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ec8f24b7 | 1 | # SPDX-License-Identifier: GPL-2.0-only |
face4374 RZ |
2 | config DEFCONFIG_LIST |
3 | string | |
b2670eac | 4 | depends on !UML |
face4374 | 5 | option defconfig_list |
47f38ae0 | 6 | default "/lib/modules/$(shell,uname -r)/.config" |
face4374 | 7 | default "/etc/kernel-config" |
47f38ae0 | 8 | default "/boot/config-$(shell,uname -r)" |
2a86f661 | 9 | default "arch/$(SRCARCH)/configs/$(KBUILD_DEFCONFIG)" |
face4374 | 10 | |
8b59cd81 MY |
11 | config CC_VERSION_TEXT |
12 | string | |
13 | default "$(CC_VERSION_TEXT)" | |
14 | help | |
15 | This is used in unclear ways: | |
16 | ||
17 | - Re-run Kconfig when the compiler is updated | |
18 | The 'default' property references the environment variable, | |
19 | CC_VERSION_TEXT so it is recorded in include/config/auto.conf.cmd. | |
20 | When the compiler is updated, Kconfig will be invoked. | |
21 | ||
22 | - Ensure full rebuild when the compier is updated | |
23 | include/linux/kconfig.h contains this option in the comment line so | |
24 | fixdep adds include/config/cc/version/text.h into the auto-generated | |
25 | dependency. When the compiler is updated, syncconfig will touch it | |
26 | and then every file will be rebuilt. | |
27 | ||
a4353898 | 28 | config CC_IS_GCC |
e33ae3ed | 29 | def_bool $(success,echo "$(CC_VERSION_TEXT)" | grep -q gcc) |
a4353898 MY |
30 | |
31 | config GCC_VERSION | |
32 | int | |
fa7295ab | 33 | default $(shell,$(srctree)/scripts/gcc-version.sh $(CC)) if CC_IS_GCC |
a4353898 MY |
34 | default 0 |
35 | ||
9553d16f ADK |
36 | config LD_VERSION |
37 | int | |
38 | default $(shell,$(LD) --version | $(srctree)/scripts/ld-version.sh) | |
39 | ||
469cb737 | 40 | config CC_IS_CLANG |
e33ae3ed | 41 | def_bool $(success,echo "$(CC_VERSION_TEXT)" | grep -q clang) |
469cb737 | 42 | |
b744b43f ST |
43 | config LD_IS_LLD |
44 | def_bool $(success,$(LD) -v | head -n 1 | grep -q LLD) | |
45 | ||
469cb737 MY |
46 | config CLANG_VERSION |
47 | int | |
48 | default $(shell,$(srctree)/scripts/clang-version.sh $(CC)) | |
49 | ||
d5750cd3 NC |
50 | config LLD_VERSION |
51 | int | |
52 | default $(shell,$(srctree)/scripts/lld-version.sh $(LD)) | |
53 | ||
1a927fd3 | 54 | config CC_CAN_LINK |
9371f86e | 55 | bool |
b816b3db MY |
56 | default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m64-flag)) if 64BIT |
57 | default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m32-flag)) | |
b1183b6d MY |
58 | |
59 | config CC_CAN_LINK_STATIC | |
60 | bool | |
b816b3db MY |
61 | default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m64-flag) -static) if 64BIT |
62 | default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m32-flag) -static) | |
1a927fd3 | 63 | |
e9666d10 MY |
64 | config CC_HAS_ASM_GOTO |
65 | def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC)) | |
66 | ||
587f1701 ND |
67 | config CC_HAS_ASM_GOTO_OUTPUT |
68 | depends on CC_HAS_ASM_GOTO | |
69 | 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) | |
70 | ||
5cf896fb | 71 | config TOOLS_SUPPORT_RELR |
2d122942 | 72 | def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh) |
5cf896fb | 73 | |
eb111869 RV |
74 | config CC_HAS_ASM_INLINE |
75 | def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null) | |
76 | ||
b99b87f7 PO |
77 | config CONSTRUCTORS |
78 | bool | |
b99b87f7 | 79 | |
e360adbe PZ |
80 | config IRQ_WORK |
81 | bool | |
e360adbe | 82 | |
10916706 | 83 | config BUILDTIME_TABLE_SORT |
1dbdc6f1 DD |
84 | bool |
85 | ||
c65eacbe AL |
86 | config THREAD_INFO_IN_TASK |
87 | bool | |
88 | help | |
89 | Select this to move thread_info off the stack into task_struct. To | |
90 | make this work, an arch will need to remove all thread_info fields | |
91 | except flags and fix any runtime bugs. | |
92 | ||
c6c314a6 AL |
93 | One subtle change that will be needed is to use try_get_task_stack() |
94 | and put_task_stack() in save_thread_stack_tsk() and get_wchan(). | |
95 | ||
ff0cfc66 | 96 | menu "General setup" |
1da177e4 | 97 | |
1da177e4 LT |
98 | config BROKEN |
99 | bool | |
1da177e4 LT |
100 | |
101 | config BROKEN_ON_SMP | |
102 | bool | |
103 | depends on BROKEN || !SMP | |
104 | default y | |
105 | ||
1da177e4 LT |
106 | config INIT_ENV_ARG_LIMIT |
107 | int | |
dd673bca AB |
108 | default 32 if !UML |
109 | default 128 if UML | |
1da177e4 | 110 | help |
34ad92c2 RD |
111 | Maximum of each of the number of arguments and environment |
112 | variables passed to init from the kernel command line. | |
1da177e4 | 113 | |
4bb16672 JS |
114 | config COMPILE_TEST |
115 | bool "Compile also drivers which will not load" | |
2186209d | 116 | depends on HAS_IOMEM |
4bb16672 JS |
117 | help |
118 | Some drivers can be compiled on a different platform than they are | |
119 | intended to be run on. Despite they cannot be loaded there (or even | |
120 | when they load they cannot be used due to missing HW support), | |
121 | developers still, opposing to distributors, might want to build such | |
122 | drivers to compile-test them. | |
123 | ||
124 | If you are a developer and want to build everything available, say Y | |
125 | here. If you are a user/distributor, say N here to exclude useless | |
126 | drivers to be distributed. | |
127 | ||
d6fc9fcb MY |
128 | config UAPI_HEADER_TEST |
129 | bool "Compile test UAPI headers" | |
fcbb8461 | 130 | depends on HEADERS_INSTALL && CC_CAN_LINK |
d6fc9fcb MY |
131 | help |
132 | Compile test headers exported to user-space to ensure they are | |
133 | self-contained, i.e. compilable as standalone units. | |
134 | ||
135 | If you are a developer or tester and want to ensure the exported | |
136 | headers are self-contained, say Y here. Otherwise, choose N. | |
137 | ||
1da177e4 LT |
138 | config LOCALVERSION |
139 | string "Local version - append to kernel release" | |
140 | help | |
141 | Append an extra string to the end of your kernel version. | |
142 | This will show up when you type uname, for example. | |
143 | The string you set here will be appended after the contents of | |
144 | any files with a filename matching localversion* in your | |
145 | object and source tree, in that order. Your total string can | |
146 | be a maximum of 64 characters. | |
147 | ||
aaebf433 RA |
148 | config LOCALVERSION_AUTO |
149 | bool "Automatically append version information to the version string" | |
150 | default y | |
ac3339ba | 151 | depends on !COMPILE_TEST |
aaebf433 RA |
152 | help |
153 | This will try to automatically determine if the current tree is a | |
6e5a5420 RD |
154 | release tree by looking for git tags that belong to the current |
155 | top of tree revision. | |
aaebf433 RA |
156 | |
157 | A string of the format -gxxxxxxxx will be added to the localversion | |
6e5a5420 | 158 | if a git-based tree is found. The string generated by this will be |
aaebf433 | 159 | appended after any matching localversion* files, and after the value |
6e5a5420 | 160 | set in CONFIG_LOCALVERSION. |
aaebf433 | 161 | |
6e5a5420 RD |
162 | (The actual string used here is the first eight characters produced |
163 | by running the command: | |
164 | ||
165 | $ git rev-parse --verify HEAD | |
166 | ||
167 | which is done within the script "scripts/setlocalversion".) | |
aaebf433 | 168 | |
9afb719e | 169 | config BUILD_SALT |
e8cf4e9c KK |
170 | string "Build ID Salt" |
171 | default "" | |
172 | help | |
173 | The build ID is used to link binaries and their debug info. Setting | |
174 | this option will use the value in the calculation of the build id. | |
175 | This is mostly useful for distributions which want to ensure the | |
176 | build is unique between builds. It's safe to leave the default. | |
9afb719e | 177 | |
2e9f3bdd PA |
178 | config HAVE_KERNEL_GZIP |
179 | bool | |
180 | ||
181 | config HAVE_KERNEL_BZIP2 | |
182 | bool | |
183 | ||
184 | config HAVE_KERNEL_LZMA | |
185 | bool | |
186 | ||
3ebe1243 LC |
187 | config HAVE_KERNEL_XZ |
188 | bool | |
189 | ||
7dd65feb AT |
190 | config HAVE_KERNEL_LZO |
191 | bool | |
192 | ||
e76e1fdf KL |
193 | config HAVE_KERNEL_LZ4 |
194 | bool | |
195 | ||
48f7ddf7 NT |
196 | config HAVE_KERNEL_ZSTD |
197 | bool | |
198 | ||
f16466af VG |
199 | config HAVE_KERNEL_UNCOMPRESSED |
200 | bool | |
201 | ||
30d65dbf | 202 | choice |
2e9f3bdd PA |
203 | prompt "Kernel compression mode" |
204 | default KERNEL_GZIP | |
48f7ddf7 | 205 | 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 | 206 | help |
30d65dbf AK |
207 | The linux kernel is a kind of self-extracting executable. |
208 | Several compression algorithms are available, which differ | |
209 | in efficiency, compression and decompression speed. | |
210 | Compression speed is only relevant when building a kernel. | |
211 | Decompression speed is relevant at each boot. | |
212 | ||
213 | If you have any problems with bzip2 or lzma compressed | |
214 | kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older | |
215 | version of this functionality (bzip2 only), for 2.4, was | |
216 | supplied by Christian Ludwig) | |
217 | ||
218 | High compression options are mostly useful for users, who | |
219 | are low on disk space (embedded systems), but for whom ram | |
220 | size matters less. | |
221 | ||
222 | If in doubt, select 'gzip' | |
223 | ||
224 | config KERNEL_GZIP | |
2e9f3bdd PA |
225 | bool "Gzip" |
226 | depends on HAVE_KERNEL_GZIP | |
227 | help | |
7dd65feb AT |
228 | The old and tried gzip compression. It provides a good balance |
229 | between compression ratio and decompression speed. | |
30d65dbf AK |
230 | |
231 | config KERNEL_BZIP2 | |
232 | bool "Bzip2" | |
2e9f3bdd | 233 | depends on HAVE_KERNEL_BZIP2 |
30d65dbf AK |
234 | help |
235 | Its compression ratio and speed is intermediate. | |
0a4dd35c | 236 | Decompression speed is slowest among the choices. The kernel |
2e9f3bdd PA |
237 | size is about 10% smaller with bzip2, in comparison to gzip. |
238 | Bzip2 uses a large amount of memory. For modern kernels you | |
239 | will need at least 8MB RAM or more for booting. | |
30d65dbf AK |
240 | |
241 | config KERNEL_LZMA | |
2e9f3bdd PA |
242 | bool "LZMA" |
243 | depends on HAVE_KERNEL_LZMA | |
244 | help | |
0a4dd35c RD |
245 | This compression algorithm's ratio is best. Decompression speed |
246 | is between gzip and bzip2. Compression is slowest. | |
247 | The kernel size is about 33% smaller with LZMA in comparison to gzip. | |
30d65dbf | 248 | |
3ebe1243 LC |
249 | config KERNEL_XZ |
250 | bool "XZ" | |
251 | depends on HAVE_KERNEL_XZ | |
252 | help | |
253 | XZ uses the LZMA2 algorithm and instruction set specific | |
254 | BCJ filters which can improve compression ratio of executable | |
255 | code. The size of the kernel is about 30% smaller with XZ in | |
256 | comparison to gzip. On architectures for which there is a BCJ | |
257 | filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ | |
258 | will create a few percent smaller kernel than plain LZMA. | |
259 | ||
260 | The speed is about the same as with LZMA: The decompression | |
261 | speed of XZ is better than that of bzip2 but worse than gzip | |
262 | and LZO. Compression is slow. | |
263 | ||
7dd65feb AT |
264 | config KERNEL_LZO |
265 | bool "LZO" | |
266 | depends on HAVE_KERNEL_LZO | |
267 | help | |
0a4dd35c | 268 | Its compression ratio is the poorest among the choices. The kernel |
681b3049 | 269 | size is about 10% bigger than gzip; however its speed |
7dd65feb AT |
270 | (both compression and decompression) is the fastest. |
271 | ||
e76e1fdf KL |
272 | config KERNEL_LZ4 |
273 | bool "LZ4" | |
274 | depends on HAVE_KERNEL_LZ4 | |
275 | help | |
276 | LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding. | |
277 | A preliminary version of LZ4 de/compression tool is available at | |
278 | <https://code.google.com/p/lz4/>. | |
279 | ||
280 | Its compression ratio is worse than LZO. The size of the kernel | |
281 | is about 8% bigger than LZO. But the decompression speed is | |
282 | faster than LZO. | |
283 | ||
48f7ddf7 NT |
284 | config KERNEL_ZSTD |
285 | bool "ZSTD" | |
286 | depends on HAVE_KERNEL_ZSTD | |
287 | help | |
288 | ZSTD is a compression algorithm targeting intermediate compression | |
289 | with fast decompression speed. It will compress better than GZIP and | |
290 | decompress around the same speed as LZO, but slower than LZ4. You | |
291 | will need at least 192 KB RAM or more for booting. The zstd command | |
292 | line tool is required for compression. | |
293 | ||
f16466af VG |
294 | config KERNEL_UNCOMPRESSED |
295 | bool "None" | |
296 | depends on HAVE_KERNEL_UNCOMPRESSED | |
297 | help | |
298 | Produce uncompressed kernel image. This option is usually not what | |
299 | you want. It is useful for debugging the kernel in slow simulation | |
300 | environments, where decompressing and moving the kernel is awfully | |
301 | slow. This option allows early boot code to skip the decompressor | |
302 | and jump right at uncompressed kernel image. | |
303 | ||
30d65dbf AK |
304 | endchoice |
305 | ||
ada4ab7a CD |
306 | config DEFAULT_INIT |
307 | string "Default init path" | |
308 | default "" | |
309 | help | |
310 | This option determines the default init for the system if no init= | |
311 | option is passed on the kernel command line. If the requested path is | |
312 | not present, we will still then move on to attempting further | |
313 | locations (e.g. /sbin/init, etc). If this is empty, we will just use | |
314 | the fallback list when init= is not passed. | |
315 | ||
bd5dc17b JT |
316 | config DEFAULT_HOSTNAME |
317 | string "Default hostname" | |
318 | default "(none)" | |
319 | help | |
320 | This option determines the default system hostname before userspace | |
321 | calls sethostname(2). The kernel traditionally uses "(none)" here, | |
322 | but you may wish to use a different default here to make a minimal | |
323 | system more usable with less configuration. | |
324 | ||
17c46a6a CH |
325 | # |
326 | # For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can | |
327 | # add proper SWAP support to them, in which case this can be remove. | |
328 | # | |
329 | config ARCH_NO_SWAP | |
330 | bool | |
331 | ||
dbf9649e AW |
332 | config VERSION_SIGNATURE |
333 | string "Arbitrary version signature" | |
334 | help | |
335 | This string will be created in a file, /proc/version_signature. It | |
336 | is useful in determining arbitrary data about your kernel. For instance, | |
337 | if you have several kernels of the same version, but need to keep track | |
338 | of a revision of the same kernel, but not affect it's ability to load | |
339 | compatible modules, this is the easiest way to do that. | |
340 | ||
1da177e4 LT |
341 | config SWAP |
342 | bool "Support for paging of anonymous memory (swap)" | |
17c46a6a | 343 | depends on MMU && BLOCK && !ARCH_NO_SWAP |
1da177e4 LT |
344 | default y |
345 | help | |
346 | This option allows you to choose whether you want to have support | |
92c3504e | 347 | for so called swap devices or swap files in your kernel that are |
1da177e4 LT |
348 | used to provide more virtual memory than the actual RAM present |
349 | in your computer. If unsure say Y. | |
350 | ||
351 | config SYSVIPC | |
352 | bool "System V IPC" | |
a7f7f624 | 353 | help |
1da177e4 LT |
354 | Inter Process Communication is a suite of library functions and |
355 | system calls which let processes (running programs) synchronize and | |
356 | exchange information. It is generally considered to be a good thing, | |
357 | and some programs won't run unless you say Y here. In particular, if | |
358 | you want to run the DOS emulator dosemu under Linux (read the | |
359 | DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), | |
360 | you'll need to say Y here. | |
361 | ||
362 | You can find documentation about IPC with "info ipc" and also in | |
363 | section 6.4 of the Linux Programmer's Guide, available from | |
364 | <http://www.tldp.org/guides.html>. | |
365 | ||
a5494dcd EB |
366 | config SYSVIPC_SYSCTL |
367 | bool | |
368 | depends on SYSVIPC | |
369 | depends on SYSCTL | |
370 | default y | |
371 | ||
1da177e4 LT |
372 | config POSIX_MQUEUE |
373 | bool "POSIX Message Queues" | |
19c92399 | 374 | depends on NET |
a7f7f624 | 375 | help |
1da177e4 LT |
376 | POSIX variant of message queues is a part of IPC. In POSIX message |
377 | queues every message has a priority which decides about succession | |
378 | of receiving it by a process. If you want to compile and run | |
379 | programs written e.g. for Solaris with use of its POSIX message | |
b0e37650 | 380 | queues (functions mq_*) say Y here. |
1da177e4 LT |
381 | |
382 | POSIX message queues are visible as a filesystem called 'mqueue' | |
383 | and can be mounted somewhere if you want to do filesystem | |
384 | operations on message queues. | |
385 | ||
386 | If unsure, say Y. | |
387 | ||
bdc8e5f8 SH |
388 | config POSIX_MQUEUE_SYSCTL |
389 | bool | |
390 | depends on POSIX_MQUEUE | |
391 | depends on SYSCTL | |
392 | default y | |
393 | ||
c73be61c DH |
394 | config WATCH_QUEUE |
395 | bool "General notification queue" | |
396 | default n | |
397 | help | |
398 | ||
399 | This is a general notification queue for the kernel to pass events to | |
400 | userspace by splicing them into pipes. It can be used in conjunction | |
401 | with watches for key/keyring change notifications and device | |
402 | notifications. | |
403 | ||
404 | See Documentation/watch_queue.rst | |
405 | ||
226b4ccd KK |
406 | config CROSS_MEMORY_ATTACH |
407 | bool "Enable process_vm_readv/writev syscalls" | |
408 | depends on MMU | |
409 | default y | |
410 | help | |
411 | Enabling this option adds the system calls process_vm_readv and | |
412 | process_vm_writev which allow a process with the correct privileges | |
a2a368d9 | 413 | to directly read from or write to another process' address space. |
226b4ccd KK |
414 | See the man page for more details. |
415 | ||
69369a70 JT |
416 | config USELIB |
417 | bool "uselib syscall" | |
b2113a41 | 418 | def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION |
69369a70 JT |
419 | help |
420 | This option enables the uselib syscall, a system call used in the | |
421 | dynamic linker from libc5 and earlier. glibc does not use this | |
422 | system call. If you intend to run programs built on libc5 or | |
423 | earlier, you may need to enable this syscall. Current systems | |
424 | running glibc can safely disable this. | |
425 | ||
391dc69c FW |
426 | config AUDIT |
427 | bool "Auditing support" | |
428 | depends on NET | |
429 | help | |
430 | Enable auditing infrastructure that can be used with another | |
431 | kernel subsystem, such as SELinux (which requires this for | |
cb74ed27 PM |
432 | logging of avc messages output). System call auditing is included |
433 | on architectures which support it. | |
391dc69c | 434 | |
7a017721 AT |
435 | config HAVE_ARCH_AUDITSYSCALL |
436 | bool | |
437 | ||
391dc69c | 438 | config AUDITSYSCALL |
cb74ed27 | 439 | def_bool y |
7a017721 | 440 | depends on AUDIT && HAVE_ARCH_AUDITSYSCALL |
391dc69c FW |
441 | select FSNOTIFY |
442 | ||
391dc69c FW |
443 | source "kernel/irq/Kconfig" |
444 | source "kernel/time/Kconfig" | |
87a4c375 | 445 | source "kernel/Kconfig.preempt" |
391dc69c FW |
446 | |
447 | menu "CPU/Task time and stats accounting" | |
448 | ||
abf917cd FW |
449 | config VIRT_CPU_ACCOUNTING |
450 | bool | |
451 | ||
fdf9c356 FW |
452 | choice |
453 | prompt "Cputime accounting" | |
454 | default TICK_CPU_ACCOUNTING if !PPC64 | |
02fc8d37 | 455 | default VIRT_CPU_ACCOUNTING_NATIVE if PPC64 |
fdf9c356 FW |
456 | |
457 | # Kind of a stub config for the pure tick based cputime accounting | |
458 | config TICK_CPU_ACCOUNTING | |
459 | bool "Simple tick based cputime accounting" | |
c58b0df1 | 460 | depends on !S390 && !NO_HZ_FULL |
fdf9c356 FW |
461 | help |
462 | This is the basic tick based cputime accounting that maintains | |
463 | statistics about user, system and idle time spent on per jiffies | |
464 | granularity. | |
465 | ||
466 | If unsure, say Y. | |
467 | ||
abf917cd | 468 | config VIRT_CPU_ACCOUNTING_NATIVE |
b952741c | 469 | bool "Deterministic task and CPU time accounting" |
c58b0df1 | 470 | depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL |
abf917cd | 471 | select VIRT_CPU_ACCOUNTING |
b952741c FW |
472 | help |
473 | Select this option to enable more accurate task and CPU time | |
474 | accounting. This is done by reading a CPU counter on each | |
475 | kernel entry and exit and on transitions within the kernel | |
476 | between system, softirq and hardirq state, so there is a | |
477 | small performance impact. In the case of s390 or IBM POWER > 5, | |
478 | this also enables accounting of stolen time on logically-partitioned | |
479 | systems. | |
480 | ||
abf917cd FW |
481 | config VIRT_CPU_ACCOUNTING_GEN |
482 | bool "Full dynticks CPU time accounting" | |
ff3fb254 | 483 | depends on HAVE_CONTEXT_TRACKING |
554b0004 | 484 | depends on HAVE_VIRT_CPU_ACCOUNTING_GEN |
041a1574 | 485 | depends on GENERIC_CLOCKEVENTS |
abf917cd FW |
486 | select VIRT_CPU_ACCOUNTING |
487 | select CONTEXT_TRACKING | |
488 | help | |
489 | Select this option to enable task and CPU time accounting on full | |
490 | dynticks systems. This accounting is implemented by watching every | |
491 | kernel-user boundaries using the context tracking subsystem. | |
492 | The accounting is thus performed at the expense of some significant | |
493 | overhead. | |
494 | ||
495 | For now this is only useful if you are working on the full | |
496 | dynticks subsystem development. | |
497 | ||
498 | If unsure, say N. | |
499 | ||
b58c3584 RR |
500 | endchoice |
501 | ||
fdf9c356 FW |
502 | config IRQ_TIME_ACCOUNTING |
503 | bool "Fine granularity task level IRQ time accounting" | |
b58c3584 | 504 | depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE |
fdf9c356 FW |
505 | help |
506 | Select this option to enable fine granularity task irq time | |
507 | accounting. This is done by reading a timestamp on each | |
508 | transitions between softirq and hardirq state, so there can be a | |
509 | small performance impact. | |
510 | ||
511 | If in doubt, say N here. | |
512 | ||
11d4afd4 VG |
513 | config HAVE_SCHED_AVG_IRQ |
514 | def_bool y | |
515 | depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING | |
516 | depends on SMP | |
517 | ||
76504793 | 518 | config SCHED_THERMAL_PRESSURE |
98eb401d | 519 | bool |
fcd7c9c3 VS |
520 | default y if ARM && ARM_CPU_TOPOLOGY |
521 | default y if ARM64 | |
76504793 | 522 | depends on SMP |
98eb401d VS |
523 | depends on CPU_FREQ_THERMAL |
524 | help | |
525 | Select this option to enable thermal pressure accounting in the | |
526 | scheduler. Thermal pressure is the value conveyed to the scheduler | |
527 | that reflects the reduction in CPU compute capacity resulted from | |
528 | thermal throttling. Thermal throttling occurs when the performance of | |
529 | a CPU is capped due to high operating temperatures. | |
530 | ||
531 | If selected, the scheduler will be able to balance tasks accordingly, | |
532 | i.e. put less load on throttled CPUs than on non/less throttled ones. | |
533 | ||
534 | This requires the architecture to implement | |
535 | arch_set_thermal_pressure() and arch_get_thermal_pressure(). | |
76504793 | 536 | |
1da177e4 LT |
537 | config BSD_PROCESS_ACCT |
538 | bool "BSD Process Accounting" | |
2813893f | 539 | depends on MULTIUSER |
1da177e4 LT |
540 | help |
541 | If you say Y here, a user level program will be able to instruct the | |
542 | kernel (via a special system call) to write process accounting | |
543 | information to a file: whenever a process exits, information about | |
544 | that process will be appended to the file by the kernel. The | |
545 | information includes things such as creation time, owning user, | |
546 | command name, memory usage, controlling terminal etc. (the complete | |
547 | list is in the struct acct in <file:include/linux/acct.h>). It is | |
548 | up to the user level program to do useful things with this | |
549 | information. This is generally a good idea, so say Y. | |
550 | ||
551 | config BSD_PROCESS_ACCT_V3 | |
552 | bool "BSD Process Accounting version 3 file format" | |
553 | depends on BSD_PROCESS_ACCT | |
554 | default n | |
555 | help | |
556 | If you say Y here, the process accounting information is written | |
557 | in a new file format that also logs the process IDs of each | |
3903bf94 | 558 | process and its parent. Note that this file format is incompatible |
1da177e4 LT |
559 | with previous v0/v1/v2 file formats, so you will need updated tools |
560 | for processing it. A preliminary version of these tools is available | |
37a4c940 | 561 | at <http://www.gnu.org/software/acct/>. |
1da177e4 | 562 | |
c757249a | 563 | config TASKSTATS |
19c92399 | 564 | bool "Export task/process statistics through netlink" |
c757249a | 565 | depends on NET |
2813893f | 566 | depends on MULTIUSER |
c757249a SN |
567 | default n |
568 | help | |
569 | Export selected statistics for tasks/processes through the | |
570 | generic netlink interface. Unlike BSD process accounting, the | |
571 | statistics are available during the lifetime of tasks/processes as | |
572 | responses to commands. Like BSD accounting, they are sent to user | |
573 | space on task exit. | |
574 | ||
575 | Say N if unsure. | |
576 | ||
ca74e92b | 577 | config TASK_DELAY_ACCT |
19c92399 | 578 | bool "Enable per-task delay accounting" |
6f44993f | 579 | depends on TASKSTATS |
f6db8347 | 580 | select SCHED_INFO |
ca74e92b SN |
581 | help |
582 | Collect information on time spent by a task waiting for system | |
583 | resources like cpu, synchronous block I/O completion and swapping | |
584 | in pages. Such statistics can help in setting a task's priorities | |
585 | relative to other tasks for cpu, io, rss limits etc. | |
586 | ||
587 | Say N if unsure. | |
588 | ||
18f705f4 | 589 | config TASK_XACCT |
19c92399 | 590 | bool "Enable extended accounting over taskstats" |
18f705f4 AD |
591 | depends on TASKSTATS |
592 | help | |
593 | Collect extended task accounting data and send the data | |
594 | to userland for processing over the taskstats interface. | |
595 | ||
596 | Say N if unsure. | |
597 | ||
598 | config TASK_IO_ACCOUNTING | |
19c92399 | 599 | bool "Enable per-task storage I/O accounting" |
18f705f4 AD |
600 | depends on TASK_XACCT |
601 | help | |
602 | Collect information on the number of bytes of storage I/O which this | |
603 | task has caused. | |
604 | ||
605 | Say N if unsure. | |
606 | ||
eb414681 JW |
607 | config PSI |
608 | bool "Pressure stall information tracking" | |
609 | help | |
610 | Collect metrics that indicate how overcommitted the CPU, memory, | |
611 | and IO capacity are in the system. | |
612 | ||
613 | If you say Y here, the kernel will create /proc/pressure/ with the | |
614 | pressure statistics files cpu, memory, and io. These will indicate | |
615 | the share of walltime in which some or all tasks in the system are | |
616 | delayed due to contention of the respective resource. | |
617 | ||
2ce7135a JW |
618 | In kernels with cgroup support, cgroups (cgroup2 only) will |
619 | have cpu.pressure, memory.pressure, and io.pressure files, | |
620 | which aggregate pressure stalls for the grouped tasks only. | |
621 | ||
c3123552 | 622 | For more details see Documentation/accounting/psi.rst. |
eb414681 JW |
623 | |
624 | Say N if unsure. | |
625 | ||
e0c27447 JW |
626 | config PSI_DEFAULT_DISABLED |
627 | bool "Require boot parameter to enable pressure stall information tracking" | |
628 | default n | |
629 | depends on PSI | |
630 | help | |
631 | If set, pressure stall information tracking will be disabled | |
428a1cb4 BS |
632 | per default but can be enabled through passing psi=1 on the |
633 | kernel commandline during boot. | |
e0c27447 | 634 | |
7b2489d3 JW |
635 | This feature adds some code to the task wakeup and sleep |
636 | paths of the scheduler. The overhead is too low to affect | |
637 | common scheduling-intense workloads in practice (such as | |
638 | webservers, memcache), but it does show up in artificial | |
639 | scheduler stress tests, such as hackbench. | |
640 | ||
641 | If you are paranoid and not sure what the kernel will be | |
642 | used for, say Y. | |
643 | ||
644 | Say N if unsure. | |
645 | ||
391dc69c | 646 | endmenu # "CPU/Task time and stats accounting" |
d9817ebe | 647 | |
5c4991e2 FW |
648 | config CPU_ISOLATION |
649 | bool "CPU isolation" | |
414a2dc1 | 650 | depends on SMP || COMPILE_TEST |
2c43838c | 651 | default y |
5c4991e2 FW |
652 | help |
653 | Make sure that CPUs running critical tasks are not disturbed by | |
654 | any source of "noise" such as unbound workqueues, timers, kthreads... | |
2c43838c FW |
655 | Unbound jobs get offloaded to housekeeping CPUs. This is driven by |
656 | the "isolcpus=" boot parameter. | |
657 | ||
658 | Say Y if unsure. | |
5c4991e2 | 659 | |
0af92d46 | 660 | source "kernel/rcu/Kconfig" |
c903ff83 | 661 | |
de5b56ba VG |
662 | config BUILD_BIN2C |
663 | bool | |
664 | default n | |
665 | ||
1da177e4 | 666 | config IKCONFIG |
f2443ab6 | 667 | tristate "Kernel .config support" |
a7f7f624 | 668 | help |
1da177e4 LT |
669 | This option enables the complete Linux kernel ".config" file |
670 | contents to be saved in the kernel. It provides documentation | |
671 | of which kernel options are used in a running kernel or in an | |
672 | on-disk kernel. This information can be extracted from the kernel | |
673 | image file with the script scripts/extract-ikconfig and used as | |
674 | input to rebuild the current kernel or to build another kernel. | |
675 | It can also be extracted from a running kernel by reading | |
676 | /proc/config.gz if enabled (below). | |
677 | ||
678 | config IKCONFIG_PROC | |
679 | bool "Enable access to .config through /proc/config.gz" | |
680 | depends on IKCONFIG && PROC_FS | |
a7f7f624 | 681 | help |
1da177e4 LT |
682 | This option enables access to the kernel configuration file |
683 | through /proc/config.gz. | |
684 | ||
f7b101d3 JFG |
685 | config IKHEADERS |
686 | tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz" | |
687 | depends on SYSFS | |
688 | help | |
689 | This option enables access to the in-kernel headers that are generated during | |
690 | the build process. These can be used to build eBPF tracing programs, | |
691 | or similar programs. If you build the headers as a module, a module called | |
692 | kheaders.ko is built which can be loaded on-demand to get access to headers. | |
43d8ce9d | 693 | |
794543a2 AJS |
694 | config LOG_BUF_SHIFT |
695 | int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" | |
550c10d2 JO |
696 | range 12 25 if !H8300 |
697 | range 12 19 if H8300 | |
f17a32e9 | 698 | default 17 |
361e9dfb | 699 | depends on PRINTK |
794543a2 | 700 | help |
23b2899f LR |
701 | Select the minimal kernel log buffer size as a power of 2. |
702 | The final size is affected by LOG_CPU_MAX_BUF_SHIFT config | |
703 | parameter, see below. Any higher size also might be forced | |
704 | by "log_buf_len" boot parameter. | |
705 | ||
f17a32e9 | 706 | Examples: |
23b2899f | 707 | 17 => 128 KB |
f17a32e9 | 708 | 16 => 64 KB |
23b2899f LR |
709 | 15 => 32 KB |
710 | 14 => 16 KB | |
794543a2 AJS |
711 | 13 => 8 KB |
712 | 12 => 4 KB | |
713 | ||
23b2899f LR |
714 | config LOG_CPU_MAX_BUF_SHIFT |
715 | int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" | |
2240a31d | 716 | depends on SMP |
23b2899f LR |
717 | range 0 21 |
718 | default 12 if !BASE_SMALL | |
719 | default 0 if BASE_SMALL | |
361e9dfb | 720 | depends on PRINTK |
23b2899f LR |
721 | help |
722 | This option allows to increase the default ring buffer size | |
723 | according to the number of CPUs. The value defines the contribution | |
724 | of each CPU as a power of 2. The used space is typically only few | |
725 | lines however it might be much more when problems are reported, | |
726 | e.g. backtraces. | |
727 | ||
728 | The increased size means that a new buffer has to be allocated and | |
729 | the original static one is unused. It makes sense only on systems | |
730 | with more CPUs. Therefore this value is used only when the sum of | |
731 | contributions is greater than the half of the default kernel ring | |
732 | buffer as defined by LOG_BUF_SHIFT. The default values are set | |
0f7636e1 | 733 | so that more than 16 CPUs are needed to trigger the allocation. |
23b2899f LR |
734 | |
735 | Also this option is ignored when "log_buf_len" kernel parameter is | |
736 | used as it forces an exact (power of two) size of the ring buffer. | |
737 | ||
738 | The number of possible CPUs is used for this computation ignoring | |
5e0d8d59 GU |
739 | hotplugging making the computation optimal for the worst case |
740 | scenario while allowing a simple algorithm to be used from bootup. | |
23b2899f LR |
741 | |
742 | Examples shift values and their meaning: | |
743 | 17 => 128 KB for each CPU | |
744 | 16 => 64 KB for each CPU | |
745 | 15 => 32 KB for each CPU | |
746 | 14 => 16 KB for each CPU | |
747 | 13 => 8 KB for each CPU | |
748 | 12 => 4 KB for each CPU | |
749 | ||
f92bac3b SS |
750 | config PRINTK_SAFE_LOG_BUF_SHIFT |
751 | int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)" | |
427934b8 PM |
752 | range 10 21 |
753 | default 13 | |
f92bac3b | 754 | depends on PRINTK |
427934b8 | 755 | help |
f92bac3b SS |
756 | Select the size of an alternate printk per-CPU buffer where messages |
757 | printed from usafe contexts are temporary stored. One example would | |
758 | be NMI messages, another one - printk recursion. The messages are | |
759 | copied to the main log buffer in a safe context to avoid a deadlock. | |
760 | The value defines the size as a power of 2. | |
427934b8 | 761 | |
f92bac3b | 762 | Those messages are rare and limited. The largest one is when |
427934b8 PM |
763 | a backtrace is printed. It usually fits into 4KB. Select |
764 | 8KB if you want to be on the safe side. | |
765 | ||
766 | Examples: | |
767 | 17 => 128 KB for each CPU | |
768 | 16 => 64 KB for each CPU | |
769 | 15 => 32 KB for each CPU | |
770 | 14 => 16 KB for each CPU | |
771 | 13 => 8 KB for each CPU | |
772 | 12 => 4 KB for each CPU | |
773 | ||
a5574cf6 IM |
774 | # |
775 | # Architectures with an unreliable sched_clock() should select this: | |
776 | # | |
777 | config HAVE_UNSTABLE_SCHED_CLOCK | |
778 | bool | |
779 | ||
38ff87f7 SB |
780 | config GENERIC_SCHED_CLOCK |
781 | bool | |
782 | ||
69842cba PB |
783 | menu "Scheduler features" |
784 | ||
785 | config UCLAMP_TASK | |
786 | bool "Enable utilization clamping for RT/FAIR tasks" | |
787 | depends on CPU_FREQ_GOV_SCHEDUTIL | |
788 | help | |
789 | This feature enables the scheduler to track the clamped utilization | |
790 | of each CPU based on RUNNABLE tasks scheduled on that CPU. | |
791 | ||
792 | With this option, the user can specify the min and max CPU | |
793 | utilization allowed for RUNNABLE tasks. The max utilization defines | |
794 | the maximum frequency a task should use while the min utilization | |
795 | defines the minimum frequency it should use. | |
796 | ||
797 | Both min and max utilization clamp values are hints to the scheduler, | |
798 | aiming at improving its frequency selection policy, but they do not | |
799 | enforce or grant any specific bandwidth for tasks. | |
800 | ||
801 | If in doubt, say N. | |
802 | ||
803 | config UCLAMP_BUCKETS_COUNT | |
804 | int "Number of supported utilization clamp buckets" | |
805 | range 5 20 | |
806 | default 5 | |
807 | depends on UCLAMP_TASK | |
808 | help | |
809 | Defines the number of clamp buckets to use. The range of each bucket | |
810 | will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the | |
811 | number of clamp buckets the finer their granularity and the higher | |
812 | the precision of clamping aggregation and tracking at run-time. | |
813 | ||
814 | For example, with the minimum configuration value we will have 5 | |
815 | clamp buckets tracking 20% utilization each. A 25% boosted tasks will | |
816 | be refcounted in the [20..39]% bucket and will set the bucket clamp | |
817 | effective value to 25%. | |
818 | If a second 30% boosted task should be co-scheduled on the same CPU, | |
819 | that task will be refcounted in the same bucket of the first task and | |
820 | it will boost the bucket clamp effective value to 30%. | |
821 | The clamp effective value of a bucket is reset to its nominal value | |
822 | (20% in the example above) when there are no more tasks refcounted in | |
823 | that bucket. | |
824 | ||
825 | An additional boost/capping margin can be added to some tasks. In the | |
826 | example above the 25% task will be boosted to 30% until it exits the | |
827 | CPU. If that should be considered not acceptable on certain systems, | |
828 | it's always possible to reduce the margin by increasing the number of | |
829 | clamp buckets to trade off used memory for run-time tracking | |
830 | precision. | |
831 | ||
832 | If in doubt, use the default value. | |
833 | ||
834 | endmenu | |
835 | ||
be3a7284 AA |
836 | # |
837 | # For architectures that want to enable the support for NUMA-affine scheduler | |
838 | # balancing logic: | |
839 | # | |
840 | config ARCH_SUPPORTS_NUMA_BALANCING | |
841 | bool | |
842 | ||
72b252ae MG |
843 | # |
844 | # For architectures that prefer to flush all TLBs after a number of pages | |
845 | # are unmapped instead of sending one IPI per page to flush. The architecture | |
846 | # must provide guarantees on what happens if a clean TLB cache entry is | |
847 | # written after the unmap. Details are in mm/rmap.c near the check for | |
848 | # should_defer_flush. The architecture should also consider if the full flush | |
849 | # and the refill costs are offset by the savings of sending fewer IPIs. | |
850 | config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH | |
851 | bool | |
852 | ||
c12d3362 | 853 | config CC_HAS_INT128 |
3a7c7331 | 854 | def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT |
c12d3362 | 855 | |
be5e610c PZ |
856 | # |
857 | # For architectures that know their GCC __int128 support is sound | |
858 | # | |
859 | config ARCH_SUPPORTS_INT128 | |
860 | bool | |
861 | ||
be3a7284 AA |
862 | # For architectures that (ab)use NUMA to represent different memory regions |
863 | # all cpu-local but of different latencies, such as SuperH. | |
864 | # | |
865 | config ARCH_WANT_NUMA_VARIABLE_LOCALITY | |
866 | bool | |
867 | ||
be3a7284 AA |
868 | config NUMA_BALANCING |
869 | bool "Memory placement aware NUMA scheduler" | |
be3a7284 AA |
870 | depends on ARCH_SUPPORTS_NUMA_BALANCING |
871 | depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY | |
872 | depends on SMP && NUMA && MIGRATION | |
873 | help | |
874 | This option adds support for automatic NUMA aware memory/task placement. | |
875 | The mechanism is quite primitive and is based on migrating memory when | |
6d56a410 | 876 | it has references to the node the task is running on. |
be3a7284 AA |
877 | |
878 | This system will be inactive on UMA systems. | |
879 | ||
6f7c97e8 AK |
880 | config NUMA_BALANCING_DEFAULT_ENABLED |
881 | bool "Automatically enable NUMA aware memory/task placement" | |
882 | default y | |
883 | depends on NUMA_BALANCING | |
884 | help | |
885 | If set, automatic NUMA balancing will be enabled if running on a NUMA | |
886 | machine. | |
887 | ||
23964d2d | 888 | menuconfig CGROUPS |
6341e62b | 889 | bool "Control Group support" |
2bd59d48 | 890 | select KERNFS |
5cdc38f9 | 891 | help |
23964d2d | 892 | This option adds support for grouping sets of processes together, for |
5cdc38f9 KH |
893 | use with process control subsystems such as Cpusets, CFS, memory |
894 | controls or device isolation. | |
895 | See | |
d6a3b247 | 896 | - Documentation/scheduler/sched-design-CFS.rst (CFS) |
da82c92f | 897 | - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation |
45ce80fb | 898 | and resource control) |
5cdc38f9 KH |
899 | |
900 | Say N if unsure. | |
901 | ||
23964d2d LZ |
902 | if CGROUPS |
903 | ||
3e32cb2e | 904 | config PAGE_COUNTER |
e8cf4e9c | 905 | bool |
3e32cb2e | 906 | |
c255a458 | 907 | config MEMCG |
a0166ec4 | 908 | bool "Memory controller" |
3e32cb2e | 909 | select PAGE_COUNTER |
79bd9814 | 910 | select EVENTFD |
00f0b825 | 911 | help |
a0166ec4 | 912 | Provides control over the memory footprint of tasks in a cgroup. |
00f0b825 | 913 | |
c255a458 | 914 | config MEMCG_SWAP |
2d1c4980 | 915 | bool |
c255a458 | 916 | depends on MEMCG && SWAP |
a42c390c | 917 | default y |
c077719b | 918 | |
84c07d11 KT |
919 | config MEMCG_KMEM |
920 | bool | |
921 | depends on MEMCG && !SLOB | |
922 | default y | |
923 | ||
6bf024e6 JW |
924 | config BLK_CGROUP |
925 | bool "IO controller" | |
926 | depends on BLOCK | |
2bc64a20 | 927 | default n |
a7f7f624 | 928 | help |
6bf024e6 JW |
929 | Generic block IO controller cgroup interface. This is the common |
930 | cgroup interface which should be used by various IO controlling | |
931 | policies. | |
2bc64a20 | 932 | |
6bf024e6 JW |
933 | Currently, CFQ IO scheduler uses it to recognize task groups and |
934 | control disk bandwidth allocation (proportional time slice allocation) | |
935 | to such task groups. It is also used by bio throttling logic in | |
936 | block layer to implement upper limit in IO rates on a device. | |
e5d1367f | 937 | |
6bf024e6 JW |
938 | This option only enables generic Block IO controller infrastructure. |
939 | One needs to also enable actual IO controlling logic/policy. For | |
940 | enabling proportional weight division of disk bandwidth in CFQ, set | |
7baf2199 | 941 | CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set |
6bf024e6 JW |
942 | CONFIG_BLK_DEV_THROTTLING=y. |
943 | ||
da82c92f | 944 | See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information. |
6bf024e6 | 945 | |
6bf024e6 JW |
946 | config CGROUP_WRITEBACK |
947 | bool | |
948 | depends on MEMCG && BLK_CGROUP | |
949 | default y | |
e5d1367f | 950 | |
7c941438 | 951 | menuconfig CGROUP_SCHED |
a0166ec4 | 952 | bool "CPU controller" |
7c941438 DG |
953 | default n |
954 | help | |
955 | This feature lets CPU scheduler recognize task groups and control CPU | |
956 | bandwidth allocation to such task groups. It uses cgroups to group | |
957 | tasks. | |
958 | ||
959 | if CGROUP_SCHED | |
960 | config FAIR_GROUP_SCHED | |
961 | bool "Group scheduling for SCHED_OTHER" | |
962 | depends on CGROUP_SCHED | |
963 | default CGROUP_SCHED | |
964 | ||
ab84d31e PT |
965 | config CFS_BANDWIDTH |
966 | bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" | |
ab84d31e PT |
967 | depends on FAIR_GROUP_SCHED |
968 | default n | |
969 | help | |
970 | This option allows users to define CPU bandwidth rates (limits) for | |
971 | tasks running within the fair group scheduler. Groups with no limit | |
972 | set are considered to be unconstrained and will run with no | |
973 | restriction. | |
d6a3b247 | 974 | See Documentation/scheduler/sched-bwc.rst for more information. |
ab84d31e | 975 | |
7c941438 DG |
976 | config RT_GROUP_SCHED |
977 | bool "Group scheduling for SCHED_RR/FIFO" | |
7c941438 DG |
978 | depends on CGROUP_SCHED |
979 | default n | |
980 | help | |
981 | This feature lets you explicitly allocate real CPU bandwidth | |
32bd7eb5 | 982 | to task groups. If enabled, it will also make it impossible to |
7c941438 DG |
983 | schedule realtime tasks for non-root users until you allocate |
984 | realtime bandwidth for them. | |
d6a3b247 | 985 | See Documentation/scheduler/sched-rt-group.rst for more information. |
7c941438 DG |
986 | |
987 | endif #CGROUP_SCHED | |
988 | ||
2480c093 PB |
989 | config UCLAMP_TASK_GROUP |
990 | bool "Utilization clamping per group of tasks" | |
991 | depends on CGROUP_SCHED | |
992 | depends on UCLAMP_TASK | |
993 | default n | |
994 | help | |
995 | This feature enables the scheduler to track the clamped utilization | |
996 | of each CPU based on RUNNABLE tasks currently scheduled on that CPU. | |
997 | ||
998 | When this option is enabled, the user can specify a min and max | |
999 | CPU bandwidth which is allowed for each single task in a group. | |
1000 | The max bandwidth allows to clamp the maximum frequency a task | |
1001 | can use, while the min bandwidth allows to define a minimum | |
1002 | frequency a task will always use. | |
1003 | ||
1004 | When task group based utilization clamping is enabled, an eventually | |
1005 | specified task-specific clamp value is constrained by the cgroup | |
1006 | specified clamp value. Both minimum and maximum task clamping cannot | |
1007 | be bigger than the corresponding clamping defined at task group level. | |
1008 | ||
1009 | If in doubt, say N. | |
1010 | ||
6bf024e6 JW |
1011 | config CGROUP_PIDS |
1012 | bool "PIDs controller" | |
1013 | help | |
1014 | Provides enforcement of process number limits in the scope of a | |
1015 | cgroup. Any attempt to fork more processes than is allowed in the | |
1016 | cgroup will fail. PIDs are fundamentally a global resource because it | |
1017 | is fairly trivial to reach PID exhaustion before you reach even a | |
1018 | conservative kmemcg limit. As a result, it is possible to grind a | |
1019 | system to halt without being limited by other cgroup policies. The | |
6cc578df | 1020 | PIDs controller is designed to stop this from happening. |
6bf024e6 JW |
1021 | |
1022 | It should be noted that organisational operations (such as attaching | |
98076833 | 1023 | to a cgroup hierarchy) will *not* be blocked by the PIDs controller, |
6bf024e6 JW |
1024 | since the PIDs limit only affects a process's ability to fork, not to |
1025 | attach to a cgroup. | |
1026 | ||
39d3e758 PP |
1027 | config CGROUP_RDMA |
1028 | bool "RDMA controller" | |
1029 | help | |
1030 | Provides enforcement of RDMA resources defined by IB stack. | |
1031 | It is fairly easy for consumers to exhaust RDMA resources, which | |
1032 | can result into resource unavailability to other consumers. | |
1033 | RDMA controller is designed to stop this from happening. | |
1034 | Attaching processes with active RDMA resources to the cgroup | |
1035 | hierarchy is allowed even if can cross the hierarchy's limit. | |
1036 | ||
6bf024e6 JW |
1037 | config CGROUP_FREEZER |
1038 | bool "Freezer controller" | |
1039 | help | |
1040 | Provides a way to freeze and unfreeze all tasks in a | |
1041 | cgroup. | |
1042 | ||
489c2a20 JW |
1043 | This option affects the ORIGINAL cgroup interface. The cgroup2 memory |
1044 | controller includes important in-kernel memory consumers per default. | |
1045 | ||
1046 | If you're using cgroup2, say N. | |
1047 | ||
6bf024e6 JW |
1048 | config CGROUP_HUGETLB |
1049 | bool "HugeTLB controller" | |
1050 | depends on HUGETLB_PAGE | |
1051 | select PAGE_COUNTER | |
afc24d49 | 1052 | default n |
6bf024e6 JW |
1053 | help |
1054 | Provides a cgroup controller for HugeTLB pages. | |
1055 | When you enable this, you can put a per cgroup limit on HugeTLB usage. | |
1056 | The limit is enforced during page fault. Since HugeTLB doesn't | |
1057 | support page reclaim, enforcing the limit at page fault time implies | |
1058 | that, the application will get SIGBUS signal if it tries to access | |
1059 | HugeTLB pages beyond its limit. This requires the application to know | |
1060 | beforehand how much HugeTLB pages it would require for its use. The | |
1061 | control group is tracked in the third page lru pointer. This means | |
1062 | that we cannot use the controller with huge page less than 3 pages. | |
afc24d49 | 1063 | |
6bf024e6 JW |
1064 | config CPUSETS |
1065 | bool "Cpuset controller" | |
e1d4eeec | 1066 | depends on SMP |
6bf024e6 JW |
1067 | help |
1068 | This option will let you create and manage CPUSETs which | |
1069 | allow dynamically partitioning a system into sets of CPUs and | |
1070 | Memory Nodes and assigning tasks to run only within those sets. | |
1071 | This is primarily useful on large SMP or NUMA systems. | |
afc24d49 | 1072 | |
6bf024e6 | 1073 | Say N if unsure. |
afc24d49 | 1074 | |
6bf024e6 JW |
1075 | config PROC_PID_CPUSET |
1076 | bool "Include legacy /proc/<pid>/cpuset file" | |
1077 | depends on CPUSETS | |
1078 | default y | |
afc24d49 | 1079 | |
6bf024e6 JW |
1080 | config CGROUP_DEVICE |
1081 | bool "Device controller" | |
1082 | help | |
1083 | Provides a cgroup controller implementing whitelists for | |
1084 | devices which a process in the cgroup can mknod or open. | |
1085 | ||
1086 | config CGROUP_CPUACCT | |
1087 | bool "Simple CPU accounting controller" | |
1088 | help | |
1089 | Provides a simple controller for monitoring the | |
1090 | total CPU consumed by the tasks in a cgroup. | |
1091 | ||
1092 | config CGROUP_PERF | |
1093 | bool "Perf controller" | |
1094 | depends on PERF_EVENTS | |
1095 | help | |
1096 | This option extends the perf per-cpu mode to restrict monitoring | |
1097 | to threads which belong to the cgroup specified and run on the | |
6546b19f NK |
1098 | designated cpu. Or this can be used to have cgroup ID in samples |
1099 | so that it can monitor performance events among cgroups. | |
6bf024e6 JW |
1100 | |
1101 | Say N if unsure. | |
1102 | ||
30070984 DM |
1103 | config CGROUP_BPF |
1104 | bool "Support for eBPF programs attached to cgroups" | |
483c4933 AL |
1105 | depends on BPF_SYSCALL |
1106 | select SOCK_CGROUP_DATA | |
30070984 DM |
1107 | help |
1108 | Allow attaching eBPF programs to a cgroup using the bpf(2) | |
1109 | syscall command BPF_PROG_ATTACH. | |
1110 | ||
1111 | In which context these programs are accessed depends on the type | |
1112 | of attachment. For instance, programs that are attached using | |
1113 | BPF_CGROUP_INET_INGRESS will be executed on the ingress path of | |
1114 | inet sockets. | |
1115 | ||
6bf024e6 | 1116 | config CGROUP_DEBUG |
23b0be48 | 1117 | bool "Debug controller" |
afc24d49 | 1118 | default n |
23b0be48 | 1119 | depends on DEBUG_KERNEL |
6bf024e6 JW |
1120 | help |
1121 | This option enables a simple controller that exports | |
23b0be48 WL |
1122 | debugging information about the cgroups framework. This |
1123 | controller is for control cgroup debugging only. Its | |
1124 | interfaces are not stable. | |
afc24d49 | 1125 | |
6bf024e6 | 1126 | Say N. |
89e9b9e0 | 1127 | |
73b35147 AB |
1128 | config SOCK_CGROUP_DATA |
1129 | bool | |
1130 | default n | |
1131 | ||
23964d2d | 1132 | endif # CGROUPS |
c077719b | 1133 | |
8dd2a82c | 1134 | menuconfig NAMESPACES |
6a108a14 | 1135 | bool "Namespaces support" if EXPERT |
2813893f | 1136 | depends on MULTIUSER |
6a108a14 | 1137 | default !EXPERT |
c5289a69 PE |
1138 | help |
1139 | Provides the way to make tasks work with different objects using | |
1140 | the same id. For example same IPC id may refer to different objects | |
1141 | or same user id or pid may refer to different tasks when used in | |
1142 | different namespaces. | |
1143 | ||
8dd2a82c DL |
1144 | if NAMESPACES |
1145 | ||
58bfdd6d PE |
1146 | config UTS_NS |
1147 | bool "UTS namespace" | |
17a6d441 | 1148 | default y |
58bfdd6d PE |
1149 | help |
1150 | In this namespace tasks see different info provided with the | |
1151 | uname() system call | |
1152 | ||
769071ac AV |
1153 | config TIME_NS |
1154 | bool "TIME namespace" | |
660fd04f | 1155 | depends on GENERIC_VDSO_TIME_NS |
769071ac AV |
1156 | default y |
1157 | help | |
1158 | In this namespace boottime and monotonic clocks can be set. | |
1159 | The time will keep going with the same pace. | |
1160 | ||
ae5e1b22 PE |
1161 | config IPC_NS |
1162 | bool "IPC namespace" | |
8dd2a82c | 1163 | depends on (SYSVIPC || POSIX_MQUEUE) |
17a6d441 | 1164 | default y |
ae5e1b22 PE |
1165 | help |
1166 | In this namespace tasks work with IPC ids which correspond to | |
614b84cf | 1167 | different IPC objects in different namespaces. |
ae5e1b22 | 1168 | |
aee16ce7 | 1169 | config USER_NS |
19c92399 | 1170 | bool "User namespace" |
5673a94c | 1171 | default n |
aee16ce7 PE |
1172 | help |
1173 | This allows containers, i.e. vservers, to use user namespaces | |
1174 | to provide different user info for different servers. | |
e11f0ae3 EB |
1175 | |
1176 | When user namespaces are enabled in the kernel it is | |
d886f4e4 JW |
1177 | recommended that the MEMCG option also be enabled and that |
1178 | user-space use the memory control groups to limit the amount | |
1179 | of memory a memory unprivileged users can use. | |
e11f0ae3 | 1180 | |
aee16ce7 PE |
1181 | If unsure, say N. |
1182 | ||
74bd59bb | 1183 | config PID_NS |
9bd38c2c | 1184 | bool "PID Namespaces" |
17a6d441 | 1185 | default y |
74bd59bb | 1186 | help |
12d2b8f9 | 1187 | Support process id namespaces. This allows having multiple |
692105b8 | 1188 | processes with the same pid as long as they are in different |
74bd59bb PE |
1189 | pid namespaces. This is a building block of containers. |
1190 | ||
d6eb633f MH |
1191 | config NET_NS |
1192 | bool "Network namespace" | |
8dd2a82c | 1193 | depends on NET |
17a6d441 | 1194 | default y |
d6eb633f MH |
1195 | help |
1196 | Allow user space to create what appear to be multiple instances | |
1197 | of the network stack. | |
1198 | ||
8dd2a82c DL |
1199 | endif # NAMESPACES |
1200 | ||
5cb366bb AR |
1201 | config CHECKPOINT_RESTORE |
1202 | bool "Checkpoint/restore support" | |
1203 | select PROC_CHILDREN | |
62291c3b | 1204 | select KCMP |
5cb366bb AR |
1205 | default n |
1206 | help | |
1207 | Enables additional kernel features in a sake of checkpoint/restore. | |
1208 | In particular it adds auxiliary prctl codes to setup process text, | |
1209 | data and heap segment sizes, and a few additional /proc filesystem | |
1210 | entries. | |
1211 | ||
1212 | If unsure, say N here. | |
1213 | ||
5091faa4 MG |
1214 | config SCHED_AUTOGROUP |
1215 | bool "Automatic process group scheduling" | |
5091faa4 MG |
1216 | select CGROUPS |
1217 | select CGROUP_SCHED | |
1218 | select FAIR_GROUP_SCHED | |
1219 | help | |
1220 | This option optimizes the scheduler for common desktop workloads by | |
1221 | automatically creating and populating task groups. This separation | |
1222 | of workloads isolates aggressive CPU burners (like build jobs) from | |
1223 | desktop applications. Task group autogeneration is currently based | |
1224 | upon task session. | |
1225 | ||
7af37bec | 1226 | config SYSFS_DEPRECATED |
5d6a4ea5 | 1227 | bool "Enable deprecated sysfs features to support old userspace tools" |
7af37bec DL |
1228 | depends on SYSFS |
1229 | default n | |
1230 | help | |
1231 | This option adds code that switches the layout of the "block" class | |
1232 | devices, to not show up in /sys/class/block/, but only in | |
1233 | /sys/block/. | |
1234 | ||
1235 | This switch is only active when the sysfs.deprecated=1 boot option is | |
1236 | passed or the SYSFS_DEPRECATED_V2 option is set. | |
1237 | ||
1238 | This option allows new kernels to run on old distributions and tools, | |
1239 | which might get confused by /sys/class/block/. Since 2007/2008 all | |
1240 | major distributions and tools handle this just fine. | |
1241 | ||
1242 | Recent distributions and userspace tools after 2009/2010 depend on | |
1243 | the existence of /sys/class/block/, and will not work with this | |
1244 | option enabled. | |
1245 | ||
1246 | Only if you are using a new kernel on an old distribution, you might | |
1247 | need to say Y here. | |
1248 | ||
1249 | config SYSFS_DEPRECATED_V2 | |
5d6a4ea5 | 1250 | bool "Enable deprecated sysfs features by default" |
7af37bec DL |
1251 | default n |
1252 | depends on SYSFS | |
1253 | depends on SYSFS_DEPRECATED | |
1254 | help | |
1255 | Enable deprecated sysfs by default. | |
1256 | ||
1257 | See the CONFIG_SYSFS_DEPRECATED option for more details about this | |
1258 | option. | |
1259 | ||
1260 | Only if you are using a new kernel on an old distribution, you might | |
1261 | need to say Y here. Even then, odds are you would not need it | |
1262 | enabled, you can always pass the boot option if absolutely necessary. | |
1263 | ||
1264 | config RELAY | |
1265 | bool "Kernel->user space relay support (formerly relayfs)" | |
26b5679e | 1266 | select IRQ_WORK |
7af37bec DL |
1267 | help |
1268 | This option enables support for relay interface support in | |
1269 | certain file systems (such as debugfs). | |
1270 | It is designed to provide an efficient mechanism for tools and | |
1271 | facilities to relay large amounts of data from kernel space to | |
1272 | user space. | |
1273 | ||
1274 | If unsure, say N. | |
1275 | ||
f991633d DG |
1276 | config BLK_DEV_INITRD |
1277 | bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" | |
f991633d DG |
1278 | help |
1279 | The initial RAM filesystem is a ramfs which is loaded by the | |
1280 | boot loader (loadlin or lilo) and that is mounted as root | |
1281 | before the normal boot procedure. It is typically used to | |
1282 | load modules needed to mount the "real" root file system, | |
8c27ceff | 1283 | etc. See <file:Documentation/admin-guide/initrd.rst> for details. |
f991633d DG |
1284 | |
1285 | If RAM disk support (BLK_DEV_RAM) is also included, this | |
1286 | also enables initial RAM disk (initrd) support and adds | |
1287 | 15 Kbytes (more on some other architectures) to the kernel size. | |
1288 | ||
1289 | If unsure say Y. | |
1290 | ||
c33df4ea JPS |
1291 | if BLK_DEV_INITRD |
1292 | ||
dbec4866 SR |
1293 | source "usr/Kconfig" |
1294 | ||
c33df4ea JPS |
1295 | endif |
1296 | ||
76db5a27 MH |
1297 | config BOOT_CONFIG |
1298 | bool "Boot config support" | |
2910b5aa | 1299 | select BLK_DEV_INITRD |
76db5a27 MH |
1300 | help |
1301 | Extra boot config allows system admin to pass a config file as | |
1302 | complemental extension of kernel cmdline when booting. | |
0947db01 | 1303 | The boot config file must be attached at the end of initramfs |
85c46b78 | 1304 | with checksum, size and magic word. |
0947db01 | 1305 | See <file:Documentation/admin-guide/bootconfig.rst> for details. |
76db5a27 MH |
1306 | |
1307 | If unsure, say Y. | |
1308 | ||
877417e6 AB |
1309 | choice |
1310 | prompt "Compiler optimization level" | |
2cc3ce24 | 1311 | default CC_OPTIMIZE_FOR_PERFORMANCE |
877417e6 AB |
1312 | |
1313 | config CC_OPTIMIZE_FOR_PERFORMANCE | |
15f5db60 | 1314 | bool "Optimize for performance (-O2)" |
877417e6 AB |
1315 | help |
1316 | This is the default optimization level for the kernel, building | |
1317 | with the "-O2" compiler flag for best performance and most | |
1318 | helpful compile-time warnings. | |
1319 | ||
15f5db60 MY |
1320 | config CC_OPTIMIZE_FOR_PERFORMANCE_O3 |
1321 | bool "Optimize more for performance (-O3)" | |
1322 | depends on ARC | |
c45b4f1f | 1323 | help |
15f5db60 MY |
1324 | Choosing this option will pass "-O3" to your compiler to optimize |
1325 | the kernel yet more for performance. | |
c45b4f1f | 1326 | |
c45b4f1f | 1327 | config CC_OPTIMIZE_FOR_SIZE |
15f5db60 | 1328 | bool "Optimize for size (-Os)" |
c45b4f1f | 1329 | help |
ce3b487f MY |
1330 | Choosing this option will pass "-Os" to your compiler resulting |
1331 | in a smaller kernel. | |
c45b4f1f | 1332 | |
877417e6 AB |
1333 | endchoice |
1334 | ||
5d20ee31 NP |
1335 | config HAVE_LD_DEAD_CODE_DATA_ELIMINATION |
1336 | bool | |
1337 | help | |
1338 | This requires that the arch annotates or otherwise protects | |
1339 | its external entry points from being discarded. Linker scripts | |
1340 | must also merge .text.*, .data.*, and .bss.* correctly into | |
1341 | output sections. Care must be taken not to pull in unrelated | |
1342 | sections (e.g., '.text.init'). Typically '.' in section names | |
1343 | is used to distinguish them from label names / C identifiers. | |
1344 | ||
1345 | config LD_DEAD_CODE_DATA_ELIMINATION | |
1346 | bool "Dead code and data elimination (EXPERIMENTAL)" | |
1347 | depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION | |
1348 | depends on EXPERT | |
e85d1d65 MY |
1349 | depends on $(cc-option,-ffunction-sections -fdata-sections) |
1350 | depends on $(ld-option,--gc-sections) | |
5d20ee31 | 1351 | help |
8b9d2712 MY |
1352 | Enable this if you want to do dead code and data elimination with |
1353 | the linker by compiling with -ffunction-sections -fdata-sections, | |
1354 | and linking with --gc-sections. | |
5d20ee31 NP |
1355 | |
1356 | This can reduce on disk and in-memory size of the kernel | |
1357 | code and static data, particularly for small configs and | |
1358 | on small systems. This has the possibility of introducing | |
1359 | silently broken kernel if the required annotations are not | |
1360 | present. This option is not well tested yet, so use at your | |
1361 | own risk. | |
1362 | ||
59612b24 NC |
1363 | config LD_ORPHAN_WARN |
1364 | def_bool y | |
1365 | depends on ARCH_WANT_LD_ORPHAN_WARN | |
d5750cd3 | 1366 | depends on !LD_IS_LLD || LLD_VERSION >= 110000 |
59612b24 NC |
1367 | depends on $(ld-option,--orphan-handling=warn) |
1368 | ||
0847062a RD |
1369 | config SYSCTL |
1370 | bool | |
1371 | ||
657a5209 MF |
1372 | config HAVE_UID16 |
1373 | bool | |
1374 | ||
1375 | config SYSCTL_EXCEPTION_TRACE | |
1376 | bool | |
1377 | help | |
1378 | Enable support for /proc/sys/debug/exception-trace. | |
1379 | ||
1380 | config SYSCTL_ARCH_UNALIGN_NO_WARN | |
1381 | bool | |
1382 | help | |
1383 | Enable support for /proc/sys/kernel/ignore-unaligned-usertrap | |
1384 | Allows arch to define/use @no_unaligned_warning to possibly warn | |
1385 | about unaligned access emulation going on under the hood. | |
1386 | ||
1387 | config SYSCTL_ARCH_UNALIGN_ALLOW | |
1388 | bool | |
1389 | help | |
1390 | Enable support for /proc/sys/kernel/unaligned-trap | |
1391 | Allows arches to define/use @unaligned_enabled to runtime toggle | |
1392 | the unaligned access emulation. | |
1393 | see arch/parisc/kernel/unaligned.c for reference | |
1394 | ||
657a5209 MF |
1395 | config HAVE_PCSPKR_PLATFORM |
1396 | bool | |
1397 | ||
f89b7755 AS |
1398 | # interpreter that classic socket filters depend on |
1399 | config BPF | |
1400 | bool | |
1401 | ||
6a108a14 DR |
1402 | menuconfig EXPERT |
1403 | bool "Configure standard kernel features (expert users)" | |
f505c553 JT |
1404 | # Unhide debug options, to make the on-by-default options visible |
1405 | select DEBUG_KERNEL | |
1da177e4 LT |
1406 | help |
1407 | This option allows certain base kernel options and settings | |
e8cf4e9c KK |
1408 | to be disabled or tweaked. This is for specialized |
1409 | environments which can tolerate a "non-standard" kernel. | |
1410 | Only use this if you really know what you are doing. | |
1da177e4 | 1411 | |
ae81f9e3 | 1412 | config UID16 |
6a108a14 | 1413 | bool "Enable 16-bit UID system calls" if EXPERT |
2813893f | 1414 | depends on HAVE_UID16 && MULTIUSER |
ae81f9e3 CE |
1415 | default y |
1416 | help | |
1417 | This enables the legacy 16-bit UID syscall wrappers. | |
1418 | ||
2813893f IM |
1419 | config MULTIUSER |
1420 | bool "Multiple users, groups and capabilities support" if EXPERT | |
1421 | default y | |
1422 | help | |
1423 | This option enables support for non-root users, groups and | |
1424 | capabilities. | |
1425 | ||
1426 | If you say N here, all processes will run with UID 0, GID 0, and all | |
1427 | possible capabilities. Saying N here also compiles out support for | |
1428 | system calls related to UIDs, GIDs, and capabilities, such as setuid, | |
1429 | setgid, and capset. | |
1430 | ||
1431 | If unsure, say Y here. | |
1432 | ||
f6187769 FF |
1433 | config SGETMASK_SYSCALL |
1434 | bool "sgetmask/ssetmask syscalls support" if EXPERT | |
a687a533 | 1435 | def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH |
a7f7f624 | 1436 | help |
f6187769 FF |
1437 | sys_sgetmask and sys_ssetmask are obsolete system calls |
1438 | no longer supported in libc but still enabled by default in some | |
1439 | architectures. | |
1440 | ||
1441 | If unsure, leave the default option here. | |
1442 | ||
6af9f7bf FF |
1443 | config SYSFS_SYSCALL |
1444 | bool "Sysfs syscall support" if EXPERT | |
1445 | default y | |
a7f7f624 | 1446 | help |
6af9f7bf FF |
1447 | sys_sysfs is an obsolete system call no longer supported in libc. |
1448 | Note that disabling this option is more secure but might break | |
1449 | compatibility with some systems. | |
1450 | ||
1451 | If unsure say Y here. | |
1452 | ||
d1b069f5 RD |
1453 | config FHANDLE |
1454 | bool "open by fhandle syscalls" if EXPERT | |
1455 | select EXPORTFS | |
1456 | default y | |
1457 | help | |
1458 | If you say Y here, a user level program will be able to map | |
1459 | file names to handle and then later use the handle for | |
1460 | different file system operations. This is useful in implementing | |
1461 | userspace file servers, which now track files using handles instead | |
1462 | of names. The handle would remain the same even if file names | |
1463 | get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) | |
1464 | syscalls. | |
1465 | ||
baa73d9e NP |
1466 | config POSIX_TIMERS |
1467 | bool "Posix Clocks & timers" if EXPERT | |
1468 | default y | |
1469 | help | |
1470 | This includes native support for POSIX timers to the kernel. | |
1471 | Some embedded systems have no use for them and therefore they | |
1472 | can be configured out to reduce the size of the kernel image. | |
1473 | ||
1474 | When this option is disabled, the following syscalls won't be | |
1475 | available: timer_create, timer_gettime: timer_getoverrun, | |
1476 | timer_settime, timer_delete, clock_adjtime, getitimer, | |
1477 | setitimer, alarm. Furthermore, the clock_settime, clock_gettime, | |
1478 | clock_getres and clock_nanosleep syscalls will be limited to | |
1479 | CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. | |
1480 | ||
1481 | If unsure say y. | |
1482 | ||
d59745ce MM |
1483 | config PRINTK |
1484 | default y | |
6a108a14 | 1485 | bool "Enable support for printk" if EXPERT |
74876a98 | 1486 | select IRQ_WORK |
d59745ce MM |
1487 | help |
1488 | This option enables normal printk support. Removing it | |
1489 | eliminates most of the message strings from the kernel image | |
1490 | and makes the kernel more or less silent. As this makes it | |
1491 | very difficult to diagnose system problems, saying N here is | |
1492 | strongly discouraged. | |
1493 | ||
42a0bb3f PM |
1494 | config PRINTK_NMI |
1495 | def_bool y | |
1496 | depends on PRINTK | |
1497 | depends on HAVE_NMI | |
1498 | ||
c8538a7a | 1499 | config BUG |
6a108a14 | 1500 | bool "BUG() support" if EXPERT |
c8538a7a MM |
1501 | default y |
1502 | help | |
e8cf4e9c KK |
1503 | Disabling this option eliminates support for BUG and WARN, reducing |
1504 | the size of your kernel image and potentially quietly ignoring | |
1505 | numerous fatal conditions. You should only consider disabling this | |
1506 | option for embedded systems with no facilities for reporting errors. | |
1507 | Just say Y. | |
c8538a7a | 1508 | |
708e9a79 | 1509 | config ELF_CORE |
046d662f | 1510 | depends on COREDUMP |
708e9a79 | 1511 | default y |
6a108a14 | 1512 | bool "Enable ELF core dumps" if EXPERT |
708e9a79 MM |
1513 | help |
1514 | Enable support for generating core dumps. Disabling saves about 4k. | |
1515 | ||
8761f1ab | 1516 | |
e5e1d3cb | 1517 | config PCSPKR_PLATFORM |
6a108a14 | 1518 | bool "Enable PC-Speaker support" if EXPERT |
8761f1ab | 1519 | depends on HAVE_PCSPKR_PLATFORM |
15f304b6 | 1520 | select I8253_LOCK |
e5e1d3cb SS |
1521 | default y |
1522 | help | |
e8cf4e9c KK |
1523 | This option allows to disable the internal PC-Speaker |
1524 | support, saving some memory. | |
e5e1d3cb | 1525 | |
1da177e4 LT |
1526 | config BASE_FULL |
1527 | default y | |
6a108a14 | 1528 | bool "Enable full-sized data structures for core" if EXPERT |
1da177e4 LT |
1529 | help |
1530 | Disabling this option reduces the size of miscellaneous core | |
1531 | kernel data structures. This saves memory on small machines, | |
1532 | but may reduce performance. | |
1533 | ||
1534 | config FUTEX | |
6a108a14 | 1535 | bool "Enable futex support" if EXPERT |
1da177e4 | 1536 | default y |
bc2eecd7 | 1537 | imply RT_MUTEXES |
1da177e4 LT |
1538 | help |
1539 | Disabling this option will cause the kernel to be built without | |
1540 | support for "fast userspace mutexes". The resulting kernel may not | |
1541 | run glibc-based applications correctly. | |
1542 | ||
bc2eecd7 NP |
1543 | config FUTEX_PI |
1544 | bool | |
1545 | depends on FUTEX && RT_MUTEXES | |
1546 | default y | |
1547 | ||
03b8c7b6 HC |
1548 | config HAVE_FUTEX_CMPXCHG |
1549 | bool | |
62b4d204 | 1550 | depends on FUTEX |
03b8c7b6 HC |
1551 | help |
1552 | Architectures should select this if futex_atomic_cmpxchg_inatomic() | |
1553 | is implemented and always working. This removes a couple of runtime | |
1554 | checks. | |
1555 | ||
1da177e4 | 1556 | config EPOLL |
6a108a14 | 1557 | bool "Enable eventpoll support" if EXPERT |
1da177e4 LT |
1558 | default y |
1559 | help | |
1560 | Disabling this option will cause the kernel to be built without | |
1561 | support for epoll family of system calls. | |
1562 | ||
fba2afaa | 1563 | config SIGNALFD |
6a108a14 | 1564 | bool "Enable signalfd() system call" if EXPERT |
fba2afaa DL |
1565 | default y |
1566 | help | |
1567 | Enable the signalfd() system call that allows to receive signals | |
1568 | on a file descriptor. | |
1569 | ||
1570 | If unsure, say Y. | |
1571 | ||
b215e283 | 1572 | config TIMERFD |
6a108a14 | 1573 | bool "Enable timerfd() system call" if EXPERT |
b215e283 DL |
1574 | default y |
1575 | help | |
1576 | Enable the timerfd() system call that allows to receive timer | |
1577 | events on a file descriptor. | |
1578 | ||
1579 | If unsure, say Y. | |
1580 | ||
e1ad7468 | 1581 | config EVENTFD |
6a108a14 | 1582 | bool "Enable eventfd() system call" if EXPERT |
e1ad7468 DL |
1583 | default y |
1584 | help | |
1585 | Enable the eventfd() system call that allows to receive both | |
1586 | kernel notification (ie. KAIO) or userspace notifications. | |
1587 | ||
1588 | If unsure, say Y. | |
1589 | ||
1da177e4 | 1590 | config SHMEM |
6a108a14 | 1591 | bool "Use full shmem filesystem" if EXPERT |
1da177e4 LT |
1592 | default y |
1593 | depends on MMU | |
1594 | help | |
1595 | The shmem is an internal filesystem used to manage shared memory. | |
1596 | It is backed by swap and manages resource limits. It is also exported | |
1597 | to userspace as tmpfs if TMPFS is enabled. Disabling this | |
1598 | option replaces shmem and tmpfs with the much simpler ramfs code, | |
1599 | which may be appropriate on small systems without swap. | |
1600 | ||
ebf3f09c | 1601 | config AIO |
6a108a14 | 1602 | bool "Enable AIO support" if EXPERT |
ebf3f09c TP |
1603 | default y |
1604 | help | |
1605 | This option enables POSIX asynchronous I/O which may by used | |
657a5209 MF |
1606 | by some high performance threaded applications. Disabling |
1607 | this option saves about 7k. | |
1608 | ||
2b188cc1 JA |
1609 | config IO_URING |
1610 | bool "Enable IO uring support" if EXPERT | |
561fb04a | 1611 | select IO_WQ |
2b188cc1 JA |
1612 | default y |
1613 | help | |
1614 | This option enables support for the io_uring interface, enabling | |
1615 | applications to submit and complete IO through submission and | |
1616 | completion rings that are shared between the kernel and application. | |
1617 | ||
d3ac21ca JT |
1618 | config ADVISE_SYSCALLS |
1619 | bool "Enable madvise/fadvise syscalls" if EXPERT | |
1620 | default y | |
1621 | help | |
1622 | This option enables the madvise and fadvise syscalls, used by | |
1623 | applications to advise the kernel about their future memory or file | |
1624 | usage, improving performance. If building an embedded system where no | |
1625 | applications use these syscalls, you can disable this option to save | |
1626 | space. | |
1627 | ||
5a281062 AA |
1628 | config HAVE_ARCH_USERFAULTFD_WP |
1629 | bool | |
1630 | help | |
1631 | Arch has userfaultfd write protection support | |
1632 | ||
5b25b13a MD |
1633 | config MEMBARRIER |
1634 | bool "Enable membarrier() system call" if EXPERT | |
1635 | default y | |
1636 | help | |
1637 | Enable the membarrier() system call that allows issuing memory | |
1638 | barriers across all running threads, which can be used to distribute | |
1639 | the cost of user-space memory barriers asymmetrically by transforming | |
1640 | pairs of memory barriers into pairs consisting of membarrier() and a | |
1641 | compiler barrier. | |
1642 | ||
1643 | If unsure, say Y. | |
1644 | ||
d1b069f5 | 1645 | config KALLSYMS |
e8cf4e9c KK |
1646 | bool "Load all symbols for debugging/ksymoops" if EXPERT |
1647 | default y | |
1648 | help | |
1649 | Say Y here to let the kernel print out symbolic crash information and | |
1650 | symbolic stack backtraces. This increases the size of the kernel | |
1651 | somewhat, as all symbols have to be loaded into the kernel image. | |
d1b069f5 RD |
1652 | |
1653 | config KALLSYMS_ALL | |
1654 | bool "Include all symbols in kallsyms" | |
1655 | depends on DEBUG_KERNEL && KALLSYMS | |
1656 | help | |
e8cf4e9c KK |
1657 | Normally kallsyms only contains the symbols of functions for nicer |
1658 | OOPS messages and backtraces (i.e., symbols from the text and inittext | |
1659 | sections). This is sufficient for most cases. And only in very rare | |
1660 | cases (e.g., when a debugger is used) all symbols are required (e.g., | |
1661 | names of variables from the data sections, etc). | |
d1b069f5 | 1662 | |
e8cf4e9c KK |
1663 | This option makes sure that all symbols are loaded into the kernel |
1664 | image (i.e., symbols from all sections) in cost of increased kernel | |
1665 | size (depending on the kernel configuration, it may be 300KiB or | |
1666 | something like this). | |
d1b069f5 | 1667 | |
e8cf4e9c | 1668 | Say N unless you really need all symbols. |
d1b069f5 RD |
1669 | |
1670 | config KALLSYMS_ABSOLUTE_PERCPU | |
1671 | bool | |
1672 | depends on KALLSYMS | |
1673 | default X86_64 && SMP | |
1674 | ||
1675 | config KALLSYMS_BASE_RELATIVE | |
1676 | bool | |
1677 | depends on KALLSYMS | |
a687a533 | 1678 | default !IA64 |
d1b069f5 RD |
1679 | help |
1680 | Instead of emitting them as absolute values in the native word size, | |
1681 | emit the symbol references in the kallsyms table as 32-bit entries, | |
1682 | each containing a relative value in the range [base, base + U32_MAX] | |
1683 | or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either | |
1684 | an absolute value in the range [0, S32_MAX] or a relative value in the | |
1685 | range [base, base + S32_MAX], where base is the lowest relative symbol | |
1686 | address encountered in the image. | |
1687 | ||
1688 | On 64-bit builds, this reduces the size of the address table by 50%, | |
1689 | but more importantly, it results in entries whose values are build | |
1690 | time constants, and no relocation pass is required at runtime to fix | |
1691 | up the entries based on the runtime load address of the kernel. | |
1692 | ||
1693 | # end of the "standard kernel features (expert users)" menu | |
1694 | ||
1695 | # syscall, maps, verifier | |
fc611f47 KS |
1696 | |
1697 | config BPF_LSM | |
1698 | bool "LSM Instrumentation with BPF" | |
4edf16b7 | 1699 | depends on BPF_EVENTS |
fc611f47 KS |
1700 | depends on BPF_SYSCALL |
1701 | depends on SECURITY | |
1702 | depends on BPF_JIT | |
1703 | help | |
1704 | Enables instrumentation of the security hooks with eBPF programs for | |
1705 | implementing dynamic MAC and Audit Policies. | |
1706 | ||
1707 | If you are unsure how to answer this question, answer N. | |
1708 | ||
d1b069f5 RD |
1709 | config BPF_SYSCALL |
1710 | bool "Enable bpf() system call" | |
d1b069f5 | 1711 | select BPF |
bae77c5e | 1712 | select IRQ_WORK |
1e6c62a8 | 1713 | select TASKS_TRACE_RCU |
d1b069f5 RD |
1714 | default n |
1715 | help | |
1716 | Enable the bpf() system call that allows to manipulate eBPF | |
1717 | programs and maps via file descriptors. | |
1718 | ||
81c22041 DB |
1719 | config ARCH_WANT_DEFAULT_BPF_JIT |
1720 | bool | |
1721 | ||
290af866 AS |
1722 | config BPF_JIT_ALWAYS_ON |
1723 | bool "Permanently enable BPF JIT and remove BPF interpreter" | |
1724 | depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT | |
1725 | help | |
1726 | Enables BPF JIT and removes BPF interpreter to avoid | |
1727 | speculative execution of BPF instructions by the interpreter | |
1728 | ||
81c22041 DB |
1729 | config BPF_JIT_DEFAULT_ON |
1730 | def_bool ARCH_WANT_DEFAULT_BPF_JIT || BPF_JIT_ALWAYS_ON | |
1731 | depends on HAVE_EBPF_JIT && BPF_JIT | |
1732 | ||
d71fa5c9 AS |
1733 | source "kernel/bpf/preload/Kconfig" |
1734 | ||
d1b069f5 RD |
1735 | config USERFAULTFD |
1736 | bool "Enable userfaultfd() system call" | |
d1b069f5 RD |
1737 | depends on MMU |
1738 | help | |
1739 | Enable the userfaultfd() system call that allows to intercept and | |
1740 | handle page faults in userland. | |
1741 | ||
3ccfebed MD |
1742 | config ARCH_HAS_MEMBARRIER_CALLBACKS |
1743 | bool | |
1744 | ||
70216e18 MD |
1745 | config ARCH_HAS_MEMBARRIER_SYNC_CORE |
1746 | bool | |
1747 | ||
62291c3b CW |
1748 | config KCMP |
1749 | bool "Enable kcmp() system call" if EXPERT | |
1750 | help | |
1751 | Enable the kernel resource comparison system call. It provides | |
1752 | user-space with the ability to compare two processes to see if they | |
1753 | share a common resource, such as a file descriptor or even virtual | |
1754 | memory space. | |
1755 | ||
1756 | If unsure, say N. | |
1757 | ||
d7822b1e MD |
1758 | config RSEQ |
1759 | bool "Enable rseq() system call" if EXPERT | |
1760 | default y | |
1761 | depends on HAVE_RSEQ | |
1762 | select MEMBARRIER | |
1763 | help | |
1764 | Enable the restartable sequences system call. It provides a | |
1765 | user-space cache for the current CPU number value, which | |
1766 | speeds up getting the current CPU number from user-space, | |
1767 | as well as an ABI to speed up user-space operations on | |
1768 | per-CPU data. | |
1769 | ||
1770 | If unsure, say Y. | |
1771 | ||
1772 | config DEBUG_RSEQ | |
1773 | default n | |
1774 | bool "Enabled debugging of rseq() system call" if EXPERT | |
1775 | depends on RSEQ && DEBUG_KERNEL | |
1776 | help | |
1777 | Enable extra debugging checks for the rseq system call. | |
1778 | ||
1779 | If unsure, say N. | |
1780 | ||
6befe5f6 RD |
1781 | config EMBEDDED |
1782 | bool "Embedded system" | |
5d2acfc7 | 1783 | option allnoconfig_y |
6befe5f6 RD |
1784 | select EXPERT |
1785 | help | |
1786 | This option should be enabled if compiling the kernel for | |
1787 | an embedded system so certain expert options are available | |
1788 | for configuration. | |
1789 | ||
cdd6c482 | 1790 | config HAVE_PERF_EVENTS |
0793a61d | 1791 | bool |
018df72d MF |
1792 | help |
1793 | See tools/perf/design.txt for details. | |
0793a61d | 1794 | |
906010b2 PZ |
1795 | config PERF_USE_VMALLOC |
1796 | bool | |
1797 | help | |
1798 | See tools/perf/design.txt for details | |
1799 | ||
ad90a3de | 1800 | config PC104 |
424529fb | 1801 | bool "PC/104 support" if EXPERT |
ad90a3de WBG |
1802 | help |
1803 | Expose PC/104 form factor device drivers and options available for | |
1804 | selection and configuration. Enable this option if your target | |
1805 | machine has a PC/104 bus. | |
1806 | ||
57c0c15b | 1807 | menu "Kernel Performance Events And Counters" |
0793a61d | 1808 | |
cdd6c482 | 1809 | config PERF_EVENTS |
57c0c15b | 1810 | bool "Kernel performance events and counters" |
392d65a9 | 1811 | default y if PROFILING |
cdd6c482 | 1812 | depends on HAVE_PERF_EVENTS |
e360adbe | 1813 | select IRQ_WORK |
83fe27ea | 1814 | select SRCU |
0793a61d | 1815 | help |
57c0c15b IM |
1816 | Enable kernel support for various performance events provided |
1817 | by software and hardware. | |
0793a61d | 1818 | |
dd77038d | 1819 | Software events are supported either built-in or via the |
57c0c15b | 1820 | use of generic tracepoints. |
0793a61d | 1821 | |
57c0c15b IM |
1822 | Most modern CPUs support performance events via performance |
1823 | counter registers. These registers count the number of certain | |
0793a61d TG |
1824 | types of hw events: such as instructions executed, cachemisses |
1825 | suffered, or branches mis-predicted - without slowing down the | |
1826 | kernel or applications. These registers can also trigger interrupts | |
1827 | when a threshold number of events have passed - and can thus be | |
1828 | used to profile the code that runs on that CPU. | |
1829 | ||
57c0c15b | 1830 | The Linux Performance Event subsystem provides an abstraction of |
dd77038d | 1831 | these software and hardware event capabilities, available via a |
57c0c15b | 1832 | system call and used by the "perf" utility in tools/perf/. It |
0793a61d TG |
1833 | provides per task and per CPU counters, and it provides event |
1834 | capabilities on top of those. | |
1835 | ||
1836 | Say Y if unsure. | |
1837 | ||
906010b2 PZ |
1838 | config DEBUG_PERF_USE_VMALLOC |
1839 | default n | |
1840 | bool "Debug: use vmalloc to back perf mmap() buffers" | |
cb307113 | 1841 | depends on PERF_EVENTS && DEBUG_KERNEL && !PPC |
906010b2 PZ |
1842 | select PERF_USE_VMALLOC |
1843 | help | |
e8cf4e9c | 1844 | Use vmalloc memory to back perf mmap() buffers. |
906010b2 | 1845 | |
e8cf4e9c KK |
1846 | Mostly useful for debugging the vmalloc code on platforms |
1847 | that don't require it. | |
906010b2 | 1848 | |
e8cf4e9c | 1849 | Say N if unsure. |
906010b2 | 1850 | |
0793a61d TG |
1851 | endmenu |
1852 | ||
f8891e5e CL |
1853 | config VM_EVENT_COUNTERS |
1854 | default y | |
6a108a14 | 1855 | bool "Enable VM event counters for /proc/vmstat" if EXPERT |
f8891e5e | 1856 | help |
2aea4fb6 PJ |
1857 | VM event counters are needed for event counts to be shown. |
1858 | This option allows the disabling of the VM event counters | |
6a108a14 | 1859 | on EXPERT systems. /proc/vmstat will only show page counts |
2aea4fb6 | 1860 | if VM event counters are disabled. |
f8891e5e | 1861 | |
41ecc55b CL |
1862 | config SLUB_DEBUG |
1863 | default y | |
6a108a14 | 1864 | bool "Enable SLUB debugging support" if EXPERT |
f6acb635 | 1865 | depends on SLUB && SYSFS |
41ecc55b CL |
1866 | help |
1867 | SLUB has extensive debug support features. Disabling these can | |
1868 | result in significant savings in code size. This also disables | |
1869 | SLUB sysfs support. /sys/slab will not exist and there will be | |
1870 | no support for cache validation etc. | |
1871 | ||
1663f26d TH |
1872 | config SLUB_MEMCG_SYSFS_ON |
1873 | default n | |
1874 | bool "Enable memcg SLUB sysfs support by default" if EXPERT | |
1875 | depends on SLUB && SYSFS && MEMCG | |
1876 | help | |
1877 | SLUB creates a directory under /sys/kernel/slab for each | |
1878 | allocation cache to host info and debug files. If memory | |
1879 | cgroup is enabled, each cache can have per memory cgroup | |
1880 | caches. SLUB can create the same sysfs directories for these | |
1881 | caches under /sys/kernel/slab/CACHE/cgroup but it can lead | |
1882 | to a very high number of debug files being created. This is | |
1883 | controlled by slub_memcg_sysfs boot parameter and this | |
1884 | config option determines the parameter's default value. | |
1885 | ||
b943c460 RD |
1886 | config COMPAT_BRK |
1887 | bool "Disable heap randomization" | |
1888 | default y | |
1889 | help | |
1890 | Randomizing heap placement makes heap exploits harder, but it | |
1891 | also breaks ancient binaries (including anything libc5 based). | |
1892 | This option changes the bootup default to heap randomization | |
692105b8 | 1893 | disabled, and can be overridden at runtime by setting |
b943c460 RD |
1894 | /proc/sys/kernel/randomize_va_space to 2. |
1895 | ||
1896 | On non-ancient distros (post-2000 ones) N is usually a safe choice. | |
1897 | ||
81819f0f CL |
1898 | choice |
1899 | prompt "Choose SLAB allocator" | |
a0acd820 | 1900 | default SLUB |
81819f0f CL |
1901 | help |
1902 | This option allows to select a slab allocator. | |
1903 | ||
1904 | config SLAB | |
1905 | bool "SLAB" | |
04385fc5 | 1906 | select HAVE_HARDENED_USERCOPY_ALLOCATOR |
81819f0f CL |
1907 | help |
1908 | The regular slab allocator that is established and known to work | |
34013886 | 1909 | well in all environments. It organizes cache hot objects in |
02f56210 | 1910 | per cpu and per node queues. |
81819f0f CL |
1911 | |
1912 | config SLUB | |
81819f0f | 1913 | bool "SLUB (Unqueued Allocator)" |
ed18adc1 | 1914 | select HAVE_HARDENED_USERCOPY_ALLOCATOR |
81819f0f CL |
1915 | help |
1916 | SLUB is a slab allocator that minimizes cache line usage | |
1917 | instead of managing queues of cached objects (SLAB approach). | |
1918 | Per cpu caching is realized using slabs of objects instead | |
1919 | of queues of objects. SLUB can use memory efficiently | |
02f56210 SA |
1920 | and has enhanced diagnostics. SLUB is the default choice for |
1921 | a slab allocator. | |
81819f0f CL |
1922 | |
1923 | config SLOB | |
6a108a14 | 1924 | depends on EXPERT |
81819f0f CL |
1925 | bool "SLOB (Simple Allocator)" |
1926 | help | |
37291458 MM |
1927 | SLOB replaces the stock allocator with a drastically simpler |
1928 | allocator. SLOB is generally more space efficient but | |
1929 | does not perform as well on large systems. | |
81819f0f CL |
1930 | |
1931 | endchoice | |
1932 | ||
7660a6fd KC |
1933 | config SLAB_MERGE_DEFAULT |
1934 | bool "Allow slab caches to be merged" | |
1935 | default y | |
1936 | help | |
1937 | For reduced kernel memory fragmentation, slab caches can be | |
1938 | merged when they share the same size and other characteristics. | |
1939 | This carries a risk of kernel heap overflows being able to | |
1940 | overwrite objects from merged caches (and more easily control | |
1941 | cache layout), which makes such heap attacks easier to exploit | |
1942 | by attackers. By keeping caches unmerged, these kinds of exploits | |
1943 | can usually only damage objects in the same cache. To disable | |
1944 | merging at runtime, "slab_nomerge" can be passed on the kernel | |
1945 | command line. | |
1946 | ||
c7ce4f60 | 1947 | config SLAB_FREELIST_RANDOM |
3404be67 | 1948 | bool "Randomize slab freelist" |
210e7a43 | 1949 | depends on SLAB || SLUB |
c7ce4f60 | 1950 | help |
210e7a43 | 1951 | Randomizes the freelist order used on creating new pages. This |
c7ce4f60 TG |
1952 | security feature reduces the predictability of the kernel slab |
1953 | allocator against heap overflows. | |
1954 | ||
2482ddec KC |
1955 | config SLAB_FREELIST_HARDENED |
1956 | bool "Harden slab freelist metadata" | |
3404be67 | 1957 | depends on SLAB || SLUB |
2482ddec KC |
1958 | help |
1959 | Many kernel heap attacks try to target slab cache metadata and | |
1960 | other infrastructure. This options makes minor performance | |
92bae787 | 1961 | sacrifices to harden the kernel slab allocator against common |
3404be67 KC |
1962 | freelist exploit methods. Some slab implementations have more |
1963 | sanity-checking than others. This option is most effective with | |
1964 | CONFIG_SLUB. | |
2482ddec | 1965 | |
e900a918 DW |
1966 | config SHUFFLE_PAGE_ALLOCATOR |
1967 | bool "Page allocator randomization" | |
1968 | default SLAB_FREELIST_RANDOM && ACPI_NUMA | |
1969 | help | |
1970 | Randomization of the page allocator improves the average | |
1971 | utilization of a direct-mapped memory-side-cache. See section | |
1972 | 5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI | |
1973 | 6.2a specification for an example of how a platform advertises | |
1974 | the presence of a memory-side-cache. There are also incidental | |
1975 | security benefits as it reduces the predictability of page | |
1976 | allocations to compliment SLAB_FREELIST_RANDOM, but the | |
1977 | default granularity of shuffling on the "MAX_ORDER - 1" i.e, | |
1978 | 10th order of pages is selected based on cache utilization | |
1979 | benefits on x86. | |
1980 | ||
1981 | While the randomization improves cache utilization it may | |
1982 | negatively impact workloads on platforms without a cache. For | |
1983 | this reason, by default, the randomization is enabled only | |
1984 | after runtime detection of a direct-mapped memory-side-cache. | |
1985 | Otherwise, the randomization may be force enabled with the | |
1986 | 'page_alloc.shuffle' kernel command line parameter. | |
1987 | ||
1988 | Say Y if unsure. | |
1989 | ||
345c905d JK |
1990 | config SLUB_CPU_PARTIAL |
1991 | default y | |
b39ffbf8 | 1992 | depends on SLUB && SMP |
345c905d JK |
1993 | bool "SLUB per cpu partial cache" |
1994 | help | |
92bae787 | 1995 | Per cpu partial caches accelerate objects allocation and freeing |
345c905d JK |
1996 | that is local to a processor at the price of more indeterminism |
1997 | in the latency of the free. On overflow these caches will be cleared | |
1998 | which requires the taking of locks that may cause latency spikes. | |
1999 | Typically one would choose no for a realtime system. | |
2000 | ||
ea637639 JZ |
2001 | config MMAP_ALLOW_UNINITIALIZED |
2002 | bool "Allow mmapped anonymous memory to be uninitialized" | |
6a108a14 | 2003 | depends on EXPERT && !MMU |
ea637639 JZ |
2004 | default n |
2005 | help | |
2006 | Normally, and according to the Linux spec, anonymous memory obtained | |
3903bf94 | 2007 | from mmap() has its contents cleared before it is passed to |
ea637639 JZ |
2008 | userspace. Enabling this config option allows you to request that |
2009 | mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus | |
2010 | providing a huge performance boost. If this option is not enabled, | |
2011 | then the flag will be ignored. | |
2012 | ||
2013 | This is taken advantage of by uClibc's malloc(), and also by | |
2014 | ELF-FDPIC binfmt's brk and stack allocator. | |
2015 | ||
2016 | Because of the obvious security issues, this option should only be | |
2017 | enabled on embedded devices where you control what is run in | |
2018 | userspace. Since that isn't generally a problem on no-MMU systems, | |
2019 | it is normally safe to say Y here. | |
2020 | ||
dd19d293 | 2021 | See Documentation/admin-guide/mm/nommu-mmap.rst for more information. |
ea637639 | 2022 | |
091f6e26 DH |
2023 | config SYSTEM_DATA_VERIFICATION |
2024 | def_bool n | |
2025 | select SYSTEM_TRUSTED_KEYRING | |
2026 | select KEYS | |
2027 | select CRYPTO | |
d43de6c7 | 2028 | select CRYPTO_RSA |
091f6e26 DH |
2029 | select ASYMMETRIC_KEY_TYPE |
2030 | select ASYMMETRIC_PUBLIC_KEY_SUBTYPE | |
091f6e26 DH |
2031 | select ASN1 |
2032 | select OID_REGISTRY | |
2033 | select X509_CERTIFICATE_PARSER | |
2034 | select PKCS7_MESSAGE_PARSER | |
82c04ff8 | 2035 | help |
091f6e26 DH |
2036 | Provide PKCS#7 message verification using the contents of the system |
2037 | trusted keyring to provide public keys. This then can be used for | |
2038 | module verification, kexec image verification and firmware blob | |
2039 | verification. | |
82c04ff8 | 2040 | |
125e5645 | 2041 | config PROFILING |
b309a294 | 2042 | bool "Profiling support" |
125e5645 MD |
2043 | help |
2044 | Say Y here to enable the extended profiling support mechanisms used | |
2045 | by profilers such as OProfile. | |
2046 | ||
5f87f112 IM |
2047 | # |
2048 | # Place an empty function call at each tracepoint site. Can be | |
2049 | # dynamically changed for a probe function. | |
2050 | # | |
97e1c18e | 2051 | config TRACEPOINTS |
5f87f112 | 2052 | bool |
97e1c18e | 2053 | |
1da177e4 LT |
2054 | endmenu # General setup |
2055 | ||
1572497c CH |
2056 | source "arch/Kconfig" |
2057 | ||
ae81f9e3 | 2058 | config RT_MUTEXES |
6341e62b | 2059 | bool |
ae81f9e3 | 2060 | |
1da177e4 LT |
2061 | config BASE_SMALL |
2062 | int | |
2063 | default 0 if BASE_FULL | |
2064 | default 1 if !BASE_FULL | |
2065 | ||
c8424e77 TJB |
2066 | config MODULE_SIG_FORMAT |
2067 | def_bool n | |
2068 | select SYSTEM_DATA_VERIFICATION | |
2069 | ||
66da5733 | 2070 | menuconfig MODULES |
1da177e4 | 2071 | bool "Enable loadable module support" |
11097a03 | 2072 | option modules |
1da177e4 LT |
2073 | help |
2074 | Kernel modules are small pieces of compiled code which can | |
2075 | be inserted in the running kernel, rather than being | |
2076 | permanently built into the kernel. You use the "modprobe" | |
2077 | tool to add (and sometimes remove) them. If you say Y here, | |
2078 | many parts of the kernel can be built as modules (by | |
2079 | answering M instead of Y where indicated): this is most | |
2080 | useful for infrequently used options which are not required | |
2081 | for booting. For more information, see the man pages for | |
2082 | modprobe, lsmod, modinfo, insmod and rmmod. | |
2083 | ||
2084 | If you say Y here, you will need to run "make | |
2085 | modules_install" to put the modules under /lib/modules/ | |
2086 | where modprobe can find them (you may need to be root to do | |
2087 | this). | |
2088 | ||
2089 | If unsure, say Y. | |
2090 | ||
0b0de144 RD |
2091 | if MODULES |
2092 | ||
826e4506 LT |
2093 | config MODULE_FORCE_LOAD |
2094 | bool "Forced module loading" | |
826e4506 LT |
2095 | default n |
2096 | help | |
91e37a79 RR |
2097 | Allow loading of modules without version information (ie. modprobe |
2098 | --force). Forced module loading sets the 'F' (forced) taint flag and | |
2099 | is usually a really bad idea. | |
826e4506 | 2100 | |
1da177e4 LT |
2101 | config MODULE_UNLOAD |
2102 | bool "Module unloading" | |
1da177e4 LT |
2103 | help |
2104 | Without this option you will not be able to unload any | |
2105 | modules (note that some modules may not be unloadable | |
f7f5b675 DV |
2106 | anyway), which makes your kernel smaller, faster |
2107 | and simpler. If unsure, say Y. | |
1da177e4 LT |
2108 | |
2109 | config MODULE_FORCE_UNLOAD | |
2110 | bool "Forced module unloading" | |
19c92399 | 2111 | depends on MODULE_UNLOAD |
1da177e4 LT |
2112 | help |
2113 | This option allows you to force a module to unload, even if the | |
2114 | kernel believes it is unsafe: the kernel will remove the module | |
2115 | without waiting for anyone to stop using it (using the -f option to | |
2116 | rmmod). This is mainly for kernel developers and desperate users. | |
2117 | If unsure, say N. | |
2118 | ||
1da177e4 | 2119 | config MODVERSIONS |
0d541643 | 2120 | bool "Module versioning support" |
1da177e4 LT |
2121 | help |
2122 | Usually, you have to use modules compiled with your kernel. | |
2123 | Saying Y here makes it sometimes possible to use modules | |
2124 | compiled for different kernels, by adding enough information | |
2125 | to the modules to (hopefully) spot any changes which would | |
2126 | make them incompatible with the kernel you are running. If | |
2127 | unsure, say N. | |
2128 | ||
2ff2b7ec MY |
2129 | config ASM_MODVERSIONS |
2130 | bool | |
2131 | default HAVE_ASM_MODVERSIONS && MODVERSIONS | |
2132 | help | |
2133 | This enables module versioning for exported symbols also from | |
2134 | assembly. This can be enabled only when the target architecture | |
2135 | supports it. | |
2136 | ||
56067812 AB |
2137 | config MODULE_REL_CRCS |
2138 | bool | |
2139 | depends on MODVERSIONS | |
2140 | ||
1da177e4 LT |
2141 | config MODULE_SRCVERSION_ALL |
2142 | bool "Source checksum for all modules" | |
1da177e4 LT |
2143 | help |
2144 | Modules which contain a MODULE_VERSION get an extra "srcversion" | |
2145 | field inserted into their modinfo section, which contains a | |
2146 | sum of the source files which made it. This helps maintainers | |
2147 | see exactly which source was used to build a module (since | |
2148 | others sometimes change the module source without updating | |
2149 | the version). With this option, such a "srcversion" field | |
2150 | will be created for all modules. If unsure, say N. | |
2151 | ||
106a4ee2 RR |
2152 | config MODULE_SIG |
2153 | bool "Module signature verification" | |
c8424e77 | 2154 | select MODULE_SIG_FORMAT |
106a4ee2 RR |
2155 | help |
2156 | Check modules for valid signatures upon load: the signature | |
2157 | is simply appended to the module. For more information see | |
cbdc8217 | 2158 | <file:Documentation/admin-guide/module-signing.rst>. |
106a4ee2 | 2159 | |
228c37ff DH |
2160 | Note that this option adds the OpenSSL development packages as a |
2161 | kernel build dependency so that the signing tool can use its crypto | |
2162 | library. | |
2163 | ||
49fcf732 DH |
2164 | You should enable this option if you wish to use either |
2165 | CONFIG_SECURITY_LOCKDOWN_LSM or lockdown functionality imposed via | |
2166 | another LSM - otherwise unsigned modules will be loadable regardless | |
2167 | of the lockdown policy. | |
2168 | ||
ea0b6dcf DH |
2169 | !!!WARNING!!! If you enable this option, you MUST make sure that the |
2170 | module DOES NOT get stripped after being signed. This includes the | |
2171 | debuginfo strip done by some packagers (such as rpmbuild) and | |
2172 | inclusion into an initramfs that wants the module size reduced. | |
2173 | ||
106a4ee2 RR |
2174 | config MODULE_SIG_FORCE |
2175 | bool "Require modules to be validly signed" | |
2176 | depends on MODULE_SIG | |
2177 | help | |
2178 | Reject unsigned modules or signed modules for which we don't have a | |
2179 | key. Without this, such modules will simply taint the kernel. | |
ea0b6dcf | 2180 | |
d9d8d7ed MM |
2181 | config MODULE_SIG_ALL |
2182 | bool "Automatically sign all modules" | |
2183 | default y | |
2184 | depends on MODULE_SIG | |
2185 | help | |
2186 | Sign all modules during make modules_install. Without this option, | |
2187 | modules must be signed manually, using the scripts/sign-file tool. | |
2188 | ||
2189 | comment "Do not forget to sign required modules with scripts/sign-file" | |
2190 | depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL | |
2191 | ||
ea0b6dcf DH |
2192 | choice |
2193 | prompt "Which hash algorithm should modules be signed with?" | |
2194 | depends on MODULE_SIG | |
2195 | help | |
2196 | This determines which sort of hashing algorithm will be used during | |
2197 | signature generation. This algorithm _must_ be built into the kernel | |
2198 | directly so that signature verification can take place. It is not | |
2199 | possible to load a signed module containing the algorithm to check | |
2200 | the signature on that module. | |
2201 | ||
2202 | config MODULE_SIG_SHA1 | |
2203 | bool "Sign modules with SHA-1" | |
2204 | select CRYPTO_SHA1 | |
2205 | ||
2206 | config MODULE_SIG_SHA224 | |
2207 | bool "Sign modules with SHA-224" | |
2208 | select CRYPTO_SHA256 | |
2209 | ||
2210 | config MODULE_SIG_SHA256 | |
2211 | bool "Sign modules with SHA-256" | |
2212 | select CRYPTO_SHA256 | |
2213 | ||
2214 | config MODULE_SIG_SHA384 | |
2215 | bool "Sign modules with SHA-384" | |
2216 | select CRYPTO_SHA512 | |
2217 | ||
2218 | config MODULE_SIG_SHA512 | |
2219 | bool "Sign modules with SHA-512" | |
2220 | select CRYPTO_SHA512 | |
2221 | ||
2222 | endchoice | |
2223 | ||
22753674 MM |
2224 | config MODULE_SIG_HASH |
2225 | string | |
2226 | depends on MODULE_SIG | |
2227 | default "sha1" if MODULE_SIG_SHA1 | |
2228 | default "sha224" if MODULE_SIG_SHA224 | |
2229 | default "sha256" if MODULE_SIG_SHA256 | |
2230 | default "sha384" if MODULE_SIG_SHA384 | |
2231 | default "sha512" if MODULE_SIG_SHA512 | |
2232 | ||
beb50df3 BJ |
2233 | config MODULE_COMPRESS |
2234 | bool "Compress modules on installation" | |
beb50df3 | 2235 | help |
beb50df3 | 2236 | |
b6c09b51 RR |
2237 | Compresses kernel modules when 'make modules_install' is run; gzip or |
2238 | xz depending on "Compression algorithm" below. | |
beb50df3 | 2239 | |
b6c09b51 | 2240 | module-init-tools MAY support gzip, and kmod MAY support gzip and xz. |
beb50df3 | 2241 | |
b6c09b51 RR |
2242 | Out-of-tree kernel modules installed using Kbuild will also be |
2243 | compressed upon installation. | |
beb50df3 | 2244 | |
b6c09b51 RR |
2245 | Note: for modules inside an initrd or initramfs, it's more efficient |
2246 | to compress the whole initrd or initramfs instead. | |
beb50df3 | 2247 | |
b6c09b51 RR |
2248 | Note: This is fully compatible with signed modules. |
2249 | ||
2250 | If in doubt, say N. | |
beb50df3 BJ |
2251 | |
2252 | choice | |
2253 | prompt "Compression algorithm" | |
2254 | depends on MODULE_COMPRESS | |
2255 | default MODULE_COMPRESS_GZIP | |
2256 | help | |
2257 | This determines which sort of compression will be used during | |
2258 | 'make modules_install'. | |
2259 | ||
2260 | GZIP (default) and XZ are supported. | |
2261 | ||
2262 | config MODULE_COMPRESS_GZIP | |
2263 | bool "GZIP" | |
2264 | ||
2265 | config MODULE_COMPRESS_XZ | |
2266 | bool "XZ" | |
2267 | ||
2268 | endchoice | |
2269 | ||
3d52ec5e MM |
2270 | config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS |
2271 | bool "Allow loading of modules with missing namespace imports" | |
2272 | help | |
2273 | Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in | |
2274 | a namespace. A module that makes use of a symbol exported with such a | |
2275 | namespace is required to import the namespace via MODULE_IMPORT_NS(). | |
2276 | There is no technical reason to enforce correct namespace imports, | |
2277 | but it creates consistency between symbols defining namespaces and | |
2278 | users importing namespaces they make use of. This option relaxes this | |
2279 | requirement and lifts the enforcement when loading a module. | |
2280 | ||
2281 | If unsure, say N. | |
2282 | ||
efd9763d MY |
2283 | config UNUSED_SYMBOLS |
2284 | bool "Enable unused/obsolete exported symbols" | |
2285 | default y if X86 | |
2286 | help | |
2287 | Unused but exported symbols make the kernel needlessly bigger. For | |
2288 | that reason most of these unused exports will soon be removed. This | |
2289 | option is provided temporarily to provide a transition period in case | |
2290 | some external kernel module needs one of these symbols anyway. If you | |
2291 | encounter such a case in your module, consider if you are actually | |
2292 | using the right API. (rationale: since nobody in the kernel is using | |
2293 | this in a module, there is a pretty good chance it's actually the | |
2294 | wrong interface to use). If you really need the symbol, please send a | |
2295 | mail to the linux kernel mailing list mentioning the symbol and why | |
2296 | you really need it, and what the merge plan to the mainline kernel for | |
2297 | your module is. | |
2298 | ||
dbacb0ef NP |
2299 | config TRIM_UNUSED_KSYMS |
2300 | bool "Trim unused exported kernel symbols" | |
d189c2a4 | 2301 | depends on !UNUSED_SYMBOLS |
dbacb0ef NP |
2302 | help |
2303 | The kernel and some modules make many symbols available for | |
2304 | other modules to use via EXPORT_SYMBOL() and variants. Depending | |
2305 | on the set of modules being selected in your kernel configuration, | |
2306 | many of those exported symbols might never be used. | |
2307 | ||
2308 | This option allows for unused exported symbols to be dropped from | |
2309 | the build. In turn, this provides the compiler more opportunities | |
2310 | (especially when using LTO) for optimizing the code and reducing | |
2311 | binary size. This might have some security advantages as well. | |
2312 | ||
f1cb637e | 2313 | If unsure, or if you need to build out-of-tree modules, say N. |
dbacb0ef | 2314 | |
1518c633 QP |
2315 | config UNUSED_KSYMS_WHITELIST |
2316 | string "Whitelist of symbols to keep in ksymtab" | |
2317 | depends on TRIM_UNUSED_KSYMS | |
2318 | help | |
2319 | By default, all unused exported symbols will be un-exported from the | |
2320 | build when TRIM_UNUSED_KSYMS is selected. | |
2321 | ||
2322 | UNUSED_KSYMS_WHITELIST allows to whitelist symbols that must be kept | |
2323 | exported at all times, even in absence of in-tree users. The value to | |
2324 | set here is the path to a text file containing the list of symbols, | |
2325 | one per line. The path can be absolute, or relative to the kernel | |
2326 | source tree. | |
2327 | ||
0b0de144 RD |
2328 | endif # MODULES |
2329 | ||
6c9692e2 PZ |
2330 | config MODULES_TREE_LOOKUP |
2331 | def_bool y | |
2332 | depends on PERF_EVENTS || TRACING | |
2333 | ||
98a79d6a RR |
2334 | config INIT_ALL_POSSIBLE |
2335 | bool | |
2336 | help | |
5f054e31 RR |
2337 | Back when each arch used to define their own cpu_online_mask and |
2338 | cpu_possible_mask, some of them chose to initialize cpu_possible_mask | |
98a79d6a RR |
2339 | with all 1s, and others with all 0s. When they were centralised, |
2340 | it was better to provide this option than to break all the archs | |
692105b8 | 2341 | and have several arch maintainers pursuing me down dark alleys. |
98a79d6a | 2342 | |
3a65dfe8 | 2343 | source "block/Kconfig" |
e98c3202 AK |
2344 | |
2345 | config PREEMPT_NOTIFIERS | |
2346 | bool | |
e260be67 | 2347 | |
16295bec SK |
2348 | config PADATA |
2349 | depends on SMP | |
2350 | bool | |
2351 | ||
4520c6a4 DH |
2352 | config ASN1 |
2353 | tristate | |
2354 | help | |
2355 | Build a simple ASN.1 grammar compiler that produces a bytecode output | |
2356 | that can be interpreted by the ASN.1 stream decoder and used to | |
2357 | inform it as to what tags are to be expected in a stream and what | |
2358 | functions to call on what tags. | |
2359 | ||
6beb0009 | 2360 | source "kernel/Kconfig.locks" |
e61938a9 | 2361 | |
0ebeea8c DB |
2362 | config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE |
2363 | bool | |
2364 | ||
e61938a9 MD |
2365 | config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE |
2366 | bool | |
1bd21c6c DB |
2367 | |
2368 | # It may be useful for an architecture to override the definitions of the | |
7303e30e DB |
2369 | # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h> |
2370 | # and the COMPAT_ variants in <linux/compat.h>, in particular to use a | |
2371 | # different calling convention for syscalls. They can also override the | |
2372 | # macros for not-implemented syscalls in kernel/sys_ni.c and | |
2373 | # kernel/time/posix-stubs.c. All these overrides need to be available in | |
2374 | # <asm/syscall_wrapper.h>. | |
1bd21c6c DB |
2375 | config ARCH_HAS_SYSCALL_WRAPPER |
2376 | def_bool n |