Commit | Line | Data |
---|---|---|
face4374 RZ |
1 | config DEFCONFIG_LIST |
2 | string | |
b2670eac | 3 | depends on !UML |
face4374 | 4 | option defconfig_list |
2972666a | 5 | default "/lib/modules/$(shell,uname --release)/.config" |
face4374 | 6 | default "/etc/kernel-config" |
2972666a | 7 | default "/boot/config-$(shell,uname --release)" |
104daea1 MY |
8 | default ARCH_DEFCONFIG |
9 | default "arch/$(ARCH)/defconfig" | |
face4374 | 10 | |
b99b87f7 PO |
11 | config CONSTRUCTORS |
12 | bool | |
13 | depends on !UML | |
b99b87f7 | 14 | |
e360adbe PZ |
15 | config IRQ_WORK |
16 | bool | |
e360adbe | 17 | |
1dbdc6f1 DD |
18 | config BUILDTIME_EXTABLE_SORT |
19 | bool | |
20 | ||
c65eacbe AL |
21 | config THREAD_INFO_IN_TASK |
22 | bool | |
23 | help | |
24 | Select this to move thread_info off the stack into task_struct. To | |
25 | make this work, an arch will need to remove all thread_info fields | |
26 | except flags and fix any runtime bugs. | |
27 | ||
c6c314a6 AL |
28 | One subtle change that will be needed is to use try_get_task_stack() |
29 | and put_task_stack() in save_thread_stack_tsk() and get_wchan(). | |
30 | ||
ff0cfc66 | 31 | menu "General setup" |
1da177e4 | 32 | |
1da177e4 LT |
33 | config BROKEN |
34 | bool | |
1da177e4 LT |
35 | |
36 | config BROKEN_ON_SMP | |
37 | bool | |
38 | depends on BROKEN || !SMP | |
39 | default y | |
40 | ||
1da177e4 LT |
41 | config INIT_ENV_ARG_LIMIT |
42 | int | |
dd673bca AB |
43 | default 32 if !UML |
44 | default 128 if UML | |
1da177e4 | 45 | help |
34ad92c2 RD |
46 | Maximum of each of the number of arguments and environment |
47 | variables passed to init from the kernel command line. | |
1da177e4 | 48 | |
4bb16672 JS |
49 | config COMPILE_TEST |
50 | bool "Compile also drivers which will not load" | |
bc083a64 | 51 | depends on !UML |
4bb16672 JS |
52 | default n |
53 | help | |
54 | Some drivers can be compiled on a different platform than they are | |
55 | intended to be run on. Despite they cannot be loaded there (or even | |
56 | when they load they cannot be used due to missing HW support), | |
57 | developers still, opposing to distributors, might want to build such | |
58 | drivers to compile-test them. | |
59 | ||
60 | If you are a developer and want to build everything available, say Y | |
61 | here. If you are a user/distributor, say N here to exclude useless | |
62 | drivers to be distributed. | |
63 | ||
1da177e4 LT |
64 | config LOCALVERSION |
65 | string "Local version - append to kernel release" | |
66 | help | |
67 | Append an extra string to the end of your kernel version. | |
68 | This will show up when you type uname, for example. | |
69 | The string you set here will be appended after the contents of | |
70 | any files with a filename matching localversion* in your | |
71 | object and source tree, in that order. Your total string can | |
72 | be a maximum of 64 characters. | |
73 | ||
aaebf433 RA |
74 | config LOCALVERSION_AUTO |
75 | bool "Automatically append version information to the version string" | |
76 | default y | |
ac3339ba | 77 | depends on !COMPILE_TEST |
aaebf433 RA |
78 | help |
79 | This will try to automatically determine if the current tree is a | |
6e5a5420 RD |
80 | release tree by looking for git tags that belong to the current |
81 | top of tree revision. | |
aaebf433 RA |
82 | |
83 | A string of the format -gxxxxxxxx will be added to the localversion | |
6e5a5420 | 84 | if a git-based tree is found. The string generated by this will be |
aaebf433 | 85 | appended after any matching localversion* files, and after the value |
6e5a5420 | 86 | set in CONFIG_LOCALVERSION. |
aaebf433 | 87 | |
6e5a5420 RD |
88 | (The actual string used here is the first eight characters produced |
89 | by running the command: | |
90 | ||
91 | $ git rev-parse --verify HEAD | |
92 | ||
93 | which is done within the script "scripts/setlocalversion".) | |
aaebf433 | 94 | |
2e9f3bdd PA |
95 | config HAVE_KERNEL_GZIP |
96 | bool | |
97 | ||
98 | config HAVE_KERNEL_BZIP2 | |
99 | bool | |
100 | ||
101 | config HAVE_KERNEL_LZMA | |
102 | bool | |
103 | ||
3ebe1243 LC |
104 | config HAVE_KERNEL_XZ |
105 | bool | |
106 | ||
7dd65feb AT |
107 | config HAVE_KERNEL_LZO |
108 | bool | |
109 | ||
e76e1fdf KL |
110 | config HAVE_KERNEL_LZ4 |
111 | bool | |
112 | ||
30d65dbf | 113 | choice |
2e9f3bdd PA |
114 | prompt "Kernel compression mode" |
115 | default KERNEL_GZIP | |
2d3c6275 | 116 | depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 |
2e9f3bdd | 117 | help |
30d65dbf AK |
118 | The linux kernel is a kind of self-extracting executable. |
119 | Several compression algorithms are available, which differ | |
120 | in efficiency, compression and decompression speed. | |
121 | Compression speed is only relevant when building a kernel. | |
122 | Decompression speed is relevant at each boot. | |
123 | ||
124 | If you have any problems with bzip2 or lzma compressed | |
125 | kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older | |
126 | version of this functionality (bzip2 only), for 2.4, was | |
127 | supplied by Christian Ludwig) | |
128 | ||
129 | High compression options are mostly useful for users, who | |
130 | are low on disk space (embedded systems), but for whom ram | |
131 | size matters less. | |
132 | ||
133 | If in doubt, select 'gzip' | |
134 | ||
135 | config KERNEL_GZIP | |
2e9f3bdd PA |
136 | bool "Gzip" |
137 | depends on HAVE_KERNEL_GZIP | |
138 | help | |
7dd65feb AT |
139 | The old and tried gzip compression. It provides a good balance |
140 | between compression ratio and decompression speed. | |
30d65dbf AK |
141 | |
142 | config KERNEL_BZIP2 | |
143 | bool "Bzip2" | |
2e9f3bdd | 144 | depends on HAVE_KERNEL_BZIP2 |
30d65dbf AK |
145 | help |
146 | Its compression ratio and speed is intermediate. | |
0a4dd35c | 147 | Decompression speed is slowest among the choices. The kernel |
2e9f3bdd PA |
148 | size is about 10% smaller with bzip2, in comparison to gzip. |
149 | Bzip2 uses a large amount of memory. For modern kernels you | |
150 | will need at least 8MB RAM or more for booting. | |
30d65dbf AK |
151 | |
152 | config KERNEL_LZMA | |
2e9f3bdd PA |
153 | bool "LZMA" |
154 | depends on HAVE_KERNEL_LZMA | |
155 | help | |
0a4dd35c RD |
156 | This compression algorithm's ratio is best. Decompression speed |
157 | is between gzip and bzip2. Compression is slowest. | |
158 | The kernel size is about 33% smaller with LZMA in comparison to gzip. | |
30d65dbf | 159 | |
3ebe1243 LC |
160 | config KERNEL_XZ |
161 | bool "XZ" | |
162 | depends on HAVE_KERNEL_XZ | |
163 | help | |
164 | XZ uses the LZMA2 algorithm and instruction set specific | |
165 | BCJ filters which can improve compression ratio of executable | |
166 | code. The size of the kernel is about 30% smaller with XZ in | |
167 | comparison to gzip. On architectures for which there is a BCJ | |
168 | filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ | |
169 | will create a few percent smaller kernel than plain LZMA. | |
170 | ||
171 | The speed is about the same as with LZMA: The decompression | |
172 | speed of XZ is better than that of bzip2 but worse than gzip | |
173 | and LZO. Compression is slow. | |
174 | ||
7dd65feb AT |
175 | config KERNEL_LZO |
176 | bool "LZO" | |
177 | depends on HAVE_KERNEL_LZO | |
178 | help | |
0a4dd35c | 179 | Its compression ratio is the poorest among the choices. The kernel |
681b3049 | 180 | size is about 10% bigger than gzip; however its speed |
7dd65feb AT |
181 | (both compression and decompression) is the fastest. |
182 | ||
e76e1fdf KL |
183 | config KERNEL_LZ4 |
184 | bool "LZ4" | |
185 | depends on HAVE_KERNEL_LZ4 | |
186 | help | |
187 | LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding. | |
188 | A preliminary version of LZ4 de/compression tool is available at | |
189 | <https://code.google.com/p/lz4/>. | |
190 | ||
191 | Its compression ratio is worse than LZO. The size of the kernel | |
192 | is about 8% bigger than LZO. But the decompression speed is | |
193 | faster than LZO. | |
194 | ||
30d65dbf AK |
195 | endchoice |
196 | ||
bd5dc17b JT |
197 | config DEFAULT_HOSTNAME |
198 | string "Default hostname" | |
199 | default "(none)" | |
200 | help | |
201 | This option determines the default system hostname before userspace | |
202 | calls sethostname(2). The kernel traditionally uses "(none)" here, | |
203 | but you may wish to use a different default here to make a minimal | |
204 | system more usable with less configuration. | |
205 | ||
1da177e4 LT |
206 | config SWAP |
207 | bool "Support for paging of anonymous memory (swap)" | |
9361401e | 208 | depends on MMU && BLOCK |
1da177e4 LT |
209 | default y |
210 | help | |
211 | This option allows you to choose whether you want to have support | |
92c3504e | 212 | for so called swap devices or swap files in your kernel that are |
1da177e4 LT |
213 | used to provide more virtual memory than the actual RAM present |
214 | in your computer. If unsure say Y. | |
215 | ||
216 | config SYSVIPC | |
217 | bool "System V IPC" | |
1da177e4 LT |
218 | ---help--- |
219 | Inter Process Communication is a suite of library functions and | |
220 | system calls which let processes (running programs) synchronize and | |
221 | exchange information. It is generally considered to be a good thing, | |
222 | and some programs won't run unless you say Y here. In particular, if | |
223 | you want to run the DOS emulator dosemu under Linux (read the | |
224 | DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), | |
225 | you'll need to say Y here. | |
226 | ||
227 | You can find documentation about IPC with "info ipc" and also in | |
228 | section 6.4 of the Linux Programmer's Guide, available from | |
229 | <http://www.tldp.org/guides.html>. | |
230 | ||
a5494dcd EB |
231 | config SYSVIPC_SYSCTL |
232 | bool | |
233 | depends on SYSVIPC | |
234 | depends on SYSCTL | |
235 | default y | |
236 | ||
1da177e4 LT |
237 | config POSIX_MQUEUE |
238 | bool "POSIX Message Queues" | |
19c92399 | 239 | depends on NET |
1da177e4 LT |
240 | ---help--- |
241 | POSIX variant of message queues is a part of IPC. In POSIX message | |
242 | queues every message has a priority which decides about succession | |
243 | of receiving it by a process. If you want to compile and run | |
244 | programs written e.g. for Solaris with use of its POSIX message | |
b0e37650 | 245 | queues (functions mq_*) say Y here. |
1da177e4 LT |
246 | |
247 | POSIX message queues are visible as a filesystem called 'mqueue' | |
248 | and can be mounted somewhere if you want to do filesystem | |
249 | operations on message queues. | |
250 | ||
251 | If unsure, say Y. | |
252 | ||
bdc8e5f8 SH |
253 | config POSIX_MQUEUE_SYSCTL |
254 | bool | |
255 | depends on POSIX_MQUEUE | |
256 | depends on SYSCTL | |
257 | default y | |
258 | ||
226b4ccd KK |
259 | config CROSS_MEMORY_ATTACH |
260 | bool "Enable process_vm_readv/writev syscalls" | |
261 | depends on MMU | |
262 | default y | |
263 | help | |
264 | Enabling this option adds the system calls process_vm_readv and | |
265 | process_vm_writev which allow a process with the correct privileges | |
a2a368d9 | 266 | to directly read from or write to another process' address space. |
226b4ccd KK |
267 | See the man page for more details. |
268 | ||
69369a70 JT |
269 | config USELIB |
270 | bool "uselib syscall" | |
b2113a41 | 271 | def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION |
69369a70 JT |
272 | help |
273 | This option enables the uselib syscall, a system call used in the | |
274 | dynamic linker from libc5 and earlier. glibc does not use this | |
275 | system call. If you intend to run programs built on libc5 or | |
276 | earlier, you may need to enable this syscall. Current systems | |
277 | running glibc can safely disable this. | |
278 | ||
391dc69c FW |
279 | config AUDIT |
280 | bool "Auditing support" | |
281 | depends on NET | |
282 | help | |
283 | Enable auditing infrastructure that can be used with another | |
284 | kernel subsystem, such as SELinux (which requires this for | |
cb74ed27 PM |
285 | logging of avc messages output). System call auditing is included |
286 | on architectures which support it. | |
391dc69c | 287 | |
7a017721 AT |
288 | config HAVE_ARCH_AUDITSYSCALL |
289 | bool | |
290 | ||
391dc69c | 291 | config AUDITSYSCALL |
cb74ed27 | 292 | def_bool y |
7a017721 | 293 | depends on AUDIT && HAVE_ARCH_AUDITSYSCALL |
391dc69c FW |
294 | |
295 | config AUDIT_WATCH | |
296 | def_bool y | |
297 | depends on AUDITSYSCALL | |
298 | select FSNOTIFY | |
299 | ||
300 | config AUDIT_TREE | |
301 | def_bool y | |
302 | depends on AUDITSYSCALL | |
303 | select FSNOTIFY | |
304 | ||
391dc69c FW |
305 | source "kernel/irq/Kconfig" |
306 | source "kernel/time/Kconfig" | |
307 | ||
308 | menu "CPU/Task time and stats accounting" | |
309 | ||
abf917cd FW |
310 | config VIRT_CPU_ACCOUNTING |
311 | bool | |
312 | ||
fdf9c356 FW |
313 | choice |
314 | prompt "Cputime accounting" | |
315 | default TICK_CPU_ACCOUNTING if !PPC64 | |
02fc8d37 | 316 | default VIRT_CPU_ACCOUNTING_NATIVE if PPC64 |
fdf9c356 FW |
317 | |
318 | # Kind of a stub config for the pure tick based cputime accounting | |
319 | config TICK_CPU_ACCOUNTING | |
320 | bool "Simple tick based cputime accounting" | |
c58b0df1 | 321 | depends on !S390 && !NO_HZ_FULL |
fdf9c356 FW |
322 | help |
323 | This is the basic tick based cputime accounting that maintains | |
324 | statistics about user, system and idle time spent on per jiffies | |
325 | granularity. | |
326 | ||
327 | If unsure, say Y. | |
328 | ||
abf917cd | 329 | config VIRT_CPU_ACCOUNTING_NATIVE |
b952741c | 330 | bool "Deterministic task and CPU time accounting" |
c58b0df1 | 331 | depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL |
abf917cd | 332 | select VIRT_CPU_ACCOUNTING |
b952741c FW |
333 | help |
334 | Select this option to enable more accurate task and CPU time | |
335 | accounting. This is done by reading a CPU counter on each | |
336 | kernel entry and exit and on transitions within the kernel | |
337 | between system, softirq and hardirq state, so there is a | |
338 | small performance impact. In the case of s390 or IBM POWER > 5, | |
339 | this also enables accounting of stolen time on logically-partitioned | |
340 | systems. | |
341 | ||
abf917cd FW |
342 | config VIRT_CPU_ACCOUNTING_GEN |
343 | bool "Full dynticks CPU time accounting" | |
ff3fb254 | 344 | depends on HAVE_CONTEXT_TRACKING |
554b0004 | 345 | depends on HAVE_VIRT_CPU_ACCOUNTING_GEN |
abf917cd FW |
346 | select VIRT_CPU_ACCOUNTING |
347 | select CONTEXT_TRACKING | |
348 | help | |
349 | Select this option to enable task and CPU time accounting on full | |
350 | dynticks systems. This accounting is implemented by watching every | |
351 | kernel-user boundaries using the context tracking subsystem. | |
352 | The accounting is thus performed at the expense of some significant | |
353 | overhead. | |
354 | ||
355 | For now this is only useful if you are working on the full | |
356 | dynticks subsystem development. | |
357 | ||
358 | If unsure, say N. | |
359 | ||
b58c3584 RR |
360 | endchoice |
361 | ||
fdf9c356 FW |
362 | config IRQ_TIME_ACCOUNTING |
363 | bool "Fine granularity task level IRQ time accounting" | |
b58c3584 | 364 | depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE |
fdf9c356 FW |
365 | help |
366 | Select this option to enable fine granularity task irq time | |
367 | accounting. This is done by reading a timestamp on each | |
368 | transitions between softirq and hardirq state, so there can be a | |
369 | small performance impact. | |
370 | ||
371 | If in doubt, say N here. | |
372 | ||
1da177e4 LT |
373 | config BSD_PROCESS_ACCT |
374 | bool "BSD Process Accounting" | |
2813893f | 375 | depends on MULTIUSER |
1da177e4 LT |
376 | help |
377 | If you say Y here, a user level program will be able to instruct the | |
378 | kernel (via a special system call) to write process accounting | |
379 | information to a file: whenever a process exits, information about | |
380 | that process will be appended to the file by the kernel. The | |
381 | information includes things such as creation time, owning user, | |
382 | command name, memory usage, controlling terminal etc. (the complete | |
383 | list is in the struct acct in <file:include/linux/acct.h>). It is | |
384 | up to the user level program to do useful things with this | |
385 | information. This is generally a good idea, so say Y. | |
386 | ||
387 | config BSD_PROCESS_ACCT_V3 | |
388 | bool "BSD Process Accounting version 3 file format" | |
389 | depends on BSD_PROCESS_ACCT | |
390 | default n | |
391 | help | |
392 | If you say Y here, the process accounting information is written | |
393 | in a new file format that also logs the process IDs of each | |
394 | process and it's parent. Note that this file format is incompatible | |
395 | with previous v0/v1/v2 file formats, so you will need updated tools | |
396 | for processing it. A preliminary version of these tools is available | |
37a4c940 | 397 | at <http://www.gnu.org/software/acct/>. |
1da177e4 | 398 | |
c757249a | 399 | config TASKSTATS |
19c92399 | 400 | bool "Export task/process statistics through netlink" |
c757249a | 401 | depends on NET |
2813893f | 402 | depends on MULTIUSER |
c757249a SN |
403 | default n |
404 | help | |
405 | Export selected statistics for tasks/processes through the | |
406 | generic netlink interface. Unlike BSD process accounting, the | |
407 | statistics are available during the lifetime of tasks/processes as | |
408 | responses to commands. Like BSD accounting, they are sent to user | |
409 | space on task exit. | |
410 | ||
411 | Say N if unsure. | |
412 | ||
ca74e92b | 413 | config TASK_DELAY_ACCT |
19c92399 | 414 | bool "Enable per-task delay accounting" |
6f44993f | 415 | depends on TASKSTATS |
f6db8347 | 416 | select SCHED_INFO |
ca74e92b SN |
417 | help |
418 | Collect information on time spent by a task waiting for system | |
419 | resources like cpu, synchronous block I/O completion and swapping | |
420 | in pages. Such statistics can help in setting a task's priorities | |
421 | relative to other tasks for cpu, io, rss limits etc. | |
422 | ||
423 | Say N if unsure. | |
424 | ||
18f705f4 | 425 | config TASK_XACCT |
19c92399 | 426 | bool "Enable extended accounting over taskstats" |
18f705f4 AD |
427 | depends on TASKSTATS |
428 | help | |
429 | Collect extended task accounting data and send the data | |
430 | to userland for processing over the taskstats interface. | |
431 | ||
432 | Say N if unsure. | |
433 | ||
434 | config TASK_IO_ACCOUNTING | |
19c92399 | 435 | bool "Enable per-task storage I/O accounting" |
18f705f4 AD |
436 | depends on TASK_XACCT |
437 | help | |
438 | Collect information on the number of bytes of storage I/O which this | |
439 | task has caused. | |
440 | ||
441 | Say N if unsure. | |
442 | ||
391dc69c | 443 | endmenu # "CPU/Task time and stats accounting" |
d9817ebe | 444 | |
5c4991e2 FW |
445 | config CPU_ISOLATION |
446 | bool "CPU isolation" | |
414a2dc1 | 447 | depends on SMP || COMPILE_TEST |
2c43838c | 448 | default y |
5c4991e2 FW |
449 | help |
450 | Make sure that CPUs running critical tasks are not disturbed by | |
451 | any source of "noise" such as unbound workqueues, timers, kthreads... | |
2c43838c FW |
452 | Unbound jobs get offloaded to housekeeping CPUs. This is driven by |
453 | the "isolcpus=" boot parameter. | |
454 | ||
455 | Say Y if unsure. | |
5c4991e2 | 456 | |
0af92d46 | 457 | source "kernel/rcu/Kconfig" |
c903ff83 | 458 | |
de5b56ba VG |
459 | config BUILD_BIN2C |
460 | bool | |
461 | default n | |
462 | ||
1da177e4 | 463 | config IKCONFIG |
f2443ab6 | 464 | tristate "Kernel .config support" |
de5b56ba | 465 | select BUILD_BIN2C |
1da177e4 LT |
466 | ---help--- |
467 | This option enables the complete Linux kernel ".config" file | |
468 | contents to be saved in the kernel. It provides documentation | |
469 | of which kernel options are used in a running kernel or in an | |
470 | on-disk kernel. This information can be extracted from the kernel | |
471 | image file with the script scripts/extract-ikconfig and used as | |
472 | input to rebuild the current kernel or to build another kernel. | |
473 | It can also be extracted from a running kernel by reading | |
474 | /proc/config.gz if enabled (below). | |
475 | ||
476 | config IKCONFIG_PROC | |
477 | bool "Enable access to .config through /proc/config.gz" | |
478 | depends on IKCONFIG && PROC_FS | |
479 | ---help--- | |
480 | This option enables access to the kernel configuration file | |
481 | through /proc/config.gz. | |
482 | ||
794543a2 AJS |
483 | config LOG_BUF_SHIFT |
484 | int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" | |
fb39f98d | 485 | range 12 25 |
f17a32e9 | 486 | default 17 |
361e9dfb | 487 | depends on PRINTK |
794543a2 | 488 | help |
23b2899f LR |
489 | Select the minimal kernel log buffer size as a power of 2. |
490 | The final size is affected by LOG_CPU_MAX_BUF_SHIFT config | |
491 | parameter, see below. Any higher size also might be forced | |
492 | by "log_buf_len" boot parameter. | |
493 | ||
f17a32e9 | 494 | Examples: |
23b2899f | 495 | 17 => 128 KB |
f17a32e9 | 496 | 16 => 64 KB |
23b2899f LR |
497 | 15 => 32 KB |
498 | 14 => 16 KB | |
794543a2 AJS |
499 | 13 => 8 KB |
500 | 12 => 4 KB | |
501 | ||
23b2899f LR |
502 | config LOG_CPU_MAX_BUF_SHIFT |
503 | int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" | |
2240a31d | 504 | depends on SMP |
23b2899f LR |
505 | range 0 21 |
506 | default 12 if !BASE_SMALL | |
507 | default 0 if BASE_SMALL | |
361e9dfb | 508 | depends on PRINTK |
23b2899f LR |
509 | help |
510 | This option allows to increase the default ring buffer size | |
511 | according to the number of CPUs. The value defines the contribution | |
512 | of each CPU as a power of 2. The used space is typically only few | |
513 | lines however it might be much more when problems are reported, | |
514 | e.g. backtraces. | |
515 | ||
516 | The increased size means that a new buffer has to be allocated and | |
517 | the original static one is unused. It makes sense only on systems | |
518 | with more CPUs. Therefore this value is used only when the sum of | |
519 | contributions is greater than the half of the default kernel ring | |
520 | buffer as defined by LOG_BUF_SHIFT. The default values are set | |
521 | so that more than 64 CPUs are needed to trigger the allocation. | |
522 | ||
523 | Also this option is ignored when "log_buf_len" kernel parameter is | |
524 | used as it forces an exact (power of two) size of the ring buffer. | |
525 | ||
526 | The number of possible CPUs is used for this computation ignoring | |
5e0d8d59 GU |
527 | hotplugging making the computation optimal for the worst case |
528 | scenario while allowing a simple algorithm to be used from bootup. | |
23b2899f LR |
529 | |
530 | Examples shift values and their meaning: | |
531 | 17 => 128 KB for each CPU | |
532 | 16 => 64 KB for each CPU | |
533 | 15 => 32 KB for each CPU | |
534 | 14 => 16 KB for each CPU | |
535 | 13 => 8 KB for each CPU | |
536 | 12 => 4 KB for each CPU | |
537 | ||
f92bac3b SS |
538 | config PRINTK_SAFE_LOG_BUF_SHIFT |
539 | int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)" | |
427934b8 PM |
540 | range 10 21 |
541 | default 13 | |
f92bac3b | 542 | depends on PRINTK |
427934b8 | 543 | help |
f92bac3b SS |
544 | Select the size of an alternate printk per-CPU buffer where messages |
545 | printed from usafe contexts are temporary stored. One example would | |
546 | be NMI messages, another one - printk recursion. The messages are | |
547 | copied to the main log buffer in a safe context to avoid a deadlock. | |
548 | The value defines the size as a power of 2. | |
427934b8 | 549 | |
f92bac3b | 550 | Those messages are rare and limited. The largest one is when |
427934b8 PM |
551 | a backtrace is printed. It usually fits into 4KB. Select |
552 | 8KB if you want to be on the safe side. | |
553 | ||
554 | Examples: | |
555 | 17 => 128 KB for each CPU | |
556 | 16 => 64 KB for each CPU | |
557 | 15 => 32 KB for each CPU | |
558 | 14 => 16 KB for each CPU | |
559 | 13 => 8 KB for each CPU | |
560 | 12 => 4 KB for each CPU | |
561 | ||
a5574cf6 IM |
562 | # |
563 | # Architectures with an unreliable sched_clock() should select this: | |
564 | # | |
565 | config HAVE_UNSTABLE_SCHED_CLOCK | |
566 | bool | |
567 | ||
38ff87f7 SB |
568 | config GENERIC_SCHED_CLOCK |
569 | bool | |
570 | ||
be3a7284 AA |
571 | # |
572 | # For architectures that want to enable the support for NUMA-affine scheduler | |
573 | # balancing logic: | |
574 | # | |
575 | config ARCH_SUPPORTS_NUMA_BALANCING | |
576 | bool | |
577 | ||
72b252ae MG |
578 | # |
579 | # For architectures that prefer to flush all TLBs after a number of pages | |
580 | # are unmapped instead of sending one IPI per page to flush. The architecture | |
581 | # must provide guarantees on what happens if a clean TLB cache entry is | |
582 | # written after the unmap. Details are in mm/rmap.c near the check for | |
583 | # should_defer_flush. The architecture should also consider if the full flush | |
584 | # and the refill costs are offset by the savings of sending fewer IPIs. | |
585 | config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH | |
586 | bool | |
587 | ||
be5e610c PZ |
588 | # |
589 | # For architectures that know their GCC __int128 support is sound | |
590 | # | |
591 | config ARCH_SUPPORTS_INT128 | |
592 | bool | |
593 | ||
be3a7284 AA |
594 | # For architectures that (ab)use NUMA to represent different memory regions |
595 | # all cpu-local but of different latencies, such as SuperH. | |
596 | # | |
597 | config ARCH_WANT_NUMA_VARIABLE_LOCALITY | |
598 | bool | |
599 | ||
be3a7284 AA |
600 | config NUMA_BALANCING |
601 | bool "Memory placement aware NUMA scheduler" | |
be3a7284 AA |
602 | depends on ARCH_SUPPORTS_NUMA_BALANCING |
603 | depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY | |
604 | depends on SMP && NUMA && MIGRATION | |
605 | help | |
606 | This option adds support for automatic NUMA aware memory/task placement. | |
607 | The mechanism is quite primitive and is based on migrating memory when | |
6d56a410 | 608 | it has references to the node the task is running on. |
be3a7284 AA |
609 | |
610 | This system will be inactive on UMA systems. | |
611 | ||
6f7c97e8 AK |
612 | config NUMA_BALANCING_DEFAULT_ENABLED |
613 | bool "Automatically enable NUMA aware memory/task placement" | |
614 | default y | |
615 | depends on NUMA_BALANCING | |
616 | help | |
617 | If set, automatic NUMA balancing will be enabled if running on a NUMA | |
618 | machine. | |
619 | ||
23964d2d | 620 | menuconfig CGROUPS |
6341e62b | 621 | bool "Control Group support" |
2bd59d48 | 622 | select KERNFS |
5cdc38f9 | 623 | help |
23964d2d | 624 | This option adds support for grouping sets of processes together, for |
5cdc38f9 KH |
625 | use with process control subsystems such as Cpusets, CFS, memory |
626 | controls or device isolation. | |
627 | See | |
5cdc38f9 | 628 | - Documentation/scheduler/sched-design-CFS.txt (CFS) |
9991a9c8 | 629 | - Documentation/cgroup-v1/ (features for grouping, isolation |
45ce80fb | 630 | and resource control) |
5cdc38f9 KH |
631 | |
632 | Say N if unsure. | |
633 | ||
23964d2d LZ |
634 | if CGROUPS |
635 | ||
3e32cb2e JW |
636 | config PAGE_COUNTER |
637 | bool | |
638 | ||
c255a458 | 639 | config MEMCG |
a0166ec4 | 640 | bool "Memory controller" |
3e32cb2e | 641 | select PAGE_COUNTER |
79bd9814 | 642 | select EVENTFD |
00f0b825 | 643 | help |
a0166ec4 | 644 | Provides control over the memory footprint of tasks in a cgroup. |
00f0b825 | 645 | |
c255a458 | 646 | config MEMCG_SWAP |
a0166ec4 | 647 | bool "Swap controller" |
c255a458 | 648 | depends on MEMCG && SWAP |
c077719b | 649 | help |
a0166ec4 JW |
650 | Provides control over the swap space consumed by tasks in a cgroup. |
651 | ||
c255a458 | 652 | config MEMCG_SWAP_ENABLED |
a0166ec4 | 653 | bool "Swap controller enabled by default" |
c255a458 | 654 | depends on MEMCG_SWAP |
a42c390c MH |
655 | default y |
656 | help | |
657 | Memory Resource Controller Swap Extension comes with its price in | |
658 | a bigger memory consumption. General purpose distribution kernels | |
43d547f9 | 659 | which want to enable the feature but keep it disabled by default |
07555ac1 | 660 | and let the user enable it by swapaccount=1 boot command line |
a42c390c MH |
661 | parameter should have this option unselected. |
662 | For those who want to have the feature enabled by default should | |
663 | select this option (if, for some reason, they need to disable it | |
00a66d29 | 664 | then swapaccount=0 does the trick). |
c077719b | 665 | |
6bf024e6 JW |
666 | config BLK_CGROUP |
667 | bool "IO controller" | |
668 | depends on BLOCK | |
2bc64a20 | 669 | default n |
6bf024e6 JW |
670 | ---help--- |
671 | Generic block IO controller cgroup interface. This is the common | |
672 | cgroup interface which should be used by various IO controlling | |
673 | policies. | |
2bc64a20 | 674 | |
6bf024e6 JW |
675 | Currently, CFQ IO scheduler uses it to recognize task groups and |
676 | control disk bandwidth allocation (proportional time slice allocation) | |
677 | to such task groups. It is also used by bio throttling logic in | |
678 | block layer to implement upper limit in IO rates on a device. | |
e5d1367f | 679 | |
6bf024e6 JW |
680 | This option only enables generic Block IO controller infrastructure. |
681 | One needs to also enable actual IO controlling logic/policy. For | |
682 | enabling proportional weight division of disk bandwidth in CFQ, set | |
683 | CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set | |
684 | CONFIG_BLK_DEV_THROTTLING=y. | |
685 | ||
9991a9c8 | 686 | See Documentation/cgroup-v1/blkio-controller.txt for more information. |
6bf024e6 JW |
687 | |
688 | config DEBUG_BLK_CGROUP | |
689 | bool "IO controller debugging" | |
690 | depends on BLK_CGROUP | |
691 | default n | |
692 | ---help--- | |
693 | Enable some debugging help. Currently it exports additional stat | |
694 | files in a cgroup which can be useful for debugging. | |
695 | ||
696 | config CGROUP_WRITEBACK | |
697 | bool | |
698 | depends on MEMCG && BLK_CGROUP | |
699 | default y | |
e5d1367f | 700 | |
7c941438 | 701 | menuconfig CGROUP_SCHED |
a0166ec4 | 702 | bool "CPU controller" |
7c941438 DG |
703 | default n |
704 | help | |
705 | This feature lets CPU scheduler recognize task groups and control CPU | |
706 | bandwidth allocation to such task groups. It uses cgroups to group | |
707 | tasks. | |
708 | ||
709 | if CGROUP_SCHED | |
710 | config FAIR_GROUP_SCHED | |
711 | bool "Group scheduling for SCHED_OTHER" | |
712 | depends on CGROUP_SCHED | |
713 | default CGROUP_SCHED | |
714 | ||
ab84d31e PT |
715 | config CFS_BANDWIDTH |
716 | bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" | |
ab84d31e PT |
717 | depends on FAIR_GROUP_SCHED |
718 | default n | |
719 | help | |
720 | This option allows users to define CPU bandwidth rates (limits) for | |
721 | tasks running within the fair group scheduler. Groups with no limit | |
722 | set are considered to be unconstrained and will run with no | |
723 | restriction. | |
cd33d880 | 724 | See Documentation/scheduler/sched-bwc.txt for more information. |
ab84d31e | 725 | |
7c941438 DG |
726 | config RT_GROUP_SCHED |
727 | bool "Group scheduling for SCHED_RR/FIFO" | |
7c941438 DG |
728 | depends on CGROUP_SCHED |
729 | default n | |
730 | help | |
731 | This feature lets you explicitly allocate real CPU bandwidth | |
32bd7eb5 | 732 | to task groups. If enabled, it will also make it impossible to |
7c941438 DG |
733 | schedule realtime tasks for non-root users until you allocate |
734 | realtime bandwidth for them. | |
735 | See Documentation/scheduler/sched-rt-group.txt for more information. | |
736 | ||
737 | endif #CGROUP_SCHED | |
738 | ||
6bf024e6 JW |
739 | config CGROUP_PIDS |
740 | bool "PIDs controller" | |
741 | help | |
742 | Provides enforcement of process number limits in the scope of a | |
743 | cgroup. Any attempt to fork more processes than is allowed in the | |
744 | cgroup will fail. PIDs are fundamentally a global resource because it | |
745 | is fairly trivial to reach PID exhaustion before you reach even a | |
746 | conservative kmemcg limit. As a result, it is possible to grind a | |
747 | system to halt without being limited by other cgroup policies. The | |
6cc578df | 748 | PIDs controller is designed to stop this from happening. |
6bf024e6 JW |
749 | |
750 | It should be noted that organisational operations (such as attaching | |
6cc578df | 751 | to a cgroup hierarchy will *not* be blocked by the PIDs controller), |
6bf024e6 JW |
752 | since the PIDs limit only affects a process's ability to fork, not to |
753 | attach to a cgroup. | |
754 | ||
39d3e758 PP |
755 | config CGROUP_RDMA |
756 | bool "RDMA controller" | |
757 | help | |
758 | Provides enforcement of RDMA resources defined by IB stack. | |
759 | It is fairly easy for consumers to exhaust RDMA resources, which | |
760 | can result into resource unavailability to other consumers. | |
761 | RDMA controller is designed to stop this from happening. | |
762 | Attaching processes with active RDMA resources to the cgroup | |
763 | hierarchy is allowed even if can cross the hierarchy's limit. | |
764 | ||
6bf024e6 JW |
765 | config CGROUP_FREEZER |
766 | bool "Freezer controller" | |
767 | help | |
768 | Provides a way to freeze and unfreeze all tasks in a | |
769 | cgroup. | |
770 | ||
489c2a20 JW |
771 | This option affects the ORIGINAL cgroup interface. The cgroup2 memory |
772 | controller includes important in-kernel memory consumers per default. | |
773 | ||
774 | If you're using cgroup2, say N. | |
775 | ||
6bf024e6 JW |
776 | config CGROUP_HUGETLB |
777 | bool "HugeTLB controller" | |
778 | depends on HUGETLB_PAGE | |
779 | select PAGE_COUNTER | |
afc24d49 | 780 | default n |
6bf024e6 JW |
781 | help |
782 | Provides a cgroup controller for HugeTLB pages. | |
783 | When you enable this, you can put a per cgroup limit on HugeTLB usage. | |
784 | The limit is enforced during page fault. Since HugeTLB doesn't | |
785 | support page reclaim, enforcing the limit at page fault time implies | |
786 | that, the application will get SIGBUS signal if it tries to access | |
787 | HugeTLB pages beyond its limit. This requires the application to know | |
788 | beforehand how much HugeTLB pages it would require for its use. The | |
789 | control group is tracked in the third page lru pointer. This means | |
790 | that we cannot use the controller with huge page less than 3 pages. | |
afc24d49 | 791 | |
6bf024e6 JW |
792 | config CPUSETS |
793 | bool "Cpuset controller" | |
e1d4eeec | 794 | depends on SMP |
6bf024e6 JW |
795 | help |
796 | This option will let you create and manage CPUSETs which | |
797 | allow dynamically partitioning a system into sets of CPUs and | |
798 | Memory Nodes and assigning tasks to run only within those sets. | |
799 | This is primarily useful on large SMP or NUMA systems. | |
afc24d49 | 800 | |
6bf024e6 | 801 | Say N if unsure. |
afc24d49 | 802 | |
6bf024e6 JW |
803 | config PROC_PID_CPUSET |
804 | bool "Include legacy /proc/<pid>/cpuset file" | |
805 | depends on CPUSETS | |
806 | default y | |
afc24d49 | 807 | |
6bf024e6 JW |
808 | config CGROUP_DEVICE |
809 | bool "Device controller" | |
810 | help | |
811 | Provides a cgroup controller implementing whitelists for | |
812 | devices which a process in the cgroup can mknod or open. | |
813 | ||
814 | config CGROUP_CPUACCT | |
815 | bool "Simple CPU accounting controller" | |
816 | help | |
817 | Provides a simple controller for monitoring the | |
818 | total CPU consumed by the tasks in a cgroup. | |
819 | ||
820 | config CGROUP_PERF | |
821 | bool "Perf controller" | |
822 | depends on PERF_EVENTS | |
823 | help | |
824 | This option extends the perf per-cpu mode to restrict monitoring | |
825 | to threads which belong to the cgroup specified and run on the | |
826 | designated cpu. | |
827 | ||
828 | Say N if unsure. | |
829 | ||
30070984 DM |
830 | config CGROUP_BPF |
831 | bool "Support for eBPF programs attached to cgroups" | |
483c4933 AL |
832 | depends on BPF_SYSCALL |
833 | select SOCK_CGROUP_DATA | |
30070984 DM |
834 | help |
835 | Allow attaching eBPF programs to a cgroup using the bpf(2) | |
836 | syscall command BPF_PROG_ATTACH. | |
837 | ||
838 | In which context these programs are accessed depends on the type | |
839 | of attachment. For instance, programs that are attached using | |
840 | BPF_CGROUP_INET_INGRESS will be executed on the ingress path of | |
841 | inet sockets. | |
842 | ||
6bf024e6 | 843 | config CGROUP_DEBUG |
23b0be48 | 844 | bool "Debug controller" |
afc24d49 | 845 | default n |
23b0be48 | 846 | depends on DEBUG_KERNEL |
6bf024e6 JW |
847 | help |
848 | This option enables a simple controller that exports | |
23b0be48 WL |
849 | debugging information about the cgroups framework. This |
850 | controller is for control cgroup debugging only. Its | |
851 | interfaces are not stable. | |
afc24d49 | 852 | |
6bf024e6 | 853 | Say N. |
89e9b9e0 | 854 | |
73b35147 AB |
855 | config SOCK_CGROUP_DATA |
856 | bool | |
857 | default n | |
858 | ||
23964d2d | 859 | endif # CGROUPS |
c077719b | 860 | |
8dd2a82c | 861 | menuconfig NAMESPACES |
6a108a14 | 862 | bool "Namespaces support" if EXPERT |
2813893f | 863 | depends on MULTIUSER |
6a108a14 | 864 | default !EXPERT |
c5289a69 PE |
865 | help |
866 | Provides the way to make tasks work with different objects using | |
867 | the same id. For example same IPC id may refer to different objects | |
868 | or same user id or pid may refer to different tasks when used in | |
869 | different namespaces. | |
870 | ||
8dd2a82c DL |
871 | if NAMESPACES |
872 | ||
58bfdd6d PE |
873 | config UTS_NS |
874 | bool "UTS namespace" | |
17a6d441 | 875 | default y |
58bfdd6d PE |
876 | help |
877 | In this namespace tasks see different info provided with the | |
878 | uname() system call | |
879 | ||
ae5e1b22 PE |
880 | config IPC_NS |
881 | bool "IPC namespace" | |
8dd2a82c | 882 | depends on (SYSVIPC || POSIX_MQUEUE) |
17a6d441 | 883 | default y |
ae5e1b22 PE |
884 | help |
885 | In this namespace tasks work with IPC ids which correspond to | |
614b84cf | 886 | different IPC objects in different namespaces. |
ae5e1b22 | 887 | |
aee16ce7 | 888 | config USER_NS |
19c92399 | 889 | bool "User namespace" |
5673a94c | 890 | default n |
aee16ce7 PE |
891 | help |
892 | This allows containers, i.e. vservers, to use user namespaces | |
893 | to provide different user info for different servers. | |
e11f0ae3 EB |
894 | |
895 | When user namespaces are enabled in the kernel it is | |
d886f4e4 JW |
896 | recommended that the MEMCG option also be enabled and that |
897 | user-space use the memory control groups to limit the amount | |
898 | of memory a memory unprivileged users can use. | |
e11f0ae3 | 899 | |
aee16ce7 PE |
900 | If unsure, say N. |
901 | ||
74bd59bb | 902 | config PID_NS |
9bd38c2c | 903 | bool "PID Namespaces" |
17a6d441 | 904 | default y |
74bd59bb | 905 | help |
12d2b8f9 | 906 | Support process id namespaces. This allows having multiple |
692105b8 | 907 | processes with the same pid as long as they are in different |
74bd59bb PE |
908 | pid namespaces. This is a building block of containers. |
909 | ||
d6eb633f MH |
910 | config NET_NS |
911 | bool "Network namespace" | |
8dd2a82c | 912 | depends on NET |
17a6d441 | 913 | default y |
d6eb633f MH |
914 | help |
915 | Allow user space to create what appear to be multiple instances | |
916 | of the network stack. | |
917 | ||
8dd2a82c DL |
918 | endif # NAMESPACES |
919 | ||
5091faa4 MG |
920 | config SCHED_AUTOGROUP |
921 | bool "Automatic process group scheduling" | |
5091faa4 MG |
922 | select CGROUPS |
923 | select CGROUP_SCHED | |
924 | select FAIR_GROUP_SCHED | |
925 | help | |
926 | This option optimizes the scheduler for common desktop workloads by | |
927 | automatically creating and populating task groups. This separation | |
928 | of workloads isolates aggressive CPU burners (like build jobs) from | |
929 | desktop applications. Task group autogeneration is currently based | |
930 | upon task session. | |
931 | ||
7af37bec | 932 | config SYSFS_DEPRECATED |
5d6a4ea5 | 933 | bool "Enable deprecated sysfs features to support old userspace tools" |
7af37bec DL |
934 | depends on SYSFS |
935 | default n | |
936 | help | |
937 | This option adds code that switches the layout of the "block" class | |
938 | devices, to not show up in /sys/class/block/, but only in | |
939 | /sys/block/. | |
940 | ||
941 | This switch is only active when the sysfs.deprecated=1 boot option is | |
942 | passed or the SYSFS_DEPRECATED_V2 option is set. | |
943 | ||
944 | This option allows new kernels to run on old distributions and tools, | |
945 | which might get confused by /sys/class/block/. Since 2007/2008 all | |
946 | major distributions and tools handle this just fine. | |
947 | ||
948 | Recent distributions and userspace tools after 2009/2010 depend on | |
949 | the existence of /sys/class/block/, and will not work with this | |
950 | option enabled. | |
951 | ||
952 | Only if you are using a new kernel on an old distribution, you might | |
953 | need to say Y here. | |
954 | ||
955 | config SYSFS_DEPRECATED_V2 | |
5d6a4ea5 | 956 | bool "Enable deprecated sysfs features by default" |
7af37bec DL |
957 | default n |
958 | depends on SYSFS | |
959 | depends on SYSFS_DEPRECATED | |
960 | help | |
961 | Enable deprecated sysfs by default. | |
962 | ||
963 | See the CONFIG_SYSFS_DEPRECATED option for more details about this | |
964 | option. | |
965 | ||
966 | Only if you are using a new kernel on an old distribution, you might | |
967 | need to say Y here. Even then, odds are you would not need it | |
968 | enabled, you can always pass the boot option if absolutely necessary. | |
969 | ||
970 | config RELAY | |
971 | bool "Kernel->user space relay support (formerly relayfs)" | |
26b5679e | 972 | select IRQ_WORK |
7af37bec DL |
973 | help |
974 | This option enables support for relay interface support in | |
975 | certain file systems (such as debugfs). | |
976 | It is designed to provide an efficient mechanism for tools and | |
977 | facilities to relay large amounts of data from kernel space to | |
978 | user space. | |
979 | ||
980 | If unsure, say N. | |
981 | ||
f991633d DG |
982 | config BLK_DEV_INITRD |
983 | bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" | |
f991633d DG |
984 | help |
985 | The initial RAM filesystem is a ramfs which is loaded by the | |
986 | boot loader (loadlin or lilo) and that is mounted as root | |
987 | before the normal boot procedure. It is typically used to | |
988 | load modules needed to mount the "real" root file system, | |
8c27ceff | 989 | etc. See <file:Documentation/admin-guide/initrd.rst> for details. |
f991633d DG |
990 | |
991 | If RAM disk support (BLK_DEV_RAM) is also included, this | |
992 | also enables initial RAM disk (initrd) support and adds | |
993 | 15 Kbytes (more on some other architectures) to the kernel size. | |
994 | ||
995 | If unsure say Y. | |
996 | ||
c33df4ea JPS |
997 | if BLK_DEV_INITRD |
998 | ||
dbec4866 SR |
999 | source "usr/Kconfig" |
1000 | ||
c33df4ea JPS |
1001 | endif |
1002 | ||
877417e6 AB |
1003 | choice |
1004 | prompt "Compiler optimization level" | |
2cc3ce24 | 1005 | default CC_OPTIMIZE_FOR_PERFORMANCE |
877417e6 AB |
1006 | |
1007 | config CC_OPTIMIZE_FOR_PERFORMANCE | |
1008 | bool "Optimize for performance" | |
1009 | help | |
1010 | This is the default optimization level for the kernel, building | |
1011 | with the "-O2" compiler flag for best performance and most | |
1012 | helpful compile-time warnings. | |
1013 | ||
c45b4f1f | 1014 | config CC_OPTIMIZE_FOR_SIZE |
96fffeb4 | 1015 | bool "Optimize for size" |
c45b4f1f | 1016 | help |
31a4af7f MY |
1017 | Enabling this option will pass "-Os" instead of "-O2" to |
1018 | your compiler resulting in a smaller kernel. | |
c45b4f1f | 1019 | |
3a55fb0d | 1020 | If unsure, say N. |
c45b4f1f | 1021 | |
877417e6 AB |
1022 | endchoice |
1023 | ||
5d20ee31 NP |
1024 | config HAVE_LD_DEAD_CODE_DATA_ELIMINATION |
1025 | bool | |
1026 | help | |
1027 | This requires that the arch annotates or otherwise protects | |
1028 | its external entry points from being discarded. Linker scripts | |
1029 | must also merge .text.*, .data.*, and .bss.* correctly into | |
1030 | output sections. Care must be taken not to pull in unrelated | |
1031 | sections (e.g., '.text.init'). Typically '.' in section names | |
1032 | is used to distinguish them from label names / C identifiers. | |
1033 | ||
1034 | config LD_DEAD_CODE_DATA_ELIMINATION | |
1035 | bool "Dead code and data elimination (EXPERIMENTAL)" | |
1036 | depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION | |
1037 | depends on EXPERT | |
1038 | help | |
1039 | Select this if the architecture wants to do dead code and | |
1040 | data elimination with the linker by compiling with | |
1041 | -ffunction-sections -fdata-sections, and linking with | |
1042 | --gc-sections. | |
1043 | ||
1044 | This can reduce on disk and in-memory size of the kernel | |
1045 | code and static data, particularly for small configs and | |
1046 | on small systems. This has the possibility of introducing | |
1047 | silently broken kernel if the required annotations are not | |
1048 | present. This option is not well tested yet, so use at your | |
1049 | own risk. | |
1050 | ||
0847062a RD |
1051 | config SYSCTL |
1052 | bool | |
1053 | ||
b943c460 RD |
1054 | config ANON_INODES |
1055 | bool | |
1056 | ||
657a5209 MF |
1057 | config HAVE_UID16 |
1058 | bool | |
1059 | ||
1060 | config SYSCTL_EXCEPTION_TRACE | |
1061 | bool | |
1062 | help | |
1063 | Enable support for /proc/sys/debug/exception-trace. | |
1064 | ||
1065 | config SYSCTL_ARCH_UNALIGN_NO_WARN | |
1066 | bool | |
1067 | help | |
1068 | Enable support for /proc/sys/kernel/ignore-unaligned-usertrap | |
1069 | Allows arch to define/use @no_unaligned_warning to possibly warn | |
1070 | about unaligned access emulation going on under the hood. | |
1071 | ||
1072 | config SYSCTL_ARCH_UNALIGN_ALLOW | |
1073 | bool | |
1074 | help | |
1075 | Enable support for /proc/sys/kernel/unaligned-trap | |
1076 | Allows arches to define/use @unaligned_enabled to runtime toggle | |
1077 | the unaligned access emulation. | |
1078 | see arch/parisc/kernel/unaligned.c for reference | |
1079 | ||
657a5209 MF |
1080 | config HAVE_PCSPKR_PLATFORM |
1081 | bool | |
1082 | ||
f89b7755 AS |
1083 | # interpreter that classic socket filters depend on |
1084 | config BPF | |
1085 | bool | |
1086 | ||
6a108a14 DR |
1087 | menuconfig EXPERT |
1088 | bool "Configure standard kernel features (expert users)" | |
f505c553 JT |
1089 | # Unhide debug options, to make the on-by-default options visible |
1090 | select DEBUG_KERNEL | |
1da177e4 LT |
1091 | help |
1092 | This option allows certain base kernel options and settings | |
1093 | to be disabled or tweaked. This is for specialized | |
1094 | environments which can tolerate a "non-standard" kernel. | |
1095 | Only use this if you really know what you are doing. | |
1096 | ||
ae81f9e3 | 1097 | config UID16 |
6a108a14 | 1098 | bool "Enable 16-bit UID system calls" if EXPERT |
2813893f | 1099 | depends on HAVE_UID16 && MULTIUSER |
ae81f9e3 CE |
1100 | default y |
1101 | help | |
1102 | This enables the legacy 16-bit UID syscall wrappers. | |
1103 | ||
2813893f IM |
1104 | config MULTIUSER |
1105 | bool "Multiple users, groups and capabilities support" if EXPERT | |
1106 | default y | |
1107 | help | |
1108 | This option enables support for non-root users, groups and | |
1109 | capabilities. | |
1110 | ||
1111 | If you say N here, all processes will run with UID 0, GID 0, and all | |
1112 | possible capabilities. Saying N here also compiles out support for | |
1113 | system calls related to UIDs, GIDs, and capabilities, such as setuid, | |
1114 | setgid, and capset. | |
1115 | ||
1116 | If unsure, say Y here. | |
1117 | ||
f6187769 FF |
1118 | config SGETMASK_SYSCALL |
1119 | bool "sgetmask/ssetmask syscalls support" if EXPERT | |
a687a533 | 1120 | def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH |
f6187769 FF |
1121 | ---help--- |
1122 | sys_sgetmask and sys_ssetmask are obsolete system calls | |
1123 | no longer supported in libc but still enabled by default in some | |
1124 | architectures. | |
1125 | ||
1126 | If unsure, leave the default option here. | |
1127 | ||
6af9f7bf FF |
1128 | config SYSFS_SYSCALL |
1129 | bool "Sysfs syscall support" if EXPERT | |
1130 | default y | |
1131 | ---help--- | |
1132 | sys_sysfs is an obsolete system call no longer supported in libc. | |
1133 | Note that disabling this option is more secure but might break | |
1134 | compatibility with some systems. | |
1135 | ||
1136 | If unsure say Y here. | |
1137 | ||
b89a8171 | 1138 | config SYSCTL_SYSCALL |
6a108a14 | 1139 | bool "Sysctl syscall support" if EXPERT |
26a7034b | 1140 | depends on PROC_SYSCTL |
c736de60 | 1141 | default n |
b89a8171 | 1142 | select SYSCTL |
ae81f9e3 | 1143 | ---help--- |
13bb7e37 EB |
1144 | sys_sysctl uses binary paths that have been found challenging |
1145 | to properly maintain and use. The interface in /proc/sys | |
1146 | using paths with ascii names is now the primary path to this | |
1147 | information. | |
b89a8171 | 1148 | |
13bb7e37 EB |
1149 | Almost nothing using the binary sysctl interface so if you are |
1150 | trying to save some space it is probably safe to disable this, | |
1151 | making your kernel marginally smaller. | |
b89a8171 | 1152 | |
c736de60 | 1153 | If unsure say N here. |
ae81f9e3 | 1154 | |
d1b069f5 RD |
1155 | config FHANDLE |
1156 | bool "open by fhandle syscalls" if EXPERT | |
1157 | select EXPORTFS | |
1158 | default y | |
1159 | help | |
1160 | If you say Y here, a user level program will be able to map | |
1161 | file names to handle and then later use the handle for | |
1162 | different file system operations. This is useful in implementing | |
1163 | userspace file servers, which now track files using handles instead | |
1164 | of names. The handle would remain the same even if file names | |
1165 | get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) | |
1166 | syscalls. | |
1167 | ||
baa73d9e NP |
1168 | config POSIX_TIMERS |
1169 | bool "Posix Clocks & timers" if EXPERT | |
1170 | default y | |
1171 | help | |
1172 | This includes native support for POSIX timers to the kernel. | |
1173 | Some embedded systems have no use for them and therefore they | |
1174 | can be configured out to reduce the size of the kernel image. | |
1175 | ||
1176 | When this option is disabled, the following syscalls won't be | |
1177 | available: timer_create, timer_gettime: timer_getoverrun, | |
1178 | timer_settime, timer_delete, clock_adjtime, getitimer, | |
1179 | setitimer, alarm. Furthermore, the clock_settime, clock_gettime, | |
1180 | clock_getres and clock_nanosleep syscalls will be limited to | |
1181 | CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. | |
1182 | ||
1183 | If unsure say y. | |
1184 | ||
d59745ce MM |
1185 | config PRINTK |
1186 | default y | |
6a108a14 | 1187 | bool "Enable support for printk" if EXPERT |
74876a98 | 1188 | select IRQ_WORK |
d59745ce MM |
1189 | help |
1190 | This option enables normal printk support. Removing it | |
1191 | eliminates most of the message strings from the kernel image | |
1192 | and makes the kernel more or less silent. As this makes it | |
1193 | very difficult to diagnose system problems, saying N here is | |
1194 | strongly discouraged. | |
1195 | ||
42a0bb3f PM |
1196 | config PRINTK_NMI |
1197 | def_bool y | |
1198 | depends on PRINTK | |
1199 | depends on HAVE_NMI | |
1200 | ||
c8538a7a | 1201 | config BUG |
6a108a14 | 1202 | bool "BUG() support" if EXPERT |
c8538a7a MM |
1203 | default y |
1204 | help | |
1205 | Disabling this option eliminates support for BUG and WARN, reducing | |
1206 | the size of your kernel image and potentially quietly ignoring | |
1207 | numerous fatal conditions. You should only consider disabling this | |
1208 | option for embedded systems with no facilities for reporting errors. | |
1209 | Just say Y. | |
1210 | ||
708e9a79 | 1211 | config ELF_CORE |
046d662f | 1212 | depends on COREDUMP |
708e9a79 | 1213 | default y |
6a108a14 | 1214 | bool "Enable ELF core dumps" if EXPERT |
708e9a79 MM |
1215 | help |
1216 | Enable support for generating core dumps. Disabling saves about 4k. | |
1217 | ||
8761f1ab | 1218 | |
e5e1d3cb | 1219 | config PCSPKR_PLATFORM |
6a108a14 | 1220 | bool "Enable PC-Speaker support" if EXPERT |
8761f1ab | 1221 | depends on HAVE_PCSPKR_PLATFORM |
15f304b6 | 1222 | select I8253_LOCK |
e5e1d3cb SS |
1223 | default y |
1224 | help | |
1225 | This option allows to disable the internal PC-Speaker | |
1226 | support, saving some memory. | |
1227 | ||
1da177e4 LT |
1228 | config BASE_FULL |
1229 | default y | |
6a108a14 | 1230 | bool "Enable full-sized data structures for core" if EXPERT |
1da177e4 LT |
1231 | help |
1232 | Disabling this option reduces the size of miscellaneous core | |
1233 | kernel data structures. This saves memory on small machines, | |
1234 | but may reduce performance. | |
1235 | ||
1236 | config FUTEX | |
6a108a14 | 1237 | bool "Enable futex support" if EXPERT |
1da177e4 | 1238 | default y |
bc2eecd7 | 1239 | imply RT_MUTEXES |
1da177e4 LT |
1240 | help |
1241 | Disabling this option will cause the kernel to be built without | |
1242 | support for "fast userspace mutexes". The resulting kernel may not | |
1243 | run glibc-based applications correctly. | |
1244 | ||
bc2eecd7 NP |
1245 | config FUTEX_PI |
1246 | bool | |
1247 | depends on FUTEX && RT_MUTEXES | |
1248 | default y | |
1249 | ||
03b8c7b6 HC |
1250 | config HAVE_FUTEX_CMPXCHG |
1251 | bool | |
62b4d204 | 1252 | depends on FUTEX |
03b8c7b6 HC |
1253 | help |
1254 | Architectures should select this if futex_atomic_cmpxchg_inatomic() | |
1255 | is implemented and always working. This removes a couple of runtime | |
1256 | checks. | |
1257 | ||
1da177e4 | 1258 | config EPOLL |
6a108a14 | 1259 | bool "Enable eventpoll support" if EXPERT |
1da177e4 | 1260 | default y |
448e3cee | 1261 | select ANON_INODES |
1da177e4 LT |
1262 | help |
1263 | Disabling this option will cause the kernel to be built without | |
1264 | support for epoll family of system calls. | |
1265 | ||
fba2afaa | 1266 | config SIGNALFD |
6a108a14 | 1267 | bool "Enable signalfd() system call" if EXPERT |
448e3cee | 1268 | select ANON_INODES |
fba2afaa DL |
1269 | default y |
1270 | help | |
1271 | Enable the signalfd() system call that allows to receive signals | |
1272 | on a file descriptor. | |
1273 | ||
1274 | If unsure, say Y. | |
1275 | ||
b215e283 | 1276 | config TIMERFD |
6a108a14 | 1277 | bool "Enable timerfd() system call" if EXPERT |
448e3cee | 1278 | select ANON_INODES |
b215e283 DL |
1279 | default y |
1280 | help | |
1281 | Enable the timerfd() system call that allows to receive timer | |
1282 | events on a file descriptor. | |
1283 | ||
1284 | If unsure, say Y. | |
1285 | ||
e1ad7468 | 1286 | config EVENTFD |
6a108a14 | 1287 | bool "Enable eventfd() system call" if EXPERT |
448e3cee | 1288 | select ANON_INODES |
e1ad7468 DL |
1289 | default y |
1290 | help | |
1291 | Enable the eventfd() system call that allows to receive both | |
1292 | kernel notification (ie. KAIO) or userspace notifications. | |
1293 | ||
1294 | If unsure, say Y. | |
1295 | ||
1da177e4 | 1296 | config SHMEM |
6a108a14 | 1297 | bool "Use full shmem filesystem" if EXPERT |
1da177e4 LT |
1298 | default y |
1299 | depends on MMU | |
1300 | help | |
1301 | The shmem is an internal filesystem used to manage shared memory. | |
1302 | It is backed by swap and manages resource limits. It is also exported | |
1303 | to userspace as tmpfs if TMPFS is enabled. Disabling this | |
1304 | option replaces shmem and tmpfs with the much simpler ramfs code, | |
1305 | which may be appropriate on small systems without swap. | |
1306 | ||
ebf3f09c | 1307 | config AIO |
6a108a14 | 1308 | bool "Enable AIO support" if EXPERT |
ebf3f09c TP |
1309 | default y |
1310 | help | |
1311 | This option enables POSIX asynchronous I/O which may by used | |
657a5209 MF |
1312 | by some high performance threaded applications. Disabling |
1313 | this option saves about 7k. | |
1314 | ||
d3ac21ca JT |
1315 | config ADVISE_SYSCALLS |
1316 | bool "Enable madvise/fadvise syscalls" if EXPERT | |
1317 | default y | |
1318 | help | |
1319 | This option enables the madvise and fadvise syscalls, used by | |
1320 | applications to advise the kernel about their future memory or file | |
1321 | usage, improving performance. If building an embedded system where no | |
1322 | applications use these syscalls, you can disable this option to save | |
1323 | space. | |
1324 | ||
5b25b13a MD |
1325 | config MEMBARRIER |
1326 | bool "Enable membarrier() system call" if EXPERT | |
1327 | default y | |
1328 | help | |
1329 | Enable the membarrier() system call that allows issuing memory | |
1330 | barriers across all running threads, which can be used to distribute | |
1331 | the cost of user-space memory barriers asymmetrically by transforming | |
1332 | pairs of memory barriers into pairs consisting of membarrier() and a | |
1333 | compiler barrier. | |
1334 | ||
1335 | If unsure, say Y. | |
1336 | ||
d1b069f5 RD |
1337 | config CHECKPOINT_RESTORE |
1338 | bool "Checkpoint/restore support" if EXPERT | |
1339 | select PROC_CHILDREN | |
1340 | default n | |
1341 | help | |
1342 | Enables additional kernel features in a sake of checkpoint/restore. | |
1343 | In particular it adds auxiliary prctl codes to setup process text, | |
1344 | data and heap segment sizes, and a few additional /proc filesystem | |
1345 | entries. | |
1346 | ||
1347 | If unsure, say N here. | |
1348 | ||
1349 | config KALLSYMS | |
1350 | bool "Load all symbols for debugging/ksymoops" if EXPERT | |
1351 | default y | |
1352 | help | |
1353 | Say Y here to let the kernel print out symbolic crash information and | |
1354 | symbolic stack backtraces. This increases the size of the kernel | |
1355 | somewhat, as all symbols have to be loaded into the kernel image. | |
1356 | ||
1357 | config KALLSYMS_ALL | |
1358 | bool "Include all symbols in kallsyms" | |
1359 | depends on DEBUG_KERNEL && KALLSYMS | |
1360 | help | |
1361 | Normally kallsyms only contains the symbols of functions for nicer | |
1362 | OOPS messages and backtraces (i.e., symbols from the text and inittext | |
1363 | sections). This is sufficient for most cases. And only in very rare | |
1364 | cases (e.g., when a debugger is used) all symbols are required (e.g., | |
1365 | names of variables from the data sections, etc). | |
1366 | ||
1367 | This option makes sure that all symbols are loaded into the kernel | |
1368 | image (i.e., symbols from all sections) in cost of increased kernel | |
1369 | size (depending on the kernel configuration, it may be 300KiB or | |
1370 | something like this). | |
1371 | ||
1372 | Say N unless you really need all symbols. | |
1373 | ||
1374 | config KALLSYMS_ABSOLUTE_PERCPU | |
1375 | bool | |
1376 | depends on KALLSYMS | |
1377 | default X86_64 && SMP | |
1378 | ||
1379 | config KALLSYMS_BASE_RELATIVE | |
1380 | bool | |
1381 | depends on KALLSYMS | |
a687a533 | 1382 | default !IA64 |
d1b069f5 RD |
1383 | help |
1384 | Instead of emitting them as absolute values in the native word size, | |
1385 | emit the symbol references in the kallsyms table as 32-bit entries, | |
1386 | each containing a relative value in the range [base, base + U32_MAX] | |
1387 | or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either | |
1388 | an absolute value in the range [0, S32_MAX] or a relative value in the | |
1389 | range [base, base + S32_MAX], where base is the lowest relative symbol | |
1390 | address encountered in the image. | |
1391 | ||
1392 | On 64-bit builds, this reduces the size of the address table by 50%, | |
1393 | but more importantly, it results in entries whose values are build | |
1394 | time constants, and no relocation pass is required at runtime to fix | |
1395 | up the entries based on the runtime load address of the kernel. | |
1396 | ||
1397 | # end of the "standard kernel features (expert users)" menu | |
1398 | ||
1399 | # syscall, maps, verifier | |
1400 | config BPF_SYSCALL | |
1401 | bool "Enable bpf() system call" | |
1402 | select ANON_INODES | |
1403 | select BPF | |
bae77c5e | 1404 | select IRQ_WORK |
d1b069f5 RD |
1405 | default n |
1406 | help | |
1407 | Enable the bpf() system call that allows to manipulate eBPF | |
1408 | programs and maps via file descriptors. | |
1409 | ||
290af866 AS |
1410 | config BPF_JIT_ALWAYS_ON |
1411 | bool "Permanently enable BPF JIT and remove BPF interpreter" | |
1412 | depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT | |
1413 | help | |
1414 | Enables BPF JIT and removes BPF interpreter to avoid | |
1415 | speculative execution of BPF instructions by the interpreter | |
1416 | ||
d1b069f5 RD |
1417 | config USERFAULTFD |
1418 | bool "Enable userfaultfd() system call" | |
1419 | select ANON_INODES | |
1420 | depends on MMU | |
1421 | help | |
1422 | Enable the userfaultfd() system call that allows to intercept and | |
1423 | handle page faults in userland. | |
1424 | ||
3ccfebed MD |
1425 | config ARCH_HAS_MEMBARRIER_CALLBACKS |
1426 | bool | |
1427 | ||
70216e18 MD |
1428 | config ARCH_HAS_MEMBARRIER_SYNC_CORE |
1429 | bool | |
1430 | ||
d7822b1e MD |
1431 | config RSEQ |
1432 | bool "Enable rseq() system call" if EXPERT | |
1433 | default y | |
1434 | depends on HAVE_RSEQ | |
1435 | select MEMBARRIER | |
1436 | help | |
1437 | Enable the restartable sequences system call. It provides a | |
1438 | user-space cache for the current CPU number value, which | |
1439 | speeds up getting the current CPU number from user-space, | |
1440 | as well as an ABI to speed up user-space operations on | |
1441 | per-CPU data. | |
1442 | ||
1443 | If unsure, say Y. | |
1444 | ||
1445 | config DEBUG_RSEQ | |
1446 | default n | |
1447 | bool "Enabled debugging of rseq() system call" if EXPERT | |
1448 | depends on RSEQ && DEBUG_KERNEL | |
1449 | help | |
1450 | Enable extra debugging checks for the rseq system call. | |
1451 | ||
1452 | If unsure, say N. | |
1453 | ||
6befe5f6 RD |
1454 | config EMBEDDED |
1455 | bool "Embedded system" | |
5d2acfc7 | 1456 | option allnoconfig_y |
6befe5f6 RD |
1457 | select EXPERT |
1458 | help | |
1459 | This option should be enabled if compiling the kernel for | |
1460 | an embedded system so certain expert options are available | |
1461 | for configuration. | |
1462 | ||
cdd6c482 | 1463 | config HAVE_PERF_EVENTS |
0793a61d | 1464 | bool |
018df72d MF |
1465 | help |
1466 | See tools/perf/design.txt for details. | |
0793a61d | 1467 | |
906010b2 PZ |
1468 | config PERF_USE_VMALLOC |
1469 | bool | |
1470 | help | |
1471 | See tools/perf/design.txt for details | |
1472 | ||
ad90a3de | 1473 | config PC104 |
424529fb | 1474 | bool "PC/104 support" if EXPERT |
ad90a3de WBG |
1475 | help |
1476 | Expose PC/104 form factor device drivers and options available for | |
1477 | selection and configuration. Enable this option if your target | |
1478 | machine has a PC/104 bus. | |
1479 | ||
57c0c15b | 1480 | menu "Kernel Performance Events And Counters" |
0793a61d | 1481 | |
cdd6c482 | 1482 | config PERF_EVENTS |
57c0c15b | 1483 | bool "Kernel performance events and counters" |
392d65a9 | 1484 | default y if PROFILING |
cdd6c482 | 1485 | depends on HAVE_PERF_EVENTS |
4c59e467 | 1486 | select ANON_INODES |
e360adbe | 1487 | select IRQ_WORK |
83fe27ea | 1488 | select SRCU |
0793a61d | 1489 | help |
57c0c15b IM |
1490 | Enable kernel support for various performance events provided |
1491 | by software and hardware. | |
0793a61d | 1492 | |
dd77038d | 1493 | Software events are supported either built-in or via the |
57c0c15b | 1494 | use of generic tracepoints. |
0793a61d | 1495 | |
57c0c15b IM |
1496 | Most modern CPUs support performance events via performance |
1497 | counter registers. These registers count the number of certain | |
0793a61d TG |
1498 | types of hw events: such as instructions executed, cachemisses |
1499 | suffered, or branches mis-predicted - without slowing down the | |
1500 | kernel or applications. These registers can also trigger interrupts | |
1501 | when a threshold number of events have passed - and can thus be | |
1502 | used to profile the code that runs on that CPU. | |
1503 | ||
57c0c15b | 1504 | The Linux Performance Event subsystem provides an abstraction of |
dd77038d | 1505 | these software and hardware event capabilities, available via a |
57c0c15b | 1506 | system call and used by the "perf" utility in tools/perf/. It |
0793a61d TG |
1507 | provides per task and per CPU counters, and it provides event |
1508 | capabilities on top of those. | |
1509 | ||
1510 | Say Y if unsure. | |
1511 | ||
906010b2 PZ |
1512 | config DEBUG_PERF_USE_VMALLOC |
1513 | default n | |
1514 | bool "Debug: use vmalloc to back perf mmap() buffers" | |
cb307113 | 1515 | depends on PERF_EVENTS && DEBUG_KERNEL && !PPC |
906010b2 PZ |
1516 | select PERF_USE_VMALLOC |
1517 | help | |
1518 | Use vmalloc memory to back perf mmap() buffers. | |
1519 | ||
1520 | Mostly useful for debugging the vmalloc code on platforms | |
1521 | that don't require it. | |
1522 | ||
1523 | Say N if unsure. | |
1524 | ||
0793a61d TG |
1525 | endmenu |
1526 | ||
f8891e5e CL |
1527 | config VM_EVENT_COUNTERS |
1528 | default y | |
6a108a14 | 1529 | bool "Enable VM event counters for /proc/vmstat" if EXPERT |
f8891e5e | 1530 | help |
2aea4fb6 PJ |
1531 | VM event counters are needed for event counts to be shown. |
1532 | This option allows the disabling of the VM event counters | |
6a108a14 | 1533 | on EXPERT systems. /proc/vmstat will only show page counts |
2aea4fb6 | 1534 | if VM event counters are disabled. |
f8891e5e | 1535 | |
41ecc55b CL |
1536 | config SLUB_DEBUG |
1537 | default y | |
6a108a14 | 1538 | bool "Enable SLUB debugging support" if EXPERT |
f6acb635 | 1539 | depends on SLUB && SYSFS |
41ecc55b CL |
1540 | help |
1541 | SLUB has extensive debug support features. Disabling these can | |
1542 | result in significant savings in code size. This also disables | |
1543 | SLUB sysfs support. /sys/slab will not exist and there will be | |
1544 | no support for cache validation etc. | |
1545 | ||
1663f26d TH |
1546 | config SLUB_MEMCG_SYSFS_ON |
1547 | default n | |
1548 | bool "Enable memcg SLUB sysfs support by default" if EXPERT | |
1549 | depends on SLUB && SYSFS && MEMCG | |
1550 | help | |
1551 | SLUB creates a directory under /sys/kernel/slab for each | |
1552 | allocation cache to host info and debug files. If memory | |
1553 | cgroup is enabled, each cache can have per memory cgroup | |
1554 | caches. SLUB can create the same sysfs directories for these | |
1555 | caches under /sys/kernel/slab/CACHE/cgroup but it can lead | |
1556 | to a very high number of debug files being created. This is | |
1557 | controlled by slub_memcg_sysfs boot parameter and this | |
1558 | config option determines the parameter's default value. | |
1559 | ||
b943c460 RD |
1560 | config COMPAT_BRK |
1561 | bool "Disable heap randomization" | |
1562 | default y | |
1563 | help | |
1564 | Randomizing heap placement makes heap exploits harder, but it | |
1565 | also breaks ancient binaries (including anything libc5 based). | |
1566 | This option changes the bootup default to heap randomization | |
692105b8 | 1567 | disabled, and can be overridden at runtime by setting |
b943c460 RD |
1568 | /proc/sys/kernel/randomize_va_space to 2. |
1569 | ||
1570 | On non-ancient distros (post-2000 ones) N is usually a safe choice. | |
1571 | ||
81819f0f CL |
1572 | choice |
1573 | prompt "Choose SLAB allocator" | |
a0acd820 | 1574 | default SLUB |
81819f0f CL |
1575 | help |
1576 | This option allows to select a slab allocator. | |
1577 | ||
1578 | config SLAB | |
1579 | bool "SLAB" | |
04385fc5 | 1580 | select HAVE_HARDENED_USERCOPY_ALLOCATOR |
81819f0f CL |
1581 | help |
1582 | The regular slab allocator that is established and known to work | |
34013886 | 1583 | well in all environments. It organizes cache hot objects in |
02f56210 | 1584 | per cpu and per node queues. |
81819f0f CL |
1585 | |
1586 | config SLUB | |
81819f0f | 1587 | bool "SLUB (Unqueued Allocator)" |
ed18adc1 | 1588 | select HAVE_HARDENED_USERCOPY_ALLOCATOR |
81819f0f CL |
1589 | help |
1590 | SLUB is a slab allocator that minimizes cache line usage | |
1591 | instead of managing queues of cached objects (SLAB approach). | |
1592 | Per cpu caching is realized using slabs of objects instead | |
1593 | of queues of objects. SLUB can use memory efficiently | |
02f56210 SA |
1594 | and has enhanced diagnostics. SLUB is the default choice for |
1595 | a slab allocator. | |
81819f0f CL |
1596 | |
1597 | config SLOB | |
6a108a14 | 1598 | depends on EXPERT |
81819f0f CL |
1599 | bool "SLOB (Simple Allocator)" |
1600 | help | |
37291458 MM |
1601 | SLOB replaces the stock allocator with a drastically simpler |
1602 | allocator. SLOB is generally more space efficient but | |
1603 | does not perform as well on large systems. | |
81819f0f CL |
1604 | |
1605 | endchoice | |
1606 | ||
7660a6fd KC |
1607 | config SLAB_MERGE_DEFAULT |
1608 | bool "Allow slab caches to be merged" | |
1609 | default y | |
1610 | help | |
1611 | For reduced kernel memory fragmentation, slab caches can be | |
1612 | merged when they share the same size and other characteristics. | |
1613 | This carries a risk of kernel heap overflows being able to | |
1614 | overwrite objects from merged caches (and more easily control | |
1615 | cache layout), which makes such heap attacks easier to exploit | |
1616 | by attackers. By keeping caches unmerged, these kinds of exploits | |
1617 | can usually only damage objects in the same cache. To disable | |
1618 | merging at runtime, "slab_nomerge" can be passed on the kernel | |
1619 | command line. | |
1620 | ||
c7ce4f60 TG |
1621 | config SLAB_FREELIST_RANDOM |
1622 | default n | |
210e7a43 | 1623 | depends on SLAB || SLUB |
c7ce4f60 TG |
1624 | bool "SLAB freelist randomization" |
1625 | help | |
210e7a43 | 1626 | Randomizes the freelist order used on creating new pages. This |
c7ce4f60 TG |
1627 | security feature reduces the predictability of the kernel slab |
1628 | allocator against heap overflows. | |
1629 | ||
2482ddec KC |
1630 | config SLAB_FREELIST_HARDENED |
1631 | bool "Harden slab freelist metadata" | |
1632 | depends on SLUB | |
1633 | help | |
1634 | Many kernel heap attacks try to target slab cache metadata and | |
1635 | other infrastructure. This options makes minor performance | |
1636 | sacrifies to harden the kernel slab allocator against common | |
1637 | freelist exploit methods. | |
1638 | ||
345c905d JK |
1639 | config SLUB_CPU_PARTIAL |
1640 | default y | |
b39ffbf8 | 1641 | depends on SLUB && SMP |
345c905d JK |
1642 | bool "SLUB per cpu partial cache" |
1643 | help | |
1644 | Per cpu partial caches accellerate objects allocation and freeing | |
1645 | that is local to a processor at the price of more indeterminism | |
1646 | in the latency of the free. On overflow these caches will be cleared | |
1647 | which requires the taking of locks that may cause latency spikes. | |
1648 | Typically one would choose no for a realtime system. | |
1649 | ||
ea637639 JZ |
1650 | config MMAP_ALLOW_UNINITIALIZED |
1651 | bool "Allow mmapped anonymous memory to be uninitialized" | |
6a108a14 | 1652 | depends on EXPERT && !MMU |
ea637639 JZ |
1653 | default n |
1654 | help | |
1655 | Normally, and according to the Linux spec, anonymous memory obtained | |
1656 | from mmap() has it's contents cleared before it is passed to | |
1657 | userspace. Enabling this config option allows you to request that | |
1658 | mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus | |
1659 | providing a huge performance boost. If this option is not enabled, | |
1660 | then the flag will be ignored. | |
1661 | ||
1662 | This is taken advantage of by uClibc's malloc(), and also by | |
1663 | ELF-FDPIC binfmt's brk and stack allocator. | |
1664 | ||
1665 | Because of the obvious security issues, this option should only be | |
1666 | enabled on embedded devices where you control what is run in | |
1667 | userspace. Since that isn't generally a problem on no-MMU systems, | |
1668 | it is normally safe to say Y here. | |
1669 | ||
1670 | See Documentation/nommu-mmap.txt for more information. | |
1671 | ||
091f6e26 DH |
1672 | config SYSTEM_DATA_VERIFICATION |
1673 | def_bool n | |
1674 | select SYSTEM_TRUSTED_KEYRING | |
1675 | select KEYS | |
1676 | select CRYPTO | |
d43de6c7 | 1677 | select CRYPTO_RSA |
091f6e26 DH |
1678 | select ASYMMETRIC_KEY_TYPE |
1679 | select ASYMMETRIC_PUBLIC_KEY_SUBTYPE | |
091f6e26 DH |
1680 | select ASN1 |
1681 | select OID_REGISTRY | |
1682 | select X509_CERTIFICATE_PARSER | |
1683 | select PKCS7_MESSAGE_PARSER | |
82c04ff8 | 1684 | help |
091f6e26 DH |
1685 | Provide PKCS#7 message verification using the contents of the system |
1686 | trusted keyring to provide public keys. This then can be used for | |
1687 | module verification, kexec image verification and firmware blob | |
1688 | verification. | |
82c04ff8 | 1689 | |
125e5645 | 1690 | config PROFILING |
b309a294 | 1691 | bool "Profiling support" |
125e5645 MD |
1692 | help |
1693 | Say Y here to enable the extended profiling support mechanisms used | |
1694 | by profilers such as OProfile. | |
1695 | ||
5f87f112 IM |
1696 | # |
1697 | # Place an empty function call at each tracepoint site. Can be | |
1698 | # dynamically changed for a probe function. | |
1699 | # | |
97e1c18e | 1700 | config TRACEPOINTS |
5f87f112 | 1701 | bool |
97e1c18e | 1702 | |
fb32e03f MD |
1703 | source "arch/Kconfig" |
1704 | ||
1da177e4 LT |
1705 | endmenu # General setup |
1706 | ||
ee7e5516 DB |
1707 | config HAVE_GENERIC_DMA_COHERENT |
1708 | bool | |
1709 | default n | |
1710 | ||
ae81f9e3 | 1711 | config RT_MUTEXES |
6341e62b | 1712 | bool |
ae81f9e3 | 1713 | |
1da177e4 LT |
1714 | config BASE_SMALL |
1715 | int | |
1716 | default 0 if BASE_FULL | |
1717 | default 1 if !BASE_FULL | |
1718 | ||
66da5733 | 1719 | menuconfig MODULES |
1da177e4 | 1720 | bool "Enable loadable module support" |
11097a03 | 1721 | option modules |
1da177e4 LT |
1722 | help |
1723 | Kernel modules are small pieces of compiled code which can | |
1724 | be inserted in the running kernel, rather than being | |
1725 | permanently built into the kernel. You use the "modprobe" | |
1726 | tool to add (and sometimes remove) them. If you say Y here, | |
1727 | many parts of the kernel can be built as modules (by | |
1728 | answering M instead of Y where indicated): this is most | |
1729 | useful for infrequently used options which are not required | |
1730 | for booting. For more information, see the man pages for | |
1731 | modprobe, lsmod, modinfo, insmod and rmmod. | |
1732 | ||
1733 | If you say Y here, you will need to run "make | |
1734 | modules_install" to put the modules under /lib/modules/ | |
1735 | where modprobe can find them (you may need to be root to do | |
1736 | this). | |
1737 | ||
1738 | If unsure, say Y. | |
1739 | ||
0b0de144 RD |
1740 | if MODULES |
1741 | ||
826e4506 LT |
1742 | config MODULE_FORCE_LOAD |
1743 | bool "Forced module loading" | |
826e4506 LT |
1744 | default n |
1745 | help | |
91e37a79 RR |
1746 | Allow loading of modules without version information (ie. modprobe |
1747 | --force). Forced module loading sets the 'F' (forced) taint flag and | |
1748 | is usually a really bad idea. | |
826e4506 | 1749 | |
1da177e4 LT |
1750 | config MODULE_UNLOAD |
1751 | bool "Module unloading" | |
1da177e4 LT |
1752 | help |
1753 | Without this option you will not be able to unload any | |
1754 | modules (note that some modules may not be unloadable | |
f7f5b675 DV |
1755 | anyway), which makes your kernel smaller, faster |
1756 | and simpler. If unsure, say Y. | |
1da177e4 LT |
1757 | |
1758 | config MODULE_FORCE_UNLOAD | |
1759 | bool "Forced module unloading" | |
19c92399 | 1760 | depends on MODULE_UNLOAD |
1da177e4 LT |
1761 | help |
1762 | This option allows you to force a module to unload, even if the | |
1763 | kernel believes it is unsafe: the kernel will remove the module | |
1764 | without waiting for anyone to stop using it (using the -f option to | |
1765 | rmmod). This is mainly for kernel developers and desperate users. | |
1766 | If unsure, say N. | |
1767 | ||
1da177e4 | 1768 | config MODVERSIONS |
0d541643 | 1769 | bool "Module versioning support" |
1da177e4 LT |
1770 | help |
1771 | Usually, you have to use modules compiled with your kernel. | |
1772 | Saying Y here makes it sometimes possible to use modules | |
1773 | compiled for different kernels, by adding enough information | |
1774 | to the modules to (hopefully) spot any changes which would | |
1775 | make them incompatible with the kernel you are running. If | |
1776 | unsure, say N. | |
1777 | ||
56067812 AB |
1778 | config MODULE_REL_CRCS |
1779 | bool | |
1780 | depends on MODVERSIONS | |
1781 | ||
1da177e4 LT |
1782 | config MODULE_SRCVERSION_ALL |
1783 | bool "Source checksum for all modules" | |
1da177e4 LT |
1784 | help |
1785 | Modules which contain a MODULE_VERSION get an extra "srcversion" | |
1786 | field inserted into their modinfo section, which contains a | |
1787 | sum of the source files which made it. This helps maintainers | |
1788 | see exactly which source was used to build a module (since | |
1789 | others sometimes change the module source without updating | |
1790 | the version). With this option, such a "srcversion" field | |
1791 | will be created for all modules. If unsure, say N. | |
1792 | ||
106a4ee2 RR |
1793 | config MODULE_SIG |
1794 | bool "Module signature verification" | |
1795 | depends on MODULES | |
091f6e26 | 1796 | select SYSTEM_DATA_VERIFICATION |
106a4ee2 RR |
1797 | help |
1798 | Check modules for valid signatures upon load: the signature | |
1799 | is simply appended to the module. For more information see | |
cbdc8217 | 1800 | <file:Documentation/admin-guide/module-signing.rst>. |
106a4ee2 | 1801 | |
228c37ff DH |
1802 | Note that this option adds the OpenSSL development packages as a |
1803 | kernel build dependency so that the signing tool can use its crypto | |
1804 | library. | |
1805 | ||
ea0b6dcf DH |
1806 | !!!WARNING!!! If you enable this option, you MUST make sure that the |
1807 | module DOES NOT get stripped after being signed. This includes the | |
1808 | debuginfo strip done by some packagers (such as rpmbuild) and | |
1809 | inclusion into an initramfs that wants the module size reduced. | |
1810 | ||
106a4ee2 RR |
1811 | config MODULE_SIG_FORCE |
1812 | bool "Require modules to be validly signed" | |
1813 | depends on MODULE_SIG | |
1814 | help | |
1815 | Reject unsigned modules or signed modules for which we don't have a | |
1816 | key. Without this, such modules will simply taint the kernel. | |
ea0b6dcf | 1817 | |
d9d8d7ed MM |
1818 | config MODULE_SIG_ALL |
1819 | bool "Automatically sign all modules" | |
1820 | default y | |
1821 | depends on MODULE_SIG | |
1822 | help | |
1823 | Sign all modules during make modules_install. Without this option, | |
1824 | modules must be signed manually, using the scripts/sign-file tool. | |
1825 | ||
1826 | comment "Do not forget to sign required modules with scripts/sign-file" | |
1827 | depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL | |
1828 | ||
ea0b6dcf DH |
1829 | choice |
1830 | prompt "Which hash algorithm should modules be signed with?" | |
1831 | depends on MODULE_SIG | |
1832 | help | |
1833 | This determines which sort of hashing algorithm will be used during | |
1834 | signature generation. This algorithm _must_ be built into the kernel | |
1835 | directly so that signature verification can take place. It is not | |
1836 | possible to load a signed module containing the algorithm to check | |
1837 | the signature on that module. | |
1838 | ||
1839 | config MODULE_SIG_SHA1 | |
1840 | bool "Sign modules with SHA-1" | |
1841 | select CRYPTO_SHA1 | |
1842 | ||
1843 | config MODULE_SIG_SHA224 | |
1844 | bool "Sign modules with SHA-224" | |
1845 | select CRYPTO_SHA256 | |
1846 | ||
1847 | config MODULE_SIG_SHA256 | |
1848 | bool "Sign modules with SHA-256" | |
1849 | select CRYPTO_SHA256 | |
1850 | ||
1851 | config MODULE_SIG_SHA384 | |
1852 | bool "Sign modules with SHA-384" | |
1853 | select CRYPTO_SHA512 | |
1854 | ||
1855 | config MODULE_SIG_SHA512 | |
1856 | bool "Sign modules with SHA-512" | |
1857 | select CRYPTO_SHA512 | |
1858 | ||
1859 | endchoice | |
1860 | ||
22753674 MM |
1861 | config MODULE_SIG_HASH |
1862 | string | |
1863 | depends on MODULE_SIG | |
1864 | default "sha1" if MODULE_SIG_SHA1 | |
1865 | default "sha224" if MODULE_SIG_SHA224 | |
1866 | default "sha256" if MODULE_SIG_SHA256 | |
1867 | default "sha384" if MODULE_SIG_SHA384 | |
1868 | default "sha512" if MODULE_SIG_SHA512 | |
1869 | ||
beb50df3 BJ |
1870 | config MODULE_COMPRESS |
1871 | bool "Compress modules on installation" | |
1872 | depends on MODULES | |
1873 | help | |
beb50df3 | 1874 | |
b6c09b51 RR |
1875 | Compresses kernel modules when 'make modules_install' is run; gzip or |
1876 | xz depending on "Compression algorithm" below. | |
beb50df3 | 1877 | |
b6c09b51 | 1878 | module-init-tools MAY support gzip, and kmod MAY support gzip and xz. |
beb50df3 | 1879 | |
b6c09b51 RR |
1880 | Out-of-tree kernel modules installed using Kbuild will also be |
1881 | compressed upon installation. | |
beb50df3 | 1882 | |
b6c09b51 RR |
1883 | Note: for modules inside an initrd or initramfs, it's more efficient |
1884 | to compress the whole initrd or initramfs instead. | |
beb50df3 | 1885 | |
b6c09b51 RR |
1886 | Note: This is fully compatible with signed modules. |
1887 | ||
1888 | If in doubt, say N. | |
beb50df3 BJ |
1889 | |
1890 | choice | |
1891 | prompt "Compression algorithm" | |
1892 | depends on MODULE_COMPRESS | |
1893 | default MODULE_COMPRESS_GZIP | |
1894 | help | |
1895 | This determines which sort of compression will be used during | |
1896 | 'make modules_install'. | |
1897 | ||
1898 | GZIP (default) and XZ are supported. | |
1899 | ||
1900 | config MODULE_COMPRESS_GZIP | |
1901 | bool "GZIP" | |
1902 | ||
1903 | config MODULE_COMPRESS_XZ | |
1904 | bool "XZ" | |
1905 | ||
1906 | endchoice | |
1907 | ||
dbacb0ef NP |
1908 | config TRIM_UNUSED_KSYMS |
1909 | bool "Trim unused exported kernel symbols" | |
1910 | depends on MODULES && !UNUSED_SYMBOLS | |
1911 | help | |
1912 | The kernel and some modules make many symbols available for | |
1913 | other modules to use via EXPORT_SYMBOL() and variants. Depending | |
1914 | on the set of modules being selected in your kernel configuration, | |
1915 | many of those exported symbols might never be used. | |
1916 | ||
1917 | This option allows for unused exported symbols to be dropped from | |
1918 | the build. In turn, this provides the compiler more opportunities | |
1919 | (especially when using LTO) for optimizing the code and reducing | |
1920 | binary size. This might have some security advantages as well. | |
1921 | ||
f1cb637e | 1922 | If unsure, or if you need to build out-of-tree modules, say N. |
dbacb0ef | 1923 | |
0b0de144 RD |
1924 | endif # MODULES |
1925 | ||
6c9692e2 PZ |
1926 | config MODULES_TREE_LOOKUP |
1927 | def_bool y | |
1928 | depends on PERF_EVENTS || TRACING | |
1929 | ||
98a79d6a RR |
1930 | config INIT_ALL_POSSIBLE |
1931 | bool | |
1932 | help | |
5f054e31 RR |
1933 | Back when each arch used to define their own cpu_online_mask and |
1934 | cpu_possible_mask, some of them chose to initialize cpu_possible_mask | |
98a79d6a RR |
1935 | with all 1s, and others with all 0s. When they were centralised, |
1936 | it was better to provide this option than to break all the archs | |
692105b8 | 1937 | and have several arch maintainers pursuing me down dark alleys. |
98a79d6a | 1938 | |
3a65dfe8 | 1939 | source "block/Kconfig" |
e98c3202 AK |
1940 | |
1941 | config PREEMPT_NOTIFIERS | |
1942 | bool | |
e260be67 | 1943 | |
16295bec SK |
1944 | config PADATA |
1945 | depends on SMP | |
1946 | bool | |
1947 | ||
4520c6a4 DH |
1948 | config ASN1 |
1949 | tristate | |
1950 | help | |
1951 | Build a simple ASN.1 grammar compiler that produces a bytecode output | |
1952 | that can be interpreted by the ASN.1 stream decoder and used to | |
1953 | inform it as to what tags are to be expected in a stream and what | |
1954 | functions to call on what tags. | |
1955 | ||
6beb0009 | 1956 | source "kernel/Kconfig.locks" |
e61938a9 MD |
1957 | |
1958 | config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE | |
1959 | bool | |
1bd21c6c DB |
1960 | |
1961 | # It may be useful for an architecture to override the definitions of the | |
7303e30e DB |
1962 | # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h> |
1963 | # and the COMPAT_ variants in <linux/compat.h>, in particular to use a | |
1964 | # different calling convention for syscalls. They can also override the | |
1965 | # macros for not-implemented syscalls in kernel/sys_ni.c and | |
1966 | # kernel/time/posix-stubs.c. All these overrides need to be available in | |
1967 | # <asm/syscall_wrapper.h>. | |
1bd21c6c DB |
1968 | config ARCH_HAS_SYSCALL_WRAPPER |
1969 | def_bool n |