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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 | |
a4353898 MY |
11 | config CC_IS_GCC |
12 | def_bool $(success,$(CC) --version | head -n 1 | grep -q gcc) | |
13 | ||
14 | config GCC_VERSION | |
15 | int | |
fa7295ab | 16 | default $(shell,$(srctree)/scripts/gcc-version.sh $(CC)) if CC_IS_GCC |
a4353898 MY |
17 | default 0 |
18 | ||
9553d16f ADK |
19 | config LD_VERSION |
20 | int | |
21 | default $(shell,$(LD) --version | $(srctree)/scripts/ld-version.sh) | |
22 | ||
469cb737 MY |
23 | config CC_IS_CLANG |
24 | def_bool $(success,$(CC) --version | head -n 1 | grep -q clang) | |
25 | ||
b744b43f ST |
26 | config LD_IS_LLD |
27 | def_bool $(success,$(LD) -v | head -n 1 | grep -q LLD) | |
28 | ||
469cb737 MY |
29 | config CLANG_VERSION |
30 | int | |
31 | default $(shell,$(srctree)/scripts/clang-version.sh $(CC)) | |
32 | ||
1a927fd3 MY |
33 | config CC_CAN_LINK |
34 | def_bool $(success,$(srctree)/scripts/cc-can-link.sh $(CC)) | |
35 | ||
e9666d10 MY |
36 | config CC_HAS_ASM_GOTO |
37 | def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC)) | |
38 | ||
5cf896fb | 39 | config TOOLS_SUPPORT_RELR |
2d122942 | 40 | def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh) |
5cf896fb | 41 | |
eb111869 RV |
42 | config CC_HAS_ASM_INLINE |
43 | def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null) | |
44 | ||
b99b87f7 PO |
45 | config CONSTRUCTORS |
46 | bool | |
87c9366e | 47 | depends on !UML |
b99b87f7 | 48 | |
e360adbe PZ |
49 | config IRQ_WORK |
50 | bool | |
e360adbe | 51 | |
10916706 | 52 | config BUILDTIME_TABLE_SORT |
1dbdc6f1 DD |
53 | bool |
54 | ||
c65eacbe AL |
55 | config THREAD_INFO_IN_TASK |
56 | bool | |
57 | help | |
58 | Select this to move thread_info off the stack into task_struct. To | |
59 | make this work, an arch will need to remove all thread_info fields | |
60 | except flags and fix any runtime bugs. | |
61 | ||
c6c314a6 AL |
62 | One subtle change that will be needed is to use try_get_task_stack() |
63 | and put_task_stack() in save_thread_stack_tsk() and get_wchan(). | |
64 | ||
ff0cfc66 | 65 | menu "General setup" |
1da177e4 | 66 | |
1da177e4 LT |
67 | config BROKEN |
68 | bool | |
1da177e4 LT |
69 | |
70 | config BROKEN_ON_SMP | |
71 | bool | |
72 | depends on BROKEN || !SMP | |
73 | default y | |
74 | ||
1da177e4 LT |
75 | config INIT_ENV_ARG_LIMIT |
76 | int | |
dd673bca AB |
77 | default 32 if !UML |
78 | default 128 if UML | |
1da177e4 | 79 | help |
34ad92c2 RD |
80 | Maximum of each of the number of arguments and environment |
81 | variables passed to init from the kernel command line. | |
1da177e4 | 82 | |
4bb16672 JS |
83 | config COMPILE_TEST |
84 | bool "Compile also drivers which will not load" | |
bc083a64 | 85 | depends on !UML |
4bb16672 JS |
86 | default n |
87 | help | |
88 | Some drivers can be compiled on a different platform than they are | |
89 | intended to be run on. Despite they cannot be loaded there (or even | |
90 | when they load they cannot be used due to missing HW support), | |
91 | developers still, opposing to distributors, might want to build such | |
92 | drivers to compile-test them. | |
93 | ||
94 | If you are a developer and want to build everything available, say Y | |
95 | here. If you are a user/distributor, say N here to exclude useless | |
96 | drivers to be distributed. | |
97 | ||
d6fc9fcb MY |
98 | config UAPI_HEADER_TEST |
99 | bool "Compile test UAPI headers" | |
fcbb8461 | 100 | depends on HEADERS_INSTALL && CC_CAN_LINK |
d6fc9fcb MY |
101 | help |
102 | Compile test headers exported to user-space to ensure they are | |
103 | self-contained, i.e. compilable as standalone units. | |
104 | ||
105 | If you are a developer or tester and want to ensure the exported | |
106 | headers are self-contained, say Y here. Otherwise, choose N. | |
107 | ||
1da177e4 LT |
108 | config LOCALVERSION |
109 | string "Local version - append to kernel release" | |
110 | help | |
111 | Append an extra string to the end of your kernel version. | |
112 | This will show up when you type uname, for example. | |
113 | The string you set here will be appended after the contents of | |
114 | any files with a filename matching localversion* in your | |
115 | object and source tree, in that order. Your total string can | |
116 | be a maximum of 64 characters. | |
117 | ||
aaebf433 RA |
118 | config LOCALVERSION_AUTO |
119 | bool "Automatically append version information to the version string" | |
120 | default y | |
ac3339ba | 121 | depends on !COMPILE_TEST |
aaebf433 RA |
122 | help |
123 | This will try to automatically determine if the current tree is a | |
6e5a5420 RD |
124 | release tree by looking for git tags that belong to the current |
125 | top of tree revision. | |
aaebf433 RA |
126 | |
127 | A string of the format -gxxxxxxxx will be added to the localversion | |
6e5a5420 | 128 | if a git-based tree is found. The string generated by this will be |
aaebf433 | 129 | appended after any matching localversion* files, and after the value |
6e5a5420 | 130 | set in CONFIG_LOCALVERSION. |
aaebf433 | 131 | |
6e5a5420 RD |
132 | (The actual string used here is the first eight characters produced |
133 | by running the command: | |
134 | ||
135 | $ git rev-parse --verify HEAD | |
136 | ||
137 | which is done within the script "scripts/setlocalversion".) | |
aaebf433 | 138 | |
9afb719e | 139 | config BUILD_SALT |
e8cf4e9c KK |
140 | string "Build ID Salt" |
141 | default "" | |
142 | help | |
143 | The build ID is used to link binaries and their debug info. Setting | |
144 | this option will use the value in the calculation of the build id. | |
145 | This is mostly useful for distributions which want to ensure the | |
146 | build is unique between builds. It's safe to leave the default. | |
9afb719e | 147 | |
2e9f3bdd PA |
148 | config HAVE_KERNEL_GZIP |
149 | bool | |
150 | ||
151 | config HAVE_KERNEL_BZIP2 | |
152 | bool | |
153 | ||
154 | config HAVE_KERNEL_LZMA | |
155 | bool | |
156 | ||
3ebe1243 LC |
157 | config HAVE_KERNEL_XZ |
158 | bool | |
159 | ||
7dd65feb AT |
160 | config HAVE_KERNEL_LZO |
161 | bool | |
162 | ||
e76e1fdf KL |
163 | config HAVE_KERNEL_LZ4 |
164 | bool | |
165 | ||
f16466af VG |
166 | config HAVE_KERNEL_UNCOMPRESSED |
167 | bool | |
168 | ||
30d65dbf | 169 | choice |
2e9f3bdd PA |
170 | prompt "Kernel compression mode" |
171 | default KERNEL_GZIP | |
f16466af | 172 | depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 || HAVE_KERNEL_UNCOMPRESSED |
2e9f3bdd | 173 | help |
30d65dbf AK |
174 | The linux kernel is a kind of self-extracting executable. |
175 | Several compression algorithms are available, which differ | |
176 | in efficiency, compression and decompression speed. | |
177 | Compression speed is only relevant when building a kernel. | |
178 | Decompression speed is relevant at each boot. | |
179 | ||
180 | If you have any problems with bzip2 or lzma compressed | |
181 | kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older | |
182 | version of this functionality (bzip2 only), for 2.4, was | |
183 | supplied by Christian Ludwig) | |
184 | ||
185 | High compression options are mostly useful for users, who | |
186 | are low on disk space (embedded systems), but for whom ram | |
187 | size matters less. | |
188 | ||
189 | If in doubt, select 'gzip' | |
190 | ||
191 | config KERNEL_GZIP | |
2e9f3bdd PA |
192 | bool "Gzip" |
193 | depends on HAVE_KERNEL_GZIP | |
194 | help | |
7dd65feb AT |
195 | The old and tried gzip compression. It provides a good balance |
196 | between compression ratio and decompression speed. | |
30d65dbf AK |
197 | |
198 | config KERNEL_BZIP2 | |
199 | bool "Bzip2" | |
2e9f3bdd | 200 | depends on HAVE_KERNEL_BZIP2 |
30d65dbf AK |
201 | help |
202 | Its compression ratio and speed is intermediate. | |
0a4dd35c | 203 | Decompression speed is slowest among the choices. The kernel |
2e9f3bdd PA |
204 | size is about 10% smaller with bzip2, in comparison to gzip. |
205 | Bzip2 uses a large amount of memory. For modern kernels you | |
206 | will need at least 8MB RAM or more for booting. | |
30d65dbf AK |
207 | |
208 | config KERNEL_LZMA | |
2e9f3bdd PA |
209 | bool "LZMA" |
210 | depends on HAVE_KERNEL_LZMA | |
211 | help | |
0a4dd35c RD |
212 | This compression algorithm's ratio is best. Decompression speed |
213 | is between gzip and bzip2. Compression is slowest. | |
214 | The kernel size is about 33% smaller with LZMA in comparison to gzip. | |
30d65dbf | 215 | |
3ebe1243 LC |
216 | config KERNEL_XZ |
217 | bool "XZ" | |
218 | depends on HAVE_KERNEL_XZ | |
219 | help | |
220 | XZ uses the LZMA2 algorithm and instruction set specific | |
221 | BCJ filters which can improve compression ratio of executable | |
222 | code. The size of the kernel is about 30% smaller with XZ in | |
223 | comparison to gzip. On architectures for which there is a BCJ | |
224 | filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ | |
225 | will create a few percent smaller kernel than plain LZMA. | |
226 | ||
227 | The speed is about the same as with LZMA: The decompression | |
228 | speed of XZ is better than that of bzip2 but worse than gzip | |
229 | and LZO. Compression is slow. | |
230 | ||
7dd65feb AT |
231 | config KERNEL_LZO |
232 | bool "LZO" | |
233 | depends on HAVE_KERNEL_LZO | |
234 | help | |
0a4dd35c | 235 | Its compression ratio is the poorest among the choices. The kernel |
681b3049 | 236 | size is about 10% bigger than gzip; however its speed |
7dd65feb AT |
237 | (both compression and decompression) is the fastest. |
238 | ||
e76e1fdf KL |
239 | config KERNEL_LZ4 |
240 | bool "LZ4" | |
241 | depends on HAVE_KERNEL_LZ4 | |
242 | help | |
243 | LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding. | |
244 | A preliminary version of LZ4 de/compression tool is available at | |
245 | <https://code.google.com/p/lz4/>. | |
246 | ||
247 | Its compression ratio is worse than LZO. The size of the kernel | |
248 | is about 8% bigger than LZO. But the decompression speed is | |
249 | faster than LZO. | |
250 | ||
f16466af VG |
251 | config KERNEL_UNCOMPRESSED |
252 | bool "None" | |
253 | depends on HAVE_KERNEL_UNCOMPRESSED | |
254 | help | |
255 | Produce uncompressed kernel image. This option is usually not what | |
256 | you want. It is useful for debugging the kernel in slow simulation | |
257 | environments, where decompressing and moving the kernel is awfully | |
258 | slow. This option allows early boot code to skip the decompressor | |
259 | and jump right at uncompressed kernel image. | |
260 | ||
30d65dbf AK |
261 | endchoice |
262 | ||
ada4ab7a CD |
263 | config DEFAULT_INIT |
264 | string "Default init path" | |
265 | default "" | |
266 | help | |
267 | This option determines the default init for the system if no init= | |
268 | option is passed on the kernel command line. If the requested path is | |
269 | not present, we will still then move on to attempting further | |
270 | locations (e.g. /sbin/init, etc). If this is empty, we will just use | |
271 | the fallback list when init= is not passed. | |
272 | ||
bd5dc17b JT |
273 | config DEFAULT_HOSTNAME |
274 | string "Default hostname" | |
275 | default "(none)" | |
276 | help | |
277 | This option determines the default system hostname before userspace | |
278 | calls sethostname(2). The kernel traditionally uses "(none)" here, | |
279 | but you may wish to use a different default here to make a minimal | |
280 | system more usable with less configuration. | |
281 | ||
17c46a6a CH |
282 | # |
283 | # For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can | |
284 | # add proper SWAP support to them, in which case this can be remove. | |
285 | # | |
286 | config ARCH_NO_SWAP | |
287 | bool | |
288 | ||
1da177e4 LT |
289 | config SWAP |
290 | bool "Support for paging of anonymous memory (swap)" | |
17c46a6a | 291 | depends on MMU && BLOCK && !ARCH_NO_SWAP |
1da177e4 LT |
292 | default y |
293 | help | |
294 | This option allows you to choose whether you want to have support | |
92c3504e | 295 | for so called swap devices or swap files in your kernel that are |
1da177e4 LT |
296 | used to provide more virtual memory than the actual RAM present |
297 | in your computer. If unsure say Y. | |
298 | ||
299 | config SYSVIPC | |
300 | bool "System V IPC" | |
1da177e4 LT |
301 | ---help--- |
302 | Inter Process Communication is a suite of library functions and | |
303 | system calls which let processes (running programs) synchronize and | |
304 | exchange information. It is generally considered to be a good thing, | |
305 | and some programs won't run unless you say Y here. In particular, if | |
306 | you want to run the DOS emulator dosemu under Linux (read the | |
307 | DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), | |
308 | you'll need to say Y here. | |
309 | ||
310 | You can find documentation about IPC with "info ipc" and also in | |
311 | section 6.4 of the Linux Programmer's Guide, available from | |
312 | <http://www.tldp.org/guides.html>. | |
313 | ||
a5494dcd EB |
314 | config SYSVIPC_SYSCTL |
315 | bool | |
316 | depends on SYSVIPC | |
317 | depends on SYSCTL | |
318 | default y | |
319 | ||
1da177e4 LT |
320 | config POSIX_MQUEUE |
321 | bool "POSIX Message Queues" | |
19c92399 | 322 | depends on NET |
1da177e4 LT |
323 | ---help--- |
324 | POSIX variant of message queues is a part of IPC. In POSIX message | |
325 | queues every message has a priority which decides about succession | |
326 | of receiving it by a process. If you want to compile and run | |
327 | programs written e.g. for Solaris with use of its POSIX message | |
b0e37650 | 328 | queues (functions mq_*) say Y here. |
1da177e4 LT |
329 | |
330 | POSIX message queues are visible as a filesystem called 'mqueue' | |
331 | and can be mounted somewhere if you want to do filesystem | |
332 | operations on message queues. | |
333 | ||
334 | If unsure, say Y. | |
335 | ||
bdc8e5f8 SH |
336 | config POSIX_MQUEUE_SYSCTL |
337 | bool | |
338 | depends on POSIX_MQUEUE | |
339 | depends on SYSCTL | |
340 | default y | |
341 | ||
226b4ccd KK |
342 | config CROSS_MEMORY_ATTACH |
343 | bool "Enable process_vm_readv/writev syscalls" | |
344 | depends on MMU | |
345 | default y | |
346 | help | |
347 | Enabling this option adds the system calls process_vm_readv and | |
348 | process_vm_writev which allow a process with the correct privileges | |
a2a368d9 | 349 | to directly read from or write to another process' address space. |
226b4ccd KK |
350 | See the man page for more details. |
351 | ||
69369a70 JT |
352 | config USELIB |
353 | bool "uselib syscall" | |
b2113a41 | 354 | def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION |
69369a70 JT |
355 | help |
356 | This option enables the uselib syscall, a system call used in the | |
357 | dynamic linker from libc5 and earlier. glibc does not use this | |
358 | system call. If you intend to run programs built on libc5 or | |
359 | earlier, you may need to enable this syscall. Current systems | |
360 | running glibc can safely disable this. | |
361 | ||
391dc69c FW |
362 | config AUDIT |
363 | bool "Auditing support" | |
364 | depends on NET | |
365 | help | |
366 | Enable auditing infrastructure that can be used with another | |
367 | kernel subsystem, such as SELinux (which requires this for | |
cb74ed27 PM |
368 | logging of avc messages output). System call auditing is included |
369 | on architectures which support it. | |
391dc69c | 370 | |
7a017721 AT |
371 | config HAVE_ARCH_AUDITSYSCALL |
372 | bool | |
373 | ||
391dc69c | 374 | config AUDITSYSCALL |
cb74ed27 | 375 | def_bool y |
7a017721 | 376 | depends on AUDIT && HAVE_ARCH_AUDITSYSCALL |
391dc69c FW |
377 | select FSNOTIFY |
378 | ||
391dc69c FW |
379 | source "kernel/irq/Kconfig" |
380 | source "kernel/time/Kconfig" | |
87a4c375 | 381 | source "kernel/Kconfig.preempt" |
391dc69c FW |
382 | |
383 | menu "CPU/Task time and stats accounting" | |
384 | ||
abf917cd FW |
385 | config VIRT_CPU_ACCOUNTING |
386 | bool | |
387 | ||
fdf9c356 FW |
388 | choice |
389 | prompt "Cputime accounting" | |
390 | default TICK_CPU_ACCOUNTING if !PPC64 | |
02fc8d37 | 391 | default VIRT_CPU_ACCOUNTING_NATIVE if PPC64 |
fdf9c356 FW |
392 | |
393 | # Kind of a stub config for the pure tick based cputime accounting | |
394 | config TICK_CPU_ACCOUNTING | |
395 | bool "Simple tick based cputime accounting" | |
c58b0df1 | 396 | depends on !S390 && !NO_HZ_FULL |
fdf9c356 FW |
397 | help |
398 | This is the basic tick based cputime accounting that maintains | |
399 | statistics about user, system and idle time spent on per jiffies | |
400 | granularity. | |
401 | ||
402 | If unsure, say Y. | |
403 | ||
abf917cd | 404 | config VIRT_CPU_ACCOUNTING_NATIVE |
b952741c | 405 | bool "Deterministic task and CPU time accounting" |
c58b0df1 | 406 | depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL |
abf917cd | 407 | select VIRT_CPU_ACCOUNTING |
b952741c FW |
408 | help |
409 | Select this option to enable more accurate task and CPU time | |
410 | accounting. This is done by reading a CPU counter on each | |
411 | kernel entry and exit and on transitions within the kernel | |
412 | between system, softirq and hardirq state, so there is a | |
413 | small performance impact. In the case of s390 or IBM POWER > 5, | |
414 | this also enables accounting of stolen time on logically-partitioned | |
415 | systems. | |
416 | ||
abf917cd FW |
417 | config VIRT_CPU_ACCOUNTING_GEN |
418 | bool "Full dynticks CPU time accounting" | |
ff3fb254 | 419 | depends on HAVE_CONTEXT_TRACKING |
554b0004 | 420 | depends on HAVE_VIRT_CPU_ACCOUNTING_GEN |
041a1574 | 421 | depends on GENERIC_CLOCKEVENTS |
abf917cd FW |
422 | select VIRT_CPU_ACCOUNTING |
423 | select CONTEXT_TRACKING | |
424 | help | |
425 | Select this option to enable task and CPU time accounting on full | |
426 | dynticks systems. This accounting is implemented by watching every | |
427 | kernel-user boundaries using the context tracking subsystem. | |
428 | The accounting is thus performed at the expense of some significant | |
429 | overhead. | |
430 | ||
431 | For now this is only useful if you are working on the full | |
432 | dynticks subsystem development. | |
433 | ||
434 | If unsure, say N. | |
435 | ||
b58c3584 RR |
436 | endchoice |
437 | ||
fdf9c356 FW |
438 | config IRQ_TIME_ACCOUNTING |
439 | bool "Fine granularity task level IRQ time accounting" | |
b58c3584 | 440 | depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE |
fdf9c356 FW |
441 | help |
442 | Select this option to enable fine granularity task irq time | |
443 | accounting. This is done by reading a timestamp on each | |
444 | transitions between softirq and hardirq state, so there can be a | |
445 | small performance impact. | |
446 | ||
447 | If in doubt, say N here. | |
448 | ||
11d4afd4 VG |
449 | config HAVE_SCHED_AVG_IRQ |
450 | def_bool y | |
451 | depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING | |
452 | depends on SMP | |
453 | ||
76504793 TG |
454 | config SCHED_THERMAL_PRESSURE |
455 | bool "Enable periodic averaging of thermal pressure" | |
456 | depends on SMP | |
457 | ||
1da177e4 LT |
458 | config BSD_PROCESS_ACCT |
459 | bool "BSD Process Accounting" | |
2813893f | 460 | depends on MULTIUSER |
1da177e4 LT |
461 | help |
462 | If you say Y here, a user level program will be able to instruct the | |
463 | kernel (via a special system call) to write process accounting | |
464 | information to a file: whenever a process exits, information about | |
465 | that process will be appended to the file by the kernel. The | |
466 | information includes things such as creation time, owning user, | |
467 | command name, memory usage, controlling terminal etc. (the complete | |
468 | list is in the struct acct in <file:include/linux/acct.h>). It is | |
469 | up to the user level program to do useful things with this | |
470 | information. This is generally a good idea, so say Y. | |
471 | ||
472 | config BSD_PROCESS_ACCT_V3 | |
473 | bool "BSD Process Accounting version 3 file format" | |
474 | depends on BSD_PROCESS_ACCT | |
475 | default n | |
476 | help | |
477 | If you say Y here, the process accounting information is written | |
478 | in a new file format that also logs the process IDs of each | |
3903bf94 | 479 | process and its parent. Note that this file format is incompatible |
1da177e4 LT |
480 | with previous v0/v1/v2 file formats, so you will need updated tools |
481 | for processing it. A preliminary version of these tools is available | |
37a4c940 | 482 | at <http://www.gnu.org/software/acct/>. |
1da177e4 | 483 | |
c757249a | 484 | config TASKSTATS |
19c92399 | 485 | bool "Export task/process statistics through netlink" |
c757249a | 486 | depends on NET |
2813893f | 487 | depends on MULTIUSER |
c757249a SN |
488 | default n |
489 | help | |
490 | Export selected statistics for tasks/processes through the | |
491 | generic netlink interface. Unlike BSD process accounting, the | |
492 | statistics are available during the lifetime of tasks/processes as | |
493 | responses to commands. Like BSD accounting, they are sent to user | |
494 | space on task exit. | |
495 | ||
496 | Say N if unsure. | |
497 | ||
ca74e92b | 498 | config TASK_DELAY_ACCT |
19c92399 | 499 | bool "Enable per-task delay accounting" |
6f44993f | 500 | depends on TASKSTATS |
f6db8347 | 501 | select SCHED_INFO |
ca74e92b SN |
502 | help |
503 | Collect information on time spent by a task waiting for system | |
504 | resources like cpu, synchronous block I/O completion and swapping | |
505 | in pages. Such statistics can help in setting a task's priorities | |
506 | relative to other tasks for cpu, io, rss limits etc. | |
507 | ||
508 | Say N if unsure. | |
509 | ||
18f705f4 | 510 | config TASK_XACCT |
19c92399 | 511 | bool "Enable extended accounting over taskstats" |
18f705f4 AD |
512 | depends on TASKSTATS |
513 | help | |
514 | Collect extended task accounting data and send the data | |
515 | to userland for processing over the taskstats interface. | |
516 | ||
517 | Say N if unsure. | |
518 | ||
519 | config TASK_IO_ACCOUNTING | |
19c92399 | 520 | bool "Enable per-task storage I/O accounting" |
18f705f4 AD |
521 | depends on TASK_XACCT |
522 | help | |
523 | Collect information on the number of bytes of storage I/O which this | |
524 | task has caused. | |
525 | ||
526 | Say N if unsure. | |
527 | ||
eb414681 JW |
528 | config PSI |
529 | bool "Pressure stall information tracking" | |
530 | help | |
531 | Collect metrics that indicate how overcommitted the CPU, memory, | |
532 | and IO capacity are in the system. | |
533 | ||
534 | If you say Y here, the kernel will create /proc/pressure/ with the | |
535 | pressure statistics files cpu, memory, and io. These will indicate | |
536 | the share of walltime in which some or all tasks in the system are | |
537 | delayed due to contention of the respective resource. | |
538 | ||
2ce7135a JW |
539 | In kernels with cgroup support, cgroups (cgroup2 only) will |
540 | have cpu.pressure, memory.pressure, and io.pressure files, | |
541 | which aggregate pressure stalls for the grouped tasks only. | |
542 | ||
c3123552 | 543 | For more details see Documentation/accounting/psi.rst. |
eb414681 JW |
544 | |
545 | Say N if unsure. | |
546 | ||
e0c27447 JW |
547 | config PSI_DEFAULT_DISABLED |
548 | bool "Require boot parameter to enable pressure stall information tracking" | |
549 | default n | |
550 | depends on PSI | |
551 | help | |
552 | If set, pressure stall information tracking will be disabled | |
428a1cb4 BS |
553 | per default but can be enabled through passing psi=1 on the |
554 | kernel commandline during boot. | |
e0c27447 | 555 | |
7b2489d3 JW |
556 | This feature adds some code to the task wakeup and sleep |
557 | paths of the scheduler. The overhead is too low to affect | |
558 | common scheduling-intense workloads in practice (such as | |
559 | webservers, memcache), but it does show up in artificial | |
560 | scheduler stress tests, such as hackbench. | |
561 | ||
562 | If you are paranoid and not sure what the kernel will be | |
563 | used for, say Y. | |
564 | ||
565 | Say N if unsure. | |
566 | ||
391dc69c | 567 | endmenu # "CPU/Task time and stats accounting" |
d9817ebe | 568 | |
5c4991e2 FW |
569 | config CPU_ISOLATION |
570 | bool "CPU isolation" | |
414a2dc1 | 571 | depends on SMP || COMPILE_TEST |
2c43838c | 572 | default y |
5c4991e2 FW |
573 | help |
574 | Make sure that CPUs running critical tasks are not disturbed by | |
575 | any source of "noise" such as unbound workqueues, timers, kthreads... | |
2c43838c FW |
576 | Unbound jobs get offloaded to housekeeping CPUs. This is driven by |
577 | the "isolcpus=" boot parameter. | |
578 | ||
579 | Say Y if unsure. | |
5c4991e2 | 580 | |
0af92d46 | 581 | source "kernel/rcu/Kconfig" |
c903ff83 | 582 | |
de5b56ba VG |
583 | config BUILD_BIN2C |
584 | bool | |
585 | default n | |
586 | ||
1da177e4 | 587 | config IKCONFIG |
f2443ab6 | 588 | tristate "Kernel .config support" |
1da177e4 LT |
589 | ---help--- |
590 | This option enables the complete Linux kernel ".config" file | |
591 | contents to be saved in the kernel. It provides documentation | |
592 | of which kernel options are used in a running kernel or in an | |
593 | on-disk kernel. This information can be extracted from the kernel | |
594 | image file with the script scripts/extract-ikconfig and used as | |
595 | input to rebuild the current kernel or to build another kernel. | |
596 | It can also be extracted from a running kernel by reading | |
597 | /proc/config.gz if enabled (below). | |
598 | ||
599 | config IKCONFIG_PROC | |
600 | bool "Enable access to .config through /proc/config.gz" | |
601 | depends on IKCONFIG && PROC_FS | |
602 | ---help--- | |
603 | This option enables access to the kernel configuration file | |
604 | through /proc/config.gz. | |
605 | ||
f7b101d3 JFG |
606 | config IKHEADERS |
607 | tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz" | |
608 | depends on SYSFS | |
609 | help | |
610 | This option enables access to the in-kernel headers that are generated during | |
611 | the build process. These can be used to build eBPF tracing programs, | |
612 | or similar programs. If you build the headers as a module, a module called | |
613 | kheaders.ko is built which can be loaded on-demand to get access to headers. | |
43d8ce9d | 614 | |
794543a2 AJS |
615 | config LOG_BUF_SHIFT |
616 | int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" | |
fb39f98d | 617 | range 12 25 |
f17a32e9 | 618 | default 17 |
361e9dfb | 619 | depends on PRINTK |
794543a2 | 620 | help |
23b2899f LR |
621 | Select the minimal kernel log buffer size as a power of 2. |
622 | The final size is affected by LOG_CPU_MAX_BUF_SHIFT config | |
623 | parameter, see below. Any higher size also might be forced | |
624 | by "log_buf_len" boot parameter. | |
625 | ||
f17a32e9 | 626 | Examples: |
23b2899f | 627 | 17 => 128 KB |
f17a32e9 | 628 | 16 => 64 KB |
23b2899f LR |
629 | 15 => 32 KB |
630 | 14 => 16 KB | |
794543a2 AJS |
631 | 13 => 8 KB |
632 | 12 => 4 KB | |
633 | ||
23b2899f LR |
634 | config LOG_CPU_MAX_BUF_SHIFT |
635 | int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" | |
2240a31d | 636 | depends on SMP |
23b2899f LR |
637 | range 0 21 |
638 | default 12 if !BASE_SMALL | |
639 | default 0 if BASE_SMALL | |
361e9dfb | 640 | depends on PRINTK |
23b2899f LR |
641 | help |
642 | This option allows to increase the default ring buffer size | |
643 | according to the number of CPUs. The value defines the contribution | |
644 | of each CPU as a power of 2. The used space is typically only few | |
645 | lines however it might be much more when problems are reported, | |
646 | e.g. backtraces. | |
647 | ||
648 | The increased size means that a new buffer has to be allocated and | |
649 | the original static one is unused. It makes sense only on systems | |
650 | with more CPUs. Therefore this value is used only when the sum of | |
651 | contributions is greater than the half of the default kernel ring | |
652 | buffer as defined by LOG_BUF_SHIFT. The default values are set | |
653 | so that more than 64 CPUs are needed to trigger the allocation. | |
654 | ||
655 | Also this option is ignored when "log_buf_len" kernel parameter is | |
656 | used as it forces an exact (power of two) size of the ring buffer. | |
657 | ||
658 | The number of possible CPUs is used for this computation ignoring | |
5e0d8d59 GU |
659 | hotplugging making the computation optimal for the worst case |
660 | scenario while allowing a simple algorithm to be used from bootup. | |
23b2899f LR |
661 | |
662 | Examples shift values and their meaning: | |
663 | 17 => 128 KB for each CPU | |
664 | 16 => 64 KB for each CPU | |
665 | 15 => 32 KB for each CPU | |
666 | 14 => 16 KB for each CPU | |
667 | 13 => 8 KB for each CPU | |
668 | 12 => 4 KB for each CPU | |
669 | ||
f92bac3b SS |
670 | config PRINTK_SAFE_LOG_BUF_SHIFT |
671 | int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)" | |
427934b8 PM |
672 | range 10 21 |
673 | default 13 | |
f92bac3b | 674 | depends on PRINTK |
427934b8 | 675 | help |
f92bac3b SS |
676 | Select the size of an alternate printk per-CPU buffer where messages |
677 | printed from usafe contexts are temporary stored. One example would | |
678 | be NMI messages, another one - printk recursion. The messages are | |
679 | copied to the main log buffer in a safe context to avoid a deadlock. | |
680 | The value defines the size as a power of 2. | |
427934b8 | 681 | |
f92bac3b | 682 | Those messages are rare and limited. The largest one is when |
427934b8 PM |
683 | a backtrace is printed. It usually fits into 4KB. Select |
684 | 8KB if you want to be on the safe side. | |
685 | ||
686 | Examples: | |
687 | 17 => 128 KB for each CPU | |
688 | 16 => 64 KB for each CPU | |
689 | 15 => 32 KB for each CPU | |
690 | 14 => 16 KB for each CPU | |
691 | 13 => 8 KB for each CPU | |
692 | 12 => 4 KB for each CPU | |
693 | ||
a5574cf6 IM |
694 | # |
695 | # Architectures with an unreliable sched_clock() should select this: | |
696 | # | |
697 | config HAVE_UNSTABLE_SCHED_CLOCK | |
698 | bool | |
699 | ||
38ff87f7 SB |
700 | config GENERIC_SCHED_CLOCK |
701 | bool | |
702 | ||
69842cba PB |
703 | menu "Scheduler features" |
704 | ||
705 | config UCLAMP_TASK | |
706 | bool "Enable utilization clamping for RT/FAIR tasks" | |
707 | depends on CPU_FREQ_GOV_SCHEDUTIL | |
708 | help | |
709 | This feature enables the scheduler to track the clamped utilization | |
710 | of each CPU based on RUNNABLE tasks scheduled on that CPU. | |
711 | ||
712 | With this option, the user can specify the min and max CPU | |
713 | utilization allowed for RUNNABLE tasks. The max utilization defines | |
714 | the maximum frequency a task should use while the min utilization | |
715 | defines the minimum frequency it should use. | |
716 | ||
717 | Both min and max utilization clamp values are hints to the scheduler, | |
718 | aiming at improving its frequency selection policy, but they do not | |
719 | enforce or grant any specific bandwidth for tasks. | |
720 | ||
721 | If in doubt, say N. | |
722 | ||
723 | config UCLAMP_BUCKETS_COUNT | |
724 | int "Number of supported utilization clamp buckets" | |
725 | range 5 20 | |
726 | default 5 | |
727 | depends on UCLAMP_TASK | |
728 | help | |
729 | Defines the number of clamp buckets to use. The range of each bucket | |
730 | will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the | |
731 | number of clamp buckets the finer their granularity and the higher | |
732 | the precision of clamping aggregation and tracking at run-time. | |
733 | ||
734 | For example, with the minimum configuration value we will have 5 | |
735 | clamp buckets tracking 20% utilization each. A 25% boosted tasks will | |
736 | be refcounted in the [20..39]% bucket and will set the bucket clamp | |
737 | effective value to 25%. | |
738 | If a second 30% boosted task should be co-scheduled on the same CPU, | |
739 | that task will be refcounted in the same bucket of the first task and | |
740 | it will boost the bucket clamp effective value to 30%. | |
741 | The clamp effective value of a bucket is reset to its nominal value | |
742 | (20% in the example above) when there are no more tasks refcounted in | |
743 | that bucket. | |
744 | ||
745 | An additional boost/capping margin can be added to some tasks. In the | |
746 | example above the 25% task will be boosted to 30% until it exits the | |
747 | CPU. If that should be considered not acceptable on certain systems, | |
748 | it's always possible to reduce the margin by increasing the number of | |
749 | clamp buckets to trade off used memory for run-time tracking | |
750 | precision. | |
751 | ||
752 | If in doubt, use the default value. | |
753 | ||
754 | endmenu | |
755 | ||
be3a7284 AA |
756 | # |
757 | # For architectures that want to enable the support for NUMA-affine scheduler | |
758 | # balancing logic: | |
759 | # | |
760 | config ARCH_SUPPORTS_NUMA_BALANCING | |
761 | bool | |
762 | ||
72b252ae MG |
763 | # |
764 | # For architectures that prefer to flush all TLBs after a number of pages | |
765 | # are unmapped instead of sending one IPI per page to flush. The architecture | |
766 | # must provide guarantees on what happens if a clean TLB cache entry is | |
767 | # written after the unmap. Details are in mm/rmap.c near the check for | |
768 | # should_defer_flush. The architecture should also consider if the full flush | |
769 | # and the refill costs are offset by the savings of sending fewer IPIs. | |
770 | config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH | |
771 | bool | |
772 | ||
c12d3362 | 773 | config CC_HAS_INT128 |
3a7c7331 | 774 | def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT |
c12d3362 | 775 | |
be5e610c PZ |
776 | # |
777 | # For architectures that know their GCC __int128 support is sound | |
778 | # | |
779 | config ARCH_SUPPORTS_INT128 | |
780 | bool | |
781 | ||
be3a7284 AA |
782 | # For architectures that (ab)use NUMA to represent different memory regions |
783 | # all cpu-local but of different latencies, such as SuperH. | |
784 | # | |
785 | config ARCH_WANT_NUMA_VARIABLE_LOCALITY | |
786 | bool | |
787 | ||
be3a7284 AA |
788 | config NUMA_BALANCING |
789 | bool "Memory placement aware NUMA scheduler" | |
be3a7284 AA |
790 | depends on ARCH_SUPPORTS_NUMA_BALANCING |
791 | depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY | |
792 | depends on SMP && NUMA && MIGRATION | |
793 | help | |
794 | This option adds support for automatic NUMA aware memory/task placement. | |
795 | The mechanism is quite primitive and is based on migrating memory when | |
6d56a410 | 796 | it has references to the node the task is running on. |
be3a7284 AA |
797 | |
798 | This system will be inactive on UMA systems. | |
799 | ||
6f7c97e8 AK |
800 | config NUMA_BALANCING_DEFAULT_ENABLED |
801 | bool "Automatically enable NUMA aware memory/task placement" | |
802 | default y | |
803 | depends on NUMA_BALANCING | |
804 | help | |
805 | If set, automatic NUMA balancing will be enabled if running on a NUMA | |
806 | machine. | |
807 | ||
23964d2d | 808 | menuconfig CGROUPS |
6341e62b | 809 | bool "Control Group support" |
2bd59d48 | 810 | select KERNFS |
5cdc38f9 | 811 | help |
23964d2d | 812 | This option adds support for grouping sets of processes together, for |
5cdc38f9 KH |
813 | use with process control subsystems such as Cpusets, CFS, memory |
814 | controls or device isolation. | |
815 | See | |
d6a3b247 | 816 | - Documentation/scheduler/sched-design-CFS.rst (CFS) |
da82c92f | 817 | - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation |
45ce80fb | 818 | and resource control) |
5cdc38f9 KH |
819 | |
820 | Say N if unsure. | |
821 | ||
23964d2d LZ |
822 | if CGROUPS |
823 | ||
3e32cb2e | 824 | config PAGE_COUNTER |
e8cf4e9c | 825 | bool |
3e32cb2e | 826 | |
c255a458 | 827 | config MEMCG |
a0166ec4 | 828 | bool "Memory controller" |
3e32cb2e | 829 | select PAGE_COUNTER |
79bd9814 | 830 | select EVENTFD |
00f0b825 | 831 | help |
a0166ec4 | 832 | Provides control over the memory footprint of tasks in a cgroup. |
00f0b825 | 833 | |
c255a458 | 834 | config MEMCG_SWAP |
2d1c4980 | 835 | bool |
c255a458 | 836 | depends on MEMCG && SWAP |
a42c390c | 837 | default y |
c077719b | 838 | |
84c07d11 KT |
839 | config MEMCG_KMEM |
840 | bool | |
841 | depends on MEMCG && !SLOB | |
842 | default y | |
843 | ||
6bf024e6 JW |
844 | config BLK_CGROUP |
845 | bool "IO controller" | |
846 | depends on BLOCK | |
2bc64a20 | 847 | default n |
6bf024e6 JW |
848 | ---help--- |
849 | Generic block IO controller cgroup interface. This is the common | |
850 | cgroup interface which should be used by various IO controlling | |
851 | policies. | |
2bc64a20 | 852 | |
6bf024e6 JW |
853 | Currently, CFQ IO scheduler uses it to recognize task groups and |
854 | control disk bandwidth allocation (proportional time slice allocation) | |
855 | to such task groups. It is also used by bio throttling logic in | |
856 | block layer to implement upper limit in IO rates on a device. | |
e5d1367f | 857 | |
6bf024e6 JW |
858 | This option only enables generic Block IO controller infrastructure. |
859 | One needs to also enable actual IO controlling logic/policy. For | |
860 | enabling proportional weight division of disk bandwidth in CFQ, set | |
7baf2199 | 861 | CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set |
6bf024e6 JW |
862 | CONFIG_BLK_DEV_THROTTLING=y. |
863 | ||
da82c92f | 864 | See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information. |
6bf024e6 | 865 | |
6bf024e6 JW |
866 | config CGROUP_WRITEBACK |
867 | bool | |
868 | depends on MEMCG && BLK_CGROUP | |
869 | default y | |
e5d1367f | 870 | |
7c941438 | 871 | menuconfig CGROUP_SCHED |
a0166ec4 | 872 | bool "CPU controller" |
7c941438 DG |
873 | default n |
874 | help | |
875 | This feature lets CPU scheduler recognize task groups and control CPU | |
876 | bandwidth allocation to such task groups. It uses cgroups to group | |
877 | tasks. | |
878 | ||
879 | if CGROUP_SCHED | |
880 | config FAIR_GROUP_SCHED | |
881 | bool "Group scheduling for SCHED_OTHER" | |
882 | depends on CGROUP_SCHED | |
883 | default CGROUP_SCHED | |
884 | ||
ab84d31e PT |
885 | config CFS_BANDWIDTH |
886 | bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" | |
ab84d31e PT |
887 | depends on FAIR_GROUP_SCHED |
888 | default n | |
889 | help | |
890 | This option allows users to define CPU bandwidth rates (limits) for | |
891 | tasks running within the fair group scheduler. Groups with no limit | |
892 | set are considered to be unconstrained and will run with no | |
893 | restriction. | |
d6a3b247 | 894 | See Documentation/scheduler/sched-bwc.rst for more information. |
ab84d31e | 895 | |
7c941438 DG |
896 | config RT_GROUP_SCHED |
897 | bool "Group scheduling for SCHED_RR/FIFO" | |
7c941438 DG |
898 | depends on CGROUP_SCHED |
899 | default n | |
900 | help | |
901 | This feature lets you explicitly allocate real CPU bandwidth | |
32bd7eb5 | 902 | to task groups. If enabled, it will also make it impossible to |
7c941438 DG |
903 | schedule realtime tasks for non-root users until you allocate |
904 | realtime bandwidth for them. | |
d6a3b247 | 905 | See Documentation/scheduler/sched-rt-group.rst for more information. |
7c941438 DG |
906 | |
907 | endif #CGROUP_SCHED | |
908 | ||
2480c093 PB |
909 | config UCLAMP_TASK_GROUP |
910 | bool "Utilization clamping per group of tasks" | |
911 | depends on CGROUP_SCHED | |
912 | depends on UCLAMP_TASK | |
913 | default n | |
914 | help | |
915 | This feature enables the scheduler to track the clamped utilization | |
916 | of each CPU based on RUNNABLE tasks currently scheduled on that CPU. | |
917 | ||
918 | When this option is enabled, the user can specify a min and max | |
919 | CPU bandwidth which is allowed for each single task in a group. | |
920 | The max bandwidth allows to clamp the maximum frequency a task | |
921 | can use, while the min bandwidth allows to define a minimum | |
922 | frequency a task will always use. | |
923 | ||
924 | When task group based utilization clamping is enabled, an eventually | |
925 | specified task-specific clamp value is constrained by the cgroup | |
926 | specified clamp value. Both minimum and maximum task clamping cannot | |
927 | be bigger than the corresponding clamping defined at task group level. | |
928 | ||
929 | If in doubt, say N. | |
930 | ||
6bf024e6 JW |
931 | config CGROUP_PIDS |
932 | bool "PIDs controller" | |
933 | help | |
934 | Provides enforcement of process number limits in the scope of a | |
935 | cgroup. Any attempt to fork more processes than is allowed in the | |
936 | cgroup will fail. PIDs are fundamentally a global resource because it | |
937 | is fairly trivial to reach PID exhaustion before you reach even a | |
938 | conservative kmemcg limit. As a result, it is possible to grind a | |
939 | system to halt without being limited by other cgroup policies. The | |
6cc578df | 940 | PIDs controller is designed to stop this from happening. |
6bf024e6 JW |
941 | |
942 | It should be noted that organisational operations (such as attaching | |
98076833 | 943 | to a cgroup hierarchy) will *not* be blocked by the PIDs controller, |
6bf024e6 JW |
944 | since the PIDs limit only affects a process's ability to fork, not to |
945 | attach to a cgroup. | |
946 | ||
39d3e758 PP |
947 | config CGROUP_RDMA |
948 | bool "RDMA controller" | |
949 | help | |
950 | Provides enforcement of RDMA resources defined by IB stack. | |
951 | It is fairly easy for consumers to exhaust RDMA resources, which | |
952 | can result into resource unavailability to other consumers. | |
953 | RDMA controller is designed to stop this from happening. | |
954 | Attaching processes with active RDMA resources to the cgroup | |
955 | hierarchy is allowed even if can cross the hierarchy's limit. | |
956 | ||
6bf024e6 JW |
957 | config CGROUP_FREEZER |
958 | bool "Freezer controller" | |
959 | help | |
960 | Provides a way to freeze and unfreeze all tasks in a | |
961 | cgroup. | |
962 | ||
489c2a20 JW |
963 | This option affects the ORIGINAL cgroup interface. The cgroup2 memory |
964 | controller includes important in-kernel memory consumers per default. | |
965 | ||
966 | If you're using cgroup2, say N. | |
967 | ||
6bf024e6 JW |
968 | config CGROUP_HUGETLB |
969 | bool "HugeTLB controller" | |
970 | depends on HUGETLB_PAGE | |
971 | select PAGE_COUNTER | |
afc24d49 | 972 | default n |
6bf024e6 JW |
973 | help |
974 | Provides a cgroup controller for HugeTLB pages. | |
975 | When you enable this, you can put a per cgroup limit on HugeTLB usage. | |
976 | The limit is enforced during page fault. Since HugeTLB doesn't | |
977 | support page reclaim, enforcing the limit at page fault time implies | |
978 | that, the application will get SIGBUS signal if it tries to access | |
979 | HugeTLB pages beyond its limit. This requires the application to know | |
980 | beforehand how much HugeTLB pages it would require for its use. The | |
981 | control group is tracked in the third page lru pointer. This means | |
982 | that we cannot use the controller with huge page less than 3 pages. | |
afc24d49 | 983 | |
6bf024e6 JW |
984 | config CPUSETS |
985 | bool "Cpuset controller" | |
e1d4eeec | 986 | depends on SMP |
6bf024e6 JW |
987 | help |
988 | This option will let you create and manage CPUSETs which | |
989 | allow dynamically partitioning a system into sets of CPUs and | |
990 | Memory Nodes and assigning tasks to run only within those sets. | |
991 | This is primarily useful on large SMP or NUMA systems. | |
afc24d49 | 992 | |
6bf024e6 | 993 | Say N if unsure. |
afc24d49 | 994 | |
6bf024e6 JW |
995 | config PROC_PID_CPUSET |
996 | bool "Include legacy /proc/<pid>/cpuset file" | |
997 | depends on CPUSETS | |
998 | default y | |
afc24d49 | 999 | |
6bf024e6 JW |
1000 | config CGROUP_DEVICE |
1001 | bool "Device controller" | |
1002 | help | |
1003 | Provides a cgroup controller implementing whitelists for | |
1004 | devices which a process in the cgroup can mknod or open. | |
1005 | ||
1006 | config CGROUP_CPUACCT | |
1007 | bool "Simple CPU accounting controller" | |
1008 | help | |
1009 | Provides a simple controller for monitoring the | |
1010 | total CPU consumed by the tasks in a cgroup. | |
1011 | ||
1012 | config CGROUP_PERF | |
1013 | bool "Perf controller" | |
1014 | depends on PERF_EVENTS | |
1015 | help | |
1016 | This option extends the perf per-cpu mode to restrict monitoring | |
1017 | to threads which belong to the cgroup specified and run on the | |
6546b19f NK |
1018 | designated cpu. Or this can be used to have cgroup ID in samples |
1019 | so that it can monitor performance events among cgroups. | |
6bf024e6 JW |
1020 | |
1021 | Say N if unsure. | |
1022 | ||
30070984 DM |
1023 | config CGROUP_BPF |
1024 | bool "Support for eBPF programs attached to cgroups" | |
483c4933 AL |
1025 | depends on BPF_SYSCALL |
1026 | select SOCK_CGROUP_DATA | |
30070984 DM |
1027 | help |
1028 | Allow attaching eBPF programs to a cgroup using the bpf(2) | |
1029 | syscall command BPF_PROG_ATTACH. | |
1030 | ||
1031 | In which context these programs are accessed depends on the type | |
1032 | of attachment. For instance, programs that are attached using | |
1033 | BPF_CGROUP_INET_INGRESS will be executed on the ingress path of | |
1034 | inet sockets. | |
1035 | ||
6bf024e6 | 1036 | config CGROUP_DEBUG |
23b0be48 | 1037 | bool "Debug controller" |
afc24d49 | 1038 | default n |
23b0be48 | 1039 | depends on DEBUG_KERNEL |
6bf024e6 JW |
1040 | help |
1041 | This option enables a simple controller that exports | |
23b0be48 WL |
1042 | debugging information about the cgroups framework. This |
1043 | controller is for control cgroup debugging only. Its | |
1044 | interfaces are not stable. | |
afc24d49 | 1045 | |
6bf024e6 | 1046 | Say N. |
89e9b9e0 | 1047 | |
73b35147 AB |
1048 | config SOCK_CGROUP_DATA |
1049 | bool | |
1050 | default n | |
1051 | ||
23964d2d | 1052 | endif # CGROUPS |
c077719b | 1053 | |
8dd2a82c | 1054 | menuconfig NAMESPACES |
6a108a14 | 1055 | bool "Namespaces support" if EXPERT |
2813893f | 1056 | depends on MULTIUSER |
6a108a14 | 1057 | default !EXPERT |
c5289a69 PE |
1058 | help |
1059 | Provides the way to make tasks work with different objects using | |
1060 | the same id. For example same IPC id may refer to different objects | |
1061 | or same user id or pid may refer to different tasks when used in | |
1062 | different namespaces. | |
1063 | ||
8dd2a82c DL |
1064 | if NAMESPACES |
1065 | ||
58bfdd6d PE |
1066 | config UTS_NS |
1067 | bool "UTS namespace" | |
17a6d441 | 1068 | default y |
58bfdd6d PE |
1069 | help |
1070 | In this namespace tasks see different info provided with the | |
1071 | uname() system call | |
1072 | ||
769071ac AV |
1073 | config TIME_NS |
1074 | bool "TIME namespace" | |
660fd04f | 1075 | depends on GENERIC_VDSO_TIME_NS |
769071ac AV |
1076 | default y |
1077 | help | |
1078 | In this namespace boottime and monotonic clocks can be set. | |
1079 | The time will keep going with the same pace. | |
1080 | ||
ae5e1b22 PE |
1081 | config IPC_NS |
1082 | bool "IPC namespace" | |
8dd2a82c | 1083 | depends on (SYSVIPC || POSIX_MQUEUE) |
17a6d441 | 1084 | default y |
ae5e1b22 PE |
1085 | help |
1086 | In this namespace tasks work with IPC ids which correspond to | |
614b84cf | 1087 | different IPC objects in different namespaces. |
ae5e1b22 | 1088 | |
aee16ce7 | 1089 | config USER_NS |
19c92399 | 1090 | bool "User namespace" |
5673a94c | 1091 | default n |
aee16ce7 PE |
1092 | help |
1093 | This allows containers, i.e. vservers, to use user namespaces | |
1094 | to provide different user info for different servers. | |
e11f0ae3 EB |
1095 | |
1096 | When user namespaces are enabled in the kernel it is | |
d886f4e4 JW |
1097 | recommended that the MEMCG option also be enabled and that |
1098 | user-space use the memory control groups to limit the amount | |
1099 | of memory a memory unprivileged users can use. | |
e11f0ae3 | 1100 | |
aee16ce7 PE |
1101 | If unsure, say N. |
1102 | ||
74bd59bb | 1103 | config PID_NS |
9bd38c2c | 1104 | bool "PID Namespaces" |
17a6d441 | 1105 | default y |
74bd59bb | 1106 | help |
12d2b8f9 | 1107 | Support process id namespaces. This allows having multiple |
692105b8 | 1108 | processes with the same pid as long as they are in different |
74bd59bb PE |
1109 | pid namespaces. This is a building block of containers. |
1110 | ||
d6eb633f MH |
1111 | config NET_NS |
1112 | bool "Network namespace" | |
8dd2a82c | 1113 | depends on NET |
17a6d441 | 1114 | default y |
d6eb633f MH |
1115 | help |
1116 | Allow user space to create what appear to be multiple instances | |
1117 | of the network stack. | |
1118 | ||
8dd2a82c DL |
1119 | endif # NAMESPACES |
1120 | ||
5cb366bb AR |
1121 | config CHECKPOINT_RESTORE |
1122 | bool "Checkpoint/restore support" | |
1123 | select PROC_CHILDREN | |
1124 | default n | |
1125 | help | |
1126 | Enables additional kernel features in a sake of checkpoint/restore. | |
1127 | In particular it adds auxiliary prctl codes to setup process text, | |
1128 | data and heap segment sizes, and a few additional /proc filesystem | |
1129 | entries. | |
1130 | ||
1131 | If unsure, say N here. | |
1132 | ||
5091faa4 MG |
1133 | config SCHED_AUTOGROUP |
1134 | bool "Automatic process group scheduling" | |
5091faa4 MG |
1135 | select CGROUPS |
1136 | select CGROUP_SCHED | |
1137 | select FAIR_GROUP_SCHED | |
1138 | help | |
1139 | This option optimizes the scheduler for common desktop workloads by | |
1140 | automatically creating and populating task groups. This separation | |
1141 | of workloads isolates aggressive CPU burners (like build jobs) from | |
1142 | desktop applications. Task group autogeneration is currently based | |
1143 | upon task session. | |
1144 | ||
7af37bec | 1145 | config SYSFS_DEPRECATED |
5d6a4ea5 | 1146 | bool "Enable deprecated sysfs features to support old userspace tools" |
7af37bec DL |
1147 | depends on SYSFS |
1148 | default n | |
1149 | help | |
1150 | This option adds code that switches the layout of the "block" class | |
1151 | devices, to not show up in /sys/class/block/, but only in | |
1152 | /sys/block/. | |
1153 | ||
1154 | This switch is only active when the sysfs.deprecated=1 boot option is | |
1155 | passed or the SYSFS_DEPRECATED_V2 option is set. | |
1156 | ||
1157 | This option allows new kernels to run on old distributions and tools, | |
1158 | which might get confused by /sys/class/block/. Since 2007/2008 all | |
1159 | major distributions and tools handle this just fine. | |
1160 | ||
1161 | Recent distributions and userspace tools after 2009/2010 depend on | |
1162 | the existence of /sys/class/block/, and will not work with this | |
1163 | option enabled. | |
1164 | ||
1165 | Only if you are using a new kernel on an old distribution, you might | |
1166 | need to say Y here. | |
1167 | ||
1168 | config SYSFS_DEPRECATED_V2 | |
5d6a4ea5 | 1169 | bool "Enable deprecated sysfs features by default" |
7af37bec DL |
1170 | default n |
1171 | depends on SYSFS | |
1172 | depends on SYSFS_DEPRECATED | |
1173 | help | |
1174 | Enable deprecated sysfs by default. | |
1175 | ||
1176 | See the CONFIG_SYSFS_DEPRECATED option for more details about this | |
1177 | option. | |
1178 | ||
1179 | Only if you are using a new kernel on an old distribution, you might | |
1180 | need to say Y here. Even then, odds are you would not need it | |
1181 | enabled, you can always pass the boot option if absolutely necessary. | |
1182 | ||
1183 | config RELAY | |
1184 | bool "Kernel->user space relay support (formerly relayfs)" | |
26b5679e | 1185 | select IRQ_WORK |
7af37bec DL |
1186 | help |
1187 | This option enables support for relay interface support in | |
1188 | certain file systems (such as debugfs). | |
1189 | It is designed to provide an efficient mechanism for tools and | |
1190 | facilities to relay large amounts of data from kernel space to | |
1191 | user space. | |
1192 | ||
1193 | If unsure, say N. | |
1194 | ||
f991633d DG |
1195 | config BLK_DEV_INITRD |
1196 | bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" | |
f991633d DG |
1197 | help |
1198 | The initial RAM filesystem is a ramfs which is loaded by the | |
1199 | boot loader (loadlin or lilo) and that is mounted as root | |
1200 | before the normal boot procedure. It is typically used to | |
1201 | load modules needed to mount the "real" root file system, | |
8c27ceff | 1202 | etc. See <file:Documentation/admin-guide/initrd.rst> for details. |
f991633d DG |
1203 | |
1204 | If RAM disk support (BLK_DEV_RAM) is also included, this | |
1205 | also enables initial RAM disk (initrd) support and adds | |
1206 | 15 Kbytes (more on some other architectures) to the kernel size. | |
1207 | ||
1208 | If unsure say Y. | |
1209 | ||
c33df4ea JPS |
1210 | if BLK_DEV_INITRD |
1211 | ||
dbec4866 SR |
1212 | source "usr/Kconfig" |
1213 | ||
c33df4ea JPS |
1214 | endif |
1215 | ||
76db5a27 MH |
1216 | config BOOT_CONFIG |
1217 | bool "Boot config support" | |
2910b5aa | 1218 | select BLK_DEV_INITRD |
76db5a27 MH |
1219 | help |
1220 | Extra boot config allows system admin to pass a config file as | |
1221 | complemental extension of kernel cmdline when booting. | |
0947db01 | 1222 | The boot config file must be attached at the end of initramfs |
85c46b78 | 1223 | with checksum, size and magic word. |
0947db01 | 1224 | See <file:Documentation/admin-guide/bootconfig.rst> for details. |
76db5a27 MH |
1225 | |
1226 | If unsure, say Y. | |
1227 | ||
877417e6 AB |
1228 | choice |
1229 | prompt "Compiler optimization level" | |
2cc3ce24 | 1230 | default CC_OPTIMIZE_FOR_PERFORMANCE |
877417e6 AB |
1231 | |
1232 | config CC_OPTIMIZE_FOR_PERFORMANCE | |
15f5db60 | 1233 | bool "Optimize for performance (-O2)" |
877417e6 AB |
1234 | help |
1235 | This is the default optimization level for the kernel, building | |
1236 | with the "-O2" compiler flag for best performance and most | |
1237 | helpful compile-time warnings. | |
1238 | ||
15f5db60 MY |
1239 | config CC_OPTIMIZE_FOR_PERFORMANCE_O3 |
1240 | bool "Optimize more for performance (-O3)" | |
1241 | depends on ARC | |
c45b4f1f | 1242 | help |
15f5db60 MY |
1243 | Choosing this option will pass "-O3" to your compiler to optimize |
1244 | the kernel yet more for performance. | |
c45b4f1f | 1245 | |
c45b4f1f | 1246 | config CC_OPTIMIZE_FOR_SIZE |
15f5db60 | 1247 | bool "Optimize for size (-Os)" |
c45b4f1f | 1248 | help |
ce3b487f MY |
1249 | Choosing this option will pass "-Os" to your compiler resulting |
1250 | in a smaller kernel. | |
c45b4f1f | 1251 | |
877417e6 AB |
1252 | endchoice |
1253 | ||
5d20ee31 NP |
1254 | config HAVE_LD_DEAD_CODE_DATA_ELIMINATION |
1255 | bool | |
1256 | help | |
1257 | This requires that the arch annotates or otherwise protects | |
1258 | its external entry points from being discarded. Linker scripts | |
1259 | must also merge .text.*, .data.*, and .bss.* correctly into | |
1260 | output sections. Care must be taken not to pull in unrelated | |
1261 | sections (e.g., '.text.init'). Typically '.' in section names | |
1262 | is used to distinguish them from label names / C identifiers. | |
1263 | ||
1264 | config LD_DEAD_CODE_DATA_ELIMINATION | |
1265 | bool "Dead code and data elimination (EXPERIMENTAL)" | |
1266 | depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION | |
1267 | depends on EXPERT | |
16fd20aa | 1268 | depends on !(FUNCTION_TRACER && CC_IS_GCC && GCC_VERSION < 40800) |
e85d1d65 MY |
1269 | depends on $(cc-option,-ffunction-sections -fdata-sections) |
1270 | depends on $(ld-option,--gc-sections) | |
5d20ee31 | 1271 | help |
8b9d2712 MY |
1272 | Enable this if you want to do dead code and data elimination with |
1273 | the linker by compiling with -ffunction-sections -fdata-sections, | |
1274 | and linking with --gc-sections. | |
5d20ee31 NP |
1275 | |
1276 | This can reduce on disk and in-memory size of the kernel | |
1277 | code and static data, particularly for small configs and | |
1278 | on small systems. This has the possibility of introducing | |
1279 | silently broken kernel if the required annotations are not | |
1280 | present. This option is not well tested yet, so use at your | |
1281 | own risk. | |
1282 | ||
0847062a RD |
1283 | config SYSCTL |
1284 | bool | |
1285 | ||
657a5209 MF |
1286 | config HAVE_UID16 |
1287 | bool | |
1288 | ||
1289 | config SYSCTL_EXCEPTION_TRACE | |
1290 | bool | |
1291 | help | |
1292 | Enable support for /proc/sys/debug/exception-trace. | |
1293 | ||
1294 | config SYSCTL_ARCH_UNALIGN_NO_WARN | |
1295 | bool | |
1296 | help | |
1297 | Enable support for /proc/sys/kernel/ignore-unaligned-usertrap | |
1298 | Allows arch to define/use @no_unaligned_warning to possibly warn | |
1299 | about unaligned access emulation going on under the hood. | |
1300 | ||
1301 | config SYSCTL_ARCH_UNALIGN_ALLOW | |
1302 | bool | |
1303 | help | |
1304 | Enable support for /proc/sys/kernel/unaligned-trap | |
1305 | Allows arches to define/use @unaligned_enabled to runtime toggle | |
1306 | the unaligned access emulation. | |
1307 | see arch/parisc/kernel/unaligned.c for reference | |
1308 | ||
657a5209 MF |
1309 | config HAVE_PCSPKR_PLATFORM |
1310 | bool | |
1311 | ||
f89b7755 AS |
1312 | # interpreter that classic socket filters depend on |
1313 | config BPF | |
1314 | bool | |
1315 | ||
6a108a14 DR |
1316 | menuconfig EXPERT |
1317 | bool "Configure standard kernel features (expert users)" | |
f505c553 JT |
1318 | # Unhide debug options, to make the on-by-default options visible |
1319 | select DEBUG_KERNEL | |
1da177e4 LT |
1320 | help |
1321 | This option allows certain base kernel options and settings | |
e8cf4e9c KK |
1322 | to be disabled or tweaked. This is for specialized |
1323 | environments which can tolerate a "non-standard" kernel. | |
1324 | Only use this if you really know what you are doing. | |
1da177e4 | 1325 | |
ae81f9e3 | 1326 | config UID16 |
6a108a14 | 1327 | bool "Enable 16-bit UID system calls" if EXPERT |
2813893f | 1328 | depends on HAVE_UID16 && MULTIUSER |
ae81f9e3 CE |
1329 | default y |
1330 | help | |
1331 | This enables the legacy 16-bit UID syscall wrappers. | |
1332 | ||
2813893f IM |
1333 | config MULTIUSER |
1334 | bool "Multiple users, groups and capabilities support" if EXPERT | |
1335 | default y | |
1336 | help | |
1337 | This option enables support for non-root users, groups and | |
1338 | capabilities. | |
1339 | ||
1340 | If you say N here, all processes will run with UID 0, GID 0, and all | |
1341 | possible capabilities. Saying N here also compiles out support for | |
1342 | system calls related to UIDs, GIDs, and capabilities, such as setuid, | |
1343 | setgid, and capset. | |
1344 | ||
1345 | If unsure, say Y here. | |
1346 | ||
f6187769 FF |
1347 | config SGETMASK_SYSCALL |
1348 | bool "sgetmask/ssetmask syscalls support" if EXPERT | |
a687a533 | 1349 | def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH |
f6187769 FF |
1350 | ---help--- |
1351 | sys_sgetmask and sys_ssetmask are obsolete system calls | |
1352 | no longer supported in libc but still enabled by default in some | |
1353 | architectures. | |
1354 | ||
1355 | If unsure, leave the default option here. | |
1356 | ||
6af9f7bf FF |
1357 | config SYSFS_SYSCALL |
1358 | bool "Sysfs syscall support" if EXPERT | |
1359 | default y | |
1360 | ---help--- | |
1361 | sys_sysfs is an obsolete system call no longer supported in libc. | |
1362 | Note that disabling this option is more secure but might break | |
1363 | compatibility with some systems. | |
1364 | ||
1365 | If unsure say Y here. | |
1366 | ||
d1b069f5 RD |
1367 | config FHANDLE |
1368 | bool "open by fhandle syscalls" if EXPERT | |
1369 | select EXPORTFS | |
1370 | default y | |
1371 | help | |
1372 | If you say Y here, a user level program will be able to map | |
1373 | file names to handle and then later use the handle for | |
1374 | different file system operations. This is useful in implementing | |
1375 | userspace file servers, which now track files using handles instead | |
1376 | of names. The handle would remain the same even if file names | |
1377 | get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) | |
1378 | syscalls. | |
1379 | ||
baa73d9e NP |
1380 | config POSIX_TIMERS |
1381 | bool "Posix Clocks & timers" if EXPERT | |
1382 | default y | |
1383 | help | |
1384 | This includes native support for POSIX timers to the kernel. | |
1385 | Some embedded systems have no use for them and therefore they | |
1386 | can be configured out to reduce the size of the kernel image. | |
1387 | ||
1388 | When this option is disabled, the following syscalls won't be | |
1389 | available: timer_create, timer_gettime: timer_getoverrun, | |
1390 | timer_settime, timer_delete, clock_adjtime, getitimer, | |
1391 | setitimer, alarm. Furthermore, the clock_settime, clock_gettime, | |
1392 | clock_getres and clock_nanosleep syscalls will be limited to | |
1393 | CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. | |
1394 | ||
1395 | If unsure say y. | |
1396 | ||
d59745ce MM |
1397 | config PRINTK |
1398 | default y | |
6a108a14 | 1399 | bool "Enable support for printk" if EXPERT |
74876a98 | 1400 | select IRQ_WORK |
d59745ce MM |
1401 | help |
1402 | This option enables normal printk support. Removing it | |
1403 | eliminates most of the message strings from the kernel image | |
1404 | and makes the kernel more or less silent. As this makes it | |
1405 | very difficult to diagnose system problems, saying N here is | |
1406 | strongly discouraged. | |
1407 | ||
42a0bb3f PM |
1408 | config PRINTK_NMI |
1409 | def_bool y | |
1410 | depends on PRINTK | |
1411 | depends on HAVE_NMI | |
1412 | ||
c8538a7a | 1413 | config BUG |
6a108a14 | 1414 | bool "BUG() support" if EXPERT |
c8538a7a MM |
1415 | default y |
1416 | help | |
e8cf4e9c KK |
1417 | Disabling this option eliminates support for BUG and WARN, reducing |
1418 | the size of your kernel image and potentially quietly ignoring | |
1419 | numerous fatal conditions. You should only consider disabling this | |
1420 | option for embedded systems with no facilities for reporting errors. | |
1421 | Just say Y. | |
c8538a7a | 1422 | |
708e9a79 | 1423 | config ELF_CORE |
046d662f | 1424 | depends on COREDUMP |
708e9a79 | 1425 | default y |
6a108a14 | 1426 | bool "Enable ELF core dumps" if EXPERT |
708e9a79 MM |
1427 | help |
1428 | Enable support for generating core dumps. Disabling saves about 4k. | |
1429 | ||
8761f1ab | 1430 | |
e5e1d3cb | 1431 | config PCSPKR_PLATFORM |
6a108a14 | 1432 | bool "Enable PC-Speaker support" if EXPERT |
8761f1ab | 1433 | depends on HAVE_PCSPKR_PLATFORM |
15f304b6 | 1434 | select I8253_LOCK |
e5e1d3cb SS |
1435 | default y |
1436 | help | |
e8cf4e9c KK |
1437 | This option allows to disable the internal PC-Speaker |
1438 | support, saving some memory. | |
e5e1d3cb | 1439 | |
1da177e4 LT |
1440 | config BASE_FULL |
1441 | default y | |
6a108a14 | 1442 | bool "Enable full-sized data structures for core" if EXPERT |
1da177e4 LT |
1443 | help |
1444 | Disabling this option reduces the size of miscellaneous core | |
1445 | kernel data structures. This saves memory on small machines, | |
1446 | but may reduce performance. | |
1447 | ||
1448 | config FUTEX | |
6a108a14 | 1449 | bool "Enable futex support" if EXPERT |
1da177e4 | 1450 | default y |
bc2eecd7 | 1451 | imply RT_MUTEXES |
1da177e4 LT |
1452 | help |
1453 | Disabling this option will cause the kernel to be built without | |
1454 | support for "fast userspace mutexes". The resulting kernel may not | |
1455 | run glibc-based applications correctly. | |
1456 | ||
bc2eecd7 NP |
1457 | config FUTEX_PI |
1458 | bool | |
1459 | depends on FUTEX && RT_MUTEXES | |
1460 | default y | |
1461 | ||
03b8c7b6 HC |
1462 | config HAVE_FUTEX_CMPXCHG |
1463 | bool | |
62b4d204 | 1464 | depends on FUTEX |
03b8c7b6 HC |
1465 | help |
1466 | Architectures should select this if futex_atomic_cmpxchg_inatomic() | |
1467 | is implemented and always working. This removes a couple of runtime | |
1468 | checks. | |
1469 | ||
1da177e4 | 1470 | config EPOLL |
6a108a14 | 1471 | bool "Enable eventpoll support" if EXPERT |
1da177e4 LT |
1472 | default y |
1473 | help | |
1474 | Disabling this option will cause the kernel to be built without | |
1475 | support for epoll family of system calls. | |
1476 | ||
fba2afaa | 1477 | config SIGNALFD |
6a108a14 | 1478 | bool "Enable signalfd() system call" if EXPERT |
fba2afaa DL |
1479 | default y |
1480 | help | |
1481 | Enable the signalfd() system call that allows to receive signals | |
1482 | on a file descriptor. | |
1483 | ||
1484 | If unsure, say Y. | |
1485 | ||
b215e283 | 1486 | config TIMERFD |
6a108a14 | 1487 | bool "Enable timerfd() system call" if EXPERT |
b215e283 DL |
1488 | default y |
1489 | help | |
1490 | Enable the timerfd() system call that allows to receive timer | |
1491 | events on a file descriptor. | |
1492 | ||
1493 | If unsure, say Y. | |
1494 | ||
e1ad7468 | 1495 | config EVENTFD |
6a108a14 | 1496 | bool "Enable eventfd() system call" if EXPERT |
e1ad7468 DL |
1497 | default y |
1498 | help | |
1499 | Enable the eventfd() system call that allows to receive both | |
1500 | kernel notification (ie. KAIO) or userspace notifications. | |
1501 | ||
1502 | If unsure, say Y. | |
1503 | ||
1da177e4 | 1504 | config SHMEM |
6a108a14 | 1505 | bool "Use full shmem filesystem" if EXPERT |
1da177e4 LT |
1506 | default y |
1507 | depends on MMU | |
1508 | help | |
1509 | The shmem is an internal filesystem used to manage shared memory. | |
1510 | It is backed by swap and manages resource limits. It is also exported | |
1511 | to userspace as tmpfs if TMPFS is enabled. Disabling this | |
1512 | option replaces shmem and tmpfs with the much simpler ramfs code, | |
1513 | which may be appropriate on small systems without swap. | |
1514 | ||
ebf3f09c | 1515 | config AIO |
6a108a14 | 1516 | bool "Enable AIO support" if EXPERT |
ebf3f09c TP |
1517 | default y |
1518 | help | |
1519 | This option enables POSIX asynchronous I/O which may by used | |
657a5209 MF |
1520 | by some high performance threaded applications. Disabling |
1521 | this option saves about 7k. | |
1522 | ||
2b188cc1 JA |
1523 | config IO_URING |
1524 | bool "Enable IO uring support" if EXPERT | |
561fb04a | 1525 | select IO_WQ |
2b188cc1 JA |
1526 | default y |
1527 | help | |
1528 | This option enables support for the io_uring interface, enabling | |
1529 | applications to submit and complete IO through submission and | |
1530 | completion rings that are shared between the kernel and application. | |
1531 | ||
d3ac21ca JT |
1532 | config ADVISE_SYSCALLS |
1533 | bool "Enable madvise/fadvise syscalls" if EXPERT | |
1534 | default y | |
1535 | help | |
1536 | This option enables the madvise and fadvise syscalls, used by | |
1537 | applications to advise the kernel about their future memory or file | |
1538 | usage, improving performance. If building an embedded system where no | |
1539 | applications use these syscalls, you can disable this option to save | |
1540 | space. | |
1541 | ||
5a281062 AA |
1542 | config HAVE_ARCH_USERFAULTFD_WP |
1543 | bool | |
1544 | help | |
1545 | Arch has userfaultfd write protection support | |
1546 | ||
5b25b13a MD |
1547 | config MEMBARRIER |
1548 | bool "Enable membarrier() system call" if EXPERT | |
1549 | default y | |
1550 | help | |
1551 | Enable the membarrier() system call that allows issuing memory | |
1552 | barriers across all running threads, which can be used to distribute | |
1553 | the cost of user-space memory barriers asymmetrically by transforming | |
1554 | pairs of memory barriers into pairs consisting of membarrier() and a | |
1555 | compiler barrier. | |
1556 | ||
1557 | If unsure, say Y. | |
1558 | ||
d1b069f5 | 1559 | config KALLSYMS |
e8cf4e9c KK |
1560 | bool "Load all symbols for debugging/ksymoops" if EXPERT |
1561 | default y | |
1562 | help | |
1563 | Say Y here to let the kernel print out symbolic crash information and | |
1564 | symbolic stack backtraces. This increases the size of the kernel | |
1565 | somewhat, as all symbols have to be loaded into the kernel image. | |
d1b069f5 RD |
1566 | |
1567 | config KALLSYMS_ALL | |
1568 | bool "Include all symbols in kallsyms" | |
1569 | depends on DEBUG_KERNEL && KALLSYMS | |
1570 | help | |
e8cf4e9c KK |
1571 | Normally kallsyms only contains the symbols of functions for nicer |
1572 | OOPS messages and backtraces (i.e., symbols from the text and inittext | |
1573 | sections). This is sufficient for most cases. And only in very rare | |
1574 | cases (e.g., when a debugger is used) all symbols are required (e.g., | |
1575 | names of variables from the data sections, etc). | |
d1b069f5 | 1576 | |
e8cf4e9c KK |
1577 | This option makes sure that all symbols are loaded into the kernel |
1578 | image (i.e., symbols from all sections) in cost of increased kernel | |
1579 | size (depending on the kernel configuration, it may be 300KiB or | |
1580 | something like this). | |
d1b069f5 | 1581 | |
e8cf4e9c | 1582 | Say N unless you really need all symbols. |
d1b069f5 RD |
1583 | |
1584 | config KALLSYMS_ABSOLUTE_PERCPU | |
1585 | bool | |
1586 | depends on KALLSYMS | |
1587 | default X86_64 && SMP | |
1588 | ||
1589 | config KALLSYMS_BASE_RELATIVE | |
1590 | bool | |
1591 | depends on KALLSYMS | |
a687a533 | 1592 | default !IA64 |
d1b069f5 RD |
1593 | help |
1594 | Instead of emitting them as absolute values in the native word size, | |
1595 | emit the symbol references in the kallsyms table as 32-bit entries, | |
1596 | each containing a relative value in the range [base, base + U32_MAX] | |
1597 | or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either | |
1598 | an absolute value in the range [0, S32_MAX] or a relative value in the | |
1599 | range [base, base + S32_MAX], where base is the lowest relative symbol | |
1600 | address encountered in the image. | |
1601 | ||
1602 | On 64-bit builds, this reduces the size of the address table by 50%, | |
1603 | but more importantly, it results in entries whose values are build | |
1604 | time constants, and no relocation pass is required at runtime to fix | |
1605 | up the entries based on the runtime load address of the kernel. | |
1606 | ||
1607 | # end of the "standard kernel features (expert users)" menu | |
1608 | ||
1609 | # syscall, maps, verifier | |
fc611f47 KS |
1610 | |
1611 | config BPF_LSM | |
1612 | bool "LSM Instrumentation with BPF" | |
4edf16b7 | 1613 | depends on BPF_EVENTS |
fc611f47 KS |
1614 | depends on BPF_SYSCALL |
1615 | depends on SECURITY | |
1616 | depends on BPF_JIT | |
1617 | help | |
1618 | Enables instrumentation of the security hooks with eBPF programs for | |
1619 | implementing dynamic MAC and Audit Policies. | |
1620 | ||
1621 | If you are unsure how to answer this question, answer N. | |
1622 | ||
d1b069f5 RD |
1623 | config BPF_SYSCALL |
1624 | bool "Enable bpf() system call" | |
d1b069f5 | 1625 | select BPF |
bae77c5e | 1626 | select IRQ_WORK |
d1b069f5 RD |
1627 | default n |
1628 | help | |
1629 | Enable the bpf() system call that allows to manipulate eBPF | |
1630 | programs and maps via file descriptors. | |
1631 | ||
81c22041 DB |
1632 | config ARCH_WANT_DEFAULT_BPF_JIT |
1633 | bool | |
1634 | ||
290af866 AS |
1635 | config BPF_JIT_ALWAYS_ON |
1636 | bool "Permanently enable BPF JIT and remove BPF interpreter" | |
1637 | depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT | |
1638 | help | |
1639 | Enables BPF JIT and removes BPF interpreter to avoid | |
1640 | speculative execution of BPF instructions by the interpreter | |
1641 | ||
81c22041 DB |
1642 | config BPF_JIT_DEFAULT_ON |
1643 | def_bool ARCH_WANT_DEFAULT_BPF_JIT || BPF_JIT_ALWAYS_ON | |
1644 | depends on HAVE_EBPF_JIT && BPF_JIT | |
1645 | ||
d1b069f5 RD |
1646 | config USERFAULTFD |
1647 | bool "Enable userfaultfd() system call" | |
d1b069f5 RD |
1648 | depends on MMU |
1649 | help | |
1650 | Enable the userfaultfd() system call that allows to intercept and | |
1651 | handle page faults in userland. | |
1652 | ||
3ccfebed MD |
1653 | config ARCH_HAS_MEMBARRIER_CALLBACKS |
1654 | bool | |
1655 | ||
70216e18 MD |
1656 | config ARCH_HAS_MEMBARRIER_SYNC_CORE |
1657 | bool | |
1658 | ||
d7822b1e MD |
1659 | config RSEQ |
1660 | bool "Enable rseq() system call" if EXPERT | |
1661 | default y | |
1662 | depends on HAVE_RSEQ | |
1663 | select MEMBARRIER | |
1664 | help | |
1665 | Enable the restartable sequences system call. It provides a | |
1666 | user-space cache for the current CPU number value, which | |
1667 | speeds up getting the current CPU number from user-space, | |
1668 | as well as an ABI to speed up user-space operations on | |
1669 | per-CPU data. | |
1670 | ||
1671 | If unsure, say Y. | |
1672 | ||
1673 | config DEBUG_RSEQ | |
1674 | default n | |
1675 | bool "Enabled debugging of rseq() system call" if EXPERT | |
1676 | depends on RSEQ && DEBUG_KERNEL | |
1677 | help | |
1678 | Enable extra debugging checks for the rseq system call. | |
1679 | ||
1680 | If unsure, say N. | |
1681 | ||
6befe5f6 RD |
1682 | config EMBEDDED |
1683 | bool "Embedded system" | |
5d2acfc7 | 1684 | option allnoconfig_y |
6befe5f6 RD |
1685 | select EXPERT |
1686 | help | |
1687 | This option should be enabled if compiling the kernel for | |
1688 | an embedded system so certain expert options are available | |
1689 | for configuration. | |
1690 | ||
cdd6c482 | 1691 | config HAVE_PERF_EVENTS |
0793a61d | 1692 | bool |
018df72d MF |
1693 | help |
1694 | See tools/perf/design.txt for details. | |
0793a61d | 1695 | |
906010b2 PZ |
1696 | config PERF_USE_VMALLOC |
1697 | bool | |
1698 | help | |
1699 | See tools/perf/design.txt for details | |
1700 | ||
ad90a3de | 1701 | config PC104 |
424529fb | 1702 | bool "PC/104 support" if EXPERT |
ad90a3de WBG |
1703 | help |
1704 | Expose PC/104 form factor device drivers and options available for | |
1705 | selection and configuration. Enable this option if your target | |
1706 | machine has a PC/104 bus. | |
1707 | ||
57c0c15b | 1708 | menu "Kernel Performance Events And Counters" |
0793a61d | 1709 | |
cdd6c482 | 1710 | config PERF_EVENTS |
57c0c15b | 1711 | bool "Kernel performance events and counters" |
392d65a9 | 1712 | default y if PROFILING |
cdd6c482 | 1713 | depends on HAVE_PERF_EVENTS |
e360adbe | 1714 | select IRQ_WORK |
83fe27ea | 1715 | select SRCU |
0793a61d | 1716 | help |
57c0c15b IM |
1717 | Enable kernel support for various performance events provided |
1718 | by software and hardware. | |
0793a61d | 1719 | |
dd77038d | 1720 | Software events are supported either built-in or via the |
57c0c15b | 1721 | use of generic tracepoints. |
0793a61d | 1722 | |
57c0c15b IM |
1723 | Most modern CPUs support performance events via performance |
1724 | counter registers. These registers count the number of certain | |
0793a61d TG |
1725 | types of hw events: such as instructions executed, cachemisses |
1726 | suffered, or branches mis-predicted - without slowing down the | |
1727 | kernel or applications. These registers can also trigger interrupts | |
1728 | when a threshold number of events have passed - and can thus be | |
1729 | used to profile the code that runs on that CPU. | |
1730 | ||
57c0c15b | 1731 | The Linux Performance Event subsystem provides an abstraction of |
dd77038d | 1732 | these software and hardware event capabilities, available via a |
57c0c15b | 1733 | system call and used by the "perf" utility in tools/perf/. It |
0793a61d TG |
1734 | provides per task and per CPU counters, and it provides event |
1735 | capabilities on top of those. | |
1736 | ||
1737 | Say Y if unsure. | |
1738 | ||
906010b2 PZ |
1739 | config DEBUG_PERF_USE_VMALLOC |
1740 | default n | |
1741 | bool "Debug: use vmalloc to back perf mmap() buffers" | |
cb307113 | 1742 | depends on PERF_EVENTS && DEBUG_KERNEL && !PPC |
906010b2 PZ |
1743 | select PERF_USE_VMALLOC |
1744 | help | |
e8cf4e9c | 1745 | Use vmalloc memory to back perf mmap() buffers. |
906010b2 | 1746 | |
e8cf4e9c KK |
1747 | Mostly useful for debugging the vmalloc code on platforms |
1748 | that don't require it. | |
906010b2 | 1749 | |
e8cf4e9c | 1750 | Say N if unsure. |
906010b2 | 1751 | |
0793a61d TG |
1752 | endmenu |
1753 | ||
f8891e5e CL |
1754 | config VM_EVENT_COUNTERS |
1755 | default y | |
6a108a14 | 1756 | bool "Enable VM event counters for /proc/vmstat" if EXPERT |
f8891e5e | 1757 | help |
2aea4fb6 PJ |
1758 | VM event counters are needed for event counts to be shown. |
1759 | This option allows the disabling of the VM event counters | |
6a108a14 | 1760 | on EXPERT systems. /proc/vmstat will only show page counts |
2aea4fb6 | 1761 | if VM event counters are disabled. |
f8891e5e | 1762 | |
41ecc55b CL |
1763 | config SLUB_DEBUG |
1764 | default y | |
6a108a14 | 1765 | bool "Enable SLUB debugging support" if EXPERT |
f6acb635 | 1766 | depends on SLUB && SYSFS |
41ecc55b CL |
1767 | help |
1768 | SLUB has extensive debug support features. Disabling these can | |
1769 | result in significant savings in code size. This also disables | |
1770 | SLUB sysfs support. /sys/slab will not exist and there will be | |
1771 | no support for cache validation etc. | |
1772 | ||
1663f26d TH |
1773 | config SLUB_MEMCG_SYSFS_ON |
1774 | default n | |
1775 | bool "Enable memcg SLUB sysfs support by default" if EXPERT | |
1776 | depends on SLUB && SYSFS && MEMCG | |
1777 | help | |
1778 | SLUB creates a directory under /sys/kernel/slab for each | |
1779 | allocation cache to host info and debug files. If memory | |
1780 | cgroup is enabled, each cache can have per memory cgroup | |
1781 | caches. SLUB can create the same sysfs directories for these | |
1782 | caches under /sys/kernel/slab/CACHE/cgroup but it can lead | |
1783 | to a very high number of debug files being created. This is | |
1784 | controlled by slub_memcg_sysfs boot parameter and this | |
1785 | config option determines the parameter's default value. | |
1786 | ||
b943c460 RD |
1787 | config COMPAT_BRK |
1788 | bool "Disable heap randomization" | |
1789 | default y | |
1790 | help | |
1791 | Randomizing heap placement makes heap exploits harder, but it | |
1792 | also breaks ancient binaries (including anything libc5 based). | |
1793 | This option changes the bootup default to heap randomization | |
692105b8 | 1794 | disabled, and can be overridden at runtime by setting |
b943c460 RD |
1795 | /proc/sys/kernel/randomize_va_space to 2. |
1796 | ||
1797 | On non-ancient distros (post-2000 ones) N is usually a safe choice. | |
1798 | ||
81819f0f CL |
1799 | choice |
1800 | prompt "Choose SLAB allocator" | |
a0acd820 | 1801 | default SLUB |
81819f0f CL |
1802 | help |
1803 | This option allows to select a slab allocator. | |
1804 | ||
1805 | config SLAB | |
1806 | bool "SLAB" | |
04385fc5 | 1807 | select HAVE_HARDENED_USERCOPY_ALLOCATOR |
81819f0f CL |
1808 | help |
1809 | The regular slab allocator that is established and known to work | |
34013886 | 1810 | well in all environments. It organizes cache hot objects in |
02f56210 | 1811 | per cpu and per node queues. |
81819f0f CL |
1812 | |
1813 | config SLUB | |
81819f0f | 1814 | bool "SLUB (Unqueued Allocator)" |
ed18adc1 | 1815 | select HAVE_HARDENED_USERCOPY_ALLOCATOR |
81819f0f CL |
1816 | help |
1817 | SLUB is a slab allocator that minimizes cache line usage | |
1818 | instead of managing queues of cached objects (SLAB approach). | |
1819 | Per cpu caching is realized using slabs of objects instead | |
1820 | of queues of objects. SLUB can use memory efficiently | |
02f56210 SA |
1821 | and has enhanced diagnostics. SLUB is the default choice for |
1822 | a slab allocator. | |
81819f0f CL |
1823 | |
1824 | config SLOB | |
6a108a14 | 1825 | depends on EXPERT |
81819f0f CL |
1826 | bool "SLOB (Simple Allocator)" |
1827 | help | |
37291458 MM |
1828 | SLOB replaces the stock allocator with a drastically simpler |
1829 | allocator. SLOB is generally more space efficient but | |
1830 | does not perform as well on large systems. | |
81819f0f CL |
1831 | |
1832 | endchoice | |
1833 | ||
7660a6fd KC |
1834 | config SLAB_MERGE_DEFAULT |
1835 | bool "Allow slab caches to be merged" | |
1836 | default y | |
1837 | help | |
1838 | For reduced kernel memory fragmentation, slab caches can be | |
1839 | merged when they share the same size and other characteristics. | |
1840 | This carries a risk of kernel heap overflows being able to | |
1841 | overwrite objects from merged caches (and more easily control | |
1842 | cache layout), which makes such heap attacks easier to exploit | |
1843 | by attackers. By keeping caches unmerged, these kinds of exploits | |
1844 | can usually only damage objects in the same cache. To disable | |
1845 | merging at runtime, "slab_nomerge" can be passed on the kernel | |
1846 | command line. | |
1847 | ||
c7ce4f60 TG |
1848 | config SLAB_FREELIST_RANDOM |
1849 | default n | |
210e7a43 | 1850 | depends on SLAB || SLUB |
c7ce4f60 TG |
1851 | bool "SLAB freelist randomization" |
1852 | help | |
210e7a43 | 1853 | Randomizes the freelist order used on creating new pages. This |
c7ce4f60 TG |
1854 | security feature reduces the predictability of the kernel slab |
1855 | allocator against heap overflows. | |
1856 | ||
2482ddec KC |
1857 | config SLAB_FREELIST_HARDENED |
1858 | bool "Harden slab freelist metadata" | |
1859 | depends on SLUB | |
1860 | help | |
1861 | Many kernel heap attacks try to target slab cache metadata and | |
1862 | other infrastructure. This options makes minor performance | |
92bae787 | 1863 | sacrifices to harden the kernel slab allocator against common |
2482ddec KC |
1864 | freelist exploit methods. |
1865 | ||
e900a918 DW |
1866 | config SHUFFLE_PAGE_ALLOCATOR |
1867 | bool "Page allocator randomization" | |
1868 | default SLAB_FREELIST_RANDOM && ACPI_NUMA | |
1869 | help | |
1870 | Randomization of the page allocator improves the average | |
1871 | utilization of a direct-mapped memory-side-cache. See section | |
1872 | 5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI | |
1873 | 6.2a specification for an example of how a platform advertises | |
1874 | the presence of a memory-side-cache. There are also incidental | |
1875 | security benefits as it reduces the predictability of page | |
1876 | allocations to compliment SLAB_FREELIST_RANDOM, but the | |
1877 | default granularity of shuffling on the "MAX_ORDER - 1" i.e, | |
1878 | 10th order of pages is selected based on cache utilization | |
1879 | benefits on x86. | |
1880 | ||
1881 | While the randomization improves cache utilization it may | |
1882 | negatively impact workloads on platforms without a cache. For | |
1883 | this reason, by default, the randomization is enabled only | |
1884 | after runtime detection of a direct-mapped memory-side-cache. | |
1885 | Otherwise, the randomization may be force enabled with the | |
1886 | 'page_alloc.shuffle' kernel command line parameter. | |
1887 | ||
1888 | Say Y if unsure. | |
1889 | ||
345c905d JK |
1890 | config SLUB_CPU_PARTIAL |
1891 | default y | |
b39ffbf8 | 1892 | depends on SLUB && SMP |
345c905d JK |
1893 | bool "SLUB per cpu partial cache" |
1894 | help | |
92bae787 | 1895 | Per cpu partial caches accelerate objects allocation and freeing |
345c905d JK |
1896 | that is local to a processor at the price of more indeterminism |
1897 | in the latency of the free. On overflow these caches will be cleared | |
1898 | which requires the taking of locks that may cause latency spikes. | |
1899 | Typically one would choose no for a realtime system. | |
1900 | ||
ea637639 JZ |
1901 | config MMAP_ALLOW_UNINITIALIZED |
1902 | bool "Allow mmapped anonymous memory to be uninitialized" | |
6a108a14 | 1903 | depends on EXPERT && !MMU |
ea637639 JZ |
1904 | default n |
1905 | help | |
1906 | Normally, and according to the Linux spec, anonymous memory obtained | |
3903bf94 | 1907 | from mmap() has its contents cleared before it is passed to |
ea637639 JZ |
1908 | userspace. Enabling this config option allows you to request that |
1909 | mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus | |
1910 | providing a huge performance boost. If this option is not enabled, | |
1911 | then the flag will be ignored. | |
1912 | ||
1913 | This is taken advantage of by uClibc's malloc(), and also by | |
1914 | ELF-FDPIC binfmt's brk and stack allocator. | |
1915 | ||
1916 | Because of the obvious security issues, this option should only be | |
1917 | enabled on embedded devices where you control what is run in | |
1918 | userspace. Since that isn't generally a problem on no-MMU systems, | |
1919 | it is normally safe to say Y here. | |
1920 | ||
1921 | See Documentation/nommu-mmap.txt for more information. | |
1922 | ||
091f6e26 DH |
1923 | config SYSTEM_DATA_VERIFICATION |
1924 | def_bool n | |
1925 | select SYSTEM_TRUSTED_KEYRING | |
1926 | select KEYS | |
1927 | select CRYPTO | |
d43de6c7 | 1928 | select CRYPTO_RSA |
091f6e26 DH |
1929 | select ASYMMETRIC_KEY_TYPE |
1930 | select ASYMMETRIC_PUBLIC_KEY_SUBTYPE | |
091f6e26 DH |
1931 | select ASN1 |
1932 | select OID_REGISTRY | |
1933 | select X509_CERTIFICATE_PARSER | |
1934 | select PKCS7_MESSAGE_PARSER | |
82c04ff8 | 1935 | help |
091f6e26 DH |
1936 | Provide PKCS#7 message verification using the contents of the system |
1937 | trusted keyring to provide public keys. This then can be used for | |
1938 | module verification, kexec image verification and firmware blob | |
1939 | verification. | |
82c04ff8 | 1940 | |
125e5645 | 1941 | config PROFILING |
b309a294 | 1942 | bool "Profiling support" |
125e5645 MD |
1943 | help |
1944 | Say Y here to enable the extended profiling support mechanisms used | |
1945 | by profilers such as OProfile. | |
1946 | ||
5f87f112 IM |
1947 | # |
1948 | # Place an empty function call at each tracepoint site. Can be | |
1949 | # dynamically changed for a probe function. | |
1950 | # | |
97e1c18e | 1951 | config TRACEPOINTS |
5f87f112 | 1952 | bool |
97e1c18e | 1953 | |
1da177e4 LT |
1954 | endmenu # General setup |
1955 | ||
1572497c CH |
1956 | source "arch/Kconfig" |
1957 | ||
ae81f9e3 | 1958 | config RT_MUTEXES |
6341e62b | 1959 | bool |
ae81f9e3 | 1960 | |
1da177e4 LT |
1961 | config BASE_SMALL |
1962 | int | |
1963 | default 0 if BASE_FULL | |
1964 | default 1 if !BASE_FULL | |
1965 | ||
c8424e77 TJB |
1966 | config MODULE_SIG_FORMAT |
1967 | def_bool n | |
1968 | select SYSTEM_DATA_VERIFICATION | |
1969 | ||
66da5733 | 1970 | menuconfig MODULES |
1da177e4 | 1971 | bool "Enable loadable module support" |
11097a03 | 1972 | option modules |
1da177e4 LT |
1973 | help |
1974 | Kernel modules are small pieces of compiled code which can | |
1975 | be inserted in the running kernel, rather than being | |
1976 | permanently built into the kernel. You use the "modprobe" | |
1977 | tool to add (and sometimes remove) them. If you say Y here, | |
1978 | many parts of the kernel can be built as modules (by | |
1979 | answering M instead of Y where indicated): this is most | |
1980 | useful for infrequently used options which are not required | |
1981 | for booting. For more information, see the man pages for | |
1982 | modprobe, lsmod, modinfo, insmod and rmmod. | |
1983 | ||
1984 | If you say Y here, you will need to run "make | |
1985 | modules_install" to put the modules under /lib/modules/ | |
1986 | where modprobe can find them (you may need to be root to do | |
1987 | this). | |
1988 | ||
1989 | If unsure, say Y. | |
1990 | ||
0b0de144 RD |
1991 | if MODULES |
1992 | ||
826e4506 LT |
1993 | config MODULE_FORCE_LOAD |
1994 | bool "Forced module loading" | |
826e4506 LT |
1995 | default n |
1996 | help | |
91e37a79 RR |
1997 | Allow loading of modules without version information (ie. modprobe |
1998 | --force). Forced module loading sets the 'F' (forced) taint flag and | |
1999 | is usually a really bad idea. | |
826e4506 | 2000 | |
1da177e4 LT |
2001 | config MODULE_UNLOAD |
2002 | bool "Module unloading" | |
1da177e4 LT |
2003 | help |
2004 | Without this option you will not be able to unload any | |
2005 | modules (note that some modules may not be unloadable | |
f7f5b675 DV |
2006 | anyway), which makes your kernel smaller, faster |
2007 | and simpler. If unsure, say Y. | |
1da177e4 LT |
2008 | |
2009 | config MODULE_FORCE_UNLOAD | |
2010 | bool "Forced module unloading" | |
19c92399 | 2011 | depends on MODULE_UNLOAD |
1da177e4 LT |
2012 | help |
2013 | This option allows you to force a module to unload, even if the | |
2014 | kernel believes it is unsafe: the kernel will remove the module | |
2015 | without waiting for anyone to stop using it (using the -f option to | |
2016 | rmmod). This is mainly for kernel developers and desperate users. | |
2017 | If unsure, say N. | |
2018 | ||
1da177e4 | 2019 | config MODVERSIONS |
0d541643 | 2020 | bool "Module versioning support" |
1da177e4 LT |
2021 | help |
2022 | Usually, you have to use modules compiled with your kernel. | |
2023 | Saying Y here makes it sometimes possible to use modules | |
2024 | compiled for different kernels, by adding enough information | |
2025 | to the modules to (hopefully) spot any changes which would | |
2026 | make them incompatible with the kernel you are running. If | |
2027 | unsure, say N. | |
2028 | ||
2ff2b7ec MY |
2029 | config ASM_MODVERSIONS |
2030 | bool | |
2031 | default HAVE_ASM_MODVERSIONS && MODVERSIONS | |
2032 | help | |
2033 | This enables module versioning for exported symbols also from | |
2034 | assembly. This can be enabled only when the target architecture | |
2035 | supports it. | |
2036 | ||
56067812 AB |
2037 | config MODULE_REL_CRCS |
2038 | bool | |
2039 | depends on MODVERSIONS | |
2040 | ||
1da177e4 LT |
2041 | config MODULE_SRCVERSION_ALL |
2042 | bool "Source checksum for all modules" | |
1da177e4 LT |
2043 | help |
2044 | Modules which contain a MODULE_VERSION get an extra "srcversion" | |
2045 | field inserted into their modinfo section, which contains a | |
2046 | sum of the source files which made it. This helps maintainers | |
2047 | see exactly which source was used to build a module (since | |
2048 | others sometimes change the module source without updating | |
2049 | the version). With this option, such a "srcversion" field | |
2050 | will be created for all modules. If unsure, say N. | |
2051 | ||
106a4ee2 RR |
2052 | config MODULE_SIG |
2053 | bool "Module signature verification" | |
c8424e77 | 2054 | select MODULE_SIG_FORMAT |
106a4ee2 RR |
2055 | help |
2056 | Check modules for valid signatures upon load: the signature | |
2057 | is simply appended to the module. For more information see | |
cbdc8217 | 2058 | <file:Documentation/admin-guide/module-signing.rst>. |
106a4ee2 | 2059 | |
228c37ff DH |
2060 | Note that this option adds the OpenSSL development packages as a |
2061 | kernel build dependency so that the signing tool can use its crypto | |
2062 | library. | |
2063 | ||
49fcf732 DH |
2064 | You should enable this option if you wish to use either |
2065 | CONFIG_SECURITY_LOCKDOWN_LSM or lockdown functionality imposed via | |
2066 | another LSM - otherwise unsigned modules will be loadable regardless | |
2067 | of the lockdown policy. | |
2068 | ||
ea0b6dcf DH |
2069 | !!!WARNING!!! If you enable this option, you MUST make sure that the |
2070 | module DOES NOT get stripped after being signed. This includes the | |
2071 | debuginfo strip done by some packagers (such as rpmbuild) and | |
2072 | inclusion into an initramfs that wants the module size reduced. | |
2073 | ||
106a4ee2 RR |
2074 | config MODULE_SIG_FORCE |
2075 | bool "Require modules to be validly signed" | |
2076 | depends on MODULE_SIG | |
2077 | help | |
2078 | Reject unsigned modules or signed modules for which we don't have a | |
2079 | key. Without this, such modules will simply taint the kernel. | |
ea0b6dcf | 2080 | |
d9d8d7ed MM |
2081 | config MODULE_SIG_ALL |
2082 | bool "Automatically sign all modules" | |
2083 | default y | |
2084 | depends on MODULE_SIG | |
2085 | help | |
2086 | Sign all modules during make modules_install. Without this option, | |
2087 | modules must be signed manually, using the scripts/sign-file tool. | |
2088 | ||
2089 | comment "Do not forget to sign required modules with scripts/sign-file" | |
2090 | depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL | |
2091 | ||
ea0b6dcf DH |
2092 | choice |
2093 | prompt "Which hash algorithm should modules be signed with?" | |
2094 | depends on MODULE_SIG | |
2095 | help | |
2096 | This determines which sort of hashing algorithm will be used during | |
2097 | signature generation. This algorithm _must_ be built into the kernel | |
2098 | directly so that signature verification can take place. It is not | |
2099 | possible to load a signed module containing the algorithm to check | |
2100 | the signature on that module. | |
2101 | ||
2102 | config MODULE_SIG_SHA1 | |
2103 | bool "Sign modules with SHA-1" | |
2104 | select CRYPTO_SHA1 | |
2105 | ||
2106 | config MODULE_SIG_SHA224 | |
2107 | bool "Sign modules with SHA-224" | |
2108 | select CRYPTO_SHA256 | |
2109 | ||
2110 | config MODULE_SIG_SHA256 | |
2111 | bool "Sign modules with SHA-256" | |
2112 | select CRYPTO_SHA256 | |
2113 | ||
2114 | config MODULE_SIG_SHA384 | |
2115 | bool "Sign modules with SHA-384" | |
2116 | select CRYPTO_SHA512 | |
2117 | ||
2118 | config MODULE_SIG_SHA512 | |
2119 | bool "Sign modules with SHA-512" | |
2120 | select CRYPTO_SHA512 | |
2121 | ||
2122 | endchoice | |
2123 | ||
22753674 MM |
2124 | config MODULE_SIG_HASH |
2125 | string | |
2126 | depends on MODULE_SIG | |
2127 | default "sha1" if MODULE_SIG_SHA1 | |
2128 | default "sha224" if MODULE_SIG_SHA224 | |
2129 | default "sha256" if MODULE_SIG_SHA256 | |
2130 | default "sha384" if MODULE_SIG_SHA384 | |
2131 | default "sha512" if MODULE_SIG_SHA512 | |
2132 | ||
beb50df3 BJ |
2133 | config MODULE_COMPRESS |
2134 | bool "Compress modules on installation" | |
beb50df3 | 2135 | help |
beb50df3 | 2136 | |
b6c09b51 RR |
2137 | Compresses kernel modules when 'make modules_install' is run; gzip or |
2138 | xz depending on "Compression algorithm" below. | |
beb50df3 | 2139 | |
b6c09b51 | 2140 | module-init-tools MAY support gzip, and kmod MAY support gzip and xz. |
beb50df3 | 2141 | |
b6c09b51 RR |
2142 | Out-of-tree kernel modules installed using Kbuild will also be |
2143 | compressed upon installation. | |
beb50df3 | 2144 | |
b6c09b51 RR |
2145 | Note: for modules inside an initrd or initramfs, it's more efficient |
2146 | to compress the whole initrd or initramfs instead. | |
beb50df3 | 2147 | |
b6c09b51 RR |
2148 | Note: This is fully compatible with signed modules. |
2149 | ||
2150 | If in doubt, say N. | |
beb50df3 BJ |
2151 | |
2152 | choice | |
2153 | prompt "Compression algorithm" | |
2154 | depends on MODULE_COMPRESS | |
2155 | default MODULE_COMPRESS_GZIP | |
2156 | help | |
2157 | This determines which sort of compression will be used during | |
2158 | 'make modules_install'. | |
2159 | ||
2160 | GZIP (default) and XZ are supported. | |
2161 | ||
2162 | config MODULE_COMPRESS_GZIP | |
2163 | bool "GZIP" | |
2164 | ||
2165 | config MODULE_COMPRESS_XZ | |
2166 | bool "XZ" | |
2167 | ||
2168 | endchoice | |
2169 | ||
3d52ec5e MM |
2170 | config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS |
2171 | bool "Allow loading of modules with missing namespace imports" | |
2172 | help | |
2173 | Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in | |
2174 | a namespace. A module that makes use of a symbol exported with such a | |
2175 | namespace is required to import the namespace via MODULE_IMPORT_NS(). | |
2176 | There is no technical reason to enforce correct namespace imports, | |
2177 | but it creates consistency between symbols defining namespaces and | |
2178 | users importing namespaces they make use of. This option relaxes this | |
2179 | requirement and lifts the enforcement when loading a module. | |
2180 | ||
2181 | If unsure, say N. | |
2182 | ||
efd9763d MY |
2183 | config UNUSED_SYMBOLS |
2184 | bool "Enable unused/obsolete exported symbols" | |
2185 | default y if X86 | |
2186 | help | |
2187 | Unused but exported symbols make the kernel needlessly bigger. For | |
2188 | that reason most of these unused exports will soon be removed. This | |
2189 | option is provided temporarily to provide a transition period in case | |
2190 | some external kernel module needs one of these symbols anyway. If you | |
2191 | encounter such a case in your module, consider if you are actually | |
2192 | using the right API. (rationale: since nobody in the kernel is using | |
2193 | this in a module, there is a pretty good chance it's actually the | |
2194 | wrong interface to use). If you really need the symbol, please send a | |
2195 | mail to the linux kernel mailing list mentioning the symbol and why | |
2196 | you really need it, and what the merge plan to the mainline kernel for | |
2197 | your module is. | |
2198 | ||
dbacb0ef NP |
2199 | config TRIM_UNUSED_KSYMS |
2200 | bool "Trim unused exported kernel symbols" | |
d189c2a4 | 2201 | depends on !UNUSED_SYMBOLS |
dbacb0ef NP |
2202 | help |
2203 | The kernel and some modules make many symbols available for | |
2204 | other modules to use via EXPORT_SYMBOL() and variants. Depending | |
2205 | on the set of modules being selected in your kernel configuration, | |
2206 | many of those exported symbols might never be used. | |
2207 | ||
2208 | This option allows for unused exported symbols to be dropped from | |
2209 | the build. In turn, this provides the compiler more opportunities | |
2210 | (especially when using LTO) for optimizing the code and reducing | |
2211 | binary size. This might have some security advantages as well. | |
2212 | ||
f1cb637e | 2213 | If unsure, or if you need to build out-of-tree modules, say N. |
dbacb0ef | 2214 | |
1518c633 QP |
2215 | config UNUSED_KSYMS_WHITELIST |
2216 | string "Whitelist of symbols to keep in ksymtab" | |
2217 | depends on TRIM_UNUSED_KSYMS | |
2218 | help | |
2219 | By default, all unused exported symbols will be un-exported from the | |
2220 | build when TRIM_UNUSED_KSYMS is selected. | |
2221 | ||
2222 | UNUSED_KSYMS_WHITELIST allows to whitelist symbols that must be kept | |
2223 | exported at all times, even in absence of in-tree users. The value to | |
2224 | set here is the path to a text file containing the list of symbols, | |
2225 | one per line. The path can be absolute, or relative to the kernel | |
2226 | source tree. | |
2227 | ||
0b0de144 RD |
2228 | endif # MODULES |
2229 | ||
6c9692e2 PZ |
2230 | config MODULES_TREE_LOOKUP |
2231 | def_bool y | |
2232 | depends on PERF_EVENTS || TRACING | |
2233 | ||
98a79d6a RR |
2234 | config INIT_ALL_POSSIBLE |
2235 | bool | |
2236 | help | |
5f054e31 RR |
2237 | Back when each arch used to define their own cpu_online_mask and |
2238 | cpu_possible_mask, some of them chose to initialize cpu_possible_mask | |
98a79d6a RR |
2239 | with all 1s, and others with all 0s. When they were centralised, |
2240 | it was better to provide this option than to break all the archs | |
692105b8 | 2241 | and have several arch maintainers pursuing me down dark alleys. |
98a79d6a | 2242 | |
3a65dfe8 | 2243 | source "block/Kconfig" |
e98c3202 AK |
2244 | |
2245 | config PREEMPT_NOTIFIERS | |
2246 | bool | |
e260be67 | 2247 | |
16295bec SK |
2248 | config PADATA |
2249 | depends on SMP | |
2250 | bool | |
2251 | ||
4520c6a4 DH |
2252 | config ASN1 |
2253 | tristate | |
2254 | help | |
2255 | Build a simple ASN.1 grammar compiler that produces a bytecode output | |
2256 | that can be interpreted by the ASN.1 stream decoder and used to | |
2257 | inform it as to what tags are to be expected in a stream and what | |
2258 | functions to call on what tags. | |
2259 | ||
6beb0009 | 2260 | source "kernel/Kconfig.locks" |
e61938a9 | 2261 | |
0ebeea8c DB |
2262 | config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE |
2263 | bool | |
2264 | ||
e61938a9 MD |
2265 | config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE |
2266 | bool | |
1bd21c6c DB |
2267 | |
2268 | # It may be useful for an architecture to override the definitions of the | |
7303e30e DB |
2269 | # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h> |
2270 | # and the COMPAT_ variants in <linux/compat.h>, in particular to use a | |
2271 | # different calling convention for syscalls. They can also override the | |
2272 | # macros for not-implemented syscalls in kernel/sys_ni.c and | |
2273 | # kernel/time/posix-stubs.c. All these overrides need to be available in | |
2274 | # <asm/syscall_wrapper.h>. | |
1bd21c6c DB |
2275 | config ARCH_HAS_SYSCALL_WRAPPER |
2276 | def_bool n |