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ec8f24b7 | 1 | # SPDX-License-Identifier: GPL-2.0-only |
face4374 RZ |
2 | config DEFCONFIG_LIST |
3 | string | |
b2670eac | 4 | depends on !UML |
face4374 | 5 | option defconfig_list |
47f38ae0 | 6 | default "/lib/modules/$(shell,uname -r)/.config" |
face4374 | 7 | default "/etc/kernel-config" |
47f38ae0 | 8 | default "/boot/config-$(shell,uname -r)" |
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 | |
b303c6df MY |
36 | config CC_HAS_WARN_MAYBE_UNINITIALIZED |
37 | def_bool $(cc-option,-Wmaybe-uninitialized) | |
38 | help | |
39 | GCC >= 4.7 supports this option. | |
40 | ||
41 | config CC_DISABLE_WARN_MAYBE_UNINITIALIZED | |
42 | bool | |
43 | depends on CC_HAS_WARN_MAYBE_UNINITIALIZED | |
44 | default CC_IS_GCC && GCC_VERSION < 40900 # unreliable for GCC < 4.9 | |
45 | help | |
46 | GCC's -Wmaybe-uninitialized is not reliable by definition. | |
47 | Lots of false positive warnings are produced in some cases. | |
48 | ||
49 | If this option is enabled, -Wno-maybe-uninitialzed is passed | |
50 | to the compiler to suppress maybe-uninitialized warnings. | |
51 | ||
b99b87f7 PO |
52 | config CONSTRUCTORS |
53 | bool | |
54 | depends on !UML | |
b99b87f7 | 55 | |
e360adbe PZ |
56 | config IRQ_WORK |
57 | bool | |
e360adbe | 58 | |
1dbdc6f1 DD |
59 | config BUILDTIME_EXTABLE_SORT |
60 | bool | |
61 | ||
c65eacbe AL |
62 | config THREAD_INFO_IN_TASK |
63 | bool | |
64 | help | |
65 | Select this to move thread_info off the stack into task_struct. To | |
66 | make this work, an arch will need to remove all thread_info fields | |
67 | except flags and fix any runtime bugs. | |
68 | ||
c6c314a6 AL |
69 | One subtle change that will be needed is to use try_get_task_stack() |
70 | and put_task_stack() in save_thread_stack_tsk() and get_wchan(). | |
71 | ||
ff0cfc66 | 72 | menu "General setup" |
1da177e4 | 73 | |
1da177e4 LT |
74 | config BROKEN |
75 | bool | |
1da177e4 LT |
76 | |
77 | config BROKEN_ON_SMP | |
78 | bool | |
79 | depends on BROKEN || !SMP | |
80 | default y | |
81 | ||
1da177e4 LT |
82 | config INIT_ENV_ARG_LIMIT |
83 | int | |
dd673bca AB |
84 | default 32 if !UML |
85 | default 128 if UML | |
1da177e4 | 86 | help |
34ad92c2 RD |
87 | Maximum of each of the number of arguments and environment |
88 | variables passed to init from the kernel command line. | |
1da177e4 | 89 | |
4bb16672 JS |
90 | config COMPILE_TEST |
91 | bool "Compile also drivers which will not load" | |
bc083a64 | 92 | depends on !UML |
4bb16672 JS |
93 | default n |
94 | help | |
95 | Some drivers can be compiled on a different platform than they are | |
96 | intended to be run on. Despite they cannot be loaded there (or even | |
97 | when they load they cannot be used due to missing HW support), | |
98 | developers still, opposing to distributors, might want to build such | |
99 | drivers to compile-test them. | |
100 | ||
101 | If you are a developer and want to build everything available, say Y | |
102 | here. If you are a user/distributor, say N here to exclude useless | |
103 | drivers to be distributed. | |
104 | ||
e846f0dc JN |
105 | config HEADER_TEST |
106 | bool "Compile test headers that should be standalone compilable" | |
107 | help | |
108 | Compile test headers listed in header-test-y target to ensure they are | |
109 | self-contained, i.e. compilable as standalone units. | |
110 | ||
111 | If you are a developer or tester and want to ensure the requested | |
112 | headers are self-contained, say Y here. Otherwise, choose N. | |
113 | ||
43c78d88 MY |
114 | config KERNEL_HEADER_TEST |
115 | bool "Compile test kernel headers" | |
116 | depends on HEADER_TEST | |
117 | help | |
118 | Headers in include/ are used to build external moduls. | |
119 | Compile test them to ensure they are self-contained, i.e. | |
120 | compilable as standalone units. | |
121 | ||
122 | If you are a developer or tester and want to ensure the headers | |
123 | in include/ are self-contained, say Y here. Otherwise, choose N. | |
124 | ||
d6fc9fcb MY |
125 | config UAPI_HEADER_TEST |
126 | bool "Compile test UAPI headers" | |
127 | depends on HEADER_TEST && HEADERS_INSTALL && CC_CAN_LINK | |
128 | help | |
129 | Compile test headers exported to user-space to ensure they are | |
130 | self-contained, i.e. compilable as standalone units. | |
131 | ||
132 | If you are a developer or tester and want to ensure the exported | |
133 | headers are self-contained, say Y here. Otherwise, choose N. | |
134 | ||
1da177e4 LT |
135 | config LOCALVERSION |
136 | string "Local version - append to kernel release" | |
137 | help | |
138 | Append an extra string to the end of your kernel version. | |
139 | This will show up when you type uname, for example. | |
140 | The string you set here will be appended after the contents of | |
141 | any files with a filename matching localversion* in your | |
142 | object and source tree, in that order. Your total string can | |
143 | be a maximum of 64 characters. | |
144 | ||
aaebf433 RA |
145 | config LOCALVERSION_AUTO |
146 | bool "Automatically append version information to the version string" | |
147 | default y | |
ac3339ba | 148 | depends on !COMPILE_TEST |
aaebf433 RA |
149 | help |
150 | This will try to automatically determine if the current tree is a | |
6e5a5420 RD |
151 | release tree by looking for git tags that belong to the current |
152 | top of tree revision. | |
aaebf433 RA |
153 | |
154 | A string of the format -gxxxxxxxx will be added to the localversion | |
6e5a5420 | 155 | if a git-based tree is found. The string generated by this will be |
aaebf433 | 156 | appended after any matching localversion* files, and after the value |
6e5a5420 | 157 | set in CONFIG_LOCALVERSION. |
aaebf433 | 158 | |
6e5a5420 RD |
159 | (The actual string used here is the first eight characters produced |
160 | by running the command: | |
161 | ||
162 | $ git rev-parse --verify HEAD | |
163 | ||
164 | which is done within the script "scripts/setlocalversion".) | |
aaebf433 | 165 | |
9afb719e LA |
166 | config BUILD_SALT |
167 | string "Build ID Salt" | |
168 | default "" | |
169 | help | |
170 | The build ID is used to link binaries and their debug info. Setting | |
171 | this option will use the value in the calculation of the build id. | |
172 | This is mostly useful for distributions which want to ensure the | |
173 | build is unique between builds. It's safe to leave the default. | |
174 | ||
2e9f3bdd PA |
175 | config HAVE_KERNEL_GZIP |
176 | bool | |
177 | ||
178 | config HAVE_KERNEL_BZIP2 | |
179 | bool | |
180 | ||
181 | config HAVE_KERNEL_LZMA | |
182 | bool | |
183 | ||
3ebe1243 LC |
184 | config HAVE_KERNEL_XZ |
185 | bool | |
186 | ||
7dd65feb AT |
187 | config HAVE_KERNEL_LZO |
188 | bool | |
189 | ||
e76e1fdf KL |
190 | config HAVE_KERNEL_LZ4 |
191 | bool | |
192 | ||
f16466af VG |
193 | config HAVE_KERNEL_UNCOMPRESSED |
194 | bool | |
195 | ||
30d65dbf | 196 | choice |
2e9f3bdd PA |
197 | prompt "Kernel compression mode" |
198 | default KERNEL_GZIP | |
f16466af | 199 | depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 || HAVE_KERNEL_UNCOMPRESSED |
2e9f3bdd | 200 | help |
30d65dbf AK |
201 | The linux kernel is a kind of self-extracting executable. |
202 | Several compression algorithms are available, which differ | |
203 | in efficiency, compression and decompression speed. | |
204 | Compression speed is only relevant when building a kernel. | |
205 | Decompression speed is relevant at each boot. | |
206 | ||
207 | If you have any problems with bzip2 or lzma compressed | |
208 | kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older | |
209 | version of this functionality (bzip2 only), for 2.4, was | |
210 | supplied by Christian Ludwig) | |
211 | ||
212 | High compression options are mostly useful for users, who | |
213 | are low on disk space (embedded systems), but for whom ram | |
214 | size matters less. | |
215 | ||
216 | If in doubt, select 'gzip' | |
217 | ||
218 | config KERNEL_GZIP | |
2e9f3bdd PA |
219 | bool "Gzip" |
220 | depends on HAVE_KERNEL_GZIP | |
221 | help | |
7dd65feb AT |
222 | The old and tried gzip compression. It provides a good balance |
223 | between compression ratio and decompression speed. | |
30d65dbf AK |
224 | |
225 | config KERNEL_BZIP2 | |
226 | bool "Bzip2" | |
2e9f3bdd | 227 | depends on HAVE_KERNEL_BZIP2 |
30d65dbf AK |
228 | help |
229 | Its compression ratio and speed is intermediate. | |
0a4dd35c | 230 | Decompression speed is slowest among the choices. The kernel |
2e9f3bdd PA |
231 | size is about 10% smaller with bzip2, in comparison to gzip. |
232 | Bzip2 uses a large amount of memory. For modern kernels you | |
233 | will need at least 8MB RAM or more for booting. | |
30d65dbf AK |
234 | |
235 | config KERNEL_LZMA | |
2e9f3bdd PA |
236 | bool "LZMA" |
237 | depends on HAVE_KERNEL_LZMA | |
238 | help | |
0a4dd35c RD |
239 | This compression algorithm's ratio is best. Decompression speed |
240 | is between gzip and bzip2. Compression is slowest. | |
241 | The kernel size is about 33% smaller with LZMA in comparison to gzip. | |
30d65dbf | 242 | |
3ebe1243 LC |
243 | config KERNEL_XZ |
244 | bool "XZ" | |
245 | depends on HAVE_KERNEL_XZ | |
246 | help | |
247 | XZ uses the LZMA2 algorithm and instruction set specific | |
248 | BCJ filters which can improve compression ratio of executable | |
249 | code. The size of the kernel is about 30% smaller with XZ in | |
250 | comparison to gzip. On architectures for which there is a BCJ | |
251 | filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ | |
252 | will create a few percent smaller kernel than plain LZMA. | |
253 | ||
254 | The speed is about the same as with LZMA: The decompression | |
255 | speed of XZ is better than that of bzip2 but worse than gzip | |
256 | and LZO. Compression is slow. | |
257 | ||
7dd65feb AT |
258 | config KERNEL_LZO |
259 | bool "LZO" | |
260 | depends on HAVE_KERNEL_LZO | |
261 | help | |
0a4dd35c | 262 | Its compression ratio is the poorest among the choices. The kernel |
681b3049 | 263 | size is about 10% bigger than gzip; however its speed |
7dd65feb AT |
264 | (both compression and decompression) is the fastest. |
265 | ||
e76e1fdf KL |
266 | config KERNEL_LZ4 |
267 | bool "LZ4" | |
268 | depends on HAVE_KERNEL_LZ4 | |
269 | help | |
270 | LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding. | |
271 | A preliminary version of LZ4 de/compression tool is available at | |
272 | <https://code.google.com/p/lz4/>. | |
273 | ||
274 | Its compression ratio is worse than LZO. The size of the kernel | |
275 | is about 8% bigger than LZO. But the decompression speed is | |
276 | faster than LZO. | |
277 | ||
f16466af VG |
278 | config KERNEL_UNCOMPRESSED |
279 | bool "None" | |
280 | depends on HAVE_KERNEL_UNCOMPRESSED | |
281 | help | |
282 | Produce uncompressed kernel image. This option is usually not what | |
283 | you want. It is useful for debugging the kernel in slow simulation | |
284 | environments, where decompressing and moving the kernel is awfully | |
285 | slow. This option allows early boot code to skip the decompressor | |
286 | and jump right at uncompressed kernel image. | |
287 | ||
30d65dbf AK |
288 | endchoice |
289 | ||
bd5dc17b JT |
290 | config DEFAULT_HOSTNAME |
291 | string "Default hostname" | |
292 | default "(none)" | |
293 | help | |
294 | This option determines the default system hostname before userspace | |
295 | calls sethostname(2). The kernel traditionally uses "(none)" here, | |
296 | but you may wish to use a different default here to make a minimal | |
297 | system more usable with less configuration. | |
298 | ||
17c46a6a CH |
299 | # |
300 | # For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can | |
301 | # add proper SWAP support to them, in which case this can be remove. | |
302 | # | |
303 | config ARCH_NO_SWAP | |
304 | bool | |
305 | ||
1da177e4 LT |
306 | config SWAP |
307 | bool "Support for paging of anonymous memory (swap)" | |
17c46a6a | 308 | depends on MMU && BLOCK && !ARCH_NO_SWAP |
1da177e4 LT |
309 | default y |
310 | help | |
311 | This option allows you to choose whether you want to have support | |
92c3504e | 312 | for so called swap devices or swap files in your kernel that are |
1da177e4 LT |
313 | used to provide more virtual memory than the actual RAM present |
314 | in your computer. If unsure say Y. | |
315 | ||
316 | config SYSVIPC | |
317 | bool "System V IPC" | |
1da177e4 LT |
318 | ---help--- |
319 | Inter Process Communication is a suite of library functions and | |
320 | system calls which let processes (running programs) synchronize and | |
321 | exchange information. It is generally considered to be a good thing, | |
322 | and some programs won't run unless you say Y here. In particular, if | |
323 | you want to run the DOS emulator dosemu under Linux (read the | |
324 | DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), | |
325 | you'll need to say Y here. | |
326 | ||
327 | You can find documentation about IPC with "info ipc" and also in | |
328 | section 6.4 of the Linux Programmer's Guide, available from | |
329 | <http://www.tldp.org/guides.html>. | |
330 | ||
a5494dcd EB |
331 | config SYSVIPC_SYSCTL |
332 | bool | |
333 | depends on SYSVIPC | |
334 | depends on SYSCTL | |
335 | default y | |
336 | ||
1da177e4 LT |
337 | config POSIX_MQUEUE |
338 | bool "POSIX Message Queues" | |
19c92399 | 339 | depends on NET |
1da177e4 LT |
340 | ---help--- |
341 | POSIX variant of message queues is a part of IPC. In POSIX message | |
342 | queues every message has a priority which decides about succession | |
343 | of receiving it by a process. If you want to compile and run | |
344 | programs written e.g. for Solaris with use of its POSIX message | |
b0e37650 | 345 | queues (functions mq_*) say Y here. |
1da177e4 LT |
346 | |
347 | POSIX message queues are visible as a filesystem called 'mqueue' | |
348 | and can be mounted somewhere if you want to do filesystem | |
349 | operations on message queues. | |
350 | ||
351 | If unsure, say Y. | |
352 | ||
bdc8e5f8 SH |
353 | config POSIX_MQUEUE_SYSCTL |
354 | bool | |
355 | depends on POSIX_MQUEUE | |
356 | depends on SYSCTL | |
357 | default y | |
358 | ||
226b4ccd KK |
359 | config CROSS_MEMORY_ATTACH |
360 | bool "Enable process_vm_readv/writev syscalls" | |
361 | depends on MMU | |
362 | default y | |
363 | help | |
364 | Enabling this option adds the system calls process_vm_readv and | |
365 | process_vm_writev which allow a process with the correct privileges | |
a2a368d9 | 366 | to directly read from or write to another process' address space. |
226b4ccd KK |
367 | See the man page for more details. |
368 | ||
69369a70 JT |
369 | config USELIB |
370 | bool "uselib syscall" | |
b2113a41 | 371 | def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION |
69369a70 JT |
372 | help |
373 | This option enables the uselib syscall, a system call used in the | |
374 | dynamic linker from libc5 and earlier. glibc does not use this | |
375 | system call. If you intend to run programs built on libc5 or | |
376 | earlier, you may need to enable this syscall. Current systems | |
377 | running glibc can safely disable this. | |
378 | ||
391dc69c FW |
379 | config AUDIT |
380 | bool "Auditing support" | |
381 | depends on NET | |
382 | help | |
383 | Enable auditing infrastructure that can be used with another | |
384 | kernel subsystem, such as SELinux (which requires this for | |
cb74ed27 PM |
385 | logging of avc messages output). System call auditing is included |
386 | on architectures which support it. | |
391dc69c | 387 | |
7a017721 AT |
388 | config HAVE_ARCH_AUDITSYSCALL |
389 | bool | |
390 | ||
391dc69c | 391 | config AUDITSYSCALL |
cb74ed27 | 392 | def_bool y |
7a017721 | 393 | depends on AUDIT && HAVE_ARCH_AUDITSYSCALL |
391dc69c FW |
394 | select FSNOTIFY |
395 | ||
391dc69c FW |
396 | source "kernel/irq/Kconfig" |
397 | source "kernel/time/Kconfig" | |
87a4c375 | 398 | source "kernel/Kconfig.preempt" |
391dc69c FW |
399 | |
400 | menu "CPU/Task time and stats accounting" | |
401 | ||
abf917cd FW |
402 | config VIRT_CPU_ACCOUNTING |
403 | bool | |
404 | ||
fdf9c356 FW |
405 | choice |
406 | prompt "Cputime accounting" | |
407 | default TICK_CPU_ACCOUNTING if !PPC64 | |
02fc8d37 | 408 | default VIRT_CPU_ACCOUNTING_NATIVE if PPC64 |
fdf9c356 FW |
409 | |
410 | # Kind of a stub config for the pure tick based cputime accounting | |
411 | config TICK_CPU_ACCOUNTING | |
412 | bool "Simple tick based cputime accounting" | |
c58b0df1 | 413 | depends on !S390 && !NO_HZ_FULL |
fdf9c356 FW |
414 | help |
415 | This is the basic tick based cputime accounting that maintains | |
416 | statistics about user, system and idle time spent on per jiffies | |
417 | granularity. | |
418 | ||
419 | If unsure, say Y. | |
420 | ||
abf917cd | 421 | config VIRT_CPU_ACCOUNTING_NATIVE |
b952741c | 422 | bool "Deterministic task and CPU time accounting" |
c58b0df1 | 423 | depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL |
abf917cd | 424 | select VIRT_CPU_ACCOUNTING |
b952741c FW |
425 | help |
426 | Select this option to enable more accurate task and CPU time | |
427 | accounting. This is done by reading a CPU counter on each | |
428 | kernel entry and exit and on transitions within the kernel | |
429 | between system, softirq and hardirq state, so there is a | |
430 | small performance impact. In the case of s390 or IBM POWER > 5, | |
431 | this also enables accounting of stolen time on logically-partitioned | |
432 | systems. | |
433 | ||
abf917cd FW |
434 | config VIRT_CPU_ACCOUNTING_GEN |
435 | bool "Full dynticks CPU time accounting" | |
ff3fb254 | 436 | depends on HAVE_CONTEXT_TRACKING |
554b0004 | 437 | depends on HAVE_VIRT_CPU_ACCOUNTING_GEN |
041a1574 | 438 | depends on GENERIC_CLOCKEVENTS |
abf917cd FW |
439 | select VIRT_CPU_ACCOUNTING |
440 | select CONTEXT_TRACKING | |
441 | help | |
442 | Select this option to enable task and CPU time accounting on full | |
443 | dynticks systems. This accounting is implemented by watching every | |
444 | kernel-user boundaries using the context tracking subsystem. | |
445 | The accounting is thus performed at the expense of some significant | |
446 | overhead. | |
447 | ||
448 | For now this is only useful if you are working on the full | |
449 | dynticks subsystem development. | |
450 | ||
451 | If unsure, say N. | |
452 | ||
b58c3584 RR |
453 | endchoice |
454 | ||
fdf9c356 FW |
455 | config IRQ_TIME_ACCOUNTING |
456 | bool "Fine granularity task level IRQ time accounting" | |
b58c3584 | 457 | depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE |
fdf9c356 FW |
458 | help |
459 | Select this option to enable fine granularity task irq time | |
460 | accounting. This is done by reading a timestamp on each | |
461 | transitions between softirq and hardirq state, so there can be a | |
462 | small performance impact. | |
463 | ||
464 | If in doubt, say N here. | |
465 | ||
11d4afd4 VG |
466 | config HAVE_SCHED_AVG_IRQ |
467 | def_bool y | |
468 | depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING | |
469 | depends on SMP | |
470 | ||
1da177e4 LT |
471 | config BSD_PROCESS_ACCT |
472 | bool "BSD Process Accounting" | |
2813893f | 473 | depends on MULTIUSER |
1da177e4 LT |
474 | help |
475 | If you say Y here, a user level program will be able to instruct the | |
476 | kernel (via a special system call) to write process accounting | |
477 | information to a file: whenever a process exits, information about | |
478 | that process will be appended to the file by the kernel. The | |
479 | information includes things such as creation time, owning user, | |
480 | command name, memory usage, controlling terminal etc. (the complete | |
481 | list is in the struct acct in <file:include/linux/acct.h>). It is | |
482 | up to the user level program to do useful things with this | |
483 | information. This is generally a good idea, so say Y. | |
484 | ||
485 | config BSD_PROCESS_ACCT_V3 | |
486 | bool "BSD Process Accounting version 3 file format" | |
487 | depends on BSD_PROCESS_ACCT | |
488 | default n | |
489 | help | |
490 | If you say Y here, the process accounting information is written | |
491 | in a new file format that also logs the process IDs of each | |
3903bf94 | 492 | process and its parent. Note that this file format is incompatible |
1da177e4 LT |
493 | with previous v0/v1/v2 file formats, so you will need updated tools |
494 | for processing it. A preliminary version of these tools is available | |
37a4c940 | 495 | at <http://www.gnu.org/software/acct/>. |
1da177e4 | 496 | |
c757249a | 497 | config TASKSTATS |
19c92399 | 498 | bool "Export task/process statistics through netlink" |
c757249a | 499 | depends on NET |
2813893f | 500 | depends on MULTIUSER |
c757249a SN |
501 | default n |
502 | help | |
503 | Export selected statistics for tasks/processes through the | |
504 | generic netlink interface. Unlike BSD process accounting, the | |
505 | statistics are available during the lifetime of tasks/processes as | |
506 | responses to commands. Like BSD accounting, they are sent to user | |
507 | space on task exit. | |
508 | ||
509 | Say N if unsure. | |
510 | ||
ca74e92b | 511 | config TASK_DELAY_ACCT |
19c92399 | 512 | bool "Enable per-task delay accounting" |
6f44993f | 513 | depends on TASKSTATS |
f6db8347 | 514 | select SCHED_INFO |
ca74e92b SN |
515 | help |
516 | Collect information on time spent by a task waiting for system | |
517 | resources like cpu, synchronous block I/O completion and swapping | |
518 | in pages. Such statistics can help in setting a task's priorities | |
519 | relative to other tasks for cpu, io, rss limits etc. | |
520 | ||
521 | Say N if unsure. | |
522 | ||
18f705f4 | 523 | config TASK_XACCT |
19c92399 | 524 | bool "Enable extended accounting over taskstats" |
18f705f4 AD |
525 | depends on TASKSTATS |
526 | help | |
527 | Collect extended task accounting data and send the data | |
528 | to userland for processing over the taskstats interface. | |
529 | ||
530 | Say N if unsure. | |
531 | ||
532 | config TASK_IO_ACCOUNTING | |
19c92399 | 533 | bool "Enable per-task storage I/O accounting" |
18f705f4 AD |
534 | depends on TASK_XACCT |
535 | help | |
536 | Collect information on the number of bytes of storage I/O which this | |
537 | task has caused. | |
538 | ||
539 | Say N if unsure. | |
540 | ||
eb414681 JW |
541 | config PSI |
542 | bool "Pressure stall information tracking" | |
543 | help | |
544 | Collect metrics that indicate how overcommitted the CPU, memory, | |
545 | and IO capacity are in the system. | |
546 | ||
547 | If you say Y here, the kernel will create /proc/pressure/ with the | |
548 | pressure statistics files cpu, memory, and io. These will indicate | |
549 | the share of walltime in which some or all tasks in the system are | |
550 | delayed due to contention of the respective resource. | |
551 | ||
2ce7135a JW |
552 | In kernels with cgroup support, cgroups (cgroup2 only) will |
553 | have cpu.pressure, memory.pressure, and io.pressure files, | |
554 | which aggregate pressure stalls for the grouped tasks only. | |
555 | ||
c3123552 | 556 | For more details see Documentation/accounting/psi.rst. |
eb414681 JW |
557 | |
558 | Say N if unsure. | |
559 | ||
e0c27447 JW |
560 | config PSI_DEFAULT_DISABLED |
561 | bool "Require boot parameter to enable pressure stall information tracking" | |
562 | default n | |
563 | depends on PSI | |
564 | help | |
565 | If set, pressure stall information tracking will be disabled | |
428a1cb4 BS |
566 | per default but can be enabled through passing psi=1 on the |
567 | kernel commandline during boot. | |
e0c27447 | 568 | |
7b2489d3 JW |
569 | This feature adds some code to the task wakeup and sleep |
570 | paths of the scheduler. The overhead is too low to affect | |
571 | common scheduling-intense workloads in practice (such as | |
572 | webservers, memcache), but it does show up in artificial | |
573 | scheduler stress tests, such as hackbench. | |
574 | ||
575 | If you are paranoid and not sure what the kernel will be | |
576 | used for, say Y. | |
577 | ||
578 | Say N if unsure. | |
579 | ||
391dc69c | 580 | endmenu # "CPU/Task time and stats accounting" |
d9817ebe | 581 | |
5c4991e2 FW |
582 | config CPU_ISOLATION |
583 | bool "CPU isolation" | |
414a2dc1 | 584 | depends on SMP || COMPILE_TEST |
2c43838c | 585 | default y |
5c4991e2 FW |
586 | help |
587 | Make sure that CPUs running critical tasks are not disturbed by | |
588 | any source of "noise" such as unbound workqueues, timers, kthreads... | |
2c43838c FW |
589 | Unbound jobs get offloaded to housekeeping CPUs. This is driven by |
590 | the "isolcpus=" boot parameter. | |
591 | ||
592 | Say Y if unsure. | |
5c4991e2 | 593 | |
0af92d46 | 594 | source "kernel/rcu/Kconfig" |
c903ff83 | 595 | |
de5b56ba VG |
596 | config BUILD_BIN2C |
597 | bool | |
598 | default n | |
599 | ||
1da177e4 | 600 | config IKCONFIG |
f2443ab6 | 601 | tristate "Kernel .config support" |
1da177e4 LT |
602 | ---help--- |
603 | This option enables the complete Linux kernel ".config" file | |
604 | contents to be saved in the kernel. It provides documentation | |
605 | of which kernel options are used in a running kernel or in an | |
606 | on-disk kernel. This information can be extracted from the kernel | |
607 | image file with the script scripts/extract-ikconfig and used as | |
608 | input to rebuild the current kernel or to build another kernel. | |
609 | It can also be extracted from a running kernel by reading | |
610 | /proc/config.gz if enabled (below). | |
611 | ||
612 | config IKCONFIG_PROC | |
613 | bool "Enable access to .config through /proc/config.gz" | |
614 | depends on IKCONFIG && PROC_FS | |
615 | ---help--- | |
616 | This option enables access to the kernel configuration file | |
617 | through /proc/config.gz. | |
618 | ||
f7b101d3 JFG |
619 | config IKHEADERS |
620 | tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz" | |
621 | depends on SYSFS | |
622 | help | |
623 | This option enables access to the in-kernel headers that are generated during | |
624 | the build process. These can be used to build eBPF tracing programs, | |
625 | or similar programs. If you build the headers as a module, a module called | |
626 | kheaders.ko is built which can be loaded on-demand to get access to headers. | |
43d8ce9d | 627 | |
794543a2 AJS |
628 | config LOG_BUF_SHIFT |
629 | int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" | |
fb39f98d | 630 | range 12 25 |
f17a32e9 | 631 | default 17 |
361e9dfb | 632 | depends on PRINTK |
794543a2 | 633 | help |
23b2899f LR |
634 | Select the minimal kernel log buffer size as a power of 2. |
635 | The final size is affected by LOG_CPU_MAX_BUF_SHIFT config | |
636 | parameter, see below. Any higher size also might be forced | |
637 | by "log_buf_len" boot parameter. | |
638 | ||
f17a32e9 | 639 | Examples: |
23b2899f | 640 | 17 => 128 KB |
f17a32e9 | 641 | 16 => 64 KB |
23b2899f LR |
642 | 15 => 32 KB |
643 | 14 => 16 KB | |
794543a2 AJS |
644 | 13 => 8 KB |
645 | 12 => 4 KB | |
646 | ||
23b2899f LR |
647 | config LOG_CPU_MAX_BUF_SHIFT |
648 | int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" | |
2240a31d | 649 | depends on SMP |
23b2899f LR |
650 | range 0 21 |
651 | default 12 if !BASE_SMALL | |
652 | default 0 if BASE_SMALL | |
361e9dfb | 653 | depends on PRINTK |
23b2899f LR |
654 | help |
655 | This option allows to increase the default ring buffer size | |
656 | according to the number of CPUs. The value defines the contribution | |
657 | of each CPU as a power of 2. The used space is typically only few | |
658 | lines however it might be much more when problems are reported, | |
659 | e.g. backtraces. | |
660 | ||
661 | The increased size means that a new buffer has to be allocated and | |
662 | the original static one is unused. It makes sense only on systems | |
663 | with more CPUs. Therefore this value is used only when the sum of | |
664 | contributions is greater than the half of the default kernel ring | |
665 | buffer as defined by LOG_BUF_SHIFT. The default values are set | |
666 | so that more than 64 CPUs are needed to trigger the allocation. | |
667 | ||
668 | Also this option is ignored when "log_buf_len" kernel parameter is | |
669 | used as it forces an exact (power of two) size of the ring buffer. | |
670 | ||
671 | The number of possible CPUs is used for this computation ignoring | |
5e0d8d59 GU |
672 | hotplugging making the computation optimal for the worst case |
673 | scenario while allowing a simple algorithm to be used from bootup. | |
23b2899f LR |
674 | |
675 | Examples shift values and their meaning: | |
676 | 17 => 128 KB for each CPU | |
677 | 16 => 64 KB for each CPU | |
678 | 15 => 32 KB for each CPU | |
679 | 14 => 16 KB for each CPU | |
680 | 13 => 8 KB for each CPU | |
681 | 12 => 4 KB for each CPU | |
682 | ||
f92bac3b SS |
683 | config PRINTK_SAFE_LOG_BUF_SHIFT |
684 | int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)" | |
427934b8 PM |
685 | range 10 21 |
686 | default 13 | |
f92bac3b | 687 | depends on PRINTK |
427934b8 | 688 | help |
f92bac3b SS |
689 | Select the size of an alternate printk per-CPU buffer where messages |
690 | printed from usafe contexts are temporary stored. One example would | |
691 | be NMI messages, another one - printk recursion. The messages are | |
692 | copied to the main log buffer in a safe context to avoid a deadlock. | |
693 | The value defines the size as a power of 2. | |
427934b8 | 694 | |
f92bac3b | 695 | Those messages are rare and limited. The largest one is when |
427934b8 PM |
696 | a backtrace is printed. It usually fits into 4KB. Select |
697 | 8KB if you want to be on the safe side. | |
698 | ||
699 | Examples: | |
700 | 17 => 128 KB for each CPU | |
701 | 16 => 64 KB for each CPU | |
702 | 15 => 32 KB for each CPU | |
703 | 14 => 16 KB for each CPU | |
704 | 13 => 8 KB for each CPU | |
705 | 12 => 4 KB for each CPU | |
706 | ||
a5574cf6 IM |
707 | # |
708 | # Architectures with an unreliable sched_clock() should select this: | |
709 | # | |
710 | config HAVE_UNSTABLE_SCHED_CLOCK | |
711 | bool | |
712 | ||
38ff87f7 SB |
713 | config GENERIC_SCHED_CLOCK |
714 | bool | |
715 | ||
69842cba PB |
716 | menu "Scheduler features" |
717 | ||
718 | config UCLAMP_TASK | |
719 | bool "Enable utilization clamping for RT/FAIR tasks" | |
720 | depends on CPU_FREQ_GOV_SCHEDUTIL | |
721 | help | |
722 | This feature enables the scheduler to track the clamped utilization | |
723 | of each CPU based on RUNNABLE tasks scheduled on that CPU. | |
724 | ||
725 | With this option, the user can specify the min and max CPU | |
726 | utilization allowed for RUNNABLE tasks. The max utilization defines | |
727 | the maximum frequency a task should use while the min utilization | |
728 | defines the minimum frequency it should use. | |
729 | ||
730 | Both min and max utilization clamp values are hints to the scheduler, | |
731 | aiming at improving its frequency selection policy, but they do not | |
732 | enforce or grant any specific bandwidth for tasks. | |
733 | ||
734 | If in doubt, say N. | |
735 | ||
736 | config UCLAMP_BUCKETS_COUNT | |
737 | int "Number of supported utilization clamp buckets" | |
738 | range 5 20 | |
739 | default 5 | |
740 | depends on UCLAMP_TASK | |
741 | help | |
742 | Defines the number of clamp buckets to use. The range of each bucket | |
743 | will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the | |
744 | number of clamp buckets the finer their granularity and the higher | |
745 | the precision of clamping aggregation and tracking at run-time. | |
746 | ||
747 | For example, with the minimum configuration value we will have 5 | |
748 | clamp buckets tracking 20% utilization each. A 25% boosted tasks will | |
749 | be refcounted in the [20..39]% bucket and will set the bucket clamp | |
750 | effective value to 25%. | |
751 | If a second 30% boosted task should be co-scheduled on the same CPU, | |
752 | that task will be refcounted in the same bucket of the first task and | |
753 | it will boost the bucket clamp effective value to 30%. | |
754 | The clamp effective value of a bucket is reset to its nominal value | |
755 | (20% in the example above) when there are no more tasks refcounted in | |
756 | that bucket. | |
757 | ||
758 | An additional boost/capping margin can be added to some tasks. In the | |
759 | example above the 25% task will be boosted to 30% until it exits the | |
760 | CPU. If that should be considered not acceptable on certain systems, | |
761 | it's always possible to reduce the margin by increasing the number of | |
762 | clamp buckets to trade off used memory for run-time tracking | |
763 | precision. | |
764 | ||
765 | If in doubt, use the default value. | |
766 | ||
767 | endmenu | |
768 | ||
be3a7284 AA |
769 | # |
770 | # For architectures that want to enable the support for NUMA-affine scheduler | |
771 | # balancing logic: | |
772 | # | |
773 | config ARCH_SUPPORTS_NUMA_BALANCING | |
774 | bool | |
775 | ||
72b252ae MG |
776 | # |
777 | # For architectures that prefer to flush all TLBs after a number of pages | |
778 | # are unmapped instead of sending one IPI per page to flush. The architecture | |
779 | # must provide guarantees on what happens if a clean TLB cache entry is | |
780 | # written after the unmap. Details are in mm/rmap.c near the check for | |
781 | # should_defer_flush. The architecture should also consider if the full flush | |
782 | # and the refill costs are offset by the savings of sending fewer IPIs. | |
783 | config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH | |
784 | bool | |
785 | ||
be5e610c PZ |
786 | # |
787 | # For architectures that know their GCC __int128 support is sound | |
788 | # | |
789 | config ARCH_SUPPORTS_INT128 | |
790 | bool | |
791 | ||
be3a7284 AA |
792 | # For architectures that (ab)use NUMA to represent different memory regions |
793 | # all cpu-local but of different latencies, such as SuperH. | |
794 | # | |
795 | config ARCH_WANT_NUMA_VARIABLE_LOCALITY | |
796 | bool | |
797 | ||
be3a7284 AA |
798 | config NUMA_BALANCING |
799 | bool "Memory placement aware NUMA scheduler" | |
be3a7284 AA |
800 | depends on ARCH_SUPPORTS_NUMA_BALANCING |
801 | depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY | |
802 | depends on SMP && NUMA && MIGRATION | |
803 | help | |
804 | This option adds support for automatic NUMA aware memory/task placement. | |
805 | The mechanism is quite primitive and is based on migrating memory when | |
6d56a410 | 806 | it has references to the node the task is running on. |
be3a7284 AA |
807 | |
808 | This system will be inactive on UMA systems. | |
809 | ||
6f7c97e8 AK |
810 | config NUMA_BALANCING_DEFAULT_ENABLED |
811 | bool "Automatically enable NUMA aware memory/task placement" | |
812 | default y | |
813 | depends on NUMA_BALANCING | |
814 | help | |
815 | If set, automatic NUMA balancing will be enabled if running on a NUMA | |
816 | machine. | |
817 | ||
23964d2d | 818 | menuconfig CGROUPS |
6341e62b | 819 | bool "Control Group support" |
2bd59d48 | 820 | select KERNFS |
5cdc38f9 | 821 | help |
23964d2d | 822 | This option adds support for grouping sets of processes together, for |
5cdc38f9 KH |
823 | use with process control subsystems such as Cpusets, CFS, memory |
824 | controls or device isolation. | |
825 | See | |
d6a3b247 | 826 | - Documentation/scheduler/sched-design-CFS.rst (CFS) |
da82c92f | 827 | - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation |
45ce80fb | 828 | and resource control) |
5cdc38f9 KH |
829 | |
830 | Say N if unsure. | |
831 | ||
23964d2d LZ |
832 | if CGROUPS |
833 | ||
3e32cb2e JW |
834 | config PAGE_COUNTER |
835 | bool | |
836 | ||
c255a458 | 837 | config MEMCG |
a0166ec4 | 838 | bool "Memory controller" |
3e32cb2e | 839 | select PAGE_COUNTER |
79bd9814 | 840 | select EVENTFD |
00f0b825 | 841 | help |
a0166ec4 | 842 | Provides control over the memory footprint of tasks in a cgroup. |
00f0b825 | 843 | |
c255a458 | 844 | config MEMCG_SWAP |
a0166ec4 | 845 | bool "Swap controller" |
c255a458 | 846 | depends on MEMCG && SWAP |
c077719b | 847 | help |
a0166ec4 JW |
848 | Provides control over the swap space consumed by tasks in a cgroup. |
849 | ||
c255a458 | 850 | config MEMCG_SWAP_ENABLED |
a0166ec4 | 851 | bool "Swap controller enabled by default" |
c255a458 | 852 | depends on MEMCG_SWAP |
a42c390c MH |
853 | default y |
854 | help | |
855 | Memory Resource Controller Swap Extension comes with its price in | |
856 | a bigger memory consumption. General purpose distribution kernels | |
43d547f9 | 857 | which want to enable the feature but keep it disabled by default |
07555ac1 | 858 | and let the user enable it by swapaccount=1 boot command line |
a42c390c MH |
859 | parameter should have this option unselected. |
860 | For those who want to have the feature enabled by default should | |
861 | select this option (if, for some reason, they need to disable it | |
00a66d29 | 862 | then swapaccount=0 does the trick). |
c077719b | 863 | |
84c07d11 KT |
864 | config MEMCG_KMEM |
865 | bool | |
866 | depends on MEMCG && !SLOB | |
867 | default y | |
868 | ||
6bf024e6 JW |
869 | config BLK_CGROUP |
870 | bool "IO controller" | |
871 | depends on BLOCK | |
2bc64a20 | 872 | default n |
6bf024e6 JW |
873 | ---help--- |
874 | Generic block IO controller cgroup interface. This is the common | |
875 | cgroup interface which should be used by various IO controlling | |
876 | policies. | |
2bc64a20 | 877 | |
6bf024e6 JW |
878 | Currently, CFQ IO scheduler uses it to recognize task groups and |
879 | control disk bandwidth allocation (proportional time slice allocation) | |
880 | to such task groups. It is also used by bio throttling logic in | |
881 | block layer to implement upper limit in IO rates on a device. | |
e5d1367f | 882 | |
6bf024e6 JW |
883 | This option only enables generic Block IO controller infrastructure. |
884 | One needs to also enable actual IO controlling logic/policy. For | |
885 | enabling proportional weight division of disk bandwidth in CFQ, set | |
886 | CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set | |
887 | CONFIG_BLK_DEV_THROTTLING=y. | |
888 | ||
da82c92f | 889 | See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information. |
6bf024e6 | 890 | |
6bf024e6 JW |
891 | config CGROUP_WRITEBACK |
892 | bool | |
893 | depends on MEMCG && BLK_CGROUP | |
894 | default y | |
e5d1367f | 895 | |
7c941438 | 896 | menuconfig CGROUP_SCHED |
a0166ec4 | 897 | bool "CPU controller" |
7c941438 DG |
898 | default n |
899 | help | |
900 | This feature lets CPU scheduler recognize task groups and control CPU | |
901 | bandwidth allocation to such task groups. It uses cgroups to group | |
902 | tasks. | |
903 | ||
904 | if CGROUP_SCHED | |
905 | config FAIR_GROUP_SCHED | |
906 | bool "Group scheduling for SCHED_OTHER" | |
907 | depends on CGROUP_SCHED | |
908 | default CGROUP_SCHED | |
909 | ||
ab84d31e PT |
910 | config CFS_BANDWIDTH |
911 | bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" | |
ab84d31e PT |
912 | depends on FAIR_GROUP_SCHED |
913 | default n | |
914 | help | |
915 | This option allows users to define CPU bandwidth rates (limits) for | |
916 | tasks running within the fair group scheduler. Groups with no limit | |
917 | set are considered to be unconstrained and will run with no | |
918 | restriction. | |
d6a3b247 | 919 | See Documentation/scheduler/sched-bwc.rst for more information. |
ab84d31e | 920 | |
7c941438 DG |
921 | config RT_GROUP_SCHED |
922 | bool "Group scheduling for SCHED_RR/FIFO" | |
7c941438 DG |
923 | depends on CGROUP_SCHED |
924 | default n | |
925 | help | |
926 | This feature lets you explicitly allocate real CPU bandwidth | |
32bd7eb5 | 927 | to task groups. If enabled, it will also make it impossible to |
7c941438 DG |
928 | schedule realtime tasks for non-root users until you allocate |
929 | realtime bandwidth for them. | |
d6a3b247 | 930 | See Documentation/scheduler/sched-rt-group.rst for more information. |
7c941438 DG |
931 | |
932 | endif #CGROUP_SCHED | |
933 | ||
2480c093 PB |
934 | config UCLAMP_TASK_GROUP |
935 | bool "Utilization clamping per group of tasks" | |
936 | depends on CGROUP_SCHED | |
937 | depends on UCLAMP_TASK | |
938 | default n | |
939 | help | |
940 | This feature enables the scheduler to track the clamped utilization | |
941 | of each CPU based on RUNNABLE tasks currently scheduled on that CPU. | |
942 | ||
943 | When this option is enabled, the user can specify a min and max | |
944 | CPU bandwidth which is allowed for each single task in a group. | |
945 | The max bandwidth allows to clamp the maximum frequency a task | |
946 | can use, while the min bandwidth allows to define a minimum | |
947 | frequency a task will always use. | |
948 | ||
949 | When task group based utilization clamping is enabled, an eventually | |
950 | specified task-specific clamp value is constrained by the cgroup | |
951 | specified clamp value. Both minimum and maximum task clamping cannot | |
952 | be bigger than the corresponding clamping defined at task group level. | |
953 | ||
954 | If in doubt, say N. | |
955 | ||
6bf024e6 JW |
956 | config CGROUP_PIDS |
957 | bool "PIDs controller" | |
958 | help | |
959 | Provides enforcement of process number limits in the scope of a | |
960 | cgroup. Any attempt to fork more processes than is allowed in the | |
961 | cgroup will fail. PIDs are fundamentally a global resource because it | |
962 | is fairly trivial to reach PID exhaustion before you reach even a | |
963 | conservative kmemcg limit. As a result, it is possible to grind a | |
964 | system to halt without being limited by other cgroup policies. The | |
6cc578df | 965 | PIDs controller is designed to stop this from happening. |
6bf024e6 JW |
966 | |
967 | It should be noted that organisational operations (such as attaching | |
98076833 | 968 | to a cgroup hierarchy) will *not* be blocked by the PIDs controller, |
6bf024e6 JW |
969 | since the PIDs limit only affects a process's ability to fork, not to |
970 | attach to a cgroup. | |
971 | ||
39d3e758 PP |
972 | config CGROUP_RDMA |
973 | bool "RDMA controller" | |
974 | help | |
975 | Provides enforcement of RDMA resources defined by IB stack. | |
976 | It is fairly easy for consumers to exhaust RDMA resources, which | |
977 | can result into resource unavailability to other consumers. | |
978 | RDMA controller is designed to stop this from happening. | |
979 | Attaching processes with active RDMA resources to the cgroup | |
980 | hierarchy is allowed even if can cross the hierarchy's limit. | |
981 | ||
6bf024e6 JW |
982 | config CGROUP_FREEZER |
983 | bool "Freezer controller" | |
984 | help | |
985 | Provides a way to freeze and unfreeze all tasks in a | |
986 | cgroup. | |
987 | ||
489c2a20 JW |
988 | This option affects the ORIGINAL cgroup interface. The cgroup2 memory |
989 | controller includes important in-kernel memory consumers per default. | |
990 | ||
991 | If you're using cgroup2, say N. | |
992 | ||
6bf024e6 JW |
993 | config CGROUP_HUGETLB |
994 | bool "HugeTLB controller" | |
995 | depends on HUGETLB_PAGE | |
996 | select PAGE_COUNTER | |
afc24d49 | 997 | default n |
6bf024e6 JW |
998 | help |
999 | Provides a cgroup controller for HugeTLB pages. | |
1000 | When you enable this, you can put a per cgroup limit on HugeTLB usage. | |
1001 | The limit is enforced during page fault. Since HugeTLB doesn't | |
1002 | support page reclaim, enforcing the limit at page fault time implies | |
1003 | that, the application will get SIGBUS signal if it tries to access | |
1004 | HugeTLB pages beyond its limit. This requires the application to know | |
1005 | beforehand how much HugeTLB pages it would require for its use. The | |
1006 | control group is tracked in the third page lru pointer. This means | |
1007 | that we cannot use the controller with huge page less than 3 pages. | |
afc24d49 | 1008 | |
6bf024e6 JW |
1009 | config CPUSETS |
1010 | bool "Cpuset controller" | |
e1d4eeec | 1011 | depends on SMP |
6bf024e6 JW |
1012 | help |
1013 | This option will let you create and manage CPUSETs which | |
1014 | allow dynamically partitioning a system into sets of CPUs and | |
1015 | Memory Nodes and assigning tasks to run only within those sets. | |
1016 | This is primarily useful on large SMP or NUMA systems. | |
afc24d49 | 1017 | |
6bf024e6 | 1018 | Say N if unsure. |
afc24d49 | 1019 | |
6bf024e6 JW |
1020 | config PROC_PID_CPUSET |
1021 | bool "Include legacy /proc/<pid>/cpuset file" | |
1022 | depends on CPUSETS | |
1023 | default y | |
afc24d49 | 1024 | |
6bf024e6 JW |
1025 | config CGROUP_DEVICE |
1026 | bool "Device controller" | |
1027 | help | |
1028 | Provides a cgroup controller implementing whitelists for | |
1029 | devices which a process in the cgroup can mknod or open. | |
1030 | ||
1031 | config CGROUP_CPUACCT | |
1032 | bool "Simple CPU accounting controller" | |
1033 | help | |
1034 | Provides a simple controller for monitoring the | |
1035 | total CPU consumed by the tasks in a cgroup. | |
1036 | ||
1037 | config CGROUP_PERF | |
1038 | bool "Perf controller" | |
1039 | depends on PERF_EVENTS | |
1040 | help | |
1041 | This option extends the perf per-cpu mode to restrict monitoring | |
1042 | to threads which belong to the cgroup specified and run on the | |
1043 | designated cpu. | |
1044 | ||
1045 | Say N if unsure. | |
1046 | ||
30070984 DM |
1047 | config CGROUP_BPF |
1048 | bool "Support for eBPF programs attached to cgroups" | |
483c4933 AL |
1049 | depends on BPF_SYSCALL |
1050 | select SOCK_CGROUP_DATA | |
30070984 DM |
1051 | help |
1052 | Allow attaching eBPF programs to a cgroup using the bpf(2) | |
1053 | syscall command BPF_PROG_ATTACH. | |
1054 | ||
1055 | In which context these programs are accessed depends on the type | |
1056 | of attachment. For instance, programs that are attached using | |
1057 | BPF_CGROUP_INET_INGRESS will be executed on the ingress path of | |
1058 | inet sockets. | |
1059 | ||
6bf024e6 | 1060 | config CGROUP_DEBUG |
23b0be48 | 1061 | bool "Debug controller" |
afc24d49 | 1062 | default n |
23b0be48 | 1063 | depends on DEBUG_KERNEL |
6bf024e6 JW |
1064 | help |
1065 | This option enables a simple controller that exports | |
23b0be48 WL |
1066 | debugging information about the cgroups framework. This |
1067 | controller is for control cgroup debugging only. Its | |
1068 | interfaces are not stable. | |
afc24d49 | 1069 | |
6bf024e6 | 1070 | Say N. |
89e9b9e0 | 1071 | |
73b35147 AB |
1072 | config SOCK_CGROUP_DATA |
1073 | bool | |
1074 | default n | |
1075 | ||
23964d2d | 1076 | endif # CGROUPS |
c077719b | 1077 | |
8dd2a82c | 1078 | menuconfig NAMESPACES |
6a108a14 | 1079 | bool "Namespaces support" if EXPERT |
2813893f | 1080 | depends on MULTIUSER |
6a108a14 | 1081 | default !EXPERT |
c5289a69 PE |
1082 | help |
1083 | Provides the way to make tasks work with different objects using | |
1084 | the same id. For example same IPC id may refer to different objects | |
1085 | or same user id or pid may refer to different tasks when used in | |
1086 | different namespaces. | |
1087 | ||
8dd2a82c DL |
1088 | if NAMESPACES |
1089 | ||
58bfdd6d PE |
1090 | config UTS_NS |
1091 | bool "UTS namespace" | |
17a6d441 | 1092 | default y |
58bfdd6d PE |
1093 | help |
1094 | In this namespace tasks see different info provided with the | |
1095 | uname() system call | |
1096 | ||
ae5e1b22 PE |
1097 | config IPC_NS |
1098 | bool "IPC namespace" | |
8dd2a82c | 1099 | depends on (SYSVIPC || POSIX_MQUEUE) |
17a6d441 | 1100 | default y |
ae5e1b22 PE |
1101 | help |
1102 | In this namespace tasks work with IPC ids which correspond to | |
614b84cf | 1103 | different IPC objects in different namespaces. |
ae5e1b22 | 1104 | |
aee16ce7 | 1105 | config USER_NS |
19c92399 | 1106 | bool "User namespace" |
5673a94c | 1107 | default n |
aee16ce7 PE |
1108 | help |
1109 | This allows containers, i.e. vservers, to use user namespaces | |
1110 | to provide different user info for different servers. | |
e11f0ae3 EB |
1111 | |
1112 | When user namespaces are enabled in the kernel it is | |
d886f4e4 JW |
1113 | recommended that the MEMCG option also be enabled and that |
1114 | user-space use the memory control groups to limit the amount | |
1115 | of memory a memory unprivileged users can use. | |
e11f0ae3 | 1116 | |
aee16ce7 PE |
1117 | If unsure, say N. |
1118 | ||
74bd59bb | 1119 | config PID_NS |
9bd38c2c | 1120 | bool "PID Namespaces" |
17a6d441 | 1121 | default y |
74bd59bb | 1122 | help |
12d2b8f9 | 1123 | Support process id namespaces. This allows having multiple |
692105b8 | 1124 | processes with the same pid as long as they are in different |
74bd59bb PE |
1125 | pid namespaces. This is a building block of containers. |
1126 | ||
d6eb633f MH |
1127 | config NET_NS |
1128 | bool "Network namespace" | |
8dd2a82c | 1129 | depends on NET |
17a6d441 | 1130 | default y |
d6eb633f MH |
1131 | help |
1132 | Allow user space to create what appear to be multiple instances | |
1133 | of the network stack. | |
1134 | ||
8dd2a82c DL |
1135 | endif # NAMESPACES |
1136 | ||
5cb366bb AR |
1137 | config CHECKPOINT_RESTORE |
1138 | bool "Checkpoint/restore support" | |
1139 | select PROC_CHILDREN | |
1140 | default n | |
1141 | help | |
1142 | Enables additional kernel features in a sake of checkpoint/restore. | |
1143 | In particular it adds auxiliary prctl codes to setup process text, | |
1144 | data and heap segment sizes, and a few additional /proc filesystem | |
1145 | entries. | |
1146 | ||
1147 | If unsure, say N here. | |
1148 | ||
5091faa4 MG |
1149 | config SCHED_AUTOGROUP |
1150 | bool "Automatic process group scheduling" | |
5091faa4 MG |
1151 | select CGROUPS |
1152 | select CGROUP_SCHED | |
1153 | select FAIR_GROUP_SCHED | |
1154 | help | |
1155 | This option optimizes the scheduler for common desktop workloads by | |
1156 | automatically creating and populating task groups. This separation | |
1157 | of workloads isolates aggressive CPU burners (like build jobs) from | |
1158 | desktop applications. Task group autogeneration is currently based | |
1159 | upon task session. | |
1160 | ||
7af37bec | 1161 | config SYSFS_DEPRECATED |
5d6a4ea5 | 1162 | bool "Enable deprecated sysfs features to support old userspace tools" |
7af37bec DL |
1163 | depends on SYSFS |
1164 | default n | |
1165 | help | |
1166 | This option adds code that switches the layout of the "block" class | |
1167 | devices, to not show up in /sys/class/block/, but only in | |
1168 | /sys/block/. | |
1169 | ||
1170 | This switch is only active when the sysfs.deprecated=1 boot option is | |
1171 | passed or the SYSFS_DEPRECATED_V2 option is set. | |
1172 | ||
1173 | This option allows new kernels to run on old distributions and tools, | |
1174 | which might get confused by /sys/class/block/. Since 2007/2008 all | |
1175 | major distributions and tools handle this just fine. | |
1176 | ||
1177 | Recent distributions and userspace tools after 2009/2010 depend on | |
1178 | the existence of /sys/class/block/, and will not work with this | |
1179 | option enabled. | |
1180 | ||
1181 | Only if you are using a new kernel on an old distribution, you might | |
1182 | need to say Y here. | |
1183 | ||
1184 | config SYSFS_DEPRECATED_V2 | |
5d6a4ea5 | 1185 | bool "Enable deprecated sysfs features by default" |
7af37bec DL |
1186 | default n |
1187 | depends on SYSFS | |
1188 | depends on SYSFS_DEPRECATED | |
1189 | help | |
1190 | Enable deprecated sysfs by default. | |
1191 | ||
1192 | See the CONFIG_SYSFS_DEPRECATED option for more details about this | |
1193 | option. | |
1194 | ||
1195 | Only if you are using a new kernel on an old distribution, you might | |
1196 | need to say Y here. Even then, odds are you would not need it | |
1197 | enabled, you can always pass the boot option if absolutely necessary. | |
1198 | ||
1199 | config RELAY | |
1200 | bool "Kernel->user space relay support (formerly relayfs)" | |
26b5679e | 1201 | select IRQ_WORK |
7af37bec DL |
1202 | help |
1203 | This option enables support for relay interface support in | |
1204 | certain file systems (such as debugfs). | |
1205 | It is designed to provide an efficient mechanism for tools and | |
1206 | facilities to relay large amounts of data from kernel space to | |
1207 | user space. | |
1208 | ||
1209 | If unsure, say N. | |
1210 | ||
f991633d DG |
1211 | config BLK_DEV_INITRD |
1212 | bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" | |
f991633d DG |
1213 | help |
1214 | The initial RAM filesystem is a ramfs which is loaded by the | |
1215 | boot loader (loadlin or lilo) and that is mounted as root | |
1216 | before the normal boot procedure. It is typically used to | |
1217 | load modules needed to mount the "real" root file system, | |
8c27ceff | 1218 | etc. See <file:Documentation/admin-guide/initrd.rst> for details. |
f991633d DG |
1219 | |
1220 | If RAM disk support (BLK_DEV_RAM) is also included, this | |
1221 | also enables initial RAM disk (initrd) support and adds | |
1222 | 15 Kbytes (more on some other architectures) to the kernel size. | |
1223 | ||
1224 | If unsure say Y. | |
1225 | ||
c33df4ea JPS |
1226 | if BLK_DEV_INITRD |
1227 | ||
dbec4866 SR |
1228 | source "usr/Kconfig" |
1229 | ||
c33df4ea JPS |
1230 | endif |
1231 | ||
877417e6 AB |
1232 | choice |
1233 | prompt "Compiler optimization level" | |
2cc3ce24 | 1234 | default CC_OPTIMIZE_FOR_PERFORMANCE |
877417e6 AB |
1235 | |
1236 | config CC_OPTIMIZE_FOR_PERFORMANCE | |
1237 | bool "Optimize for performance" | |
1238 | help | |
1239 | This is the default optimization level for the kernel, building | |
1240 | with the "-O2" compiler flag for best performance and most | |
1241 | helpful compile-time warnings. | |
1242 | ||
c45b4f1f | 1243 | config CC_OPTIMIZE_FOR_SIZE |
96fffeb4 | 1244 | bool "Optimize for size" |
b303c6df | 1245 | imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED # avoid false positives |
c45b4f1f | 1246 | help |
31a4af7f MY |
1247 | Enabling this option will pass "-Os" instead of "-O2" to |
1248 | your compiler resulting in a smaller kernel. | |
c45b4f1f | 1249 | |
3a55fb0d | 1250 | If unsure, say N. |
c45b4f1f | 1251 | |
877417e6 AB |
1252 | endchoice |
1253 | ||
5d20ee31 NP |
1254 | config HAVE_LD_DEAD_CODE_DATA_ELIMINATION |
1255 | bool | |
1256 | help | |
1257 | This requires that the arch annotates or otherwise protects | |
1258 | its external entry points from being discarded. Linker scripts | |
1259 | must also merge .text.*, .data.*, and .bss.* correctly into | |
1260 | output sections. Care must be taken not to pull in unrelated | |
1261 | sections (e.g., '.text.init'). Typically '.' in section names | |
1262 | is used to distinguish them from label names / C identifiers. | |
1263 | ||
1264 | config LD_DEAD_CODE_DATA_ELIMINATION | |
1265 | bool "Dead code and data elimination (EXPERIMENTAL)" | |
1266 | depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION | |
1267 | depends on EXPERT | |
16fd20aa | 1268 | depends on !(FUNCTION_TRACER && CC_IS_GCC && GCC_VERSION < 40800) |
e85d1d65 MY |
1269 | depends on $(cc-option,-ffunction-sections -fdata-sections) |
1270 | depends on $(ld-option,--gc-sections) | |
5d20ee31 | 1271 | help |
8b9d2712 MY |
1272 | Enable this if you want to do dead code and data elimination with |
1273 | the linker by compiling with -ffunction-sections -fdata-sections, | |
1274 | and linking with --gc-sections. | |
5d20ee31 NP |
1275 | |
1276 | This can reduce on disk and in-memory size of the kernel | |
1277 | code and static data, particularly for small configs and | |
1278 | on small systems. This has the possibility of introducing | |
1279 | silently broken kernel if the required annotations are not | |
1280 | present. This option is not well tested yet, so use at your | |
1281 | own risk. | |
1282 | ||
0847062a RD |
1283 | config SYSCTL |
1284 | bool | |
1285 | ||
657a5209 MF |
1286 | config HAVE_UID16 |
1287 | bool | |
1288 | ||
1289 | config SYSCTL_EXCEPTION_TRACE | |
1290 | bool | |
1291 | help | |
1292 | Enable support for /proc/sys/debug/exception-trace. | |
1293 | ||
1294 | config SYSCTL_ARCH_UNALIGN_NO_WARN | |
1295 | bool | |
1296 | help | |
1297 | Enable support for /proc/sys/kernel/ignore-unaligned-usertrap | |
1298 | Allows arch to define/use @no_unaligned_warning to possibly warn | |
1299 | about unaligned access emulation going on under the hood. | |
1300 | ||
1301 | config SYSCTL_ARCH_UNALIGN_ALLOW | |
1302 | bool | |
1303 | help | |
1304 | Enable support for /proc/sys/kernel/unaligned-trap | |
1305 | Allows arches to define/use @unaligned_enabled to runtime toggle | |
1306 | the unaligned access emulation. | |
1307 | see arch/parisc/kernel/unaligned.c for reference | |
1308 | ||
657a5209 MF |
1309 | config HAVE_PCSPKR_PLATFORM |
1310 | bool | |
1311 | ||
f89b7755 AS |
1312 | # interpreter that classic socket filters depend on |
1313 | config BPF | |
1314 | bool | |
1315 | ||
6a108a14 DR |
1316 | menuconfig EXPERT |
1317 | bool "Configure standard kernel features (expert users)" | |
f505c553 JT |
1318 | # Unhide debug options, to make the on-by-default options visible |
1319 | select DEBUG_KERNEL | |
1da177e4 LT |
1320 | help |
1321 | This option allows certain base kernel options and settings | |
1322 | to be disabled or tweaked. This is for specialized | |
1323 | environments which can tolerate a "non-standard" kernel. | |
1324 | Only use this if you really know what you are doing. | |
1325 | ||
ae81f9e3 | 1326 | config UID16 |
6a108a14 | 1327 | bool "Enable 16-bit UID system calls" if EXPERT |
2813893f | 1328 | depends on HAVE_UID16 && MULTIUSER |
ae81f9e3 CE |
1329 | default y |
1330 | help | |
1331 | This enables the legacy 16-bit UID syscall wrappers. | |
1332 | ||
2813893f IM |
1333 | config MULTIUSER |
1334 | bool "Multiple users, groups and capabilities support" if EXPERT | |
1335 | default y | |
1336 | help | |
1337 | This option enables support for non-root users, groups and | |
1338 | capabilities. | |
1339 | ||
1340 | If you say N here, all processes will run with UID 0, GID 0, and all | |
1341 | possible capabilities. Saying N here also compiles out support for | |
1342 | system calls related to UIDs, GIDs, and capabilities, such as setuid, | |
1343 | setgid, and capset. | |
1344 | ||
1345 | If unsure, say Y here. | |
1346 | ||
f6187769 FF |
1347 | config SGETMASK_SYSCALL |
1348 | bool "sgetmask/ssetmask syscalls support" if EXPERT | |
a687a533 | 1349 | def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH |
f6187769 FF |
1350 | ---help--- |
1351 | sys_sgetmask and sys_ssetmask are obsolete system calls | |
1352 | no longer supported in libc but still enabled by default in some | |
1353 | architectures. | |
1354 | ||
1355 | If unsure, leave the default option here. | |
1356 | ||
6af9f7bf FF |
1357 | config SYSFS_SYSCALL |
1358 | bool "Sysfs syscall support" if EXPERT | |
1359 | default y | |
1360 | ---help--- | |
1361 | sys_sysfs is an obsolete system call no longer supported in libc. | |
1362 | Note that disabling this option is more secure but might break | |
1363 | compatibility with some systems. | |
1364 | ||
1365 | If unsure say Y here. | |
1366 | ||
b89a8171 | 1367 | config SYSCTL_SYSCALL |
6a108a14 | 1368 | bool "Sysctl syscall support" if EXPERT |
26a7034b | 1369 | depends on PROC_SYSCTL |
c736de60 | 1370 | default n |
b89a8171 | 1371 | select SYSCTL |
ae81f9e3 | 1372 | ---help--- |
13bb7e37 EB |
1373 | sys_sysctl uses binary paths that have been found challenging |
1374 | to properly maintain and use. The interface in /proc/sys | |
1375 | using paths with ascii names is now the primary path to this | |
1376 | information. | |
b89a8171 | 1377 | |
13bb7e37 EB |
1378 | Almost nothing using the binary sysctl interface so if you are |
1379 | trying to save some space it is probably safe to disable this, | |
1380 | making your kernel marginally smaller. | |
b89a8171 | 1381 | |
c736de60 | 1382 | If unsure say N here. |
ae81f9e3 | 1383 | |
d1b069f5 RD |
1384 | config FHANDLE |
1385 | bool "open by fhandle syscalls" if EXPERT | |
1386 | select EXPORTFS | |
1387 | default y | |
1388 | help | |
1389 | If you say Y here, a user level program will be able to map | |
1390 | file names to handle and then later use the handle for | |
1391 | different file system operations. This is useful in implementing | |
1392 | userspace file servers, which now track files using handles instead | |
1393 | of names. The handle would remain the same even if file names | |
1394 | get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) | |
1395 | syscalls. | |
1396 | ||
baa73d9e NP |
1397 | config POSIX_TIMERS |
1398 | bool "Posix Clocks & timers" if EXPERT | |
1399 | default y | |
1400 | help | |
1401 | This includes native support for POSIX timers to the kernel. | |
1402 | Some embedded systems have no use for them and therefore they | |
1403 | can be configured out to reduce the size of the kernel image. | |
1404 | ||
1405 | When this option is disabled, the following syscalls won't be | |
1406 | available: timer_create, timer_gettime: timer_getoverrun, | |
1407 | timer_settime, timer_delete, clock_adjtime, getitimer, | |
1408 | setitimer, alarm. Furthermore, the clock_settime, clock_gettime, | |
1409 | clock_getres and clock_nanosleep syscalls will be limited to | |
1410 | CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. | |
1411 | ||
1412 | If unsure say y. | |
1413 | ||
d59745ce MM |
1414 | config PRINTK |
1415 | default y | |
6a108a14 | 1416 | bool "Enable support for printk" if EXPERT |
74876a98 | 1417 | select IRQ_WORK |
d59745ce MM |
1418 | help |
1419 | This option enables normal printk support. Removing it | |
1420 | eliminates most of the message strings from the kernel image | |
1421 | and makes the kernel more or less silent. As this makes it | |
1422 | very difficult to diagnose system problems, saying N here is | |
1423 | strongly discouraged. | |
1424 | ||
42a0bb3f PM |
1425 | config PRINTK_NMI |
1426 | def_bool y | |
1427 | depends on PRINTK | |
1428 | depends on HAVE_NMI | |
1429 | ||
c8538a7a | 1430 | config BUG |
6a108a14 | 1431 | bool "BUG() support" if EXPERT |
c8538a7a MM |
1432 | default y |
1433 | help | |
1434 | Disabling this option eliminates support for BUG and WARN, reducing | |
1435 | the size of your kernel image and potentially quietly ignoring | |
1436 | numerous fatal conditions. You should only consider disabling this | |
1437 | option for embedded systems with no facilities for reporting errors. | |
1438 | Just say Y. | |
1439 | ||
708e9a79 | 1440 | config ELF_CORE |
046d662f | 1441 | depends on COREDUMP |
708e9a79 | 1442 | default y |
6a108a14 | 1443 | bool "Enable ELF core dumps" if EXPERT |
708e9a79 MM |
1444 | help |
1445 | Enable support for generating core dumps. Disabling saves about 4k. | |
1446 | ||
8761f1ab | 1447 | |
e5e1d3cb | 1448 | config PCSPKR_PLATFORM |
6a108a14 | 1449 | bool "Enable PC-Speaker support" if EXPERT |
8761f1ab | 1450 | depends on HAVE_PCSPKR_PLATFORM |
15f304b6 | 1451 | select I8253_LOCK |
e5e1d3cb SS |
1452 | default y |
1453 | help | |
1454 | This option allows to disable the internal PC-Speaker | |
1455 | support, saving some memory. | |
1456 | ||
1da177e4 LT |
1457 | config BASE_FULL |
1458 | default y | |
6a108a14 | 1459 | bool "Enable full-sized data structures for core" if EXPERT |
1da177e4 LT |
1460 | help |
1461 | Disabling this option reduces the size of miscellaneous core | |
1462 | kernel data structures. This saves memory on small machines, | |
1463 | but may reduce performance. | |
1464 | ||
1465 | config FUTEX | |
6a108a14 | 1466 | bool "Enable futex support" if EXPERT |
1da177e4 | 1467 | default y |
bc2eecd7 | 1468 | imply RT_MUTEXES |
1da177e4 LT |
1469 | help |
1470 | Disabling this option will cause the kernel to be built without | |
1471 | support for "fast userspace mutexes". The resulting kernel may not | |
1472 | run glibc-based applications correctly. | |
1473 | ||
bc2eecd7 NP |
1474 | config FUTEX_PI |
1475 | bool | |
1476 | depends on FUTEX && RT_MUTEXES | |
1477 | default y | |
1478 | ||
03b8c7b6 HC |
1479 | config HAVE_FUTEX_CMPXCHG |
1480 | bool | |
62b4d204 | 1481 | depends on FUTEX |
03b8c7b6 HC |
1482 | help |
1483 | Architectures should select this if futex_atomic_cmpxchg_inatomic() | |
1484 | is implemented and always working. This removes a couple of runtime | |
1485 | checks. | |
1486 | ||
1da177e4 | 1487 | config EPOLL |
6a108a14 | 1488 | bool "Enable eventpoll support" if EXPERT |
1da177e4 LT |
1489 | default y |
1490 | help | |
1491 | Disabling this option will cause the kernel to be built without | |
1492 | support for epoll family of system calls. | |
1493 | ||
fba2afaa | 1494 | config SIGNALFD |
6a108a14 | 1495 | bool "Enable signalfd() system call" if EXPERT |
fba2afaa DL |
1496 | default y |
1497 | help | |
1498 | Enable the signalfd() system call that allows to receive signals | |
1499 | on a file descriptor. | |
1500 | ||
1501 | If unsure, say Y. | |
1502 | ||
b215e283 | 1503 | config TIMERFD |
6a108a14 | 1504 | bool "Enable timerfd() system call" if EXPERT |
b215e283 DL |
1505 | default y |
1506 | help | |
1507 | Enable the timerfd() system call that allows to receive timer | |
1508 | events on a file descriptor. | |
1509 | ||
1510 | If unsure, say Y. | |
1511 | ||
e1ad7468 | 1512 | config EVENTFD |
6a108a14 | 1513 | bool "Enable eventfd() system call" if EXPERT |
e1ad7468 DL |
1514 | default y |
1515 | help | |
1516 | Enable the eventfd() system call that allows to receive both | |
1517 | kernel notification (ie. KAIO) or userspace notifications. | |
1518 | ||
1519 | If unsure, say Y. | |
1520 | ||
1da177e4 | 1521 | config SHMEM |
6a108a14 | 1522 | bool "Use full shmem filesystem" if EXPERT |
1da177e4 LT |
1523 | default y |
1524 | depends on MMU | |
1525 | help | |
1526 | The shmem is an internal filesystem used to manage shared memory. | |
1527 | It is backed by swap and manages resource limits. It is also exported | |
1528 | to userspace as tmpfs if TMPFS is enabled. Disabling this | |
1529 | option replaces shmem and tmpfs with the much simpler ramfs code, | |
1530 | which may be appropriate on small systems without swap. | |
1531 | ||
ebf3f09c | 1532 | config AIO |
6a108a14 | 1533 | bool "Enable AIO support" if EXPERT |
ebf3f09c TP |
1534 | default y |
1535 | help | |
1536 | This option enables POSIX asynchronous I/O which may by used | |
657a5209 MF |
1537 | by some high performance threaded applications. Disabling |
1538 | this option saves about 7k. | |
1539 | ||
2b188cc1 JA |
1540 | config IO_URING |
1541 | bool "Enable IO uring support" if EXPERT | |
1542 | select ANON_INODES | |
1543 | default y | |
1544 | help | |
1545 | This option enables support for the io_uring interface, enabling | |
1546 | applications to submit and complete IO through submission and | |
1547 | completion rings that are shared between the kernel and application. | |
1548 | ||
d3ac21ca JT |
1549 | config ADVISE_SYSCALLS |
1550 | bool "Enable madvise/fadvise syscalls" if EXPERT | |
1551 | default y | |
1552 | help | |
1553 | This option enables the madvise and fadvise syscalls, used by | |
1554 | applications to advise the kernel about their future memory or file | |
1555 | usage, improving performance. If building an embedded system where no | |
1556 | applications use these syscalls, you can disable this option to save | |
1557 | space. | |
1558 | ||
5b25b13a MD |
1559 | config MEMBARRIER |
1560 | bool "Enable membarrier() system call" if EXPERT | |
1561 | default y | |
1562 | help | |
1563 | Enable the membarrier() system call that allows issuing memory | |
1564 | barriers across all running threads, which can be used to distribute | |
1565 | the cost of user-space memory barriers asymmetrically by transforming | |
1566 | pairs of memory barriers into pairs consisting of membarrier() and a | |
1567 | compiler barrier. | |
1568 | ||
1569 | If unsure, say Y. | |
1570 | ||
d1b069f5 RD |
1571 | config KALLSYMS |
1572 | bool "Load all symbols for debugging/ksymoops" if EXPERT | |
1573 | default y | |
1574 | help | |
1575 | Say Y here to let the kernel print out symbolic crash information and | |
1576 | symbolic stack backtraces. This increases the size of the kernel | |
1577 | somewhat, as all symbols have to be loaded into the kernel image. | |
1578 | ||
1579 | config KALLSYMS_ALL | |
1580 | bool "Include all symbols in kallsyms" | |
1581 | depends on DEBUG_KERNEL && KALLSYMS | |
1582 | help | |
1583 | Normally kallsyms only contains the symbols of functions for nicer | |
1584 | OOPS messages and backtraces (i.e., symbols from the text and inittext | |
1585 | sections). This is sufficient for most cases. And only in very rare | |
1586 | cases (e.g., when a debugger is used) all symbols are required (e.g., | |
1587 | names of variables from the data sections, etc). | |
1588 | ||
1589 | This option makes sure that all symbols are loaded into the kernel | |
1590 | image (i.e., symbols from all sections) in cost of increased kernel | |
1591 | size (depending on the kernel configuration, it may be 300KiB or | |
1592 | something like this). | |
1593 | ||
1594 | Say N unless you really need all symbols. | |
1595 | ||
1596 | config KALLSYMS_ABSOLUTE_PERCPU | |
1597 | bool | |
1598 | depends on KALLSYMS | |
1599 | default X86_64 && SMP | |
1600 | ||
1601 | config KALLSYMS_BASE_RELATIVE | |
1602 | bool | |
1603 | depends on KALLSYMS | |
a687a533 | 1604 | default !IA64 |
d1b069f5 RD |
1605 | help |
1606 | Instead of emitting them as absolute values in the native word size, | |
1607 | emit the symbol references in the kallsyms table as 32-bit entries, | |
1608 | each containing a relative value in the range [base, base + U32_MAX] | |
1609 | or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either | |
1610 | an absolute value in the range [0, S32_MAX] or a relative value in the | |
1611 | range [base, base + S32_MAX], where base is the lowest relative symbol | |
1612 | address encountered in the image. | |
1613 | ||
1614 | On 64-bit builds, this reduces the size of the address table by 50%, | |
1615 | but more importantly, it results in entries whose values are build | |
1616 | time constants, and no relocation pass is required at runtime to fix | |
1617 | up the entries based on the runtime load address of the kernel. | |
1618 | ||
1619 | # end of the "standard kernel features (expert users)" menu | |
1620 | ||
1621 | # syscall, maps, verifier | |
1622 | config BPF_SYSCALL | |
1623 | bool "Enable bpf() system call" | |
d1b069f5 | 1624 | select BPF |
bae77c5e | 1625 | select IRQ_WORK |
d1b069f5 RD |
1626 | default n |
1627 | help | |
1628 | Enable the bpf() system call that allows to manipulate eBPF | |
1629 | programs and maps via file descriptors. | |
1630 | ||
290af866 AS |
1631 | config BPF_JIT_ALWAYS_ON |
1632 | bool "Permanently enable BPF JIT and remove BPF interpreter" | |
1633 | depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT | |
1634 | help | |
1635 | Enables BPF JIT and removes BPF interpreter to avoid | |
1636 | speculative execution of BPF instructions by the interpreter | |
1637 | ||
d1b069f5 RD |
1638 | config USERFAULTFD |
1639 | bool "Enable userfaultfd() system call" | |
d1b069f5 RD |
1640 | depends on MMU |
1641 | help | |
1642 | Enable the userfaultfd() system call that allows to intercept and | |
1643 | handle page faults in userland. | |
1644 | ||
3ccfebed MD |
1645 | config ARCH_HAS_MEMBARRIER_CALLBACKS |
1646 | bool | |
1647 | ||
70216e18 MD |
1648 | config ARCH_HAS_MEMBARRIER_SYNC_CORE |
1649 | bool | |
1650 | ||
d7822b1e MD |
1651 | config RSEQ |
1652 | bool "Enable rseq() system call" if EXPERT | |
1653 | default y | |
1654 | depends on HAVE_RSEQ | |
1655 | select MEMBARRIER | |
1656 | help | |
1657 | Enable the restartable sequences system call. It provides a | |
1658 | user-space cache for the current CPU number value, which | |
1659 | speeds up getting the current CPU number from user-space, | |
1660 | as well as an ABI to speed up user-space operations on | |
1661 | per-CPU data. | |
1662 | ||
1663 | If unsure, say Y. | |
1664 | ||
1665 | config DEBUG_RSEQ | |
1666 | default n | |
1667 | bool "Enabled debugging of rseq() system call" if EXPERT | |
1668 | depends on RSEQ && DEBUG_KERNEL | |
1669 | help | |
1670 | Enable extra debugging checks for the rseq system call. | |
1671 | ||
1672 | If unsure, say N. | |
1673 | ||
6befe5f6 RD |
1674 | config EMBEDDED |
1675 | bool "Embedded system" | |
5d2acfc7 | 1676 | option allnoconfig_y |
6befe5f6 RD |
1677 | select EXPERT |
1678 | help | |
1679 | This option should be enabled if compiling the kernel for | |
1680 | an embedded system so certain expert options are available | |
1681 | for configuration. | |
1682 | ||
cdd6c482 | 1683 | config HAVE_PERF_EVENTS |
0793a61d | 1684 | bool |
018df72d MF |
1685 | help |
1686 | See tools/perf/design.txt for details. | |
0793a61d | 1687 | |
906010b2 PZ |
1688 | config PERF_USE_VMALLOC |
1689 | bool | |
1690 | help | |
1691 | See tools/perf/design.txt for details | |
1692 | ||
ad90a3de | 1693 | config PC104 |
424529fb | 1694 | bool "PC/104 support" if EXPERT |
ad90a3de WBG |
1695 | help |
1696 | Expose PC/104 form factor device drivers and options available for | |
1697 | selection and configuration. Enable this option if your target | |
1698 | machine has a PC/104 bus. | |
1699 | ||
57c0c15b | 1700 | menu "Kernel Performance Events And Counters" |
0793a61d | 1701 | |
cdd6c482 | 1702 | config PERF_EVENTS |
57c0c15b | 1703 | bool "Kernel performance events and counters" |
392d65a9 | 1704 | default y if PROFILING |
cdd6c482 | 1705 | depends on HAVE_PERF_EVENTS |
e360adbe | 1706 | select IRQ_WORK |
83fe27ea | 1707 | select SRCU |
0793a61d | 1708 | help |
57c0c15b IM |
1709 | Enable kernel support for various performance events provided |
1710 | by software and hardware. | |
0793a61d | 1711 | |
dd77038d | 1712 | Software events are supported either built-in or via the |
57c0c15b | 1713 | use of generic tracepoints. |
0793a61d | 1714 | |
57c0c15b IM |
1715 | Most modern CPUs support performance events via performance |
1716 | counter registers. These registers count the number of certain | |
0793a61d TG |
1717 | types of hw events: such as instructions executed, cachemisses |
1718 | suffered, or branches mis-predicted - without slowing down the | |
1719 | kernel or applications. These registers can also trigger interrupts | |
1720 | when a threshold number of events have passed - and can thus be | |
1721 | used to profile the code that runs on that CPU. | |
1722 | ||
57c0c15b | 1723 | The Linux Performance Event subsystem provides an abstraction of |
dd77038d | 1724 | these software and hardware event capabilities, available via a |
57c0c15b | 1725 | system call and used by the "perf" utility in tools/perf/. It |
0793a61d TG |
1726 | provides per task and per CPU counters, and it provides event |
1727 | capabilities on top of those. | |
1728 | ||
1729 | Say Y if unsure. | |
1730 | ||
906010b2 PZ |
1731 | config DEBUG_PERF_USE_VMALLOC |
1732 | default n | |
1733 | bool "Debug: use vmalloc to back perf mmap() buffers" | |
cb307113 | 1734 | depends on PERF_EVENTS && DEBUG_KERNEL && !PPC |
906010b2 PZ |
1735 | select PERF_USE_VMALLOC |
1736 | help | |
1737 | Use vmalloc memory to back perf mmap() buffers. | |
1738 | ||
1739 | Mostly useful for debugging the vmalloc code on platforms | |
1740 | that don't require it. | |
1741 | ||
1742 | Say N if unsure. | |
1743 | ||
0793a61d TG |
1744 | endmenu |
1745 | ||
f8891e5e CL |
1746 | config VM_EVENT_COUNTERS |
1747 | default y | |
6a108a14 | 1748 | bool "Enable VM event counters for /proc/vmstat" if EXPERT |
f8891e5e | 1749 | help |
2aea4fb6 PJ |
1750 | VM event counters are needed for event counts to be shown. |
1751 | This option allows the disabling of the VM event counters | |
6a108a14 | 1752 | on EXPERT systems. /proc/vmstat will only show page counts |
2aea4fb6 | 1753 | if VM event counters are disabled. |
f8891e5e | 1754 | |
41ecc55b CL |
1755 | config SLUB_DEBUG |
1756 | default y | |
6a108a14 | 1757 | bool "Enable SLUB debugging support" if EXPERT |
f6acb635 | 1758 | depends on SLUB && SYSFS |
41ecc55b CL |
1759 | help |
1760 | SLUB has extensive debug support features. Disabling these can | |
1761 | result in significant savings in code size. This also disables | |
1762 | SLUB sysfs support. /sys/slab will not exist and there will be | |
1763 | no support for cache validation etc. | |
1764 | ||
1663f26d TH |
1765 | config SLUB_MEMCG_SYSFS_ON |
1766 | default n | |
1767 | bool "Enable memcg SLUB sysfs support by default" if EXPERT | |
1768 | depends on SLUB && SYSFS && MEMCG | |
1769 | help | |
1770 | SLUB creates a directory under /sys/kernel/slab for each | |
1771 | allocation cache to host info and debug files. If memory | |
1772 | cgroup is enabled, each cache can have per memory cgroup | |
1773 | caches. SLUB can create the same sysfs directories for these | |
1774 | caches under /sys/kernel/slab/CACHE/cgroup but it can lead | |
1775 | to a very high number of debug files being created. This is | |
1776 | controlled by slub_memcg_sysfs boot parameter and this | |
1777 | config option determines the parameter's default value. | |
1778 | ||
b943c460 RD |
1779 | config COMPAT_BRK |
1780 | bool "Disable heap randomization" | |
1781 | default y | |
1782 | help | |
1783 | Randomizing heap placement makes heap exploits harder, but it | |
1784 | also breaks ancient binaries (including anything libc5 based). | |
1785 | This option changes the bootup default to heap randomization | |
692105b8 | 1786 | disabled, and can be overridden at runtime by setting |
b943c460 RD |
1787 | /proc/sys/kernel/randomize_va_space to 2. |
1788 | ||
1789 | On non-ancient distros (post-2000 ones) N is usually a safe choice. | |
1790 | ||
81819f0f CL |
1791 | choice |
1792 | prompt "Choose SLAB allocator" | |
a0acd820 | 1793 | default SLUB |
81819f0f CL |
1794 | help |
1795 | This option allows to select a slab allocator. | |
1796 | ||
1797 | config SLAB | |
1798 | bool "SLAB" | |
04385fc5 | 1799 | select HAVE_HARDENED_USERCOPY_ALLOCATOR |
81819f0f CL |
1800 | help |
1801 | The regular slab allocator that is established and known to work | |
34013886 | 1802 | well in all environments. It organizes cache hot objects in |
02f56210 | 1803 | per cpu and per node queues. |
81819f0f CL |
1804 | |
1805 | config SLUB | |
81819f0f | 1806 | bool "SLUB (Unqueued Allocator)" |
ed18adc1 | 1807 | select HAVE_HARDENED_USERCOPY_ALLOCATOR |
81819f0f CL |
1808 | help |
1809 | SLUB is a slab allocator that minimizes cache line usage | |
1810 | instead of managing queues of cached objects (SLAB approach). | |
1811 | Per cpu caching is realized using slabs of objects instead | |
1812 | of queues of objects. SLUB can use memory efficiently | |
02f56210 SA |
1813 | and has enhanced diagnostics. SLUB is the default choice for |
1814 | a slab allocator. | |
81819f0f CL |
1815 | |
1816 | config SLOB | |
6a108a14 | 1817 | depends on EXPERT |
81819f0f CL |
1818 | bool "SLOB (Simple Allocator)" |
1819 | help | |
37291458 MM |
1820 | SLOB replaces the stock allocator with a drastically simpler |
1821 | allocator. SLOB is generally more space efficient but | |
1822 | does not perform as well on large systems. | |
81819f0f CL |
1823 | |
1824 | endchoice | |
1825 | ||
7660a6fd KC |
1826 | config SLAB_MERGE_DEFAULT |
1827 | bool "Allow slab caches to be merged" | |
1828 | default y | |
1829 | help | |
1830 | For reduced kernel memory fragmentation, slab caches can be | |
1831 | merged when they share the same size and other characteristics. | |
1832 | This carries a risk of kernel heap overflows being able to | |
1833 | overwrite objects from merged caches (and more easily control | |
1834 | cache layout), which makes such heap attacks easier to exploit | |
1835 | by attackers. By keeping caches unmerged, these kinds of exploits | |
1836 | can usually only damage objects in the same cache. To disable | |
1837 | merging at runtime, "slab_nomerge" can be passed on the kernel | |
1838 | command line. | |
1839 | ||
c7ce4f60 TG |
1840 | config SLAB_FREELIST_RANDOM |
1841 | default n | |
210e7a43 | 1842 | depends on SLAB || SLUB |
c7ce4f60 TG |
1843 | bool "SLAB freelist randomization" |
1844 | help | |
210e7a43 | 1845 | Randomizes the freelist order used on creating new pages. This |
c7ce4f60 TG |
1846 | security feature reduces the predictability of the kernel slab |
1847 | allocator against heap overflows. | |
1848 | ||
2482ddec KC |
1849 | config SLAB_FREELIST_HARDENED |
1850 | bool "Harden slab freelist metadata" | |
1851 | depends on SLUB | |
1852 | help | |
1853 | Many kernel heap attacks try to target slab cache metadata and | |
1854 | other infrastructure. This options makes minor performance | |
92bae787 | 1855 | sacrifices to harden the kernel slab allocator against common |
2482ddec KC |
1856 | freelist exploit methods. |
1857 | ||
e900a918 DW |
1858 | config SHUFFLE_PAGE_ALLOCATOR |
1859 | bool "Page allocator randomization" | |
1860 | default SLAB_FREELIST_RANDOM && ACPI_NUMA | |
1861 | help | |
1862 | Randomization of the page allocator improves the average | |
1863 | utilization of a direct-mapped memory-side-cache. See section | |
1864 | 5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI | |
1865 | 6.2a specification for an example of how a platform advertises | |
1866 | the presence of a memory-side-cache. There are also incidental | |
1867 | security benefits as it reduces the predictability of page | |
1868 | allocations to compliment SLAB_FREELIST_RANDOM, but the | |
1869 | default granularity of shuffling on the "MAX_ORDER - 1" i.e, | |
1870 | 10th order of pages is selected based on cache utilization | |
1871 | benefits on x86. | |
1872 | ||
1873 | While the randomization improves cache utilization it may | |
1874 | negatively impact workloads on platforms without a cache. For | |
1875 | this reason, by default, the randomization is enabled only | |
1876 | after runtime detection of a direct-mapped memory-side-cache. | |
1877 | Otherwise, the randomization may be force enabled with the | |
1878 | 'page_alloc.shuffle' kernel command line parameter. | |
1879 | ||
1880 | Say Y if unsure. | |
1881 | ||
345c905d JK |
1882 | config SLUB_CPU_PARTIAL |
1883 | default y | |
b39ffbf8 | 1884 | depends on SLUB && SMP |
345c905d JK |
1885 | bool "SLUB per cpu partial cache" |
1886 | help | |
92bae787 | 1887 | Per cpu partial caches accelerate objects allocation and freeing |
345c905d JK |
1888 | that is local to a processor at the price of more indeterminism |
1889 | in the latency of the free. On overflow these caches will be cleared | |
1890 | which requires the taking of locks that may cause latency spikes. | |
1891 | Typically one would choose no for a realtime system. | |
1892 | ||
ea637639 JZ |
1893 | config MMAP_ALLOW_UNINITIALIZED |
1894 | bool "Allow mmapped anonymous memory to be uninitialized" | |
6a108a14 | 1895 | depends on EXPERT && !MMU |
ea637639 JZ |
1896 | default n |
1897 | help | |
1898 | Normally, and according to the Linux spec, anonymous memory obtained | |
3903bf94 | 1899 | from mmap() has its contents cleared before it is passed to |
ea637639 JZ |
1900 | userspace. Enabling this config option allows you to request that |
1901 | mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus | |
1902 | providing a huge performance boost. If this option is not enabled, | |
1903 | then the flag will be ignored. | |
1904 | ||
1905 | This is taken advantage of by uClibc's malloc(), and also by | |
1906 | ELF-FDPIC binfmt's brk and stack allocator. | |
1907 | ||
1908 | Because of the obvious security issues, this option should only be | |
1909 | enabled on embedded devices where you control what is run in | |
1910 | userspace. Since that isn't generally a problem on no-MMU systems, | |
1911 | it is normally safe to say Y here. | |
1912 | ||
1913 | See Documentation/nommu-mmap.txt for more information. | |
1914 | ||
091f6e26 DH |
1915 | config SYSTEM_DATA_VERIFICATION |
1916 | def_bool n | |
1917 | select SYSTEM_TRUSTED_KEYRING | |
1918 | select KEYS | |
1919 | select CRYPTO | |
d43de6c7 | 1920 | select CRYPTO_RSA |
091f6e26 DH |
1921 | select ASYMMETRIC_KEY_TYPE |
1922 | select ASYMMETRIC_PUBLIC_KEY_SUBTYPE | |
091f6e26 DH |
1923 | select ASN1 |
1924 | select OID_REGISTRY | |
1925 | select X509_CERTIFICATE_PARSER | |
1926 | select PKCS7_MESSAGE_PARSER | |
82c04ff8 | 1927 | help |
091f6e26 DH |
1928 | Provide PKCS#7 message verification using the contents of the system |
1929 | trusted keyring to provide public keys. This then can be used for | |
1930 | module verification, kexec image verification and firmware blob | |
1931 | verification. | |
82c04ff8 | 1932 | |
125e5645 | 1933 | config PROFILING |
b309a294 | 1934 | bool "Profiling support" |
125e5645 MD |
1935 | help |
1936 | Say Y here to enable the extended profiling support mechanisms used | |
1937 | by profilers such as OProfile. | |
1938 | ||
5f87f112 IM |
1939 | # |
1940 | # Place an empty function call at each tracepoint site. Can be | |
1941 | # dynamically changed for a probe function. | |
1942 | # | |
97e1c18e | 1943 | config TRACEPOINTS |
5f87f112 | 1944 | bool |
97e1c18e | 1945 | |
1da177e4 LT |
1946 | endmenu # General setup |
1947 | ||
1572497c CH |
1948 | source "arch/Kconfig" |
1949 | ||
ae81f9e3 | 1950 | config RT_MUTEXES |
6341e62b | 1951 | bool |
ae81f9e3 | 1952 | |
1da177e4 LT |
1953 | config BASE_SMALL |
1954 | int | |
1955 | default 0 if BASE_FULL | |
1956 | default 1 if !BASE_FULL | |
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 | ||
56067812 AB |
2017 | config MODULE_REL_CRCS |
2018 | bool | |
2019 | depends on MODVERSIONS | |
2020 | ||
1da177e4 LT |
2021 | config MODULE_SRCVERSION_ALL |
2022 | bool "Source checksum for all modules" | |
1da177e4 LT |
2023 | help |
2024 | Modules which contain a MODULE_VERSION get an extra "srcversion" | |
2025 | field inserted into their modinfo section, which contains a | |
2026 | sum of the source files which made it. This helps maintainers | |
2027 | see exactly which source was used to build a module (since | |
2028 | others sometimes change the module source without updating | |
2029 | the version). With this option, such a "srcversion" field | |
2030 | will be created for all modules. If unsure, say N. | |
2031 | ||
106a4ee2 RR |
2032 | config MODULE_SIG |
2033 | bool "Module signature verification" | |
2034 | depends on MODULES | |
091f6e26 | 2035 | select SYSTEM_DATA_VERIFICATION |
106a4ee2 RR |
2036 | help |
2037 | Check modules for valid signatures upon load: the signature | |
2038 | is simply appended to the module. For more information see | |
cbdc8217 | 2039 | <file:Documentation/admin-guide/module-signing.rst>. |
106a4ee2 | 2040 | |
228c37ff DH |
2041 | Note that this option adds the OpenSSL development packages as a |
2042 | kernel build dependency so that the signing tool can use its crypto | |
2043 | library. | |
2044 | ||
ea0b6dcf DH |
2045 | !!!WARNING!!! If you enable this option, you MUST make sure that the |
2046 | module DOES NOT get stripped after being signed. This includes the | |
2047 | debuginfo strip done by some packagers (such as rpmbuild) and | |
2048 | inclusion into an initramfs that wants the module size reduced. | |
2049 | ||
106a4ee2 RR |
2050 | config MODULE_SIG_FORCE |
2051 | bool "Require modules to be validly signed" | |
2052 | depends on MODULE_SIG | |
2053 | help | |
2054 | Reject unsigned modules or signed modules for which we don't have a | |
2055 | key. Without this, such modules will simply taint the kernel. | |
ea0b6dcf | 2056 | |
d9d8d7ed MM |
2057 | config MODULE_SIG_ALL |
2058 | bool "Automatically sign all modules" | |
2059 | default y | |
2060 | depends on MODULE_SIG | |
2061 | help | |
2062 | Sign all modules during make modules_install. Without this option, | |
2063 | modules must be signed manually, using the scripts/sign-file tool. | |
2064 | ||
2065 | comment "Do not forget to sign required modules with scripts/sign-file" | |
2066 | depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL | |
2067 | ||
ea0b6dcf DH |
2068 | choice |
2069 | prompt "Which hash algorithm should modules be signed with?" | |
2070 | depends on MODULE_SIG | |
2071 | help | |
2072 | This determines which sort of hashing algorithm will be used during | |
2073 | signature generation. This algorithm _must_ be built into the kernel | |
2074 | directly so that signature verification can take place. It is not | |
2075 | possible to load a signed module containing the algorithm to check | |
2076 | the signature on that module. | |
2077 | ||
2078 | config MODULE_SIG_SHA1 | |
2079 | bool "Sign modules with SHA-1" | |
2080 | select CRYPTO_SHA1 | |
2081 | ||
2082 | config MODULE_SIG_SHA224 | |
2083 | bool "Sign modules with SHA-224" | |
2084 | select CRYPTO_SHA256 | |
2085 | ||
2086 | config MODULE_SIG_SHA256 | |
2087 | bool "Sign modules with SHA-256" | |
2088 | select CRYPTO_SHA256 | |
2089 | ||
2090 | config MODULE_SIG_SHA384 | |
2091 | bool "Sign modules with SHA-384" | |
2092 | select CRYPTO_SHA512 | |
2093 | ||
2094 | config MODULE_SIG_SHA512 | |
2095 | bool "Sign modules with SHA-512" | |
2096 | select CRYPTO_SHA512 | |
2097 | ||
2098 | endchoice | |
2099 | ||
22753674 MM |
2100 | config MODULE_SIG_HASH |
2101 | string | |
2102 | depends on MODULE_SIG | |
2103 | default "sha1" if MODULE_SIG_SHA1 | |
2104 | default "sha224" if MODULE_SIG_SHA224 | |
2105 | default "sha256" if MODULE_SIG_SHA256 | |
2106 | default "sha384" if MODULE_SIG_SHA384 | |
2107 | default "sha512" if MODULE_SIG_SHA512 | |
2108 | ||
beb50df3 BJ |
2109 | config MODULE_COMPRESS |
2110 | bool "Compress modules on installation" | |
2111 | depends on MODULES | |
2112 | help | |
beb50df3 | 2113 | |
b6c09b51 RR |
2114 | Compresses kernel modules when 'make modules_install' is run; gzip or |
2115 | xz depending on "Compression algorithm" below. | |
beb50df3 | 2116 | |
b6c09b51 | 2117 | module-init-tools MAY support gzip, and kmod MAY support gzip and xz. |
beb50df3 | 2118 | |
b6c09b51 RR |
2119 | Out-of-tree kernel modules installed using Kbuild will also be |
2120 | compressed upon installation. | |
beb50df3 | 2121 | |
b6c09b51 RR |
2122 | Note: for modules inside an initrd or initramfs, it's more efficient |
2123 | to compress the whole initrd or initramfs instead. | |
beb50df3 | 2124 | |
b6c09b51 RR |
2125 | Note: This is fully compatible with signed modules. |
2126 | ||
2127 | If in doubt, say N. | |
beb50df3 BJ |
2128 | |
2129 | choice | |
2130 | prompt "Compression algorithm" | |
2131 | depends on MODULE_COMPRESS | |
2132 | default MODULE_COMPRESS_GZIP | |
2133 | help | |
2134 | This determines which sort of compression will be used during | |
2135 | 'make modules_install'. | |
2136 | ||
2137 | GZIP (default) and XZ are supported. | |
2138 | ||
2139 | config MODULE_COMPRESS_GZIP | |
2140 | bool "GZIP" | |
2141 | ||
2142 | config MODULE_COMPRESS_XZ | |
2143 | bool "XZ" | |
2144 | ||
2145 | endchoice | |
2146 | ||
dbacb0ef NP |
2147 | config TRIM_UNUSED_KSYMS |
2148 | bool "Trim unused exported kernel symbols" | |
2149 | depends on MODULES && !UNUSED_SYMBOLS | |
2150 | help | |
2151 | The kernel and some modules make many symbols available for | |
2152 | other modules to use via EXPORT_SYMBOL() and variants. Depending | |
2153 | on the set of modules being selected in your kernel configuration, | |
2154 | many of those exported symbols might never be used. | |
2155 | ||
2156 | This option allows for unused exported symbols to be dropped from | |
2157 | the build. In turn, this provides the compiler more opportunities | |
2158 | (especially when using LTO) for optimizing the code and reducing | |
2159 | binary size. This might have some security advantages as well. | |
2160 | ||
f1cb637e | 2161 | If unsure, or if you need to build out-of-tree modules, say N. |
dbacb0ef | 2162 | |
0b0de144 RD |
2163 | endif # MODULES |
2164 | ||
6c9692e2 PZ |
2165 | config MODULES_TREE_LOOKUP |
2166 | def_bool y | |
2167 | depends on PERF_EVENTS || TRACING | |
2168 | ||
98a79d6a RR |
2169 | config INIT_ALL_POSSIBLE |
2170 | bool | |
2171 | help | |
5f054e31 RR |
2172 | Back when each arch used to define their own cpu_online_mask and |
2173 | cpu_possible_mask, some of them chose to initialize cpu_possible_mask | |
98a79d6a RR |
2174 | with all 1s, and others with all 0s. When they were centralised, |
2175 | it was better to provide this option than to break all the archs | |
692105b8 | 2176 | and have several arch maintainers pursuing me down dark alleys. |
98a79d6a | 2177 | |
3a65dfe8 | 2178 | source "block/Kconfig" |
e98c3202 AK |
2179 | |
2180 | config PREEMPT_NOTIFIERS | |
2181 | bool | |
e260be67 | 2182 | |
16295bec SK |
2183 | config PADATA |
2184 | depends on SMP | |
2185 | bool | |
2186 | ||
4520c6a4 DH |
2187 | config ASN1 |
2188 | tristate | |
2189 | help | |
2190 | Build a simple ASN.1 grammar compiler that produces a bytecode output | |
2191 | that can be interpreted by the ASN.1 stream decoder and used to | |
2192 | inform it as to what tags are to be expected in a stream and what | |
2193 | functions to call on what tags. | |
2194 | ||
6beb0009 | 2195 | source "kernel/Kconfig.locks" |
e61938a9 MD |
2196 | |
2197 | config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE | |
2198 | bool | |
1bd21c6c DB |
2199 | |
2200 | # It may be useful for an architecture to override the definitions of the | |
7303e30e DB |
2201 | # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h> |
2202 | # and the COMPAT_ variants in <linux/compat.h>, in particular to use a | |
2203 | # different calling convention for syscalls. They can also override the | |
2204 | # macros for not-implemented syscalls in kernel/sys_ni.c and | |
2205 | # kernel/time/posix-stubs.c. All these overrides need to be available in | |
2206 | # <asm/syscall_wrapper.h>. | |
1bd21c6c DB |
2207 | config ARCH_HAS_SYSCALL_WRAPPER |
2208 | def_bool n |