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ec8f24b7 | 1 | # SPDX-License-Identifier: GPL-2.0-only |
8b59cd81 MY |
2 | config CC_VERSION_TEXT |
3 | string | |
4 | default "$(CC_VERSION_TEXT)" | |
5 | help | |
6 | This is used in unclear ways: | |
7 | ||
8 | - Re-run Kconfig when the compiler is updated | |
9 | The 'default' property references the environment variable, | |
10 | CC_VERSION_TEXT so it is recorded in include/config/auto.conf.cmd. | |
11 | When the compiler is updated, Kconfig will be invoked. | |
12 | ||
f9c8bc46 | 13 | - Ensure full rebuild when the compiler is updated |
ce6ed1c4 | 14 | include/linux/compiler-version.h contains this option in the comment |
0e0345b7 | 15 | line so fixdep adds include/config/CC_VERSION_TEXT into the |
ce6ed1c4 MY |
16 | auto-generated dependency. When the compiler is updated, syncconfig |
17 | will touch it and then every file will be rebuilt. | |
8b59cd81 | 18 | |
a4353898 | 19 | config CC_IS_GCC |
aec6c60a | 20 | def_bool $(success,test "$(cc-name)" = GCC) |
a4353898 MY |
21 | |
22 | config GCC_VERSION | |
23 | int | |
aec6c60a | 24 | default $(cc-version) if CC_IS_GCC |
a4353898 MY |
25 | default 0 |
26 | ||
469cb737 | 27 | config CC_IS_CLANG |
aec6c60a | 28 | def_bool $(success,test "$(cc-name)" = Clang) |
b744b43f | 29 | |
469cb737 MY |
30 | config CLANG_VERSION |
31 | int | |
aec6c60a MY |
32 | default $(cc-version) if CC_IS_CLANG |
33 | default 0 | |
469cb737 | 34 | |
ba64beb1 MY |
35 | config AS_IS_GNU |
36 | def_bool $(success,test "$(as-name)" = GNU) | |
37 | ||
38 | config AS_IS_LLVM | |
39 | def_bool $(success,test "$(as-name)" = LLVM) | |
40 | ||
41 | config AS_VERSION | |
42 | int | |
43 | # Use clang version if this is the integrated assembler | |
44 | default CLANG_VERSION if AS_IS_LLVM | |
45 | default $(as-version) | |
46 | ||
02aff859 MY |
47 | config LD_IS_BFD |
48 | def_bool $(success,test "$(ld-name)" = BFD) | |
49 | ||
50 | config LD_VERSION | |
51 | int | |
52 | default $(ld-version) if LD_IS_BFD | |
53 | default 0 | |
54 | ||
55 | config LD_IS_LLD | |
56 | def_bool $(success,test "$(ld-name)" = LLD) | |
469cb737 | 57 | |
d5750cd3 NC |
58 | config LLD_VERSION |
59 | int | |
02aff859 MY |
60 | default $(ld-version) if LD_IS_LLD |
61 | default 0 | |
d5750cd3 | 62 | |
1a927fd3 | 63 | config CC_CAN_LINK |
9371f86e | 64 | bool |
b816b3db MY |
65 | default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m64-flag)) if 64BIT |
66 | default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m32-flag)) | |
b1183b6d MY |
67 | |
68 | config CC_CAN_LINK_STATIC | |
69 | bool | |
b816b3db MY |
70 | default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m64-flag) -static) if 64BIT |
71 | default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m32-flag) -static) | |
1a927fd3 | 72 | |
e9666d10 MY |
73 | config CC_HAS_ASM_GOTO |
74 | def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC)) | |
75 | ||
587f1701 ND |
76 | config CC_HAS_ASM_GOTO_OUTPUT |
77 | depends on CC_HAS_ASM_GOTO | |
78 | def_bool $(success,echo 'int foo(int x) { asm goto ("": "=r"(x) ::: bar); return x; bar: return 0; }' | $(CC) -x c - -c -o /dev/null) | |
79 | ||
5cf896fb | 80 | config TOOLS_SUPPORT_RELR |
2d122942 | 81 | def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh) |
5cf896fb | 82 | |
eb111869 RV |
83 | config CC_HAS_ASM_INLINE |
84 | def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null) | |
85 | ||
b99b87f7 PO |
86 | config CONSTRUCTORS |
87 | bool | |
b99b87f7 | 88 | |
e360adbe PZ |
89 | config IRQ_WORK |
90 | bool | |
e360adbe | 91 | |
10916706 | 92 | config BUILDTIME_TABLE_SORT |
1dbdc6f1 DD |
93 | bool |
94 | ||
c65eacbe AL |
95 | config THREAD_INFO_IN_TASK |
96 | bool | |
97 | help | |
98 | Select this to move thread_info off the stack into task_struct. To | |
99 | make this work, an arch will need to remove all thread_info fields | |
100 | except flags and fix any runtime bugs. | |
101 | ||
c6c314a6 AL |
102 | One subtle change that will be needed is to use try_get_task_stack() |
103 | and put_task_stack() in save_thread_stack_tsk() and get_wchan(). | |
104 | ||
ff0cfc66 | 105 | menu "General setup" |
1da177e4 | 106 | |
1da177e4 LT |
107 | config BROKEN |
108 | bool | |
1da177e4 LT |
109 | |
110 | config BROKEN_ON_SMP | |
111 | bool | |
112 | depends on BROKEN || !SMP | |
113 | default y | |
114 | ||
1da177e4 LT |
115 | config INIT_ENV_ARG_LIMIT |
116 | int | |
dd673bca AB |
117 | default 32 if !UML |
118 | default 128 if UML | |
1da177e4 | 119 | help |
34ad92c2 RD |
120 | Maximum of each of the number of arguments and environment |
121 | variables passed to init from the kernel command line. | |
1da177e4 | 122 | |
4bb16672 JS |
123 | config COMPILE_TEST |
124 | bool "Compile also drivers which will not load" | |
ea29b20a | 125 | depends on HAS_IOMEM |
4bb16672 JS |
126 | help |
127 | Some drivers can be compiled on a different platform than they are | |
128 | intended to be run on. Despite they cannot be loaded there (or even | |
129 | when they load they cannot be used due to missing HW support), | |
130 | developers still, opposing to distributors, might want to build such | |
131 | drivers to compile-test them. | |
132 | ||
133 | If you are a developer and want to build everything available, say Y | |
134 | here. If you are a user/distributor, say N here to exclude useless | |
135 | drivers to be distributed. | |
136 | ||
d6fc9fcb MY |
137 | config UAPI_HEADER_TEST |
138 | bool "Compile test UAPI headers" | |
fcbb8461 | 139 | depends on HEADERS_INSTALL && CC_CAN_LINK |
d6fc9fcb MY |
140 | help |
141 | Compile test headers exported to user-space to ensure they are | |
142 | self-contained, i.e. compilable as standalone units. | |
143 | ||
144 | If you are a developer or tester and want to ensure the exported | |
145 | headers are self-contained, say Y here. Otherwise, choose N. | |
146 | ||
1da177e4 LT |
147 | config LOCALVERSION |
148 | string "Local version - append to kernel release" | |
149 | help | |
150 | Append an extra string to the end of your kernel version. | |
151 | This will show up when you type uname, for example. | |
152 | The string you set here will be appended after the contents of | |
153 | any files with a filename matching localversion* in your | |
154 | object and source tree, in that order. Your total string can | |
155 | be a maximum of 64 characters. | |
156 | ||
aaebf433 RA |
157 | config LOCALVERSION_AUTO |
158 | bool "Automatically append version information to the version string" | |
159 | default y | |
ac3339ba | 160 | depends on !COMPILE_TEST |
aaebf433 RA |
161 | help |
162 | This will try to automatically determine if the current tree is a | |
6e5a5420 RD |
163 | release tree by looking for git tags that belong to the current |
164 | top of tree revision. | |
aaebf433 RA |
165 | |
166 | A string of the format -gxxxxxxxx will be added to the localversion | |
6e5a5420 | 167 | if a git-based tree is found. The string generated by this will be |
aaebf433 | 168 | appended after any matching localversion* files, and after the value |
6e5a5420 | 169 | set in CONFIG_LOCALVERSION. |
aaebf433 | 170 | |
6e5a5420 RD |
171 | (The actual string used here is the first eight characters produced |
172 | by running the command: | |
173 | ||
174 | $ git rev-parse --verify HEAD | |
175 | ||
176 | which is done within the script "scripts/setlocalversion".) | |
aaebf433 | 177 | |
9afb719e | 178 | config BUILD_SALT |
e8cf4e9c KK |
179 | string "Build ID Salt" |
180 | default "" | |
181 | help | |
182 | The build ID is used to link binaries and their debug info. Setting | |
183 | this option will use the value in the calculation of the build id. | |
184 | This is mostly useful for distributions which want to ensure the | |
185 | build is unique between builds. It's safe to leave the default. | |
9afb719e | 186 | |
2e9f3bdd PA |
187 | config HAVE_KERNEL_GZIP |
188 | bool | |
189 | ||
190 | config HAVE_KERNEL_BZIP2 | |
191 | bool | |
192 | ||
193 | config HAVE_KERNEL_LZMA | |
194 | bool | |
195 | ||
3ebe1243 LC |
196 | config HAVE_KERNEL_XZ |
197 | bool | |
198 | ||
7dd65feb AT |
199 | config HAVE_KERNEL_LZO |
200 | bool | |
201 | ||
e76e1fdf KL |
202 | config HAVE_KERNEL_LZ4 |
203 | bool | |
204 | ||
48f7ddf7 NT |
205 | config HAVE_KERNEL_ZSTD |
206 | bool | |
207 | ||
f16466af VG |
208 | config HAVE_KERNEL_UNCOMPRESSED |
209 | bool | |
210 | ||
30d65dbf | 211 | choice |
2e9f3bdd PA |
212 | prompt "Kernel compression mode" |
213 | default KERNEL_GZIP | |
48f7ddf7 | 214 | depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 || HAVE_KERNEL_ZSTD || HAVE_KERNEL_UNCOMPRESSED |
2e9f3bdd | 215 | help |
30d65dbf AK |
216 | The linux kernel is a kind of self-extracting executable. |
217 | Several compression algorithms are available, which differ | |
218 | in efficiency, compression and decompression speed. | |
219 | Compression speed is only relevant when building a kernel. | |
220 | Decompression speed is relevant at each boot. | |
221 | ||
222 | If you have any problems with bzip2 or lzma compressed | |
223 | kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older | |
224 | version of this functionality (bzip2 only), for 2.4, was | |
225 | supplied by Christian Ludwig) | |
226 | ||
227 | High compression options are mostly useful for users, who | |
228 | are low on disk space (embedded systems), but for whom ram | |
229 | size matters less. | |
230 | ||
231 | If in doubt, select 'gzip' | |
232 | ||
233 | config KERNEL_GZIP | |
2e9f3bdd PA |
234 | bool "Gzip" |
235 | depends on HAVE_KERNEL_GZIP | |
236 | help | |
7dd65feb AT |
237 | The old and tried gzip compression. It provides a good balance |
238 | between compression ratio and decompression speed. | |
30d65dbf AK |
239 | |
240 | config KERNEL_BZIP2 | |
241 | bool "Bzip2" | |
2e9f3bdd | 242 | depends on HAVE_KERNEL_BZIP2 |
30d65dbf AK |
243 | help |
244 | Its compression ratio and speed is intermediate. | |
0a4dd35c | 245 | Decompression speed is slowest among the choices. The kernel |
2e9f3bdd PA |
246 | size is about 10% smaller with bzip2, in comparison to gzip. |
247 | Bzip2 uses a large amount of memory. For modern kernels you | |
248 | will need at least 8MB RAM or more for booting. | |
30d65dbf AK |
249 | |
250 | config KERNEL_LZMA | |
2e9f3bdd PA |
251 | bool "LZMA" |
252 | depends on HAVE_KERNEL_LZMA | |
253 | help | |
0a4dd35c RD |
254 | This compression algorithm's ratio is best. Decompression speed |
255 | is between gzip and bzip2. Compression is slowest. | |
256 | The kernel size is about 33% smaller with LZMA in comparison to gzip. | |
30d65dbf | 257 | |
3ebe1243 LC |
258 | config KERNEL_XZ |
259 | bool "XZ" | |
260 | depends on HAVE_KERNEL_XZ | |
261 | help | |
262 | XZ uses the LZMA2 algorithm and instruction set specific | |
263 | BCJ filters which can improve compression ratio of executable | |
264 | code. The size of the kernel is about 30% smaller with XZ in | |
265 | comparison to gzip. On architectures for which there is a BCJ | |
266 | filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ | |
267 | will create a few percent smaller kernel than plain LZMA. | |
268 | ||
269 | The speed is about the same as with LZMA: The decompression | |
270 | speed of XZ is better than that of bzip2 but worse than gzip | |
271 | and LZO. Compression is slow. | |
272 | ||
7dd65feb AT |
273 | config KERNEL_LZO |
274 | bool "LZO" | |
275 | depends on HAVE_KERNEL_LZO | |
276 | help | |
0a4dd35c | 277 | Its compression ratio is the poorest among the choices. The kernel |
681b3049 | 278 | size is about 10% bigger than gzip; however its speed |
7dd65feb AT |
279 | (both compression and decompression) is the fastest. |
280 | ||
e76e1fdf KL |
281 | config KERNEL_LZ4 |
282 | bool "LZ4" | |
283 | depends on HAVE_KERNEL_LZ4 | |
284 | help | |
285 | LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding. | |
286 | A preliminary version of LZ4 de/compression tool is available at | |
287 | <https://code.google.com/p/lz4/>. | |
288 | ||
289 | Its compression ratio is worse than LZO. The size of the kernel | |
290 | is about 8% bigger than LZO. But the decompression speed is | |
291 | faster than LZO. | |
292 | ||
48f7ddf7 NT |
293 | config KERNEL_ZSTD |
294 | bool "ZSTD" | |
295 | depends on HAVE_KERNEL_ZSTD | |
296 | help | |
297 | ZSTD is a compression algorithm targeting intermediate compression | |
298 | with fast decompression speed. It will compress better than GZIP and | |
299 | decompress around the same speed as LZO, but slower than LZ4. You | |
300 | will need at least 192 KB RAM or more for booting. The zstd command | |
301 | line tool is required for compression. | |
302 | ||
f16466af VG |
303 | config KERNEL_UNCOMPRESSED |
304 | bool "None" | |
305 | depends on HAVE_KERNEL_UNCOMPRESSED | |
306 | help | |
307 | Produce uncompressed kernel image. This option is usually not what | |
308 | you want. It is useful for debugging the kernel in slow simulation | |
309 | environments, where decompressing and moving the kernel is awfully | |
310 | slow. This option allows early boot code to skip the decompressor | |
311 | and jump right at uncompressed kernel image. | |
312 | ||
30d65dbf AK |
313 | endchoice |
314 | ||
ada4ab7a CD |
315 | config DEFAULT_INIT |
316 | string "Default init path" | |
317 | default "" | |
318 | help | |
319 | This option determines the default init for the system if no init= | |
320 | option is passed on the kernel command line. If the requested path is | |
321 | not present, we will still then move on to attempting further | |
322 | locations (e.g. /sbin/init, etc). If this is empty, we will just use | |
323 | the fallback list when init= is not passed. | |
324 | ||
bd5dc17b JT |
325 | config DEFAULT_HOSTNAME |
326 | string "Default hostname" | |
327 | default "(none)" | |
328 | help | |
329 | This option determines the default system hostname before userspace | |
330 | calls sethostname(2). The kernel traditionally uses "(none)" here, | |
331 | but you may wish to use a different default here to make a minimal | |
332 | system more usable with less configuration. | |
333 | ||
17c46a6a CH |
334 | # |
335 | # For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can | |
336 | # add proper SWAP support to them, in which case this can be remove. | |
337 | # | |
338 | config ARCH_NO_SWAP | |
339 | bool | |
340 | ||
1da177e4 LT |
341 | config SWAP |
342 | bool "Support for paging of anonymous memory (swap)" | |
17c46a6a | 343 | depends on MMU && BLOCK && !ARCH_NO_SWAP |
1da177e4 LT |
344 | default y |
345 | help | |
346 | This option allows you to choose whether you want to have support | |
92c3504e | 347 | for so called swap devices or swap files in your kernel that are |
1da177e4 LT |
348 | used to provide more virtual memory than the actual RAM present |
349 | in your computer. If unsure say Y. | |
350 | ||
351 | config SYSVIPC | |
352 | bool "System V IPC" | |
a7f7f624 | 353 | help |
1da177e4 LT |
354 | Inter Process Communication is a suite of library functions and |
355 | system calls which let processes (running programs) synchronize and | |
356 | exchange information. It is generally considered to be a good thing, | |
357 | and some programs won't run unless you say Y here. In particular, if | |
358 | you want to run the DOS emulator dosemu under Linux (read the | |
359 | DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), | |
360 | you'll need to say Y here. | |
361 | ||
362 | You can find documentation about IPC with "info ipc" and also in | |
363 | section 6.4 of the Linux Programmer's Guide, available from | |
364 | <http://www.tldp.org/guides.html>. | |
365 | ||
a5494dcd EB |
366 | config SYSVIPC_SYSCTL |
367 | bool | |
368 | depends on SYSVIPC | |
369 | depends on SYSCTL | |
370 | default y | |
371 | ||
1da177e4 LT |
372 | config POSIX_MQUEUE |
373 | bool "POSIX Message Queues" | |
19c92399 | 374 | depends on NET |
a7f7f624 | 375 | help |
1da177e4 LT |
376 | POSIX variant of message queues is a part of IPC. In POSIX message |
377 | queues every message has a priority which decides about succession | |
378 | of receiving it by a process. If you want to compile and run | |
379 | programs written e.g. for Solaris with use of its POSIX message | |
b0e37650 | 380 | queues (functions mq_*) say Y here. |
1da177e4 LT |
381 | |
382 | POSIX message queues are visible as a filesystem called 'mqueue' | |
383 | and can be mounted somewhere if you want to do filesystem | |
384 | operations on message queues. | |
385 | ||
386 | If unsure, say Y. | |
387 | ||
bdc8e5f8 SH |
388 | config POSIX_MQUEUE_SYSCTL |
389 | bool | |
390 | depends on POSIX_MQUEUE | |
391 | depends on SYSCTL | |
392 | default y | |
393 | ||
c73be61c DH |
394 | config WATCH_QUEUE |
395 | bool "General notification queue" | |
396 | default n | |
397 | help | |
398 | ||
399 | This is a general notification queue for the kernel to pass events to | |
400 | userspace by splicing them into pipes. It can be used in conjunction | |
401 | with watches for key/keyring change notifications and device | |
402 | notifications. | |
403 | ||
404 | See Documentation/watch_queue.rst | |
405 | ||
226b4ccd KK |
406 | config CROSS_MEMORY_ATTACH |
407 | bool "Enable process_vm_readv/writev syscalls" | |
408 | depends on MMU | |
409 | default y | |
410 | help | |
411 | Enabling this option adds the system calls process_vm_readv and | |
412 | process_vm_writev which allow a process with the correct privileges | |
a2a368d9 | 413 | to directly read from or write to another process' address space. |
226b4ccd KK |
414 | See the man page for more details. |
415 | ||
69369a70 JT |
416 | config USELIB |
417 | bool "uselib syscall" | |
b2113a41 | 418 | def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION |
69369a70 JT |
419 | help |
420 | This option enables the uselib syscall, a system call used in the | |
421 | dynamic linker from libc5 and earlier. glibc does not use this | |
422 | system call. If you intend to run programs built on libc5 or | |
423 | earlier, you may need to enable this syscall. Current systems | |
424 | running glibc can safely disable this. | |
425 | ||
391dc69c FW |
426 | config AUDIT |
427 | bool "Auditing support" | |
428 | depends on NET | |
429 | help | |
430 | Enable auditing infrastructure that can be used with another | |
431 | kernel subsystem, such as SELinux (which requires this for | |
cb74ed27 PM |
432 | logging of avc messages output). System call auditing is included |
433 | on architectures which support it. | |
391dc69c | 434 | |
7a017721 AT |
435 | config HAVE_ARCH_AUDITSYSCALL |
436 | bool | |
437 | ||
391dc69c | 438 | config AUDITSYSCALL |
cb74ed27 | 439 | def_bool y |
7a017721 | 440 | depends on AUDIT && HAVE_ARCH_AUDITSYSCALL |
391dc69c FW |
441 | select FSNOTIFY |
442 | ||
391dc69c FW |
443 | source "kernel/irq/Kconfig" |
444 | source "kernel/time/Kconfig" | |
b24abcff | 445 | source "kernel/bpf/Kconfig" |
87a4c375 | 446 | source "kernel/Kconfig.preempt" |
391dc69c FW |
447 | |
448 | menu "CPU/Task time and stats accounting" | |
449 | ||
abf917cd FW |
450 | config VIRT_CPU_ACCOUNTING |
451 | bool | |
452 | ||
fdf9c356 FW |
453 | choice |
454 | prompt "Cputime accounting" | |
455 | default TICK_CPU_ACCOUNTING if !PPC64 | |
02fc8d37 | 456 | default VIRT_CPU_ACCOUNTING_NATIVE if PPC64 |
fdf9c356 FW |
457 | |
458 | # Kind of a stub config for the pure tick based cputime accounting | |
459 | config TICK_CPU_ACCOUNTING | |
460 | bool "Simple tick based cputime accounting" | |
c58b0df1 | 461 | depends on !S390 && !NO_HZ_FULL |
fdf9c356 FW |
462 | help |
463 | This is the basic tick based cputime accounting that maintains | |
464 | statistics about user, system and idle time spent on per jiffies | |
465 | granularity. | |
466 | ||
467 | If unsure, say Y. | |
468 | ||
abf917cd | 469 | config VIRT_CPU_ACCOUNTING_NATIVE |
b952741c | 470 | bool "Deterministic task and CPU time accounting" |
c58b0df1 | 471 | depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL |
abf917cd | 472 | select VIRT_CPU_ACCOUNTING |
b952741c FW |
473 | help |
474 | Select this option to enable more accurate task and CPU time | |
475 | accounting. This is done by reading a CPU counter on each | |
476 | kernel entry and exit and on transitions within the kernel | |
477 | between system, softirq and hardirq state, so there is a | |
478 | small performance impact. In the case of s390 or IBM POWER > 5, | |
479 | this also enables accounting of stolen time on logically-partitioned | |
480 | systems. | |
481 | ||
abf917cd FW |
482 | config VIRT_CPU_ACCOUNTING_GEN |
483 | bool "Full dynticks CPU time accounting" | |
ff3fb254 | 484 | depends on HAVE_CONTEXT_TRACKING |
554b0004 | 485 | depends on HAVE_VIRT_CPU_ACCOUNTING_GEN |
041a1574 | 486 | depends on GENERIC_CLOCKEVENTS |
abf917cd FW |
487 | select VIRT_CPU_ACCOUNTING |
488 | select CONTEXT_TRACKING | |
489 | help | |
490 | Select this option to enable task and CPU time accounting on full | |
491 | dynticks systems. This accounting is implemented by watching every | |
492 | kernel-user boundaries using the context tracking subsystem. | |
493 | The accounting is thus performed at the expense of some significant | |
494 | overhead. | |
495 | ||
496 | For now this is only useful if you are working on the full | |
497 | dynticks subsystem development. | |
498 | ||
499 | If unsure, say N. | |
500 | ||
b58c3584 RR |
501 | endchoice |
502 | ||
fdf9c356 FW |
503 | config IRQ_TIME_ACCOUNTING |
504 | bool "Fine granularity task level IRQ time accounting" | |
b58c3584 | 505 | depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE |
fdf9c356 FW |
506 | help |
507 | Select this option to enable fine granularity task irq time | |
508 | accounting. This is done by reading a timestamp on each | |
509 | transitions between softirq and hardirq state, so there can be a | |
510 | small performance impact. | |
511 | ||
512 | If in doubt, say N here. | |
513 | ||
11d4afd4 VG |
514 | config HAVE_SCHED_AVG_IRQ |
515 | def_bool y | |
516 | depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING | |
517 | depends on SMP | |
518 | ||
76504793 | 519 | config SCHED_THERMAL_PRESSURE |
98eb401d | 520 | bool |
fcd7c9c3 VS |
521 | default y if ARM && ARM_CPU_TOPOLOGY |
522 | default y if ARM64 | |
76504793 | 523 | depends on SMP |
98eb401d VS |
524 | depends on CPU_FREQ_THERMAL |
525 | help | |
526 | Select this option to enable thermal pressure accounting in the | |
527 | scheduler. Thermal pressure is the value conveyed to the scheduler | |
528 | that reflects the reduction in CPU compute capacity resulted from | |
529 | thermal throttling. Thermal throttling occurs when the performance of | |
530 | a CPU is capped due to high operating temperatures. | |
531 | ||
532 | If selected, the scheduler will be able to balance tasks accordingly, | |
533 | i.e. put less load on throttled CPUs than on non/less throttled ones. | |
534 | ||
535 | This requires the architecture to implement | |
432900f8 | 536 | arch_set_thermal_pressure() and arch_scale_thermal_pressure(). |
76504793 | 537 | |
1da177e4 LT |
538 | config BSD_PROCESS_ACCT |
539 | bool "BSD Process Accounting" | |
2813893f | 540 | depends on MULTIUSER |
1da177e4 LT |
541 | help |
542 | If you say Y here, a user level program will be able to instruct the | |
543 | kernel (via a special system call) to write process accounting | |
544 | information to a file: whenever a process exits, information about | |
545 | that process will be appended to the file by the kernel. The | |
546 | information includes things such as creation time, owning user, | |
547 | command name, memory usage, controlling terminal etc. (the complete | |
548 | list is in the struct acct in <file:include/linux/acct.h>). It is | |
549 | up to the user level program to do useful things with this | |
550 | information. This is generally a good idea, so say Y. | |
551 | ||
552 | config BSD_PROCESS_ACCT_V3 | |
553 | bool "BSD Process Accounting version 3 file format" | |
554 | depends on BSD_PROCESS_ACCT | |
555 | default n | |
556 | help | |
557 | If you say Y here, the process accounting information is written | |
558 | in a new file format that also logs the process IDs of each | |
3903bf94 | 559 | process and its parent. Note that this file format is incompatible |
1da177e4 LT |
560 | with previous v0/v1/v2 file formats, so you will need updated tools |
561 | for processing it. A preliminary version of these tools is available | |
37a4c940 | 562 | at <http://www.gnu.org/software/acct/>. |
1da177e4 | 563 | |
c757249a | 564 | config TASKSTATS |
19c92399 | 565 | bool "Export task/process statistics through netlink" |
c757249a | 566 | depends on NET |
2813893f | 567 | depends on MULTIUSER |
c757249a SN |
568 | default n |
569 | help | |
570 | Export selected statistics for tasks/processes through the | |
571 | generic netlink interface. Unlike BSD process accounting, the | |
572 | statistics are available during the lifetime of tasks/processes as | |
573 | responses to commands. Like BSD accounting, they are sent to user | |
574 | space on task exit. | |
575 | ||
576 | Say N if unsure. | |
577 | ||
ca74e92b | 578 | config TASK_DELAY_ACCT |
19c92399 | 579 | bool "Enable per-task delay accounting" |
6f44993f | 580 | depends on TASKSTATS |
f6db8347 | 581 | select SCHED_INFO |
ca74e92b SN |
582 | help |
583 | Collect information on time spent by a task waiting for system | |
584 | resources like cpu, synchronous block I/O completion and swapping | |
585 | in pages. Such statistics can help in setting a task's priorities | |
586 | relative to other tasks for cpu, io, rss limits etc. | |
587 | ||
588 | Say N if unsure. | |
589 | ||
18f705f4 | 590 | config TASK_XACCT |
19c92399 | 591 | bool "Enable extended accounting over taskstats" |
18f705f4 AD |
592 | depends on TASKSTATS |
593 | help | |
594 | Collect extended task accounting data and send the data | |
595 | to userland for processing over the taskstats interface. | |
596 | ||
597 | Say N if unsure. | |
598 | ||
599 | config TASK_IO_ACCOUNTING | |
19c92399 | 600 | bool "Enable per-task storage I/O accounting" |
18f705f4 AD |
601 | depends on TASK_XACCT |
602 | help | |
603 | Collect information on the number of bytes of storage I/O which this | |
604 | task has caused. | |
605 | ||
606 | Say N if unsure. | |
607 | ||
eb414681 JW |
608 | config PSI |
609 | bool "Pressure stall information tracking" | |
610 | help | |
611 | Collect metrics that indicate how overcommitted the CPU, memory, | |
612 | and IO capacity are in the system. | |
613 | ||
614 | If you say Y here, the kernel will create /proc/pressure/ with the | |
615 | pressure statistics files cpu, memory, and io. These will indicate | |
616 | the share of walltime in which some or all tasks in the system are | |
617 | delayed due to contention of the respective resource. | |
618 | ||
2ce7135a JW |
619 | In kernels with cgroup support, cgroups (cgroup2 only) will |
620 | have cpu.pressure, memory.pressure, and io.pressure files, | |
621 | which aggregate pressure stalls for the grouped tasks only. | |
622 | ||
c3123552 | 623 | For more details see Documentation/accounting/psi.rst. |
eb414681 JW |
624 | |
625 | Say N if unsure. | |
626 | ||
e0c27447 JW |
627 | config PSI_DEFAULT_DISABLED |
628 | bool "Require boot parameter to enable pressure stall information tracking" | |
629 | default n | |
630 | depends on PSI | |
631 | help | |
632 | If set, pressure stall information tracking will be disabled | |
428a1cb4 BS |
633 | per default but can be enabled through passing psi=1 on the |
634 | kernel commandline during boot. | |
e0c27447 | 635 | |
7b2489d3 JW |
636 | This feature adds some code to the task wakeup and sleep |
637 | paths of the scheduler. The overhead is too low to affect | |
638 | common scheduling-intense workloads in practice (such as | |
639 | webservers, memcache), but it does show up in artificial | |
640 | scheduler stress tests, such as hackbench. | |
641 | ||
642 | If you are paranoid and not sure what the kernel will be | |
643 | used for, say Y. | |
644 | ||
645 | Say N if unsure. | |
646 | ||
391dc69c | 647 | endmenu # "CPU/Task time and stats accounting" |
d9817ebe | 648 | |
5c4991e2 FW |
649 | config CPU_ISOLATION |
650 | bool "CPU isolation" | |
414a2dc1 | 651 | depends on SMP || COMPILE_TEST |
2c43838c | 652 | default y |
5c4991e2 FW |
653 | help |
654 | Make sure that CPUs running critical tasks are not disturbed by | |
655 | any source of "noise" such as unbound workqueues, timers, kthreads... | |
2c43838c FW |
656 | Unbound jobs get offloaded to housekeeping CPUs. This is driven by |
657 | the "isolcpus=" boot parameter. | |
658 | ||
659 | Say Y if unsure. | |
5c4991e2 | 660 | |
0af92d46 | 661 | source "kernel/rcu/Kconfig" |
c903ff83 | 662 | |
de5b56ba VG |
663 | config BUILD_BIN2C |
664 | bool | |
665 | default n | |
666 | ||
1da177e4 | 667 | config IKCONFIG |
f2443ab6 | 668 | tristate "Kernel .config support" |
a7f7f624 | 669 | help |
1da177e4 LT |
670 | This option enables the complete Linux kernel ".config" file |
671 | contents to be saved in the kernel. It provides documentation | |
672 | of which kernel options are used in a running kernel or in an | |
673 | on-disk kernel. This information can be extracted from the kernel | |
674 | image file with the script scripts/extract-ikconfig and used as | |
675 | input to rebuild the current kernel or to build another kernel. | |
676 | It can also be extracted from a running kernel by reading | |
677 | /proc/config.gz if enabled (below). | |
678 | ||
679 | config IKCONFIG_PROC | |
680 | bool "Enable access to .config through /proc/config.gz" | |
681 | depends on IKCONFIG && PROC_FS | |
a7f7f624 | 682 | help |
1da177e4 LT |
683 | This option enables access to the kernel configuration file |
684 | through /proc/config.gz. | |
685 | ||
f7b101d3 JFG |
686 | config IKHEADERS |
687 | tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz" | |
688 | depends on SYSFS | |
689 | help | |
690 | This option enables access to the in-kernel headers that are generated during | |
691 | the build process. These can be used to build eBPF tracing programs, | |
692 | or similar programs. If you build the headers as a module, a module called | |
693 | kheaders.ko is built which can be loaded on-demand to get access to headers. | |
43d8ce9d | 694 | |
794543a2 AJS |
695 | config LOG_BUF_SHIFT |
696 | int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" | |
550c10d2 JO |
697 | range 12 25 if !H8300 |
698 | range 12 19 if H8300 | |
f17a32e9 | 699 | default 17 |
361e9dfb | 700 | depends on PRINTK |
794543a2 | 701 | help |
23b2899f LR |
702 | Select the minimal kernel log buffer size as a power of 2. |
703 | The final size is affected by LOG_CPU_MAX_BUF_SHIFT config | |
704 | parameter, see below. Any higher size also might be forced | |
705 | by "log_buf_len" boot parameter. | |
706 | ||
f17a32e9 | 707 | Examples: |
23b2899f | 708 | 17 => 128 KB |
f17a32e9 | 709 | 16 => 64 KB |
23b2899f LR |
710 | 15 => 32 KB |
711 | 14 => 16 KB | |
794543a2 AJS |
712 | 13 => 8 KB |
713 | 12 => 4 KB | |
714 | ||
23b2899f LR |
715 | config LOG_CPU_MAX_BUF_SHIFT |
716 | int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" | |
2240a31d | 717 | depends on SMP |
23b2899f LR |
718 | range 0 21 |
719 | default 12 if !BASE_SMALL | |
720 | default 0 if BASE_SMALL | |
361e9dfb | 721 | depends on PRINTK |
23b2899f LR |
722 | help |
723 | This option allows to increase the default ring buffer size | |
724 | according to the number of CPUs. The value defines the contribution | |
725 | of each CPU as a power of 2. The used space is typically only few | |
726 | lines however it might be much more when problems are reported, | |
727 | e.g. backtraces. | |
728 | ||
729 | The increased size means that a new buffer has to be allocated and | |
730 | the original static one is unused. It makes sense only on systems | |
731 | with more CPUs. Therefore this value is used only when the sum of | |
732 | contributions is greater than the half of the default kernel ring | |
733 | buffer as defined by LOG_BUF_SHIFT. The default values are set | |
0f7636e1 | 734 | so that more than 16 CPUs are needed to trigger the allocation. |
23b2899f LR |
735 | |
736 | Also this option is ignored when "log_buf_len" kernel parameter is | |
737 | used as it forces an exact (power of two) size of the ring buffer. | |
738 | ||
739 | The number of possible CPUs is used for this computation ignoring | |
5e0d8d59 GU |
740 | hotplugging making the computation optimal for the worst case |
741 | scenario while allowing a simple algorithm to be used from bootup. | |
23b2899f LR |
742 | |
743 | Examples shift values and their meaning: | |
744 | 17 => 128 KB for each CPU | |
745 | 16 => 64 KB for each CPU | |
746 | 15 => 32 KB for each CPU | |
747 | 14 => 16 KB for each CPU | |
748 | 13 => 8 KB for each CPU | |
749 | 12 => 4 KB for each CPU | |
750 | ||
f92bac3b SS |
751 | config PRINTK_SAFE_LOG_BUF_SHIFT |
752 | int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)" | |
427934b8 PM |
753 | range 10 21 |
754 | default 13 | |
f92bac3b | 755 | depends on PRINTK |
427934b8 | 756 | help |
f92bac3b SS |
757 | Select the size of an alternate printk per-CPU buffer where messages |
758 | printed from usafe contexts are temporary stored. One example would | |
759 | be NMI messages, another one - printk recursion. The messages are | |
760 | copied to the main log buffer in a safe context to avoid a deadlock. | |
761 | The value defines the size as a power of 2. | |
427934b8 | 762 | |
f92bac3b | 763 | Those messages are rare and limited. The largest one is when |
427934b8 PM |
764 | a backtrace is printed. It usually fits into 4KB. Select |
765 | 8KB if you want to be on the safe side. | |
766 | ||
767 | Examples: | |
768 | 17 => 128 KB for each CPU | |
769 | 16 => 64 KB for each CPU | |
770 | 15 => 32 KB for each CPU | |
771 | 14 => 16 KB for each CPU | |
772 | 13 => 8 KB for each CPU | |
773 | 12 => 4 KB for each CPU | |
774 | ||
a5574cf6 IM |
775 | # |
776 | # Architectures with an unreliable sched_clock() should select this: | |
777 | # | |
778 | config HAVE_UNSTABLE_SCHED_CLOCK | |
779 | bool | |
780 | ||
38ff87f7 SB |
781 | config GENERIC_SCHED_CLOCK |
782 | bool | |
783 | ||
69842cba PB |
784 | menu "Scheduler features" |
785 | ||
786 | config UCLAMP_TASK | |
787 | bool "Enable utilization clamping for RT/FAIR tasks" | |
788 | depends on CPU_FREQ_GOV_SCHEDUTIL | |
789 | help | |
790 | This feature enables the scheduler to track the clamped utilization | |
791 | of each CPU based on RUNNABLE tasks scheduled on that CPU. | |
792 | ||
793 | With this option, the user can specify the min and max CPU | |
794 | utilization allowed for RUNNABLE tasks. The max utilization defines | |
795 | the maximum frequency a task should use while the min utilization | |
796 | defines the minimum frequency it should use. | |
797 | ||
798 | Both min and max utilization clamp values are hints to the scheduler, | |
799 | aiming at improving its frequency selection policy, but they do not | |
800 | enforce or grant any specific bandwidth for tasks. | |
801 | ||
802 | If in doubt, say N. | |
803 | ||
804 | config UCLAMP_BUCKETS_COUNT | |
805 | int "Number of supported utilization clamp buckets" | |
806 | range 5 20 | |
807 | default 5 | |
808 | depends on UCLAMP_TASK | |
809 | help | |
810 | Defines the number of clamp buckets to use. The range of each bucket | |
811 | will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the | |
812 | number of clamp buckets the finer their granularity and the higher | |
813 | the precision of clamping aggregation and tracking at run-time. | |
814 | ||
815 | For example, with the minimum configuration value we will have 5 | |
816 | clamp buckets tracking 20% utilization each. A 25% boosted tasks will | |
817 | be refcounted in the [20..39]% bucket and will set the bucket clamp | |
818 | effective value to 25%. | |
819 | If a second 30% boosted task should be co-scheduled on the same CPU, | |
820 | that task will be refcounted in the same bucket of the first task and | |
821 | it will boost the bucket clamp effective value to 30%. | |
822 | The clamp effective value of a bucket is reset to its nominal value | |
823 | (20% in the example above) when there are no more tasks refcounted in | |
824 | that bucket. | |
825 | ||
826 | An additional boost/capping margin can be added to some tasks. In the | |
827 | example above the 25% task will be boosted to 30% until it exits the | |
828 | CPU. If that should be considered not acceptable on certain systems, | |
829 | it's always possible to reduce the margin by increasing the number of | |
830 | clamp buckets to trade off used memory for run-time tracking | |
831 | precision. | |
832 | ||
833 | If in doubt, use the default value. | |
834 | ||
835 | endmenu | |
836 | ||
be3a7284 AA |
837 | # |
838 | # For architectures that want to enable the support for NUMA-affine scheduler | |
839 | # balancing logic: | |
840 | # | |
841 | config ARCH_SUPPORTS_NUMA_BALANCING | |
842 | bool | |
843 | ||
72b252ae MG |
844 | # |
845 | # For architectures that prefer to flush all TLBs after a number of pages | |
846 | # are unmapped instead of sending one IPI per page to flush. The architecture | |
847 | # must provide guarantees on what happens if a clean TLB cache entry is | |
848 | # written after the unmap. Details are in mm/rmap.c near the check for | |
849 | # should_defer_flush. The architecture should also consider if the full flush | |
850 | # and the refill costs are offset by the savings of sending fewer IPIs. | |
851 | config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH | |
852 | bool | |
853 | ||
c12d3362 | 854 | config CC_HAS_INT128 |
3a7c7331 | 855 | def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT |
c12d3362 | 856 | |
be5e610c PZ |
857 | # |
858 | # For architectures that know their GCC __int128 support is sound | |
859 | # | |
860 | config ARCH_SUPPORTS_INT128 | |
861 | bool | |
862 | ||
be3a7284 AA |
863 | # For architectures that (ab)use NUMA to represent different memory regions |
864 | # all cpu-local but of different latencies, such as SuperH. | |
865 | # | |
866 | config ARCH_WANT_NUMA_VARIABLE_LOCALITY | |
867 | bool | |
868 | ||
be3a7284 AA |
869 | config NUMA_BALANCING |
870 | bool "Memory placement aware NUMA scheduler" | |
be3a7284 AA |
871 | depends on ARCH_SUPPORTS_NUMA_BALANCING |
872 | depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY | |
873 | depends on SMP && NUMA && MIGRATION | |
874 | help | |
875 | This option adds support for automatic NUMA aware memory/task placement. | |
876 | The mechanism is quite primitive and is based on migrating memory when | |
6d56a410 | 877 | it has references to the node the task is running on. |
be3a7284 AA |
878 | |
879 | This system will be inactive on UMA systems. | |
880 | ||
6f7c97e8 AK |
881 | config NUMA_BALANCING_DEFAULT_ENABLED |
882 | bool "Automatically enable NUMA aware memory/task placement" | |
883 | default y | |
884 | depends on NUMA_BALANCING | |
885 | help | |
886 | If set, automatic NUMA balancing will be enabled if running on a NUMA | |
887 | machine. | |
888 | ||
23964d2d | 889 | menuconfig CGROUPS |
6341e62b | 890 | bool "Control Group support" |
2bd59d48 | 891 | select KERNFS |
5cdc38f9 | 892 | help |
23964d2d | 893 | This option adds support for grouping sets of processes together, for |
5cdc38f9 KH |
894 | use with process control subsystems such as Cpusets, CFS, memory |
895 | controls or device isolation. | |
896 | See | |
d6a3b247 | 897 | - Documentation/scheduler/sched-design-CFS.rst (CFS) |
da82c92f | 898 | - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation |
45ce80fb | 899 | and resource control) |
5cdc38f9 KH |
900 | |
901 | Say N if unsure. | |
902 | ||
23964d2d LZ |
903 | if CGROUPS |
904 | ||
3e32cb2e | 905 | config PAGE_COUNTER |
e8cf4e9c | 906 | bool |
3e32cb2e | 907 | |
c255a458 | 908 | config MEMCG |
a0166ec4 | 909 | bool "Memory controller" |
3e32cb2e | 910 | select PAGE_COUNTER |
79bd9814 | 911 | select EVENTFD |
00f0b825 | 912 | help |
a0166ec4 | 913 | Provides control over the memory footprint of tasks in a cgroup. |
00f0b825 | 914 | |
c255a458 | 915 | config MEMCG_SWAP |
2d1c4980 | 916 | bool |
c255a458 | 917 | depends on MEMCG && SWAP |
a42c390c | 918 | default y |
c077719b | 919 | |
84c07d11 KT |
920 | config MEMCG_KMEM |
921 | bool | |
922 | depends on MEMCG && !SLOB | |
923 | default y | |
924 | ||
6bf024e6 JW |
925 | config BLK_CGROUP |
926 | bool "IO controller" | |
927 | depends on BLOCK | |
2bc64a20 | 928 | default n |
a7f7f624 | 929 | help |
6bf024e6 JW |
930 | Generic block IO controller cgroup interface. This is the common |
931 | cgroup interface which should be used by various IO controlling | |
932 | policies. | |
2bc64a20 | 933 | |
6bf024e6 JW |
934 | Currently, CFQ IO scheduler uses it to recognize task groups and |
935 | control disk bandwidth allocation (proportional time slice allocation) | |
936 | to such task groups. It is also used by bio throttling logic in | |
937 | block layer to implement upper limit in IO rates on a device. | |
e5d1367f | 938 | |
6bf024e6 JW |
939 | This option only enables generic Block IO controller infrastructure. |
940 | One needs to also enable actual IO controlling logic/policy. For | |
941 | enabling proportional weight division of disk bandwidth in CFQ, set | |
7baf2199 | 942 | CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set |
6bf024e6 JW |
943 | CONFIG_BLK_DEV_THROTTLING=y. |
944 | ||
da82c92f | 945 | See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information. |
6bf024e6 | 946 | |
6bf024e6 JW |
947 | config CGROUP_WRITEBACK |
948 | bool | |
949 | depends on MEMCG && BLK_CGROUP | |
950 | default y | |
e5d1367f | 951 | |
7c941438 | 952 | menuconfig CGROUP_SCHED |
a0166ec4 | 953 | bool "CPU controller" |
7c941438 DG |
954 | default n |
955 | help | |
956 | This feature lets CPU scheduler recognize task groups and control CPU | |
957 | bandwidth allocation to such task groups. It uses cgroups to group | |
958 | tasks. | |
959 | ||
960 | if CGROUP_SCHED | |
961 | config FAIR_GROUP_SCHED | |
962 | bool "Group scheduling for SCHED_OTHER" | |
963 | depends on CGROUP_SCHED | |
964 | default CGROUP_SCHED | |
965 | ||
ab84d31e PT |
966 | config CFS_BANDWIDTH |
967 | bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" | |
ab84d31e PT |
968 | depends on FAIR_GROUP_SCHED |
969 | default n | |
970 | help | |
971 | This option allows users to define CPU bandwidth rates (limits) for | |
972 | tasks running within the fair group scheduler. Groups with no limit | |
973 | set are considered to be unconstrained and will run with no | |
974 | restriction. | |
d6a3b247 | 975 | See Documentation/scheduler/sched-bwc.rst for more information. |
ab84d31e | 976 | |
7c941438 DG |
977 | config RT_GROUP_SCHED |
978 | bool "Group scheduling for SCHED_RR/FIFO" | |
7c941438 DG |
979 | depends on CGROUP_SCHED |
980 | default n | |
981 | help | |
982 | This feature lets you explicitly allocate real CPU bandwidth | |
32bd7eb5 | 983 | to task groups. If enabled, it will also make it impossible to |
7c941438 DG |
984 | schedule realtime tasks for non-root users until you allocate |
985 | realtime bandwidth for them. | |
d6a3b247 | 986 | See Documentation/scheduler/sched-rt-group.rst for more information. |
7c941438 DG |
987 | |
988 | endif #CGROUP_SCHED | |
989 | ||
2480c093 PB |
990 | config UCLAMP_TASK_GROUP |
991 | bool "Utilization clamping per group of tasks" | |
992 | depends on CGROUP_SCHED | |
993 | depends on UCLAMP_TASK | |
994 | default n | |
995 | help | |
996 | This feature enables the scheduler to track the clamped utilization | |
997 | of each CPU based on RUNNABLE tasks currently scheduled on that CPU. | |
998 | ||
999 | When this option is enabled, the user can specify a min and max | |
1000 | CPU bandwidth which is allowed for each single task in a group. | |
1001 | The max bandwidth allows to clamp the maximum frequency a task | |
1002 | can use, while the min bandwidth allows to define a minimum | |
1003 | frequency a task will always use. | |
1004 | ||
1005 | When task group based utilization clamping is enabled, an eventually | |
1006 | specified task-specific clamp value is constrained by the cgroup | |
1007 | specified clamp value. Both minimum and maximum task clamping cannot | |
1008 | be bigger than the corresponding clamping defined at task group level. | |
1009 | ||
1010 | If in doubt, say N. | |
1011 | ||
6bf024e6 JW |
1012 | config CGROUP_PIDS |
1013 | bool "PIDs controller" | |
1014 | help | |
1015 | Provides enforcement of process number limits in the scope of a | |
1016 | cgroup. Any attempt to fork more processes than is allowed in the | |
1017 | cgroup will fail. PIDs are fundamentally a global resource because it | |
1018 | is fairly trivial to reach PID exhaustion before you reach even a | |
1019 | conservative kmemcg limit. As a result, it is possible to grind a | |
1020 | system to halt without being limited by other cgroup policies. The | |
6cc578df | 1021 | PIDs controller is designed to stop this from happening. |
6bf024e6 JW |
1022 | |
1023 | It should be noted that organisational operations (such as attaching | |
98076833 | 1024 | to a cgroup hierarchy) will *not* be blocked by the PIDs controller, |
6bf024e6 JW |
1025 | since the PIDs limit only affects a process's ability to fork, not to |
1026 | attach to a cgroup. | |
1027 | ||
39d3e758 PP |
1028 | config CGROUP_RDMA |
1029 | bool "RDMA controller" | |
1030 | help | |
1031 | Provides enforcement of RDMA resources defined by IB stack. | |
1032 | It is fairly easy for consumers to exhaust RDMA resources, which | |
1033 | can result into resource unavailability to other consumers. | |
1034 | RDMA controller is designed to stop this from happening. | |
1035 | Attaching processes with active RDMA resources to the cgroup | |
1036 | hierarchy is allowed even if can cross the hierarchy's limit. | |
1037 | ||
6bf024e6 JW |
1038 | config CGROUP_FREEZER |
1039 | bool "Freezer controller" | |
1040 | help | |
1041 | Provides a way to freeze and unfreeze all tasks in a | |
1042 | cgroup. | |
1043 | ||
489c2a20 JW |
1044 | This option affects the ORIGINAL cgroup interface. The cgroup2 memory |
1045 | controller includes important in-kernel memory consumers per default. | |
1046 | ||
1047 | If you're using cgroup2, say N. | |
1048 | ||
6bf024e6 JW |
1049 | config CGROUP_HUGETLB |
1050 | bool "HugeTLB controller" | |
1051 | depends on HUGETLB_PAGE | |
1052 | select PAGE_COUNTER | |
afc24d49 | 1053 | default n |
6bf024e6 JW |
1054 | help |
1055 | Provides a cgroup controller for HugeTLB pages. | |
1056 | When you enable this, you can put a per cgroup limit on HugeTLB usage. | |
1057 | The limit is enforced during page fault. Since HugeTLB doesn't | |
1058 | support page reclaim, enforcing the limit at page fault time implies | |
1059 | that, the application will get SIGBUS signal if it tries to access | |
1060 | HugeTLB pages beyond its limit. This requires the application to know | |
1061 | beforehand how much HugeTLB pages it would require for its use. The | |
1062 | control group is tracked in the third page lru pointer. This means | |
1063 | that we cannot use the controller with huge page less than 3 pages. | |
afc24d49 | 1064 | |
6bf024e6 JW |
1065 | config CPUSETS |
1066 | bool "Cpuset controller" | |
e1d4eeec | 1067 | depends on SMP |
6bf024e6 JW |
1068 | help |
1069 | This option will let you create and manage CPUSETs which | |
1070 | allow dynamically partitioning a system into sets of CPUs and | |
1071 | Memory Nodes and assigning tasks to run only within those sets. | |
1072 | This is primarily useful on large SMP or NUMA systems. | |
afc24d49 | 1073 | |
6bf024e6 | 1074 | Say N if unsure. |
afc24d49 | 1075 | |
6bf024e6 JW |
1076 | config PROC_PID_CPUSET |
1077 | bool "Include legacy /proc/<pid>/cpuset file" | |
1078 | depends on CPUSETS | |
1079 | default y | |
afc24d49 | 1080 | |
6bf024e6 JW |
1081 | config CGROUP_DEVICE |
1082 | bool "Device controller" | |
1083 | help | |
1084 | Provides a cgroup controller implementing whitelists for | |
1085 | devices which a process in the cgroup can mknod or open. | |
1086 | ||
1087 | config CGROUP_CPUACCT | |
1088 | bool "Simple CPU accounting controller" | |
1089 | help | |
1090 | Provides a simple controller for monitoring the | |
1091 | total CPU consumed by the tasks in a cgroup. | |
1092 | ||
1093 | config CGROUP_PERF | |
1094 | bool "Perf controller" | |
1095 | depends on PERF_EVENTS | |
1096 | help | |
1097 | This option extends the perf per-cpu mode to restrict monitoring | |
1098 | to threads which belong to the cgroup specified and run on the | |
6546b19f NK |
1099 | designated cpu. Or this can be used to have cgroup ID in samples |
1100 | so that it can monitor performance events among cgroups. | |
6bf024e6 JW |
1101 | |
1102 | Say N if unsure. | |
1103 | ||
30070984 DM |
1104 | config CGROUP_BPF |
1105 | bool "Support for eBPF programs attached to cgroups" | |
483c4933 AL |
1106 | depends on BPF_SYSCALL |
1107 | select SOCK_CGROUP_DATA | |
30070984 DM |
1108 | help |
1109 | Allow attaching eBPF programs to a cgroup using the bpf(2) | |
1110 | syscall command BPF_PROG_ATTACH. | |
1111 | ||
1112 | In which context these programs are accessed depends on the type | |
1113 | of attachment. For instance, programs that are attached using | |
1114 | BPF_CGROUP_INET_INGRESS will be executed on the ingress path of | |
1115 | inet sockets. | |
1116 | ||
a72232ea VS |
1117 | config CGROUP_MISC |
1118 | bool "Misc resource controller" | |
1119 | default n | |
1120 | help | |
1121 | Provides a controller for miscellaneous resources on a host. | |
1122 | ||
1123 | Miscellaneous scalar resources are the resources on the host system | |
1124 | which cannot be abstracted like the other cgroups. This controller | |
1125 | tracks and limits the miscellaneous resources used by a process | |
1126 | attached to a cgroup hierarchy. | |
1127 | ||
1128 | For more information, please check misc cgroup section in | |
1129 | /Documentation/admin-guide/cgroup-v2.rst. | |
1130 | ||
6bf024e6 | 1131 | config CGROUP_DEBUG |
23b0be48 | 1132 | bool "Debug controller" |
afc24d49 | 1133 | default n |
23b0be48 | 1134 | depends on DEBUG_KERNEL |
6bf024e6 JW |
1135 | help |
1136 | This option enables a simple controller that exports | |
23b0be48 WL |
1137 | debugging information about the cgroups framework. This |
1138 | controller is for control cgroup debugging only. Its | |
1139 | interfaces are not stable. | |
afc24d49 | 1140 | |
6bf024e6 | 1141 | Say N. |
89e9b9e0 | 1142 | |
73b35147 AB |
1143 | config SOCK_CGROUP_DATA |
1144 | bool | |
1145 | default n | |
1146 | ||
23964d2d | 1147 | endif # CGROUPS |
c077719b | 1148 | |
8dd2a82c | 1149 | menuconfig NAMESPACES |
6a108a14 | 1150 | bool "Namespaces support" if EXPERT |
2813893f | 1151 | depends on MULTIUSER |
6a108a14 | 1152 | default !EXPERT |
c5289a69 PE |
1153 | help |
1154 | Provides the way to make tasks work with different objects using | |
1155 | the same id. For example same IPC id may refer to different objects | |
1156 | or same user id or pid may refer to different tasks when used in | |
1157 | different namespaces. | |
1158 | ||
8dd2a82c DL |
1159 | if NAMESPACES |
1160 | ||
58bfdd6d PE |
1161 | config UTS_NS |
1162 | bool "UTS namespace" | |
17a6d441 | 1163 | default y |
58bfdd6d PE |
1164 | help |
1165 | In this namespace tasks see different info provided with the | |
1166 | uname() system call | |
1167 | ||
769071ac AV |
1168 | config TIME_NS |
1169 | bool "TIME namespace" | |
660fd04f | 1170 | depends on GENERIC_VDSO_TIME_NS |
769071ac AV |
1171 | default y |
1172 | help | |
1173 | In this namespace boottime and monotonic clocks can be set. | |
1174 | The time will keep going with the same pace. | |
1175 | ||
ae5e1b22 PE |
1176 | config IPC_NS |
1177 | bool "IPC namespace" | |
8dd2a82c | 1178 | depends on (SYSVIPC || POSIX_MQUEUE) |
17a6d441 | 1179 | default y |
ae5e1b22 PE |
1180 | help |
1181 | In this namespace tasks work with IPC ids which correspond to | |
614b84cf | 1182 | different IPC objects in different namespaces. |
ae5e1b22 | 1183 | |
aee16ce7 | 1184 | config USER_NS |
19c92399 | 1185 | bool "User namespace" |
5673a94c | 1186 | default n |
aee16ce7 PE |
1187 | help |
1188 | This allows containers, i.e. vservers, to use user namespaces | |
1189 | to provide different user info for different servers. | |
e11f0ae3 EB |
1190 | |
1191 | When user namespaces are enabled in the kernel it is | |
d886f4e4 JW |
1192 | recommended that the MEMCG option also be enabled and that |
1193 | user-space use the memory control groups to limit the amount | |
1194 | of memory a memory unprivileged users can use. | |
e11f0ae3 | 1195 | |
aee16ce7 PE |
1196 | If unsure, say N. |
1197 | ||
74bd59bb | 1198 | config PID_NS |
9bd38c2c | 1199 | bool "PID Namespaces" |
17a6d441 | 1200 | default y |
74bd59bb | 1201 | help |
12d2b8f9 | 1202 | Support process id namespaces. This allows having multiple |
692105b8 | 1203 | processes with the same pid as long as they are in different |
74bd59bb PE |
1204 | pid namespaces. This is a building block of containers. |
1205 | ||
d6eb633f MH |
1206 | config NET_NS |
1207 | bool "Network namespace" | |
8dd2a82c | 1208 | depends on NET |
17a6d441 | 1209 | default y |
d6eb633f MH |
1210 | help |
1211 | Allow user space to create what appear to be multiple instances | |
1212 | of the network stack. | |
1213 | ||
8dd2a82c DL |
1214 | endif # NAMESPACES |
1215 | ||
5cb366bb AR |
1216 | config CHECKPOINT_RESTORE |
1217 | bool "Checkpoint/restore support" | |
1218 | select PROC_CHILDREN | |
bfe3911a | 1219 | select KCMP |
5cb366bb AR |
1220 | default n |
1221 | help | |
1222 | Enables additional kernel features in a sake of checkpoint/restore. | |
1223 | In particular it adds auxiliary prctl codes to setup process text, | |
1224 | data and heap segment sizes, and a few additional /proc filesystem | |
1225 | entries. | |
1226 | ||
1227 | If unsure, say N here. | |
1228 | ||
5091faa4 MG |
1229 | config SCHED_AUTOGROUP |
1230 | bool "Automatic process group scheduling" | |
5091faa4 MG |
1231 | select CGROUPS |
1232 | select CGROUP_SCHED | |
1233 | select FAIR_GROUP_SCHED | |
1234 | help | |
1235 | This option optimizes the scheduler for common desktop workloads by | |
1236 | automatically creating and populating task groups. This separation | |
1237 | of workloads isolates aggressive CPU burners (like build jobs) from | |
1238 | desktop applications. Task group autogeneration is currently based | |
1239 | upon task session. | |
1240 | ||
7af37bec | 1241 | config SYSFS_DEPRECATED |
5d6a4ea5 | 1242 | bool "Enable deprecated sysfs features to support old userspace tools" |
7af37bec DL |
1243 | depends on SYSFS |
1244 | default n | |
1245 | help | |
1246 | This option adds code that switches the layout of the "block" class | |
1247 | devices, to not show up in /sys/class/block/, but only in | |
1248 | /sys/block/. | |
1249 | ||
1250 | This switch is only active when the sysfs.deprecated=1 boot option is | |
1251 | passed or the SYSFS_DEPRECATED_V2 option is set. | |
1252 | ||
1253 | This option allows new kernels to run on old distributions and tools, | |
1254 | which might get confused by /sys/class/block/. Since 2007/2008 all | |
1255 | major distributions and tools handle this just fine. | |
1256 | ||
1257 | Recent distributions and userspace tools after 2009/2010 depend on | |
1258 | the existence of /sys/class/block/, and will not work with this | |
1259 | option enabled. | |
1260 | ||
1261 | Only if you are using a new kernel on an old distribution, you might | |
1262 | need to say Y here. | |
1263 | ||
1264 | config SYSFS_DEPRECATED_V2 | |
5d6a4ea5 | 1265 | bool "Enable deprecated sysfs features by default" |
7af37bec DL |
1266 | default n |
1267 | depends on SYSFS | |
1268 | depends on SYSFS_DEPRECATED | |
1269 | help | |
1270 | Enable deprecated sysfs by default. | |
1271 | ||
1272 | See the CONFIG_SYSFS_DEPRECATED option for more details about this | |
1273 | option. | |
1274 | ||
1275 | Only if you are using a new kernel on an old distribution, you might | |
1276 | need to say Y here. Even then, odds are you would not need it | |
1277 | enabled, you can always pass the boot option if absolutely necessary. | |
1278 | ||
1279 | config RELAY | |
1280 | bool "Kernel->user space relay support (formerly relayfs)" | |
26b5679e | 1281 | select IRQ_WORK |
7af37bec DL |
1282 | help |
1283 | This option enables support for relay interface support in | |
1284 | certain file systems (such as debugfs). | |
1285 | It is designed to provide an efficient mechanism for tools and | |
1286 | facilities to relay large amounts of data from kernel space to | |
1287 | user space. | |
1288 | ||
1289 | If unsure, say N. | |
1290 | ||
f991633d DG |
1291 | config BLK_DEV_INITRD |
1292 | bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" | |
f991633d DG |
1293 | help |
1294 | The initial RAM filesystem is a ramfs which is loaded by the | |
1295 | boot loader (loadlin or lilo) and that is mounted as root | |
1296 | before the normal boot procedure. It is typically used to | |
1297 | load modules needed to mount the "real" root file system, | |
8c27ceff | 1298 | etc. See <file:Documentation/admin-guide/initrd.rst> for details. |
f991633d DG |
1299 | |
1300 | If RAM disk support (BLK_DEV_RAM) is also included, this | |
1301 | also enables initial RAM disk (initrd) support and adds | |
1302 | 15 Kbytes (more on some other architectures) to the kernel size. | |
1303 | ||
1304 | If unsure say Y. | |
1305 | ||
c33df4ea JPS |
1306 | if BLK_DEV_INITRD |
1307 | ||
dbec4866 SR |
1308 | source "usr/Kconfig" |
1309 | ||
c33df4ea JPS |
1310 | endif |
1311 | ||
76db5a27 MH |
1312 | config BOOT_CONFIG |
1313 | bool "Boot config support" | |
2910b5aa | 1314 | select BLK_DEV_INITRD |
76db5a27 MH |
1315 | help |
1316 | Extra boot config allows system admin to pass a config file as | |
1317 | complemental extension of kernel cmdline when booting. | |
0947db01 | 1318 | The boot config file must be attached at the end of initramfs |
85c46b78 | 1319 | with checksum, size and magic word. |
0947db01 | 1320 | See <file:Documentation/admin-guide/bootconfig.rst> for details. |
76db5a27 MH |
1321 | |
1322 | If unsure, say Y. | |
1323 | ||
877417e6 AB |
1324 | choice |
1325 | prompt "Compiler optimization level" | |
2cc3ce24 | 1326 | default CC_OPTIMIZE_FOR_PERFORMANCE |
877417e6 AB |
1327 | |
1328 | config CC_OPTIMIZE_FOR_PERFORMANCE | |
15f5db60 | 1329 | bool "Optimize for performance (-O2)" |
877417e6 AB |
1330 | help |
1331 | This is the default optimization level for the kernel, building | |
1332 | with the "-O2" compiler flag for best performance and most | |
1333 | helpful compile-time warnings. | |
1334 | ||
15f5db60 MY |
1335 | config CC_OPTIMIZE_FOR_PERFORMANCE_O3 |
1336 | bool "Optimize more for performance (-O3)" | |
1337 | depends on ARC | |
c45b4f1f | 1338 | help |
15f5db60 MY |
1339 | Choosing this option will pass "-O3" to your compiler to optimize |
1340 | the kernel yet more for performance. | |
c45b4f1f | 1341 | |
c45b4f1f | 1342 | config CC_OPTIMIZE_FOR_SIZE |
15f5db60 | 1343 | bool "Optimize for size (-Os)" |
c45b4f1f | 1344 | help |
ce3b487f MY |
1345 | Choosing this option will pass "-Os" to your compiler resulting |
1346 | in a smaller kernel. | |
c45b4f1f | 1347 | |
877417e6 AB |
1348 | endchoice |
1349 | ||
5d20ee31 NP |
1350 | config HAVE_LD_DEAD_CODE_DATA_ELIMINATION |
1351 | bool | |
1352 | help | |
1353 | This requires that the arch annotates or otherwise protects | |
1354 | its external entry points from being discarded. Linker scripts | |
1355 | must also merge .text.*, .data.*, and .bss.* correctly into | |
1356 | output sections. Care must be taken not to pull in unrelated | |
1357 | sections (e.g., '.text.init'). Typically '.' in section names | |
1358 | is used to distinguish them from label names / C identifiers. | |
1359 | ||
1360 | config LD_DEAD_CODE_DATA_ELIMINATION | |
1361 | bool "Dead code and data elimination (EXPERIMENTAL)" | |
1362 | depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION | |
1363 | depends on EXPERT | |
e85d1d65 MY |
1364 | depends on $(cc-option,-ffunction-sections -fdata-sections) |
1365 | depends on $(ld-option,--gc-sections) | |
5d20ee31 | 1366 | help |
8b9d2712 MY |
1367 | Enable this if you want to do dead code and data elimination with |
1368 | the linker by compiling with -ffunction-sections -fdata-sections, | |
1369 | and linking with --gc-sections. | |
5d20ee31 NP |
1370 | |
1371 | This can reduce on disk and in-memory size of the kernel | |
1372 | code and static data, particularly for small configs and | |
1373 | on small systems. This has the possibility of introducing | |
1374 | silently broken kernel if the required annotations are not | |
1375 | present. This option is not well tested yet, so use at your | |
1376 | own risk. | |
1377 | ||
59612b24 NC |
1378 | config LD_ORPHAN_WARN |
1379 | def_bool y | |
1380 | depends on ARCH_WANT_LD_ORPHAN_WARN | |
d5750cd3 | 1381 | depends on !LD_IS_LLD || LLD_VERSION >= 110000 |
59612b24 NC |
1382 | depends on $(ld-option,--orphan-handling=warn) |
1383 | ||
0847062a RD |
1384 | config SYSCTL |
1385 | bool | |
1386 | ||
657a5209 MF |
1387 | config HAVE_UID16 |
1388 | bool | |
1389 | ||
1390 | config SYSCTL_EXCEPTION_TRACE | |
1391 | bool | |
1392 | help | |
1393 | Enable support for /proc/sys/debug/exception-trace. | |
1394 | ||
1395 | config SYSCTL_ARCH_UNALIGN_NO_WARN | |
1396 | bool | |
1397 | help | |
1398 | Enable support for /proc/sys/kernel/ignore-unaligned-usertrap | |
1399 | Allows arch to define/use @no_unaligned_warning to possibly warn | |
1400 | about unaligned access emulation going on under the hood. | |
1401 | ||
1402 | config SYSCTL_ARCH_UNALIGN_ALLOW | |
1403 | bool | |
1404 | help | |
1405 | Enable support for /proc/sys/kernel/unaligned-trap | |
1406 | Allows arches to define/use @unaligned_enabled to runtime toggle | |
1407 | the unaligned access emulation. | |
1408 | see arch/parisc/kernel/unaligned.c for reference | |
1409 | ||
657a5209 MF |
1410 | config HAVE_PCSPKR_PLATFORM |
1411 | bool | |
1412 | ||
f89b7755 AS |
1413 | # interpreter that classic socket filters depend on |
1414 | config BPF | |
1415 | bool | |
1416 | ||
6a108a14 DR |
1417 | menuconfig EXPERT |
1418 | bool "Configure standard kernel features (expert users)" | |
f505c553 JT |
1419 | # Unhide debug options, to make the on-by-default options visible |
1420 | select DEBUG_KERNEL | |
1da177e4 LT |
1421 | help |
1422 | This option allows certain base kernel options and settings | |
e8cf4e9c KK |
1423 | to be disabled or tweaked. This is for specialized |
1424 | environments which can tolerate a "non-standard" kernel. | |
1425 | Only use this if you really know what you are doing. | |
1da177e4 | 1426 | |
ae81f9e3 | 1427 | config UID16 |
6a108a14 | 1428 | bool "Enable 16-bit UID system calls" if EXPERT |
2813893f | 1429 | depends on HAVE_UID16 && MULTIUSER |
ae81f9e3 CE |
1430 | default y |
1431 | help | |
1432 | This enables the legacy 16-bit UID syscall wrappers. | |
1433 | ||
2813893f IM |
1434 | config MULTIUSER |
1435 | bool "Multiple users, groups and capabilities support" if EXPERT | |
1436 | default y | |
1437 | help | |
1438 | This option enables support for non-root users, groups and | |
1439 | capabilities. | |
1440 | ||
1441 | If you say N here, all processes will run with UID 0, GID 0, and all | |
1442 | possible capabilities. Saying N here also compiles out support for | |
1443 | system calls related to UIDs, GIDs, and capabilities, such as setuid, | |
1444 | setgid, and capset. | |
1445 | ||
1446 | If unsure, say Y here. | |
1447 | ||
f6187769 FF |
1448 | config SGETMASK_SYSCALL |
1449 | bool "sgetmask/ssetmask syscalls support" if EXPERT | |
a687a533 | 1450 | def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH |
a7f7f624 | 1451 | help |
f6187769 FF |
1452 | sys_sgetmask and sys_ssetmask are obsolete system calls |
1453 | no longer supported in libc but still enabled by default in some | |
1454 | architectures. | |
1455 | ||
1456 | If unsure, leave the default option here. | |
1457 | ||
6af9f7bf FF |
1458 | config SYSFS_SYSCALL |
1459 | bool "Sysfs syscall support" if EXPERT | |
1460 | default y | |
a7f7f624 | 1461 | help |
6af9f7bf FF |
1462 | sys_sysfs is an obsolete system call no longer supported in libc. |
1463 | Note that disabling this option is more secure but might break | |
1464 | compatibility with some systems. | |
1465 | ||
1466 | If unsure say Y here. | |
1467 | ||
d1b069f5 RD |
1468 | config FHANDLE |
1469 | bool "open by fhandle syscalls" if EXPERT | |
1470 | select EXPORTFS | |
1471 | default y | |
1472 | help | |
1473 | If you say Y here, a user level program will be able to map | |
1474 | file names to handle and then later use the handle for | |
1475 | different file system operations. This is useful in implementing | |
1476 | userspace file servers, which now track files using handles instead | |
1477 | of names. The handle would remain the same even if file names | |
1478 | get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) | |
1479 | syscalls. | |
1480 | ||
baa73d9e NP |
1481 | config POSIX_TIMERS |
1482 | bool "Posix Clocks & timers" if EXPERT | |
1483 | default y | |
1484 | help | |
1485 | This includes native support for POSIX timers to the kernel. | |
1486 | Some embedded systems have no use for them and therefore they | |
1487 | can be configured out to reduce the size of the kernel image. | |
1488 | ||
1489 | When this option is disabled, the following syscalls won't be | |
1490 | available: timer_create, timer_gettime: timer_getoverrun, | |
1491 | timer_settime, timer_delete, clock_adjtime, getitimer, | |
1492 | setitimer, alarm. Furthermore, the clock_settime, clock_gettime, | |
1493 | clock_getres and clock_nanosleep syscalls will be limited to | |
1494 | CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. | |
1495 | ||
1496 | If unsure say y. | |
1497 | ||
d59745ce MM |
1498 | config PRINTK |
1499 | default y | |
6a108a14 | 1500 | bool "Enable support for printk" if EXPERT |
74876a98 | 1501 | select IRQ_WORK |
d59745ce MM |
1502 | help |
1503 | This option enables normal printk support. Removing it | |
1504 | eliminates most of the message strings from the kernel image | |
1505 | and makes the kernel more or less silent. As this makes it | |
1506 | very difficult to diagnose system problems, saying N here is | |
1507 | strongly discouraged. | |
1508 | ||
42a0bb3f PM |
1509 | config PRINTK_NMI |
1510 | def_bool y | |
1511 | depends on PRINTK | |
1512 | depends on HAVE_NMI | |
1513 | ||
c8538a7a | 1514 | config BUG |
6a108a14 | 1515 | bool "BUG() support" if EXPERT |
c8538a7a MM |
1516 | default y |
1517 | help | |
e8cf4e9c KK |
1518 | Disabling this option eliminates support for BUG and WARN, reducing |
1519 | the size of your kernel image and potentially quietly ignoring | |
1520 | numerous fatal conditions. You should only consider disabling this | |
1521 | option for embedded systems with no facilities for reporting errors. | |
1522 | Just say Y. | |
c8538a7a | 1523 | |
708e9a79 | 1524 | config ELF_CORE |
046d662f | 1525 | depends on COREDUMP |
708e9a79 | 1526 | default y |
6a108a14 | 1527 | bool "Enable ELF core dumps" if EXPERT |
708e9a79 MM |
1528 | help |
1529 | Enable support for generating core dumps. Disabling saves about 4k. | |
1530 | ||
8761f1ab | 1531 | |
e5e1d3cb | 1532 | config PCSPKR_PLATFORM |
6a108a14 | 1533 | bool "Enable PC-Speaker support" if EXPERT |
8761f1ab | 1534 | depends on HAVE_PCSPKR_PLATFORM |
15f304b6 | 1535 | select I8253_LOCK |
e5e1d3cb SS |
1536 | default y |
1537 | help | |
e8cf4e9c KK |
1538 | This option allows to disable the internal PC-Speaker |
1539 | support, saving some memory. | |
e5e1d3cb | 1540 | |
1da177e4 LT |
1541 | config BASE_FULL |
1542 | default y | |
6a108a14 | 1543 | bool "Enable full-sized data structures for core" if EXPERT |
1da177e4 LT |
1544 | help |
1545 | Disabling this option reduces the size of miscellaneous core | |
1546 | kernel data structures. This saves memory on small machines, | |
1547 | but may reduce performance. | |
1548 | ||
1549 | config FUTEX | |
6a108a14 | 1550 | bool "Enable futex support" if EXPERT |
1da177e4 | 1551 | default y |
bc2eecd7 | 1552 | imply RT_MUTEXES |
1da177e4 LT |
1553 | help |
1554 | Disabling this option will cause the kernel to be built without | |
1555 | support for "fast userspace mutexes". The resulting kernel may not | |
1556 | run glibc-based applications correctly. | |
1557 | ||
bc2eecd7 NP |
1558 | config FUTEX_PI |
1559 | bool | |
1560 | depends on FUTEX && RT_MUTEXES | |
1561 | default y | |
1562 | ||
03b8c7b6 HC |
1563 | config HAVE_FUTEX_CMPXCHG |
1564 | bool | |
62b4d204 | 1565 | depends on FUTEX |
03b8c7b6 HC |
1566 | help |
1567 | Architectures should select this if futex_atomic_cmpxchg_inatomic() | |
1568 | is implemented and always working. This removes a couple of runtime | |
1569 | checks. | |
1570 | ||
1da177e4 | 1571 | config EPOLL |
6a108a14 | 1572 | bool "Enable eventpoll support" if EXPERT |
1da177e4 LT |
1573 | default y |
1574 | help | |
1575 | Disabling this option will cause the kernel to be built without | |
1576 | support for epoll family of system calls. | |
1577 | ||
fba2afaa | 1578 | config SIGNALFD |
6a108a14 | 1579 | bool "Enable signalfd() system call" if EXPERT |
fba2afaa DL |
1580 | default y |
1581 | help | |
1582 | Enable the signalfd() system call that allows to receive signals | |
1583 | on a file descriptor. | |
1584 | ||
1585 | If unsure, say Y. | |
1586 | ||
b215e283 | 1587 | config TIMERFD |
6a108a14 | 1588 | bool "Enable timerfd() system call" if EXPERT |
b215e283 DL |
1589 | default y |
1590 | help | |
1591 | Enable the timerfd() system call that allows to receive timer | |
1592 | events on a file descriptor. | |
1593 | ||
1594 | If unsure, say Y. | |
1595 | ||
e1ad7468 | 1596 | config EVENTFD |
6a108a14 | 1597 | bool "Enable eventfd() system call" if EXPERT |
e1ad7468 DL |
1598 | default y |
1599 | help | |
1600 | Enable the eventfd() system call that allows to receive both | |
1601 | kernel notification (ie. KAIO) or userspace notifications. | |
1602 | ||
1603 | If unsure, say Y. | |
1604 | ||
1da177e4 | 1605 | config SHMEM |
6a108a14 | 1606 | bool "Use full shmem filesystem" if EXPERT |
1da177e4 LT |
1607 | default y |
1608 | depends on MMU | |
1609 | help | |
1610 | The shmem is an internal filesystem used to manage shared memory. | |
1611 | It is backed by swap and manages resource limits. It is also exported | |
1612 | to userspace as tmpfs if TMPFS is enabled. Disabling this | |
1613 | option replaces shmem and tmpfs with the much simpler ramfs code, | |
1614 | which may be appropriate on small systems without swap. | |
1615 | ||
ebf3f09c | 1616 | config AIO |
6a108a14 | 1617 | bool "Enable AIO support" if EXPERT |
ebf3f09c TP |
1618 | default y |
1619 | help | |
1620 | This option enables POSIX asynchronous I/O which may by used | |
657a5209 MF |
1621 | by some high performance threaded applications. Disabling |
1622 | this option saves about 7k. | |
1623 | ||
2b188cc1 JA |
1624 | config IO_URING |
1625 | bool "Enable IO uring support" if EXPERT | |
561fb04a | 1626 | select IO_WQ |
2b188cc1 JA |
1627 | default y |
1628 | help | |
1629 | This option enables support for the io_uring interface, enabling | |
1630 | applications to submit and complete IO through submission and | |
1631 | completion rings that are shared between the kernel and application. | |
1632 | ||
d3ac21ca JT |
1633 | config ADVISE_SYSCALLS |
1634 | bool "Enable madvise/fadvise syscalls" if EXPERT | |
1635 | default y | |
1636 | help | |
1637 | This option enables the madvise and fadvise syscalls, used by | |
1638 | applications to advise the kernel about their future memory or file | |
1639 | usage, improving performance. If building an embedded system where no | |
1640 | applications use these syscalls, you can disable this option to save | |
1641 | space. | |
1642 | ||
5a281062 AA |
1643 | config HAVE_ARCH_USERFAULTFD_WP |
1644 | bool | |
1645 | help | |
1646 | Arch has userfaultfd write protection support | |
1647 | ||
7677f7fd AR |
1648 | config HAVE_ARCH_USERFAULTFD_MINOR |
1649 | bool | |
1650 | help | |
1651 | Arch has userfaultfd minor fault support | |
1652 | ||
5b25b13a MD |
1653 | config MEMBARRIER |
1654 | bool "Enable membarrier() system call" if EXPERT | |
1655 | default y | |
1656 | help | |
1657 | Enable the membarrier() system call that allows issuing memory | |
1658 | barriers across all running threads, which can be used to distribute | |
1659 | the cost of user-space memory barriers asymmetrically by transforming | |
1660 | pairs of memory barriers into pairs consisting of membarrier() and a | |
1661 | compiler barrier. | |
1662 | ||
1663 | If unsure, say Y. | |
1664 | ||
d1b069f5 | 1665 | config KALLSYMS |
e8cf4e9c KK |
1666 | bool "Load all symbols for debugging/ksymoops" if EXPERT |
1667 | default y | |
1668 | help | |
1669 | Say Y here to let the kernel print out symbolic crash information and | |
1670 | symbolic stack backtraces. This increases the size of the kernel | |
1671 | somewhat, as all symbols have to be loaded into the kernel image. | |
d1b069f5 RD |
1672 | |
1673 | config KALLSYMS_ALL | |
1674 | bool "Include all symbols in kallsyms" | |
1675 | depends on DEBUG_KERNEL && KALLSYMS | |
1676 | help | |
e8cf4e9c KK |
1677 | Normally kallsyms only contains the symbols of functions for nicer |
1678 | OOPS messages and backtraces (i.e., symbols from the text and inittext | |
1679 | sections). This is sufficient for most cases. And only in very rare | |
1680 | cases (e.g., when a debugger is used) all symbols are required (e.g., | |
1681 | names of variables from the data sections, etc). | |
d1b069f5 | 1682 | |
e8cf4e9c KK |
1683 | This option makes sure that all symbols are loaded into the kernel |
1684 | image (i.e., symbols from all sections) in cost of increased kernel | |
1685 | size (depending on the kernel configuration, it may be 300KiB or | |
1686 | something like this). | |
d1b069f5 | 1687 | |
e8cf4e9c | 1688 | Say N unless you really need all symbols. |
d1b069f5 RD |
1689 | |
1690 | config KALLSYMS_ABSOLUTE_PERCPU | |
1691 | bool | |
1692 | depends on KALLSYMS | |
1693 | default X86_64 && SMP | |
1694 | ||
1695 | config KALLSYMS_BASE_RELATIVE | |
1696 | bool | |
1697 | depends on KALLSYMS | |
a687a533 | 1698 | default !IA64 |
d1b069f5 RD |
1699 | help |
1700 | Instead of emitting them as absolute values in the native word size, | |
1701 | emit the symbol references in the kallsyms table as 32-bit entries, | |
1702 | each containing a relative value in the range [base, base + U32_MAX] | |
1703 | or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either | |
1704 | an absolute value in the range [0, S32_MAX] or a relative value in the | |
1705 | range [base, base + S32_MAX], where base is the lowest relative symbol | |
1706 | address encountered in the image. | |
1707 | ||
1708 | On 64-bit builds, this reduces the size of the address table by 50%, | |
1709 | but more importantly, it results in entries whose values are build | |
1710 | time constants, and no relocation pass is required at runtime to fix | |
1711 | up the entries based on the runtime load address of the kernel. | |
1712 | ||
1713 | # end of the "standard kernel features (expert users)" menu | |
1714 | ||
1715 | # syscall, maps, verifier | |
fc611f47 | 1716 | |
d1b069f5 RD |
1717 | config USERFAULTFD |
1718 | bool "Enable userfaultfd() system call" | |
d1b069f5 RD |
1719 | depends on MMU |
1720 | help | |
1721 | Enable the userfaultfd() system call that allows to intercept and | |
1722 | handle page faults in userland. | |
1723 | ||
3ccfebed MD |
1724 | config ARCH_HAS_MEMBARRIER_CALLBACKS |
1725 | bool | |
1726 | ||
70216e18 MD |
1727 | config ARCH_HAS_MEMBARRIER_SYNC_CORE |
1728 | bool | |
1729 | ||
bfe3911a CW |
1730 | config KCMP |
1731 | bool "Enable kcmp() system call" if EXPERT | |
1732 | help | |
1733 | Enable the kernel resource comparison system call. It provides | |
1734 | user-space with the ability to compare two processes to see if they | |
1735 | share a common resource, such as a file descriptor or even virtual | |
1736 | memory space. | |
1737 | ||
1738 | If unsure, say N. | |
1739 | ||
d7822b1e MD |
1740 | config RSEQ |
1741 | bool "Enable rseq() system call" if EXPERT | |
1742 | default y | |
1743 | depends on HAVE_RSEQ | |
1744 | select MEMBARRIER | |
1745 | help | |
1746 | Enable the restartable sequences system call. It provides a | |
1747 | user-space cache for the current CPU number value, which | |
1748 | speeds up getting the current CPU number from user-space, | |
1749 | as well as an ABI to speed up user-space operations on | |
1750 | per-CPU data. | |
1751 | ||
1752 | If unsure, say Y. | |
1753 | ||
1754 | config DEBUG_RSEQ | |
1755 | default n | |
1756 | bool "Enabled debugging of rseq() system call" if EXPERT | |
1757 | depends on RSEQ && DEBUG_KERNEL | |
1758 | help | |
1759 | Enable extra debugging checks for the rseq system call. | |
1760 | ||
1761 | If unsure, say N. | |
1762 | ||
6befe5f6 RD |
1763 | config EMBEDDED |
1764 | bool "Embedded system" | |
1765 | select EXPERT | |
1766 | help | |
1767 | This option should be enabled if compiling the kernel for | |
1768 | an embedded system so certain expert options are available | |
1769 | for configuration. | |
1770 | ||
cdd6c482 | 1771 | config HAVE_PERF_EVENTS |
0793a61d | 1772 | bool |
018df72d MF |
1773 | help |
1774 | See tools/perf/design.txt for details. | |
0793a61d | 1775 | |
906010b2 PZ |
1776 | config PERF_USE_VMALLOC |
1777 | bool | |
1778 | help | |
1779 | See tools/perf/design.txt for details | |
1780 | ||
ad90a3de | 1781 | config PC104 |
424529fb | 1782 | bool "PC/104 support" if EXPERT |
ad90a3de WBG |
1783 | help |
1784 | Expose PC/104 form factor device drivers and options available for | |
1785 | selection and configuration. Enable this option if your target | |
1786 | machine has a PC/104 bus. | |
1787 | ||
57c0c15b | 1788 | menu "Kernel Performance Events And Counters" |
0793a61d | 1789 | |
cdd6c482 | 1790 | config PERF_EVENTS |
57c0c15b | 1791 | bool "Kernel performance events and counters" |
392d65a9 | 1792 | default y if PROFILING |
cdd6c482 | 1793 | depends on HAVE_PERF_EVENTS |
e360adbe | 1794 | select IRQ_WORK |
83fe27ea | 1795 | select SRCU |
0793a61d | 1796 | help |
57c0c15b IM |
1797 | Enable kernel support for various performance events provided |
1798 | by software and hardware. | |
0793a61d | 1799 | |
dd77038d | 1800 | Software events are supported either built-in or via the |
57c0c15b | 1801 | use of generic tracepoints. |
0793a61d | 1802 | |
57c0c15b IM |
1803 | Most modern CPUs support performance events via performance |
1804 | counter registers. These registers count the number of certain | |
0793a61d TG |
1805 | types of hw events: such as instructions executed, cachemisses |
1806 | suffered, or branches mis-predicted - without slowing down the | |
1807 | kernel or applications. These registers can also trigger interrupts | |
1808 | when a threshold number of events have passed - and can thus be | |
1809 | used to profile the code that runs on that CPU. | |
1810 | ||
57c0c15b | 1811 | The Linux Performance Event subsystem provides an abstraction of |
dd77038d | 1812 | these software and hardware event capabilities, available via a |
57c0c15b | 1813 | system call and used by the "perf" utility in tools/perf/. It |
0793a61d TG |
1814 | provides per task and per CPU counters, and it provides event |
1815 | capabilities on top of those. | |
1816 | ||
1817 | Say Y if unsure. | |
1818 | ||
906010b2 PZ |
1819 | config DEBUG_PERF_USE_VMALLOC |
1820 | default n | |
1821 | bool "Debug: use vmalloc to back perf mmap() buffers" | |
cb307113 | 1822 | depends on PERF_EVENTS && DEBUG_KERNEL && !PPC |
906010b2 PZ |
1823 | select PERF_USE_VMALLOC |
1824 | help | |
e8cf4e9c | 1825 | Use vmalloc memory to back perf mmap() buffers. |
906010b2 | 1826 | |
e8cf4e9c KK |
1827 | Mostly useful for debugging the vmalloc code on platforms |
1828 | that don't require it. | |
906010b2 | 1829 | |
e8cf4e9c | 1830 | Say N if unsure. |
906010b2 | 1831 | |
0793a61d TG |
1832 | endmenu |
1833 | ||
f8891e5e CL |
1834 | config VM_EVENT_COUNTERS |
1835 | default y | |
6a108a14 | 1836 | bool "Enable VM event counters for /proc/vmstat" if EXPERT |
f8891e5e | 1837 | help |
2aea4fb6 PJ |
1838 | VM event counters are needed for event counts to be shown. |
1839 | This option allows the disabling of the VM event counters | |
6a108a14 | 1840 | on EXPERT systems. /proc/vmstat will only show page counts |
2aea4fb6 | 1841 | if VM event counters are disabled. |
f8891e5e | 1842 | |
41ecc55b CL |
1843 | config SLUB_DEBUG |
1844 | default y | |
6a108a14 | 1845 | bool "Enable SLUB debugging support" if EXPERT |
f6acb635 | 1846 | depends on SLUB && SYSFS |
41ecc55b CL |
1847 | help |
1848 | SLUB has extensive debug support features. Disabling these can | |
1849 | result in significant savings in code size. This also disables | |
1850 | SLUB sysfs support. /sys/slab will not exist and there will be | |
1851 | no support for cache validation etc. | |
1852 | ||
b943c460 RD |
1853 | config COMPAT_BRK |
1854 | bool "Disable heap randomization" | |
1855 | default y | |
1856 | help | |
1857 | Randomizing heap placement makes heap exploits harder, but it | |
1858 | also breaks ancient binaries (including anything libc5 based). | |
1859 | This option changes the bootup default to heap randomization | |
692105b8 | 1860 | disabled, and can be overridden at runtime by setting |
b943c460 RD |
1861 | /proc/sys/kernel/randomize_va_space to 2. |
1862 | ||
1863 | On non-ancient distros (post-2000 ones) N is usually a safe choice. | |
1864 | ||
81819f0f CL |
1865 | choice |
1866 | prompt "Choose SLAB allocator" | |
a0acd820 | 1867 | default SLUB |
81819f0f CL |
1868 | help |
1869 | This option allows to select a slab allocator. | |
1870 | ||
1871 | config SLAB | |
1872 | bool "SLAB" | |
04385fc5 | 1873 | select HAVE_HARDENED_USERCOPY_ALLOCATOR |
81819f0f CL |
1874 | help |
1875 | The regular slab allocator that is established and known to work | |
34013886 | 1876 | well in all environments. It organizes cache hot objects in |
02f56210 | 1877 | per cpu and per node queues. |
81819f0f CL |
1878 | |
1879 | config SLUB | |
81819f0f | 1880 | bool "SLUB (Unqueued Allocator)" |
ed18adc1 | 1881 | select HAVE_HARDENED_USERCOPY_ALLOCATOR |
81819f0f CL |
1882 | help |
1883 | SLUB is a slab allocator that minimizes cache line usage | |
1884 | instead of managing queues of cached objects (SLAB approach). | |
1885 | Per cpu caching is realized using slabs of objects instead | |
1886 | of queues of objects. SLUB can use memory efficiently | |
02f56210 SA |
1887 | and has enhanced diagnostics. SLUB is the default choice for |
1888 | a slab allocator. | |
81819f0f CL |
1889 | |
1890 | config SLOB | |
6a108a14 | 1891 | depends on EXPERT |
81819f0f CL |
1892 | bool "SLOB (Simple Allocator)" |
1893 | help | |
37291458 MM |
1894 | SLOB replaces the stock allocator with a drastically simpler |
1895 | allocator. SLOB is generally more space efficient but | |
1896 | does not perform as well on large systems. | |
81819f0f CL |
1897 | |
1898 | endchoice | |
1899 | ||
7660a6fd KC |
1900 | config SLAB_MERGE_DEFAULT |
1901 | bool "Allow slab caches to be merged" | |
1902 | default y | |
1903 | help | |
1904 | For reduced kernel memory fragmentation, slab caches can be | |
1905 | merged when they share the same size and other characteristics. | |
1906 | This carries a risk of kernel heap overflows being able to | |
1907 | overwrite objects from merged caches (and more easily control | |
1908 | cache layout), which makes such heap attacks easier to exploit | |
1909 | by attackers. By keeping caches unmerged, these kinds of exploits | |
1910 | can usually only damage objects in the same cache. To disable | |
1911 | merging at runtime, "slab_nomerge" can be passed on the kernel | |
1912 | command line. | |
1913 | ||
c7ce4f60 | 1914 | config SLAB_FREELIST_RANDOM |
3404be67 | 1915 | bool "Randomize slab freelist" |
210e7a43 | 1916 | depends on SLAB || SLUB |
c7ce4f60 | 1917 | help |
210e7a43 | 1918 | Randomizes the freelist order used on creating new pages. This |
c7ce4f60 TG |
1919 | security feature reduces the predictability of the kernel slab |
1920 | allocator against heap overflows. | |
1921 | ||
2482ddec KC |
1922 | config SLAB_FREELIST_HARDENED |
1923 | bool "Harden slab freelist metadata" | |
3404be67 | 1924 | depends on SLAB || SLUB |
2482ddec KC |
1925 | help |
1926 | Many kernel heap attacks try to target slab cache metadata and | |
1927 | other infrastructure. This options makes minor performance | |
92bae787 | 1928 | sacrifices to harden the kernel slab allocator against common |
3404be67 KC |
1929 | freelist exploit methods. Some slab implementations have more |
1930 | sanity-checking than others. This option is most effective with | |
1931 | CONFIG_SLUB. | |
2482ddec | 1932 | |
e900a918 DW |
1933 | config SHUFFLE_PAGE_ALLOCATOR |
1934 | bool "Page allocator randomization" | |
1935 | default SLAB_FREELIST_RANDOM && ACPI_NUMA | |
1936 | help | |
1937 | Randomization of the page allocator improves the average | |
1938 | utilization of a direct-mapped memory-side-cache. See section | |
1939 | 5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI | |
1940 | 6.2a specification for an example of how a platform advertises | |
1941 | the presence of a memory-side-cache. There are also incidental | |
1942 | security benefits as it reduces the predictability of page | |
1943 | allocations to compliment SLAB_FREELIST_RANDOM, but the | |
1944 | default granularity of shuffling on the "MAX_ORDER - 1" i.e, | |
1945 | 10th order of pages is selected based on cache utilization | |
1946 | benefits on x86. | |
1947 | ||
1948 | While the randomization improves cache utilization it may | |
1949 | negatively impact workloads on platforms without a cache. For | |
1950 | this reason, by default, the randomization is enabled only | |
1951 | after runtime detection of a direct-mapped memory-side-cache. | |
1952 | Otherwise, the randomization may be force enabled with the | |
1953 | 'page_alloc.shuffle' kernel command line parameter. | |
1954 | ||
1955 | Say Y if unsure. | |
1956 | ||
345c905d JK |
1957 | config SLUB_CPU_PARTIAL |
1958 | default y | |
b39ffbf8 | 1959 | depends on SLUB && SMP |
345c905d JK |
1960 | bool "SLUB per cpu partial cache" |
1961 | help | |
92bae787 | 1962 | Per cpu partial caches accelerate objects allocation and freeing |
345c905d JK |
1963 | that is local to a processor at the price of more indeterminism |
1964 | in the latency of the free. On overflow these caches will be cleared | |
1965 | which requires the taking of locks that may cause latency spikes. | |
1966 | Typically one would choose no for a realtime system. | |
1967 | ||
ea637639 JZ |
1968 | config MMAP_ALLOW_UNINITIALIZED |
1969 | bool "Allow mmapped anonymous memory to be uninitialized" | |
6a108a14 | 1970 | depends on EXPERT && !MMU |
ea637639 JZ |
1971 | default n |
1972 | help | |
1973 | Normally, and according to the Linux spec, anonymous memory obtained | |
3903bf94 | 1974 | from mmap() has its contents cleared before it is passed to |
ea637639 JZ |
1975 | userspace. Enabling this config option allows you to request that |
1976 | mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus | |
1977 | providing a huge performance boost. If this option is not enabled, | |
1978 | then the flag will be ignored. | |
1979 | ||
1980 | This is taken advantage of by uClibc's malloc(), and also by | |
1981 | ELF-FDPIC binfmt's brk and stack allocator. | |
1982 | ||
1983 | Because of the obvious security issues, this option should only be | |
1984 | enabled on embedded devices where you control what is run in | |
1985 | userspace. Since that isn't generally a problem on no-MMU systems, | |
1986 | it is normally safe to say Y here. | |
1987 | ||
dd19d293 | 1988 | See Documentation/admin-guide/mm/nommu-mmap.rst for more information. |
ea637639 | 1989 | |
091f6e26 DH |
1990 | config SYSTEM_DATA_VERIFICATION |
1991 | def_bool n | |
1992 | select SYSTEM_TRUSTED_KEYRING | |
1993 | select KEYS | |
1994 | select CRYPTO | |
d43de6c7 | 1995 | select CRYPTO_RSA |
091f6e26 DH |
1996 | select ASYMMETRIC_KEY_TYPE |
1997 | select ASYMMETRIC_PUBLIC_KEY_SUBTYPE | |
091f6e26 DH |
1998 | select ASN1 |
1999 | select OID_REGISTRY | |
2000 | select X509_CERTIFICATE_PARSER | |
2001 | select PKCS7_MESSAGE_PARSER | |
82c04ff8 | 2002 | help |
091f6e26 DH |
2003 | Provide PKCS#7 message verification using the contents of the system |
2004 | trusted keyring to provide public keys. This then can be used for | |
2005 | module verification, kexec image verification and firmware blob | |
2006 | verification. | |
82c04ff8 | 2007 | |
125e5645 | 2008 | config PROFILING |
b309a294 | 2009 | bool "Profiling support" |
125e5645 MD |
2010 | help |
2011 | Say Y here to enable the extended profiling support mechanisms used | |
f8408264 | 2012 | by profilers. |
125e5645 | 2013 | |
5f87f112 IM |
2014 | # |
2015 | # Place an empty function call at each tracepoint site. Can be | |
2016 | # dynamically changed for a probe function. | |
2017 | # | |
97e1c18e | 2018 | config TRACEPOINTS |
5f87f112 | 2019 | bool |
97e1c18e | 2020 | |
1da177e4 LT |
2021 | endmenu # General setup |
2022 | ||
1572497c CH |
2023 | source "arch/Kconfig" |
2024 | ||
ae81f9e3 | 2025 | config RT_MUTEXES |
6341e62b | 2026 | bool |
ae81f9e3 | 2027 | |
1da177e4 LT |
2028 | config BASE_SMALL |
2029 | int | |
2030 | default 0 if BASE_FULL | |
2031 | default 1 if !BASE_FULL | |
2032 | ||
c8424e77 TJB |
2033 | config MODULE_SIG_FORMAT |
2034 | def_bool n | |
2035 | select SYSTEM_DATA_VERIFICATION | |
2036 | ||
66da5733 | 2037 | menuconfig MODULES |
1da177e4 | 2038 | bool "Enable loadable module support" |
6dd85ff1 | 2039 | modules |
1da177e4 LT |
2040 | help |
2041 | Kernel modules are small pieces of compiled code which can | |
2042 | be inserted in the running kernel, rather than being | |
2043 | permanently built into the kernel. You use the "modprobe" | |
2044 | tool to add (and sometimes remove) them. If you say Y here, | |
2045 | many parts of the kernel can be built as modules (by | |
2046 | answering M instead of Y where indicated): this is most | |
2047 | useful for infrequently used options which are not required | |
2048 | for booting. For more information, see the man pages for | |
2049 | modprobe, lsmod, modinfo, insmod and rmmod. | |
2050 | ||
2051 | If you say Y here, you will need to run "make | |
2052 | modules_install" to put the modules under /lib/modules/ | |
2053 | where modprobe can find them (you may need to be root to do | |
2054 | this). | |
2055 | ||
2056 | If unsure, say Y. | |
2057 | ||
0b0de144 RD |
2058 | if MODULES |
2059 | ||
826e4506 LT |
2060 | config MODULE_FORCE_LOAD |
2061 | bool "Forced module loading" | |
826e4506 LT |
2062 | default n |
2063 | help | |
91e37a79 RR |
2064 | Allow loading of modules without version information (ie. modprobe |
2065 | --force). Forced module loading sets the 'F' (forced) taint flag and | |
2066 | is usually a really bad idea. | |
826e4506 | 2067 | |
1da177e4 LT |
2068 | config MODULE_UNLOAD |
2069 | bool "Module unloading" | |
1da177e4 LT |
2070 | help |
2071 | Without this option you will not be able to unload any | |
2072 | modules (note that some modules may not be unloadable | |
f7f5b675 DV |
2073 | anyway), which makes your kernel smaller, faster |
2074 | and simpler. If unsure, say Y. | |
1da177e4 LT |
2075 | |
2076 | config MODULE_FORCE_UNLOAD | |
2077 | bool "Forced module unloading" | |
19c92399 | 2078 | depends on MODULE_UNLOAD |
1da177e4 LT |
2079 | help |
2080 | This option allows you to force a module to unload, even if the | |
2081 | kernel believes it is unsafe: the kernel will remove the module | |
2082 | without waiting for anyone to stop using it (using the -f option to | |
2083 | rmmod). This is mainly for kernel developers and desperate users. | |
2084 | If unsure, say N. | |
2085 | ||
1da177e4 | 2086 | config MODVERSIONS |
0d541643 | 2087 | bool "Module versioning support" |
1da177e4 LT |
2088 | help |
2089 | Usually, you have to use modules compiled with your kernel. | |
2090 | Saying Y here makes it sometimes possible to use modules | |
2091 | compiled for different kernels, by adding enough information | |
2092 | to the modules to (hopefully) spot any changes which would | |
2093 | make them incompatible with the kernel you are running. If | |
2094 | unsure, say N. | |
2095 | ||
2ff2b7ec MY |
2096 | config ASM_MODVERSIONS |
2097 | bool | |
2098 | default HAVE_ASM_MODVERSIONS && MODVERSIONS | |
2099 | help | |
2100 | This enables module versioning for exported symbols also from | |
2101 | assembly. This can be enabled only when the target architecture | |
2102 | supports it. | |
2103 | ||
56067812 AB |
2104 | config MODULE_REL_CRCS |
2105 | bool | |
2106 | depends on MODVERSIONS | |
2107 | ||
1da177e4 LT |
2108 | config MODULE_SRCVERSION_ALL |
2109 | bool "Source checksum for all modules" | |
1da177e4 LT |
2110 | help |
2111 | Modules which contain a MODULE_VERSION get an extra "srcversion" | |
2112 | field inserted into their modinfo section, which contains a | |
2113 | sum of the source files which made it. This helps maintainers | |
2114 | see exactly which source was used to build a module (since | |
2115 | others sometimes change the module source without updating | |
2116 | the version). With this option, such a "srcversion" field | |
2117 | will be created for all modules. If unsure, say N. | |
2118 | ||
106a4ee2 RR |
2119 | config MODULE_SIG |
2120 | bool "Module signature verification" | |
c8424e77 | 2121 | select MODULE_SIG_FORMAT |
106a4ee2 RR |
2122 | help |
2123 | Check modules for valid signatures upon load: the signature | |
2124 | is simply appended to the module. For more information see | |
cbdc8217 | 2125 | <file:Documentation/admin-guide/module-signing.rst>. |
106a4ee2 | 2126 | |
228c37ff DH |
2127 | Note that this option adds the OpenSSL development packages as a |
2128 | kernel build dependency so that the signing tool can use its crypto | |
2129 | library. | |
2130 | ||
49fcf732 DH |
2131 | You should enable this option if you wish to use either |
2132 | CONFIG_SECURITY_LOCKDOWN_LSM or lockdown functionality imposed via | |
2133 | another LSM - otherwise unsigned modules will be loadable regardless | |
2134 | of the lockdown policy. | |
2135 | ||
ea0b6dcf DH |
2136 | !!!WARNING!!! If you enable this option, you MUST make sure that the |
2137 | module DOES NOT get stripped after being signed. This includes the | |
2138 | debuginfo strip done by some packagers (such as rpmbuild) and | |
2139 | inclusion into an initramfs that wants the module size reduced. | |
2140 | ||
106a4ee2 RR |
2141 | config MODULE_SIG_FORCE |
2142 | bool "Require modules to be validly signed" | |
2143 | depends on MODULE_SIG | |
2144 | help | |
2145 | Reject unsigned modules or signed modules for which we don't have a | |
2146 | key. Without this, such modules will simply taint the kernel. | |
ea0b6dcf | 2147 | |
d9d8d7ed MM |
2148 | config MODULE_SIG_ALL |
2149 | bool "Automatically sign all modules" | |
2150 | default y | |
0165f4ca | 2151 | depends on MODULE_SIG || IMA_APPRAISE_MODSIG |
d9d8d7ed MM |
2152 | help |
2153 | Sign all modules during make modules_install. Without this option, | |
2154 | modules must be signed manually, using the scripts/sign-file tool. | |
2155 | ||
2156 | comment "Do not forget to sign required modules with scripts/sign-file" | |
2157 | depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL | |
2158 | ||
ea0b6dcf DH |
2159 | choice |
2160 | prompt "Which hash algorithm should modules be signed with?" | |
0165f4ca | 2161 | depends on MODULE_SIG || IMA_APPRAISE_MODSIG |
ea0b6dcf DH |
2162 | help |
2163 | This determines which sort of hashing algorithm will be used during | |
2164 | signature generation. This algorithm _must_ be built into the kernel | |
2165 | directly so that signature verification can take place. It is not | |
2166 | possible to load a signed module containing the algorithm to check | |
2167 | the signature on that module. | |
2168 | ||
2169 | config MODULE_SIG_SHA1 | |
2170 | bool "Sign modules with SHA-1" | |
2171 | select CRYPTO_SHA1 | |
2172 | ||
2173 | config MODULE_SIG_SHA224 | |
2174 | bool "Sign modules with SHA-224" | |
2175 | select CRYPTO_SHA256 | |
2176 | ||
2177 | config MODULE_SIG_SHA256 | |
2178 | bool "Sign modules with SHA-256" | |
2179 | select CRYPTO_SHA256 | |
2180 | ||
2181 | config MODULE_SIG_SHA384 | |
2182 | bool "Sign modules with SHA-384" | |
2183 | select CRYPTO_SHA512 | |
2184 | ||
2185 | config MODULE_SIG_SHA512 | |
2186 | bool "Sign modules with SHA-512" | |
2187 | select CRYPTO_SHA512 | |
2188 | ||
2189 | endchoice | |
2190 | ||
22753674 MM |
2191 | config MODULE_SIG_HASH |
2192 | string | |
0165f4ca | 2193 | depends on MODULE_SIG || IMA_APPRAISE_MODSIG |
22753674 MM |
2194 | default "sha1" if MODULE_SIG_SHA1 |
2195 | default "sha224" if MODULE_SIG_SHA224 | |
2196 | default "sha256" if MODULE_SIG_SHA256 | |
2197 | default "sha384" if MODULE_SIG_SHA384 | |
2198 | default "sha512" if MODULE_SIG_SHA512 | |
2199 | ||
d4bbe942 MY |
2200 | choice |
2201 | prompt "Module compression mode" | |
beb50df3 | 2202 | help |
d4bbe942 MY |
2203 | This option allows you to choose the algorithm which will be used to |
2204 | compress modules when 'make modules_install' is run. (or, you can | |
2205 | choose to not compress modules at all.) | |
beb50df3 | 2206 | |
d4bbe942 MY |
2207 | External modules will also be compressed in the same way during the |
2208 | installation. | |
beb50df3 | 2209 | |
d4bbe942 MY |
2210 | For modules inside an initrd or initramfs, it's more efficient to |
2211 | compress the whole initrd or initramfs instead. | |
beb50df3 | 2212 | |
d4bbe942 | 2213 | This is fully compatible with signed modules. |
beb50df3 | 2214 | |
d4bbe942 MY |
2215 | Please note that the tool used to load modules needs to support the |
2216 | corresponding algorithm. module-init-tools MAY support gzip, and kmod | |
c3d7ef37 | 2217 | MAY support gzip, xz and zstd. |
beb50df3 | 2218 | |
d4bbe942 MY |
2219 | Your build system needs to provide the appropriate compression tool |
2220 | to compress the modules. | |
b6c09b51 | 2221 | |
d4bbe942 | 2222 | If in doubt, select 'None'. |
beb50df3 | 2223 | |
d4bbe942 MY |
2224 | config MODULE_COMPRESS_NONE |
2225 | bool "None" | |
beb50df3 | 2226 | help |
d4bbe942 MY |
2227 | Do not compress modules. The installed modules are suffixed |
2228 | with .ko. | |
beb50df3 BJ |
2229 | |
2230 | config MODULE_COMPRESS_GZIP | |
2231 | bool "GZIP" | |
d4bbe942 MY |
2232 | help |
2233 | Compress modules with GZIP. The installed modules are suffixed | |
2234 | with .ko.gz. | |
beb50df3 BJ |
2235 | |
2236 | config MODULE_COMPRESS_XZ | |
2237 | bool "XZ" | |
d4bbe942 MY |
2238 | help |
2239 | Compress modules with XZ. The installed modules are suffixed | |
2240 | with .ko.xz. | |
beb50df3 | 2241 | |
c3d7ef37 PG |
2242 | config MODULE_COMPRESS_ZSTD |
2243 | bool "ZSTD" | |
2244 | help | |
2245 | Compress modules with ZSTD. The installed modules are suffixed | |
2246 | with .ko.zst. | |
beb50df3 BJ |
2247 | |
2248 | endchoice | |
2249 | ||
3d52ec5e MM |
2250 | config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS |
2251 | bool "Allow loading of modules with missing namespace imports" | |
2252 | help | |
2253 | Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in | |
2254 | a namespace. A module that makes use of a symbol exported with such a | |
2255 | namespace is required to import the namespace via MODULE_IMPORT_NS(). | |
2256 | There is no technical reason to enforce correct namespace imports, | |
2257 | but it creates consistency between symbols defining namespaces and | |
2258 | users importing namespaces they make use of. This option relaxes this | |
2259 | requirement and lifts the enforcement when loading a module. | |
2260 | ||
2261 | If unsure, say N. | |
2262 | ||
17652f42 RV |
2263 | config MODPROBE_PATH |
2264 | string "Path to modprobe binary" | |
2265 | default "/sbin/modprobe" | |
2266 | help | |
2267 | When kernel code requests a module, it does so by calling | |
2268 | the "modprobe" userspace utility. This option allows you to | |
2269 | set the path where that binary is found. This can be changed | |
2270 | at runtime via the sysctl file | |
2271 | /proc/sys/kernel/modprobe. Setting this to the empty string | |
2272 | removes the kernel's ability to request modules (but | |
2273 | userspace can still load modules explicitly). | |
2274 | ||
dbacb0ef | 2275 | config TRIM_UNUSED_KSYMS |
a555bdd0 LT |
2276 | bool "Trim unused exported kernel symbols" if EXPERT |
2277 | depends on !COMPILE_TEST | |
dbacb0ef NP |
2278 | help |
2279 | The kernel and some modules make many symbols available for | |
2280 | other modules to use via EXPORT_SYMBOL() and variants. Depending | |
2281 | on the set of modules being selected in your kernel configuration, | |
2282 | many of those exported symbols might never be used. | |
2283 | ||
2284 | This option allows for unused exported symbols to be dropped from | |
2285 | the build. In turn, this provides the compiler more opportunities | |
2286 | (especially when using LTO) for optimizing the code and reducing | |
2287 | binary size. This might have some security advantages as well. | |
2288 | ||
f1cb637e | 2289 | If unsure, or if you need to build out-of-tree modules, say N. |
dbacb0ef | 2290 | |
1518c633 QP |
2291 | config UNUSED_KSYMS_WHITELIST |
2292 | string "Whitelist of symbols to keep in ksymtab" | |
2293 | depends on TRIM_UNUSED_KSYMS | |
2294 | help | |
2295 | By default, all unused exported symbols will be un-exported from the | |
2296 | build when TRIM_UNUSED_KSYMS is selected. | |
2297 | ||
2298 | UNUSED_KSYMS_WHITELIST allows to whitelist symbols that must be kept | |
2299 | exported at all times, even in absence of in-tree users. The value to | |
2300 | set here is the path to a text file containing the list of symbols, | |
2301 | one per line. The path can be absolute, or relative to the kernel | |
2302 | source tree. | |
2303 | ||
0b0de144 RD |
2304 | endif # MODULES |
2305 | ||
6c9692e2 PZ |
2306 | config MODULES_TREE_LOOKUP |
2307 | def_bool y | |
cf68fffb | 2308 | depends on PERF_EVENTS || TRACING || CFI_CLANG |
6c9692e2 | 2309 | |
98a79d6a RR |
2310 | config INIT_ALL_POSSIBLE |
2311 | bool | |
2312 | help | |
5f054e31 RR |
2313 | Back when each arch used to define their own cpu_online_mask and |
2314 | cpu_possible_mask, some of them chose to initialize cpu_possible_mask | |
98a79d6a RR |
2315 | with all 1s, and others with all 0s. When they were centralised, |
2316 | it was better to provide this option than to break all the archs | |
692105b8 | 2317 | and have several arch maintainers pursuing me down dark alleys. |
98a79d6a | 2318 | |
3a65dfe8 | 2319 | source "block/Kconfig" |
e98c3202 AK |
2320 | |
2321 | config PREEMPT_NOTIFIERS | |
2322 | bool | |
e260be67 | 2323 | |
16295bec SK |
2324 | config PADATA |
2325 | depends on SMP | |
2326 | bool | |
2327 | ||
4520c6a4 DH |
2328 | config ASN1 |
2329 | tristate | |
2330 | help | |
2331 | Build a simple ASN.1 grammar compiler that produces a bytecode output | |
2332 | that can be interpreted by the ASN.1 stream decoder and used to | |
2333 | inform it as to what tags are to be expected in a stream and what | |
2334 | functions to call on what tags. | |
2335 | ||
6beb0009 | 2336 | source "kernel/Kconfig.locks" |
e61938a9 | 2337 | |
0ebeea8c DB |
2338 | config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE |
2339 | bool | |
2340 | ||
e61938a9 MD |
2341 | config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE |
2342 | bool | |
1bd21c6c DB |
2343 | |
2344 | # It may be useful for an architecture to override the definitions of the | |
7303e30e DB |
2345 | # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h> |
2346 | # and the COMPAT_ variants in <linux/compat.h>, in particular to use a | |
2347 | # different calling convention for syscalls. They can also override the | |
2348 | # macros for not-implemented syscalls in kernel/sys_ni.c and | |
2349 | # kernel/time/posix-stubs.c. All these overrides need to be available in | |
2350 | # <asm/syscall_wrapper.h>. | |
1bd21c6c DB |
2351 | config ARCH_HAS_SYSCALL_WRAPPER |
2352 | def_bool n |