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1 | config ARCH | |
2 | string | |
3 | option env="ARCH" | |
4 | ||
5 | config KERNELVERSION | |
6 | string | |
7 | option env="KERNELVERSION" | |
8 | ||
9 | config DEFCONFIG_LIST | |
10 | string | |
11 | depends on !UML | |
12 | option defconfig_list | |
13 | default "/lib/modules/$UNAME_RELEASE/.config" | |
14 | default "/etc/kernel-config" | |
15 | default "/boot/config-$UNAME_RELEASE" | |
16 | default "$ARCH_DEFCONFIG" | |
17 | default "arch/$ARCH/defconfig" | |
18 | ||
19 | config CONSTRUCTORS | |
20 | bool | |
21 | depends on !UML | |
22 | ||
23 | config IRQ_WORK | |
24 | bool | |
25 | ||
26 | config BUILDTIME_EXTABLE_SORT | |
27 | bool | |
28 | ||
29 | menu "General setup" | |
30 | ||
31 | config BROKEN | |
32 | bool | |
33 | ||
34 | config BROKEN_ON_SMP | |
35 | bool | |
36 | depends on BROKEN || !SMP | |
37 | default y | |
38 | ||
39 | config INIT_ENV_ARG_LIMIT | |
40 | int | |
41 | default 32 if !UML | |
42 | default 128 if UML | |
43 | help | |
44 | Maximum of each of the number of arguments and environment | |
45 | variables passed to init from the kernel command line. | |
46 | ||
47 | ||
48 | config CROSS_COMPILE | |
49 | string "Cross-compiler tool prefix" | |
50 | help | |
51 | Same as running 'make CROSS_COMPILE=prefix-' but stored for | |
52 | default make runs in this kernel build directory. You don't | |
53 | need to set this unless you want the configured kernel build | |
54 | directory to select the cross-compiler automatically. | |
55 | ||
56 | config COMPILE_TEST | |
57 | bool "Compile also drivers which will not load" | |
58 | default n | |
59 | help | |
60 | Some drivers can be compiled on a different platform than they are | |
61 | intended to be run on. Despite they cannot be loaded there (or even | |
62 | when they load they cannot be used due to missing HW support), | |
63 | developers still, opposing to distributors, might want to build such | |
64 | drivers to compile-test them. | |
65 | ||
66 | If you are a developer and want to build everything available, say Y | |
67 | here. If you are a user/distributor, say N here to exclude useless | |
68 | drivers to be distributed. | |
69 | ||
70 | config LOCALVERSION | |
71 | string "Local version - append to kernel release" | |
72 | help | |
73 | Append an extra string to the end of your kernel version. | |
74 | This will show up when you type uname, for example. | |
75 | The string you set here will be appended after the contents of | |
76 | any files with a filename matching localversion* in your | |
77 | object and source tree, in that order. Your total string can | |
78 | be a maximum of 64 characters. | |
79 | ||
80 | config LOCALVERSION_AUTO | |
81 | bool "Automatically append version information to the version string" | |
82 | default y | |
83 | help | |
84 | This will try to automatically determine if the current tree is a | |
85 | release tree by looking for git tags that belong to the current | |
86 | top of tree revision. | |
87 | ||
88 | A string of the format -gxxxxxxxx will be added to the localversion | |
89 | if a git-based tree is found. The string generated by this will be | |
90 | appended after any matching localversion* files, and after the value | |
91 | set in CONFIG_LOCALVERSION. | |
92 | ||
93 | (The actual string used here is the first eight characters produced | |
94 | by running the command: | |
95 | ||
96 | $ git rev-parse --verify HEAD | |
97 | ||
98 | which is done within the script "scripts/setlocalversion".) | |
99 | ||
100 | config HAVE_KERNEL_GZIP | |
101 | bool | |
102 | ||
103 | config HAVE_KERNEL_BZIP2 | |
104 | bool | |
105 | ||
106 | config HAVE_KERNEL_LZMA | |
107 | bool | |
108 | ||
109 | config HAVE_KERNEL_XZ | |
110 | bool | |
111 | ||
112 | config HAVE_KERNEL_LZO | |
113 | bool | |
114 | ||
115 | config HAVE_KERNEL_LZ4 | |
116 | bool | |
117 | ||
118 | choice | |
119 | prompt "Kernel compression mode" | |
120 | default KERNEL_GZIP | |
121 | depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 | |
122 | help | |
123 | The linux kernel is a kind of self-extracting executable. | |
124 | Several compression algorithms are available, which differ | |
125 | in efficiency, compression and decompression speed. | |
126 | Compression speed is only relevant when building a kernel. | |
127 | Decompression speed is relevant at each boot. | |
128 | ||
129 | If you have any problems with bzip2 or lzma compressed | |
130 | kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older | |
131 | version of this functionality (bzip2 only), for 2.4, was | |
132 | supplied by Christian Ludwig) | |
133 | ||
134 | High compression options are mostly useful for users, who | |
135 | are low on disk space (embedded systems), but for whom ram | |
136 | size matters less. | |
137 | ||
138 | If in doubt, select 'gzip' | |
139 | ||
140 | config KERNEL_GZIP | |
141 | bool "Gzip" | |
142 | depends on HAVE_KERNEL_GZIP | |
143 | help | |
144 | The old and tried gzip compression. It provides a good balance | |
145 | between compression ratio and decompression speed. | |
146 | ||
147 | config KERNEL_BZIP2 | |
148 | bool "Bzip2" | |
149 | depends on HAVE_KERNEL_BZIP2 | |
150 | help | |
151 | Its compression ratio and speed is intermediate. | |
152 | Decompression speed is slowest among the choices. The kernel | |
153 | size is about 10% smaller with bzip2, in comparison to gzip. | |
154 | Bzip2 uses a large amount of memory. For modern kernels you | |
155 | will need at least 8MB RAM or more for booting. | |
156 | ||
157 | config KERNEL_LZMA | |
158 | bool "LZMA" | |
159 | depends on HAVE_KERNEL_LZMA | |
160 | help | |
161 | This compression algorithm's ratio is best. Decompression speed | |
162 | is between gzip and bzip2. Compression is slowest. | |
163 | The kernel size is about 33% smaller with LZMA in comparison to gzip. | |
164 | ||
165 | config KERNEL_XZ | |
166 | bool "XZ" | |
167 | depends on HAVE_KERNEL_XZ | |
168 | help | |
169 | XZ uses the LZMA2 algorithm and instruction set specific | |
170 | BCJ filters which can improve compression ratio of executable | |
171 | code. The size of the kernel is about 30% smaller with XZ in | |
172 | comparison to gzip. On architectures for which there is a BCJ | |
173 | filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ | |
174 | will create a few percent smaller kernel than plain LZMA. | |
175 | ||
176 | The speed is about the same as with LZMA: The decompression | |
177 | speed of XZ is better than that of bzip2 but worse than gzip | |
178 | and LZO. Compression is slow. | |
179 | ||
180 | config KERNEL_LZO | |
181 | bool "LZO" | |
182 | depends on HAVE_KERNEL_LZO | |
183 | help | |
184 | Its compression ratio is the poorest among the choices. The kernel | |
185 | size is about 10% bigger than gzip; however its speed | |
186 | (both compression and decompression) is the fastest. | |
187 | ||
188 | config KERNEL_LZ4 | |
189 | bool "LZ4" | |
190 | depends on HAVE_KERNEL_LZ4 | |
191 | help | |
192 | LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding. | |
193 | A preliminary version of LZ4 de/compression tool is available at | |
194 | <https://code.google.com/p/lz4/>. | |
195 | ||
196 | Its compression ratio is worse than LZO. The size of the kernel | |
197 | is about 8% bigger than LZO. But the decompression speed is | |
198 | faster than LZO. | |
199 | ||
200 | endchoice | |
201 | ||
202 | config DEFAULT_HOSTNAME | |
203 | string "Default hostname" | |
204 | default "(none)" | |
205 | help | |
206 | This option determines the default system hostname before userspace | |
207 | calls sethostname(2). The kernel traditionally uses "(none)" here, | |
208 | but you may wish to use a different default here to make a minimal | |
209 | system more usable with less configuration. | |
210 | ||
211 | config SWAP | |
212 | bool "Support for paging of anonymous memory (swap)" | |
213 | depends on MMU && BLOCK | |
214 | default y | |
215 | help | |
216 | This option allows you to choose whether you want to have support | |
217 | for so called swap devices or swap files in your kernel that are | |
218 | used to provide more virtual memory than the actual RAM present | |
219 | in your computer. If unsure say Y. | |
220 | ||
221 | config SYSVIPC | |
222 | bool "System V IPC" | |
223 | ---help--- | |
224 | Inter Process Communication is a suite of library functions and | |
225 | system calls which let processes (running programs) synchronize and | |
226 | exchange information. It is generally considered to be a good thing, | |
227 | and some programs won't run unless you say Y here. In particular, if | |
228 | you want to run the DOS emulator dosemu under Linux (read the | |
229 | DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), | |
230 | you'll need to say Y here. | |
231 | ||
232 | You can find documentation about IPC with "info ipc" and also in | |
233 | section 6.4 of the Linux Programmer's Guide, available from | |
234 | <http://www.tldp.org/guides.html>. | |
235 | ||
236 | config SYSVIPC_SYSCTL | |
237 | bool | |
238 | depends on SYSVIPC | |
239 | depends on SYSCTL | |
240 | default y | |
241 | ||
242 | config POSIX_MQUEUE | |
243 | bool "POSIX Message Queues" | |
244 | depends on NET | |
245 | ---help--- | |
246 | POSIX variant of message queues is a part of IPC. In POSIX message | |
247 | queues every message has a priority which decides about succession | |
248 | of receiving it by a process. If you want to compile and run | |
249 | programs written e.g. for Solaris with use of its POSIX message | |
250 | queues (functions mq_*) say Y here. | |
251 | ||
252 | POSIX message queues are visible as a filesystem called 'mqueue' | |
253 | and can be mounted somewhere if you want to do filesystem | |
254 | operations on message queues. | |
255 | ||
256 | If unsure, say Y. | |
257 | ||
258 | config POSIX_MQUEUE_SYSCTL | |
259 | bool | |
260 | depends on POSIX_MQUEUE | |
261 | depends on SYSCTL | |
262 | default y | |
263 | ||
264 | config CROSS_MEMORY_ATTACH | |
265 | bool "Enable process_vm_readv/writev syscalls" | |
266 | depends on MMU | |
267 | default y | |
268 | help | |
269 | Enabling this option adds the system calls process_vm_readv and | |
270 | process_vm_writev which allow a process with the correct privileges | |
271 | to directly read from or write to another process' address space. | |
272 | See the man page for more details. | |
273 | ||
274 | config FHANDLE | |
275 | bool "open by fhandle syscalls" | |
276 | select EXPORTFS | |
277 | help | |
278 | If you say Y here, a user level program will be able to map | |
279 | file names to handle and then later use the handle for | |
280 | different file system operations. This is useful in implementing | |
281 | userspace file servers, which now track files using handles instead | |
282 | of names. The handle would remain the same even if file names | |
283 | get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) | |
284 | syscalls. | |
285 | ||
286 | config USELIB | |
287 | bool "uselib syscall" | |
288 | default y | |
289 | help | |
290 | This option enables the uselib syscall, a system call used in the | |
291 | dynamic linker from libc5 and earlier. glibc does not use this | |
292 | system call. If you intend to run programs built on libc5 or | |
293 | earlier, you may need to enable this syscall. Current systems | |
294 | running glibc can safely disable this. | |
295 | ||
296 | config AUDIT | |
297 | bool "Auditing support" | |
298 | depends on NET | |
299 | help | |
300 | Enable auditing infrastructure that can be used with another | |
301 | kernel subsystem, such as SELinux (which requires this for | |
302 | logging of avc messages output). Does not do system-call | |
303 | auditing without CONFIG_AUDITSYSCALL. | |
304 | ||
305 | config HAVE_ARCH_AUDITSYSCALL | |
306 | bool | |
307 | ||
308 | config AUDITSYSCALL | |
309 | bool "Enable system-call auditing support" | |
310 | depends on AUDIT && HAVE_ARCH_AUDITSYSCALL | |
311 | default y if SECURITY_SELINUX | |
312 | help | |
313 | Enable low-overhead system-call auditing infrastructure that | |
314 | can be used independently or with another kernel subsystem, | |
315 | such as SELinux. | |
316 | ||
317 | config AUDIT_WATCH | |
318 | def_bool y | |
319 | depends on AUDITSYSCALL | |
320 | select FSNOTIFY | |
321 | ||
322 | config AUDIT_TREE | |
323 | def_bool y | |
324 | depends on AUDITSYSCALL | |
325 | select FSNOTIFY | |
326 | ||
327 | source "kernel/irq/Kconfig" | |
328 | source "kernel/time/Kconfig" | |
329 | ||
330 | menu "CPU/Task time and stats accounting" | |
331 | ||
332 | config VIRT_CPU_ACCOUNTING | |
333 | bool | |
334 | ||
335 | choice | |
336 | prompt "Cputime accounting" | |
337 | default TICK_CPU_ACCOUNTING if !PPC64 | |
338 | default VIRT_CPU_ACCOUNTING_NATIVE if PPC64 | |
339 | ||
340 | # Kind of a stub config for the pure tick based cputime accounting | |
341 | config TICK_CPU_ACCOUNTING | |
342 | bool "Simple tick based cputime accounting" | |
343 | depends on !S390 && !NO_HZ_FULL | |
344 | help | |
345 | This is the basic tick based cputime accounting that maintains | |
346 | statistics about user, system and idle time spent on per jiffies | |
347 | granularity. | |
348 | ||
349 | If unsure, say Y. | |
350 | ||
351 | config VIRT_CPU_ACCOUNTING_NATIVE | |
352 | bool "Deterministic task and CPU time accounting" | |
353 | depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL | |
354 | select VIRT_CPU_ACCOUNTING | |
355 | help | |
356 | Select this option to enable more accurate task and CPU time | |
357 | accounting. This is done by reading a CPU counter on each | |
358 | kernel entry and exit and on transitions within the kernel | |
359 | between system, softirq and hardirq state, so there is a | |
360 | small performance impact. In the case of s390 or IBM POWER > 5, | |
361 | this also enables accounting of stolen time on logically-partitioned | |
362 | systems. | |
363 | ||
364 | config VIRT_CPU_ACCOUNTING_GEN | |
365 | bool "Full dynticks CPU time accounting" | |
366 | depends on HAVE_CONTEXT_TRACKING | |
367 | depends on HAVE_VIRT_CPU_ACCOUNTING_GEN | |
368 | select VIRT_CPU_ACCOUNTING | |
369 | select CONTEXT_TRACKING | |
370 | help | |
371 | Select this option to enable task and CPU time accounting on full | |
372 | dynticks systems. This accounting is implemented by watching every | |
373 | kernel-user boundaries using the context tracking subsystem. | |
374 | The accounting is thus performed at the expense of some significant | |
375 | overhead. | |
376 | ||
377 | For now this is only useful if you are working on the full | |
378 | dynticks subsystem development. | |
379 | ||
380 | If unsure, say N. | |
381 | ||
382 | config IRQ_TIME_ACCOUNTING | |
383 | bool "Fine granularity task level IRQ time accounting" | |
384 | depends on HAVE_IRQ_TIME_ACCOUNTING && !NO_HZ_FULL | |
385 | help | |
386 | Select this option to enable fine granularity task irq time | |
387 | accounting. This is done by reading a timestamp on each | |
388 | transitions between softirq and hardirq state, so there can be a | |
389 | small performance impact. | |
390 | ||
391 | If in doubt, say N here. | |
392 | ||
393 | endchoice | |
394 | ||
395 | config BSD_PROCESS_ACCT | |
396 | bool "BSD Process Accounting" | |
397 | depends on MULTIUSER | |
398 | help | |
399 | If you say Y here, a user level program will be able to instruct the | |
400 | kernel (via a special system call) to write process accounting | |
401 | information to a file: whenever a process exits, information about | |
402 | that process will be appended to the file by the kernel. The | |
403 | information includes things such as creation time, owning user, | |
404 | command name, memory usage, controlling terminal etc. (the complete | |
405 | list is in the struct acct in <file:include/linux/acct.h>). It is | |
406 | up to the user level program to do useful things with this | |
407 | information. This is generally a good idea, so say Y. | |
408 | ||
409 | config BSD_PROCESS_ACCT_V3 | |
410 | bool "BSD Process Accounting version 3 file format" | |
411 | depends on BSD_PROCESS_ACCT | |
412 | default n | |
413 | help | |
414 | If you say Y here, the process accounting information is written | |
415 | in a new file format that also logs the process IDs of each | |
416 | process and it's parent. Note that this file format is incompatible | |
417 | with previous v0/v1/v2 file formats, so you will need updated tools | |
418 | for processing it. A preliminary version of these tools is available | |
419 | at <http://www.gnu.org/software/acct/>. | |
420 | ||
421 | config TASKSTATS | |
422 | bool "Export task/process statistics through netlink" | |
423 | depends on NET | |
424 | depends on MULTIUSER | |
425 | default n | |
426 | help | |
427 | Export selected statistics for tasks/processes through the | |
428 | generic netlink interface. Unlike BSD process accounting, the | |
429 | statistics are available during the lifetime of tasks/processes as | |
430 | responses to commands. Like BSD accounting, they are sent to user | |
431 | space on task exit. | |
432 | ||
433 | Say N if unsure. | |
434 | ||
435 | config TASK_DELAY_ACCT | |
436 | bool "Enable per-task delay accounting" | |
437 | depends on TASKSTATS | |
438 | select SCHED_INFO | |
439 | help | |
440 | Collect information on time spent by a task waiting for system | |
441 | resources like cpu, synchronous block I/O completion and swapping | |
442 | in pages. Such statistics can help in setting a task's priorities | |
443 | relative to other tasks for cpu, io, rss limits etc. | |
444 | ||
445 | Say N if unsure. | |
446 | ||
447 | config TASK_XACCT | |
448 | bool "Enable extended accounting over taskstats" | |
449 | depends on TASKSTATS | |
450 | help | |
451 | Collect extended task accounting data and send the data | |
452 | to userland for processing over the taskstats interface. | |
453 | ||
454 | Say N if unsure. | |
455 | ||
456 | config TASK_IO_ACCOUNTING | |
457 | bool "Enable per-task storage I/O accounting" | |
458 | depends on TASK_XACCT | |
459 | help | |
460 | Collect information on the number of bytes of storage I/O which this | |
461 | task has caused. | |
462 | ||
463 | Say N if unsure. | |
464 | ||
465 | endmenu # "CPU/Task time and stats accounting" | |
466 | ||
467 | menu "RCU Subsystem" | |
468 | ||
469 | config TREE_RCU | |
470 | bool | |
471 | default y if !PREEMPT && SMP | |
472 | help | |
473 | This option selects the RCU implementation that is | |
474 | designed for very large SMP system with hundreds or | |
475 | thousands of CPUs. It also scales down nicely to | |
476 | smaller systems. | |
477 | ||
478 | config PREEMPT_RCU | |
479 | bool | |
480 | default y if PREEMPT | |
481 | help | |
482 | This option selects the RCU implementation that is | |
483 | designed for very large SMP systems with hundreds or | |
484 | thousands of CPUs, but for which real-time response | |
485 | is also required. It also scales down nicely to | |
486 | smaller systems. | |
487 | ||
488 | Select this option if you are unsure. | |
489 | ||
490 | config TINY_RCU | |
491 | bool | |
492 | default y if !PREEMPT && !SMP | |
493 | help | |
494 | This option selects the RCU implementation that is | |
495 | designed for UP systems from which real-time response | |
496 | is not required. This option greatly reduces the | |
497 | memory footprint of RCU. | |
498 | ||
499 | config RCU_EXPERT | |
500 | bool "Make expert-level adjustments to RCU configuration" | |
501 | default n | |
502 | help | |
503 | This option needs to be enabled if you wish to make | |
504 | expert-level adjustments to RCU configuration. By default, | |
505 | no such adjustments can be made, which has the often-beneficial | |
506 | side-effect of preventing "make oldconfig" from asking you all | |
507 | sorts of detailed questions about how you would like numerous | |
508 | obscure RCU options to be set up. | |
509 | ||
510 | Say Y if you need to make expert-level adjustments to RCU. | |
511 | ||
512 | Say N if you are unsure. | |
513 | ||
514 | config SRCU | |
515 | bool | |
516 | help | |
517 | This option selects the sleepable version of RCU. This version | |
518 | permits arbitrary sleeping or blocking within RCU read-side critical | |
519 | sections. | |
520 | ||
521 | config TASKS_RCU | |
522 | bool | |
523 | default n | |
524 | select SRCU | |
525 | help | |
526 | This option enables a task-based RCU implementation that uses | |
527 | only voluntary context switch (not preemption!), idle, and | |
528 | user-mode execution as quiescent states. | |
529 | ||
530 | config RCU_STALL_COMMON | |
531 | def_bool ( TREE_RCU || PREEMPT_RCU || RCU_TRACE ) | |
532 | help | |
533 | This option enables RCU CPU stall code that is common between | |
534 | the TINY and TREE variants of RCU. The purpose is to allow | |
535 | the tiny variants to disable RCU CPU stall warnings, while | |
536 | making these warnings mandatory for the tree variants. | |
537 | ||
538 | config CONTEXT_TRACKING | |
539 | bool | |
540 | ||
541 | config RCU_USER_QS | |
542 | bool | |
543 | help | |
544 | This option sets hooks on kernel / userspace boundaries and | |
545 | puts RCU in extended quiescent state when the CPU runs in | |
546 | userspace. It means that when a CPU runs in userspace, it is | |
547 | excluded from the global RCU state machine and thus doesn't | |
548 | try to keep the timer tick on for RCU. | |
549 | ||
550 | config CONTEXT_TRACKING_FORCE | |
551 | bool "Force context tracking" | |
552 | depends on CONTEXT_TRACKING | |
553 | default y if !NO_HZ_FULL | |
554 | help | |
555 | The major pre-requirement for full dynticks to work is to | |
556 | support the context tracking subsystem. But there are also | |
557 | other dependencies to provide in order to make the full | |
558 | dynticks working. | |
559 | ||
560 | This option stands for testing when an arch implements the | |
561 | context tracking backend but doesn't yet fullfill all the | |
562 | requirements to make the full dynticks feature working. | |
563 | Without the full dynticks, there is no way to test the support | |
564 | for context tracking and the subsystems that rely on it: RCU | |
565 | userspace extended quiescent state and tickless cputime | |
566 | accounting. This option copes with the absence of the full | |
567 | dynticks subsystem by forcing the context tracking on all | |
568 | CPUs in the system. | |
569 | ||
570 | Say Y only if you're working on the development of an | |
571 | architecture backend for the context tracking. | |
572 | ||
573 | Say N otherwise, this option brings an overhead that you | |
574 | don't want in production. | |
575 | ||
576 | ||
577 | config RCU_FANOUT | |
578 | int "Tree-based hierarchical RCU fanout value" | |
579 | range 2 64 if 64BIT | |
580 | range 2 32 if !64BIT | |
581 | depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT | |
582 | default 64 if 64BIT | |
583 | default 32 if !64BIT | |
584 | help | |
585 | This option controls the fanout of hierarchical implementations | |
586 | of RCU, allowing RCU to work efficiently on machines with | |
587 | large numbers of CPUs. This value must be at least the fourth | |
588 | root of NR_CPUS, which allows NR_CPUS to be insanely large. | |
589 | The default value of RCU_FANOUT should be used for production | |
590 | systems, but if you are stress-testing the RCU implementation | |
591 | itself, small RCU_FANOUT values allow you to test large-system | |
592 | code paths on small(er) systems. | |
593 | ||
594 | Select a specific number if testing RCU itself. | |
595 | Take the default if unsure. | |
596 | ||
597 | config RCU_FANOUT_LEAF | |
598 | int "Tree-based hierarchical RCU leaf-level fanout value" | |
599 | range 2 64 if 64BIT | |
600 | range 2 32 if !64BIT | |
601 | depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT | |
602 | default 16 | |
603 | help | |
604 | This option controls the leaf-level fanout of hierarchical | |
605 | implementations of RCU, and allows trading off cache misses | |
606 | against lock contention. Systems that synchronize their | |
607 | scheduling-clock interrupts for energy-efficiency reasons will | |
608 | want the default because the smaller leaf-level fanout keeps | |
609 | lock contention levels acceptably low. Very large systems | |
610 | (hundreds or thousands of CPUs) will instead want to set this | |
611 | value to the maximum value possible in order to reduce the | |
612 | number of cache misses incurred during RCU's grace-period | |
613 | initialization. These systems tend to run CPU-bound, and thus | |
614 | are not helped by synchronized interrupts, and thus tend to | |
615 | skew them, which reduces lock contention enough that large | |
616 | leaf-level fanouts work well. | |
617 | ||
618 | Select a specific number if testing RCU itself. | |
619 | ||
620 | Select the maximum permissible value for large systems. | |
621 | ||
622 | Take the default if unsure. | |
623 | ||
624 | config RCU_FAST_NO_HZ | |
625 | bool "Accelerate last non-dyntick-idle CPU's grace periods" | |
626 | depends on NO_HZ_COMMON && SMP && RCU_EXPERT | |
627 | default n | |
628 | help | |
629 | This option permits CPUs to enter dynticks-idle state even if | |
630 | they have RCU callbacks queued, and prevents RCU from waking | |
631 | these CPUs up more than roughly once every four jiffies (by | |
632 | default, you can adjust this using the rcutree.rcu_idle_gp_delay | |
633 | parameter), thus improving energy efficiency. On the other | |
634 | hand, this option increases the duration of RCU grace periods, | |
635 | for example, slowing down synchronize_rcu(). | |
636 | ||
637 | Say Y if energy efficiency is critically important, and you | |
638 | don't care about increased grace-period durations. | |
639 | ||
640 | Say N if you are unsure. | |
641 | ||
642 | config TREE_RCU_TRACE | |
643 | def_bool RCU_TRACE && ( TREE_RCU || PREEMPT_RCU ) | |
644 | select DEBUG_FS | |
645 | help | |
646 | This option provides tracing for the TREE_RCU and | |
647 | PREEMPT_RCU implementations, permitting Makefile to | |
648 | trivially select kernel/rcutree_trace.c. | |
649 | ||
650 | config RCU_BOOST | |
651 | bool "Enable RCU priority boosting" | |
652 | depends on RT_MUTEXES && PREEMPT_RCU && RCU_EXPERT | |
653 | default n | |
654 | help | |
655 | This option boosts the priority of preempted RCU readers that | |
656 | block the current preemptible RCU grace period for too long. | |
657 | This option also prevents heavy loads from blocking RCU | |
658 | callback invocation for all flavors of RCU. | |
659 | ||
660 | Say Y here if you are working with real-time apps or heavy loads | |
661 | Say N here if you are unsure. | |
662 | ||
663 | config RCU_KTHREAD_PRIO | |
664 | int "Real-time priority to use for RCU worker threads" | |
665 | range 1 99 if RCU_BOOST | |
666 | range 0 99 if !RCU_BOOST | |
667 | default 1 if RCU_BOOST | |
668 | default 0 if !RCU_BOOST | |
669 | depends on RCU_EXPERT | |
670 | help | |
671 | This option specifies the SCHED_FIFO priority value that will be | |
672 | assigned to the rcuc/n and rcub/n threads and is also the value | |
673 | used for RCU_BOOST (if enabled). If you are working with a | |
674 | real-time application that has one or more CPU-bound threads | |
675 | running at a real-time priority level, you should set | |
676 | RCU_KTHREAD_PRIO to a priority higher than the highest-priority | |
677 | real-time CPU-bound application thread. The default RCU_KTHREAD_PRIO | |
678 | value of 1 is appropriate in the common case, which is real-time | |
679 | applications that do not have any CPU-bound threads. | |
680 | ||
681 | Some real-time applications might not have a single real-time | |
682 | thread that saturates a given CPU, but instead might have | |
683 | multiple real-time threads that, taken together, fully utilize | |
684 | that CPU. In this case, you should set RCU_KTHREAD_PRIO to | |
685 | a priority higher than the lowest-priority thread that is | |
686 | conspiring to prevent the CPU from running any non-real-time | |
687 | tasks. For example, if one thread at priority 10 and another | |
688 | thread at priority 5 are between themselves fully consuming | |
689 | the CPU time on a given CPU, then RCU_KTHREAD_PRIO should be | |
690 | set to priority 6 or higher. | |
691 | ||
692 | Specify the real-time priority, or take the default if unsure. | |
693 | ||
694 | config RCU_BOOST_DELAY | |
695 | int "Milliseconds to delay boosting after RCU grace-period start" | |
696 | range 0 3000 | |
697 | depends on RCU_BOOST | |
698 | default 500 | |
699 | help | |
700 | This option specifies the time to wait after the beginning of | |
701 | a given grace period before priority-boosting preempted RCU | |
702 | readers blocking that grace period. Note that any RCU reader | |
703 | blocking an expedited RCU grace period is boosted immediately. | |
704 | ||
705 | Accept the default if unsure. | |
706 | ||
707 | config RCU_NOCB_CPU | |
708 | bool "Offload RCU callback processing from boot-selected CPUs" | |
709 | depends on TREE_RCU || PREEMPT_RCU | |
710 | default n | |
711 | help | |
712 | Use this option to reduce OS jitter for aggressive HPC or | |
713 | real-time workloads. It can also be used to offload RCU | |
714 | callback invocation to energy-efficient CPUs in battery-powered | |
715 | asymmetric multiprocessors. | |
716 | ||
717 | This option offloads callback invocation from the set of | |
718 | CPUs specified at boot time by the rcu_nocbs parameter. | |
719 | For each such CPU, a kthread ("rcuox/N") will be created to | |
720 | invoke callbacks, where the "N" is the CPU being offloaded, | |
721 | and where the "x" is "b" for RCU-bh, "p" for RCU-preempt, and | |
722 | "s" for RCU-sched. Nothing prevents this kthread from running | |
723 | on the specified CPUs, but (1) the kthreads may be preempted | |
724 | between each callback, and (2) affinity or cgroups can be used | |
725 | to force the kthreads to run on whatever set of CPUs is desired. | |
726 | ||
727 | Say Y here if you want to help to debug reduced OS jitter. | |
728 | Say N here if you are unsure. | |
729 | ||
730 | choice | |
731 | prompt "Build-forced no-CBs CPUs" | |
732 | default RCU_NOCB_CPU_NONE | |
733 | depends on RCU_NOCB_CPU | |
734 | help | |
735 | This option allows no-CBs CPUs (whose RCU callbacks are invoked | |
736 | from kthreads rather than from softirq context) to be specified | |
737 | at build time. Additional no-CBs CPUs may be specified by | |
738 | the rcu_nocbs= boot parameter. | |
739 | ||
740 | config RCU_NOCB_CPU_NONE | |
741 | bool "No build_forced no-CBs CPUs" | |
742 | help | |
743 | This option does not force any of the CPUs to be no-CBs CPUs. | |
744 | Only CPUs designated by the rcu_nocbs= boot parameter will be | |
745 | no-CBs CPUs, whose RCU callbacks will be invoked by per-CPU | |
746 | kthreads whose names begin with "rcuo". All other CPUs will | |
747 | invoke their own RCU callbacks in softirq context. | |
748 | ||
749 | Select this option if you want to choose no-CBs CPUs at | |
750 | boot time, for example, to allow testing of different no-CBs | |
751 | configurations without having to rebuild the kernel each time. | |
752 | ||
753 | config RCU_NOCB_CPU_ZERO | |
754 | bool "CPU 0 is a build_forced no-CBs CPU" | |
755 | help | |
756 | This option forces CPU 0 to be a no-CBs CPU, so that its RCU | |
757 | callbacks are invoked by a per-CPU kthread whose name begins | |
758 | with "rcuo". Additional CPUs may be designated as no-CBs | |
759 | CPUs using the rcu_nocbs= boot parameter will be no-CBs CPUs. | |
760 | All other CPUs will invoke their own RCU callbacks in softirq | |
761 | context. | |
762 | ||
763 | Select this if CPU 0 needs to be a no-CBs CPU for real-time | |
764 | or energy-efficiency reasons, but the real reason it exists | |
765 | is to ensure that randconfig testing covers mixed systems. | |
766 | ||
767 | config RCU_NOCB_CPU_ALL | |
768 | bool "All CPUs are build_forced no-CBs CPUs" | |
769 | help | |
770 | This option forces all CPUs to be no-CBs CPUs. The rcu_nocbs= | |
771 | boot parameter will be ignored. All CPUs' RCU callbacks will | |
772 | be executed in the context of per-CPU rcuo kthreads created for | |
773 | this purpose. Assuming that the kthreads whose names start with | |
774 | "rcuo" are bound to "housekeeping" CPUs, this reduces OS jitter | |
775 | on the remaining CPUs, but might decrease memory locality during | |
776 | RCU-callback invocation, thus potentially degrading throughput. | |
777 | ||
778 | Select this if all CPUs need to be no-CBs CPUs for real-time | |
779 | or energy-efficiency reasons. | |
780 | ||
781 | endchoice | |
782 | ||
783 | config RCU_EXPEDITE_BOOT | |
784 | bool | |
785 | default n | |
786 | help | |
787 | This option enables expedited grace periods at boot time, | |
788 | as if rcu_expedite_gp() had been invoked early in boot. | |
789 | The corresponding rcu_unexpedite_gp() is invoked from | |
790 | rcu_end_inkernel_boot(), which is intended to be invoked | |
791 | at the end of the kernel-only boot sequence, just before | |
792 | init is exec'ed. | |
793 | ||
794 | Accept the default if unsure. | |
795 | ||
796 | endmenu # "RCU Subsystem" | |
797 | ||
798 | config BUILD_BIN2C | |
799 | bool | |
800 | default n | |
801 | ||
802 | config IKCONFIG | |
803 | tristate "Kernel .config support" | |
804 | select BUILD_BIN2C | |
805 | ---help--- | |
806 | This option enables the complete Linux kernel ".config" file | |
807 | contents to be saved in the kernel. It provides documentation | |
808 | of which kernel options are used in a running kernel or in an | |
809 | on-disk kernel. This information can be extracted from the kernel | |
810 | image file with the script scripts/extract-ikconfig and used as | |
811 | input to rebuild the current kernel or to build another kernel. | |
812 | It can also be extracted from a running kernel by reading | |
813 | /proc/config.gz if enabled (below). | |
814 | ||
815 | config IKCONFIG_PROC | |
816 | bool "Enable access to .config through /proc/config.gz" | |
817 | depends on IKCONFIG && PROC_FS | |
818 | ---help--- | |
819 | This option enables access to the kernel configuration file | |
820 | through /proc/config.gz. | |
821 | ||
822 | config LOG_BUF_SHIFT | |
823 | int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" | |
824 | range 12 25 | |
825 | default 17 | |
826 | depends on PRINTK | |
827 | help | |
828 | Select the minimal kernel log buffer size as a power of 2. | |
829 | The final size is affected by LOG_CPU_MAX_BUF_SHIFT config | |
830 | parameter, see below. Any higher size also might be forced | |
831 | by "log_buf_len" boot parameter. | |
832 | ||
833 | Examples: | |
834 | 17 => 128 KB | |
835 | 16 => 64 KB | |
836 | 15 => 32 KB | |
837 | 14 => 16 KB | |
838 | 13 => 8 KB | |
839 | 12 => 4 KB | |
840 | ||
841 | config LOG_CPU_MAX_BUF_SHIFT | |
842 | int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" | |
843 | depends on SMP | |
844 | range 0 21 | |
845 | default 12 if !BASE_SMALL | |
846 | default 0 if BASE_SMALL | |
847 | depends on PRINTK | |
848 | help | |
849 | This option allows to increase the default ring buffer size | |
850 | according to the number of CPUs. The value defines the contribution | |
851 | of each CPU as a power of 2. The used space is typically only few | |
852 | lines however it might be much more when problems are reported, | |
853 | e.g. backtraces. | |
854 | ||
855 | The increased size means that a new buffer has to be allocated and | |
856 | the original static one is unused. It makes sense only on systems | |
857 | with more CPUs. Therefore this value is used only when the sum of | |
858 | contributions is greater than the half of the default kernel ring | |
859 | buffer as defined by LOG_BUF_SHIFT. The default values are set | |
860 | so that more than 64 CPUs are needed to trigger the allocation. | |
861 | ||
862 | Also this option is ignored when "log_buf_len" kernel parameter is | |
863 | used as it forces an exact (power of two) size of the ring buffer. | |
864 | ||
865 | The number of possible CPUs is used for this computation ignoring | |
866 | hotplugging making the compuation optimal for the the worst case | |
867 | scenerio while allowing a simple algorithm to be used from bootup. | |
868 | ||
869 | Examples shift values and their meaning: | |
870 | 17 => 128 KB for each CPU | |
871 | 16 => 64 KB for each CPU | |
872 | 15 => 32 KB for each CPU | |
873 | 14 => 16 KB for each CPU | |
874 | 13 => 8 KB for each CPU | |
875 | 12 => 4 KB for each CPU | |
876 | ||
877 | # | |
878 | # Architectures with an unreliable sched_clock() should select this: | |
879 | # | |
880 | config HAVE_UNSTABLE_SCHED_CLOCK | |
881 | bool | |
882 | ||
883 | config GENERIC_SCHED_CLOCK | |
884 | bool | |
885 | ||
886 | # | |
887 | # For architectures that want to enable the support for NUMA-affine scheduler | |
888 | # balancing logic: | |
889 | # | |
890 | config ARCH_SUPPORTS_NUMA_BALANCING | |
891 | bool | |
892 | ||
893 | # | |
894 | # For architectures that know their GCC __int128 support is sound | |
895 | # | |
896 | config ARCH_SUPPORTS_INT128 | |
897 | bool | |
898 | ||
899 | # For architectures that (ab)use NUMA to represent different memory regions | |
900 | # all cpu-local but of different latencies, such as SuperH. | |
901 | # | |
902 | config ARCH_WANT_NUMA_VARIABLE_LOCALITY | |
903 | bool | |
904 | ||
905 | config NUMA_BALANCING | |
906 | bool "Memory placement aware NUMA scheduler" | |
907 | depends on ARCH_SUPPORTS_NUMA_BALANCING | |
908 | depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY | |
909 | depends on SMP && NUMA && MIGRATION | |
910 | help | |
911 | This option adds support for automatic NUMA aware memory/task placement. | |
912 | The mechanism is quite primitive and is based on migrating memory when | |
913 | it has references to the node the task is running on. | |
914 | ||
915 | This system will be inactive on UMA systems. | |
916 | ||
917 | config NUMA_BALANCING_DEFAULT_ENABLED | |
918 | bool "Automatically enable NUMA aware memory/task placement" | |
919 | default y | |
920 | depends on NUMA_BALANCING | |
921 | help | |
922 | If set, automatic NUMA balancing will be enabled if running on a NUMA | |
923 | machine. | |
924 | ||
925 | menuconfig CGROUPS | |
926 | bool "Control Group support" | |
927 | select KERNFS | |
928 | select PERCPU_RWSEM | |
929 | help | |
930 | This option adds support for grouping sets of processes together, for | |
931 | use with process control subsystems such as Cpusets, CFS, memory | |
932 | controls or device isolation. | |
933 | See | |
934 | - Documentation/scheduler/sched-design-CFS.txt (CFS) | |
935 | - Documentation/cgroups/ (features for grouping, isolation | |
936 | and resource control) | |
937 | ||
938 | Say N if unsure. | |
939 | ||
940 | if CGROUPS | |
941 | ||
942 | config CGROUP_DEBUG | |
943 | bool "Example debug cgroup subsystem" | |
944 | default n | |
945 | help | |
946 | This option enables a simple cgroup subsystem that | |
947 | exports useful debugging information about the cgroups | |
948 | framework. | |
949 | ||
950 | Say N if unsure. | |
951 | ||
952 | config CGROUP_FREEZER | |
953 | bool "Freezer cgroup subsystem" | |
954 | help | |
955 | Provides a way to freeze and unfreeze all tasks in a | |
956 | cgroup. | |
957 | ||
958 | config CGROUP_DEVICE | |
959 | bool "Device controller for cgroups" | |
960 | help | |
961 | Provides a cgroup implementing whitelists for devices which | |
962 | a process in the cgroup can mknod or open. | |
963 | ||
964 | config CPUSETS | |
965 | bool "Cpuset support" | |
966 | help | |
967 | This option will let you create and manage CPUSETs which | |
968 | allow dynamically partitioning a system into sets of CPUs and | |
969 | Memory Nodes and assigning tasks to run only within those sets. | |
970 | This is primarily useful on large SMP or NUMA systems. | |
971 | ||
972 | Say N if unsure. | |
973 | ||
974 | config PROC_PID_CPUSET | |
975 | bool "Include legacy /proc/<pid>/cpuset file" | |
976 | depends on CPUSETS | |
977 | default y | |
978 | ||
979 | config CGROUP_CPUACCT | |
980 | bool "Simple CPU accounting cgroup subsystem" | |
981 | help | |
982 | Provides a simple Resource Controller for monitoring the | |
983 | total CPU consumed by the tasks in a cgroup. | |
984 | ||
985 | config PAGE_COUNTER | |
986 | bool | |
987 | ||
988 | config MEMCG | |
989 | bool "Memory Resource Controller for Control Groups" | |
990 | select PAGE_COUNTER | |
991 | select EVENTFD | |
992 | help | |
993 | Provides a memory resource controller that manages both anonymous | |
994 | memory and page cache. (See Documentation/cgroups/memory.txt) | |
995 | ||
996 | config MEMCG_SWAP | |
997 | bool "Memory Resource Controller Swap Extension" | |
998 | depends on MEMCG && SWAP | |
999 | help | |
1000 | Add swap management feature to memory resource controller. When you | |
1001 | enable this, you can limit mem+swap usage per cgroup. In other words, | |
1002 | when you disable this, memory resource controller has no cares to | |
1003 | usage of swap...a process can exhaust all of the swap. This extension | |
1004 | is useful when you want to avoid exhaustion swap but this itself | |
1005 | adds more overheads and consumes memory for remembering information. | |
1006 | Especially if you use 32bit system or small memory system, please | |
1007 | be careful about enabling this. When memory resource controller | |
1008 | is disabled by boot option, this will be automatically disabled and | |
1009 | there will be no overhead from this. Even when you set this config=y, | |
1010 | if boot option "swapaccount=0" is set, swap will not be accounted. | |
1011 | Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page | |
1012 | size is 4096bytes, 512k per 1Gbytes of swap. | |
1013 | config MEMCG_SWAP_ENABLED | |
1014 | bool "Memory Resource Controller Swap Extension enabled by default" | |
1015 | depends on MEMCG_SWAP | |
1016 | default y | |
1017 | help | |
1018 | Memory Resource Controller Swap Extension comes with its price in | |
1019 | a bigger memory consumption. General purpose distribution kernels | |
1020 | which want to enable the feature but keep it disabled by default | |
1021 | and let the user enable it by swapaccount=1 boot command line | |
1022 | parameter should have this option unselected. | |
1023 | For those who want to have the feature enabled by default should | |
1024 | select this option (if, for some reason, they need to disable it | |
1025 | then swapaccount=0 does the trick). | |
1026 | config MEMCG_KMEM | |
1027 | bool "Memory Resource Controller Kernel Memory accounting" | |
1028 | depends on MEMCG | |
1029 | depends on SLUB || SLAB | |
1030 | help | |
1031 | The Kernel Memory extension for Memory Resource Controller can limit | |
1032 | the amount of memory used by kernel objects in the system. Those are | |
1033 | fundamentally different from the entities handled by the standard | |
1034 | Memory Controller, which are page-based, and can be swapped. Users of | |
1035 | the kmem extension can use it to guarantee that no group of processes | |
1036 | will ever exhaust kernel resources alone. | |
1037 | ||
1038 | config CGROUP_HUGETLB | |
1039 | bool "HugeTLB Resource Controller for Control Groups" | |
1040 | depends on HUGETLB_PAGE | |
1041 | select PAGE_COUNTER | |
1042 | default n | |
1043 | help | |
1044 | Provides a cgroup Resource Controller for HugeTLB pages. | |
1045 | When you enable this, you can put a per cgroup limit on HugeTLB usage. | |
1046 | The limit is enforced during page fault. Since HugeTLB doesn't | |
1047 | support page reclaim, enforcing the limit at page fault time implies | |
1048 | that, the application will get SIGBUS signal if it tries to access | |
1049 | HugeTLB pages beyond its limit. This requires the application to know | |
1050 | beforehand how much HugeTLB pages it would require for its use. The | |
1051 | control group is tracked in the third page lru pointer. This means | |
1052 | that we cannot use the controller with huge page less than 3 pages. | |
1053 | ||
1054 | config CGROUP_PERF | |
1055 | bool "Enable perf_event per-cpu per-container group (cgroup) monitoring" | |
1056 | depends on PERF_EVENTS && CGROUPS | |
1057 | help | |
1058 | This option extends the per-cpu mode to restrict monitoring to | |
1059 | threads which belong to the cgroup specified and run on the | |
1060 | designated cpu. | |
1061 | ||
1062 | Say N if unsure. | |
1063 | ||
1064 | menuconfig CGROUP_SCHED | |
1065 | bool "Group CPU scheduler" | |
1066 | default n | |
1067 | help | |
1068 | This feature lets CPU scheduler recognize task groups and control CPU | |
1069 | bandwidth allocation to such task groups. It uses cgroups to group | |
1070 | tasks. | |
1071 | ||
1072 | if CGROUP_SCHED | |
1073 | config FAIR_GROUP_SCHED | |
1074 | bool "Group scheduling for SCHED_OTHER" | |
1075 | depends on CGROUP_SCHED | |
1076 | default CGROUP_SCHED | |
1077 | ||
1078 | config CFS_BANDWIDTH | |
1079 | bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" | |
1080 | depends on FAIR_GROUP_SCHED | |
1081 | default n | |
1082 | help | |
1083 | This option allows users to define CPU bandwidth rates (limits) for | |
1084 | tasks running within the fair group scheduler. Groups with no limit | |
1085 | set are considered to be unconstrained and will run with no | |
1086 | restriction. | |
1087 | See tip/Documentation/scheduler/sched-bwc.txt for more information. | |
1088 | ||
1089 | config RT_GROUP_SCHED | |
1090 | bool "Group scheduling for SCHED_RR/FIFO" | |
1091 | depends on CGROUP_SCHED | |
1092 | default n | |
1093 | help | |
1094 | This feature lets you explicitly allocate real CPU bandwidth | |
1095 | to task groups. If enabled, it will also make it impossible to | |
1096 | schedule realtime tasks for non-root users until you allocate | |
1097 | realtime bandwidth for them. | |
1098 | See Documentation/scheduler/sched-rt-group.txt for more information. | |
1099 | ||
1100 | endif #CGROUP_SCHED | |
1101 | ||
1102 | config BLK_CGROUP | |
1103 | bool "Block IO controller" | |
1104 | depends on BLOCK | |
1105 | default n | |
1106 | ---help--- | |
1107 | Generic block IO controller cgroup interface. This is the common | |
1108 | cgroup interface which should be used by various IO controlling | |
1109 | policies. | |
1110 | ||
1111 | Currently, CFQ IO scheduler uses it to recognize task groups and | |
1112 | control disk bandwidth allocation (proportional time slice allocation) | |
1113 | to such task groups. It is also used by bio throttling logic in | |
1114 | block layer to implement upper limit in IO rates on a device. | |
1115 | ||
1116 | This option only enables generic Block IO controller infrastructure. | |
1117 | One needs to also enable actual IO controlling logic/policy. For | |
1118 | enabling proportional weight division of disk bandwidth in CFQ, set | |
1119 | CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set | |
1120 | CONFIG_BLK_DEV_THROTTLING=y. | |
1121 | ||
1122 | See Documentation/cgroups/blkio-controller.txt for more information. | |
1123 | ||
1124 | config DEBUG_BLK_CGROUP | |
1125 | bool "Enable Block IO controller debugging" | |
1126 | depends on BLK_CGROUP | |
1127 | default n | |
1128 | ---help--- | |
1129 | Enable some debugging help. Currently it exports additional stat | |
1130 | files in a cgroup which can be useful for debugging. | |
1131 | ||
1132 | config CGROUP_WRITEBACK | |
1133 | bool | |
1134 | depends on MEMCG && BLK_CGROUP | |
1135 | default y | |
1136 | ||
1137 | endif # CGROUPS | |
1138 | ||
1139 | config CHECKPOINT_RESTORE | |
1140 | bool "Checkpoint/restore support" if EXPERT | |
1141 | select PROC_CHILDREN | |
1142 | default n | |
1143 | help | |
1144 | Enables additional kernel features in a sake of checkpoint/restore. | |
1145 | In particular it adds auxiliary prctl codes to setup process text, | |
1146 | data and heap segment sizes, and a few additional /proc filesystem | |
1147 | entries. | |
1148 | ||
1149 | If unsure, say N here. | |
1150 | ||
1151 | menuconfig NAMESPACES | |
1152 | bool "Namespaces support" if EXPERT | |
1153 | depends on MULTIUSER | |
1154 | default !EXPERT | |
1155 | help | |
1156 | Provides the way to make tasks work with different objects using | |
1157 | the same id. For example same IPC id may refer to different objects | |
1158 | or same user id or pid may refer to different tasks when used in | |
1159 | different namespaces. | |
1160 | ||
1161 | if NAMESPACES | |
1162 | ||
1163 | config UTS_NS | |
1164 | bool "UTS namespace" | |
1165 | default y | |
1166 | help | |
1167 | In this namespace tasks see different info provided with the | |
1168 | uname() system call | |
1169 | ||
1170 | config IPC_NS | |
1171 | bool "IPC namespace" | |
1172 | depends on (SYSVIPC || POSIX_MQUEUE) | |
1173 | default y | |
1174 | help | |
1175 | In this namespace tasks work with IPC ids which correspond to | |
1176 | different IPC objects in different namespaces. | |
1177 | ||
1178 | config USER_NS | |
1179 | bool "User namespace" | |
1180 | default n | |
1181 | help | |
1182 | This allows containers, i.e. vservers, to use user namespaces | |
1183 | to provide different user info for different servers. | |
1184 | ||
1185 | When user namespaces are enabled in the kernel it is | |
1186 | recommended that the MEMCG and MEMCG_KMEM options also be | |
1187 | enabled and that user-space use the memory control groups to | |
1188 | limit the amount of memory a memory unprivileged users can | |
1189 | use. | |
1190 | ||
1191 | If unsure, say N. | |
1192 | ||
1193 | config PID_NS | |
1194 | bool "PID Namespaces" | |
1195 | default y | |
1196 | help | |
1197 | Support process id namespaces. This allows having multiple | |
1198 | processes with the same pid as long as they are in different | |
1199 | pid namespaces. This is a building block of containers. | |
1200 | ||
1201 | config NET_NS | |
1202 | bool "Network namespace" | |
1203 | depends on NET | |
1204 | default y | |
1205 | help | |
1206 | Allow user space to create what appear to be multiple instances | |
1207 | of the network stack. | |
1208 | ||
1209 | endif # NAMESPACES | |
1210 | ||
1211 | config SCHED_AUTOGROUP | |
1212 | bool "Automatic process group scheduling" | |
1213 | select CGROUPS | |
1214 | select CGROUP_SCHED | |
1215 | select FAIR_GROUP_SCHED | |
1216 | help | |
1217 | This option optimizes the scheduler for common desktop workloads by | |
1218 | automatically creating and populating task groups. This separation | |
1219 | of workloads isolates aggressive CPU burners (like build jobs) from | |
1220 | desktop applications. Task group autogeneration is currently based | |
1221 | upon task session. | |
1222 | ||
1223 | config SYSFS_DEPRECATED | |
1224 | bool "Enable deprecated sysfs features to support old userspace tools" | |
1225 | depends on SYSFS | |
1226 | default n | |
1227 | help | |
1228 | This option adds code that switches the layout of the "block" class | |
1229 | devices, to not show up in /sys/class/block/, but only in | |
1230 | /sys/block/. | |
1231 | ||
1232 | This switch is only active when the sysfs.deprecated=1 boot option is | |
1233 | passed or the SYSFS_DEPRECATED_V2 option is set. | |
1234 | ||
1235 | This option allows new kernels to run on old distributions and tools, | |
1236 | which might get confused by /sys/class/block/. Since 2007/2008 all | |
1237 | major distributions and tools handle this just fine. | |
1238 | ||
1239 | Recent distributions and userspace tools after 2009/2010 depend on | |
1240 | the existence of /sys/class/block/, and will not work with this | |
1241 | option enabled. | |
1242 | ||
1243 | Only if you are using a new kernel on an old distribution, you might | |
1244 | need to say Y here. | |
1245 | ||
1246 | config SYSFS_DEPRECATED_V2 | |
1247 | bool "Enable deprecated sysfs features by default" | |
1248 | default n | |
1249 | depends on SYSFS | |
1250 | depends on SYSFS_DEPRECATED | |
1251 | help | |
1252 | Enable deprecated sysfs by default. | |
1253 | ||
1254 | See the CONFIG_SYSFS_DEPRECATED option for more details about this | |
1255 | option. | |
1256 | ||
1257 | Only if you are using a new kernel on an old distribution, you might | |
1258 | need to say Y here. Even then, odds are you would not need it | |
1259 | enabled, you can always pass the boot option if absolutely necessary. | |
1260 | ||
1261 | config RELAY | |
1262 | bool "Kernel->user space relay support (formerly relayfs)" | |
1263 | help | |
1264 | This option enables support for relay interface support in | |
1265 | certain file systems (such as debugfs). | |
1266 | It is designed to provide an efficient mechanism for tools and | |
1267 | facilities to relay large amounts of data from kernel space to | |
1268 | user space. | |
1269 | ||
1270 | If unsure, say N. | |
1271 | ||
1272 | config BLK_DEV_INITRD | |
1273 | bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" | |
1274 | depends on BROKEN || !FRV | |
1275 | help | |
1276 | The initial RAM filesystem is a ramfs which is loaded by the | |
1277 | boot loader (loadlin or lilo) and that is mounted as root | |
1278 | before the normal boot procedure. It is typically used to | |
1279 | load modules needed to mount the "real" root file system, | |
1280 | etc. See <file:Documentation/initrd.txt> for details. | |
1281 | ||
1282 | If RAM disk support (BLK_DEV_RAM) is also included, this | |
1283 | also enables initial RAM disk (initrd) support and adds | |
1284 | 15 Kbytes (more on some other architectures) to the kernel size. | |
1285 | ||
1286 | If unsure say Y. | |
1287 | ||
1288 | if BLK_DEV_INITRD | |
1289 | ||
1290 | source "usr/Kconfig" | |
1291 | ||
1292 | endif | |
1293 | ||
1294 | config CC_OPTIMIZE_FOR_SIZE | |
1295 | bool "Optimize for size" | |
1296 | help | |
1297 | Enabling this option will pass "-Os" instead of "-O2" to | |
1298 | your compiler resulting in a smaller kernel. | |
1299 | ||
1300 | If unsure, say N. | |
1301 | ||
1302 | config SYSCTL | |
1303 | bool | |
1304 | ||
1305 | config ANON_INODES | |
1306 | bool | |
1307 | ||
1308 | config HAVE_UID16 | |
1309 | bool | |
1310 | ||
1311 | config SYSCTL_EXCEPTION_TRACE | |
1312 | bool | |
1313 | help | |
1314 | Enable support for /proc/sys/debug/exception-trace. | |
1315 | ||
1316 | config SYSCTL_ARCH_UNALIGN_NO_WARN | |
1317 | bool | |
1318 | help | |
1319 | Enable support for /proc/sys/kernel/ignore-unaligned-usertrap | |
1320 | Allows arch to define/use @no_unaligned_warning to possibly warn | |
1321 | about unaligned access emulation going on under the hood. | |
1322 | ||
1323 | config SYSCTL_ARCH_UNALIGN_ALLOW | |
1324 | bool | |
1325 | help | |
1326 | Enable support for /proc/sys/kernel/unaligned-trap | |
1327 | Allows arches to define/use @unaligned_enabled to runtime toggle | |
1328 | the unaligned access emulation. | |
1329 | see arch/parisc/kernel/unaligned.c for reference | |
1330 | ||
1331 | config HAVE_PCSPKR_PLATFORM | |
1332 | bool | |
1333 | ||
1334 | # interpreter that classic socket filters depend on | |
1335 | config BPF | |
1336 | bool | |
1337 | ||
1338 | menuconfig EXPERT | |
1339 | bool "Configure standard kernel features (expert users)" | |
1340 | # Unhide debug options, to make the on-by-default options visible | |
1341 | select DEBUG_KERNEL | |
1342 | help | |
1343 | This option allows certain base kernel options and settings | |
1344 | to be disabled or tweaked. This is for specialized | |
1345 | environments which can tolerate a "non-standard" kernel. | |
1346 | Only use this if you really know what you are doing. | |
1347 | ||
1348 | config UID16 | |
1349 | bool "Enable 16-bit UID system calls" if EXPERT | |
1350 | depends on HAVE_UID16 && MULTIUSER | |
1351 | default y | |
1352 | help | |
1353 | This enables the legacy 16-bit UID syscall wrappers. | |
1354 | ||
1355 | config MULTIUSER | |
1356 | bool "Multiple users, groups and capabilities support" if EXPERT | |
1357 | default y | |
1358 | help | |
1359 | This option enables support for non-root users, groups and | |
1360 | capabilities. | |
1361 | ||
1362 | If you say N here, all processes will run with UID 0, GID 0, and all | |
1363 | possible capabilities. Saying N here also compiles out support for | |
1364 | system calls related to UIDs, GIDs, and capabilities, such as setuid, | |
1365 | setgid, and capset. | |
1366 | ||
1367 | If unsure, say Y here. | |
1368 | ||
1369 | config SGETMASK_SYSCALL | |
1370 | bool "sgetmask/ssetmask syscalls support" if EXPERT | |
1371 | def_bool PARISC || MN10300 || BLACKFIN || M68K || PPC || MIPS || X86 || SPARC || CRIS || MICROBLAZE || SUPERH | |
1372 | ---help--- | |
1373 | sys_sgetmask and sys_ssetmask are obsolete system calls | |
1374 | no longer supported in libc but still enabled by default in some | |
1375 | architectures. | |
1376 | ||
1377 | If unsure, leave the default option here. | |
1378 | ||
1379 | config SYSFS_SYSCALL | |
1380 | bool "Sysfs syscall support" if EXPERT | |
1381 | default y | |
1382 | ---help--- | |
1383 | sys_sysfs is an obsolete system call no longer supported in libc. | |
1384 | Note that disabling this option is more secure but might break | |
1385 | compatibility with some systems. | |
1386 | ||
1387 | If unsure say Y here. | |
1388 | ||
1389 | config SYSCTL_SYSCALL | |
1390 | bool "Sysctl syscall support" if EXPERT | |
1391 | depends on PROC_SYSCTL | |
1392 | default n | |
1393 | select SYSCTL | |
1394 | ---help--- | |
1395 | sys_sysctl uses binary paths that have been found challenging | |
1396 | to properly maintain and use. The interface in /proc/sys | |
1397 | using paths with ascii names is now the primary path to this | |
1398 | information. | |
1399 | ||
1400 | Almost nothing using the binary sysctl interface so if you are | |
1401 | trying to save some space it is probably safe to disable this, | |
1402 | making your kernel marginally smaller. | |
1403 | ||
1404 | If unsure say N here. | |
1405 | ||
1406 | config KALLSYMS | |
1407 | bool "Load all symbols for debugging/ksymoops" if EXPERT | |
1408 | default y | |
1409 | help | |
1410 | Say Y here to let the kernel print out symbolic crash information and | |
1411 | symbolic stack backtraces. This increases the size of the kernel | |
1412 | somewhat, as all symbols have to be loaded into the kernel image. | |
1413 | ||
1414 | config KALLSYMS_ALL | |
1415 | bool "Include all symbols in kallsyms" | |
1416 | depends on DEBUG_KERNEL && KALLSYMS | |
1417 | help | |
1418 | Normally kallsyms only contains the symbols of functions for nicer | |
1419 | OOPS messages and backtraces (i.e., symbols from the text and inittext | |
1420 | sections). This is sufficient for most cases. And only in very rare | |
1421 | cases (e.g., when a debugger is used) all symbols are required (e.g., | |
1422 | names of variables from the data sections, etc). | |
1423 | ||
1424 | This option makes sure that all symbols are loaded into the kernel | |
1425 | image (i.e., symbols from all sections) in cost of increased kernel | |
1426 | size (depending on the kernel configuration, it may be 300KiB or | |
1427 | something like this). | |
1428 | ||
1429 | Say N unless you really need all symbols. | |
1430 | ||
1431 | config PRINTK | |
1432 | default y | |
1433 | bool "Enable support for printk" if EXPERT | |
1434 | select IRQ_WORK | |
1435 | help | |
1436 | This option enables normal printk support. Removing it | |
1437 | eliminates most of the message strings from the kernel image | |
1438 | and makes the kernel more or less silent. As this makes it | |
1439 | very difficult to diagnose system problems, saying N here is | |
1440 | strongly discouraged. | |
1441 | ||
1442 | config BUG | |
1443 | bool "BUG() support" if EXPERT | |
1444 | default y | |
1445 | help | |
1446 | Disabling this option eliminates support for BUG and WARN, reducing | |
1447 | the size of your kernel image and potentially quietly ignoring | |
1448 | numerous fatal conditions. You should only consider disabling this | |
1449 | option for embedded systems with no facilities for reporting errors. | |
1450 | Just say Y. | |
1451 | ||
1452 | config ELF_CORE | |
1453 | depends on COREDUMP | |
1454 | default y | |
1455 | bool "Enable ELF core dumps" if EXPERT | |
1456 | help | |
1457 | Enable support for generating core dumps. Disabling saves about 4k. | |
1458 | ||
1459 | ||
1460 | config PCSPKR_PLATFORM | |
1461 | bool "Enable PC-Speaker support" if EXPERT | |
1462 | depends on HAVE_PCSPKR_PLATFORM | |
1463 | select I8253_LOCK | |
1464 | default y | |
1465 | help | |
1466 | This option allows to disable the internal PC-Speaker | |
1467 | support, saving some memory. | |
1468 | ||
1469 | config BASE_FULL | |
1470 | default y | |
1471 | bool "Enable full-sized data structures for core" if EXPERT | |
1472 | help | |
1473 | Disabling this option reduces the size of miscellaneous core | |
1474 | kernel data structures. This saves memory on small machines, | |
1475 | but may reduce performance. | |
1476 | ||
1477 | config FUTEX | |
1478 | bool "Enable futex support" if EXPERT | |
1479 | default y | |
1480 | select RT_MUTEXES | |
1481 | help | |
1482 | Disabling this option will cause the kernel to be built without | |
1483 | support for "fast userspace mutexes". The resulting kernel may not | |
1484 | run glibc-based applications correctly. | |
1485 | ||
1486 | config HAVE_FUTEX_CMPXCHG | |
1487 | bool | |
1488 | depends on FUTEX | |
1489 | help | |
1490 | Architectures should select this if futex_atomic_cmpxchg_inatomic() | |
1491 | is implemented and always working. This removes a couple of runtime | |
1492 | checks. | |
1493 | ||
1494 | config EPOLL | |
1495 | bool "Enable eventpoll support" if EXPERT | |
1496 | default y | |
1497 | select ANON_INODES | |
1498 | help | |
1499 | Disabling this option will cause the kernel to be built without | |
1500 | support for epoll family of system calls. | |
1501 | ||
1502 | config SIGNALFD | |
1503 | bool "Enable signalfd() system call" if EXPERT | |
1504 | select ANON_INODES | |
1505 | default y | |
1506 | help | |
1507 | Enable the signalfd() system call that allows to receive signals | |
1508 | on a file descriptor. | |
1509 | ||
1510 | If unsure, say Y. | |
1511 | ||
1512 | config TIMERFD | |
1513 | bool "Enable timerfd() system call" if EXPERT | |
1514 | select ANON_INODES | |
1515 | default y | |
1516 | help | |
1517 | Enable the timerfd() system call that allows to receive timer | |
1518 | events on a file descriptor. | |
1519 | ||
1520 | If unsure, say Y. | |
1521 | ||
1522 | config EVENTFD | |
1523 | bool "Enable eventfd() system call" if EXPERT | |
1524 | select ANON_INODES | |
1525 | default y | |
1526 | help | |
1527 | Enable the eventfd() system call that allows to receive both | |
1528 | kernel notification (ie. KAIO) or userspace notifications. | |
1529 | ||
1530 | If unsure, say Y. | |
1531 | ||
1532 | # syscall, maps, verifier | |
1533 | config BPF_SYSCALL | |
1534 | bool "Enable bpf() system call" | |
1535 | select ANON_INODES | |
1536 | select BPF | |
1537 | default n | |
1538 | help | |
1539 | Enable the bpf() system call that allows to manipulate eBPF | |
1540 | programs and maps via file descriptors. | |
1541 | ||
1542 | config SHMEM | |
1543 | bool "Use full shmem filesystem" if EXPERT | |
1544 | default y | |
1545 | depends on MMU | |
1546 | help | |
1547 | The shmem is an internal filesystem used to manage shared memory. | |
1548 | It is backed by swap and manages resource limits. It is also exported | |
1549 | to userspace as tmpfs if TMPFS is enabled. Disabling this | |
1550 | option replaces shmem and tmpfs with the much simpler ramfs code, | |
1551 | which may be appropriate on small systems without swap. | |
1552 | ||
1553 | config AIO | |
1554 | bool "Enable AIO support" if EXPERT | |
1555 | default y | |
1556 | help | |
1557 | This option enables POSIX asynchronous I/O which may by used | |
1558 | by some high performance threaded applications. Disabling | |
1559 | this option saves about 7k. | |
1560 | ||
1561 | config ADVISE_SYSCALLS | |
1562 | bool "Enable madvise/fadvise syscalls" if EXPERT | |
1563 | default y | |
1564 | help | |
1565 | This option enables the madvise and fadvise syscalls, used by | |
1566 | applications to advise the kernel about their future memory or file | |
1567 | usage, improving performance. If building an embedded system where no | |
1568 | applications use these syscalls, you can disable this option to save | |
1569 | space. | |
1570 | ||
1571 | config PCI_QUIRKS | |
1572 | default y | |
1573 | bool "Enable PCI quirk workarounds" if EXPERT | |
1574 | depends on PCI | |
1575 | help | |
1576 | This enables workarounds for various PCI chipset | |
1577 | bugs/quirks. Disable this only if your target machine is | |
1578 | unaffected by PCI quirks. | |
1579 | ||
1580 | config EMBEDDED | |
1581 | bool "Embedded system" | |
1582 | option allnoconfig_y | |
1583 | select EXPERT | |
1584 | help | |
1585 | This option should be enabled if compiling the kernel for | |
1586 | an embedded system so certain expert options are available | |
1587 | for configuration. | |
1588 | ||
1589 | config HAVE_PERF_EVENTS | |
1590 | bool | |
1591 | help | |
1592 | See tools/perf/design.txt for details. | |
1593 | ||
1594 | config PERF_USE_VMALLOC | |
1595 | bool | |
1596 | help | |
1597 | See tools/perf/design.txt for details | |
1598 | ||
1599 | menu "Kernel Performance Events And Counters" | |
1600 | ||
1601 | config PERF_EVENTS | |
1602 | bool "Kernel performance events and counters" | |
1603 | default y if PROFILING | |
1604 | depends on HAVE_PERF_EVENTS | |
1605 | select ANON_INODES | |
1606 | select IRQ_WORK | |
1607 | select SRCU | |
1608 | help | |
1609 | Enable kernel support for various performance events provided | |
1610 | by software and hardware. | |
1611 | ||
1612 | Software events are supported either built-in or via the | |
1613 | use of generic tracepoints. | |
1614 | ||
1615 | Most modern CPUs support performance events via performance | |
1616 | counter registers. These registers count the number of certain | |
1617 | types of hw events: such as instructions executed, cachemisses | |
1618 | suffered, or branches mis-predicted - without slowing down the | |
1619 | kernel or applications. These registers can also trigger interrupts | |
1620 | when a threshold number of events have passed - and can thus be | |
1621 | used to profile the code that runs on that CPU. | |
1622 | ||
1623 | The Linux Performance Event subsystem provides an abstraction of | |
1624 | these software and hardware event capabilities, available via a | |
1625 | system call and used by the "perf" utility in tools/perf/. It | |
1626 | provides per task and per CPU counters, and it provides event | |
1627 | capabilities on top of those. | |
1628 | ||
1629 | Say Y if unsure. | |
1630 | ||
1631 | config DEBUG_PERF_USE_VMALLOC | |
1632 | default n | |
1633 | bool "Debug: use vmalloc to back perf mmap() buffers" | |
1634 | depends on PERF_EVENTS && DEBUG_KERNEL && !PPC | |
1635 | select PERF_USE_VMALLOC | |
1636 | help | |
1637 | Use vmalloc memory to back perf mmap() buffers. | |
1638 | ||
1639 | Mostly useful for debugging the vmalloc code on platforms | |
1640 | that don't require it. | |
1641 | ||
1642 | Say N if unsure. | |
1643 | ||
1644 | endmenu | |
1645 | ||
1646 | config VM_EVENT_COUNTERS | |
1647 | default y | |
1648 | bool "Enable VM event counters for /proc/vmstat" if EXPERT | |
1649 | help | |
1650 | VM event counters are needed for event counts to be shown. | |
1651 | This option allows the disabling of the VM event counters | |
1652 | on EXPERT systems. /proc/vmstat will only show page counts | |
1653 | if VM event counters are disabled. | |
1654 | ||
1655 | config SLUB_DEBUG | |
1656 | default y | |
1657 | bool "Enable SLUB debugging support" if EXPERT | |
1658 | depends on SLUB && SYSFS | |
1659 | help | |
1660 | SLUB has extensive debug support features. Disabling these can | |
1661 | result in significant savings in code size. This also disables | |
1662 | SLUB sysfs support. /sys/slab will not exist and there will be | |
1663 | no support for cache validation etc. | |
1664 | ||
1665 | config COMPAT_BRK | |
1666 | bool "Disable heap randomization" | |
1667 | default y | |
1668 | help | |
1669 | Randomizing heap placement makes heap exploits harder, but it | |
1670 | also breaks ancient binaries (including anything libc5 based). | |
1671 | This option changes the bootup default to heap randomization | |
1672 | disabled, and can be overridden at runtime by setting | |
1673 | /proc/sys/kernel/randomize_va_space to 2. | |
1674 | ||
1675 | On non-ancient distros (post-2000 ones) N is usually a safe choice. | |
1676 | ||
1677 | choice | |
1678 | prompt "Choose SLAB allocator" | |
1679 | default SLUB | |
1680 | help | |
1681 | This option allows to select a slab allocator. | |
1682 | ||
1683 | config SLAB | |
1684 | bool "SLAB" | |
1685 | help | |
1686 | The regular slab allocator that is established and known to work | |
1687 | well in all environments. It organizes cache hot objects in | |
1688 | per cpu and per node queues. | |
1689 | ||
1690 | config SLUB | |
1691 | bool "SLUB (Unqueued Allocator)" | |
1692 | help | |
1693 | SLUB is a slab allocator that minimizes cache line usage | |
1694 | instead of managing queues of cached objects (SLAB approach). | |
1695 | Per cpu caching is realized using slabs of objects instead | |
1696 | of queues of objects. SLUB can use memory efficiently | |
1697 | and has enhanced diagnostics. SLUB is the default choice for | |
1698 | a slab allocator. | |
1699 | ||
1700 | config SLOB | |
1701 | depends on EXPERT | |
1702 | bool "SLOB (Simple Allocator)" | |
1703 | help | |
1704 | SLOB replaces the stock allocator with a drastically simpler | |
1705 | allocator. SLOB is generally more space efficient but | |
1706 | does not perform as well on large systems. | |
1707 | ||
1708 | endchoice | |
1709 | ||
1710 | config SLUB_CPU_PARTIAL | |
1711 | default y | |
1712 | depends on SLUB && SMP | |
1713 | bool "SLUB per cpu partial cache" | |
1714 | help | |
1715 | Per cpu partial caches accellerate objects allocation and freeing | |
1716 | that is local to a processor at the price of more indeterminism | |
1717 | in the latency of the free. On overflow these caches will be cleared | |
1718 | which requires the taking of locks that may cause latency spikes. | |
1719 | Typically one would choose no for a realtime system. | |
1720 | ||
1721 | config MMAP_ALLOW_UNINITIALIZED | |
1722 | bool "Allow mmapped anonymous memory to be uninitialized" | |
1723 | depends on EXPERT && !MMU | |
1724 | default n | |
1725 | help | |
1726 | Normally, and according to the Linux spec, anonymous memory obtained | |
1727 | from mmap() has it's contents cleared before it is passed to | |
1728 | userspace. Enabling this config option allows you to request that | |
1729 | mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus | |
1730 | providing a huge performance boost. If this option is not enabled, | |
1731 | then the flag will be ignored. | |
1732 | ||
1733 | This is taken advantage of by uClibc's malloc(), and also by | |
1734 | ELF-FDPIC binfmt's brk and stack allocator. | |
1735 | ||
1736 | Because of the obvious security issues, this option should only be | |
1737 | enabled on embedded devices where you control what is run in | |
1738 | userspace. Since that isn't generally a problem on no-MMU systems, | |
1739 | it is normally safe to say Y here. | |
1740 | ||
1741 | See Documentation/nommu-mmap.txt for more information. | |
1742 | ||
1743 | config SYSTEM_TRUSTED_KEYRING | |
1744 | bool "Provide system-wide ring of trusted keys" | |
1745 | depends on KEYS | |
1746 | help | |
1747 | Provide a system keyring to which trusted keys can be added. Keys in | |
1748 | the keyring are considered to be trusted. Keys may be added at will | |
1749 | by the kernel from compiled-in data and from hardware key stores, but | |
1750 | userspace may only add extra keys if those keys can be verified by | |
1751 | keys already in the keyring. | |
1752 | ||
1753 | Keys in this keyring are used by module signature checking. | |
1754 | ||
1755 | config SYSTEM_TRUSTED_KEYS | |
1756 | string "Additional X.509 keys for default system keyring" | |
1757 | depends on SYSTEM_TRUSTED_KEYRING | |
1758 | help | |
1759 | If set, this option should be the filename of a PEM-formatted file | |
1760 | containing trusted X.509 certificates to be included in the default | |
1761 | system keyring. Any certificate used for module signing is implicitly | |
1762 | also trusted. | |
1763 | ||
1764 | NOTE: If you previously provided keys for the system keyring in the | |
1765 | form of DER-encoded *.x509 files in the top-level build directory, | |
1766 | those are no longer used. You will need to set this option instead. | |
1767 | ||
1768 | config SYSTEM_DATA_VERIFICATION | |
1769 | def_bool n | |
1770 | select SYSTEM_TRUSTED_KEYRING | |
1771 | select KEYS | |
1772 | select CRYPTO | |
1773 | select ASYMMETRIC_KEY_TYPE | |
1774 | select ASYMMETRIC_PUBLIC_KEY_SUBTYPE | |
1775 | select PUBLIC_KEY_ALGO_RSA | |
1776 | select ASN1 | |
1777 | select OID_REGISTRY | |
1778 | select X509_CERTIFICATE_PARSER | |
1779 | select PKCS7_MESSAGE_PARSER | |
1780 | help | |
1781 | Provide PKCS#7 message verification using the contents of the system | |
1782 | trusted keyring to provide public keys. This then can be used for | |
1783 | module verification, kexec image verification and firmware blob | |
1784 | verification. | |
1785 | ||
1786 | config PROFILING | |
1787 | bool "Profiling support" | |
1788 | help | |
1789 | Say Y here to enable the extended profiling support mechanisms used | |
1790 | by profilers such as OProfile. | |
1791 | ||
1792 | # | |
1793 | # Place an empty function call at each tracepoint site. Can be | |
1794 | # dynamically changed for a probe function. | |
1795 | # | |
1796 | config TRACEPOINTS | |
1797 | bool | |
1798 | ||
1799 | source "arch/Kconfig" | |
1800 | ||
1801 | endmenu # General setup | |
1802 | ||
1803 | config HAVE_GENERIC_DMA_COHERENT | |
1804 | bool | |
1805 | default n | |
1806 | ||
1807 | config SLABINFO | |
1808 | bool | |
1809 | depends on PROC_FS | |
1810 | depends on SLAB || SLUB_DEBUG | |
1811 | default y | |
1812 | ||
1813 | config RT_MUTEXES | |
1814 | bool | |
1815 | ||
1816 | config BASE_SMALL | |
1817 | int | |
1818 | default 0 if BASE_FULL | |
1819 | default 1 if !BASE_FULL | |
1820 | ||
1821 | menuconfig MODULES | |
1822 | bool "Enable loadable module support" | |
1823 | option modules | |
1824 | help | |
1825 | Kernel modules are small pieces of compiled code which can | |
1826 | be inserted in the running kernel, rather than being | |
1827 | permanently built into the kernel. You use the "modprobe" | |
1828 | tool to add (and sometimes remove) them. If you say Y here, | |
1829 | many parts of the kernel can be built as modules (by | |
1830 | answering M instead of Y where indicated): this is most | |
1831 | useful for infrequently used options which are not required | |
1832 | for booting. For more information, see the man pages for | |
1833 | modprobe, lsmod, modinfo, insmod and rmmod. | |
1834 | ||
1835 | If you say Y here, you will need to run "make | |
1836 | modules_install" to put the modules under /lib/modules/ | |
1837 | where modprobe can find them (you may need to be root to do | |
1838 | this). | |
1839 | ||
1840 | If unsure, say Y. | |
1841 | ||
1842 | if MODULES | |
1843 | ||
1844 | config MODULE_FORCE_LOAD | |
1845 | bool "Forced module loading" | |
1846 | default n | |
1847 | help | |
1848 | Allow loading of modules without version information (ie. modprobe | |
1849 | --force). Forced module loading sets the 'F' (forced) taint flag and | |
1850 | is usually a really bad idea. | |
1851 | ||
1852 | config MODULE_UNLOAD | |
1853 | bool "Module unloading" | |
1854 | help | |
1855 | Without this option you will not be able to unload any | |
1856 | modules (note that some modules may not be unloadable | |
1857 | anyway), which makes your kernel smaller, faster | |
1858 | and simpler. If unsure, say Y. | |
1859 | ||
1860 | config MODULE_FORCE_UNLOAD | |
1861 | bool "Forced module unloading" | |
1862 | depends on MODULE_UNLOAD | |
1863 | help | |
1864 | This option allows you to force a module to unload, even if the | |
1865 | kernel believes it is unsafe: the kernel will remove the module | |
1866 | without waiting for anyone to stop using it (using the -f option to | |
1867 | rmmod). This is mainly for kernel developers and desperate users. | |
1868 | If unsure, say N. | |
1869 | ||
1870 | config MODVERSIONS | |
1871 | bool "Module versioning support" | |
1872 | help | |
1873 | Usually, you have to use modules compiled with your kernel. | |
1874 | Saying Y here makes it sometimes possible to use modules | |
1875 | compiled for different kernels, by adding enough information | |
1876 | to the modules to (hopefully) spot any changes which would | |
1877 | make them incompatible with the kernel you are running. If | |
1878 | unsure, say N. | |
1879 | ||
1880 | config MODULE_SRCVERSION_ALL | |
1881 | bool "Source checksum for all modules" | |
1882 | help | |
1883 | Modules which contain a MODULE_VERSION get an extra "srcversion" | |
1884 | field inserted into their modinfo section, which contains a | |
1885 | sum of the source files which made it. This helps maintainers | |
1886 | see exactly which source was used to build a module (since | |
1887 | others sometimes change the module source without updating | |
1888 | the version). With this option, such a "srcversion" field | |
1889 | will be created for all modules. If unsure, say N. | |
1890 | ||
1891 | config MODULE_SIG | |
1892 | bool "Module signature verification" | |
1893 | depends on MODULES | |
1894 | select SYSTEM_DATA_VERIFICATION | |
1895 | help | |
1896 | Check modules for valid signatures upon load: the signature | |
1897 | is simply appended to the module. For more information see | |
1898 | Documentation/module-signing.txt. | |
1899 | ||
1900 | !!!WARNING!!! If you enable this option, you MUST make sure that the | |
1901 | module DOES NOT get stripped after being signed. This includes the | |
1902 | debuginfo strip done by some packagers (such as rpmbuild) and | |
1903 | inclusion into an initramfs that wants the module size reduced. | |
1904 | ||
1905 | config MODULE_SIG_FORCE | |
1906 | bool "Require modules to be validly signed" | |
1907 | depends on MODULE_SIG | |
1908 | help | |
1909 | Reject unsigned modules or signed modules for which we don't have a | |
1910 | key. Without this, such modules will simply taint the kernel. | |
1911 | ||
1912 | config MODULE_SIG_ALL | |
1913 | bool "Automatically sign all modules" | |
1914 | default y | |
1915 | depends on MODULE_SIG | |
1916 | help | |
1917 | Sign all modules during make modules_install. Without this option, | |
1918 | modules must be signed manually, using the scripts/sign-file tool. | |
1919 | ||
1920 | comment "Do not forget to sign required modules with scripts/sign-file" | |
1921 | depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL | |
1922 | ||
1923 | choice | |
1924 | prompt "Which hash algorithm should modules be signed with?" | |
1925 | depends on MODULE_SIG | |
1926 | help | |
1927 | This determines which sort of hashing algorithm will be used during | |
1928 | signature generation. This algorithm _must_ be built into the kernel | |
1929 | directly so that signature verification can take place. It is not | |
1930 | possible to load a signed module containing the algorithm to check | |
1931 | the signature on that module. | |
1932 | ||
1933 | config MODULE_SIG_SHA1 | |
1934 | bool "Sign modules with SHA-1" | |
1935 | select CRYPTO_SHA1 | |
1936 | ||
1937 | config MODULE_SIG_SHA224 | |
1938 | bool "Sign modules with SHA-224" | |
1939 | select CRYPTO_SHA256 | |
1940 | ||
1941 | config MODULE_SIG_SHA256 | |
1942 | bool "Sign modules with SHA-256" | |
1943 | select CRYPTO_SHA256 | |
1944 | ||
1945 | config MODULE_SIG_SHA384 | |
1946 | bool "Sign modules with SHA-384" | |
1947 | select CRYPTO_SHA512 | |
1948 | ||
1949 | config MODULE_SIG_SHA512 | |
1950 | bool "Sign modules with SHA-512" | |
1951 | select CRYPTO_SHA512 | |
1952 | ||
1953 | endchoice | |
1954 | ||
1955 | config MODULE_SIG_HASH | |
1956 | string | |
1957 | depends on MODULE_SIG | |
1958 | default "sha1" if MODULE_SIG_SHA1 | |
1959 | default "sha224" if MODULE_SIG_SHA224 | |
1960 | default "sha256" if MODULE_SIG_SHA256 | |
1961 | default "sha384" if MODULE_SIG_SHA384 | |
1962 | default "sha512" if MODULE_SIG_SHA512 | |
1963 | ||
1964 | config MODULE_SIG_KEY | |
1965 | string "File name or PKCS#11 URI of module signing key" | |
1966 | default "signing_key.pem" | |
1967 | depends on MODULE_SIG | |
1968 | help | |
1969 | Provide the file name of a private key/certificate in PEM format, | |
1970 | or a PKCS#11 URI according to RFC7512. The file should contain, or | |
1971 | the URI should identify, both the certificate and its corresponding | |
1972 | private key. | |
1973 | ||
1974 | If this option is unchanged from its default "signing_key.pem", | |
1975 | then the kernel will automatically generate the private key and | |
1976 | certificate as described in Documentation/module-signing.txt | |
1977 | ||
1978 | config MODULE_COMPRESS | |
1979 | bool "Compress modules on installation" | |
1980 | depends on MODULES | |
1981 | help | |
1982 | ||
1983 | Compresses kernel modules when 'make modules_install' is run; gzip or | |
1984 | xz depending on "Compression algorithm" below. | |
1985 | ||
1986 | module-init-tools MAY support gzip, and kmod MAY support gzip and xz. | |
1987 | ||
1988 | Out-of-tree kernel modules installed using Kbuild will also be | |
1989 | compressed upon installation. | |
1990 | ||
1991 | Note: for modules inside an initrd or initramfs, it's more efficient | |
1992 | to compress the whole initrd or initramfs instead. | |
1993 | ||
1994 | Note: This is fully compatible with signed modules. | |
1995 | ||
1996 | If in doubt, say N. | |
1997 | ||
1998 | choice | |
1999 | prompt "Compression algorithm" | |
2000 | depends on MODULE_COMPRESS | |
2001 | default MODULE_COMPRESS_GZIP | |
2002 | help | |
2003 | This determines which sort of compression will be used during | |
2004 | 'make modules_install'. | |
2005 | ||
2006 | GZIP (default) and XZ are supported. | |
2007 | ||
2008 | config MODULE_COMPRESS_GZIP | |
2009 | bool "GZIP" | |
2010 | ||
2011 | config MODULE_COMPRESS_XZ | |
2012 | bool "XZ" | |
2013 | ||
2014 | endchoice | |
2015 | ||
2016 | endif # MODULES | |
2017 | ||
2018 | config MODULES_TREE_LOOKUP | |
2019 | def_bool y | |
2020 | depends on PERF_EVENTS || TRACING | |
2021 | ||
2022 | config INIT_ALL_POSSIBLE | |
2023 | bool | |
2024 | help | |
2025 | Back when each arch used to define their own cpu_online_mask and | |
2026 | cpu_possible_mask, some of them chose to initialize cpu_possible_mask | |
2027 | with all 1s, and others with all 0s. When they were centralised, | |
2028 | it was better to provide this option than to break all the archs | |
2029 | and have several arch maintainers pursuing me down dark alleys. | |
2030 | ||
2031 | config STOP_MACHINE | |
2032 | bool | |
2033 | default y | |
2034 | depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU | |
2035 | help | |
2036 | Need stop_machine() primitive. | |
2037 | ||
2038 | source "block/Kconfig" | |
2039 | ||
2040 | config PREEMPT_NOTIFIERS | |
2041 | bool | |
2042 | ||
2043 | config PADATA | |
2044 | depends on SMP | |
2045 | bool | |
2046 | ||
2047 | # Can be selected by architectures with broken toolchains | |
2048 | # that get confused by correct const<->read_only section | |
2049 | # mappings | |
2050 | config BROKEN_RODATA | |
2051 | bool | |
2052 | ||
2053 | config ASN1 | |
2054 | tristate | |
2055 | help | |
2056 | Build a simple ASN.1 grammar compiler that produces a bytecode output | |
2057 | that can be interpreted by the ASN.1 stream decoder and used to | |
2058 | inform it as to what tags are to be expected in a stream and what | |
2059 | functions to call on what tags. | |
2060 | ||
2061 | source "kernel/Kconfig.locks" |