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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 | |
22 | default y | |
23 | ||
e360adbe PZ |
24 | config HAVE_IRQ_WORK |
25 | bool | |
26 | ||
27 | config IRQ_WORK | |
28 | bool | |
29 | depends on HAVE_IRQ_WORK | |
30 | ||
ff0cfc66 | 31 | menu "General setup" |
1da177e4 LT |
32 | |
33 | config EXPERIMENTAL | |
34 | bool "Prompt for development and/or incomplete code/drivers" | |
35 | ---help--- | |
36 | Some of the various things that Linux supports (such as network | |
37 | drivers, file systems, network protocols, etc.) can be in a state | |
38 | of development where the functionality, stability, or the level of | |
39 | testing is not yet high enough for general use. This is usually | |
40 | known as the "alpha-test" phase among developers. If a feature is | |
41 | currently in alpha-test, then the developers usually discourage | |
42 | uninformed widespread use of this feature by the general public to | |
43 | avoid "Why doesn't this work?" type mail messages. However, active | |
44 | testing and use of these systems is welcomed. Just be aware that it | |
45 | may not meet the normal level of reliability or it may fail to work | |
46 | in some special cases. Detailed bug reports from people familiar | |
47 | with the kernel internals are usually welcomed by the developers | |
48 | (before submitting bug reports, please read the documents | |
49 | <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>, | |
50 | <file:Documentation/BUG-HUNTING>, and | |
51 | <file:Documentation/oops-tracing.txt> in the kernel source). | |
52 | ||
53 | This option will also make obsoleted drivers available. These are | |
54 | drivers that have been replaced by something else, and/or are | |
55 | scheduled to be removed in a future kernel release. | |
56 | ||
57 | Unless you intend to help test and develop a feature or driver that | |
58 | falls into this category, or you have a situation that requires | |
59 | using these features, you should probably say N here, which will | |
60 | cause the configurator to present you with fewer choices. If | |
61 | you say Y here, you will be offered the choice of using features or | |
62 | drivers that are currently considered to be in the alpha-test phase. | |
63 | ||
1da177e4 LT |
64 | config BROKEN |
65 | bool | |
1da177e4 LT |
66 | |
67 | config BROKEN_ON_SMP | |
68 | bool | |
69 | depends on BROKEN || !SMP | |
70 | default y | |
71 | ||
1da177e4 LT |
72 | config INIT_ENV_ARG_LIMIT |
73 | int | |
dd673bca AB |
74 | default 32 if !UML |
75 | default 128 if UML | |
1da177e4 | 76 | help |
34ad92c2 RD |
77 | Maximum of each of the number of arguments and environment |
78 | variables passed to init from the kernel command line. | |
1da177e4 | 79 | |
1da177e4 | 80 | |
84336466 RM |
81 | config CROSS_COMPILE |
82 | string "Cross-compiler tool prefix" | |
83 | help | |
84 | Same as running 'make CROSS_COMPILE=prefix-' but stored for | |
85 | default make runs in this kernel build directory. You don't | |
86 | need to set this unless you want the configured kernel build | |
87 | directory to select the cross-compiler automatically. | |
88 | ||
1da177e4 LT |
89 | config LOCALVERSION |
90 | string "Local version - append to kernel release" | |
91 | help | |
92 | Append an extra string to the end of your kernel version. | |
93 | This will show up when you type uname, for example. | |
94 | The string you set here will be appended after the contents of | |
95 | any files with a filename matching localversion* in your | |
96 | object and source tree, in that order. Your total string can | |
97 | be a maximum of 64 characters. | |
98 | ||
aaebf433 RA |
99 | config LOCALVERSION_AUTO |
100 | bool "Automatically append version information to the version string" | |
101 | default y | |
102 | help | |
103 | This will try to automatically determine if the current tree is a | |
6e5a5420 RD |
104 | release tree by looking for git tags that belong to the current |
105 | top of tree revision. | |
aaebf433 RA |
106 | |
107 | A string of the format -gxxxxxxxx will be added to the localversion | |
6e5a5420 | 108 | if a git-based tree is found. The string generated by this will be |
aaebf433 | 109 | appended after any matching localversion* files, and after the value |
6e5a5420 | 110 | set in CONFIG_LOCALVERSION. |
aaebf433 | 111 | |
6e5a5420 RD |
112 | (The actual string used here is the first eight characters produced |
113 | by running the command: | |
114 | ||
115 | $ git rev-parse --verify HEAD | |
116 | ||
117 | which is done within the script "scripts/setlocalversion".) | |
aaebf433 | 118 | |
2e9f3bdd PA |
119 | config HAVE_KERNEL_GZIP |
120 | bool | |
121 | ||
122 | config HAVE_KERNEL_BZIP2 | |
123 | bool | |
124 | ||
125 | config HAVE_KERNEL_LZMA | |
126 | bool | |
127 | ||
3ebe1243 LC |
128 | config HAVE_KERNEL_XZ |
129 | bool | |
130 | ||
7dd65feb AT |
131 | config HAVE_KERNEL_LZO |
132 | bool | |
133 | ||
30d65dbf | 134 | choice |
2e9f3bdd PA |
135 | prompt "Kernel compression mode" |
136 | default KERNEL_GZIP | |
3ebe1243 | 137 | depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO |
2e9f3bdd | 138 | help |
30d65dbf AK |
139 | The linux kernel is a kind of self-extracting executable. |
140 | Several compression algorithms are available, which differ | |
141 | in efficiency, compression and decompression speed. | |
142 | Compression speed is only relevant when building a kernel. | |
143 | Decompression speed is relevant at each boot. | |
144 | ||
145 | If you have any problems with bzip2 or lzma compressed | |
146 | kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older | |
147 | version of this functionality (bzip2 only), for 2.4, was | |
148 | supplied by Christian Ludwig) | |
149 | ||
150 | High compression options are mostly useful for users, who | |
151 | are low on disk space (embedded systems), but for whom ram | |
152 | size matters less. | |
153 | ||
154 | If in doubt, select 'gzip' | |
155 | ||
156 | config KERNEL_GZIP | |
2e9f3bdd PA |
157 | bool "Gzip" |
158 | depends on HAVE_KERNEL_GZIP | |
159 | help | |
7dd65feb AT |
160 | The old and tried gzip compression. It provides a good balance |
161 | between compression ratio and decompression speed. | |
30d65dbf AK |
162 | |
163 | config KERNEL_BZIP2 | |
164 | bool "Bzip2" | |
2e9f3bdd | 165 | depends on HAVE_KERNEL_BZIP2 |
30d65dbf AK |
166 | help |
167 | Its compression ratio and speed is intermediate. | |
2e9f3bdd PA |
168 | Decompression speed is slowest among the three. The kernel |
169 | size is about 10% smaller with bzip2, in comparison to gzip. | |
170 | Bzip2 uses a large amount of memory. For modern kernels you | |
171 | will need at least 8MB RAM or more for booting. | |
30d65dbf AK |
172 | |
173 | config KERNEL_LZMA | |
2e9f3bdd PA |
174 | bool "LZMA" |
175 | depends on HAVE_KERNEL_LZMA | |
176 | help | |
177 | The most recent compression algorithm. | |
178 | Its ratio is best, decompression speed is between the other | |
179 | two. Compression is slowest. The kernel size is about 33% | |
180 | smaller with LZMA in comparison to gzip. | |
30d65dbf | 181 | |
3ebe1243 LC |
182 | config KERNEL_XZ |
183 | bool "XZ" | |
184 | depends on HAVE_KERNEL_XZ | |
185 | help | |
186 | XZ uses the LZMA2 algorithm and instruction set specific | |
187 | BCJ filters which can improve compression ratio of executable | |
188 | code. The size of the kernel is about 30% smaller with XZ in | |
189 | comparison to gzip. On architectures for which there is a BCJ | |
190 | filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ | |
191 | will create a few percent smaller kernel than plain LZMA. | |
192 | ||
193 | The speed is about the same as with LZMA: The decompression | |
194 | speed of XZ is better than that of bzip2 but worse than gzip | |
195 | and LZO. Compression is slow. | |
196 | ||
7dd65feb AT |
197 | config KERNEL_LZO |
198 | bool "LZO" | |
199 | depends on HAVE_KERNEL_LZO | |
200 | help | |
201 | Its compression ratio is the poorest among the 4. The kernel | |
681b3049 | 202 | size is about 10% bigger than gzip; however its speed |
7dd65feb AT |
203 | (both compression and decompression) is the fastest. |
204 | ||
30d65dbf AK |
205 | endchoice |
206 | ||
1da177e4 LT |
207 | config SWAP |
208 | bool "Support for paging of anonymous memory (swap)" | |
9361401e | 209 | depends on MMU && BLOCK |
1da177e4 LT |
210 | default y |
211 | help | |
212 | This option allows you to choose whether you want to have support | |
92c3504e | 213 | for so called swap devices or swap files in your kernel that are |
1da177e4 LT |
214 | used to provide more virtual memory than the actual RAM present |
215 | in your computer. If unsure say Y. | |
216 | ||
217 | config SYSVIPC | |
218 | bool "System V IPC" | |
1da177e4 LT |
219 | ---help--- |
220 | Inter Process Communication is a suite of library functions and | |
221 | system calls which let processes (running programs) synchronize and | |
222 | exchange information. It is generally considered to be a good thing, | |
223 | and some programs won't run unless you say Y here. In particular, if | |
224 | you want to run the DOS emulator dosemu under Linux (read the | |
225 | DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), | |
226 | you'll need to say Y here. | |
227 | ||
228 | You can find documentation about IPC with "info ipc" and also in | |
229 | section 6.4 of the Linux Programmer's Guide, available from | |
230 | <http://www.tldp.org/guides.html>. | |
231 | ||
a5494dcd EB |
232 | config SYSVIPC_SYSCTL |
233 | bool | |
234 | depends on SYSVIPC | |
235 | depends on SYSCTL | |
236 | default y | |
237 | ||
1da177e4 LT |
238 | config POSIX_MQUEUE |
239 | bool "POSIX Message Queues" | |
240 | depends on NET && EXPERIMENTAL | |
241 | ---help--- | |
242 | POSIX variant of message queues is a part of IPC. In POSIX message | |
243 | queues every message has a priority which decides about succession | |
244 | of receiving it by a process. If you want to compile and run | |
245 | programs written e.g. for Solaris with use of its POSIX message | |
b0e37650 | 246 | queues (functions mq_*) say Y here. |
1da177e4 LT |
247 | |
248 | POSIX message queues are visible as a filesystem called 'mqueue' | |
249 | and can be mounted somewhere if you want to do filesystem | |
250 | operations on message queues. | |
251 | ||
252 | If unsure, say Y. | |
253 | ||
bdc8e5f8 SH |
254 | config POSIX_MQUEUE_SYSCTL |
255 | bool | |
256 | depends on POSIX_MQUEUE | |
257 | depends on SYSCTL | |
258 | default y | |
259 | ||
1da177e4 LT |
260 | config BSD_PROCESS_ACCT |
261 | bool "BSD Process Accounting" | |
262 | help | |
263 | If you say Y here, a user level program will be able to instruct the | |
264 | kernel (via a special system call) to write process accounting | |
265 | information to a file: whenever a process exits, information about | |
266 | that process will be appended to the file by the kernel. The | |
267 | information includes things such as creation time, owning user, | |
268 | command name, memory usage, controlling terminal etc. (the complete | |
269 | list is in the struct acct in <file:include/linux/acct.h>). It is | |
270 | up to the user level program to do useful things with this | |
271 | information. This is generally a good idea, so say Y. | |
272 | ||
273 | config BSD_PROCESS_ACCT_V3 | |
274 | bool "BSD Process Accounting version 3 file format" | |
275 | depends on BSD_PROCESS_ACCT | |
276 | default n | |
277 | help | |
278 | If you say Y here, the process accounting information is written | |
279 | in a new file format that also logs the process IDs of each | |
280 | process and it's parent. Note that this file format is incompatible | |
281 | with previous v0/v1/v2 file formats, so you will need updated tools | |
282 | for processing it. A preliminary version of these tools is available | |
37a4c940 | 283 | at <http://www.gnu.org/software/acct/>. |
1da177e4 | 284 | |
990d6c2d AK |
285 | config FHANDLE |
286 | bool "open by fhandle syscalls" | |
287 | select EXPORTFS | |
288 | help | |
289 | If you say Y here, a user level program will be able to map | |
290 | file names to handle and then later use the handle for | |
291 | different file system operations. This is useful in implementing | |
292 | userspace file servers, which now track files using handles instead | |
293 | of names. The handle would remain the same even if file names | |
294 | get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) | |
295 | syscalls. | |
296 | ||
c757249a SN |
297 | config TASKSTATS |
298 | bool "Export task/process statistics through netlink (EXPERIMENTAL)" | |
299 | depends on NET | |
300 | default n | |
301 | help | |
302 | Export selected statistics for tasks/processes through the | |
303 | generic netlink interface. Unlike BSD process accounting, the | |
304 | statistics are available during the lifetime of tasks/processes as | |
305 | responses to commands. Like BSD accounting, they are sent to user | |
306 | space on task exit. | |
307 | ||
308 | Say N if unsure. | |
309 | ||
ca74e92b SN |
310 | config TASK_DELAY_ACCT |
311 | bool "Enable per-task delay accounting (EXPERIMENTAL)" | |
6f44993f | 312 | depends on TASKSTATS |
ca74e92b SN |
313 | help |
314 | Collect information on time spent by a task waiting for system | |
315 | resources like cpu, synchronous block I/O completion and swapping | |
316 | in pages. Such statistics can help in setting a task's priorities | |
317 | relative to other tasks for cpu, io, rss limits etc. | |
318 | ||
319 | Say N if unsure. | |
320 | ||
18f705f4 AD |
321 | config TASK_XACCT |
322 | bool "Enable extended accounting over taskstats (EXPERIMENTAL)" | |
323 | depends on TASKSTATS | |
324 | help | |
325 | Collect extended task accounting data and send the data | |
326 | to userland for processing over the taskstats interface. | |
327 | ||
328 | Say N if unsure. | |
329 | ||
330 | config TASK_IO_ACCOUNTING | |
331 | bool "Enable per-task storage I/O accounting (EXPERIMENTAL)" | |
332 | depends on TASK_XACCT | |
333 | help | |
334 | Collect information on the number of bytes of storage I/O which this | |
335 | task has caused. | |
336 | ||
337 | Say N if unsure. | |
338 | ||
1da177e4 LT |
339 | config AUDIT |
340 | bool "Auditing support" | |
804a6a49 | 341 | depends on NET |
1da177e4 LT |
342 | help |
343 | Enable auditing infrastructure that can be used with another | |
344 | kernel subsystem, such as SELinux (which requires this for | |
345 | logging of avc messages output). Does not do system-call | |
346 | auditing without CONFIG_AUDITSYSCALL. | |
347 | ||
348 | config AUDITSYSCALL | |
349 | bool "Enable system-call auditing support" | |
022382a5 | 350 | depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH) |
1da177e4 LT |
351 | default y if SECURITY_SELINUX |
352 | help | |
353 | Enable low-overhead system-call auditing infrastructure that | |
354 | can be used independently or with another kernel subsystem, | |
67640b60 | 355 | such as SELinux. |
1da177e4 | 356 | |
939a67fc EP |
357 | config AUDIT_WATCH |
358 | def_bool y | |
359 | depends on AUDITSYSCALL | |
360 | select FSNOTIFY | |
1da177e4 | 361 | |
74c3cbe3 AV |
362 | config AUDIT_TREE |
363 | def_bool y | |
63c882a0 | 364 | depends on AUDITSYSCALL |
28a3a7eb | 365 | select FSNOTIFY |
74c3cbe3 | 366 | |
d9817ebe TG |
367 | source "kernel/irq/Kconfig" |
368 | ||
c903ff83 MT |
369 | menu "RCU Subsystem" |
370 | ||
371 | choice | |
372 | prompt "RCU Implementation" | |
31c9a24e | 373 | default TREE_RCU |
c903ff83 | 374 | |
c903ff83 MT |
375 | config TREE_RCU |
376 | bool "Tree-based hierarchical RCU" | |
687d7a96 | 377 | depends on !PREEMPT && SMP |
c903ff83 MT |
378 | help |
379 | This option selects the RCU implementation that is | |
380 | designed for very large SMP system with hundreds or | |
c17ef453 PM |
381 | thousands of CPUs. It also scales down nicely to |
382 | smaller systems. | |
c903ff83 | 383 | |
f41d911f | 384 | config TREE_PREEMPT_RCU |
a57eb940 | 385 | bool "Preemptible tree-based hierarchical RCU" |
f41d911f PM |
386 | depends on PREEMPT |
387 | help | |
388 | This option selects the RCU implementation that is | |
389 | designed for very large SMP systems with hundreds or | |
390 | thousands of CPUs, but for which real-time response | |
bbe3eae8 PM |
391 | is also required. It also scales down nicely to |
392 | smaller systems. | |
f41d911f | 393 | |
9b1d82fa PM |
394 | config TINY_RCU |
395 | bool "UP-only small-memory-footprint RCU" | |
396 | depends on !SMP | |
397 | help | |
398 | This option selects the RCU implementation that is | |
399 | designed for UP systems from which real-time response | |
400 | is not required. This option greatly reduces the | |
401 | memory footprint of RCU. | |
402 | ||
a57eb940 PM |
403 | config TINY_PREEMPT_RCU |
404 | bool "Preemptible UP-only small-memory-footprint RCU" | |
405 | depends on !SMP && PREEMPT | |
406 | help | |
407 | This option selects the RCU implementation that is designed | |
408 | for real-time UP systems. This option greatly reduces the | |
409 | memory footprint of RCU. | |
410 | ||
c903ff83 MT |
411 | endchoice |
412 | ||
a57eb940 PM |
413 | config PREEMPT_RCU |
414 | def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU ) | |
415 | help | |
416 | This option enables preemptible-RCU code that is common between | |
417 | the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations. | |
418 | ||
c903ff83 MT |
419 | config RCU_TRACE |
420 | bool "Enable tracing for RCU" | |
c903ff83 MT |
421 | help |
422 | This option provides tracing in RCU which presents stats | |
423 | in debugfs for debugging RCU implementation. | |
424 | ||
425 | Say Y here if you want to enable RCU tracing | |
426 | Say N if you are unsure. | |
427 | ||
428 | config RCU_FANOUT | |
429 | int "Tree-based hierarchical RCU fanout value" | |
430 | range 2 64 if 64BIT | |
431 | range 2 32 if !64BIT | |
f41d911f | 432 | depends on TREE_RCU || TREE_PREEMPT_RCU |
c903ff83 MT |
433 | default 64 if 64BIT |
434 | default 32 if !64BIT | |
435 | help | |
436 | This option controls the fanout of hierarchical implementations | |
437 | of RCU, allowing RCU to work efficiently on machines with | |
4d87ffad PM |
438 | large numbers of CPUs. This value must be at least the fourth |
439 | root of NR_CPUS, which allows NR_CPUS to be insanely large. | |
440 | The default value of RCU_FANOUT should be used for production | |
441 | systems, but if you are stress-testing the RCU implementation | |
442 | itself, small RCU_FANOUT values allow you to test large-system | |
443 | code paths on small(er) systems. | |
c903ff83 MT |
444 | |
445 | Select a specific number if testing RCU itself. | |
446 | Take the default if unsure. | |
447 | ||
448 | config RCU_FANOUT_EXACT | |
449 | bool "Disable tree-based hierarchical RCU auto-balancing" | |
f41d911f | 450 | depends on TREE_RCU || TREE_PREEMPT_RCU |
c903ff83 MT |
451 | default n |
452 | help | |
453 | This option forces use of the exact RCU_FANOUT value specified, | |
454 | regardless of imbalances in the hierarchy. This is useful for | |
455 | testing RCU itself, and might one day be useful on systems with | |
456 | strong NUMA behavior. | |
457 | ||
458 | Without RCU_FANOUT_EXACT, the code will balance the hierarchy. | |
459 | ||
460 | Say N if unsure. | |
461 | ||
8bd93a2c PM |
462 | config RCU_FAST_NO_HZ |
463 | bool "Accelerate last non-dyntick-idle CPU's grace periods" | |
464 | depends on TREE_RCU && NO_HZ && SMP | |
465 | default n | |
466 | help | |
467 | This option causes RCU to attempt to accelerate grace periods | |
468 | in order to allow the final CPU to enter dynticks-idle state | |
469 | more quickly. On the other hand, this option increases the | |
470 | overhead of the dynticks-idle checking, particularly on systems | |
471 | with large numbers of CPUs. | |
472 | ||
473 | Say Y if energy efficiency is critically important, particularly | |
474 | if you have relatively few CPUs. | |
475 | ||
476 | Say N if you are unsure. | |
477 | ||
c903ff83 | 478 | config TREE_RCU_TRACE |
f41d911f | 479 | def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU ) |
c903ff83 MT |
480 | select DEBUG_FS |
481 | help | |
f41d911f PM |
482 | This option provides tracing for the TREE_RCU and |
483 | TREE_PREEMPT_RCU implementations, permitting Makefile to | |
484 | trivially select kernel/rcutree_trace.c. | |
c903ff83 | 485 | |
24278d14 PM |
486 | config RCU_BOOST |
487 | bool "Enable RCU priority boosting" | |
27f4d280 | 488 | depends on RT_MUTEXES && PREEMPT_RCU |
24278d14 PM |
489 | default n |
490 | help | |
491 | This option boosts the priority of preempted RCU readers that | |
492 | block the current preemptible RCU grace period for too long. | |
493 | This option also prevents heavy loads from blocking RCU | |
494 | callback invocation for all flavors of RCU. | |
495 | ||
496 | Say Y here if you are working with real-time apps or heavy loads | |
497 | Say N here if you are unsure. | |
498 | ||
499 | config RCU_BOOST_PRIO | |
500 | int "Real-time priority to boost RCU readers to" | |
501 | range 1 99 | |
502 | depends on RCU_BOOST | |
503 | default 1 | |
504 | help | |
505 | This option specifies the real-time priority to which preempted | |
506 | RCU readers are to be boosted. If you are working with CPU-bound | |
507 | real-time applications, you should specify a priority higher then | |
508 | the highest-priority CPU-bound application. | |
509 | ||
510 | Specify the real-time priority, or take the default if unsure. | |
511 | ||
512 | config RCU_BOOST_DELAY | |
513 | int "Milliseconds to delay boosting after RCU grace-period start" | |
514 | range 0 3000 | |
515 | depends on RCU_BOOST | |
516 | default 500 | |
517 | help | |
518 | This option specifies the time to wait after the beginning of | |
519 | a given grace period before priority-boosting preempted RCU | |
520 | readers blocking that grace period. Note that any RCU reader | |
521 | blocking an expedited RCU grace period is boosted immediately. | |
522 | ||
523 | Accept the default if unsure. | |
524 | ||
c903ff83 MT |
525 | endmenu # "RCU Subsystem" |
526 | ||
1da177e4 | 527 | config IKCONFIG |
f2443ab6 | 528 | tristate "Kernel .config support" |
1da177e4 LT |
529 | ---help--- |
530 | This option enables the complete Linux kernel ".config" file | |
531 | contents to be saved in the kernel. It provides documentation | |
532 | of which kernel options are used in a running kernel or in an | |
533 | on-disk kernel. This information can be extracted from the kernel | |
534 | image file with the script scripts/extract-ikconfig and used as | |
535 | input to rebuild the current kernel or to build another kernel. | |
536 | It can also be extracted from a running kernel by reading | |
537 | /proc/config.gz if enabled (below). | |
538 | ||
539 | config IKCONFIG_PROC | |
540 | bool "Enable access to .config through /proc/config.gz" | |
541 | depends on IKCONFIG && PROC_FS | |
542 | ---help--- | |
543 | This option enables access to the kernel configuration file | |
544 | through /proc/config.gz. | |
545 | ||
794543a2 AJS |
546 | config LOG_BUF_SHIFT |
547 | int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" | |
548 | range 12 21 | |
f17a32e9 | 549 | default 17 |
794543a2 AJS |
550 | help |
551 | Select kernel log buffer size as a power of 2. | |
f17a32e9 AB |
552 | Examples: |
553 | 17 => 128 KB | |
554 | 16 => 64 KB | |
555 | 15 => 32 KB | |
556 | 14 => 16 KB | |
794543a2 AJS |
557 | 13 => 8 KB |
558 | 12 => 4 KB | |
559 | ||
a5574cf6 IM |
560 | # |
561 | # Architectures with an unreliable sched_clock() should select this: | |
562 | # | |
563 | config HAVE_UNSTABLE_SCHED_CLOCK | |
564 | bool | |
565 | ||
23964d2d LZ |
566 | menuconfig CGROUPS |
567 | boolean "Control Group support" | |
0dea1168 | 568 | depends on EVENTFD |
5cdc38f9 | 569 | help |
23964d2d | 570 | This option adds support for grouping sets of processes together, for |
5cdc38f9 KH |
571 | use with process control subsystems such as Cpusets, CFS, memory |
572 | controls or device isolation. | |
573 | See | |
5cdc38f9 | 574 | - Documentation/scheduler/sched-design-CFS.txt (CFS) |
45ce80fb LZ |
575 | - Documentation/cgroups/ (features for grouping, isolation |
576 | and resource control) | |
5cdc38f9 KH |
577 | |
578 | Say N if unsure. | |
579 | ||
23964d2d LZ |
580 | if CGROUPS |
581 | ||
5cdc38f9 KH |
582 | config CGROUP_DEBUG |
583 | bool "Example debug cgroup subsystem" | |
5cdc38f9 KH |
584 | default n |
585 | help | |
586 | This option enables a simple cgroup subsystem that | |
587 | exports useful debugging information about the cgroups | |
23964d2d | 588 | framework. |
5cdc38f9 | 589 | |
23964d2d | 590 | Say N if unsure. |
5cdc38f9 | 591 | |
5cdc38f9 | 592 | config CGROUP_FREEZER |
23964d2d | 593 | bool "Freezer cgroup subsystem" |
23964d2d LZ |
594 | help |
595 | Provides a way to freeze and unfreeze all tasks in a | |
5cdc38f9 KH |
596 | cgroup. |
597 | ||
598 | config CGROUP_DEVICE | |
599 | bool "Device controller for cgroups" | |
5cdc38f9 KH |
600 | help |
601 | Provides a cgroup implementing whitelists for devices which | |
602 | a process in the cgroup can mknod or open. | |
603 | ||
604 | config CPUSETS | |
605 | bool "Cpuset support" | |
5cdc38f9 KH |
606 | help |
607 | This option will let you create and manage CPUSETs which | |
608 | allow dynamically partitioning a system into sets of CPUs and | |
609 | Memory Nodes and assigning tasks to run only within those sets. | |
610 | This is primarily useful on large SMP or NUMA systems. | |
611 | ||
612 | Say N if unsure. | |
613 | ||
23964d2d LZ |
614 | config PROC_PID_CPUSET |
615 | bool "Include legacy /proc/<pid>/cpuset file" | |
616 | depends on CPUSETS | |
617 | default y | |
618 | ||
d842de87 SV |
619 | config CGROUP_CPUACCT |
620 | bool "Simple CPU accounting cgroup subsystem" | |
d842de87 SV |
621 | help |
622 | Provides a simple Resource Controller for monitoring the | |
23964d2d | 623 | total CPU consumed by the tasks in a cgroup. |
d842de87 | 624 | |
e552b661 PE |
625 | config RESOURCE_COUNTERS |
626 | bool "Resource counters" | |
627 | help | |
628 | This option enables controller independent resource accounting | |
23964d2d | 629 | infrastructure that works with cgroups. |
e552b661 | 630 | |
00f0b825 BS |
631 | config CGROUP_MEM_RES_CTLR |
632 | bool "Memory Resource Controller for Control Groups" | |
79ae9c29 | 633 | depends on RESOURCE_COUNTERS |
cf475ad2 | 634 | select MM_OWNER |
00f0b825 | 635 | help |
84ad6d70 | 636 | Provides a memory resource controller that manages both anonymous |
21acb9ca | 637 | memory and page cache. (See Documentation/cgroups/memory.txt) |
00f0b825 BS |
638 | |
639 | Note that setting this option increases fixed memory overhead | |
84ad6d70 KH |
640 | associated with each page of memory in the system. By this, |
641 | 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory | |
642 | usage tracking struct at boot. Total amount of this is printed out | |
643 | at boot. | |
00f0b825 BS |
644 | |
645 | Only enable when you're ok with these trade offs and really | |
84ad6d70 KH |
646 | sure you need the memory resource controller. Even when you enable |
647 | this, you can set "cgroup_disable=memory" at your boot option to | |
648 | disable memory resource controller and you can avoid overheads. | |
c9d5409f | 649 | (and lose benefits of memory resource controller) |
00f0b825 | 650 | |
cf475ad2 BS |
651 | This config option also selects MM_OWNER config option, which |
652 | could in turn add some fork/exit overhead. | |
653 | ||
c077719b | 654 | config CGROUP_MEM_RES_CTLR_SWAP |
65e0e811 KH |
655 | bool "Memory Resource Controller Swap Extension" |
656 | depends on CGROUP_MEM_RES_CTLR && SWAP | |
c077719b KH |
657 | help |
658 | Add swap management feature to memory resource controller. When you | |
659 | enable this, you can limit mem+swap usage per cgroup. In other words, | |
660 | when you disable this, memory resource controller has no cares to | |
661 | usage of swap...a process can exhaust all of the swap. This extension | |
662 | is useful when you want to avoid exhaustion swap but this itself | |
663 | adds more overheads and consumes memory for remembering information. | |
664 | Especially if you use 32bit system or small memory system, please | |
665 | be careful about enabling this. When memory resource controller | |
666 | is disabled by boot option, this will be automatically disabled and | |
667 | there will be no overhead from this. Even when you set this config=y, | |
668 | if boot option "noswapaccount" is set, swap will not be accounted. | |
627991a2 KH |
669 | Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page |
670 | size is 4096bytes, 512k per 1Gbytes of swap. | |
a42c390c MH |
671 | config CGROUP_MEM_RES_CTLR_SWAP_ENABLED |
672 | bool "Memory Resource Controller Swap Extension enabled by default" | |
673 | depends on CGROUP_MEM_RES_CTLR_SWAP | |
674 | default y | |
675 | help | |
676 | Memory Resource Controller Swap Extension comes with its price in | |
677 | a bigger memory consumption. General purpose distribution kernels | |
43d547f9 | 678 | which want to enable the feature but keep it disabled by default |
a42c390c MH |
679 | and let the user enable it by swapaccount boot command line |
680 | parameter should have this option unselected. | |
681 | For those who want to have the feature enabled by default should | |
682 | select this option (if, for some reason, they need to disable it | |
683 | then noswapaccount does the trick). | |
c077719b | 684 | |
e5d1367f SE |
685 | config CGROUP_PERF |
686 | bool "Enable perf_event per-cpu per-container group (cgroup) monitoring" | |
687 | depends on PERF_EVENTS && CGROUPS | |
688 | help | |
689 | This option extends the per-cpu mode to restrict monitoring to | |
2d0f2520 | 690 | threads which belong to the cgroup specified and run on the |
e5d1367f SE |
691 | designated cpu. |
692 | ||
693 | Say N if unsure. | |
694 | ||
7c941438 DG |
695 | menuconfig CGROUP_SCHED |
696 | bool "Group CPU scheduler" | |
79ae9c29 | 697 | depends on EXPERIMENTAL |
7c941438 DG |
698 | default n |
699 | help | |
700 | This feature lets CPU scheduler recognize task groups and control CPU | |
701 | bandwidth allocation to such task groups. It uses cgroups to group | |
702 | tasks. | |
703 | ||
704 | if CGROUP_SCHED | |
705 | config FAIR_GROUP_SCHED | |
706 | bool "Group scheduling for SCHED_OTHER" | |
707 | depends on CGROUP_SCHED | |
708 | default CGROUP_SCHED | |
709 | ||
710 | config RT_GROUP_SCHED | |
711 | bool "Group scheduling for SCHED_RR/FIFO" | |
712 | depends on EXPERIMENTAL | |
713 | depends on CGROUP_SCHED | |
714 | default n | |
715 | help | |
716 | This feature lets you explicitly allocate real CPU bandwidth | |
32bd7eb5 | 717 | to task groups. If enabled, it will also make it impossible to |
7c941438 DG |
718 | schedule realtime tasks for non-root users until you allocate |
719 | realtime bandwidth for them. | |
720 | See Documentation/scheduler/sched-rt-group.txt for more information. | |
721 | ||
722 | endif #CGROUP_SCHED | |
723 | ||
afc24d49 VG |
724 | config BLK_CGROUP |
725 | tristate "Block IO controller" | |
79ae9c29 | 726 | depends on BLOCK |
afc24d49 VG |
727 | default n |
728 | ---help--- | |
729 | Generic block IO controller cgroup interface. This is the common | |
730 | cgroup interface which should be used by various IO controlling | |
731 | policies. | |
732 | ||
733 | Currently, CFQ IO scheduler uses it to recognize task groups and | |
734 | control disk bandwidth allocation (proportional time slice allocation) | |
e43473b7 VG |
735 | to such task groups. It is also used by bio throttling logic in |
736 | block layer to implement upper limit in IO rates on a device. | |
afc24d49 VG |
737 | |
738 | This option only enables generic Block IO controller infrastructure. | |
e43473b7 | 739 | One needs to also enable actual IO controlling logic/policy. For |
79e2e759 MW |
740 | enabling proportional weight division of disk bandwidth in CFQ, set |
741 | CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set | |
c5e0591a | 742 | CONFIG_BLK_DEV_THROTTLING=y. |
afc24d49 VG |
743 | |
744 | See Documentation/cgroups/blkio-controller.txt for more information. | |
745 | ||
746 | config DEBUG_BLK_CGROUP | |
747 | bool "Enable Block IO controller debugging" | |
748 | depends on BLK_CGROUP | |
749 | default n | |
750 | ---help--- | |
751 | Enable some debugging help. Currently it exports additional stat | |
752 | files in a cgroup which can be useful for debugging. | |
753 | ||
23964d2d | 754 | endif # CGROUPS |
c077719b | 755 | |
8dd2a82c | 756 | menuconfig NAMESPACES |
6a108a14 DR |
757 | bool "Namespaces support" if EXPERT |
758 | default !EXPERT | |
c5289a69 PE |
759 | help |
760 | Provides the way to make tasks work with different objects using | |
761 | the same id. For example same IPC id may refer to different objects | |
762 | or same user id or pid may refer to different tasks when used in | |
763 | different namespaces. | |
764 | ||
8dd2a82c DL |
765 | if NAMESPACES |
766 | ||
58bfdd6d PE |
767 | config UTS_NS |
768 | bool "UTS namespace" | |
17a6d441 | 769 | default y |
58bfdd6d PE |
770 | help |
771 | In this namespace tasks see different info provided with the | |
772 | uname() system call | |
773 | ||
ae5e1b22 PE |
774 | config IPC_NS |
775 | bool "IPC namespace" | |
8dd2a82c | 776 | depends on (SYSVIPC || POSIX_MQUEUE) |
17a6d441 | 777 | default y |
ae5e1b22 PE |
778 | help |
779 | In this namespace tasks work with IPC ids which correspond to | |
614b84cf | 780 | different IPC objects in different namespaces. |
ae5e1b22 | 781 | |
aee16ce7 PE |
782 | config USER_NS |
783 | bool "User namespace (EXPERIMENTAL)" | |
8dd2a82c | 784 | depends on EXPERIMENTAL |
17a6d441 | 785 | default y |
aee16ce7 PE |
786 | help |
787 | This allows containers, i.e. vservers, to use user namespaces | |
788 | to provide different user info for different servers. | |
789 | If unsure, say N. | |
790 | ||
74bd59bb | 791 | config PID_NS |
9bd38c2c | 792 | bool "PID Namespaces" |
17a6d441 | 793 | default y |
74bd59bb | 794 | help |
12d2b8f9 | 795 | Support process id namespaces. This allows having multiple |
692105b8 | 796 | processes with the same pid as long as they are in different |
74bd59bb PE |
797 | pid namespaces. This is a building block of containers. |
798 | ||
d6eb633f MH |
799 | config NET_NS |
800 | bool "Network namespace" | |
8dd2a82c | 801 | depends on NET |
17a6d441 | 802 | default y |
d6eb633f MH |
803 | help |
804 | Allow user space to create what appear to be multiple instances | |
805 | of the network stack. | |
806 | ||
8dd2a82c DL |
807 | endif # NAMESPACES |
808 | ||
5091faa4 MG |
809 | config SCHED_AUTOGROUP |
810 | bool "Automatic process group scheduling" | |
811 | select EVENTFD | |
812 | select CGROUPS | |
813 | select CGROUP_SCHED | |
814 | select FAIR_GROUP_SCHED | |
815 | help | |
816 | This option optimizes the scheduler for common desktop workloads by | |
817 | automatically creating and populating task groups. This separation | |
818 | of workloads isolates aggressive CPU burners (like build jobs) from | |
819 | desktop applications. Task group autogeneration is currently based | |
820 | upon task session. | |
821 | ||
7af37bec DL |
822 | config MM_OWNER |
823 | bool | |
824 | ||
825 | config SYSFS_DEPRECATED | |
5d6a4ea5 | 826 | bool "Enable deprecated sysfs features to support old userspace tools" |
7af37bec DL |
827 | depends on SYSFS |
828 | default n | |
829 | help | |
830 | This option adds code that switches the layout of the "block" class | |
831 | devices, to not show up in /sys/class/block/, but only in | |
832 | /sys/block/. | |
833 | ||
834 | This switch is only active when the sysfs.deprecated=1 boot option is | |
835 | passed or the SYSFS_DEPRECATED_V2 option is set. | |
836 | ||
837 | This option allows new kernels to run on old distributions and tools, | |
838 | which might get confused by /sys/class/block/. Since 2007/2008 all | |
839 | major distributions and tools handle this just fine. | |
840 | ||
841 | Recent distributions and userspace tools after 2009/2010 depend on | |
842 | the existence of /sys/class/block/, and will not work with this | |
843 | option enabled. | |
844 | ||
845 | Only if you are using a new kernel on an old distribution, you might | |
846 | need to say Y here. | |
847 | ||
848 | config SYSFS_DEPRECATED_V2 | |
5d6a4ea5 | 849 | bool "Enable deprecated sysfs features by default" |
7af37bec DL |
850 | default n |
851 | depends on SYSFS | |
852 | depends on SYSFS_DEPRECATED | |
853 | help | |
854 | Enable deprecated sysfs by default. | |
855 | ||
856 | See the CONFIG_SYSFS_DEPRECATED option for more details about this | |
857 | option. | |
858 | ||
859 | Only if you are using a new kernel on an old distribution, you might | |
860 | need to say Y here. Even then, odds are you would not need it | |
861 | enabled, you can always pass the boot option if absolutely necessary. | |
862 | ||
863 | config RELAY | |
864 | bool "Kernel->user space relay support (formerly relayfs)" | |
865 | help | |
866 | This option enables support for relay interface support in | |
867 | certain file systems (such as debugfs). | |
868 | It is designed to provide an efficient mechanism for tools and | |
869 | facilities to relay large amounts of data from kernel space to | |
870 | user space. | |
871 | ||
872 | If unsure, say N. | |
873 | ||
f991633d DG |
874 | config BLK_DEV_INITRD |
875 | bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" | |
876 | depends on BROKEN || !FRV | |
877 | help | |
878 | The initial RAM filesystem is a ramfs which is loaded by the | |
879 | boot loader (loadlin or lilo) and that is mounted as root | |
880 | before the normal boot procedure. It is typically used to | |
881 | load modules needed to mount the "real" root file system, | |
882 | etc. See <file:Documentation/initrd.txt> for details. | |
883 | ||
884 | If RAM disk support (BLK_DEV_RAM) is also included, this | |
885 | also enables initial RAM disk (initrd) support and adds | |
886 | 15 Kbytes (more on some other architectures) to the kernel size. | |
887 | ||
888 | If unsure say Y. | |
889 | ||
c33df4ea JPS |
890 | if BLK_DEV_INITRD |
891 | ||
dbec4866 SR |
892 | source "usr/Kconfig" |
893 | ||
c33df4ea JPS |
894 | endif |
895 | ||
c45b4f1f | 896 | config CC_OPTIMIZE_FOR_SIZE |
96fffeb4 | 897 | bool "Optimize for size" |
c45b4f1f LT |
898 | help |
899 | Enabling this option will pass "-Os" instead of "-O2" to gcc | |
900 | resulting in a smaller kernel. | |
901 | ||
775a7229 | 902 | If unsure, say Y. |
c45b4f1f | 903 | |
0847062a RD |
904 | config SYSCTL |
905 | bool | |
906 | ||
b943c460 RD |
907 | config ANON_INODES |
908 | bool | |
909 | ||
6a108a14 DR |
910 | menuconfig EXPERT |
911 | bool "Configure standard kernel features (expert users)" | |
1da177e4 LT |
912 | help |
913 | This option allows certain base kernel options and settings | |
914 | to be disabled or tweaked. This is for specialized | |
915 | environments which can tolerate a "non-standard" kernel. | |
916 | Only use this if you really know what you are doing. | |
917 | ||
ae81f9e3 | 918 | config UID16 |
6a108a14 | 919 | bool "Enable 16-bit UID system calls" if EXPERT |
09337f50 | 920 | depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION) |
ae81f9e3 CE |
921 | default y |
922 | help | |
923 | This enables the legacy 16-bit UID syscall wrappers. | |
924 | ||
b89a8171 | 925 | config SYSCTL_SYSCALL |
6a108a14 | 926 | bool "Sysctl syscall support" if EXPERT |
26a7034b | 927 | depends on PROC_SYSCTL |
13bb7e37 | 928 | default y |
b89a8171 | 929 | select SYSCTL |
ae81f9e3 | 930 | ---help--- |
13bb7e37 EB |
931 | sys_sysctl uses binary paths that have been found challenging |
932 | to properly maintain and use. The interface in /proc/sys | |
933 | using paths with ascii names is now the primary path to this | |
934 | information. | |
b89a8171 | 935 | |
13bb7e37 EB |
936 | Almost nothing using the binary sysctl interface so if you are |
937 | trying to save some space it is probably safe to disable this, | |
938 | making your kernel marginally smaller. | |
b89a8171 | 939 | |
13bb7e37 | 940 | If unsure say Y here. |
ae81f9e3 | 941 | |
1da177e4 | 942 | config KALLSYMS |
6a108a14 | 943 | bool "Load all symbols for debugging/ksymoops" if EXPERT |
1da177e4 LT |
944 | default y |
945 | help | |
946 | Say Y here to let the kernel print out symbolic crash information and | |
947 | symbolic stack backtraces. This increases the size of the kernel | |
948 | somewhat, as all symbols have to be loaded into the kernel image. | |
949 | ||
950 | config KALLSYMS_ALL | |
951 | bool "Include all symbols in kallsyms" | |
952 | depends on DEBUG_KERNEL && KALLSYMS | |
953 | help | |
71a83ec7 AB |
954 | Normally kallsyms only contains the symbols of functions for nicer |
955 | OOPS messages and backtraces (i.e., symbols from the text and inittext | |
956 | sections). This is sufficient for most cases. And only in very rare | |
957 | cases (e.g., when a debugger is used) all symbols are required (e.g., | |
958 | names of variables from the data sections, etc). | |
959 | ||
960 | This option makes sure that all symbols are loaded into the kernel | |
961 | image (i.e., symbols from all sections) in cost of increased kernel | |
962 | size (depending on the kernel configuration, it may be 300KiB or | |
963 | something like this). | |
964 | ||
965 | Say N unless you really need all symbols. | |
d59745ce | 966 | |
712f47ce | 967 | config HOTPLUG |
6a108a14 | 968 | bool "Support for hot-pluggable devices" if EXPERT |
712f47ce GKH |
969 | default y |
970 | help | |
971 | This option is provided for the case where no hotplug or uevent | |
972 | capabilities is wanted by the kernel. You should only consider | |
973 | disabling this option for embedded systems that do not use modules, a | |
974 | dynamic /dev tree, or dynamic device discovery. Just say Y. | |
975 | ||
d59745ce MM |
976 | config PRINTK |
977 | default y | |
6a108a14 | 978 | bool "Enable support for printk" if EXPERT |
d59745ce MM |
979 | help |
980 | This option enables normal printk support. Removing it | |
981 | eliminates most of the message strings from the kernel image | |
982 | and makes the kernel more or less silent. As this makes it | |
983 | very difficult to diagnose system problems, saying N here is | |
984 | strongly discouraged. | |
985 | ||
c8538a7a | 986 | config BUG |
6a108a14 | 987 | bool "BUG() support" if EXPERT |
c8538a7a MM |
988 | default y |
989 | help | |
990 | Disabling this option eliminates support for BUG and WARN, reducing | |
991 | the size of your kernel image and potentially quietly ignoring | |
992 | numerous fatal conditions. You should only consider disabling this | |
993 | option for embedded systems with no facilities for reporting errors. | |
994 | Just say Y. | |
995 | ||
708e9a79 MM |
996 | config ELF_CORE |
997 | default y | |
6a108a14 | 998 | bool "Enable ELF core dumps" if EXPERT |
708e9a79 MM |
999 | help |
1000 | Enable support for generating core dumps. Disabling saves about 4k. | |
1001 | ||
e5e1d3cb | 1002 | config PCSPKR_PLATFORM |
6a108a14 | 1003 | bool "Enable PC-Speaker support" if EXPERT |
e5e1d3cb SS |
1004 | depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES |
1005 | default y | |
1006 | help | |
1007 | This option allows to disable the internal PC-Speaker | |
1008 | support, saving some memory. | |
1009 | ||
1da177e4 LT |
1010 | config BASE_FULL |
1011 | default y | |
6a108a14 | 1012 | bool "Enable full-sized data structures for core" if EXPERT |
1da177e4 LT |
1013 | help |
1014 | Disabling this option reduces the size of miscellaneous core | |
1015 | kernel data structures. This saves memory on small machines, | |
1016 | but may reduce performance. | |
1017 | ||
1018 | config FUTEX | |
6a108a14 | 1019 | bool "Enable futex support" if EXPERT |
1da177e4 | 1020 | default y |
23f78d4a | 1021 | select RT_MUTEXES |
1da177e4 LT |
1022 | help |
1023 | Disabling this option will cause the kernel to be built without | |
1024 | support for "fast userspace mutexes". The resulting kernel may not | |
1025 | run glibc-based applications correctly. | |
1026 | ||
1027 | config EPOLL | |
6a108a14 | 1028 | bool "Enable eventpoll support" if EXPERT |
1da177e4 | 1029 | default y |
448e3cee | 1030 | select ANON_INODES |
1da177e4 LT |
1031 | help |
1032 | Disabling this option will cause the kernel to be built without | |
1033 | support for epoll family of system calls. | |
1034 | ||
fba2afaa | 1035 | config SIGNALFD |
6a108a14 | 1036 | bool "Enable signalfd() system call" if EXPERT |
448e3cee | 1037 | select ANON_INODES |
fba2afaa DL |
1038 | default y |
1039 | help | |
1040 | Enable the signalfd() system call that allows to receive signals | |
1041 | on a file descriptor. | |
1042 | ||
1043 | If unsure, say Y. | |
1044 | ||
b215e283 | 1045 | config TIMERFD |
6a108a14 | 1046 | bool "Enable timerfd() system call" if EXPERT |
448e3cee | 1047 | select ANON_INODES |
b215e283 DL |
1048 | default y |
1049 | help | |
1050 | Enable the timerfd() system call that allows to receive timer | |
1051 | events on a file descriptor. | |
1052 | ||
1053 | If unsure, say Y. | |
1054 | ||
e1ad7468 | 1055 | config EVENTFD |
6a108a14 | 1056 | bool "Enable eventfd() system call" if EXPERT |
448e3cee | 1057 | select ANON_INODES |
e1ad7468 DL |
1058 | default y |
1059 | help | |
1060 | Enable the eventfd() system call that allows to receive both | |
1061 | kernel notification (ie. KAIO) or userspace notifications. | |
1062 | ||
1063 | If unsure, say Y. | |
1064 | ||
1da177e4 | 1065 | config SHMEM |
6a108a14 | 1066 | bool "Use full shmem filesystem" if EXPERT |
1da177e4 LT |
1067 | default y |
1068 | depends on MMU | |
1069 | help | |
1070 | The shmem is an internal filesystem used to manage shared memory. | |
1071 | It is backed by swap and manages resource limits. It is also exported | |
1072 | to userspace as tmpfs if TMPFS is enabled. Disabling this | |
1073 | option replaces shmem and tmpfs with the much simpler ramfs code, | |
1074 | which may be appropriate on small systems without swap. | |
1075 | ||
ebf3f09c | 1076 | config AIO |
6a108a14 | 1077 | bool "Enable AIO support" if EXPERT |
ebf3f09c TP |
1078 | default y |
1079 | help | |
1080 | This option enables POSIX asynchronous I/O which may by used | |
1081 | by some high performance threaded applications. Disabling | |
1082 | this option saves about 7k. | |
1083 | ||
6befe5f6 RD |
1084 | config EMBEDDED |
1085 | bool "Embedded system" | |
1086 | select EXPERT | |
1087 | help | |
1088 | This option should be enabled if compiling the kernel for | |
1089 | an embedded system so certain expert options are available | |
1090 | for configuration. | |
1091 | ||
cdd6c482 | 1092 | config HAVE_PERF_EVENTS |
0793a61d | 1093 | bool |
018df72d MF |
1094 | help |
1095 | See tools/perf/design.txt for details. | |
0793a61d | 1096 | |
906010b2 PZ |
1097 | config PERF_USE_VMALLOC |
1098 | bool | |
1099 | help | |
1100 | See tools/perf/design.txt for details | |
1101 | ||
57c0c15b | 1102 | menu "Kernel Performance Events And Counters" |
0793a61d | 1103 | |
cdd6c482 | 1104 | config PERF_EVENTS |
57c0c15b IM |
1105 | bool "Kernel performance events and counters" |
1106 | default y if (PROFILING || PERF_COUNTERS) | |
cdd6c482 | 1107 | depends on HAVE_PERF_EVENTS |
4c59e467 | 1108 | select ANON_INODES |
e360adbe | 1109 | select IRQ_WORK |
0793a61d | 1110 | help |
57c0c15b IM |
1111 | Enable kernel support for various performance events provided |
1112 | by software and hardware. | |
0793a61d | 1113 | |
dd77038d | 1114 | Software events are supported either built-in or via the |
57c0c15b | 1115 | use of generic tracepoints. |
0793a61d | 1116 | |
57c0c15b IM |
1117 | Most modern CPUs support performance events via performance |
1118 | counter registers. These registers count the number of certain | |
0793a61d TG |
1119 | types of hw events: such as instructions executed, cachemisses |
1120 | suffered, or branches mis-predicted - without slowing down the | |
1121 | kernel or applications. These registers can also trigger interrupts | |
1122 | when a threshold number of events have passed - and can thus be | |
1123 | used to profile the code that runs on that CPU. | |
1124 | ||
57c0c15b | 1125 | The Linux Performance Event subsystem provides an abstraction of |
dd77038d | 1126 | these software and hardware event capabilities, available via a |
57c0c15b | 1127 | system call and used by the "perf" utility in tools/perf/. It |
0793a61d TG |
1128 | provides per task and per CPU counters, and it provides event |
1129 | capabilities on top of those. | |
1130 | ||
1131 | Say Y if unsure. | |
1132 | ||
57c0c15b IM |
1133 | config PERF_COUNTERS |
1134 | bool "Kernel performance counters (old config option)" | |
1135 | depends on HAVE_PERF_EVENTS | |
1136 | help | |
1137 | This config has been obsoleted by the PERF_EVENTS | |
1138 | config option - please see that one for details. | |
1139 | ||
1140 | It has no effect on the kernel whether you enable | |
1141 | it or not, it is a compatibility placeholder. | |
1142 | ||
1143 | Say N if unsure. | |
1144 | ||
906010b2 PZ |
1145 | config DEBUG_PERF_USE_VMALLOC |
1146 | default n | |
1147 | bool "Debug: use vmalloc to back perf mmap() buffers" | |
1148 | depends on PERF_EVENTS && DEBUG_KERNEL | |
1149 | select PERF_USE_VMALLOC | |
1150 | help | |
1151 | Use vmalloc memory to back perf mmap() buffers. | |
1152 | ||
1153 | Mostly useful for debugging the vmalloc code on platforms | |
1154 | that don't require it. | |
1155 | ||
1156 | Say N if unsure. | |
1157 | ||
0793a61d TG |
1158 | endmenu |
1159 | ||
f8891e5e CL |
1160 | config VM_EVENT_COUNTERS |
1161 | default y | |
6a108a14 | 1162 | bool "Enable VM event counters for /proc/vmstat" if EXPERT |
f8891e5e | 1163 | help |
2aea4fb6 PJ |
1164 | VM event counters are needed for event counts to be shown. |
1165 | This option allows the disabling of the VM event counters | |
6a108a14 | 1166 | on EXPERT systems. /proc/vmstat will only show page counts |
2aea4fb6 | 1167 | if VM event counters are disabled. |
f8891e5e | 1168 | |
3d137310 TP |
1169 | config PCI_QUIRKS |
1170 | default y | |
6a108a14 | 1171 | bool "Enable PCI quirk workarounds" if EXPERT |
61cfc7e4 | 1172 | depends on PCI |
3d137310 TP |
1173 | help |
1174 | This enables workarounds for various PCI chipset | |
1175 | bugs/quirks. Disable this only if your target machine is | |
1176 | unaffected by PCI quirks. | |
1177 | ||
41ecc55b CL |
1178 | config SLUB_DEBUG |
1179 | default y | |
6a108a14 | 1180 | bool "Enable SLUB debugging support" if EXPERT |
f6acb635 | 1181 | depends on SLUB && SYSFS |
41ecc55b CL |
1182 | help |
1183 | SLUB has extensive debug support features. Disabling these can | |
1184 | result in significant savings in code size. This also disables | |
1185 | SLUB sysfs support. /sys/slab will not exist and there will be | |
1186 | no support for cache validation etc. | |
1187 | ||
b943c460 RD |
1188 | config COMPAT_BRK |
1189 | bool "Disable heap randomization" | |
1190 | default y | |
1191 | help | |
1192 | Randomizing heap placement makes heap exploits harder, but it | |
1193 | also breaks ancient binaries (including anything libc5 based). | |
1194 | This option changes the bootup default to heap randomization | |
692105b8 | 1195 | disabled, and can be overridden at runtime by setting |
b943c460 RD |
1196 | /proc/sys/kernel/randomize_va_space to 2. |
1197 | ||
1198 | On non-ancient distros (post-2000 ones) N is usually a safe choice. | |
1199 | ||
81819f0f CL |
1200 | choice |
1201 | prompt "Choose SLAB allocator" | |
a0acd820 | 1202 | default SLUB |
81819f0f CL |
1203 | help |
1204 | This option allows to select a slab allocator. | |
1205 | ||
1206 | config SLAB | |
1207 | bool "SLAB" | |
1208 | help | |
1209 | The regular slab allocator that is established and known to work | |
34013886 | 1210 | well in all environments. It organizes cache hot objects in |
02f56210 | 1211 | per cpu and per node queues. |
81819f0f CL |
1212 | |
1213 | config SLUB | |
81819f0f CL |
1214 | bool "SLUB (Unqueued Allocator)" |
1215 | help | |
1216 | SLUB is a slab allocator that minimizes cache line usage | |
1217 | instead of managing queues of cached objects (SLAB approach). | |
1218 | Per cpu caching is realized using slabs of objects instead | |
1219 | of queues of objects. SLUB can use memory efficiently | |
02f56210 SA |
1220 | and has enhanced diagnostics. SLUB is the default choice for |
1221 | a slab allocator. | |
81819f0f CL |
1222 | |
1223 | config SLOB | |
6a108a14 | 1224 | depends on EXPERT |
81819f0f CL |
1225 | bool "SLOB (Simple Allocator)" |
1226 | help | |
37291458 MM |
1227 | SLOB replaces the stock allocator with a drastically simpler |
1228 | allocator. SLOB is generally more space efficient but | |
1229 | does not perform as well on large systems. | |
81819f0f CL |
1230 | |
1231 | endchoice | |
1232 | ||
ea637639 JZ |
1233 | config MMAP_ALLOW_UNINITIALIZED |
1234 | bool "Allow mmapped anonymous memory to be uninitialized" | |
6a108a14 | 1235 | depends on EXPERT && !MMU |
ea637639 JZ |
1236 | default n |
1237 | help | |
1238 | Normally, and according to the Linux spec, anonymous memory obtained | |
1239 | from mmap() has it's contents cleared before it is passed to | |
1240 | userspace. Enabling this config option allows you to request that | |
1241 | mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus | |
1242 | providing a huge performance boost. If this option is not enabled, | |
1243 | then the flag will be ignored. | |
1244 | ||
1245 | This is taken advantage of by uClibc's malloc(), and also by | |
1246 | ELF-FDPIC binfmt's brk and stack allocator. | |
1247 | ||
1248 | Because of the obvious security issues, this option should only be | |
1249 | enabled on embedded devices where you control what is run in | |
1250 | userspace. Since that isn't generally a problem on no-MMU systems, | |
1251 | it is normally safe to say Y here. | |
1252 | ||
1253 | See Documentation/nommu-mmap.txt for more information. | |
1254 | ||
125e5645 | 1255 | config PROFILING |
b309a294 | 1256 | bool "Profiling support" |
125e5645 MD |
1257 | help |
1258 | Say Y here to enable the extended profiling support mechanisms used | |
1259 | by profilers such as OProfile. | |
1260 | ||
5f87f112 IM |
1261 | # |
1262 | # Place an empty function call at each tracepoint site. Can be | |
1263 | # dynamically changed for a probe function. | |
1264 | # | |
97e1c18e | 1265 | config TRACEPOINTS |
5f87f112 | 1266 | bool |
97e1c18e | 1267 | |
fb32e03f MD |
1268 | source "arch/Kconfig" |
1269 | ||
1da177e4 LT |
1270 | endmenu # General setup |
1271 | ||
ee7e5516 DB |
1272 | config HAVE_GENERIC_DMA_COHERENT |
1273 | bool | |
1274 | default n | |
1275 | ||
158a9624 LT |
1276 | config SLABINFO |
1277 | bool | |
1278 | depends on PROC_FS | |
0f389ec6 | 1279 | depends on SLAB || SLUB_DEBUG |
158a9624 LT |
1280 | default y |
1281 | ||
ae81f9e3 CE |
1282 | config RT_MUTEXES |
1283 | boolean | |
ae81f9e3 | 1284 | |
1da177e4 LT |
1285 | config BASE_SMALL |
1286 | int | |
1287 | default 0 if BASE_FULL | |
1288 | default 1 if !BASE_FULL | |
1289 | ||
66da5733 | 1290 | menuconfig MODULES |
1da177e4 LT |
1291 | bool "Enable loadable module support" |
1292 | help | |
1293 | Kernel modules are small pieces of compiled code which can | |
1294 | be inserted in the running kernel, rather than being | |
1295 | permanently built into the kernel. You use the "modprobe" | |
1296 | tool to add (and sometimes remove) them. If you say Y here, | |
1297 | many parts of the kernel can be built as modules (by | |
1298 | answering M instead of Y where indicated): this is most | |
1299 | useful for infrequently used options which are not required | |
1300 | for booting. For more information, see the man pages for | |
1301 | modprobe, lsmod, modinfo, insmod and rmmod. | |
1302 | ||
1303 | If you say Y here, you will need to run "make | |
1304 | modules_install" to put the modules under /lib/modules/ | |
1305 | where modprobe can find them (you may need to be root to do | |
1306 | this). | |
1307 | ||
1308 | If unsure, say Y. | |
1309 | ||
0b0de144 RD |
1310 | if MODULES |
1311 | ||
826e4506 LT |
1312 | config MODULE_FORCE_LOAD |
1313 | bool "Forced module loading" | |
826e4506 LT |
1314 | default n |
1315 | help | |
91e37a79 RR |
1316 | Allow loading of modules without version information (ie. modprobe |
1317 | --force). Forced module loading sets the 'F' (forced) taint flag and | |
1318 | is usually a really bad idea. | |
826e4506 | 1319 | |
1da177e4 LT |
1320 | config MODULE_UNLOAD |
1321 | bool "Module unloading" | |
1da177e4 LT |
1322 | help |
1323 | Without this option you will not be able to unload any | |
1324 | modules (note that some modules may not be unloadable | |
f7f5b675 DV |
1325 | anyway), which makes your kernel smaller, faster |
1326 | and simpler. If unsure, say Y. | |
1da177e4 LT |
1327 | |
1328 | config MODULE_FORCE_UNLOAD | |
1329 | bool "Forced module unloading" | |
1330 | depends on MODULE_UNLOAD && EXPERIMENTAL | |
1331 | help | |
1332 | This option allows you to force a module to unload, even if the | |
1333 | kernel believes it is unsafe: the kernel will remove the module | |
1334 | without waiting for anyone to stop using it (using the -f option to | |
1335 | rmmod). This is mainly for kernel developers and desperate users. | |
1336 | If unsure, say N. | |
1337 | ||
1da177e4 | 1338 | config MODVERSIONS |
0d541643 | 1339 | bool "Module versioning support" |
1da177e4 LT |
1340 | help |
1341 | Usually, you have to use modules compiled with your kernel. | |
1342 | Saying Y here makes it sometimes possible to use modules | |
1343 | compiled for different kernels, by adding enough information | |
1344 | to the modules to (hopefully) spot any changes which would | |
1345 | make them incompatible with the kernel you are running. If | |
1346 | unsure, say N. | |
1347 | ||
1348 | config MODULE_SRCVERSION_ALL | |
1349 | bool "Source checksum for all modules" | |
1da177e4 LT |
1350 | help |
1351 | Modules which contain a MODULE_VERSION get an extra "srcversion" | |
1352 | field inserted into their modinfo section, which contains a | |
1353 | sum of the source files which made it. This helps maintainers | |
1354 | see exactly which source was used to build a module (since | |
1355 | others sometimes change the module source without updating | |
1356 | the version). With this option, such a "srcversion" field | |
1357 | will be created for all modules. If unsure, say N. | |
1358 | ||
0b0de144 RD |
1359 | endif # MODULES |
1360 | ||
98a79d6a RR |
1361 | config INIT_ALL_POSSIBLE |
1362 | bool | |
1363 | help | |
1364 | Back when each arch used to define their own cpu_online_map and | |
1365 | cpu_possible_map, some of them chose to initialize cpu_possible_map | |
1366 | with all 1s, and others with all 0s. When they were centralised, | |
1367 | it was better to provide this option than to break all the archs | |
692105b8 | 1368 | and have several arch maintainers pursuing me down dark alleys. |
98a79d6a | 1369 | |
1da177e4 LT |
1370 | config STOP_MACHINE |
1371 | bool | |
1372 | default y | |
1373 | depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU | |
1374 | help | |
1375 | Need stop_machine() primitive. | |
3a65dfe8 | 1376 | |
3a65dfe8 | 1377 | source "block/Kconfig" |
e98c3202 AK |
1378 | |
1379 | config PREEMPT_NOTIFIERS | |
1380 | bool | |
e260be67 | 1381 | |
16295bec SK |
1382 | config PADATA |
1383 | depends on SMP | |
1384 | bool | |
1385 | ||
6beb0009 | 1386 | source "kernel/Kconfig.locks" |