Commit | Line | Data |
---|---|---|
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)" |
104daea1 MY |
9 | default ARCH_DEFCONFIG |
10 | default "arch/$(ARCH)/defconfig" | |
face4374 | 11 | |
a4353898 MY |
12 | config CC_IS_GCC |
13 | def_bool $(success,$(CC) --version | head -n 1 | grep -q gcc) | |
14 | ||
15 | config GCC_VERSION | |
16 | int | |
fa7295ab | 17 | default $(shell,$(srctree)/scripts/gcc-version.sh $(CC)) if CC_IS_GCC |
a4353898 MY |
18 | default 0 |
19 | ||
469cb737 MY |
20 | config CC_IS_CLANG |
21 | def_bool $(success,$(CC) --version | head -n 1 | grep -q clang) | |
22 | ||
23 | config CLANG_VERSION | |
24 | int | |
25 | default $(shell,$(srctree)/scripts/clang-version.sh $(CC)) | |
26 | ||
1a927fd3 MY |
27 | config CC_CAN_LINK |
28 | def_bool $(success,$(srctree)/scripts/cc-can-link.sh $(CC)) | |
29 | ||
e9666d10 MY |
30 | config CC_HAS_ASM_GOTO |
31 | def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC)) | |
32 | ||
5cf896fb | 33 | config TOOLS_SUPPORT_RELR |
2d122942 | 34 | def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh) |
5cf896fb | 35 | |
eb111869 RV |
36 | config CC_HAS_ASM_INLINE |
37 | def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null) | |
38 | ||
b303c6df MY |
39 | config CC_HAS_WARN_MAYBE_UNINITIALIZED |
40 | def_bool $(cc-option,-Wmaybe-uninitialized) | |
41 | help | |
42 | GCC >= 4.7 supports this option. | |
43 | ||
44 | config CC_DISABLE_WARN_MAYBE_UNINITIALIZED | |
45 | bool | |
46 | depends on CC_HAS_WARN_MAYBE_UNINITIALIZED | |
47 | default CC_IS_GCC && GCC_VERSION < 40900 # unreliable for GCC < 4.9 | |
48 | help | |
49 | GCC's -Wmaybe-uninitialized is not reliable by definition. | |
50 | Lots of false positive warnings are produced in some cases. | |
51 | ||
52 | If this option is enabled, -Wno-maybe-uninitialzed is passed | |
53 | to the compiler to suppress maybe-uninitialized warnings. | |
54 | ||
b99b87f7 PO |
55 | config CONSTRUCTORS |
56 | bool | |
b99b87f7 | 57 | |
e360adbe PZ |
58 | config IRQ_WORK |
59 | bool | |
e360adbe | 60 | |
1dbdc6f1 DD |
61 | config BUILDTIME_EXTABLE_SORT |
62 | bool | |
63 | ||
c65eacbe AL |
64 | config THREAD_INFO_IN_TASK |
65 | bool | |
66 | help | |
67 | Select this to move thread_info off the stack into task_struct. To | |
68 | make this work, an arch will need to remove all thread_info fields | |
69 | except flags and fix any runtime bugs. | |
70 | ||
c6c314a6 AL |
71 | One subtle change that will be needed is to use try_get_task_stack() |
72 | and put_task_stack() in save_thread_stack_tsk() and get_wchan(). | |
73 | ||
ff0cfc66 | 74 | menu "General setup" |
1da177e4 | 75 | |
1da177e4 LT |
76 | config BROKEN |
77 | bool | |
1da177e4 LT |
78 | |
79 | config BROKEN_ON_SMP | |
80 | bool | |
81 | depends on BROKEN || !SMP | |
82 | default y | |
83 | ||
1da177e4 LT |
84 | config INIT_ENV_ARG_LIMIT |
85 | int | |
dd673bca AB |
86 | default 32 if !UML |
87 | default 128 if UML | |
1da177e4 | 88 | help |
34ad92c2 RD |
89 | Maximum of each of the number of arguments and environment |
90 | variables passed to init from the kernel command line. | |
1da177e4 | 91 | |
4bb16672 JS |
92 | config COMPILE_TEST |
93 | bool "Compile also drivers which will not load" | |
bc083a64 | 94 | depends on !UML |
4bb16672 JS |
95 | default n |
96 | help | |
97 | Some drivers can be compiled on a different platform than they are | |
98 | intended to be run on. Despite they cannot be loaded there (or even | |
99 | when they load they cannot be used due to missing HW support), | |
100 | developers still, opposing to distributors, might want to build such | |
101 | drivers to compile-test them. | |
102 | ||
103 | If you are a developer and want to build everything available, say Y | |
104 | here. If you are a user/distributor, say N here to exclude useless | |
105 | drivers to be distributed. | |
106 | ||
e846f0dc JN |
107 | config HEADER_TEST |
108 | bool "Compile test headers that should be standalone compilable" | |
109 | help | |
110 | Compile test headers listed in header-test-y target to ensure they are | |
111 | self-contained, i.e. compilable as standalone units. | |
112 | ||
113 | If you are a developer or tester and want to ensure the requested | |
114 | headers are self-contained, say Y here. Otherwise, choose N. | |
115 | ||
43c78d88 MY |
116 | config KERNEL_HEADER_TEST |
117 | bool "Compile test kernel headers" | |
118 | depends on HEADER_TEST | |
119 | help | |
120 | Headers in include/ are used to build external moduls. | |
121 | Compile test them to ensure they are self-contained, i.e. | |
122 | compilable as standalone units. | |
123 | ||
124 | If you are a developer or tester and want to ensure the headers | |
125 | in include/ are self-contained, say Y here. Otherwise, choose N. | |
126 | ||
d6fc9fcb MY |
127 | config UAPI_HEADER_TEST |
128 | bool "Compile test UAPI headers" | |
129 | depends on HEADER_TEST && HEADERS_INSTALL && CC_CAN_LINK | |
130 | help | |
131 | Compile test headers exported to user-space to ensure they are | |
132 | self-contained, i.e. compilable as standalone units. | |
133 | ||
134 | If you are a developer or tester and want to ensure the exported | |
135 | headers are self-contained, say Y here. Otherwise, choose N. | |
136 | ||
1da177e4 LT |
137 | config LOCALVERSION |
138 | string "Local version - append to kernel release" | |
139 | help | |
140 | Append an extra string to the end of your kernel version. | |
141 | This will show up when you type uname, for example. | |
142 | The string you set here will be appended after the contents of | |
143 | any files with a filename matching localversion* in your | |
144 | object and source tree, in that order. Your total string can | |
145 | be a maximum of 64 characters. | |
146 | ||
aaebf433 RA |
147 | config LOCALVERSION_AUTO |
148 | bool "Automatically append version information to the version string" | |
149 | default y | |
ac3339ba | 150 | depends on !COMPILE_TEST |
aaebf433 RA |
151 | help |
152 | This will try to automatically determine if the current tree is a | |
6e5a5420 RD |
153 | release tree by looking for git tags that belong to the current |
154 | top of tree revision. | |
aaebf433 RA |
155 | |
156 | A string of the format -gxxxxxxxx will be added to the localversion | |
6e5a5420 | 157 | if a git-based tree is found. The string generated by this will be |
aaebf433 | 158 | appended after any matching localversion* files, and after the value |
6e5a5420 | 159 | set in CONFIG_LOCALVERSION. |
aaebf433 | 160 | |
6e5a5420 RD |
161 | (The actual string used here is the first eight characters produced |
162 | by running the command: | |
163 | ||
164 | $ git rev-parse --verify HEAD | |
165 | ||
166 | which is done within the script "scripts/setlocalversion".) | |
aaebf433 | 167 | |
9afb719e LA |
168 | config BUILD_SALT |
169 | string "Build ID Salt" | |
170 | default "" | |
171 | help | |
172 | The build ID is used to link binaries and their debug info. Setting | |
173 | this option will use the value in the calculation of the build id. | |
174 | This is mostly useful for distributions which want to ensure the | |
175 | build is unique between builds. It's safe to leave the default. | |
176 | ||
2e9f3bdd PA |
177 | config HAVE_KERNEL_GZIP |
178 | bool | |
179 | ||
180 | config HAVE_KERNEL_BZIP2 | |
181 | bool | |
182 | ||
183 | config HAVE_KERNEL_LZMA | |
184 | bool | |
185 | ||
3ebe1243 LC |
186 | config HAVE_KERNEL_XZ |
187 | bool | |
188 | ||
7dd65feb AT |
189 | config HAVE_KERNEL_LZO |
190 | bool | |
191 | ||
e76e1fdf KL |
192 | config HAVE_KERNEL_LZ4 |
193 | bool | |
194 | ||
f16466af VG |
195 | config HAVE_KERNEL_UNCOMPRESSED |
196 | bool | |
197 | ||
30d65dbf | 198 | choice |
2e9f3bdd PA |
199 | prompt "Kernel compression mode" |
200 | default KERNEL_GZIP | |
f16466af | 201 | depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 || HAVE_KERNEL_UNCOMPRESSED |
2e9f3bdd | 202 | help |
30d65dbf AK |
203 | The linux kernel is a kind of self-extracting executable. |
204 | Several compression algorithms are available, which differ | |
205 | in efficiency, compression and decompression speed. | |
206 | Compression speed is only relevant when building a kernel. | |
207 | Decompression speed is relevant at each boot. | |
208 | ||
209 | If you have any problems with bzip2 or lzma compressed | |
210 | kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older | |
211 | version of this functionality (bzip2 only), for 2.4, was | |
212 | supplied by Christian Ludwig) | |
213 | ||
214 | High compression options are mostly useful for users, who | |
215 | are low on disk space (embedded systems), but for whom ram | |
216 | size matters less. | |
217 | ||
218 | If in doubt, select 'gzip' | |
219 | ||
220 | config KERNEL_GZIP | |
2e9f3bdd PA |
221 | bool "Gzip" |
222 | depends on HAVE_KERNEL_GZIP | |
223 | help | |
7dd65feb AT |
224 | The old and tried gzip compression. It provides a good balance |
225 | between compression ratio and decompression speed. | |
30d65dbf AK |
226 | |
227 | config KERNEL_BZIP2 | |
228 | bool "Bzip2" | |
2e9f3bdd | 229 | depends on HAVE_KERNEL_BZIP2 |
30d65dbf AK |
230 | help |
231 | Its compression ratio and speed is intermediate. | |
0a4dd35c | 232 | Decompression speed is slowest among the choices. The kernel |
2e9f3bdd PA |
233 | size is about 10% smaller with bzip2, in comparison to gzip. |
234 | Bzip2 uses a large amount of memory. For modern kernels you | |
235 | will need at least 8MB RAM or more for booting. | |
30d65dbf AK |
236 | |
237 | config KERNEL_LZMA | |
2e9f3bdd PA |
238 | bool "LZMA" |
239 | depends on HAVE_KERNEL_LZMA | |
240 | help | |
0a4dd35c RD |
241 | This compression algorithm's ratio is best. Decompression speed |
242 | is between gzip and bzip2. Compression is slowest. | |
243 | The kernel size is about 33% smaller with LZMA in comparison to gzip. | |
30d65dbf | 244 | |
3ebe1243 LC |
245 | config KERNEL_XZ |
246 | bool "XZ" | |
247 | depends on HAVE_KERNEL_XZ | |
248 | help | |
249 | XZ uses the LZMA2 algorithm and instruction set specific | |
250 | BCJ filters which can improve compression ratio of executable | |
251 | code. The size of the kernel is about 30% smaller with XZ in | |
252 | comparison to gzip. On architectures for which there is a BCJ | |
253 | filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ | |
254 | will create a few percent smaller kernel than plain LZMA. | |
255 | ||
256 | The speed is about the same as with LZMA: The decompression | |
257 | speed of XZ is better than that of bzip2 but worse than gzip | |
258 | and LZO. Compression is slow. | |
259 | ||
7dd65feb AT |
260 | config KERNEL_LZO |
261 | bool "LZO" | |
262 | depends on HAVE_KERNEL_LZO | |
263 | help | |
0a4dd35c | 264 | Its compression ratio is the poorest among the choices. The kernel |
681b3049 | 265 | size is about 10% bigger than gzip; however its speed |
7dd65feb AT |
266 | (both compression and decompression) is the fastest. |
267 | ||
e76e1fdf KL |
268 | config KERNEL_LZ4 |
269 | bool "LZ4" | |
270 | depends on HAVE_KERNEL_LZ4 | |
271 | help | |
272 | LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding. | |
273 | A preliminary version of LZ4 de/compression tool is available at | |
274 | <https://code.google.com/p/lz4/>. | |
275 | ||
276 | Its compression ratio is worse than LZO. The size of the kernel | |
277 | is about 8% bigger than LZO. But the decompression speed is | |
278 | faster than LZO. | |
279 | ||
f16466af VG |
280 | config KERNEL_UNCOMPRESSED |
281 | bool "None" | |
282 | depends on HAVE_KERNEL_UNCOMPRESSED | |
283 | help | |
284 | Produce uncompressed kernel image. This option is usually not what | |
285 | you want. It is useful for debugging the kernel in slow simulation | |
286 | environments, where decompressing and moving the kernel is awfully | |
287 | slow. This option allows early boot code to skip the decompressor | |
288 | and jump right at uncompressed kernel image. | |
289 | ||
30d65dbf AK |
290 | endchoice |
291 | ||
bd5dc17b JT |
292 | config DEFAULT_HOSTNAME |
293 | string "Default hostname" | |
294 | default "(none)" | |
295 | help | |
296 | This option determines the default system hostname before userspace | |
297 | calls sethostname(2). The kernel traditionally uses "(none)" here, | |
298 | but you may wish to use a different default here to make a minimal | |
299 | system more usable with less configuration. | |
300 | ||
17c46a6a CH |
301 | # |
302 | # For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can | |
303 | # add proper SWAP support to them, in which case this can be remove. | |
304 | # | |
305 | config ARCH_NO_SWAP | |
306 | bool | |
307 | ||
1da177e4 LT |
308 | config SWAP |
309 | bool "Support for paging of anonymous memory (swap)" | |
17c46a6a | 310 | depends on MMU && BLOCK && !ARCH_NO_SWAP |
1da177e4 LT |
311 | default y |
312 | help | |
313 | This option allows you to choose whether you want to have support | |
92c3504e | 314 | for so called swap devices or swap files in your kernel that are |
1da177e4 LT |
315 | used to provide more virtual memory than the actual RAM present |
316 | in your computer. If unsure say Y. | |
317 | ||
318 | config SYSVIPC | |
319 | bool "System V IPC" | |
1da177e4 LT |
320 | ---help--- |
321 | Inter Process Communication is a suite of library functions and | |
322 | system calls which let processes (running programs) synchronize and | |
323 | exchange information. It is generally considered to be a good thing, | |
324 | and some programs won't run unless you say Y here. In particular, if | |
325 | you want to run the DOS emulator dosemu under Linux (read the | |
326 | DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), | |
327 | you'll need to say Y here. | |
328 | ||
329 | You can find documentation about IPC with "info ipc" and also in | |
330 | section 6.4 of the Linux Programmer's Guide, available from | |
331 | <http://www.tldp.org/guides.html>. | |
332 | ||
a5494dcd EB |
333 | config SYSVIPC_SYSCTL |
334 | bool | |
335 | depends on SYSVIPC | |
336 | depends on SYSCTL | |
337 | default y | |
338 | ||
1da177e4 LT |
339 | config POSIX_MQUEUE |
340 | bool "POSIX Message Queues" | |
19c92399 | 341 | depends on NET |
1da177e4 LT |
342 | ---help--- |
343 | POSIX variant of message queues is a part of IPC. In POSIX message | |
344 | queues every message has a priority which decides about succession | |
345 | of receiving it by a process. If you want to compile and run | |
346 | programs written e.g. for Solaris with use of its POSIX message | |
b0e37650 | 347 | queues (functions mq_*) say Y here. |
1da177e4 LT |
348 | |
349 | POSIX message queues are visible as a filesystem called 'mqueue' | |
350 | and can be mounted somewhere if you want to do filesystem | |
351 | operations on message queues. | |
352 | ||
353 | If unsure, say Y. | |
354 | ||
bdc8e5f8 SH |
355 | config POSIX_MQUEUE_SYSCTL |
356 | bool | |
357 | depends on POSIX_MQUEUE | |
358 | depends on SYSCTL | |
359 | default y | |
360 | ||
226b4ccd KK |
361 | config CROSS_MEMORY_ATTACH |
362 | bool "Enable process_vm_readv/writev syscalls" | |
363 | depends on MMU | |
364 | default y | |
365 | help | |
366 | Enabling this option adds the system calls process_vm_readv and | |
367 | process_vm_writev which allow a process with the correct privileges | |
a2a368d9 | 368 | to directly read from or write to another process' address space. |
226b4ccd KK |
369 | See the man page for more details. |
370 | ||
69369a70 JT |
371 | config USELIB |
372 | bool "uselib syscall" | |
b2113a41 | 373 | def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION |
69369a70 JT |
374 | help |
375 | This option enables the uselib syscall, a system call used in the | |
376 | dynamic linker from libc5 and earlier. glibc does not use this | |
377 | system call. If you intend to run programs built on libc5 or | |
378 | earlier, you may need to enable this syscall. Current systems | |
379 | running glibc can safely disable this. | |
380 | ||
391dc69c FW |
381 | config AUDIT |
382 | bool "Auditing support" | |
383 | depends on NET | |
384 | help | |
385 | Enable auditing infrastructure that can be used with another | |
386 | kernel subsystem, such as SELinux (which requires this for | |
cb74ed27 PM |
387 | logging of avc messages output). System call auditing is included |
388 | on architectures which support it. | |
391dc69c | 389 | |
7a017721 AT |
390 | config HAVE_ARCH_AUDITSYSCALL |
391 | bool | |
392 | ||
391dc69c | 393 | config AUDITSYSCALL |
cb74ed27 | 394 | def_bool y |
7a017721 | 395 | depends on AUDIT && HAVE_ARCH_AUDITSYSCALL |
391dc69c FW |
396 | select FSNOTIFY |
397 | ||
391dc69c FW |
398 | source "kernel/irq/Kconfig" |
399 | source "kernel/time/Kconfig" | |
87a4c375 | 400 | source "kernel/Kconfig.preempt" |
391dc69c FW |
401 | |
402 | menu "CPU/Task time and stats accounting" | |
403 | ||
abf917cd FW |
404 | config VIRT_CPU_ACCOUNTING |
405 | bool | |
406 | ||
fdf9c356 FW |
407 | choice |
408 | prompt "Cputime accounting" | |
409 | default TICK_CPU_ACCOUNTING if !PPC64 | |
02fc8d37 | 410 | default VIRT_CPU_ACCOUNTING_NATIVE if PPC64 |
fdf9c356 FW |
411 | |
412 | # Kind of a stub config for the pure tick based cputime accounting | |
413 | config TICK_CPU_ACCOUNTING | |
414 | bool "Simple tick based cputime accounting" | |
c58b0df1 | 415 | depends on !S390 && !NO_HZ_FULL |
fdf9c356 FW |
416 | help |
417 | This is the basic tick based cputime accounting that maintains | |
418 | statistics about user, system and idle time spent on per jiffies | |
419 | granularity. | |
420 | ||
421 | If unsure, say Y. | |
422 | ||
abf917cd | 423 | config VIRT_CPU_ACCOUNTING_NATIVE |
b952741c | 424 | bool "Deterministic task and CPU time accounting" |
c58b0df1 | 425 | depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL |
abf917cd | 426 | select VIRT_CPU_ACCOUNTING |
b952741c FW |
427 | help |
428 | Select this option to enable more accurate task and CPU time | |
429 | accounting. This is done by reading a CPU counter on each | |
430 | kernel entry and exit and on transitions within the kernel | |
431 | between system, softirq and hardirq state, so there is a | |
432 | small performance impact. In the case of s390 or IBM POWER > 5, | |
433 | this also enables accounting of stolen time on logically-partitioned | |
434 | systems. | |
435 | ||
abf917cd FW |
436 | config VIRT_CPU_ACCOUNTING_GEN |
437 | bool "Full dynticks CPU time accounting" | |
ff3fb254 | 438 | depends on HAVE_CONTEXT_TRACKING |
554b0004 | 439 | depends on HAVE_VIRT_CPU_ACCOUNTING_GEN |
041a1574 | 440 | depends on GENERIC_CLOCKEVENTS |
abf917cd FW |
441 | select VIRT_CPU_ACCOUNTING |
442 | select CONTEXT_TRACKING | |
443 | help | |
444 | Select this option to enable task and CPU time accounting on full | |
445 | dynticks systems. This accounting is implemented by watching every | |
446 | kernel-user boundaries using the context tracking subsystem. | |
447 | The accounting is thus performed at the expense of some significant | |
448 | overhead. | |
449 | ||
450 | For now this is only useful if you are working on the full | |
451 | dynticks subsystem development. | |
452 | ||
453 | If unsure, say N. | |
454 | ||
b58c3584 RR |
455 | endchoice |
456 | ||
fdf9c356 FW |
457 | config IRQ_TIME_ACCOUNTING |
458 | bool "Fine granularity task level IRQ time accounting" | |
b58c3584 | 459 | depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE |
fdf9c356 FW |
460 | help |
461 | Select this option to enable fine granularity task irq time | |
462 | accounting. This is done by reading a timestamp on each | |
463 | transitions between softirq and hardirq state, so there can be a | |
464 | small performance impact. | |
465 | ||
466 | If in doubt, say N here. | |
467 | ||
11d4afd4 VG |
468 | config HAVE_SCHED_AVG_IRQ |
469 | def_bool y | |
470 | depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING | |
471 | depends on SMP | |
472 | ||
1da177e4 LT |
473 | config BSD_PROCESS_ACCT |
474 | bool "BSD Process Accounting" | |
2813893f | 475 | depends on MULTIUSER |
1da177e4 LT |
476 | help |
477 | If you say Y here, a user level program will be able to instruct the | |
478 | kernel (via a special system call) to write process accounting | |
479 | information to a file: whenever a process exits, information about | |
480 | that process will be appended to the file by the kernel. The | |
481 | information includes things such as creation time, owning user, | |
482 | command name, memory usage, controlling terminal etc. (the complete | |
483 | list is in the struct acct in <file:include/linux/acct.h>). It is | |
484 | up to the user level program to do useful things with this | |
485 | information. This is generally a good idea, so say Y. | |
486 | ||
487 | config BSD_PROCESS_ACCT_V3 | |
488 | bool "BSD Process Accounting version 3 file format" | |
489 | depends on BSD_PROCESS_ACCT | |
490 | default n | |
491 | help | |
492 | If you say Y here, the process accounting information is written | |
493 | in a new file format that also logs the process IDs of each | |
3903bf94 | 494 | process and its parent. Note that this file format is incompatible |
1da177e4 LT |
495 | with previous v0/v1/v2 file formats, so you will need updated tools |
496 | for processing it. A preliminary version of these tools is available | |
37a4c940 | 497 | at <http://www.gnu.org/software/acct/>. |
1da177e4 | 498 | |
c757249a | 499 | config TASKSTATS |
19c92399 | 500 | bool "Export task/process statistics through netlink" |
c757249a | 501 | depends on NET |
2813893f | 502 | depends on MULTIUSER |
c757249a SN |
503 | default n |
504 | help | |
505 | Export selected statistics for tasks/processes through the | |
506 | generic netlink interface. Unlike BSD process accounting, the | |
507 | statistics are available during the lifetime of tasks/processes as | |
508 | responses to commands. Like BSD accounting, they are sent to user | |
509 | space on task exit. | |
510 | ||
511 | Say N if unsure. | |
512 | ||
ca74e92b | 513 | config TASK_DELAY_ACCT |
19c92399 | 514 | bool "Enable per-task delay accounting" |
6f44993f | 515 | depends on TASKSTATS |
f6db8347 | 516 | select SCHED_INFO |
ca74e92b SN |
517 | help |
518 | Collect information on time spent by a task waiting for system | |
519 | resources like cpu, synchronous block I/O completion and swapping | |
520 | in pages. Such statistics can help in setting a task's priorities | |
521 | relative to other tasks for cpu, io, rss limits etc. | |
522 | ||
523 | Say N if unsure. | |
524 | ||
18f705f4 | 525 | config TASK_XACCT |
19c92399 | 526 | bool "Enable extended accounting over taskstats" |
18f705f4 AD |
527 | depends on TASKSTATS |
528 | help | |
529 | Collect extended task accounting data and send the data | |
530 | to userland for processing over the taskstats interface. | |
531 | ||
532 | Say N if unsure. | |
533 | ||
534 | config TASK_IO_ACCOUNTING | |
19c92399 | 535 | bool "Enable per-task storage I/O accounting" |
18f705f4 AD |
536 | depends on TASK_XACCT |
537 | help | |
538 | Collect information on the number of bytes of storage I/O which this | |
539 | task has caused. | |
540 | ||
541 | Say N if unsure. | |
542 | ||
eb414681 JW |
543 | config PSI |
544 | bool "Pressure stall information tracking" | |
545 | help | |
546 | Collect metrics that indicate how overcommitted the CPU, memory, | |
547 | and IO capacity are in the system. | |
548 | ||
549 | If you say Y here, the kernel will create /proc/pressure/ with the | |
550 | pressure statistics files cpu, memory, and io. These will indicate | |
551 | the share of walltime in which some or all tasks in the system are | |
552 | delayed due to contention of the respective resource. | |
553 | ||
2ce7135a JW |
554 | In kernels with cgroup support, cgroups (cgroup2 only) will |
555 | have cpu.pressure, memory.pressure, and io.pressure files, | |
556 | which aggregate pressure stalls for the grouped tasks only. | |
557 | ||
c3123552 | 558 | For more details see Documentation/accounting/psi.rst. |
eb414681 JW |
559 | |
560 | Say N if unsure. | |
561 | ||
e0c27447 JW |
562 | config PSI_DEFAULT_DISABLED |
563 | bool "Require boot parameter to enable pressure stall information tracking" | |
564 | default n | |
565 | depends on PSI | |
566 | help | |
567 | If set, pressure stall information tracking will be disabled | |
428a1cb4 BS |
568 | per default but can be enabled through passing psi=1 on the |
569 | kernel commandline during boot. | |
e0c27447 | 570 | |
7b2489d3 JW |
571 | This feature adds some code to the task wakeup and sleep |
572 | paths of the scheduler. The overhead is too low to affect | |
573 | common scheduling-intense workloads in practice (such as | |
574 | webservers, memcache), but it does show up in artificial | |
575 | scheduler stress tests, such as hackbench. | |
576 | ||
577 | If you are paranoid and not sure what the kernel will be | |
578 | used for, say Y. | |
579 | ||
580 | Say N if unsure. | |
581 | ||
391dc69c | 582 | endmenu # "CPU/Task time and stats accounting" |
d9817ebe | 583 | |
5c4991e2 FW |
584 | config CPU_ISOLATION |
585 | bool "CPU isolation" | |
414a2dc1 | 586 | depends on SMP || COMPILE_TEST |
2c43838c | 587 | default y |
5c4991e2 FW |
588 | help |
589 | Make sure that CPUs running critical tasks are not disturbed by | |
590 | any source of "noise" such as unbound workqueues, timers, kthreads... | |
2c43838c FW |
591 | Unbound jobs get offloaded to housekeeping CPUs. This is driven by |
592 | the "isolcpus=" boot parameter. | |
593 | ||
594 | Say Y if unsure. | |
5c4991e2 | 595 | |
0af92d46 | 596 | source "kernel/rcu/Kconfig" |
c903ff83 | 597 | |
de5b56ba VG |
598 | config BUILD_BIN2C |
599 | bool | |
600 | default n | |
601 | ||
1da177e4 | 602 | config IKCONFIG |
f2443ab6 | 603 | tristate "Kernel .config support" |
1da177e4 LT |
604 | ---help--- |
605 | This option enables the complete Linux kernel ".config" file | |
606 | contents to be saved in the kernel. It provides documentation | |
607 | of which kernel options are used in a running kernel or in an | |
608 | on-disk kernel. This information can be extracted from the kernel | |
609 | image file with the script scripts/extract-ikconfig and used as | |
610 | input to rebuild the current kernel or to build another kernel. | |
611 | It can also be extracted from a running kernel by reading | |
612 | /proc/config.gz if enabled (below). | |
613 | ||
614 | config IKCONFIG_PROC | |
615 | bool "Enable access to .config through /proc/config.gz" | |
616 | depends on IKCONFIG && PROC_FS | |
617 | ---help--- | |
618 | This option enables access to the kernel configuration file | |
619 | through /proc/config.gz. | |
620 | ||
f7b101d3 JFG |
621 | config IKHEADERS |
622 | tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz" | |
623 | depends on SYSFS | |
624 | help | |
625 | This option enables access to the in-kernel headers that are generated during | |
626 | the build process. These can be used to build eBPF tracing programs, | |
627 | or similar programs. If you build the headers as a module, a module called | |
628 | kheaders.ko is built which can be loaded on-demand to get access to headers. | |
43d8ce9d | 629 | |
794543a2 AJS |
630 | config LOG_BUF_SHIFT |
631 | int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" | |
fb39f98d | 632 | range 12 25 |
f17a32e9 | 633 | default 17 |
361e9dfb | 634 | depends on PRINTK |
794543a2 | 635 | help |
23b2899f LR |
636 | Select the minimal kernel log buffer size as a power of 2. |
637 | The final size is affected by LOG_CPU_MAX_BUF_SHIFT config | |
638 | parameter, see below. Any higher size also might be forced | |
639 | by "log_buf_len" boot parameter. | |
640 | ||
f17a32e9 | 641 | Examples: |
23b2899f | 642 | 17 => 128 KB |
f17a32e9 | 643 | 16 => 64 KB |
23b2899f LR |
644 | 15 => 32 KB |
645 | 14 => 16 KB | |
794543a2 AJS |
646 | 13 => 8 KB |
647 | 12 => 4 KB | |
648 | ||
23b2899f LR |
649 | config LOG_CPU_MAX_BUF_SHIFT |
650 | int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" | |
2240a31d | 651 | depends on SMP |
23b2899f LR |
652 | range 0 21 |
653 | default 12 if !BASE_SMALL | |
654 | default 0 if BASE_SMALL | |
361e9dfb | 655 | depends on PRINTK |
23b2899f LR |
656 | help |
657 | This option allows to increase the default ring buffer size | |
658 | according to the number of CPUs. The value defines the contribution | |
659 | of each CPU as a power of 2. The used space is typically only few | |
660 | lines however it might be much more when problems are reported, | |
661 | e.g. backtraces. | |
662 | ||
663 | The increased size means that a new buffer has to be allocated and | |
664 | the original static one is unused. It makes sense only on systems | |
665 | with more CPUs. Therefore this value is used only when the sum of | |
666 | contributions is greater than the half of the default kernel ring | |
667 | buffer as defined by LOG_BUF_SHIFT. The default values are set | |
668 | so that more than 64 CPUs are needed to trigger the allocation. | |
669 | ||
670 | Also this option is ignored when "log_buf_len" kernel parameter is | |
671 | used as it forces an exact (power of two) size of the ring buffer. | |
672 | ||
673 | The number of possible CPUs is used for this computation ignoring | |
5e0d8d59 GU |
674 | hotplugging making the computation optimal for the worst case |
675 | scenario while allowing a simple algorithm to be used from bootup. | |
23b2899f LR |
676 | |
677 | Examples shift values and their meaning: | |
678 | 17 => 128 KB for each CPU | |
679 | 16 => 64 KB for each CPU | |
680 | 15 => 32 KB for each CPU | |
681 | 14 => 16 KB for each CPU | |
682 | 13 => 8 KB for each CPU | |
683 | 12 => 4 KB for each CPU | |
684 | ||
f92bac3b SS |
685 | config PRINTK_SAFE_LOG_BUF_SHIFT |
686 | int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)" | |
427934b8 PM |
687 | range 10 21 |
688 | default 13 | |
f92bac3b | 689 | depends on PRINTK |
427934b8 | 690 | help |
f92bac3b SS |
691 | Select the size of an alternate printk per-CPU buffer where messages |
692 | printed from usafe contexts are temporary stored. One example would | |
693 | be NMI messages, another one - printk recursion. The messages are | |
694 | copied to the main log buffer in a safe context to avoid a deadlock. | |
695 | The value defines the size as a power of 2. | |
427934b8 | 696 | |
f92bac3b | 697 | Those messages are rare and limited. The largest one is when |
427934b8 PM |
698 | a backtrace is printed. It usually fits into 4KB. Select |
699 | 8KB if you want to be on the safe side. | |
700 | ||
701 | Examples: | |
702 | 17 => 128 KB for each CPU | |
703 | 16 => 64 KB for each CPU | |
704 | 15 => 32 KB for each CPU | |
705 | 14 => 16 KB for each CPU | |
706 | 13 => 8 KB for each CPU | |
707 | 12 => 4 KB for each CPU | |
708 | ||
a5574cf6 IM |
709 | # |
710 | # Architectures with an unreliable sched_clock() should select this: | |
711 | # | |
712 | config HAVE_UNSTABLE_SCHED_CLOCK | |
713 | bool | |
714 | ||
38ff87f7 SB |
715 | config GENERIC_SCHED_CLOCK |
716 | bool | |
717 | ||
69842cba PB |
718 | menu "Scheduler features" |
719 | ||
720 | config UCLAMP_TASK | |
721 | bool "Enable utilization clamping for RT/FAIR tasks" | |
722 | depends on CPU_FREQ_GOV_SCHEDUTIL | |
723 | help | |
724 | This feature enables the scheduler to track the clamped utilization | |
725 | of each CPU based on RUNNABLE tasks scheduled on that CPU. | |
726 | ||
727 | With this option, the user can specify the min and max CPU | |
728 | utilization allowed for RUNNABLE tasks. The max utilization defines | |
729 | the maximum frequency a task should use while the min utilization | |
730 | defines the minimum frequency it should use. | |
731 | ||
732 | Both min and max utilization clamp values are hints to the scheduler, | |
733 | aiming at improving its frequency selection policy, but they do not | |
734 | enforce or grant any specific bandwidth for tasks. | |
735 | ||
736 | If in doubt, say N. | |
737 | ||
738 | config UCLAMP_BUCKETS_COUNT | |
739 | int "Number of supported utilization clamp buckets" | |
740 | range 5 20 | |
741 | default 5 | |
742 | depends on UCLAMP_TASK | |
743 | help | |
744 | Defines the number of clamp buckets to use. The range of each bucket | |
745 | will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the | |
746 | number of clamp buckets the finer their granularity and the higher | |
747 | the precision of clamping aggregation and tracking at run-time. | |
748 | ||
749 | For example, with the minimum configuration value we will have 5 | |
750 | clamp buckets tracking 20% utilization each. A 25% boosted tasks will | |
751 | be refcounted in the [20..39]% bucket and will set the bucket clamp | |
752 | effective value to 25%. | |
753 | If a second 30% boosted task should be co-scheduled on the same CPU, | |
754 | that task will be refcounted in the same bucket of the first task and | |
755 | it will boost the bucket clamp effective value to 30%. | |
756 | The clamp effective value of a bucket is reset to its nominal value | |
757 | (20% in the example above) when there are no more tasks refcounted in | |
758 | that bucket. | |
759 | ||
760 | An additional boost/capping margin can be added to some tasks. In the | |
761 | example above the 25% task will be boosted to 30% until it exits the | |
762 | CPU. If that should be considered not acceptable on certain systems, | |
763 | it's always possible to reduce the margin by increasing the number of | |
764 | clamp buckets to trade off used memory for run-time tracking | |
765 | precision. | |
766 | ||
767 | If in doubt, use the default value. | |
768 | ||
769 | endmenu | |
770 | ||
be3a7284 AA |
771 | # |
772 | # For architectures that want to enable the support for NUMA-affine scheduler | |
773 | # balancing logic: | |
774 | # | |
775 | config ARCH_SUPPORTS_NUMA_BALANCING | |
776 | bool | |
777 | ||
72b252ae MG |
778 | # |
779 | # For architectures that prefer to flush all TLBs after a number of pages | |
780 | # are unmapped instead of sending one IPI per page to flush. The architecture | |
781 | # must provide guarantees on what happens if a clean TLB cache entry is | |
782 | # written after the unmap. Details are in mm/rmap.c near the check for | |
783 | # should_defer_flush. The architecture should also consider if the full flush | |
784 | # and the refill costs are offset by the savings of sending fewer IPIs. | |
785 | config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH | |
786 | bool | |
787 | ||
c12d3362 AB |
788 | config CC_HAS_INT128 |
789 | def_bool y | |
790 | depends on !$(cc-option,-D__SIZEOF_INT128__=0) | |
791 | ||
be5e610c PZ |
792 | # |
793 | # For architectures that know their GCC __int128 support is sound | |
794 | # | |
795 | config ARCH_SUPPORTS_INT128 | |
796 | bool | |
797 | ||
be3a7284 AA |
798 | # For architectures that (ab)use NUMA to represent different memory regions |
799 | # all cpu-local but of different latencies, such as SuperH. | |
800 | # | |
801 | config ARCH_WANT_NUMA_VARIABLE_LOCALITY | |
802 | bool | |
803 | ||
be3a7284 AA |
804 | config NUMA_BALANCING |
805 | bool "Memory placement aware NUMA scheduler" | |
be3a7284 AA |
806 | depends on ARCH_SUPPORTS_NUMA_BALANCING |
807 | depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY | |
808 | depends on SMP && NUMA && MIGRATION | |
809 | help | |
810 | This option adds support for automatic NUMA aware memory/task placement. | |
811 | The mechanism is quite primitive and is based on migrating memory when | |
6d56a410 | 812 | it has references to the node the task is running on. |
be3a7284 AA |
813 | |
814 | This system will be inactive on UMA systems. | |
815 | ||
6f7c97e8 AK |
816 | config NUMA_BALANCING_DEFAULT_ENABLED |
817 | bool "Automatically enable NUMA aware memory/task placement" | |
818 | default y | |
819 | depends on NUMA_BALANCING | |
820 | help | |
821 | If set, automatic NUMA balancing will be enabled if running on a NUMA | |
822 | machine. | |
823 | ||
23964d2d | 824 | menuconfig CGROUPS |
6341e62b | 825 | bool "Control Group support" |
2bd59d48 | 826 | select KERNFS |
5cdc38f9 | 827 | help |
23964d2d | 828 | This option adds support for grouping sets of processes together, for |
5cdc38f9 KH |
829 | use with process control subsystems such as Cpusets, CFS, memory |
830 | controls or device isolation. | |
831 | See | |
d6a3b247 | 832 | - Documentation/scheduler/sched-design-CFS.rst (CFS) |
da82c92f | 833 | - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation |
45ce80fb | 834 | and resource control) |
5cdc38f9 KH |
835 | |
836 | Say N if unsure. | |
837 | ||
23964d2d LZ |
838 | if CGROUPS |
839 | ||
3e32cb2e JW |
840 | config PAGE_COUNTER |
841 | bool | |
842 | ||
c255a458 | 843 | config MEMCG |
a0166ec4 | 844 | bool "Memory controller" |
3e32cb2e | 845 | select PAGE_COUNTER |
79bd9814 | 846 | select EVENTFD |
00f0b825 | 847 | help |
a0166ec4 | 848 | Provides control over the memory footprint of tasks in a cgroup. |
00f0b825 | 849 | |
c255a458 | 850 | config MEMCG_SWAP |
a0166ec4 | 851 | bool "Swap controller" |
c255a458 | 852 | depends on MEMCG && SWAP |
c077719b | 853 | help |
a0166ec4 JW |
854 | Provides control over the swap space consumed by tasks in a cgroup. |
855 | ||
c255a458 | 856 | config MEMCG_SWAP_ENABLED |
a0166ec4 | 857 | bool "Swap controller enabled by default" |
c255a458 | 858 | depends on MEMCG_SWAP |
a42c390c MH |
859 | default y |
860 | help | |
861 | Memory Resource Controller Swap Extension comes with its price in | |
862 | a bigger memory consumption. General purpose distribution kernels | |
43d547f9 | 863 | which want to enable the feature but keep it disabled by default |
07555ac1 | 864 | and let the user enable it by swapaccount=1 boot command line |
a42c390c MH |
865 | parameter should have this option unselected. |
866 | For those who want to have the feature enabled by default should | |
867 | select this option (if, for some reason, they need to disable it | |
00a66d29 | 868 | then swapaccount=0 does the trick). |
c077719b | 869 | |
84c07d11 KT |
870 | config MEMCG_KMEM |
871 | bool | |
872 | depends on MEMCG && !SLOB | |
873 | default y | |
874 | ||
6bf024e6 JW |
875 | config BLK_CGROUP |
876 | bool "IO controller" | |
877 | depends on BLOCK | |
2bc64a20 | 878 | default n |
6bf024e6 JW |
879 | ---help--- |
880 | Generic block IO controller cgroup interface. This is the common | |
881 | cgroup interface which should be used by various IO controlling | |
882 | policies. | |
2bc64a20 | 883 | |
6bf024e6 JW |
884 | Currently, CFQ IO scheduler uses it to recognize task groups and |
885 | control disk bandwidth allocation (proportional time slice allocation) | |
886 | to such task groups. It is also used by bio throttling logic in | |
887 | block layer to implement upper limit in IO rates on a device. | |
e5d1367f | 888 | |
6bf024e6 JW |
889 | This option only enables generic Block IO controller infrastructure. |
890 | One needs to also enable actual IO controlling logic/policy. For | |
891 | enabling proportional weight division of disk bandwidth in CFQ, set | |
892 | CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set | |
893 | CONFIG_BLK_DEV_THROTTLING=y. | |
894 | ||
da82c92f | 895 | See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information. |
6bf024e6 | 896 | |
6bf024e6 JW |
897 | config CGROUP_WRITEBACK |
898 | bool | |
899 | depends on MEMCG && BLK_CGROUP | |
900 | default y | |
e5d1367f | 901 | |
7c941438 | 902 | menuconfig CGROUP_SCHED |
a0166ec4 | 903 | bool "CPU controller" |
7c941438 DG |
904 | default n |
905 | help | |
906 | This feature lets CPU scheduler recognize task groups and control CPU | |
907 | bandwidth allocation to such task groups. It uses cgroups to group | |
908 | tasks. | |
909 | ||
910 | if CGROUP_SCHED | |
911 | config FAIR_GROUP_SCHED | |
912 | bool "Group scheduling for SCHED_OTHER" | |
913 | depends on CGROUP_SCHED | |
914 | default CGROUP_SCHED | |
915 | ||
ab84d31e PT |
916 | config CFS_BANDWIDTH |
917 | bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" | |
ab84d31e PT |
918 | depends on FAIR_GROUP_SCHED |
919 | default n | |
920 | help | |
921 | This option allows users to define CPU bandwidth rates (limits) for | |
922 | tasks running within the fair group scheduler. Groups with no limit | |
923 | set are considered to be unconstrained and will run with no | |
924 | restriction. | |
d6a3b247 | 925 | See Documentation/scheduler/sched-bwc.rst for more information. |
ab84d31e | 926 | |
7c941438 DG |
927 | config RT_GROUP_SCHED |
928 | bool "Group scheduling for SCHED_RR/FIFO" | |
7c941438 DG |
929 | depends on CGROUP_SCHED |
930 | default n | |
931 | help | |
932 | This feature lets you explicitly allocate real CPU bandwidth | |
32bd7eb5 | 933 | to task groups. If enabled, it will also make it impossible to |
7c941438 DG |
934 | schedule realtime tasks for non-root users until you allocate |
935 | realtime bandwidth for them. | |
d6a3b247 | 936 | See Documentation/scheduler/sched-rt-group.rst for more information. |
7c941438 DG |
937 | |
938 | endif #CGROUP_SCHED | |
939 | ||
2480c093 PB |
940 | config UCLAMP_TASK_GROUP |
941 | bool "Utilization clamping per group of tasks" | |
942 | depends on CGROUP_SCHED | |
943 | depends on UCLAMP_TASK | |
944 | default n | |
945 | help | |
946 | This feature enables the scheduler to track the clamped utilization | |
947 | of each CPU based on RUNNABLE tasks currently scheduled on that CPU. | |
948 | ||
949 | When this option is enabled, the user can specify a min and max | |
950 | CPU bandwidth which is allowed for each single task in a group. | |
951 | The max bandwidth allows to clamp the maximum frequency a task | |
952 | can use, while the min bandwidth allows to define a minimum | |
953 | frequency a task will always use. | |
954 | ||
955 | When task group based utilization clamping is enabled, an eventually | |
956 | specified task-specific clamp value is constrained by the cgroup | |
957 | specified clamp value. Both minimum and maximum task clamping cannot | |
958 | be bigger than the corresponding clamping defined at task group level. | |
959 | ||
960 | If in doubt, say N. | |
961 | ||
6bf024e6 JW |
962 | config CGROUP_PIDS |
963 | bool "PIDs controller" | |
964 | help | |
965 | Provides enforcement of process number limits in the scope of a | |
966 | cgroup. Any attempt to fork more processes than is allowed in the | |
967 | cgroup will fail. PIDs are fundamentally a global resource because it | |
968 | is fairly trivial to reach PID exhaustion before you reach even a | |
969 | conservative kmemcg limit. As a result, it is possible to grind a | |
970 | system to halt without being limited by other cgroup policies. The | |
6cc578df | 971 | PIDs controller is designed to stop this from happening. |
6bf024e6 JW |
972 | |
973 | It should be noted that organisational operations (such as attaching | |
98076833 | 974 | to a cgroup hierarchy) will *not* be blocked by the PIDs controller, |
6bf024e6 JW |
975 | since the PIDs limit only affects a process's ability to fork, not to |
976 | attach to a cgroup. | |
977 | ||
39d3e758 PP |
978 | config CGROUP_RDMA |
979 | bool "RDMA controller" | |
980 | help | |
981 | Provides enforcement of RDMA resources defined by IB stack. | |
982 | It is fairly easy for consumers to exhaust RDMA resources, which | |
983 | can result into resource unavailability to other consumers. | |
984 | RDMA controller is designed to stop this from happening. | |
985 | Attaching processes with active RDMA resources to the cgroup | |
986 | hierarchy is allowed even if can cross the hierarchy's limit. | |
987 | ||
6bf024e6 JW |
988 | config CGROUP_FREEZER |
989 | bool "Freezer controller" | |
990 | help | |
991 | Provides a way to freeze and unfreeze all tasks in a | |
992 | cgroup. | |
993 | ||
489c2a20 JW |
994 | This option affects the ORIGINAL cgroup interface. The cgroup2 memory |
995 | controller includes important in-kernel memory consumers per default. | |
996 | ||
997 | If you're using cgroup2, say N. | |
998 | ||
6bf024e6 JW |
999 | config CGROUP_HUGETLB |
1000 | bool "HugeTLB controller" | |
1001 | depends on HUGETLB_PAGE | |
1002 | select PAGE_COUNTER | |
afc24d49 | 1003 | default n |
6bf024e6 JW |
1004 | help |
1005 | Provides a cgroup controller for HugeTLB pages. | |
1006 | When you enable this, you can put a per cgroup limit on HugeTLB usage. | |
1007 | The limit is enforced during page fault. Since HugeTLB doesn't | |
1008 | support page reclaim, enforcing the limit at page fault time implies | |
1009 | that, the application will get SIGBUS signal if it tries to access | |
1010 | HugeTLB pages beyond its limit. This requires the application to know | |
1011 | beforehand how much HugeTLB pages it would require for its use. The | |
1012 | control group is tracked in the third page lru pointer. This means | |
1013 | that we cannot use the controller with huge page less than 3 pages. | |
afc24d49 | 1014 | |
6bf024e6 JW |
1015 | config CPUSETS |
1016 | bool "Cpuset controller" | |
e1d4eeec | 1017 | depends on SMP |
6bf024e6 JW |
1018 | help |
1019 | This option will let you create and manage CPUSETs which | |
1020 | allow dynamically partitioning a system into sets of CPUs and | |
1021 | Memory Nodes and assigning tasks to run only within those sets. | |
1022 | This is primarily useful on large SMP or NUMA systems. | |
afc24d49 | 1023 | |
6bf024e6 | 1024 | Say N if unsure. |
afc24d49 | 1025 | |
6bf024e6 JW |
1026 | config PROC_PID_CPUSET |
1027 | bool "Include legacy /proc/<pid>/cpuset file" | |
1028 | depends on CPUSETS | |
1029 | default y | |
afc24d49 | 1030 | |
6bf024e6 JW |
1031 | config CGROUP_DEVICE |
1032 | bool "Device controller" | |
1033 | help | |
1034 | Provides a cgroup controller implementing whitelists for | |
1035 | devices which a process in the cgroup can mknod or open. | |
1036 | ||
1037 | config CGROUP_CPUACCT | |
1038 | bool "Simple CPU accounting controller" | |
1039 | help | |
1040 | Provides a simple controller for monitoring the | |
1041 | total CPU consumed by the tasks in a cgroup. | |
1042 | ||
1043 | config CGROUP_PERF | |
1044 | bool "Perf controller" | |
1045 | depends on PERF_EVENTS | |
1046 | help | |
1047 | This option extends the perf per-cpu mode to restrict monitoring | |
1048 | to threads which belong to the cgroup specified and run on the | |
1049 | designated cpu. | |
1050 | ||
1051 | Say N if unsure. | |
1052 | ||
30070984 DM |
1053 | config CGROUP_BPF |
1054 | bool "Support for eBPF programs attached to cgroups" | |
483c4933 AL |
1055 | depends on BPF_SYSCALL |
1056 | select SOCK_CGROUP_DATA | |
30070984 DM |
1057 | help |
1058 | Allow attaching eBPF programs to a cgroup using the bpf(2) | |
1059 | syscall command BPF_PROG_ATTACH. | |
1060 | ||
1061 | In which context these programs are accessed depends on the type | |
1062 | of attachment. For instance, programs that are attached using | |
1063 | BPF_CGROUP_INET_INGRESS will be executed on the ingress path of | |
1064 | inet sockets. | |
1065 | ||
6bf024e6 | 1066 | config CGROUP_DEBUG |
23b0be48 | 1067 | bool "Debug controller" |
afc24d49 | 1068 | default n |
23b0be48 | 1069 | depends on DEBUG_KERNEL |
6bf024e6 JW |
1070 | help |
1071 | This option enables a simple controller that exports | |
23b0be48 WL |
1072 | debugging information about the cgroups framework. This |
1073 | controller is for control cgroup debugging only. Its | |
1074 | interfaces are not stable. | |
afc24d49 | 1075 | |
6bf024e6 | 1076 | Say N. |
89e9b9e0 | 1077 | |
73b35147 AB |
1078 | config SOCK_CGROUP_DATA |
1079 | bool | |
1080 | default n | |
1081 | ||
23964d2d | 1082 | endif # CGROUPS |
c077719b | 1083 | |
8dd2a82c | 1084 | menuconfig NAMESPACES |
6a108a14 | 1085 | bool "Namespaces support" if EXPERT |
2813893f | 1086 | depends on MULTIUSER |
6a108a14 | 1087 | default !EXPERT |
c5289a69 PE |
1088 | help |
1089 | Provides the way to make tasks work with different objects using | |
1090 | the same id. For example same IPC id may refer to different objects | |
1091 | or same user id or pid may refer to different tasks when used in | |
1092 | different namespaces. | |
1093 | ||
8dd2a82c DL |
1094 | if NAMESPACES |
1095 | ||
58bfdd6d PE |
1096 | config UTS_NS |
1097 | bool "UTS namespace" | |
17a6d441 | 1098 | default y |
58bfdd6d PE |
1099 | help |
1100 | In this namespace tasks see different info provided with the | |
1101 | uname() system call | |
1102 | ||
ae5e1b22 PE |
1103 | config IPC_NS |
1104 | bool "IPC namespace" | |
8dd2a82c | 1105 | depends on (SYSVIPC || POSIX_MQUEUE) |
17a6d441 | 1106 | default y |
ae5e1b22 PE |
1107 | help |
1108 | In this namespace tasks work with IPC ids which correspond to | |
614b84cf | 1109 | different IPC objects in different namespaces. |
ae5e1b22 | 1110 | |
aee16ce7 | 1111 | config USER_NS |
19c92399 | 1112 | bool "User namespace" |
5673a94c | 1113 | default n |
aee16ce7 PE |
1114 | help |
1115 | This allows containers, i.e. vservers, to use user namespaces | |
1116 | to provide different user info for different servers. | |
e11f0ae3 EB |
1117 | |
1118 | When user namespaces are enabled in the kernel it is | |
d886f4e4 JW |
1119 | recommended that the MEMCG option also be enabled and that |
1120 | user-space use the memory control groups to limit the amount | |
1121 | of memory a memory unprivileged users can use. | |
e11f0ae3 | 1122 | |
aee16ce7 PE |
1123 | If unsure, say N. |
1124 | ||
74bd59bb | 1125 | config PID_NS |
9bd38c2c | 1126 | bool "PID Namespaces" |
17a6d441 | 1127 | default y |
74bd59bb | 1128 | help |
12d2b8f9 | 1129 | Support process id namespaces. This allows having multiple |
692105b8 | 1130 | processes with the same pid as long as they are in different |
74bd59bb PE |
1131 | pid namespaces. This is a building block of containers. |
1132 | ||
d6eb633f MH |
1133 | config NET_NS |
1134 | bool "Network namespace" | |
8dd2a82c | 1135 | depends on NET |
17a6d441 | 1136 | default y |
d6eb633f MH |
1137 | help |
1138 | Allow user space to create what appear to be multiple instances | |
1139 | of the network stack. | |
1140 | ||
8dd2a82c DL |
1141 | endif # NAMESPACES |
1142 | ||
5cb366bb AR |
1143 | config CHECKPOINT_RESTORE |
1144 | bool "Checkpoint/restore support" | |
1145 | select PROC_CHILDREN | |
1146 | default n | |
1147 | help | |
1148 | Enables additional kernel features in a sake of checkpoint/restore. | |
1149 | In particular it adds auxiliary prctl codes to setup process text, | |
1150 | data and heap segment sizes, and a few additional /proc filesystem | |
1151 | entries. | |
1152 | ||
1153 | If unsure, say N here. | |
1154 | ||
5091faa4 MG |
1155 | config SCHED_AUTOGROUP |
1156 | bool "Automatic process group scheduling" | |
5091faa4 MG |
1157 | select CGROUPS |
1158 | select CGROUP_SCHED | |
1159 | select FAIR_GROUP_SCHED | |
1160 | help | |
1161 | This option optimizes the scheduler for common desktop workloads by | |
1162 | automatically creating and populating task groups. This separation | |
1163 | of workloads isolates aggressive CPU burners (like build jobs) from | |
1164 | desktop applications. Task group autogeneration is currently based | |
1165 | upon task session. | |
1166 | ||
7af37bec | 1167 | config SYSFS_DEPRECATED |
5d6a4ea5 | 1168 | bool "Enable deprecated sysfs features to support old userspace tools" |
7af37bec DL |
1169 | depends on SYSFS |
1170 | default n | |
1171 | help | |
1172 | This option adds code that switches the layout of the "block" class | |
1173 | devices, to not show up in /sys/class/block/, but only in | |
1174 | /sys/block/. | |
1175 | ||
1176 | This switch is only active when the sysfs.deprecated=1 boot option is | |
1177 | passed or the SYSFS_DEPRECATED_V2 option is set. | |
1178 | ||
1179 | This option allows new kernels to run on old distributions and tools, | |
1180 | which might get confused by /sys/class/block/. Since 2007/2008 all | |
1181 | major distributions and tools handle this just fine. | |
1182 | ||
1183 | Recent distributions and userspace tools after 2009/2010 depend on | |
1184 | the existence of /sys/class/block/, and will not work with this | |
1185 | option enabled. | |
1186 | ||
1187 | Only if you are using a new kernel on an old distribution, you might | |
1188 | need to say Y here. | |
1189 | ||
1190 | config SYSFS_DEPRECATED_V2 | |
5d6a4ea5 | 1191 | bool "Enable deprecated sysfs features by default" |
7af37bec DL |
1192 | default n |
1193 | depends on SYSFS | |
1194 | depends on SYSFS_DEPRECATED | |
1195 | help | |
1196 | Enable deprecated sysfs by default. | |
1197 | ||
1198 | See the CONFIG_SYSFS_DEPRECATED option for more details about this | |
1199 | option. | |
1200 | ||
1201 | Only if you are using a new kernel on an old distribution, you might | |
1202 | need to say Y here. Even then, odds are you would not need it | |
1203 | enabled, you can always pass the boot option if absolutely necessary. | |
1204 | ||
1205 | config RELAY | |
1206 | bool "Kernel->user space relay support (formerly relayfs)" | |
26b5679e | 1207 | select IRQ_WORK |
7af37bec DL |
1208 | help |
1209 | This option enables support for relay interface support in | |
1210 | certain file systems (such as debugfs). | |
1211 | It is designed to provide an efficient mechanism for tools and | |
1212 | facilities to relay large amounts of data from kernel space to | |
1213 | user space. | |
1214 | ||
1215 | If unsure, say N. | |
1216 | ||
f991633d DG |
1217 | config BLK_DEV_INITRD |
1218 | bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" | |
f991633d DG |
1219 | help |
1220 | The initial RAM filesystem is a ramfs which is loaded by the | |
1221 | boot loader (loadlin or lilo) and that is mounted as root | |
1222 | before the normal boot procedure. It is typically used to | |
1223 | load modules needed to mount the "real" root file system, | |
8c27ceff | 1224 | etc. See <file:Documentation/admin-guide/initrd.rst> for details. |
f991633d DG |
1225 | |
1226 | If RAM disk support (BLK_DEV_RAM) is also included, this | |
1227 | also enables initial RAM disk (initrd) support and adds | |
1228 | 15 Kbytes (more on some other architectures) to the kernel size. | |
1229 | ||
1230 | If unsure say Y. | |
1231 | ||
c33df4ea JPS |
1232 | if BLK_DEV_INITRD |
1233 | ||
dbec4866 SR |
1234 | source "usr/Kconfig" |
1235 | ||
c33df4ea JPS |
1236 | endif |
1237 | ||
877417e6 AB |
1238 | choice |
1239 | prompt "Compiler optimization level" | |
2cc3ce24 | 1240 | default CC_OPTIMIZE_FOR_PERFORMANCE |
877417e6 AB |
1241 | |
1242 | config CC_OPTIMIZE_FOR_PERFORMANCE | |
15f5db60 | 1243 | bool "Optimize for performance (-O2)" |
877417e6 AB |
1244 | help |
1245 | This is the default optimization level for the kernel, building | |
1246 | with the "-O2" compiler flag for best performance and most | |
1247 | helpful compile-time warnings. | |
1248 | ||
15f5db60 MY |
1249 | config CC_OPTIMIZE_FOR_PERFORMANCE_O3 |
1250 | bool "Optimize more for performance (-O3)" | |
1251 | depends on ARC | |
b303c6df | 1252 | imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED # avoid false positives |
c45b4f1f | 1253 | help |
15f5db60 MY |
1254 | Choosing this option will pass "-O3" to your compiler to optimize |
1255 | the kernel yet more for performance. | |
c45b4f1f | 1256 | |
c45b4f1f | 1257 | config CC_OPTIMIZE_FOR_SIZE |
15f5db60 | 1258 | bool "Optimize for size (-Os)" |
b303c6df | 1259 | imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED # avoid false positives |
c45b4f1f | 1260 | help |
ce3b487f MY |
1261 | Choosing this option will pass "-Os" to your compiler resulting |
1262 | in a smaller kernel. | |
c45b4f1f | 1263 | |
877417e6 AB |
1264 | endchoice |
1265 | ||
5d20ee31 NP |
1266 | config HAVE_LD_DEAD_CODE_DATA_ELIMINATION |
1267 | bool | |
1268 | help | |
1269 | This requires that the arch annotates or otherwise protects | |
1270 | its external entry points from being discarded. Linker scripts | |
1271 | must also merge .text.*, .data.*, and .bss.* correctly into | |
1272 | output sections. Care must be taken not to pull in unrelated | |
1273 | sections (e.g., '.text.init'). Typically '.' in section names | |
1274 | is used to distinguish them from label names / C identifiers. | |
1275 | ||
1276 | config LD_DEAD_CODE_DATA_ELIMINATION | |
1277 | bool "Dead code and data elimination (EXPERIMENTAL)" | |
1278 | depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION | |
1279 | depends on EXPERT | |
16fd20aa | 1280 | depends on !(FUNCTION_TRACER && CC_IS_GCC && GCC_VERSION < 40800) |
e85d1d65 MY |
1281 | depends on $(cc-option,-ffunction-sections -fdata-sections) |
1282 | depends on $(ld-option,--gc-sections) | |
5d20ee31 | 1283 | help |
8b9d2712 MY |
1284 | Enable this if you want to do dead code and data elimination with |
1285 | the linker by compiling with -ffunction-sections -fdata-sections, | |
1286 | and linking with --gc-sections. | |
5d20ee31 NP |
1287 | |
1288 | This can reduce on disk and in-memory size of the kernel | |
1289 | code and static data, particularly for small configs and | |
1290 | on small systems. This has the possibility of introducing | |
1291 | silently broken kernel if the required annotations are not | |
1292 | present. This option is not well tested yet, so use at your | |
1293 | own risk. | |
1294 | ||
0847062a RD |
1295 | config SYSCTL |
1296 | bool | |
1297 | ||
657a5209 MF |
1298 | config HAVE_UID16 |
1299 | bool | |
1300 | ||
1301 | config SYSCTL_EXCEPTION_TRACE | |
1302 | bool | |
1303 | help | |
1304 | Enable support for /proc/sys/debug/exception-trace. | |
1305 | ||
1306 | config SYSCTL_ARCH_UNALIGN_NO_WARN | |
1307 | bool | |
1308 | help | |
1309 | Enable support for /proc/sys/kernel/ignore-unaligned-usertrap | |
1310 | Allows arch to define/use @no_unaligned_warning to possibly warn | |
1311 | about unaligned access emulation going on under the hood. | |
1312 | ||
1313 | config SYSCTL_ARCH_UNALIGN_ALLOW | |
1314 | bool | |
1315 | help | |
1316 | Enable support for /proc/sys/kernel/unaligned-trap | |
1317 | Allows arches to define/use @unaligned_enabled to runtime toggle | |
1318 | the unaligned access emulation. | |
1319 | see arch/parisc/kernel/unaligned.c for reference | |
1320 | ||
657a5209 MF |
1321 | config HAVE_PCSPKR_PLATFORM |
1322 | bool | |
1323 | ||
f89b7755 AS |
1324 | # interpreter that classic socket filters depend on |
1325 | config BPF | |
1326 | bool | |
1327 | ||
6a108a14 DR |
1328 | menuconfig EXPERT |
1329 | bool "Configure standard kernel features (expert users)" | |
f505c553 JT |
1330 | # Unhide debug options, to make the on-by-default options visible |
1331 | select DEBUG_KERNEL | |
1da177e4 LT |
1332 | help |
1333 | This option allows certain base kernel options and settings | |
1334 | to be disabled or tweaked. This is for specialized | |
1335 | environments which can tolerate a "non-standard" kernel. | |
1336 | Only use this if you really know what you are doing. | |
1337 | ||
ae81f9e3 | 1338 | config UID16 |
6a108a14 | 1339 | bool "Enable 16-bit UID system calls" if EXPERT |
2813893f | 1340 | depends on HAVE_UID16 && MULTIUSER |
ae81f9e3 CE |
1341 | default y |
1342 | help | |
1343 | This enables the legacy 16-bit UID syscall wrappers. | |
1344 | ||
2813893f IM |
1345 | config MULTIUSER |
1346 | bool "Multiple users, groups and capabilities support" if EXPERT | |
1347 | default y | |
1348 | help | |
1349 | This option enables support for non-root users, groups and | |
1350 | capabilities. | |
1351 | ||
1352 | If you say N here, all processes will run with UID 0, GID 0, and all | |
1353 | possible capabilities. Saying N here also compiles out support for | |
1354 | system calls related to UIDs, GIDs, and capabilities, such as setuid, | |
1355 | setgid, and capset. | |
1356 | ||
1357 | If unsure, say Y here. | |
1358 | ||
f6187769 FF |
1359 | config SGETMASK_SYSCALL |
1360 | bool "sgetmask/ssetmask syscalls support" if EXPERT | |
a687a533 | 1361 | def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH |
f6187769 FF |
1362 | ---help--- |
1363 | sys_sgetmask and sys_ssetmask are obsolete system calls | |
1364 | no longer supported in libc but still enabled by default in some | |
1365 | architectures. | |
1366 | ||
1367 | If unsure, leave the default option here. | |
1368 | ||
6af9f7bf FF |
1369 | config SYSFS_SYSCALL |
1370 | bool "Sysfs syscall support" if EXPERT | |
1371 | default y | |
1372 | ---help--- | |
1373 | sys_sysfs is an obsolete system call no longer supported in libc. | |
1374 | Note that disabling this option is more secure but might break | |
1375 | compatibility with some systems. | |
1376 | ||
1377 | If unsure say Y here. | |
1378 | ||
d1b069f5 RD |
1379 | config FHANDLE |
1380 | bool "open by fhandle syscalls" if EXPERT | |
1381 | select EXPORTFS | |
1382 | default y | |
1383 | help | |
1384 | If you say Y here, a user level program will be able to map | |
1385 | file names to handle and then later use the handle for | |
1386 | different file system operations. This is useful in implementing | |
1387 | userspace file servers, which now track files using handles instead | |
1388 | of names. The handle would remain the same even if file names | |
1389 | get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) | |
1390 | syscalls. | |
1391 | ||
baa73d9e NP |
1392 | config POSIX_TIMERS |
1393 | bool "Posix Clocks & timers" if EXPERT | |
1394 | default y | |
1395 | help | |
1396 | This includes native support for POSIX timers to the kernel. | |
1397 | Some embedded systems have no use for them and therefore they | |
1398 | can be configured out to reduce the size of the kernel image. | |
1399 | ||
1400 | When this option is disabled, the following syscalls won't be | |
1401 | available: timer_create, timer_gettime: timer_getoverrun, | |
1402 | timer_settime, timer_delete, clock_adjtime, getitimer, | |
1403 | setitimer, alarm. Furthermore, the clock_settime, clock_gettime, | |
1404 | clock_getres and clock_nanosleep syscalls will be limited to | |
1405 | CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. | |
1406 | ||
1407 | If unsure say y. | |
1408 | ||
d59745ce MM |
1409 | config PRINTK |
1410 | default y | |
6a108a14 | 1411 | bool "Enable support for printk" if EXPERT |
74876a98 | 1412 | select IRQ_WORK |
d59745ce MM |
1413 | help |
1414 | This option enables normal printk support. Removing it | |
1415 | eliminates most of the message strings from the kernel image | |
1416 | and makes the kernel more or less silent. As this makes it | |
1417 | very difficult to diagnose system problems, saying N here is | |
1418 | strongly discouraged. | |
1419 | ||
42a0bb3f PM |
1420 | config PRINTK_NMI |
1421 | def_bool y | |
1422 | depends on PRINTK | |
1423 | depends on HAVE_NMI | |
1424 | ||
c8538a7a | 1425 | config BUG |
6a108a14 | 1426 | bool "BUG() support" if EXPERT |
c8538a7a MM |
1427 | default y |
1428 | help | |
1429 | Disabling this option eliminates support for BUG and WARN, reducing | |
1430 | the size of your kernel image and potentially quietly ignoring | |
1431 | numerous fatal conditions. You should only consider disabling this | |
1432 | option for embedded systems with no facilities for reporting errors. | |
1433 | Just say Y. | |
1434 | ||
708e9a79 | 1435 | config ELF_CORE |
046d662f | 1436 | depends on COREDUMP |
708e9a79 | 1437 | default y |
6a108a14 | 1438 | bool "Enable ELF core dumps" if EXPERT |
708e9a79 MM |
1439 | help |
1440 | Enable support for generating core dumps. Disabling saves about 4k. | |
1441 | ||
8761f1ab | 1442 | |
e5e1d3cb | 1443 | config PCSPKR_PLATFORM |
6a108a14 | 1444 | bool "Enable PC-Speaker support" if EXPERT |
8761f1ab | 1445 | depends on HAVE_PCSPKR_PLATFORM |
15f304b6 | 1446 | select I8253_LOCK |
e5e1d3cb SS |
1447 | default y |
1448 | help | |
1449 | This option allows to disable the internal PC-Speaker | |
1450 | support, saving some memory. | |
1451 | ||
1da177e4 LT |
1452 | config BASE_FULL |
1453 | default y | |
6a108a14 | 1454 | bool "Enable full-sized data structures for core" if EXPERT |
1da177e4 LT |
1455 | help |
1456 | Disabling this option reduces the size of miscellaneous core | |
1457 | kernel data structures. This saves memory on small machines, | |
1458 | but may reduce performance. | |
1459 | ||
1460 | config FUTEX | |
6a108a14 | 1461 | bool "Enable futex support" if EXPERT |
1da177e4 | 1462 | default y |
bc2eecd7 | 1463 | imply RT_MUTEXES |
1da177e4 LT |
1464 | help |
1465 | Disabling this option will cause the kernel to be built without | |
1466 | support for "fast userspace mutexes". The resulting kernel may not | |
1467 | run glibc-based applications correctly. | |
1468 | ||
bc2eecd7 NP |
1469 | config FUTEX_PI |
1470 | bool | |
1471 | depends on FUTEX && RT_MUTEXES | |
1472 | default y | |
1473 | ||
03b8c7b6 HC |
1474 | config HAVE_FUTEX_CMPXCHG |
1475 | bool | |
62b4d204 | 1476 | depends on FUTEX |
03b8c7b6 HC |
1477 | help |
1478 | Architectures should select this if futex_atomic_cmpxchg_inatomic() | |
1479 | is implemented and always working. This removes a couple of runtime | |
1480 | checks. | |
1481 | ||
1da177e4 | 1482 | config EPOLL |
6a108a14 | 1483 | bool "Enable eventpoll support" if EXPERT |
1da177e4 LT |
1484 | default y |
1485 | help | |
1486 | Disabling this option will cause the kernel to be built without | |
1487 | support for epoll family of system calls. | |
1488 | ||
fba2afaa | 1489 | config SIGNALFD |
6a108a14 | 1490 | bool "Enable signalfd() system call" if EXPERT |
fba2afaa DL |
1491 | default y |
1492 | help | |
1493 | Enable the signalfd() system call that allows to receive signals | |
1494 | on a file descriptor. | |
1495 | ||
1496 | If unsure, say Y. | |
1497 | ||
b215e283 | 1498 | config TIMERFD |
6a108a14 | 1499 | bool "Enable timerfd() system call" if EXPERT |
b215e283 DL |
1500 | default y |
1501 | help | |
1502 | Enable the timerfd() system call that allows to receive timer | |
1503 | events on a file descriptor. | |
1504 | ||
1505 | If unsure, say Y. | |
1506 | ||
e1ad7468 | 1507 | config EVENTFD |
6a108a14 | 1508 | bool "Enable eventfd() system call" if EXPERT |
e1ad7468 DL |
1509 | default y |
1510 | help | |
1511 | Enable the eventfd() system call that allows to receive both | |
1512 | kernel notification (ie. KAIO) or userspace notifications. | |
1513 | ||
1514 | If unsure, say Y. | |
1515 | ||
1da177e4 | 1516 | config SHMEM |
6a108a14 | 1517 | bool "Use full shmem filesystem" if EXPERT |
1da177e4 LT |
1518 | default y |
1519 | depends on MMU | |
1520 | help | |
1521 | The shmem is an internal filesystem used to manage shared memory. | |
1522 | It is backed by swap and manages resource limits. It is also exported | |
1523 | to userspace as tmpfs if TMPFS is enabled. Disabling this | |
1524 | option replaces shmem and tmpfs with the much simpler ramfs code, | |
1525 | which may be appropriate on small systems without swap. | |
1526 | ||
ebf3f09c | 1527 | config AIO |
6a108a14 | 1528 | bool "Enable AIO support" if EXPERT |
ebf3f09c TP |
1529 | default y |
1530 | help | |
1531 | This option enables POSIX asynchronous I/O which may by used | |
657a5209 MF |
1532 | by some high performance threaded applications. Disabling |
1533 | this option saves about 7k. | |
1534 | ||
2b188cc1 JA |
1535 | config IO_URING |
1536 | bool "Enable IO uring support" if EXPERT | |
1537 | select ANON_INODES | |
561fb04a | 1538 | select IO_WQ |
2b188cc1 JA |
1539 | default y |
1540 | help | |
1541 | This option enables support for the io_uring interface, enabling | |
1542 | applications to submit and complete IO through submission and | |
1543 | completion rings that are shared between the kernel and application. | |
1544 | ||
d3ac21ca JT |
1545 | config ADVISE_SYSCALLS |
1546 | bool "Enable madvise/fadvise syscalls" if EXPERT | |
1547 | default y | |
1548 | help | |
1549 | This option enables the madvise and fadvise syscalls, used by | |
1550 | applications to advise the kernel about their future memory or file | |
1551 | usage, improving performance. If building an embedded system where no | |
1552 | applications use these syscalls, you can disable this option to save | |
1553 | space. | |
1554 | ||
5b25b13a MD |
1555 | config MEMBARRIER |
1556 | bool "Enable membarrier() system call" if EXPERT | |
1557 | default y | |
1558 | help | |
1559 | Enable the membarrier() system call that allows issuing memory | |
1560 | barriers across all running threads, which can be used to distribute | |
1561 | the cost of user-space memory barriers asymmetrically by transforming | |
1562 | pairs of memory barriers into pairs consisting of membarrier() and a | |
1563 | compiler barrier. | |
1564 | ||
1565 | If unsure, say Y. | |
1566 | ||
d1b069f5 RD |
1567 | config KALLSYMS |
1568 | bool "Load all symbols for debugging/ksymoops" if EXPERT | |
1569 | default y | |
1570 | help | |
1571 | Say Y here to let the kernel print out symbolic crash information and | |
1572 | symbolic stack backtraces. This increases the size of the kernel | |
1573 | somewhat, as all symbols have to be loaded into the kernel image. | |
1574 | ||
1575 | config KALLSYMS_ALL | |
1576 | bool "Include all symbols in kallsyms" | |
1577 | depends on DEBUG_KERNEL && KALLSYMS | |
1578 | help | |
1579 | Normally kallsyms only contains the symbols of functions for nicer | |
1580 | OOPS messages and backtraces (i.e., symbols from the text and inittext | |
1581 | sections). This is sufficient for most cases. And only in very rare | |
1582 | cases (e.g., when a debugger is used) all symbols are required (e.g., | |
1583 | names of variables from the data sections, etc). | |
1584 | ||
1585 | This option makes sure that all symbols are loaded into the kernel | |
1586 | image (i.e., symbols from all sections) in cost of increased kernel | |
1587 | size (depending on the kernel configuration, it may be 300KiB or | |
1588 | something like this). | |
1589 | ||
1590 | Say N unless you really need all symbols. | |
1591 | ||
1592 | config KALLSYMS_ABSOLUTE_PERCPU | |
1593 | bool | |
1594 | depends on KALLSYMS | |
1595 | default X86_64 && SMP | |
1596 | ||
1597 | config KALLSYMS_BASE_RELATIVE | |
1598 | bool | |
1599 | depends on KALLSYMS | |
a687a533 | 1600 | default !IA64 |
d1b069f5 RD |
1601 | help |
1602 | Instead of emitting them as absolute values in the native word size, | |
1603 | emit the symbol references in the kallsyms table as 32-bit entries, | |
1604 | each containing a relative value in the range [base, base + U32_MAX] | |
1605 | or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either | |
1606 | an absolute value in the range [0, S32_MAX] or a relative value in the | |
1607 | range [base, base + S32_MAX], where base is the lowest relative symbol | |
1608 | address encountered in the image. | |
1609 | ||
1610 | On 64-bit builds, this reduces the size of the address table by 50%, | |
1611 | but more importantly, it results in entries whose values are build | |
1612 | time constants, and no relocation pass is required at runtime to fix | |
1613 | up the entries based on the runtime load address of the kernel. | |
1614 | ||
1615 | # end of the "standard kernel features (expert users)" menu | |
1616 | ||
1617 | # syscall, maps, verifier | |
1618 | config BPF_SYSCALL | |
1619 | bool "Enable bpf() system call" | |
d1b069f5 | 1620 | select BPF |
bae77c5e | 1621 | select IRQ_WORK |
d1b069f5 RD |
1622 | default n |
1623 | help | |
1624 | Enable the bpf() system call that allows to manipulate eBPF | |
1625 | programs and maps via file descriptors. | |
1626 | ||
290af866 AS |
1627 | config BPF_JIT_ALWAYS_ON |
1628 | bool "Permanently enable BPF JIT and remove BPF interpreter" | |
1629 | depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT | |
1630 | help | |
1631 | Enables BPF JIT and removes BPF interpreter to avoid | |
1632 | speculative execution of BPF instructions by the interpreter | |
1633 | ||
d1b069f5 RD |
1634 | config USERFAULTFD |
1635 | bool "Enable userfaultfd() system call" | |
d1b069f5 RD |
1636 | depends on MMU |
1637 | help | |
1638 | Enable the userfaultfd() system call that allows to intercept and | |
1639 | handle page faults in userland. | |
1640 | ||
3ccfebed MD |
1641 | config ARCH_HAS_MEMBARRIER_CALLBACKS |
1642 | bool | |
1643 | ||
70216e18 MD |
1644 | config ARCH_HAS_MEMBARRIER_SYNC_CORE |
1645 | bool | |
1646 | ||
d7822b1e MD |
1647 | config RSEQ |
1648 | bool "Enable rseq() system call" if EXPERT | |
1649 | default y | |
1650 | depends on HAVE_RSEQ | |
1651 | select MEMBARRIER | |
1652 | help | |
1653 | Enable the restartable sequences system call. It provides a | |
1654 | user-space cache for the current CPU number value, which | |
1655 | speeds up getting the current CPU number from user-space, | |
1656 | as well as an ABI to speed up user-space operations on | |
1657 | per-CPU data. | |
1658 | ||
1659 | If unsure, say Y. | |
1660 | ||
1661 | config DEBUG_RSEQ | |
1662 | default n | |
1663 | bool "Enabled debugging of rseq() system call" if EXPERT | |
1664 | depends on RSEQ && DEBUG_KERNEL | |
1665 | help | |
1666 | Enable extra debugging checks for the rseq system call. | |
1667 | ||
1668 | If unsure, say N. | |
1669 | ||
6befe5f6 RD |
1670 | config EMBEDDED |
1671 | bool "Embedded system" | |
5d2acfc7 | 1672 | option allnoconfig_y |
6befe5f6 RD |
1673 | select EXPERT |
1674 | help | |
1675 | This option should be enabled if compiling the kernel for | |
1676 | an embedded system so certain expert options are available | |
1677 | for configuration. | |
1678 | ||
cdd6c482 | 1679 | config HAVE_PERF_EVENTS |
0793a61d | 1680 | bool |
018df72d MF |
1681 | help |
1682 | See tools/perf/design.txt for details. | |
0793a61d | 1683 | |
906010b2 PZ |
1684 | config PERF_USE_VMALLOC |
1685 | bool | |
1686 | help | |
1687 | See tools/perf/design.txt for details | |
1688 | ||
ad90a3de | 1689 | config PC104 |
424529fb | 1690 | bool "PC/104 support" if EXPERT |
ad90a3de WBG |
1691 | help |
1692 | Expose PC/104 form factor device drivers and options available for | |
1693 | selection and configuration. Enable this option if your target | |
1694 | machine has a PC/104 bus. | |
1695 | ||
57c0c15b | 1696 | menu "Kernel Performance Events And Counters" |
0793a61d | 1697 | |
cdd6c482 | 1698 | config PERF_EVENTS |
57c0c15b | 1699 | bool "Kernel performance events and counters" |
392d65a9 | 1700 | default y if PROFILING |
cdd6c482 | 1701 | depends on HAVE_PERF_EVENTS |
e360adbe | 1702 | select IRQ_WORK |
83fe27ea | 1703 | select SRCU |
0793a61d | 1704 | help |
57c0c15b IM |
1705 | Enable kernel support for various performance events provided |
1706 | by software and hardware. | |
0793a61d | 1707 | |
dd77038d | 1708 | Software events are supported either built-in or via the |
57c0c15b | 1709 | use of generic tracepoints. |
0793a61d | 1710 | |
57c0c15b IM |
1711 | Most modern CPUs support performance events via performance |
1712 | counter registers. These registers count the number of certain | |
0793a61d TG |
1713 | types of hw events: such as instructions executed, cachemisses |
1714 | suffered, or branches mis-predicted - without slowing down the | |
1715 | kernel or applications. These registers can also trigger interrupts | |
1716 | when a threshold number of events have passed - and can thus be | |
1717 | used to profile the code that runs on that CPU. | |
1718 | ||
57c0c15b | 1719 | The Linux Performance Event subsystem provides an abstraction of |
dd77038d | 1720 | these software and hardware event capabilities, available via a |
57c0c15b | 1721 | system call and used by the "perf" utility in tools/perf/. It |
0793a61d TG |
1722 | provides per task and per CPU counters, and it provides event |
1723 | capabilities on top of those. | |
1724 | ||
1725 | Say Y if unsure. | |
1726 | ||
906010b2 PZ |
1727 | config DEBUG_PERF_USE_VMALLOC |
1728 | default n | |
1729 | bool "Debug: use vmalloc to back perf mmap() buffers" | |
cb307113 | 1730 | depends on PERF_EVENTS && DEBUG_KERNEL && !PPC |
906010b2 PZ |
1731 | select PERF_USE_VMALLOC |
1732 | help | |
1733 | Use vmalloc memory to back perf mmap() buffers. | |
1734 | ||
1735 | Mostly useful for debugging the vmalloc code on platforms | |
1736 | that don't require it. | |
1737 | ||
1738 | Say N if unsure. | |
1739 | ||
0793a61d TG |
1740 | endmenu |
1741 | ||
f8891e5e CL |
1742 | config VM_EVENT_COUNTERS |
1743 | default y | |
6a108a14 | 1744 | bool "Enable VM event counters for /proc/vmstat" if EXPERT |
f8891e5e | 1745 | help |
2aea4fb6 PJ |
1746 | VM event counters are needed for event counts to be shown. |
1747 | This option allows the disabling of the VM event counters | |
6a108a14 | 1748 | on EXPERT systems. /proc/vmstat will only show page counts |
2aea4fb6 | 1749 | if VM event counters are disabled. |
f8891e5e | 1750 | |
41ecc55b CL |
1751 | config SLUB_DEBUG |
1752 | default y | |
6a108a14 | 1753 | bool "Enable SLUB debugging support" if EXPERT |
f6acb635 | 1754 | depends on SLUB && SYSFS |
41ecc55b CL |
1755 | help |
1756 | SLUB has extensive debug support features. Disabling these can | |
1757 | result in significant savings in code size. This also disables | |
1758 | SLUB sysfs support. /sys/slab will not exist and there will be | |
1759 | no support for cache validation etc. | |
1760 | ||
1663f26d TH |
1761 | config SLUB_MEMCG_SYSFS_ON |
1762 | default n | |
1763 | bool "Enable memcg SLUB sysfs support by default" if EXPERT | |
1764 | depends on SLUB && SYSFS && MEMCG | |
1765 | help | |
1766 | SLUB creates a directory under /sys/kernel/slab for each | |
1767 | allocation cache to host info and debug files. If memory | |
1768 | cgroup is enabled, each cache can have per memory cgroup | |
1769 | caches. SLUB can create the same sysfs directories for these | |
1770 | caches under /sys/kernel/slab/CACHE/cgroup but it can lead | |
1771 | to a very high number of debug files being created. This is | |
1772 | controlled by slub_memcg_sysfs boot parameter and this | |
1773 | config option determines the parameter's default value. | |
1774 | ||
b943c460 RD |
1775 | config COMPAT_BRK |
1776 | bool "Disable heap randomization" | |
1777 | default y | |
1778 | help | |
1779 | Randomizing heap placement makes heap exploits harder, but it | |
1780 | also breaks ancient binaries (including anything libc5 based). | |
1781 | This option changes the bootup default to heap randomization | |
692105b8 | 1782 | disabled, and can be overridden at runtime by setting |
b943c460 RD |
1783 | /proc/sys/kernel/randomize_va_space to 2. |
1784 | ||
1785 | On non-ancient distros (post-2000 ones) N is usually a safe choice. | |
1786 | ||
81819f0f CL |
1787 | choice |
1788 | prompt "Choose SLAB allocator" | |
a0acd820 | 1789 | default SLUB |
81819f0f CL |
1790 | help |
1791 | This option allows to select a slab allocator. | |
1792 | ||
1793 | config SLAB | |
1794 | bool "SLAB" | |
04385fc5 | 1795 | select HAVE_HARDENED_USERCOPY_ALLOCATOR |
81819f0f CL |
1796 | help |
1797 | The regular slab allocator that is established and known to work | |
34013886 | 1798 | well in all environments. It organizes cache hot objects in |
02f56210 | 1799 | per cpu and per node queues. |
81819f0f CL |
1800 | |
1801 | config SLUB | |
81819f0f | 1802 | bool "SLUB (Unqueued Allocator)" |
ed18adc1 | 1803 | select HAVE_HARDENED_USERCOPY_ALLOCATOR |
81819f0f CL |
1804 | help |
1805 | SLUB is a slab allocator that minimizes cache line usage | |
1806 | instead of managing queues of cached objects (SLAB approach). | |
1807 | Per cpu caching is realized using slabs of objects instead | |
1808 | of queues of objects. SLUB can use memory efficiently | |
02f56210 SA |
1809 | and has enhanced diagnostics. SLUB is the default choice for |
1810 | a slab allocator. | |
81819f0f CL |
1811 | |
1812 | config SLOB | |
6a108a14 | 1813 | depends on EXPERT |
81819f0f CL |
1814 | bool "SLOB (Simple Allocator)" |
1815 | help | |
37291458 MM |
1816 | SLOB replaces the stock allocator with a drastically simpler |
1817 | allocator. SLOB is generally more space efficient but | |
1818 | does not perform as well on large systems. | |
81819f0f CL |
1819 | |
1820 | endchoice | |
1821 | ||
7660a6fd KC |
1822 | config SLAB_MERGE_DEFAULT |
1823 | bool "Allow slab caches to be merged" | |
1824 | default y | |
1825 | help | |
1826 | For reduced kernel memory fragmentation, slab caches can be | |
1827 | merged when they share the same size and other characteristics. | |
1828 | This carries a risk of kernel heap overflows being able to | |
1829 | overwrite objects from merged caches (and more easily control | |
1830 | cache layout), which makes such heap attacks easier to exploit | |
1831 | by attackers. By keeping caches unmerged, these kinds of exploits | |
1832 | can usually only damage objects in the same cache. To disable | |
1833 | merging at runtime, "slab_nomerge" can be passed on the kernel | |
1834 | command line. | |
1835 | ||
c7ce4f60 TG |
1836 | config SLAB_FREELIST_RANDOM |
1837 | default n | |
210e7a43 | 1838 | depends on SLAB || SLUB |
c7ce4f60 TG |
1839 | bool "SLAB freelist randomization" |
1840 | help | |
210e7a43 | 1841 | Randomizes the freelist order used on creating new pages. This |
c7ce4f60 TG |
1842 | security feature reduces the predictability of the kernel slab |
1843 | allocator against heap overflows. | |
1844 | ||
2482ddec KC |
1845 | config SLAB_FREELIST_HARDENED |
1846 | bool "Harden slab freelist metadata" | |
1847 | depends on SLUB | |
1848 | help | |
1849 | Many kernel heap attacks try to target slab cache metadata and | |
1850 | other infrastructure. This options makes minor performance | |
92bae787 | 1851 | sacrifices to harden the kernel slab allocator against common |
2482ddec KC |
1852 | freelist exploit methods. |
1853 | ||
e900a918 DW |
1854 | config SHUFFLE_PAGE_ALLOCATOR |
1855 | bool "Page allocator randomization" | |
1856 | default SLAB_FREELIST_RANDOM && ACPI_NUMA | |
1857 | help | |
1858 | Randomization of the page allocator improves the average | |
1859 | utilization of a direct-mapped memory-side-cache. See section | |
1860 | 5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI | |
1861 | 6.2a specification for an example of how a platform advertises | |
1862 | the presence of a memory-side-cache. There are also incidental | |
1863 | security benefits as it reduces the predictability of page | |
1864 | allocations to compliment SLAB_FREELIST_RANDOM, but the | |
1865 | default granularity of shuffling on the "MAX_ORDER - 1" i.e, | |
1866 | 10th order of pages is selected based on cache utilization | |
1867 | benefits on x86. | |
1868 | ||
1869 | While the randomization improves cache utilization it may | |
1870 | negatively impact workloads on platforms without a cache. For | |
1871 | this reason, by default, the randomization is enabled only | |
1872 | after runtime detection of a direct-mapped memory-side-cache. | |
1873 | Otherwise, the randomization may be force enabled with the | |
1874 | 'page_alloc.shuffle' kernel command line parameter. | |
1875 | ||
1876 | Say Y if unsure. | |
1877 | ||
345c905d JK |
1878 | config SLUB_CPU_PARTIAL |
1879 | default y | |
b39ffbf8 | 1880 | depends on SLUB && SMP |
345c905d JK |
1881 | bool "SLUB per cpu partial cache" |
1882 | help | |
92bae787 | 1883 | Per cpu partial caches accelerate objects allocation and freeing |
345c905d JK |
1884 | that is local to a processor at the price of more indeterminism |
1885 | in the latency of the free. On overflow these caches will be cleared | |
1886 | which requires the taking of locks that may cause latency spikes. | |
1887 | Typically one would choose no for a realtime system. | |
1888 | ||
ea637639 JZ |
1889 | config MMAP_ALLOW_UNINITIALIZED |
1890 | bool "Allow mmapped anonymous memory to be uninitialized" | |
6a108a14 | 1891 | depends on EXPERT && !MMU |
ea637639 JZ |
1892 | default n |
1893 | help | |
1894 | Normally, and according to the Linux spec, anonymous memory obtained | |
3903bf94 | 1895 | from mmap() has its contents cleared before it is passed to |
ea637639 JZ |
1896 | userspace. Enabling this config option allows you to request that |
1897 | mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus | |
1898 | providing a huge performance boost. If this option is not enabled, | |
1899 | then the flag will be ignored. | |
1900 | ||
1901 | This is taken advantage of by uClibc's malloc(), and also by | |
1902 | ELF-FDPIC binfmt's brk and stack allocator. | |
1903 | ||
1904 | Because of the obvious security issues, this option should only be | |
1905 | enabled on embedded devices where you control what is run in | |
1906 | userspace. Since that isn't generally a problem on no-MMU systems, | |
1907 | it is normally safe to say Y here. | |
1908 | ||
1909 | See Documentation/nommu-mmap.txt for more information. | |
1910 | ||
091f6e26 DH |
1911 | config SYSTEM_DATA_VERIFICATION |
1912 | def_bool n | |
1913 | select SYSTEM_TRUSTED_KEYRING | |
1914 | select KEYS | |
1915 | select CRYPTO | |
d43de6c7 | 1916 | select CRYPTO_RSA |
091f6e26 DH |
1917 | select ASYMMETRIC_KEY_TYPE |
1918 | select ASYMMETRIC_PUBLIC_KEY_SUBTYPE | |
091f6e26 DH |
1919 | select ASN1 |
1920 | select OID_REGISTRY | |
1921 | select X509_CERTIFICATE_PARSER | |
1922 | select PKCS7_MESSAGE_PARSER | |
82c04ff8 | 1923 | help |
091f6e26 DH |
1924 | Provide PKCS#7 message verification using the contents of the system |
1925 | trusted keyring to provide public keys. This then can be used for | |
1926 | module verification, kexec image verification and firmware blob | |
1927 | verification. | |
82c04ff8 | 1928 | |
125e5645 | 1929 | config PROFILING |
b309a294 | 1930 | bool "Profiling support" |
125e5645 MD |
1931 | help |
1932 | Say Y here to enable the extended profiling support mechanisms used | |
1933 | by profilers such as OProfile. | |
1934 | ||
5f87f112 IM |
1935 | # |
1936 | # Place an empty function call at each tracepoint site. Can be | |
1937 | # dynamically changed for a probe function. | |
1938 | # | |
97e1c18e | 1939 | config TRACEPOINTS |
5f87f112 | 1940 | bool |
97e1c18e | 1941 | |
1da177e4 LT |
1942 | endmenu # General setup |
1943 | ||
1572497c CH |
1944 | source "arch/Kconfig" |
1945 | ||
ae81f9e3 | 1946 | config RT_MUTEXES |
6341e62b | 1947 | bool |
ae81f9e3 | 1948 | |
1da177e4 LT |
1949 | config BASE_SMALL |
1950 | int | |
1951 | default 0 if BASE_FULL | |
1952 | default 1 if !BASE_FULL | |
1953 | ||
c8424e77 TJB |
1954 | config MODULE_SIG_FORMAT |
1955 | def_bool n | |
1956 | select SYSTEM_DATA_VERIFICATION | |
1957 | ||
66da5733 | 1958 | menuconfig MODULES |
1da177e4 | 1959 | bool "Enable loadable module support" |
11097a03 | 1960 | option modules |
1da177e4 LT |
1961 | help |
1962 | Kernel modules are small pieces of compiled code which can | |
1963 | be inserted in the running kernel, rather than being | |
1964 | permanently built into the kernel. You use the "modprobe" | |
1965 | tool to add (and sometimes remove) them. If you say Y here, | |
1966 | many parts of the kernel can be built as modules (by | |
1967 | answering M instead of Y where indicated): this is most | |
1968 | useful for infrequently used options which are not required | |
1969 | for booting. For more information, see the man pages for | |
1970 | modprobe, lsmod, modinfo, insmod and rmmod. | |
1971 | ||
1972 | If you say Y here, you will need to run "make | |
1973 | modules_install" to put the modules under /lib/modules/ | |
1974 | where modprobe can find them (you may need to be root to do | |
1975 | this). | |
1976 | ||
1977 | If unsure, say Y. | |
1978 | ||
0b0de144 RD |
1979 | if MODULES |
1980 | ||
826e4506 LT |
1981 | config MODULE_FORCE_LOAD |
1982 | bool "Forced module loading" | |
826e4506 LT |
1983 | default n |
1984 | help | |
91e37a79 RR |
1985 | Allow loading of modules without version information (ie. modprobe |
1986 | --force). Forced module loading sets the 'F' (forced) taint flag and | |
1987 | is usually a really bad idea. | |
826e4506 | 1988 | |
1da177e4 LT |
1989 | config MODULE_UNLOAD |
1990 | bool "Module unloading" | |
1da177e4 LT |
1991 | help |
1992 | Without this option you will not be able to unload any | |
1993 | modules (note that some modules may not be unloadable | |
f7f5b675 DV |
1994 | anyway), which makes your kernel smaller, faster |
1995 | and simpler. If unsure, say Y. | |
1da177e4 LT |
1996 | |
1997 | config MODULE_FORCE_UNLOAD | |
1998 | bool "Forced module unloading" | |
19c92399 | 1999 | depends on MODULE_UNLOAD |
1da177e4 LT |
2000 | help |
2001 | This option allows you to force a module to unload, even if the | |
2002 | kernel believes it is unsafe: the kernel will remove the module | |
2003 | without waiting for anyone to stop using it (using the -f option to | |
2004 | rmmod). This is mainly for kernel developers and desperate users. | |
2005 | If unsure, say N. | |
2006 | ||
1da177e4 | 2007 | config MODVERSIONS |
0d541643 | 2008 | bool "Module versioning support" |
1da177e4 LT |
2009 | help |
2010 | Usually, you have to use modules compiled with your kernel. | |
2011 | Saying Y here makes it sometimes possible to use modules | |
2012 | compiled for different kernels, by adding enough information | |
2013 | to the modules to (hopefully) spot any changes which would | |
2014 | make them incompatible with the kernel you are running. If | |
2015 | unsure, say N. | |
2016 | ||
2ff2b7ec MY |
2017 | config ASM_MODVERSIONS |
2018 | bool | |
2019 | default HAVE_ASM_MODVERSIONS && MODVERSIONS | |
2020 | help | |
2021 | This enables module versioning for exported symbols also from | |
2022 | assembly. This can be enabled only when the target architecture | |
2023 | supports it. | |
2024 | ||
56067812 AB |
2025 | config MODULE_REL_CRCS |
2026 | bool | |
2027 | depends on MODVERSIONS | |
2028 | ||
1da177e4 LT |
2029 | config MODULE_SRCVERSION_ALL |
2030 | bool "Source checksum for all modules" | |
1da177e4 LT |
2031 | help |
2032 | Modules which contain a MODULE_VERSION get an extra "srcversion" | |
2033 | field inserted into their modinfo section, which contains a | |
2034 | sum of the source files which made it. This helps maintainers | |
2035 | see exactly which source was used to build a module (since | |
2036 | others sometimes change the module source without updating | |
2037 | the version). With this option, such a "srcversion" field | |
2038 | will be created for all modules. If unsure, say N. | |
2039 | ||
106a4ee2 RR |
2040 | config MODULE_SIG |
2041 | bool "Module signature verification" | |
c8424e77 | 2042 | select MODULE_SIG_FORMAT |
106a4ee2 RR |
2043 | help |
2044 | Check modules for valid signatures upon load: the signature | |
2045 | is simply appended to the module. For more information see | |
cbdc8217 | 2046 | <file:Documentation/admin-guide/module-signing.rst>. |
106a4ee2 | 2047 | |
228c37ff DH |
2048 | Note that this option adds the OpenSSL development packages as a |
2049 | kernel build dependency so that the signing tool can use its crypto | |
2050 | library. | |
2051 | ||
49fcf732 DH |
2052 | You should enable this option if you wish to use either |
2053 | CONFIG_SECURITY_LOCKDOWN_LSM or lockdown functionality imposed via | |
2054 | another LSM - otherwise unsigned modules will be loadable regardless | |
2055 | of the lockdown policy. | |
2056 | ||
ea0b6dcf DH |
2057 | !!!WARNING!!! If you enable this option, you MUST make sure that the |
2058 | module DOES NOT get stripped after being signed. This includes the | |
2059 | debuginfo strip done by some packagers (such as rpmbuild) and | |
2060 | inclusion into an initramfs that wants the module size reduced. | |
2061 | ||
106a4ee2 RR |
2062 | config MODULE_SIG_FORCE |
2063 | bool "Require modules to be validly signed" | |
2064 | depends on MODULE_SIG | |
2065 | help | |
2066 | Reject unsigned modules or signed modules for which we don't have a | |
2067 | key. Without this, such modules will simply taint the kernel. | |
ea0b6dcf | 2068 | |
d9d8d7ed MM |
2069 | config MODULE_SIG_ALL |
2070 | bool "Automatically sign all modules" | |
2071 | default y | |
2072 | depends on MODULE_SIG | |
2073 | help | |
2074 | Sign all modules during make modules_install. Without this option, | |
2075 | modules must be signed manually, using the scripts/sign-file tool. | |
2076 | ||
2077 | comment "Do not forget to sign required modules with scripts/sign-file" | |
2078 | depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL | |
2079 | ||
ea0b6dcf DH |
2080 | choice |
2081 | prompt "Which hash algorithm should modules be signed with?" | |
2082 | depends on MODULE_SIG | |
2083 | help | |
2084 | This determines which sort of hashing algorithm will be used during | |
2085 | signature generation. This algorithm _must_ be built into the kernel | |
2086 | directly so that signature verification can take place. It is not | |
2087 | possible to load a signed module containing the algorithm to check | |
2088 | the signature on that module. | |
2089 | ||
2090 | config MODULE_SIG_SHA1 | |
2091 | bool "Sign modules with SHA-1" | |
2092 | select CRYPTO_SHA1 | |
2093 | ||
2094 | config MODULE_SIG_SHA224 | |
2095 | bool "Sign modules with SHA-224" | |
2096 | select CRYPTO_SHA256 | |
2097 | ||
2098 | config MODULE_SIG_SHA256 | |
2099 | bool "Sign modules with SHA-256" | |
2100 | select CRYPTO_SHA256 | |
2101 | ||
2102 | config MODULE_SIG_SHA384 | |
2103 | bool "Sign modules with SHA-384" | |
2104 | select CRYPTO_SHA512 | |
2105 | ||
2106 | config MODULE_SIG_SHA512 | |
2107 | bool "Sign modules with SHA-512" | |
2108 | select CRYPTO_SHA512 | |
2109 | ||
2110 | endchoice | |
2111 | ||
22753674 MM |
2112 | config MODULE_SIG_HASH |
2113 | string | |
2114 | depends on MODULE_SIG | |
2115 | default "sha1" if MODULE_SIG_SHA1 | |
2116 | default "sha224" if MODULE_SIG_SHA224 | |
2117 | default "sha256" if MODULE_SIG_SHA256 | |
2118 | default "sha384" if MODULE_SIG_SHA384 | |
2119 | default "sha512" if MODULE_SIG_SHA512 | |
2120 | ||
beb50df3 BJ |
2121 | config MODULE_COMPRESS |
2122 | bool "Compress modules on installation" | |
beb50df3 | 2123 | help |
beb50df3 | 2124 | |
b6c09b51 RR |
2125 | Compresses kernel modules when 'make modules_install' is run; gzip or |
2126 | xz depending on "Compression algorithm" below. | |
beb50df3 | 2127 | |
b6c09b51 | 2128 | module-init-tools MAY support gzip, and kmod MAY support gzip and xz. |
beb50df3 | 2129 | |
b6c09b51 RR |
2130 | Out-of-tree kernel modules installed using Kbuild will also be |
2131 | compressed upon installation. | |
beb50df3 | 2132 | |
b6c09b51 RR |
2133 | Note: for modules inside an initrd or initramfs, it's more efficient |
2134 | to compress the whole initrd or initramfs instead. | |
beb50df3 | 2135 | |
b6c09b51 RR |
2136 | Note: This is fully compatible with signed modules. |
2137 | ||
2138 | If in doubt, say N. | |
beb50df3 BJ |
2139 | |
2140 | choice | |
2141 | prompt "Compression algorithm" | |
2142 | depends on MODULE_COMPRESS | |
2143 | default MODULE_COMPRESS_GZIP | |
2144 | help | |
2145 | This determines which sort of compression will be used during | |
2146 | 'make modules_install'. | |
2147 | ||
2148 | GZIP (default) and XZ are supported. | |
2149 | ||
2150 | config MODULE_COMPRESS_GZIP | |
2151 | bool "GZIP" | |
2152 | ||
2153 | config MODULE_COMPRESS_XZ | |
2154 | bool "XZ" | |
2155 | ||
2156 | endchoice | |
2157 | ||
3d52ec5e MM |
2158 | config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS |
2159 | bool "Allow loading of modules with missing namespace imports" | |
2160 | help | |
2161 | Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in | |
2162 | a namespace. A module that makes use of a symbol exported with such a | |
2163 | namespace is required to import the namespace via MODULE_IMPORT_NS(). | |
2164 | There is no technical reason to enforce correct namespace imports, | |
2165 | but it creates consistency between symbols defining namespaces and | |
2166 | users importing namespaces they make use of. This option relaxes this | |
2167 | requirement and lifts the enforcement when loading a module. | |
2168 | ||
2169 | If unsure, say N. | |
2170 | ||
efd9763d MY |
2171 | config UNUSED_SYMBOLS |
2172 | bool "Enable unused/obsolete exported symbols" | |
2173 | default y if X86 | |
2174 | help | |
2175 | Unused but exported symbols make the kernel needlessly bigger. For | |
2176 | that reason most of these unused exports will soon be removed. This | |
2177 | option is provided temporarily to provide a transition period in case | |
2178 | some external kernel module needs one of these symbols anyway. If you | |
2179 | encounter such a case in your module, consider if you are actually | |
2180 | using the right API. (rationale: since nobody in the kernel is using | |
2181 | this in a module, there is a pretty good chance it's actually the | |
2182 | wrong interface to use). If you really need the symbol, please send a | |
2183 | mail to the linux kernel mailing list mentioning the symbol and why | |
2184 | you really need it, and what the merge plan to the mainline kernel for | |
2185 | your module is. | |
2186 | ||
dbacb0ef NP |
2187 | config TRIM_UNUSED_KSYMS |
2188 | bool "Trim unused exported kernel symbols" | |
d189c2a4 | 2189 | depends on !UNUSED_SYMBOLS |
dbacb0ef NP |
2190 | help |
2191 | The kernel and some modules make many symbols available for | |
2192 | other modules to use via EXPORT_SYMBOL() and variants. Depending | |
2193 | on the set of modules being selected in your kernel configuration, | |
2194 | many of those exported symbols might never be used. | |
2195 | ||
2196 | This option allows for unused exported symbols to be dropped from | |
2197 | the build. In turn, this provides the compiler more opportunities | |
2198 | (especially when using LTO) for optimizing the code and reducing | |
2199 | binary size. This might have some security advantages as well. | |
2200 | ||
f1cb637e | 2201 | If unsure, or if you need to build out-of-tree modules, say N. |
dbacb0ef | 2202 | |
0b0de144 RD |
2203 | endif # MODULES |
2204 | ||
6c9692e2 PZ |
2205 | config MODULES_TREE_LOOKUP |
2206 | def_bool y | |
2207 | depends on PERF_EVENTS || TRACING | |
2208 | ||
98a79d6a RR |
2209 | config INIT_ALL_POSSIBLE |
2210 | bool | |
2211 | help | |
5f054e31 RR |
2212 | Back when each arch used to define their own cpu_online_mask and |
2213 | cpu_possible_mask, some of them chose to initialize cpu_possible_mask | |
98a79d6a RR |
2214 | with all 1s, and others with all 0s. When they were centralised, |
2215 | it was better to provide this option than to break all the archs | |
692105b8 | 2216 | and have several arch maintainers pursuing me down dark alleys. |
98a79d6a | 2217 | |
3a65dfe8 | 2218 | source "block/Kconfig" |
e98c3202 AK |
2219 | |
2220 | config PREEMPT_NOTIFIERS | |
2221 | bool | |
e260be67 | 2222 | |
16295bec SK |
2223 | config PADATA |
2224 | depends on SMP | |
2225 | bool | |
2226 | ||
4520c6a4 DH |
2227 | config ASN1 |
2228 | tristate | |
2229 | help | |
2230 | Build a simple ASN.1 grammar compiler that produces a bytecode output | |
2231 | that can be interpreted by the ASN.1 stream decoder and used to | |
2232 | inform it as to what tags are to be expected in a stream and what | |
2233 | functions to call on what tags. | |
2234 | ||
6beb0009 | 2235 | source "kernel/Kconfig.locks" |
e61938a9 MD |
2236 | |
2237 | config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE | |
2238 | bool | |
1bd21c6c DB |
2239 | |
2240 | # It may be useful for an architecture to override the definitions of the | |
7303e30e DB |
2241 | # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h> |
2242 | # and the COMPAT_ variants in <linux/compat.h>, in particular to use a | |
2243 | # different calling convention for syscalls. They can also override the | |
2244 | # macros for not-implemented syscalls in kernel/sys_ni.c and | |
2245 | # kernel/time/posix-stubs.c. All these overrides need to be available in | |
2246 | # <asm/syscall_wrapper.h>. | |
1bd21c6c DB |
2247 | config ARCH_HAS_SYSCALL_WRAPPER |
2248 | def_bool n |