Commit | Line | Data |
---|---|---|
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 | ||
51c2ee6d ND |
86 | config CC_HAS_NO_PROFILE_FN_ATTR |
87 | def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror) | |
88 | ||
b99b87f7 PO |
89 | config CONSTRUCTORS |
90 | bool | |
b99b87f7 | 91 | |
e360adbe PZ |
92 | config IRQ_WORK |
93 | bool | |
e360adbe | 94 | |
10916706 | 95 | config BUILDTIME_TABLE_SORT |
1dbdc6f1 DD |
96 | bool |
97 | ||
c65eacbe AL |
98 | config THREAD_INFO_IN_TASK |
99 | bool | |
100 | help | |
101 | Select this to move thread_info off the stack into task_struct. To | |
102 | make this work, an arch will need to remove all thread_info fields | |
103 | except flags and fix any runtime bugs. | |
104 | ||
c6c314a6 AL |
105 | One subtle change that will be needed is to use try_get_task_stack() |
106 | and put_task_stack() in save_thread_stack_tsk() and get_wchan(). | |
107 | ||
ff0cfc66 | 108 | menu "General setup" |
1da177e4 | 109 | |
1da177e4 LT |
110 | config BROKEN |
111 | bool | |
1da177e4 LT |
112 | |
113 | config BROKEN_ON_SMP | |
114 | bool | |
115 | depends on BROKEN || !SMP | |
116 | default y | |
117 | ||
1da177e4 LT |
118 | config INIT_ENV_ARG_LIMIT |
119 | int | |
dd673bca AB |
120 | default 32 if !UML |
121 | default 128 if UML | |
1da177e4 | 122 | help |
34ad92c2 RD |
123 | Maximum of each of the number of arguments and environment |
124 | variables passed to init from the kernel command line. | |
1da177e4 | 125 | |
4bb16672 JS |
126 | config COMPILE_TEST |
127 | bool "Compile also drivers which will not load" | |
ea29b20a | 128 | depends on HAS_IOMEM |
4bb16672 JS |
129 | help |
130 | Some drivers can be compiled on a different platform than they are | |
131 | intended to be run on. Despite they cannot be loaded there (or even | |
132 | when they load they cannot be used due to missing HW support), | |
133 | developers still, opposing to distributors, might want to build such | |
134 | drivers to compile-test them. | |
135 | ||
136 | If you are a developer and want to build everything available, say Y | |
137 | here. If you are a user/distributor, say N here to exclude useless | |
138 | drivers to be distributed. | |
139 | ||
d6fc9fcb MY |
140 | config UAPI_HEADER_TEST |
141 | bool "Compile test UAPI headers" | |
fcbb8461 | 142 | depends on HEADERS_INSTALL && CC_CAN_LINK |
d6fc9fcb MY |
143 | help |
144 | Compile test headers exported to user-space to ensure they are | |
145 | self-contained, i.e. compilable as standalone units. | |
146 | ||
147 | If you are a developer or tester and want to ensure the exported | |
148 | headers are self-contained, say Y here. Otherwise, choose N. | |
149 | ||
1da177e4 LT |
150 | config LOCALVERSION |
151 | string "Local version - append to kernel release" | |
152 | help | |
153 | Append an extra string to the end of your kernel version. | |
154 | This will show up when you type uname, for example. | |
155 | The string you set here will be appended after the contents of | |
156 | any files with a filename matching localversion* in your | |
157 | object and source tree, in that order. Your total string can | |
158 | be a maximum of 64 characters. | |
159 | ||
aaebf433 RA |
160 | config LOCALVERSION_AUTO |
161 | bool "Automatically append version information to the version string" | |
162 | default y | |
ac3339ba | 163 | depends on !COMPILE_TEST |
aaebf433 RA |
164 | help |
165 | This will try to automatically determine if the current tree is a | |
6e5a5420 RD |
166 | release tree by looking for git tags that belong to the current |
167 | top of tree revision. | |
aaebf433 RA |
168 | |
169 | A string of the format -gxxxxxxxx will be added to the localversion | |
6e5a5420 | 170 | if a git-based tree is found. The string generated by this will be |
aaebf433 | 171 | appended after any matching localversion* files, and after the value |
6e5a5420 | 172 | set in CONFIG_LOCALVERSION. |
aaebf433 | 173 | |
6e5a5420 RD |
174 | (The actual string used here is the first eight characters produced |
175 | by running the command: | |
176 | ||
177 | $ git rev-parse --verify HEAD | |
178 | ||
179 | which is done within the script "scripts/setlocalversion".) | |
aaebf433 | 180 | |
9afb719e | 181 | config BUILD_SALT |
e8cf4e9c KK |
182 | string "Build ID Salt" |
183 | default "" | |
184 | help | |
185 | The build ID is used to link binaries and their debug info. Setting | |
186 | this option will use the value in the calculation of the build id. | |
187 | This is mostly useful for distributions which want to ensure the | |
188 | build is unique between builds. It's safe to leave the default. | |
9afb719e | 189 | |
2e9f3bdd PA |
190 | config HAVE_KERNEL_GZIP |
191 | bool | |
192 | ||
193 | config HAVE_KERNEL_BZIP2 | |
194 | bool | |
195 | ||
196 | config HAVE_KERNEL_LZMA | |
197 | bool | |
198 | ||
3ebe1243 LC |
199 | config HAVE_KERNEL_XZ |
200 | bool | |
201 | ||
7dd65feb AT |
202 | config HAVE_KERNEL_LZO |
203 | bool | |
204 | ||
e76e1fdf KL |
205 | config HAVE_KERNEL_LZ4 |
206 | bool | |
207 | ||
48f7ddf7 NT |
208 | config HAVE_KERNEL_ZSTD |
209 | bool | |
210 | ||
f16466af VG |
211 | config HAVE_KERNEL_UNCOMPRESSED |
212 | bool | |
213 | ||
30d65dbf | 214 | choice |
2e9f3bdd PA |
215 | prompt "Kernel compression mode" |
216 | default KERNEL_GZIP | |
48f7ddf7 | 217 | 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 | 218 | help |
30d65dbf AK |
219 | The linux kernel is a kind of self-extracting executable. |
220 | Several compression algorithms are available, which differ | |
221 | in efficiency, compression and decompression speed. | |
222 | Compression speed is only relevant when building a kernel. | |
223 | Decompression speed is relevant at each boot. | |
224 | ||
225 | If you have any problems with bzip2 or lzma compressed | |
226 | kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older | |
227 | version of this functionality (bzip2 only), for 2.4, was | |
228 | supplied by Christian Ludwig) | |
229 | ||
230 | High compression options are mostly useful for users, who | |
231 | are low on disk space (embedded systems), but for whom ram | |
232 | size matters less. | |
233 | ||
234 | If in doubt, select 'gzip' | |
235 | ||
236 | config KERNEL_GZIP | |
2e9f3bdd PA |
237 | bool "Gzip" |
238 | depends on HAVE_KERNEL_GZIP | |
239 | help | |
7dd65feb AT |
240 | The old and tried gzip compression. It provides a good balance |
241 | between compression ratio and decompression speed. | |
30d65dbf AK |
242 | |
243 | config KERNEL_BZIP2 | |
244 | bool "Bzip2" | |
2e9f3bdd | 245 | depends on HAVE_KERNEL_BZIP2 |
30d65dbf AK |
246 | help |
247 | Its compression ratio and speed is intermediate. | |
0a4dd35c | 248 | Decompression speed is slowest among the choices. The kernel |
2e9f3bdd PA |
249 | size is about 10% smaller with bzip2, in comparison to gzip. |
250 | Bzip2 uses a large amount of memory. For modern kernels you | |
251 | will need at least 8MB RAM or more for booting. | |
30d65dbf AK |
252 | |
253 | config KERNEL_LZMA | |
2e9f3bdd PA |
254 | bool "LZMA" |
255 | depends on HAVE_KERNEL_LZMA | |
256 | help | |
0a4dd35c RD |
257 | This compression algorithm's ratio is best. Decompression speed |
258 | is between gzip and bzip2. Compression is slowest. | |
259 | The kernel size is about 33% smaller with LZMA in comparison to gzip. | |
30d65dbf | 260 | |
3ebe1243 LC |
261 | config KERNEL_XZ |
262 | bool "XZ" | |
263 | depends on HAVE_KERNEL_XZ | |
264 | help | |
265 | XZ uses the LZMA2 algorithm and instruction set specific | |
266 | BCJ filters which can improve compression ratio of executable | |
267 | code. The size of the kernel is about 30% smaller with XZ in | |
268 | comparison to gzip. On architectures for which there is a BCJ | |
269 | filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ | |
270 | will create a few percent smaller kernel than plain LZMA. | |
271 | ||
272 | The speed is about the same as with LZMA: The decompression | |
273 | speed of XZ is better than that of bzip2 but worse than gzip | |
274 | and LZO. Compression is slow. | |
275 | ||
7dd65feb AT |
276 | config KERNEL_LZO |
277 | bool "LZO" | |
278 | depends on HAVE_KERNEL_LZO | |
279 | help | |
0a4dd35c | 280 | Its compression ratio is the poorest among the choices. The kernel |
681b3049 | 281 | size is about 10% bigger than gzip; however its speed |
7dd65feb AT |
282 | (both compression and decompression) is the fastest. |
283 | ||
e76e1fdf KL |
284 | config KERNEL_LZ4 |
285 | bool "LZ4" | |
286 | depends on HAVE_KERNEL_LZ4 | |
287 | help | |
288 | LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding. | |
289 | A preliminary version of LZ4 de/compression tool is available at | |
290 | <https://code.google.com/p/lz4/>. | |
291 | ||
292 | Its compression ratio is worse than LZO. The size of the kernel | |
293 | is about 8% bigger than LZO. But the decompression speed is | |
294 | faster than LZO. | |
295 | ||
48f7ddf7 NT |
296 | config KERNEL_ZSTD |
297 | bool "ZSTD" | |
298 | depends on HAVE_KERNEL_ZSTD | |
299 | help | |
300 | ZSTD is a compression algorithm targeting intermediate compression | |
301 | with fast decompression speed. It will compress better than GZIP and | |
302 | decompress around the same speed as LZO, but slower than LZ4. You | |
303 | will need at least 192 KB RAM or more for booting. The zstd command | |
304 | line tool is required for compression. | |
305 | ||
f16466af VG |
306 | config KERNEL_UNCOMPRESSED |
307 | bool "None" | |
308 | depends on HAVE_KERNEL_UNCOMPRESSED | |
309 | help | |
310 | Produce uncompressed kernel image. This option is usually not what | |
311 | you want. It is useful for debugging the kernel in slow simulation | |
312 | environments, where decompressing and moving the kernel is awfully | |
313 | slow. This option allows early boot code to skip the decompressor | |
314 | and jump right at uncompressed kernel image. | |
315 | ||
30d65dbf AK |
316 | endchoice |
317 | ||
ada4ab7a CD |
318 | config DEFAULT_INIT |
319 | string "Default init path" | |
320 | default "" | |
321 | help | |
322 | This option determines the default init for the system if no init= | |
323 | option is passed on the kernel command line. If the requested path is | |
324 | not present, we will still then move on to attempting further | |
325 | locations (e.g. /sbin/init, etc). If this is empty, we will just use | |
326 | the fallback list when init= is not passed. | |
327 | ||
bd5dc17b JT |
328 | config DEFAULT_HOSTNAME |
329 | string "Default hostname" | |
330 | default "(none)" | |
331 | help | |
332 | This option determines the default system hostname before userspace | |
333 | calls sethostname(2). The kernel traditionally uses "(none)" here, | |
334 | but you may wish to use a different default here to make a minimal | |
335 | system more usable with less configuration. | |
336 | ||
17c46a6a CH |
337 | # |
338 | # For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can | |
339 | # add proper SWAP support to them, in which case this can be remove. | |
340 | # | |
341 | config ARCH_NO_SWAP | |
342 | bool | |
343 | ||
1da177e4 LT |
344 | config SWAP |
345 | bool "Support for paging of anonymous memory (swap)" | |
17c46a6a | 346 | depends on MMU && BLOCK && !ARCH_NO_SWAP |
1da177e4 LT |
347 | default y |
348 | help | |
349 | This option allows you to choose whether you want to have support | |
92c3504e | 350 | for so called swap devices or swap files in your kernel that are |
1da177e4 LT |
351 | used to provide more virtual memory than the actual RAM present |
352 | in your computer. If unsure say Y. | |
353 | ||
354 | config SYSVIPC | |
355 | bool "System V IPC" | |
a7f7f624 | 356 | help |
1da177e4 LT |
357 | Inter Process Communication is a suite of library functions and |
358 | system calls which let processes (running programs) synchronize and | |
359 | exchange information. It is generally considered to be a good thing, | |
360 | and some programs won't run unless you say Y here. In particular, if | |
361 | you want to run the DOS emulator dosemu under Linux (read the | |
362 | DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), | |
363 | you'll need to say Y here. | |
364 | ||
365 | You can find documentation about IPC with "info ipc" and also in | |
366 | section 6.4 of the Linux Programmer's Guide, available from | |
367 | <http://www.tldp.org/guides.html>. | |
368 | ||
a5494dcd EB |
369 | config SYSVIPC_SYSCTL |
370 | bool | |
371 | depends on SYSVIPC | |
372 | depends on SYSCTL | |
373 | default y | |
374 | ||
1da177e4 LT |
375 | config POSIX_MQUEUE |
376 | bool "POSIX Message Queues" | |
19c92399 | 377 | depends on NET |
a7f7f624 | 378 | help |
1da177e4 LT |
379 | POSIX variant of message queues is a part of IPC. In POSIX message |
380 | queues every message has a priority which decides about succession | |
381 | of receiving it by a process. If you want to compile and run | |
382 | programs written e.g. for Solaris with use of its POSIX message | |
b0e37650 | 383 | queues (functions mq_*) say Y here. |
1da177e4 LT |
384 | |
385 | POSIX message queues are visible as a filesystem called 'mqueue' | |
386 | and can be mounted somewhere if you want to do filesystem | |
387 | operations on message queues. | |
388 | ||
389 | If unsure, say Y. | |
390 | ||
bdc8e5f8 SH |
391 | config POSIX_MQUEUE_SYSCTL |
392 | bool | |
393 | depends on POSIX_MQUEUE | |
394 | depends on SYSCTL | |
395 | default y | |
396 | ||
c73be61c DH |
397 | config WATCH_QUEUE |
398 | bool "General notification queue" | |
399 | default n | |
400 | help | |
401 | ||
402 | This is a general notification queue for the kernel to pass events to | |
403 | userspace by splicing them into pipes. It can be used in conjunction | |
404 | with watches for key/keyring change notifications and device | |
405 | notifications. | |
406 | ||
407 | See Documentation/watch_queue.rst | |
408 | ||
226b4ccd KK |
409 | config CROSS_MEMORY_ATTACH |
410 | bool "Enable process_vm_readv/writev syscalls" | |
411 | depends on MMU | |
412 | default y | |
413 | help | |
414 | Enabling this option adds the system calls process_vm_readv and | |
415 | process_vm_writev which allow a process with the correct privileges | |
a2a368d9 | 416 | to directly read from or write to another process' address space. |
226b4ccd KK |
417 | See the man page for more details. |
418 | ||
69369a70 JT |
419 | config USELIB |
420 | bool "uselib syscall" | |
b2113a41 | 421 | def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION |
69369a70 JT |
422 | help |
423 | This option enables the uselib syscall, a system call used in the | |
424 | dynamic linker from libc5 and earlier. glibc does not use this | |
425 | system call. If you intend to run programs built on libc5 or | |
426 | earlier, you may need to enable this syscall. Current systems | |
427 | running glibc can safely disable this. | |
428 | ||
391dc69c FW |
429 | config AUDIT |
430 | bool "Auditing support" | |
431 | depends on NET | |
432 | help | |
433 | Enable auditing infrastructure that can be used with another | |
434 | kernel subsystem, such as SELinux (which requires this for | |
cb74ed27 PM |
435 | logging of avc messages output). System call auditing is included |
436 | on architectures which support it. | |
391dc69c | 437 | |
7a017721 AT |
438 | config HAVE_ARCH_AUDITSYSCALL |
439 | bool | |
440 | ||
391dc69c | 441 | config AUDITSYSCALL |
cb74ed27 | 442 | def_bool y |
7a017721 | 443 | depends on AUDIT && HAVE_ARCH_AUDITSYSCALL |
391dc69c FW |
444 | select FSNOTIFY |
445 | ||
391dc69c FW |
446 | source "kernel/irq/Kconfig" |
447 | source "kernel/time/Kconfig" | |
b24abcff | 448 | source "kernel/bpf/Kconfig" |
87a4c375 | 449 | source "kernel/Kconfig.preempt" |
391dc69c FW |
450 | |
451 | menu "CPU/Task time and stats accounting" | |
452 | ||
abf917cd FW |
453 | config VIRT_CPU_ACCOUNTING |
454 | bool | |
455 | ||
fdf9c356 FW |
456 | choice |
457 | prompt "Cputime accounting" | |
458 | default TICK_CPU_ACCOUNTING if !PPC64 | |
02fc8d37 | 459 | default VIRT_CPU_ACCOUNTING_NATIVE if PPC64 |
fdf9c356 FW |
460 | |
461 | # Kind of a stub config for the pure tick based cputime accounting | |
462 | config TICK_CPU_ACCOUNTING | |
463 | bool "Simple tick based cputime accounting" | |
c58b0df1 | 464 | depends on !S390 && !NO_HZ_FULL |
fdf9c356 FW |
465 | help |
466 | This is the basic tick based cputime accounting that maintains | |
467 | statistics about user, system and idle time spent on per jiffies | |
468 | granularity. | |
469 | ||
470 | If unsure, say Y. | |
471 | ||
abf917cd | 472 | config VIRT_CPU_ACCOUNTING_NATIVE |
b952741c | 473 | bool "Deterministic task and CPU time accounting" |
c58b0df1 | 474 | depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL |
abf917cd | 475 | select VIRT_CPU_ACCOUNTING |
b952741c FW |
476 | help |
477 | Select this option to enable more accurate task and CPU time | |
478 | accounting. This is done by reading a CPU counter on each | |
479 | kernel entry and exit and on transitions within the kernel | |
480 | between system, softirq and hardirq state, so there is a | |
481 | small performance impact. In the case of s390 or IBM POWER > 5, | |
482 | this also enables accounting of stolen time on logically-partitioned | |
483 | systems. | |
484 | ||
abf917cd FW |
485 | config VIRT_CPU_ACCOUNTING_GEN |
486 | bool "Full dynticks CPU time accounting" | |
ff3fb254 | 487 | depends on HAVE_CONTEXT_TRACKING |
554b0004 | 488 | depends on HAVE_VIRT_CPU_ACCOUNTING_GEN |
041a1574 | 489 | depends on GENERIC_CLOCKEVENTS |
abf917cd FW |
490 | select VIRT_CPU_ACCOUNTING |
491 | select CONTEXT_TRACKING | |
492 | help | |
493 | Select this option to enable task and CPU time accounting on full | |
494 | dynticks systems. This accounting is implemented by watching every | |
495 | kernel-user boundaries using the context tracking subsystem. | |
496 | The accounting is thus performed at the expense of some significant | |
497 | overhead. | |
498 | ||
499 | For now this is only useful if you are working on the full | |
500 | dynticks subsystem development. | |
501 | ||
502 | If unsure, say N. | |
503 | ||
b58c3584 RR |
504 | endchoice |
505 | ||
fdf9c356 FW |
506 | config IRQ_TIME_ACCOUNTING |
507 | bool "Fine granularity task level IRQ time accounting" | |
b58c3584 | 508 | depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE |
fdf9c356 FW |
509 | help |
510 | Select this option to enable fine granularity task irq time | |
511 | accounting. This is done by reading a timestamp on each | |
512 | transitions between softirq and hardirq state, so there can be a | |
513 | small performance impact. | |
514 | ||
515 | If in doubt, say N here. | |
516 | ||
11d4afd4 VG |
517 | config HAVE_SCHED_AVG_IRQ |
518 | def_bool y | |
519 | depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING | |
520 | depends on SMP | |
521 | ||
76504793 | 522 | config SCHED_THERMAL_PRESSURE |
98eb401d | 523 | bool |
fcd7c9c3 VS |
524 | default y if ARM && ARM_CPU_TOPOLOGY |
525 | default y if ARM64 | |
76504793 | 526 | depends on SMP |
98eb401d VS |
527 | depends on CPU_FREQ_THERMAL |
528 | help | |
529 | Select this option to enable thermal pressure accounting in the | |
530 | scheduler. Thermal pressure is the value conveyed to the scheduler | |
531 | that reflects the reduction in CPU compute capacity resulted from | |
532 | thermal throttling. Thermal throttling occurs when the performance of | |
533 | a CPU is capped due to high operating temperatures. | |
534 | ||
535 | If selected, the scheduler will be able to balance tasks accordingly, | |
536 | i.e. put less load on throttled CPUs than on non/less throttled ones. | |
537 | ||
538 | This requires the architecture to implement | |
432900f8 | 539 | arch_set_thermal_pressure() and arch_scale_thermal_pressure(). |
76504793 | 540 | |
1da177e4 LT |
541 | config BSD_PROCESS_ACCT |
542 | bool "BSD Process Accounting" | |
2813893f | 543 | depends on MULTIUSER |
1da177e4 LT |
544 | help |
545 | If you say Y here, a user level program will be able to instruct the | |
546 | kernel (via a special system call) to write process accounting | |
547 | information to a file: whenever a process exits, information about | |
548 | that process will be appended to the file by the kernel. The | |
549 | information includes things such as creation time, owning user, | |
550 | command name, memory usage, controlling terminal etc. (the complete | |
551 | list is in the struct acct in <file:include/linux/acct.h>). It is | |
552 | up to the user level program to do useful things with this | |
553 | information. This is generally a good idea, so say Y. | |
554 | ||
555 | config BSD_PROCESS_ACCT_V3 | |
556 | bool "BSD Process Accounting version 3 file format" | |
557 | depends on BSD_PROCESS_ACCT | |
558 | default n | |
559 | help | |
560 | If you say Y here, the process accounting information is written | |
561 | in a new file format that also logs the process IDs of each | |
3903bf94 | 562 | process and its parent. Note that this file format is incompatible |
1da177e4 LT |
563 | with previous v0/v1/v2 file formats, so you will need updated tools |
564 | for processing it. A preliminary version of these tools is available | |
37a4c940 | 565 | at <http://www.gnu.org/software/acct/>. |
1da177e4 | 566 | |
c757249a | 567 | config TASKSTATS |
19c92399 | 568 | bool "Export task/process statistics through netlink" |
c757249a | 569 | depends on NET |
2813893f | 570 | depends on MULTIUSER |
c757249a SN |
571 | default n |
572 | help | |
573 | Export selected statistics for tasks/processes through the | |
574 | generic netlink interface. Unlike BSD process accounting, the | |
575 | statistics are available during the lifetime of tasks/processes as | |
576 | responses to commands. Like BSD accounting, they are sent to user | |
577 | space on task exit. | |
578 | ||
579 | Say N if unsure. | |
580 | ||
ca74e92b | 581 | config TASK_DELAY_ACCT |
19c92399 | 582 | bool "Enable per-task delay accounting" |
6f44993f | 583 | depends on TASKSTATS |
f6db8347 | 584 | select SCHED_INFO |
ca74e92b SN |
585 | help |
586 | Collect information on time spent by a task waiting for system | |
587 | resources like cpu, synchronous block I/O completion and swapping | |
588 | in pages. Such statistics can help in setting a task's priorities | |
589 | relative to other tasks for cpu, io, rss limits etc. | |
590 | ||
591 | Say N if unsure. | |
592 | ||
18f705f4 | 593 | config TASK_XACCT |
19c92399 | 594 | bool "Enable extended accounting over taskstats" |
18f705f4 AD |
595 | depends on TASKSTATS |
596 | help | |
597 | Collect extended task accounting data and send the data | |
598 | to userland for processing over the taskstats interface. | |
599 | ||
600 | Say N if unsure. | |
601 | ||
602 | config TASK_IO_ACCOUNTING | |
19c92399 | 603 | bool "Enable per-task storage I/O accounting" |
18f705f4 AD |
604 | depends on TASK_XACCT |
605 | help | |
606 | Collect information on the number of bytes of storage I/O which this | |
607 | task has caused. | |
608 | ||
609 | Say N if unsure. | |
610 | ||
eb414681 JW |
611 | config PSI |
612 | bool "Pressure stall information tracking" | |
613 | help | |
614 | Collect metrics that indicate how overcommitted the CPU, memory, | |
615 | and IO capacity are in the system. | |
616 | ||
617 | If you say Y here, the kernel will create /proc/pressure/ with the | |
618 | pressure statistics files cpu, memory, and io. These will indicate | |
619 | the share of walltime in which some or all tasks in the system are | |
620 | delayed due to contention of the respective resource. | |
621 | ||
2ce7135a JW |
622 | In kernels with cgroup support, cgroups (cgroup2 only) will |
623 | have cpu.pressure, memory.pressure, and io.pressure files, | |
624 | which aggregate pressure stalls for the grouped tasks only. | |
625 | ||
c3123552 | 626 | For more details see Documentation/accounting/psi.rst. |
eb414681 JW |
627 | |
628 | Say N if unsure. | |
629 | ||
e0c27447 JW |
630 | config PSI_DEFAULT_DISABLED |
631 | bool "Require boot parameter to enable pressure stall information tracking" | |
632 | default n | |
633 | depends on PSI | |
634 | help | |
635 | If set, pressure stall information tracking will be disabled | |
428a1cb4 BS |
636 | per default but can be enabled through passing psi=1 on the |
637 | kernel commandline during boot. | |
e0c27447 | 638 | |
7b2489d3 JW |
639 | This feature adds some code to the task wakeup and sleep |
640 | paths of the scheduler. The overhead is too low to affect | |
641 | common scheduling-intense workloads in practice (such as | |
642 | webservers, memcache), but it does show up in artificial | |
643 | scheduler stress tests, such as hackbench. | |
644 | ||
645 | If you are paranoid and not sure what the kernel will be | |
646 | used for, say Y. | |
647 | ||
648 | Say N if unsure. | |
649 | ||
391dc69c | 650 | endmenu # "CPU/Task time and stats accounting" |
d9817ebe | 651 | |
5c4991e2 FW |
652 | config CPU_ISOLATION |
653 | bool "CPU isolation" | |
414a2dc1 | 654 | depends on SMP || COMPILE_TEST |
2c43838c | 655 | default y |
5c4991e2 FW |
656 | help |
657 | Make sure that CPUs running critical tasks are not disturbed by | |
658 | any source of "noise" such as unbound workqueues, timers, kthreads... | |
2c43838c FW |
659 | Unbound jobs get offloaded to housekeeping CPUs. This is driven by |
660 | the "isolcpus=" boot parameter. | |
661 | ||
662 | Say Y if unsure. | |
5c4991e2 | 663 | |
0af92d46 | 664 | source "kernel/rcu/Kconfig" |
c903ff83 | 665 | |
de5b56ba VG |
666 | config BUILD_BIN2C |
667 | bool | |
668 | default n | |
669 | ||
1da177e4 | 670 | config IKCONFIG |
f2443ab6 | 671 | tristate "Kernel .config support" |
a7f7f624 | 672 | help |
1da177e4 LT |
673 | This option enables the complete Linux kernel ".config" file |
674 | contents to be saved in the kernel. It provides documentation | |
675 | of which kernel options are used in a running kernel or in an | |
676 | on-disk kernel. This information can be extracted from the kernel | |
677 | image file with the script scripts/extract-ikconfig and used as | |
678 | input to rebuild the current kernel or to build another kernel. | |
679 | It can also be extracted from a running kernel by reading | |
680 | /proc/config.gz if enabled (below). | |
681 | ||
682 | config IKCONFIG_PROC | |
683 | bool "Enable access to .config through /proc/config.gz" | |
684 | depends on IKCONFIG && PROC_FS | |
a7f7f624 | 685 | help |
1da177e4 LT |
686 | This option enables access to the kernel configuration file |
687 | through /proc/config.gz. | |
688 | ||
f7b101d3 JFG |
689 | config IKHEADERS |
690 | tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz" | |
691 | depends on SYSFS | |
692 | help | |
693 | This option enables access to the in-kernel headers that are generated during | |
694 | the build process. These can be used to build eBPF tracing programs, | |
695 | or similar programs. If you build the headers as a module, a module called | |
696 | kheaders.ko is built which can be loaded on-demand to get access to headers. | |
43d8ce9d | 697 | |
794543a2 AJS |
698 | config LOG_BUF_SHIFT |
699 | int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" | |
550c10d2 JO |
700 | range 12 25 if !H8300 |
701 | range 12 19 if H8300 | |
f17a32e9 | 702 | default 17 |
361e9dfb | 703 | depends on PRINTK |
794543a2 | 704 | help |
23b2899f LR |
705 | Select the minimal kernel log buffer size as a power of 2. |
706 | The final size is affected by LOG_CPU_MAX_BUF_SHIFT config | |
707 | parameter, see below. Any higher size also might be forced | |
708 | by "log_buf_len" boot parameter. | |
709 | ||
f17a32e9 | 710 | Examples: |
23b2899f | 711 | 17 => 128 KB |
f17a32e9 | 712 | 16 => 64 KB |
23b2899f LR |
713 | 15 => 32 KB |
714 | 14 => 16 KB | |
794543a2 AJS |
715 | 13 => 8 KB |
716 | 12 => 4 KB | |
717 | ||
23b2899f LR |
718 | config LOG_CPU_MAX_BUF_SHIFT |
719 | int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" | |
2240a31d | 720 | depends on SMP |
23b2899f LR |
721 | range 0 21 |
722 | default 12 if !BASE_SMALL | |
723 | default 0 if BASE_SMALL | |
361e9dfb | 724 | depends on PRINTK |
23b2899f LR |
725 | help |
726 | This option allows to increase the default ring buffer size | |
727 | according to the number of CPUs. The value defines the contribution | |
728 | of each CPU as a power of 2. The used space is typically only few | |
729 | lines however it might be much more when problems are reported, | |
730 | e.g. backtraces. | |
731 | ||
732 | The increased size means that a new buffer has to be allocated and | |
733 | the original static one is unused. It makes sense only on systems | |
734 | with more CPUs. Therefore this value is used only when the sum of | |
735 | contributions is greater than the half of the default kernel ring | |
736 | buffer as defined by LOG_BUF_SHIFT. The default values are set | |
0f7636e1 | 737 | so that more than 16 CPUs are needed to trigger the allocation. |
23b2899f LR |
738 | |
739 | Also this option is ignored when "log_buf_len" kernel parameter is | |
740 | used as it forces an exact (power of two) size of the ring buffer. | |
741 | ||
742 | The number of possible CPUs is used for this computation ignoring | |
5e0d8d59 GU |
743 | hotplugging making the computation optimal for the worst case |
744 | scenario while allowing a simple algorithm to be used from bootup. | |
23b2899f LR |
745 | |
746 | Examples shift values and their meaning: | |
747 | 17 => 128 KB for each CPU | |
748 | 16 => 64 KB for each CPU | |
749 | 15 => 32 KB for each CPU | |
750 | 14 => 16 KB for each CPU | |
751 | 13 => 8 KB for each CPU | |
752 | 12 => 4 KB for each CPU | |
753 | ||
f92bac3b SS |
754 | config PRINTK_SAFE_LOG_BUF_SHIFT |
755 | int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)" | |
427934b8 PM |
756 | range 10 21 |
757 | default 13 | |
f92bac3b | 758 | depends on PRINTK |
427934b8 | 759 | help |
f92bac3b SS |
760 | Select the size of an alternate printk per-CPU buffer where messages |
761 | printed from usafe contexts are temporary stored. One example would | |
762 | be NMI messages, another one - printk recursion. The messages are | |
763 | copied to the main log buffer in a safe context to avoid a deadlock. | |
764 | The value defines the size as a power of 2. | |
427934b8 | 765 | |
f92bac3b | 766 | Those messages are rare and limited. The largest one is when |
427934b8 PM |
767 | a backtrace is printed. It usually fits into 4KB. Select |
768 | 8KB if you want to be on the safe side. | |
769 | ||
770 | Examples: | |
771 | 17 => 128 KB for each CPU | |
772 | 16 => 64 KB for each CPU | |
773 | 15 => 32 KB for each CPU | |
774 | 14 => 16 KB for each CPU | |
775 | 13 => 8 KB for each CPU | |
776 | 12 => 4 KB for each CPU | |
777 | ||
a5574cf6 IM |
778 | # |
779 | # Architectures with an unreliable sched_clock() should select this: | |
780 | # | |
781 | config HAVE_UNSTABLE_SCHED_CLOCK | |
782 | bool | |
783 | ||
38ff87f7 SB |
784 | config GENERIC_SCHED_CLOCK |
785 | bool | |
786 | ||
69842cba PB |
787 | menu "Scheduler features" |
788 | ||
789 | config UCLAMP_TASK | |
790 | bool "Enable utilization clamping for RT/FAIR tasks" | |
791 | depends on CPU_FREQ_GOV_SCHEDUTIL | |
792 | help | |
793 | This feature enables the scheduler to track the clamped utilization | |
794 | of each CPU based on RUNNABLE tasks scheduled on that CPU. | |
795 | ||
796 | With this option, the user can specify the min and max CPU | |
797 | utilization allowed for RUNNABLE tasks. The max utilization defines | |
798 | the maximum frequency a task should use while the min utilization | |
799 | defines the minimum frequency it should use. | |
800 | ||
801 | Both min and max utilization clamp values are hints to the scheduler, | |
802 | aiming at improving its frequency selection policy, but they do not | |
803 | enforce or grant any specific bandwidth for tasks. | |
804 | ||
805 | If in doubt, say N. | |
806 | ||
807 | config UCLAMP_BUCKETS_COUNT | |
808 | int "Number of supported utilization clamp buckets" | |
809 | range 5 20 | |
810 | default 5 | |
811 | depends on UCLAMP_TASK | |
812 | help | |
813 | Defines the number of clamp buckets to use. The range of each bucket | |
814 | will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the | |
815 | number of clamp buckets the finer their granularity and the higher | |
816 | the precision of clamping aggregation and tracking at run-time. | |
817 | ||
818 | For example, with the minimum configuration value we will have 5 | |
819 | clamp buckets tracking 20% utilization each. A 25% boosted tasks will | |
820 | be refcounted in the [20..39]% bucket and will set the bucket clamp | |
821 | effective value to 25%. | |
822 | If a second 30% boosted task should be co-scheduled on the same CPU, | |
823 | that task will be refcounted in the same bucket of the first task and | |
824 | it will boost the bucket clamp effective value to 30%. | |
825 | The clamp effective value of a bucket is reset to its nominal value | |
826 | (20% in the example above) when there are no more tasks refcounted in | |
827 | that bucket. | |
828 | ||
829 | An additional boost/capping margin can be added to some tasks. In the | |
830 | example above the 25% task will be boosted to 30% until it exits the | |
831 | CPU. If that should be considered not acceptable on certain systems, | |
832 | it's always possible to reduce the margin by increasing the number of | |
833 | clamp buckets to trade off used memory for run-time tracking | |
834 | precision. | |
835 | ||
836 | If in doubt, use the default value. | |
837 | ||
838 | endmenu | |
839 | ||
be3a7284 AA |
840 | # |
841 | # For architectures that want to enable the support for NUMA-affine scheduler | |
842 | # balancing logic: | |
843 | # | |
844 | config ARCH_SUPPORTS_NUMA_BALANCING | |
845 | bool | |
846 | ||
72b252ae MG |
847 | # |
848 | # For architectures that prefer to flush all TLBs after a number of pages | |
849 | # are unmapped instead of sending one IPI per page to flush. The architecture | |
850 | # must provide guarantees on what happens if a clean TLB cache entry is | |
851 | # written after the unmap. Details are in mm/rmap.c near the check for | |
852 | # should_defer_flush. The architecture should also consider if the full flush | |
853 | # and the refill costs are offset by the savings of sending fewer IPIs. | |
854 | config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH | |
855 | bool | |
856 | ||
c12d3362 | 857 | config CC_HAS_INT128 |
3a7c7331 | 858 | def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT |
c12d3362 | 859 | |
be5e610c PZ |
860 | # |
861 | # For architectures that know their GCC __int128 support is sound | |
862 | # | |
863 | config ARCH_SUPPORTS_INT128 | |
864 | bool | |
865 | ||
be3a7284 AA |
866 | # For architectures that (ab)use NUMA to represent different memory regions |
867 | # all cpu-local but of different latencies, such as SuperH. | |
868 | # | |
869 | config ARCH_WANT_NUMA_VARIABLE_LOCALITY | |
870 | bool | |
871 | ||
be3a7284 AA |
872 | config NUMA_BALANCING |
873 | bool "Memory placement aware NUMA scheduler" | |
be3a7284 AA |
874 | depends on ARCH_SUPPORTS_NUMA_BALANCING |
875 | depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY | |
876 | depends on SMP && NUMA && MIGRATION | |
877 | help | |
878 | This option adds support for automatic NUMA aware memory/task placement. | |
879 | The mechanism is quite primitive and is based on migrating memory when | |
6d56a410 | 880 | it has references to the node the task is running on. |
be3a7284 AA |
881 | |
882 | This system will be inactive on UMA systems. | |
883 | ||
6f7c97e8 AK |
884 | config NUMA_BALANCING_DEFAULT_ENABLED |
885 | bool "Automatically enable NUMA aware memory/task placement" | |
886 | default y | |
887 | depends on NUMA_BALANCING | |
888 | help | |
889 | If set, automatic NUMA balancing will be enabled if running on a NUMA | |
890 | machine. | |
891 | ||
23964d2d | 892 | menuconfig CGROUPS |
6341e62b | 893 | bool "Control Group support" |
2bd59d48 | 894 | select KERNFS |
5cdc38f9 | 895 | help |
23964d2d | 896 | This option adds support for grouping sets of processes together, for |
5cdc38f9 KH |
897 | use with process control subsystems such as Cpusets, CFS, memory |
898 | controls or device isolation. | |
899 | See | |
d6a3b247 | 900 | - Documentation/scheduler/sched-design-CFS.rst (CFS) |
da82c92f | 901 | - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation |
45ce80fb | 902 | and resource control) |
5cdc38f9 KH |
903 | |
904 | Say N if unsure. | |
905 | ||
23964d2d LZ |
906 | if CGROUPS |
907 | ||
3e32cb2e | 908 | config PAGE_COUNTER |
e8cf4e9c | 909 | bool |
3e32cb2e | 910 | |
c255a458 | 911 | config MEMCG |
a0166ec4 | 912 | bool "Memory controller" |
3e32cb2e | 913 | select PAGE_COUNTER |
79bd9814 | 914 | select EVENTFD |
00f0b825 | 915 | help |
a0166ec4 | 916 | Provides control over the memory footprint of tasks in a cgroup. |
00f0b825 | 917 | |
c255a458 | 918 | config MEMCG_SWAP |
2d1c4980 | 919 | bool |
c255a458 | 920 | depends on MEMCG && SWAP |
a42c390c | 921 | default y |
c077719b | 922 | |
84c07d11 KT |
923 | config MEMCG_KMEM |
924 | bool | |
925 | depends on MEMCG && !SLOB | |
926 | default y | |
927 | ||
6bf024e6 JW |
928 | config BLK_CGROUP |
929 | bool "IO controller" | |
930 | depends on BLOCK | |
2bc64a20 | 931 | default n |
a7f7f624 | 932 | help |
6bf024e6 JW |
933 | Generic block IO controller cgroup interface. This is the common |
934 | cgroup interface which should be used by various IO controlling | |
935 | policies. | |
2bc64a20 | 936 | |
6bf024e6 JW |
937 | Currently, CFQ IO scheduler uses it to recognize task groups and |
938 | control disk bandwidth allocation (proportional time slice allocation) | |
939 | to such task groups. It is also used by bio throttling logic in | |
940 | block layer to implement upper limit in IO rates on a device. | |
e5d1367f | 941 | |
6bf024e6 JW |
942 | This option only enables generic Block IO controller infrastructure. |
943 | One needs to also enable actual IO controlling logic/policy. For | |
944 | enabling proportional weight division of disk bandwidth in CFQ, set | |
7baf2199 | 945 | CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set |
6bf024e6 JW |
946 | CONFIG_BLK_DEV_THROTTLING=y. |
947 | ||
da82c92f | 948 | See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information. |
6bf024e6 | 949 | |
6bf024e6 JW |
950 | config CGROUP_WRITEBACK |
951 | bool | |
952 | depends on MEMCG && BLK_CGROUP | |
953 | default y | |
e5d1367f | 954 | |
7c941438 | 955 | menuconfig CGROUP_SCHED |
a0166ec4 | 956 | bool "CPU controller" |
7c941438 DG |
957 | default n |
958 | help | |
959 | This feature lets CPU scheduler recognize task groups and control CPU | |
960 | bandwidth allocation to such task groups. It uses cgroups to group | |
961 | tasks. | |
962 | ||
963 | if CGROUP_SCHED | |
964 | config FAIR_GROUP_SCHED | |
965 | bool "Group scheduling for SCHED_OTHER" | |
966 | depends on CGROUP_SCHED | |
967 | default CGROUP_SCHED | |
968 | ||
ab84d31e PT |
969 | config CFS_BANDWIDTH |
970 | bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" | |
ab84d31e PT |
971 | depends on FAIR_GROUP_SCHED |
972 | default n | |
973 | help | |
974 | This option allows users to define CPU bandwidth rates (limits) for | |
975 | tasks running within the fair group scheduler. Groups with no limit | |
976 | set are considered to be unconstrained and will run with no | |
977 | restriction. | |
d6a3b247 | 978 | See Documentation/scheduler/sched-bwc.rst for more information. |
ab84d31e | 979 | |
7c941438 DG |
980 | config RT_GROUP_SCHED |
981 | bool "Group scheduling for SCHED_RR/FIFO" | |
7c941438 DG |
982 | depends on CGROUP_SCHED |
983 | default n | |
984 | help | |
985 | This feature lets you explicitly allocate real CPU bandwidth | |
32bd7eb5 | 986 | to task groups. If enabled, it will also make it impossible to |
7c941438 DG |
987 | schedule realtime tasks for non-root users until you allocate |
988 | realtime bandwidth for them. | |
d6a3b247 | 989 | See Documentation/scheduler/sched-rt-group.rst for more information. |
7c941438 DG |
990 | |
991 | endif #CGROUP_SCHED | |
992 | ||
2480c093 PB |
993 | config UCLAMP_TASK_GROUP |
994 | bool "Utilization clamping per group of tasks" | |
995 | depends on CGROUP_SCHED | |
996 | depends on UCLAMP_TASK | |
997 | default n | |
998 | help | |
999 | This feature enables the scheduler to track the clamped utilization | |
1000 | of each CPU based on RUNNABLE tasks currently scheduled on that CPU. | |
1001 | ||
1002 | When this option is enabled, the user can specify a min and max | |
1003 | CPU bandwidth which is allowed for each single task in a group. | |
1004 | The max bandwidth allows to clamp the maximum frequency a task | |
1005 | can use, while the min bandwidth allows to define a minimum | |
1006 | frequency a task will always use. | |
1007 | ||
1008 | When task group based utilization clamping is enabled, an eventually | |
1009 | specified task-specific clamp value is constrained by the cgroup | |
1010 | specified clamp value. Both minimum and maximum task clamping cannot | |
1011 | be bigger than the corresponding clamping defined at task group level. | |
1012 | ||
1013 | If in doubt, say N. | |
1014 | ||
6bf024e6 JW |
1015 | config CGROUP_PIDS |
1016 | bool "PIDs controller" | |
1017 | help | |
1018 | Provides enforcement of process number limits in the scope of a | |
1019 | cgroup. Any attempt to fork more processes than is allowed in the | |
1020 | cgroup will fail. PIDs are fundamentally a global resource because it | |
1021 | is fairly trivial to reach PID exhaustion before you reach even a | |
1022 | conservative kmemcg limit. As a result, it is possible to grind a | |
1023 | system to halt without being limited by other cgroup policies. The | |
6cc578df | 1024 | PIDs controller is designed to stop this from happening. |
6bf024e6 JW |
1025 | |
1026 | It should be noted that organisational operations (such as attaching | |
98076833 | 1027 | to a cgroup hierarchy) will *not* be blocked by the PIDs controller, |
6bf024e6 JW |
1028 | since the PIDs limit only affects a process's ability to fork, not to |
1029 | attach to a cgroup. | |
1030 | ||
39d3e758 PP |
1031 | config CGROUP_RDMA |
1032 | bool "RDMA controller" | |
1033 | help | |
1034 | Provides enforcement of RDMA resources defined by IB stack. | |
1035 | It is fairly easy for consumers to exhaust RDMA resources, which | |
1036 | can result into resource unavailability to other consumers. | |
1037 | RDMA controller is designed to stop this from happening. | |
1038 | Attaching processes with active RDMA resources to the cgroup | |
1039 | hierarchy is allowed even if can cross the hierarchy's limit. | |
1040 | ||
6bf024e6 JW |
1041 | config CGROUP_FREEZER |
1042 | bool "Freezer controller" | |
1043 | help | |
1044 | Provides a way to freeze and unfreeze all tasks in a | |
1045 | cgroup. | |
1046 | ||
489c2a20 JW |
1047 | This option affects the ORIGINAL cgroup interface. The cgroup2 memory |
1048 | controller includes important in-kernel memory consumers per default. | |
1049 | ||
1050 | If you're using cgroup2, say N. | |
1051 | ||
6bf024e6 JW |
1052 | config CGROUP_HUGETLB |
1053 | bool "HugeTLB controller" | |
1054 | depends on HUGETLB_PAGE | |
1055 | select PAGE_COUNTER | |
afc24d49 | 1056 | default n |
6bf024e6 JW |
1057 | help |
1058 | Provides a cgroup controller for HugeTLB pages. | |
1059 | When you enable this, you can put a per cgroup limit on HugeTLB usage. | |
1060 | The limit is enforced during page fault. Since HugeTLB doesn't | |
1061 | support page reclaim, enforcing the limit at page fault time implies | |
1062 | that, the application will get SIGBUS signal if it tries to access | |
1063 | HugeTLB pages beyond its limit. This requires the application to know | |
1064 | beforehand how much HugeTLB pages it would require for its use. The | |
1065 | control group is tracked in the third page lru pointer. This means | |
1066 | that we cannot use the controller with huge page less than 3 pages. | |
afc24d49 | 1067 | |
6bf024e6 JW |
1068 | config CPUSETS |
1069 | bool "Cpuset controller" | |
e1d4eeec | 1070 | depends on SMP |
6bf024e6 JW |
1071 | help |
1072 | This option will let you create and manage CPUSETs which | |
1073 | allow dynamically partitioning a system into sets of CPUs and | |
1074 | Memory Nodes and assigning tasks to run only within those sets. | |
1075 | This is primarily useful on large SMP or NUMA systems. | |
afc24d49 | 1076 | |
6bf024e6 | 1077 | Say N if unsure. |
afc24d49 | 1078 | |
6bf024e6 JW |
1079 | config PROC_PID_CPUSET |
1080 | bool "Include legacy /proc/<pid>/cpuset file" | |
1081 | depends on CPUSETS | |
1082 | default y | |
afc24d49 | 1083 | |
6bf024e6 JW |
1084 | config CGROUP_DEVICE |
1085 | bool "Device controller" | |
1086 | help | |
1087 | Provides a cgroup controller implementing whitelists for | |
1088 | devices which a process in the cgroup can mknod or open. | |
1089 | ||
1090 | config CGROUP_CPUACCT | |
1091 | bool "Simple CPU accounting controller" | |
1092 | help | |
1093 | Provides a simple controller for monitoring the | |
1094 | total CPU consumed by the tasks in a cgroup. | |
1095 | ||
1096 | config CGROUP_PERF | |
1097 | bool "Perf controller" | |
1098 | depends on PERF_EVENTS | |
1099 | help | |
1100 | This option extends the perf per-cpu mode to restrict monitoring | |
1101 | to threads which belong to the cgroup specified and run on the | |
6546b19f NK |
1102 | designated cpu. Or this can be used to have cgroup ID in samples |
1103 | so that it can monitor performance events among cgroups. | |
6bf024e6 JW |
1104 | |
1105 | Say N if unsure. | |
1106 | ||
30070984 DM |
1107 | config CGROUP_BPF |
1108 | bool "Support for eBPF programs attached to cgroups" | |
483c4933 AL |
1109 | depends on BPF_SYSCALL |
1110 | select SOCK_CGROUP_DATA | |
30070984 DM |
1111 | help |
1112 | Allow attaching eBPF programs to a cgroup using the bpf(2) | |
1113 | syscall command BPF_PROG_ATTACH. | |
1114 | ||
1115 | In which context these programs are accessed depends on the type | |
1116 | of attachment. For instance, programs that are attached using | |
1117 | BPF_CGROUP_INET_INGRESS will be executed on the ingress path of | |
1118 | inet sockets. | |
1119 | ||
a72232ea VS |
1120 | config CGROUP_MISC |
1121 | bool "Misc resource controller" | |
1122 | default n | |
1123 | help | |
1124 | Provides a controller for miscellaneous resources on a host. | |
1125 | ||
1126 | Miscellaneous scalar resources are the resources on the host system | |
1127 | which cannot be abstracted like the other cgroups. This controller | |
1128 | tracks and limits the miscellaneous resources used by a process | |
1129 | attached to a cgroup hierarchy. | |
1130 | ||
1131 | For more information, please check misc cgroup section in | |
1132 | /Documentation/admin-guide/cgroup-v2.rst. | |
1133 | ||
6bf024e6 | 1134 | config CGROUP_DEBUG |
23b0be48 | 1135 | bool "Debug controller" |
afc24d49 | 1136 | default n |
23b0be48 | 1137 | depends on DEBUG_KERNEL |
6bf024e6 JW |
1138 | help |
1139 | This option enables a simple controller that exports | |
23b0be48 WL |
1140 | debugging information about the cgroups framework. This |
1141 | controller is for control cgroup debugging only. Its | |
1142 | interfaces are not stable. | |
afc24d49 | 1143 | |
6bf024e6 | 1144 | Say N. |
89e9b9e0 | 1145 | |
73b35147 AB |
1146 | config SOCK_CGROUP_DATA |
1147 | bool | |
1148 | default n | |
1149 | ||
23964d2d | 1150 | endif # CGROUPS |
c077719b | 1151 | |
8dd2a82c | 1152 | menuconfig NAMESPACES |
6a108a14 | 1153 | bool "Namespaces support" if EXPERT |
2813893f | 1154 | depends on MULTIUSER |
6a108a14 | 1155 | default !EXPERT |
c5289a69 PE |
1156 | help |
1157 | Provides the way to make tasks work with different objects using | |
1158 | the same id. For example same IPC id may refer to different objects | |
1159 | or same user id or pid may refer to different tasks when used in | |
1160 | different namespaces. | |
1161 | ||
8dd2a82c DL |
1162 | if NAMESPACES |
1163 | ||
58bfdd6d PE |
1164 | config UTS_NS |
1165 | bool "UTS namespace" | |
17a6d441 | 1166 | default y |
58bfdd6d PE |
1167 | help |
1168 | In this namespace tasks see different info provided with the | |
1169 | uname() system call | |
1170 | ||
769071ac AV |
1171 | config TIME_NS |
1172 | bool "TIME namespace" | |
660fd04f | 1173 | depends on GENERIC_VDSO_TIME_NS |
769071ac AV |
1174 | default y |
1175 | help | |
1176 | In this namespace boottime and monotonic clocks can be set. | |
1177 | The time will keep going with the same pace. | |
1178 | ||
ae5e1b22 PE |
1179 | config IPC_NS |
1180 | bool "IPC namespace" | |
8dd2a82c | 1181 | depends on (SYSVIPC || POSIX_MQUEUE) |
17a6d441 | 1182 | default y |
ae5e1b22 PE |
1183 | help |
1184 | In this namespace tasks work with IPC ids which correspond to | |
614b84cf | 1185 | different IPC objects in different namespaces. |
ae5e1b22 | 1186 | |
aee16ce7 | 1187 | config USER_NS |
19c92399 | 1188 | bool "User namespace" |
5673a94c | 1189 | default n |
aee16ce7 PE |
1190 | help |
1191 | This allows containers, i.e. vservers, to use user namespaces | |
1192 | to provide different user info for different servers. | |
e11f0ae3 EB |
1193 | |
1194 | When user namespaces are enabled in the kernel it is | |
d886f4e4 JW |
1195 | recommended that the MEMCG option also be enabled and that |
1196 | user-space use the memory control groups to limit the amount | |
1197 | of memory a memory unprivileged users can use. | |
e11f0ae3 | 1198 | |
aee16ce7 PE |
1199 | If unsure, say N. |
1200 | ||
74bd59bb | 1201 | config PID_NS |
9bd38c2c | 1202 | bool "PID Namespaces" |
17a6d441 | 1203 | default y |
74bd59bb | 1204 | help |
12d2b8f9 | 1205 | Support process id namespaces. This allows having multiple |
692105b8 | 1206 | processes with the same pid as long as they are in different |
74bd59bb PE |
1207 | pid namespaces. This is a building block of containers. |
1208 | ||
d6eb633f MH |
1209 | config NET_NS |
1210 | bool "Network namespace" | |
8dd2a82c | 1211 | depends on NET |
17a6d441 | 1212 | default y |
d6eb633f MH |
1213 | help |
1214 | Allow user space to create what appear to be multiple instances | |
1215 | of the network stack. | |
1216 | ||
8dd2a82c DL |
1217 | endif # NAMESPACES |
1218 | ||
5cb366bb AR |
1219 | config CHECKPOINT_RESTORE |
1220 | bool "Checkpoint/restore support" | |
1221 | select PROC_CHILDREN | |
bfe3911a | 1222 | select KCMP |
5cb366bb AR |
1223 | default n |
1224 | help | |
1225 | Enables additional kernel features in a sake of checkpoint/restore. | |
1226 | In particular it adds auxiliary prctl codes to setup process text, | |
1227 | data and heap segment sizes, and a few additional /proc filesystem | |
1228 | entries. | |
1229 | ||
1230 | If unsure, say N here. | |
1231 | ||
5091faa4 MG |
1232 | config SCHED_AUTOGROUP |
1233 | bool "Automatic process group scheduling" | |
5091faa4 MG |
1234 | select CGROUPS |
1235 | select CGROUP_SCHED | |
1236 | select FAIR_GROUP_SCHED | |
1237 | help | |
1238 | This option optimizes the scheduler for common desktop workloads by | |
1239 | automatically creating and populating task groups. This separation | |
1240 | of workloads isolates aggressive CPU burners (like build jobs) from | |
1241 | desktop applications. Task group autogeneration is currently based | |
1242 | upon task session. | |
1243 | ||
7af37bec | 1244 | config SYSFS_DEPRECATED |
5d6a4ea5 | 1245 | bool "Enable deprecated sysfs features to support old userspace tools" |
7af37bec DL |
1246 | depends on SYSFS |
1247 | default n | |
1248 | help | |
1249 | This option adds code that switches the layout of the "block" class | |
1250 | devices, to not show up in /sys/class/block/, but only in | |
1251 | /sys/block/. | |
1252 | ||
1253 | This switch is only active when the sysfs.deprecated=1 boot option is | |
1254 | passed or the SYSFS_DEPRECATED_V2 option is set. | |
1255 | ||
1256 | This option allows new kernels to run on old distributions and tools, | |
1257 | which might get confused by /sys/class/block/. Since 2007/2008 all | |
1258 | major distributions and tools handle this just fine. | |
1259 | ||
1260 | Recent distributions and userspace tools after 2009/2010 depend on | |
1261 | the existence of /sys/class/block/, and will not work with this | |
1262 | option enabled. | |
1263 | ||
1264 | Only if you are using a new kernel on an old distribution, you might | |
1265 | need to say Y here. | |
1266 | ||
1267 | config SYSFS_DEPRECATED_V2 | |
5d6a4ea5 | 1268 | bool "Enable deprecated sysfs features by default" |
7af37bec DL |
1269 | default n |
1270 | depends on SYSFS | |
1271 | depends on SYSFS_DEPRECATED | |
1272 | help | |
1273 | Enable deprecated sysfs by default. | |
1274 | ||
1275 | See the CONFIG_SYSFS_DEPRECATED option for more details about this | |
1276 | option. | |
1277 | ||
1278 | Only if you are using a new kernel on an old distribution, you might | |
1279 | need to say Y here. Even then, odds are you would not need it | |
1280 | enabled, you can always pass the boot option if absolutely necessary. | |
1281 | ||
1282 | config RELAY | |
1283 | bool "Kernel->user space relay support (formerly relayfs)" | |
26b5679e | 1284 | select IRQ_WORK |
7af37bec DL |
1285 | help |
1286 | This option enables support for relay interface support in | |
1287 | certain file systems (such as debugfs). | |
1288 | It is designed to provide an efficient mechanism for tools and | |
1289 | facilities to relay large amounts of data from kernel space to | |
1290 | user space. | |
1291 | ||
1292 | If unsure, say N. | |
1293 | ||
f991633d DG |
1294 | config BLK_DEV_INITRD |
1295 | bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" | |
f991633d DG |
1296 | help |
1297 | The initial RAM filesystem is a ramfs which is loaded by the | |
1298 | boot loader (loadlin or lilo) and that is mounted as root | |
1299 | before the normal boot procedure. It is typically used to | |
1300 | load modules needed to mount the "real" root file system, | |
8c27ceff | 1301 | etc. See <file:Documentation/admin-guide/initrd.rst> for details. |
f991633d DG |
1302 | |
1303 | If RAM disk support (BLK_DEV_RAM) is also included, this | |
1304 | also enables initial RAM disk (initrd) support and adds | |
1305 | 15 Kbytes (more on some other architectures) to the kernel size. | |
1306 | ||
1307 | If unsure say Y. | |
1308 | ||
c33df4ea JPS |
1309 | if BLK_DEV_INITRD |
1310 | ||
dbec4866 SR |
1311 | source "usr/Kconfig" |
1312 | ||
c33df4ea JPS |
1313 | endif |
1314 | ||
76db5a27 MH |
1315 | config BOOT_CONFIG |
1316 | bool "Boot config support" | |
2910b5aa | 1317 | select BLK_DEV_INITRD |
76db5a27 MH |
1318 | help |
1319 | Extra boot config allows system admin to pass a config file as | |
1320 | complemental extension of kernel cmdline when booting. | |
0947db01 | 1321 | The boot config file must be attached at the end of initramfs |
85c46b78 | 1322 | with checksum, size and magic word. |
0947db01 | 1323 | See <file:Documentation/admin-guide/bootconfig.rst> for details. |
76db5a27 MH |
1324 | |
1325 | If unsure, say Y. | |
1326 | ||
877417e6 AB |
1327 | choice |
1328 | prompt "Compiler optimization level" | |
2cc3ce24 | 1329 | default CC_OPTIMIZE_FOR_PERFORMANCE |
877417e6 AB |
1330 | |
1331 | config CC_OPTIMIZE_FOR_PERFORMANCE | |
15f5db60 | 1332 | bool "Optimize for performance (-O2)" |
877417e6 AB |
1333 | help |
1334 | This is the default optimization level for the kernel, building | |
1335 | with the "-O2" compiler flag for best performance and most | |
1336 | helpful compile-time warnings. | |
1337 | ||
15f5db60 MY |
1338 | config CC_OPTIMIZE_FOR_PERFORMANCE_O3 |
1339 | bool "Optimize more for performance (-O3)" | |
1340 | depends on ARC | |
c45b4f1f | 1341 | help |
15f5db60 MY |
1342 | Choosing this option will pass "-O3" to your compiler to optimize |
1343 | the kernel yet more for performance. | |
c45b4f1f | 1344 | |
c45b4f1f | 1345 | config CC_OPTIMIZE_FOR_SIZE |
15f5db60 | 1346 | bool "Optimize for size (-Os)" |
c45b4f1f | 1347 | help |
ce3b487f MY |
1348 | Choosing this option will pass "-Os" to your compiler resulting |
1349 | in a smaller kernel. | |
c45b4f1f | 1350 | |
877417e6 AB |
1351 | endchoice |
1352 | ||
5d20ee31 NP |
1353 | config HAVE_LD_DEAD_CODE_DATA_ELIMINATION |
1354 | bool | |
1355 | help | |
1356 | This requires that the arch annotates or otherwise protects | |
1357 | its external entry points from being discarded. Linker scripts | |
1358 | must also merge .text.*, .data.*, and .bss.* correctly into | |
1359 | output sections. Care must be taken not to pull in unrelated | |
1360 | sections (e.g., '.text.init'). Typically '.' in section names | |
1361 | is used to distinguish them from label names / C identifiers. | |
1362 | ||
1363 | config LD_DEAD_CODE_DATA_ELIMINATION | |
1364 | bool "Dead code and data elimination (EXPERIMENTAL)" | |
1365 | depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION | |
1366 | depends on EXPERT | |
e85d1d65 MY |
1367 | depends on $(cc-option,-ffunction-sections -fdata-sections) |
1368 | depends on $(ld-option,--gc-sections) | |
5d20ee31 | 1369 | help |
8b9d2712 MY |
1370 | Enable this if you want to do dead code and data elimination with |
1371 | the linker by compiling with -ffunction-sections -fdata-sections, | |
1372 | and linking with --gc-sections. | |
5d20ee31 NP |
1373 | |
1374 | This can reduce on disk and in-memory size of the kernel | |
1375 | code and static data, particularly for small configs and | |
1376 | on small systems. This has the possibility of introducing | |
1377 | silently broken kernel if the required annotations are not | |
1378 | present. This option is not well tested yet, so use at your | |
1379 | own risk. | |
1380 | ||
59612b24 NC |
1381 | config LD_ORPHAN_WARN |
1382 | def_bool y | |
1383 | depends on ARCH_WANT_LD_ORPHAN_WARN | |
d5750cd3 | 1384 | depends on !LD_IS_LLD || LLD_VERSION >= 110000 |
59612b24 NC |
1385 | depends on $(ld-option,--orphan-handling=warn) |
1386 | ||
0847062a RD |
1387 | config SYSCTL |
1388 | bool | |
1389 | ||
657a5209 MF |
1390 | config HAVE_UID16 |
1391 | bool | |
1392 | ||
1393 | config SYSCTL_EXCEPTION_TRACE | |
1394 | bool | |
1395 | help | |
1396 | Enable support for /proc/sys/debug/exception-trace. | |
1397 | ||
1398 | config SYSCTL_ARCH_UNALIGN_NO_WARN | |
1399 | bool | |
1400 | help | |
1401 | Enable support for /proc/sys/kernel/ignore-unaligned-usertrap | |
1402 | Allows arch to define/use @no_unaligned_warning to possibly warn | |
1403 | about unaligned access emulation going on under the hood. | |
1404 | ||
1405 | config SYSCTL_ARCH_UNALIGN_ALLOW | |
1406 | bool | |
1407 | help | |
1408 | Enable support for /proc/sys/kernel/unaligned-trap | |
1409 | Allows arches to define/use @unaligned_enabled to runtime toggle | |
1410 | the unaligned access emulation. | |
1411 | see arch/parisc/kernel/unaligned.c for reference | |
1412 | ||
657a5209 MF |
1413 | config HAVE_PCSPKR_PLATFORM |
1414 | bool | |
1415 | ||
f89b7755 AS |
1416 | # interpreter that classic socket filters depend on |
1417 | config BPF | |
1418 | bool | |
1419 | ||
6a108a14 DR |
1420 | menuconfig EXPERT |
1421 | bool "Configure standard kernel features (expert users)" | |
f505c553 JT |
1422 | # Unhide debug options, to make the on-by-default options visible |
1423 | select DEBUG_KERNEL | |
1da177e4 LT |
1424 | help |
1425 | This option allows certain base kernel options and settings | |
e8cf4e9c KK |
1426 | to be disabled or tweaked. This is for specialized |
1427 | environments which can tolerate a "non-standard" kernel. | |
1428 | Only use this if you really know what you are doing. | |
1da177e4 | 1429 | |
ae81f9e3 | 1430 | config UID16 |
6a108a14 | 1431 | bool "Enable 16-bit UID system calls" if EXPERT |
2813893f | 1432 | depends on HAVE_UID16 && MULTIUSER |
ae81f9e3 CE |
1433 | default y |
1434 | help | |
1435 | This enables the legacy 16-bit UID syscall wrappers. | |
1436 | ||
2813893f IM |
1437 | config MULTIUSER |
1438 | bool "Multiple users, groups and capabilities support" if EXPERT | |
1439 | default y | |
1440 | help | |
1441 | This option enables support for non-root users, groups and | |
1442 | capabilities. | |
1443 | ||
1444 | If you say N here, all processes will run with UID 0, GID 0, and all | |
1445 | possible capabilities. Saying N here also compiles out support for | |
1446 | system calls related to UIDs, GIDs, and capabilities, such as setuid, | |
1447 | setgid, and capset. | |
1448 | ||
1449 | If unsure, say Y here. | |
1450 | ||
f6187769 FF |
1451 | config SGETMASK_SYSCALL |
1452 | bool "sgetmask/ssetmask syscalls support" if EXPERT | |
a687a533 | 1453 | def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH |
a7f7f624 | 1454 | help |
f6187769 FF |
1455 | sys_sgetmask and sys_ssetmask are obsolete system calls |
1456 | no longer supported in libc but still enabled by default in some | |
1457 | architectures. | |
1458 | ||
1459 | If unsure, leave the default option here. | |
1460 | ||
6af9f7bf FF |
1461 | config SYSFS_SYSCALL |
1462 | bool "Sysfs syscall support" if EXPERT | |
1463 | default y | |
a7f7f624 | 1464 | help |
6af9f7bf FF |
1465 | sys_sysfs is an obsolete system call no longer supported in libc. |
1466 | Note that disabling this option is more secure but might break | |
1467 | compatibility with some systems. | |
1468 | ||
1469 | If unsure say Y here. | |
1470 | ||
d1b069f5 RD |
1471 | config FHANDLE |
1472 | bool "open by fhandle syscalls" if EXPERT | |
1473 | select EXPORTFS | |
1474 | default y | |
1475 | help | |
1476 | If you say Y here, a user level program will be able to map | |
1477 | file names to handle and then later use the handle for | |
1478 | different file system operations. This is useful in implementing | |
1479 | userspace file servers, which now track files using handles instead | |
1480 | of names. The handle would remain the same even if file names | |
1481 | get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) | |
1482 | syscalls. | |
1483 | ||
baa73d9e NP |
1484 | config POSIX_TIMERS |
1485 | bool "Posix Clocks & timers" if EXPERT | |
1486 | default y | |
1487 | help | |
1488 | This includes native support for POSIX timers to the kernel. | |
1489 | Some embedded systems have no use for them and therefore they | |
1490 | can be configured out to reduce the size of the kernel image. | |
1491 | ||
1492 | When this option is disabled, the following syscalls won't be | |
1493 | available: timer_create, timer_gettime: timer_getoverrun, | |
1494 | timer_settime, timer_delete, clock_adjtime, getitimer, | |
1495 | setitimer, alarm. Furthermore, the clock_settime, clock_gettime, | |
1496 | clock_getres and clock_nanosleep syscalls will be limited to | |
1497 | CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. | |
1498 | ||
1499 | If unsure say y. | |
1500 | ||
d59745ce MM |
1501 | config PRINTK |
1502 | default y | |
6a108a14 | 1503 | bool "Enable support for printk" if EXPERT |
74876a98 | 1504 | select IRQ_WORK |
d59745ce MM |
1505 | help |
1506 | This option enables normal printk support. Removing it | |
1507 | eliminates most of the message strings from the kernel image | |
1508 | and makes the kernel more or less silent. As this makes it | |
1509 | very difficult to diagnose system problems, saying N here is | |
1510 | strongly discouraged. | |
1511 | ||
42a0bb3f PM |
1512 | config PRINTK_NMI |
1513 | def_bool y | |
1514 | depends on PRINTK | |
1515 | depends on HAVE_NMI | |
1516 | ||
c8538a7a | 1517 | config BUG |
6a108a14 | 1518 | bool "BUG() support" if EXPERT |
c8538a7a MM |
1519 | default y |
1520 | help | |
e8cf4e9c KK |
1521 | Disabling this option eliminates support for BUG and WARN, reducing |
1522 | the size of your kernel image and potentially quietly ignoring | |
1523 | numerous fatal conditions. You should only consider disabling this | |
1524 | option for embedded systems with no facilities for reporting errors. | |
1525 | Just say Y. | |
c8538a7a | 1526 | |
708e9a79 | 1527 | config ELF_CORE |
046d662f | 1528 | depends on COREDUMP |
708e9a79 | 1529 | default y |
6a108a14 | 1530 | bool "Enable ELF core dumps" if EXPERT |
708e9a79 MM |
1531 | help |
1532 | Enable support for generating core dumps. Disabling saves about 4k. | |
1533 | ||
8761f1ab | 1534 | |
e5e1d3cb | 1535 | config PCSPKR_PLATFORM |
6a108a14 | 1536 | bool "Enable PC-Speaker support" if EXPERT |
8761f1ab | 1537 | depends on HAVE_PCSPKR_PLATFORM |
15f304b6 | 1538 | select I8253_LOCK |
e5e1d3cb SS |
1539 | default y |
1540 | help | |
e8cf4e9c KK |
1541 | This option allows to disable the internal PC-Speaker |
1542 | support, saving some memory. | |
e5e1d3cb | 1543 | |
1da177e4 LT |
1544 | config BASE_FULL |
1545 | default y | |
6a108a14 | 1546 | bool "Enable full-sized data structures for core" if EXPERT |
1da177e4 LT |
1547 | help |
1548 | Disabling this option reduces the size of miscellaneous core | |
1549 | kernel data structures. This saves memory on small machines, | |
1550 | but may reduce performance. | |
1551 | ||
1552 | config FUTEX | |
6a108a14 | 1553 | bool "Enable futex support" if EXPERT |
1da177e4 | 1554 | default y |
bc2eecd7 | 1555 | imply RT_MUTEXES |
1da177e4 LT |
1556 | help |
1557 | Disabling this option will cause the kernel to be built without | |
1558 | support for "fast userspace mutexes". The resulting kernel may not | |
1559 | run glibc-based applications correctly. | |
1560 | ||
bc2eecd7 NP |
1561 | config FUTEX_PI |
1562 | bool | |
1563 | depends on FUTEX && RT_MUTEXES | |
1564 | default y | |
1565 | ||
03b8c7b6 HC |
1566 | config HAVE_FUTEX_CMPXCHG |
1567 | bool | |
62b4d204 | 1568 | depends on FUTEX |
03b8c7b6 HC |
1569 | help |
1570 | Architectures should select this if futex_atomic_cmpxchg_inatomic() | |
1571 | is implemented and always working. This removes a couple of runtime | |
1572 | checks. | |
1573 | ||
1da177e4 | 1574 | config EPOLL |
6a108a14 | 1575 | bool "Enable eventpoll support" if EXPERT |
1da177e4 LT |
1576 | default y |
1577 | help | |
1578 | Disabling this option will cause the kernel to be built without | |
1579 | support for epoll family of system calls. | |
1580 | ||
fba2afaa | 1581 | config SIGNALFD |
6a108a14 | 1582 | bool "Enable signalfd() system call" if EXPERT |
fba2afaa DL |
1583 | default y |
1584 | help | |
1585 | Enable the signalfd() system call that allows to receive signals | |
1586 | on a file descriptor. | |
1587 | ||
1588 | If unsure, say Y. | |
1589 | ||
b215e283 | 1590 | config TIMERFD |
6a108a14 | 1591 | bool "Enable timerfd() system call" if EXPERT |
b215e283 DL |
1592 | default y |
1593 | help | |
1594 | Enable the timerfd() system call that allows to receive timer | |
1595 | events on a file descriptor. | |
1596 | ||
1597 | If unsure, say Y. | |
1598 | ||
e1ad7468 | 1599 | config EVENTFD |
6a108a14 | 1600 | bool "Enable eventfd() system call" if EXPERT |
e1ad7468 DL |
1601 | default y |
1602 | help | |
1603 | Enable the eventfd() system call that allows to receive both | |
1604 | kernel notification (ie. KAIO) or userspace notifications. | |
1605 | ||
1606 | If unsure, say Y. | |
1607 | ||
1da177e4 | 1608 | config SHMEM |
6a108a14 | 1609 | bool "Use full shmem filesystem" if EXPERT |
1da177e4 LT |
1610 | default y |
1611 | depends on MMU | |
1612 | help | |
1613 | The shmem is an internal filesystem used to manage shared memory. | |
1614 | It is backed by swap and manages resource limits. It is also exported | |
1615 | to userspace as tmpfs if TMPFS is enabled. Disabling this | |
1616 | option replaces shmem and tmpfs with the much simpler ramfs code, | |
1617 | which may be appropriate on small systems without swap. | |
1618 | ||
ebf3f09c | 1619 | config AIO |
6a108a14 | 1620 | bool "Enable AIO support" if EXPERT |
ebf3f09c TP |
1621 | default y |
1622 | help | |
1623 | This option enables POSIX asynchronous I/O which may by used | |
657a5209 MF |
1624 | by some high performance threaded applications. Disabling |
1625 | this option saves about 7k. | |
1626 | ||
2b188cc1 JA |
1627 | config IO_URING |
1628 | bool "Enable IO uring support" if EXPERT | |
561fb04a | 1629 | select IO_WQ |
2b188cc1 JA |
1630 | default y |
1631 | help | |
1632 | This option enables support for the io_uring interface, enabling | |
1633 | applications to submit and complete IO through submission and | |
1634 | completion rings that are shared between the kernel and application. | |
1635 | ||
d3ac21ca JT |
1636 | config ADVISE_SYSCALLS |
1637 | bool "Enable madvise/fadvise syscalls" if EXPERT | |
1638 | default y | |
1639 | help | |
1640 | This option enables the madvise and fadvise syscalls, used by | |
1641 | applications to advise the kernel about their future memory or file | |
1642 | usage, improving performance. If building an embedded system where no | |
1643 | applications use these syscalls, you can disable this option to save | |
1644 | space. | |
1645 | ||
5a281062 AA |
1646 | config HAVE_ARCH_USERFAULTFD_WP |
1647 | bool | |
1648 | help | |
1649 | Arch has userfaultfd write protection support | |
1650 | ||
7677f7fd AR |
1651 | config HAVE_ARCH_USERFAULTFD_MINOR |
1652 | bool | |
1653 | help | |
1654 | Arch has userfaultfd minor fault support | |
1655 | ||
5b25b13a MD |
1656 | config MEMBARRIER |
1657 | bool "Enable membarrier() system call" if EXPERT | |
1658 | default y | |
1659 | help | |
1660 | Enable the membarrier() system call that allows issuing memory | |
1661 | barriers across all running threads, which can be used to distribute | |
1662 | the cost of user-space memory barriers asymmetrically by transforming | |
1663 | pairs of memory barriers into pairs consisting of membarrier() and a | |
1664 | compiler barrier. | |
1665 | ||
1666 | If unsure, say Y. | |
1667 | ||
d1b069f5 | 1668 | config KALLSYMS |
e8cf4e9c KK |
1669 | bool "Load all symbols for debugging/ksymoops" if EXPERT |
1670 | default y | |
1671 | help | |
1672 | Say Y here to let the kernel print out symbolic crash information and | |
1673 | symbolic stack backtraces. This increases the size of the kernel | |
1674 | somewhat, as all symbols have to be loaded into the kernel image. | |
d1b069f5 RD |
1675 | |
1676 | config KALLSYMS_ALL | |
1677 | bool "Include all symbols in kallsyms" | |
1678 | depends on DEBUG_KERNEL && KALLSYMS | |
1679 | help | |
e8cf4e9c KK |
1680 | Normally kallsyms only contains the symbols of functions for nicer |
1681 | OOPS messages and backtraces (i.e., symbols from the text and inittext | |
1682 | sections). This is sufficient for most cases. And only in very rare | |
1683 | cases (e.g., when a debugger is used) all symbols are required (e.g., | |
1684 | names of variables from the data sections, etc). | |
d1b069f5 | 1685 | |
e8cf4e9c KK |
1686 | This option makes sure that all symbols are loaded into the kernel |
1687 | image (i.e., symbols from all sections) in cost of increased kernel | |
1688 | size (depending on the kernel configuration, it may be 300KiB or | |
1689 | something like this). | |
d1b069f5 | 1690 | |
e8cf4e9c | 1691 | Say N unless you really need all symbols. |
d1b069f5 RD |
1692 | |
1693 | config KALLSYMS_ABSOLUTE_PERCPU | |
1694 | bool | |
1695 | depends on KALLSYMS | |
1696 | default X86_64 && SMP | |
1697 | ||
1698 | config KALLSYMS_BASE_RELATIVE | |
1699 | bool | |
1700 | depends on KALLSYMS | |
a687a533 | 1701 | default !IA64 |
d1b069f5 RD |
1702 | help |
1703 | Instead of emitting them as absolute values in the native word size, | |
1704 | emit the symbol references in the kallsyms table as 32-bit entries, | |
1705 | each containing a relative value in the range [base, base + U32_MAX] | |
1706 | or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either | |
1707 | an absolute value in the range [0, S32_MAX] or a relative value in the | |
1708 | range [base, base + S32_MAX], where base is the lowest relative symbol | |
1709 | address encountered in the image. | |
1710 | ||
1711 | On 64-bit builds, this reduces the size of the address table by 50%, | |
1712 | but more importantly, it results in entries whose values are build | |
1713 | time constants, and no relocation pass is required at runtime to fix | |
1714 | up the entries based on the runtime load address of the kernel. | |
1715 | ||
1716 | # end of the "standard kernel features (expert users)" menu | |
1717 | ||
1718 | # syscall, maps, verifier | |
fc611f47 | 1719 | |
d1b069f5 RD |
1720 | config USERFAULTFD |
1721 | bool "Enable userfaultfd() system call" | |
d1b069f5 RD |
1722 | depends on MMU |
1723 | help | |
1724 | Enable the userfaultfd() system call that allows to intercept and | |
1725 | handle page faults in userland. | |
1726 | ||
3ccfebed MD |
1727 | config ARCH_HAS_MEMBARRIER_CALLBACKS |
1728 | bool | |
1729 | ||
70216e18 MD |
1730 | config ARCH_HAS_MEMBARRIER_SYNC_CORE |
1731 | bool | |
1732 | ||
bfe3911a CW |
1733 | config KCMP |
1734 | bool "Enable kcmp() system call" if EXPERT | |
1735 | help | |
1736 | Enable the kernel resource comparison system call. It provides | |
1737 | user-space with the ability to compare two processes to see if they | |
1738 | share a common resource, such as a file descriptor or even virtual | |
1739 | memory space. | |
1740 | ||
1741 | If unsure, say N. | |
1742 | ||
d7822b1e MD |
1743 | config RSEQ |
1744 | bool "Enable rseq() system call" if EXPERT | |
1745 | default y | |
1746 | depends on HAVE_RSEQ | |
1747 | select MEMBARRIER | |
1748 | help | |
1749 | Enable the restartable sequences system call. It provides a | |
1750 | user-space cache for the current CPU number value, which | |
1751 | speeds up getting the current CPU number from user-space, | |
1752 | as well as an ABI to speed up user-space operations on | |
1753 | per-CPU data. | |
1754 | ||
1755 | If unsure, say Y. | |
1756 | ||
1757 | config DEBUG_RSEQ | |
1758 | default n | |
1759 | bool "Enabled debugging of rseq() system call" if EXPERT | |
1760 | depends on RSEQ && DEBUG_KERNEL | |
1761 | help | |
1762 | Enable extra debugging checks for the rseq system call. | |
1763 | ||
1764 | If unsure, say N. | |
1765 | ||
6befe5f6 RD |
1766 | config EMBEDDED |
1767 | bool "Embedded system" | |
1768 | select EXPERT | |
1769 | help | |
1770 | This option should be enabled if compiling the kernel for | |
1771 | an embedded system so certain expert options are available | |
1772 | for configuration. | |
1773 | ||
cdd6c482 | 1774 | config HAVE_PERF_EVENTS |
0793a61d | 1775 | bool |
018df72d MF |
1776 | help |
1777 | See tools/perf/design.txt for details. | |
0793a61d | 1778 | |
906010b2 PZ |
1779 | config PERF_USE_VMALLOC |
1780 | bool | |
1781 | help | |
1782 | See tools/perf/design.txt for details | |
1783 | ||
ad90a3de | 1784 | config PC104 |
424529fb | 1785 | bool "PC/104 support" if EXPERT |
ad90a3de WBG |
1786 | help |
1787 | Expose PC/104 form factor device drivers and options available for | |
1788 | selection and configuration. Enable this option if your target | |
1789 | machine has a PC/104 bus. | |
1790 | ||
57c0c15b | 1791 | menu "Kernel Performance Events And Counters" |
0793a61d | 1792 | |
cdd6c482 | 1793 | config PERF_EVENTS |
57c0c15b | 1794 | bool "Kernel performance events and counters" |
392d65a9 | 1795 | default y if PROFILING |
cdd6c482 | 1796 | depends on HAVE_PERF_EVENTS |
e360adbe | 1797 | select IRQ_WORK |
83fe27ea | 1798 | select SRCU |
0793a61d | 1799 | help |
57c0c15b IM |
1800 | Enable kernel support for various performance events provided |
1801 | by software and hardware. | |
0793a61d | 1802 | |
dd77038d | 1803 | Software events are supported either built-in or via the |
57c0c15b | 1804 | use of generic tracepoints. |
0793a61d | 1805 | |
57c0c15b IM |
1806 | Most modern CPUs support performance events via performance |
1807 | counter registers. These registers count the number of certain | |
0793a61d TG |
1808 | types of hw events: such as instructions executed, cachemisses |
1809 | suffered, or branches mis-predicted - without slowing down the | |
1810 | kernel or applications. These registers can also trigger interrupts | |
1811 | when a threshold number of events have passed - and can thus be | |
1812 | used to profile the code that runs on that CPU. | |
1813 | ||
57c0c15b | 1814 | The Linux Performance Event subsystem provides an abstraction of |
dd77038d | 1815 | these software and hardware event capabilities, available via a |
57c0c15b | 1816 | system call and used by the "perf" utility in tools/perf/. It |
0793a61d TG |
1817 | provides per task and per CPU counters, and it provides event |
1818 | capabilities on top of those. | |
1819 | ||
1820 | Say Y if unsure. | |
1821 | ||
906010b2 PZ |
1822 | config DEBUG_PERF_USE_VMALLOC |
1823 | default n | |
1824 | bool "Debug: use vmalloc to back perf mmap() buffers" | |
cb307113 | 1825 | depends on PERF_EVENTS && DEBUG_KERNEL && !PPC |
906010b2 PZ |
1826 | select PERF_USE_VMALLOC |
1827 | help | |
e8cf4e9c | 1828 | Use vmalloc memory to back perf mmap() buffers. |
906010b2 | 1829 | |
e8cf4e9c KK |
1830 | Mostly useful for debugging the vmalloc code on platforms |
1831 | that don't require it. | |
906010b2 | 1832 | |
e8cf4e9c | 1833 | Say N if unsure. |
906010b2 | 1834 | |
0793a61d TG |
1835 | endmenu |
1836 | ||
f8891e5e CL |
1837 | config VM_EVENT_COUNTERS |
1838 | default y | |
6a108a14 | 1839 | bool "Enable VM event counters for /proc/vmstat" if EXPERT |
f8891e5e | 1840 | help |
2aea4fb6 PJ |
1841 | VM event counters are needed for event counts to be shown. |
1842 | This option allows the disabling of the VM event counters | |
6a108a14 | 1843 | on EXPERT systems. /proc/vmstat will only show page counts |
2aea4fb6 | 1844 | if VM event counters are disabled. |
f8891e5e | 1845 | |
41ecc55b CL |
1846 | config SLUB_DEBUG |
1847 | default y | |
6a108a14 | 1848 | bool "Enable SLUB debugging support" if EXPERT |
f6acb635 | 1849 | depends on SLUB && SYSFS |
78869146 | 1850 | select STACKDEPOT if STACKTRACE_SUPPORT |
41ecc55b CL |
1851 | help |
1852 | SLUB has extensive debug support features. Disabling these can | |
1853 | result in significant savings in code size. This also disables | |
1854 | SLUB sysfs support. /sys/slab will not exist and there will be | |
1855 | no support for cache validation etc. | |
1856 | ||
b943c460 RD |
1857 | config COMPAT_BRK |
1858 | bool "Disable heap randomization" | |
1859 | default y | |
1860 | help | |
1861 | Randomizing heap placement makes heap exploits harder, but it | |
1862 | also breaks ancient binaries (including anything libc5 based). | |
1863 | This option changes the bootup default to heap randomization | |
692105b8 | 1864 | disabled, and can be overridden at runtime by setting |
b943c460 RD |
1865 | /proc/sys/kernel/randomize_va_space to 2. |
1866 | ||
1867 | On non-ancient distros (post-2000 ones) N is usually a safe choice. | |
1868 | ||
81819f0f CL |
1869 | choice |
1870 | prompt "Choose SLAB allocator" | |
a0acd820 | 1871 | default SLUB |
81819f0f CL |
1872 | help |
1873 | This option allows to select a slab allocator. | |
1874 | ||
1875 | config SLAB | |
1876 | bool "SLAB" | |
04385fc5 | 1877 | select HAVE_HARDENED_USERCOPY_ALLOCATOR |
81819f0f CL |
1878 | help |
1879 | The regular slab allocator that is established and known to work | |
34013886 | 1880 | well in all environments. It organizes cache hot objects in |
02f56210 | 1881 | per cpu and per node queues. |
81819f0f CL |
1882 | |
1883 | config SLUB | |
81819f0f | 1884 | bool "SLUB (Unqueued Allocator)" |
ed18adc1 | 1885 | select HAVE_HARDENED_USERCOPY_ALLOCATOR |
81819f0f CL |
1886 | help |
1887 | SLUB is a slab allocator that minimizes cache line usage | |
1888 | instead of managing queues of cached objects (SLAB approach). | |
1889 | Per cpu caching is realized using slabs of objects instead | |
1890 | of queues of objects. SLUB can use memory efficiently | |
02f56210 SA |
1891 | and has enhanced diagnostics. SLUB is the default choice for |
1892 | a slab allocator. | |
81819f0f CL |
1893 | |
1894 | config SLOB | |
6a108a14 | 1895 | depends on EXPERT |
81819f0f CL |
1896 | bool "SLOB (Simple Allocator)" |
1897 | help | |
37291458 MM |
1898 | SLOB replaces the stock allocator with a drastically simpler |
1899 | allocator. SLOB is generally more space efficient but | |
1900 | does not perform as well on large systems. | |
81819f0f CL |
1901 | |
1902 | endchoice | |
1903 | ||
7660a6fd KC |
1904 | config SLAB_MERGE_DEFAULT |
1905 | bool "Allow slab caches to be merged" | |
1906 | default y | |
1907 | help | |
1908 | For reduced kernel memory fragmentation, slab caches can be | |
1909 | merged when they share the same size and other characteristics. | |
1910 | This carries a risk of kernel heap overflows being able to | |
1911 | overwrite objects from merged caches (and more easily control | |
1912 | cache layout), which makes such heap attacks easier to exploit | |
1913 | by attackers. By keeping caches unmerged, these kinds of exploits | |
1914 | can usually only damage objects in the same cache. To disable | |
1915 | merging at runtime, "slab_nomerge" can be passed on the kernel | |
1916 | command line. | |
1917 | ||
c7ce4f60 | 1918 | config SLAB_FREELIST_RANDOM |
3404be67 | 1919 | bool "Randomize slab freelist" |
210e7a43 | 1920 | depends on SLAB || SLUB |
c7ce4f60 | 1921 | help |
210e7a43 | 1922 | Randomizes the freelist order used on creating new pages. This |
c7ce4f60 TG |
1923 | security feature reduces the predictability of the kernel slab |
1924 | allocator against heap overflows. | |
1925 | ||
2482ddec KC |
1926 | config SLAB_FREELIST_HARDENED |
1927 | bool "Harden slab freelist metadata" | |
3404be67 | 1928 | depends on SLAB || SLUB |
2482ddec KC |
1929 | help |
1930 | Many kernel heap attacks try to target slab cache metadata and | |
1931 | other infrastructure. This options makes minor performance | |
92bae787 | 1932 | sacrifices to harden the kernel slab allocator against common |
3404be67 KC |
1933 | freelist exploit methods. Some slab implementations have more |
1934 | sanity-checking than others. This option is most effective with | |
1935 | CONFIG_SLUB. | |
2482ddec | 1936 | |
e900a918 DW |
1937 | config SHUFFLE_PAGE_ALLOCATOR |
1938 | bool "Page allocator randomization" | |
1939 | default SLAB_FREELIST_RANDOM && ACPI_NUMA | |
1940 | help | |
1941 | Randomization of the page allocator improves the average | |
1942 | utilization of a direct-mapped memory-side-cache. See section | |
1943 | 5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI | |
1944 | 6.2a specification for an example of how a platform advertises | |
1945 | the presence of a memory-side-cache. There are also incidental | |
1946 | security benefits as it reduces the predictability of page | |
1947 | allocations to compliment SLAB_FREELIST_RANDOM, but the | |
1948 | default granularity of shuffling on the "MAX_ORDER - 1" i.e, | |
1949 | 10th order of pages is selected based on cache utilization | |
1950 | benefits on x86. | |
1951 | ||
1952 | While the randomization improves cache utilization it may | |
1953 | negatively impact workloads on platforms without a cache. For | |
1954 | this reason, by default, the randomization is enabled only | |
1955 | after runtime detection of a direct-mapped memory-side-cache. | |
1956 | Otherwise, the randomization may be force enabled with the | |
1957 | 'page_alloc.shuffle' kernel command line parameter. | |
1958 | ||
1959 | Say Y if unsure. | |
1960 | ||
345c905d JK |
1961 | config SLUB_CPU_PARTIAL |
1962 | default y | |
b39ffbf8 | 1963 | depends on SLUB && SMP |
345c905d JK |
1964 | bool "SLUB per cpu partial cache" |
1965 | help | |
92bae787 | 1966 | Per cpu partial caches accelerate objects allocation and freeing |
345c905d JK |
1967 | that is local to a processor at the price of more indeterminism |
1968 | in the latency of the free. On overflow these caches will be cleared | |
1969 | which requires the taking of locks that may cause latency spikes. | |
1970 | Typically one would choose no for a realtime system. | |
1971 | ||
ea637639 JZ |
1972 | config MMAP_ALLOW_UNINITIALIZED |
1973 | bool "Allow mmapped anonymous memory to be uninitialized" | |
6a108a14 | 1974 | depends on EXPERT && !MMU |
ea637639 JZ |
1975 | default n |
1976 | help | |
1977 | Normally, and according to the Linux spec, anonymous memory obtained | |
3903bf94 | 1978 | from mmap() has its contents cleared before it is passed to |
ea637639 JZ |
1979 | userspace. Enabling this config option allows you to request that |
1980 | mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus | |
1981 | providing a huge performance boost. If this option is not enabled, | |
1982 | then the flag will be ignored. | |
1983 | ||
1984 | This is taken advantage of by uClibc's malloc(), and also by | |
1985 | ELF-FDPIC binfmt's brk and stack allocator. | |
1986 | ||
1987 | Because of the obvious security issues, this option should only be | |
1988 | enabled on embedded devices where you control what is run in | |
1989 | userspace. Since that isn't generally a problem on no-MMU systems, | |
1990 | it is normally safe to say Y here. | |
1991 | ||
dd19d293 | 1992 | See Documentation/admin-guide/mm/nommu-mmap.rst for more information. |
ea637639 | 1993 | |
091f6e26 DH |
1994 | config SYSTEM_DATA_VERIFICATION |
1995 | def_bool n | |
1996 | select SYSTEM_TRUSTED_KEYRING | |
1997 | select KEYS | |
1998 | select CRYPTO | |
d43de6c7 | 1999 | select CRYPTO_RSA |
091f6e26 DH |
2000 | select ASYMMETRIC_KEY_TYPE |
2001 | select ASYMMETRIC_PUBLIC_KEY_SUBTYPE | |
091f6e26 DH |
2002 | select ASN1 |
2003 | select OID_REGISTRY | |
2004 | select X509_CERTIFICATE_PARSER | |
2005 | select PKCS7_MESSAGE_PARSER | |
82c04ff8 | 2006 | help |
091f6e26 DH |
2007 | Provide PKCS#7 message verification using the contents of the system |
2008 | trusted keyring to provide public keys. This then can be used for | |
2009 | module verification, kexec image verification and firmware blob | |
2010 | verification. | |
82c04ff8 | 2011 | |
125e5645 | 2012 | config PROFILING |
b309a294 | 2013 | bool "Profiling support" |
125e5645 MD |
2014 | help |
2015 | Say Y here to enable the extended profiling support mechanisms used | |
f8408264 | 2016 | by profilers. |
125e5645 | 2017 | |
5f87f112 IM |
2018 | # |
2019 | # Place an empty function call at each tracepoint site. Can be | |
2020 | # dynamically changed for a probe function. | |
2021 | # | |
97e1c18e | 2022 | config TRACEPOINTS |
5f87f112 | 2023 | bool |
97e1c18e | 2024 | |
1da177e4 LT |
2025 | endmenu # General setup |
2026 | ||
1572497c CH |
2027 | source "arch/Kconfig" |
2028 | ||
ae81f9e3 | 2029 | config RT_MUTEXES |
6341e62b | 2030 | bool |
ae81f9e3 | 2031 | |
1da177e4 LT |
2032 | config BASE_SMALL |
2033 | int | |
2034 | default 0 if BASE_FULL | |
2035 | default 1 if !BASE_FULL | |
2036 | ||
c8424e77 TJB |
2037 | config MODULE_SIG_FORMAT |
2038 | def_bool n | |
2039 | select SYSTEM_DATA_VERIFICATION | |
2040 | ||
66da5733 | 2041 | menuconfig MODULES |
1da177e4 | 2042 | bool "Enable loadable module support" |
6dd85ff1 | 2043 | modules |
1da177e4 LT |
2044 | help |
2045 | Kernel modules are small pieces of compiled code which can | |
2046 | be inserted in the running kernel, rather than being | |
2047 | permanently built into the kernel. You use the "modprobe" | |
2048 | tool to add (and sometimes remove) them. If you say Y here, | |
2049 | many parts of the kernel can be built as modules (by | |
2050 | answering M instead of Y where indicated): this is most | |
2051 | useful for infrequently used options which are not required | |
2052 | for booting. For more information, see the man pages for | |
2053 | modprobe, lsmod, modinfo, insmod and rmmod. | |
2054 | ||
2055 | If you say Y here, you will need to run "make | |
2056 | modules_install" to put the modules under /lib/modules/ | |
2057 | where modprobe can find them (you may need to be root to do | |
2058 | this). | |
2059 | ||
2060 | If unsure, say Y. | |
2061 | ||
0b0de144 RD |
2062 | if MODULES |
2063 | ||
826e4506 LT |
2064 | config MODULE_FORCE_LOAD |
2065 | bool "Forced module loading" | |
826e4506 LT |
2066 | default n |
2067 | help | |
91e37a79 RR |
2068 | Allow loading of modules without version information (ie. modprobe |
2069 | --force). Forced module loading sets the 'F' (forced) taint flag and | |
2070 | is usually a really bad idea. | |
826e4506 | 2071 | |
1da177e4 LT |
2072 | config MODULE_UNLOAD |
2073 | bool "Module unloading" | |
1da177e4 LT |
2074 | help |
2075 | Without this option you will not be able to unload any | |
2076 | modules (note that some modules may not be unloadable | |
f7f5b675 DV |
2077 | anyway), which makes your kernel smaller, faster |
2078 | and simpler. If unsure, say Y. | |
1da177e4 LT |
2079 | |
2080 | config MODULE_FORCE_UNLOAD | |
2081 | bool "Forced module unloading" | |
19c92399 | 2082 | depends on MODULE_UNLOAD |
1da177e4 LT |
2083 | help |
2084 | This option allows you to force a module to unload, even if the | |
2085 | kernel believes it is unsafe: the kernel will remove the module | |
2086 | without waiting for anyone to stop using it (using the -f option to | |
2087 | rmmod). This is mainly for kernel developers and desperate users. | |
2088 | If unsure, say N. | |
2089 | ||
1da177e4 | 2090 | config MODVERSIONS |
0d541643 | 2091 | bool "Module versioning support" |
1da177e4 LT |
2092 | help |
2093 | Usually, you have to use modules compiled with your kernel. | |
2094 | Saying Y here makes it sometimes possible to use modules | |
2095 | compiled for different kernels, by adding enough information | |
2096 | to the modules to (hopefully) spot any changes which would | |
2097 | make them incompatible with the kernel you are running. If | |
2098 | unsure, say N. | |
2099 | ||
2ff2b7ec MY |
2100 | config ASM_MODVERSIONS |
2101 | bool | |
2102 | default HAVE_ASM_MODVERSIONS && MODVERSIONS | |
2103 | help | |
2104 | This enables module versioning for exported symbols also from | |
2105 | assembly. This can be enabled only when the target architecture | |
2106 | supports it. | |
2107 | ||
56067812 AB |
2108 | config MODULE_REL_CRCS |
2109 | bool | |
2110 | depends on MODVERSIONS | |
2111 | ||
1da177e4 LT |
2112 | config MODULE_SRCVERSION_ALL |
2113 | bool "Source checksum for all modules" | |
1da177e4 LT |
2114 | help |
2115 | Modules which contain a MODULE_VERSION get an extra "srcversion" | |
2116 | field inserted into their modinfo section, which contains a | |
2117 | sum of the source files which made it. This helps maintainers | |
2118 | see exactly which source was used to build a module (since | |
2119 | others sometimes change the module source without updating | |
2120 | the version). With this option, such a "srcversion" field | |
2121 | will be created for all modules. If unsure, say N. | |
2122 | ||
106a4ee2 RR |
2123 | config MODULE_SIG |
2124 | bool "Module signature verification" | |
c8424e77 | 2125 | select MODULE_SIG_FORMAT |
106a4ee2 RR |
2126 | help |
2127 | Check modules for valid signatures upon load: the signature | |
2128 | is simply appended to the module. For more information see | |
cbdc8217 | 2129 | <file:Documentation/admin-guide/module-signing.rst>. |
106a4ee2 | 2130 | |
228c37ff DH |
2131 | Note that this option adds the OpenSSL development packages as a |
2132 | kernel build dependency so that the signing tool can use its crypto | |
2133 | library. | |
2134 | ||
49fcf732 DH |
2135 | You should enable this option if you wish to use either |
2136 | CONFIG_SECURITY_LOCKDOWN_LSM or lockdown functionality imposed via | |
2137 | another LSM - otherwise unsigned modules will be loadable regardless | |
2138 | of the lockdown policy. | |
2139 | ||
ea0b6dcf DH |
2140 | !!!WARNING!!! If you enable this option, you MUST make sure that the |
2141 | module DOES NOT get stripped after being signed. This includes the | |
2142 | debuginfo strip done by some packagers (such as rpmbuild) and | |
2143 | inclusion into an initramfs that wants the module size reduced. | |
2144 | ||
106a4ee2 RR |
2145 | config MODULE_SIG_FORCE |
2146 | bool "Require modules to be validly signed" | |
2147 | depends on MODULE_SIG | |
2148 | help | |
2149 | Reject unsigned modules or signed modules for which we don't have a | |
2150 | key. Without this, such modules will simply taint the kernel. | |
ea0b6dcf | 2151 | |
d9d8d7ed MM |
2152 | config MODULE_SIG_ALL |
2153 | bool "Automatically sign all modules" | |
2154 | default y | |
0165f4ca | 2155 | depends on MODULE_SIG || IMA_APPRAISE_MODSIG |
d9d8d7ed MM |
2156 | help |
2157 | Sign all modules during make modules_install. Without this option, | |
2158 | modules must be signed manually, using the scripts/sign-file tool. | |
2159 | ||
2160 | comment "Do not forget to sign required modules with scripts/sign-file" | |
2161 | depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL | |
2162 | ||
ea0b6dcf DH |
2163 | choice |
2164 | prompt "Which hash algorithm should modules be signed with?" | |
0165f4ca | 2165 | depends on MODULE_SIG || IMA_APPRAISE_MODSIG |
ea0b6dcf DH |
2166 | help |
2167 | This determines which sort of hashing algorithm will be used during | |
2168 | signature generation. This algorithm _must_ be built into the kernel | |
2169 | directly so that signature verification can take place. It is not | |
2170 | possible to load a signed module containing the algorithm to check | |
2171 | the signature on that module. | |
2172 | ||
2173 | config MODULE_SIG_SHA1 | |
2174 | bool "Sign modules with SHA-1" | |
2175 | select CRYPTO_SHA1 | |
2176 | ||
2177 | config MODULE_SIG_SHA224 | |
2178 | bool "Sign modules with SHA-224" | |
2179 | select CRYPTO_SHA256 | |
2180 | ||
2181 | config MODULE_SIG_SHA256 | |
2182 | bool "Sign modules with SHA-256" | |
2183 | select CRYPTO_SHA256 | |
2184 | ||
2185 | config MODULE_SIG_SHA384 | |
2186 | bool "Sign modules with SHA-384" | |
2187 | select CRYPTO_SHA512 | |
2188 | ||
2189 | config MODULE_SIG_SHA512 | |
2190 | bool "Sign modules with SHA-512" | |
2191 | select CRYPTO_SHA512 | |
2192 | ||
2193 | endchoice | |
2194 | ||
22753674 MM |
2195 | config MODULE_SIG_HASH |
2196 | string | |
0165f4ca | 2197 | depends on MODULE_SIG || IMA_APPRAISE_MODSIG |
22753674 MM |
2198 | default "sha1" if MODULE_SIG_SHA1 |
2199 | default "sha224" if MODULE_SIG_SHA224 | |
2200 | default "sha256" if MODULE_SIG_SHA256 | |
2201 | default "sha384" if MODULE_SIG_SHA384 | |
2202 | default "sha512" if MODULE_SIG_SHA512 | |
2203 | ||
d4bbe942 MY |
2204 | choice |
2205 | prompt "Module compression mode" | |
beb50df3 | 2206 | help |
d4bbe942 MY |
2207 | This option allows you to choose the algorithm which will be used to |
2208 | compress modules when 'make modules_install' is run. (or, you can | |
2209 | choose to not compress modules at all.) | |
beb50df3 | 2210 | |
d4bbe942 MY |
2211 | External modules will also be compressed in the same way during the |
2212 | installation. | |
beb50df3 | 2213 | |
d4bbe942 MY |
2214 | For modules inside an initrd or initramfs, it's more efficient to |
2215 | compress the whole initrd or initramfs instead. | |
beb50df3 | 2216 | |
d4bbe942 | 2217 | This is fully compatible with signed modules. |
beb50df3 | 2218 | |
d4bbe942 MY |
2219 | Please note that the tool used to load modules needs to support the |
2220 | corresponding algorithm. module-init-tools MAY support gzip, and kmod | |
c3d7ef37 | 2221 | MAY support gzip, xz and zstd. |
beb50df3 | 2222 | |
d4bbe942 MY |
2223 | Your build system needs to provide the appropriate compression tool |
2224 | to compress the modules. | |
b6c09b51 | 2225 | |
d4bbe942 | 2226 | If in doubt, select 'None'. |
beb50df3 | 2227 | |
d4bbe942 MY |
2228 | config MODULE_COMPRESS_NONE |
2229 | bool "None" | |
beb50df3 | 2230 | help |
d4bbe942 MY |
2231 | Do not compress modules. The installed modules are suffixed |
2232 | with .ko. | |
beb50df3 BJ |
2233 | |
2234 | config MODULE_COMPRESS_GZIP | |
2235 | bool "GZIP" | |
d4bbe942 MY |
2236 | help |
2237 | Compress modules with GZIP. The installed modules are suffixed | |
2238 | with .ko.gz. | |
beb50df3 BJ |
2239 | |
2240 | config MODULE_COMPRESS_XZ | |
2241 | bool "XZ" | |
d4bbe942 MY |
2242 | help |
2243 | Compress modules with XZ. The installed modules are suffixed | |
2244 | with .ko.xz. | |
beb50df3 | 2245 | |
c3d7ef37 PG |
2246 | config MODULE_COMPRESS_ZSTD |
2247 | bool "ZSTD" | |
2248 | help | |
2249 | Compress modules with ZSTD. The installed modules are suffixed | |
2250 | with .ko.zst. | |
beb50df3 BJ |
2251 | |
2252 | endchoice | |
2253 | ||
3d52ec5e MM |
2254 | config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS |
2255 | bool "Allow loading of modules with missing namespace imports" | |
2256 | help | |
2257 | Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in | |
2258 | a namespace. A module that makes use of a symbol exported with such a | |
2259 | namespace is required to import the namespace via MODULE_IMPORT_NS(). | |
2260 | There is no technical reason to enforce correct namespace imports, | |
2261 | but it creates consistency between symbols defining namespaces and | |
2262 | users importing namespaces they make use of. This option relaxes this | |
2263 | requirement and lifts the enforcement when loading a module. | |
2264 | ||
2265 | If unsure, say N. | |
2266 | ||
17652f42 RV |
2267 | config MODPROBE_PATH |
2268 | string "Path to modprobe binary" | |
2269 | default "/sbin/modprobe" | |
2270 | help | |
2271 | When kernel code requests a module, it does so by calling | |
2272 | the "modprobe" userspace utility. This option allows you to | |
2273 | set the path where that binary is found. This can be changed | |
2274 | at runtime via the sysctl file | |
2275 | /proc/sys/kernel/modprobe. Setting this to the empty string | |
2276 | removes the kernel's ability to request modules (but | |
2277 | userspace can still load modules explicitly). | |
2278 | ||
dbacb0ef | 2279 | config TRIM_UNUSED_KSYMS |
a555bdd0 LT |
2280 | bool "Trim unused exported kernel symbols" if EXPERT |
2281 | depends on !COMPILE_TEST | |
dbacb0ef NP |
2282 | help |
2283 | The kernel and some modules make many symbols available for | |
2284 | other modules to use via EXPORT_SYMBOL() and variants. Depending | |
2285 | on the set of modules being selected in your kernel configuration, | |
2286 | many of those exported symbols might never be used. | |
2287 | ||
2288 | This option allows for unused exported symbols to be dropped from | |
2289 | the build. In turn, this provides the compiler more opportunities | |
2290 | (especially when using LTO) for optimizing the code and reducing | |
2291 | binary size. This might have some security advantages as well. | |
2292 | ||
f1cb637e | 2293 | If unsure, or if you need to build out-of-tree modules, say N. |
dbacb0ef | 2294 | |
1518c633 QP |
2295 | config UNUSED_KSYMS_WHITELIST |
2296 | string "Whitelist of symbols to keep in ksymtab" | |
2297 | depends on TRIM_UNUSED_KSYMS | |
2298 | help | |
2299 | By default, all unused exported symbols will be un-exported from the | |
2300 | build when TRIM_UNUSED_KSYMS is selected. | |
2301 | ||
2302 | UNUSED_KSYMS_WHITELIST allows to whitelist symbols that must be kept | |
2303 | exported at all times, even in absence of in-tree users. The value to | |
2304 | set here is the path to a text file containing the list of symbols, | |
2305 | one per line. The path can be absolute, or relative to the kernel | |
2306 | source tree. | |
2307 | ||
0b0de144 RD |
2308 | endif # MODULES |
2309 | ||
6c9692e2 PZ |
2310 | config MODULES_TREE_LOOKUP |
2311 | def_bool y | |
cf68fffb | 2312 | depends on PERF_EVENTS || TRACING || CFI_CLANG |
6c9692e2 | 2313 | |
98a79d6a RR |
2314 | config INIT_ALL_POSSIBLE |
2315 | bool | |
2316 | help | |
5f054e31 RR |
2317 | Back when each arch used to define their own cpu_online_mask and |
2318 | cpu_possible_mask, some of them chose to initialize cpu_possible_mask | |
98a79d6a RR |
2319 | with all 1s, and others with all 0s. When they were centralised, |
2320 | it was better to provide this option than to break all the archs | |
692105b8 | 2321 | and have several arch maintainers pursuing me down dark alleys. |
98a79d6a | 2322 | |
3a65dfe8 | 2323 | source "block/Kconfig" |
e98c3202 AK |
2324 | |
2325 | config PREEMPT_NOTIFIERS | |
2326 | bool | |
e260be67 | 2327 | |
16295bec SK |
2328 | config PADATA |
2329 | depends on SMP | |
2330 | bool | |
2331 | ||
4520c6a4 DH |
2332 | config ASN1 |
2333 | tristate | |
2334 | help | |
2335 | Build a simple ASN.1 grammar compiler that produces a bytecode output | |
2336 | that can be interpreted by the ASN.1 stream decoder and used to | |
2337 | inform it as to what tags are to be expected in a stream and what | |
2338 | functions to call on what tags. | |
2339 | ||
6beb0009 | 2340 | source "kernel/Kconfig.locks" |
e61938a9 | 2341 | |
0ebeea8c DB |
2342 | config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE |
2343 | bool | |
2344 | ||
e61938a9 MD |
2345 | config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE |
2346 | bool | |
1bd21c6c DB |
2347 | |
2348 | # It may be useful for an architecture to override the definitions of the | |
7303e30e DB |
2349 | # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h> |
2350 | # and the COMPAT_ variants in <linux/compat.h>, in particular to use a | |
2351 | # different calling convention for syscalls. They can also override the | |
2352 | # macros for not-implemented syscalls in kernel/sys_ni.c and | |
2353 | # kernel/time/posix-stubs.c. All these overrides need to be available in | |
2354 | # <asm/syscall_wrapper.h>. | |
1bd21c6c DB |
2355 | config ARCH_HAS_SYSCALL_WRAPPER |
2356 | def_bool n |