
1186 | ||
57c0c15b | 1187 | The Linux Performance Event subsystem provides an abstraction of |
dd77038d | 1188 | these software and hardware event capabilities, available via a |
57c0c15b | 1189 | system call and used by the "perf" utility in tools/perf/. It |
0793a61d TG |
1190 | provides per task and per CPU counters, and it provides event |
1191 | capabilities on top of those. | |
1192 | ||
1193 | Say Y if unsure. | |
1194 | ||
57c0c15b IM |
1195 | config PERF_COUNTERS |
1196 | bool "Kernel performance counters (old config option)" | |
1197 | depends on HAVE_PERF_EVENTS | |
1198 | help | |
1199 | This config has been obsoleted by the PERF_EVENTS | |
1200 | config option - please see that one for details. | |
1201 | ||
1202 | It has no effect on the kernel whether you enable | |
1203 | it or not, it is a compatibility placeholder. | |
1204 | ||
1205 | Say N if unsure. | |
1206 | ||
906010b2 PZ |
1207 | config DEBUG_PERF_USE_VMALLOC |
1208 | default n | |
1209 | bool "Debug: use vmalloc to back perf mmap() buffers" | |
1210 | depends on PERF_EVENTS && DEBUG_KERNEL | |
1211 | select PERF_USE_VMALLOC | |
1212 | help | |
1213 | Use vmalloc memory to back perf mmap() buffers. | |
1214 | ||
1215 | Mostly useful for debugging the vmalloc code on platforms | |
1216 | that don't require it. | |
1217 | ||
1218 | Say N if unsure. | |
1219 | ||
0793a61d TG |
1220 | endmenu |
1221 | ||
f8891e5e CL |
1222 | config VM_EVENT_COUNTERS |
1223 | default y | |
6a108a14 | 1224 | bool "Enable VM event counters for /proc/vmstat" if EXPERT |
f8891e5e | 1225 | help |
2aea4fb6 PJ |
1226 | VM event counters are needed for event counts to be shown. |
1227 | This option allows the disabling of the VM event counters | |
6a108a14 | 1228 | on EXPERT systems. /proc/vmstat will only show page counts |
2aea4fb6 | 1229 | if VM event counters are disabled. |
f8891e5e | 1230 | |
3d137310 TP |
1231 | config PCI_QUIRKS |
1232 | default y | |
6a108a14 | 1233 | bool "Enable PCI quirk workarounds" if EXPERT |
61cfc7e4 | 1234 | depends on PCI |
3d137310 TP |
1235 | help |
1236 | This enables workarounds for various PCI chipset | |
1237 | bugs/quirks. Disable this only if your target machine is | |
1238 | unaffected by PCI quirks. | |
1239 | ||
41ecc55b CL |
1240 | config SLUB_DEBUG |
1241 | default y | |
6a108a14 | 1242 | bool "Enable SLUB debugging support" if EXPERT |
f6acb635 | 1243 | depends on SLUB && SYSFS |
41ecc55b CL |
1244 | help |
1245 | SLUB has extensive debug support features. Disabling these can | |
1246 | result in significant savings in code size. This also disables | |
1247 | SLUB sysfs support. /sys/slab will not exist and there will be | |
1248 | no support for cache validation etc. | |
1249 | ||
b943c460 RD |
1250 | config COMPAT_BRK |
1251 | bool "Disable heap randomization" | |
1252 | default y | |
1253 | help | |
1254 | Randomizing heap placement makes heap exploits harder, but it | |
1255 | also breaks ancient binaries (including anything libc5 based). | |
1256 | This option changes the bootup default to heap randomization | |
692105b8 | 1257 | disabled, and can be overridden at runtime by setting |
b943c460 RD |
1258 | /proc/sys/kernel/randomize_va_space to 2. |
1259 | ||
1260 | On non-ancient distros (post-2000 ones) N is usually a safe choice. | |
1261 | ||
81819f0f CL |
1262 | choice |
1263 | prompt "Choose SLAB allocator" | |
a0acd820 | 1264 | default SLUB |
81819f0f CL |
1265 | help |
1266 | This option allows to select a slab allocator. | |
1267 | ||
1268 | config SLAB | |
1269 | bool "SLAB" | |
1270 | help | |
1271 | The regular slab allocator that is established and known to work | |
34013886 | 1272 | well in all environments. It organizes cache hot objects in |
02f56210 | 1273 | per cpu and per node queues. |
81819f0f CL |
1274 | |
1275 | config SLUB | |
81819f0f CL |
1276 | bool "SLUB (Unqueued Allocator)" |
1277 | help | |
1278 | SLUB is a slab allocator that minimizes cache line usage | |
1279 | instead of managing queues of cached objects (SLAB approach). | |
1280 | Per cpu caching is realized using slabs of objects instead | |
1281 | of queues of objects. SLUB can use memory efficiently | |
02f56210 SA |
1282 | and has enhanced diagnostics. SLUB is the default choice for |
1283 | a slab allocator. | |
81819f0f CL |
1284 | |
1285 | config SLOB | |
6a108a14 | 1286 | depends on EXPERT |
81819f0f CL |
1287 | bool "SLOB (Simple Allocator)" |
1288 | help | |
37291458 MM |
1289 | SLOB replaces the stock allocator with a drastically simpler |
1290 | allocator. SLOB is generally more space efficient but | |
1291 | does not perform as well on large systems. | |
81819f0f CL |
1292 | |
1293 | endchoice | |
1294 | ||
ea637639 JZ |
1295 | config MMAP_ALLOW_UNINITIALIZED |
1296 | bool "Allow mmapped anonymous memory to be uninitialized" | |
6a108a14 | 1297 | depends on EXPERT && !MMU |
ea637639 JZ |
1298 | default n |
1299 | help | |
1300 | Normally, and according to the Linux spec, anonymous memory obtained | |
1301 | from mmap() has it's contents cleared before it is passed to | |
1302 | userspace. Enabling this config option allows you to request that | |
1303 | mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus | |
1304 | providing a huge performance boost. If this option is not enabled, | |
1305 | then the flag will be ignored. | |
1306 | ||
1307 | This is taken advantage of by uClibc's malloc(), and also by | |
1308 | ELF-FDPIC binfmt's brk and stack allocator. | |
1309 | ||
1310 | Because of the obvious security issues, this option should only be | |
1311 | enabled on embedded devices where you control what is run in | |
1312 | userspace. Since that isn't generally a problem on no-MMU systems, | |
1313 | it is normally safe to say Y here. | |
1314 | ||
1315 | See Documentation/nommu-mmap.txt for more information. | |
1316 | ||
125e5645 | 1317 | config PROFILING |
b309a294 | 1318 | bool "Profiling support" |
125e5645 MD |
1319 | help |
1320 | Say Y here to enable the extended profiling support mechanisms used | |
1321 | by profilers such as OProfile. | |
1322 | ||
5f87f112 IM |
1323 | # |
1324 | # Place an empty function call at each tracepoint site. Can be | |
1325 | # dynamically changed for a probe function. | |
1326 | # | |
97e1c18e | 1327 | config TRACEPOINTS |
5f87f112 | 1328 | bool |
97e1c18e | 1329 | |
fb32e03f MD |
1330 | source "arch/Kconfig" |
1331 | ||
1da177e4 LT |
1332 | endmenu # General setup |
1333 | ||
ee7e5516 DES |
1334 | config HAVE_GENERIC_DMA_COHERENT |
1335 | bool | |
1336 | default n | |
1337 | ||
158a9624 LT |
1338 | config SLABINFO |
1339 | bool | |
1340 | depends on PROC_FS | |
0f389ec6 | 1341 | depends on SLAB || SLUB_DEBUG |
158a9624 LT |
1342 | default y |
1343 | ||
ae81f9e3 CE |
1344 | config RT_MUTEXES |
1345 | boolean | |
ae81f9e3 | 1346 | |
1da177e4 LT |
1347 | config BASE_SMALL |
1348 | int | |
1349 | default 0 if BASE_FULL | |
1350 | default 1 if !BASE_FULL | |
1351 | ||
66da5733 | 1352 | menuconfig MODULES |
1da177e4 LT |
1353 | bool "Enable loadable module support" |
1354 | help | |
1355 | Kernel modules are small pieces of compiled code which can | |
1356 | be inserted in the running kernel, rather than being | |
1357 | permanently built into the kernel. You use the "modprobe" | |
1358 | tool to add (and sometimes remove) them. If you say Y here, | |
1359 | many parts of the kernel can be built as modules (by | |
1360 | answering M instead of Y where indicated): this is most | |
1361 | useful for infrequently used options which are not required | |
1362 | for booting. For more information, see the man pages for | |
1363 | modprobe, lsmod, modinfo, insmod and rmmod. | |
1364 | ||
1365 | If you say Y here, you will need to run "make | |
1366 | modules_install" to put the modules under /lib/modules/ | |
1367 | where modprobe can find them (you may need to be root to do | |
1368 | this). | |
1369 | ||
1370 | If unsure, say Y. | |
1371 | ||
0b0de144 RD |
1372 | if MODULES |
1373 | ||
826e4506 LT |
1374 | config MODULE_FORCE_LOAD |
1375 | bool "Forced module loading" | |
826e4506 LT |
1376 | default n |
1377 | help | |
91e37a79 RR |
1378 | Allow loading of modules without version information (ie. modprobe |
1379 | --force). Forced module loading sets the 'F' (forced) taint flag and | |
1380 | is usually a really bad idea. | |
826e4506 | 1381 | |
1da177e4 LT |
1382 | config MODULE_UNLOAD |
1383 | bool "Module unloading" | |
1da177e4 LT |
1384 | help |
1385 | Without this option you will not be able to unload any | |
1386 | modules (note that some modules may not be unloadable | |
f7f5b675 DV |
1387 | anyway), which makes your kernel smaller, faster |
1388 | and simpler. If unsure, say Y. | |
1da177e4 LT |
1389 | |
1390 | config MODULE_FORCE_UNLOAD | |
1391 | bool "Forced module unloading" | |
1392 | depends on MODULE_UNLOAD && EXPERIMENTAL | |
1393 | help | |
1394 | This option allows you to force a module to unload, even if the | |
1395 | kernel believes it is unsafe: the kernel will remove the module | |
1396 | without waiting for anyone to stop using it (using the -f option to | |
1397 | rmmod). This is mainly for kernel developers and desperate users. | |
1398 | If unsure, say N. | |
1399 | ||
1da177e4 | 1400 | config MODVERSIONS |
0d541643 | 1401 | bool "Module versioning support" |
1da177e4 LT |
1402 | help |
1403 | Usually, you have to use modules compiled with your kernel. | |
1404 | Saying Y here makes it sometimes possible to use modules | |
1405 | compiled for different kernels, by adding enough information | |
1406 | to the modules to (hopefully) spot any changes which would | |
1407 | make them incompatible with the kernel you are running. If | |
1408 | unsure, say N. | |
1409 | ||
1410 | config MODULE_SRCVERSION_ALL | |
1411 | bool "Source checksum for all modules" | |
1da177e4 LT |
1412 | help |
1413 | Modules which contain a MODULE_VERSION get an extra "srcversion" | |
1414 | field inserted into their modinfo section, which contains a | |
1415 | sum of the source files which made it. This helps maintainers | |
1416 | see exactly which source was used to build a module (since | |
1417 | others sometimes change the module source without updating | |
1418 | the version). With this option, such a "srcversion" field | |
1419 | will be created for all modules. If unsure, say N. | |
1420 | ||
0b0de144 RD |
1421 | endif # MODULES |
1422 | ||
98a79d6a RR |
1423 | config INIT_ALL_POSSIBLE |
1424 | bool | |
1425 | help | |
1426 | Back when each arch used to define their own cpu_online_map and | |
1427 | cpu_possible_map, some of them chose to initialize cpu_possible_map | |
1428 | with all 1s, and others with all 0s. When they were centralised, | |
1429 | it was better to provide this option than to break all the archs | |
692105b8 | 1430 | and have several arch maintainers pursuing me down dark alleys. |
98a79d6a | 1431 | |
1da177e4 LT |
1432 | config STOP_MACHINE |
1433 | bool | |
1434 | default y | |
1435 | depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU | |
1436 | help | |
1437 | Need stop_machine() primitive. | |
3a65dfe8 | 1438 | |
3a65dfe8 | 1439 | source "block/Kconfig" |
e98c3202 AK |
1440 | |
1441 | config PREEMPT_NOTIFIERS | |
1442 | bool | |
e260be67 | 1443 | |
16295bec SK |
1444 | config PADATA |
1445 | depends on SMP | |
1446 | bool | |
1447 | ||
6beb0009 | 1448 | source "kernel/Kconfig.locks" |